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2002

Cleveland State University

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Articles 1 - 25 of 25

Full-Text Articles in Engineering

The Effect Of Convection On Disorder In Primary Cellular And Dendritic Arrays, R. Trivedi, P. Mazumder, Surendra N. Tewari Dec 2002

The Effect Of Convection On Disorder In Primary Cellular And Dendritic Arrays, R. Trivedi, P. Mazumder, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

Directional solidification studies have been carried out to characterize the spatial disorder in the arrays of cells and dendrites. Different factors that cause array disorder are investigated experimentally and analyzed numerically. In addition to the disorder resulting from the fundamental selection of a range of primary spacings under given experimental conditions, a significant variation in primary spacings is shown to occur in bulk samples due to convection effects, especially at low growth velocities. The effect of convection on array disorder is examined through directional solidification studies in two different alloy systems, Pb-Sn and Al-Cu. A detailed analysis of the spacing …

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Training Fuzzy Systems With The Extended Kalman Filter, Daniel J. Simon Dec 2002

Training Fuzzy Systems With The Extended Kalman Filter, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

The generation of membership functions for fuzzy systems is a challenging problem. We show that for Mamdani-type fuzzy systems with correlation-product inference, centroid defuzzification, and triangular membership functions, optimizing the membership functions can be viewed as an identification problem for a nonlinear dynamic system. This identification problem can be solved with an extended Kalman filter. We describe the algorithm and compare it with gradient descent and with adaptive neuro-fuzzy inference system (ANFIS) based optimization of fuzzy membership functions. The methods discussed in this paper are illustrated on a fuzzy filter for motor winding current estimation, and are compared with Butterworth …

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Primary Dendrite Distribution And Disorder During Directional Solidification Of Pb-Sb Alloys, Jun Hui, R. Tiwari, X. Wu, Surendra N. Tewari, R. Trivedi Nov 2002

Primary Dendrite Distribution And Disorder During Directional Solidification Of Pb-Sb Alloys, Jun Hui, R. Tiwari, X. Wu, Surendra N. Tewari, R. Trivedi

Chemical & Biomedical Engineering Faculty Publications

Pb-2.2 wt pct Sb and Pb-5.8 wt pet Sb alloys have been directionally solidified from a single-crystal seed with its [100] orientation parallel to the growth direction, to examine the primary dendrite distribution and disorder of the dendrite arrays. The dendrite distribution and ordering have been investigated using analysis techniques such as the Gauss-amplitude fit to the frequency distribution of nearest and higher-order spacings, minimum spanning tree (MST), Voronoi polygon, and Fourier transform (FT) of the dendrite centers. Since the arrangement of dendrites is driven by the requirement to accommodate side-branch growth along the (100) directions, the FT images of …

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Compressive Properties Of Zone-Directionally Solidified Β-Nial And Its Off-Eutectic Alloys With Chromium And Tungsten, R. Asthana, R. Tiwari, Surendra N. Tewari Oct 2002

Compressive Properties Of Zone-Directionally Solidified Β-Nial And Its Off-Eutectic Alloys With Chromium And Tungsten, R. Asthana, R. Tiwari, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

The ordered intermetallic compound β-NiAl and its pseudo-binary off-eutectic alloys with 1 at.% tungsten and 9.7 at.% chromium were directionally solidified (DS) in the ‘floating-zone’ mode, and tested for compressive strength and fracture behavior in the temperature range 300–800 K. The dual-phase structures created by the DS of ternary NiAl alloys led to improvements in both the compressive strength and the ductility. The room-temperature (300 K) 0.2% compressive yield strength (CYS) of DS NiAl(W) (623 MPa) is larger than the CYS of DS NiAl(Cr) (565 MPa) and DS NiAl (435 MPa). The CYS of the three alloys dropped …

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2002 Scholars And Artists Bibliography, Michael Schwartz Library, Cleveland State University, Friends Of The Michael Schwartz Library Oct 2002

2002 Scholars And Artists Bibliography, Michael Schwartz Library, Cleveland State University, Friends Of The Michael Schwartz Library

