Engineering Commons^™

Period Formulas For Concrete Shear Wall Buildings, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

Most seismic codes specify empirical formulas to estimate the fundamental vibration period of buildings. Evaluated first in this paper are the formulas specified in present U.S. codes using the available data on the fundamental period of buildings "measured" from their motions recorded during eight California earthquakes, starting with the 1971 San Fernando earthquake and ending with the 1994 Northridge earthquake. It is shown that current code formulas for estimating the fundamental period of concrete shear wall buildings are grossly inadequate. Subsequently, an improved formula is developed by calibrating a theoretical formula, derived using Dunkerley's method, against the measured period data …

Factors Affecting The Room-Temperature Mechanical Properties Of Ticr2-Base Laves Phase Alloys, Katherine C. Chen, Samuel M. Allen, James D. Livingston

Materials Engineering

Various effects on the room-temperature mechanical properties of TiCr₂-base alloys have been assessed in efforts to improve the toughness of Laves phase intermetallics (AB₂). Systematic studies were performed on: (i) single-phase stoichiometric and nonstoichiometric TiCr₂, (ii) TiCr₂-base ternary Laves phases, and (iii) two-phase binary alloys containing TiCr₂. In order to make quantitative comparisons among the different alloys, Vickers indentation was used to obtain hardness and fracture toughness values. Within the single-phase field, constitutional defects accounted for the compositional dependencies of properties, and may aid the synchroshear deformation process. Ternary Laves …

Water Level Sensor And Datalogger Testing And Demonstration, A. Burt, Mike Lehmkuhl, Charles M. Burt, Stuart W. Styles

BioResource and Agricultural Engineering

Electronic water level sensing equipment is becoming increasingly important for the implementation of water conservation programs in irrigation districts. A need has risen for information on costs, advantages/disadvantages, required support equipment, and required maintenance for the various options. ITRC conducted a yearlong study on water level sensors and dataloggers and produced this report.

Effects Of Supplemental Viscous Damping On Seismic Response Of Asymmetric-Plan Systems, Rakesh K. Goel

Civil and Environmental Engineering

Coupling between lateral and torsional motions may lead to much larger edge deformations in asymmetric‐plan systems compared to systems with a symmetric plan. Supplemental viscous damping has been found to be effective in reducing deformations in the symmetric‐plan system. This investigation examined how supplemental damping affects the edge deformations in asymmetric‐plan systems. First, the parameters that characterize supplemental viscous damping and its plan‐wise distribution were identified, and then the effects of these parameters on edge deformations were investigated. It was found that supplemental damping reduces edge deformations and that reductions by a factor of up three are feasible with proper …

Seismic Code Analysis Of Multi-Storey Asymmetric Buildings, Anthony P. Harasimowicz, Rakesh K. Goel

Civil and Environmental Engineering

Static torsional provisions in most seismic codes require that the lateral force at each floor level be applied at some distance from the reference centre at that floor. However, codes do not specify how to determine the locations of these centres. As a result, several different definitions of the reference centres are being used to implement the code analysis. This investigation examined how the results using various reference centres differ and which of these centres would lead to results that are in agreement with those of dynamic analysis. For this purpose three different buildings ranging form torsionally stiff to torsionally …

Determination Of Bumper Styling And Engineering Parameters To Reduce Pedestrian Leg Injuries, Peter J. Schuster, Bradley Staines

Mechanical Engineering

The European Commission is proposing legislation aimed at reducing the severity of injuries sustained by pedestrians in the event of an impact with the front-end of a motor vehicle. One aspect of this proposed legislation is reducing the pedestrian's leg injuries due to contact with the bumper and frontal surfaces of a vehicle, assessed using a 'pedestrian leg impact device,' or 'leg-form.'

This proposed legislation presents the challenge of designing a bumper system which achieves the required performance in the leg-form impact-without sacrificing the bumper's primary function of vehicle protection during low-speed impacts. The first step in meeting this challenge …

Crosstalk In Passive Matrix Polymer Led Displays, David Braun

Electrical Engineering

Passive matrix displays based on polymer and organic light-emitting diodes (LEDs) suffer from crosstalk, the emission of light from pixels other than those selected. This article explores the topic of crosstalk both with an approximate but analytic model and by means of more exact circuit simulation in order to explain the causes of crosstalk and to quantify the consequences. We conclude that crosstalk has implications for display power consumption.

