bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial, Multibody Modeling and Vehicle Dynamics Analysis of an Interim Armored Vehicle
Authors: Letherwood Michael D. , Gunter David D.
Published: May 2008

The US Army vision, announced in October of 1999, encompasses people, readiness, and transformation. The goal of the Army vision is to transition the entire Army into a force that is strategically responsive and dominant at every point of the spectrum of operations. The transformation component will be accomplished in three ways: the Objective Force, the Legacy (current) Force, and the Interim Force. The objective force is not platform driven, but rather the focus is on achieving capabilities that will operate as a “system of systems.” As part of the Interim Force, the US Army plans to begin production of the Interim Armored Vehicle (IAV) in FY02 and field the first unit by May 2002 and complete first unit fielding by 2003 to address the current force’s operational shortfall. The intent is to get forces on the ground quickly with enough combat power to influence a potential situation, so the Army is converting six to eight combat brigades into Interim Brigade Combat Teams (IBCTs). These teams will be a rapidly deployable combat brigade task force that will be centered around the IAV (figure 1), which was recently selected during a source selection. The IAV program is a family of medium armored vehicles intended to equip the Army’s IBCTs.
Truck Driving Simulator Effectiveness
Authors: Hoskins A. , El-Gindy M. , Vance R. , Hiller N. , Goodhart C.
Published: May 2008

The Pennsylvania Truck Driving Simulator (PTDS) has been implemented in several different studies. The effectiveness of utilizing the simulator for training heavy truck operators was investigated through a study with the Pennsylvania Department of Transportation (PENNDOT). Thirty-four highway equipment operator trainees from PENNDOT completed a series of driving tasks in the simulator. The driving tasks were developed as five independent driving scenarios within the simulator each requiring different skills. Measures of driver performance included ratings from professional driving instructors and numerical records from the simulator’s recording capability. These were analyzed to determine if a) students improved their driving through completing the driving scenarios, and b) the two sets of data agreed in the assessment of driver performance. This paper presents the results of this study, which showed that students’ driving skill did improve as they completed the driving tasks. The vehicle dynamics response measurement data also largely agreed with the instructors’ evaluation.
Natural Convection in a Square Enclosure With a Partially Heated Wall Section Covered by a Blind-Like Attachment in Which There Is a Linearly Varying Heat Generation Rate
Authors: Oosthuizen Patrick H.
Published: May 2008

Natural convective heat transfer across a square enclosure with one vertical wall partially heated to a uniform high temperature and with the opposite vertical wall cooled to a lower uniform temperature has been numerically investigated. The remaining wall sections are adiabatic. The heated wall section is covered at the top and in the front by thin straight walls that offer no resistance to heat transfer. There is heat generation in vertical portion of this covering wall that is parallel to the heated wall section. The present work was undertaken as part of a wider study of the effect of window coverings on the heat transfer rate from windows, particularly for the case where the window is hotter than the room air. The situation being considered here is an approximate model of a window covered by a plane (roller) blind. In such situations there is often effectively heat generation in the blind as a result of the absorption of solar radiation. However, because of the sun angle and the effect of building overhangs, this heat generation is often not uniform along the blind. To study this effect, the case where there is a linearly varying rate of heat generation in the barrier (the “blind”) with the highest rate of heat generation at the bottom of the barrier and with no heat generation at the top has been considered. The flow in the enclosure has been assumed to be laminar and two-dimensional. Fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces. The governing equations have been written in dimensionless form and have been solved using a finite-element method. The solution has the Rayleigh number, the Prandtl number, the dimensionless distance of the barrier from the hot vertical surface, the mean dimensionless rate of heat generation in the barrier, and the dimensionless size of the heated wall section as parameters. Results have only been obtained for a Prandtl number of 0.7. The effect of the other dimensionless variables on the heat transfer rate from the hot wall section has then been numerically determined.
The Basis for a Correction for Exponential Dependence of Viscosity on Temperature for Natural Convection by an Integral Method
Authors: Burmeister Louis C.
Published: May 2008

The Nusselt number for laminar natural convection is affected by the exponential dependence on inverse absolute temperature of the viscosity of some liquids, oil being a prime example. A common means of correcting for this effect is to multiply the correlation Nu = C Ra1/4 for constant properties by a factor (μ∞/μw)n to obtain Nu = C Ra1/4(μ∞/μw)n. That there is a sound basis for the form of this corrective term is shown by employing an integral method to obtain approximate, closed-form solutions to the laminar boundary layer equations for the case of a vertical plate of specified temperature to such a liquid.
An Investigation Into the Heat Transfer and Fluid Flow Around a Circular Cylinder in Buoyancy Assisting Cross Flow
Authors: Dalton Tara , Egan Vanessa , Newport David , Davies Mark , Whelan Maurice
Published: May 2008

