bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of EC2000 Criteria 3 (a)-(k) Program Outcomes
Authors: Abu-Mulaweh H. I.
Published: April 2008

A comprehensive assessment process for EC2000 Criterion 3 (a)-(k) program outcomes of the mechanical engineering program at Indiana University-Purdue University Fort Wayne (IPFW) is presented. This assessment process is a part of an assessment plan that was developed by the author with some feedback from the faculty to assess the mechanical engineering educational objectives and program outcomes using internal and external measures. This process involves feedback from several parties that include: courses’ instructors (faculty), students, and graduating seniors, local industries that sponsor capstone senior design projects, and Fundamental of Engineering (FE) examination.
Experimental Characterization of a Unique Carbon Fiber Brush Heat Sink in Two-Phase Heat Transfer
Authors: Chengalvala Harish , Fleischer Amy S. , Jones G. F.
Published: April 2008

The performance enhancements and footprint decreases of advanced electronic devices result in soaring power densities which may in turn lead to elevated operating temperatures. As elevated device temperatures lead to decreased device reliability and increased thermal stresses, it is necessary to employ aggressive thermal management techniques to maintain an acceptable junction temperature at high power densities. For this reason, interest is growing in a variety of liquid cooling techniques This study analyzes an advanced engineered-material heat sink which provides significant improvements in thermal management strategies for advanced electronics. The heat sink consists of a very large number of small cross-section fins fabricated from carbon pitch fibers. For these carbon pitch fibers, the high thermal conductivity reduces the temperature drop along the length of the fin creating a longer effective fin length than for copper fins. The longer length results in more heat transfer surface area and a more effective heat sink. In liquid cooling, the rough surface of the fin will provide multiple bubble nucleation sites, strongly promoting active two-phase heat transfer over the entire fin surface. This surface enhancement is expected to lead to significant increases in performance over conventional heat sinks. This experimental analysis characterizes the thermal performance of the carbon-fiber heat sink in two-phase closed loop thermosyphon operation using FC72 as the operating fluid. The influence of power load, thermosyphon fill volume and condenser operating temperature on the overall thermal performance is examined. The results of this experiment provide significant insight into the possible implementation and benefits of carbon fiber heat sink technology in two-phase flow leading to significant improvements in thermal management strategies for advanced electronics.
Dynamic Axial Crush Tests of Roll Wrapped Composite Tubes: Plug vs. Non-Plug Crush Initiators
Authors: Browne Alan L. , Johnson Nancy L.
Published: April 2008

This paper discusses the effects of the method of crush initiation on the dynamic axial crush response of roll wrapped composite tubes. This constitutes a portion of a successful fundamental study conducted at GM R&D of the dynamic axial crush of automotive rail-sized composite tubes reinforced variously with carbon fiber, Kevlar® and hybrid combinations of the two, and manufactured using roll wrapping techniques suitable for the low cost high volume needs of the automotive industry. All tubes were manufactured using roll wrapping from multiple layers of uni-directional thermoset prepreg with the uni-directional fabric plies being oriented at ± 15° with respect to the longitudinal axis of the tube. A total of 21 dynamic axial crush tests were conducted using a free flight drop tower facility. Tests spanned a range of tube geometries — circular and square with different wall and cross section dimensions with cored and uncored walls and differing numbers of plies — and a range of drop heights/impact velocities and drop masses. A general finding was that stable and progressive crush occurred at acceptable load levels in all of the roll-wrapped tubes that were tested for all methods of crush initiation that were considered — a 45° lead end bevel either alone, with a zero radius plug-type crush initiator, or with a 12.7 mm radius plug. The method of crush initiation was, however, found to be capable of producing major differences in the crush initiation force Fp, the displacement average crush force Fav(D), the specific energy absorption SEA, and the crush morphology. As examples, both the displacement average value of dynamic axial crush force and the value of SEA were changed by as much as a factor of eight by the method of crush initiation.
Methods to Improve the Accuracy of Registration for Multimodal Inspection of Mechanical Parts
Authors: Wu Yanyan , Singh Prabhjot
Published: April 2008

Registration refers to the process of aligning corresponding features in images or point data sets in the same coordinate system. Multimodal inspection is a growing trend wherein an accurate measurement of the part is made by fusing data from different modalities. Registration is a key task in multimodal data fusion. The main problem with high-accuracy registration comes from noise inherent in the measurement data and the lack of the one-to-one correspondence in the data from different modalities. We present methods to deal with outliers and noise in the measurement data to improve registration accuracy. The proposed algorithms operate on point sets. Our method distinguishes between noise and accurate measurements using a new metric based on the intrinsic geometric characteristics of the point set, including distance, surface normal and curvature. Our method is unique in that it does not require a-priori knowledge of the noise in the measurement data, therefore fully automatic registration is enabled. The proposed methods can be incorporated into any point-based registration method. It was tested with the traditional ICP (Iterative Closest Point) algorithm with application to the data registration among point, image, and mesh data. The proposed method can be applied to both rigid and non-rigid registration.
Simulation of Fracture Behavior of Elastomer Modified Polypropylene Based on Elastoviscoplastic Constitutive Equation With Craze and Tensile Softening Law
Authors: Mae Hiroyuki
Published: April 2008

