Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Engineering

Discipline
Institution
Publication Year
Publication
Publication Type
File Type

Articles 1771 - 1800 of 2079

Full-Text Articles in Entire DC Network

Fatigue Effects On Manual Lifting Acceleration., Youngjoun Kim Jan 1992

Fatigue Effects On Manual Lifting Acceleration., Youngjoun Kim

LSU Historical Dissertations and Theses

The objective of this research was to study the effects of fatigue on lifting acceleration and posture caused by repetitive manual lifting. Electromyogram, oxygen consumption and heart rate were used as indices of a subject's physiological fatigue. Data were collected for a period of two hours of continuous lifting, at a rate of 4 lifts per minute using the free-style posture. A box of fixed dimensions (30cm x 30cm x 20cm) and fixed weight (15.9 Kg) was used as load. It was found that the average load acceleration increased with work duration. Peak acceleration was found to be maximum in …

Go to article

Failure Predictions In Repairable Multi-Component Systems., Woodrow Thomas Roberts Jr Jan 1992

Failure Predictions In Repairable Multi-Component Systems., Woodrow Thomas Roberts Jr

LSU Historical Dissertations and Theses

The subject of this research is the prediction of failures in repairable multi-component systems from statistical models that utilize the historical failure data for the systems. Failures occurring in repairable systems are examples of a series of discrete events which occur randomly in a continuum. Such stochastic point processes are analyzed using the statistics of event series. The Crow nonhomogenous Poisson process, NHPP, model is recognized by the reliability community as being one of the best models for repairable systems. The objective of this research is to show that the Crow NHPP model, with its overall failure predictions for a …

Go to article

Nonlinear Inelastic Finite Element Analysis Of Reinforced Concrete Structures With Emphasis On Shear And Torsion. (Volumes I And Ii)., Ananth Ramaswamy Jan 1992

Nonlinear Inelastic Finite Element Analysis Of Reinforced Concrete Structures With Emphasis On Shear And Torsion. (Volumes I And Ii)., Ananth Ramaswamy

LSU Historical Dissertations and Theses

In this study a post-cracking formulation for the analysis of reinforced concrete structures has been proposed. The secant stiffness formulation considers the following nonlinearities: effects of tension-stiffening in concrete along the reinforcing direction(s), aggregate interlock model with variable shear based on crack confining stresses, and reduction of concrete compressive strength and stiffness after cracking as a function of stresses or strains. The cracking model is capable of simulating the effects of multiple non-orthogonal cracks at a point. This total stiffness formulation treats concrete unloading and reloading along a secant path and is capable of simulating the post-peak strain softening response. …

Go to article

A Neural Network-Based Trajectory Planner For Redundant Systems Using Direct Inverse Modeling, Franklin J. Rudolph Jan 1992

A Neural Network-Based Trajectory Planner For Redundant Systems Using Direct Inverse Modeling, Franklin J. Rudolph

Doctoral Dissertations

Redundant (i.e., under-determined) systems can not be trained effectively using direct inverse modeling with supervised learning, for reasons well out-lined by Michael Jordan at MIT. There is a "loop-hole", however, in Jordan's preconditions, which seems to allow just such an architecture. A robot path planner implementing a cerebellar inspired "habituation" paradigm with such an architecture will be introduced. The system, called ARTFORMS, for "Adaptive Redundant Trajectory Formation System" uses on-line training of multiple CMACS. CMACs are locally generalizing networks, and have an a priori deterministic geometric input space mapping. These properties together with on-line learning and rapid convergence satisfy the …

Go to article

Interactive Graphics-Based Musculotendon Modeling For Reconstructive Surgery Of The Hand., Inmo Yoon Jan 1992

Interactive Graphics-Based Musculotendon Modeling For Reconstructive Surgery Of The Hand., Inmo Yoon

LSU Historical Dissertations and Theses

This research has been directed at studying and developing a prototype research and clinical Computer Aided Design (CAD) tool to be used for planning tendon paths in hand reconstructive surgery. Of equal importance is the goal of having an educational tool for teaching hand biomechanics to students of this specialty. The application of CAD to rehabilitative surgery of the hand is a new field of endeavor. There are currently no existing commercial products designed to assist the orthopedic surgeon in planning these complex procedures. Additionally, orthopedic surgeons are not trained in mechanics, kinematics, math modeling, or the use of computers. …

Go to article

Assimilation Of Organic Contaminants In Wetlands: Processes And A Conceptual Model., John Howard Pardue Jan 1992

Assimilation Of Organic Contaminants In Wetlands: Processes And A Conceptual Model., John Howard Pardue

