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1
Gharemeshg, Gharavi Ayshe. "Thickness Effects In Hydrogen Sorption Of Magnesium/palladium Thin Films." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614051/index.pdf.
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Magnesium (Mg) thin films with various thicknesses ranging from 50 to 1000 nm capped with nominally 20 nm Palladium (Pd) were prepared by a thermal evaporation unit. A total of 25 glass substrates were used in each experiment. The unit had a rotatable macro shutter, rectangular in shape, rotation axes opposite to the Mg source, which allowed controlled exposure of the substrates. Thin films of 50, 100, 150, 200, 300, 400, 500, 600, 800 nm and 1000 nm were produced in a single experiment. Hydrogenation and dehydrogenation of the films were examined using a gas loading chamber which allowed in-situ resistance measurement. Samples were hydrogenated isochronally up to 453 K with a heating rate of 1.5 K/min. Samples cooled to room temperature were subjected to dehydrogenation test. The chamber was taken under vacuum (~10-2 mbar) and the sample was heated up to 453 K at a rate of 1.5 K/min. The results showed that the hydrogenation and dehydrogenation temperatures correlate with the film thickness, thinner films reacting with hydrogen at low temperatures. While 200 nm thin film hydrogenated at 420 K and desorbed it at 423 K, 50 nm thin film hydrogenated at room temperature and desorbed it at 405 K. Thicker films needed higher temperatures to react with hydrogen. It is concluded that films thinner than 200 nm react fully with hydrogenwhile a considerable portion of the thicker films remain unreacted. Significance of this is discussed with reference to the design of hydrogen storage systems based on thin films or nanoparticles.
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Suarez, Matthew. "The Effect of Membrane Thickness on the Performance of PBI-Based High-Temperature Direct Methanol Fuel Cells." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/1131.
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"This project investigates the effect of membrane thickness on the performance and durability of a Direct Methanol Fuel Cell (DMFC) using a commercially available Celtec®P-1000 PBI-based membrane electrode assembly (MEA). The PBI-based membranes tested were the 100µm, the standard thickness, 200µm and 250µm thick. With various methanol feed concentrations and cathode feeds, oxygen and air, the PBI-based MEAs were operated between 160 and 180°C with vaporized methanol feed. Results showed that the DMFC performance increased with temperature and with PBI membrane thickness. The optimal concentration for the 100µm membrane was at 5M while the best performance with the 200µm membrane was obtained at 3M. The 250µm membrane looked like it could have had better performance than the 200µm, but unfortunately experimental issues didn’t allow completion of these results."
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Mellott, Stephen Richard. "Tensile, Creep, and Fatigue Behaviors of Thermoplastics Including Thickness, Mold Flow Direction, Mean Stress, Temperature, and Loading Rate Effects." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1344541288.
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Lokre, Chinmay Vivekananda. "Effect of Density, Initial Water Content, Drying Temperature, Layer Thickness, and Plasticity Characteristics on Shrinkage Crack Development in Clay Soils: An Experimental Study." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1557423451910154.
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Blot, Joseph. "Relation entre les grandeurs supraconductrices caracteristiques de l'aluminium massif et les champs de transition de films divises, en fonction de leur epaisseur." Rennes, INSA, 1987. http://www.theses.fr/1987ISAR0006.
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Etude de l'influence de la taille des echantillons sur les champs magnetiques de surchauffe et de retard a la condensation dans l'etat supraconducteur sur des couches d'aluminium divisees en damiers et dont le refroidissement est assure dans un dispositif cryogenique a helium liquide permettant d'atteindre 0,37k. Analyse systematique en fonction de la temperature et de l'epaisseur, des champs paralleles et perpendiculaire de transition presentes par une serie de films evapores sur des substrats de verre a la temperature ambiante
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Pezant, Joannes Charles. "High temperature thickness monitoring using ultrasonic waves." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26577.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Michaels, Jennifer; Committee Member: Jacobs, Laurence; Committee Member: Michaels, Thomas. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Pellan, Yves. "Etude de la metastabilite de la transition supraconductrice de films divises d'indium sous champ magnetique parallele et perpendiculaire." Rennes, INSA, 1987. http://www.theses.fr/1987ISAR0007.
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Mesures systematiques des champs de surchauffe et de retard a la condensation et du champ critique thermodynamique du film en fonction de l'epaisseur, de la temperature et de l'orientation du champ magnetique, sur deux series de films deposes sur des substrats a 295k et 77k. Determination de la profondeur de penetration, de la longueur de coherence et du parametre de ginzburg-landau de l'indium supraconducteur pur
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Vedantham, Vikram. "In-situ temperature and thickness characterization for silicon wafers undergoing thermal annealing." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1181.
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Nano scale processing of IC chips has become the prime production technique as the microelectronic industry aims towards scaling down product dimensions while increasing accuracy and performance. Accurate control of temperature and a good monitoring mechanism for thickness of the deposition layers during epitaxial growth are critical parameters influencing a good yield. The two-fold objective of this thesis is to establish the feasibility of an alternative to the current pyrometric and ellipsometric techniques to simultaneously measure temperature and thickness during wafer processing. TAP-NDE is a non-contact, non-invasive, laser-based ultrasound technique that is employed in this study to contemporarily profile the thermal and spatial characteristics of the wafer. The Gabor wavelet transform allows the wave dispersion to be unraveled and the group velocity of individual frequency components to be extracted from the experimentally acquired time waveform. The thesis illustrates the formulation of a theoretical model that is used to identify the frequencies sensitive to temperature and thickness changes. The group velocity of the corresponding frequency components is determined and their corresponding changes with respect to temperature for different thickness are analytically modeled. TAP-NDE is then used to perform an experimental analysis on Silicon wafers of different thickness to determine the maximum possible resolution of TAP-NDE towards temperature sensitivity, and to demonstrate the ability to differentiate between wafers of different deposition layer thickness at temperatures up to 600?C. Temperature resolution is demonstrated for ?10?C resolution and for ?5?C resolution; while thickness differentiation is carried out with wafers carrying 4000? and 8000? of aluminum deposition layer. The experimental group velocities of a set of selected frequency components extracted using the Gabor Wavelet time-frequency analysis as compared to their corresponding theoretical group velocities show satisfactory agreement. As a result of this work, it is seen that TAP-NDE is a suitable tool to identify and characterize thickness and temperature changes simultaneously during thermal annealing that can replace the current need for separate characterization of these two important parameters in semiconductor manufacturing.
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RABE, CLAUDIO. "TEMPERATURE EFFECTS ON SOILS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1521@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO presente trabalho apresenta um estudo do comportamento mecânico de um solo argiloso e um solo residual, submetidos a ensaios com temperaturas entre 20ºC e 70ºC. O programa experimental envolveu ensaios de caracterização (limites de Atterberg), ensaios de adensamento com carregamento incremental (SIC), triaxiais não drenados (CIU) e de cisalhamento direto. Para a realização dos ensaios de limites de Atterberg, as amostras foram previamente aquecidas em estufa. Para a realização dos ensaios de adensamento, triaxiais e de cisalhamento direto, foram desenvolvidos sistemas de aquecimento, controle e distribuição térmica, para garantir ao corpo de prova uma uniformidade da temperatura preestabelecida. Uma metodologia de calibração do sistema de aquecimento foi desenvolvida para se determinar o tempo necessário para o equilíbrio térmico dos solos. Houve também a preocupação com a calibração prévia dos instrumentos eletrônicos da prensa triaxial (transdutores e célula de carga) na temperatura dos ensaios. Na faixa de temperatura estudada, o preaquecimento não têm influência nos resultados de limites do solo argiloso. Os ensaios de adensamento revelaram que o aquecimento leva a um aumento da compressibilidade do solo, assim como um aumento da velocidade de adensamento. Nos ensaios triaxiais, observou-se que o aumento da temperatura causa um aumento da resistência dos materiais, além de reduzir o excesso de poropressões gerado durante o cisalhamento não drenado. Os ensaios de cisalhamento direto confirmaram a tendência de aumento da resistência observada nos ensaios triaxiais, além de indicar uma redução da deformabilidade volumétrica durante o cisalhamento.
