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Dissertations / Theses on the topic 'Stressed state'
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1
Paquin, Normand. "Electron transport in uniaxially stressed silicon MOSFETs." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257213.
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Hadzhiyski, Vilhelm, and Zviatko Atanasov. "Investigation of stressed state of elastic element of elastic clutch from three ply reinforced polymer material." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-228801.
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The use of composite materials in engineering practice and in particular nonmetallic composite materials in the preparation of elastic couplings (clutches) requires modeling of their mechanical behavior. The production of elastic couplings with a elastic element having reinforced polymer materials require studying the behavior of those materials for loads which are typical for their operation. In many modern structures of elastic clutches are used multilayer reinforced composites. This kind of materials are composed of separate layers with different orientation of reinforcing fibers. Several authors have studied the behavior of this type of laminated materials (Yongming L. 2005, Zhang Y.X., 2009). Factors,which determine the stress and deformation state of this type of elastic elements are:
— structure and mechanical characteristics
— matrix and reinforced material
— connection between matrix and reinforced material
— orientation of reinforcement.
The aim of this paper is to investigate stress and strain state of elastic element of coupling, creating a model for determination of the state of threelayers nonmetallic material for manufacturing of nonmetallic elastic elements.
3
Hadzhiyski, Vilhelm, and Zviatko Atanasov. "Investigation of stressed state of elastic element of elastic clutch from three ply reinforced polymer material." TUDpress - Verlag der Wissenschaften GmbH, 2012. https://tud.qucosa.de/id/qucosa%3A30531.
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The use of composite materials in engineering practice and in particular nonmetallic composite materials in the preparation of elastic couplings (clutches) requires modeling of their mechanical behavior. The production of elastic couplings with a elastic element having reinforced polymer materials require studying the behavior of those materials for loads which are typical for their operation. In many modern structures of elastic clutches are used multilayer reinforced composites. This kind of materials are composed of separate layers with different orientation of reinforcing fibers. Several authors have studied the behavior of this type of laminated materials (Yongming L. 2005, Zhang Y.X., 2009). Factors,which determine the stress and deformation state of this type of elastic elements are:
— structure and mechanical characteristics
— matrix and reinforced material
— connection between matrix and reinforced material
— orientation of reinforcement.
The aim of this paper is to investigate stress and strain state of elastic element of coupling, creating a model for determination of the state of threelayers nonmetallic material for manufacturing of nonmetallic elastic elements.
4
Andreev, A. A., S. N. Grigorev, O. V. Sobol, M. A. Volosova, V. A. Stolbovoy, and V. Ye Filchikov. "Structural-phase and Strained State of Vacuum-ARC Mo-N Coatings." Thesis, Сумський державний університет, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34806.
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The effect of substrate bias on the structural-phase and elastic stress-strained state during the formation
of vacuum-arc deposited nanostructural coatings of the Mo–N system has been studied. An increase
in the bias potential leads to (i) predominant [111] orientation of the growing molybdenum nitride
crystals with a NaCl-type cubic lattice (γ-Mo2N phase) and (ii) the appearance of a second phase with a
body-centered cubic crystal lattice that is characteristic of pure molybdenum. The elastically strained
(stressed) state of the coating is determined not only by the conditions of deposition, but also by the mechanical
properties of a substrate. In order to provide for formation of coatings in a high-elastic-strained
(stressed) state, it is necessary to deposit coatings onto substrates with high elastic modulus, which prevent
metal flow at the interface.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34806
5
Váša, Jiří. "Návrh přemostění komunikace." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392093.
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The diploma thesis deals with the design of the motorway bridge over the II / 464 road between Butovice-Bílovec. For the bridging design four variants were made, from which a variant of the slab with longitudinal extensions was selected for further processing. The design assessment was performed for the ultimate limit state and serviceability limit state according to valid standards. Determination of internal forces was performed on the model developed in Scia Engineer 18.0.
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Matuška, Vojtěch. "Porovnání variant nádrže ČOV z železobetonu a z předpjatého betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409800.
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The diploma thesis deals with design and comparison of variants of cast-in-place concrete sewage tank made from reinforced concrete and pre-stressed concrete. The layout of sewage tank is rectangular. The tank is in longitudinal way divided into two chambers. The tank is not roofed and is partialy embedded in the ground. The design for ultimate limit state and for service limit state is made for both variants. There is focus on generation and development of cracks in service limit state. For calcuation of internal forces is used model made in software SCIA Engineer, based on finite element method. The reinforced concrete and pre-stressed concrete versions are compared in last part in term of volumes of materials needed. Also there are proposed possible savings.
7
Arnett, Sarah B. "Fiscal Stress in the U.S. States: An Analysis of Measures and Responses." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/pmap_diss/38.
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Fiscal stress is an important and recurring problem that states face. Research to date on state fiscal stress involves, predominantly, cross-sectional and case study analyses and does not address the effectiveness of state responses. Many of these studies use different definitions and measures of fiscal stress compounding the difficulty of comparing fiscal stress findings. The present research effort adds to the fiscal stress literature by (1) clarifying the meaning of fiscal stress in the state context, (2) developing a measure of fiscal stress that operationalizes this meaning and is comparable across units, and 3) using this measure analyzes patterns in and the effectiveness of state responses. Fiscal stress is measured using four indexes: budget, cash, long-run, service-level. Eleven financial indicators, calculated using data from state Comprehensive Annual Financial Reports (CAFRs), are used to create these indexes for all fifty states for the years 2002-2009. Descriptive analysis compares state fiscal stress levels (grouped into low, moderate, and high fiscal stress by cluster analysis) to state economic growth rates, state responses, and institutional factors yielding several findings. First, states do not use an incremental or punctuated equilibrium strategy in responding to fiscal stress; nor do their responses follow the pattern predicted by Cutback Management theory. Second, institutional factors affect both the levels of fiscal stress and state responses to fiscal stress. Regression analysis supports and extends these findings. First, short-term responses of expenditure cuts, tax increases, and rainy day fund use do not affect state fiscal stress levels. Second, these responses have long-term effects on fiscal stress levels. A major implication of this research is that there is very little states can do in the short-term to reduce fiscal stress. However, by balancing expenditures and revenues states can set themselves up to weather the next economic downturn with lower levels of fiscal stress.
