Engineering Commons^™

Thermodynamic Modeling, Energy Equipartition, And Nonconservation Of Entropy For Discrete-Time Dynamical Systems, Wassim H. Haddad, Qing Hui, Sergey G. Nersesov, Vijaysekhar Chellaboina

Department of Electrical and Computer Engineering: Faculty Publications

We develop thermodynamic models for discrete-time large-scale dynamical systems. Specifically, using compartmental dynamical system theory, we develop energy flowmodels possessing energy conservation, energy equipartition, temperature equipartition, and entropy nonconservation principles for discrete-time, large-scale dynamical systems. Furthermore, we introduce a new and dual notion to entropy; namely, ectropy, as a measure of the tendency of a dynamical system to do useful work and grow more organized, and show that conservation of energy in an isolated thermodynamic system necessarily leads to nonconservation of ectropy and entropy. In addition, using the system ectropy as a Lyapunov function candidate, we show that our discrete-time, …

Compliant Mechanisms To Perform Bearing And Spring Function In High Precision Applications, Jesse R. Cannon

Theses and Dissertations

An increasing number of mechanical systems are being designed on the micro and meso scales. Assembly and maintenance become increasingly difficult as the size of mechanisms decrease, and the minimum size of traditional elements such as bearings and springs is limited. The backlash of bearings also limits their usefulness in applications where high precision and repeatability are needed. At small scales and for high precision applications, alternative, non-traditional elements are needed.

The objective of this thesis is to develop reliable and scalable compliant components to replace bearings and helical springs. Components replacing springs must be able to produce specified torque/motion …

Bicistronic And Fused Monocistronic Transcripts Are Derived From Adjacent Loci In The Arabidopsis Genome, Jyothi Thimmapuram, Hui Duan, Lei Liu, Mary A. Schuler

Cyber Center Publications

Comparisons of full-length cDNAs and genomic DNAs available for Arabidopsis thaliana described here indicate that some adjacent loci are transcribed into extremely long RNAs spanning two annotated genes. Once expressed, some of these transcripts are post-transcriptionally spliced within their coding and intergenic sequences to generate bicistronic transcripts containing two complete open reading frames. Others are spliced to generate monocistronic transcripts coding for fusion proteins with sequences derived from both loci. RT-PCR of several P450 transcripts in this collection indicates that these extended transcripts exist side by side with shorter monocistronic transcripts derived from the individual loci in each pair. The …

Real Space Projects For University Student Education, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Real Space Projects for University Student Education" from November 17, 2004.

Additive-Assisted Cerium-Based Electrolytic Coating Process For Corrosion Protection Of Aluminum Alloys, James O. Stoffer, Thomas J. O'Keefe, Eric L. Morris, Scott Hayes, Paul Yu, Alex Williams, Xuan Lin

Chemistry Faculty Research & Creative Works

The corrosion resistance of an aluminum or aluminum alloy component is enhanced by immersing an aluminum alloy to act as a cathode and an oxygen-evolving anode in an electrolyte comprising water, cerium ions, and an additive selected from among animal gelatin, derivatives of animal gelatin, and amino acids, then passing an electrical current through the electrolyte to deposit a cerium-based coating onto the aluminum-based component.

The Impossible Dose - How Can Something Simple Be So Complex? , Lars Hode

Light Activated Tissue Regeneration and Therapy

No abstract provided.

