bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Stiffness and Damping Control of Air Mounted/Suspended Systems
Authors: Mahmoudian Pooya , Kashani Reza
Published: August 2009

Passive mounts/springs with negligible damping and low stiffness are highly effective in isolating vibration but have poor shock isolation characteristics. This and other contradictory traits of passive mounts, make the realization of an ideal, uncompromised isolation system unfeasible. To avoid an isolation system design based on a compromise among its conflicting requirements, a degree of real-time, on-demand adjustability should be built into the mounting system. Air springs/mounts, because of their inherent adjustability, are the best candidate for such adjustable isolation; other passive mounts, e.g. elastomeric, would require the introduction of an additional active element/actuator to work in parallel with the mount. In this proposed adjustable air mounting system, shock isolation can be enhanced without undermining the vibration isolation effectiveness by using an on-demand, active damping scheme which adds various levels of damping to an air mounted/suspension application, e.g., the cab in a truck, depending on the instantaneous urgency of shock isolation over vibration isolation. In addition, the proposed adjustable isolation scheme contains an on-demand, active stiffness control working in parallel with the active damping scheme. Depending on the operating conditions, the stiffness of the mount will be lowered to better its vibration isolation or increased to enhance its shock isolation. The active damping and stiffness control along with other on-demand adjustment tactics for an air isolation system are described, numerically examined, and experimentally demonstrated.
Sensorless Detection of Impeller Cracks in Motor Driven Centrifugal Pumps
Authors: Harihara Parasuram P. , Parlos Alexander G.
Published: August 2009

Electrical signal analysis has been in use for quite some time to detect and diagnose induction motor faults. In most industrial applications, induction motors are used to drive dynamic loads such as pumps, compressors, fans, etc. Failure of either the motors or the driven loads results in an unscheduled downtime which in turn leads to loss of production. These operational disruptions could be avoided if the equipment degradation is detected in its early stages prior to reaching catastrophic failure conditions. Hence the need arises for cost-effective detection schemes not only for assessing the condition of electric motors but also the driven loads. This paper presents an experimentally demonstrated sensor-less approach to detect impeller cracks in centrifugal pumps. The proposed method is sensorless in the sense that it does not use any mechanical and/or process pump sensors to detect impeller faults. Rather motor electrical measurements are used for the intended purpose. Mechanical sensors have high costs and low reliability, and frequently fail more often than the system being monitored. Hence add-on mechanical sensors reduce the overall system reliability. In this study, fault detection is accomplished using only the line voltages and phase currents of the electric motor driving the pump. The developed detection algorithm is insensitive to electrical power supply and load variations. Furthermore, it does not require prior knowledge of either a motor or the pump model or design parameters and hence the detection algorithm can be easily ported to motor-pump systems of varying manufacturers and sizes. The proposed fault detection scheme has been tested on data collected from a centrifugal pump driven by a 3-φ, 3 hp induction motor. Several cracks on the pump impeller are staged to validate the detection effectiveness of the proposed scheme and compare its effectiveness with respect to continuous vibration monitoring. In addition to these staged faults, experiments are also conducted to demonstrate the prevention of false alarms by the algorithm. Results from all of these experiments are presented to substantiate the performance of the sensorless pump fault detection scheme.
Numerical Simulation of the Effects of Pulverized Coal Concentration on Coal Ignition by High Temperature Air
Authors: Kang Zhi-Zhong , Sun Bao-Min
Published: August 2009

In China, over 70 percent of the power production feeds on thermal power plants running with pulverized coal (PC) fired boilers. Millions of tons of oil is consumed annually to ignite PC when the boiler starts up, as well as to stabilize the combustion. In this paper, one oil-free ignition technique is studied for oil-saving, in which high temperature air is used to ignite PC. As a key parameter, the effects of PC concentration on the ignition of PC are investigated by means of particular numerical simulations of FLUENT5.3. Under the given conditions of coal analysis, the author simulates the effects of different PC concentrations on ignition process, including ignition distance, temperature of flame and gas components. Part of the simulation results has the same tendency as the experimental data. The research provides guidance for structure improvement and operation optimization of the oil-free ignition burner by high temperature air.
An Assessment of the Relative Value of Knowledge Transfer Processes to Project Success
Authors: Pantelides Arthur , Allario Frank , Antony Gerhard
Published: August 2009

