bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Exchange Characteristics of a Gas-Gas Counterflow Microchannel Heat Exchanger
Authors: Koyama K. , Asako Y.
Published: August 2009

Heat exchange characteristics of a gas-gas counterflow microchannel heat exchanger have been investigated experimentally. The microchannel has a rectangular cross section with 200 μm high and 300 μm wide. Working fluid is air. Reynolds number in the hot passage ranges from 127 to 381, and that in the cold passage ranges from 25 to 381. Temperatures and pressures at inlets and outlets of the heat exchanger have been measured to obtain heat transfer rates and pressure losses. The heat exchange and the pressure loss characteristics of the tested microchannel heat exchanger are discussed. Since the partition wall of the heat exchanger is thick comparing with the microchannel dimensions, a simple heat exchange model, the wall temperature of which is constant, is proposed to predict the heat transfer rate. The predicted heat transfer rates are compared with those of the experimental results and both results agree well.
Mathematical Modeling of Passive Hydraulic Engine Mounts
Authors: Duan Shanzhong Shawn , Ries Andrew
Published: August 2009

Hydraulic engine mounts are widely used in automotive powertrain for vibration isolation. A lumped mechanical parameter model is a traditional approach for modeling and simulation of such mounts. This paper presents a mathematical model of passive hydraulic engine mounts with a double-chamber, an inertia track, a decoupler, and a plunger. The model is developed based on analogy between electrical systems and mechanical-hydraulic systems. The model is created to capture both the low and high frequency dynamic behavior of hydraulic mounts. The model will be further used to find the approximate pulse responses of the mounts in terms of the force transmission and top chamber pressure. The close form solution from the simplified linear model may provide some insight into the highly nonlinear behavior of the mounts. Various operational scenarios are also discussed.
MEMS Methanol Reformer Integrated With a Catalytic Combustor for a PEM Fuel Cell
Authors: Kim Taegyu , Kwon Sejin
Published: August 2009

This paper presents the development of a micro methanol reformer for a portable fuel cell power system. The micro methanol reformer consists of a methanol steam reformer, catalytic combustor, and heat-exchanger in-between. Cu/ZnO was selected as a catalyst for methanol steam reforming and Pt for catalytic combustion of hydrogen with air. Porous ceramic material was used as a catalyst support due to large surface area and thermal stability. Photosensitive glass wafers were selected as a structural material. Catalyst loaded supports were inserted in the cavity made on the glass wafer. The membrane heat-exchanger was manufactured to increase the heat transfer between the reformer and the combustor. Performance of reformer and combustor unit was measured at various test conditions and the optimum operation condition was sought. The micro methanol reformer was heated by the catalytic combustor that generated sufficient amount of heat to sustain the steam reforming of methanol. The micro methanol reformer generated 53.7 ml/min hydrogen and the conversion of methanol was 95.7%. The generated hydrogen can operate a 4.5 W polymer electrolyte membrane fuel cell.
An Internet-Based Quality Control Laboratory via Integration of Remote Robotic Operation and Nondestructive Ultrasound Evaluation
Authors: Chiou Richard , Genis Vladimir , Rosen Warren , Moulton Anthony , Kwon Yongjin
Published: August 2009

This paper discusses the integration of a remote robot laboratory with nondestructive ultrasound evaluation (NDE) experiments. A remotely automated quality inspection system is designed to analyze dimensions as well as detect internal flaws of parts via an Internet-based NDE system. The remote quality inspection system includes: Internet controllable robot via Ethernet connection, multiple Web-cameras, Ultrasonic Automatic Flaw Detector, LabVIEW module, and computers with Internet access capable of remote connection. The uniqueness of the project lies in making this process Internet-based and remote robot operated. An Internet-based procedure such as the one we are developing will allow industrial companies involved in NDE procedures to increase productivity and profits by allowing an employee to monitor multiple operations over the Internet without having to be at a specified location. In addition, the utilization of remotely controlled robots for educational purposes is expected to increase the degree of immersive presence of the students engaging in such Internet-based laboratory exercises as well as the level of online interactivity between the faculty and students.
Nonlinear Modeling and Surface Mounting Optimization for Extremely Large Deployable Mesh Antenna Reflectors
Authors: Yang Bingen , Shi Hang , Thomson Mark , Fang Houfei
Published: August 2009

Adaptive Surface Control (ASC) technologies are being developed to enable extremely large deployable high RF mesh antenna reflectors for future NASA missions. This paper presents the results that are obtained from an initial study on the ASC technologies for the mesh reflector. A three-dimensional nonlinear truss model is developed to describe large deformation of the reflector during deployment. The deployment process of the reflector involves mounting a network of truss elements on a rigid frame through use of tension ties. An initial profile of the undeformed truss structure is to be determined to achieve required surface accuracy after deployment. The mathematical description of this surface mounting leads to a nonlinear optimization problem. An iterative algorithm is devised to obtain the initial profile of the undeformed reflector. The proposed model and surface optimization algorithm are applied to an 835-node reflector. Numerical simulation shows that the algorithm converges fast at low computational costs, and that the solutions obtained are accurate to computer’s digits. The reflector model and surface optimization algorithm are readily applicable to adaptive surface control of the antenna reflector under thermal loads.
Structural Modeling and Dynamic Analysis of a Piezoelectric Forceps Actuator
Authors: Susanto Ken , Yang Bingen
Published: August 2009