The subject matter of this thesis is the study of the mechanical behavior of clay and residual soils subjected to a series of tests with temperatures ranging from 20 to 70ºC. The experimental program consisted of Atterberg limits, consolidation tests with incremental loading (SIC), triaxial consolidated undrained tests (CIU) and direct shear tests on both soil types under saturated conditions. Samples for Atterberg limit tests have been pre-heated in oven to the specified temperature. Heating control and thermal distribution systems have been specially developed for insuring an homogeneous temperature throughout the consolidation, triaxial and direct shear tests. The thermal balance times for the two soils were achieved by means of a calibration method developed for the heating system. Transducers and load cell calibration were carefully calibrated acording to the temperature range for the testing program. It may be concluded that pre-heating to temperatures below 70ºC has no influence on the Atterberg limits results for both soils. Consolidation tests have shown that heating on samples leads to an increase in compressibility and also on the coefficient of consolidation. From the triaxial tests it was observed that an increase in temperature leads to an increase in strength and to smaller excess porepressures during undrained shear tests. The increase in shear strenght with temperature observed on triaxial tests was also confirmed by direct shear tests. These effects were more significant in clay than in residual soil.
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Wang, Dong. "Fatigue behavior of thin Cu films film thickness and interface effects /." Karlsruhe : Forschungszentrum Karlsruhe, 2007. http://d-nb.info/98578797X/34.
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Shouse, Michael. "BIOMECHANICAL EFFECTS OF TREES AND SOIL THICKNESS IN THE CUMBERLAND PLATEAU." UKnowledge, 2014. http://uknowledge.uky.edu/geography_etds/25.
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Previous research in the Ouachita Mountains, Arkansas suggests that, on relatively thin soils overlying bedrock, individual trees locally thicken the regolith by root penetration into bedrock. However, that work was conducted mainly in areas of strongly dipping and contorted rock, where joints and bedding planes susceptible to root penetration are more common and accessible. This project extended this concept to the Cumberland Plateau, Kentucky, with flat, level-bedded sedimentary rocks. Spatial variability of soil thickness was quantified at three nested spatial scales, and statistical relationships with other potential influences of thickness were examined. In addition, soil depth beneath trees was compared to that of non-tree sites by measuring depth to bedrock of stumps and immediately adjacent sites.
While soil thickness beneath stumps was greater in the Ouachita Mountains compared to the Kentucky sites, there were no statistically significant differences in the difference between stump and adjacent sites between the two regions. In both regions, however, soils beneath stumps are significantly deeper than adjacent soils. This suggests the local deepening effects of trees occur in flat-bedded as well as steeply dipping lithologies. Regression results at the Cumberland Plateau sites showed no statistically significant relationship between soil depth and geomorphic or stand-level ecological variables, consistent with a major role for individual tree effects. Nested analysis of variance between 10 ha stands, 1.0 ha plots, and 0.1 ha subplots indicates that about 67 percent of total depth variance occurs at, or below, the subplot level of organization. This highly localized variability is consistent with, and most plausibly explained by, individual tree effects.
The effects of biomechanical weathering by trees are not limited to areas with strongly dipping and contorted bedrock. Variability of soil depth in the Cumberland Plateau is likely influenced by positive feedbacks from tree root growth, that these interactions occur over multiple generations of growth, and that the effects of trees are the dominant control of local soil thickness. Since lateral lithological variation was minimal, this study also provides evidence that the positive feedback from biomechanical weathering by trees leads to divergent development of soil thickness.
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Jefferson, Ian. "Temperature effects on clay soils." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/7233.
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Temperature changes occur in soils in a number of ways, e. g. landfill liners, around buried services and during sampling. An experimental programme was conducted to examine the effect of temperature (between 10 to 80 °C) on the volume change and shear behaviour of saturated clays. Testing included Liquid Limit (cone penetrometer), residual shear strength (modified Bromhead Ring Shear), laboratory vane shear ( at moisture contents between the Liquid and Plastic Limits) and oedometer tests. An extensive literature survey indicated that kaolinites and smectites would show extremes of thermal behaviour. To examine this two artificially pure clays were tested: English China Clay (a well crystallised kaolinite) and Wyoming Bentonite (a monovalent smectite). To supplement this four British soils were tested: Keuper Marl, Lower Lias Clay, London Clay and Oxford Clay. Full material data were obtained coupled with careful control of stress and thermal histories. It is concluded that two types of extreme thermal response exists: a thermomechanical and a thermo-physicochemical change exhibited by kaolinite and smectite respectively. The temperature sensitivity of clays relative to a particular parameter is positively related to its specific surface area. A quick and repeatable method to qualitatively assess this has been developed: the LUT method. Its advantages include that no temperature calibrations are needed and it has a relatively large operating temperature range, 10 to 80 °C having been successfully used. The consolidation pressure (in the oedometer) needed to change the nature of a soil's thermal response is negatively related to its specific surface area. This, it is postulated, occurs at the same 'critical' contact stress for all clays, i. e. the interparticle threshold stress at which a thermo-physicochemical response changes to a thermo-mechanical one. This threshold stress occurs at a anisotropic consolidation pressure of 60 kPa for a well crystallised kaolinite , at 250 kPa for reconstituted London Clay and at 480 kPa for a mono-valent smectite. Furthermore, greater parallel particle alignment or reconstituting a sample enhances a soil's temperature sensitivity in the oedometer. The thermal changes to consolidation and permeability coefficients can be typically predicted by the corresponding change to the dynamic viscosity of water. Deviations occur with smectites at normal stresses greater than 480 kPa, while for Keuper Marl this occurred at normal stresses of 50 kPa and greater than 850 kPa. Keuper Marl exhibits a greater temperature sensitivity of different parameters than predicted by index tests. This is strongly dependent on consolidation pressure and temperature. At elevated temperatures (>40 °C) and under increasing consolidation pressure, ped units tend to collapse, but once the pressure is removed ped reformation occurs. Thus knowledge of thermal and stress histories, coupled with full material data, is essential to effectively predict temperature effects on the engineering behaviour of soils with any degree of confidence.
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Del, Zio Michael R. (Michael Robert) 1982. "Conducting polymer actuators : temperature effects." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35656.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references.
In order to utilize conducting polymer actuators as a viable engineering solution, it is necessary to produce usable levels of force with a reasonable bandwidth. Polypyrrole actuated at temperatures as high as 100 °C increases stress magnitudes by as much as 4x and stress rates by 5x. The effect is caused by a combination of decreased solution resistance and increased ion diffusion within the polymer. However, these temperatures cause accelerated degradation due to the time-temperature correlation common to viscoelastic polymers. Actuation at these temperatures can decrease cycle life by as much as 20x. Excessive heating without actuation can also result in poor actuator performance. Impedance spectroscopy coupled with electro-mechanical analysis highlighted previous results and also showed an improved frequency response from actuation at high temperatures.
by Michael R. Del Zio.
S.M.
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Bezuidenhout, Johannes Jurie. "Convective heat flux determination using surface temperature history measurements and an inverse calculation method." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35706.
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Effective gages to measure skin friction and heat transfer have been established over decades. One of the most important criteria in designing such a gage is the physical size of the gage to minimise the interference of the flow, as well as the mass of these devices. The combined measurement of skin friction and heat flux using one single gage on the other hand, present unique opportunities and with it, unique technical problems. The objective of this study is therefore to develop a cost-effective single gage that can be used to measure both skin friction and heat flux. The method proposed in this study is to install a coaxial thermocouple into an existing skin friction gage to measure the unsteady temperature on the surface of the gage. By using the temperature history and a computer program the heat flux through the surface can be obtained through an iterative guessing method. To ensure that the heat flux through the gage is similar to the heat flux through the rest of the surface, the gage is manufactured of a material very similar to the rest of the surface.