The strong strain-rate dependence, neck propagation and craze evolution characterize the large plastic deformation and fracture behavior of polymer. In the latest study, Kobayashi, Tomii and Shizawa suggested the elastoviscoplastic constitutive equation based on craze evolution and annihilation and then applied it to the plane strain issue of polymer. In the previous study, the author applied their suggested elastoviscoplastic constitutive equation with craze effect to the three dimensional shell issue and then showed that the load displacement history was in good agreement with the experimental result including only microscopic crack such as craze. For the future industrial applications, the macroscopic crack had to be taken into account. For instance, an airbag deployment simulation needed the macroscopic crack prediction. Thus, the main objective of this study was to propose the tensile softening equation and then add it to the elastoviscoplastic constitutive equation with craze effect so that the load displacement history could be roughly simulated during the macroscopic crack propagation. The tested material in this study was the elastomer blended polypropylene used in the interior and exterior of automobiles. First, the material properties were obtained based on the tensile test results at wide range of strain rates: 10−4 – 102 (1/sec). Next, the fast compact tension test was conducted and then the tensile softening parameters were fixed. Then, the fast bending test and the dart impact test were carried out in order to obtain the load displacement history and also observe the macroscopic crack propagation at high strain rate. Finally, the fracture behavior was simulated and then compared with the experimental results. It was shown that the predictions of the constitutive equation with the proposed tensile softening equation were in good agreement with the experimental results.
Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers
Authors: Cody Kristin Lai-Fook , Hambric Stephen A. , Pollack Martin L.
Published: April 2008

At low flow Mach numbers, fluid-elastic lock-in may occur when a shear layer instability interacts with an adjoining or nearby structure and the resulting vibration of the structure reinforces the shear layer instability. Despite the significant amount of study of lock-in with acoustic resonators, fluid-elastic lock-in of a shear layer fluctuation over a cavity and a structural resonator is not well understood and has not been thoroughly studied. Design of an experimental system is described and preliminary diagnostics are addressed as a basis for a platform for developing a fundamental understanding of the feedback mechanism, analytical models for predicting and describing fluid-elastic lock-in conditions, and the roles of the fluid and structural dynamics in the process. Features of the system investigated here include design for characterization of modal excitation of a beam-like structure from the shear layer fluctuation, isolation of the predominant instability source to the shear layer fluctuation over the cavity, variation of the cavity size to identify critical parameters that govern fluid-elastic lock-in, and alteration of the inflow boundary layer momentum thickness. So far, lock-in between the cavity and the distributed elastic resonator has not been achieved. Further investigations to determine the role of the source and resonator attributes are underway.
Energy Analysis of Liquid Desiccant Based Evaporative Cooling System
Authors: Al-Sulaiman Faleh A. , Gandhidasan P.
Published: April 2008

This paper presents preliminary findings of the energy analysis of a cooling system with multistage evaporative coolers using liquid desiccant dehumidifier between the stages. The proposed evaporative cooling system utilizes the air humidity for cooling in humid areas and requires no additional water supply. The major energy requirement associated with this cooling system is the energy for regenerating the weak liquid desiccant. In this paper two types of energy namely thermal energy as well as mechanical energy are considered for regeneration. For thermal energy, the heat input for regeneration is supplied from the conventional energy sources such as a simple line heater. Reverse osmosis (RO) process is considered for regeneration by mechanical energy and MFI zeolite membrane is proposed for separation of water from the weak desiccant solution. Energy analysis has been carried out for both methods of regeneration. The results show that the energy consumption is about 25% less for the mechanical regeneration system with 3 % recovery than the thermal energy regeneration system to increase the desiccant solution temperature of 22°C. The COP of the proposed cooling system is defined as the cooling effect by the mass rate of water evaporated in the system divided by the amount of energy supplied to the system, that is, the COP is independent of the energy source.
Heat Management With Phase Change of Self-Rewetting Fluids
Authors: Abe Yoshiyuki
Published: April 2008

The present paper mainly describes the latest progress in the thermal management devices with using “self-rewetting fluids” as a working fluid. The self-rewetting fluids are those dilute aqueous solutions of high carbon alcohols, which show a particular surface tension behavior—an increase in the surface tension with increasing temperature. In the case of phase change of these particular solutions, the Marangoni effects caused by both temperature gradient and concentration gradient along vapor/liquid interface are expected to induce a strong liquid inflow to local hot or dry spot at heater wall. Such a behavior is more pronounced in reduced gravity conditions and micro-scale heat transfer. The paper contains a series of reduced gravity and terrestrial experimental results on thermal management devices with self-rewetting fluids, wickless heat pipes and wicked heat pipes in reduced gravity and terrestrial conditions, respectively. In addition, preliminary experimental data for pool boiling characteristics of self-rewetting fluids are given.
Comparison of Spur Gear Root Stress Calculations
Authors: Janna Sied , Lin Hsiang H.
Published: April 2008

