bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy Considerations in the Spreading of LNG on Sea Water
Authors: Subramani A. , Jayanti S.
Published: August 2009

The spreading of an accidental spill of Liquefied Natural Gas (LNG) on sea water has been studied for many years and several theoretical models have been proposed and successfully used. Many modeling techniques have been used by researchers for the spreading of LNG. However, most of these neglect the heat transfer aspects related to the spreading, and the effect of temperature dependent properties such as density, thermal conductivity and specific heat of LNG is not included in the analysis. In the present study, this situation is redressed by including the depth-averaged energy equation in a one-dimensional model of the spreading of LNG on sea water. The thermophysical and transport properties of the fluid are made temperature-dependent and heat transfer to the pool from the water below and the flame above are included. The resulting set of coupled one-dimensional mass, radial momentum and energy balance equations are solved numerically using an explicit, second order-accurate finite difference method-based discretization of the governing equations. Results obtained in the present study show that the incorporation of the variable properties gives significantly improved predictions over conventional models. The predicted results are compared with the experimental results of Raj et al [1], and with a conventional, constant-properties model of Fay [2] for the test case #12. Excellent agreement is found between the current model predictions and the experimental data while the conventional model overpredicts the pool diameter for longer times. It is demonstrated that the present approach is inherently capable of distinguishing between the spreading of different LNG mixtures, and can therefore be readily extended to the analysis of the accidental spill of any other hazardous substance.
Sound Quality Evaluation for the Vehicle HVAC System After Active Noise Control
Authors: Yang In Hyung , Kwon O. Cheol , Lee Jung Youn , Oh Jae-Eung
Published: August 2009

The reduction of the Vehicle interior noise has been the main interest of NVH engineers. The driver’s perception on the vehicle noise is affected largely by psychoacoustic characteristic of the noise as well as the SPL. In particular, the HVAC sound among the vehicle interior noise has been reflected sensitively in the side of psychology. In previous study, we have developed to verify identification of source for the vehicle HVAC system through multiple-dimensional spectral analysis. Also we carried out objective assessments on the vehicle HVAC noises and subjective assessments have been already performed with 30 subjects. In this study, the linear regression models were obtained for the subjective evaluation and the sound quality metrics. The regression procedure also allows you to produce diagnostic statistics to evaluate the regression estimates including appropriation and accuracy. Appropriation of regression model is necessary to R2 value and F-value. And testing for regression model is necessary to Independence, Homoscedesticity and Normality. To enhance sound quality, we applied active noise control (ANC) which is effective in the low-frequency bandwidth. Primary noise of the HVAC system is less than 500Hz. As a result of ANC application, sound quality is improved by more quiet, powerful, expensive, smooth.
Nonlinear Behaviors of the Machine-Tool Spindle System Supported by Ball Bearings With Clearance
Authors: Gao S.-H. , Long X.-H. , Li H.-G. , Meng G.
Published: August 2009

In this effort, the nonlinear dynamics of a machine-tool spindle system supported by ball bearings is investigated. Considering the loss of contact between the inner race and ball in the ball bearing, the system is described by a set of second order nonlinear differential equations with piecewise stiffness and damping. The nonlinear responses of the system exhibit the softening behavior due to the loss of contact. As the initial preload is applied to the spindle system and the balls are fully contacting with the inner race of the bearing, the nonlinear responses of the system switche to the hardening behavior. Due to the 3/2 nonlinearity, resonance are found when the excitation frequency is close to one-third of the first natural frequency, one-half of the first nature frequency, two-third of the first natural frequency, and the first natural frequency. The route of the period-doubling bifurcation to chaos and the tori doubling process to chaos which usually occurs in the impact system are also observed in this spindle-bearing system.
Improving the Operation of a Cyclone Coupled With an Ejector
Authors: Strasser Wayne
Published: August 2009

The dynamics of a plant-scale cyclone/ejector system have been studied numerically. The purpose of said system is to separate and evacuate solid particles from a highly dense vapor stream involved in polyethylene production. Complexity arises from the fact that the transient pressure field within the Lappel cyclone governs the operation of the annular ejector, and vice versa. Specifically, the cyclone’s asymmetrically dancing vortex dips well into the ejector suction; therefore the two units cannot be computationally uncoupled. Compressible, time-dependent CFD results were surprisingly sensitive to the pressure discretization approach. Results had a mixed dependency on the slow pressure strain formulation in the differential Reynolds Stress calculations, while they were insensitive to the pressure-velocity coupling routine. Interesting results from earlier researchers regarding particle orbit radius, as well as particle bypassing were confirmed. Six geometric configurations for improving the system operation were evaluated. Pressure differential and solids collection efficiency were the two primary measures. Since said system is an integral part of a complex commercial operation, cost and physical space constraints severely limit the extent to which the geometry can be modified. Simple geometric changes were shown numerically to make operational improvements while only incrementally improving particle collection efficiency.
Optimized Design Method of Vehicle Suspension Systems Using a Reverse Engineering Approach
Authors: Gubitosa Marco , De Cuyper Joris , Cibrario Valerio
Published: August 2009