LSU Historical Dissertations and Theses

Laboratory studies and field measurements were conducted to quantify assimilative capacity of toxic organic contaminants in freshwater wetlands. Studies were conducted for hexachlorobenzene and naphthalene in a mineral-dominated bottomland hardwood forest and an organic matter-dominated freshwater marsh. In laboratory studies, sorption of hexachlorobenzene (HCB) in wetland soil and floodwater was strongly influenced by high levels of naturally occurring dissolved organic carbon (DOC). Organic matter-dominated wetlands (e.g., marshes) demonstrated no advantage over mineral-dominated wetlands (e.g., bottomland hardwood forests) for sorption of HCB due to partitioning in this DOC phase. Over the short-term, sorption of HCB was adequately described using a three-phase …

Go to article

Plasticity-Damage Bounding Surface Model For Concrete Under Cyclic-Multiaxial Loading., Taher Mowafaq Abu-Lebdeh Jan 1992

Plasticity-Damage Bounding Surface Model For Concrete Under Cyclic-Multiaxial Loading., Taher Mowafaq Abu-Lebdeh

LSU Historical Dissertations and Theses

Concrete exhibits a significant strain-softening behavior beyond the peak stress, and moreover, the mechanism of inelastic deformation in concrete consists of both plastic slip and microcracking. Hence, a combined plasticity and damage mechanics model is proposed for modeling concrete behavior under both multiaxial monotonic and cyclic loadings. The model adopts a bounding surface concept for both plasticity and damage. The introduced plasticity bounding surface is a function of the maximum compressive strain experience by the material, while the damage bounding surface is a function of the accumulated damage parameter. By this definition, both surfaces shrink in size in the stress …

Go to article

Development Of A Technique To Determine The Temperature Dependence Of The Refractive Index Of Carbonaceous Particulates., Barry James Stagg Jan 1992

Development Of A Technique To Determine The Temperature Dependence Of The Refractive Index Of Carbonaceous Particulates., Barry James Stagg

LSU Historical Dissertations and Theses

The complex refractive index of carbonaceous particulates is an important quantity in many areas of combustion research and practical applications. This property characterizes the radiative transport in luminous flames and plays a key role in the interpretation of conventional light scattering measurements. The purpose of the present study is to develop a technique which will allow the experimental determination of the temperature dependence of the refractive indices of carbonaceous materials and provide a predictive model for the variation of the indices. A high temperature ellipsometer system is developed that allows measurements of the intensity of polarized light reflected from the …

Go to article

Modification Of The Drainmod-Creams Model To Incorporate A Nutrient Submodel., Abdul Razak Bin Saleh Jan 1992

Modification Of The Drainmod-Creams Model To Incorporate A Nutrient Submodel., Abdul Razak Bin Saleh

LSU Historical Dissertations and Theses

DRAINMOD-CREAMS model was used to simulate surface runoff and sediment loss from subsurface drained plot and non-subsurface drained plot in southern Louisiana. Seven years (1981-1987) of recorded data were used in this study. In general, the performance of the model in simulating surface runoff and sediment loss from subsurface drained plot is satisfactory. However, the DRAINMOD-CREAMS model did not simulate surface runoff and sediment loss accurately from non-subsurface drained plot. The CREAMS nutrient submodel was also tested on both plots. The CREAMS model seriously overestimates the nitrogen loss from non-subsurface drained plot. The sensitivity of the DRAINMOD-CREAMS model on erodibility …

Go to article

Modeling Three-Dimensional Groundwater Flow And Solute Transport By The Finite Element Method With Parameter Estimation., Fang Xin Yu Jan 1992

Modeling Three-Dimensional Groundwater Flow And Solute Transport By The Finite Element Method With Parameter Estimation., Fang Xin Yu

LSU Historical Dissertations and Theses

A general, systematic and improved numerical formulation for the three-dimensional (3-D) groundwater flow and solute transport problems was derived, using the finite element method. In the numerical formulation, a hidden mistake, which has appeared in many textbooks and journal papers dealing with the advective term of the general 3-D solute transport equation, was found and corrected. Some simpler and practical expressions for the leaky boundary condition, surface flux condition, and sources and sinks were proposed. To improve the conventional formulation for the time derivatives, a combination of the Galerkin method and the collocation method was developed. A more accurate scheme …

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 8, November 1991, College Of Engineering And Computer Science, Wright State University Nov 1991

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 8, November 1991, 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.

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 7, October 1991, College Of Engineering And Computer Science, Wright State University Oct 1991

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 7, October 1991, 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.

Go to article

Bs News Oct 1991

Bs News

Building Services Engineering

No abstract provided.

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 6, September 1991, College Of Engineering And Computer Science, Wright State University Sep 1991

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 6, September 1991, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, May 1991, College Of Engineering And Computer Science, Wright State University May 1991

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, May 1991, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Go to article

Bs News May 1991

Bs News

Building Services Engineering

No abstract provided.