Walker developed a computer program capable of predicting the heat flux through a surface from the measured surface temperature history. The program is based on an inverse approach to calculate the heat flux through the surface. The biggest advantages of this method are its stability and the small amount of noise induced into the system. The drawback of the method is that it is limited to semi-infinite objects. For surfaces with a finite thickness, a second thermocouple was installed into the system some distance below the first thermocouple. By modifying the computer program these two unsteady temperatures can be used to predict the heat flux through a surface of finite thickness.
As part of this study, the effect of noise induced by the Cook-Felderman technique, found in the literature were investigated in detail and it was concluded that the method proposed in this study is superior to this Cook-Felderman method. Heat flux measurements compared well with measurements recorded with heat flux gages. In all cases evaluated the difference was less than 20%. It can therefore be concluded that heat flux gages on their own can measure surface heat flux very accurately. These gages are however too large to install in a skin-friction gage. The method introduced in this study is noisier than the heat flux gages on their own, but the size which is very important, is magnitudes smaller when using a coaxial thermocouple, to measure the surface temperature history.
Master of Science
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Roshanaei, Sina. "Stress-Strain data for metals in bar and sheet form : strain rate, thickness and temperature influences." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/15614.
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Over the past few decades various models of different formats have been developed to correctly evaluate and predict the strength of materials. However, these models are limited in certain environmental conditions in implementing the effect of material's thickness into their models. As such an there was a need to consider the basics of mechanical engineering and to try and define the trend, thickness has upon the behaviour of materials with respect to environmental conditions. The work consisted of a representation of tensile testing testing of common engineering alloys across a wide range of temperature, strain rate and thickness. Acquisition of high strain rate data and extended strain data (split-hopkinson, bulge forming and plane strain compression). A review of existing graphical techniques and limited applications using strength reduction factors, as well as applying the accepted empirical formulae, Johnson-Cook, Armstrong-Zerrili, Ramberg-Osgood and Hollomon. Later, recognising a need for a new approach as with a universal (quartic) polynomial fit to all plastic flow curves in which coefficients are T, ε̇ and t̄ dependant. Adoptation of a common numerical procedure for strain intercept ε0 and cut-off instability co-ordinates (σi, εi)- each as the solution to the roots of a quartic. Therefore, a proposal of the flow curve tables allowing interpolation and extrapolation, a numerical representation of any previous "Atlas of Curves". Subsequently, leading to reconstruction of the full stress-strain curve with the addition of elastic strain calculated from the modulus applicable to the specific test condition by further testing of these data from literature; both improving the existing and producing new empirical and simulation based models to analyse the materials, which will be subjected to dynamic loading as well as temperature and strain rates variations. The main objective of the work, was involved in creating a polynomial fit to describe the three physical conditions in terms of coefficients and to verify the findings in a FEA package, ABAQUS. A new process in reading the stress-strain data. By means of such development an instability study of strain limits based on Considére criteria was developed which illustrated the ways to prolong the instability limit. A secondary study of this work relates to creating a bridge between the micro-structure and macro-structure of the tested materials. A series of correlations and trends were developed to further signify the shift in micro-structural restructuring, whilst the material is under load. Another important aspect of the work consists, of carrying out an analytical study on Ramberg-Osgood equation. Ramberg-Osgood equation has been at the forefront of many engineering advancement. However it can yet be improved and reformatted by means of defining a set value for its variable constants. As such a fix ƞt value based on a best-fit approach was developed which was analytically tested.
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Lin, Weiwei, Kai Chen, Shufeng Zhang, and C. L. Chien. "Enhancement of Thermally Injected Spin Current through an Antiferromagnetic Insulator." AMER PHYSICAL SOC, 2016. http://hdl.handle.net/10150/614754.
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We report a large enhancement of thermally injected spin current in normal metal (NM)/antiferromagnet (AF)/yttrium iron garnet (YIG), where a thin AF insulating layer of NiO or CoO can enhance the spin current from YIG to a NM by up to a factor of 10. The spin current enhancement in NM/AF/YIG, with a pronounced maximum near the Neel temperature of the thin AF layer, has been found to scale linearly with the spin-mixing conductance at the NM/YIG interface for NM = 3d, 4d, and 5d metals. Calculations of spin current enhancement and spin mixing conductance are qualitatively consistent with the experimental results.
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Parakala, Padma. "Effects of Thickness and Indenter Tip Geometry in Nanoindentation of Nickel Films." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4452/.
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Nanoindentation has become a widely used technique to measure the mechanical properties of materials. Due to its capability to deform materials in micro- and nano-scale, nanoindentation has found more applications in characterizing the deformation behavior and determining the mechanical properties of thin films and coatings. This research deals with the characterization of samples received from Center for Advanced Microstructures and Devices (CAMD) and Integran Technologies Inc., Toronto, Canada and the objective of this investigation was to utilize the experimental data obtained from nanoindentation to determine the deformation behavior, mechanical properties of thin films on substrates and bulk materials, and the effect of geometrically different indenters (Berkovich, cubecorner, and conical). X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) analysis were performed on these materials to determine the crystal orientation, grain size of the material, and also to measure any substrate effects like pile-up or sin-in respectively. The results indicate that indentation size effect (ISE) strongly depends on shape of the indenter and less sensitive to penetration depth where as the hardness measurements depends on shape of indenter and depth of penetration. There is a negligible strain rate dependency of hardness at deeper depths and a significant increase in the hardness due to the decrease in grain size and results also indicate that there is no significant substrate effect on thin films for 10% and 20% of film thicknesses. Nanocrystalline material could not validate a dislocation based mechanisms deformation for indentation made by cubecorner and conical indenters in depths less than 1mm.
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kumar, Amit. "TEMPERATURE INSIDE THE LANDFILL: EFFECTS OF LIQUID INJECTION AND AMBIENT TEMPERATURE." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2231.
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This study represents an analysis of comprehensive temperature and moisture content data collected from the anaerobic portion of a bioreactor landfill at the New River Regional Landfill, Florida, USA. The main focus of the study was the analysis of effects of the liquid injection on the temperature inside the landfill. When the leachate or groundwater at lower temperature than the landfilled waste is injected into the landfill, it has an initial cooling effect on the waste until the biological activity, enhanced by the additional moisture, releases heat. This cooling effect was tested in the study to determine whether it could be used to track moisture arrival as an alternative to moisture sensors. First of all, this hypothesis of cooling effect was tested at the injection wells by correlating temperature drops at the injection wells with known injection events. Then the temperature drop events were identified at monitoring locations where temperature and moisture sensors were co-located. The identification step at the monitoring wells was more difficult than in the case of the injection wells because the cooling effect at the injection well is more pronounced than at the monitoring sites, located 7.62 m away from the point of injection. From the analysis it was found out that, overall, the temperature drop at monitoring locations brought about by the injected liquid is a good criterion for tracking the moisture arrival, however only at the first arrival of moisture. Of all of the cases studied, temperature was able to indicate the moisture arrival for 85% of the times at the first injection as opposed to 36% overall. The difference was attributed to the stimulation of biological activity and subsequent heating of the injected liquid as it moves through the waste. Another focus of the research was the estimation of the waste quantity (volume) wetted from the injection. It was assumed that complete mixing takes places between injected liquid and the moisture already present in the waste and that the temperature of the injected liquid is the ambient temperature. According to the results, there was a significant gap between the expected and the actual wetted volume. The waste volume actually wetted was < 1% to 9% of the total waste volume expected to be wetted. Also studied was the effect of ambient temperature on the waste temperature. It was observed that the ambient temperature has no effect on the global temperature inside a bioreactor landfill even at a shallow depth of 4.6 m. While analyzing the trend of waste temperature inside the landfill, liquid injection was found to lead to an increase in temperature.M.S.Env.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engr MSEnvE
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Parker, Latise Anitrá. "3D integration, temperature effects, and modeling." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2533.