Nowadays companies dealing with the automotive market, and in particular product designers, are facing with highly competitive environments though conflicting demands to deliver more complex products with increased quality in ever shorter development cycles. The usage of numerical simulations is therefore a confirmed technique going through the conceptual (1D) modeling towards a detailed digital mock-up to realize complex multibody (3D) simulations. The purpose of this paper is to develop a systematic design method for the suspension systems using CAE (Computer Aided Engineering) tools to investigate different properties which have influence on the ride & handling of a vehicle. Running a reverse engineering approach, the elasto-kinematic characteristics of different types of suspensions can be focused out and exported from a multibody environment (Virtual.Lab Motion has been chosen as example) as look-up tables to be read by a 1D multi-domain software (in the work here presented we used Imagine.Lab AMESim). Combined runs of sensitivity analyses and optimization cycles would then bring to the final goal of understanding the most suitable target behavior of the full system and the weight of different design variables on this, being hence able to directly address modifications of the global configuration.
Galvanotactic Control of Self-Powered Microstructures
Authors: Steager Edward , Sakar M. Selman , Cheang U. Kei , Casale David , Kumar Vijay , Pappas George J. , Kim Min Jun
Published: August 2009

We are examining microactuation techniques by employing the electrokinetic and galvanotactic behavior of certain bacteria. We cultured selected strains of swarming Serratia marcescens which were attached to microstructures using a blotting technique that creates a bacterial monolayer carpet. These bacterial carpets naturally self-coordinate to propel the microstructures. The microstructures were placed in an open channel and a voltage was applied and polarity was switched. We have demonstrated directional control of the motion of the microstructures patterned with bacteria. This mobility is due to the patterning of bacteria on the microstructure surface and arises from a combination of electrokinetic effects and galvanotaxis.
A Gaussian Process-Based Approach for Handling Uncertainty in Vehicle Dynamics Simulation
Authors: Schmitt Kyle , Madsen Justin , Anitescu Mihai , Negrut Dan
Published: August 2009

Advances in vehicle modeling and simulation in recent years have led to designs that are safer, easier to handle, and less sensitive to external factors. Yet, the potential of simulation is adversely impacted by its limited ability to predict vehicle dynamics in the presence of uncertainty. A commonly occurring source of uncertainty in vehicle dynamics is the road-tire friction interaction, typically represented through a spatially distributed stochastic friction coefficient. The importance of its variation becomes apparent on roads with ice patches, where if the stochastic attributes of the friction coefficient are correctly factored into real time dynamics simulation, robust control strategies could be designed to improve transportation safety. This work concentrates on correctly accounting in the nonlinear dynamics of a car model for the inherent uncertainty in friction coefficient distribution at the road/tire interface. The outcome of this effort is the ability to quantify the effect of input uncertainty on a vehicle’s trajectory and the associated escalation of risk in driving. By using a space-dependent Gaussian process, the statistical representation of the friction coefficient allows for consistent space dependence of randomness. The approach proposed allows for the incorporation of noise in the observed data and a nonzero mean for inhomogeneous distribution of the friction coefficient. Based on the statistical model considered, consistent friction coefficient sample distributions are generated over large spatial domains of interest. These samples are subsequently used to compute and characterize the statistics associated with the dynamics of a nonlinear vehicle model. The information concerning the state of the road and thus the friction coefficient is assumed available (measured) at a limited number of points by some sensing device that has a relatively homogeneous noise field (satellite picture or ground sensors, for instance). The methodology proposed can be modified to incorporate information that is sensed by each individual car as it advances along its trajectory.
Biogas Combustion and Chemical Kinetics for Gas Turbine Applications
Authors: Jahangirian Saeed , Engeda Abraham
Published: August 2009

Biogas is produced from anaerobic digestion of biodegradable materials such as agricultural waste, animal waste, and municipal solid waste and its main constituents are CH4 and CO2. A review of biogas production and benefits as well as its combustion as an alternative gas turbine fuel is presented. To further understand the characteristics of biogas combustion, a detailed chemical kinetics study of biogas is conducted using the GRI-Mech 3.0 and the San Diego detailed mechanisms and a reduced mechanism in a counterflow configuration. Ignition delays and laminar flame speeds of some gaseous fuel blends which simulate biogas are calculated. Effects of the concentration of each species in the blend are discussed as well as its chemical contribution in the biogas combustion. Approximate analytical correlations are extracted from these results for quantitative predictions. Results of this study will provide valuable data both for gas turbine manufacturers and for biogas producers to modify the gas turbine design for biogas and to figure out how much cleaning and upgrading is required for biogas turbines.
Probing Bacterial Flagellar Polymorphism in Various Fluidic Environments Using Solid-State Sub-Micropores
Authors: Mulero Rafael , Hesse William R. , Wu Liang , Kim Min Jun
Published: August 2009