There is considerable interest in mixed convection heat transfer in relation to electronic cooling applications but the physics of this flow in certain situations has yet to be understood. In this paper, an investigation of the heat transfer and fluid flow around a two dimensional circular cylinder is made. The experimental configuration comprised a long heated cylinder suspended in a glass walled enclosure. The airflow within the enclosure was controlled using a baffled axial fan to give a range of low Reynolds numbers from 30 to 83. For three Grashof numbers of 2.40E+04, 3.77E+04 and 5.99E+04, the mean Nusselt number around the cylinder was measured for buoyancy assisting cross flow. Optical techniques were employed to extract the full flow and temperature fields about the cylinder. Digital Speckle Pattern Interferometry (DSPI) was employed to measure the temperature field, and Particle Image Velocimetry (PIV) for the velocity field. The presence of the assisting flow was found to stabilise a naturally oscillatory buoyant flow and led to an increase in the heat transfer coefficient over that found in natural flow.
A Study of Natural Convection in Densified Cryogenic Propellants: The Effect of Heat Transfer on Circulation Patterns
Authors: Akyuzlu K. M. , Manalo L.
Published: May 2008

A two-dimensional (radial and axial) single domain (liquid) mathematical model is adopted to investigate the development of the circulation patterns inside the liquid propellant due to heat transfer from the walls of the container and the heat and mass transfer to the vapor in the ullage. The physics based mathematical model consists of conservation of mass, momentum, and energy equations for the liquid subjected to appropriate boundary conditions at the liquid-vapor interface and variable heat flux boundary condition at the walls of the container. The density of the liquid is assumed to be temperature dependent only in the buoyancy term of the momentum equation (Boussinesq approximation). The resulting nonlinear governing equations are then solved by an implicit finite difference technique (where the pressure distribution is determined by solving the Poisson’s equation) to predict the transient temperature and velocity fields inside the propellant. The computational domain is stretched in both directions to improve the results near the walls of the container. The model is tested for a benchmark case to verify the accuracy of the numerical scheme. Finally, the model is used to conduct numerical experiments to study the effect of different heat transfer boundary conditions on the circulation patterns and the resulting thermal stratification in the densified propellant.
Flow Visualization and Air Temperature Measurements in Symmetrically Heated Vertical Channels With Adiabatic Extensions
Authors: Manca Oronzio , Musto Marilena , Naso Vincenzo
Published: May 2008

Air natural convection in a vertical channel-chimney system with the channel walls symmetrically heated at a uniform heat flux has been experimentally investigated. Flow visualization photographs and average air temperatures are presented. Some profiles of air temperature fluctuations are reported, which point out the fluid flow interactions in the chinmey. The flow visualization showed that the cold air inflow penetrating into the chimney affects the thermal performance of the channel. The improvement in the thermal performance of the channel determined by the chimney effect, for various values of the process parameters, has also been pointed out. In all investigated configurations and ranges of the process parameters the air flow in the channel was laminar. The flow in the chimney is strongly affected by the aspect ratio. Moreover, at the lower values of the expansion ratio the flow was laminar in the chimney and in its lower corner a stable vortex was noticed whereas at larger values of the expansion ratio a cold ambient air downflow worsened the thermal performance of the system. Interactions between the thermal plume arising from the channel, the vortex in the comer in the inlet chimney region and the cold air inflow yield fluctuations in the air temperature in the system. The distribution of time averaged air temperature in the cross sections validates indications given by the flow visualization in the chimney.
Chemical Equilibrium of Butane Combustion in a Perfectly Stirred Reactor: Thermodynamic – Mathematical Model
Authors: Va´squez Ricardo S. , Bula Antonio J. , Camargo Javier E.
Published: May 2008

Based on classic thermo chemistry, energy balance and the introduction of chemical equilibrium, a mathematical and thermodynamic model was developed for the combustion of butane in a perfectly stirred reactor (PSR). In order to obtain this model, it was necessary to take into account certain variables that have a strong effect on combustion such as adiabatic flame temperature, equivalence ratio, equilibrium composition, reactor pressure and the incoming temperature of the reactants (ITR). By using the mathematical model it was possible to obtain graphic solutions for adiabatic flame temperature, equilibrium composition of the different species vs equivalence ratio, composition changes as a function of pressure ratio and the ITR. The mathematical model gave reasonable results, showing values that match with those obtained using complex models. This shows that it is possible to achieve a very simple model for butane combustion by using the basic principles, and what is more important, the results present a high degree of accuracy.
Transient Analysis of Natural Convection in a Horizontal Open Ended Cavity
Authors: Andreozi Assunta , Manca Oronzio , Jaluria Yogesh
Published: May 2008

The configuration of two horizontal parallel walls can be found in many applications, such as the cooling of electronic components, solar energy systems and chemical vapor deposition systems (CVD). In the present investigation a transient numerical analysis for laminar natural convection in air between two horizontal parallel plates, with the upper plate heated at uniform heat flux and the lower one unheated, is carried out by means of the finite volume method. The model was assumed to be two-dimensional. The full two-dimensional Navier-Stokes equations together with the continuity and energy equations are solved by a numerical scheme derived from a SIMPLE-like algorithm in an H-shaped domain. Results are presented in terms of velocity and temperature profiles, wall temperature profiles and the temporal behavior of several significant variables, such as the penetration length, is reported for different Rayleigh numbers and aspect ratio values.
Experimental Measurements of an Air Conditioner Performance
Authors: Rosario Luis , Rahman Muhammad M. , Porteiro Jose L. F.
Published: May 2008