As activities of companies become global there is an emerging need to understand the processes that lead to the success of large projects in which the core competency is centered in a parent company; an engineering department in a foreign subsidiary; and customers that are distributed across the globe. This situation requires an ever-increasing role for project managers (PM) to cross international boundaries. The modern PM must consider many facets of their responsibilities including: managing corporate knowledge as a strategic asset; transferring corporate knowledge to the project team and transferring engineering capabilities back to corporate; and, developing customer requirements that ensure project success. In order to meet these responsibilities, the project manager needs to understand the diversity of technical communication from parent to subsidiary, the cultural vagaries of these communications, in addition to maintaining an eye on knowledge transfer. The challenge for an organization is to manage knowledge transfer between headquarters and its subsidiaries optimally. This initial study will investigate the factors associated with successes of international projects examining cultural and knowledge transfer processes of industrial companies and their subsidiaries. It plans to improve understanding of how communication structures and mechanisms of companies are integrating factors between culture and knowledge transfer and how they impact project success.
Experimental Analysis of Vibration of Micromachined Resonators
Authors: Hassanpour Pezhman A. , Esmailzadeh Ebrahim , Cleghorn William L. , Mills James K.
Published: August 2009

Among many different mechanisms that are used for excitation and detection of vibration of micro-beam resonators, electrostatic comb-drives have the benefit of simplicity and large range of linear operation. The disadvantage of using comb-drives is the effect of added mass to the beam; however, the analytical model of the beam-mass system predicts that this shortcoming can be overcome by proper adjustment of the mass, rotary inertia, and location of the comb-drive. In addition, the analytical model can predict the effect of the axial force of the beam on the resonance frequencies. In this paper, the results of the experiments on two resonators are presented. These results are used to verify the validity of the analytical model and finding its parameters. Very close agreement between the theory and experiment is observed. The residual stress of the MEMS structural layer is measured using the calibrated analytical model parameters.
Development of Lead-Free Nanocomposite Solders Using Oxide Based Reinforcement
Authors: Babaghorbani P. , Nai S. M. L. , Gupta M.
Published: August 2009

In this study, Sn.3.5Ag/SnO2 nanocomposite solders are developed. Composites with 0.7 and 1.0 volume percentage of tin oxide were synthesized through powder metallurgy route incorporating microwave assisted rapid sintering technique followed by hot extrusion. The extruded specimens were examined in terms of their physical and tensile properties. Tensile characterization studies revealed that 0.2% yield strength and ultimate tensile strength were increased significantly by addition of 0.7 volume percent of nano SnO2 particles. An attempt is made to correlate mechanical properties of Sn-3.5Ag with the presence of SnO2 particles at the nanometer length scale.
Five-Bar Double-Slider Two-DOF Parallel Manipulators for Singularity-Free Path Generation
Authors: Zhou Hong , Borgaonkar Kamlesh , Venkat Rao Govind Raj
Published: August 2009

Parallel manipulators are closed-loop multi-degree-of-freedom linkages, which have the merits of high stiffness, load-bearing, operation speed and precision positioning capabilities that are required in many industrial applications. The main challenges for parallel manipulators are the limited workspace and singularity-free path generation capability. This paper is focused on the singularity-free path generation of five-bar double-slider two-DOF parallel manipulators. The linkage feasibility conditions are derived based on the elimination of dead point position within the workspace. The workspace is generated using the curve-enveloping theory. The singularity characteristics and linkage configurations are presented. The singularity-free path generation capability is analyzed. The performance index contours within the workspace are produced using the condition number of the manipulator Jacobian matrix. This paper shows that five-bar double-slider two-DOF parallel manipulators can be used as effective singularity-free path generators if properly designed. The results of this paper provide a useful map for the proper design of this type of parallel manipulator.
A Study of the Impact of 3D Haptic-Augmented Learning Tools on Dynamics Course
Authors: Zhu Weihang , Aung Kendrick , Parikh Bhavan , Zhou Jiang , Srinivasan Malur , Matthews Thomas
Published: August 2009

This paper presents our recent investigation on the impact of 3D haptic-augmented learning tools on Dynamics, which is a basic course in most of the engineering education program. Dynamics is considered to be one of the most difficult and non-intuitive courses that engineering students encounter during their undergraduate study because the course combines basic Newtonian physics and various mathematical concepts such as vector algebra, geometry, trigonometry, and calculus and these were applied to dynamical systems. Recent advances in Virtual Reality and robotics enable the human tactual system to be stimulated in a controlled manner through 3-dimensional (3D) force feedback devices, a.k.a. haptic interfaces. In this study, 3D haptic-augmented learning tools are created and used to complement the course materials in Dynamics course. Experiments are conducted with a group of Mechanical Engineering students in the Dynamics class. The assessment result shows that the innovative learning tools: 1) allow the students to interact with virtual objects with force feedback and better understand the abstract concepts by investigating the dynamics responses; 2) stimulate the students’ learning interests in understanding the fundamental physics theories.
Calculating Outcrossing Rates Used in Decision Support Systems for Ships
Authors: Nielsen Ulrik D.
Published: August 2009

