Engineering Commons^™

Analysis Of Energy Efficiency In Fading Channels Under Qos Constraints, Deli Qiao, M. Cenk Gursoy, Senem Velipasalar

Department of Electrical and Computer Engineering: Faculty Publications

Energy efficiency in fading channels in the presence of Quality of Service (QoS) constraints is studied. Effective capacity, which provides the maximum arrival rate that a wireless channel can sustain while satisfying statistical QoS constraints, is considered. Spectral efficiency–bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity formulation, rather than the Shannon capacity. Through this analysis, energy requirements under QoS constraints are identified. The analysis is conducted under two assumptions: perfect channel side information (CSI) available only at the receiver and perfect CSI available at both the receiver and transmitter. In particular, it …

Control Of Ipm Synchronous Generator For Maximum Wind Power Generation Considering Magnetic Saturation, Wei Qiao, Qu, Richard G. Harley

Department of Electrical and Computer Engineering: Faculty Publications

Permanent-magnet synchronous generators (PMSGs) are commonly used for small variable-speed wind turbines to produce high-efficiency, high-reliability, and low-cost wind power generation. This paper proposes a novel control scheme for an interior PMSG (IPMSG) driven by a wind turbine, in which the d-axis and q-axis stator-current components are optimally controlled to achieve the maximum wind power generation and loss minimization of the IPMSG. The effect of magnetic saturation, which causes the highly nonlinear characteristics of the IPMSG, is considered in the control-scheme design. The optimal d-axis stator-current command is obtained as a function of the IPMSG rotor speed by solving a …

Real-Time Implementation Of A Statcom On A Wind Farm Equipped With Doubly Fed Induction Generators, Wei Qiao, Ganesh Kumar Venayagamoorthy, Ronald G. Harley

Department of Electrical and Computer Engineering: Faculty Publications

Voltage stability is a key issue to achieve the uninterrupted operation of wind farms equipped with doubly fed induction generators (DFIGs) during grid faults. This paper investigates the application of a static synchronous compensator (STATCOM) to assist with the uninterrupted operation of a wind turbine driving a DFIG, which is connected to a power network, during grid faults. The control schemes of the DFIG rotor- and grid-side converters and the STATCOM are suitably designed and coordinated. The system is implemented in real-time on a Real Time Digital Simulator. Results show that the STATCOM improves the transient voltage stability and therefore …

Coordinated Reactive Power Control Of A Large Wind Farm And A Statcom Using Heuristic Dynamic Programming, Wei Qiao, Ronald G. Harley, Ganesh Venayagamoorthy

Department of Electrical and Computer Engineering: Faculty Publications

A novel interface neurocontroller (INC) is proposed for the coordinated reactive power control between a large wind farmequippedwith doubly fed induction generators (DFIGs) and a static synchronous compensator (STATCOM). The heuristic dynamic programming (HDP) technique and radial basis function neural networks (RBFNNs) are used to design this INC. It effectively reduces the level of voltage sags as well as the over-currents in the DFIG rotor circuit during grid faults, and therefore, significantly enhances the fault ride-through capability of thewind farm. The INCalso acts as a coordinated external damping controller for the wind farm and the STATCOM, and therefore, improves power …

Dynamic Modeling And Control Of Doubly Fed Induction Generators Driven By Wind Turbines, Wei Qiao

Department of Electrical and Computer Engineering: Faculty Publications

Two different models are presented and developed in PSCAD/EMTDC to represent a variable-speed wind turbine equipped with a doubly fed induction generator (DFIG). One is the most detailed switching-level (SL) model. The other is a simplified fundamental-frequency (FF) model. The effect of different shaft system representations on the dynamic behavior of the wind turbine generator (WTG) system and the issue of damping low-frequency torsional oscillations are investigated. Dynamic and transient simulation studies are carried out to compare two models with different shaft system representations. Results show that the FF model is sufficient while the lumpedmass shaft model is insufficient to …

Enhanced Chemical Vapor Deposition Of Diamond By Wavelength-Matched Vibrational Excitations Of Ethylene Molecules Using Tunable Co2 Laser Irradiation, Hao Ling, Q. Xie, T. Gebre, X. K. Shen, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Wavelength-matched vibrational excitations of ethylene (C₂H₄ molecules using a tunable carbon dioxide (CO₂) laser were employed to significantly enhance the chemical vapor deposition (CVD) of diamond in open air using a precursor gas mixture of C₂H₄, acetylene (C₂H₂), and oxygen (O₂). The CH₂-wag vibration mode (_v7) of the C₂H₄ molecules was selected to achieve the resonant excitation in the CVD process. Both laser wavelengths of 10.591 and 10.532 μm were applied to the CVD processes to compare …