A novel method for the detection of an assortment of environmental conditions in a microfluidic system using bacterial flagella and submicro-scale solid state pores is presented. Differences in various environmental conditions stimulate the polymorphic helix structure of Salmonella typhimurium flagella to transform to its lowest energetic conformation. By measuring the ionic current blockage (resistive pulse) as flagella electrophoretically translocate a submicro-scale pore, detection of the polymorphic state of flagella corresponding to the conditions of the environmental stimuli is possible. We test the viability of this method using purified depolymerized and repolymerized S. Typhimurium flagella and a high resolution electrical signal readout sub-micropore-based detection system.
Numerical Simulation of Heat Transfer for the Gob Delivery System in Glass Container Production
Authors: Liu X. J. , Hyre M. R. , Frost G. S. , Austin S. A.
Published: August 2009

Heat transfer is extremely important in glass container production since the physical properties of the glass are greatly affected by temperature. The change of glass properties in the production process needs to be closely monitored and controlled to produce high quality containers. The delivery system, which transports glass from feeder to the blank mold of the IS machine, contains the scoop, trough and deflector. It is the first place in the delivery system that molten glass inside feeder is brought into contact with a much colder environment on the delivery equipment. Recent developments in numerical techniques and computing capabilities enable the 3-dimensional free surface simulation of a gob of molten glass in the delivery system. In this study, a finite element method implemented by the computational fluid dynamics package Polyflow from ANSYS is used to track the large free surface deformations of a glass gob during the transport from the feeder to the blank mold. The capability to apply a user defined function allows the effect of varying heat transfer between the contact surface of gob and delivery equipment to be analyzed. A contact algorithm coupled with a Lagrangian remeshing scheme is applied to detect the interface between the molten glass gob and delivery equipment. The heat transfer profile is further studied by using a Fluent model for the equipment and comparing the resultant temperature profiles with measured field data. Better understanding of the delivery system can help manufacturers improve process control and facilitate equipment adjustment to produce containers with consistent loading that leads to increased productivity and reduced defects.
Effect of Coriolis Forces in a Rotating Channel With Dimples and Protrusions
Authors: Elyyan Mohammad A. , Tafti Danesh K.
Published: August 2009

The use of dimple-protrusions for internal cooling of rotating turbine blades has been investigated. A channel with dimple imprint diameter to channel height ratio (H/D = 1.0), dimple depth to channel height ratio (δ/H = 0.2), spanwise and streamwise pitch to channel height ratios (P/H = S/H = 1.62) was modeled. Four rotation numbers; Rob = 0.0, 0.15, 0.39, and 0.64, at nominal flow Reynolds number, ReH = 10000, were investigated to quantify the effect of Coriolis forces on the flow structure and heat transfer in the channel. Under the influence of rotation, the leading (protrusion) side of the channel showed weaker flow impingement, larger wakes and delayed flow reattachment with increasing rotation number. The trailing (dimple) side experienced a smaller recirculation region inside the dimple and stronger flow ejection from the dimple cavity with increasing rotation. Secondary flow structures in the cross-section played a major role in transporting momentum away from the trailing side at high rotation numbers and limiting heat transfer augmentation. While heat transfer augmentation on the trailing side increases by over 90% at Rob = 0.64, overall Nusselt number and friction coefficient augmentation ratios decrease from 2.5 to 2.05, and 5.74 to 4.78, respectively, as rotation increased from Rob = 0 to Rob = 0.64.
Study the Effect of Anticancer Drugs on Human Breast Cancer Cells Using Three Dimensional Silicon Microstructures
Authors: Nikkhah Mehdi , Strobl Jeannine S. , Agah Masoud
Published: August 2009

In this paper we report development of three dimensional silicon microenvironments in order to test the morphological changes and adhesion properties of human breast cancer cells after treatment with different anticancer drugs such as Trichostatin A (TSA), suberoylanilide hydroxamic acid (SAHA) and Scriptaid. Our results indicate that the cancer cells reorganize their cytoskeleton structure after treatment with TSA and Scriptaid. However, SAHA does not change the behavior of the cells inside the three dimensional microstructures while TSA and Scriptaid evoked striking changes in the cells morphology. TSA and Scriptaid drugs cause the cells to stretch inside the isotropic microchambers to avoid contact with curved sidewalls in contrast to their originally rounded shape. The proposed microstructures can be used to evaluate mechanical properties and the pathological grade of various cancer cell lines after different conditions i.e. drug exposure.
Design of Streamwise Stagger Within a Pin Fin Array to Minimize Pressure Loss
Authors: Andrews Stephen A. , Allan William D. E.
Published: August 2009

