To see the other types of publications on this topic, follow the link: Compressive test.
Dissertations / Theses on the topic 'Compressive test'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Compressive test.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Ulker, Elcin. "Comparison Of Compressive Strength Test Procedures For Blended Cements." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612506/index.pdf.
Full textAbstract:
The aim of this thesis is to twofold, in order to demonstrate the variabilities that can be faced within the compressive strength of blended cements, one blended cement namely CEM IV / B (P-V) 32.5N is selected and the 28-day compressive strength is obtained by 16 different laboratories following TS EN 196-1 standard. Later, to show the variabilities that could be faced by different standards, three different cement types were selected and their compressive strengths are determined following two procedures first with TS EN 196-1, later with similar procedure described in ASTM.
The strength of cement is determined by TS EN 196-1 in Turkey that is the same for all types of cements. However, American cement producers use different standards for testing the strength of Portland cement and blended cements. The main difference is the amount of water utilized in producing the cement mortar.
It was observed that for Portland and Portland composite cementsthere is not any significant difference in between the compressive strength results of cement mortars prepared by both methods. However, for pozzolanic cements, there is much deviance in the compressive strength results of cement mortars prepared by TS EN 196-1.
2
McCamey, Morgan R. "Deep Learning for Compressive SAR Imaging with Train-Test Discrepancy." Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1624266549100904.
Full text
3
Neumann, Karoline Mali. "Probabilistic Design of Midship Panel based on Model scale compressive Ice Test." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22958.
Full textAbstract:
This thesis is investigating compressive ice loads acting on the mid-ship using a model experiment performed in Aalto ice tank where atactile sensor was mounted on the side. In order to get insight in thevery complex behavior of ice; the sea ice growth, mechanical prop-erties and failure mechanisms are presented. Further some previouswork on the topic is presented, with discussion, in addition to regula-tions on local ice loads and structure requirements. The execution ofthe experiment is described, and the method for processing the dataand based on this data using probabilistic design to design a midshippanel. For datasets where the interaction area is semi-continuous anew event denition is proposed, based on temporal events consistingof spatial events. The maximum event method developed by [Jordaanet al., 1993] is applied in sampling data from the new temporal events.Data is sampled for increasing area sizes corresponding to number ofconnected triggered censor cells. The data is adjusted for exposure inorder to have a standardized curve corresponding to the area in ques-tion. An exponential distribution is tted to the tail of the data, andpresented in a Weibull probability plot. The parameters of the distri-butions, x0 and are functions of area. Assuming the area is acting ina line corresponding to the span of a longitudinally framed panel, andgiven a return period and a scenario, a design load is predicted. Basedon this load, scantlings of a panel is recommended which also complieswith Finnish-Swedish ice class rules. The integrity of the structure ischecked using Monte Carlo analysis. To get more insight into the dataset, a local pressure area curve, and an average pressure over totalmeasured contact area relationship is presented for the entire data set,as well as spatial and process pressure area curves and pressure historyfor the biggest load event and the biggest pressure event.
4
Moffett, Theodore James. "Relationship Between Compressive Strength of Different Shape and Thickness Specimens of Type S Mortar." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/8811.
Full textAbstract:
Mortar is the cementitious binding material placed between masonry blocks to create a composite system. The American Society of Testing and Materials (ASTM), along with other organizations, have established the testing of prismatic mortar specimens for evaluating mechanical properties, like compressive strength. Mortar joints, however, possess vastly different characteristics compared to prismatic specimens, especially in terms of geometry and water content. These differences prevent a direct comparison of compressive strength between prismatic specimens and actual mortar joints in the assembly. The objective of this study was to analyze Type S mortar joints, with particular emphasis on specimen shape and water content, to draw accurate comparisons of compressive strength to ASTM prescribed mortar prismatic specimens.To examine the effect of water on mortar compressive strength, three different water contents were evaluated across nearly all testing series. Cubic (2-in) and cylindrical (2 by 4-in) mortar specimens were prepared and tested according to ASTM guidelines to verify the compressive strength relationship described by ASTM and to be used as comparative data. In addition, a small masonry wall was assembled and cured in a laboratory to simulate true properties of mortar joints. Mortar joints subjected to testing were a combination of thin slices cut from prismatic specimens as well as in-place bed joints cured between concrete masonry units (CMU). Two unorthodox test methods, the double punch test (DPT) and helix pull-out test (HPT), were selected as methods for assessing mortar joints. In addition, confining effects from neighboring material common to DPT were evaluated as a function of specimen face dimensions. The compressive strength ratio obtained through testing of 2-in cubic and 2 by 4-in cylindrical specimens was lower than ASTM recommendations. This may have been in part due to testing cylindrical specimens with rough surfaces and no capping material. DPT confinement on 2-in square and 2-in diameter circular specimens was found to be equivalent. Thinly sliced specimens tested in DPT showed increases in compressive strength as water content and specimen thickness decreased. As a whole, DPT results on thin mortar slices showed promise for accurate comparison to prismatic mortar specimens. In-place mortar joints tested in HPT showed moderate to high scatter. In addition, evaluation via HPT was determined to be more appropriate for qualitative rather than quantitative assessments of in-situ mortar.
5
Jones, John David. "Evaluation of the MD shear test method as a criterion for predicting box compressive strength." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/8620.
Full textAbstract:
Includes bibliographical references (leaves 145-149).Corrugated board is a composite sandwich type material used in the packaging industry worldwide. In the design of corrugated boxes, the stacking strength is an important design parameter. Current research shows that box failure is influenced by the flexural rigidities of the panel and its transverse shear rigidities. McKinlay proposed a new method to measure the MD transverse shear stiffness of corrugated board. This research was aimed at designing a fixture to perform the MD shear test and to evaluate its performance. In addition, the properties that influence box strength were to be investigated. These properties were then to be used in improved box strength predictions. It was found that the designed MD shear fixture was able to measure the transverse shear stiffness of corrugated board in the MD direction with a high degree of accuracy and reproducibility. This method was much easier to perform than the standard block shear test method and also much quicker. This was a very important factor considering the application of this testing method in a research and development environment. In addition, the stiffness test exhibited good possibilities for use as a quality control tool. Extensive testing showed that the material used in the manufacture of corrugated board had a strong influence on board and box strength. In addition, it was found that the separation of the faces in a corrugated board structure had an influence on the strength and stability of the box. Factors such as the manufacturing process and board structure were also found to have an effect on box strength. Box strength predictions were performed using the methods available in the literature. These predictions had good correlation with the experimental box compression values. It was shown that box strength can be accurately predicted from liner and fluting properties and this capability is an important tool in box strength design.
6
Reynolds, Michael Scott. "A Relationship Between the Strengths of Type N Cubic Mortar Specimens and In-Situ Mortar." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7572.
Full textAbstract:
The compressive strength of mortar is typically determined using the American Societyfor Testing and Materials (ASTM) standard method using 2 inch cubes which are compressed tillfailure. There is however a disparity between the compressive strengths of mortar cubes, and insitumortar. This disparity is a result of the differences in thickness, aspect ratio, curingconditions, water content, and confinement between mortar cubes and mortar joints. While thesedifferences lead to mortar joints being stronger than mortar cubes, a relationship between theirstrengths is desired.Two less-common mortar strength tests were used to determine more accurately thecompressive strength of in-situ mortar. The results of both tests were compared to the results ofASTM standard compressive testing with mortars of the same water content. The first was theDouble Punch test which involves the use of two metal punches that compress either side of athin mortar sample till failure. The Double Punch test is more difficult to perform than theASTM standard compression test, but was useful because it simulates the confinement that insitumortar will experience. The Double Punch test was also used with mortar specimens ofvarying thickness to determine a relationship between specimen thickness and compressivestrength. The second test used was the Helix Pullout test. This test is performed by insertingmetal helical screws into a mortar joint, and pulling from the joint while restricting rotation. Themaximum load used to extract the Helix is recorded as the Pullout Load, and is used to find thecompressive strength by use of a calibration curve. This test was used on a masonry wall paneland mortar cubes were also made with the same mortar for compressive testing.The tested mortar exhibited decreased compressive strength with increased water content.The mortar also decreased in strength with increasing specimen thickness. Mortar joints wereshown to be significantly stronger than mortar cubes based on factors of specimen thickness andconfinement by an average factor of at least 2.40. Although results are affected by punchdiameter, the Double Punch test was shown to be a consistent and reliable means of estimatingmortar compressive strength. The Helix Pullout test exhibited wide variation, and wasdetermined to be primarily useful for qualitative comparison as opposed to quantitativedetermination of strength.
7
Dean, Maureen A. "Predictions of Distal Radius Compressive Strength by Measurements of Bone Mineral and Stiffness." Ohio University Art and Sciences Honors Theses / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ouashonors1461595642.
Full text
8
Crook, Amy Lyn. "Assessment of the Tube Suction Test for Identifying Non-Frost-Susceptible Soils Stabilized with Cement." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/804.
Full textAbstract:
Frost heave is a primary mechanism of pavement distress in cold regions. The distress exhibited is dependent on the frost susceptibility of the soil within the depth of frost penetration, the availability of subsurface water, and the duration of freezing surface temperatures. Cement stabilization is one technique used to mitigate the effects of frost heave. The tube suction test (TST) is one possible method for determining the frost susceptibility of soils in the laboratory. The purpose of this research was to assess the utility of the TST for identifying non-frost-susceptible (NFS) materials stabilized with cement. This research investigated two aggregate base materials from Alaska that have exhibited negligible frost susceptibility in the field. The unconfined compressive strength (UCS), final dielectric value in the TST, and frost heave at three levels of cement treatment and in the untreated condition were evaluated for both materials. The data collected in this research indicate that, for the two known NFS materials included in this study, the TST is a good indicator of frost heave behavior. The total heave of the untreated materials was approximately 0.15 in. at the conclusion of the 10-day freezing period, which classifies these materials as NFS according to the U.S Army Corp of Engineers. Both materials had final dielectric values of less than 10 in the TST, indicating a superior moisture susceptibility rating. The results of this research suggest that the TST should be considered for identifying NFS materials, including those stabilized with cement. Additional testing should be performed on known NFS materials stabilized with cement and other additives to further assess the validity of using the TST to differentiate between frost-susceptible and NFS materials. Consistent with previous studies, this research indicates that, once a sufficient amount of cement has been added to significantly reduce frost heave, additional cement has only a marginal effect on further reduction. Therefore, to avoid unnecessary expense in construction, the minimum cement content required for preventing frost heave should be identified through laboratory testing and specified by the engineer. In this work, UCS values ranging between 200 psi and 400 psi after a 7-day cure were typically associated with this minimum cement content. Because the scope of this research is limited to two aggregate base materials, further testing is also necessary to validate this finding.
9
Cunto, Flávio José Craveiro. "Determinação do módulo de resiliência através de ensaios triaxiais dinâmicos e a sua estimativa a partir de ensaios de compressão simples: estudo de três solos do nordeste brasileiro." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/18/18137/tde-28022018-142425/.
