bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Path Planning of Redundant Cooperative Robots Under Equality and Inequality Constraints
Authors: Hosseini Ali , Keshmiri Mehdi
Published: May 2008

Using kinematic resolution, the optimal path planning for two redundant cooperative manipulators carrying a solid object on a desired trajectory is studied. The optimization problem is first solved with no constraint. Consequently, the nonlinear inequality constraints, which model obstacles, are added to the problem. The formulation has been derived using Pontryagin Minimum Principle and results in a Two Point Boundary Value Problem (TPBVP). The problem is solved for a cooperative manipulator system consisting of two 3-DOF serial robots jointly carrying an object and the results are compared with those obtained from a search algorithm. Defining the obstacles in workspace as functions of joint space coordinates, the inequality constrained optimization problem is solved for the cooperative manipulators.
Geometric Error Assessment of a Nanomechanical Drill
Authors: Joshi Nikhil , Malshe Ajay P. , Bryan April , Camelio Jaime A. , Hu S. Jack
Published: May 2008

Manufacturability of micro and nano systems has gained importance with the advent of microelectromechanical systems (MEMS). Whereas the manufacturability of macro systems has been a widely researched subject, the behavior of MEMS devices in large scale manufacturing operations is virtually an unexplored field. Therefore, in order to predict resulting product characteristics, theories developed for macro-scale manufacturing are currently being extended to micro-systems. This research employs computer aided engineering (CAE) tools in the determination of the final dimensional quality of a drilled hole created by a nano-drill. In order to obtain a valid prediction of the drilled-hole dimensions, an adequate knowledge of the processes occurring during nano drilling and the factors affecting these processes are necessary. A complete analysis requires consideration of the kinematic, static and dynamic factors that contribute to the error in the drill tip. In this paper, only the kinematic errors that affect the hole geometric quality are considered. The causes of these kinematic errors and their effect on the variation of the drilled hole are also investigated. The resulting hole size will be considered to be the result of the “stack-up” of the errors in the tool.
An Experimental Study on the Cooling Effect of Die Casting Die Insert Cooling Devices
Authors: Sun Feng , Schwam D. , Wang G.-X. , Wallace J. F.
Published: May 2008

Water is usually introduced into a die insert in die casting through a water line to reduce the temperature of the die insert and thus prevent its cracking. In many cases, a drilled waterline circuit is not possible due to confinement of the space. Bubblers or baffles then become typical water passage systems for die insert cooling. This paper presents an experimental study of the relative effectiveness of bubbler and baffle in die insert cooling. An internally channeled steel cylinder was designed as a die insert, with the blind channel drilled for water-cooling. Commercially available bubblers and baffles were inserted in the channel and water was introduced to cool the specimen when it was either heated in an air furnace or cyclically dipped into a molten aluminum bath. Thermocouples were mounted inside the wall of the cylinder to monitor the variation of the insert temperature under various cooling conditions. Experimental results indicate that both the bubbler and baffle can effectively lower the surface temperature of a die insert, with a bubbler being more suitable to cool a specific “hot spot” than a baffle. For a given cooling channel, within the experimental range, the bubbler with a smaller inner diameter has a better cooling effect to a “hot spot” than a bubbler with a larger inner diameter. Increasing the water flow rate always enhances the heat transfer between the cooling water and the sidewall of the cooling channel.
CBN Tool Wear Modeling in Finish Hard Turning
Authors: Huang Yong , Liang Steven Y.
Published: May 2008

The cubic boron nitride (CBN) cutting tools are commonly used for single point turning of hardened materials. The wear behavior and tool life of CBN cutters are important issues in order for hard turning to be a viable technology in view of the high cost of CBN cutting tools and the cost of down-time for tool change. The objective of this study is to develop a methodology to model the rate of CBN tool wear on both the flank and rake faces. The model can serve both as a basis to guide the design of CBN tool geometry and to optimize cutting parameters in finish hard turning. First, the kinematics, stress distribution, and temperature variation on the tool flank and rake faces are formulated. Subsequently, the wear volume loss is modeled as functions of cutting temperature, stress, and other process information based on the consideration of main wear mechanisms of abrasion, adhesion, and diffusion. Then, flank/crater wear rates are predicted in terms of tool/work material properties and cutting configuration. Finally, based on the calibrated wear coefficients in independent tests, the proposed models are experimentally validated in finish turning hardened 52100 bearing steel using a low CBN content insert. The model predictions agree with the measurements in terms of the behavior of stable growths of wear land and crater. The adhesion is found to be the dominating wear mechanism over the range of cutting parameters examined.
Cylindrical Grinding Cycle Design Based on Final Part Quality Constraints
Authors: Hecker Rogelio L. , Liang Steven Y.
Published: May 2008

