Engineering Commons^™

Production Of Bio-Hydrogen By Mesophilic Anaerobic Fermentation In An Acid-Phase Sequencing Batch Reactor, D. Y. Cheong, C. L. Hansen, David King Stevens

Civil and Environmental Engineering Faculty Publications

The pH and hydraulic retention time (HRT) of an anaerobic sequencing batch reactor (ASBR) were varied to optimize the conversion of carbohydrate-rich synthetic wastewater into bio-hydrogen. A full factorial design using evolutionary operation (EVOP) was used to determine the effect of the factors and to find the optimum condition of each factor required for high hydrogen production rate. Experimental results from 20 runs indicate that a maximum hydrogen production rate of 4,460-5,540 mL/L/day under the volumetric organic loading rate (VOLR) of 75 g-COD/L/day obtained at an observed design point of HRT = 8 h and pH = 5.7. The hydrogen …

Associating Characterization Bentonite-Based Buffer/Backfill Materials By Distribution Ratio And Plastic Index (Pi), Yi-Lin Jan, Shih-Chin Tsai, Chun-Nan Hsu

Journal of Marine Science and Technology–Taiwan

Choosing buffer materials with the required engineering and sorption characteristics for radwaste disposal is very important. This work investigates the relationships between engineering characteristics (plastic index; PI) and sorption properties (distribution ratio; Rd) for two mixed buffer materials that are composed of bentonite/quartz sand and bentonite/laterite, to provide an overall functional evaluation of buffer materials. Se is the nuclide of interest, and both synthetic groundwater (GW) and seawater (SW) were employed in batch sorption experiments. Deionized water (DIW) was used in engineering property tests. SW and GW were also used to evaluate the effects on PI. The results indicate that …

Hybrid Recursive Particle Swarm Optimization Learning Algorithm In The Design Of Radial Basis Function Networks, Ching-Yi Chen, Hsuan-Ming Feng, Fun Ye

Journal of Marine Science and Technology–Taiwan

In this paper, an innovative hybrid recursive particle swarm optimization (HRPSO) learning algorithm with normalized fuzzy cmean (NFCM) clustering, particle swarm optimization (PSO) and recursive least-squares (RLS) is proposed to generate radial basis function networks (RBFNs) modeling system with small numbers of descriptive radial basis functions (RBFs) for fast approximating two complex and nonlinear functions. Simulation results demonstrate that the generated NFCM-based learning schemes approach the desired modeling systems within the smaller population sizes.

Optimal Allocation Of Heat Transfer Area For A Refrigeration Plant, Tong-Bou Chang

Journal of Marine Science and Technology–Taiwan

For an internally reversible refrigerant plant, Bejan proposed an optimal way of dividing the area ratio of heat transfer for the hot end and cold end heat exchangers. In the present study, an optimal design of a refrigeration plant has been developed by considering both the external and internal irreversibilities. The internal irreversibility is modeled by a heat bypass which represents the actual internal heat leak and the friction losses due to mechanism movement. A more general formulation than previous study of optimal area-ratio is obtained in this study. For the case of no internal irreversibility, this formulation is exactly …

High Gain Low Power Operational Amplifier Design And Compensation Techniques, Lisha Li

Theses and Dissertations

This dissertation discusses and compares the existing compensation methods for operational amplifiers. It explores a method to stabilize the op amps without sacrificing bandwidth to the same degree that commonly used methods do. A creative design methodology combining intuition, mathematical analysis, and mixed level simulation is explored for the new compensation scheme. The mixed level approach, associating system level simulation for most circuits along with device level simulation for some critical analog circuit paths, is presented to verify the behavior of new design concepts in an effective way. This approach also provides sufficient accuracy to predict the circuit performance realistically. …

Tessellated Surface Machining, Jiewu Lu

Theses and Dissertations

Sculptured surface machining (SSM) is the end milling of sculptured surfaces with multi-axis machine tools. SSM consists of the tessellated model machining (TMM) and the parametric model machining (PMM). The former is gaining more and more attention over the past decade because it offers many advantages over the latter. New methods for various machining stages of TMM are proposed in this dissertation. First, in the 5-axis finish machining stage, a 3-dimension Configuration-space (3D C-space) machining method is presented. Next, in clean-up machining stage, an effective and creative approach is introduced. Finally, a complete TMM system is developed. The TMM system …

Quarter-Wave Layers With 50% Reflectance For Obliquely Incident Unpolarized Light, R. M.A. Azzam, F. F. Sudradjat