Methods of Spur Gear Root Stress determination were analyzed by comparing an experimentally proven method to documented theoretical methods. The methods evaluated were German DIN standards, AGMA standard, JGMA standard, and Cornell method. The Cornell method was used as a benchmark for comparison of other methods. Each method was used to calculate root stresses in a spur gear system. The gear system variables were torque and rotational speed. Seven different torque settings and four different rotational speeds were used in the analysis, giving 28 different system settings for analysis. The system was modeled using a NASA computer program, Dynamic Analysis of Spur Gear Transmission (DANST) developed by one of the authors. The stresses in the tooth root were calculated from the dynamic forces at 121 points along the involute tooth profile during a two-gear mesh. The study has shown that the stresses calculated using AGMA could predict the stresses calculated using the Cornell method of stress calculation. The JGMA method calculates the maximum root stress of the gear system within three percent of the Cornell method. The study showed that AGMA, and JGMA methods could be as effective at calculating the root stresses as the Cornell method.
Multiscale Modeling of Elastoplastic Behavior for Aluminum-Based Metallic-Glass Nanocomposites
Authors: Liu Haitao , Sun Lizhi
Published: April 2008

Progress has recently been made in experimental studies on mechanical properties and strengthening mechanisms of nanoparticle (α-Al) reinforced amorphous aluminum-matrix nanocomposites. However, little quantitative mechanical modeling of amorphous nanocomposites is available to demonstrate the underlying strengthening and deforming mechanisms. The objective of this paper is to explore the overall constitutive relationship of α-Al-reinforced amorphous nanocomposites in terms of a multiscale approach starting from the microstructure at nanoscale. The overall strengthening and deforming behavior of the nanocomposites is investigated from nanomechanics framework and homogenization procedures. Specifically, with the introduction of the nanoparticle surface area-volume ratio, the dependence of overall mechanical properties on nanoparticle sizes is particularly emphasized. Further effects of the nanoparticle concentration and local particle interaction are formulated. The proposed model can provide direct determination of the intrinsic mechanisms of material structure-property relationship at the nanoscale.
Multi-Scale Analysis of a Refractory Composite
Authors: Kwon Y. W. , Chu T. , Kim D.
Published: April 2008

A refractory composite for a high temperature application was studied at various length scales, and its effective thermo-mechanical properties were computed. The analysis considered a micro-scale model made of a representative carbon fiber, a matrix layer, and a coating layer. The model included weak tangential bonding of the intra-layer of the matrix material in order to reduce the thermal stress occurring in the coating material caused by mismatch of coefficients of thermal expansions. In addition, unit-cell models for a 3-D braided composite and a plane-weave composite were also studied. The modeling technique developed in this study can be used as a design tool for an optimal refractory composite for a given application.
Particle Orientational Properties and Viscosity of a Dense Colloidal Dispersion Composed of Ferromagnetic Spherocylinder Particles: Analysis by Means of Mean Field Approximation for a Simple Shear
Authors: Satoh Akira
Published: April 2008

We have theoretically investigated the particle orientational distribution and viscosity of a dense colloidal dispersion composed of ferromagnetic spherocylinder particles under circumstances of an applied magnetic field. The mean field approximation has been applied to take into account the magnetic interactions of the particle of interest with the other ones which belong to the neighboring clusters, besides its own cluster. The basic equation of the orientational distribution function, which is an integro-differential equation, has approximately been solved by Galerkin’s method and the method of successive approximation. Even when the magnetic interaction between particles is of the order of the thermal energy, the effect of particle-particle interactions on the orientational distribution comes to appear more significantly with increasing the volumetric fraction of particles. This effect comes to appear more significantly when the influence of the applied magnetic field is not relatively so strong compared with magnetic particle-particle interactions.
Fabricating Plastic Microfluidic Devices With Photodefinable Microvalves for Protein Separations
Authors: Fredrickson Carl K. , Das Champak , Tavares Fernando T. , Ferguson Ryan , Xia Zheng , Fan Z. Hugh
Published: April 2008

This paper describes the results of fabricating plastic microfluidic devices and creating a microvalve array for protein separation. Plastic devices are selected due to low cost of raw materials, bio-compatibility, and disposability. Although the methods for fabricating plastic devices have appeared in literature, reports typically indicate one set of conditions that yield functional devices. We report a systematic study of fabrication process parameters including compression rate, molding temperature, and the compression force used by a hydraulic press. Their effects on the device thickness, channel dimension, and pattern transfer fidelity will be discussed. In addition, we investigated creating an array of pseudo-microvalves using photodefinable, in situ gel polymerization. The valves were developed for introducing two types of separation media for performing two-dimensional protein separation in a microfluidic device. We also demonstrated rapid protein separation using the mechanism for the first dimension, isoelectric focusing.
Stress Analysis of Rectangular Plate With Bilateral Interface Cracks Under Hybrid Boundary Conditions
Authors: Liu Jiemin , Ma Guangtao , Sawa Toshiyuki
Published: April 2008