Full textAbstract:
O módulo de resiliência é um parâmetro de crucial importância nas análises mecanísticas que envolvem a estimativa das tensões e deformações na estrutura do pavimento e no seu subleito, quando da ação do tráfego. Embora ensaios de campo possam ser empregados para se determinar o MR, a grande maioria das pesquisas nesse sentido são desenvolvidas em laboratório, onde é possível um maior controle das condições da amostra, dos sistemas de aplicação de carregamento e de medida dos deslocamentos. Entretanto, os ensaios em laboratório que visam à determinação do MR ainda são considerados especiais e exigem equipamentos relativamente complexos, ensejando portanto, pesquisas com a finalidade de se obter expressões que estimem o MR a partir de parâmetros advindos de ensaios mais simples e rotineiros. Neste trabalho foram realizados ensaios triaxiais dinâmicos para a determinação do módulo de resiliência de três solos empregados em rodovias do nordeste brasileiro. Através dos resultados de laboratório, verificou-se o desempenho dos modelos mais comumente empregados para se representar a variação do módulo de resiliência em função do estado de tensão. Observou-se para os três solos desta pesquisa, que o MR foi mais influenciado, quanto ao estado de tensão, pela tensão de confinamento e pela tensão principal maior. Analisou-se, por fim, a existência de uma expressão matemática entre o módulo de resiliência obtido a partir dos ensaios triaxiais dinâmicos e o módulo tangente inicial proveniente de ensaios de compressão simples, sob diversos níveis de tensão. Os resultados mostram que este tipo de associação é promissora, mas exige-se que o universo de solos estudados seja ampliado para que se estabeleça uma inferência decisiva.Resilient modulus is a crucial parameter in mechanistic analysis involving the estimation of stress and strains under the pavement structure subjected to traffic loading. While field tests can be used to determine the dynamic behavior of soils, most researches favor laboratory tests. Such preference is based on the fact that laboratory tests are less constrained because of their carefully controlled conditions. Unfortunately these tests are still unusual due to relative complex equipment, therefore researches involving the correlation of resilient modulus from repeated load triaxial tests with other test results is needed. In this work, repeated load triaxial tests were performed on three soils used in northeastern Brazilian roadways to estimate the resilient modulus. The performance of the models most commonly adopted to represent resilient modulus as a function of state of stress were verified. lt was observed for the three soils in this research, that confining stress and principal major stress influenced resilient moduli values. Predictive equations correlating the resilient modulus from repeated load triaxial tests and parameters from compressive strength tests, considering different states of stress were investigated. lt was shown that this type of empirical correlation presented satisfactory results, although incisive conclusions can\'t be drawn without a wider number and variety of soils.
10
Lundgren, Daniel, and Michael Persson. "Kvalitetsprovning av låskulor till hydrauliska snabbkopplingar." Thesis, Högskolan i Skövde, Institutionen för teknik och samhälle, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-6053.
Full textAbstract:
Ett företag som tillverkar hydrauliska snabbkopplingar har genom regelbundna kvalitetsprover upptäckt att vissa låskulor till snabbkopplingarnas låsmekanism plötsligt fått en bristande kvalité och spricker vid belastning. Låskulorna är gjorda av rostfritt stål och har en viktig funktion i låsmekanismen. Om de spricker vid användning kan det leda till konsekvenser med materiella skador eller personskador. Företaget vill förekomma eventuella kvalitetsproblem och måste därför säkerställa att låskulorna har rätt hållfasthet. Låskulorna köps in från en underleverantör och företaget vill därför utveckla en provmetod som provar låskulornas materialegenskaper när de levereras till fabriken. Arbetet i denna rapport syftar till att hjälpa företaget utveckla en sådan provmetod. Ett första steg är att undersöka orsaken till att låskulorna spricker. Materialanalyser utförs av ett materiallaboratorium för att fastställa vilka faktorer i materialet som orsakar brott i låskulorna. Analyserna visar att låskulorna sannolikt spricker på grund av en ökad sprödhet i materialet. Sprödheten beror på att martensiten i materialet är dåligt anlöpt samt en stor mängd karbider. Med orsaken till sprickorna fastställd undersöks befintliga metoder för materialprovning. En provmetod måste prova materialet i färdigtillverkade låskulor eftersom låskulornas tillverkningsprocess påverkar materialegenskaperna. Många av de standardiserade provmetoderna är dock svåra att tillämpa på låskulorna med anledning av låskulornas geometri och små dimensioner. En form av slagprov och pressprov utförs på låskulorna. Ett av syftena med proven är att undersöka om de är lämpliga att använda som provmetod. Genom proven framträder olika materialegenskaper för olika låskulor. Resultaten är dock inte jämförbara låskulorna emellan och proven anses inte vara lämpliga som provmetod. Även ett utmattningsprov utförs på låskulorna genom en upprepande belastning i en snabbkoppling. Detta prov är inte heller lämpligt att använda som provmetod då provet är mycket tidskrävande samt att det finns vissa osäkerheter kring provresultatet. I detta arbete undersöks även två nyligen framtagna provmetoder för kulor till kullager och möjligheten att tillämpa dessa provmetoder på låskulorna. I undersökningen jämförs de båda provmetoderna med avseende på utförande samt framtagning av provkropp. Även en spänningsanalys av en låskula belastad i en snabbkoppling utförs för att ta reda på i vilket område av låskulan de maximala spänningarna uppstår. Undersökningen ger att enbart en provmetod är intressant för fortsatt arbete. Den provmetod som föreslås i detta arbete kallas "the notched ball test" (NBT). Provmetoden innebär att en djup och smal skåra bearbetas i en låskula som sedan belastas med en tryckande kraft vinkelrätt mot skåran tills brott uppstår. Den maximala spänningen som verkar vid brottet beräknas med en enkel ekvation och används som mått för låskulans hållfasthet. Provmetoden är lämplig då den går att utföra med befintlig utrustning på företaget, den provar materialet i färdigtillverkade låskulor samt i samma område som de maximala spänningarna i en låskula belastad i en snabbkoppling uppstår. NBT nyttjar även dragspänningar vilket är fördelaktigt när sprödhet ska upptäckas i ett material. För att fastställa hur olika materialegenskaper samt geometrier för provkroppen påverkar provresultaten utförs en djupare analys av provmetoden. Analysen ger även vilka geometrier som bör användas vid utförandet av NBT samt värdet för den konstant som används vid beräkning av brottspänningen. Praktiska prov av NBT utförs inte i detta arbete men rapporten innefattar slutsatser om provmetoden och rekommendationer till företaget hur ett fortsatt arbete med NBT kan utföras.A company that manufactures hydraulic quick-couplings has discovered through regular quality checks that the quality of some of the locking balls for the locking mechanism in the quick couplings suddenly has become insufficient and the locking balls rupture under load. The locking balls are made of stainless steel and if they rupture during usage the consequences can be material damage or even personal injury. The company wants to prevent any quality problems and must therefore ensure that the strength of the locking balls is sufficient. The locking balls are purchased from a subcontractor and the company would therefore like to develop a method for strength testing locking balls delivered to the factory. This thesis aims to help the company in developing such a method. A first step is to investigate the cause of the locking balls rupture. Material analyses are executed by a material laboratory in order to determine what features in the material that causes the ruptures. The analyses shows that rupture is probably caused by an increased brittleness in the material and the brittleness is a consequence of less tempered martensite and a high amount of carbides. With the cause of rupture determined, existing methods for testing material properties is studied. It is important that strength testing is carried out with test specimens prepared from the actual locking balls. Otherwise the influence of the locking balls manufacturing process on the material properties is not taking into account. Many of the standardized methods for testing material properties, however, are hard to apply to the locking balls due to the geometry and small dimensions of the locking balls. A kind of impact test and compression test is performed. One of the purposes with the tests is to investigate if they are adequate for strength testing the locking balls. The results of the tests, however, are not suitable for comparison. Also, a fatigue test of the locking balls is performed by a repetitive loading of a quick coupling. The fatigue test is, however, time consuming and there are uncertainties in the test results. None of these tests is considered suitable as a strength testing method. In this thesis, two recently developed methods for strength testing ceramic balls and the possibility to apply these methods on the locking balls is studied. The study includes an analysis of the stress distribution in a locking ball under load to determine in which region the highest stresses occur. The study provides that only one of the methods is suitable for the locking balls due to differences in preparing the test specimen and which region of the locking ball that is tested in each method. The strength testing method that is proposed in this thesis is called the notched ball test (NBT). In NBT a long and narrow notch is cut in a locking ball which is then loaded in compression perpendicular to the notch until rupture occurs. The maximum stress acting at the rupture is calculated and used to determine the strength of the locking ball. NBT is suitable because it can be performed with existing equipment at the company, the test specimen is prepared from actual locking balls and the test uses tensile stresses which is an advantage when brittleness is to be detected in a material. An analysis of NBT is performed to determine how material properties and different notch geometries is affecting the test results. The analysis also gives some recommendations for notch geometries that should be used when performing NBT as well as a constant that is used when calculating the maximum stress. Practical experiments of NBT are not carried out in this thesis. Instead, conclusions regarding NBT and recommendations for the company on how they should proceed with NBT are given.
11
Podgorski, Michael. "Rôle des interfaces dans les propriétés macroscopiques de composites C/C." Thesis, Bordeaux 1, 2009. http://www.theses.fr/2010BOR13852.
Full textAbstract:
Les composites Carbone/Carbone (C/C), largement utilisés à hautes températures dans des environnements oxydants, sont sensibles à l'oxydation dès 400°C. Deux voies sont envisagées pour accroître la tenue à l'oxydation de ces matériaux. La première est de renforcer la force de la liaison fibre/matrice en modifiant les propriétés de surface des fibres de carbone. La seconde voie d 'étude consiste à remplacer une partie de la matrice carbone par un oxyde. L'introduction d'une nouvelle phase conduit à la création de nouvelles interfaces dans les matériaux. L'ensemble des résultats obtenus à partir des caractérisations physico-chimiques et macroscopiques des matériaux élaborés permettent alors de répondre à la problématique qui est de connaître le rôle des interfaces dans les propriétés macroscopiques de composites C/CC/C composites are widely used as structural parts in oxiding environment. Yet, they become very sensitive to air oxidation for temperature higher than 400°C. This work proposed two methods to improve their oxidation resistance :(i) the fiber/matrix bond is increased by modifying the properties of the carbon fiber surface, and (ii) a fraction of the carbon matrix is substitued by an oxide phase.Introduction of new constituants leads to the creation of new material interfaces. Thus, the influence of the interfaces on the macroscopic properties of the composite is evaluated by physico-chemical and macroscopic characterizations
12
Merli, Francesca. "Static and dynamic elastic moduli of historical brick masonry subjected to freeze-thaw cycles and to different moisture amounts." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
Environment conditions and moisture presence in masonry structures may affect durability or even mechanical properties of architectural heritage.
Among all the deterioration causes, the degradation of historic masonry by freeze-thaw cycles and different moisture amount are considered to evaluate their influence on elastic properties.
Therefore, two experimental campaigns were carried out in the present study.
The first one was performed at the Dept. of Geotechincal Engineering at Tongji University, to assess the influence of freeze-thaw cycles on elastic modulus of historic Chinese brick.
The static elastic modulus was evaluated from the compressive strength test on masonry specimens subjected to different numbers of freeze-thaw cycles.
Moreover, strength decay of the masonry was investigated, also analysing data obtained during ultrasonic test (UPV, non-destructive test). The aim of this step was to obtain the dynamic elastic modulus. Thanks to interpolation of the obtained data it was possible to improve the knowledge of the Elasticity modulus’ reduction of historic masonry subjected to freeze-thaw cycles.
The second experimental campaign was performed at DICAM, University of Bologna, on ancient Chinese and Italian bricks, to assess the sensitivity of dynamic elastic modulus to moisture amount. In particular the influence of water presence in the material pores on the UPV measurements.
The close relationship between the ultrasonic pulse velocity and the moisture content was investigated on brick cores in dry, 50% saturated and saturated conditions.
Practical value and one of the main contribution of the experiments was the investigation of external factor and intrinsic properties of porous materials which directly influence the ultrasonic pulse velocity test.
13
Carmo, Cássio Alberto Teoro do. "A avaliação do módulo de resiliência através de ensaios triaxiais dinâmicos de dois solos compactados e a sua estimativa a partir de ensaios rotineiros." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/18/18137/tde-14032018-111408/.
