Engineering Commons^™

C-Ring Strength Of Advanced Monolithic Ceramics, A. A. Wereszczak, R. J. Caspe, J. J. Swab, S. F. Duffy, E. H. Baker

Civil and Environmental Engineering Faculty Publications

Alumina, silicon carbide, silicon nitride, and zirconia are common candidate ceramics for load-bearing tubular components. To help facilitate design and reliability modeling with each ceramic, Weibull strength distributions were determined with each material using a diametrally compressed c-ring specimen in accordance with ASTM C1323. The investigated silicon nitride and zirconia were found to exhibit higher uncensored characteristic strengths than the alumina and silicon carbide. The occurrence of chamfer-located fracture initiation was problematic, and hindered the ability to generate valid design data in some of these ceramics. Fractography and stress modeling results suggest that some aspects of ASTM C1323 should be …

Effect Of Crucible Diameter Reduction On The Convection, Macrosegregation, And Dendritic Morphology During Directional Solidification Of Pb-2.2 Wt Pct Sb Alloy, Jun Chen, Surendra N. Tewari, G. Magadi, H. C. Degroh Iii

Chemical & Biomedical Engineering Faculty Publications

The Pb-2.2 wt pct Sb alloy has been directionally solidified in 1, 2-, 3-, and 7-mm-diameter crucibles with planar and dendritic liquid-solid interface morphology. For plane front solidification, the experimentally observed macrosegregation along the solidified length follows the relationship proposed by Favier.([17,18]) Application of a 0.4 T transverse magnetic field has no effect on the extent of convection. Reducing the ampoule diameter appears to decrease the extent of convection. However, extensive convection is still present even in the 1-mm-diameter crucible. An extrapolation of the observed behavior indicates that nearly diffusive transport conditions require ampoules that are about 40 mum in …

Energy Efficient Routing Protocols For Mobile Ad Hoc Networks, Chansu Yu, Ben Lee, Hee Yong Youn

Electrical and Computer Engineering Faculty Publications

Although establishing correct and efficient routes is an important design issue in mobile ad hoc networks (MANETs), a more challenging goal is to provide energy efficient routes because mobile nodes' operation time is the most critical limiting factor. This article surveys and classifies the energy-aware routing protocols proposed for MANETs. They minimize either the active communication energy required to transmit or receive packets or the inactive energy consumed when a mobile node stays idle but listens to the wireless medium for any possible communication requests from other nodes. Transmission power control approach and load distribution approach belong to the former …

Simulated Properties Of Kagomé And Tetragonal Truss Core Panels, S. Hyun, Anette M. Karlsson, S. Torquato, A. G. Evans

Mechanical Engineering Faculty Publications

The finite element method has been used to simulate the properties of panels with Kagomé and tetragonal cores under compressive and shear loading. The simulation has been performed for two different materials: a Cu-alloy with extensive strain hardening and an Al-alloy with minimal hardening. It is shown that the Kagomé core is more resistant to plastic buckling than the tetragonal core under both compression and shear. One consequence is that the Kagomé structure has the greater load capacity and a deferred susceptibility to softening. Another is that the Kagomé core is isotropic in shear: contrasting with the soft orientations exhibited …

Development And Validation Of A 3-D Model To Predict Knee Joint Loading During Dynamic Movement, Scott G. Mclean, Anne Su, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

The purpose of this study was to develop a subject-specific 3-D model of the lower
extremity to predict neuromuscular control effects on 3-D knee joint loading during movements that can potentially cause injury to the anterior cruciate ligament (ACL) in the knee. The simulation consisted of a forward dynamic 3-D musculoskeletal model of the lower extremity, scaled to represent a specific subject. Inputs of the model were the initial position and velocity of the skeletal elements, and the muscle stimulation patterns. Outputs of the model were movement and ground reaction forces, as well as resultant 3-D forces and moments acting …

Oci-Based Group Communication Support In Corba, Dongman Lee, Dukyun Nam, Hee Yong Youn, Chansu Yu

Electrical and Computer Engineering Faculty Publications

Group communication is a useful mechanism guaranteeing consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We thus propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the open communications interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We also define the group communication inter-ORB protocol (GCIOP) as a …

Kalman Filtering For Fuzzy Discrete Time Dynamic Systems, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