8
Svoboda, Tomáš. "Most přes údolí potoka Kyselá voda." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227255.
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The subject of the diploma thesis is the design of the ghrinder bridge over the Kyselá voda brook valley. The main topic is static calculation of supporting construction of six span structure. Two studies were executed and the second option, pre-stressed girder bridge was chosen. The lenght of the spans is 27 + 6 x 35 + 27 m. Static model and effect of loading are solved in software Scia Engineer. Reviews are calculated by hand according to current standards.
9
Navrátil, Tomáš. "Most přes Knovízský potok." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240311.
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The subject of the diploma thesis is the design of the ghrinder bridge over the Knovízský potok brook valley. The main topic is static calculation of supporting construction of five span structure. Three studies were executed and one of them, pre-stressed girder bridge was chosen. The langht of the spans is 27 + 3 x 32 + 27 m. Static model and effect of loading are solved in software Scia Engineer. Reviews are caltulated by hand according to current standards.
10
Arnett, Sarah. "Fiscal stress in the U.S. states: an analysis of measures and responses." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42860.
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Fiscal stress is an important and recurring problem that states face. Research to date on state fiscal stress involves, predominantly, cross-sectional and case study analyses and does not address the effectiveness of state responses. Many of these studies use different definitions and measures of fiscal stress compounding the difficulty of comparing fiscal stress findings. The present research effort adds to the fiscal stress literature by (1) clarifying the meaning of fiscal stress in the state context, (2) developing a measure of fiscal stress that operationalizes this meaning and is comparable across units, and 3) using this measure analyzes patterns in and the effectiveness of state responses. Fiscal stress is measured using four indexes: budget, cash, long-run, service-level. Eleven financial indicators, calculated using data from state Comprehensive Annual Financial Reports (CAFRs), are used to create these indexes for all fifty states for the years 2002-2009. Descriptive analysis compares state fiscal stress levels (grouped into low, moderate, and high fiscal stress by cluster analysis) to state economic growth rates, state responses, and institutional factors yielding several findings. First, states do not use an incremental or punctuated equilibrium strategy in responding to fiscal stress; nor do their responses follow the pattern predicted by Cutback Management theory. Second, institutional factors affect both the levels of fiscal stress and state responses to fiscal stress. Regression analysis supports and extends these findings. First, short-term responses of expenditure cuts, tax increases, and rainy day fund use do not affect state fiscal stress levels. Second, these responses have long-term effects on fiscal stress levels. A major implication of this research is that there is very little states can do in the short-term to reduce fiscal stress. However, by balancing expenditures and revenues states can set themselves up to weather the next economic downturn with lower levels of fiscal stress.
11
Fernandez, Americo Leon. "Tomographic imaging the state of stress." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20698.
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Duda, Tomáš. "Statické řešení střešní konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226743.
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The subject of the diploma thesis is the design and static analysis of roof structure. It is prestressed roof shell (membrane) supported by a cable. The whole thesis is divided into several separated units according to task's specification. The text section describes the introduction to the issue of presstressed suspension cable constructions and displays their possible shapes, types and realizations. There is also technical report of solved shell, which was written on the base of the documents, drawn drawings and structural (static) analysis.
13
Carolina, Löf. "Att mäta stress : Adaptering och validering av Dundee Stress State Questionnaire." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157318.
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Studien hade till syfte att adaptera och validera den multidimensionella stressenkäten Dundee Stress State Questionnaire (DSSQ) som mäter stress utifrån 12 skalor som sammanfaller kring tre högre dimensioner: uppgiftsfokus, ångest och oro. DSSQ adapteras från originalspråket, engelska, till svenska. Tillämpbarheten för den svenska versionen av DSSQ undersöks genom att studera enkätens reliabilitet och validitet samt genom att tillämpa enkäten i två olika kontext, där två olika typer av uppgifter genomförs, ett arbetsminnestest och en polisstudentövning. Sammantaget visade resultatet att den svenska adaptionen av DSSQ har en hög reliabilitet. Dock gick det inte att bekräfta att den svenska adaptionen av DSSQ bibehåller samma faktormodell som originalversionen av DSSQ. Den statistiska analysen visade att de förändringar som identifierats i deltagarnas sinnesstämning delvis stämmer överens med tidigare forskning. Slutsatsen är att fler deltagare behövs för att validera faktormodellen hos den svenska adaptionen av DSSQ och den svenska adaptionen av DSSQ anses vara tillämpar i forskning då den visar på god reliabilitet.<br>The purpose of this study was to adapt and validate the Dundee Stress State Questionnaire (DSSQ), which measures stress based on 12 scales that cohere around three higher order dimensions: task engagement, distress and worry. DSSQ is adapted from its original language, English, to Swedish. The applicability of the Swedish version of DSSQ is tested by studying the questionnaire's reliability and validity, and by applying the survey in two different contexts, where two different tasks are performed, a work memory task and a police student exam task. Overall, the result showed that the Swedish adaptation of DSSQ has high reliability. However, it was not possible to confirm that the Swedish adaptation of DSSQ maintained the same factor model as the original DSSQ has. The statistical analysis showed the changes identified in the participants' moods partly in lines with previous research. The conclusion is that more participants are needed to validate the factor model for the Swedish adaptation of DSSQ and since the Swedish adaptation of DSSQ shows good reliability, it can be applied in research.
