Engineering Commons^™

Polymeric Impulsive Actuation Mechanisms: Development, Characterization, And Modeling, Yongjin Kim

Doctoral Dissertations

Recent advances in the field of biomedical and life-sciences are increasingly demanding more life-like actuation with higher degrees of freedom in motion at small scales. Many researchers have developed various solutions to satisfy these emerging requirements. In many cases, new solutions are made possible with the development of novel polymeric actuators. Advances in polymeric actuation not only addressed problems concerning low degree of freedom in motion, large system size, and bio-incompatibility associated with conventional actuators, but also led to the discovery of novel applications, which were previously unattainable with conventional engineered systems. This dissertation focuses on developing novel actuation mechanisms …

Capacitive Spectroscopy Of Defects In Semiconductors, Doped By Atoms Of Gadolinium, Shoakhriyor B. Norkulov, Khodjakbar S. Daliev, Makhmud Sh. Dehkanov, Uktam K. Erugliev

Euroasian Journal of Semiconductors Science and Engineering

The processes of formation of defects in silicon, doped by gadolinium are investigated by the method of DLTS. It is shown that in diffusion the introduction of Gd in the Si leads to the formation of deep levels with ionization energies Ec–0.23 eV, Ec–0.35 eV, Ec–0.41 eV and Ec–0.54 eV and a capture cross section of electrons n: 410-17cm-2, 210-15 cm2, 1.110-16 cm2 and 1.510-15 cm2, respectively, and in samples p-Si found only one level with Ev+0.32 eV.

Calculation And Tabulation Of Efficiencies For Tungsten Foil Positron Moderators, R. Alsulami, M. Albarqi, S. Jaradat, Shoaib Usman, Joseph T. Graham

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

Monte Carlo radiation transport simulations were used to calculate the positron stopping profiles in tungsten positron moderator foils. Stopping profiles were numerically integrated with efficiency kernels derived from Green's function solutions of the 3D diffusion equation to determine the moderation efficiency in both the backscattering and transmission geometries. Stopping profiles and efficiencies were calculated for positron energies from 10 keV to 10 MeV and incident angles from 0° to 75°. The resulting efficiencies agreed with other calculated and measured values in the literature, especially when similar values of the positron diffusion length and surface emission branching ratio were used. Large …

Ipv6 Diffusion Milestones: Assessing The Quantity And Quality Of Adoption, John Pickard, Mark Angolia, Dale Drummond

Journal of International Technology and Information Management

There are currently two versions of Internet Protocol (IP) in use today, IP version 4 (IPv4) and IP version 6 (IPv6). The original version, IPv4, was standardized in the early 1980s as part of the Defense Advanced Research Project Agency Internet program and became the official Internet protocol in 1983 (Kleinrock, 2010). IPv6 was standardized in 1995 as its successor to provide enhanced capabilities and address IPv4 technological limitations, most notable of which was the anticipated exhaustion of address space (Deering & Hinden, 1995). While the two protocols have some functional similarities, they are distinct and not backward compatible; IPv4-only …

Analytical Models For 3-D Diffusion Of Ions From Salt-Contaminated Aggregates, Robert J. Thomas, Andrew D. Sorensen, Marc Maguire

Civil and Environmental Engineering Faculty Publications

This article presents an analytical investigation of the mobility of salts from contaminated aggregates in concrete. Salt-contaminated aggregates may have varied effects on the mechanical properties and durability of concrete. These depend primarily on the mobility of salts within the concrete matrix. Existing diffusion-based models for the mobility of salts in concrete focus on their intrusion from external sources (e.g., chloride penetration from deicing salts and brines). Such problems are well described by the closed-form solution of Fick’s law for diffusion in one dimension from a continuous source. Salt-contaminated aggregates represent a case of diffusion from a finite internal source …

Design Of A Carburizing Treatment Of Steel Base Gear In The Materials Science Course, Jiliang Li, Jin Xu, Nuri Zeytinoglu, Jinyuan Zhai

ASEE IL-IN Section Conference

Diffusion PDE Application to Carburizing Treatment of Steel Base Gear

An introductory materials-science course is required in the mechanical engineering curriculum of many universities. This article describes an example effort to incorporate programming, diffusion transfer, heat treatment process and mechanical-property determination as an integral part of the materials-science course instruction. This effort was undertaken in order to give students additional experience in Fick’s 1^st and 2^nd laws and in-depth understanding of physics and mathematics involved in diffusion analysis. We chose to focus on Fick’s second law because its applications are not restricted to the materials-science field [1]. As …