A piezoelectric forceps actuator (PFA) is recently invented for potential use in minimum invasive and non-invasive surgery and diagnosis, and other biomedical applications. This paper is concerned with structural modeling, dynamic analysis, and feedback control of such an actuator. The PFA is modeled as a composite curved beam with laminated piezoelectric layers. The exact open-loop and closed-loop transfer functions of the PFA control system consisting of the curved beam, sensor, actuator and control logic are obtained in exact and closed form without discretization. With the transfer function formulation, the natural frequencies and frequency response of the actuator are then predicted and a simple feedback control law is implemented. The theoretical model of the actuator is validated in experiments.
On Modeling the Mechanical Behavior of Amorphous Polymers for the Micro-Hot-Embossing of Microfluidic Devices
Authors: Srivastava Vikas , Anand Lallit
Published: August 2009

In this paper, a brief summary of some of our recent work [1, 2] is presented, with the goal of developing an engineering science-based process-simulation capability for micro-hot-embossing of amorphous polymers. To achieve this goal: (i) a three-dimensional thermo-mechanically-coupled large deformation constitutive theory has been developed to model the temperature and rate-dependent elastic-viscoplastic response of amorphous polymers; (ii) the material parameters in the theory were calibrated by using new experimental data from a suite of simple compression tests on Zeonex-690R (cyclo-olefin polymer), that covers a wide range of temperatures and strain rates; (iii) the constitutive model was implemented in the finite element program ABAQUS/Explicit; and (iv) the predictive capability of the numerical simulation procedures were validated by comparing results from the simulation of a representative micro-hot-embossing process against corresponding results from a physical experiment.
Quasi-2D Monte Carlo Simulations of a Colloidal Dispersion Composed of Magnetic Plate-Like Particles With Magnetic Moment Normal to the Particle Axis
Authors: Satoh Akira , Sakuda Yasuhiro
Published: August 2009

We have investigated aggregation phenomena of a colloidal dispersion composed of magnetic plate-like particles by means of Monte Carlo simulations. Such plate-like particles have been modeled as disk-like particles which have a magnetic moment normal to the particle axis at the particle center, with the section shape of a spherocylinder. The main objective of the present study is to clarify the influences of magnetic field strength and magnetic interactions between particles on particle aggregation phenomena. We have concentrated our attention on a quasi-2D system from an application point of view such as development of surface changing technology using such magnetic plate-like particles. A magnetic field was applied along a direction perpendicular to the plane of the monolayer. Internal structures of particle aggregates have been discussed quantitatively in terms of radial distribution and orientational pair correlation functions. The main results obtained here are summarized as follows. For the case of strong magnetic interactions between particles, the particles form long column-like clusters with their magnetic moments alternating in direction between the neighboring particles. These tendencies appear under circumstances of a weak applied magnetic field. However, as the magnetic field strength increases, the particles incline toward the magnetic field direction, so that the particles do not form such clusters.
Experience in Developing and Teaching a General Education Course in Energy
Authors: Ganji Ahmad R.
Published: August 2009

A general education/non-major course has been developed and taught in the School of Engineering at San Francisco State University. The course enrollment has grown steadily in the past five years, and based on class evaluations, it has shown to be quite beneficial in educating non-major students on various aspects of energy, from energy resources to the consumption stages. Details on the reasoning behind, content and the administration of the course are presented in this paper.
Further Development and Preliminary Testing of the α-Prototype of an Ultra-Micro Gas Turbine for Portable Power Generation
Authors: Capata R. , Sciubba E.
Published: August 2009

The ever increasing development of portable electronics leads to a higher demand for compact and reliable power sources. Significant resources are being presently dedicated to the study of micro machined turbines, because of their remarkable power density that suggests that the generation of about 100–300 W with a total device weight of few hundreds grams and a fuel mass flow rate of few grams per second may be feasible in the short range. In this paper a possible configuration of such a nano-GT set is considered, which was defined on the basis of previous thermo-fluid dynamic analysis: the results of a preliminary design study, including some cold-run tests, are reported in this paper. The layout of the device was finalized on the basis of both a CFD and a FEM analysis that identified the “optimal” blade shape, shaft size and rotors arrangements under the point of view of the energy efficiency and of thermo-mechanical material stresses, Some of the problems deriving by the physical construction and preliminary testing of the prototype are analyzed and discussed.
Demystifying Thermodynamics by Connecting It With Mechanics
Authors: Dartnall W. John , Reizes John , Anstis Geoff
Published: August 2009