14
Djabella, Hocine. "Finite element analysis of elastic stresses in coated surfaces." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334019.
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15
Yelbay, Hasan Ilker. "Determination Of Residual Stress State In Steel Weldments." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610657/index.pdf.
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The purpose of this study is to estimate the residual stress state in steel weldments by using Magnetic Barkhausen Noise (MBN) technique. For obtaining accurate, fast and continuous residual stress measurements a set up for single pass welded plates was designed and used. In order to convert the MBN values to residual stress values a calibration set up was also designed and a procedure for obtaining calibration curves was developed. After welding of low-C steel plates, residual stresses on heat affected zone (HAZ) and parent metal were measured by MBN technique. The results were verified by the hole drilling method. Microstructural investigation and hardness measurements were also conducted.
16
Barsoum, Imad. "The effect of stress state in ductile failure." Doctoral thesis, Stockholm : Hållfasthetslära, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4667.
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Wellons, Stefanie C., and David A. Ph D. Washburn. "Task-Demand Effects on Self-reported Stress State." Digital Archive @ GSU, 2010. http://digitalarchive.gsu.edu/psych_hontheses/9.
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18
Shea, William Thomas. "The state of stress associated with overthrust faulting." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37853.
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19
Laughton, Lorraine Rosemary. "Teacher-stress in South African state high schools." Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1005865.
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20
Malm, Richard. "Shear cracks in concrete structures subjected to in-plane stresses." Licentiate thesis, KTH, Civil and Architectural Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4215.
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<p>After only two years of service, extensive cracking was found in the webs of two light-rail commuter line bridges in Stockholm, the Gröndal and Alvik bridges. Due to this incident it was found necessary to study the means available for analysing shear cracking in concrete structures subjected to in-plane stresses. The aim of this PhD project is to study shear cracking with these two bridges as reference. In this thesis, the first part aims to study the possibility of using finite element analysis as a tool for predicting shear cracking for plane state stresses. The second part is concerning how the shear cracks are treated in the concrete design standards.</p><p>Shear cracking in reinforced beams has been studied with non-linear finite element analyses. In these analyses the shear cracking behaviour was compared to experiments conducted to analyse the shear failure behaviour. Finite element analyses were performed with two different FE programs Abaqus and Atena. The material model used in Atena is a smeared crack model based on damage and fracture theory with either fixed or rotated crack direction. The material model used in Abaqus is based on plasticity and damage theory. The fixed crack model in Atena and the model in Abaqus gave good results for all studied beams. For the two studied deep beams with flanges the results from the rotated crack model were almost the same as obtained with the fixed crack model. The rotated crack model in Atena gave though for some beams a rather poor estimation of the behaviour.</p><p>The calculation of crack widths of shear cracks has been studied for the long-term load case in the serviceability state for the Gröndal and Alvik bridges, with the means available in the design standards. The methods based on the crack direction corresponding to the principal stress and do not include the effect of aggregate interlocking seems to be too conservative. Two of the studied methods included the effect of aggregate interlocking, it was made either by introducing stresses in the crack plane or implicitly by changing the direction of the crack so that it no longer coincide with the direction of principal stress. For calculations based on probable load conditions, these methods gave estimations of the crack widths that were close to the ones observed at the bridges. Continuous measurements of cracks at the Gröndal and the Alvik bridges have also been included. Monitoring revealed that the strengthening work with post-tensioned tendons has, so far, been successful. It also revealed that the crack width variations after strengthening are mainly temperature dependent where the daily temperature variation creates movements ten times greater than those from a passing light-rail vehicle. Monitoring a crack between the top flange and the webs on the Gröndal Bridge showed that the top flange was moving in a longitudinal direction relative to the web until the strengthening was completed. The crack widths in the sections strengthened solely by carbon fibre laminates seem to increase due to long-term effects.</p>
21
Vuppala, Archana. "Thermal and thermal stress analyses of the state-changing tooling." abstract and full text PDF (free order & download UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1460787.
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Hudson, Craig. "A study of the cause of residual stresses in sputtered films." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387735.
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Khan, Raja Hameed Ullah. "Characteristics and stress state of Plasma Electrolytic Oxidation Coatings." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500210.
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Mani, Ashwini. "Study of partial discharge activity in magnet wires aged by combined stresses." Master's thesis, Mississippi State : Mississippi State University, 2005. http://library.msstate.edu/etd/show.asp?etd=etd-11072005-171152.
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O'Neill, J. M. "Thermoelastic stress analysis of anisotropic materials." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376642.
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Мордвінцева, Ірина Олександрівна. "Моделювання в САПР нестаціонарних термічних навантажень та ресурсної міцності поршнів швидкохідних дизелів". Thesis, Національний технічний університет "Харківський політехнічний інститут", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/40132.
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Дисертація на здобуття наукового ступеня кандидата технічних наук зі спеціальності 05.05.03 – двигуни та енергетичні установки. – Національний технічний університет "Харківський політехнічний інститут". –Харків, 2018.
