Engineering Commons^™

The Theory Of Quaternion Orthogonal Designs, Jennifer Seberry, Ken Finlayson, Sarah Spence Adams, Tadeusz Wysocki, Tianbing Xia, Beata Joanna Wysocki

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Over the past several years, there has been a renewed interest in complex orthogonal designs for their application in space–time block coding. Motivated by the success of this application, this paper generalizes the definition of complex orthogonal designs by introducing orthogonal designs over the quaternion domain. This paper builds a theory of these novel quaternion orthogonal designs, offers examples, and provides several construction techniques. These theoretical results, along with the results of preliminary simulations, lay the foundation for developing applications of these designs as orthogonal space–time-polarization block codes.

Why Divide By (N-1) For Sample Standard Deviation?, Paul Savory

Department of Industrial and Management Systems Engineering: Instructional Materials

In statistics, the sample standard deviation is a widely used measure of the variability or dispersion of a data set. The standard deviation of a data set is the square root of its variance. In calculating the sample standard deviation, the divisor is the number of samples in the data set minus one (n-1) rather than n. This often confuses students. This paper offers a quick overview of why the divisor is (n-1) for calculating the sample standard deviation.

Thermodynamically Coupled Transport In Simple Catalytic Reactions, Yaşar Demirel

Yaşar Demirel Publications

Considerable work published on chemical reaction-diffusion systems investigates mainly mathematically coupled nonlinear differential equations. This study presents the modeling of a simple elementary chemical reaction with thermodynamically and mathematically coupled heat and mass transport with external mass and heat transfer resistances. The thermodynamic coupling refers that a flow occurs without or against its primary thermodynamic driving force, which may be a gradient of temperature or chemical potential. The modeling is based on the linear nonequilibrium thermodynamics approach and phenomenological equations by assuming that the system is in the vicinity of global equilibrium. This approach does not need detailed coupling mechanisms. …

Truncated Hyperbolic Mapping For Non-Binary Turbo Coding In Uwb, K. Popovski, Tadeusz Wysocki, B. J. Wysocki

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

The combination of user multiplexing and data encoding within Ultra Wideband systems has been proposed to improve bit error performance. Relative to conventional binary coding, this technique has shown to reduce error rates in scarcely populated systems. Where non-binary turbo coding modulates data to form an integer sequence, a random mapping is generally applied to develop a time hopping sequence. This paper explores the possibility of mapping through the application of truncated hyperbolic congruence codes. Comparative results against a random mapping indicate an improvement in system performance for higher turbo iteration levels in the receiver. Transceiver architecture is based upon …

Combined User Multiplexing And Data Modulation Through Non-Binary Turbo Codes For Uwb, K. Popovski, Tadeusz Wysocki, B. J. Wysocki

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

With significant research being conducted in Ultra Wideband communications to increase error performance, this paper proposes a combination of user multiplexing and data encoding to achieve a BER improvement. Through the use of non-binary turbo coding, data is modulated to form a time hopping code which is applied to a time-reversed UWB system. Comparative results with conventional binary coding are given, showing the possibility for BER improvements in systems with a low number of users. Slight performance degradations for a large number of users exist. The effects of a user applying turbo coding on other users not applying forward error …

Artificial Immune System Based Image Pattern Recognition In Energy Efficient Wireless Multimedia Sensor Networks, Honggang Wang, Dongming Peng, Wei Wang, Hamid Sharif, J. Wegiel, D. Nguyen, R. Bowne, C. Backhaus

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

In Wireless Multimedia Sensor Networks (WMSNs), low cost Complementary Metal Oxide Semiconductor (CMOS) camera sensors may only produce low resolution images due to hardware limitations. However, super-resolution images may be constructed from these low resolution images in a multiple sensor network, improving object pattern recognition success rates. There is a critical image recognition challenge in these reconstructed superresolution images for accuracy, complexity and limited energy resource in wireless sensor networks. Artificial Immune Systems (AIS), in particular those possessing algorithmic efficiency for image pattern differentiation, categorization and recognition, have potential advantages in low-cost automated monitoring and object detection applications. In this …

Throughput Vs. Distance Tradeoffs And Deployment Considerations For A Multi-Hop Ieee 802.16e Railroad Test Bed, Wei Wang, Hamid Sharif, Ting Zhou, Puttipong Mahasukhon