Electrical Engineering Faculty Publications

The conditions under which light interference in a transparent quarter-wave layer of refractive index n1 on a transparent substrate of refractive index n2 leads to 50% reflectance for incident unpolarized light at an angle φ are determined. Two distinct solution branches are obtained that correspond to light reflection above and below the polarizing angle, φp , of zero reflection for p polarization. The real p and s amplitude reflection coefficients have the same (negative) sign for the solution branch φ>φp and have opposite signs for the solution branch φ<φp . Operation at φ<φp is the basis of a 50%–50% beam splitter that divides an incident totally polarized light beam (with p and s components of equal intensity) into reflected and …

Wrinkling Of A Charged Elastic Film On A Viscous Layer, Xiang-Fa Wu, Yuris A. Dzenis, Kyle W. Strabala

Department of Engineering Mechanics: Faculty Publications

A thin metallic film deposited on a compliant polymeric substrate begins to wrinkle under compression induced in curing process and afterwards cooling of the system. The wrinkle mode depends upon the thin film elasticity, thickness, compressive strain, as well as mechanical properties of the compliant substrate. This paper presents a simple model to study the modulation of the wrinkle mode of thin metallic films bonded on viscous layers in external electric field. During the procedure, linear perturbation analysis was performed for determining the characteristic relation that governs the evolution of the plane-strain wrinkle of the thin films under varying conditions, …

Effect Of Oxygen Vacancies On Spin-Dependent Tunneling In Fe/Mgo/Fe, Julian P. Velev, Kirill D. Belashchenko, Sitaram S. Jaswal, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

First-principles calculations based on density functional theory are used to elucidate the effect of O vacancies, forming F centers, on spin-dependent tunneling in Fe/MgO/Fe(001) magnetic tunnel junctions. O vacancies produce occupied localized s states and unoccupied resonant p states, which is consistent with available experimental data. The authors find that O vacancies affect the conductance by nonresonant scattering of tunneling electrons causing a substantial reduction of tunneling magnetoresistance (TMR). Improving the quality of the MgO barrier to reduce O vacancy concentration would improve TMR in these and similar junctions.

Identification And Characterization Of Calcium And Manganese Transporting Atpase (Pmr1) Gene Of Pichia Pastoris, Michael P. Dux, Mehmet Inan

Papers in Biotechnology

A gene homologous to Saccharomyces cerevisiae PMR1 has been cloned in the methylotrophic yeast Pichia pastoris.The entire P. pastoris PMR1 gene (PpPMR1 ) codes a protein of 924 amino acids. Sequence analysis of the PpPMR1 cDNA and the genomic DNA revealed that there is no intron in the coding region. The putative gene product contains all of the conserved regions observed in P-type ATPases and exhibits 66.2%, 60.3% and 50.6% identity to Pichia angusta (Hansenula polymorpha), Saccharomyces cerevisiae PMR1 and human ATP2C1 gene products, respectively. A pmr1 null mutant strain of P. pastoris exhibited growth defects in media with the …

Optical Emission Study Of Nonthermal Plasma Confirms Reaction Mechanisms Involving Neutral Rather Than Charged Species, Gui-Bing Zhao, Morris D. Argyle, Maciej Radosz

Faculty Publications

Charge transfer reactions are commonly used to explain NO_x conversion in nonthermal plasma. An analysis of optical emission spectra induced by pulsed corona discharge in NO_x-containing argon suggests that, in fact, the contribution of charge transfer reactions to NO_x conversion in nonthermal plasma is negligible. During electrical discharge in such gas mixtures, NO (B)⁠, an electronic excited state of NO formed due to the dissociative recombination reactions of NO_x⁺ and N₂O⁺ and the optical emission of NO (B) could be a proof that cations are responsible for NO_x conversion. However, …

Performance Evaluation For Hybrid Architectures, Praveen Krishnamurthy

All Computer Science and Engineering Research

In this dissertation we discuss methologies for estimating the performance of applications on hybrid architectures, systems that include various types of computing resources (e.g. traditional general-purpose processors, chip multiprocessors, reconfigurable hardware). A common use of hybrid architectures will be to deploy coarse pipeline stages of application on "suitable" compute units with communication path for transferring data. The first problem we focus on relates to the sizing the data queues between the different processing elements of an hybrid system. Much of the discussion centers on our analytical models that can be used to derive performance metrics of interest such as, throughput …

Ccfss Technical Bulletin Spring 2007, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.

Acuta Enews February 2007, Vol. 36, No. 2

ACUTA Newsletters

In This Issue

Nominate Now for ACUTA Board of Directors 2007-08

From the President.............. Carmine Piscopo, RCDD, Providence College

Nominations Still Open for Institutional Excellence Awards............. Pat Todus, Northwestern Univ.

