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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
731

Nanostructured Microcantilever for the Detection of Volatile Compounds

McNeilly, Ryan J. 20 December 2017 (has links)
No description available.
732

Use of Torrefied Sorghum as Eco-friendly Filler in Styrene Butadiene Rubber

Sun, Weicheng 14 September 2018 (has links)
No description available.
733

Analysis of Measurement of Analytes level in Girls age 6-9 year old

Dikong, Gabriel N. 04 August 2011 (has links)
No description available.
734

Cometabolic Degradation of Halogenated Aliphatic Hydrocarbons by Aerobic Microorganisms Naturally Associated with Wetland Plant Roots

Smith, Madelyn M. 13 July 2012 (has links)
No description available.
735

Konstruktion och utveckling av träningsmaskin för basövningar / Design and development of exercise machine for compound exercises

Stenberg, Tom, Kamal, Yousuf, Ljung, Christian January 2021 (has links)
Träning och fysisk aktivitet har kommit att bli alltmer av en lärdom i en nutid och framtid som präglas av en allt mindre aktiv livsstil. Opinionen i rapporterade undersökningar och statistik visarpå en tydlig och permanent övergång till en mer flexibel och digital arbetsplats med mindre avsatt kontorstid i veckan. En lösning till problemet är användningen av en multifunktionell träningsmaskin för hemmabruk med möjlighet till träning som kan motsvara ett fulländat helkroppspass. En tydlig majoritet av studier och branschexperter hävdar att marknaden för hemmagym och träningsredskap för hemmabruk kommer att växa. Samtidigt är utbudet av träningsmaskiner påmarknaden för hemmabruk som möjliggör basövningar knapphändig. Projektets mål är att utveckla och konstruera en träningsmaskin som möjliggör effektiv belastande helkroppsträning. Produktutvecklingsprocessen utgörs av ett antal aktiviteter som utförs för att förstå, konstruera och marknadsföra produkter. Den tillämpade produktutvecklingsmetoden utgår från en hybrid av den allmänna produktutvecklingsprocessen enligt Ulrich och Eppinger samt projektmodellen somanvänds vid KTH Södertälje. Träningsmaskinen konstrueras med utgångspunkt i en kombination av ett så kallat power rack, en kubisk ram av stålbalkar som används vid skivstångsövningar, och en kabelmaskin tillämpad för att genomföra de sex vanligaste basövningarna för att uppnå en fullständig helkroppsträning. Ett antal befintliga lösningar på marknaden i kombination med en nyskapande talja implementeras föratt optimera och effektivisera såväl träningen som hemmabruk. Träningsmaskinen lämpar sig som såväl ett substitut som komplement till fria vikter samtidigt som stabiliteten och användarvänligheten förekommande hos kommersiella träningsmaskiner tas tillvara. Slutligen presenteras träningsmaskinen som en prototyp vars avsikt är att påvisa genomförbarheten med denna typ av utformning av träningsmaskin. / Exercise and physical activity have become more of an achieved knowledge in a present and future that is characterized by an increasingly less active lifestyle. The reported trend in surveys shows adistinct and permanent transition to a more flexible and digital workplace with less weekly office hours. One solution to the problem is the use of a multifunctional exercise machine for home use with the possibility of exercise that correspond to a full body workout. A clear majority of studies and experts claim that the market for home gyms and equipment will continue to grow. At the same time, the availability of multifunctional exercise machines on the market for home usage that utilizes compound exercises is scarce. The goal of the project is to develop and design an exercise machine that enables effective whole bodytraining. The product development process consists of several activities that are performed to understand, design and market products. The applied product development method is based on a hybrid of the general product development process according to Ulrich and Eppinger and the project course model used at KTH Södertälje. The exercise machine is designed based on a combination of a power rack, a cubical cage made of steel beams that is used for barbell exercises, and cable machine applied to perform the six most common basic exercises to achieve a complete full body workout. Several existing solutions onthe market in combination with an innovative hoist are implemented to optimize and streamline both training and home use. The exercise machine is suitable as both a substitute and a complement to free weights, while at the same time taking advantage of the stability and user-friendliness of commercial exercise machines. Finally, the exercise machine is presented as a prototype whose intention is to demonstrate the feasibility of this type of exercise machine design.
736