Presented is an approach for obtaining whole-field stress distributions of a bi-material rectangular plate, which is composed of plate I and plate II with a fixed boundary and subjected to external loads, using elasticity mechanics theory. There are two cracks at the edges of the interface of plate I and plate II, which are called as bilateral interface cracks. In the analysis, the effects of the ratio of Young’s modulus of material I (plate I) and to that of material II (plate II) and the ratio of the crack length to the width of the plate on the stress distributions in the vicinity of the interface were examined. Stress Intensity Factor (SIF) and normalized SIF equations were also calculated through the stresses in the vicinity of the crack tips.
Implementing Inter-Enterprise Workflow Management Using Agent-Based Web Services
Authors: Wang Shuying , Shen Weiming , Hao Qi
Published: April 2008

The service-orientated computing paradigm is transforming traditional workflow management from a close, centralized control system into a worldwide dynamic business process. This paper presents an agent-based Web service model to support inter-enterprise workflow management. In the proposed model, agent-based technology provides the workflow coordination at both inter-and intra-enterprise levels while Web services based technology provides infrastructures for messaging, service description and workflow enactment. Coordination agents and resource agents negotiate through a bidding mechanism for constructing dynamic workflow process between business partners. The agent system architecture, coordination model and related components are described. A prototype system is implemented for simulating the formation process of virtual enterprises. Our current approach integrating agents and Web services mainly focuses on communication and interaction. Our ongoing work is focusing on semantic integration in composing a dynamic workflow for inter-enterprise cooperation.
Three-Dimensional Thermal Analysis for Laser Assisted Milling of Silicon Nitride Ceramics Using FEA
Authors: Shen Xinwei , Liu W. J. , Lei Shuting
Published: April 2008

Laser assisted machining (LAM) is one promising method for ceramic machining. In this paper, a three-dimensional heat transfer and thermal stress analysis is completed using commercial FEA software (ANSYS) to gain some insights on the thermal aspects for laser assisted milling. The transient temperature distribution was analyzed for a silicon nitride (Si3N4) ceramic workpiece undergoing a translating laser heat source which simulates the heating environment of the slot-milling operation with LAM. The effects of the operating parameters, such as laser power, laser beam diameter, laser preheat time and laser translating speed, were investigated. The thermal stresses induced from the steep temperature change and the effects of the operating parameters on thermal stresses were investigated. Additionally, the maximum-normal stress failure theory for brittle materials were employed to predict the possibility of cracking on ceramic workpiece due to thermal stresses.
Flow Structure of an Inclined Jet in Crossflow
Authors: Dano Bertrand P. E. , Liburdy James A.
Published: April 2008

The velocity and turbulence fields associated with a streamwise 45° inclined jet in a crossflow are investigated in three dimensions. Using Stereo-PIV data, full 3D rendering of the 3-component velocity field and turbulent characteristics are achieved and used to study the near field flow structure of the jet flow. A two dimensional vortex detection algorithm is also used to further assess the vortical structures in the flow.
A Novel Asymmetric Microfluidic Oscillator
Authors: Chen Chiko , Yang Jing-Tang , Ho Chien-Hung
Published: April 2008

In this work we present an asymmetric microfluidics oscillator of innovative design and systematically investigated it with both numerical and experimental methods. The design of both entrance nozzle and asymmetric feedback channels enable the oscillator to stably oscillate in very small range of Reynolds number 1~100, whereas the Strouhal number remained as 1 × 10−3. The results reveal that improvement of the performance was resulted from the augmented periodic impingement of the flows from the feedback channels. The analysis also indicates that dynamic phenomena in the working fluid of this novel oscillator were distinctive and appropriately appraised.
Didactical Set for the Analysis and Synthesizes of Mechanisms (DSASM)
Authors: Di´az Carlos Rodolfo Di´az , Venegas Jose´ Colin
Published: April 2008

In this paper we present a new design of mechanisms laboratory which permits to analyze and design planar mechanisms like the four-bar mechanism and the slider mechanism, plus its variables with one degree of freedom (1 DOF). This design we call Didactical Set for the Analysis and Synthesizes of Mechanisms (DSASM) or BDASM, as its initials in Spanish language. This laboratory combines mechanical design, electronics, and programming skills to offer more abilities for develop mechanisms and automation programming. This set has various advantages: Easy to assemble mechanisms, Easy to control, has Data acquisition and is comfortable.
Flexural Response of Laminated Steel
Authors: Xiao Xinran (Sharon) , Hsiung Ching-Kuo , Zhao Zhong
Published: April 2008