An experiment was conducted on the effects of streamwise stagger on heat transfer and pressure drop in a pin-fin array. The data were analyzed so as to highlight how stagger could be used to design a pin fin array for the lowest possible pressure loss. Design of arrays for low pressure loss is important in electronics cooling applications. They require large amounts of heat to be extracted from fixed areas, using a minimum of power to do so. This analysis found that the minimum friction factor occurred at a streamwise stagger of approximately 12% of the range between fully inline and fully staggered. By fixing the pin diameter, varying the stagger resulted in a 63% reduction in friction factor with only a 18% reduction in the Nusselt number, based on the array footprint. Additionally, it was found that for a fixed Nusselt number, the pin diameter could vary within a finite range, with decreasing diameters permitting arrays with more efficient degrees of stagger which continued to carry the required heating/cooling load.
Modeling the Automotive Engine Components With Viscoelastic Gasket Elements
Authors: Kurapati Siva N. V. R. K. , Lu Y. C.
Published: August 2009

The present paper presents a methodology to model the automotive engine components using newly developed viscoelastic gasket elements. The viscoelastic gasket element is one-dimensional element with load and deflection defined in the thickness direction only, thus has great computational efficiency. In addition, this element has the ability to incorporate the frequency-dependent viscoelastic properties of the materials and thus can be used to model the vibration and acoustic performance of the engines and subsystems. In the present study, an elastomer isolated engine cylinder-head cover assembly is modeled. The results obtained are consistent with the experimental measurements and with the work done earlier using viscoelastic shell elements.
Parametric Study on Beam Deflection Using Photostrictive Optical Actuators: A Finite Element Modeling Approach
Authors: Rahman Mosfequr , Jackson John E.
Published: August 2009

The objective of this work is to study the effect of three important parameters such as photostrictive actuator thickness, incident light intensity and convective heat transfer coefficient on a silicon cantilever beam with thin photostrictive optical actuator film surface. The authors have developed a computational method useful for design of systems incorporating thin film photostrictive actuators. The element has been implemented in an in-house finite element code named BAMAFEM. A finite element for static analysis of photostrictive thin films has already been developed and verified with analytical analysis approach of another author. To the best of our knowledge, finite element parametric analysis of the photostrictive thin film has not been extensively studied, if studied at all. Photostrictive materials, such as PLZT, demonstrate significant photostrictive behavior under illumination by high-energy light, which can be considered a superposition of a bulk photovoltaic effect and a converse piezoelectric effect. Photostrictive actuators can directly convert photonic energy to mechanical motion. Photostrictive materials can produce strain as a result of irradiation from high-intensity light. Neither electric lead wires nor electric circuits are required. Thus, photostrictive actuators are relatively immune from electrical interference. They have potential use in numerous MEMS devices. At least from the computational point of view, it would be interesting to investigate the effect of different parameters in the actuation of beam using the thin film photostrictive actuators to develop a finite element model useful for design of numerous MEMS and NANO systems having photostrictive actuators.
Comparison of the 4th Order Stream Function and 2nd Order Vorticity Transport Representations for Modeling Float-Zone Crystal Growth With a Constant Magnetic Field
Authors: Huang Yue , Houchens Brent C.
Published: August 2009

During optically heated float-zone crystal growth processing, a cylindrical melting zone forms from a polycrystalline rod by lateral heating, then re-solidifies into single crystal rod. Thermocapillary forces drive a flow in the melt region. This base flow is susceptible to instabilities, which lead to nonuniformities and defects in the crystal. In order to minimize these imperfections, a magnetic field is employed to damp the base flow within the melt region. Modeling this base flow has proven challenging, and two representations are discussed here. The float-zone crystal growth base flow under the influence of a constant magnetic field and neglecting buoyancy is investigated with a full-zone model. The flow field and temperature distributions are calculated by a steady state, axisymmetric spectral collocation method using Chebyshev polynomials as basis functions. A 2nd order vorticity transport representation is compared with a 4th order stream function formulation. The results show high consistency between the models.
Continuous Dielectrophoretic Separation of Multiple Particles in a Microfluidic Chip
Authors: Davidson Christian , Zhu Junjie , Xuan Xiangchun
Published: August 2009

We successfully demonstrate that DC dielectrophoresis can be utilized to separate particles of three dissimilar sizes simultaneously in a microfluidic chip. This continuous-flow separation is attributed to the particle size dependent dielectrophoretic force that is generated by the non-uniform electric field around a single insulating hurdle on the channel sidewall.
Vehicle State Estimation for Rollover Avoidance
Authors: Huang Jihua
Published: August 2009