Tech Talk: Visibility for Your School and ACUTA............. Kevin Tanzillo, Dux PR

DC Update............ Jeanne Jansenius, Sewanee, The University of the South

Overheard on the Listserv: Pricing VoIP

FYI: Useful Information from the Campus........... Student Monitor

Web Tip: What's New on ACUTA Website...... Aaron Fuehrer, ACUTA Information Technology Manager

Board Report.......... Riny Ledgerwood, San Diego State Univ., ACUTA Sec./Treasurer

Info Links............ Randy Hayes, Univ. of Northern Iowa

Remembering Harry Kyle …

Russian Peasant Multiplication Algorithm, Rsa Cryptosystem, And A New Explanation Of Half-Orders Of Magnitude, J. Ivan Vargas, Olga Kosheleva

Departmental Technical Reports (CS)

In his papers, J. Hobbs has observed that when people make crude estimates, they usually feel reasonably comfortable choosing between alternatives which differ by a half order of magnitude (HOM). He also provided an explanation for this level of granularity based on the need for the resulting crude estimates to represent both the original data and the result of processing this data. According to this explanation, HOM are optimal -- when we limit ourselves to these first crude estimates.

In many practical situations, we do not stop with the original estimate, we refine it one or more times by using …

Use Of Deterministic Traffic Assignment Algorithms In Stochastic Networks: Analysis Of Equivalent Link Disutility Functions, Ruey L. Cheu, Vladik Kreinovich

Departmental Technical Reports (CS)

At present, in practice, most traffic assignment tasks are performed by using deterministic network (DN) models, which assume that the link travel time is uniquely determined by the link volume and link capacity. In reality, for the same link volume and link capacity, a link may have different travel times. However, the corresponding stochastic network (SN) models are not widely used because they are much more computationally complex than the DN models. In the past research, it was shown that in the important particular case, when the link travel time follows Gamma distribution, the traffic assignment problem for SN can …

Logit Discrete Choice Model: A New Distribution-Free Justification, Ruey L. Cheu, Hung T. Nguyen, Tanja Magoc, Vladik Kreinovich

Departmental Technical Reports (CS)

According to decision making theory, if we know the user's utility Ui=U(si) of all possible alternatives si, then we can uniquely predict the user's preferences. In practice, we often only know approximate values Vi~Ui of the user's utilities. Based on these approximate values, we can only make probabilistic predictions of the user's preferences. It is empirically known that in many real-life situations, the corresponding probabilities are described by a logit model, in which the probability pi of selecting the alternative si is equal to pi=exp(b*Vi)/(exp(b*V1)+...+exp(b*Vn)). There exist many theoretical explanations of this empirical formula, some of these explanations led to …

The Effect Of Oil Swelling On The Fatigue Life Of Elastomers Subjected To Cyclic Bubble Inflation, Niall Murphy, John Hanley, Stephen Jerrams, Ali Hassan

Conference Papers

This paper describes the behaviour of rubber in multi-axial fatigue, with respect to oil resistance. A series of tests were carried out on EPDM specimens subjected to varying degrees of swelling. The control methodology and the loading mechanism employed in the testing of elastomers using dynamic multi-axial bubble inflation are outlined. Swollen specimens were prepared by immersing them in reference mineral oil. Specimens were cycled to failure and the results were analysed. The number of cycles to failure for a given engineering stress amplitude was plotted for both dry (unswollen) and swollen specimens. Fracture surfaces for each set of specimens …

Flexible Irrigation Systems: Concept, Design And Application, John L. Merriam, Stuart W. Styles, Beau J. Freeman

BioResource and Agricultural Engineering

This paper presents the need, value, and concept of flexible irrigation water supply systems that can deliver water with flexibility in frequency, rate, and duration under the control of the farmer at the point of application using a limited rate arranged-demand or other schedule. It introduces the needed terminology including “congestion” — how much reserve time and capacity is required to assure water delivery at the frequency and rate desired. An illustrative design procedure for the necessary pipeline and reservoir capacities is illustrated. The techniques discussed emphasize the conversion of the economical steady supply canal flows to flexible on-farm usage …

Dynamic Feedback Coupling Of Continuous Hydrologic And Socio-Economic Model Components Of The Upper Thames River Basin, Predrag Prodanovic, Slobodan P. Simonovic

Water Resources Research Report

The main contribution of this work consists of formulating a novel simulation framework used in analysis of climate change impact assessment. The model developed consists of a continuous hydrologic component coupled (via feedback) to a socioeconomic component developed using system dynamics. The hydrologic component of the model responds to changes in socio-economic conditions (such as changing economic, demographic and land use patterns), while socio-economic conditions are continually influenced by hydrologic quantities (such as available ground water recharge, flow and precipitation). As the two components are connected via feedback, each dynamically influences, and is influenced by, the other thereby mimicking such …

Rockport Reservoir Final Environmental Assessment And Finding Of No Significant Impact Pro-06-004, Peter Crookston, U.S. Department Of The Interior, Bureau Of Reclamation

All U.S. Government Documents (Utah Regional Depository)

No abstract provided.