Onboard decision support systems (DSS) are used to increase the operational safety of ships. Ideally, DSS can estimate — in the statistical sense — future ship responses on a time scale of the order of 1–3 hours taking into account speed and course changes. The calculations depend on both operational and environmental parameters that are known only in the statistical sense. The present paper suggests a procedure to incorporate random variables and associated uncertainties in calculations of outcrossing rates, which are the basis for risk-based DSS. The procedure is based on parallel system analysis, and the paper derives and describes the main ideas. The concept is illustrated by an example, where the limit state of a non-linear ship response is considered. The results from the parallel system analysis are in agreement with corresponding Monte Carlo simulations. However, the computational speed of the parallel system analysis proved slower than expected. Moreover, it is important that the failure surface of the limit state is smooth, otherwise the parallel system analysis may not be applicable.
Performance Optimization Method for Radial Fans With Combined Vaneless Circular and Volute Diffusers Applied to an Industrial Fan
Authors: Epple Philipp , Miclea Mihai , Delgado Antonio
Published: August 2009

The use of high speed radial impellers is very common for industrial fans and blowers. The aerodynamic design of these machines can be made through direct or inverse means. The design process is almost always direct, based on the existing impeller series and available experimental data [1]. This paper presents the design results and optimization of high speed radial impellers with combined vaneless radial and volute diffusers used for industrial fans, through a combined analytical–numerical method validated by measurements of prototypes at the test rig. The reduction of the velocity from the outlet of the impeller to the outlet of the vaneless diffuser and hence the velocity at the inlet of the volute has a significant influence on the turbulence intensity and hence on the noise and therefore was a major parameter in determining the outer diameter of the circular vaneless diffuser. The designs where then validated by means of CFD computation, and following the numerical results, prototypes for both the volute and the impeller were built and experimentally investigated. The experimental results confirmed the numerical ones and it was shown that the optimized impeller had an absolute increase in efficiency with 70% at the operating point. One has to mention, that in this design, because of the special medical application, the operating point has to be unusually chosen shifted from the maximum efficiency. The results presented show the potential and advantages of the combined analytical and numerical method suited to perform a coupled design of high efficiency radial impellers and spiral casings. It shows also that new designs and improvement of existing designs are possible without the need of a previous impeller series or knowledge of experimental data.
Surface Decontamination via Plasma Mediated Ultra-Short Pulsed Laser Ablation
Authors: Wang Xiaoliang , Guo Zhixiong
Published: August 2009

Ultra-short pulsed laser removal of thin film blood contamination at glass surface has been studied. Utilizing plasma mediated ablation effect, the blood contamination was transformed into plasma cloud and collected with a vacuum system. A laser beam (wavelength 1552nm, pulse duration 1.2 picosecond) is focused into a working spot and scanned over the contaminated x-y plane area via an automated stage. The ablation effects of different laser parameters (pulse repetition rate, pulse energy) are demonstrated. The ablation result is evaluated with microscope.
Approximating a Three-Dimensional Fluidized Bed With Two-Dimensional Simulations
Authors: Deza Mirka , Battaglia Francine , Heindel Theodore J.
Published: August 2009

Fluidized beds can be used to gasify biomass in the production of producer gas, a flammable gas that can replace natural gas in process heating. Modeling these reactors with computational fluid dynamics (CFD) simulations is advantageous when performing parametric studies for design and scale-up. From a computational resource point of view, two-dimensional simulations are easier to perform than three-dimensional simulations, but they may not capture the proper physics. This paper will compare two- and three-dimensional simulations in a 10.2 cm diameter fluidized bed with side air injection to determine when two-dimensional simulations are adequate to capture the bed hydrodynamics. Simulations will be completed in a glass bead fluidized bed operating at 1.5Umf and 3Umf, where Umf is the minimum fluidization velocity. Side air injection is also simulated to model biomass injection for gasification applications. The simulations are compared to experimentally obtained time-averaged local gas holdup values using X-ray computed tomography. Results indicate that for the conditions of this study, two-dimensional simulations qualitatively predict the correct hydrodynamics and gas holdup trends that are observed experimentally for a limited range of fluidization conditions.
The Effect of Nonlinear Piezoelectric Coupling on Vibration-Based Energy Harvesting
Authors: Triplett Angela , Quinn D. Dane
Published: August 2009

Advances in electronic and consumer technology are increasing the need for smaller, more efficient energy sources. Thus vibration-based energy harvesting, the scavenging of energy from existing ambient vibration sources and its conversion to useful electrical power, is becoming an increasingly attractive alternative to traditional power sources such as batteries. Energy harvesting devices have been developed based on a number of electro-mechanical coupling mechanisms and their design must be optimized to produce the maximum output for given environmental conditions. While the role of nonlinearities in the components has been shown to be significant in terms of the overall device efficiency, few studies have systematically investigated their influence on the system performance. In this work the role of a nonlinear piezoelectric relationship is considered on the performance of a vibration-based energy harvester. Using a Poincare´-Lindstedt perturbation analysis the response of the harvesting system is approximated, including mechanical damping, stiffness nonlinearities, and the above mentioned nonlinear piezoelectric constitutive relationship. The predicted behavior is then compared against numerical simulations of the original system, focusing on the relationship between the power generated by the device, the ambient vibration characteristics, and the nonlinearities in the system.
Improving the Mechanical Properties in Tissue Engineered Scaffolds
Authors: Arafat M. T. , Savalani M. M. , Gibson I.
Published: August 2009