Interfacial Stability Of Electrodeposition Of Cuprous Oxide Thin Films, Partho Neogi

Chemical and Biochemical Engineering Faculty Research & Creative Works

Experiments on deposition of Cu₂O films from basic cupper sulfate solution show that copper also deposits. At low, but basic values of pH only copper deposits and at high pH only cuprous oxide deposits. In the intermediate range where both compete the system shows oscillations at "constant current." Linear stability analysis has been conducted for such an electrochemical cell to show that oscillations can take place in the parameter space identified in the experiments. The results are keeping with most of the experimental observations, which are many, but not with all. The physical mechanisms behind the oscillations are …

Simulation Of Gate Lag And Current Collapse In Gallium Nitride Field-Effect Transistors, N. Braga, R. Mickevicius, R. Gaska, M. S. Shur, M. Asif Khan, Grigory Simin

Faculty Publications

Results of two-dimensional numerical simulations of gate lag and current collapse in GaN heterostructurefield-effect transistors are presented. Simulation results clearly show that current collapse takes place only if an enhanced trapping occurs under the gate edges. Hot electrons play an instrumental role in the collapse mechanism. The simulation results also link the current collapse with electrons spreading into the buffer layer and confirm that a better electron localization (as in a double heterostructurefield-effect transistor) can dramatically reduce current collapse.

Lead-Free Solder Joint Reliability – State Of The Art And Perspectives, Jianbiao Pan, Jyhwen Wang, David M. Shaddock

Industrial and Manufacturing Engineering

There is an increasing demand in replacing tin-lead (Sn/Pb) solders with lead-free solders in the electronics industry due to health and environmental concern. The European Union recently passed a law to ban the use of lead in electronic products. The ban will go into effect in July of 2006. The Japanese electronics industry has worked to eliminate lead from consumer electronic products for several years. Although currently there are no specific regulations banning lead in electronics devices in the United States, many companies and consortiums are working on lead-free solder initiatives including Intel, Motorola, Agilent Technologies, General Electric, Boeing, NEMI …

Annealing And Oxidation Of Silicon Oxide Films Prepared By Plasma-Enhanced Chemical Vapor Deposition, X. Y. Chen, Yongfeng Lu, L. J. Tang, Y. H. Wu, B. J. Cho, J. R. Dong, W. D. Song

Department of Electrical and Computer Engineering: Faculty Publications

We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiO_x, 0,x,2) films by high-vacuum annealing and dry oxidation. The SiO_x films were deposited by plasma-enhanced chemical vapor deposition at different nitrous–oxide/silane flow ratios. The physical and optical properties of the SiO_x films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000 °C, the intermediate Si continuum in XPS spectra (referring to the …

Coordination Variables And Consensus Building In Multiple Vehicle Systems, Tim Mclain

Faculty Publications

Much of the research focus in the cooperative control community has been on formation control problems. This focus may be due to the fact that the group control problem can be reduced to well-established single-agent control problems by employing a leader-follower type control strategy. For example, single-agent path planning and trajectory generation techniques can be employed for the leader, and conventional trajectory tracking strategies can be employed for the followers. Indeed, formation control problems are much like linear systems theory: we search where the light is the brightest. It can be argued that formation control problems are the simplest type …

Environmental Effects On Corrosion Properties Of Alloy 22, K. S. Raja, L. G. Mcmillion, Shantanu A. Namjoshi, Paige Russel, Raymond E. Keeler, Amy J. Smiecinski

Publications (YM)

During the regulatory life of the Yucca Mountain High Level Nuclear Waste (HLNW) repository the primary engineered barrier that is to prevent release of radioactive material into the environment is proposed to be a Corrosion-Resistant Material (CRM) outer shell covering the Waste Package (WP) container. The current selection for the CRM is Alloy 22 (UNS N06022), a Ni-Cr-Mo-W-Fe alloy. Alloy 22 forms a defective chromic oxide passive film which results in excellent corrosion resistance; the presence of molybdenum in Alloy 22 offers corrosion resistance in reducing environments as well as oxidizing environments.

Elastomer Reclaiming Composition And Method, Michael W. Rouse, Victor M. Deeb, Morgan L. White, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The present invention relates to elastomeric compositions and methods including compositions and methods involving the use of aromatic alcohols. The present invention further relates to elastomeric compositions that can include ground reclaimed elastomeric particles. Compositions of the present invention are usable in numerous elastomeric applications including interior and exterior vehicle parts, roofing, asphalt, and any other applications that employ an elastomer as an ingredient thereof, particularly those utilizing rubber or a similar elastomer.