The laws of thermodynamics provide an adequate basis for the development of classical thermodynamics and for the many empirical relationships used by mechanical and chemical engineers. The laws evolved before the advent of the computer with its ability to handle complex simulations. This led to the classical structure that did not require a molecular view of matter. The concept of entropy grew out of this classical view but, has unfortunately earned a reputation for being something mysterious and difficult. Statistical mechanics, much of which is based on Newtonian mechanics, has the power to remove the mystery. But, because of its mathematical complexity, it has rarely been used by engineers either to clarify understanding or to analyze processes and models. We propose, illustrating with examples, that simple Newtonian mechanical models can be used in place of statistical mechanics — at least for the teaching of concepts. Surprisingly, the models developed using Newton’s three Laws allow the development of the zeroth, first and second laws of thermodynamics and the processes by which equilibrium is reached. We believe that in teaching thermodynamics the links with Newtonian mechanics would best be established by the proposed simple methods because of the resulting enlivening of Newtonian mechanics and the enhanced understanding of the fundamental concepts of thermodynamics.
Flame Stability of a Micro Can-Type Afterburner for a SOFC
Authors: Yahagi Yuji
Published: August 2009

This paper is fundamental studies on an afterburner for a 20kW class home cogeneration solid oxide fuel cell (SOFC) hybrid system. The proposed burner is a micro size can-type with a baffle plate having multi air holes set annularly and an opposite arranged single fuel and air nozzle in the center. This geometry is suitable to enhance the fuel and air mixing and to stabilize the flame in the ultra lean fuel of the effluent from SOFC stack in the MGT. The blow off limits and flame shape are discussed with the flow structure behind the baffle plate which measured by using a particle image velocimetry (PIV). The formed flames can be classified into four groups which are a premixed flame, a partially premixed flame, a partially nonpremixed flame, and a nonpremixed flame depend on the pilot air jet velocity, the baffle plate holes air jets velocity, and the clearance of the fuel nozzle exit and baffle plate, even when the flow rate of the fuel is same. When the premixed flame formed side by the fuel nozzle, the fuel is preheated approximately 750K. The counter-rotating vortices are formed behind the baffle plate and the vortices play a key role for the fuel and air mixing as well as the flame stabilization. The pilot jet not only controlled the flame position but also enhanced the fuel and air mixing. Especially, the pilot jet is important to form the premixed flame near the blow off conditions, and the desirable velocity is close to the air jets velocity of the baffle plate holes. However, there are some ineffective conditions for the pilot air jet.
Process Analysis for Ultrasonic Welding of Thermoplastics
Authors: Ling S.-F. , Li X. , Sun Z.
Published: August 2009

Ultrasonic welding is one of the most popular techniques for joining thermoplastics. In this paper, a process analysis was conducted to describe the ultrasonic welding mechanism for thermoplastics. An in-situ sensor-less method was used to measure the welding force and the velocity applied to the workpiece. Using this method, the mechanical impedance variation and the force versus displacement curve at any time during ultrasonic welding can be generated and quantified. A detailed description of ultrasonic welding process for thermoplastics was then proposed based on the experimental data obtained. In this description, the welding process is divided into four distinct phases: the viscoelastic-plastic phase, the energy director melting phase, the melting completing phase and the upper & lower parts coupling phase. The process analysis clearly reveals that the mechanical impedance at the joint interface is the most characteristic variable of ultrasonic welding. Both the analysis method and the description of the process in the study are demonstrated to be useful tools for better understanding of ultrasonic welding mechanism.
Burning Profile of High Ash Indian Coals in Oxy-Fuel Environment
Authors: Saravanan V. , Aravind Arun , Jayanti Sreenivas , Ramakrishna
Published: August 2009

Oxy-fuel combustion is one of the emerging technologies to capture and store CO2 emissions generated from thermal power plants. Research programs are in full swing to find out the possibility of retrofitting existing coal fired power plants with oxy-fuel mode combustion. Most of the Indian thermal power plants are pulverized coal based and use sub-bituminous Indian coals. These coals differ from the foreign coals in respect of maceral composition, ash content and combustion kinetics. It is imperative to understand the burning characteristics of Indian coals in oxy-fuel environment to evolve the suitable design for the retrofit of Indian boilers with oxy-fuel mode for the efficient and economic carbon capture without losing thermal efficiency. The present study involves the assessment of the kinetics of pyrolysis and char oxidation of three different Indian coals with varying ash contents viz. 33 to 44% in normal air and in oxy-fuel environment with three different CO2/O2 concentrations (60:40, 70:30 and 80:20) by Thermo Gravimetric method (TGA). The results are compared in respect of weight loss pattern, peaking temperatures and weighted mean activation energy. The results have shown that the combustion kinetics of the selected high ash Indian coals in normal air combustion is more comparable with 70:30 and 80:20 than 60:40 CO2/O2 concentrations. The methodology adopted in the present study is found useful for comparing the combustion kinetics of various types of coals in normal air and oxy-fuel environment.
Trajectory Tracking for Two-Link Flexible Arm via Two-Time Scale and Boundary Control Methods
Authors: Ashayeri A. , Eghtesad M. , Farid M.
Published: August 2009