Electroluminescent Device Comprising A Transparent Structured Electrode Layer Made From A Conductive Polymer, Aemilianus G. J. Staring, David Braun

Electrical Engineering

An electroluminescent (EL) device is (1) composed of polymeric LEDs comprising an active layer (7) of a conjugated polymer and a transparent polymeric electrode layer (5) having electroconductive areas (51) as electrodes. Like the active layer (7), the electrode layer (5) can be manufactured in a simple manner by spin coating. The electrode layer (5) is structured into conductive electrodes (51) by exposure to UV light. The electrodes (9) and (51) jointly form a matrix of LEDs for a display. When a flexible substrate (3) is used, a very bendable EL device is obtained.

Improved Proportional-Integral (Pi) Logic For Canal Automation, Charles M. Burt, R S. Mills, Ram Dhan Khalsa, V. C. Ruiz

BioResource and Agricultural Engineering

Successful implementation of Proportional-Integral (PI) control logic for gate automation on irrigation canals has been problematic because of difficulties in tuning the PI controllers for a wide range of flows. This research shows that successful and relatively simple tuning for upstream controllers can be accomplished if one uses the velocity form of the PI logic. The velocity form must be modified with a newly-developed Universal Factor (UF) concept, which accounts for the nonlinearity of the upstream water level response to gate movement. The UF function is unique for each check structure, and can be determined with a steady state simulation …

Influence Of Canal Geometry And Dynamics On Controllability, Theodor S. Strelkoff, Jean Luc Deltour, Charles M. Burt, Albert J. Clemmens, Jean Pierre Baume

BioResource and Agricultural Engineering

This paper presents the results of the Task Committee on Canal Automation Algorithms with regard to the influence of canal properties on the controllability of irrigation canals. While the control provided by individual algorithms was not evaluated, studies were performed to illustrate inherent hydraulic limitations—the inability of canal pools to recover rapidly from disturbances or flow perturbations. Studies were performed in nondimensional form to develop a better understanding of how pool properties influence pool response. Three such studies were performed. First, nondimensional backwater curves were developed for a range of canal conditions. The second study involved the propagation of waves …

The Restoration Of A Wwii Avenger Provides Projects For Wpi Students, Donald N. Zwiep, William W. Durgin, Nathan H. Mayo

Office of the Provost Scholarship

In 1970 WPI completely revised its traditional approach to engineering education. The resulting program, the WPI Plan, emphasized the use of projects as a distinctive process for achieving educational goals. Every student, as a degree requirement, had to successfully complete two major projects: one in a student's major field, the Major Qualifying Project (MQP) and the second, the Interactive Qualifying Project (IQP), which related science and technology to societal issues.

The IQP's related to the restoration of the WWII Avenger at Mayocraft, Inc. for the Collings Foundation in Stow, Massachusetts enabled the students working with the authors as advisors to …

Stability And Performance Of Feedback Control Systems With Time Delays, M. S. Ali, Z. K. Hou, Mohammad N. Noori

Office of the Dean (CENG) Scholarship

This paper investigates the time delay effects on the stability and performance of active feedback control systems for engineering structures. A computer algorithm is developed for stability analysis of a SDOF system with unequal delay time pair in the velocity and displacement feedback loops. It is found that there may exist multiple stable regions in the plane of the time delay pair, which contain time delays greater than the maximum allowable values obtained by previous studies. The size, shape and location of these stable and unstable regions depend on the system parameters and the feedback control gains. For systems with …

My Methanol Motorcycle, Art Maccarley

Electrical Engineering

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Markovian Decision Control For Traffic Signal Systems, Xiao-Hua Yu, Allen R. Stubberud

Electrical Engineering

Setting signals at intersections to minimize the queue length and vehicle delay time is a key goal in traffic management. In this paper, a new control strategy for a signalized traffic intersection is developed by applying Markovian decision control theory. Statistical analysis of simulation results with different arrival rates indicate the excellent potential of this approach.

Formation Of A Metastable Bcc Solid Solution And Decomposition To A C15 Laves Phase In Melt-Spun Crnb10Ti10, Katherine C. Chen, P. G. Kotula, F. Chu, Dan J. Thoma

Materials Engineering

A metastable, disordered bcc phase has been formed from the melt in a Cr-rich alloy of the Nb-Cr-Ti system, where large volume fractions of the Laves phase would develop under equilibrium solidification conditions. X-ray diffraction (XRD) studies and lattice constant determinations confirm that the melt-spun ribbons contain a bcc phase beyond its terminal solid solution limits. Solidification pathways are proposed based upon metastable and equilibrium phase diagrams. Microstructures have been studied using optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Cross-sectional TEM reveals tiny, dispersed Laves phase precipitates within the metastable bcc grains near the chill (wheel) …

Determination Of A Flexibility Range For Cellular Manufacturing Systems Under Product Mix Variations, Hamid Seifoddini, Manocher Djassemi

Industrial Technology and Packaging

One of the underlying assumptions in cellular manufacturing is that product mix is relatively stable over time. In this paper, a procedure for the sensitivity analysis of the performance of a cellular manufacturing system with respect to changes in the product mix is presented and a flexibility range representing the capability of the system in dealing with these changes is determined using simulation modelling. The simulation results in this study show that as the changes in the product mix increase the superiority of the performance of the cellular manufacturing system to the corresponding job shop system diminishes.