To enhance vehicle/road safety, rollover warning and control systems have received considerable research interest in recent years, especially for vehicles with high center of gravity (CG). Accurate and reliable estimates of the relevant vehicle states facilitate the design of such systems. This paper investigates the state estimation for rollover avoidance, in which the relevant states include vehicle roll velocity and roll angle, as well as sideslip velocity and yaw velocity. The main challenge of the design comes from the fact that, under near-rollover situations, vehicle dynamics is complex and nonlinear. Not only vehicle suspension and tires are in their nonlinear region, but also vehicle yaw, sideslip and roll motions are highly coupled. In addition, the estimation needs to deal with sensor biases and sensor nonlinearity under this extreme condition. To address those issues, this paper proposes a vehicle state estimation design that consists of three parts: a sensor pre-filter, an Extended Kalman filter (EKF), and a sideslip velocity estimator. The sensor pre-processor removes sensor biases by utilizing the Recursive Least Square technique with a varying forgetting factor. The EKF is designed based on a linear yaw/sideslip/roll model, and its feedback gains are further scheduled based on vehicle lateral acceleration in order to reduce the effects of increased model inaccuracy as vehicle roll motion becomes more severe. The sideslip velocity estimator adjusts the sideslip velocity estimated by the EKF to extend the estimation to the nonlinear region. Both simulation and vehicle fishhook testing have been used to verify the effectiveness of the design.
Development of Technologies for Eliminating High-Level Noise Emitting Vehicles on Japanese Roads
Authors: Ishihama Masao , Kaneko Shigehiko , Kamata Minoru , Tanaka Takeharu , Sakamoto Ichiro
Published: August 2009

The purpose of the present study is to improve the on-street exhaust noise measurement technique for regulating vehicles that emit unacceptably large exhaust noise. The method under development uses racing operation of engines with a wide-open throttle on a standing vehicle. In contrast, the engine operation condition considered in the conventional on-street measurement technique considers operation at 75% of rated power followed by the throttle valve being released to its original position. The current regulation considers the maximum noise level during this engine operation condition. Accordingly, the engine is not loaded during testing. This loading condition provides unsatisfactory correlation between the exhaust noise level measured by the on-street method and the ISO vehicle acceleration noise under the wide-open throttle condition. The present paper reports the advantages of the proposed method as well as some important factors in the proper application of the newly proposed method. In the present study, we perform noise measurement along highways, a vehicle experiment in an anechoic chassis dynamometer, and computer simulations. The results revealed that the proposed on-street measurement method can be used to approximately determine the exhaust noise level during full acceleration for most vehicle types. In addition, the sensitivities of the measured noise levels for the testing conditions were clarified. The second item in this study is efficient engine speed measurement using exhaust sound signal only without electric wire harnessing. A survey of the measurement systems proposed by three different companies revealed that the measurement principles of two of these systems have potential application to on-street exhaust measurement. The last item investigated herein is better indices of exhaust noise evaluation. Loudness defined by ISO was found to be much better than the conventional dB(A) scale in terms of correlation with subjective evaluation results.
Study on Numerical Methods for Conjugate Heat Transfer Simulation of an Air Cooling Turbine
Authors: Wang Qiang , Zhou Chi , Guo Zhaoyuan , Yan Peigang , Feng Guotai , Wang Zhongqi
Published: August 2009

The effects of several numerical methods, including computational grids, coupling method, transition model and inner cooling air flow prediction, on the conjugate simulations were studied in the research. Firstly a finite difference conjugate solver was developed. Such solver included an N-S solver and a thermal conduction module for fluid flow and solid thermal conduction, respectively. Then conjugate simulations of an air cooling turbine were carried out. There were four kinds of conjugate simulations: the first one employs different types of computational grids, including H-type grids and O-type grids, for discretizing near-wall regions in fluid zone; the second one employs different coupling methods including indirect and direct ones; the third one employs different models including the B-L and q-ω turbulence models, and the AGS transition model; and the forth one employs different turbulence models for the prediction of flows in the cooling channels. All of the numerical results have been compared to the experimental result. Finally it concludes that to accurately predict thermal and aerodynamic load of the air cooled turbine, the conjugate simulation should employ O-type girds to discretize the near wall regions in the fluid zone, use the direct coupling method to transfer data between solid and fluid domains, and utilize the transition model to predict accurate flow details within the boundary layers, and also account for flows in the cooling air channels.
An Experimental Investigation on the Clocking Effect Between Inlet Guide Vanes and Vaned Diffuser in a Centrifugal Compressor Stage
Authors: Hua Jiang , Guang Xi , Wei Zhang , Gong WuQi , Wang ZhiHeng
Published: August 2009