Дисертація присвячена моделюванню в САПР нестаціонарних термічних навантажень та ресурсної міцності поршнів швидкохідних дизелів. З'ясовано, що для моделювання температурного стану поршня в перехідних процесах дизеля необхідно застосування нестаціонарних моделей експлуатації. При цьому, при завданні граничних умов необхідно мати дані щодо функцій керування, які враховують час перехідного процесу. Визначено допустимі спрощення завдання ГУ в характерних зонах поршня при розрахунках температурного та термонапруженого стану поршня на стаціонарних та в перехідних процесах дизеля. Їх використання дозволяє скоротити час проектування без порушення концепції гарантованого забезпечення ресурсу кромки КЗ на початкових етапах застосування САПР. Проведено експериментальне дослідження з визначення температурного стану поршня для дизеля 4ЧН12/14 в перехідних процесах дизеля. За даними дослідження визначені функції керування для кожного перехідного процесу. Запропоновано комплекс математичних моделей для визначення температурного та термонапруженого стану поршня в перехідних процесах дизеля. Для цього визначені рівняння функцій керування ГУ для ділянок першого та другого ПК. При спрощені ГУ достовірність результатів запропоновано встановлювати за показником відносного розрахункового збільшення ресурсу. За результатами досліджень встановлено вплив запізнення в часі ступінчастої зміни ГУ 3-го роду поршня в перехідному процесі дизеля на ресурсну міцність кромки КЗ. Означений захід дає змогу підвищити ефективність САПР на стаціонарних та нестаціонарних навантаженнях та при виконанні оцінки ресурсної міцності поршнів. Запропоновані нові конструкції поршнів з порожнинами масляного охолодження.<br>Thesis for the science degree of the Candidate of technical sciences by specialіty 05.05.03 – engines and power plants. – National Technical University "Kharkov polytechnic institute", Kharkov, 2018.
The thesis is devoted to modeling in CAD of non-stationary thermal stresses and resource durability of pistons of high-speed diesel engines. The dissertation is devoted to the modeling of non-stationary thermal loads and resource strength of high-speed diesels in CAD. It has been found that for modeling the thermal state of the piston in the transient processes diesel, it is necessary to use non-stationary models of operation. In this case, when the boundary conditions are imposed, it is necessary to have data on control functions that including the time of the transition process. The allowable simplifications of the border conditions problem in the characteristic zones of the piston in the calculations of the thermal and thermo-stressed state of the piston on the stationary and in the transient processes of the diesel load are determined. Their use allows to shorten the design time without violating the concept of guaranteed maintenance of the resource of the edge of the combustion chamber in the initial stages of CAD application. An experimental study was conducted to determine the thermal of a piston for a 4CHN12/14 diesel engine in transient diesel processes. According to the study, control functions are defined for each transient process. A complex of mathematical models for the determination of the thermal and thermo-stressed state of the piston in the transient processes of the diesel is proposed. With simplified border conditions, the reliability of the results proposed to set the indicator of the relative estimated increase in the resource. According to the results of the research, the effect of the shift in time of the step change of the BC of the 3rd kind of a piston in the transient process of the diesel engine on the resource strength of the edge of the combustion chamber is established. This measure allows to increase the efficiency of CAD on stationary and non-stationary loads and when performing the evaluation of the resource strength of the pistons. New designs of pistons with oil-cooling cavities are proposed.
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Мордвінцева, Ірина Олександрівна. "Моделювання в САПР нестаціонарних термічних навантажень та ресурсної міцності поршнів швидкохідних дизелів". Thesis, Національний технічний університет "Харківський політехнічний інститут", 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/40129.
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Дисертація на здобуття наукового ступеня кандидата технічних наук зі спеціальності 05.05.03 – двигуни та енергетичні установки. – Національний технічний університет "Харківський політехнічний інститут". –Харків, 2018.
Дисертація присвячена моделюванню в САПР нестаціонарних термічних навантажень та ресурсної міцності поршнів швидкохідних дизелів. З'ясовано, що для моделювання температурного стану поршня в перехідних процесах дизеля необхідно застосування нестаціонарних моделей експлуатації. При цьому, при завданні граничних умов необхідно мати дані щодо функцій керування, які враховують час перехідного процесу. Визначено допустимі спрощення завдання ГУ в характерних зонах поршня при розрахунках температурного та термонапруженого стану поршня на стаціонарних та в перехідних процесах дизеля. Їх використання дозволяє скоротити час проектування без порушення концепції гарантованого забезпечення ресурсу кромки КЗ на початкових етапах застосування САПР. Проведено експериментальне дослідження з визначення температурного стану поршня для дизеля 4ЧН12/14 в перехідних процесах дизеля. За даними дослідження визначені функції керування для кожного перехідного процесу. Запропоновано комплекс математичних моделей для визначення температурного та термонапруженого стану поршня в перехідних процесах дизеля. Для цього визначені рівняння функцій керування ГУ для ділянок першого та другого ПК. При спрощені ГУ достовірність результатів запропоновано встановлювати за показником відносного розрахункового збільшення ресурсу. За результатами досліджень встановлено вплив запізнення в часі ступінчастої зміни ГУ 3-го роду поршня в перехідному процесі дизеля на ресурсну міцність кромки КЗ. Означений захід дає змогу підвищити ефективність САПР на стаціонарних та нестаціонарних навантаженнях та при виконанні оцінки ресурсної міцності поршнів. Запропоновані нові конструкції поршнів з порожнинами масляного охолодження.<br>Thesis for the science degree of the Candidate of technical sciences by specialіty 05.05.03 – engines and power plants. – National Technical University "Kharkov polytechnic institute", Kharkov, 2018.
