Engineering Commons^™

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 13, Number 4, April 1997, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A ten page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Investigating The Use Of Kalman Filtering Approaches For Dynamic Origin-Destination Trip Table Estimation, Pushkin Kachroo, Kaan Ozbay, Arvind Narayanan

Electrical & Computer Engineering Faculty Research

This paper studies the applicability of Kalman filtering approaches for network wide traveler origin-destination estimation from link traffic volumes. The paper evaluates the modeling assumptions of the Kalman filters and examines the implications of such assumptions.

Slice Location Dependence Of Aortic Regurgitation Measurements With Mr Phase Velocity Mapping, George P. Chatzimavroudis, Peter G. Walker, John N. Oshinski, Robert H. Franch, Roderic I. Pettigrew, Ajit P. Yoganathan

Chemical & Biomedical Engineering Faculty Publications

Although several methods have been used clinically to assess aortic regurgitation (AR), there is no “gold standard” for regurgitant volume measurement. Magnetic resonance phase velocity mapping (PVM) can be used for noninvasive blood flow measurements. To evaluate the accuracy of PVM in quantifying AR with a single imaging slice in the ascending aorta, in vitro experiments were performed by using a compliant aortic model. Attention was focused on determining the slice location that provided the best results. The most accurate measurements were taken between the aortic valve annulus and the coronary ostia where the measured (Y) and actual …

Evaluation Of Speed Limits In Kentucky (Kyspr 96-172), Kenneth R. Agent, Jerry G. Pigman, Joel M. Weber

Kentucky Transportation Center Research Report

The objectives of this study were to examine current criteria and procedures used for setting speed limits on public roads and to recommend appropriate maximum speed limits for various types of roads. The study involved three major areas. These were: review of literature, collection and analysis of speed data, and collection and analysis of accident data. The speed data included collecting data on various highway types using the “moving” radar mode, use of data from speed monitoring stations, comparison of spot speed data before and after speed limit changes, and both moving and spot speed data at construction zones. Accident …

Feedback Control Solutions To Network Level User-Equilibrium Real-Time Dynamic Traffic Assignment Problems, Pushkin Kachroo, Kaan Ozbay

Electrical & Computer Engineering Faculty Research

A new method for performing dynamic traffic assignment (DTA) is presented which is applicable in real time, since the solution is based on feedback control. This method employs the design of nonlinear H∞ feedback control systems which is robust to certain class of uncertainties in the system. The solution aims at achieving user equilibrium on alternate routes in a network setting.

Identifying Air Flow Failure Modes In Small Commercial Buildings: Tools And Methodologies For Building Commissioning Diagnostics, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

A recent study of small commercial buildings in central Florida found that uncontrolled air flow -- including duct leakage, return air imbalance, and exhaust air/make-up air imbalance -- is widespread. Of 70 buildings studied, only 1 was identified as having no significant uncontrolled air flow. The causes of uncontrolled air flow include failure of design, poor workmanship, O&M problems, HVAC commissioning failures, materials degradation, and building retrofits. This study also found that the consequences of uncontrolled air flow are often quite severe and varied -- including high utility bills, occupant thermal discomfort, high humidity, mold and mildew growth, moisture damage …

Least-Squares Approximate Solution Of Overdetermined Sylvester Equations, A. Scottedward Hodel, Pradeep Misra

Electrical Engineering Faculty Publications

We address the problem of computing a low-rank estimate Y of the solution X of the Lyapunov equation AX + XA' + Q = O without computing the matrix X itself. This problem has applications in both the reduced-order modeling and the control of large dimensional systems as well as in a hybrid algorithm for the rapid numerical solution of the Lyapunov equation via the alternating direction implicit method. While no known methods for low-rank approximate solution provide the two-norm optimal rank k estimate Xk of the exact solution X of the Lyapunov equation, our iterative algorithms provide an effective …

An Adaptive Scheme For Admission Control In Atm Networks, Saragur M. Srinidhi, William H. Thesling, Vijaya K. Konangi

Electrical and Computer Engineering Faculty Publications

This paper presents a real time front-end admission control scheme for ATM networks. A call management scheme which uses the burstiness associated with traffic sources in a heterogeneous ATM environment to effect dynamic assignment of bandwidth is presented. In the proposed scheme, call acceptance is based on an on-line evaluation of the upper bound on cell loss probability which is derived from the estimated distribution of the number of calls arriving. Using this scheme, the negotiated quality of service will be assured when there is no estimation error. The control mechanism is effective when the number of …

Generalized Beam Matrices. Iv. Optical System Design, Anthony A. Tovar, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

Systematic procedures are presented for determining the optical components needed to produce an arbitrary transformation of a Gaussian light beams's spot size, radius of curvature, displacement, and direction of propagation. As an example, an optical system is considered that spatially separates the two coincident Gaussian beams produced by a high-diffraction-loss resonator that uses a Gaussian variable-reflectivity output coupler. In addition, an ABCDGH reverse matrix theorem and an ABCDGH Sylvester theorem are also derived. These matrix theorems may be used to satisfy special constraints inherent in the design of multipass and periodic optical systems.