Different circumferential angle positions between stator or rotor vane rows in turbomachinery can lead to different flow structures or stage performances. The clocking effect phenomenon has been detected in axial compressor and turbine by investigators, but rarely reported on centrifugal compressor. The present work is an experimental investigation on the stator clocking effect between inlet guide vanes (IGV) and vaned diffuser in a low-speed centrifugal compressor. The experimental rig consists of a circumferentially rotatable IGV, an unshrouded centrifugal impeller, a vaned diffuser, a volute and etc. The impeller diameter is 796mm, and the rotate speed is about 3100 rpm. At each inlet prewhirl angle of −20°, 0° and +20°, the stage performance curves are measured at three clocking angle positions of 0°, 8° and 16°. The result shows that at the circumferential angles of 0° and 8°, the efficiency curve has a double peak value feature, but at the angle of 16° being the conventional single peak value curve. Further, at the circumferential angles of 0° and 8°, the stage efficiency is bigger 3.6% than that case of the angle being 16°, where the IGV prewhirl angles are 0° and 20°. When the IGV prewhirl angle is changed into −20°, the stage efficiency increases about 2.0% near the first peak value position at the circumferential angles of 0°and 8° than at 16°, however, at the second peak value position, the stage efficiency at the circumferential angle of 0° is bigger about 1.4% than at 8° and 16°. Moreover, the circumferential angle positions between IGV and vaned diffuser have corresponding influence on the pressure ratio.
The Effect of Isolated Air Mass and Fuel/Air Ratio on the Efficiency of Isolated Combustion and Diluted Expansion (ICADE) I. C. Engine Cycle
Authors: Dhahad Hayder Abed , Khalil Kamal Ch.
Published: August 2009

The Isolated Combustion and Diluted Expansion (ICADE) internal combustion engine cycle combines the advantages of constant volume combustion of the Otto cycle with the high compression ratio of the Diesel cycle. In this work we studies the effect of Isolated air mass on the efficiency of the cycle, the analysis shown that the decrease of Isolated air mass will increase the efficiency of the cycle, the large dilution air mass will quenches all NOx forming reactions and reduce unburned hydrocarbons. Furthermore, the effect of Fuel / Air ratio on the efficiency studies the analysis shown that the increase of Fuel / Air ratio will increase efficiency of the cycle.
A Three-Dimensional Finite Element Stress Analysis of Plain-Woven CFRP Adhesive Laminated Plates and Hollow Cylinder Under Out-of-Plane Loading
Authors: Sawa Toshiyuki , Noshita Yukiya , Iwamoto Takeshi
Published: August 2009

Carbon-Fiber-Reinforced-Plastic (CFRP) laminates have been used extensively in many industrial applications because of their good mechanical properties, such as high specific strength and elastic modulus. However, when CFRP laminated plate is bent, cracks and delaminations occur at the interfaces where fiber orientations are changed. Therefore, it is important to know the stress distributions at the interfaces. In this study, the stress distributions of plain-woven CFRP adhesive laminated plates and hollow cylinder bonded reinforcements under out-of-plane loads are examined. Stress distributions in the CFRP laminated plates are analyzed using three-dimensional Finite Element Method. The effects of the thickness, stiffness and length of coating reinforcements are examined in the numerical calculations. The three point bending tests were carried out for the verifications of the FEM calculations. The strains at the interfaces, the deflection and the delaminations stress were measured under static out-of-plane loading. A fairly good agreement was seen between the FEM calculations and the experimental results concerning the strains and the deflections. Moreover, the mechanism of delaminations is examined using the interface stress distributions in the CFRP laminated plates.
Human Carotid Atherosclerotic Plaque Growth Function and Progression Simulation Using Meshless GFD and Statistical Methods Based on Multi-Year In Vivo MRI
Authors: Yang Chun , Petruccelli Joseph D. , Teng Zhongzhao , Yuan Chun , Canton Gador , Liu Fei , Hatsukami Thomas S. , Tang Dalin
Published: August 2009

Atherosclerotic plaque rupture and progression have been the focus of intensive investigations in recent years. The mechanisms governing plaque progression and rupture process are not well understood. Using computational models based on patient-specific multi-year in vivo MRI data, our recent results indicated that 18 out of 21 patients studied showed significant negative correlation between plaque progression measured by vessel wall thickness increase (WTI) and plaque wall (structural) stress (PWS) [1]. In this paper, a computational procedure based on meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data was introduced to simulate plaque progression. Participating patients were scanned three times (T1, T2, and T3, at intervals of approximately 18 months) to obtain plaque progression data. Vessel wall thickness (WT) changes were used as the measure for plaque progression. Starting from T2 plaque geometry, plaque progression was simulated by solving the solid model and adjusting wall thickness using plaque growth functions iteratively until time T3 is reached. Numerically simulated plaque progression showed very good agreement with actual plaque geometry at T3 given by MRI data. We believe this is the first time plaque progression simulation results based on multi-year patient-tracking data are reported. Multi-year tracking data and MRI-based progression simulation add time dimension to plaque vulnerability assessment and will improve prediction accuracy.
An Efficient Crashworthiness Design Optimization Approach for Frontal Automobile Structures
Authors: Kamel Hesham , Sedaghati Ramin , Medraj Mamoun
Published: August 2009