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, April 1991, College Of Engineering And Computer Science, Wright State University Apr 1991

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, April 1991, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, March 1991, College Of Engineering And Computer Science, Wright State University Mar 1991

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, March 1991, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, February 1991, College Of Engineering And Computer Science, Wright State University Feb 1991

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, February 1991, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Go to article

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1991, College Of Engineering And Computer Science, Wright State University Jan 1991

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1991, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Go to article

An Improved Multi-Dimensional Cmac Neural Network: Receptive Field Function And Placement, Pak-Cheung Edgar An Jan 1991

An Improved Multi-Dimensional Cmac Neural Network: Receptive Field Function And Placement, Pak-Cheung Edgar An

Doctoral Dissertations

The standard CMAC has been shown to have fast learning computation as a result of modular receptive field placement, rectangular receptive field shape and a simple weight adaptation algorithm. The standard CMAC, however, suffers from slow convergence at some critical frequency due to the rectangular receptive field shape. A linearly-tapered field, which requires a uniform placement, was used in this research. The receptive field placement of the standard CMAC becomes less uniform locally for a larger receptive field width. This dissertation suggests a new field placement which is more uniform without extra computation. Results show that the slow convergence at …

Go to article

Three-Dimensional Modeling Of Reaction Injection Molding., Yu-Wen Lo Jan 1991

Three-Dimensional Modeling Of Reaction Injection Molding., Yu-Wen Lo

LSU Historical Dissertations and Theses

Since increasing more complex RIM molds are being used in industry, the goal of this research is to develop a model which can be used to predict the dynamic filling front, hot spots, and air entrapment in molds. In this research a method to simulate the RIM process by considering both the filling and curing stages in variously shaped molds for unsteady state three dimensional state cases was developed. This model can be used to predict not only the temperature and conversion changes with time but also the front position changing as a function time. Using given physical and chemical …

Go to article

A Blackboard Architecture For The Integration Of Manufacturing Systems., Calvin Michael Collins Jan 1991

A Blackboard Architecture For The Integration Of Manufacturing Systems., Calvin Michael Collins

LSU Historical Dissertations and Theses

American companies engaged in manufacturing are in the midst of adjusting to the increasingly stiff foreign competition as they attempt to satisfy the demands of expanding markets. U.S. manufacturing must continue the movement toward leaner, more streamlined production if they are to survive with the new market realities. Computerizing different aspects in the accounting, production, planning, and marketing divisions, has been central in the quest for higher productivity for four decades. Research is now centering on the integration of these systems and the goal is to integrate the accounting, planning and marketing functions of the organization with the automated manufacturing …

Go to article

A Neural Network Truth Maintenance System., Suresh Guddanti Jan 1991

A Neural Network Truth Maintenance System., Suresh Guddanti

LSU Historical Dissertations and Theses

A novel approach using Neural Networks has been developed to generate consistent labelling of facts in relation to a given set of rules. In the proposed system, facts are represented by neurons and their interconnections form the knowledge base. The Neural Network Truth Maintenance System(TMS) arrives at a valid solution provided the solution exists. A valid solution is a consistent labelling of facts. If a valid solution does not exist the network does not converge. An experimental setup was built and tested using conventional integrated circuits. The hardware design is suitable for VLSI implementation for large, real-time problems. The TMS …

Go to article

Specific Cell Adhesion And Its Application In Mixed Culture Fermentations., Yeou-Fu Hwang Jan 1991

Specific Cell Adhesion And Its Application In Mixed Culture Fermentations., Yeou-Fu Hwang

LSU Historical Dissertations and Theses

Cell adhesion mediated by bonds between receptors in the cell membrane and ligands on a solid support is referred to as specific cell adhesion. This work focused on the application of specific cell adhesion in control of mixed culture fermentations and on the development of solution methods of mathematical models for cell adhesion. Through various experimental techniques, a model two-strain mixed culture system was obtained. This system was used to explore the possibility of mixed culture control through selective adhesion of particular subpopulations. It was found that through a proper reactor design and operating procedure, the coexistence of the mixed …

Go to article

Biological Treatment Of Hazardous Waste Sludges In Suspended Growth Systems For Removal Of Benzo(A)Pyrene And Other Polynuclear Aromatics., Robert E. Marks Jan 1991

Biological Treatment Of Hazardous Waste Sludges In Suspended Growth Systems For Removal Of Benzo(A)Pyrene And Other Polynuclear Aromatics., Robert E. Marks