The present invention further is directed to asphalt compositions and their methods of manufacture and use.

Stable Zeolite/Cellulose Composite Materials And Method Of Preparation, Gustavo F. Larsen

Department of Chemical and Biomolecular Engineering: Patents

Stable cellulosic fiber material for use in forming zeolite/cellulose composites is prepared by suspending loose cellulose fibers in an aqueous solution of sodium hydroxide, potassium hydroxide or sodium silicate, stirring the resulting suspension until it reaches a macroscopically homogenous appearance, heating the resulting mixture at a temperature of 323-423 K until only dry solids remain, contacting the resulting mixture with excess distilled water to remove physically adsorbed or trapped sodium hydroxide, potassium hydroxide or sodium silicate from the fibers, and heating the resulting fiber material at 323-423 K to dry the fiber material. Stable zeolite/cellulose composite material characterized in that …

Real-Time Registration And Display Of Confocal Microscope Imagery For Multiple-Band Analysis, Scott E. Budge, A.M. Mayampurath, J.C. Solinsky

Electrical and Computer Engineering Faculty Publications

Multiple images acquired in real-time from a confocal microscope in different illumination wavebands are used to construct a three-dimensional understanding of living cell signal propagation. Registration, fusion, and display of these images are performed in real-time using field programmable gate array (FPGA) technology to allow the biological scientist to observe time critical signaling processes as they occur. The registration and display system operates at a rate of up to 15 frames/s, and performs dark offset correction and noise reduction, followed by non-linear correction for lens warp and focal plane tilt, and finally correction for spatial mismatch between the different wavebands. …

Disorder-Induced Depression Of The Curie Temperature In Mechanically Milled Gdal2, Marco Morales Torres, D. S. Williams, Paul M. Shand, C. Stark, Thomas M. Pekarek, Lanping Yue, Valeri G. Petkov, Diandra Leslie-Pelecky

Materials Research Science and Engineering Center: Faculty Publications

The effect of disorder on the ferromagnetic transition is investigated in mechanically milled GdAl₂. GdAl₂is a ferromagnet when crystalline and a spin glass when amorphous. Mechanical milling progressively disorders the alloy, allowing observation of the change from ferromagnetic to a disordered magnetic state. X-ray diffraction and pair-distribution-function analysis are used to determine the grain size, lattice parameter, and mean-squared atomic displacements. The magnetization as a function of temperature is described by a Gaussian distribution of Curie temperatures. The mean Curie temperature decreases with decreasing lattice parameter, where lattice parameter serves as a measure of defect concentration. …

Developed Pumping Strategies For Mather Afb Tce Plume, Richard C. Peralta, Bassel Timani

Civil and Environmental Engineering Faculty Publications

Accomplishments prior to BCT Meeting/Phone Conference of 14 October 2004 Prior to 14 October 2004, the best pumping strategy USU achieved manually completely contains both PCE and TCE1 (within revised containment zones proposed by USU on that date), at the end of years 2, 3, 4, 5 and 5-year intervals thereafter. This strategy uses two new extraction wells (USUE3 and USUE4). The strategy did not utilize a recently constructed well EW-12B. USU did not previously know about EW-12B and the well package USU received did not indicate a well at its location, cell (3,58,43). On 14 October, USU also learned …

Ultimate Strength Of A Continuous Decking Of Cold-Drawn Low-Ductility High Strength Steel, A. Monayem Akhand, W. H. Wan Badaruzzaman, Kosai A. Sanjery

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Profiled decking of cold-drawn low-ductility high strength steel is a relatively new introduction to composite floor construction. This type of decking shows high sensitivity to distortional as well as local buckling. Prediction of ultimate strength of such decking in continuous configuration is not adequately covered in any of the analytical methods of modern day codes. Instead, due to inadequate guidance, various design codes currently apply additional restrictions on their design and use. The support moment-rotation and ultimate moment of resistance of such decking are the two most important parameters in designing such decking as continuous structure for the construction stage …