This paper uses Kalman filter theory to design a state estimator for noisy discrete time Takagi–Sugeno (T–S) fuzzy models. One local filter is designed for each local linear model using standard Kalman filter theory. Steady state solutions can be found for each of the local filters. Then a linear combination of the local filters is used to derive a global filter. The local filters are time-invariant, which greatly reduces the computational complexity of the global filter. The global filter is shown to be unbiased and (under certain conditions) stable. In addition, under the approximation of uncorrelatedness among the local models, …

Exotendons For Assistance Of Human Locomotion, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Background: Powered robotic exoskeletons for assistance of human locomotion are currently
under development for military and medical applications. The energy requirements for such devices are excessive, and this has become a major obstacle for practical applications. Legged locomotion in many animals, however, is very energy efficient. We propose that poly-articular elastic mechanisms are a major contributor to the economy of locomotion in such specialized animals. Consequently, it should be possible to design unpowered assistive devices that make effective use of similar mechanisms.

Methods: A passive assistive technology is presented, based on long elastic cords attached to an
exoskeleton and guided …

2003 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

M-Ary Amplitude Shift Keying Ofdm System, Fuqin Xiong

Electrical and Computer Engineering Faculty Publications

Coherent M-ary amplitude-shift keying (MASK) is proposed for use in orthogonal frequency-division multiplexing (OFDM) systems. The frequency separation between subcarriers is only 1/2T instead of 1/T. With a slightly wider bandwidth, an √M-ary ASK OFDM can achieve the same bit-error rate (BER) of M-ary quadrature amplitude modulation (QAM) OFDM and a better BER than that of M-ary phase-shift keying (MPSK) OFDM. The √M-ary ASK OFDM has the same peak-to-average-power ratio as that of the M-ary QAM OFDM. The MASK OFDM can be implemented digitally and efficiently by fast cosine transform and demodulated by inverse fast cosine transform. Comparisons show that …

A Mushy-Zone Rayleigh Number To Describe Interdendritic Convection During Directional Solidification Of Hypoeutectic Pb-Sb And Pb-Sn Alloys, Surendra N. Tewari, R. Tiwari

Chemical & Biomedical Engineering Faculty Publications

Based on measurements of the specific dendrite surface area (S-nu), fraction of interdendritic liquid (phi), and primary dendrite spacing (lambda(1)) on transverse sections in a range of directionally solidified hypoeutectic Pb-Sb and Pb-Sn alloys that were grown at thermal gradients varying from 10 to 197 K cm(-1) and growth speeds ranging from 2 to 157 mum s(-1), it is observed that S-nu = lambda(1)(-1) S*(-0.33) (3.38 - 3.29 phi + 8.85 phi(2)), where S* = D-l G(eff)/V m(1) C-o (k - 1)/k, with D-l being the solutal diffusivity in the melt, G(eff) being the effective thermal gradient, V being the …

On The Mechanical Response In A Thermal Barrier System Due To Martensitic Phase Transformation In The Bond Coat, Anette M. Karlsson

Mechanical Engineering Faculty Publications

Recentstudies have shown that Pt-aluminide—a common bond coat material inthermal barrier coatings—undergoes martensitic transformations during thermal cycling. The transformationsare associated with both large transformation strain and a strainhysteresis, leading to accumulation of a mismatch strain. Thermal barriersystems based on Pt-aluminide bond coats are susceptible to interfacialmorphological instabilities. In this study, we investigate how the cyclicmartensitic transformation influences the morphology. Two key results are: (i)the morphological instabilities are highly sensitive to the thermo-mechanical propertiesof the substrate due to the martensitic transformation; (ii) thehysteresis associated with cyclic martensitic transformation cannot drive the morphologicalinstabilities; the strains associated with the formation of the thermallygrown …

Directional Solidification And Convection In Small Diameter Crucibles, Jun Chen, P. K. Sung, D. R. Poirier, H. C. De Groh Iii

Chemical & Biomedical Engineering Faculty Publications

Pb–2.2 wt.% Sb alloy was directionally solidified in 1, 2, 3 and 7 mm diameter crucibles. Pb–Sb alloy presents a solutally unstable case. Under plane–front conditions, the resulting macrosegregation along the solidified length indicates that convection persists even in the 1 mm diameter crucible. Al–2 wt.% Cu alloy was directionally solidified because this alloy was expected to be stable with respect to convection. Nevertheless, the resulting macrosegregation pattern and the microstructure in solidified examples indicated the presence of convection. Simulations performed for both alloys show that convection persists for crucibles as small as 0.6 mm of diameter …

A Novel Method For Measuring Induction Machine Magnetizing Inductance, Ana Vladan Stankovic, Eric L. Benedict, Vinod John, Thomas A. Lipo

