Engineering Commons^™

Reduced Bandwidth For Remote Vehicle Operations, Timothy E. Noell, Fred W. Depiero

Electrical Engineering

Oak Ridge National Laboratory staff have developed a video compression system for low-bandwidth remote operations. The objective is to provide real-time video at data rates comparable to available tactical radio links, typically 16 to 64 thousand bits per second (kbps), while maintaining sufficient quality to achieve mission objectives. The system supports both continuous lossy transmission of black and white (gray scale) video for remote driving and progressive lossless transmission of black and white images for remote automatic target acquisition. The average data rate of the resulting bit stream is 64 kbps. This system has been demonstrated to provide video of …

A Technical Approach To Groundwater Contamination Problems, Jacqueline C. Burton, Catherine Leser, Candace M. Rose

United States Department of Energy: Publications

Argonne National Laboratory has been performing technical investigations at sites in Nebraska and Kansas that have identified groundwater contamination by carbon tetrachloride. This comprehensive program will ultimately provide the affected communities with safe drinking water. The first step in the program is to evaluate the available data and identify sites that will require an Alternate Water Supply Study (AWSS). The objective of the AWSS is to identify options for providing a safe drinking water supply to all users, in compliance with the Safe Drinking Water Act. The AWSS consists of an engineering and cost evaluation followed by implementation of the …

Brittle Compressive Failure Of Salt-Water Columnar Ice Under Biaxial Loading, T. R. Smith, E. M. Schulson

Dartmouth Scholarship

The brittle failure of saline columnar ice was investigated under biaxial compression at and −10° and −40°C over the range 0 ≤ R A < 1 where R A is the ratio of the intermediate to major principal compressive stress. The major principal stress and the intermediate (confining) stress were orthogonal to the columnar axes (type-A confinement); both stresses and the c-axes of the grains were co-planar. The results confirm earlier work by Hausier (1981) and Timco and Frederking (1983, 1986) on saline ice and follow similar behavior to fresh-water columnar ice found by Smith and Schulson (1993) and Frederking (1977). Failure stress and failure mode are sensitive to the confinement and two regimes of behavior are found: the failure stress first rapidly increases with R A in the range 0 ≤ R A < R T and then tends to decrease for R A > R t. The transition stress ratio, R t changes from ≈0.2 at −10°C to ≈0.1 at −40°C. The failure mode changes from axial splitting to shear faulting in the loading plane for 0 < R A < R t. Above R t failure changes to a combined mode of splitting across the columns and shear faulting out of the loading plane. The failure-stress envelope is of a truncated Coulomb-type. Damage studies show wing cracks and local fragmentation of grains involving the brine pockets. The results are explained in terms of Coulombic sliding and Hertzian crack mechanics.

Scattering Of A Light Beam From Waves At An Air-Sea Interface, Donald D. Duncan, W. H. Carter

Electrical and Computer Engineering Faculty Publications and Presentations

The authors report a new theory that describes the scattering of an upward propagating laser beam from the sea through the air-sea interface in the presence of sea waves. The sea is assumed to be a uniform dielectric and conventional scattering theory is employed by using a modification to the first Born approximation that permits treatment of surface refraction phenomena. Methods of statistical radiometry are also used in a new manner by assuming that the surface scattering function for the sea waves can be treated by a quasi-homogeneous source model to calculate the second-order correlation functions for the partially coherent …

Vibration Suppression Of Beam Structures Traversed By Multiple Moving Loads Using A Damped Absorber, Y.H. Lin, C.H. Cho

Journal of Marine Science and Technology–Taiwan

This paper deals with the dynamic analysis of a simply supported beam subjected to multiple discrete and distributed moving loads. Resonant vibration is observed for the support beam traversed by multiple discrete moving loads. A practical scheme is applied to reduce the excessive beam vibration to an acceptable range by using a damped absorber attached at the beam center. Lagrange's equation is used to formulated the system governing equation and Laplace transformation is applied to derive the dynamic responses for both the beam and the absorber, Various design parameters, such as the mass ratio, the tuning ratio, and the damping …

Pitting Of Fe-Mn-Al Alloys In Nacl Solution, M Ruscak, T.P Perng

Journal of Marine Science and Technology–Taiwan

the increase of ferrite content. However, the nearly ferritic alloy showed much better passivation behavior, presumably due to the addition of 6% Cr.In aerated solution, no or very small passive region was observed. From the immersion test, the general corrosion was found to be minor. Pitting corrosion was the primary corrosion except for the ferritic alloy. The pits were found more frequently in the ferrite phase or at the interface between the ferrite and austenite phases.