Main purpose of the study presented in this paper is to demonstrate the boundary controllers design by singular perturbation approach for trajectory tracking of two-link flexible arm. Applying the two-time scale control theory on the nonlinear PDE model, a control scheme is elaborated which makes hubs’ angles track a desired trajectory while damping out the links vibration. In the proposed controller, fast (flexible) subsystem controller will damp out the vibration of the flexible links by a Lyapunov-type design and the other slow (rigid) subsystem Inverse Dynamic controller dominates the trajectory tracking. These two controllers constitute the composite control scheme. The method does not require any information about the vibration of the links along the links for the proposed fast control law as well as discretizing the PDE of arm vibration to set of ODEs. Therefore, the method excludes the effect of both observation and control spillover instability. The simulation results confirm that the proposed boundary controllers are quite effective in performance.
Further Validation of the Ford Human Body FE Model and Use of the Model to Investigate the Effects of Shoulder Belt Force Limiting of 3-Point and 4-Point Restraints in Frontal Impact
Authors: El-Jawahri Raed E. , Ruan Jesse S. , Rouhana Stephen W. , Barbat Saeed D. , Prasad Priya
Published: August 2009

Ford Motor Company human body FE model was validated against 3-point & 4-point belted PMHS tests in frontal impact and PMHS knee impact. The chest deflection, chest acceleration, and belt force in frontal impact simulations were compared with the PMHS test data, while the impact force, femur acceleration, pelvis acceleration, and sacrum acceleration of the knee impact simulations were compared with the respective corridors from PMHS tests. The model used represents a 50th percentile adult male. It was used to study the effects of shoulder belt force limit on 3-point and 4-point restrained occupants in frontal impacts without airbags. A 25 g pulse and a shoulder belt load limit of 1, 2, 3, 4, 6, and 8 kN were used for the 3-point and 4-point restraint systems with a rigid steering wheel, front header, and windshield of a stiffer larger vehicle structure. The results showed that the head acceleration and the chest deflection of the 4-point belt system are less than the respective cases of the 3-point system while the chest acceleration levels were about the same in 3-point and 4-point belt. The mid-shaft femur forces were always higher in the 4-point belt than those of the 3-point belt.
A Screw-Gas Bulk Sucking and Taking Equipment
Authors: Li Yu , Li Yongzhi , Chen Dingfang
Published: August 2009

Among the whole ship unloading process, how to effectively and conveniently put the bulk into the ship-unloader is often a big and key problem. This article advance a new equipment to solve the problem—Screw-gas Bulk Sucking and Taking Equipment, which applies both the theory of vertical screw conveyor and the theory of pneumatic handling. The author describes the constitution of the equipment and explains the working principles in detail, by thus pointing out the superiorities of the equipment, such as low clearing-up, little dust removal, simple construction and convenient maintenance. The article also brings tentative data for proof. The article gives a good solution by providing with a brand-new equipment—Screw-gas Bulk Sucking and Taking Equipment, which applies both the theory of vertical screw conveyor and the theory of pneumatic handling. It constitutes of 3 parts; respectively from bottom to above they are: Centrifugal force Separating Part, Screw Lifting Part and Pneumatic Conveying Part. Granular material is drawn into the equipment in the form of gas-solid two-phase flow by the Atmospheric pressure, and then helically rises in the Centrifugal Force Separating Part which is an inverted cone. The material would be separated from the two-phase flow by the effect of centrifugal force and then be lifted in the Screw Lifting Part. The gas flow with the very little remained material would be drawn into the blower. By thus Screw-gas Bulk Sucking and Taking Equipment could take the material and put it to the next conveying process conveniently and efficiently with the superiorities of low clearing-up, little dust removal, simple construction and convenient maintenance.
Perturbation/Correlation Based Optimization and its Application to Internal Combustion Engines
Authors: Lee Sooyong , Park Shinsuk
Published: August 2009

This paper addresses the application of the perturbation/correlation method to optimizing the torque output of internal combustion engines. This application was inspired by observations of the limitations in current techniques of the automotive performance tuning industry. The engine simulated is the Cooperative Fuel Research Engine, which is an industry standard testing engine. Issues such as selection of parameter perturbation frequency and amplitude are addressed as well their effect on input parameter stability. Based on these parameters, a basis for correlation multiplication terms will be chosen. Performance issues to take into consideration are errors from true optimum spark timing and fuel injector pulse width values as well as convergence. The ability of the system to deal with engine cycle to cycle variations and its effect on input parameters is also analyzed.
Investigation of Device Interactions Between Two MOSFETs in Si CMOS
Authors: Hatakeyama T. , Fushinobu K. , Okazaki K.
Published: August 2009