LSU Historical Dissertations and Theses

The scope of this research project was to develop a bioremediation process for accelerated oxidation of bioresistant hazardous waste sludges in continuous flow sludge reactors. Benzo(a)pyrene (BaP) was selected as the target compound due its strong bioresistance, highly carcinogenic nature, extremely low aqueous solubility, and extremely low allowable release limits for land disposal. BaP is often a major hazardous organic component in many hazardous waste impoundments when source wastes have originated from either petroleum refining or associated petrochemical facilities. There is evidence that the biodegradation rate of high molecular weight polynuclear aromatic hydrocarbons (PNA's) is the rate limiting step in …

Go to article

Modeling The Effect Of Shale Heterogeneities On Hazardous Waste Transport In Deep Well Disposal Systems., Seung-Whee Rhee Jan 1991

Modeling The Effect Of Shale Heterogeneities On Hazardous Waste Transport In Deep Well Disposal Systems., Seung-Whee Rhee

LSU Historical Dissertations and Theses

The transport of hazardous wastes in heterogeneous confining layers was evaluated using numerical simulations. The expected configuration of the confining layers was defined by Monte Carlo techniques assuming a binary random structure composed of pure sand and pure shale zones. Flow and solute transport in the generated configuration was determined via a finite element model. The effective permeability under saturated steady-state flow was dominated by shale permeability for higher shale fractions ($>$0.65) and by sand permeability for lower shale fraction ($<$0.4). The results agreed well with the numerical result of Desbarats (1987) and the analytical results of Dagan (1979). The effective vertical permeabilities were found to be dependent on shale size and anisotropy. Application of the techniques to a well in Jefferson Parish, Louisiana suggested that a mean advective penetration into confining layer using the injection pressure as an upper bound to the driving pressure was only 3m over 10,000 years. Transport calculations assuming a constant pressure driving force over 10,000 years suggested solute transport was controlled by hydrodynamic dispersion (dispersion + diffusion) rather than advection for higher shale fractions. Transport calculations assuming active injection for only the first 100 years suggested solute transport was controlled by diffusion for higher shale fraction. Buoyancy effects associated with salinity and temperature variations were negligible for solute transport through confining layers with a shale permeability less than 0.01 md. The results of solute transport of hazardous wastes in heterogeneous confining layers suggested that confining layers greater than 300 ft in thickness with shale fractions of greater than 0.65 and shale permeabilities of less than 0.01 md would be expected to contain injected wastes for 10,000 years.

Go to article

Radial Flow Chromatography In Compressed Pancake-Shaped Beds., Brian Keith Heft Jan 1991

Radial Flow Chromatography In Compressed Pancake-Shaped Beds., Brian Keith Heft

LSU Historical Dissertations and Theses

The separation of a methane/n-butane mixture was demonstrated using radial flow through compressed, pancake-shaped beds of fine alumina powder. The compacted stationary phase improved performance relative to an uncompressed sorbent by assuring flow uniformity through the bed, reducing band-broadening and tailing (by decreasing interstitial hold-up) and decreasing effective plate height (through an increase in the capacity ratio of the chromatograph). Dispersion was identified as the key dissipative effect in the prototype radial flow adsorber. An exact analytical solution derived for the transport equations describing such a device compared favorably with experimental data. The dispersion coefficients were found to be strong …

Go to article

Feedback Linearization Of Nonlinear Systems: Robustness And Adaptive Control., Weon Ho Kim Jan 1991

Feedback Linearization Of Nonlinear Systems: Robustness And Adaptive Control., Weon Ho Kim

LSU Historical Dissertations and Theses

Feedback linearization provides an effective means of designing nonlinear control systems. This method permits one to have an exactly equivalent linear system by using a coordinate transformation and state feedback. Once the nonlinear system is transformed to a linear system, one can proceed with well developed control technologies for linear systems. Feedback linearization is based on a model of the real system. If there is mismatch between the model and the real plant, feedback linearization does not yield an exactly linear system. The question of robustness then arises: will a controller based on the model be stable when applied to …

Go to article

Mechanism And Enhancement Of Phase Segregation In Drilling Fluids., John Marvin Griffin Jan 1991

Mechanism And Enhancement Of Phase Segregation In Drilling Fluids., John Marvin Griffin

LSU Historical Dissertations and Theses

Dewaterability of a compressible suspension can be characterized by two fundamental properties of viscoelastic networks: permeability and bulk modulus of elasticity. Time required for dewatering can be obtained from the former, while the latter can furnish the data required for predicting ultimate compaction. A method has been derived and an apparatus constructed for measurement of these two properties in a centrifugal field. The method was applied to a variety of drilling fluids and mineral suspensions. A floor-mounted laboratory centrifuge was used in this investigation. The methods developed have merit for evaluating pre-treatments prior to centrifugal dewatering. A method for quantifying …

Go to article

First Prev Next Last