Achievable Rates And Resource Allocation Strategies For Imperfectly Known Fading Relay Channels, Junwei Zhang, M. Cenk Gursoy

Department of Electrical and Computer Engineering: Faculty Publications

Achievable rates and resource allocation strategies for imperfectly known fading relay channels are studied. It is assumed that communication starts with the network training phase in which the receivers estimate the fading coefficients. Achievable rate expressions for amplify-and-forward and decode-and-forward relaying schemes with different degrees of cooperation are obtained. We identify efficient strategies in three resource allocation problems: (1) power allocation between data and training symbols, (2) time/bandwidth allocation to the relay, and (3) power allocation between the source and relay in the presence of total power constraints. It is noted that unless the source-relay channel quality is high, cooperation …

Sequencing, Analysis, And Annotation Of Expressed Sequence Tags For Camelus Dromedarius, Abdulaziz M. Al-Swailem, Maher M. Shehata, Faisel M. Abu-Duhier, Essam J. Al-Yamani, Khalid A. Al-Busadah, Mohammed S. Al-Arawi, Ali Y. Al-Khider, Abdullah N. Al-Muhaimeed, Fahad H. Al-Qahtani, Manee M. Manee, Badr M. Al-Shomrani, Saad M. Al-Qhtani, Amer S. Al-Harthi, Kadir C. Akdemir, Mehmet S. Inan, Hasan H. Otu

Department of Electrical and Computer Engineering: Faculty Publications

Despite its economical, cultural, and biological importance, there has not been a large scale sequencing project to date for Camelus dromedarius. With the goal of sequencing complete DNA of the organism, we first established and sequenced camel EST libraries, generating 70,272 reads. Following trimming, chimera check, repeat masking, cluster and assembly, we obtained 23,602 putative gene sequences, out of which over 4,500 potentially novel or fast evolving gene sequences do not carry any homology to other available genomes. Functional annotation of sequences with similarities in nucleotide and protein databases has been obtained using Gene Ontology classification. Comparison to available …

Genes Differentially Expressed By Cumulus Cells And Assays Using Same To Identify Pregnancy Competent Oocytes, Jose B. Cibelli, Amy E. Iager, Hasan H. Otu

Department of Electrical and Computer Engineering: Faculty Publications

A genetic means of identifying "pregnancy competent" oocytes is provided. The means comprises detecting the level of expression of one or more genes that are expressed at characteristic levels (upregulated or downregulated) in cumulus cells derived from pregnancy competent oocytes. This characteristic gene expression level, or pattern referred to herein as the "pregnancy signature", also can be used to identify subjects with underlying conditions that impair or prevent the development of a viable pregnancy, e.g., pre-menopausal condition, other hormonal dysfunction, ovarian dysfunction, ovarian cyst, cancer or other cell proliferation disorder, autoimmune disease and the like. In preferred embodiments the …

Sample Investigating System, Martin M. Liphardt, Thomas E. Tiwald, Blaine D. Johs, Jeffery S. Hale, Craig M. Herzinger, Steven E. Green, Ping He, Ronald A. Synowicki, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

A spectroscopic system for adjusting spacing between an adjacent source/detector as a unit, and a sample, and a reflecting means for directing an incident beam which refelcts from said sample back onto said sample and then into the detector along a locus which is in a plance of incidence that is offset from that of the incident beam, or directly from the reflecting means into the detecor, including means for reducing reflections of a beam fo electromagnetic from the back of a sample, including methodology of use.

Simulation Of Coherent Radar Imaging Using Continuous Wave Noise Radar, Jing Xu, Michael Hoffman, B.L. Cheong, R.D. Palmer

Department of Electrical and Computer Engineering: Faculty Publications

A computationally simple cross-correlation model for multiple backscattering from a continuous wave (CW) noise radar is developed and verified with theoretical analysis and brute-force time-domain simulations. Based on this cross-correlation model, a modification of an existing numerical method originally developed by Holdsworth and Reid for spaced antenna (SA) pulsed radar is used to simulate the estimated cross correlation corresponding to atmospheric backscattering using a coherent CW noise radar. Subse- quently, coherent radar imaging (CRI) processing comparisons between the CW noise radar and a con- ventional pulsed radar are presented that verify the potential of CW noise radar for atmospheric imaging.