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Thesis (M.S.) -- University of Maryland, College Park, 2005.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Wang, Dong [Verfasser]. "Fatigue behavior of thin Cu films : film thickness and interface effects / Dong Wang." Karlsruhe : Forschungszentrum Karlsruhe, 2007. http://d-nb.info/98578797X/34.
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Grattan, Lesley Jane. "Investigation of thickness effects on the dielectric constant barium strontium titanate thin films." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396079.
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Sauter, Linda Xenia. "Microstructural and film thickness effects on the thermomechanical behavior of thin Au films." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-31632.
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Sauter, Linda Xenia. "Microstructural and film thickness effects on the thermomechanical behavior of thin Au films." Stuttgart : Max-Planck-Inst. für Metallforschung, 2007. http://d-nb.info/995370753/34.
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Zhang, Jian. "INVESTIGATION OF THE EFFECTS OF LAYER THICKNESS ON DYE SENSITIZED SOLAR CELL PERFORMANCE." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1377132624.
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Lube, Vinicius Munaldi. "Effects of moisture-induced thickness swelling on the microstructure of oriented strand board." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59774.
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When wood becomes wet and then dries, restraint of shrinkage at the surface of wood by wetter surface and also sub-surface layers causes tensile stresses to develop resulting in micro-checking. Wood elements in composites such as oriented strand board (OSB) also swell and shrink when they become wet and dry. Furthermore, some wood elements are large enough to develop unbalanced surface and sub-surface tensile stresses. Hence, moisture changes and swelling and shrinkage of OSB might result in micro-checking. I test this hypothesis in this thesis. I also examine whether micro-checking contributes to thickness swelling of OSB. I used macro-photography, X-ray micro-computed tomography, and field emission scanning electron microscopy to probe the microstructure of OSB exposed to wetting and drying. These techniques were used to visualize and quantify the thickness swelling of OSB and the dimensions of micro-checks and other voids in OSB during and after wetting and drying. The spatial micro-distribution of a zinc borate biocide in OSB was also examined before and after samples were exposed to wetting and drying. Numerous surface and internal micro-checks developed in OSB exposed to wetting and drying as I hypothesized. Micro-checks developed during wetting, unlike the pattern of checking found in solid wood. Enlargement of voids was also observed during wetting and drying. Micro-checks occurred at the interface between latewood and earlywood and in the rays of softwood flakes and, less commonly, in the rays of aspen flakes. My results indicate that the pattern of micro-checking of OSB is different in some respects to that of solid wood, and suggest that micro-checking contributes to the irreversible thickness swelling of OSB. I briefly discuss the implications of my findings for the development of treatments designed to reduce the irreversible thickness swelling of OSB.Forestry, Faculty of
Graduate
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Karademir, Tanay. "Elevated temperature effects on interface shear behavior." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42764.
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Environmental conditions such as temperature inevitably impact the long term performance, strength and deformation characteristics of most materials in infrastructure applications. The mechanical and durability properties of geosynthetic materials are strongly temperature dependent. The interfaces between geotextiles and geomembranes as well as between granular materials such as sands and geomembranes in landfill applications are subject to temperature changes due to seasonal temperature variations as well as exothermic reactions occurring in the waste body. This can be a critical factor governing the stability of modern waste containment lining systems. Historically, most laboratory geosynthetic interface testing has been performed at room temperature. Information today is emerging that shows how temperatures in the liner systems of landfills can be much higher.
An extensive research study was undertaken in an effort to investigate temperature effects on interface shear behavior between (a) NPNW polypropylene geotextiles and both smooth PVC as well as smooth and textured HDPE geomembranes and (b) sands of different angularity and smooth PVC and HDPE geomembranes. A temperature controlled chamber was designed and developed to simulate elevated temperature field conditions and shear displacement-failure mechanisms at these higher temperatures. The physical laboratory testing program consisted of multiple series of interface shear tests between material combinations found in landfill applications under a range of normal stress levels from 10 to 400 kPa and at a range of test temperatures from 20 to 50 °C.
Complementary geotextile single filament tensile tests were performed at different temperatures using a dynamic thermo-mechanical analyzer (DMA) to evaluate tensile strength properties of geotextile single filaments at elevated temperatures. The single filament studies are important since the interface strength between geotextiles and geomembranes is controlled by the fabric global matrix properties as well as the micro-scale characteristics of the geotextile and how it interacts with the geomembrane macro-topography.
The peak interface strength for sand-geomembrane as well as geotextile-geomembrane interfaces depends on the geomembrane properties such as hardness and micro texture. To this end, the surface hardness of smooth HDPE and PVC geomembrane samples was measured at different temperatures in the temperature controlled chamber to evaluate how temperature changes affect the interface shear behavior and strength of geomembranes in combination with granular materials and/or geotextiles. The focus of this portion of the experimental work was to examine: i) the change in geomembrane hardness with temperature; ii) develop empirical relationships to predict shear strength properties of sand - geomembrane interfaces as a function of temperature; and iii) compare the results of empirically predicted frictional shear strength properties with the results of direct measurements from the interface shear tests performed at different elevated temperatures.
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Bryant, Ruth. "Effects of temperature on wheat-pathogen interactions." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/48755/.
Full textAbstract:
Climate change is affecting UK agriculture, and research is needed to prepare crops for the future. Wheat is the UK’s most important crop, and needs to be protected from losses caused by disease. While direct effect of the environment on pathogen spread is often reported, effect of the environment on host defence is not. Many wheat resistance genes are temperature sensitive and these were used as a starting point to investigate defence temperature sensitivity in wheat starting with yellow rust resistance gene Yr36, previously shown to be temperature-sensitive. The effect of temperature on resistance was shown to be independent of Yr36 in breeding line UC1041, and was more likely to be due to a previously-uncharacterised background temperature sensitivity. These results suggest that temperature changes, rather than thresholds, might influence some disease resistance mechanisms. Understanding this phenomenon could enable the breeding of more stable defence in crops. In order to gain further insight into how temperature changes influence resistance, plants were grown under different thermoperiods and challenged with different types of pathogens; Results showed that resistance to multiple pathogens in one cultivar Claire was enhanced under variable temperatures, compared to constant temperatures. Taken together, the research presented revealed that defence temperature sensitivity in plants is much more complex than previously thought, considering that both temperature changes and different thermoperiods can influence aspects of wheat defence. To ascertain which research approaches will be most valuable in preparing for climate change, the effect of the environment on take-all was also investigated. Vulnerable periods for wheat from the threat of take-all development were identified by analysing historical datasets, and controlled environment experiments. Results showed a relationship between initial post-sowing temperatures and spring take-all levels in 2nd 3rd or 4th winter wheats, depending on the location. The work on yellow rust resistance and take-all both identify vulnerable periods for wheat caused by the environment, be it weakening of host defence responses, or increased threat from disease pressure. Further characterisation and understanding of vulnerable periods will be essential to control disease outbreaks under an increasingly unstable climate.
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Farjallah, Emna. "Monitoring of temperature effects on CMOS memories." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS091/document.