A New Control Strategy For A Signalized Traffic Intersection, Allen R. Stubberud, Xiao-Hua Yu

Electrical Engineering

A traffic control problem can be formulated as a decision-making problem for a stochastic dynamic system. Optimal traffic signal settings at intersections can minimize the vehicle delay time or the queue length at a stop line. In this paper, a new adaptive control strategy for signalized intersections is developed and tested by simulation. The simulation results show significant improvement over the traditional fully actuated control algorithm, especially for the case of high volume traffic demand.

Accuracy Of Irrigation Efficiency Estimates, A. J. Clemmens, Charles M. Burt

BioResource and Agricultural Engineering

Evaluation of actual irrigation system performance should rely on an accurate hydrologic water balance over the area considered. In a companion paper, water uses are categorized as consumptive or nonconsumptive, and beneficial or nonbeneficial. Real performance is based on water uses over a specified period of time, rather than observation of a single irrigation event (with associate potential, but not yet actual, consumptive and/or beneficial uses). Once the components in the water balance have been determined, it is shown that the accuracy of irrigation performance parameters can be determined from the accuracy of the components in the water balance, using …

Seismic Response Of Asymmetric Systems: Energy-Based Approach, Rakesh K. Goel

Civil and Environmental Engineering

An energy-based approach has been used to investigate the seismic behavior of code-designed asymmetric-plan systems. The systems considered in this investigation had large eccentricities in both directions, were designed for bidirectional earthquake loading, and their responses were computed with both components of ground motion acting simultaneously. The presented results demonstrate that the total input energy is about the same whether the system plan is symmetric or asymmetric. Furthermore, flexible-side elements in asymmetric- plan systems may be more vulnerable to earthquakes than the same elements in symmetric-plan systems if they are not designed to accommodate the higher hysteretic-energy demands. This observation …

Earthquake Characteristics Of Bridges With Integral Abutments, Rakesh K. Goel

Civil and Environmental Engineering

Earthquake analysis of bridges requires that the period and damping ratio be determined for each significant mode of vibration. Data on these vibration properties, identified from motions of bridges recorded during actual earthquake events, provide the most direct means of verifying and improving the current guidelines. Thus, the aim of this investigation was to measure the vibration properties of a two-span concrete bridge from its motions recorded during actual earthquake events. These data were then used to investigate how abutment participation affected the vibration properties of bridges with integral abutments. It is shown that the vibration period elongated and the …

Irrigation Performance Measures: Efficiency And Uniformity, Charles M. Burt, Albert J. Clemmens, Theodor S. Strelkoff, Kenneth H. Solomon, Ronald D. Bliesner, Leland A. Hardy, Terry A. Howell, Dean E. Eisenhauer

BioResource and Agricultural Engineering

It is essential to standardize the definitions and approaches to quantifying various irrigation performance measures. The ASCE Task Committee on Defining Irrigation Efficiency and Uniformity provides a comprehensive examination of various performance indices such as irrigation efficiency, application efficiency, irrigation sagacity, distribution uniformity, and others. Consistency is provided among different irrigation methods and different scales. Clarification of common points of confusion is provided, and methods are proposed whereby the accuracy of numerical values of the performance indicators can be assessed. This issue has two companion papers that provide more detailed information on statistical distribution uniformity and the accuracy of irrigation …

Period Formulas For Moment-Resisting Frame Buildings, Rakesh K. Goel, Anil K. Chopra

Civil and Environmental Engineering

Most seismic codes specify empirical formulas to estimate the fundamental vibration period of buildings. Evaluated first in this paper are the formulas specified in present U.S. codes using the available data on the fundamental period of buildings "measured" from their motions recorded during eight California earthquakes, starting with the 1971 San Fernando earthquake and ending with the 1994 Northridge earthquake. It is shown that, although the code formulas provide periods that are generally shorter than measured periods, these formulas can be improved to provide better correlation with the measured data. Subsequently, improved formulas for estimating the fundamental periods of reinforced …