The thesis is devoted to modeling in CAD of non-stationary thermal stresses and resource durability of pistons of high-speed diesel engines. The dissertation is devoted to the modeling of non-stationary thermal loads and resource strength of high-speed diesels in CAD. It has been found that for modeling the thermal state of the piston in the transient processes diesel, it is necessary to use non-stationary models of operation. In this case, when the boundary conditions are imposed, it is necessary to have data on control functions that including the time of the transition process. The allowable simplifications of the border conditions problem in the characteristic zones of the piston in the calculations of the thermal and thermo-stressed state of the piston on the stationary and in the transient processes of the diesel load are determined. Their use allows to shorten the design time without violating the concept of guaranteed maintenance of the resource of the edge of the combustion chamber in the initial stages of CAD application. An experimental study was conducted to determine the thermal of a piston for a 4CHN12/14 diesel engine in transient diesel processes. According to the study, control functions are defined for each transient process. A complex of mathematical models for the determination of the thermal and thermo-stressed state of the piston in the transient processes of the diesel is proposed. With simplified border conditions, the reliability of the results proposed to set the indicator of the relative estimated increase in the resource. According to the results of the research, the effect of the shift in time of the step change of the BC of the 3rd kind of a piston in the transient process of the diesel engine on the resource strength of the edge of the combustion chamber is established. This measure allows to increase the efficiency of CAD on stationary and non-stationary loads and when performing the evaluation of the resource strength of the pistons. New designs of pistons with oil-cooling cavities are proposed.
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Savvas, Thrasyvoulos. "Pneumatic stress induced rupture processes in solids." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338444.
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Mansfield, Mark. "Surface stress and reconstructions on metal surfaces." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359866.
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Tucker, Matthew Taylor. "Structure-property stress state dependent relationships under varying strain rates." Diss., Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-04022009-091044.
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Tucker, Matthew T. "STRUCTURE-PROPERTY STRESS STATE DEPENDENT RELATIONSHIPS UNDER VARYING STRAIN RATES." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04022009-091044/.
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In this work, understanding the microstructural effects on stress state and strain rate dependent plasticity, damage, and failure of aluminum and magnesium alloys were examined. Several experimental techniques were employed to implement the test data into a physics-based internal state variable plasticity-damage model. Effects arising from various strain rates, stress states, and material orientations were quantified and discussed within the framework of linking microstructural features to mechanical properties. The method developed for determining structure-property relations was validated by accurately capturing the effects for a variety of materials and loading conditions. The end result is a methodology capable of predicting the onset of damage and failure for a material loaded under complex dynamic conditions.
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Al-Harbi, Naif Mohammad. "Stress amongst male teachers in state schools in Saudi Arabia." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488981.
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There has been increasing professional and public interest in issues related to occupational stress carried out during the last two decades. While a number of studies have been carried out in developed countries on such issues, few studies have been conducted in Saudi Arabia, particularly in the field of education. This study is therefore important because there has been virtually no research that has focused on teacher stress in the country and no study, to-date, has compared teachers' stress at the primary, intermediate, and secondary school stages. This study therefore aims to fill the research gap and to conduct an investigation into an issue that is currently raising serious concerns in the education field.
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Crisan, Romulus Leon. "An investigation into the stress-strain state of case furniture." Thesis, University of Buckingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327158.
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Keohane, Stephen Field. "School District Stress Prevention Practices in a Southern U.S. State." ScholarWorks, 2015. https://scholarworks.waldenu.edu/dissertations/215.
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The growing recognition that stress is a risk factor for youth health problems has spawned research on school-based stress prevention programs and services. While such programs and services are now available for adoption by schools, there is an absence of data on their use in U.S. schools systems. In the current study, Everett Rogers's diffusion of innovations model provided the theoretical framework for the investigation of school district stress prevention practices in one southern U.S. state. The sample for this quantitative descriptive study consisted of 135 out of 136 active public districts, and 72% of school systems completed and returned the survey (N = 97). Participants were designated school system personnel (83% administrators) who accepted either the e-mail or postal invitation to take part in the study. Descriptive data were gathered on the prevalence and characteristics of stress prevention programs and services for students, and the relationship between school district characteristics and programming and services prevalence was examined via chi-square and Fisher's exact tests. The frequency results indicate that 19% of districts provide programming, 22% provide services, and 23% provide both programming and services to students, and the Fisher's exact test revealed that programming prevalence is highest among urban districts compared to small town/rural school systems (p = 0.12). Recommendations for future research include the study of stress prevention practices with students and school system personnel at the national level. The findings of this study may contribute to the health and welfare of children and adolescents by informing the efforts of school systems to promote the adaptive competence of general student populations.
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Sandström, Daniel. "Analysis of the virgin state of stress at the Kiirunavaara mine." Licentiate thesis, Luleå, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16968.