The performance of the air conditioner was tested in an extensive experimental program using the environmentally controlled chambers in a test facility. Two psychometric rooms provided constant ambient temperature and humidity conditions for a test unit using ASHRAE standard procedures [1]. The indoor and outdoor units were placed into separate environmental chambers, which provided precise temperature, humidity, and airflow conditions for simulation of various operating conditions. The first goal of the experimental program was to define the range of conditions over which the test unit should be tested. The second goal of the experimental studies was to determine the performance of the test unit under the defined conditions. All air conditioner performance data has been collected with air side instrumentation only. Experimental tests were performed using the test unit over a range of outdoor temperatures between 22.4°C (80°F) and 40.6°C (105°F) and indoor temperatures between 18.3°C (65°F) and 35°C (95°F). Analysis of the experimental data was performed by studying air conditioning parameters such as heat rejection rate qc, compressor power W, system capacity qe, and coefficient of performance COP. The analysis was accomplished with the variation of a boundary condition. The sensitivity analysis of experimental data gave expected results when compared to those shown by air conditioning units similar to our test unit.
Free Convection Thermal Interaction Between 2D Components Mounted on a Vertically Oriented PCB
Authors: Newport D. , Dalton T. , Davies M.
Published: May 2008

In this paper, measurements are presented of the temperature and velocity fields about two PCBs, with an array of five equally spaced two dimensional ribs. The ribs are two dimensional approximations of the Super Ball Grid Array (SuperBGA) package from Amkor electronics. The temperature and Nusselt number distributions are measured using Digital Moire´ Subtraction Interferometry and PIV is used to measure the velocity field. The effect of substrate conductivity is examined, and the level of thermal interaction is quantified. It is found that substrate conductivity significantly alters the induced boundary layer flow and also the recirculating vortex structure external to it. It is also found that there is a trade-off between a downstream component being heated by the thermal energy of the plume from a lower component, and cooled by the kinetic energy of that plume. The spacing to length ratio, above which the cooling effect is greater, is three for components mounted on a board with a high effective conductivity (15 W/m K). The ratio is greater than three for PCBs with lower effective conductivities. Previous work in the literature indicates a ratio greater than four for components mounted flush with an adiabatic substrate.
A Generalized Mixed Kinematic-Isotropic Hardening Plastic Model Coupled With Anisotropic Damage for Sheet Metal Forming
Authors: Chow C. L. , Yang X. J.
Published: May 2008

The paper presents a generalized mixed isotropic-kinematic hardening plastic model coupled with anisotropic damage for sheet metal forming. A nonlinear anisotropic kinematic hardening is developed. For the predication of limit strains at localized necking in stamping under complex strain history, the model and its associated damage criterion for localized necking are established and implemented into LS-DYNA3D by compiling it as a user subroutine. The finite element simulation of LS-DYNA3D based on the present model is carried out. The location of localized necking for sheet metal forming has been successfully identified.
Confined Jet Impingement Thermal Management Using Liquid Ammonia as the Working Fluid
Authors: Rahman Muhammad M. , Dontaraju Padmaja , Ponnappan Rengasamy
Published: May 2008

The focus of the study was the conjugate heat transfer during impingement of a confined liquid jet. Two numerical models of a heat transfer process with heat transmission through a fluid-solid interface have been developed. In the first case only the fluid region has been considered while in the second case the solid region has been modeled along with the fluid region as a conjugate problem. The inlet nozzle Reynolds number has been kept at values where laminar flow can be assumed in all cases. The solid-fluid interface temperature shows a strong dependence on several geometric, fluid flow, and heat transfer parameters. The Nusselt number increased with Reynolds number. For a given flow rate, a higher heat transfer coefficient was obtained with smaller slot width and lower impingement height. A higher heat transfer coefficient at the impingement location was seen at a smaller thickness, whereas a thicker plate provided a more uniform distribution of heat transfer coefficient. Compared to Mil-7808 and FC-77, ammonia provided much smaller solid-fluid interface temperature and higher heat transfer coefficient.
Effect of Boiler Feedwater Inlet Locations on the Water Circulation Characteristics in a Firetube Boiler With the Non-Symmetrically Arranged Tube Passes 3 and 4
Authors: Park Hyunjae , Bowman Anthony , Stansfield Tod , Huibregtse Brian , Wilkinson Steve , Ayala Willie
Published: May 2008