BLOCK DESIGNS UNDER AUTOCORRELATED ERRORS

Shu, Xiaohua January 2011 (has links)
This research work is focused on the balanced and partially balanced incomplete block designs when observations within blocks are correlated. The topic for this dissertation was motivated by a problem in pharmaceutical research, when several treatments are allocated to individuals, and repeated measurements are taken on each individual. In that case, there is correlation among the observations taken on the same individual. Typically, it is reasonable to assume that the observations within individual close to each other are highly correlated than observations that are far away from each other. It is also reasonable to assume that the correlation between any two observations within each individual is same. We have characterized balanced and partially balanced incomplete block designs when observations within blocks are autocorrelated. In Chapter 3, we have provided an explicit expression for the average variance of estimated elementary treatment contrasts for designs obtained by Type I and II series of orthogonal arrays, under autocorrelated errors, and compared them with the corresponding balanced incomplete block designs with uncorrelated errors. The relative efficiency of balanced incomplete block design compared to the corresponding balanced incomplete block design obtained by Types I and II series of orthogonal array under autocorrelated errors does not depend on the number of treatments (v) and is an increasing function of the block size (k). When orthogonal arrays of Type I or Type II do not exist for a given number of treatments, we provided alternative partially balanced designs with autocorrelated errors. In Chapter 4, we rearranged the treatments in each block of symmetric balanced incomplete block designs and used them with autocorrelated error structure of the plots in a block. The C-matrix of estimated treatment effects under autocorrelation was given and the relative efficiency of symmetric balanced incomplete block designs with independent errors compared to the autocorrelated designs is given. In Chapter 5, we discussed the compound symmetry correlation structure within blocks. An explicit expression of the average variance of designs obtained by Type I and II series of orthogonal arrays and symmetric balanced incomplete block designs under compound symmetric errors has been provided and compared them with the corresponding balanced incomplete block designs with uncorrelated errors. Finally, the relative efficiencies of these designs with autocorrelated errors vs. compound symmetric error structure are given / Statistics
737

