The design of machine elements such as belts, chain and sprocket, gears, cams, bearings, etc., is a complex procedure. The analytical procedure to design such elements is non-linear, often based upon statistical information and frequently heuristic in nature. The procedure is iterative and involves choosing various weighing factors based upon the application and usage. The procedure is greatly influenced by a designer's intuitive skill and experience. Due to the increased popularity of the Internet as a source of information, a number of machine element manufacturers have published design procedures for the design of machine elements. Here, an attempt has been made to arrange all the formulae, tables, charts, standards, and web resources, which are inherent to the design process, to best aid the designer. A number of computer applications for machine design have been developed in the recent past but are limited in scope and utility as they tend to allow the designer to change only certain parameters while assigning fixed values to most parameters. This stifles the designer's creativity and diverts focus on the computer program rather than the physical problem. An attempt has been made here to allow the designer flexibility in design and increased productivity, by keeping a record of the various steps undertaken by the designer, in a particular design process. / Master of Science

In my dissertation, I developed mixed hp-finite element methods for linear elasticity with weakly imposed symmetry, which is based on Arnold-Falk-Winther's stable mixed finite elements. I have proved the h-stability of my method for meshes with arbitrary variable orders. In order to show the h-stability, I need an upper limit of the highest order of meshes, which can be an arbitrary nonnegative integer. / text

Ett examensarbete i informationsdesign med inriktning mot rumslig gestaltning. En studie av väntrum i primärvården i Södermanlands län, Eskilstuna, Smedens vårdcentral har genomförts kring hur väntrumsmiljöer påverkar besökaren. Syftet var att studera utformningen av hur ett väntrum kommunicerar information mellan verksamhet och besökare utifrån rumsupplevelse samt att förbättra känslan av trygghet i väntrummet. Arbetet har utförts genom att studera väntrum och målgruppens interaktion med rummet och dess information utifrån ett rumsligt perspektiv. Utifrån designprinciper och kognitionsteorier har rummets brister identifieras och vilka förbättringsmöjligheter som finns har synliggjorts. Utifrån empiri från litteraturstudier, intervjuer, omvärldsanalys, rumslig analys och observation skapades förståelse för besökarens behov. Detta gav ett underlag till ett gestaltningsförslag som skapar en tydligare identitet för rummet och som bidrar till en starkare informationslänk och bättre upplevelse mellan besökare och personal på vårdcentralen. Ett väntrum som kommunicerar information mellan myndighet och besökare utifrån rumsupplevelse i relation till hur det används, samt ökar känslan av trevnad och trygghet i väntrummen. Arbetet har resulterat i att ett gestaltningsförslag har tagits fram i 3D programmet, Sketch Up genom bilder och text som presenteras. Designförslaget bygger på de slutsatser som dragits, vilket är att skapa avskildhet och samhörighet genom valbarhet samt att dölja men även förmedla information mellan besökare och verksamhet.

This thesis is a summary of my research works at the MSM department of the University of Liège since 1989. These research works are devoted to the numerical simulation of the three-dimensional sheet metal forming processes by the finite element method. Several research areas, including the finite element modelling, the time-integration technique of material constitutive laws and the 3D contact treatments are covered. The theoretical methodologies, the numerical implementation and industrial applications will be presented. The thesis begins with a brief overview made in chapter 1. In chapter 2, a 8-node mixed brick element based on the HU-WASHIZU variational principle is developed (JET3D element). Special attention is paid to avoid hourglass modes as well as locking phenomena, including "shear locking" and "volumetric locking" in nonlinear analysis. Numerical examples are used at the end of this chapter to assess the performance and applicability of this element. In chapter 3, a 3D four-node shallow element, which was originally developed by Ph. JETTEUR and then has been improved by him and his co-workers, is recalled (COQJ4 element). Special care is taken to the finite rotation problems and a new formulation for the finite rotation is developed. An example is used at the end of the chapter to show the performance of the proposed formulation for the finite rotation problems. A special contact element is developed for the shell element in chapter 4. In this chapter, some basics aspects of numerical tretments of contact problem are discussed and some attentions are paid to the contact searching algorithms, which has proved to be very important in 3D cases. In chapter 5, the appropriate constitutive equations are examined together with the techniques of time-integration and the evaluation of the tangent stiffness matrix. Much attention is paid to the implicit integration methods, which have proved to be very efficient for large increments of deformation. Finally, in chapter 6, two benchmark tests are used as validation of the code. Special attention is paid to the possibility of using dynamic explicit procedure in the numerical simulation of sheet metal forming, although it is often characterised as a quasi-static process. All the developments made in the thesis have been implemented into the finite element code LAGAMINE developed since 1982 at the MSM department of the University of Liège.