Full textAbstract:
La complexité des systèmes électroniques ne cesse d’augmenter, tout comme la tendance actuelle de miniaturisation des transistors. La fiabilité est ainsi devenue un continuel défi. Les environnements hostiles caractérisés par des conditions extrêmes de hautes températures affectent le bon fonctionnement des systèmes. Pour les composants de stockage de données, la température est considérée comme une menace pour la fiabilité. Le développement de techniques de suivi et de contrôle devient ainsi essentiel afin de garantir la fiabilité des mémoires volatiles et non volatiles. Dans le cadre de ma thèse, je me suis intéressée à deux types de mémoires : les mémoires NAND Flash et les mémoires SRAM. Pour contrôler les effets de la température sur les mémoires Flash, une solution basée sur l’utilisation d’un timer a été proposée afin de réduire la fréquence de rafraîchissement de ces mémoires tout en continuant à garantir l’intégrité de l’information stockée. Pour les mémoires SRAM, l’effet de la température sur la vulnérabilité par rapport aux événements singuliers (SEU) a été étudiée. Une étude comparative sur l’apparition des SEU a été menée avec différentes températures pour des cellules standards 6T-SRAM et des cellules de stockage durcies (DICE). Enfin, une méthode statistique et une approximation calculatoire basées sur des opérations de vérification périodique ont été proposées afin d’améliorer le taux d’erreurs (RBER) tolérable dans des SSDs de type Entreprise à base de mémoires FlashWith the constant increase of microelectronic systems complexity and the continual scaling of transistors, reliability remains one of the main challenges. Harsh environments, with extreme conditions of high temperature and thermal cycling, alter the proper functioning of systems. For data storage devices, high temperature is considered as a main reliability threat. Therefore, it becomes essential to develop monitoring techniques to guarantee the reliability of volatile and non-volatile memories over an entire range of operating temperatures. In the frame of this thesis, I focus my studies on two types of memories: NAND Flash memories and SRAM. To monitor the effects of temperature in NAND Flash Memories, a timer-based solution is proposed in order to reduce the refresh frequency and continue to guarantee the integrity of data. For SRAM memories, the effect of temperature on Single Event Upset (SEU) sensitivity is studied. A comparative study on SEU occurrence under different temperatures is conducted for standard 6T-SRAM cells and hardened Dual Interlocked Storage Cells (DICE). Finally, statistical and computational approximation techniques based on periodic check operations are proposed in order to improve the tolerated Raw Bit Error Rate (RBER) in enterprise-class Flash based SSDs
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Al-Ali, Abdullah Mubarak Abdulmohsen. "Temperature effects on fine-grained soil erodibility." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32514.
Full textAbstract:
Master of ScienceCivil Engineering
Stacey Tucker
Recent climate changes may affect the stability of our infrastructure in many ways. This study investigated the effects of fine-grained soil temperature on erosion rate. If climate change is shown to affect the erodibility of soils the impacts must be identified to monitor the stability of existing infrastructure, improve design of levees and structures founded in erosive environments, and to prevent sediment loss and stream meanders. Fine-grained soil erosion is complicated by the dynamic linkage of multiple parameters, including physical, biological and geochemical properties. This study held constant all parameters that influence fine-grained soil erodibility while only varying soil temperature in order to study the effects it has on erodibility. This study also confirmed previous findings that water temperature affects soil erodibility. The main objective of this study was to investigate the effects of fine-grained soil temperature on erosion rate. This study also instrumented a turbidity sensor to reliably map soil erosion. Based on this research, the conclusion was made that an increase in soil temperature increases soil erosion rate. The turbidity sensor was a valuable tool for comparing soil erosion. Future studies should investigate the effects soil temperatures below room temperature, the magnitude of temperature increase or decrease, and the effects of cyclic heating and cooling on fine grained soil erodibility.
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Whelton, Andrew James. "Temperature Effects on Drinking Water Odor Perception." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/36221.
Full textAbstract:
Thirteen volunteer panelists were trained according to Standard Method 2170, flavor profile analysis (FPA). Following training these panelists underwent triangle test screening to determine whether or not they could detect the odorants used in this study. Following triangle testing, panelists underwent directional difference testing to determine if temperature affected odor perception when presented with two water samples. Following directional difference testing, panelists used FPA and evaluated water samples that contained odorants at either 25°C or 45°C. Samples containing geosmin cooled to 5°C were also evaluated.
Sensory analyses experiments indicate that odor intensity is a function of both aqueous concentration and water temperature for geosmin, MIB, nonadienal, n-hexanal, free chlorine, and 1-butanol. The higher water temperature resulted in an increase in odor intensity for some, but not all, concentrations of geosmin, 2-methylisoborneol, trans-2, cis-6-nonadienal, n-hexanal, free chlorine, and 1-butanol. Additionally, above 400 ng/L of geosmin, 400 ng/L of MIB, and 100 ng/L the odor intensity was equal to or less than the odor intensity at 600, 600, and 200 ng/L, respectively. Henry's Law should predict that an increase in concentration would increase the amount of odorant the panelist comes into contact with; however, results demonstrated that at specific aqueous odorant concentrations odor perception did not follow Henry's Law. Odor response to drinking water containing isobutanal was affected by concentration but not water temperature.
Master of Science
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Matsuda, Hiroshi. "Effects of Temperature on Cherimoya Reproductive Organs." Kyoto University, 2015. http://hdl.handle.net/2433/199367.
Full textAbstract:
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19043号
農博第2121号
新制||農||1032(附属図書館)
学位論文||H27||N4925(農学部図書室)
31994
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 縄田 栄治, 教授 田中 千尋, 教授 北島 宣
学位規則第4条第1項該当
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Paula, Adson Agrico de. "The airfoil thickness effects on wavy leading edge phenomena at low Reynolds number regime." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-27092016-153422/.
Full textAbstract:
Recently, the wavy leading edge airfoils, inspired by the humpback whale´s flipper, have been investigated, as flow control mechanisms, at low Reynolds numbers in order to improve aerodynamic performance in this particular flow regime. The overall aim of this work is to investigate the airfoil geometric effects on wavy leading edge phenomena in the low Reynolds number regime. Experimental investigations were carried out correlating force measurements with mini-tuft and oil visualizations in order to understand the airfoil thickness effects on wavy leading edge phenomena. Three sets of airfoil thickness were tested (NACA 0012, NACA 0020 and NACA 0030), each set consisting of smooth plus three wavy configurations (A=0.11c, ?=0.40c; A=0.03c, ?=0.40c and A=0.03c, ?=0.11c); Reynolds number was varied between 50,000 and 290,000. The results present many findings that were not possible in previous studies due the fact that these investigations were constrained to specific geometries and/or flow conditions. At higher Reynolds number, the decrease in airfoil thickness leads the airfoils to leading edge stall characteristics causing the lowest aerodynamic deterioration for the thinnest wavy airfoil as compared to smooth configuration in the pre-stall regime. In addition, the results show impressive tubercle performance in the lowest Reynolds number. For any tubercle geometry and airfoil thickness, the wavy leading edge airfoils present higher maximum lift values as compared to smooth configurations showing an unprecedented increase in performance for a full-span model tested in the literature. The flow visualizations present two flow mechanisms triggered by secondary flow: three-dimensional laminar separation bubbles and vortical structures. Regarding three-dimensional laminar bubbles, the results confirm some of the few previous experimental and numerical studies, and presents for the first time these structures as a very efficient flow control mechanism in the post-stall regime justifying the impressive increase in maximum lift in the lowest Reynolds number. Besides that, two characteristics of laminar bubbles, \"tipped-bubbles\" and \"elongated-bubbles\", are identified with different effects in the pre-stall regime. This thesis presents higher tubercle performance for thinner airfoils (NACA 0012) and/or lower Reynolds number conditions (Re=50,000) showing clearly that an optimum performance lead the \"tubercles\" to operate under conditions of leading edge flow separation conditions. Therefore, a design space for tubercles conducted to leading edge stall characteristics confirming the hypothesis of Stanway (2008) eight years before.Recentemente, aerofólios com bordo de ataque ondulados, inspirados na nadadeira da baleia jubarte, tem sido investigados como mecanismo de controle de escoamento para baixo número de Reynolds com a finalidade de se aumentar o desempenho aerodinâmico neste específico regime de escoamento. O objetivo geral deste trabalho é investigar os efeitos geométricos do aerofólio nos fenômenos do bordo de ataque ondulado na condição de baixo número de Reynolds. Investigações experimentais foram realizadas correlacionando medições de forças com visualizações de lã e óleo a fim de compreender os efeitos da espessura do aerofólio sobre os fenômenos de bordo de ataque ondulado. Três conjuntos de espessura de aerofólios foram testados (NACA 0012, NACA 0020 e NACA 0030) na faixa de número de Reynolds entre 50,000 e 290,000, onde cada conjunto tem um aerofólio liso e três ondulados (A = 0.11c, ? = 0.40c; A = 0.03c, ? = 0.40c e A = 0.03c, 0.11c ? =0.11c). O dados experimentais mostram importantes resultados que não foram possíveis em estudos anteriores devido às investigações serem restritas à geometria ou/e condição de escoamento específicas. O resultados de medida de força mostram que a diminuição da espessura do aerofólio conduz às características de separação de escoamento de bordo de ataque que causam menor deterioração aerodinâmica nos aerofólios ondulados finos quando comparados aos lisos no regime de pré-stall. Além disso, os resultados mostram um desempenho destacado do bordo de ataque ondulado para condição de menor número de Reynolds. Em quaisquer espessuras de aerofólio, os bordos ondulados apresentam valores de sustentação máxima maiores quando comparado aos aerofólios lisos mostrando assim resultado inédito na literatura para modelos ondulados bi-dimensionais. As visualizações de óleo evidenciaram dois mecanismos de controle de escoamento desencadeadas pelo escoamento secundário: bolhas de separação laminar tridimensionais e estruturas vorticais. Os resultados confirmam alguns poucos estudos experimentais e numéricos anteriores relacionadas com bolhas tridimensionais, e apresenta pela primeira vez estas estruturas como um mecanismo muito eficiente de controle de escoamento em regime de pós-stall justificando o aumento de máxima sustentação para o menor número de Reynolds. Adicionalmente, foram identificadas duas estruturas de bolhas tridimensionais nomeados aqui como \"bolhas com pontas\" e \"bolhas alongadas\" que causam distintos efeitos no regime de pré-stall. Esta tese apresenta como resultado maior desempenho para aerofólios ondulados com menor espessura (NACA 0012) e/ou para condições de menor número de Reynolds (Re=50,000)mostrando claramente que estas características levam as ondulações a operarem em condições de stall de bordo de ataque assim tendo um desempenho superior. Portanto, um espaço de projeto para tubérculos conduz às características de stall de bordo de ataque confirmando a suposição de Stanway (2008) oitos anos antes.