Full textAbstract:
O conhecimento do módulo de resiliência dos materiais constituintes do pavimento e do seu subleito é indispensável quando o objetivo é projetá-lo, ou analisar o seu comportamento frente à solicitação das cargas rodoviárias. O módulo de resiliência é determinado, na maioria das vezes, a partir de resultados de ensaios triaxiais dinâmicos, que exigem equipamentos complexos para a sua realização. Assim, é desejável que se disponha de métodos que possibilitem a sua avaliação a partir de resultados de ensaios mais simples. Neste trabalho, foram realizados ensaios triaxiais dinâmicos para a determinação do módulo de resiliência de dois solos, um argiloso e outro arenoso fino, compactados nas energias normal e intermediária. A partir dos resultados dos ensaios cíclicos foi possível modelar a variação do módulo de resiliência com a variação do carregamento aplicado e identificar, entre as variáveis de tensão, aquelas que exercem maior influência no valor deste módulo. A existência de discrepâncias significativas entre os valores de módulo de resiliência obtidos a partir de sucessivos ensaios de um mesmo corpo-de-prova foi também investigada. Finalmente, analisou-se a existência de uma relação entre o módulo de resiliência obtido nos ensaios dinâmicos e o módulo tangente inicial proveniente de ensaios de compressão simples, sob diversos níveis de tensão. Os resultados mostram que este tipo de associação é promissora, mas exige-se que o universo dos solos estudados seja ampliado para que se estabeleça uma conclusão definitiva.The knowledge about the resilient modulus of the pavement constituent materials and subgrade is essential in order to design or to analyze theirs behavior subjected to traffic loading. Often, the resilient modulus is obtained from repeated load triaxial tests demanding complex equipment for their execution. Thus, is desirable to develop methods to permit its evaluation from more simple tests. In this work, repeated load triaxial tests are carried out to the determination of the resilient modulus of two soils, a clay and a fine sand, compacted in the normal and intermediate AASHTO compretion efforts. From the repeated load triaxial test data it was possible to model the variation of resilient modulus with the variation of applied loading as wellos to identify, among the stress parameters, those of more influence on the value of this modulus. The significant discrepancy among the resilient modulus values obtained from successive tests in the same sample was also investigated. Finally, equations were developed in order to correlata the resilient modulus from repeated load triaxial tests to parameters from compressive strength tests, considering different states of stress. lt was shown that this type of empirical correlation presented satisfactory results, although incisiva conclusions could not be drawn without using a lager number and variety of soils.
14
Villegas, Effio Marcelo Alonso. "Aplicación de redes neuronales para la predicción de la resistencia a la compresión del concreto según el ensayo de esclerometría." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/626504.
Full textAbstract:
El número de rebote es el valor resultante del ensayo de dureza superficial, que consiste en determinar el nivel de compacidad de las partículas del concreto. Esta característica lleva relación directa con el desarrollo de la resistencia a compresión, denominada f’c; ya que mientras más compactas se encuentren las partículas del concreto, mayor será la resistencia mecánica y mayor el valor del número de rebote. La relación de estos ensayos ha sido materia de estudio desde hace muchos años y se ha determinado valores altos de correlación, aunque sin cuantificar la influencia de parámetros adicionales que no resultan ajenos al ensayo de esclerometría. En la presente investigación se analizan los principales factores que afectan al valor de dureza superficial e influyen en la determinación de la resistencia mecánica del concreto. Los factores estudiados son la relación agua – cemento, condición de humedad, edad del concreto y tamaño máximo de agregado. Estos factores son analizados en muestras de concreto normalizadas (probetas diseñadas según norma de calidad vigente) y los resultados obtenidos procesados estadísticamente bajo la metodología de Red Neuronal Artificial (RNA), con el que se podrá predecir resultados de resistencia a compresión una vez determinados los factores antes mencionados. Los resultados demuestran que puede predecirse el resultado de resistencia a la compresión con margen de error aceptable y que considerar los factores de influencia en la predicción genera mayor exactitud en los resultados y reducción en el índice de correlación de Pearson estudiado entre los ensayos de dureza superficial y resistencia a compresión.The rebound number index is a result value of surface hardness´s test. This method is based on obtain concrete particular’s level. This characteristic has a direct relationship with the development of compressive strength, called f’c. So, if concrete particulars are more compact, it will increase mechanic strength and rebound number index´s value. The relationships between these tests have been studied over the years and it has been estimated high values of correlation, although without quantifying the influence of additional parameters that are not indifferent to the sclerometer test. In this research are analyzed the principal factors which affect surface hardness´s value and influent in the determination of mechanic strength of concrete. The factors studied are the water-cement ratio, humidity condition, age of concrete and maximum size of aggregate. These factors are analyzed in standardized concrete samples and the results obtained were processed statistically by artificial neuronal network’s methodology (RNA), this tool will predict results of compressive strength when other factors, which were explained, have been determinate. The results of this research show that the result of resistance to compression can be predicted with acceptable margin of error and that considering the influence factors in the prediction generates better accuracy in the results and reduction in the Pearson correlation index studied between the test of surface hardness and compressive strength.
Tesis
15
Santos, Adriana Goulart dos. "Estudo do comportamento resiliente de três solos da região de Campo Grande-MS e de relações entre o módulo de resiliência e resultados de ensaios de compressão simples." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18137/tde-06102009-093939/.
Full textAbstract:
O conhecimento do módulo de resiliência (MR) é fundamental ao se projetar um pavimento, pois ele é necessário para o cálculo de tensões, deformações e deflexões nas suas camadas e subleito, bem como, a análise do desempenho do sistema. Embora ensaios de campo possam ser empregados para se determinar o MR, a grande maioria das pesquisas nesse sentido são desenvolvidas em laboratório, onde é possível um maior controle das condições da amostra, da aplicação de carregamento e medida dos deslocamentos. Porém, pela complexidade e alto custo dos ensaios de laboratório, há a necessidade de pesquisas que disponibilizem expressões que permitam estimar o MR a partir de resultados de ensaios mais simples que o triaxial cíclico e usuais na pavimentação. Nesta pesquisa, foram realizados ensaios triaxiais cíclicos para a determinação do MR de três solos empregados em rodovias de Campo Grande - MS. A partir dos resultados dos ensaios triaxiais cíclicos, verificou-se o desempenho dos modelos mais comumente empregados para se representar a variação do módulo de resiliência em função do estado de tensão. Foram propostas e analisadas expressões matemáticas entre o MR obtido a partir dos ensaios triaxiais cíclicos e o módulo tangente inicial proveniente de ensaios de compressão simples, sob diversos níveis de tensão. Finalmente, analisou-se a existência de relações que englobem, além dos solos estudados nesta pesquisa, os solos estudados anteriormente em outras pesquisas desenvolvidas na EESC-USP. Os resultados mostram que este tipo de associação é promissora, mas exige-se que o universo de solos estudados seja ampliado para que se estabeleça uma inferência decisiva.The resilient modulus knowledge (MR) is fundamental for pavement design, once it is necessary for stresses, strains and deflections calculus in its layers and subgrade, as well as, the analysis of system performance. Although field tests may be used to determine the dynamic behavior of soils, most of researchers favor laboratory tests, based on the fact that such tests are less constrained because of their carefully controlled conditions. Because laboratory procedures are considered complex and highly expensive, it is desirable to establish relationships among MR and other index properties that are relatively simple and usual in pavement construction. In this research, cyclic triaxial tests were performed to determine MR of three soils used in Campo Grande-MS roads. The performance of the models most commonly adopted to represent resilient modulus as a function of state of stress were verified. A mathematical expression among MR, obtained from the cyclic triaxial tests, and the initial tangent modulus, obtained from unconfined compression strength tests, were developed considering different states of stress. Finally, were analyzed the existence of relationships among soils studied in this research, and soils used in previous studies developed at EESC-USP. Results show that this type of empirical correlation presents a satisfactory results, however incisive conclusions cannot be taken without a large number and variety of soils.
16
Silva, Bruno do Vale. "Proposição de um teste de aderência apropriado para controle tecnológico da resistência à compressão do concreto." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/107489.
Full textAbstract:
Esta pesquisa propõe-se estudar a viabilidade de um ensaio de aderência aço-concreto apropriado (Appropriate Bond Test - ABT) para estimativa da resistência à compressão axial do concreto, objetivando empregá-lo como complemento ao controle de qualidade do concreto armado em campo. Originalmente os autores Lorrain e Barbosa (2008) apresentaram a utilização de um ensaio de aderência apropriado, denominado APULOT, para estimar a resistência à compressão do concreto, aumentando as possibilidades de controle tecnológico do concreto armado em canteiros de obras. Os mesmos propõem uma adaptação do método pull-out test (POT) tradicional, normalizado pela RILEM CEB/FIP RC6:1983, por ser este um ensaio de baixa complexidade e de custo reduzido. Para viabilizar o uso de um ensaio de aderência apropriado como ensaio de controle tecnológico do concreto em canteiro de obras é necessário definir um padrão para o mesmo e adaptá-lo da prática experimental do laboratório para o campo. O presente trabalho buscou avaliar os seguintes parâmetros: (1) Tipo de carregamento do ensaio (pull-out e push-in); (2) Influência do tipo de configuração geométrica das barras de aço; (3) Análises da preparação, moldagem, cura e estocagem dos corpos de prova do ABT; (4) Análises quanto à execução do ABT referentes à idade de ruptura, taxa de carregamento e tipo de ruptura; (5) Implementação do ABT em canteiro de obras, avaliando a sua potencialidade de efetuar estimativas da resistência à compressão a partir dos dados da tensão de aderência. Para tanto, foram ensaiadas 26 composições de concreto de classes distintas, com idades entre 3 e 28 dias. Foram, ainda, testadas 8 configurações distintas de barras de aço com diâmetros nominais de 8 e 12,5 mm. Os resultados obtidos mostram que, sob condições padronizadas de ensaio e adotando os coeficientes adequados, a correlação entre a tensão máxima de aderência e a resistência à compressão do concreto é satisfatória, fortalecendo o propósito de consolidar este ensaio como uma alternativa complementar para controle de qualidade do concreto armado.This research proposes a study on the feasibility of bond test steel-concrete appropriate (Appropriate Bond Test - ABT) to estimate the compressive strength of concrete, aiming to use them as a supplement in the quality control of concrete in situ. Originally the authors Lorrain and Barbosa (2008) proposed the use of a modified bond test, called APULOT to estimate the compressive strength of the concrete, increasing the possibilities for technological control of reinforced concrete on construction sites. They propose an adaptation of the traditional method pull-out test (POT), normalized by the CEB / FIP RC6: 1983, because it is a test of low complexity and low cost. To enable the use of the test as a test technological control of concrete in construction site is necessary to define a standard for yourself and adapt it practice experimental laboratory to the field. This study evaluated the following parameters: (1) Type of load test (pull-out and push-in); (2) Influence of the type of geometric configuration of steel bar; (3) Analyses of preparation, molding, curing and storage of specimens of ABT; (4) Review of the implementation of ABT on age rupture, loading rate and type of fracture; (5) Implementation of ABT in construction site, evaluating its potential to make estimates of compressive strength from the data of bond stress. Therefore, 26 different compositions of concrete classes, aged between 3 and 28 days, were tested. Were also tested 8 different configurations of steel bars with nominal diameters of 8 and 12.5 mm. The results indicate that, under standard testing and adopting the appropriate coefficients conditions, the correlation between the maximum bond stress and the compressive strength of concrete is satisfactory, strengthening the purpose of consolidating this test as a complementary alternative to quality control reinforced concrete.
17
Kozáček, Vojtěch. "Experimentální stanovení závislosti parametrů NDT a pevnosti v tlaku betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409957.
Full textAbstract:
The diploma thesis deals with non-destructive testing of concrete as well as with the relationship between determined parameters and the compressive strength of concrete. The thesis is mainly focused on the ultrasonic pulse velocity method and the rebound hammer test. The experimental part of the thesis describes non-destructive tests performed on concrete blocks. The compressive strength was tested on the drill cores taken from the concrete blocks. The aim of this thesis is to find regression models of the relationship between the compressive strength and non-destructive parameters, and the subsequent analysis of the results.
18
Gonçalves, Ricardo Freire. "Estudo da influência da variação do teor de umidade no valor do módulo de resiliência de um solo argiloso encontrado em subleito de rodovias no interior paulista." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/18/18137/tde-30012018-113018/.