Experimental works about the device interactions between nMOS and pMOS in bulk Si CMOS were performed. In the bulk Si CMOS, in the case that the distance between two MOSFETs is not enough, it is important to consider the risk of the device interactions between nMOS and pMOS. In this work, we fabricated bulk Si CMOS, in which the distance between pMOS and nMOS can be variable. And we observed the characteristics of the device operation by using fabricated CMOS under the dc bias condition. In this research, we focused on the leakage current between two MOSFETs in CMOS inverter depending on the distance between two MOSFETs, applied voltage and temperature. Experimental results showed that our fabricated CMOS shows quite small leakage current and the leakage current is less than 1% compared to CMOS on state current even with small distance between two MOSFETs at the high voltage condition and the high temperature condition.
A Neural Networks Based on Structural Characteristics of Cerebral Neocortex
Authors: Hasegawa Ryo , Shiraishi Toshihiko , Morishita Shin
Published: August 2009

Artificial neural networks have been applied to pattern recognition, prediction and control because they have abilities of learning, generalization and nonlinear mapping. These conventional neural networks have not had “intelligence” yet. In pattern recognition, the recognition rate can be low when there are some noises in recognized patterns. Not so many neural networks have been reported that introduce the structural and functional characteristics of the brain obtained by the progress of neurophysiology. In this study, we focused on the cerebral neocortex, which is the most developed in human to be compared with the other animals and deals with recognition, language and imagination, introduced its characteristics of uniform, hierarchical, column structures and six layers to neural networks and investigated the possibility of emerging its functional characteristics of the human brain.
Effects of Acceleration Amplitude and Frequency of Mechanical Vibration on Cultured Osteoblasts
Authors: Shikata Tetsuo , Shiraishi Toshihiko , Morishita Shin , Takeuchi Ryohei
Published: August 2009

This paper describes the effects of the frequency and acceleration amplitude of mechanical vibration on osteoblasts, the bone cells that generate the bone matrix. Their cell proliferation and bone matrix generation were investigated when sinusoidal inertia force was applied to the cells. Bone formation is subject in vivo to mechanical stimulation. Although many researches for bone cells of osteoblastic lineage sensing and responding to mechanical stimulation have been reported mainly in the biochemical field, effects of mechanical stimulation on bone cells are not well understood. After the cells were cultured in culture plates in a CO2 incubator for one day and adhered on the cultured plane, vibrating groups of the culture plates were set on an aluminum plate attached to a exciter and cultured under sinusoidal excitation in another incubator separated from non-vibrating groups of the culture plates. Acceleration amplitude and frequency were set to several kinds of conditions. The time evolution of cell density was obtained by counting the number of cells with a hemocytometer. Calcium salts generated by the cells were observed by being stained with alizarin red S solution and their images were captured with a CCD camera. The vibrating groups for the cell proliferation and the calcium salts staining were sinusoidally excited for 24 hours a day during 28 days of culture. Gene expression of alkaline phosphatase (ALP) and runt-related gene 2 (Runx2) was measured by a real-time reverse transcription polymerase chain reaction (real-time RT-PCR) method. After the vibrating groups for the PCR were excited for 4 days, the total RNAs were extracted. After reverse transcription, real-time RT-PCR was performed. Gene expression for ALP, Runx2, and a housekeeping gene were determined simultaneously for each sample. ALP and Runx2 gene level in each sample was normalized to the measured housekeeping gene level. The following experimental results of sinusoidal excitation of osteoblasts have been shown: (a) Cell density decreased at 0.5 G with increasing frequency in the range from 12.5 to 1000 Hz and increased at 25 Hz with increasing acceleration amplitude from 0 to 0.5 G at 14 days of culture. (b) No calcium salts were observed in the non-vibrating group and the areas of calcium salts observed in the 0.5 G vibration group were larger than those in the 0.25 G group at 25 Hz at 21 days of culture. (c) The mRNA level of ALP at 0.5 G showed the peak at 50 Hz in the range from 12.5 to 1000 Hz and that at 50 Hz showed the peak at 0.5 G in the range from 0.25 to 1 G at 4 days of culture. In the case of Runx2, the same tendency was found. It has been shown that it is important to consider mechanical vibration as well as biochemical aspects in studies of the functional adaptation of cells to mechanical stimulation.
Design and Development of an Improved Air Distributor for a Large Coal-Fired Fluidised Bed Combustor
Authors: Ward John , Garwood Roy , Bowen Randall , Fisher Maurice , Gent David
Published: August 2009