Synthesis And Molecular Transport Studies In Zeolites And Nanoporous Membranes, Vivek Vattipalli

Doctoral Dissertations

The advent of nanoporous materials such as zeolites and nanoporous membranes has provided cost-effective solutions to some of the most pressing problems of the 20^th century such as the conversion of crude oil into fuels and valuable chemicals. Hierarchical zeolites and mesoporous inorganic membranes are showing great promise in addressing new problems such as the conversion of biomass into value-added chemicals and development of energy-efficient separation processes. The synthesis and fundamental aspects of molecular transport in these new materials with hierarchical porosities need to be better understood in order to rationally develop them for these desired applications. Pore narrowing …

Analysis Of Diffusion Properties Of Methane In Low Rank Coal, Meng Zhaoping, Zhang Guiyuan, Li Guoqing, Liu Jinrong

Coal Geology & Exploration

Diffusion properties of methane in coal is an important reservoir parameter affecting CBM production. Using the lignite samples from the Xiaolongtan Formation of the Miocene Neogene in southeastern Yunnan Province, the isothermal adsorption experiments of methane in low rank coal were carried out. Based on the relationship between adsorption amount and time obtained from isothermal adsorption experiment, the diffusion coefficient of methane in coal was calculated by using an unipore model of unsteady gas diffusion. The diffusion law of methane in coal and its control mechanism were revealed. The results show that gas diffusion law in coal obeys Langmuir equation; …

Effect Of Diffusion Distance On Evolution Of Kirkendall Pores In Titanium-Coated Nickel Wires, Aaron R. Yosta, Dinc Erdeniz, Ashley E. Paz Y Puente, David C. Dunanda

Mechanical Engineering Faculty Research and Publications

Microtubes of near-equiatomic nickel-titanium (NiTi) alloys can be created via the Kirkendall effect during NiTi interdiffusion, when nickel wires are surface-coated with titanium via pack cementation and subsequently homogenized. This study explores the effect of diffusion distance upon Kirkendall microtube formation in NiTi by considering a range of Ni wire diameters. For Ni wire diameters of 25, 50 and 100 μm, titanized at 925 °C for 0.5, 2, and 8 h to achieve average NiTi composition, partial interdiffusion occurs concurrently with Ti surface deposition, resulting in concentric shells of NiTi₂, NiTi and Ni₃Ti around a Ni …

Utilization Of Scale In Keypoint Detection And Feature Description, Andrew P. Rhodes

Graduate Theses, Dissertations, and Problem Reports

Ubiquitous availability of inexpensive three dimensional (3D) sensors has led to an abundance of keypoint detection and feature description techniques for point-clouds. While some recent methods utilize color along with geometric information, most only implicitly discuss -- if not completely disregard -- the information provided by scale. Scale is an inherent characteristic of any keypoint or feature that describes its physical size or region of support.

Exploiting information provided by scale facilitates the processes of keypoint detection and feature description. A 3D scale-space, extended from robust and popular 2D methods, is constructed to diffuse a signal on triangulated meshes. Methods …

Development And Characterization Of Nanostructured Steels And High Entropy Alloys For Nuclear Applications, Andrew Kalevi Hoffman

Doctoral Dissertations

"Nuclear reactor materials are subjected to a harsh environment including high temperatures and radiation fluences. In order to extend the lifetime of current light water reactors (LWRs) and realize the development of advanced Gen IV nuclear reactors new materials must be developed which can withstand such an environment. This thesis involves two approaches to solving this materials problem: advanced manufacturing of current commercial alloys using severe plastic deformation (SPD) and the development of new advanced high entropy alloys (HEAs).

Because SPD is effective at achieving grain refinement, this technique was used to obtain material having a high volume fraction of …

Spatiotemporal Modeling And Model Restructuration Approaches In Studies Of Intracellular Signalling Pathways, Md Shahinuzzaman

Doctoral Dissertations

"The main focus of the research is to understand the complex phenomena of cell transduction pathways and cell biology in a single cell. Mathematical modeling and experimental evaluation are widely used approaches for this kind of research. Firstly, A multiscale framework for protein-protein interaction has been established using Brownian dynamics algorithm. Sit specific feature, steric collision, diffusion, co-localization and complex formation with time and space has been included in this spatial modeling framework. By implementation of the time adaptive feature in this framework, the computation time reduces in an order of magnitude compared with traditional modeling framework. This multiscale Brownian …