Since the furnace section of a boiler is the primary heat transfer surface for the production of vapor, the overall water circulation patterns in the boiler will be significantly influenced by the circulation patterns near the furnace area. Boiler water circulation characteristics for a newly designed 4-pass firetube boiler with the non-symmetric arrangement of tube passes 3 and 4 were investigated in the previous work [1], in which the attraction forces between 28 different temperature nodes on the furnace wall were evaluated to predict the characteristics of water circulation near the boiler furnace. It was found that various non-symmetric water circulation patterns would occur for different firing conditions. As a consequence, in this paper, the analysis methods developed in the authors’ previous work are explicitly employed to predict and improve the water circulation in a firetube boiler when 6 different boiler feedwater inlet locations (3 on the right-hand side and 3 on the left-hand side of the boiler vessel shell) are used. Each side has 3 different feedwater inlet locations below the centerline of the boiler pressure vessel along its length. Investigation of the analysis results reveals that non-symmetric water circulation patterns are not unavoidable, but improvements in the water circulation and potentially the heat transfer rate can be achieved when the boiler feed water inlet is located near the front head of the boiler pressure vessel.
Numerical Analysis of the Hydrodynamics of the Flow in an Axially Rotating Heat Pipe
Authors: Gutierrez Gustavo , Jen Tien-Chien
Published: May 2008

A numerical study is conducted on the vapor and liquid flow in a wick structure of an axially rotating heat pipe. For the vapor, the governing equations are the Navier-Stokes. For the liquid a space average of the Navier-Stokes equation is performed and a porous media model is introduced for the cross correlation that appears from the averaging process. A control volume approach on a staggered grid is used in the development of the computer program. Suction and blowing velocities are used as boundary conditions of the vapor and liquid, which are related to a local heat flux input in the evaporator section, and local heat flux output in the condenser section, respectively. The aim behind this study is the application of heat pipes in drilling applications. A triangular heat flux distribution is assumed in the evaporator due to the higher heat flux generated at the tip of the drill. A parametric study is conducted to analyze the effect of different parameters such as rotational speeds, saturation conditions, porosity, permeability and dimensions of the wick structure in the porous medium. These parameters significantly affect the pressure drop in the heat pipe and allow predicting failure conditions, which is critical in the design of heat pipes in drilling applications. The results of this study will be useful for the complete analysis of the heat pipe performance including the solution of the heat transfer on the solid wall as a conjugate problem.
CFD-Aided Design for Polysilicon Production System
Authors: Cai D. , Zheng L. L. , Zhang H. , Wan Y. , Hariharan A. V. , Chandra M.
Published: May 2008

This paper presents the CFD-aided design for polysilicon production system that utilizes an innovative technique of silicon tube-based CVD process. Virtual experiment has been conducted, which involves the development of a complex computational model capable of describing multi-component fluid flow, gas/surface chemistry, conjugate heat transfer, thermal radiation, and species transport. Theoretical analysis has been conducted and a desirable velocity regime for silane and hydrogen mixture has been found. The simulations of the flow field, temperature and species transport have been performed for various reactor geometries, operating conditions (e.g., flow rates of primary silane and secondary hydrogen gases), and heating power design. The deposition rate of polysilicon has been derived analytically as well as computationally. The effects of various conditions on deposition rate have been investigated, and optimal geometry and operating conditions have been obtained for the targeted deposition rate.
Kinetic Theory Treatment for Heat Transfer in Plasma Spraying
Authors: Zhang Q. , Jog M. A.
Published: May 2008

In plasma spraying process thermal plasma is used as a heat source to heat and melt metallic or ceramic particles. In this paper, heat transfer from a thermal plasma to a solid spherical particle has been analyzed using a kinetic theory approach. We have considered a solid particle introduced in an ionized gas made up of electrons, ions, and neutrals. Two-sided electron velocity and temperature distributions and two-sided ion velocity distributions are used. Maxwell’s transport equations are obtained by taking moments of the Boltzmann equation. The transport equations are solved with the Poisson’s equation for the self-consistent electric field. The ion and the electron number density distributions, temperature distribution, and the electric potential variation are obtained. The charged species flux to the particle surface is evaluated. Heat transport to the surface is calculated by accounting for all the modes of energy transfer including the energy deposited during electron and ion recombination at the surface. Results indicate that contribution to heat transfer from charged species recombination is substantial at high plasma temperatures.
Numerical Modeling of CO2 Laser-Heated Moving Glass Rods
Authors: Tian Weixue , Chiu Wilson K. S.
Published: May 2008

A numerical model is introduced to calculate the temperature field in moving glass rods heated by CO2 laser irradiation at a wavelength of 10.6 μm. The glass is assumed to be opaque to laser irradiation due to its high absorption coefficient at 10.6 μm. The dependence of the absorption coefficient on wavelength and temperature is considered in this model. The diffusion approximation is incorporated to analyze the radiation heat transfer in the glass rod. This approximation is valid when the glass rod is above a critical diameter. The temperature within the glass is solved using the finite volume method. The effect of laser power, laser focus, the moving speed and the radius of glass rod on the temperature distribution are studied. It is found that all these parameters have a significant effect on the temperature distribution in the glass rod. Results of simulation show that, with careful choice of these parameters, a CO2 laser may be used as a heat source for glass rod annealing or coating with stringent temperature constraints.
A Pseudo-Spectral Numerical Scheme for the Simulation of Convective Flows
Authors: Guessous Laila , Zheng Yuehong
Published: May 2008