The air distribution system in a fluidised bed combustor is usually required to provide a reasonably uniform distribution of combustion air over the cross-sectional area of the entire bed. Various designs of distributor have been employed and one of the simplest and cheapest constructions is the so-called sparge pipe system, in which an array of horizontal pipes is fitted near the base of the bed. Combustion air is then supplied to one end of each pipe and enters the bed through a series of downward facing holes positioned along the pipe length. This paper describes the re-design and subsequent modification of an existing sparge pipe distributor for a large coal fired fluidised bed combustor which produced hot exhaust gases for drying of pressed sugar beet pulp. The air flow out of the holes in the existing pipes varied by a factor of approximately 3.8:1 along the length and moreover the overall flow was limited by the high pressure drop within the system. As a result the thermal output of the combustor cannot always meet the demands of the drying process. Excessive erosion and wear of the walls of the pipes near some of the holes can also be a problem. A computational fluid dynamics (CFD) study was undertaken of the flow characteristics of different designs of sparge pipe and the results validated by flow and pressure measurements on full scale laboratory models. The flow distribution was substantially improved and the overall flow rate increased by approximately 7% by varying the hole diameters and spacings between adjacent holes. In addition much greater increases in predicted overall flow rates can be achieved by reducing the thickness of the pipe wall (whilst maintaining a constant outer diameter) although this may reduce the operating life of the pipe because of erosion and excessive wear. Erosion of the outside of the pipes was studied in near ambient temperature fluidised beds using multiple thin layers of different coloured paints on the outside of the pipes to assess the wear patterns. These patterns were found to be similar to those observed on actual sparge pipes at the end of an operating campaign. Quantitative measurements of the rate of wear of the paint layers indicated that pipe wall erosion can be substantially reduced by reducing the angle of inclination of the downward facing holes in the pipes.
Optofluidic Surface Enhanced Raman Scattering Chip for Detection of Dengue Virus
Authors: Huh Yun Suk , Chung Aram J. , Cordovez Bernardo , Erickson David
Published: August 2009

In this work we describe the development of an optofluidic device for surface enhanced Raman scattering (SERS) based detection of biological pathogens. The chip exploits the use of electro-active microwells which serve to both physically concentrate the Raman enhancers and to reduce the total analysis time through a unique electrokinetically driven on-chip mixing effect. To quantify the concentration performance of the device we use 44 nm polystyrene particles at low electric field strength (between 1.00–2.00 V) and demonstrate close to 90% concentration saturation within 2.5 s. We demonstrate the mixing capability through the enhanced detection of dengue virus serotype 2 (DENV-2). With DENV-2, we successfully detected the SERS signals with a limit of detection of 30 pM.
Numerical Simulation of the Power Shift Drive (PSD)-Axle in the Forklift
Authors: Park Sung-Moon , Park Tae-Won , Lee Soo-Ho , Jun Kab-Jin , Jung Sung-Pil , Park Joong-Soon
Published: August 2009

In this study, a new concept of power delivery system is developed. Power Shift Drive (PSD)-Axle vehicle modeling and dynamic movement analysis are performed by simulation. The dynamic vehicle model is constructed from data obtained from the derived equation, considering the specific characteristic of each part. The model is composed of a torque converter, a gear box, a differential, hub reduction and an engine, which is the power source of the 1st forward and reverse PSD-Axle, as the principle parts. By unifying the mathematical equation of each component, a mathematical model of the 1st forward gear is derived. The system dynamic model is created using Matlab/Simulink based on the mathematical model. Simulation is carried out using simulink to estimate the dynamic behavior of the PSD-Axle. Also, the dynamo test result is used to verify the reliability of the system dynamic model. This study can be used to establish the basic design concept for the forward and reverse PSD-Axle multi gear system.
CFD Based Prediction Method of Thrombus Formation in Shear Flow and Its Validation
Authors: Tamagawa Masaaki , Nagahama Sho
Published: August 2009

This paper describes development of the prediction method of thrombus formation by Computational Fluid Dynamics (CFD) on pipe orifice shear flows. These shear flows are typical models of the flow in the rotary blood pump. In this investigation, the thrombus formation in blood plasma flow is visualized, and modified lattice Boltzmann method are used to predict the backward forwarding step flow, that is simple model of the orifice flow.
Thermal Transport From Gold Nanorod to Solvent, an Investigation of Ligand Effects by Ultrafast Laser Spectroscopy
Authors: Alper Joshua , Schmidt Aaron , Hamad-Schifferli Kimberly
Published: August 2009

To facilitate analysis of nanoscale heat transfer in nanoparticle systems the thermal properties of ligand layers must be understood. To this end, we use an optical pump-probe technique to study the thermal transport across ligands on gold nanorods and into the solvent. We find that varying properties of the ligand can have large impacts on the thermal decay of a nanorod after exposure to a laser pulse. By raising the concentration of free CTAB from 1 mM and 10 mM in solutions, the CTAB layer’s effective thermal interface conductance increases three fold. The transition occurs near the CTAB critical micelle concentration. Similar results are found for other ligand layers.
Planar Robotic Systems for Upper-Limb Post-Stroke Rehabilitation
Authors: Rosati Giulio , Secoli Riccardo , Zanotto Damiano , Rossi Aldo , Boschetti Giovanni
Published: August 2009