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The mining production in Kiruna is heading towards larger depth and it is necessary to prepare for the next generation of underground facilities and new mining methods below the current main level. An important issue is the increasing rock stresses, which follows the ever-increasing depth of mining. This may result in instability of drifts, ramps, shaft and other facilities. The objective of this thesis is to clarify the stress situation in the mine and to state a relationship that could be used for rock mechanical analysis. The first part of the thesis is an appraisal of the results from the rock stress measurements carried out during the 1980's and 1990's. The measured state of stress shows a large variation, which depends on the influence of the mining production, measuring errors, and the heterogeneous nature of the rock mass. Even though, the stress measurements clearly affected by the mining production is sorted out, the variation remains. This means that the stress state in Kiirunavaara is still difficult to interpret. In order to increase the understanding of the natural variation, a literature review and analyses of the stress distribution in the rock mass is given. Because of this uncertainty, the second part presents another approach of handling the problems with the large scatter in the measured state of stress. By doing conceptual numerical analyses and probabilistic sensitivity analyses of underground constructions, the parameters affecting the behavior of the rock mass are studied. The analyses shows that the significance of the variation of the stress state is less than the significance of many other parameters like the stiffness and the strength of the rock mass. The recommendations is therefore, that a geomechanical model of the mine should be developed including for instance, the spatial variation of parameters like Young's modulus and strength of intact rock and joint parameters like number of joint sets, orientation, frequency and filling material.<br><p>Godkänd; 2003; 20070218 (ysko)</p>
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Jordon, James Brian. "DAMAGE AND STRESS STATE INFLUENCE ON BAUSCHINGER EFFECT IN ALUMINUM ALLOYS." MSSTATE, 2006. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04172006-133053/.
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In this work, the Bauschinger effect is shown to be intimately tied not only to plasticity but to damage as well. The plasticity-damage effect on the Bauschinger effect is demonstrated by employing different definitions (Bauschinger Stress Parameter, Bauschinger Effect Parameter, the Ratio of Forward-to-Reverse Yield, and the Ratio of Kinematic-to-Isotropic Hardening) for two differently processed aluminum alloys (rolled and cast) in which specimens were tested to different prestrain levels under tension and compression. Damage progression from second phase particles and inclusions that were generally equiaxed for the cast A356-T6 aluminum alloy and elongated for the rolled 7075 aluminum alloy was quantified from interrupted experiments. Observations showed that the Bauschinger effect had larger values for compression prestrains when compared to tension. The Bauschinger effect was also found to be a function of damage to particles/inclusions, dislocation/particle interaction, the work hardening rate, and the Bauschinger effect definition.
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Schultz, Heather Rae. "The Effects of Mindful Coloring on State Mindfulness, Anxiety, and Stress." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1504005638593573.
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Macgregor, Kenneth Waddell. "An investigation into the induced state of stress around inclined boreholes under non-hydrostatic stress conditions." Thesis, University of Strathclyde, 1987. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21493.
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This thesis details research conducted towards investigating the state of stress around inclined boreholes with the ultimate aim of predicting borehole stability and providing realistic estimates of closure stress. Chapter 1 discusses the factors affecting the stability of boreholes and reviews previous research conducted into borehole failure. The mechanics of hydraulic fracturing are reviewed as are methods of predicting fracture gradients. The manner in which closure stress is estimated is also critically reviewed. Chapter 2 describes an initial investigation into the stresses around inclined boreholes using the photoelastic technique of Stress Freezing. Chapter 3 details the laboratory determination of rock properties required for the borehole stability work detailed in Chapter 4. The applicability of the Brinell Hardness test to rock is also examined. Chapter 4 presents a detailed analysis of borehole stability. Failure criteria are developed and applied to estimate the mud weight required to maintain the hole in an elastic condition. To investigate the post-failure stability, existing 'yield zone' equations are modified to allow the effect of rock strength, oil flow rate, in-situ stress and hole angle to be examined. Chapter 5 describes the design and in-house manufacture of the specialised equipment required to measure fracture conductivity in the laboratory, the development of experimental procedures, the various test results and the conclusions drawn from them. Finally, the direct effect of a yield zone on the estimation of closure stress and on proppant selection is examined Chapter 6 summarises the conclusions that may be drawn from the work detailed in this thesis. The chapter also describes possible fields of future research which have been stimulated by the work presented. Two appendices are included, one providing a data-base of proppant properties, the other detailing the results of the application of the data-base to formation samples.
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Кириченко, Володимир Якович, Владимир Яковлевич Кириченко та V. Y. Kirichenko. "Наукові основи підвищення стійкості виробок високоресурсним кріпленням в геодинамічних зонах очисної виїмки". Thesis, Видавництво НГУ, 2012. http://ir.nmu.org.ua/handle/123456789/155.
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Дисертація на здобуття наукового ступеня доктора технічних наук за cпеціальністю 05.15.02 – підземна розробка родовищ корисних копалин, Державний ВНЗ «Національний гірничий університет» МОНмолодьспорт України, Дніпропетровськ, 2012.<br>Диссертация на соискание учёной степени доктора технических наук по специальности 05.15.02 – подземная разработка месторождений полезных ископаемых. Государственный ВУЗ «Национальный горный университет» МОН молодежи и спорта Украины, Днепропетровск, 2012.<br>Doctor of technical sciences thesis on specialization 05.15.02 – Underground mining of mineral deposits. – State higher education instituton “National Mining University”, Dniproperovsk, 2012.<br>Дисертація присвячена питанням надійної й економічної підтримки підготовчих виробок на основі методів і способів керування напруженим станом металорамних кріплень і масиву, що вміщує виробку.
Основна ідея роботи полягає у використанні явища утворення рухомих порушених зон навколо відслоненої поверхні (очисного вибою лави), що рухається для наукового обґрунтування й розробки високоресурсних металорамних кріплень, що забезпечують безпеку й ефективність підтримання підготовчих виробок у складних гірничо-геологічних умовах.