Web Crippling Of Cold Formed Steel Multi -Web Deck Sections Subjected To End One-Flange Loading, J. A. Wallace, R. M. Schuster

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Presented in this paper are the results of a study where the web crippling capacity of multi-web deck sections subjected to End One-Flange loading (EOF) was investigated. A total of 148 tests were completed. New coefficients were established using the data from this study and any appropriate data from previous work. New resistance factors and factors of safety were also established. Also investigated in this study was the web crippling capacity of partially fastened deck sections and re-entrant deck type sections subjected to EOF loading. Seventy-seven (77) partially fastened multi-web decks and 36 re-entrant decks were tested in this study. …

Behavior Of Complex Hat Shapes Used As Truss Chord Members, Nuthaporn Nuttayasakul, W. Samuel Easterling

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Cold-formed steel roof truss systems that use complex hat shape members for both top and bottom chord elements are a growing trend in the North America steel framing industry. When designing cold-formed steel sections, a structural engineer typically tries to improve the local buckling behavior of the coldformed steel elements. The complex hat shape has proven to limit the negative influence of local buckling. However, a distortional buckling mode can be the control mode of failure in the design for the chord member with an intermediate un-braced length. The chord member may be subjected to both bending and compressive load …

Channel Section Beams Under Static And Impact Loading, J. Rhodes, M. Macdonald

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The elasto-plastic behaviour of plain channel section beams under central point loading is investigated under static and impact loading conditions. Two different loading set-ups are considered, the first in which the load is applied to cause compression at the flange free edges and the second in which the load is applied to cause tension at the flange free edges. For each of these load set-ups static loading tests, single impact loading tests and multiple impact loading tests are carried out on a total of 86 channel beams. The energy absorption behaviour of the beams tested is examined and the static …

Cold-Formed Steel Examples To The Theory And Finite Element Implementation Of Plasticity, Herm Hofmeyer

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper presents two examples to the theory and finite element implementation of plasticity. The first example is on the cross-sectional behavior of trapezoidal sheeting subjected to a concentrated load. It is shown that the number of elements (and thus the number of integration points) along the comer radius are important for the correct modeling of this static problem. The second example is on the failure of first-generation sheeting subjected to a concentrated load and a bending moment. This problem, especially for large span lengths, can be solved only with explicit dynamic simulations. These are, for our research field, for …

Shear Stiffness Of Pallet Rack Upright Frames, S. Sambasiva Rao, R. G. Beale, M. H. R. Godley

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

PaIIet racks, often fabricated using cold-formed steel, are used for the storage of goods. Uprights of these racks are braced in the cross-aisle direction forming a frame, which behaves like a built-up column. Evaluation of the shear stiffness of this frame is needed to determine the buckling load. Currently two approaches prevail in the rack industry to determine the shear stiffness. The RMI code uses a theoretical formula and the FEM code requires testing. There is a considerable difference in the stiffness values determined by two approaches. The present paper describes experimental and numerical studies conducted at Oxford Brookes University …

Tests Of Storage Rack Channel Columns With Rear Flanges, Nabil Abdel-Rahman, Ashraf Fadel, Mohamed Ei-Sadaawy, Sherif Mourad

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

An experimental study was performed to investigate the ultimate strength and modes of failure of axially loaded channel rack columns with rear flanges. A total of 16 column specimens fabricated by press-brake forming method were tested up to failure. The material properties of the column specimens were determined using standard tensile coupon tests. The deformation and stress behavior of the tested columns were monitored using displacement transducers and strain gauges. The effects of column slenderness ratio, thickness, perforation, and end conditions on the column ultimate strength and mode of failure were studied. The test failure loads were compared to the …

Initial Geometrical Imperfections In Three-Storey Modular Steel Scaffolds, W. K. Yu, K. F. Chung, S. L. Chan