Motion-Compensating Long-Term Memory Prediction, Thomas Wiegand, Xiaozheng Zhang, Bernd Girod

Electrical Engineering

Motion-compensating long-term memory prediction extends the spatial displacement utilized in block-based hybrid video coding by a variable time delay permitting the use of more frames than the previously decoded one for motion compensation. The long-term memory covers the decoded frames of some seconds at encoder and decoder. We investigate the influence of memory size in our motion compensation scheme and analyze the trade-off between the bit-rates spent for motion compensated prediction and residual coding. Simulation results are obtained by integrating long-term memory prediction into an H.263 codec. PSNR improvements up to 2 dB for the Foreman sequence and 1.5 dB …

Block-Based Hybrid Video Coding Using Motion-Compensated Long-Term Memory Prediction, Thomas Wiegand, Xiaozheng Zhang, Bernd Girod

Electrical Engineering

Our new approach extends the spatial displacement vector utilized in block-based hybrid video coding by a variable time delay permitting the use of more frames than the previously decoded one for motion compensation. The longterm memory covers the decoded frames of some seconds at the encoder's as well as the decoder's side. This scheme is well suited in cases of repetition in the sequence, e.g. a head is rotating back into its old position, or if the camera is shaking. However, transmission of the variable time delay requires additional bit-rate which may be prohibitive when the size of the long-term …

Orientation Relationships In The System Nb-Nbcr2, P. G. Kotula, Katherine C. Chen, Dan J. Thoma, F. Chu, T. E. Mitchell

Materials Engineering

No abstract provided.

Field Evaluation Of Ultrasonic Method For Assessing Well Seals, Nazli Yesiller, Craig H. Benson, Tuncer B. Edil

Civil and Environmental Engineering

Field tests were conducted in three boreholes using an ultrasonic testing method to evaluate its ability to assess contact between the seal and riser (casing). The ultrasonic method is used inside the riser without disturbing the riser, seal, or formation soil. The risers were 50-mm-diameter (2-inch) Schedule 40 steel pipes that are used for ground water monitoring wells. Different types of seals were placed around the risers and defects were purposely introduced in the seals to test the ultrasonic method. The ultrasonic response changed as the neat-cement seals cured or hydration of the bentonite seals changed. When adequate moisture was …

Studying Initiation And Growth Of Shear Cracks In Reinforced Concrete Beams Using Full-Field Digital Imaging, Daniel C. Jansen, Sokhwan Choi, Surendra P. Shah

Civil and Environmental Engineering

The mechanisms which lead to shear failure of longitudinally reinforced concrete beams are complex and often misunderstood. In this paper, a combination of a special closed loop test technique and machine vision are applied to tests on two reinforced concrete beams failing in shear: one made of normal strength concrete and the second of high strength concrete. To control the progression of the shear crack, a closed-loop test technique was devised and employed such that the crack propagation was stable even during the post peak. To locate the crack and to measure the crack displacements, machine vision, a nondestructive measuring …

Drip Irrigation Technology: A Resource Management Tool For Farmers, John C. Roberts, Stuart W. Styles

BioResource and Agricultural Engineering

No abstract provided.

Improved Biquad Structures Using Double-Output Transconductance Blocks For Tunable Continuous-Time Filters, Vladimir I. Prodanov, Micheal M. Green

Electrical Engineering

A family of g_m −C biquad structures is derived. These biquads require only a pair of grounded capacitors and three transconductors. It is shown that a pair of complex zeros can be realized simply by replicating the output stage of the transconductance block, thereby constructing a second output current that is proportional to the original output current. Although these biquad structures are very compact, they allow independent programming of the filter’s center frequency and Q. IC simulations and measurements are presented using a fifth-order tunable filter as an example.

Model Of Flexural Fatigue Damage Accumulation For Cortical Bone, L. V. Griffin, J. C. Gibeling, R. B. Martin, V. A. Gibson, S. M. Stover

Biomedical Engineering

Analytical models that predict modulus degradation in cortical bone subjected to uniaxial fatigue loading in tension and compression are presented. On the basis of experimental observations, damage was modeled as self-limiting for tension but not for compression. These mechanistic uniaxial damage models were then developed into a model for flexural fatigue of cortical bone based on laminated beam theory. The unknown coefficients in the uniaxial damage models were obtained by successfully fitting the resulting equations to uniaxial fatigue data from the literature on human cortical bone in tension and compression. Then, the predictions of the flexural model for the behavior …