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O'Donnell, Alison J., Kathryn J. Allen, Robert M. Evans, Edward R. Cook, and Valerie Trouet. "Wood density provides new opportunities for reconstructing past temperature variability from southeastern Australian trees." Elsevier B.V, 2016. http://hdl.handle.net/10150/621340.
Full textAbstract:
Tree-ring based climate reconstructions have been critical for understanding past variability and
recent trends in climate worldwide, but they are scarce in Australia. This is particularly the case for
temperature: only one tree-ring width based temperature reconstruction – based on Huon Pine
trees from Mt Read, Tasmania – exists for Australia. Here, we investigate whether additional tree-
ring parameters derived from Athrotaxis cupressoides trees growing in the same region have
potential to provide robust proxy records of past temperature variability.
We measured wood properties, including tree-ring width (TRW), mean density, mean cell wall
thickness (CWT), and tracheid radial diameter (TRD) of annual growth rings in Athrotaxis
cupressoides, a long-lived, high-elevation conifer in central Tasmania, Australia. Mean density and
CWT were strongly and negatively correlated with summer temperatures. In contrast, the summer
temperature signal in TRW was weakly positive. The strongest climate signal in any of the tree-ring
parameters was maximum temperature in January (mid-summer; JanTmax) and we chose this as the
target climate variable for reconstruction. The model that explained most of the variance in JanTmax
was based on TRW and mean density as predictors. TRW and mean density provided complementary
proxies with mean density showing greater high-frequency (inter-annual to multi-year) variability
and TRW showing more low-frequency (decadal to centennial-scale) variability. The final
reconstruction model is robust, explaining 55% of the variance in JanTmax, and was used to
reconstruct JanTmax for the last five centuries (1530–2010 C.E.). The reconstruction suggests that the
most recent 60 years have been warmer than average in the context of the last ca. 500 years. This
unusually warm period is likely linked to a coincident increase in the intensity of the subtropical
ridge and dominance of the positive phase of the Southern Annular Mode in summer, which weaken
the influence of the band of prevailing westerly winds and storms on Tasmanian climate. Our
findings indicate that wood properties, such as mean density, are likely to provide significant
contributions toward the development of robust climate reconstructions in the Southern
Hemisphere and thus toward an improved understanding of past climate in Australasia.
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Zhang, Yiping. "Effects of temperature on foamy solution gas-drive." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0020/MQ48073.pdf.
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D'Entremont, Hélène. "Temperature effects on Biolog community level physiological profiles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62341.pdf.
Full text
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Obakponovwe, Okite. "Temperature effects in fatigue of alumina-filled PMMA." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406398.
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McEvoy, James P. "Temperature and solvent effects in protein film voltammetry." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249424.
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Chang, Fu An, and 張富安. "Effects of Molded Temperature Gradient on the Thickness Distribution of Water-Assisted Injection Molded Parts." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/38184020506106421090.
Full textAbstract:
碩士長庚大學
機械工程研究所
96
ABSTRACT The study investigated the effects of molded temperature gradient on the thickness distribution of water assisted injection molded parts. Experiments were carried out on an 80-ton injection-molding machine equipped with a laboratory scale water injection system, which included a water pump, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit. The materials used in this study were two different melt flow rate polypropylene. Various processing variables were studied in terms of their influence on the thickness distribution of molded parts, including melt temperature, mold temperature gradient, water temperature, water pressure, short shot size, water hold and water injection delay time. In addition, the water assisted process was compared with gas assisted process. For single parameter of water assisted process, the major influence the thickness distribution was the melt temperature, mold temperature gradient and water pressure. For single parameter of gas assisted process, the major influence the thickness distribution was the melt temperature and mold temperature gradient .In water assisted process, the result found that the mold temperature gradient in two different melt flow rate polypropylene has give different thickness distribution.
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Chu, Yu-Yi, and 朱育儀. "The Effect of Temperature and Thickness on Thin Part Injection Molding." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/30642499442302495207.
Full textAbstract:
碩士國立成功大學
航空太空工程學系
87
With the increase demand for plastic, the production is more concentrated on improvement of quality and accuracy of plastic products. And, it also becomes a trend to make products of lighter and smaller. Among many of the manufacturing processes, injection molding is one of the most widespread method for fabricating plastic parts.In this article, we have a closer look on how temperature and thickness affect the mold filling on thin part injection molding. By using different mold temperatures and the thicknesses of a mold cavity, we can observe the effect of molding and also measure the change of temperature. The thinner the specimen, the more serious the problem of short shot. But after raising the mold temperature and injection pressure, the improvement is not as much as in the case of molding a thin part. We find that the effect of mold filling between mold temperature 80℃ to 120 ℃ have no much difference. Thickness is the major factor in this experiment. We also use electron microscopes to observe the cross section of the molding specimen that contains short glass fiber. There are a lot of article that have had some relative research about the effect of injection molding thickness, but the discussion of thin part molding is not quite complete. This experiment investigates the effect of some factors such as mold temperature and thickness on the thin part injection molding.
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Chang, Chih-Wei, and 張志偉. "Effects of Dopant Out-Diffusion Deposited Different Poly-Si Thickness and Temperature for Buried Strap of DRAM Technology." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/10183557199169007376.