Full textAbstract:
O objetivo deste trabalho é avaliar a influência da variação do teor de umidade no valor do módulo de resiliência (MR) de um solo argiloso de subleito, tendo em vista que este parâmetro é muito susceptível à variações climáticas ambientais. Foram realizados ensaios triaxiais cíclicos para se estimar o módulo de resiliência de corpos de prova ensaiados em diversas condições de umidade. Verificou-se que o MR é influenciado pela tensão desvio, de forma que aquele aumenta com o acréscimo desta. Constatou-se que os corpos de prova moldados na Wot e submetidos a trajetórias de secagem e umedecimento alcançaram valores de MR superiores e inferiores, respectivamente, ao se comparar com o MR de corpos de prova ensaiados na Wot. Este fato foi também observado para os corpos de prova moldados com massa específica seca máxima, em teores de umidade abaixo e acima do teor ótimo. Determinou-se, ainda, a sucção no solo através do método do papel filtro e levantou-se a sua curva característica. Verificou-se que à medida que a umidade aumenta, a sucção diminui. Observou-se que o valor do MR aumenta com o aumento da sucção no solo. Este crescimento é tanto maior quanto maior seja a tensão desvio aplicada. Foi possível determinar a relação entre o MR, a tensão desvio e o módulo tangente inicial (Eo), proveniente dos ensaios de compressão simples. Relacionou-se, também, o Eo e a sucção no solo.The aim of this work is to evaluate the influence of moisture content variation in resilient modulus value (MR) of a subgrade clayey soil, considering that this parameter is very susceptible to environmental climatic variations. Cyclic triaxial tests were performed to acess resilient modulus of specimens tested in several moisture conditions. lt has been verified that MR is influenced by deviator stress, so that the former increases with the latter increases. lt has been confirmed that specimens molded in Wot and submited to a drying and moistening route reached MR values higher and lower, respectively, to compare with MR of specimens tested in Wot. This fact was also observed for the specimens molded with dry density, in moisture contents below and above of optimum moisture content. lt has been also determined the soil suction using filter paper method and it has been built its characteristic curve. lt has been verified that when moisture increases, the suction decreases. lt has been observed that MR value increases with the soil suction increase. This increase is as bigger as bigger the applied deviator stress be. lt was possible to determine the relationship between MR, deviator stress and parameters from compressive strength tests. lt has been related parameters from compressive strength tests and soil suction.
19
Takeda, Marcelo de Castro. "A influência da variação da umidade pós-compactação no comportamento mecânico de solos de rodovias do interior paulista." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18143/tde-25112006-225630/.
Full textAbstract:
Na construção de rodovias, as condições de umidade e densidade observadas na compactação são, geralmente, próximas daquelas correspondentes ao pico da curva de compactação obtida no ensaio Proctor. É sabido que variações ambientais no decorrer da vida do pavimento podem alterar, de maneira significativa, a umidade do subleito e dos seus componentes e assim, as suas propriedades resilientes. O objetivo principal desta pesquisa é avaliar a influência da variação da umidade pós-compactação no módulo de resiliência de solos de rodovias do interior paulista a partir de resultados de ensaios de laboratório. Foram coletados e caracterizados setenta e três solos, e, dentre estes, selecionados trinta para a etapa de estudo da variação da umidade pós-compactação, após a realização de ensaios MCT, difração de raios-x, microscopia eletrônica de varredura e azul de metileno para determinação da gênese. Os solos selecionados apresentam características distintas quanto à gênese, sendo metade laterítico e metade não-laterítico. Os corpos-de-prova foram compactados na umidade ótima e submetidos a processos de secagem e umedecimento e, posteriormente, realizados ensaios triaxiais cíclicos. Os resultados permitiram a modelagem do 'M IND.R' em função do estado de tensão para diferentes umidades e a avaliação da competência de alguns modelos matemáticos nesta representação. Estudou-se a influência da gênese e da granulometria sobre o valor do 'M IND.R' e avaliou-se a conseqüência da variação da umidade sobre este para solos lateríticos e não-lateríticos. Determinou-se uma expressão para estimar a variação do 'M IND.R' com a variação da umidade a partir do parâmetro k1, independentemente do estado de tensão. Pesquisou-se a existência de relações entre os parâmetros de regressão do modelo composto e os resultados dos ensaios de compressão simples e as propriedades físicas dos solos, de forma a permitir a estimativa do módulo de resiliência a partir do resultado de ensaios mais simples. Investigou-se a possibilidade de se utilizar as relações entre a variação do módulo tangente inicial com a variação da umidade para estimar os efeitos sobre o 'M IND.R'.On road construction, the field compaction conditions are usually close to those determined from Proctor tests. Environmental variations may lead to changes in the pavement moisture and also changing its resilient properties. The main objective of this research is to study the influence of post-compaction moisture content variation on the resilient modulus of soils from São Paulo state pavements, using laboratory tests. To accomplish this objective, seventy three soils samples were collected and characterized. Among them, thirty samples were selected, after four different tests were carried out to determine the soils genesis, to study the post-compaction moisture content variation. Half of these selected soils are lateritic ones, and the other half are non-lateritic soils. The specimens were compacted at optimum moisture content and submitted to drying and moistening processes prior cyclic triaxial test to be carried out. The results allowed the resilient modulus modeling as a function at the stress state and the performance evaluation of five different models. The genesis and grain size distribution influence on the resilient modulus values were studied. The effects of moisture content variations on lateritic and non-lateritic soils were investigated. An expression to estimate the resilient modulus variations with the moisture variations was determined, independently of the stress state. The existence of relations of the compound model regression parameters with the results of unconfined compressive strength and soil properties were studied. The possibility of using the initial tangent modulus variations with the moisture variations to estimate the effects on the resilient modulus were also investigated.
20
Franceschelli, Stefano. "Experiments on Chinese historical brick and masonry to evaluate their physical and mechanical properties after freeze-thaw cycles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Find full textAbstract:
Ultrasonic Pulse Velocity (UPV) and Rebound test as non-destructive techniques may effectively contribute to in situ analysis of bricks and masonries elements for the restoration, rehabilitation and strengthening of historic buildings.
Fired-clay bricks were commonly used in buildings in ancient China, but there is few knowledge on their behaviour in environmental conditions. Moisture is one of the main factors that cause deterioration in historic building, in particular in areas with natural freeze-thaw cycles.
In this work, two laboratory experiments were carried out, at Tongji University, China, and DICAM Department of Bologna University, Italy, respectively. Fired-clay bricks about 200 years old were collected from demolished buildings in Changzhi City in Shanxi Province, belonging to the Yellow River Region, where the climate involves natural freeze-thaw cycles.
The aim was to evaluate how the frost damage changes the physical and mechanical properties of Chinese historical bricks and masonries. Several non-destructive methods were used, focusing on the effectiveness of Ultrasonic Pulse Velocity (UPV) for evaluating physical and mechanical properties of Chinese historic grey bricks and masonries. Destructive tests were also used to evaluate compressive strength and static elastic modulus.
The samples showed a reduction of their properties due to freeze-thaw cycles. The presence of water affected the values of the analysed parameters, leading to a decrease of UPV.
The trend determined by these methods can be used to assess the uniformity of bricks and to detect areas of poor quality or deteriorated masonry structures.
21
Kim, Woochan. "Development of Bi-Directional Module using Wafer-Bonded Chips." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51170.
Full textAbstract:
Double-sided module exhibits electrical and thermal characteristics that are superior to wire-bonded counterpart. Such structure, however, induces more than twice the thermo-mechanical stress in a single-layer structure. Compressive posts have been developed and integrated into the double-sided module to reduce the stress to a level acceptable by silicon dice. For a 14 mm x 21 mm module carrying 6.6 mm x 6.6 mm die, finite-element simulation suggested an optimal design having four posts located 1 mm from the die; the z-direction stress at the chip was reduced from 17 MPa to 0.6 MPa.Ph. D.
22
Amani, Yasin. "Modélisation basée sur données de tomographie aux rayons X de l'endommagement et de la conductivité thermique dans les matériaux cellulaires métalliques." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI036/document.
Full textAbstract:
Les propriétés des matériaux cellulaires dépendent de leur architecture et des défauts de coulée. L'architecture se réfère à la forme et la distribution de la phase solide. Les défauts correspondent à la présence et aux distributions des cavités et d'intermétalliques dans la phase solide du fait de la procédure de fabrication. Deux types de matériaux produits de différentes façons sont étudiés dans cette thèse. D'une part, deux mousses ERG de tailles de pores différentes ont été choisies pour étudier l'effet de la présence des intermétalliques sur la plasticité et l'endommagement. Des tests de micro-traction et des expériences de nanoindentation ont été réalisés sur des éprouvettes extraites de la mousse pour déterminer leur comportement micro-élastoplastique de la phase solide. D'autre part, deux structures ayant la même forme et le même motif répétitif, mais différentes épaisseurs d'entretoises et de nœuds ont été produites par fusion sélective par laser pour étudier aussi la plasticité et l'endommagement. Ce travail de thèse visait à développer une procédure de modélisation par éléments finis générique basée sur les images 3D pour prendre en compte l'effet de la porosité locale et la présence des intermétalliques dans le comportement. Les états initiaux des échantillons ont été numérisés en utilisant des méthodes de tomographie "locale" et "stitching" à haute résolution. Les géométries 3D maillées, la porosité locale et les propriétés élastiques-plastiques de chaque élément ont été directement renseignées à partir des images 3D à haute résolution. Les procédures de déformation et de rupture des échantillons ont été illustrées en effectuant des expériences in-situ/ex-situ couplées à une numérisation tomographique à basse résolution. Des modèles éléments finis conformes à l'image 3D ont été développés pour la simulation des essais de traction/compression et montrent que la prise en compte des hétérogénéités locales de microstructure permet de prédire plus finement le comportement mécanique des structures cellulaires, en particulier dans la rupture. L'étude visait également à déterminer la conductivité thermique d'une mousse ERG hautement poreuse en utilisant des calculs par éléments finis basés sur l'image. Les résultats ont été vérifiés en comparant avec la conductivité thermique mesurée à partir des expériences de plaques chaufféesThe properties of cellular materials depend on their architecture and casting defects. The architecture refers to shape and distribution of the solid phase. Defects correspond to the presence and distribution of cavities or intermetallic particles in the solid phase due to the fabrication procedure. Two types of materials produced by different fabricating routes are studied in this manuscript. On the one hand, two ERG foams with different cell sizes were chosen to study the effect of the presence of intermetallic particles on the plasticity and damage. Micro-tensile tests and nanoindentation experiment were also performed on the struts extracted from the foam to determine their micro elastoplastic behaviour. On the other hand, two structures with the same shape and repetitive pattern but different struts and nodes thicknesses were produced by selective laser melting manufacturing route to study the effect of porosity on plasticity and damage. This PhD-work aimed at developing a generic image-based finite element procedure to take into account the effect of the local porosity and the presence of intermetallic particles into the finite element simulations of the cellular materials. The initial state of the samples was pictured by performing high resolution "local" tomography and "stitching" methods. The 3D geometries were meshed and the local porosity and elastic-plastic properties of each element were directly informed according to high-resolution 3D images. The deformation and fracture procedures of the samples were pictured by performing in-situ/ex-situ experiments coupled with low-resolution tomography scanning. 3D image-based finite element models were developed for the simulation of the tension/compression tests. The microstructurally informed FE models better capture the mechanical behaviour of the cellular structures, especially for the prediction of the fracture. The study also aimed at determining the thermal conductivity of a highly porous ERG foam using image-based finite element calculations. The results were verified by comparing with the measured thermal conductivity from guarded hot plates experiments
23
Linhares, Pontes Elvys. "Compressive Cross-Language Text Summarization." Thesis, Avignon, 2018. http://www.theses.fr/2018AVIG0232/document.
