Engineering Commons^™

Flow Controller Design And Performance Analysis For Self-Similar Network Traffic, Peng Yan

Turkish Journal of Electrical Engineering and Computer Sciences

Recent studies of high-resolution traffic measurement discovered the self-similarity in both LAN and WAN traffic. In this paper, we introduce a two-degree of freedom rate based flow controller, which includes a robust H^{\infity} control block and an LMMSE based capacity predictor. The former part can guarantee the robust stability against time-varying time delay uncertainties and the latter improves the transient response by predicting the self-similar cross-traffic. Implementation issues are discussed and performance analysis is provided to validate our design. We also investigate the prediction and control in larger time scale which is more applicable for the real network environment

Optimum And Suboptimum Blind Channel And Symbol Estimation For Siso Channels, T. Engi̇n Tuncer

Turkish Journal of Electrical Engineering and Computer Sciences

We present three methods for blind channel and symbol identification from a single or multi-block observation. These methods are deterministic approaches suitable for the identification of quickly changing wireless channels. The first method uses the finite alphabet property and it has good performance even for noisy observations. It requires only a single data frame, which is a unique feature of the method. This method can also be used to identify the channel order. For multi-block observations, we present the maximal ratio combining cross relation (MRCCR) method. It is an optimum approach in terms of instantaneous SNR and is based on …

Effect Of Stochastic Dead Space On Noise In Avalanche Photodiodes, Oh-Hyun Kwon, Majeed M. Hayat, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

A stochastic dead-space model for impact ionization is developed and used to study the effect of the soft nature of the ionization capability of carriers on the excess noise factor of avalanche photodiodes. The proposed model is based on the rationale that the gradual, or soft, transition in the probability density function (PDF) for the distance from birth to impact ionization can be viewed as that resulting from uncertainty in the dead space itself. The resulting soft PDF, which is parameterized by a tunable softness parameter, is used to establish the limitations of the existing hard-threshold ionization models in ultrathin …

Optimized Breakdown Probabilities In Al/Sub 0.6/Ga/Sub 0.4/As-Gaas Heterojunction Avalanche Photodiodes, Oh-Hyun Kwon, Majeed M. Hayat, Joe C. Campbell, Bahaa E.A. Saleh, Malvin Carl Teich

Electrical and Computer Engineering Faculty Research and Publications

Recently, it has been shown that the noise characteristics of heterojunction Al/sub 0.6/Ga/sub 0.4/As-GaAs avalanche photodiodes (APDs) can be optimized by proper selection of the width of the Al/sub 0.6/Ga/sub 0.4/As layer. Similar trends have also been shown theoretically for the bandwidth characteristics. The resulting noise reduction and potential bandwidth enhancement have been attributed to the fact that the high bandgap Al/sub 0.6/Ga/sub 0.4/As layer serves to energize the injected electrons, thereby minimizing their first dead space in the GaAs layer. We show theoretically that the same optimized structures yield optimal breakdown-probability characteristics when the APD is operated in Geiger …

Hydrologic Variations Within Created And Natural Wetlands In Southeastern Virginia, Aaron Dyer Despres

OES Theses and Dissertations

The hydrology of wetlands, particularly how wetland soils collect, store, and redistribute water strongly affects how wetland systems function. In created wetlands, construction processes and materials influence the hydrology and consequently, the potential for successful reestablishment of target vegetation communities. During 2002–2004, the Virginia Department of Transportation constructed large mitigation wetlands on two different Quaternary aged surfaces with very similar hydrogeomorphic conditions. The Sandy Bottom Nature Park site (SBNP) located in Hampton, VA and rests on the sandy loam Tabb Formation while the Charles City Wetland site (CCW) lies on the older and clay-rich Shirley Formation. This study documents and …

Analysis Of Human Thermal Comfort Using A Coupled Model For Predicting Human Body-Environment Heat And Mass Exchange, Ahmed M. Al-Mogbel

Mechanical & Aerospace Engineering Theses & Dissertations

Recent advances in computational fluid dynamics (CFD) make it possible to accurately predict many features of airflow within ventilated spaces. The present study investigates thermal comfort aspects of an occupant in a conditioned space, using a CFD code.