Propagation Of Ultrashort Laser Pulses Through Water, Jianchao Li, Dennis R. Alexander, Haifeng Zhang, Ufuk Parali, David Doerr, John Clark Bruce Iii, Hao Wang

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, propagation of ultrashort pulses through a long 3.5 meter water channel was studied. Of particular interest was the attenuation of the beam at various lengths along the variable path length and to find an explanation of why the attenuation deviates from typical Beer Lambert law around 3 meters for ultrashort laser pulse transmission. Laser pulses of 10 fs at 75 MHz, 100 fs at 80 MHz and 300 fs at 1 KHz were employed to investigate the effects of pulse duration, spectrum and repetition rate on the attenuation after propagating through water up to 3 meters. Stretched …

Towards A General Description Of Physical Invariance In Category Theory, John Symons, Julio C. Urenda, Vladik Kreinovich

Departmental Technical Reports (CS)

Invariance is one of the most important notions in applications of mathematics. It is one of the key concepts in modern physics, is a computational tool that helps in solving complex equations, etc. In view of its importance, it is desirable to come up with a definition of invariance which is as general as possible. In this paper, we describe how to formulate a general notion of invariance in categorial terms.

Safety Performance Evaluation Of Minnesota's Temporary Rigid Panel Sign Stand Systems, Karla A. Polivka, James C. Holloway, Ronald K. Faller, John R. Rohde

Nebraska Department of Transportation: Research Reports

No abstract provided.

Ccfss News Spring 2007, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.

Percussive Penetration Of Unconsolidated Granular Media In A Laboratory Setting, Leslie S. Gertsch

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This controlled study examined the feasibility of a simple percussive approach to drilling through unconsolidated regolith deposits on Mars. The experiments showed that the approach is feasible at the low power levels and low confining pressures used, and that the rate of impact is more important to the penetration rate than is the mass of the impactor (hammer). More massive impactors tend to lower energy efficiency, as they do in terrestrial pile-driving. Unexpectedly, penetration plotted against applied energy tends to cluster into parallel linear trends. Within a given cluster, penetration is very sensitive to applied energy, while between clusters, the …

Hyperthermic Effects Of Gold Nanorods On Tumor Cells, Terry B. Huff, Ling Tong, Matthew N. Hansen, Ji-Xin Cheng, Alexander Wei

Other Nanotechnology Publications

Plasmon-resonant gold nanorods, which have large absorption cross sections at near-infrared frequencies, are excellent candidates as multifunctional agents for image-guided therapies based on localized hyperthermia. The controlled modification of the surface chemistry of the nanorods is of critical importance, as issues of cell-specific targeting and nonspecific uptake must be addressed prior to clinical evaluation. Nanorods coated with cetyltrimethylammonium bromide (a cationic surfactant used in nanorod synthesis) are internalized within hours into KB cells by a nonspecific uptake pathway, whereas the careful removal of cetyltrimethylammonium bromide from nanorods functionalized with folate results in their accumulation on the cell surface over the …

Model-Based Estimation Of Muscle Forces Exerted During Movements, Ahmet Erdemir, Scott Mclean, Walter Herzog, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Estimation of individual muscle forces during human movement can provide insight into neural control and tissue loading and can thus contribute to improved diagnosis and management of both neurological and orthopaedic conditions. Direct measurement of muscle forces is generally not feasible in a clinical setting, and non-invasive methods based on musculoskeletal modeling should therefore be considered. The current state of the art in clinical movement analysis is that resultant joint torques can be reliably estimated from motion data and external forces (inverse dynamic analysis). Static optimization methods to transform joint torques into estimates of individual muscle forces using musculoskeletal models, …

Threshold Power Of Canonical Antennas For Inducing Sar At Compliance Limits In The 300-3000 Mhz Frequency Range, Mohammod Ali, Mark G. Douglas, Abu T.M. Sayem, Antonio Faraone, Chung-Kwang Chou

Faculty Publications

A study of the specific absorption rate (SAR) in an exposed body induced by canonical antennas is presented, with the aim of determining an upper bound for the antenna transmit power that demonstrates that a product is inherently compliant with internationally accepted radio frequency (RF) exposure limits. Starting from the fundamental limits in antenna quality factor (Q) and the corresponding bandwidth, several antenna sizes are selected, and their SAR distributions are computed using the method of moments (MoM) and finite-difference time domain (FDTD) method in the frequency range 300-3000 MHz. The threshold powers are then determined, below which the peak …

Design And Evaluation Of An Open Combination Traffic/Bicycle Bridge Railing System, Jason A. Hascall, John R. Rohde, Dean L. Sicking, Karla A. Polivka, Ronald K. Faller, James C. Holloway M.S.C.E., E.I.T.

Nebraska Department of Transportation: Research Reports

No abstract provided.