This paper focuses on the development and validation of a pseudo-spectral numerical scheme, based on a variational formulation, for the solution of the three-dimensional, time-dependent governing equations in wall bounded forced and natural convective flows. One of the novel aspects of this numerical scheme is the use of rescaled Legendre-Lagrangian interpolants to represent the velocity and temperature in the vertical direction. These interpolants were obtained by dividing the Legendre Lagrangian interpolants of same order by the square root of the corresponding weight used for Gauss-Lobatto quadrature. By rescaling the interpolants in such a manner, the mass matrix resulting from the variational formulation becomes the identity matrix, thus simplifying the numerical algorithm. Two specific problems have been investigated as part of the validation process: Steady and unsteady channel flow driven by an external streamwise oscillating pressure gradient and Rayleigh Be´nard convection. In all cases, comparison with exact solutions and published results yield excellent agreement.
Quasi-Steady State Natural Convection in Laser Chemical Vapor Deposition With a Moving Laser Beam
Authors: Zhang Yuwen
Published: May 2008

Numerical analysis of laser chemical vapor deposition (LCVD) of Titanium Nitride by a moving laser beam is investigated numerically. The effect of natural convection due to temperature and concentration differences in the gases mixture is modeled and implemented into the thermal model of LCVD by a moving laser beam. The problem is formulated in the coordinate system that moves with the laser beam. The results show that the effect of natural convection on the shape of deposited film is very insignificant for cases with lower laser power but it becomes important when the laser power is increased.
Hybrid Numerical Method for Heat Transfer Analysis of Complex 3D Geometries
Authors: Fernando Greshan
Published: May 2008

The heat transfer analysis of systems with complex 3D geometries is usually done by numerical methods. Finite Element Method (FEM) and Finite Difference Methods (FDM) are widely used for this purpose. Complex geometries are accurately analyzed by FEM method. However, FEM solutions can be computationally inefficient for thermal problems that have high mesh densities with complex boundary conditions and variable material properties. On the other hand, Finite Difference method (FDM) is difficult to apply for complex geometric shapes. A hybrid numerical approach that combines the advantages of FDM and FEM has been integrated into a thermal simulation code. The hybrid technique has been implemented using object oriented programming techniques in a PC environment. A comparison of the computational efficiency of the two methods has been presented.
Analysis of Gas Convection and Temperature Distribution in a Rotating Wafer in a Cylindrical Lamp Heating Apparatus
Authors: Hirasawa Shigeki , Maruyama Shigenao
Published: May 2008

A three-dimensional radiation-heat-transfer analysis and a convection-heat-transfer analysis are combined in order to determine the temperature distribution in a rotating wafer in a cylindrical lamp heating apparatus for rapid thermal processing. The calculated results show that the temperature variation in the wafer increases 1.4 K by the effect of natural convection, when inlet gas velocity is 0.1 m/s during 1273 K steady-state heating of the non-rotating wafer. The effect of gas convection on the temperature variations in the wafer can be minimized when the wafer is rotating in an axisymmetric apparatus and the heating rates of the lamps are optimally controlled.
A Multi-Mechanics Approach to Computational Heat Transfer
Authors: Moen C. D. , Evans G. H. , Domino S. P. , Burns S. P.
Published: May 2008

We present a turbulent combustion code for modeling heat transfer in fires that arise in accident scenarios. The code is a component of a multi-mechanics framework and is based on a domain-decomposition, message-passing approach to parallel computing. The turbulent combustion code is based on a vertex-centered, finite-volume scheme for 3D unstructured meshes. The multi-mechanics nature of the frameworks allows us to couple to a conduction heat transfer code for conjugate heat transfer problems or a participating media radiation code for radiation transport in soot-laden flows. We describe our numerical methods, our approach to parallel computing, and the multi-mechanics frameworks. We demonstrate parallel performance using some example verification problems.
Direct Simulation Monte Carlo Calculations of Three Dimensional Non-Continuum Gas Flows
Authors: Yan Fang , Farouk Bakhtier , Johnson Jeremy
Published: May 2008

This paper describes the parallel implementation of a three-dimensional direct simulation Monte Carlo (DSMC) code using the OpenMP procedure on a shared memory multiprocessor computer. A dynamic domain decomposition is performed to maintain load balance among the threads. Performance tests are conducted to evaluate the effect of granularity on efficiency. It is shown that the parallel performance is dependent on the problem size. For larger-scale problems, better efficiency can be expected. Synchronization overhead due to data contention is reduced by re-arranging particle removal procedure. The parallel code is used to simulate flow through a rectangular channel with a high-speed moving wall (Couette flow). For high Knudsen (Kn) numbers, the Couette flow characteristics are found to be very different from their continuum counterparts. ‘Ultimate pressures’ are calculated for a wide range of Kn number flows. The variation of the ultimate pressure with Kn number is computed for given wall speed. Maximum compression ratio is obtained in the transition flow region.
Parallel Multiblock Mixed Finite Element Method for Elliptic Problems on Unstructured Grids
Authors: Pepper Darrell W. , Li Jichun
Published: May 2008