Full textAbstract:
La popularisation des réseaux sociaux et des documents numériques a rapidement accru l'information disponible sur Internet. Cependant, cette quantité massive de données ne peut pas être analysée manuellement. Parmi les applications existantes du Traitement Automatique du Langage Naturel (TALN), nous nous intéressons dans cette thèse au résumé cross-lingue de texte, autrement dit à la production de résumés dans une langue différente de celle des documents sources. Nous analysons également d'autres tâches du TALN (la représentation des mots, la similarité sémantique ou encore la compression de phrases et de groupes de phrases) pour générer des résumés cross-lingues plus stables et informatifs. La plupart des applications du TALN, celle du résumé automatique y compris, utilisent une mesure de similarité pour analyser et comparer le sens des mots, des séquences de mots, des phrases et des textes. L’une des façons d'analyser cette similarité est de générer une représentation de ces phrases tenant compte de leur contenu. Le sens des phrases est défini par plusieurs éléments, tels que le contexte des mots et des expressions, l'ordre des mots et les informations précédentes. Des mesures simples, comme la mesure cosinus et la distance euclidienne, fournissent une mesure de similarité entre deux phrases. Néanmoins, elles n'analysent pas l'ordre des mots ou les séquences de mots. En analysant ces problèmes, nous proposons un modèle de réseau de neurones combinant des réseaux de neurones récurrents et convolutifs pour estimer la similarité sémantique d'une paire de phrases (ou de textes) en fonction des contextes locaux et généraux des mots. Sur le jeu de données analysé, notre modèle a prédit de meilleurs scores de similarité que les systèmes de base en analysant mieux le sens local et général des mots mais aussi des expressions multimots. Afin d'éliminer les redondances et les informations non pertinentes de phrases similaires, nous proposons de plus une nouvelle méthode de compression multiphrase, fusionnant des phrases au contenu similaire en compressions courtes. Pour ce faire, nous modélisons des groupes de phrases semblables par des graphes de mots. Ensuite, nous appliquons un modèle de programmation linéaire en nombres entiers qui guide la compression de ces groupes à partir d'une liste de mots-clés ; nous cherchons ainsi un chemin dans le graphe de mots qui a une bonne cohésion et qui contient le maximum de mots-clés. Notre approche surpasse les systèmes de base en générant des compressions plus informatives et plus correctes pour les langues française, portugaise et espagnole. Enfin, nous combinons les méthodes précédentes pour construire un système de résumé de texte cross-lingue. Notre système génère des résumés cross-lingue de texte en analysant l'information à la fois dans les langues source et cible, afin d’identifier les phrases les plus pertinentes. Inspirés par les méthodes de résumé de texte par compression en analyse monolingue, nous adaptons notre méthode de compression multiphrase pour ce problème afin de ne conserver que l'information principale. Notre système s'avère être performant pour compresser l'information redondante et pour préserver l'information pertinente, en améliorant les scores d'informativité sans perdre la qualité grammaticale des résumés cross-lingues du français vers l'anglais. En analysant les résumés cross-lingues depuis l’anglais, le français, le portugais ou l’espagnol, vers l’anglais ou le français, notre système améliore les systèmes par extraction de l'état de l'art pour toutes ces langues. En outre, une expérience complémentaire menée sur des transcriptions automatiques de vidéo montre que notre approche permet là encore d'obtenir des scores ROUGE meilleurs et plus stables, même pour ces documents qui présentent des erreurs grammaticales et des informations inexactes ou manquantesThe popularization of social networks and digital documents increased quickly the informationavailable on the Internet. However, this huge amount of data cannot be analyzedmanually. Natural Language Processing (NLP) analyzes the interactions betweencomputers and human languages in order to process and to analyze natural languagedata. NLP techniques incorporate a variety of methods, including linguistics, semanticsand statistics to extract entities, relationships and understand a document. Amongseveral NLP applications, we are interested, in this thesis, in the cross-language textsummarization which produces a summary in a language different from the languageof the source documents. We also analyzed other NLP tasks (word encoding representation,semantic similarity, sentence and multi-sentence compression) to generate morestable and informative cross-lingual summaries.Most of NLP applications (including all types of text summarization) use a kind ofsimilarity measure to analyze and to compare the meaning of words, chunks, sentencesand texts in their approaches. A way to analyze this similarity is to generate a representationfor these sentences that contains the meaning of them. The meaning of sentencesis defined by several elements, such as the context of words and expressions, the orderof words and the previous information. Simple metrics, such as cosine metric andEuclidean distance, provide a measure of similarity between two sentences; however,they do not analyze the order of words or multi-words. Analyzing these problems,we propose a neural network model that combines recurrent and convolutional neuralnetworks to estimate the semantic similarity of a pair of sentences (or texts) based onthe local and general contexts of words. Our model predicted better similarity scoresthan baselines by analyzing better the local and the general meanings of words andmulti-word expressions.In order to remove redundancies and non-relevant information of similar sentences,we propose a multi-sentence compression method that compresses similar sentencesby fusing them in correct and short compressions that contain the main information ofthese similar sentences. We model clusters of similar sentences as word graphs. Then,we apply an integer linear programming model that guides the compression of theseclusters based on a list of keywords. We look for a path in the word graph that has goodcohesion and contains the maximum of keywords. Our approach outperformed baselinesby generating more informative and correct compressions for French, Portugueseand Spanish languages. Finally, we combine these previous methods to build a cross-language text summarizationsystem. Our system is an {English, French, Portuguese, Spanish}-to-{English,French} cross-language text summarization framework that analyzes the informationin both languages to identify the most relevant sentences. Inspired by the compressivetext summarization methods in monolingual analysis, we adapt our multi-sentencecompression method for this problem to just keep the main information. Our systemproves to be a good alternative to compress redundant information and to preserve relevantinformation. Our system improves informativeness scores without losing grammaticalquality for French-to-English cross-lingual summaries. Analyzing {English,French, Portuguese, Spanish}-to-{English, French} cross-lingual summaries, our systemsignificantly outperforms extractive baselines in the state of the art for all these languages.In addition, we analyze the cross-language text summarization of transcriptdocuments. Our approach achieved better and more stable scores even for these documentsthat have grammatical errors and missing information
24
Izquierdo, Orieta Soto. "Estudo da interface bloco/graute em elementos de alvenaria estrutural." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-13052015-165029/.
Full textAbstract:
A construção de edifícios em alvenaria estrutural tem evoluído de maneira significativa no Brasil. Os edifícios têm se tornado cada vez mais altos, atingindo a marca de 20 pavimentos. Quanto mais altos os edifícios, maiores se tornam os níveis de compressão provenientes dos carregamentos verticais e a sua composição com as ações devidas ao vento e ao desaprumo, obrigando a um maior emprego da alvenaria estrutural armada. A aderência bloco/graute como fator limitante à capacidade do conjunto armadura/graute/bloco na absorção da compressão e tração simples ou da tração oriunda da flexão não é especificada nas normas tanto nacionais como internacionais. Este trabalho tem como objetivo principal estudar o comportamento da interface bloco/graute, tanto para blocos de concreto como cerâmicos e com a presença ou não de armadura, submetidos a solicitações que provocam tração e compressão. Recursos experimentais e numéricos foram realizados para o desenvolvimento da presente pesquisa. Foram feitos ensaios de caracterização dos materiais, dos componentes e da alvenaria, além de ensaios de \"push-out\" (empurramento) para determinar a resistência de aderência na interface graute/bloco e ensaios de \"pull-out\" (arrancamento) considerando-se a presença de barras de armadura para o estudo do comportamento do conjunto graute/bloco/armadura utilizados. Posteriormente foram realizadas modelagens computacionais no programa DIANA, que é baseado no método dos elementos finitos, para prever o comportamento estrutural dos modelos. A partir dos resultados experimentais e numéricos pôde-se concluir que existe uma boa aderência entre as paredes dos blocos de concreto e o graute, suficiente para evitar o escorregamento, sendo possível mobilizar toda a resistência de tração das barras de armadura de diâmetros usuais, desde que devidamente ancoradas. Já com os blocos cerâmicos observa-se uma menor aderência entre as paredes dos blocos e o graute, podendo ocorrer o escorregamento do material de enchimento, antes que a armadura alcance sua tensão de escoamento. O graute de maior resistência à compressão e menor fator água cimento (graute G30) apresentou maior resistência de aderência em relação ao graute mais fraco (graute G14) e de maior fator água/cimento. Quanto aos limites estabelecidos para a tensão de escoamento das armaduras, observa-se que, no caso de blocos de concreto, não deve haver restrição. Em contraposição, quanto aos blocos cerâmicos, o problema é mais complexo, cabendo a realização de mais ensaios para a confirmação de limites, com a variação de blocos e grautes. Os resultados do estudo paramétrico apontam limites que devem ser adotados no caso de diâmetro superior a 10 mm. De maneira simplificada, como ponto para futuras verificações pode-se propor: 75% para Ø 12,5 mm, 50% para Ø 16 mm e 25% para Ø 20 mm. As análises numéricas realizadas nos modelos ensaiados a push-out e pull-out representaram adequadamente o comportamentos observado em laboratório, permitindo a realização da análise paramétrica.The construction of structural masonry buildings has evolved significantly in Brazil. The buildings have become ever higher, reaching the level of 20 floors. Higher buildings lead to lager compression levels, coming from the vertical loads combined to the horizontal actions due to wind and lack of verticality, obliging a greater use of reinforced structural masonry. The block/grout adherence is not specified in both national and international standards. This work aims to study the behavior of the block/grout interface, for both concrete and clay blocks, with and without reinforcement, submitted to tensile and compressive forces. Experimental and numerical resources were used to development of this study. The experimental program studied the masonry behavior using push-out specimens to determine the bond strength between the grout and the concrete unit, and pull-out specimens to study the behavior of the interface of the grout/block/reinforcement. Computational modelling was carried out using the FEM software Diana, which has a library with constitutive models suitable for civil engineering application, to complete the study and understand the structural behavior of the block/grout interface. The experimental results showed that there is a good bond between the concrete blocks internal faces and the grout, enough to prevent infill-slippage, and that the whole tensile strength of the usual reinforcement rebars is achieved provided they are properly anchored. Nevertheless, for clay blocks there is a low bond between the clay blocks internal faces and the grout, allowing the infill-slippage before the reinforcement bars reach their yield stress. The higher strength grout with lower water/cement ratio (grout G30) presented higher bond strength compared to the lower strength grout and higher water/cement ratio (grout G14). In the case of concrete blocks there should be no restriction limits on the yield stress of reinforcement, in a practical sense and considering other prescribed limits. In contradiction, in the case of clay blocks, additional tests should be carried out for establishing limits, with varying blocks and grouts. The parametric analysis indicates limits that should be adopted for a diameter larger than 10 mm. The authors of this research suggest 75% for Ø 12.5 mm, 50% for Ø 16 mm and 25% for Ø 20 mm as a reference point for future investigations. The numerical analysis showed that the computer models of the push-out and pull-out specimens represented adequately the behavior of the physical models, and thus can be used in parametric analysis.
25
Brown, Ashley Vannoy. "Cement Stabilization of Aggregate Base Materials Blended with Reclaimed Asphalt Pavement." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1314.pdf.
Full text
26
Fójcik, Tomáš. "Vliv triaxiální deformace kameniva na vlastnosti betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216555.
Full textAbstract:
This diploma work takes focus in elastic modulus of unbound granular aggregates, which was determined by repeat load triaxial test and in deformation behaviour of unbound granular aggregates - elastic and plastic deformation. It was examine the propriety of this aggregate for its service as underlying granular material in pavement. Further, there was observed the influence of elastic modulus of unbound granular aggregates on concrete characteristics - compressive and bending strength. Finally, it was observed the influence of individual fractions of aggregates on its elastic modulus and strength of concrete.
27
Kumar, Amit. "Generation of compact test sets and a design for the generation of tests with low switching activity." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/1476.
Full textAbstract:
Test generation procedures for large VLSI designs are required to achieve close to 100% fault coverage using a small number of tests. They also must accommodate on-chip test compression circuits which are widely used in modern designs. To obtain test sets with small sizes one could use extra hardware such as test points or use software techniques. An important aspects impacting test generation is the number of specified positions, which facilitate the encoding of test cubes when using test compression logic. Fortuitous detection or generation of tests such that they facilitate detection of yet not targeted faults, is also an important goal for test generation procedures.
At first, we consider the generation of compact test sets for designs using on-chip test compression logic. We introduce two new measures to guide automatic test generation procedures (ATPGs) to balance between these two contradictory requirements of fortuitous detection and number of specifications. One of the new measures is meant to facilitate detection of yet undetected faults, and the value of the measures is periodically updated. The second measure reduces the number of specified positions, which is crucial when using high compression. Additionally, we introduce a way to randomly choose between the two measures.
We also propose an ATPG methodology tailored for BIST ready designs with X-bounding logic and test points. X-bounding and test points used to have a significant impact on test data compression by reducing the number of specified positions. We propose a new ATPG guidance mechanism that balances between reduced specifications in BIST ready designs, and also facilitates detection of undetected faults. We also found that compact test generation for BIST ready designs is influenced by the order in which faults are targeted, and we proposed a new fault ordering technique based on fault location in a FFR. Transition faults are difficult to test and often result in longer test lengths, we propose a new fault ordering technique based on test enumeration, this ordering technique and a new guidance approach was also proposed for transition faults. Test set sizes were reduced significantly for both stuck-at and transition fault models.