Rehabilitation is the only way to promote recovery of lost function in post-stroke hemiplegic subjects, leading to independence and early reintegration into social and domestic life. In particular, upper limb rehabilitation is fundamental to regain ability in Activities of Daily Living (ADLs). Robot-aided rehabilitation is an emerging field seeking to employ leading-edge robotic systems to increase patient recovery in the rehabilitation treatment. Even though the effectiveness of robotic therapy is still being discussed, the use of robotic devices can increase therapists’ efficiency by alleviating the labor-intensive aspects of physical rehabilitation, and can produce a reduction in treatment costs. This paper presents a comparison between different planar robotic devices designed for upper-limb rehabilitation in chronic patients. A planar configuration of the workspace leads to straightforward mechanical and control system design, and allows to define very simple and understandable treatment exercises. Also, the graphical user interface becomes very intuitive for the patient, and a set of Cartesian-based measures of the patient’s performance can be defined easily. In the paper, SCARA (Selective Compliance Assembly Robot Arm) robots such as the MIT-Manus, Cartesian robots and cable-driven robots are considered and compared in terms of inertial properties and force exertion capabilities. Two cable-driven devices, designed at the Robotics Lab of the Department if Innovation In Mechanics and Management, University of Padua, Italy, are presented for the first time. The first robot employs four driven cables to produce a planar force on the end-effector, whereas the second one is based on a three-cable configuration plus a linear actuator to obtain better overall robot performance.
An Innovative Micro Control System for Quasi-Continuous Power Transmission Systems (QCPTS)
Authors: Nasr Asghar , Jozani Yaser Jafari , Ghazvini Mohsen
Published: August 2009

Ordinary stepped power transmission systems that used in industry, exhibit abundant energy dissipation, complicated handling and costly maintenance. On the other hand, continuously-variable power transmissions (CVTs), which are recently considered to be used in the industry, despite their high capabilities, face a number of drawbacks including such as : limited torque transmission capacity, high-precision manufacturing and installation requirements, low cost effectiveness and relatively modest power transmission efficiencies. Therefore, innovative power transmission systems that intend to resolve or lessen one or more of these disadvantages are critical in power transmission from pinion to wheel in electric traction motors (motors) of both diesel and electric locomotives; especially when active and advanced control of traction effort and adhesion is of high importance and are going to be welcomed by rail industries. The controlling subsystem of QCPTS includes a micro control system consisting of rotational velocity sensor, power supplier source, and intelligent pins. In each rotational velocity range the velocity sensor sends a signal to the micro controller for processing which causes one intelligent pins become activated and the previously activated pin become deactivated simultaneously. As a result, depending on the rotational velocity change of the rotating output shaft the QCPTS engages a pair of gears. The intelligent magnetic pins have two Start and End work stations. The Start station activates the gear by receiving a starting signal from micro controller and also the End station deactivates the gear by receiving the End signal from micro.
Math and Science Education Comparisons Between the United States and the Rest of the World
Authors: Wong Kaufui V. , Do Baochan D. , Hagen William
Published: August 2009

At the end of secondary education, the students of the United States are behind most advanced countries in science and mathematics. The main problem lies in the fact that the United States education system does not have a clear focus in their teaching of math and science through primary and secondary schools. According to the United States Department of Education, only 22 of the 50 states in the U.S. require that three years of math and science be taught in order to graduate from high school. This puts students of the United States at a disadvantage against the rest of the competitors on the global marketplace. This lack of uniformity in the United States is the reason that high school graduates are behind other developed countries in their math and science scores and subsequently less Americans are graduating from universities in the sciences. These facts could contribute detrimentally to the economic progress in the United States. To remedy this lack of American scientists and engineers, the United States needs to have a comprehensive system to encourage the study of math and science from primary school all the way to implementation in the economic marketplace.
A Non-Local Visco-Plastic Model With Strain Laplacian Effects and Interphase Effects for Simulating the Stiffness and Yield Strength of a Class of Polymer Nanocomposites
Authors: Li Yaning , Waas Anthony M. , Arruda Ellen M.
Published: August 2009

Numerical simulation of nanocomposite mechanics Representative Volume Elements (RVE) that include nanostructural information is a powerful and popular current approach. However, some limitations exist for this method, for example, the large difference between the Young’s moduli of the nanoparticles and the matrix materials causes large strain gradients around the nanoparticles or effective particles which presents numerical difficulties. Also the nanoscale mesh size requires extremely small time steps and therefore high computational costs, especially for dynamic simulations. In the present investigation, an analytical constitutive model is developed by adding the interphase effects and strain gradient effects to a classic spring-dashpot viscoplastic model of polymers. It is shown that this model can predict the constitutive behavior quantitatively. The mechanism of a brittle to ductile transition can also be captured and studied. Useful information for material design can be obtained through parameter study of the current model.
A BPTT-Like Optimal Control Algorithm With Vehicle Dynamics Control Application
Authors: Kasac J. , Deur J. , Novakovic B. , Kolmanovsky I.
Published: August 2009