The heat and mass transfer between the human body and the surrounding environment is analyzed by a coupled model that accounts for dispersal of metabolically generated heat in the body to the surroundings by the combined mechanisms of radiation, convection, respiration and evaporation. A two-node model in which two coupled non-linear algebraic equations govern the skin temperature and the body core temperature …

Noise Simulations For An Inverse-Geometry Volumetric Ct System, Taly Gilat Schmidt, Rebecca Fahrig, Norbert J. Pelc

Biomedical Engineering Faculty Research and Publications

This paper examines the noise performance of an inverse-geometry volumetric CT (IGCT) scanner through simulations. The IGCT system uses a large area scanned source and a smaller array of detectors to rapidly acquire volumetric data with negligible cone-beam artifacts. The first investigation compares the photon efficiency of the IGCT geometry to a 2D parallel ray system. The second investigation models the photon output of the IGCT source and calculates the expected noise. For the photon efficiency investigation. the same total number of photons was modeled in an IGCT acquisition and a comparable multi-slice 2D parallel ray acquisition. For both cases …

Development Of A Numerical Model To Simulate Pressure Distributions In Ultrasound Angioplasty, Graham Gavin, Garrett Mcguinness, Finbar Dolan, M.S. Hashmi

Conference Papers

Ultrasound Angioplasty has been shown to be effective in the removal and re-canalising of blockages in arteries (Siegel RJ, 1993). The ultrasound is delivered via a wire waveguide to the lesion location. The wire, generally, has a ball-tip at the distal end to increase transmission of the ultrasound to the surrounding fluid by causing the ball-tip to oscillate between 20– 45kHz and with displacements of up to 100mm peak-to-peak (Atar, 1999 and Yock, 1997). Pressure waves, micro streaming, cavitation and direct contact with the oscillating ball-tip affect the blockage. Most work to date has concentrated on a spherical ball-tip geometry …

Microstructure Design Of A Two Phase Composite Using Two-Point Correlation Functions, Brent L. Adams, H. Garmestani, G. Saheli

Faculty Publications

This work has been funded under the AFOSR Grant no. F49620-03-1-0011 and Army Research Lab contract no. DAAD17-02-P-0398 and DAAD 19-01-1-0742. Two-point distribution functions are used here as to introduce "Microstructure Sensitive Design" in two-phase composites. Statistical distribution functions are commonly used for the representation of microstructures and also for homogenization of materials properties. The use of two-point statistics allows the composite designer to include the morphology and distribution in addition to the properties of the individual phases and components. Statistical continuum mechanics is used to make a direct link between the microstructure and properties (elastic and plastic) in terms …

Coordinated Uav Target Assignment Using Distributed Tour Calculation, David H. Walker, Timothy W. Mclain, Jason K. Kowlett

Faculty Publications

In this chapter a method for assigning unmanned aerial vehicle agents to targets through the use of preplanned vehicle tours is presented. Assignments are based on multi-target tours that consider the spread of the targets and the sensor capabilities of the vehicles. In this way, the individual agents and the team as a whole make better use of team resources and improve team cooperation. Planning and assignments are accomplished in reasonable computational time through the use of heuristics to reduce the problem size.

Ignition Behavior Of Live California Chaparral Leaves, Joshua D. Engstrom, Jared K. Butler, Steven G. Smith, Larry L. Baxter, Thomas H. Fletcher, David R. Weise

Faculty Publications

Current forest fire models are largely empirical correlations based on data from beds of dead vegetation. Improvement in model capabilities is sought by developing models of the combustion of live fuels. A facility was developed to determine the combustion behavior of small samples of live fuels, consisting of a flat-flame burner on a moveable platform. Qualitative and quantitative combustion data are presented for representative samples of California chaparral: manzanita (Arctostaphylos parryana); oak (Quercus berberidifolia); ceanothus (Ceanothus crassifolius), and chamise (Adenostoma fasciculatum). Times to ignition were significantly influenced by shape effects, whereas ignition temperature was more dependent on chemical composition

Electrical Breakdown In Polar Liquids, Shu Xiao

Electrical & Computer Engineering Theses & Dissertations

Hydrodynamic processes following the electrical breakdown in polar liquids, mainly water and propylene carbonate, are studied with electrical pulse-probe systems and optical diagnostics including shadowgraphy and Schlieren techniques. The dielectric strength of water in a repetitively pulsed power system is found to be 750 kV/cm and 650 kV/cm for pulses of 200 nanosecond and 8 microsecond duration, respectively. For energies less than 1 J, the discharge plasma decays in approximately one microsecond. The mechanical effect created by the expanding plasma is a shock wave which has an initial pressure of 1 GPa and decays within approximately 5 microseconds. The observed …