Full textAbstract:
碩士長庚大學
電子工程研究所
93
In DRAM process, a deep trench’s 2nd poly-Si & 3rd poly-Si play the key roles as buried strap forming supplier. As impurity in poly-Si crystal went through intrinic poly-Si and nitride interface diffusing into silicon subsrate. The various poly-Si process cause different impurity mobility and solid solubility, it also affect the concentration of As in buried strap region and directly control burid strap contact resistance. The stability of contact resistance of buried strap is a significant index to make a healthy array device of DRAM(Dynamic Ramdom Access Memory). Higher contact resistance will cause the charge sharing fail due to RC delay from deep trench capacitor to bit line in DRAM operation. Lower contact resistance will also cause sub-threshold leakage from nMOSFET device due to As over-diffusing to nMOSFET channel. In this thesis, I study the character of As doped poly-Si to provide a clear mechanism to help us well known the relationships between poly-Si and nMOSFET device to overcome the challenge from deep sub micron generation of DRAM process.
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Lu, Bo-Ning, and 盧柏寧. "Effects of die thickness and underfill thickness above chip on structural stresses in an overmold CSP module under the conditions of reflow, underfill curing process, and temperature cycling." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/76647469407236642970.
Full textAbstract:
碩士國立屏東科技大學
材料工程研究所
104
This study reports the improvement of a commercial product of CSP module, in which the underfill is not dispensed, leading to the electricity failure after temperature cycling test (300 cycles). This electricity failure appeared at the top-corner of die due to the rupture of outermost solder ball via the failure analysis. Using Solidworks and ANSYS, this study constructed a 3-D model to numerically investigate structural stresses in a CSP module dispensed the underfill under the conditions of reflow, underfill curing process, and temperature cycling. This study also investigates the degree to which the die thickness and underfill thickness above chip influence structural stresses in a wrapped CSP module. The numerical results revealed the following important findings. (1) An obvious decrease in the stress in the solder balls after the underfill curing process. (2) As the die thickness and underfill thickness above chip decreased, during the processes of reflow and underfill curing, the warpage in the wrapped CSP module became obvious, but variations in the stress and plastic strain energy density were not obvious. (3) The addition of underfill proved effective in suppressing the accumulation of energy in the solder balls during the variation in temperature.
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Tzu-HuaChen and 陳姿樺. "Study of Transparent Visible-Light-Active TiO2 Self-Cleaning Surfaces–Effects of N-Doping Temperature and Thin Film Thickness." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/15323791739392581849.
Full textAbstract:
碩士國立成功大學
化學工程學系碩博士班
98
The main purpose of this work is to fabricate a transparent visible-light-active nitrogen-doped TiO2/SiO2 self-cleaning surfaces. All-nanoparticle thin film coatings on glass substrates by electrostatic layer-by-layer (ELbL) assembly of 7 nm TiO2 and 22 nm SiO2 nanoparticles were performed. Followed by periodic calcination process after every 30 bilayers, then calcine the coatings under ammonia gas flow with different temperature and number of bilayer, multibilayer nitrogen-doped nanoparticulate thin films (TiO2-δNδ/SiO2 )X with x=1-120 can be fabricated and to determine effects of N-doping temperature and thin film thickness under visible light illumination. Antireflective property was exhibited by all of the nanoparticulate thin films fabricated as revealed by UV-vis transmittance spectra. In addition, average refractive indices of the nanoparticle thin films about 1.31±0.05 and linear growth behavior nearly 20.03±0.07 nm for a bilayer of the multilayers were determined using ellipsometry and scanning electron microscopy. According the result of experiment, N-doped TiO2 thin film can be fabricated by different calcination temperature under NH3 gas flow and extend absorbance wavelength from UV light to visible light. Beside, there is an optimum calcination temperature condition (500℃/NH3) to show the best photocatalytic activity which is evaluated by the degradation of methylene blue under visible light illumination. This suggests that the isolated narrow band formed above the valence band is responsible for the visible light response in the present N-doped TiO2 but nitrogen doping is likely to be accompanied by oxygen vacancy formation. Furthermore, photocatalytic degradation of methylene blue by the nanoparticle thin films with different number of bilayers under visible light illumination showed the same self-cleaning property.
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Liao, Chin-Chung, and 廖進忠. "Effect of Coating Thickness of Silicon Resin on Resistance and Surface Temperature in Power Resistors." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/78640537227978086672.
Full textAbstract:
碩士中原大學
機械工程研究所
93
Abstract Silicon based polymeric coating is widely used for the protective coating of the resistors in the industry. Due to its properties of good insulation and non-flammability. This study is investigating the effect of the heat conduction properties of silicon based polymeric coating on the heat loading of the cylindrical shape ceramic rods system with different thickness of the coating on the surface. The ceramic rods contain 85% of Al2O3 and the surface is spray-coated with tin oxide (SnO2) as the conductive film. This conductive film will go through spiral grove type of cutting process to raise the resistance value of the conductive film to higher values. The surface of the processed filmed rods will be covered either with no silicon coating or different thickness (0.0435㎜、0.155㎜、0.3365㎜) of silicon coating. Under the same rated power applied to the ceramic rods system, the surface temperature of the rods is measured. When the coating is thicker, the surface temperature is lower and the cooling rate is also slower. Based on the percentage change of resistance value of the conductive film in the load same rated power 1000hr test, also indicates the lower surface temperature from a thicker coating. Besides the thickness of the coating that will affect the surface temperature of the system, the concentration of the Al2O3 and the dimension of the ceramic rods will also be important factors. Among them, the most critical one should be the content of Al2O3 which will dominate the heat resistance of the ceramic rod resistor system. In this study, the physical properties of the spray-coated SnO2 film and its process temperature as well the content of the Al2O3 (85%) and dimension of the ceramic rods (φ4.5㎜*14㎜) are fixed, the effect of different thickness of the silicon coating on the surface temperature of the system was studied. This was also been studied about the effect on the reliability property of the power type resistors under load life test (ambient temperature is 70℃and 1,000 hours of duration time). This is based on the percentage change of the resistance value from the load life test. From the analysis, the results can be summarized as follows: (1). Under the same loading power, and coating thickness is smaller than 0.3365mm, the surface temperature of the system is lower when the coating is getting thicker. (2). The different spray-coated temperature with metal oxide (SnO2) as the conductive film based ceramic composition, under the same voltage loading condition, and different pray-coated temperature on 680℃and 800℃, the percentage of change of the resistance value is smaller at 800℃than it at 680℃. (3). By lowering the surface temperature of the system, the percentage of change of the resistance value of the resistor components under load test for 1000 hour is reduced.
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CHANG, BETRAND, and 張博程. "Study of the relation between Y3Fe5O12 film thickness and curie temperature by magneto-optical effect." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/34868890227710013712.
Full textAbstract:
碩士國立臺灣大學
物理學系研究所
86
Because the method of pulsed laser deposition (PLD) can make the target material deposited on substrate with its components almost the same , complex multicomponent compounds can be grown easily by PLD . In this experiment , We grow Y3Fe5O12 (YIG) thin film with various thickness by using Gd3Ga5O12 (GGG) as substrate at the temperature of 800℃ and oxygen pressure of 200 mTorr . The measurememt of film thickness and surface roughness is according to the technique of grazing angle X-Ray reflectivity and the Refs software works well in the simulation of experimental results . The magneto-optical effect of YIG thin film can be investigated by Kerr method . Because the linearly polarized light may become elliptically polarized after it reflects from thin film and its rotation angle is proportional to the thin film magnetization , we can get the relation between thin films thickness and curie temperature by measuring these angles with the temperature changed . In order to reduce the background noise and measure the angles at good accuracy ,we use photoelastic modulator (PEM) to make this more easily .
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Simões, Tânia Sofia Ribeiro. "Moisture buffering capacity of earth mortar plasters and hemp concrete. Effect of temperature and thickness." Master's thesis, 2015. http://hdl.handle.net/10362/99920.
Full textAbstract:
Earth mortar plasters and hemp concrete are hygroscopic materials since they have the ability to uptake and release water vapour. These materials can be used for a passive control of relative humidity (RH) inside buildings, with the benefits of improving the health and comfort of the occupants, as well as reducing the energy consumption of buildings. The quantification of this passive control potential for buildings material has been extensively studied by the scientific community since the last decade. These studies notably lead to the Nordtest project (Rode et al. 2005) where the concept of Moisture Buffering Value (MBV) was developed, as well as a test protocol in order to quantify this characteristic of the material.