Generic, Geometric Finite Element Analysis Of The Transtibial Residual Limb And Prosthetic Socket, Barbara Silver-Thorn, Dudley S. Childress

Biomedical Engineering Faculty Research and Publications

Finite element analysis was used to investigate the stress distribution between the residual limb and prosthetic socket of persons with transtibial amputation (TTA). The purpose of this study was to develop a tool to provide a quantitative estimate of prosthetic interface pressures to improve our understanding of residual limb/prosthetic socket biomechanics and prosthetic fit. FE models of the residual limb and prosthetic socket were created. In contrast to previous FE models of the prosthetic socket/residual limb system, these models were not based on the geometry of a particular individual, but instead were based on a generic, geometric approximation of the …

Hybrid Rocket Powered Upper Stage Design Report, Imran Mukhtar

Honors Capstone Projects and Theses

No abstract provided.

Rate-Equation Approximations In High-Gain Lasers, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

The rate-equation approximation is one of the most fundamental and universally employed simplifications in laser analyses. The accuracy and regions of applicability of this approximation are explored in comparisons with more rigorous semiclassical models. Higher-order rate-equation approximations are also developed, and these improved models can yield much better accuracy than conventional rate equations with little added complexity. The modified adiabatic elimination methods reported here would also be useful in reducing the mathematical models governing other physical systems.

Glycerolysis Of Fats And Methyl Esters., Hossein Noureddini, V Medikonduru

Papers in Biomaterials

The glycerolysis of methyl esters and triglycerides with crude glycerol. a coproduct from the transesterification of triglycerides, was studied. Three procedures were followed ior this conversion. The first procedure was a one-step glycerolysis with methyl esters. The second procedure was a two-step process. This proced~~irnev olved an initial partial glycerolysis with methyl esters, followed by fat glycerolysis. The third procedure u,as a simultaneous glycerolysis n,ith methyl esters and triglycerides. In the glycerolysis with methyl esters, the removal of methanol is vital to the production of mono- and diglycerides. Methanol was removed either by drawing vacuum on the reactor or by …

Mlpq: A Linear Constraint Database System With Aggregate Operators, Yiming Li

School of Computing: Dissertations, Theses, and Student Research

In this project report, I will discuss a Multiple Linear Programming Query (MLPQ) system and the theoretical background of this system.The MPLQ system is developed to solve some realistic problems involving both linear programming (UP) techniques and linear constraint databases (LCDBs) theory. The MLPQ system is aimed at providing a mechanism of bridging these two important areas. system basically consists of three parts which are a linear constraint database, an LP solver, and an interface between the LCDB and the LP solver. The LCDB of the MLPQ system contains multiple linear programming problems. The LP solver used in the MPLQ …

Analysis Of The "Crack Characteristic Signal" Using A Generalized Scattering Matrix Representation, Christian J. Huber, Habibollah Abiri, R. Zoughi, Stoyan I. Ganchev

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic properties of a system formed by an open-ended rectangular waveguide and a surface crack/slot in a metallic specimen are described in this paper. Scanning a crack on a metal surface changes the reflection coefficient of the incident dominant mode. A model as a function of relative crack location within the waveguide aperture (i.e., crack moving with respect to the waveguide aperture) is desired to describe and optimize practical crack detection applications. Hence, the change in the reflection coefficient for a generalized system encompassing empty, filled, and finite cracks located at an arbitrary position inside the waveguide aperture, is evaluated. …

Bs News

Building Services Engineering

No abstract provided.

Predicting Timing Behavior In Architectural Design Exploration Of Real-Time Embedded Systems, Rajeshkumar Sambandam

Masters Theses

This thesis aims at developing efficient analytical techniques to perform trade-off studies in the architectural design exploration phase of real-time embedded systems. Real-time embedded systems (RTES) have stringent timing requirements. In the process of designing such a system, a key issue is to determine if a system is able to meet all the timing requirements imposed on it, though it may prove attractive in terms of cost and performance. Traditional methods of using event-driven simulation for modern RTES are very time consuming and are not guaranteed to prove feasibility. Specifically, we identify a flexibility metric to compare various options in …

High Resolution Wavelength Modulation Spectroscopy For Precise Gaseous Characterization, Audra Michiele Bullock

Electrical & Computer Engineering Theses & Dissertations

Wavelength modulation spectroscopy is a highly sensitive, non-intrusive technique for probing gaseous species. Parameters such as velocity, density, and temperature can be measured and monitored with a high degree of precision. In addition, with the use of this technique multiple molecular species may be identified with a single laser probe. This measurement technique utilizes the well-known principles of modulation absorption spectroscopy in a novel way.