Scaffold-based tissue engineering research aims to aid in the repair and regeneration of bone defects. Scaffolds act as a basis for carrying cells or therapeutic agents for regenerative therapies. To achieve this, the scaffold should have appropriate osteoconductive, osteoinductive and biodegradable properties. To date, such structures have only been used with some success in low-load bearing applications, despite the large variety of biomaterials and fabrication techniques explored in the last two decades. Previous studies have illustrated the suitability of the Fused Deposition Modelling (FDM) process in fabricating PCL-20% β-TCP scaffolds for low-load bearing bone tissue engineering applications. This paper aims to demonstrate the possibility of increasing the mechanical properties of such scaffolds by introducing a through-hole. In addition, it is conjectured that such through-holes may also become useful for the channeling or storage of nutrients. A number of scaffolds with through-holes of various sizes were fabricated in order to study the effect of the through-hole diameter on the modulus (stiffness) of the complete scaffold. It was observed that the stiffness of the scaffolds varies with the diameter of the through-hole. After a certain through-hole diameter threshold the stiffness of the scaffold begins to increase above that of the original scaffold. An improvement of approximately 37% was observed in the PCL-20% β-TCP scaffolds. Also, it was noted that the threshold value for the through-hole diameter depends on the spacing of the adjacent filaments of the scaffolds.
Nomographs for Enumeration of Clutching Sequences Associated With Epicyclic-Type Automatic Transmission Mechanisms
Authors: Esmail Essam L.
Published: August 2009

A new methodology for the enumeration of feasible clutching sequences for a given epicyclic gear mechanism (EGM) is presented using the kinematic nomographs of epicyclic-type transmission mechanisms. From such nomographs, the kinematic characteristics of an epicyclic gear mechanism can be expressed in terms of the gear ratios of its gear pairs. From a single nomograph, the angular velocities for all of the coaxial links can be estimated and compared directly without specifying the exact size of each gear. In addition, the angular velocities can be arranged in a descending sequence without using complicated artificial intelligence or algorithmic techniques. Then, a procedure for the enumeration of feasible clutching sequences associated with a transmission mechanism composed of two or more fundamental gear entities (FGEs) is developed. The reliability of the methodology is established by applying it to two transmission gear trains for which solutions are either fully or partially available in the literature. In the process, an incomplete in the results reported in previous literature is brought to light. And the root cause of this incompleteness is explored. The present methodology is judged to be more efficient for enumeration of all feasible clutching sequences of an EGM.
Hazard Analysis and Risk Assessment for the Operators of Stand-Up Forklifts
Authors: Railsback Ben T. , Ziernicki Richard M.
Published: August 2009

Past studies have indicated that the greatest risk that a forklift operator faces is the hazard of an overturning forklift crushing the operator. This conclusion has been developed largely based on accident experience with sit-down forklifts. In contrast, this paper examines a data set of approximately 3,000 stand-up lift truck accidents (rather than sit-down forklifts) and finds that the operator of a stand-up lift truck is at greater risk of being involved in a collision with a stationary object than at risk for an accident involving the stability of the forklift. Greater than 50% of the approximately 3,000 accidents studied involved a collision between a stand-up forklift and a stationary object, resulting in approximately 700 serious injuries and 22 deaths of stand-up forklift operators. This paper will also identify the hazards associated with the use of stand-up lift trucks and the statistical likelihood of the hazard based on the approximately 3,000 accident data set.
Implicit Integration in Molecular Dynamics Simulation
Authors: Schafer Nicholas P. , Serban Radu , Negrut Dan
Published: August 2009

Molecular Dynamics (MD) simulation is a versatile methodology that has found many applications in materials science, chemistry and biology. In biology, the models employed range from mixed quantum mechanical and fully atomistic to united atom and continuum mechanical. These systems are evolved in discrete time by solving Newton’s equations of motion at each time step. The numerical methods currently in use limit the step size of a typical all atom simulation to 1 femtosecond. This step size limitation means that many steps need to be taken in order to reach biologically relevant time scales. At each time step, an evaluation of the forces on each atom must be performed resulting in heavy computational loads. This work investigates the use of implicit integration methods in MD. Implicit integration methods have been proven superior to their explicit counterparts in classical mechanical simulation, with which MD has many similarities. Longer time steps reduce the number of force evaluations that must be performed and the corresponding computational load. Herein we present results that compare implicit integration techniques with the current standard for molecular dynamics, the explicit velocity Verlet integration scheme. Total energy conservation is used as a metric for evaluating the dependability of simulations in the microcanonical ensemble. In order to understand the nature of the problem, several long simulations were run and analyzed by performing a Fourier analysis on the position, velocity and acceleration signals. Lastly, several methods for improving the viability of implicit integration methods are considered including replacing the Jacobian used in the Quasi-Newton method with a constant, diagonal mass matrix, evaluating the Jacobian infrequently and finding a better prediction of the system configuration to improve the convergence of the Quasi-Newton method.
Solid State Electrochemical Sensor for Monitoring Lean Direct Injection Engines
Authors: Rheaume Jonathan , Hable Wolfgang , Dibble Robert , Pisano Albert
Published: August 2009