У роботі обґрунтовано новий підхід і вимоги до деформаційно-силових параметрів кріплень; надано нове уявлення закономірностей протікання деформаційних процесів у підроблюваному масиві; установлені характер і механізм взаємодії кріплення виробки й підроблюваного масиву; обґрунтований новий підхід керування надійністю виробок за рахунок попереднього резервування й оптимізації запасу міцності кріплення при очікуваному впливі напружено-деформованих зон, що переміщаються. Це дозволило обґрунтувати й розробити нові конструкції металорамних кріплень, замкових з'єднань і шахтного спецпрофілю, які забезпечують суттєве підвищення стійкості підготовчих виробок і зниження витрат на їх підтримання.<br>Диссертация посвящена вопросам надёжного и экономичного поддержания подготовительных выработок на основе методов и способов управления напряжённым состоянием металлорамных крепей и вмещающего массива.
Основная идея работы заключается в использовании явления образования перемещающихся нарушенных зон в окрестности движущейся обнажённой поверхности (очистного забоя лавы) для научного обоснования и разработки высокоресурсных металлорамных крепей, обеспечивающих безопасность и эффективность поддержания подготовительных выработок в сложных горно-геологических условиях.
Обоснованы требования к силовым и кинематическим параметрам крепей. Установлено, что для обеспечения эксплуатационной устойчивости выработок наиболее эффективный интервал сопротивления крепи 150 – 250 кН/м2 и может увеличиваться (при глубине разработки более 1000 м) до 350 – 450 кН/м2, а более 400 кН/м2 – является нецелесообразным.
Впервые дано представление закономерностей протекания деформационных процессов в подрабатываемом массиве, заключающиеся в том, что впереди движущегося очистного забоя вслед за нарастающим волнообразным изменением напряжённого состояния пород в упругом режиме деформаций происходит (на удалении порядка 1/2 длины лавы) разрушение пород, обусловленное изменением соотношения компонента напряжений, с образованием перемещающихся нарушенных зон «сжатия – разуплотнения» с периодическим расщеплением породной толщи на структурные блочно-слоистые элементы, с приближением к очистному забою протяжённость этих зон снижается, а степень разрушения – увеличивается.
Установлено, что при взаимодействии зон – стационарной вокруг проведённой подготовительной выработки и движущейся впереди очистного фронта - наблюдается последовательное (по мере приближения забоя лавы) изменение внешнего граничного условия, проходящего ступенчато с нарастанием, в силу чего предельное равновесие нарушается и размеры зоны увеличиваются, а обеспечение устойчивости выработки достигается соответствующим увеличением внутреннего граничного условия, т.е. усилением крепи, которое должно упреждающе соответствовать приросту внешнего граничного условия, определяемому скоростью подвигания лавы и прочностными свойствами массива пород.
Обоснован научный подход к эффективному управлению надёжностью крепи, заключающийся в резервировании и оптимизации запаса прочности конструкции, что достигается формоизменением элементов крепи, их разнорадиусным исполнением и сопряжённостью в узлах податливости, обеспечивающих сглаживание реакции крепи на воздействие перемещающихся напряжённо-деформированных зон пород. Установлено, что повышение предельной несущей способности крепи достигается дифференцированным изменением кривизны критического элемента, с увеличением которой по гиперболическому закону возрастает несущая способность (в 2 и более раз).
Определены необходимые значения силовых и кинематических параметров металлорамных крепей: предельная несущая способность комплекта не менее 700 – 850 кН/раму; рабочее сопротивление не менее 450 кН/раму; конструктивная податливость для трехзвенных конструкций до 700 мм и для многозвенных конструкций до 1000 мм. Это обеспечивается формоизменением сечения к эллипсной конфигурации и дифференцированным усилением образующих элементов, совершенствованием конструкции и расположения соединительных элементов крепи (узлов податливости), применением более совершенных способов гибки образующих сегментов крепи.
Разработаны конструкции крепей нового технического уровня (КШПУ-М, КЦЛ, КПП, КМП-А3(А4)Р2, КМП-А3(А5)Р2, КЦЛО). Типоразмерный ряд крепей охватывает максимальный диапазон сечений: от 9,5 до 25,5 м2. Всего создано 65 типоразмерных моделей. В новых конструкциях по сравнению с типовыми крепями достигнуто увеличение силовых характеристик в 1,5 – 2,0 и более раз.
Разработан новый профиль горячекатаный для крепей горных выработок – спецпрофиль СПА, в конструкции которого поперечное сечение днища выполнено переменной толщины, которое увеличивается от плоскости симметрии к участкам сопряжения с наклонными боковыми стенками, а нижние грани фланцев сопряжены с криволинейными опорными поверхностями фланцев и расположены под острым углом к горизонтальной плоскости. Принципиальным отличием и преимуществом профиля СПА является возможность использования принципа трения в желобе, реализация которого в узлах податливости крепи позволяет повысить уровень рабочего сопротивления на 30 – 50% и стабилизировать его значение.
Высокоресурсные крепи нового технического уровня внедрены в практику крепления подготовительных выработок на шахтах со сложными горно-геологическими условиями (ОАО «Павлоградуголь», ПАО «Ш/у «Покровское», ГП «Красноармейскуголь», ДУЭК, «Дзержинскуголь», Свердловантрацит», «Краснодонуголь» и др.), а также за рубежом (Болгария, Иран, Эстония). Подтверждённый экономический эффект – 93,7 млн грн.<br>The thesis is dedicated to safe and economic maintenance of development workings based on methods of stress state management of metal-frame supports and host massif.