Scholars and Artists Bibliographies

This bibliography was created for the annual Friends of the Michael Schwartz Library Scholars and Artists Reception, recognizing scholarly and creative achievements of Cleveland State University faculty, staff and emeriti

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Using The Ltpp Database In A Pavement Design Course, Norbert J. Delatte Oct 2002

Using The Ltpp Database In A Pavement Design Course, Norbert J. Delatte

Civil and Environmental Engineering Faculty Publications

The Strategic Highway Research Program Long Term Pavement Performance (LTPP) database provides considerable information about a large number of pavement test sections. The information may be easily accessed using DataPave 2.0 software, available free from the Federal Highway Administration. This software provides information on approximately 3,000 sections, with several modules for data analysis and extraction. This paper describes the integration of LTPP DataPave 2.0 software into a pavement design course. The database was used at several points throughout the course, including lessons on traffic characterization, materials, reliability, performance, and design. Twelve Texas pavement case studies were used. Each student was …

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An Intelligent System For Monitoring The Microgravity Environment Quality On-Board The International Space Station, Paul P. Lin, Kenol Jules Oct 2002

An Intelligent System For Monitoring The Microgravity Environment Quality On-Board The International Space Station, Paul P. Lin, Kenol Jules

Mechanical Engineering Faculty Publications

An intelligent system for monitoring the microgravity environment quality on-board the International Space Station is presented. The monitoring system uses a new approach combining Kohonen's self-organizing feature map, learning vector quantization, and a back propagation neural network to recognize and classify the known and unknown patterns. Finally, fuzzy logic is used to assess the level of confidence associated with each vibrating source activation detected by the system.

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Training Radial Basis Neural Networks With The Extended Kalman Filter, Daniel J. Simon Oct 2002

Training Radial Basis Neural Networks With The Extended Kalman Filter, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Radial basis function (RBF) neural networks provide attractive possibilities for solving signal processing and pattern classification problems. Several algorithms have been proposed for choosing the RBF prototypes and training the network. The selection of the RBF prototypes and the network weights can be viewed as a system identification problem. As such, this paper proposes the use of the extended Kalman filter for the learning procedure. After the user chooses how many prototypes to include in the network, the Kalman filter simultaneously solves for the prototype vectors and the weight matrix. A decoupled extended Kalman filter is then proposed in order …

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Accurate Quantification Of Steady And Pulsatile Flow With Segmented K-Space Magnetic Resonance Velocimetry, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White, George P. Chatzimavroudis Sep 2002

Accurate Quantification Of Steady And Pulsatile Flow With Segmented K-Space Magnetic Resonance Velocimetry, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White, George P. Chatzimavroudis

Chemical & Biomedical Engineering Faculty Publications

Conventional non-segmented magnetic resonance phase velocity mapping (MRPVM) is an accurate but relatively slow velocimetric technique. Therefore, the aim of this study was to evaluate the accuracy of the much faster segmented k-space MRPVM in quantifying flow. The axial velocity was measured in four straight tubes (inner diameter: 5.6–26.2 mm), using a segmented MRPVM sequence with seven lines of k-space per segment. The flow rate and flow volume were accurately quantified (errorssteady (r2=0.99) and pulsatile flow (r2=0.98), respectively. The measured velocity profiles and flow rates from the segmented sequence agreed …

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Comment On "Quadriceps Protects The Anterior Cruciate Ligament", Antonie J. Van Den Bogert Sep 2002

Comment On "Quadriceps Protects The Anterior Cruciate Ligament", Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

No abstract provided.