In this paper, we develop a general multiblock mixed finite element method for solving 2D and 3D elliptic problems by different unstructured grids on both serial and parallel platforms. Detailed implementations and numerical results are presented.
Parallelization of a Large Scale Hydrocarbon Pool Fire in the Uintah PSE
Authors: Rawat Rajesh , Spinti Jennifer P. , Yee Wing , Smith Philip J.
Published: May 2008

Realistic simulation of complicated systems such as large-scale pool fires requires the representation of relevant physical processes such as turbulent reacting flows, convective and radiative heat transfer, and fundamental gas-phase chemistry. Resolution of the length and time scales responsible for controlling the dynamic features of fire are also required to capture important fire physics. Resolving these length and time scales, however, requires massively parallel computations. To achieve coupling of these complicated processes in a massively parallel environment, software components that reuse physics-based, legacy fire codes (written in Fortran) are developed and integrated with Uintah, a component-based, visual Problem Solving Environment (PSE) [1]. Uintah provides the framework for large-scale parallelization for different applications. The integration of the new fire code in Uintah is built on three principles: 1) Develop different, reusable, physics-based components that can be used interchangeably and interact with other components, 2) reuse the legacy fire code as much as possible, and 3) use components developed by third parties, specifically non-linear and linear solvers designed for solving complex-flow problems. The simulation of a 10-m heptane pool fire illustrates the parallel scalability obtained with the integrated fire code. Linear scalability to 1000 processors is obtained on the SGI Origin 2000 at Los Alamos National Laboratory.
Building Energy Management: Co-Generation Coupling With Thermal Energy Storage
Authors: Khan K. H. , Rasul M. G. , Khan M. M. K.
Published: May 2008

This paper is concerned with the feasibility study and evaluation of an energy savings opportunity in buildings energy management using co-generation coupling with thermal energy storage. Both the technical and economical feasibility is presented first for the co-generation and then compared with the co-generation using thermal energy storage. On-site co-generation with double effect absorption chiller provides a potential of at least 13% peak demand reduction and about 16% savings in energy consumption. It provides an internal rate of return (IRR) greater than 21% but saving potential is limited by the low demand of co-generated chilled water within the community of the institution. Thermal energy storage coupling with co-generation offers a simple and economically more attractive approach for maximizing the utilization of co-generated chilled water and shows 23% reduction in peak demand and 21% savings in energy consumption. It provides higher IRR, greater than 25%.
Control of Position and Grasping Force With Cooperating Arms: A Feedback Linearization Approach
Authors: Oh So-Ryeok , Agrawal Sunil K.
Published: May 2008

Robotic applications require coordination of multiple manipulators. This paper discusses an approach for control of manipulators with given end-effector stiffness properties. The approach is designed for concurrent regulation of position of a work piece and grasping force applied by the manipulators on the work piece. The approach is based on input-output feedback linearization. Simulations demonstrate feasibility of the proposed control scheme.
Dynamics, Contact Motion and Control of Dual Arm Object Manipulation With Soft Rolling Fingertips
Authors: Doulgeri Zoe , Fasoulas John
Published: May 2008

In this paper a detailed derivation is made of the kinematics and dynamics of a pair of robotic fingers manipulating a rectangular object with soft fingertips that are allowed to roll along the object surface. The whole system is confined to the horizontal plane. Two contact motion models for the soft area contact are considered and it is shown that they significantly affect contact mode and type of finger rolling constraints. A discussion on contact forces and a grasp analysis at object’s equilibrium is made. Last, simple feedback control solutions that have been proposed for stabilizing the grasping and regulating the object’s posture are presented.
End Point Control of Nonlinear Flexible Manipulators With Control Constraint Using SDRE Method
Authors: Yim Woosoon , Singh Sahjendra N.
Published: May 2008

The paper treats the question of end point regulation of multi-link light-weight manipulators using the state dependent Riccati equation (SDRE) method. It is assumed that each link is flexible and deforms when maneuvered. It is well known that end point trajectory control using widely used feedback linearization technique is not possible since the system is nonminimum phase. Furthermore, control saturation is a major problem in controlling nonlinear systems. In this paper, an optimal control problem is formulated for the derivation of control law with and without control constraints on the joint torques and suboptimal control laws are designed using the SDRE method. This design approach is applicable to minimum and as well as nonminimum phase nonlinear systems. For the purpose of control, psuedo joint angles and elastic modes of each link are regulated to their equilibrium values which correspond to the target end point under gravity. Weighting matrices in the quadratic performance index provide flexibility in shaping the psuedo angle and elastic mode trajectories. In the closed-loop system, the equilibrium state is asymptotically stable, and vibration is uppressed. Simulation results are presented for a single link flexible manipulator which shows that in the closed-loop system, end point regulation is accomplished even with hard bounds on the control torque, and that the transient characteristics of the psuedo angles and elastic modes are easily shaped by the choice of the the performance criterion.
Temporal Difference Approach to Coordinated Motion Control of Cooperating Two Link Robots
Authors: Garg Devendra P. , Gulati Navneet
Published: May 2008