This work presents a novel scheme for the use of an oxygen sensor operating in dynamic engine conditions. Our modeling and experimental work show that a solid state, single cell, amperometric oxygen sensor located inside the cylinder of a lean direct injection engine produces a signal that provides different information depending on the stroke. During the intake stroke, the sensor’s signal is proportional to the partial pressure of oxygen, facilitating exhaust gas recirculation. During the compression stroke of a diesel engine prior to fuel injection, the sensor’s output indicates the cylinder pressure, which is useful for control and diagnostic purposes. The signal during the power stroke confirms combustion. During the exhaust stroke, the sensor’s signal indicates the oxygen quantity after combustion. Our model of engine and sensor operation simulates the changes in air properties including temperature, pressure, and oxygen concentration over the entire four strokes of the diesel cycle; these parameters affect the diffusivity of oxygen and the signal output. The model describes a sensor signal limited by diffusion or electrolytic conductivity depending on electrode design parameters (dimensions, porosity, tortuosity, etc). Knowledge of the sensor temperature and the engine crank angle are required in order to evaluate the signal. Experimental results confirm the pressure dependence of the oxygen sensor’s output signal when using air as the analyte fluid.
Sensorless Detection and Isolation of Faults in Motor-Pump Systems
Authors: Harihara Parasuram P. , Parlos Alexander G.
Published: August 2009

Induction motors are the workhorses of industry and a lot of effort has been invested in detecting and diagnosing induction motor faults through the analysis of the motor electrical signals. However, in many industrial applications, electric motors are used to drive dynamic loads such as pumps, fans, blowers etc. Failure of either the motors or the driven loads is associated with operational disruption. Consequently it would be beneficial if the entire motor-pump system is monitored and diagnosed. The large costs associated with production losses can be avoided if system degradation can be detected at early stages prior to failure. Moreover, downtime can be further reduced if the faulty component within the drive power system can be isolated thereby aiding plant personnel to be better prepared with spares and repair kits. Hence there is not only a strong need for cost-effective detection schemes to assess the condition of the drive power system as a whole, but also a strong need for efficient isolation schemes to identify the component within the system that is faulty. This paper describes a sensorless approach to detect and isolate induction motor and/or centrifugal pump faults. Motor and pump bearing degradation is considered to validate the performance effectiveness of the proposed scheme. No add-on sensors, on either the motor or the pump, are used in the development of the proposed method to avoid any reduction in overall system reliability and prevent increased costs. In fact, motor and/or pump bearing degradation is detected and isolated using only the motor line voltages and phase currents. The proposed technique is insensitive to electric power supply fluctuations and mechanical load variations and it does not require prior knowledge of either the motor or the pump design parameters. Hence this approach can be easily ported to motor-pump systems of varying manufacturers and sizes. The developed algorithm has been tested on accelerated fault data collected from a centrifugal pump fluid loop driven by a 3-φ, 3 hp induction motor. Results from these experiments indicate that the proposed fault detection and isolation scheme successfully detects and classifies bearing degradation in the motor and/or the pump without false positives or misclassification.
Numerical Research on Establishing Optimum Design Criterion of Ship’s Funnel
Authors: Kim J. H. , Park S. M. , Cha H. , Seol S. S.
Published: August 2009

Exhaust gases of a vessel from a main engine, a diesel generator and an incinerator contain very harmful substances like soot, SO2 and NOx. It is necessary to have the proper design of funnel shape to prevent those harmful exhaust gases influencing on accommodation and a fan room. The exhaust gases are also hot enough to damage electronic devices like radar. Therefore the funnel should be designed in the way that electronic devices are not directly exposed to the exhaust gas. This study provides guidelines for the funnel design to prevent the thermal damage of the electronic devices from the exhaust gases, and to block them re-circulating near accommodation and inflowing into fan room intakes. From CFD analyses, it is certain that the major factors affecting the exhaust gas dispersion are the large scale mixing by separation vortices and the sluggish flow in the recirculation region. And also the standards of the funnel design to minimize the exhaust gas dispersion have been established by adjusting the funnel shape, the position of the exhaust pipe, the shape of bulwark, the exhaust direction of air ventilated an engine room and the angle of the exhaust pipe.
A Study of Promotion of Sublimation Phenomenon of Freeze Drying by Using Thermal Edge Flow
Authors: Kitamura Masahiro , Tsutahara Michihisa , Taguchi Satoshi , Mitani Ryousuke , Enomura Masakazu , Zhang XiaoFeng
Published: August 2009