Correction To “The Theory Of Quaternion Orthogonal Designs”, Tadeusz Wysocki, Beata J. Wysocki, Sarah Spence Adams

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

Seberry et al. claimed that even though the dual-polarized transmission channel cannot be considered as described by means of a single quaternionic gain, the maximum-likelihood (ML) decoding rule can be decoupled for orthogonal space–time-polarization block codes (OSTPBCs) derived from quaternion orthogonal designs (QODs) [1, Sec. IV]. Regretfully, a correction is necessary, and we will show that decoupled decoding using the method presented therein is only optimal for codes derived from certain QODs, not from arbitrary QODs as previously suggested.

Measuring Performance Of Innovative Pavement Features, Wayne Jensen, Zhigang Shen, Cody Kluver

Department of Construction Engineering and Management: Faculty Publications

The Nebraska Department of Roads (NDOR) conducts annual examinations of the state's interstate and federal highway pavements. During these examinations, numerous indicators of pavement performance are measured directly or compiled from parameters recorded by a vehicle passing over the pavement section. Parameters are documented and analyzed for each one-tenth mile pavement segment. Seven sections where innovative features have been incorporated into the pavement were selected by the NDOR for comparison to nearby conventional pavement sections. This study used various parameters recorded by the NDOR as well as field observations to compare the performance of seven pairs of pavement sections. Each …

Reduction Of Surface Acoustic Wave Resonator Normal Acceleration Sensitivity Using Piezoelectric Actuators, X. Y. Shan, Y. T. Hu, J. S. Yang

Department of Engineering Mechanics: Faculty Publications

We attach a piezoelectric actuator to a surface acoustic wave resonator under normal acceleration to reduce its acceleration sensitivity. It is shown theoretically that under a given acceleration, the acceleration induced frequency shift in the resonator can be reduced or even completely eliminated when a proper electric field is applied to the piezoelectric actuator.

Harvesting Magnetic Energy Using Extensional Vibration Of Laminated Magnetoelectric Plates, C. L. Zhang, J. S Yang, W. Q. Chen

Department of Engineering Mechanics: Faculty Publications

Magnetically forced extensional vibrations of laminated plates with piezoelectric and piezomagnetic layers are analyzed theoretically. It is shown that such a structure can be used to harvest magnetic energy and convert it to electric energy. The output power and the energy conversion efficiency are calculated. The load dependence of the magnetoelectric coupling coefficient is also obtained.

Real-Time Depth Sectioning: Isolating The Effect Of Stress On Structure Development In Pressure-Driven Flow, Lucia Fernandez-Ballester, Derek W. Thurman, Julia A Kornfield

Department of Engineering Mechanics: Faculty Publications

Transient structure development at a specific distance from the channel wall in a pressure-driven flow is obtained from a set of real-time measurements that integrate contributions throughout the thickness of a rectangular channel. This “depth sectioning method” retains the advantages of pressure-driven flow while revealing flow-induced structures as a function of stress. The method is illustrated by applying it to isothermal shear-induced crystallization of an isotactic polypropylene using both synchrotron x-ray scattering and optical retardance. Real-time, depth-resolved information about the development of oriented precursors reveals features that cannot be extracted from ex-situ observation of the final morphology and that are …

Convergence, Adaptive Refinement, And Scaling In 1d Peridynamics, Florin Bobaru Ph.D., Mijia Yabg Ph.D., Leonardo F. Alves M.S., Stewart A. Silling Ph.D., Ebrahim Askari Ph.D., Jifeng Xu Ph.D.

Department of Engineering Mechanics: Faculty Publications

We introduce here adaptive refinement algorithms for the non-local method peridynamics, which was proposed (in J. Mech. Phys. Solids 2000; 48:175–209) as a reformulation of classical elasticity for discontinuities and long-range forces. We use scaling of the micromodulus and horizon and discuss the particular features of adaptivity in peridynamics for which multiscale modeling and grid refinement are closely connected. We discuss three types of numerical convergence for peridynamics and obtain uniform convergence to the classical solutions of static and dynamic elasticity problems in 1D in the limit of the horizon going to zero. Continuous micromoduli lead to optimal rates of …

Evaporation Induced Two-Dimensional Buckling Within Liquid Droplet, Ziguang Chen, Maozi Liu, Gang-Yu Liu, Li Tan

Department of Engineering Mechanics: Faculty Publications

Evaporation of a liquid droplet containing a thin layer of surfactants atop could generate two-dimensional buckling on surfaces. Herringbone features were produced via embedded nanoparticle beds. We assign transient surface tension as the driving force for such a phenomenon. Considering the surfactant layer as a thin elastic film, a continuum model is employed to calculate the mechanical properties of the layer. Particularly, we estimated an elastic modulus of 4 GPa for the surfactant layer, indicating rather strong mechanical properties of these small molecules when they are close packed to form supramolecules via noncovalent binding.