To perform complex manufacturing operations, two or more manipulators are made to work in concert. When robots work independently of other robots, small errors made (e.g., due to inaccuracies in modeling of the manipulator) by individual robots may be acceptable. However, when robots work together, then high precision is required. This calls for the use of adaptive controllers in order to minimize errors. This paper discusses the application of Temporal Difference Learning (TDL) method, wherein stiffness of manipulator is adapted based on the feedback obtained from force/torque sensors. In order to accomplish this, simulation was carried out by adding feedback (force and change of force) to controllers, so that required trajectory could be adhered. Normally this error (deviation from required trajectory) occurs due to non-availability of the correct values of stiffness of the system. Stiffness of system is difficult to calculate due to inherent complexities in formulating an accurate dynamic model of system. Variation in parameters, for example change of friction due to aging, change of moment of inertia due to changes in payload position and orientation, significantly affect the dynamic model of manipulator. One of the ways to achieve compliance is by updating the dynamic model of the system. The other way is to use the external control loop which provide manipulator with set-points such that the desired compliance can be achieved [1]. This paper demonstrates the appropriateness of TDL method in updating the dynamic model of the system. This updated model is then used to calculate the torques of the joints. As the process of learning converges, the function learned represents a nearly perfect model of the stiffness of the system.
The Development of Engineering Radiative Heat Transfer
Authors: Howell John R.
Published: May 2008

The history of the development of thermal radiation heat transfer is reviewed from the early studies of the characteristics of radiation through the recognition of the infrared portion of the spectrum, Maxwell’s equations, and on to Planck’s derivation of the blackbody energy spectrum and the impact of that analysis on the development of modern physics. More recent developments and applications in response to important applications in spacecraft, propulsion systems, high temperature systems, manufacturing, and contemporary microscale systems are reviewed, and the rapid development of the field during the last half of the 20th century is outlined. Present and emerging research areas are briefly reviewed.
Air Pollution Caused by Scented Candles
Authors: Barufaldi Caroline , Kepko Jon , Wong Kau-Fui Vincent
Published: May 2008

The effects of candles with respect to indoor air quality are more serious than most would first think. Candles can emit such toxins as soot and lead. The levels of soot present are very high when there are multiple carbon-carbon bonds. These levels can even be high enough to cause soot deposits throughout a house within four months. The levels of lead are high enough to cause major lead poisoning in children and can be between 10 and 36 times the allowable level permitted by the Environmental Protection Agency (EPA). Our recommendations would be for better labeling and a ban on metallic cores with greater than 0.01% lead present. Certainly when such products are exported overseas, or imported from abroad, candles with metallic cores containing more than 0.01% lead should not be allowed, and the labels should clearly state their contents. Management of technology means not importing or exporting environmental problems in the present context.
The Original “Silken Valley”: How and Why the Derwent Valley Became the Birthplace of the Industrial Revolution
Authors: Crofts John G.
Published: May 2008

The paper outlines the history of the extraction of power from the River Derwent in Derbyshire, England, a source of abundant, reliable and vigorous water flow; and how this renewable power source provided power for the industrialization of what were formerly cottage occupations. The Romans introduced Water Wheels to Britain in the 1st century, which were used in the Derwent Valley to grind grist, mine lead, power iron forges and pump water. The prototype factories of the Industrial Revolution were built here, utilizing water power technology to drive textile mills. Cotchett’s Silk Mill, built in Derby in 1702, was followed by Lombe’s Silk Mill nearby in 1717, Then followed the cotton industry, led by Arkwright and Strutt in Cromford, the first “modern” mill, with 200 hands and round-the-clock operations, in 1771. After this success, Strutt built a larger mill in 1782 at Belper, powered by eleven 21 ft diameter water wheels. Samuel Slater, apprenticed during the building of this mill, emigrated secretly to America, where he enabled the first successful U.S cotton mill to be built in Pawtucket, R.I. The skills and traditions remain in the area, in such notable companies as Rolls-Royce and the Royal Crown Derby Porcelain works.
An Assessment of the 107th U.S. Congress Energy Policy Debate in the History of Energy Use and Development in the United States
Authors: Reinecke Royce M.
Published: May 2008