A blower driven by the thermal edge flow was shown to be possible to use for freeze drying. First, the pressure rise by the thermal edge flow was confirmed by using an accumulation unit. The pressure rise of 5Pa was given. Next, the effect of the blower for sublimation from frozen material was confirmed by using frozen sponges containing some water. The necessary time for drying by using the blower was roughly half compared with a drying time by not using the blower and the effect of the blower for sublimation depended on the surrounding vacuum pressure.
Shape Recovery and Mechanical Properties of Shape Memory Composites
Authors: Yarborough Christina N. , Childress Emily M. , Kunz Richard K.
Published: August 2009

As the need for deployable space structures continues to increase, a deeper understanding of the mechanical properties and the responses of shape memory composites will be needed. Past research efforts have been focused on woven (0/90) carbon fiber composites which limit the shape memory capabilities due to the brittle nature of this fiber. The current work not only utilizes a synthetic fiber which allowed for a greater versatility in the composite, but also investigates the effects of angle plies and fiber volume fraction on the attainable bend ratio of the laminates. Four types of laminates were made to test the effects of laminate thickness, angle-plies, and fiber volume fraction. The specimens from these laminates were placed in both bending and tensile tests to investigate the effect of the fiber reinforcement on the polymer’s stiffness, strength and recovery. Testing revealed that the thicker specimens demonstrated improved recovery over the thinner samples, and that the angle-ply specimens recovered better than the (0/90) specimens. The recovery of the (0/90) specimens was improved by increasing the fiber volume fraction. Most significantly, the specimens were able to achieve smaller bend ratios than in previous studies without fiber microbuckling or fiber breakage. The tensile test data revealed that the bending cycles had little to no affect on the material properties of the composite. Only the modulus of the 5-ply (0/90) was seen to slightly decrease as the bending ratio decreased.
A Computational Study of the Thermal Performance of a 15 kV Solid State Current Limiter Cooled by Immersion in Mineral Oil
Authors: Warzoha Ronald , Fleischer Amy S. , Gandhi Mahesh , Sundaram Ashok
Published: August 2009

This paper outlines the thermal performance of a unique liquid-cooled 15 kV/4000 A Solid State Fault Current Limiter (SSFCL) developed by Silicon Power of Malvern, PA with support of EPRI. The design features an extremely high power system which consumes 96 kW of power in a one phase configuration. The system is submerged in mineral oil coolant and the waste heat is dissipated by internal liquid convection and subsequently through an external radiator system driven by a centrifugal pump. This project numerically explores the effects of various design parameters on the heat dissipation and the resulting effect on the operating temperature of several components within the system.
Evaluating the Influence of Charge Motion Control on In-Cylinder Flow Using MTV
Authors: Mittal M. , Schock H. J. , Sadr R.
Published: August 2009

An experimental study is performed to investigate the effects of charge motion control on flow measurement inside an internal combustion (IC) engine assembly. Molecular Tagging Velocimetry (MTV) is used to obtain the multiple point measurement of the instantaneous velocity field. MTV is a molecular counterpart of PIV based techniques, and it eliminates the use of seed particles. A two-dimensional velocity field is obtained at various crank angle degrees (CADs) for tumble and swirl measurement planes inside an optical engine assembly [1500 and 2500 rpm engine speeds]. Effects of charge motion control are studied considering different cases of: (i) Charge motion control valve (CMCV) deactivated and (ii) CMCV activated. Both the measurement planes are used in each case to study the cycle-to-cycle variability inside an engine cylinder. Probability density functions (PDFs) of the normalized circulation (NC) are calculated from the instantaneous planar velocity to quantify the cycle-to-cycle variations of in-cylinder flows. Different geometries of CMCV produce different effects on the in-cylinder flow field. It is found that the CMCV used in this work has a profound effect on fuel-air mixing; however, its influence is not as significant during the late compression. Therefore, it can be assumed that CMCV has less contribution to enhance the flame speed during the combustion process.
Application of the Rapid Update Cycle (RUC) to Aircraft Flight Simulation
Authors: Zhang Yan , McGovern Seamus
Published: August 2009

An aircraft flight simulation model under development aims to provide a computer simulation tool to investigate aircraft flight performance during en route flight and landing under various atmospherical conditions [1]. Within this model, the air pressure and temperature serve as important parameters for deriving the true airspeed (TAS). Also important are the wind speed and direction, which will be direct inputs for the flight simulation model. In this paper, the Rapid Update Cycle (RUC) data, provided hourly by the National Centers for Environmental Prediction (NCEP) and the National Oceanic and Atmospheric Administration (NOAA) are used to derive the atmospherical parameters. We relate the pressure to the geodetic altitude by using the geopotential height from the RUC data and the theoretical model. Then the resultant pressure as a function of the geodetic altitude is used to retrieve other parameters such as the temperature and wind velocity by multi-dimensional interpolation. Airplane flights simulated by the X-Plane® simulator with the input of the RUC data are demonstrated.
XeF2 Etching of Silicon for the Release of Micro-Cantilever Based Sensors
Authors: Easter Clayton , O’Neal Chad
Published: August 2009