Steel/polymer/steel laminate sheets, commonly known as laminated steel, received renewed interest recently for their superior noise damping properties in automotive applications. Earlier work in the literature indicates that the tensile properties of the laminated steel follow the prediction of the rule of mixtures. The flexural response of the laminated steel, however, depends on the type of the sandwich configuration. The flexural rigidity of the vibration-damping type of laminated steel is lower than the value calculated using beam theory. The finite element (FE) modeling techniques that might be suitable for a particular type of laminated steel are directly linked to how the flexural rigidity of the laminated steel conforms to the prediction using the beam theory. This paper examines the flexural response of the vibration-damping type of laminated steel through comparison of beam theory predictions with the experimental results for cantilever beam and three-point bending configurations. In addition, tensile and shear tests were conducted. The paper evaluates some FE modeling techniques in LS-DYNA for the analysis of laminated steel under flexural loading. The recommended modeling method was also examined for tensile loading.
A Comparative Study of DES and URANS in a Two-Pass Internal Cooling Duct With Normal Ribs
Authors: Viswanathan Aroon K. , Tafti Danesh K.
Published: April 2008

The capabilities of the Detached Eddy Simulation (DES) and the Unsteady Reynolds Averaged Navier-Stokes (URANS) versions of the 1988 κ-ω model in predicting the turbulent flow field and the heat transfer in a two-pass internal cooling duct with normal ribs is presented. The flow is dominated by the separation and reattachment of shear layers; unsteady vorticity induced secondary flows and strong streamline curvature. The techniques are evaluated in predicting the developing flow at the entrance to the duct and downstream of the 180° bend, fully-developed regime in the first pass, and in the 180° bend. Results of mean flow quantities, secondary flows, friction and heat transfer are compared to experiments and Large-Eddy Simulations (LES). DES predicts a slower flow development than LES, while URANS predicts it much earlier than LES computations and experiments. However it is observed that as fully developed conditions are established, the capability of the base model in predicting the flow and heat transfer is enhanced by switching to the DES formulation. DES accurately predicts the flow and heat transfer both in the fully-developed region as well as the 180° bend of the duct. URANS fails to predict the secondary flows in the fully-developed region of the duct and is clearly inferior to DES in the 180° bend.
Design Integration for Screw Compressors
Authors: Kovacevic Ahmed , Stosic Nikola , Mujic Elvedin , Smith Ian K.
Published: April 2008

DISCO - Design Integration for Screw Compressors is a tool interface for screw compressor design developed with aim to reduce intensive efforts and speed up the design process. This procedure connects software components required to produce three-dimensional CAD models and manufacturing drawings with calculation of thermodynamic process, fluid flow and solid structure stresses and strains. A number of input parameters required to describe a machine geometry and operating conditions is small and introduced only once for all of design software. Because of that, a control over the design process is easy to maintain. This allows that the modifications made to the compressor model in any of the design stages are cross referenced through all of software components. Such an approach saves both the computer resources and time when compared with a classical design processes.
Combined Analysis of Plastic Flow and Temperature Distribution During Friction Stir Welding
Authors: Hirasawa Shigeki , Okamoto Kazutaka , Hirano Satoshi , Tomimura Toshio
Published: April 2008

Plastic flow, heat generation by shear force, and temperature distribution during the FSW process were analyzed. The plastic flow was numerically calculated using a particle method and the temperature distribution was calculated using a finite element method. Both analyses were combined. Temperature distributions were calculated by changing conditions of heat generation caused by the friction between the rotating tool and the metal plates. Local temperature distributions near the rotating tool differed for the conditions, but whole temperature distributions were almost same. In the calculation result of the plastic deformation, the heat generation by the shear force occurred about 60% at near the shoulder and 40% at near the pin of the tool.
Model Simplifications for Nonlinear Hydraulic Circuits
Authors: Alirand M. , Orand N. , Lebrun M.
Published: April 2008

The aim of this paper is to have a view of different levels of model simplifications for a simple hydraulic circuit. The bond graph is used to synthesize the simplifications and the different assumptions behind. Different models were built in order to keep continuity in model simplification. These models have the two causalities allowed for a particular physical phenomenon. It is believed that software will give access to different levels of model simplifications and the user will choose between these different levels the proper one that will answer to his question. However this proper model will only be achieved step by step using continuity in model simplification. The paper also shows that systems may include very different levels of power (pilot and main stages or thermal effects) and in such a case at least one C-, I- or R-element should be kept per power level.
Predictions on Wall Pressure Fluctuations for a Backward-Facing Step
Authors: Lee Yu-Tai , Farabee Theodore M. , Blake William K.
Published: April 2008