Computation Of Shock Induced Noise In Imperfectly Expanded Supersonic Jets, Bulent Imamoglu

Mechanical & Aerospace Engineering Theses & Dissertations

Screech noise exists only in imperfectly expanded jets. The exit pressure of imperfectly expanded jets does not match ambient pressure, so expansion or compression waves appear out of the nozzle and generate shock cell patterns. Screech is generated by the interaction of shock cells and instability waves. Many experiments and computations have been done to model screech noise, but it is not yet a very well known subject.

A numerical study is performed to understand screech generation mechanisms and to compare with latest experiments. A supersonic underexpanded jet of 25.4 mm diameter is modeled for cases of Mach numbers of …

An Integration Of Pc Hardware & Software In Teaching Engineering Technology Courses, Steve Hsiung, Richard Jones

Engineering Technology Faculty Publications

As technology advances, the price of a PC drops dramatically. This trend has resulted in PCs that are complex, powerful, and very affordable. Today's PC is a popular and essential tool in teaching software programming course(s) in C, C++, Visual Basic, or Java, running commercial software supporting courses in circuit simulation/design or circuit board layout, and acting as a workstation to gain access to the Internet or LAN networks. In most Engineering Technology curricula there is a limited amount of linkage between those PC applications. The actual effort to merge the hard-gained knowledge of hardware & software concepts together through …

Development Of Indiana's Sps9-A Site, Ayesha Shah, J. Olek

JTRP Technical Reports

The Superpave system for hot mix asphalt (HMA) design was introduced in 1995 and adopted throughout most of the USA by 2000. This system uses performance-oriented approach to materials selection and mix design, and takes into account the local environmental and traffic conditions. It recognizes that the behavior of HMA depends on the temperature, loading and aging conditions and provides tools (in the form of materials selection and performance-related tests) that should help to protect pavements against low-temperature cracking, rutting and fatigue cracking. This report summarizes the field and laboratory studies conducted to investigate the influence of asphalt binder grade …

Evaluation Of Indot Hyperfix Project, Kumares C. Sinha, Bob G. Mccullouch, Darcy M. Bullock, Sravanthi Konduri, Jon D. Fricker, Samuel Labi

JTRP Technical Reports

In 2003 the Indiana Department of Transportation executed an ambitious interstate reconstruction project in Indianapolis, named Hyperfix. This project completely closed the I-65/70 section during reconstruction, on which approximately 250,000 vehicles travel daily. Due to the scope and risk involved, an extensive amount of planning, coordination, and cooperation occurred. The main section was rebuilt during the total closure phase, which lasted 55 days. The total closure approach had never been performed before by INDOT on such a high volume artery in a downtown metropolitan area. This present study analyzed the project and its impact on the Indianapolis area. The report …

New Combination Treatments For Control Of Johnsongrass Along Roadsides, D. James Morré

JTRP Technical Reports

This project was to develop a cost-effective method for chemical eradication of Johnsongrass along Indiana roadsides. Johnsongrass, together with Canada thistle, represents Indiana’s most serious noxious weed invader where the need for control is mandated by law. Combined target-directed laboratory and greenhouse studies identified a new candidate herbicide, Outrider, which when combined with a new additive designated TR-IV gives eradication of Johnsongrass when applied to plants after less than 20 inches (70 cm) of growth or regrowth following mowing. The combination does not harm oversprayed established fescue or bluegrass. Based on limited implementation activities (two years experience), the recommendation is …

A Proposal For Re-Engineering The Procurement Of Building Materials By Effective Use Of Ict, Alan V. Hore, Roger West

Conference papers

This paper seeks to establish the case for re-engineering the procurement of materials in the Irish construction industry. The authors make their observations from witnessing, first-hand, the operation of a purchasing function in a large contracting organisation in the Republic of Ireland. The authors identify the core problems that exist in the current mainly paper-based process and present a strong case for the re-engineering of the process by the adoption of a fully integrated Information Communications Technology (ICT) solution

Resource Harvesting Within The Oai-Pmh Framework, Herbert Van De Sompel, Michael L. Nelson, Carl Lagoze, Simeon Warner

Computer Science Faculty Publications

Motivated by preservation and resource discovery, we examine how digital resources, and not just metadata about resources, can be harvested using the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). We review and critique existing techniques for identifying and gathering digital resources using metadata harvested through the OAI-PMH. We introduce an alternative solution that builds on the introduction of complex object formats that provide a more accurate way to describe digital resources. We argue that the use of complex object formats as OAI-PMH metadata formats results in a reliable and attractive approach for incremental harvesting of resources using the OAI-PMH.