The release of microstructures from a Si substrate depends directly on the underetching (isotropic) characteristics of the etchant used. For the purpose of this study, XeF2 gas was selected as the etchant medium. Etching by XeF2 is primarily a function of pressure, which determines the rate of interaction between the Si surface and the etchant gas. However, other factors play a large role in XeF2 etching characteristics. Testing was conducted to determine the etch rate and profile of XeF2 etching when various parameters of the structure design are changed (Si exposure area, size and dimension of structures, spacing of structures). The gas was introduced at a pressure cycle of approximately 4.0 Torr for 180 s. Uniformity of the etched surface is improved by increasing the number of etch cycles, or by increasing the gas pressure of the surrounding XeF2.
Modeling and Analysis of the Effect of Disc Degeneration, Artificial Disc Replacement and Spinal Fusion on the Biomechanics of the Lumbar Spine
Authors: Mazzoleni Andre P. , Gonzalez Antonio , Padgett David , Hey Lloyd A.
Published: August 2009

This paper presents observations regarding the frequency response behavior of the lumbar spine. The frequency response ratio is calculated using a model of the spine which treats the vertebrae as cubic masses and the discs as systems of springs and dampers. The frequency response of the spinal model under healthy spine conditions is cataloged. The model is varied to simulate intervertebral disc degradation, spinal fusions, and artificial disc replacements, and the frequency response for these cases are calculated and compared with the response of the healthy spine.
Showerhead Film Cooling Performance of a Turbine Vane at High Freestream Turbulence in a Transonic Cascade
Authors: Nasir S. , Bolchoz T. , Ng W. F. , Zhang L. J. , Moon H. K. , Anthony R. J.
Published: August 2009

This paper experimentally investigates the effect of blowing ratio and exit Reynolds number/Mach number on the film cooling performance of a showerhead film cooled first stage turbine vane. The vane midspan was instrumented with single-sided platinum thin film gauges to experimentally characterize the Nusselt number and film cooling effectiveness distributions over the surface. The vane was arranged in a two-dimensional, linear cascade in a heated, transonic, blow-down wind tunnel. Three different exit Mach numbers of Mex = 0.57, 0.76 and 1.0—corresponding to exit Reynolds numbers based on vane chord of 9.7 × 105, 1.1 × 106 and 1.5 × 106, respectively—were tested with an inlet free stream turbulence intensity (Tu) of 16% and an integral length scale normalized by vane pitch (Λx/P) of 0.23. A showerhead cooling scheme with five rows of cooling holes was tested at blowing ratios of BR = 0, 1.5, 2.0, and 2.5 and a density ratio of DR = 1.3. Nusselt number and adiabatic film cooling effectiveness distributions were presented on the vane surface over a range of s/C = −0.58 on the pressure side to s/C = 0.72 on the suction side of the vane. The primary effects of coolant injection were to augment the Nusselt number and reduce the adiabatic wall temperature downstream of the injection on the vane surface as compared to no film injection case (BR = 0) at all exit Mach number conditions. In general, an increase in blowing ratio (BR = 1.5 to 2.5) showed noticeable Nusselt number augmentation on pressure surface as compared to suction surface at exit Mach 0.57 and 0.75; however, the Nusselt number augmentation for these blowing ratios was found to be negligible on the vane surface for exit Mach 1.0 case. At exit Mach 1.0, an increase in blowing ratio (BR = 1.5 to 2.5) was observed to have an adverse effect on the adiabatic effectiveness on the pressure surface but had negligible effect on suction surface. The effectiveness trend on the suction surface was also found to be influenced by a favorable pressure gradient due to Mach number and boundary layer transition in the region s/C = 0.28 to s/C = 0.45 at all blowing ratio and exit Mach number conditions. An increase in Reynolds number from exit Mach 0.76 to 1.0 increased heat transfer levels on the vane surface at all blowing ratio conditions. A large increase in Reynolds number adversely affected adiabatic effectiveness on the pressure surface at all blowing ratio conditions. On the suction surface, a large increase in Reynolds number also affected adiabatic effectiveness in the favorable pressure gradient and boundary layer transition region.
Synthetic Nanoscale Architectures for Lipoprotein Separation
Authors: Prabhu Anmiv S. , Moraga Alejandro , Cecchini Michael , Mulero Rafael , Olsen Stephen , Cho Young I. , Kim Min Jun
Published: August 2009