Time-mean flow fields and turbulent flow characteristics obtained from solving the Reynolds averaged Navier Stokes (RANS) equations with a k-ε turbulence model are used to predict the frequency spectrum of wall-pressure fluctuations for flow past a backward facing step. The linear source term of the governing fluctuating pressure equation is used in deriving the final double integration formula for the fluctuating wall pressure. The integrand includes the RANS mean-velocity gradient, modeled turbulence normal fluctuation, Green’s function and the spectral model for the interplane correlation. An anisotropic distribution of the turbulent kinetic energy is implemented using a function named anisotropic factor. This function represents a ratio of the turbulent normal Reynolds stress to the turbulent kinetic energy and is developed based on an equilibrium turbulent flow or flows with zero streamwise pressure gradient. The spectral correlation model for predicting the wall-pressure fluctuations is obtained through modeling of the streamwise and spanwise wavenumber spectra. The non-linear source term in the original governing equation is considered following the conclusion of Kim’s direct numerical simulation (DNS) study. Predictions of frequency spectra for the reattachment flow past a backward facing step (BFS) are investigated to verify the validity of the current modeling. Detailed turbulence features and wall-pressure spectra for the flow in the reattachment region of the BFS are predicted and discussed. The prediction results based on different modeling characteristics and flow physics agree with the observed turbulence field.
Comparison of the Braking Performance of Electromechanical and Hydraulic ABS Systems
Authors: Emereole Okwuchi C. , Good Malcolm C.
Published: April 2008

The benefits potentially available by replacing conventional hydraulic ABS brake systems with electromechanical brake-by-wire systems (EMB) are extensive and have been well documented. They include increased functionality, packaging and design flexibility, reduced assembly costs, and elimination of hydraulic fluids [1, 2]. A characteristic of most ABS systems is a sequence of discontinuous build-hold-dump pressure cycles, whereas EMB systems will allow continuous control of brake torque. In this paper, the antilock performance of an EMB using a continuous brake torque control strategy is compared against that of a current state-of-the-art hydraulic ABS system. The comparison was performed using a half-car model developed in the Simulink environment. The hydraulic system characteristics were identified from ABS test data on a recent production vehicle and the simulated ABS logic was also validated using this data. A simple model of the dynamics of an EMB actuator with clamp force control was developed, and validated against limited test results from a prototype EMB system. A continuous gain-scheduled PID wheel slip controller was developed for the EMB to replace the conventional ABS logic. Brake system performances were compared using an Antilock Performance Index (API). The results of the comparison indicate that an EMB with continuous slip control has the potential to perform better than a conventional ABS system, provided a suitably robust wheel slip controller and algorithm for determining the appropriate target slip are available.
Development of a Causal Model for Air Transport Safety
Authors: Ale B. J. M. , Bellamy L. J. , Roelen A. L. C. , Cooke R. M. , Goossens L. H. J. , Hale A. R. , Kurowicka D. , Smith E.
Published: April 2008

The development of the Dutch international airport Schiphol has been the subject of fierce political debate for several decades. One of the considerations has been the safety of the population living around the airport. In the debate about the acceptability of the risks associated with the air traffic above The Netherlands the need has arisen to gain a more thorough understanding of the accident genesis in air traffic, with the ultimate aim of improving the safety situation in air traffic in general and around Schiphol in particular. To this end a research effort has been started in order to develop causal models for air traffic risks in the expectation that these will ultimately give the necessary insights. The first step is to organise the information available in accident databases.
An Improved Model of Machining Chip Breaking Limits for Smart Machining Process Design
Authors: Avanessian A. , Rong Y. , Tan G.
Published: April 2008

Prediction of chip-breaking in machining is an important task for automated manufacturing. According to experiments and previous study, there are chip-breaking limits in machining chip-breaking chart, which determine the chip-breaking range. When inserts with 3-D grooves are used in finish machining, there is an additional chip-breaking region beyond the chip breaking limits determined by the prediction models in previous study. In this paper, the chip-breaking chart is studied for protruded insert grooves. Analytical models are established in order to determine minimum and maximum depths of cut in the additional region of the chip breaking chart. In the end, the analytical critical feed rate model is extended to the cases that the depth of cut is smaller than nose radius.
Asymmetrical Flow Behaviour in Transitional Pipe Flow of Non-Newtonian Liquids
Authors: Poole R. J. , Escudier M. P. , Presti F. , Dales C. , Nouar C. , Desaubry C. , Graham L. , Pullum L.
Published: April 2008