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Throughput vs. distance analysis and coverage requirements are critical issues in planning wireless network deployments. With the recent availability of IEEE 802.16e and its promise of larger coverage areas for high-speed data communication, evaluating it in a real-world environment is very important to us in our ongoing study of standards based wireless technologies for the Federal Railroad Administration (FRA). In this paper, we present results obtained with our IEEE 802.16e module for NS-2, particularly throughput vs. distance performance, and its consideration for designing a real-world multi-hop IEEE 802.16e testbed. Firstly, a quantitative analysis of throughput vs. distance performance is conducted …

Development And Performance Evaluation Of A Flexible, Low Cost Manet, M. Abolhasan, B. Hagelstein, J.C-P. Wang, D.R. Franklin, F Safaei, Tadeusz Wysocki

Department of Electrical and Computer Engineering: Faculty Publications (to 2015)

Performance evaluations of multi-hop ad hoc network routing protocols have been primarily conducted through analytic and simulation-based studies, which frequently fail to accurately predict real-world performance and behaviour. One reason for this is the challenge in developing low cost, representative test beds with the degree of flexibility and mobility required. We have developed a Portable Wireless Ad hoc Node (PWAN) device which establishes multi-hop routes using the OLSR routing protocol. The PWAN’s performance has been investigated using two test bed configurations to evaluate its capacity under conditions of high node density in a short-range, multi-hop environment. Our results illustrate that …

Grammar-Based Distance In Progressive Multiple Sequence Alignment, David Russell, Hasan H. Otu, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

Background: We propose a multiple sequence alignment (MSA) algorithm and compare the alignment-quality and execution-time of the proposed algorithm with that of existing algorithms. The proposed progressive alignment algorithm uses a grammar-based distance metric to determine the order in which biological sequences are to be pairwise aligned. The progressive alignment occurs via pairwise aligning new sequences with an ensemble of the sequences previously aligned.
Results: The performance of the proposed algorithm is validated via comparison to popular progressive multiple alignment approaches, ClustalW and T-Coffee, and to the more recently developed algorithms MAFFT, MUSCLE, Kalign, and PSAlign using the BAliBASE 3.0 …

Reaction Pathway Insights Into The Solvothermal Preparation Of Culn1- XGaXSe2 Nanocrystalline Materials, Christopher L. Exstrom, Scott A. Darveau, Andrea L. Martinez-Skinner, Matt Ingersoll, Jiri Olejnicek, Anatole Mirasano, Adam T. Haussler, James Huguenin-Love, Chad Kamler, Martin Diaz, Natale J. Ianno, Rodney J. Soukup

Department of Electrical and Computer Engineering: Faculty Publications

Reaction pathway investigations of the solvothermal preparation of nanocrystalline Culn_{1- x}Ga_xSe₂ in triethylenetetramine reveal the early formation of a previously unreported Cu_2-xSe(S) intermediate. Over 24 hours, this reacts with In and Se species to form CulnSe₂(s). If Ga is present, the reaction proceeds over an additional 48 hours to form Culn_1-xGa_xSe₂. Adding ammonium halide salts reduces the CulnSe₂ formation time to as little as 30 minutes. It is proposed that in these cases, Cu_2-xSe particle growth is limited via a competitive Cu-halide …

A Theoretical Framework For Quality-Aware Cross-Layer Optimized Wireless Multimedia Communications, Song Ci, Haohong Wang, Dalei Wu

Department of Electrical and Computer Engineering: Faculty Publications

Although cross-layer has been thought as one of themost effective and efficient ways formultimedia communications over wireless networks and a plethora of research has been done in this area, there is still lacking of a rigorous mathematical model to gain indepth understanding of cross-layer design tradeoffs, spanning from application layer to physical layer. As a result, many existing cross-layer designs enhance the performance of certain layers at the price of either introducing side effects to the overall system performance or violating the syntax and semantics of the layered network architecture. Therefore, lacking of a rigorous theoretical study makes existing cross-layer …

Effects Of Wind Field Inhomogeneities On Doppler Beam Swinging Revealed By An Imaging Radar, B.L. Cheong, T.-Y. Yu, Robert D. Palmer, K.-F. Yang, Michael Hoffman, S.J. Frasier, F.J. Lopez-Dekker