Electrical and Computer Engineering Faculty Publications

This paper presents a novel method for measuring the magnetizing inductance of an induction machine. The approach uses a static DC excitation technique which can be employed whenever the neutral of the machine is accessible. The proposed method measures only the magnetizing inductance and not the self inductance which normally includes the effect of the stator leakage inductance. Because this test uses a DC excitation, the iron losses in the motor are considerably reduced as well and minimally influence the measurement when compared to the traditional 60-Hz no-load test. By using the proposed method for measuring only the magnetizing inductance, …

Vibration Based Crack Detection In A Rotating Disk: Part 1—An Analytical Study, Andrew L. Gyekenyesi, Jerzy T. Sawicki, George Y. Baaklini

Mechanical Engineering Faculty Publications

This paper describes the analytical results concerning the detection of a crack in a rotating disk. The concept of the approach is based on the fact that the development of a disk crack results in a distorted strain field within the component. As a result, a minute deformation in the disk’s geometry as well as a change in the system’s center of mass occurs. Finite element analyses were conducted concerning a notched disk in order to define the sensitivity of the method. The notch was used to simulate an actual crack and will be the method utilized for upcoming experiments. …

The Displacement Of The Thermally Grown Oxide In Thermal Barrier Systems Upon Temperature Cycling, Anette M. Karlsson, J. W. Hutchinson, A. G. Evans

Mechanical Engineering Faculty Publications

Models that characterize the displacement instability of the thermally grown oxide (TGO) found in some thermal barrier systems are reviewed, consolidated and extended. It is demonstrated that the simulations are only consistent with the observations whenever the bond coat and TGO both undergo plastic deformation. The TGO yields at the peak temperature, during growth, while the bond coat yields on thermal cycling. The trends oppose. Namely, the TGO displacement is diminished by increasing the high temperature strength of the bond coat, but is increased upon increasing the TGO strength. The model rationalizes certain experimental trends, particularly the decrease in durability …

Aircraft Turbofan Engine Health Estimation Using Constrained Kalman Filtering, Daniel J. Simon, D. L. Simon

Electrical and Computer Engineering Faculty Publications

No abstract provided.

Coding, Decoding, And Recovery Of Clock Synchronization In Digital Multiplexing System, Hansheng Wang, Xiaoyi Qin, Lieguang Zeng, Fuqin Xiong

Electrical and Computer Engineering Faculty Publications

High-speed broadband digital communication networks rely on digital multiplexing technology where clock synchronization, including processing, transmission, and recovery of the clock, is the critical technique. This paper interprets the process of clock synchronization in multiplexing systems as quantizing and coding the information of clock synchronization, interprets clock justification as timing sigma-delta modulation (TΔ-ΣM), and interprets the jitter of justification as quantization error. As a result, decreasing the quantization error is equivalent to decreasing the jitter of justification. Using this theory, the paper studies the existing jitter-reducing techniques in transmitters and receivers, presents some techniques that can decrease the quantization error …

Isomorphic Strategy For Processor Allocation In K-Ary N-Cube Systems, Moonsoo Kang, Chansu Yu, Hee Yong Youn, Ben Lee, Myungchul Kim

Electrical and Computer Engineering Faculty Publications

Due to its topological generality and flexibility, the k-ary n-cube architecture has been actively researched for various applications. However, the processor allocation problem has not been adequately addressed for the k-ary n-cube architecture, even though it has been studied extensively for hypercubes and meshes. The earlier k-ary n-cube allocation schemes based on conventional slice partitioning suffer from internal fragmentation of processors. In contrast, algorithms based on job-based partitioning alleviate the fragmentation problem but require higher time complexity. This paper proposes a new allocation scheme based on isomorphic partitioning, where the processor space is partitioned into higher dimensional isomorphic subcubes. The …

Single Fiber Model Of Particle Retention In An Acoustically Driven Porous Mesh, Michael T. Grossner, Alan E. Penrod, Joanne M. Belovich, Donald L. Feke

Chemical & Biomedical Engineering Faculty Publications

A method for the capture of small particles (tens of microns in diameter) from a continuously flowing suspension has recently been reported. This technique relies on a standing acoustic wave resonating in a rectangular chamber filled with a high-porosity mesh. Particles are retained in this chamber via a complex interaction between the acoustic field and the porous mesh. Although the mesh has a pore size two orders of magnitude larger than the particle diameter, collection efficiencies of 90% have been measured. A mathematical model has been developed to understand the experimentally observed phenomena and to be able to predict filtration …