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Agricultural Product Loads And Warehouse Failures, Norbert J. Delatte Aug 2002

Agricultural Product Loads And Warehouse Failures, Norbert J. Delatte

Civil and Environmental Engineering Faculty Publications

Two manufactured metal building warehouses loaded with agricultural products failed in service. Inspection revealed considerable damage to the structure and the foundation. The building owner filed suit against the building supplier, the building erector, and the soils testing laboratory whose engineer had designed the foundation. The agricultural product imposed substantial outward lateral pressures on the walls of the structures. Review of the available design documents indicated that these loads had not been accounted for in design. A structural analysis revealed that elements of the structure were underdesigned for the agricultural product loads. In addition, the foundation did not have any …

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Forensics And Case Studies In Civil Engineering Education: State Of The Art, Norbert J. Delatte, Kevin L. Rens Aug 2002

Forensics And Case Studies In Civil Engineering Education: State Of The Art, Norbert J. Delatte, Kevin L. Rens

Civil and Environmental Engineering Faculty Publications

This paper reviews the state of the art in the use of forensic engineering and failure case studies in civil engineering education. The study of engineering failures can offer students valuable insights into associated technical, ethical, and professional issues. Lessons learned from failures have substantially affected civil engineering practice. For the student, study of these cases can help place design and analysis procedures into historical context and reinforce the necessity of lifelong learning. Three approaches for bringing forensics and failure case studies into the civil engineering curriculum are discussed in this paper. These are stand-alone forensic engineering or failure case …

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A Fundamental Model Of Cyclic Instabilities In Thermal Barrier Systems, Anette M. Karlsson, J. W. Hutchinson, A. G. Evans Aug 2002

A Fundamental Model Of Cyclic Instabilities In Thermal Barrier Systems, Anette M. Karlsson, J. W. Hutchinson, A. G. Evans

Mechanical Engineering Faculty Publications

Cyclic morphological instabilities in the thermally grown oxide (TGO) represent a source of failure in some thermal barrier systems. Observations and simulations have indicated that several factors interact to cause these instabilities to propagate: (i) thermal cycling; (ii) thermal expansion misfit; (iii) oxidation strain; (iv) yielding in the TGO and the bond coat; and (v) initial geometric imperfections. This study explores a fundamental understanding of the propagation phenomenon by devising a spherically symmetric model that can be solved analytically. The applicability of this model is addressed through comparison with simulations conducted for representative geometric imperfections and by analogy with the …

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Sum Normal Optimization Of Fuzzy Membership Functions, Daniel J. Simon Aug 2002

Sum Normal Optimization Of Fuzzy Membership Functions, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Given a fuzzy logic system, how can we determine the membership functions that will result in the best performance? If we constrain the membership functions to a certain shape (e.g., triangles or trapezoids) then each membership function can be parameterized by a small number of variables and the membership optimization problem can be reduced to a parameter optimization problem. This is the approach that is typically taken, but it results in membership functions that are not (in general) sum normal. That is, the resulting membership function values do not add up to one at each point in the domain. This …

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A Model Study Of Displacement Instabilities During Cyclic Oxidation, Anette M. Karlsson, C. G. Levi, A. G. Evans Apr 2002

A Model Study Of Displacement Instabilities During Cyclic Oxidation, Anette M. Karlsson, C. G. Levi, A. G. Evans

Mechanical Engineering Faculty Publications

The shape changes that occur at imperfections on the surface of an alumina-forming alloy, subject to thermal cycling, have been simulated and measured. Observations have been made by emplacing a surface groove into a FeCrAlY material. Upon thermal cycling, large shape distortions have been observed: whereas, for comparable isothermal oxidation, the shape changes are minimal. The simulations predict similar responses. Upon cycling, upward displacements (pile-up) occur around the perimeter, accompanied by downward displacements at the center. Yet, minimal displacements arise upon isothermal oxidation. To realize cyclic displacements comparable in magnitude to those found experimentally, large values of the in-plane growth …

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Cellular Array Morphology During Directional Solidification, Surendra N. Tewari, Y-Husuan Weng, G. L. Ding, R. Trivedi Apr 2002

Cellular Array Morphology During Directional Solidification, Surendra N. Tewari, Y-Husuan Weng, G. L. Ding, R. Trivedi