Comparison Of Fuzzy Clustering Methods And Their Applications To Geophysics Data, David J. Miller, Carl A. Nelson, Molly Boeka Cannon, Kenneth P. Cannon

Department of Mechanical and Materials Engineering: Faculty Publications

Fuzzy clustering algorithms are helpful when there exists a dataset with subgroupings of points having indistinct boundaries and overlap between the clusters. Traditional methods have been extensively studied and used on real-world data, but require users to have some knowledge of the outcome a priori in order to determine howmany clusters to look for. Additionally, iterative algorithms choose the optimal number of clusters based on one of several performance measures. In this study, the authors compare the performance of three algorithms (fuzzy c-means, Gustafson-Kessel, and an iterative version of Gustafson-Kessel) when clustering a traditional data set as well as real-world …

Missouri River Recovery Program: Fish And Wildlife Protection – Key To A Healthy River

United States Army Corps of Engineers, Omaha District

Fish and wildlife conservation on the Missouri River is one of the eight congressionally-authorized project purposes of the U.S. Army Corps of Engineers. In support of this, the Corps manages lands and waters to ensure its availability for future generations and to help preserve healthy ecosystems and biodiversity. This purpose originally focused on maintaining native and game species, but in recent years it has taken on renewed prominence with efforts to recover threatened and endangered species.

The Missouri River is a dynamic ecosystem, creating and maintaining important open water, sandbar, wetland, and forest habitat for a wide diversity of wildlife, …

Missouri River Recovery Program: Reclaiming Lost Habitat: Real Estate Program

United States Army Corps of Engineers, Omaha District

Historically, the Missouri River continually reshaped itself by eroding banks in some areas and building up islands and sandbars in other areas. The river’s dynamic nature provided plenty of habitat for native species of animals and plants.

Efforts in the 1900s to manage the river by building dams, levees and a navigation channel provided many social and economic benefits to the nation but drastically reduced the amount of habitat available for the river’s native species. Today, lack of habitat is a major reason that several Missouri River species are endangered or threatened, such as the pallid sturgeon, least tern and …

Missouri River Recovery Program: River Power To Clean Energy

United States Army Corps of Engineers, Omaha District

The overall vision of the Missouri River Recovery Program is to create a sustainable ecosystem supporting thriving populations of native species while providing for current social and economic values. Many of these social and economic values are authorized by the U.S. Congress as crucial uses of the river’s resources. Hydroelectric power is one of these authorized purposes. Hydroelectric power uses the power of the river to provide electricity to homes and businesses within the Missouri River Basin and beyond.

Missouri River Recovery Program: Missouri River Basin

United States Army Corps of Engineers, Omaha District

The Missouri River, the nation’s longest, travels more than 2,300 miles from Three Forks, Montana, to join the Mississippi River near St. Louis, Missouri. For centuries, the river has served as the center of life for the inhabitants of North America’s Great Plains. Following exploration and mapping by Lewis and Clark’s Corps of Discovery in the early 1800s, the Missouri River became the gateway to the West.

Historically, the dynamic and untamed Missouri River has produced violent floods in the spring and summer with erosive forces that ate away its banks and turned its waters the color of mud.

Since …

Missouri River Recovery Program: Emergent Sandbar Habitat

United States Army Corps of Engineers, Omaha District

This Value Engineering (VE) Report summarizes the events of the April 6-8, 2009 VE workshop facilitated by GeoVal, Inc. for the U.S. Army Corps of Engineers (USACE) Omaha District, Nebraska. The Missouri River Recovery Program - Emergent Sandbar Habitat Value Engineering Study focuses on the assessment of the Missouri River Recovery Program (MRRP) Habitat Creation Project with specific focus on the creation of emergent sandbar habitats, examining current plans and programs to seek out alternative approaches and ideas that will improve the overall performance of the program.