Current low density lipoprotein (LDL) apheresis procedures are expensive and time consuming. We report here a novel technique to detect and separate nanoparticles using solid state nanopores. Our technique relies on the resistive pulse phenomenon used in coulter counters. We used a 150nm diameter nanopore to detect nanoparticles that closely resembled HDL and LDL in terms of their size and surface charge. Statistical analysis of the translocation data revealed that our setup preferentially allowed the particles resembling HDL to pass thorough while restricting the translocation of the particles that resembled LDL.
Modeling of Fatigue Slip Bands and Application to Notch Fatigue Problems
Authors: Matsuno Hiroshi
Published: August 2009

In the present paper, equivalent stress ratios (REQ-ratios), which have been proposed as parameters for correspondence between cyclic stress conditions of notched and unnotched specimens, are reviewed. The REQ-ratios are formulated based on a concept of plastic adaptation hypothesized for a fatigue slip band from a viewpoint of macro-mechanics. A method for diagramming fatigue strength of metals based on the parameter of the REQ-ratios is newly proposed. The method diagramming together the fatigue strength of notched and unnotched specimens is applied not only to fatigue problems of usually annealed, normalized and heat-treated materials but also to those of severely heat-treated and surface-treated ones. Fatigue strength diagrams are characterized with two types of fatigue strength: σw1 and σw2. The character of σw2 appears not only in specimens with sharp notches but also in unnotched specimens fatigue-tested at lower RN-ratios. Criteria on fatigue strength σw1 and σw2 are derived from the fatigue strength diagrams and formulated as empirical equations. Characteristics of fatigue slip bands are reviewed and two types of fatigue mechanisms are proposed related with fatigue strength σw1 and σw2 from a viewpoint of micro-mechanics. Consequently, it is found that the hypothesis of plastic adaptation is a very useful and fundamental idea for modeling a fatigue slip band and also for analyzing fatigue data of practical metals and alloys.
Use of Nonlinear Vibration Frequencies and Electrical Conductivity Measurements in the Separation of Internal and Boundary Damage in Structures
Authors: Butcher Eric A. , Sevostianov Igor , Sari Ma’en S. , Al-Shudeifat Mohammad A.
Published: August 2009

The paper addresses one of the key problems in structural health monitoring — how to separate defects, both microscopic and macroscopic, accumulated in structural members from damage in the joints and boundaries. It is suggested to use a simultaneous set of measurements — nonlinear vibration frequencies and electrical conductivities — to distinguish between three distinct types of defects. Nonlinearities occur as a result of breathing internal cracks and slapping in damaged joints. The use of proper orthogonal decomposition and a local equivalent linear stiffness method allows for model updating to account for the damage. The theory is presented for full three-dimensional elastic solids and illustrated via the problem of a beam damaged both internally as well as at the boundaries.
A Wafer Level Vibration Test System for MEMS Accelerometer Sensitivity Measurement and Calibration
Authors: Chen Wei , O’Reilly Robert , Tang Huy
Published: August 2009

Sensitivities of microelctromechanical system (MEMS) accelerometers are typically measured and calibrated at final production test of packaged devices. This process typically requires expensive special automated test equipment (ATE) that can generate vibration stimulus. A single-axis vibration test system has been developed on an existing commercial wafer probe/trim system to calibrate sensitivities of MEMS accelerometers during wafer probe/trim process to minimize the need for such vibration test equipment. To increase signal to noise ratio but avoid damage of probe pad/pin during the test, the vibration exciter must be able to generate high frequency but small displacement vibration stimulus. The vibration exciter also needs to be small enough to fit into the existing commercial probe/trim system and requires minimum changes to the system. A high resolution but small size in-situ noncontact vibration measurement technique is needed to ensure calibration accuracy. This paper presents a unique solution to meet all these challenges. The success of this system has been validated by final product test data of a test device, a 3-axis low-g MEMS accelerometer.
Effects of Substrate Surface Roughness on Electron-Phonon Coupling in Thin Au Films
Authors: Fish Michael C. , Hopkins Patrick E. , Norris Pamela M.
Published: August 2009

As device fabrication and design engineers continue to decrease the sizes of transistors within integrated circuits, the removal of waste heat becomes a limiting factor that impedes further advances in solid state nanotechnology. An in-depth understanding of how heat is transferred in thin metal films is critical to the design of better methods of heat transport in microelectronic applications. This work examines how electron scattering processes in thin Au films is affected by the presence of a dielectric interface. Ten Au films are deposited on Si and glass substrates subject to different fabrication conditions, causing a varying degree of “roughness” between the film and the substrate. The Au samples are subjected to nonequilibrium heating via the femtosecond pulsed transient thermoreflectance (TTR) technique. The rate of electron-phonon equilibration is examined by comparing the temperature decay on the surface of the Au film to the two temperature model (TTM) with insulative boundary conditions.