Nonlinear finite element simulation is the state of the art tool to assess the crashworthiness performance of current automobile design. Despite all the advancements in today’s computational capabilities, simulations are still extremely computationally expensive. Moreover design optimization for crashworthiness is a highly nonlinear mathematical problem in which both analysis and optimization components are nonlinear and involve highly iterative process. This makes design optimization process prohibitively possible due to the associated unrealistic computational cost. This paper presents a practical approach that enables the designer to conduct design optimization for crashworthiness at an affordable computational cost.
An Approach to Information Requirements Analysis for Holonic Manufacturing Systems Development
Authors: Farahani Manesh Hamed
Published: August 2009

This paper presets a methodology for representing a manufacturing System in order to help with the requirements analysis (RA) in Holonic Manufacturing Systems (HMS) development. The proposed methodology can reduce the cost and time involved at this stage by producing precise and accurate plans, specification requirements, and a design for HMS information systems. The dynamic activities, working mechanism of each holon, and relationships among holons are modeled using the Agent Unified Modeling Language (AUML) with Multi Agent Systems (MAS) approach. An experimental case study has been carried out in a firm in the die casting industry in order to demonstrate the features and the potential industrial application of presented methodology.
MEMS Modulated Retroreflectors for Secure Optical Communication
Authors: Bifano Thomas , Schatzberg Leah , Stewart Jason , Cornelissen Steven
Published: August 2009

Design, modeling, fabrication, and testing of a new type of optical communication node enabled by micromachined mirror is described. The micromirror device is capable of switching within 1μs between two states — one planar and reflective in the substrate surface normal direction and one corrugated and diffractive. It is used as one facet in a corner-cube retroreflector that can communicate by returning a temporally modulated beam to an interrogating laser transceiver. Design of a very low-cost device suitable for use as a communication node at ranges of several hundred meters is detailed. In particular, fabrication approaches are described for the micromirror that minimize the number of layers and process steps while employing scalable, high-volume thin film manufacturing. Ultimately, a process comprised of three thin film depositions, on lithographic patterning step, and one timed etch produces a robust and easily mass produced device. The devices that were tested featured up to 10:1 modulation of an incident beam in some configurations, and allow robust, secure optical switching through free space. Processes for combining the modulator with two orthogonal facets to comprise a retroreflector are described, and adequate orthogonality is demonstrated for communication over the intended range. Intrinsic stress behavior of tensile thin films are exploited to achieve nanometer scale flatness in the unactuated device, and a compact electronics driver is used to encode data and frequency modulate the active device. Electromechanical models that predict device behavior during electrostatic actuation are detailed. A functional prototype communication system using the modulated retroreflector and a telescope containing a 1.5μm wavelength laser and photodetector decoder is described, and secure communication is demonstrated over a free space path.
Design, Fabrication, and Testing of the Van Der Pauw Piezoresistive Structure for Pressure Sensing
Authors: Cassel Robert , Mian Ahsan
Published: August 2009

In our specific application of the van der Pauw (VDP) structure as a pressure sensor, where the stress field varies significantly, smaller VDP size is beneficial. The resistivity of the VDP sensor is affected by the stress state of the entire area over which it lies, providing a relation between resistance and the average stress in an area, rather than the stress at a point. The further the area over which the VDP lies is reduced, the closer we approximate the stress at a point rather than the average stress over a large surface. Due to microfabrication and other limitations, small, point-like sensors may not be feasible. In our study, a clear relationship between size and sensitivity could not be made. However, it was apparent that size had little overall effect on sensitivity. In testing the VDP devices for comparison with conventional sensor types, it was found that the VDP devices had a linear response as expected, were the most sensitive, and provided a number of additional advantages. Specifically, the VDP device allows for significant miniaturization, because its resistance value is independent of size, and the measurement technique is independent of line resistance. The simple geometry of the VDP also simplifies fabrication.
Sensor Diaphragm Under Initial Tension: Nonlinear Interactions During Asymmetric Oscillations
Authors: Long Xinhua , Yu Miao , Balachandran Balakumar
Published: August 2009

In this article, investigations into the nonlinear asymmetric vibrations of a pressure sensor diaphragm under initial tension are presented. A comprehensive mechanics model based on a plate with in-plane tension is presented and the effect of cubic nonlinearity is studied on the nonlinear asymmetric response when the excitation frequency is close to the natural frequency of an asymmetric mode of the plate. The obtained results show that in the presence of an internal resonance, depending on the initial tension, the response can have not only the form of a standing wave but also the form of a traveling wave. The results of this work should be relevant to diaphragm-type structures used in micro-scale sensors including pressure sensors.
Design and Manufacturing of the Injection Mold for Metal-Inserted Rubber Parts Using CAD/CAM/CAE Technologies: A Case Study of the Engine Mounting
Authors: Rodkwan Supasit , Chookaew Wacharapong , Panyawipart Rungtham , Raksiri Chana
Published: August 2009