Dehumidification Of Air Flowing In The Entrance Region Of A Channel, R.H. Yeh, W.H. Huang

Journal of Marine Science and Technology–Taiwan

The heat transfer and dehumidifying characteristics in the entrance region of the parallel plates are studied. Two-dimensional boundary layer equations are solved numerically to obtain the mass concentration for the air-vapor mixture in the inlet of a channel. A simple experiment is conducted to verify the theory. The ratio of the flow length to plate spacing is chosen to be 20/3. It shows that the average total and mass transfer colburn j-factors obtained from experimental data are higher than those of numerical analysis. Finally, the relationships between experimental data and numerical results are acquired to facilitate the prospective design of …

Breaking Wave Spectrum And Set-Down Set-Up In Shallow Water, W.H. Yang

Journal of Marine Science and Technology–Taiwan

To study the mean water surface in the shallow water, it is necessary to compute the wave set-up and set-down of random waves on the surf zone. Therefore, the breaking wave spectra and radiation stress must be calculated from a wide-band breaking wave model. In this study, we extend the breaking wave spectrum model (Yang, 1991) by using the Wallops spectrum in the deep water. The Wallops spectrum is based on wave dynamics theoretical analysis and no empirical coefficients to be determined by the users. It also contents correct energy (Huang et al., 1981). The breaking wave spectra, radiation stress, …

Identification Of Whirling Motions By Phase Unwrapping Technique, Rong-Juin Shyu

Journal of Marine Science and Technology–Taiwan

A method for identifying the whirling motion of a rotating shaft has been developed. This method is based on the phase unwrapping of two strain gages' signals. These two stain gages are being attached ninety degrees apart onto the rotating shaft thus observe the shaft's motion in a rotating coordinate with speed the same as that of the shaft. With such arrangement of the strain gages, the whirling motions of the shaft can be identified provided that the rotation speed of the shaft is known. These whirling motions include forward whirl and backward whirl. Equations are given to show how …

Effects Of Anisotropy On The Hydrogen Induced Fatigue Crack Propagation Of A Banded Ferrite/Pearlite Steel, L. Tau, S.L.I. Chan, C.S. Shint

Journal of Marine Science and Technology–Taiwan

The fatigue crack propagation (FCP) properties of AISI 4130 steel plates with a ferrite/pearlite (F/P) banded structure were evaluated both in air and electrolytic hydrogen charging environments. To understand the combined effects of hydrogen, directions of banding and elongated non-metallic inclusions on the FCP, specimens with six different orien- tations relative to the rolling direction were sampled and charged with hydrogen. When tested in air, the result reveals that the crack plane as related to the direction of banding, and the local stress concentration induced by elongated inclusions, largely affected the FCP rate. It also shows that the relative dominance …

Second Law Analysis On Ejection Cooling System, S.P. Liaw, Y.H. Chang

Journal of Marine Science and Technology–Taiwan

Ejection cooling system is analyzed by the second law of thermodynamics in this study. It is mainly consisted of a boiler, an ejector, an expansion device, a condenser, and an evaporator. Special focus is stressed on the variation of exergy in each component. The working refrigerant received exergy from boiler and pump and cons umed in other parts of the system. The coefficients of performance based on both the first and the second laws are computed respectively and thus the changes of energy and exergy in each component of the system can be readily understood. In addition, the boiler temperature, …

Aluminum Electrodeposition From Room Temperature Molten Alcl3-Bpc Salt Bath, C.C. Yang, C.P. Chang

Journal of Marine Science and Technology–Taiwan

The characteristics of aluminum electrodeposited layer from an ambient temperature molten salt were discussed in this study. The experimental results indicated that it is possible to carry out aluminum electrodeposition on the surface of brass and stainless steel when binary AlCI3-8P C molten electrolysis were used. The morphology of the components, characteristics and images can be detected by SEM, Auger Analysis, X-ray diffraction analysis and electrochemical polarization curves. The denser and more adhesive electrodeposited aluminum layer can be achieved by chosing proper electrolyte components (AlCI3: BPC-acidic salt bath), current forms (D.C./pulse), current density, electrolytic time and other pretreatment. In addition, …

Numerical Study Of Spray Flame Characteristics, C.Y. Lin

Journal of Marine Science and Technology–Taiwan

A numerical method was considered to calculate spray flame structure and emissions characteristics. The turbulence fluctuation was predicted using k-e-g and algebraic mixing-length-hypothesis (mlh) turbulence models. The numerical method was evaluated using a set of available experimental data. It is shown that this theoretical model predicts the data well in the near nozzle region and the predictions improve quantitatively along the axial distance. In comparing the turbulence models, the k-e-g model provides a better result for the varying-density flow of spray combustion.