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Modular steel scaffolds are commonly used as supporting scaffolds in building construction. They are highly susceptible to global and local instability, and traditionally, the load carrying capacities of these scaffolds are obtained from limited full-scale tests with little rational design. Structural failure of these scaffolds occurs from time to time due to inadequate design, poor installation and over-loads on sites. Initial geometrical imperfections are considered to be very important to the structural behaviour of multi-storey modular steel scaffolds. This paper presents an extensive numerical investigation on three different approaches in analyzing and designing multi-story modular steel scaffolds, namely, a) Notional …

Experimental Investigation Of Distortional Buckling Of Cold-Formed Stainless Steel Sections, Maura Leece, Kim J. R. Rasmussen

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper describes the experimental investigation of the distortional buckling of thin-walled stainless steel sections in compression. Austenitic 304, ferritic 430 stainless steel and ferritic-like 3Crl2 chromium weldable steel sheets were brake-pressed into simple-lipped channels and simple-lipped channels with intermediate stiffeners. A comprehensive procedure to determine the mechanical properties of stainless steel material is described. A total of 19 distortional tests failed at stresses greater than the proportionality stress, and hence were influenced by material non-linearity. Data required to assess current design guidelines in place for distortional buckling of stainless steel compression members are provided herein.

Introduction To The Theory And Finite Element Implementation Of (Steel) Plasticity, Herm Hofmeyer

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper tries to enlighten the subject of (numerical) plasticity by presenting fundamental theory and some very practical examples. For a two-dimensional plain stress state, a Hubert-Henky yield criterion is derived. The flow rule is discussed, including an explanatory numerical example. The yield criteria and flow rule are theoretically applied in a four node finite element. This element is used to show some of the conditions and limitations of a plastic calculation in the finite element method. Finally, a real finite element calculation is made for illustrating the theory derived.

Design Of Cold-Formed Stainless Steel Sections With Single Web Subjected To Web Crippling, Feng Zhou, Ben Young

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

An experimental investigation of cold-formed stainless steel hollow sections subjected to web crippling is presented in this paper. Tests were conducted on square and rectangular hollow sections of austenitic stainless steel type 304. Tensile and compression coupon tests were performed to obtain the longitudinal tension and transverse compression material properties. The web crippling tests were conducted under two loading conditions for End-Two-Flange (ETF) and Interior-Two-Flange (ITF) specified in the current American Specification and Australian/New Zealand Standard for cold-formed stainless steel structures. The test strengths obtained from this study and the test strengths of stainless steel lipped channel sections under End-One-Flange …

Design Of Stainless Steel Sections Against Distortional Buckling, Maura Leece, Kim J. R. Rasmussen

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Current cold-formed stainless steel design codes for distortional buckling, including the Australian/New Zealand Standard AS/NZS 4673 (2001) and the North American ASCE (2002), have been based on cold-formed carbon steel codes without the support or corroboration of experimental evidence. As such, an experimental program on the distortional buckling of axially compressed, cold-formed stainless steel simple lipped channels and lipped channels with intermediate stiffeners was conducted. Results show that the effect of stainless steel material non-linearity is partially negated by the strength-enhanced corners, and this becomes evident in the design evaluation. Both the effective width and the "direct strength" (ASINZS 4600 …

Material Properties Of Cold-Formed High Strength Stainless Steel Tubular Sections, Ben Young, Wing-Man Lui

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper presents the behaviour of cold-formed high strength stainless steel sections. The test specimens were cold-rolled from flat strips of duplex and high strength austenitic stainless steel. The material properties of high strength stainless steel square and rectangular hollow sections were determined. Tensile coupons at different locations in cross-section were tested. Hence, the distributions of 0.2% proof stress and tensile strength measured in the cross-section of cold-formed high strength stainless steel sections were plotted. The material properties of the complete cross-section in the cold-worked state were also obtained from stub column tests. Detailed measurements of initial local geometric imperfections …