The MRRP seeks to mitigate near-term losses of Missouri River habitats and recover …

Missouri River Recovery Program: Putting The Pieces Together: Mrrp Main Programs

United States Army Corps of Engineers, Omaha District

The Missouri River Recovery Program (MRRP) is a comprehensive effort led by the U.S. Army Corps of Engineers in partnership with the U.S. Fish and Wildlife Service, Tribes, states, other federal agencies and non-governmental organizations to develop and implement actions to create a healthy Missouri River.

The MRRP consists of:

-The Missouri River Bank Stabilization and Navigation Project (BSNP) Fish
and Wildlife Mitigation Project

- The Amended Biological Opinion and the Corps’ Record of Decision related
to the Master Water Control Manual for the Missouri River

- The 2007 Water Resources Development Act

Each of these guiding authorities set out …

Missouri River Recovery Program: Spring Rise Monitoring

United States Army Corps of Engineers, Omaha District

The U.S. Army Corps of Engineers is committed to recover Missouri River species, while fulfilling its century-old responsibility to protect human health and safety. To aid in the recovery of the endangered pallid sturgeon, the Corps releases extra water from Missouri River reservoirs in March and May. These “spring pulses” mimic the historic river rises that resulted from melting snow on the plains and mountains, before the construction of dams on the river. Biologists believe these pulse events are necessary for Missouri River species to reproduce and survive, which is critical for a healthy river environment.

At the same time, …

Farm Tractor Rollover Protection: Why Simply Getting Rollover Protective Structures Installed On All Tractors Is Not Sufficient, Roger M. Hoy

Department of Agricultural and Biological Systems Engineering: Faculty Publications

In North America, agricultural is one of the most hazardous occupations, trailing only mining and construction in likelihood of experiencing a serious injury or fatality. Without quoting specific statistics, roughly one-half of the serious injuries experienced each year involve an agricultural tractor, and roughly one-half of the serious injuries involving tractors are rollovers. It is well established that when a tractor is equipped with a rollover protective structure (ROPS) and seatbelt, and both are utilized, serious injuries rarely, if ever occur, in the event of an overturn. In fact, tractor overturns are the leading cause of agricultural fatalities in the …

Switchgrass For Bioethanol And Other Value-Added Applications: A Review, Deepak R. Keshwani, Jay J. Cheng

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Switchgrass is a promising feedstock for value-added applications due to its high productivity, potentially low requirements for agricultural inputs and positive environmental impacts. The objective of this paper is to review published research on the conversion of switchgrass into bioethanol and other value-added products. Environmental benefits associated with switchgrass include the potential for carbon sequestration, nutrient recovery from runoff, soil remediation and provision of habitats for grassland birds. Pretreatment of switchgrass is required to improve the yields of fermentable sugars. Based on the type of pretreatment, glucose yields range from 70% to 90%, and xylose yields range from 70% to …

Plant Sterol And Policosanol Characterization Of Hexane Extracts From Grain Sorghum, Corn, And Their Ddgs, Caolina Leguizamón, Curtis L. Weller, Vicki L. Schlegel, Timothy P. Carr

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Plant sterols (PS) and policosanols (PC) have been attributed with plasma cholesterol-lowering properties in humans. Hexane extracts from grain sorghum, corn and their distillers dried grain with solubles (DDGS), an important co-product of ethanol production, contain these health promoting compounds, which could be used to develop health promoting dietary products. However, limited information is currently available regarding optimal methods of extraction and their influence on plant sterol or PC levels and compositions. Therefore, the objective of this study was to quantify lipids, particularly PS and PC extracted from grain sorghum and its DDGS using reflux and Soxtec methods. Corn and …

Thermal Degradation Kinetics Of Distillers Grains And Solubles In Nitrogen And Air, Lijun Wang, Ajay Kumar, Milford Hanna, Curtis L. Weller, D. D. Jones

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The pyrolysis and oxidation kinetics of distillers grains and solubles were determined using thermogravimetric analysis. The starting temperature of pyrolysis and oxidation of distillers grains and solubles increased with the increase of heating rate and initial moisture content. The pyrolysis and oxidation of distillers grains and solubles were completed at 650°C and 850°C, respectively, which were independent of the heating rate and the initial moisture content. The residual weights of distillers grains and solubles after pyrolysis and oxidation were 27.15% and 5.49% of the original dry mass of distillers grains and solubles. Thermogravimetrical analysis data was used to determine kinetic …