In addition to reducing data volume, test time, and test pin counts, the test compression schemes have been used successfully to limit test power dissipation. Indisputably, toggling of scan cells in scan chains that are universally used to facilitate testing of industrial designs can consume much more power than a circuit is rated for. Balancing test set sizes against the power consumption in a given design is therefore a challenge. We propose a new Design for Test (DFT) scheme that deploys an on-chip power-aware test data decompressor, the corresponding test cube encoding method, and a compression-constrained ATPG that allows loading scan chains with patterns having low transition counts, while encoding a significant number of specified bits produced
by ATPG in a compression-friendly manner. Moreover, the new scheme avoids periods of elevated toggling in scan chains and reduces scan unload switching activity due to unique test stimuli produced by the new technique, leading to a significantly reduced power envelope for the entire circuit under test.
28
Jas, Abhijit. "Test vector compression techniques for systems-on-chip /." Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008359.
Full text
29
Gattis, Sherri L. "Ruggedized Television Compression Equipment for Test Range Systems." International Foundation for Telemetering, 1988. http://hdl.handle.net/10150/615062.
Full textAbstract:
International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, NevadaThe Wideband Data Protection Program was necessitated from the need to develop digitized, compressed video to enable encryption.
30
Wilson, Timothy David. "Animation of text compression algorithms." Thesis, University of Canterbury. Computer Science, 1992. http://hdl.handle.net/10092/9570.
Full textAbstract:
It has been said that, there is no particular mystery in animation ... it's very simple and like anything that is simple, it is about the hardest thing in the world to do. Text compression is about finding ways of representing text with the smallest amount of data such that it can be restored to its original state. Text compression algorithms are abstract concepts and bringing them into the visual domain is difficult but the effort can bring insight both to the student and to the researcher. This thesis presents some animations of text compression methods and observations about producing good educational and research animations. Several algorithm animation systems were used in the animation production and it was found that although there are several good animation systems fulfilling different functions, little is known about what makes good algorithms animation. A better way of defining animations and some practical principles for animation that were discovered while producing these animations are discussed.
31
Branavan, Satchuthananthavale Rasiah Kuhan. "High compression rate text summarization." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44368.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 95-97).
This thesis focuses on methods for condensing large documents into highly concise summaries, achieving compression rates on par with human writers. While the need for such summaries in the current age of information overload is increasing, the desired compression rate has thus far been beyond the reach of automatic summarization systems. The potency of our summarization methods is due to their in-depth modelling of document content in a probabilistic framework. We explore two types of document representation that capture orthogonal aspects of text content. The first represents the semantic properties mentioned in a document in a hierarchical Bayesian model. This method is used to summarize thousands of consumer reviews by identifying the product properties mentioned by multiple reviewers. The second representation captures discourse properties, modelling the connections between different segments of a document. This discriminatively trained model is employed to generate tables of contents for books and lecture transcripts. The summarization methods presented here have been incorporated into large-scale practical systems that help users effectively access information online.
by Satchuthananthavale Rasiah Kuhan Branavan.
S.M.
32
Sjöstrand, Björn. "Evaluation of Compression Testing and Compression Failure Modes of Paperboard : Video analysis of paperboard during short-span compression and the suitability of short- and long-span compression testing of paperboard." Thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper (from 2013), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-27519.
Full textAbstract:
The objectives of the thesis were to find the mechanisms that govern compression failures in paperboard and to find the link between manufacturing process and paperboard properties. The thesis also investigates two different test methods and evaluates how suitable they are for paperboard grades. The materials are several commercial board grades and a set of hand-formed dynamic sheets that are made to mimic the construction of commercial paperboard. The method consists of mounting a stereomicroscope on a short-span compression tester and recording the compression failure on video, long-span compression testing and standard properties testing. The observed failure modes of paperboard under compression were classified into four categories depending on the appearance of the failures. Initiation of failure takes place where the structure is weakest and fiber buckling happens after the initiation, which consists of breaking of fiber-fiber bonds or fiber wall delamination. The compression strength is correlated to density and operations and raw materials that increase the density also increases the compression strength. Short-span compression and Long-span compression are not suitable for testing all kinds of papers; the clamps in short-span give bulky specimens an initial geometrical shape that can affect the given value of compression strength. Long-span compression is only suitable for a limited range of papers, one problem with too thin papers are low wavelength buckling.
33
Moris, Izabela Cristina Mauricio. "Efeito de cargas compressivas oblíquas e da simulação de ciclos mastigatório sobre pilares para implantes cone morse." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/58/58131/tde-15022012-114656/.
Full textAbstract:
A literatura relata que a união osso/implante é extremamente confiável, porém limitações clínicas em relação à prótese ainda ocorrem. Recentemente foi proposto um pilar para implantes cone morse cujo desenho permite a escolha entre coroas cimentadas ou parafusadas, adicionalmente, este pilar também é apresentado em dois tamanhos, o convencional (ø 4,8 mm) e reduzido (ø 3,8 mm). O objetivo deste estudo foi avaliar a resistência à deformação dos pilares protéticos, a resistência de cimentação das coroas e os efeitos da simulação de ciclos mastigatórios sobre: adaptação marginal, perda de torque nos parafusos das coroas e perda de torque dos dois diferentes pilares. Para avaliar a resistência à deformação, 20 implantes/pilares com diâmetro de 4.8 e 3.8 foram submetidos à carga compressiva oblíqua. Para avaliar as outras situações, 40 implantes/pilares foram divididos nos seguintes grupos (N=10): G4.8P- pilar de 4.8 e coroas parafusadas; G4.8C-pilar de 4.8 e coroas cimentadas; G3.8P- pilar de 3.8 e coroas parafusadas; G3.8C- pilar de 3.8 e coroas cimentadas. Todas as coroas foram avaliadas em relação à adaptação marginal antes e após a simulação de ciclos mastigatórios e as coroas cimentadas foram submetidas ao teste de resistência à tração previamente ao ensaio. Os conjuntos foram submetidos a 300.000 ciclos de simulação de movimentos mastigatórios. A perda de torque das coroas parafusadas e de todos os pilares foi analisada antes a após o ensaio. Não houve diferenças significantes para a resistência à deformação entre os pilares; para a resistência de cimentação houve diferenças significantes entre os dois pilares (p≤0,05). Para a adaptação marginal houve diferenças significantes antes e após a simulação dos ciclos mastigatórios entre os grupos G3.8P (p=0,037) e G3.8C (p≤0,05); para a comparação da adaptação das coroas entre os pilares houve diferenças antes da simulação dos ciclos mastigatórios quando comparado os grupos 3.8C com 3.8P e antes e após da simulação quando comparado os grupos 4.8C com 4.8P, para as demais comparações não houve diferença. Quanto à perda de torque nos parafusos das coroas houve diferenças significantes antes e após a simulação dos ciclos mastigatórios para ambos os pilares, quanto às comparações entre os diferentes grupos antes e após a simulação de ciclos mastigatórios houve diferença apenas após (p=0,008) a simulação. Quanto à perda de torque para os pilares houve diferenças significantes apenas para o grupo 3.8C (p≤0,05) antes e após a simulação dos ciclos mastigatórios. Considerando as limitações deste estudo, conclui-se que em relação à resistência à deformação os pilares apresentaram valores próximos; quanto a retenção das coroas, cimentadas e parafusadas, os pilares de 4.8 foram estatisticamente superiores aos pilares de 3.8; a simulação de ciclos mastigatórios teve influência sobre a adaptação marginal das coroas e em relação a perda de torque dos pilares não foram encontradas diferenças estatísticas.Reports in the literature have stated that the bone/implant interface is extremely reliable. However, clinical limitations in relation to the prosthesis still occur. A Morse taper implant-abutment design that allows choosing between cemented or screwed crowns has been recently proposed. The abutment is presented in two different diameter sizes (conventional (ø 4.8 mm) and narrow (ø 3.8 mm). The aim of this study was to evaluate the resistance to deformation of the implant/abutment interface, the tensile strength of the cemented crowns and the effects of simulated chewing cycles on: marginal fit, crown-screw torque loss and torque loss of the two different abutments. To evaluate the resistance to deformation, 20 abutments with diameter of 4.8 and 3.8 were subjected to compressive oblique load. To evaluate the other situations, 40 implants/abutments were divided into the following groups (N = 10): G4.8P-abutment 4.8 with screwed crowns; G4.8C-abutment 4.8 with cemented crowns; G3.8P abutment 3.8 with screwed crows; G3.8C-abutment 3.8 with cemented crowns. All crowns were evaluated for marginal fit before and after simulation of the chewing cycles. The cemented crowns were subjected to tensile strength test before the simulated chewing cycles. The specimens were subjected to 300,000 cycles that simulated the chewing movements. The torque loss of the screwed crowns and all abutments were analyzed before and after the cycling tests. No significant differences were found for the deformation resistance between the abutments. No significant differences were found in the tensile strength of the cemented crowns between the two abutments (p≤0.05). The marginal fit of the crowns found no significant differences before and after the simulation of the chewing cycles between groups G3.8P (p = 0.037) and G3.8C (p≤0.05). No differences were found in crown misfit between the abutments before simulating the chewing cycles when compared between groups 3.8C 3.8P. No differences were found between groups 4.8C and 4.8P before and after the chewing simulation. Torque loss of the screwed crowns was not significantly different before and after the simulation of the chewing cycles for both abutments. Comparisons between the different groups before and after simulation found significant differences after the simulation of the chewing cycles (p = 0.008). Group 3.8C was the only group that presented significant differences (p≤0.05) before and after the simulation cycles. Within the limitations of this study, it can be concluded that the resistance to deformation between both abutments was similar. Retention of cemented and screwed crowns was statistically higher for the 4.8 abutments when compared to the 3.8 abutments. The simulation of chewing cycles significantly influenced the marginal fit of the crowns. No differences statistically significant in torque loss were found between the two abutments.
34
Poirier, Régis. "Compression de données pour le test des circuits intégrés." Montpellier 2, 2004. http://www.theses.fr/2004MON20119.
Full text
35
Khayat, Moghaddam Elham. "On low power test and low power compression techniques." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/997.
Full textAbstract:
With the ever increasing integration capability of semiconductor technology, today's large integrated circuits require an increasing amount of data to test them which increases test time and elevated requirements of tester memory.
At the same time, as VLSI design sizes and their operating frequencies continue to increase, timing-related defects are high proportion of the total chip defects and at-speed test is crucial. DFT techniques are widely used in order to improve the testability of a design. While DFT techniques facilitate generation and application of tests, they may cause the test vectors to contain non-functional states which result in higher switching activities compared to the functional mode of operation. Excessive switching activity causes higher power dissipation as well as higher peak supply currents. Excessive power dissipation may cause hot spots that could cause damage the circuit. Excessive peak supply currents may cause higher IR drops which increase signal propagation delays during test causing yield loss.
Several methods have been proposed to reduce the switching activity in the circuit under test during shift and capture cycles. While these methods reduce switching activity during test and eliminate the abnormal IR drop, circuits may now operate faster on the tester than they would in the actual system. For speed related and high resistance defect mechanisms, this type of undertesting means that the device could be rejected by the systems integrator or by the end consumer and thus increasing the DPPM of the devices. Therefore, it is critical to ensure that the peak switching activity generated during the two functional clock cycles of an at-speed test is as close as possible to the functional switching activity levels specified for the device.
The first part of this dissertation proposes a new method to generate test vectors that mimic functional operation from the switching activity point of view. It uses states obtained by applying a number of functional clock cycles starting from the scan-in state of a test vector to fill unspecified scan cells in test cubes. Experimental results indicate that for industrial designs, the proposed techniques can reduce the peak capture switching on average by 49% while keeping the quality of test very close to conventional ATPG.
The second part of this dissertation addresses IR-drop and power minimization techniques in embedded deterministic test environment. The proposed technique employs a controller that allows a given scan chain to be driven by either the decompressor or pseudo functional background. Experimental results indicate an average of 36% reduction in peak switching activity during capture using the proposed technique.