In general, rubber parts used in automotive applications are designed and manufactured without any inserts; it is significant, however, that for certain parts, such as an engine mounting that, the metal core must be used to increase the compressive strength of products. With the lack of numerical tools used to predict the rubber flow characteristics and the interaction between rubber and metal insert during the molding process, mold designers must rely on their experience and the trial-and-error method to design molds. Therefore, in this research, an application of CAD/CAM/CAE on the design and manufacturing of an injection mold for the engine mounting rubber made of a blend of Natural Rubber (NR) and AcryloNitrile-Butadiene Rubber (NBR) is performed. A CAD model of the part is constructed and then a two-cavity mold as well as various runner patterns and gate positions are designed and further analyzed using CAE. Subsequently, with use of the CAM system, a metal-inserted mold and related components are manufactured and used to produce the rubber engine mounts on the vertical rubber injection machine. The empirical and numerical resulting parameters, including part geometry, injection pressure, and part temperature at various injection stages, correlate well. This information provides mold designers and manufacturers a better understanding of the rubber behavior during curing in the metal-inserted rubber molding process so that various mold components can properly designed and effectively used. Consequently, better mold and product quality with less defects as well as reduced production time can be obtained.
Molecular Dynamics Computation of Thermal Properties in Si/Ge Nanocomposites
Authors: Huang Xiaopeng , Huai Xiulan , Liang Shiqiang , Wang Xinwei , Li Ji
Published: August 2009

In this paper, an atomic scale study is carried out to characterize the thermal transport in Si/Ge nanocomposites by using the molecular dynamics (MD) simulation. The influence of size, heat flux, interface, as well as voids, on thermal properties and the inner temperature profiles of nanowire composites are studied. The results show that the thermal conductivity of nanowire composites is much lower than that of alloy, which accounts mainly for ZT enhancement and owes a great deal to the effect of interface thermal resistance. The results also indicate that a nonfourier phenomena what we call “reflecting effect” is remarkable at the Si/Ge interface, and the thermal conductivity is also dependent slightly on the bulk temperature and the specified heat flux in the range of selected system sizes and temperatures. It is also investigated that how the thermal conductivity of Si1−xGex composites changes with the atomic percentage x of germanium for wire dimension of LSi = 10 nm. Simulation results reveal that for a constant silicon wire dimension, the thermal conductivity of the Si/Ge nanocomposites increases with x. An attempt study on the influence of the voids on thermal conductivity shows that the thermal conductivity decreases with the void density. Most of the presented results from the simulations in this work come to favorable agreement with previous work, suggesting a good reliability of the present simulation method for further analysis of thermal transportation phenomena in nanocomposites and even more complex composites with pores, dislocations and impurities.
Conceptual Model Driven Architecture to Support Global Product Development
Authors: Pereda Javier , Hincapie Mauricio , Molina Arturo
Published: August 2009

For a rapid configuration of a given product development process, taking into account today unavoidable market’s requirements as is the integrated product, process and manufacturing system development considering their entire lifecycles, in this paper, an enterprise holistic framework, consisting in a three dimensional model, is described to support the model driven architecture (MDA) concept for global product development projects (GPDP). The holistic framework has been established based on the integration of three fundamental areas of research: concurrent engineering (CE), product lifecycle, and enterprise integration engineering (EIE). The integration of these three fields of knowledge, using a 3D holistic framework, generates a solid support for a model driven architecture. As a result, through a 3D matrix, more important elements of the product development process can be combined and modeled following their natural interactions through the project realization. Questions about a global product development project like: What needs to be developed? Who will develop it? Where will be developed? How will be developed? When is being developed? can be generated during the planning and execution of the project but, as part of this research effort, these questions are answered in an organized manner using the proposed enterprise holistic framework. The conceptual model (enterprise holistic framework) for the global product development project was established as a base to capture, store and configure a project including the integration of product, manufacturing process and manufacturing system development considering their entire lifecycles in the enterprise context.
On the Design of Robotic Fish Based on Lighthill’s Small-Amplitude Elongated Body Theory
Authors: Shahi Mohammad , Meghdari Ali
Published: August 2009

This paper addresses the issues of energy efficiency in robotic fish design by use of hydrodynamic models. The use of Lighthill’s small-amplitude elongated body theory for designing of robotic fish, obtaining optimal kinematics and dynamic analysis with emphasis on compliant mechanism is presented. Simulation results for a sample case have demonstrated the importance of proposed approach in robotic fish design.