The purpose of this presentation is to report mean velocity-profile data for fully-developed pipe flow of a wide range of shear-thinning liquids together with two Newtonian control liquids. Although most of the data reported are for the laminar-turbulent transition regime, data are also included for laminar and turbulent flow. The experimental data were obtained in unrelated research programmes in UK, France and Australia, all using laser Doppler anemometry (LDA) as the measurement technique. In the majority of cases, axisymmetric flow is observed for the laminar and turbulent flow conditions, although asymmetry due to the Earth’s rotation is evident for the laminar flow of a Newtonian fluid of low viscosity (i.e. low Ekman number). The key point, however, is that for certain fluids, both yield-stress and viscoelastic (all fluids in this study are shear thinning), asymmetry to varying degrees is apparent at all stages of transition from laminar to turbulent flow, i.e. from the first indications to almost fully-developed turbulence. The fact that symmetrical velocity profiles are obtained for both laminar and turbulent flow of all the non-Newtonian fluids in all three laboratories leads to the conclusion that the asymmetry must be a consequence of a fluid-dynamic mechanism, as yet not identified, rather than imperfections in the flow facilities.
Thermal Modeling of a Sodium Borohydride-Based Hydrogen Storage System
Authors: Zhang Jinsong , Fisher T. S.
Published: April 2008

On-board hydrogen storage has been identified as one of the most challenging technical barriers to the transition from gasoline- to hydrogen-powered vehicles. The Hydrogen-On-Demand system patented by Millennium Cell Inc. uses sodium borohydride as a hydrogen storage medium. Sodium borohydride generates hydrogen when it reacts with water in the presence of catalyst. This system is much safer than other types of storage methods, such as compressed hydrogen, liquid hydrogen and metal hydrides. Nevertheless, it suffers severe disadvantages of adding significant amount of additional heat load to the already challenging thermal management problem of fuel-cell powered vehicles. To make this hydrogen storage method attractive, innovative thermal management should be adopted. This paper models the thermal behavior of a sodium borohydride-based hydrogen storage system and considers various potential methods to reduce the on-board cooling load by increasing reactor pressure and decreasing fuel cell pressure.
Structural Analysis of Utility Boiler Waterwall
Authors: Kim Tae-Woan , Kim Jae-Cheol , Hwang Suk-Hwan
Published: April 2008

The safe structural design of boiler waterwalls with various loadings such as dead weight, fluid pressure, gas pressure and thermal differences is an extensive problem demanding the use of sophisticated computation methods due to the complexity of the geometric structure and the large size of the walls. To evaluate the operating reliability of boiler waterwalls, it is essential to know not only overall behavior of the whole structure but also the stress states at the critical zones. In this paper, the structural soundness for the Korea standard 500MW boiler waterwalls is preliminary examined. The equivalent orthotropic plate model is used to investigate the structural behavior of boiler waterwalls under thermal differences. Submodeling technique for part model of boiler waterwalls is proposed to accurately compute stresses of waterwalls at the critical zones under gas pressure. The computed stresses are combined and finally compared with the allowable stress limits according to the criteria of ASME Code.
Improving Ethanol Life Cycle Energy Efficiency by Direct Combustion of Wet Ethanol in HCCI Engines
Authors: Martinez-Frias Joel , Aceves Salvador M. , Flowers Daniel L.
Published: April 2008

Homogenous Charge Compression Ignition (HCCI) is a relatively new engine technology with fundamental differences over conventional engines. HCCI engines are intrinsically fuel flexible, and can run on low grade fuels, as long as the fuel can be evaporated and heated to the point of ignition. In particular, HCCI engines can run on wet ethanol with high concentration of water. Considering that much of the energy required for processing the ethanol is spent in distillation and dehydration, direct use of wet ethanol in an HCCI engine considerably shifts the energy balance in favor of ethanol. The results of the paper show that an HCCI engine with efficient heat recovery can operate on a 35-65% volumetric mixture of ethanol and water, while achieving a high efficiency (38.7%) and very low NOx (1.6 parts per million, clean enough to meet any existing or oncoming emissions standards). Operation of the HCCI engine with 35% ethanol by volume reduces the energy required for distillation and dehydration from 37% to 3% of the overall energy of ethanol and coproducts. The net energy gain increases considerably, from 21% to 55% of the total energy value of the fuel and coproducts. Wet ethanol combustion in HCCI engines shows great potential for improving the ethanol energy balance, and merits more detailed analysis and experimental evaluation.
Spray Penetration and Drop Size Studies of Diesel Fuels
Authors: Jawad Badih A. , Riedel Chris H. , Bazzari Ahmad
Published: April 2008

Understanding the disintegration mechanism, spray penetration, and spray motion is of great importance in the design of a high quality diesel engine. The atomization process that a liquid would undergo as it is injected into a high-temperature, high-pressure air, is investigated in this work. The purpose of this study is to gain further insight into the atomization mechanism, the variation over time in droplet size distribution and spray penetration. This is done based on effect of chamber pressure, injection pressure, and type of fuel. A laser diffraction method is used to determine droplet mean diameters, single injection with synchronized time mechanism allowed the time dependent studies. Obscuration signals are obtained through a digital oscilloscope from which arrival time of spray can be measured. The spray penetration correlation obtained is compared to other correlation’s obtained from different other techniques used in the literature.
Turbulent Heat Transfer and Flow Structure Downstream of a Plate Blockage
Authors: Molki Majid , Deshetty Avinash , Rajendran Arun
Published: April 2008