Metadata And Buckets In The Smart Object, Dumb Archive (Soda) Model, Michael L. Nelson, Kurt Maly, Delwin R. Croom Jr., Steven W. Robbins

Computer Science Faculty Publications

We present the Smart Object, Dumb Archive (SODA) model for digital libraries (DLs), and discuss the role of metadata in SODA. The premise of the SODA model is to "push down" many of the functionalities generally associated with archives into the data objects themselves. Thus the data objects become "smarter", and the archives "dumber". In the SODA model, archives become primarily set managers, and the objects themselves negotiate and handle presentation, enforce terms and conditions, and perform data content management. Buckets are our implementation of smart objects, and da is our reference implementation for dumb archives. We also present our …

Logistics Outsourcing And 3pl Challenges, Michelle L. F. Cheong

Research Collection School Of Computing and Information Systems

Logistics has been an important part of every economy and every business entity. The worldwide trend in globalization has led to many companies outsourcing their logistics function to Third-Party Logistics (3PL) companies, so as to focus on their core competencies. This paper attempts to broadly identify and categorize the challenges faced by 3PL companies and discover potential gaps for future research. Some of the challenges will be related with the experience and information collected from interviews with two 3PL companies.

The Role Of The Solid Substrate On The Spreading Kinetics Of A Liquid Droplet, Bashar Jalal Sasa

Theses

Classic hydrodynamic wetting theory leads to a linear relationship between spreading speed and the capillary force, being determined only by the surface tension of the liquid and its viscosity.

The theory appears in good agreement with results generated from experiments conducted on the spreading of Polydimethylsiloxanes (PDMS) on soda-lime glass substrate and fails to account for the behavior of other liquids. This thesis examines the role played by the solid substrate on the spreading kinetics of liquid droplets. The set of experiments whose results are presented below used different types of liquids with various properties of surface tension and viscosity …

Material Selection For A Composite Hip Joint, Ahmed Abdullah Ali Al-Hosani

Theses

The use of biomaterials in orthopedic surgery has been successfully acceptable in the current medical practice. Total hip joint replacement (THR) is one of the most popular and successful operations in orthopedics. Total hip replacement (THR) has been using metal prosthesis for many years. However, the use of metal implants has two major disadvantages. The first disadvantage is that the stiffness of the metallic prosthesis is relatively high compared to the surrounding, load carrying bone. The elastic moduli of titanium and cobalt-chromium alloy are 110 and 210 GPa, respectively. Whereas the elastic modulus of cortical bone ranges from 15 to …

Building A Comprehensive Energy Model For Off-Highway Vehicles With Emphasis On Vehicle Thermal Control Systems, Ayhan Zora

Dissertations and Theses @ UNI

Utilizing machine and thermal system simulations (vehicle energy models) can be very helpful for vehicle manufacturing companies to develop a machine with acceptable component temperatures, less heat loads to the vehicle cooling systems, and reduced emissions that will also reduce overall product development cycle.

Energy models of vehicles were developed mostly in the automotive industry, and most of these studies were based on partial energy models.

The aim of this research study was to create a comprehensive energy model for agricultural machinery, which will be a basis for future work on similar products. A tractor model from a Midwest off-road …

Creating A Video Device Application, Kevin Septor

Honors Theses

A video device, such as a webcam, has the capability to be used in many ways, including recording video and behaving like a security camera. A TV tuner card can also record video, and in addition be used for watching television. However, the video hardware and device driver the operating system uses to access it are only capable of delivering raw frames of video. A user space application is necessary for exploiting the capabilities of such a device beyond reading sequential frames of video. This research explores the desiderata in a powerful video device application, and introduces a program that …