The research focuses on harmonic detection and the advantages gained by performing detection at higher harmonics, those greater than the commonly used second harmonic. We show that there is an increase in the sensitivity to …

Analysis And Testing Of Plates With Piezoelectric Sensors And Actuators, Jeffrey S. Bevan

Mechanical & Aerospace Engineering Theses & Dissertations

Piezoelectric material inherently possesses coupling between electrostatics and structural dynamics. Utilizing linear piezoelectric theory results in an intrinsically coupled pair of piezoelectric constitutive equations. One set describes the direct piezoelectric effect, where strains produce an electric field, and the other set describes the converse effect, where an applied electrical field produces strain. The purpose of this study is to compare the finite element analysis and experiments of a thin plate with bonded piezoelectric material.

Since an isotropic plate in combination with a thin piezoelectric layer constitutes a laminated composite, the classical laminate plate theory is used in the formulation to …

A Sociotechnical Systems Analysis Of The Approval Process For A Complex Public Works Proposal, James C. Pyne

Engineering Management & Systems Engineering Theses & Dissertations

This research applied sociotechnical systems theory to explore the process used by two elected bodies to decide upon adoption of a complex technical engineering proposal. The research used a modified sociotechnical systems conceptual framework that was developed by Pava (1983) for application to non-traditional work settings. Pava applied the conceptual framework to what he termed non-routine office work which is characterized by non-linear conversion flow, multiple, concurrent conversion processes and vocational separatism (Pava, 1983).

The research was designed as a multiple case study of two town councils each undertaking a decision process to approve or reject a public works proposal …

Development Of A Method For Determining The Relative Manufacturing Complexity Of Advanced Engineering Materials, Shardul Y. Pandya

Engineering Management & Systems Engineering Theses & Dissertations

The immediate adaptation of newly developed materials--with unique and highly desirable properties--is hampered by several factors, including: (1) high material cost and limited availability, (2) lack of information on them, including prior experience in their design and manufacture, immature manufacturing processes and general uncertainty in their behavior patterns, (3) unique handling issues, such as excessive manual labor, high process temperatures, toxicity, disposal problems, limited working lives, and low damage tolerance

Therefore, in spite of their significant benefits, potential users tend to shy away from the widespread use of new materials, instead preferring conventional and tested materials forms.

This dissertation is …

Three-Dimensional Aerodynamic Design Optimization Using Discrete Sensitivity Analysis And Parallel Computing, Amidu Olawale Oloso

Mechanical & Aerospace Engineering Theses & Dissertations

A hybrid automatic differentiation/incremental iterative method was implemented in the general purpose advanced computational fluid dynamics code (CFL3D Version 4.1) to yield a new code (CFL3D.ADII) that is capable of computing consistently discrete first order sensitivity derivatives for complex geometries. With the exception of unsteady problems, the new code retains all the useful features and capabilities of the original CFL3D flow analysis code. The superiority of the new code over a carefully applied method of finite-differences is demonstrated.

A coarse grain, scalable, distributed-memory, parallel version of CFL3D.ADII was developed based on "derivative stripmining". In this data-parallel approach, an identical copy …

Aerodynamic Gradient-Based Optimization Using Computational Fluid Dynamics And Discrete Sensitivities For Practical Problems, Mohagna Jayendrarai Pandya

Mechanical & Aerospace Engineering Theses & Dissertations

A gradient-based shape optimization methodology based on quasi-analytical sensitivities has been developed for practical three-dimensional aerodynamic applications. The flow analysis has been rendered by a fully implicit, finite-volume formulation of the Euler and Thin Layer Navier-Stokes (TLNS) equations. The flow equations and aerodynamic sensitivity equation have been solved using an alternating-direction-implicit (ADI) algorithm for memory efficiency. A wing geometry model based on space-surface and planform parameterization has been utilized. The present methodology and its components have been tested via several comparisons.