In the last part of this dissertation, a new low power test data compression scheme using clock gater circuitry is proposed to simultaneously reduce test data volume and test power by enabling only a subset of the scan chains in each test phase. Since, most of the total power during test is typically in clock tree, by disabling significant portion of clock tree in each test phase, significant reduction in the test power in both combinational logic and clock distribution network are achieved. Using this technique, transitions in the scan chains during both loading of test stimuli and unloading of test responses decrease which will permit increased scan shift frequency and also increase in the number of cores that can be tested in parallel in multi-core designs. The proposed method has the ability of decreasing, in a power aware fashion, the test data volume. Experimental results presented for industrial designs demonstrate that on average reduction factors of 2 and 4 in test data volume and test power are achievable, respectively.
36
Navickas, T. A., and S. G. Jones. "PULSE CODE MODULATION DATA COMPRESSION FOR AUTOMATED TEST EQUIPMENT." International Foundation for Telemetering, 1991. http://hdl.handle.net/10150/612065.
Full textAbstract:
International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, NevadaDevelopment of automated test equipment for an advanced telemetry system requires continuous monitoring of PCM data while exercising telemetry inputs. This requirements leads to a large amount of data that needs to be stored and later analyzed. For example, a data stream of 4 Mbits/s and a test time of thirty minutes would yield 900 Mbytes of raw data. With this raw data, information needs to be stored to correlate the raw data to the test stimulus. This leads to a total of 1.8 Gb of data to be stored and analyzed. There is no method to analyze this amount of data in a reasonable time. A data compression method is needed to reduce the amount of data collected to a reasonable amount. The solution to the problem was data reduction. Data reduction was accomplished by real time limit checking, time stamping, and smart software. Limit checking was accomplished by an eight state finite state machine and four compression algorithms. Time stamping was needed to correlate stimulus to the appropriate output for data reconstruction. The software was written in the C programming language with a DOS extender used to allow it to run in extended mode. A 94 - 98% compression in the amount of data gathered was accomplished using this method.
37
Langiu, Alessio. "Optimal Parsing for dictionary text compression." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1091/document.
Full textAbstract:
Les algorithmes de compression de données basés sur les dictionnaires incluent une stratégie de parsing pour transformer le texte d'entrée en une séquence de phrases du dictionnaire. Etant donné un texte, un tel processus n'est généralement pas unique et, pour comprimer, il est logique de trouver, parmi les parsing possibles, celui qui minimise le plus le taux de compression finale. C'est ce qu'on appelle le problème du parsing. Un parsing optimal est une stratégie de parsing ou un algorithme de parsing qui résout ce problème en tenant compte de toutes les contraintes d'un algorithme de compression ou d'une classe d'algorithmes de compression homogène. Les contraintes de l'algorithme de compression sont, par exemple, le dictionnaire lui-même, c'est-à-dire l'ensemble dynamique de phrases disponibles, et combien une phrase pèse sur le texte comprimé, c'est-à-dire quelle est la longueur du mot de code qui représente la phrase, appelée aussi le coût du codage d'un pointeur de dictionnaire. En plus de 30 ans d'histoire de la compression de texte par dictionnaire, une grande quantité d'algorithmes, de variantes et d'extensions sont apparus. Cependant, alors qu'une telle approche de la compression du texte est devenue l'une des plus appréciées et utilisées dans presque tous les processus de stockage et de communication, seuls quelques algorithmes de parsing optimaux ont été présentés. Beaucoup d'algorithmes de compression manquent encore d'optimalité pour leur parsing, ou du moins de la preuve de l'optimalité. Cela se produit parce qu'il n'y a pas un modèle général pour le problème de parsing qui inclut tous les algorithmes par dictionnaire et parce que les parsing optimaux existants travaillent sous des hypothèses trop restrictives. Ce travail focalise sur le problème de parsing et présente à la fois un modèle général pour la compression des textes basée sur les dictionnaires appelé la théorie Dictionary-Symbolwise et un algorithme général de parsing qui a été prouvé être optimal sous certaines hypothèses réalistes. Cet algorithme est appelé Dictionary-Symbolwise Flexible Parsing et couvre pratiquement tous les cas des algorithmes de compression de texte basés sur dictionnaire ainsi que la grande classe de leurs variantes où le texte est décomposé en une séquence de symboles et de phrases du dictionnaire. Dans ce travail, nous avons aussi considéré le cas d'un mélange libre d'un compresseur par dictionnaire et d'un compresseur symbolwise. Notre Dictionary-Symbolwise Flexible Parsing couvre également ce cas-ci. Nous avons bien un algorithme de parsing optimal dans le cas de compression Dictionary-Symbolwise où le dictionnaire est fermé par préfixe et le coût d'encodage des pointeurs du dictionnaire est variable. Le compresseur symbolwise est un compresseur symbolwise classique qui fonctionne en temps linéaire, comme le sont de nombreux codeurs communs à longueur variable. Notre algorithme fonctionne sous l'hypothèse qu'un graphe spécial, qui sera décrit par la suite, soit bien défini. Même si cette condition n'est pas remplie, il est possible d'utiliser la même méthode pour obtenir des parsing presque optimaux. Dans le détail, lorsque le dictionnaire est comme LZ78, nous montrons comment mettre en œuvre notre algorithme en temps linéaire. Lorsque le dictionnaire est comme LZ77 notre algorithme peut être mis en œuvre en temps O (n log n) où n est le longueur du texte. Dans les deux cas, la complexité en espace est O (n). Même si l'objectif principal de ce travail est de nature théorique, des résultats expérimentaux seront présentés pour souligner certains effets pratiques de l'optimalité du parsing sur les performances de compression et quelques résultats expérimentaux plus détaillés sont mis dans une annexe appropriéeDictionary-based compression algorithms include a parsing strategy to transform the input text into a sequence of dictionary phrases. Given a text, such process usually is not unique and, for compression purpose, it makes sense to find one of the possible parsing that minimizes the final compression ratio. This is the parsing problem. An optimal parsing is a parsing strategy or a parsing algorithm that solve the parsing problem taking account of all the constraints of a compression algorithm or of a class of homogeneous compression algorithms. Compression algorithm constrains are, for instance, the dictionary itself, i.e. the dynamic set of available phrases, and how much a phrase weight on the compressed text, i.e. the length of the codeword that represent such phrase also denoted as the cost of a dictionary pointer encoding. In more than 30th years of history of dictionary based text compression, while plenty of algorithms, variants and extensions appeared and while such approach to text compression become one of the most appreciated and utilized in almost all the storage and communication process, only few optimal parsing algorithms was presented. Many compression algorithms still leaks optimality of their parsing or, at least, proof of optimality. This happens because there is not a general model of the parsing problem that includes all the dictionary based algorithms and because the existing optimal parsings work under too restrictive hypothesis. This work focus on the parsing problem and presents both a general model for dictionary based text compression called Dictionary-Symbolwise theory and a general parsing algorithm that is proved to be optimal under some realistic hypothesis. This algorithm is called Dictionary-Symbolwise Flexible Parsing and it covers almost all the cases of dictionary based text compression algorithms together with the large class of their variants where the text is decomposed in a sequence of symbols and dictionary phrases.In this work we further consider the case of a free mixture of a dictionary compressor and a symbolwise compressor. Our Dictionary-Symbolwise Flexible Parsing covers also this case. We have indeed an optimal parsing algorithm in the case of dictionary-symbolwise compression where the dictionary is prefix closed and the cost of encoding dictionary pointer is variable. The symbolwise compressor is any classical one that works in linear time, as many common variable-length encoders do. Our algorithm works under the assumption that a special graph that will be described in the following, is well defined. Even if this condition is not satisfied it is possible to use the same method to obtain almost optimal parses. In detail, when the dictionary is LZ78-like, we show how to implement our algorithm in linear time. When the dictionary is LZ77-like our algorithm can be implemented in time O(n log n). Both have O(n) space complexity. Even if the main aim of this work is of theoretical nature, some experimental results will be introduced to underline some practical effects of the parsing optimality in compression performance and some more detailed experiments are hosted in a devoted appendix
38
Liu, Yingdi. "Design for test methods to reduce test set size." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6459.
Full textAbstract:
With rapid development in semiconductor technology, today's large and complex integrated circuits require a large amount of test data to achieve desired test coverage. Test cost, which is proportional to the size of the test set, can be reduced by generating a small number of highly effective test patterns. Automatic Test Pattern Generators (ATPGs) generate effective deterministic test patterns for different fault models and can achieve high test coverage. To reduce ATPG-produced test set size, design for test (DFT) methods can be used to further improve the ATPG process and apply generated test patterns in more efficient ways.
The first part of this dissertation introduces a test point insertion (TPI) technique that reduces the test pattern counts and test data volume of a design by adding additional hardware called control points. These dedicated control points are inserted at internal nodes of the design to resolve large internal conflicts during ATPG. Therefore, more faults can be detected by a single test pattern. To minimize silicon area needed to implement these control points, we propose a method that reuses some existing functional flip-flops as drivers of the control points, instead of inserting dedicated flip-flops for the control points. Experimental results on industrial designs indicate that the proposed technique can achieve significant test pattern reductions, similar to the control points using dedicated flip-flops.
The second part of this dissertation proposes a staggered ATPG scheme that produces deterministic test-per-clock-based staggered test patterns by using dedicated compactor scan chains to capture additional test responses during scan shift cycles that are used for regular scan cells to completely load each test pattern. These compactor scan chains are formed by dedicated capture-per-cycle observation test points inserted at suitable locations of the design. By leveraging this new scan infrastructure, more compacted test patterns can be generated, and more faults can also be systematically detected during the simulation process, thus reducing the overall test pattern count.
To meet the stringent test requirements for in-system test (especially for automotive test), a built-in self-test (BIST) approach, called Stellar BIST, is introduced in the last part of this dissertation. Stellar BIST employs a dedicated BIST infrastructure with additional on-system memory to store some parent test patterns (seeds). Derivative test patterns can be obtained by complementing selected bits of corresponding parent patterns through an on-chip Stellar BIST controller. A dedicated ATPG process is also proposed for generating a minimal set of test patterns that need to be stored and their effective derivative patterns that require short test application time. Furthermore, the proposed scheme can provide flexible trade-offs between stored test data volume and test application time.
39
Dalmasso, Julien. "Compression de données de test pour architecture de systèmes intégrés basée sur bus ou réseaux et réduction des coûts de test." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20061/document.
Full textAbstract:
Les circuits intégrés devenant de plus en plus complexes, leur test demande des efforts considérables se répercutant sur le coût de développement et de production de ces composants. De nombreux travaux ont donc porté sur la réduction du coût de ce test en utilisant en particulier les techniques de compression de données de test. Toutefois ces techniques n'adressent que des coeurs numériques dont les concepteurs détiennent la connaissance de toutes les informations structurelles et donc en pratique n'adressent que le test de sous-blocs d'un système complet. Dans cette thèse, nous proposons tout d'abord une nouvelle technique de compression des données de test pour les circuits intégrés compatible avec le paradigme de la conception de systèmes (SoC) à partir de fonctions pré-synthétisées (IPs ou coeurs). Puis, deux méthodes de test des systèmes utilisant la compression sont proposées. La première est relative au test des systèmes SoC utilisant l'architecture de test IEEE 1500 (avec un mécanisme d'accès au test de type bus), la deuxième concerne le test des systèmes pour lesquels la communication interne s'appuie sur des structures de type réseau sur puce (NoC). Ces deux méthodes utilisent conjointement un ordonnancement du test des coeurs du système avec une technique de compression horizontale afin d'augmenter le parallélisme du test des coeurs constituant le système et ce, à coût matériel constant. Les résultats expérimentaux sur des systèmes sur puces de référence montrent des gains de l'ordre de 50% sur le temps de test du système completWhile microelectronics systems become more and more complex, test costs have increased in the same way. Last years have seen many works focused on test cost reduction by using test data compression. However these techniques only focus on individual digital circuits whose structural implementation (netlist) is fully known by the designer. Therefore, they are not suitable for the testing of cores of a complete system. The goal of this PhD work was to provide a new solution for test data compression of integrated circuits taking into account the paradigm of systems-on-chip (SoC) built from pre-synthesized functions (IPs or cores). Then two systems testing method using compression are proposed for two different system architectures. The first one concerns SoC with IEEE 1500 test architecture (with bus-based test access mechanism), the second one concerns NoC-based systems. Both techniques use test scheduling methods combined with test data compression for better exploration of the design space. The idea is to increase test parallelism with no hardware extra cost. Experimental results performed on system-on-chip benchmarks show that the use of test data compression leads to test time reduction of about 50% at system level
40
Ong, Ghim Hwee. "Text compression for transmission and storage." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/13790.