Department of Electrical and Computer Engineering: Faculty Publications

In this work, the accuracy of the Doppler beam-swinging (DBS) technique for wind measurements is studied using an imaging radar—the turbulent eddy profiler (TEP) developed by the University of Mas- sachusetts, with data collected in summer 2003. With up to 64 independent receivers, and using coherent radar imaging (CRI), several hundred partially independent beams can be formed simultaneously within the volume defined by the transmit beam. By selecting a subset of these beams, an unprecedented number of DBS configurations with varying zenith angle, azimuth angle, and number of beams can be investigated. The angular distributions of echo power and radial …

Historical Perspective And Contribution Of Us Researchers Into The Field Of Self-Propagating High-Temperature Synthesis (Shs)/Combustion Synthesis (Cs): Personal Reflections, J. W. Mccauley, J. A. Puszynski

United States Army: Publications

In 1967, Merzhanov, Skhiro, and Borovinskaya published the first comprehensive paper describing self-sustaining character of reactions in a condensed phase, which could be utilized for synthesis of many ceramic and intermetallic materials [1]. In this paper, the authors demonstrated the principle of the so called “solid flame” using reactions between transition metals and boron, carbon or nitrogen. The world-wide combustion synthesis community considers this comprehensive paper and subsequent integrated experimental and theoretical research effort conducted in the former Soviet Union as the beginning of a new approach and method of synthesizing advanced high temperature materials. The main research was conducted …

Anaerobic Treatment Of Army Ammunition Production Wastewater Containing Perchlorate And Rdx, Emina Atikovic, Makram T. Suidan, Stephen W. Maloney

United States Army: Publications

Perchlorate is an oxidizer that has been routinely used in solid rocket motors by the Department of Defense and National Aeronautics and Space Administration. Royal Demolition Explosive (RDX) is a major component of military high explosives and is used in a wide variety of munitions. Perchlorate bearing wastewater typically results from production of solid rocket motors, while RDX is transferred to Army industrial wastewaters during load, assemble and pack operations for new munitions, and hot water or steam washout for disposal and deactivation of old munitions (commonly referred to as demilitarization, or simply demil).
Biological degradation in Anaerobic Fluidized Bed …

Catfish Consumption As A Contributor To Elevated Pcb Levels In A Non-Hispanic Black Subpopulation, Max Weintraub, Linda S. Birnbaum

United States Environmental Protection Agency: Publications

The human body burden of polychlorinated biphenyls (PCBs) sharply declined after production was banned in the US in 1979. For the 10% of the US population that remains most exposed to PCBs, fish consumption is the primary source. National Health and Nutrition Examination Survey (NHANES) data indicates that the highest remaining PCB levels exist in a non-Hispanic black subpopulation. Our review suggests that catfish consumption may be a significant PCB source for the one million non-Hispanic black anglers who fish for catfish. In comparison to non-Hispanic white anglers, non-Hispanic black anglers consume more catfish, are more likely to eat the …

The History Of The Unl Water Center From 1964, Water Center, School Of Natural Resources

Nebraska Water Center: Administrative Materials

Water is an integral part of Nebraska’s economy and well being in a state that depends on an adequate supply for all uses, including agricultural, municipal, industrial, recreational and wildlife habitat.

Nebraska is fortunate with regard to its water supply, having tremendous groundwater reserves which are estimated to be in excess of two billion acrefeet (an acre-foot being enough water to cover one acre of land with a foot of water, or approximately 325,000 gallons), combined with an estimated annual precipitation of 86 million acre-feet and annual average surface water inflows of 1.7 million acre-feet, give the state adequate supplies …

Effects Of Gamma-Sterilization On The Physico-Chemical Properties Of Natural Sediments, T.L. Bank, Ravi K. Kukkadapu, A.S. Madden, M.A. Ginder-Vogel, M.E. Baldwin, P.M. Jardine

United States Department of Energy: Publications

Batch U(VI) sorption/reduction experiments were completed on sterilized and non-sterilized sediment samples to elucidate biological and geochemical reduction mechanisms. Results from X-ray absorption nearedge structure (XANES) spectroscopy revealed that γ-sterilized sediments were actually better sorbents of U(VI), despite the absence of any measurable biological activity. These results indicate that γ-irradiation induced significant physico-chemical changes in the sediment which is contrary to numerous other studies identifying γ-sterilization as an effective and minimally invasive technique. To identify the extent and method of alteration of the soil as a result of γ-sterilization, untreated soil samples, physically separated size fractions, …