In this thesis, we have explained the different types of DAC (Digital-to-Analog) architectures and their advantages and disadvantages. We have mainly focused on current-steering digital-to-analog design for achieving high speed and high performance. The current-steering DAC is designed using binary weighted architecture. The benefits of this architecture is that it occupies less area, consumes less power and the number of control signals required are very less. The requirements for high speed and high performance DAC are discussed in detail. The circuit is implemented in a state-of-the-art 65 nm process, with a supply voltage of 1.2 V and at a sampling speed of 2 GHz. The resolution of the DAC is 8-bits. The design of 8-bit current-steering DAC converts 8 most significant bits (MSBs) into their binary weighted equivalent, which controls 256 unit current sources. The performance of the DAC is measured using the static and dynamic  parameters. In communication applications the static performance measures such as INL and DNL are not of utmost importance. In this work, we have mainly concentrated on the dynamic performance characteristics like SNR (Signal to Noise Ratio) and SFDR (Spurious Free Dynamic Range). For measuring the dynamic parameters, frequency domain analysis is a better choice. Also, we have discussed how the pole-zero analysis can be used to arrive at the dynamic performance metrics of a unit element of the DAC at higher frequencies. Different methods were discussed here to show the effects of poles and zeroes on the output impedance of a unit element at higher frequencies, for example, by hand calculation, using Mathematica and by using cadence. After extensive literature studies, we have implemented a technique in cadence, to increase the output impedance at higher frequencies. This technique is called as “complimentary current solution technique”. This technique will improve the output impedance and SFDR compared to the normal unit element design. Our technique contains mostly analog building blocks, like, current mirrors, biasing scheme and switching scheme and few digital blocks like D-ff (D-flip flop). The whole system is simulated and verified in MATLAB. Dynamic performances of the DAC such as SNR and SFDR are found with the help of MATLAB.

This thesis reports onreview and research work carried out on the numerical analysis of elastomers. The two numerical techniques investigated for this purpose are the finite and boundary element methods. The finite element method is studied so that existing theory is used to develop a finite element code both to review the finite element method as applied to the stress analysis of elastomers and to provide a comparison of results and numerical approach with the boundary element method. The research work supported on in this thesis covers the application of the boundary element method to the stress analysis of elastomers. To this end a simplified regularization approach is discussed for the removal of strong and hypersingularities generated in the system on non-linear boundary integral equations. The necessary programming details for the implementation of the boundary element method are discussed based on the code developed for this research. Both the finite and boundary element codes developed for this research use the Mooney-Rivlin material model as the strain energy based constitutive stress strain function. For validation purposes four test cases are investigated. These are the uni-axial patch test, pressurized thick wall cylinder, centrifugal loading of a rotating disk and the J-Integral evaluation for a centrally cracked plate. For the patch test and pressurized cylinder, both plane stress and strain have been investigated. For the centrifugal loading and centrally cracked plate test cases only plane stress has been investigated. For each test case the equivalent results for an equivalent FEM program mesh have been presented. The test results included in this thesis prove that the FE and BE derivations detailed in this work are correct. Specifically the simplified domain integral singular and hyper-singular regularization approach was shown to lead to accurate results for the test cases detailed. Various algorithm findings specific to the BEM implementation of the theory are also discussed.

Abstract This study aims to understand the influence of weathering and human perturbation on spatial and temporal variability of major and trace element distributions in the Kaoping River basin. The collected data are used to elucidate the production, transport and export of major and trace elements from the Kaoping River basin. Experimental results show that the weathering index of the Kaoping River basin is rather high. The significant loss of major ions and enrichment of iron and aluminum from river suspended matter indicate the characteristic of high weathering rate in most tropical rivers. Particulate Si/Al mole ratios range from 1 to 2 showing that the distributions of dissolved and particulate matter are largely controlled by the weathering process of kaolinite and /or smectite formation. During the study period (2002), the physical and chemical weathering rates were estimated about 655.8 and 416.2 g/m2/yr, respectively. Both physical and chemical weathering rates are much lower than those estimated by Yang (2001) during the period of 1999-2000 [3601 g/m2/yr (physical weathering rate), 1146 g/m2/yr (chemical weathering rate)], due to significant difference in river discharge. However, the estimated physical and chemical weathering rates are still much higher than the world averages of physical (150 g/m2/yr) and chemical (33-40 g/m2/yr) weathering rates. The marked difference between this and Yang¡¦s estimates is caused from large difference in river discharge. Silicate weathering was estimated about 97.09 ¡Ó 2.41% of total chemical weathering in the Kaoping River basin. The temporal variations of enrichment factor (EF) for most particulate trace metals (Mn, Zn, Cu, Cr, Pb, Cd, and Hg) reveal a greater pollution status in the dry season than in the wet season. Spatial variations of EF also reveal a greater pollution in the downstream zone than in the upstream zone. Time-series observation showed that concentrations of particulate trace elements were inversely correlated with discharge. The significant correlation between the fluxes of dissolved and particulate trace elements and discharge suggesting that river discharge controlled largely the fluxes of major and trace elements. The annual variations of elemental fluxes were determined critically by the annual difference of river discharge. The distributions of particulate organic carbon (POC) and particulate nitrogen (PN) were similar between suspended matter in the Kaoping River and surface sediments in the Kaoping Canyon. The data of £_13Corg show that about 77.2% of organic matter derived from the Kaoping River basin deposit in the Kaoping Canyon. The Kaoping Canyon appears to play an important role on the transport and deposition of organic matter from the Kaoping River basin.

Not available / text

Thesis (Ph.D.)--University of Western Australia, 2006.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 232-235). Also available via the Internet.