Initially, the inviscid flow analysis for a wing has been compared with those obtained using an unfactored, Preconditioned Conjugate …

Broadband Dynamic Modification Using Feedforward Control, Kendeas Antonis Karantonis

Mechanical & Aerospace Engineering Theses & Dissertations

The use of feedforward control for dynamic modification is relatively new to the area of structural vibration control. In this thesis the disturbance path dynamics of a flexible aluminum beam, pinned at both ends and under the influence of broadband excitation inputs, are modified through the use of feedforward control. The ideal algebraically determined feedforward control method for response cancellation is first presented. Theoretically, this compensator modifies the disturbance path dynamics to any desired behavior. This ideal algebraic approach can only be used for minimum phase systems. In non-minimum phase systems, right half s-plane plant zeros emerge as unstable poles …

Investigation Of An Alternative Technique For Measuring Turbulence In The Upper Atmosphere, Charles Patrick Leonard

Mechanical & Aerospace Engineering Theses & Dissertations

The capability of the Global Positioning System (GPS) as a tool for measuring turbulence in the upper atmosphere is presented. By studying experimental ground and flight test data, a methodology for extracting macroscale turbulence data from in situ measurements was developed.

A description of the GPS using a single nonprecision receiver is followed by data from ground and flight testing. Ground testing focused on determining the smallest turbulent scales discernible by the GPS receiver. Testing was also undertaken to compare turbulence data from the GPS with that of a simultaneously operating constant-temperature hot-wire anemometer, the conventional tool for making turbulence …

Development Of Curved-Plate Elements For The Exact Buckling Analysis Of Composite Plate Assemblies Including Transverse-Shear Effects, David Michael Mcgowan

Mechanical & Aerospace Engineering Theses & Dissertations

The analytical formulation of curved-plate non-linear equilibrium equations including transverse-shear-deformation effects is presented. The formulation uses the principle of virtual work. A unified set of non-linear strains that contains terms from both physical and tensorial strain measures is used. Linearized, perturbed equilibrium equations (stability equations) that describe the response of the plate just after buckling occurs are then derived after the application of several simplifying assumptions. These equations are then modified to allow the reference surface of the plate to be located at a distance z_c, from the centroidal surface. The implementation of the new theory into the …

An Experimental Investigation Of Bolt Preload Relaxation In Pultruded Gfrp Composite Joints, Srinivas Ravi

Mechanical & Aerospace Engineering Theses & Dissertations

Mechanically fastened joints in pultruded composites are necessary for reasons of maintenance, repair, and assembly. Pultruded composites utilize polymers as matrices and therefore are susceptible to time-dependent effects. The positive effects of increasing the clamping force in bolted joints are well known. To maintain a safe operation of the assembly a minimum clamping force must be guaranteed. But since these materials show time-dependent effects, the bolt-preload relaxes over a period of time. The present study is aimed at investigating the bolt preload relaxation. In this study 1/2 in. thick pultruded sheets were first tested under compression in the thickness direction. …

Additional Shear Wall Values For Light Weight Steel Framing (Draft), Reynaud Serrette, Jose Encalada, Georgi Hall, Brandon Matchen, Hoang Nguyen, Alexander Williams, Light Gauge Steel Research Group

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

AlSI sponsored research at Santa Clara University (Serrette, 1996) led to the development of shear values for plywood, oriented strand board (OSB), and gypswn wallboard (GWB) sheathed light weight steel framed wall assemblies. The scope of the 1996 work was, however, limited to plywood, OSB. and GWB on 0.033 in. (20 gauge) framing. To provide a wider range of design options and clarify some of the values from the 1996 test program. a new test program was initialed. The new program included the following wall assemblies: flat strap X-braced walls. steel sheathed walls, high aspect ratio walls, and walls framed …

Infrared Ellipsometry On Hexagonal And Cubic Boron Nitride Thin Films, E. Franke, H. Neumann, Mathias Schubert, T. E. Tiwald, John A. Woollam, J. Hahn

Department of Electrical and Computer Engineering: Faculty Publications

Infrared spectroscopic ellipsometry (IRSE) over the wavelength range from 700 to 3000 cm^-1 has been used to study and distinguish the microstructure of polycrystalline hexagonal and cubic boron nitride thin films deposited by magnetron sputtering onto (100) silicon. The IRSE data are sensitive to the thin-film layer structure, phase composition, and average grain c-axes orientations of the hexagonal phase. We determine the amount of cubic material in high cubic boron nitride content thin films from the infrared optical dielectric function using an effective medium approach.

Input Design For Systems Under Identification Using Indirect And Direct Methods, Marco P. Schoen

Mechanical & Aerospace Engineering Theses & Dissertations

The motivation for system identification can be manifold. In this work, the provocation to identify unknown system characteristics is derived from the control engineering point of view. That is, one intends to design a control strategy based on the identified system properties. The used system identification methods are the Open-Loop Kalman filter System Identification method (OKID) and the Closed-Loop System Identification method (CLID). It is shown that the quantitative largest error of the system identification is given by its model representation, that is the attempt to describe a system with model parameters which poses a linear relationship with the input/output …