Analysis And Simulation Of Solidification For Phase Change Materials In A Cylindrical Container, H.C. Tien, J.S. Chang

Journal of Marine Science and Technology–Taiwan

The objective of this paper is to study the solidification problem of the phase change materials (PCM) in a thick-walled cylindrical container. Through varying each controlling parameter such as the thermophysical properties of wall (mold), wall thickness, aspect ratio of the container, initial temperature of PCM and the external cooling conditions, etc., the effect of each parameter on the solidification process is shown clearly. By knowing how a thick wall interacts with such a phase change phenomenon, it is therefore possible to well control the solidification process and also to improve the solid structure formed. In this study, convective boundary …

Formation Of Amorphous Cu-Zr Alloy Powder By Mechanical Alloying, T.R. Chen, P.Y. Lee

Journal of Marine Science and Technology–Taiwan

Amorphous Cux Zr100-x alloy powder has been synthesized in the range 20 ≦ x ≦ 80 by mechanical alloying mixtures of Cu and Zr powders. This range is larger than amorphous alloys produced by the vaporquenching technique. A mixture of amorphous and crystalline phases formed at the compositions of Cu10Zr90 and Cu90Zr10. Amorphous CuxZr100-x alloy powder also has been synthesized in the range 20 ≦ X ≦ 60 by mechanical alloying mixtures of intermetallic compound Cu9Zr2 and CuZr2 powders. The temperature and activation energy for crystallization of the MA Cu-Zr amorphous powders are higher than that for vaporquenched samples. The …

The Naval Reserve Civil Engineer Corps Environmental Engineering Program, William A. Heine, Samuel A. Vigil

Civil and Environmental Engineering

The Navy is engaged in a national effort to bring its shore facilities into compliance with all applicable local, state, and federal environmental regulations. This work is being completed by civil service employees, consultants, and contractors under the supervision of Navy Civil Engineer Corps officers. To supplement these active duty and civilian resources, the Reserve Division of the Naval Facilities Engineering Command (RDNAVFAC) has identified Reserve officers with substantial environmental engineering skills who are being assigned to assist Navy shore activities all over the world in this essential task. The Naval Reserve Civil Engineer Corps (CEC) is composed of over …

Predicting Seepage Of Leachate From The St. Johns Landfill To Ground And Surface Water Systems, Kevin A. Schock

Dissertations and Theses

Determination of the vertical and horizontal groundwater hydraulic gradient within a landfill is the first step in determining the potential of groundwater contamination from the landfill leachate. The length of a study and the frequency at which measurements are recorded can greatly affect the description of the local groundwater environment. A more comprehensive analysis can be preformed for longer periods of study and greater measurement frequency. The intent of this study was to install a continuous groundwater level monitoring system around the st. Johns Landfill for a minimum study length of one year. This would allow a more thorough study …

Waveform Estimation With Jitter Noise By Pseudo Symmetrical Probability Density Function, Wei-Da Hao

Dissertations and Theses

A new method for solving jitter noise in estimating high frequency waveform is proposed. It reduces the bias of the estimation in those points where all the other methods fail to achieve. It provides preliminary models for estimating percentiles in Normal, Exponential probability density function. Based on the model for Normal probability density function, a model for any probability density function is derived. The resulting percentiles, in turn, are used as estimates for the amplitude of the waveform. Simulation results show us with satisfactory accuracy.

Performance Analysis Of A Hierarchical, Cache-Coherent, Shared Memory Based, Multi-Processor System, Raman Nayyar

Dissertations and Theses

We have conducted a performance analysis of a large scale multiprocessor system based on shared buses organized in a hierarchical fashion and employing an easy to implement snoopy cache protocol. · This arrangement, named TREEBUS [ 5], presents a logical extension path for multiprocessor systems based on a single shared bus whose scalability is limited by the available system bus bandwidth [26]. The multiple, independent, hierarchical buses overcome the bus bandwidth limitation and the architecture can scale to relatively large sizes. We have developed an easy to use, reasonably accurate and computationally efficient analytic model for analyzing the performance of …

Measurement Techniques For Noise Figure And Gain Of Bipolar Transistors, Wayne Kan Jung

Dissertations and Theses

First, the concepts of reflection coefficients, s-parameters, Smith chart, noise figure, and available power gain will be introduced. This lays out the foundation for the presentation of techniques on measuring noise figure and gain of high speed bipolar junction transistors. Noise sources in a bipolar junction transistor and an equivalent circuit including these noise sources will be presented. The process of determining the noise parameters of a transistor will also be discussed. A Pascal program and several TEKSPICE scripts are developed to calculate the stability, available power gain, and noise figure circles. Finally, these circles are plotted on a Smith …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 6, June 1993, 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.