Chemical & Biomedical Engineering Faculty Publications

Cellular array morphology has been examined in the shallow cell, deep cell, and cell-to-dendrite transition regime in Pb-2.2 wt pct Sb and Al-4.1 wt pct Cu alloy single-crystal samples that were directionally solidified along [100]. Statistical analysis of the cellular spacing distribution on transverse sections has been carried out using minimum spanning tree (MST), Voronoi polygons, radial distribution factor, and fast Fourier transform (FFT) techniques. The frequency distribution of the number of nearest neighbors and the MST parameters suggest that the arrangement of cells may be visualized as a hexagonal tessellation with superimposed 50 pct random noise. However, the power …

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From Linear To Nonlinear Control Means: A Practical Progression, Zhiqiang Gao Apr 2002

From Linear To Nonlinear Control Means: A Practical Progression, Zhiqiang Gao

Electrical and Computer Engineering Faculty Publications

With the rapid advance of digital control hardware, it is time to take the simple but effective proportional-integral-derivative (PID) control technology to the next level of performance and robustness. For this purpose, a nonlinear PID and active disturbance rejection framework are introduced in this paper. It complements the existing theory in that (1) it actively and systematically explores the use of nonlinear control mechanisms for better performance, even for linear plants; (2) it represents a control strategy that is rather independent of mathematical models of the plants, thus achieving inherent robustness and reducing design complexity. Stability analysis, as well as …

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The Effect Of The Thermal Barrier Coating On The Displacement Instability In Thermal Barrier Systems, Anette M. Karlsson, T. Xu, A. G. Evans Mar 2002

The Effect Of The Thermal Barrier Coating On The Displacement Instability In Thermal Barrier Systems, Anette M. Karlsson, T. Xu, A. G. Evans

Mechanical Engineering Faculty Publications

Thermal barrier systems are susceptible to instability of the thermally grown oxide (TGO) at the interface between the bond coat and the thermal barrier coating (TBC). The instabilities have been linked to thermal cycling and initial geometrical imperfections, as well as to misfit strains due to both oxide growth and thermal expansion misfit. Numerical simulations are used to investigate the role of the thermo-mechanical properties of the TBC in this instability. It is found that the TBC constrains the deformation, whereupon instabilities develop preferentially in regions where crack-like imperfections either pre-exist in the TBC or are created because of the …

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A Stable Self-Tuning Fuzzy Logic Control System For Industrial Temperature Regulation, Zhiqiang Gao, Thomas A. Trautzsch, James G. Dawson Mar 2002

A Stable Self-Tuning Fuzzy Logic Control System For Industrial Temperature Regulation, Zhiqiang Gao, Thomas A. Trautzsch, James G. Dawson

Electrical and Computer Engineering Faculty Publications

A closed-loop control system incorporating fuzzy logic has been developed for a class of industrial temperature control problems. A unique fuzzy logic controller (FLC) structure with an efficient realization and a small rule base that can be easily implemented in existing industrial controllers was proposed. The potential of FLC in both software simulation and hardware test in an industrial setting was demonstrated. This includes compensating for thermo mass changes in the system, dealing with unknown and variable delays, operating at very different temperature set points without retuning, etc. It is achieved by implementing, in the FLC, a classical control strategy …

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Closure To “Another Look At The L’Ambiance Plaza Collapse,” By Rachel Martin And Norbert J. Delatte, Norbert J. Delatte Feb 2002

Closure To “Another Look At The L’Ambiance Plaza Collapse,” By Rachel Martin And Norbert J. Delatte, Norbert J. Delatte

Civil and Environmental Engineering Faculty Publications

No abstract provided.

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Response Time Is More Important Than Walking Speed For The Ability Of Older Adults To Avoid A Fall After A Trip, Antonie J. Van Den Bogert, M. J. Pavol, M. D. Grabiner Feb 2002

Response Time Is More Important Than Walking Speed For The Ability Of Older Adults To Avoid A Fall After A Trip, Antonie J. Van Den Bogert, M. J. Pavol, M. D. Grabiner

Mechanical Engineering Faculty Publications

We previously reported that the probability of an older adult recovering from a forward trip and using a “lowering” strategy increases with decreased walking velocity and faster response time. To determine the within-subject interaction of these variables we asked three questions: (1) Is the body orientation at the time that the recovery foot is lowered to the ground (“tilt angle”) critical for successful recovery? (2) Can a simple inverted pendulum model, using subject-specific walking velocity and response time as input variables, predict this body orientation, and thus success of recovery? (3) Is slower walking velocity or faster response time more …