Full textAbstract:
The increasing use of computers for document preparation and publishing coupled with a growth in the general information management facilities available on computers has meant that most documents exist in computer processable form during their lifetime. This has led to a substantial increase in the demand for data storage facilities, which frequently seems to exceed the provision of storage facilities, despite the advances in storage technology. Furthermore, there is growing demand to transmit these textual documents from one use to another, rather than use a printed form for transfer between sites which then needs to be re-entered into a computer at the receiving site. Transmission facilities are, however, limited and large documents can be difficult and expensive to transmit. Problems of storage and transmission capacity can be alleviated by compacting the textual information beforehand, providing that there is no loss of information in this process. Conventional compaction techniques have been designed to compact all forms of data (binary as well as text) and have, predominantly, been based on the byte as the unit of compression. This thesis investigates the alternative of designing a compaction procedure for natural language texts, using the textual word as the unit of compression. Four related alternative techniques are developed and analysed in the thesis. These are designed to be appropriate for different circumstances where either maximum compression or maximum point to point transmission speed is of greatest importance, and where the characteristics of the transmission, or storage, medium may be oriented to a seven or eight bit data unit. The effectiveness of the four techniques is investigated both theoretically and by practical comparison with a widely used conventional alternative. It is shown that for a wide range of textual material the word based techniques yield a greater compression and require substantially less processing time.
41
Zacharia, Nadime. "Compression and decompression of test data for scan based designs." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20218.
Full textAbstract:
Traditional methods to test integrated circuits (ICs) require enormous amount of memory, which make them increasingly expensive and unattractive. This thesis addresses this issue for scan-based designs by proposing a method to compress and decompress input test patterns. By storing the test patterns in a compressed format, the amount of memory required to test ICs can be reduced to manageable levels. The thesis describes the compression and decompression scheme in details. The proposed method relies on the insertion of a decompression unit on the chip. During test application, the patterns are decompressed by the decompression unit as they are applied. Hence, decompression is done on-the-fly in hardware and does not slow down test application.The design of the decompression unit is treated in depth and a design is proposed that minimizes the amount of extra hardware required. In fact, the design of the decompression unit uses flip-flops already on the chip: it is implemented without inserting any additional flip-flops.
The proposed scheme is applied in two different contexts: (1) in (external) deterministic-stored testing, to reduce the memory requirements imposed on the test equipment; and (2) in built-in self test, to design a test pattern generator capable of generating deterministic patterns with modest area and memory requirements.
Experimental results are provided for the largest ISCAS'89 benchmarks. All of these results point to show that the proposed technique greatly reduces the amount of test data while requiring little area overhead. Compression factors of more than 20 are reported for some circuits.
42
Pateras, Stephen. "Correlated and cube-contained random patterns : test set compression techniques." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70300.
Full textAbstract:
Two novel methods to reduce the number of random test patterns required to fully test a circuit are proposed in this thesis. In the concept of correlated random patterns, reductions in a circuit's random pattern test length are achieved by taking advantage of correlations measured between values applied at different input positions in a complete deterministic test set. Instead of being generated independently, correlated inputs have their random values generated from a common source with each input's value then individually biased at a rate necessary to match the measured correlation. In the concept of cube-contained random patterns, reductions in random pattern test lengths are achieved by the successive assignment of temporarily fixed values to selected inputs during the random pattern generation process.The concepts of correlated and cube-contained random patterns can be viewed as methods to compress a deterministic test set into a small amount of information which is then used to control the generation of a superset of the deterministic test set. The goal is to make this superset as small as possible while maintaining its containment of the original test set. The two concepts are meant to be used in either a Built-In Self-Test (BIST) environment or with an external tester when the storage requirements of a deterministic test are too large.
Experimental results show that both correlated and cube-contained random patterns can achieve 100% fault coverage of synthesized circuits using orders or magnitude less patterns than when equiprobable random patterns are used.
43
Zacharia, Nadime. "Compression and decompression of test data for scan-based designs." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0004/MQ44048.pdf.
Full text
44
Hsu, Ting-Yu, and 許庭瑜. "Compressive Strength Comparisons of Equal Angles-Theory、Specification and Test." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4u77na.
Full textAbstract:
碩士國立中興大學
土木工程學系所
107
Steel single angles are widely used in a variety of steel structures, connected with gusset plate by bolts. When single angles under eccentric load, the mechanical behavior is complicated due to the section is asymmetric. For most structural engineers, the design of an eccentrically loaded equal angle was considered to be a formidable task prior to the publication of the 2005 AISC Specification for structural steel buildings. This study intends to use the AISC (2005, 2010 and 2016) formulas to deal with equal angles. Compare AISC Specification 2016 with previous versions. Use equal angle section L5×5×5/16 as example to illustrate the analysis and design of the basic concepts of equal angles. Compare the compressive strengths among different loaded positions, which are concentrically loaded and eccentrically loaded. Use the simplified method provided by AISC Specification to calculate compressive strengths and compare the results with AISC Specification results. This study uses Bathon test results with equal angle section L5×5×5/16. Eplore the difference of Bathon tests and AISC results. Calculate the values which eccentrically loaded applied at point according to AISC (2005, 2010 and 2016), and compare with Bathon test results. This study uses a variety of methods for the analysis of the equal angles. The results are compared with the Bathon experimental values. It was found that the experimental values are significantly higher than the AISC design ones. This result is in line with industry expectations.
45
Chen, Sin-An, and 陳信安. "Compressive Strength Comparisons of Unequal Angles-Theory, Specification and Test." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/48w245.
Full textAbstract:
碩士國立中興大學
土木工程學系所
107
As the section of steel unequal angles is asymmetric, unequal angles are often used as second members. When single angles under eccentric load, the mechanical behavior is complicated due to the section is asymmetric. For most structural engineers, the design of an eccentrically loaded unequal angle was considered to be a formidable task prior to the publication of the 2005 AISC Specification for structural steel buildings. This study intends to use the AISC (2005, 2010 and 2016) formulas to deal with unequal angles. Compare AISC 2016 with previous versions. The provided examples are furnished to indicate the analysis and design of the basic concepts of unequal angles. This study explores the difference of Bathon tests and AISC results. Calculate the values which eccentric load applied at point according to AISC (2005, 2010 and 2016), and compare with Bathon test results. Analysis are made between a variety of methods of the unequal angles. It was found that the AISC design experimental values are significantly lower than the experimental values, which means the result is in line with industry expectations.
46
Shahirnia, Meisam. "Deformation Behaviour of TiNi Shape Memory Alloys under Tensile and Compressive Loads." 2011. http://hdl.handle.net/10222/13883.
Full textAbstract:
TiNi shape memory alloys (SMAs) have been extensively used in various applications. The great interest in TiNi alloys is due to its unique shape memory and superelasticity effects, along with its superior wear and dent resistance. Shape memory and superelastic effects are due to a reversible martensitic transformation that can be induced either thermally or mechanically. In this study, indentation tests at different temperatures, loads and strain rates have been performed on superelastic TiNi alloy. Deformation characteristics of superelastic TiNi under indentation have been compared to AISI 304 steel as a conventional material. Also, in-situ optical microscopy tests with interrupted heating have been employed in order to gain an insight into the coupled deformation and reversible martensitic transformation behaviour of TiNi SMAs under tensile loads. An understanding of the impacts of strain rate and temperature on the deformation behaviour of TiNi SMAs under localized compressive loads has been proposed.
47
Fu, Zhe-Xian, and 傅哲賢. "COMPARING TENSILE AND COMPRESSIVE BEARING BEHAVIRS OF PILE IN SAND BY MODEL TEST." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/93786778253764222517.
Full textAbstract:
碩士國立中央大學
土木工程研究所
95
This paper presents the results of model test for tensile and compressive bearing behavior of pile in sands. A model pile was statically pushed into a dry sand or a saturated sand, then, there are two kinds of pile load tests were performed. One is the pile was loaded first in compression and then loaded in tension, and then the compression-tension load cycle was repeated five times. The other case is the pile was loaded first in tension and then loaded in compression, and then the tension-compression load cycle was repeated five times. The measured end-bearing capacity and skin friction of the piles in tension and compression were then compared. The tension-compression capacity and friction of the pile varies with the pile head displacement. The larger the displacement, the smaller the ratio. It is found that the friction increases from the top to the bottom for tensile pile, however, the frictions at the top and bottom are smaller than the friction at the middle part for compressive pile.
48
CHEN, YI-MIN, and 陳宜旻. "Applying Artificial Intelligence to Improve Ultrasonic Pulse Velocity Test in Determining Concrete Compressive Strength." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/00906193816315945596.
Full textAbstract:
碩士國立高雄應用科技大學
土木工程與防災科技研究所
104
In the construction industry, using non-destructive testing (NDT) methods (Ultrasonic Pulse Velocity Test, UPV) to examine the compressive strength of the concrete is quite economical and feasible. Without damaging the structure, it can effectively evaluate the uniformity and relative quality of concrete structures. Ultrasonic Pulse Velocity has some advantages such as the low cost, easier to operate and convenient to carry. But, using UPV test to estimate concrete compressive strength have an average of over 20% mean absolute percentage error (MAPE) when comparing to the actual compressive strength obtained by destructive the tests. As a result, this research collected a total of 312 sample data from a material testing laboratory in Chia-Yi. The collected data are used to train and validate the concrete strength prediction model developed by this research. Firstly, linear and nonlinear regression prediction models are developed and then three artificial intelligence techniques, artificial neural network (ANN), support vector machine (SVM) and adaptive neural fuzzy inference system (ANFIS), are adopted to develop the AI prediction models. The objective is to establish a best prediction model for the UPV test. The results show that both of the MAPEs for the linear and nonlinear regression models are 11.17% and 17.66% respectively. The MAPEs for ANFIS, ANN and SVM models are 9.86%, 10.94% and 10.495% respectively. The research results can provide valuable information when UPV tests are used to estimate concrete compressive strength.
49
Chen, Jou-Wen, and 陳柔文. "Finite Element Evaluation for Lumbar Disc Prostheses with the Application of Compressive-Shearing Test Method." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/90102317864924938253.
Full textAbstract:
碩士國立陽明大學
醫學工程研究所
100
Security verifications with international testing standards before marketing are essential for orthopaedic implants. Lumbar disc prosthesis, as a non-fusion implant for treatment of degenerated lumbar intervertebral disc, has met the basic biomechanical requirements through the examination with ASTM F-2646. It has been claimed that the defined testing conditions in ASTM standard cannot include all the possible situations after implantation, thus failures of disc prostheses in clinical practice may be the evidences that the current testing method may be a perfect way. A modified compressive-shearing test (MCS test), based on ASTM standard, has been developed utilized for evaluating the security of polyethylene (PE) component in disc prosthesis. However, loading conditions in the MCS test have not been completely evaluated, neither has the comparison between the MCS test and ASTM standard been performed. Purpose of current study was to accomplish a more completed finite element evaluation to the MCS test method with 2 commercial lumbar disc prostheses, and also compared with traditional ASTM standard testing method to confirm the differences between the methods. The values and distributions of von Mises stresses on PE components were considered as the main mechanical parameter for evaluation. Results revealed that, lower resultant force was required for PE component failure in the MCS test method than the ASTM standard testing method. With the application of MCS test method, the mechanical safe zones can be respectively defined for the different prosthetic disc designs. Current study has accomplished more detailed evaluations of the MCS test method, and represented that the mechanical failure of PE component in lumbar disc prosthesis can be more conservatively evaluated using the MCS test method than the ASTM standard testing method. The MCS test method can be beneficial for future lumbar disc prosthesis in the early stage of its designing process.
50
Yang, Xiaoxia. "Establishing an acoustic emission detecting system and its application in compressive test for composite materials." 1992. http://catalog.hathitrust.org/api/volumes/oclc/31733668.html.
Full textAbstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1992.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 81-84).