The paper presents a gradient-based numerical algorithm for optimal control of nonlinear multivariable systems with control and state vectors constraints. The algorithm has a backward-in-time recurrent structure similar to the backpropagation-through-time (BPTT) algorithm, which is mostly used as a learning algorithm for dynamic neural networks. This paper presents an enhancement of the basic optimization algorithm. Our enhanced algorithm uses high-order Adams time-discretization schemes instead of the basic Euler discretization method, and a numerical calculation of Jacobians as an alternative to analytical Jacobians. Two examples are considered to illustrate the algorithm and its performance. The first example is that of a tubular reactor, for which an analytical solution is available, which can be readily used for validation of our approach. The second example is related to controlling vehicle dynamics based on a realistic high order model.
Complete Modeling of a Light-Pipe Radiation Thermometer in a Rapid Thermal Processing System
Authors: Erturk Hakan , Howell John R.
Published: August 2009

Light-pipe radiation thermometers are predominantly used to monitor wafer temperature during rapid thermal processing (RTP) of semiconductors. The processes used in fabrication of semiconductor devices during rapid thermal processing are extremely temperature sensitive and the errors associated with light-pipe measurements are great concerns across the industry. Modeling of the light-pipes has helped in understanding the signal transport process and errors associated with the light pipe measurements. However, due to the smaller size of the light-pipe sensor area with respect to the total system area, full scale modeling of such a system including the light pipe thermometer has not been possible due to the computational demand. In this paper, the reverse Monte Carlo method is used to model the signal transport through a light-pipe thermometer used in a RTP system. The Monte Carlo model considers the spectral and angular dependent optical properties of the chamber and quartz materials. The reverse Monte Carlo model is applied to the full scale instrumented system with characteristics of a RTP system with a quartz light pipe probe and the results are compared against previously published measurements from the same system.
Analytical Model for Thermal Warpage History of Laminated PBGAs
Authors: Munday Lynn , Keller Norman , Dasgupta Abhijit , Han Bong-Tae
Published: August 2009

Thermally induced warpage can lead to deformed or bridged solder joints during reflow of large laminate-based area-array components like high I/O PBGAs. This study presents a simple, rapid-assessment modeling capability to assess the warpage risk of such components, based on their architecture information. A piece-wise, classical laminated plate model is used in this study for estimation of the thermally induced warpage. This model uses temperature-dependent elastic properties to account for the large change in material behavior as the reflow temperature exceeds the glass-transition temperatures of the various polymers (substrate, die attach and epoxy molding compound). The laminated plate modeling strategy provides the capability to handle complex component architectures and temperature gradients in the thickness direction. The piecewise modeling strategy allows the model to account for the changes in the stack-up as we move from under the die footprint to the region outside the footprint. Several test cases are examined during the model development. Results are compared to detailed finite element models, as well as to other analytical methods like finite-length plate models. The model is found to be very sensitive to the thermo-mechanical properties of common epoxy molding compounds (EMCs) above their glass transition temperature. Since the model approximates a complex viscoplastic problem with an equivalent temperature-dependent elastic formulation, part of the focus is on developing equivalent temperature-dependent material properties to calibrate the model. The goal in this approximation is to find a suitably smooth transition between the material properties below and above Tg, based on the discrete properties typically found in data sheets. The trends predicted by this simplified model are also found to agree well with shadow moire measurements of warpage in actual components during large temperature excursions.
Systematic Characterization of Coupled Structural-Acoustic Systems With the Aid of Temporal and Spectral (Complex) Proper Orthogonal Decomposition
Authors: Papadopoulos Christos I. , Georgiou Ioannis T.
Published: August 2009

We extend the application of temporal and spectral Proper Orthogonal Decomposition (POD) to study the sound propagation and sound-structure interaction of systems combined of acoustic and structural subsystems. We consider a prototypical system consisted of two adjacent rooms separated by a sound insulating plate. Approximation to the steady-state and transient response is obtained with the aid of the finite element method. We define the temporal (real) and spectral (complex) variations of POD to tackle acoustical and structural degrees of freedom. We apply the method to process the numerical databases of the finite element solutions. It is shown that the steady-state and transient response may be represented by a small number of dominant POD modes. The extracted frequencies and spatial shapes are evaluated and linked to the modal properties of the system. It is shown that POD analysis may provide significant insight on the properties of coupled structural-acoustic systems.
Stepladders: Why They’re Not Safe
Authors: Seluga K. J. , Baker L. L. , Ojalvo I. U.
Published: August 2009

The US Consumer Product Safety Commission (CPSC) estimates that there are approximately 180,000 serious ladder accidents in the US each year. Stepladders are one of the most common types of ladders in use, and it is estimated that they are involved in over half of all incidents. Therefore, it is important to determine the root causes of these accidents and what, if anything, can be done to improve ladder safety by way of design and standard testing requirements. Herein, we discuss common failure modes experienced during use, current design standards promulgated by the American National Standards Institute (ANSI) A14 Standards Committee, complications which are not explicitly addressed in these standards, and design and manufacturing practices employed in stepladders produced for the US market. Finally, we propose a number of potential safety improvements to the current design of and safety standards for stepladders, though further research may be necessary to quantify specific design recommendations.