Turbulent flow in a rectangular duct with a plate blockage attached to the lower wall was numerically solved. The computational models used were Large Eddy Simulation (LES), 2D and 3D, steady and unsteady Reynolds-averaged Navier-Stokes (2D-SRANS and 3D-URANS). The fluid was air in all computations, and the Reynolds number (Re) was 5000 and 30,000. The predictions of LES were in several ways closer to the experimental data. For the two values of Re considered in this study, the LES over-predicted the location of maximum Nusselt number (Nu) by 24.1–24.9%, while the 3D-URANS under-predicted it by 23.7–36.8%. The best prediction for the value of maximum Nu was made by LES for Re = 5000, which was 9.3% higher than the experimental value. The LES under-predicted the maximum Nu by 24.1% for Re = 30,000. In the given range of Re, the under-predictions of 2D-SRANS and 3D-URANS for the value of maximum Nu were, respectively, 15.1–16.5% and 25.9–30.1%. As to the location of flow reattachment, the best value was predicted by the 2D-SRANS, while those of LES and 3D-URANS were close.
Design Synthesis and Evaluation in a Design Reuse System
Authors: Xu Q. L. , Ong S. K. , Nee A. Y. C.
Published: April 2008

This paper presents a design reuse approach to facilitate product conceptual design. While current design information management systems are useful in storing and retrieving product knowledge, providing effective assistance to intelligent design synthesis is still far from satisfactory, let alone the support to logical solution evaluation. Accordingly, this paper proposes an approach to automatically generate design solutions and evaluate them analytically according to multiple design objectives. To achieve these functions, a design synthesis method based on a multi-objective optimization algorithm is proposed. It makes use of existing product information to create multiple candidate solutions. Moreover, a component fitness assessment (CFA) method is proposed to evaluate the reusability of the design components. This CFA method is used in the selection of design components during the design synthesis. A design reuse system is developed to implement the methodology. It can effectively manage heterogeneous product information as well as provide computational support for design synthesis and evaluation.
A Level Set Method for Simulation of Coalescence of Droplets
Authors: Salih A. , Moulic S. Ghosh
Published: April 2008

In the present paper, we discuss a numerical method based on the level set algorithm to simulate two-phase fluid flow systems. Surface tension force at the fluid interface is implemented through the CSF model of Brackbill et al. [1]. The incompressible Navier-Stokes equations were solved on a staggered grid using an explicit projection method. A fifth-order WENO [2] scheme was used for advancing the level set function. We improved the implementation of WENO scheme by staggering the level set function. The Navier-Stokes part of the code was validated by computing the standard lid-driven cavity flow and the free surface part of the code was validated by advecting the interface in a prescribed velocity field. The Young-Laplace law for a static drop has been verified to validate the implementation of surface tension force. We simulated the coalescence of two drops under zero-gravity condition and evaluated the mass conservation property of the level set method.
Membrane Deflection Analysis of the Intelligent Micro-Sensor/Pump Under the Consideration of Micro-Viscosity and Membrane Pillar
Authors: Yih T. C. , Gillella Shalini R.
Published: April 2008

New emerging technologies such as MEMS “Micro-Electro-Mechanical Systems” provides many promising opportunities for developing innovative methods. This research focuses on the design, development and analysis of functional micro-pumps. Micro-pumps open new frontiers of engineering applications where precise fluid amounts to a targeted location are required. Micro-pumps can be used in environmental monitoring, where localized water quality measurements are needed, chemical/biological detection and analysis, and industrial process control. Conventional MEMS micro-pumps are driven by micro-actuators, which add complication to micro-pump membrane/structure design, control, and fabrication. The proposed MEMS micro-pump will have its membrane (or diaphragm) be sensitive to external pressure change and self-actuated in response to a designated pressure level; thus named IMSP (intelligent micro-sensor/pump). This paper provides a detailed study of membrane deflection which is one of the most important component of micro-pump. The membrane of the conventional design has uniform thickness. The novel smart micro-pump has a membrane pillar in the center. This membrane pillar has advantages of greater stability, larger pumping force and longer life cycle. The deflection of the membrane is analyzed and compared in two cases: 1) Membrane deflection without membrane pillar, and 2) Membrane deflection with membrane pillar. The micro-viscosity effect on a micro-pump will be augmented as the size of the micro-pump becomes smaller, especially in the micron range. Therefore two more cases are analyzed under the consideration of micro-viscosity effect: 1) Membrane deflection with micro-viscosity effect and without membrane pillar, and 2) Membrane deflection with micro-viscosity effect and with membrane pillar. The critical design parameters of the membrane—thickness and diameter—are varied and substituted into the governing equations to calculate the membrane deflection. The curves of membrane deflection versus the applied pressure on the membrane are plotted for further characterization of the micro-pump. This study will lead to the full development of a smart micro-pump and set off a new research direction.