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Heat Transfer In A Thin Liquid Film In The Presence Of Electric Field For Non-Isothermal Interfacial Condition, Rama S.R. Gorla, Jorge E. Gatica, Bahman Ghorashi, Pijarn In-Eure, Larry W. Byrd Jan 2002

Heat Transfer In A Thin Liquid Film In The Presence Of Electric Field For Non-Isothermal Interfacial Condition, Rama S.R. Gorla, Jorge E. Gatica, Bahman Ghorashi, Pijarn In-Eure, Larry W. Byrd

Chemical & Biomedical Engineering Faculty Publications

Heat transfer enhancement in an evaporating thin liquid film using the electric field under non-isothermal interfacial condition is presented. A new mathematical model subjected to van der Waals attractive forces, the capillary pressure and the electric field is developed to describe the heat transfer enhancement in the evaporating thin liquid film. The effect of an electrostatic field on the curvature of the thin film, evaporative flux, pressure gradient distribution, heat flux, and heat transfer coefficient in the thin film is presented. The results show that the electric field can enhance heat transfer in the thin liquid film significantly. In addition, …

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Ultrafast Flow Quantification With Segmented K-Space Magnetic Resonance Phase Velocity Mapping, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White, George P. Chatzimavroudis Jan 2002

Ultrafast Flow Quantification With Segmented K-Space Magnetic Resonance Phase Velocity Mapping, Haosen Zhang, Sandra S. Halliburton, James R. Moore, Orlando P. Simonetti, Paulo R. Schvartzman, Richard D. White, George P. Chatzimavroudis

Chemical & Biomedical Engineering Faculty Publications

Magnetic resonance (MR) phase-velocity mapping (PVM) is routinely being used clinically to measure blood flow velocity. Conventional nonsegmented PVM is accurate but relatively slow (3–5 min per measurement). Ultrafast k-space segmented PVM offers much shorter acquisitions (on the order of seconds instead of minutes). The aim of this study was to evaluate the accuracy of segmented PVM in quantifying flow from through-plane velocity measurements. Experiments were performed using four straight tubes (inner diameter of 5.6–26.2 mm), under a variety of steady (1.7–200 ml/s) and pulsatile (6–90 ml/cycle) flow conditions. Two different segmented PVM schemes were …

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Comparison Of Mobility Method And Mass Conservation Method In A Study Of Dynamically Loaded Journal Bearings, Biao Yu, Jerzy T. Sawicki Jan 2002

Comparison Of Mobility Method And Mass Conservation Method In A Study Of Dynamically Loaded Journal Bearings, Biao Yu, Jerzy T. Sawicki

Mechanical Engineering Faculty Publications

The inverse problem of dynamically loaded journal bearings was solved using generalized Reynolds equation coupled with a complete mass conservative cavitation boundary conditions, as outlined by the Jacobsson-Floberg and Olsson (JFO) cavitation theory. In the course of solution, the modified Thomas algorithms was employed, instead of standard Gauss±Jordan reduction method, which fully utilizes the sparse character of the system matrix, and thus greatly reduces computational time. The developed model was tested against the well-known mobility method for the case of journal bearings in a commercial reciprocating air compressor. It was found that the mobility method overestimates minimum film thickness and …

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Kalman Filtering With State Equality Constraints, Daniel J. Simon, Tien Li Chia Jan 2002

Kalman Filtering With State Equality Constraints, Daniel J. Simon, Tien Li Chia

Electrical and Computer Engineering Faculty Publications

Kalman filters are commonly used to estimate the states of a dynamic system. However, in the application of Kalman filters there is often known model or signal information that is either ignored or dealt with heuristically. For instance, constraints on state values (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. A rigorous analytic method of incorporating state equality constraints in the Kalman filter is developed. The constraints may be time varying. At each time step the unconstrained Kalman filter solution is projected onto the state …

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