The main objective of this dissertation is to study the impact of temperature and thickness of a coating material on its passive regulation potential of indoor air RH. For that purpose, two types of hygroscopic coatings materials are studied: earth mortar plasters and hemp concretes. The influence of the thickness is analysed through dynamic MBV test (“Moisture Buffering Value“ test) at 23°C on three formulations of each material (earth and hemp concrete) at three different thicknesses. The influence of temperature is performed only for hemp concrete formulations on static (sorption curves) and dynamic (MBV tests) tests at 23°C and 40°C.
The analysis of the results, made using the support of theoretical models, allows underlining that the thickness involved in the daily passive control of RH remains most of the time limited (only the first centimetre of the earth plasters and 5cm for hemp concretes). However, some surface irregularities may have a strong impact on this active thickness. The other main result of this dissertation is the strong impact of temperature on both static and dynamic hygroscopic characteristics of the material. Indeed, the increase of temperature at a constant RH tends to significantly reduce the water content of the material. But, on the other side, due to higher vapour pressure at saturation and water vapour diffusion coefficient, the dynamic sorption-desorption properties increased with temperature by approximately 65%.Developed within the IBIS project and BIOTERRA project with the collaboration of the "Direction Territoriale Centre-Est" of the CEREMA
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Wang, Yen-Hsiang, and 王彥翔. "Effects of the thickness and position of chip on structural stress of the chip-scale-package on module under temperature cycling condition." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/69787798297346866024.
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碩士國立屏東科技大學
機械工程系所
101
The solder joints of the CSP module is the electrical pass between the CSP and carrier PCB substrate. In this study, the primary failure of the CSP module is the bulk solder failure by SEM examination under temperature cycling test condition. To investigate the structural stresses under reflow and temperature cycling conditions, a 3D model was established for stress simulation using the finite element analysis ANSYS software. The result shows the failed solder joint which is at the upper right corner of the CSP has the largest von Mises stress and is consistent with the SEM observations. We also consider the effects of the thinkness and position of CSP on the structural stress of module. The simulation results show the stresses clecrease with decreasing the thickness of the CSP and the effect of position is not significant increase of stress of CSP module.
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Tu, Cheng Hsin, and 杜承鑫. "The Effect of membrane thickness, cell temperature, and methanol concentration on methanol crossover and fuel cell performance." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/33977470410708916340.
Full textAbstract:
碩士元智大學
機械工程學系
91
ABSTRACT Methanol crossover will largely affect the efficiency of power generation in direct methanol fuel cell. Although methanol will spontaneously oxidize at the cathode, it also causes serious overpotential and conversion loss in terms of lost fuel. In this study, by changing the operating condition (ex. membrane thickness, cell temperature, methanol solution concentration), we found how these parameters affect methanol crossover and power generation in direct methanol fuel cell. By fixing the membrane thickness, we found that the increasing temperature will obviously promoting the cell performance, and low methanol solution concentration will cause concentration polarization therefore resulting in lower cell performance. Although high methanol solution concentration will overcome the concentration polarization, serious methanol crossover will lower the cell performance at high operating temperature. From this study, we found that open circuit voltage will be in inverse proportion to methanol solution concentration and methanol crossover, and will be in proportion to membrane thickness and cell temperature. Although increasing membrane thickness will lower the degree of methanol crossover, it will also increases the distance for ion to transport. Therefore, the cell performance including Nafion 117 is lower than Nafion 112. Keywords: direct methanol fuel cell (DMFC)，Overpotential，Crossover，concentration polarization
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Mulvaney-Johnson, Leigh, Elaine C. Brown, and Philip D. Coates. "Ultrasonic measurement of residual wall thickness during gas assisted injection moulding." 2007. http://hdl.handle.net/10454/3138.
Full textAbstract:
NoUltrasonic technology provides a powerful and noninvasive method of in-process measurement during injection molding and extrusion. Changes in the velocity, attenuation and reflection coefficients of high frequency sound waves can be related to the state and conditions of the materials through which they propagate. The velocity of an ultrasonic wave changes with density and elastic moduli; this allows information on solidification and material properties to be collected during the molding cycle. The time of flight of the wave is a function of velocity and path length. This paper shows that it can be correlated with the residual wall thickness of polymer in the mold during gas assisted injection molding.
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Wang, Tza-Hao, and 王澤豪. "Study The Pattern and Thickness Effect on Low- Temperature Polycrystalline Silicon Thin Film Induced by Nickel Silicide Crystallization Method." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/46541960080822608482.
Full textAbstract:
碩士國立清華大學
材料科學工程學系
89
Abstract Low-temperature polycrystalline silicon (poly-Si) thin film has been widely studied. Among various approaches, the most useful method to mediate crystallization is metal induced crystallization (MIC) or metal induced lateral crystallization (MILC). In the MIC or MILC process, Ni is deposited on amorphous silicon (a-Si). Consequently, NiSi2 forms upon annealing. As the NiSi2 moves further towards the a-Si region, poly-crystalline Si forms behind the NiSi2 front. It is known that the quality of crystallinity of poly-Si thin film will deeply affect the electrical properties of the transistor. How to get a good quality poly-Si via low-temperature process is important. It is shown that both the deposited Ni pattern and the thickness of a-Si layer significantly affect the crystallization rate, crystallinity and the residual Ni impurities in the poly-Si thin film. In this work, these effects will be discussed and a model will be proposed to explain them. In the first section, we will discuss the geometrical effect of the Ni pattern on the quality of crystallization silicon. From optical microscopy (OM) images, we find that a-Si covered with patterned Ni whose pattern curvature is smaller would exhibit a high crystallization velocity. In contrast, a pattern having a larger curvature leads to a smaller crystallization velocity. Transmission electron microscopy (TEM) and Raman spectroscopy indicate that the crystallinity of MILC of a-Si covered with a rectangular layer of Ni is better than that covered with a circular layer of Ni. From SIMS analysis, the residual Ni concentration in MILC of a-Si covered with Ni rectangles is smaller when compared to that of a-Si covered with Ni circles. In the second section, the effect of a-Si layer thickness will be discussed. From the OM images, the MILC crystallization rate increases with the thickness of a-Si. X-ray Diffractometer (XRD), TEM and Raman spectroscopy, show that the grain size of crystal silicon of thicker a-Si is larger with better crystallinity. SIMS analysis indicates that the residual Ni concentration in the MILC layer is smaller in 1000Å a-Si case than that in the 300 Å a-Si layer.
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Hsieh, Yi-Chieh, and 謝易桀. "Effects of die thickness and underfill dispensing shape on structural stresses in a CSP module under the conditions of reflow, underfill curing process, and temperature cycling." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/05363384824857224193.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
104
This study reports the improvement of a commercial product of CSP module, in which the underfill is not dispensed, leading to the electricity failure after temperature cycling test (300 cycles). This is attributed to the rupture of solder balls through the failure analysis. Using Solidworks and ANSYS, this study constructed a 3-D model to numerically investigate structural stresses in a CSP module dispensed the underfill under the conditions of reflow, underfill curing process, and temperature cycling, which can be used to support the possibility of using underfill to promote the reliability in the CSP module. This study also investigates the degree to which the die thickness as well as dispensing shape and height of underfill influence structural stresses in a CSP module. The numerical results revealed the following important findings. (1) The addition of underfill in a CSP module can reduce the stress and suppress the accumulation of plastic strain energy density in the solder balls. (2) A decrease in the die thickness led to the reductions in the stress and plastic strain energy density in the solder balls. (3) Changes in the shape and height of underfill can not obviously affect the stress and plastic strain energy density in the solder balls; however, these changes significantly influence the stress in the die.