Gibbs Dividing Surface And Helium Adsorption, Sasidhar Gumma, Orhan Talu

Chemical & Biomedical Engineering Faculty Publications

All adsorption data is based on the definition of Gibbs dividing surface, which is a purely mathematical transformation. Adsorption measurements in microporous solids necessitate experimental determination of the dividing surface. An international protocol does not exist on how to perform this important measurement. Commonly, helium is assumed not to adsorb and used as a probe molecule for this measurement. Each experimentalist chooses an arbitrary set of conditions, often without even disclosing them, which adds to the confusion in adsorption literature. Here, a self-consistent method for the analysis of helium data is proposed which does not assume non-adsorbing helium …

An All-Digital Clock-Smoothing Technique—Counting-Prognostication, Xiaoyi Qin, Hansheng Wang, Lieguang Zeng, Fuqin Xiong

Electrical and Computer Engineering Faculty Publications

This article presents a novel universal all-digital clock-smoothing technique - counting-prognostication. Operation principles, performance analysis, and comparisons are given. Analysis and measurement results show that this technique can efficiently smooth jitter and wander for a wide pull-in range and pull-out range, and jitter accumulation is small. A cycle-varying counting-prognostication method, which decreases pull-in time, is also suggested.

Corp - A Method Of Concatenation And Optimization For Resource Reservation Path In Mobile Internet, Kyounghee Lee, Myungchul Kim, Samuel T. Chanson, Chansu Yu, Jonghyun Lee

Electrical and Computer Engineering Faculty Publications

Existing research related to RSVP with mobility support has mainly focused on maintaining reservation state along the routing path, which changes continuously with the movements of mobile host (MH), without much overhead and delay. However, problems such as deepening RSVP's inherent scalability problem and requiring significant changes in the existing network infrastructure have not been adequately addressed. In this paper, we propose a new approach, known as Concatenation and Optimization for Reservation Path (CORP), which addresses these issues. In CORP, each BS pre-establishes pseudo reservations to its neighboring BSs in anticipation of the MH's movement. When the MH moves into …

A Discrete Dimming Ballast For Linear Fluorescent Lamps, Haiyan Wang

ETD Archive

No abstract provided.

Frequency-Hopped Multiple-Access Communications With Noncoherent M-Ary Ofdm-Ask, A. Al-Dweik, Fuqin Xiong

Electrical and Computer Engineering Faculty Publications

A noncoherent, bandwidth-efficient modulation scheme is proposed for frequency-hopping multiple-access (FH-MA) networks. The proposed scheme is a combination of noncoherent M-ary amplitude-shift keying (NMASK) and orthogonal frequency-division multiplexing (OFDM). Using this scheme minimizes the required data bandwidth. The number of frequency slots available to the users increases significantly for a fixed spread-spectrum bandwidth (BW_SS). The effect of the multiple-access interference is reduced. Simple and accurate bit error rate expressions have been derived for FH-OFDM-MASK in additive white Gaussian noise channels and for FH-OFDM-ASK in Rayleigh fading channels.

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

Chemical & Biomedical Engineering Faculty Publications

To evaluate the accuracy of segmented k-space magnetic resonance phase velocity mapping (PVM) in quantifying aortic blood flow from through-plane velocity measurements.

Two segmented PVM schemes were evaluated, one with seven lines per segment (seg-7) and one with nine lines per segment (seg-9), in twenty patients with cardiovascular disease. A non-segmented (non-seg) PVM acquisition was also performed to provide the reference data.

There was agreement between the aortic flow curves acquired with segmented and non-segmented PVM. The calculated systolic and total flow volume per cycle from the seg-7 and the seg-9 scans correlated and agreed with the flow volumes from …

Thermomechanical Behavior Of Rotor With Rubbing, Jerzy T. Sawicki, Alberto Montilla-Bravo, Zdzislaw Gosiewski

Mechanical Engineering Faculty Publications

This article presents an analytical study of the dynamics and stability of rotors subjected to rubbing due to contact with seals, taking account of associated thermal effects. The seal interaction force acting on the shaft gives rise to a friction force, which is a source of heating and can induce so-called spiral vibrations. A mathematical model that has been developed couples the heat-conduction equation with the equations for motion of the rotor. Numerical simulations have been conducted that show the thermomechanical behavior of the rotor at various operating conditions. A procedure for analyzing the stability of multibearing rotors based on …