Experimental Characterization and Modeling of Tire-Ice Interface

Mousavi, Hoda 18 March 2021 (has links)
Tire parameters play a very important role in tire performance. Depending on the driving conditions for which a given tire is designed, its parameters must be chosen appropriately (e.g., the radius of the tire, the width of the tire, material properties of different sections). Among tire characteristics, the material properties of the rubber compounds have a vital role in tire behavior. Previous studies show that the material properties of the rubber are highly dependent on temperature. Thus, a comprehensive study on the effect of the material properties of the rubber on tire performance for different temperatures as well as different road conditions is required. In this study, a theoretical model has been developed for tire-ice interaction. The temperature changes obtained from the model are used to calculate the height of the water film created by the heat generated due to the friction force. Next, the viscous friction coefficient at the contact patch is obtained. By using the thermal balance equation at the contact patch, dry friction is obtained. Knowing the friction coefficients for the dry and wet regions, the equivalent friction coefficient is calculated. The model has been validated using experimental results for three similar tires with different rubber compounds properties. For the experimental part of this study, four tires have been selected for testing. Three of them have identical tire geometry and structure but different rubber tread compounds. Several tests were conducted for the chosen tires in three modes: free-rolling, braking, and traction. The tests were performed for two different normal loads (4 kN and 5.6 kN), two different inflation pressures (21 psi (144.8 kPa) and 28 psi (193 kPa)), and three tire temperatures levels (-10°C, -5°C, and -1 °C). The Terramechanics Rig at TMVS at Virginia Tech has been used for conducting the tests. The results from this study show the sensitivity of the magnitude of the tractive force with respect to parameters such as tire temperature, normal load, etc. The results also indicate that the tire with the lowest value of the Young modulus has the highest traction among all four tires used in this study. The model developed can be used to predict the temperature changes at the contact patch, the tire friction force, the areas of wet and dry regions, the height of the water film for different ice temperatures, different normal loads, etc. The results from this study coincide with the obtained results from the experiments. According to the data available, tire B with the smallest value of Young modulus and the smallest value of the specific heat parameter was shown to have the highest friction coefficient in both simulation and experiment. After validating the results using experimentally collected data, the model was used to perform a sensitivity analysis on the tire performance with respect to six material properties of the tread rubber: thermal conductivity, rubber density, Young's modulus, specific heat, roughness parameter of the rubber, and radii of spherical asperities of the rubber. The results from this study show the sensitivity of the magnitude of the friction coefficient to the rubber material properties. The friction coefficient has a direct relationship with the density of the rubber and has an inverse relationship with Young's modulus, specific heat, and roughness parameter. / Doctor of Philosophy / In order to decrease the number of deaths and injuries caused by driving on icy roads and increase the safety of the vehicle, it is important to improve the tire performance on ice. To this, understanding the effects of different tire and road parameters such as material properties of the rubber, loading condition, and temperature on the tire-ice performance is required. Tire parameters play a very important role in tire performance. Depending on the driving conditions for which a given tire is designed, its parameters must be chosen appropriately In this project, the effects of different tire and terrain parameters such as rubber material properties on tire performance on ice using an experimental and modeling approach have been studied. For the experimental part of this study, several tests were conducted for more than 30 tires with different material properties. The results of this study show what are the most important material properties of the rubber for designing a tire with the best performance on ice. For the modeling part of this study, a semi-analytical model was developed. The model was validated using collected experimental data and was used to predict the performance of the tire by having information about its material and physical properties. The developed model called ATIIM2.0 has several advantages. First, it is a unique model for a complete tire (not a rubber block) that can be used to predict the performance of the tire by using its material properties. In addition, this model can be connected to vehicle models to improve the performance of the vehicle in general. The model developed can be used to predict the temperature changes at the contact patch, the tire friction force, the areas of wet and dry regions, the height of the water film for different ice temperatures, different normal loads, etc. The results from this study coincide with the obtained results from the experiments.
738

Trends in pig product processing at British Neolithic Grooved Ware sites traced through organic residues in potsherds

Mukherjee, A.J., Gibson, Alex M., Evershed, R.P. January 2008 (has links)
No / Gas chromatography (GC), GC-mass spectrometry (GC-MS) and GC-combustion-isotope ratio MS (GC-C-IRMS) analyses of absorbed and surface lipid residues preserved in potsherds were used to explore the extent of pig product processing exploitation in the later British Neolithic Grooved Ware tradition. Assessments were made regarding whether porcine lipids were associated with specific Grooved Ware traits, i.e. decoration, substyle, geographical area and type of site. Two hundred and twenty-two Grooved Ware potsherds were analysed, 70% of which contained lipid concentrations considered significant (>5 μg g−1). All the lipid residues were dominated by animal fats, although plant and beeswax were also detected in a small number of extracts. δ13C values of the major fatty acid components of degraded animal fats (C16:0 and C18:0) were determined for 126 extracts and used to assign ruminant or porcine origins to the residues; 16% of these were found to have a predominantly porcine isotope signature. Statistical associations with pig exploitation were shown to exist with substyle, geographical area and site type, whereas, no relationship was seen between decoration and the type of commodity processed. Intact triacylglycerols were preserved in 19% of the sherds; half of these had distributions consistent with the identifications based on δ13C values, the remainder differed either due to the presence of mixed commodities or because lower molecular weight homologues had been lost due to degradation. In addition to the detection of pig exploitation, results from lipid residue analysis showed a good correlation with faunal assemblages, suggesting that stable isotope analysis may be used as a proxy for animal exploitation at sites where bones have not survived.
739