The national energy policy debate in the 107th US Congress may mark a significant milestone in the development of energy use and conversion technologies in the United States. It has been said that the result of this congressional energy policy debate was an expensive statements that, despite proposed tax breaks and subsidies for everything from solar power and hybrid cars to coal and nuclear power, may accomplish little — with not much either on the supply or the demand side that’s going to make any difference to the American public. This paper provides an insider assessment of how the debate developed, what energy policy decisions were or were not made, and what the implications are for the development of energy use and conversion technologies going forward. This debate may represent the final exhaustive struggle of long-held, but misguided, ineffectual and limited-vision policies that date to the 1970s. In combination with the September 11 events, this stalemate may open the door to new, fresh, global perspectives on meeting the energy needs of people throughout the world, including in lesser developed countries such as Afghanistan. Engineers and entrepreneurs are advised to understand the seminal implications of the 107th congressional energy policy debate on future energy use and conversion technologies.
Numerical Simulation of Thermal Energy Storage in Cylindrical Cells
Authors: Ramos-Aboites Horacio , Hernandez-Guerrero Abel , Aceves Salvador M. , Lesso-Arroyo Raul
Published: May 2008

This paper presents the results of a -numerical transient model for phase change in a storage cell filled with a phase change material (PCM). Phase change occurs under the presence of natural convection. The PCM is encapsulated in a cylindrical energy storage cell. Two cases of PCM melting are analyzed, (1) the surface temperature of the bottom half of the cylindrical cell is kept at a constant temperature, which is higher than the melting temperature of the PCM, and (2) a fluid flows under the cell with an inlet temperature that is higher than the melting point of the PCM. The results show the evolution of the solid-liquid interface, isotherms and flow lines during the melting process.
History and Evolution of the Offshore Oil and Gas Industry in Southern Louisiana: Worker Perspectives
Authors: Austin Diane , McGuire Thomas
Published: May 2008

The history of the offshore oil and gas industry in the Gulf of Mexico is one of both progressive and punctuated development. New technologies, forms of work organization, and regulatory regimes have all combined over the past seventy years to influence the evolution of this industry. This paper reports early results of a multiyear, multi-team effort to document this history and its impacts on southern Louisiana. It focuses on the work of one team, applied anthropologists from the University of Arizona, to capture the history from the perspectives of the workers and local entrepreneurs who made this industry happen.
A General Analytical Approach for Defining Effectiveness in Ideal Two Fluid Heat Exchangers
Authors: Shrivastava Devashish , Ameel Tim
Published: May 2008

A general analytical development, based on the first and second laws of thermodynamics, is used to define the maximum possible heat transfer in an ideal two-fluid exchanger as well as the maximum possible temperature differences for both fluid streams. It is shown that the conventional expression for the maximum possible heat transfer in ideal two-fluid heat exchangers is a special case of the general expressions. The application of both the first and second laws of thermodynamics in defining the maximum possible heat transfer and maximum possible temperature difference provides only one expression (instead of two different expressions) for either stream which is a measure of both thermal and temperature effectiveness of the particular stream. Differences between the conventional and proposed effectiveness values are presented as functions of the capacity ratio and NTU. These data are used to demonstrate the advantages of the new definitions for maximum heat transfer and maximum temperature difference in ideal two-fluid heat exchangers.
100 Years of Oil and Gas Development: From the Marshes to Deepwater, Louisiana Has Played a Major Role in Water-Oriented Exploration and Development
Authors: Davis Donald W.
Published: May 2008

September, 2001 marked the 100th anniversary of the oil and gas business in Louisiana. Consequently, hydrocarbon exploration and development has been a vital part of Louisiana’s economy for over a century. In the latter part of the 1980s, the industry was considered dead or dying. Exploration and development had declined throughout the state. In the 1990s Louisiana’s industry was reborn in the deepwater of the northern Gulf of Mexico—a region that holds enormous potential in water depths that create unique exploration, development and production challenges. As technology changed, or was developed to meet the industry’s needs, new frontiers were explored. There was a pioneering entrepreneurial spirit that pushed the limits. Today, the frontier continues to expand and Louisiana is the beneficiary of this activity. One hundred years after the first discovery well in Louisiana, more than 250,000 oil and/or gas wells have been drilled in the state. In addition, over 4,000 structures are anchored parallel to its coast in water depths approaching two miles (3.2 km). From the uplands, to the swamps and marshes and into the deepwater of the Gulf of Mexico, Louisiana has been a leader in helping meet the Nation’s energy demands.
Analysis of Effect of Fouling on Thermodynamic Performance of Convective Heat Transfer Process Through a Duct
Authors: Wu Shuangying , Zeng Danling
Published: May 2008

Based on the first and second laws of thermodynamics simultaneously, the effect of fouling on the thermodynamic performance of convective heat transfer process through a duct with constant wall temperature and constant heat flux is investigated analytically when the flow is turbulent. A criterion evaluating the effect of fouling is defined as the entropy generation increase rate per unit heat transfer rate. The effect of Reynolds number (not considering fouling) and dimensionless inlet temperature difference and dimensionless wall heat flux on the entropy generation increase rate per unit heat transfer rate is discussed. In addition, the results with constant wall temperature are compared with that with constant wall heat flux.