Enhanced Blocking Temperature And Isothermal Control Of Hysteresis Loop Shifts In Co/Nio/[Co/Pt] Heterostructures With Orthogonal Easy Axes, A. Baruth, Shireen Adenwalla

Nebraska Center for Materials and Nanoscience: Faculty Publications

Heterostructures of Co 4 nm/NiO 1.1 nm/[Co 0.4 nm/Pt 0.6 nm] with mutually orthogonal easy axes allow for isothermal tuning of the hysteresis loop shifts along the applied field axis at room temperature, as well as displaying a greatly enhanced blocking temperature. The loop shifts can be varied up to 35 Oe through the application of moderate dc magnetic fields of 3 kOe. The presence of the [Co/Pt] multilayer with perpendicular anisotropy is responsible for a significant enhancement of the blocking temperature. For this thickness of NiO, the blocking temperature is expected to be well below 50 K, in contrast …

A Low-Temperature Specific Heat Study Of Giant Dielectric Constant Materials, C. P. Sun, Jianjun Liu, J.-Y. Lin, Chun-Gang Duan, Wao-Ning Mei, H. D. Yang

Nebraska Center for Materials and Nanoscience: Faculty Publications

A low-temperature specific heat study has been performed on the insulating giant dielectric constant material CaCu₃Ti₄O₁₂ and two related compounds, Bi_2/3Cu₃Ti₄O₁₂ and La_0.5Na_0.5Cu₃Ti₄O₁₂, from 0.6 to 10 K. From analyzing the specific heat data in a very low-temperature range, 0.6–1.5 K, and moderately low-temperature range, 1.5–5 K, in addition to the expected Debye terms, we observed significant contributions originating from the linear and Einstein terms, which we attributed as the manifestation of low-lying elementary excitations due to lattice …

Self-Assembly Of A Micrometers-Long One-Dimensional Network Of Cemented Au Nanoparticles, Vivek C. Maheshwari, Jennifer Kane, Ravi F. Saraf

Ravi Saraf Publications

One-dimensional Au nanoparticles connected by ionic linkers self-assemble into a micrometer-scale network. Reactions between linker ions reinforce the assembly and lead to the formation of a continuous network. This continuous network demonstrates room temperature Coulomb-blockade characteristics that are indicative of electron transport along the 1D pathways.

Computer Simulation Of Radio Frequency Heating Of Model Fruit Immersed In Water, Sohan Birla, Shaojin Wang, Juming Tang

Department of Engineering Mechanics: Faculty Publications

The present study investigated the effect of different factors on temperature distribution within a spherical object in a parallel plate radio frequency (RF) heating system. A finite element-computer simulation program - FEMLAB was used to solve the electromagnetic and Navier-Stoke equations for developing a model to study the effect of dielectric properties of a model fruit and its surrounding medium. The model fruit was prepared from 1% gellan gel for experimental validation of the simulation results. The results showed that spherically-shaped samples surrounded with air between RF electrodes and placed in the proximity of electrodes would not heat uniformly. Immersing …

The Highly Similar Arabidopsis Homologs Of Trithorax Atx1 And Atx2 Encode Proteins With Divergent Biochemical Functions, Abdelaty Saleh, Raul Alvarez-Venegas, Mehtap Yilmaz, Oahn-Le, Guichuan Hou, Monther Sadder, Ayed Al-Abdallat, Yuannan Xia, Guoqinq Lu, Istvan Ladunga, Zoya Avramova

Nebraska Center for Biotechnology: Faculty and Staff Publications

Gene duplication followed by functional specialization is a potent force in the evolution of biological diversity. A comparative study of two highly conserved duplicated genes, ARABIDOPSIS TRITHORAX-LIKE PROTEIN1 (ATX1) and ATX2, revealed features of both partial redundancy and of functional divergence. Although structurally similar, their regulatory sequences have diverged, resulting in distinct temporal and spatial patterns of expression of the ATX1 and ATX2 genes. We found that ATX2 methylates only a limited fraction of nucleosomes and that ATX1 and ATX2 influence the expression of largely nonoverlapping gene sets. Even when coregulating shared targets, ATX1 and ATX2 may employ different …

Nebraska Blueprint – Winter 2007-08

Nebraska Blueprint (Student Publication)

Table of Contents:

Bike Lanes: Making Space for Safety
Engineering: Building a Better Bike
Bridge Safety: A Local Perspective
Alumni Tips: Advice for Undergraduates
Performance: Improving Cyclists
Tech Guru: Internet Browsers br> Student Profile: Daniela Cadore br> Student Profile: Erin Hammons