Basic idea of the work is usage of detected phenomena of dislocating fractured zones formation close to the moving exposed surface (longwall stope) for scientific substantiation and development of new constructions of metal-frame supports providing safety and effectiveness of development workings support in complex mining-geological conditions.
New approach and requirements for strain-force parameters of supports is substantiated; new representation of laws of strain processes flow within developed massif is given; character and interaction mechanism of support and developed massif is established; new approach of workings reliability management is substantiated by way of preliminary reserving and optimization of support durability reserve with expected influence of moving stress-strain zones.
It would allow to substantiate and develop new constructions of metal-frame, lock connections and mine special profile that provide significant increase of development workings stability and decrease of costs for their maintenance.
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Marchant, Forde Ruth M. "Heart rate variability and sympathovagal balance during normal and stressed states in farm animals." Thesis, Durham University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400684.
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Dananaj, Ivan. "Rock stress relaxation in dry and saturated states." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ62205.pdf.
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Browne, Niall. "Nanoscale stress-induced conducting states in functional oxides." Thesis, Queen's University Belfast, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.766282.
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Putwain, David William. "Stress and anxiety in key stage 4 assessments." Thesis, University of Manchester, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518522.
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Hartnett, S. J. "Uniaxial stress/DLTS studies on deep level defects in n-GaAs." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361362.
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Mäestu, Jarek. "The perceived recovery-stress state and selected hormonal markers of training stress in highly trained male rowers /." Online version, 2004. http://dspace.utlib.ee/dspace/bitstream/10062/868/5/maestu.pdf.
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Mohammadi, Amirabbas. "The Effects of Initial State on the Cyclic Response of Sydney Sand." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27356.
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The state of a soil illustrated in the spaces of voids ratio and shear stress versus mean effective stress is known to control the soil behaviour through reflecting the impacts of initial density, stress level, static and cyclic stress ratios, and stress reversal condition. The multiplicity of the variables has led to confusing observations in studies of failure modes and cyclic strength. This research develops a better understanding of the effects of the state variables on the undrained cyclic response through conducting cyclic and monotonic triaxial tests on iso and anisotropically consolidated samples of Sydney sand, and using relevant experimental data published in the literature. The results indicate the major role of the degree of cyclic stress reversal in determining the cyclic failure mode. A “reversal ratio” is introduced, to quantify the reversal level, and a hybrid failure mechanism, referred to here as “plastic strain accumulation followed by cyclic mobility”, is analysed in detail. It is shown that the reversal ratio captures the combined impacts of the static and cyclic stress ratios on the behaviour. “Threshold reversal ratio” which is associated with the boundaries between different modes of failure is discussed and estimated. A state parameter approach is employed to investigate the impacts of static and cyclic stress ratios on the cyclic strength. The number of cycles to failure, Nf, and the cyclic resistance ratios, CRR15, CRR100 and CRR500, were found to correlate with the state parameter. However, these correlations become more sensitive to the state parameter as the static stress ratio increases. The results suggest that the interconnection between Nf and CRRn is not largely influenced by the static stress ratio and can be an alternative to the state parameter approach. Furthermore, the states causing failure are depicted on a unified state diagram that combines the roles of density, stress level, static stress ratio and cyclic stress ratio.
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Williams, Walter Ray. "Stress analysis of a glued timber beam." Master's thesis, Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-04032009-085801.
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Sivathayalan, Sivapathasundaram. "Fabric, initial state and stress path effects on liquefaction susceptibility of sands." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/NQ56623.pdf.
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Gibson, James B. "Three Essays on Fiscal Stress and Financial Stability in State Government Finance." UKnowledge, 2013. http://uknowledge.uky.edu/msppa_etds/4.
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State government finance is a substantial endeavor in the United States. The management of a multitude of revenues and expenditures often involves some level of fiscal stress. In an age of increased public scrutiny, policymakers must be mindful of possible causes of fiscal stress, and the policy options available to mitigate fiscal stress and increase financial stability. This dissertation contains three essays that examine different elements of fiscal stress, and in some cases, the applicable policy responses.
Chapter two examines rainy day funds and their countercyclical goal of reducing recessionary fiscal stress. This essay takes a different approach from much of the literature, by using forecast residuals to quantify fiscal stress as tax revenue volatility and searching for any relationship between rainy day funds and states that had greater volatility. Empirical results indicate states that experience positive residuals, that is actual tax revenues greater than the forecast trend line, had greater rainy day fund balances.
Chapter three focuses on the problem of lost revenues facing states from e-commerce. Due to Supreme Court decisions, businesses that do not have a physical location, or nexus, in a state are not required to collect sales and use taxes. To date, the policy response to lost revenue that has gained the most traction is the Streamlined Sales and Use Tax Agreement. Results indicate that states with local option sales taxes and higher sales tax rates were more likely to adopt this agreement.
Chapter four scrutinizes state unemployment trust funds, which are used to fund state unemployment insurance programs. If state funds run short of money during recessions due to the larger number of individuals drawing benefits, then states must borrow from the federal government’s unemployment trust fund. This creates another liability that must be managed by state governments. Empirical findings show that several features of programs affect balances and the probability of taking a loan from the federal fund including the taxable wage base, weekly benefits, and unemployment tax rates. This dissertation concludes by summarizing the results and exploring future research possibilities on the three essay topics.
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Sirotkina, Natalia. "Stress in ion-beam assisted silicon dioxide and tantalum pentoxide thin films." Thesis, University of Salford, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272625.
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