Estimation of flow direction in meandering compound channels

Liu, X., Zhou, Q., Huang, S., Guo, Yakun, Liu, C. 01 November 2017 (has links)
Yes / The flow in the main channel of a meandering compound channel does not occur in the ridge direction because of the effect of the upstream floodplain flows. This study proposes a model for estimating the flow direction in the depth-averaged two-dimensional domain (depth-averaged flow angles) between the entrance and the apex sections. Detailed velocity measurements were performed in the region between the meander entrance section and apex section in a large-scale meandering compound channel. The vertical size of the secondary current cell is highly related to the depth-averaged flow angle; thus, the means of the local flow angles above the secondary current cell and within the cell are separately discussed. The experimental measurements indicate that the mean local flow angle above the cell is equal to the section angle, whereas the mean local flow angle within the cell is equal to zero. The proposed model is validated using published data from five sources. Good agreement is obtained between the predictions and measurements, indicating that the proposed model can accurately estimate the depth-averaged flow direction in the meandering compound channels. Finally, the limitations and application ranges of the model are discussed. / National Key Research and Development Program of China (No. 2016YFC0402302), the National Natural Science Foundation of China (Nos. 51539007 and 51609160)
740

Real-Time Interfacial FTIR-Electrochemical Investigation of Smart Passivating Film for Extended Lifetime of Copper Containing Microelectronic Devices

Salunke, Ashish Shivaji 12 1900 (has links)
Copper (Cu) has been the main choice of the metallization in advanced IC package technology. The epoxy molding compounds (EMC) and the solder flux used in the packaging devices can release ionic impurities. In the halide environment, the electrochemical migration (ECM) failure and corrosion related failure of copper redistribution layer (RDL) and the Cu bond pads respectively was studied. Electrolytic migration arises when the IC package undergoes testing as per JESD22-A110 standards (130oC, 85% RH for 96/256 hrs.). Copper migration is fundamentally an ionic process that requires an electrolyte, moisture, and bias. To accelerate the time for investigating these failures, it was important to benchmark the metrology for real time observation of ECM failure under high voltage. Metrology for electrochemical defect analysis (MEDA) was developed to provide insight on failure mechanism. The Cu RDL on wafer level chip scale package devices were tested by PEG drop test (PDT) using non-aqueous polyethylene glycol (PEG) matrix doped with ions (Cl-, ClO4-, SO4-) to simulate EMC environment. PDT was conducted to analyze the real time migration behavior of Cu electrodes using a potentiostat and microscope. A novel Cu-selective passivation coating was applied on Cu either by wet processes or chemical vapor deposition (CVD) that are IC manufacturing compatible. This Cu-selective passivation coating is thermally stable, strongly adheres to Cu, corrosion resistant, low cost and shows good potential to prevent ECM defects at the high voltage bHAST condition. FTIR and potentiodynamic polarization were utilized to characterize the Cu-selective passivation coating. Statistically union of selected analytical techniques help to acquire unique results about the chemical systems. Together, electrochemistry and spectroscopy help to gather chemical information about the composition near and on the electrode. Additionally, during the SnAgCu (SAC) solder ball bonding on the Cu wafer by mass reflow process, solder flux is used to reduce the native oxides on Cu and SAC solder ball. Post cleaning, residual amount of the solder flux corrodes the Cu wafer. Passivation coating is used as an organic solder preservative to avoid the solder flux while facilitating a good bond between the SAC solder ball and Cu wafer. We investigated the efficiency of the passivation coating in preventing the copper thermal oxidation. The intermetallic compound formation between the Cu wafer and SAC solder ball was studied on 2nm, 6nm, 30nm and 50nm passivated Cu wafer. Based on the SEM/EDS analysis 1.7 µm CuxSny IMC was formed on 2nm coated cu wafer with a Cu:Sn ratio of 1.8:1 & 0.13:1.

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