Nebraska Blueprint - Spring 2008

Nebraska Blueprint (Student Publication)

Table of Contents:

Letter from the Editor
E-Engineering: Environmentalism Tips
Tech Guru: Eye-Fi
E-Engineering by Lt. Col. Jeff Gillen
E-Engineering by Rachel Thorpe
E-Week 2008 - Speaker Jeff Zvolanek
E-Week 2008: Behind the Scenes
E-Week 2008 Responses
E-Week 2008 Awards

Nebraska Blueprint- Winter 2008

Nebraska Blueprint (Student Publication)

Table of Contents:

4 From the Editor

5 The Engineering Library

6 Gasifier and More at Splinter Labs

8 Anechoic Chamber and Scatterometer

10 Surgical Robotics Lab

12 Research Computing Facility and Schorr Center

How Do You Interpret A Confidence Interval?, Paul Savory

Department of Industrial and Management Systems Engineering: Instructional Materials

A confidence interval (CI) is an interval estimate of a population parameter. Instead of estimating the parameter by a single value, a point estimate, an interval likely to cover the parameter is developed. Many student incorrectly interpret the meaning of a confidence interval. This paper offers a quick overview of how to correctly interpret a confidence interval.

Evaluation Of A Virtual Refrigerant Charge Sensor, Woohyun Kim, James E. Braun, Haorong Li

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper presents a thorough evaluation of a method for determining refrigerant charge that employs low-cost, non-invasive measurements (i.e., surface mounted temperature measurements). The method could be used as part of a protocol for verified service providers (VSPs) in AC diagnostic tune-up or refrigerant charge, air flow (RCA) verification programs. Ultimately, the method could be embedded within a portable virtual refrigerant charge gauge for a technician’s use or permanently installed on the AC unit. The accuracy of the virtual refrigerant charge sensor method is evaluated in this paper using laboratory data for a number of different systems and over a …

Polaron And Phonon Properties In Proton Intercalated Amorphous Tungsten Oxide Thin Films, M. Saenger, T. Hoing, Brian W. Robertson, R. Billa, Tino Hofmann, Eva Schubert, Mathias Schubert

Nebraska Center for Materials and Nanoscience: Faculty Publications

We report on the evolution of the polaron and phonon mode properties in amorphous tungsten oxide thin films measured by spectroscopic ellipsometry in the infrared to ultraviolet spectral regions as a function of the intercalated proton density. A parametric physical model dielectric function is presented, which excellently describes the ellipsometry data over a large intercalated charge-density range. Upon increased amounts of intercalated charge we observe a strong increase in the polaron absorption in the visible spectral range, a decrease in the infrared W–O bond polarity, and an increase in the W=O bond polarity. Our findings support the oxygen-extraction model as …

Geometrical Interpretation And Simulation Of Holz Patterns, Xingzhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

Higher-order Laue zone (HOLZ) pattern is very useful in measurement of crystalline lattice parameters, strain and composition variation in a small area of sample. Bloch dynamical theory on convergent-beam electron diffraction (CBED), including the formation of HOLZ lines, has been well developed and documented in Ref. and references therein. Although CBED patterns and included HOLZ lines are best modeled using a dynamical formulation, models based on a geometrical interpretation for the HOLZ-line positions have remained in widespread use because of their simplicity. Moreover, the geometrical interpretation is helpful to understand the formation of HOLZ lines for beginners. The geometrical interpretation …

High Temperature Dilute Acid Pretreatment Of Coastal Bermudagrass, Arthur Redding, Deepak R. Keshwani, Ziyu Wang, Jay J. Cheng

Department of Agricultural and Biological Systems Engineering: Presentations and White Papers

The conversion of lignocellulosic biomass into ethanol is an encouraging technology in the face of concerns over global warming and finite energy resources. In the southeastern United States, coastal bermudagrass shows potential for use as an energy crop for ethanol production. A review of the literature has shown that research has been done on the dilute sulfuric acid pretreatment of costal bermudagrass at 121ºC prior to enzymatic hydrolysis. This study examined dilute acid concentrations of 0.3%(w/w) to 1.2%(w/w) at temperatures from 120ºC to 180ºC over residence times of 5 to 60 minutes in an effort to optimize the pretreatment process …