Acuta Enews June 1993, Vol. 22, No. 6

ACUTA Newsletters

In This Issue

Telemedicine

Vancouver Review

Economy at Turning Point

Yale Meridian Upgrade

Executive Director's Message

Field Trip Report: To View Effect Of An Earthquake That Happened Almost 200 Years Ago, David Stewart

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Calibrated Dynamic Response Analysis Of Stafford Dam, L. H. Mejia, R. W. Boulanger

International Conference on Case Histories in Geotechnical Engineering

Stafford Dam, an approximately 79-ft high compacted earthfill founded on stream alluvium approximately 40 feet thick, was shaken by the 1989 Lorna Prieta Earthquake. Records of the earthquake motions were obtained from seismographs located at the dam crest and at the right abutment on rock. Two-dimensional dynamic finite element analyses were performed to calibrate a model of the dam using the recorded motions. Excellent agreement between the recorded and calculated response was obtained by appropriate adjustments to material parameters based on shear wave velocity measurements. Various deconvolution methods for obtaining input bedrock motions to calculate the dam response are discussed.

Seismic Failure Of Barahona Tailings Dam, J. H. Troncoso, A. Vergara, A. Avendaño

International Conference on Case Histories in Geotechnical Engineering

The seismic failure of Barahona Tailings Dam has been analyzed. Causes of failure were decrease of the shear strength of the slimes and large displacements and breaching of the sand dikes. The dikes were partially founded on the unconsolidated slimes because the dam was built by the upstream method. Liquefied tailings flowed violently down the courses of Barahona creek and Cachapoal River causing heavy destruction over a 50 km long path. It is concluded that the upstream method of construction of tailings dams should not be encouraged in seismic zones; however, it could be considered as an alternative solution, provided …

Failures Of Quay Walls During Chilean Earthquake Of March 1985, P. Ortigosa, E. Retamal, R. V. Whitman

International Conference on Case Histories in Geotechnical Engineering

Extensive damage took place in the quay walls in the Ports of Valparaíso and San Antonio during the Chilean earthquake of March 1985. Different types of retaining structures such as gravity retaining walls built with concrete blocks, sheetpiles and decks on vertical piles were subjected to large shaking ranging from 0.3 - 0.45g at Valparaíso Port to more than 0.6g at San Antonio. Some of the retaining structures collapsed and others behave quite well. In addition, some liquefaction and settlements in the sandy fill below the yards did occur at San Antonio, along with permanent displacements in the fill slope …

Analyzing Man-Made Vibrations, Diagnostics And Monitoring, M. R. Svinkin

International Conference on Case Histories in Geotechnical Engineering

Machine foundation and construction vibrations ate main industrial man-made vibrating sources. Eight presented case histories are divided on two groups: machine foundation oscillations and seismic effect of man-made vibrations. There is the attempt in this paper to suggest a guideline for determination the causes of arisen perceptible machine foundation vibrations. Some case histories are described shortly using the following set-up: arisen problem, field investigation and measurements, the suggested solution, the performance, and final results. Others case histories are elaborated in details.

Construction Of Pedestrian Tunnels, Essex Junction, Vt, B. F. Townsend, A. D. Walker

International Conference on Case Histories in Geotechnical Engineering

A combination of innovative tunnel engineering concepts and ground improvement technologies are described as applied to an IBM facility in Vermont, with emphasis on the geotechnical aspects of the construction. By this approach, emergency access and egress tunnels were built through difficult soils beneath the slab on grade of a vibration sensitive manufacturing building, with minimal disruption to daily operations.

General Report Session No. 6: Case Histories Of Geotechnical Engineering And Rock Engineering, Charles J. Haas

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Soft Clay Ground Improvement Of Ningbo International Airport, X. R. Zhu, Q. Y. Pan, K. H. Xie

International Conference on Case Histories in Geotechnical Engineering

Ningbo International Airport is built on the soft clay ground first in China. It has a runway 3,000m in length and 45m in width. The thickness of soft clay is greater than 32m. The calculating consolidation settlement is 0. 48m, far beyond to allowable limit. The soft clay ground is improved by wick drain and surcharge precompression. The airport has been put in service since July, 1990. The process and the results of a full scale embankment test, the ground improvement and the settlement observation are described. The influence of the smear and the well resistance of the wick drain …