A grinding process model to predict the forces and power based on a probabilistic analysis of the chip thickness is presented. The model includes tool properties, material properties, kinematic conditions, and dynamic effects. A surface roughness model based on the predicted chip thickness is formulated and validated with empirical data. A grinding cycle is proposed by combining power control during the stock removal stage and feed control during the finishing stage. The grinding power model and the surface roughness model were used to simulate the process and to find the optimal settings for the cycle. The desired grinding power and the workpiece rotational velocity for stock removal were selected to not exceed the machine capabilities and to prevent workpiece burn. The feed and the workpiece tangential velocity of the finishing stage were found based on the final part requirements such as surface roughness and the theoretical out-of-roundness. This grinding cycle was implemented and tested in an open architecture machine.
Highlights From the European Thermal Project PROFIT
Authors: Lasance Clemens J. M.
Published: May 2008

On January 1, 2000, the European project PROFIT commenced as a follow up to the successfully finished EC-funded projects DELPHI, SEED and THERMINIC. PROFIT finished in March 2003. The project aimed at creating methods and tools to enable a sufficiently accurate measurement and prediction of temperature gradients in time and space required for a more accurate and timely assessment of cost, performance, safety and reliability of electronic products in all stages of the product realisation process. The PROFIT partners produced 55 deliverables and over 70 conference and journal papers. The paper discusses some highlights of the project and indicates shortly their potential for small scale applications.
Analysis of Damage in Fused Quartz Glass Induced by Mechanical Processing
Authors: Lee Hong-Lim , Kim Hyun-Ho , Jeung Sang-Hun , Jeong Seong-Min , Park Sung-Eun , Oh Han-Seog
Published: May 2008

Grinding for the commercial fused quartz glass was carried out to induce the artificial defects on the specimens. The short-range ordering structures for the ground samples were analyzed by the micro Raman spectroscopy. The roughness for the ground samples was analyzed using atomic force microscopy (AFM) and power spectral density (PSD) curve. Thermal treatments were performed to analyze the annealing effect. As results, the Raman spectral shift showed that the machining induces residual tensile stress on the surface. The damages by mechanical process lowered the crystallization temperature of the fused quartz glass. However, the proper thermal annealing could relax the process-induced damages. Therefore, the thermal annealing should be considered together with process-induced damage to optimize the mechanical process for the fused quartz glass.
Cluster of High Powered Racks Within a Raised Floor Computer Data Center: Effect of Perforated Tile Flow Distribution on Rack Inlet Air Temperatures
Authors: Schmidt Roger , Cruz Ethan
Published: May 2008

This paper focuses on the effect on inlet rack air temperatures as a result of maldistribution of airflows exiting the perforated tiles located adjacent to the fronts of the racks. The flow distribution exiting the perforated tiles was generated from a computational fluid dynamics (CFD) tool called Tileflow (Trademark of Innovative Research, Inc.). Both raised floor heights and perforated tile free area were varied in order to explore the effect on rack inlet temperatures. The flow distribution exiting the perforated tiles was used as boundary conditions to the above floor CFD model. A CFD model was generated for the room with electronic equipment installed on a raised floor. Fourty racks of data processing (DP) equipment were arranged in rows in a data center cooled by chilled air exhausting from perforated floor tiles. The chilled air was provided by four A/C units placed inside a room 12.1 m wide × 13.4 m long. Since the arrangement of the racks in the data center was symmetric only one-half of the data center was modeled. The numerical modeling for above the raised floor was performed using a commercially available finite control volume computer code called Flotherm (Trademark of Flomerics, Inc.). The flow was modeled using the k-e turbulence model. Results are displayed to provide some guidance on the design and layout of a data center.
Quantification of Recrystallization Kinetics in Heavily Drawn OFHC Copper Wires by Microhardness Technique
Authors: Waryoba D. R. , Kalu P. N.
Published: May 2008

Mechanical properties of materials are inherently dependent on the microstructures that evolve during processing. The microstruture of heavily drawn and annealed OFHC copper is inhomogeneous, and as such it is difficult to assess its recrystallization kinetics by conventional methods. In this article, restoration kinetics of static recrystallization of heavily drawn oxygen free high conducting (OFHC) copper wires has been investigated by microhardness technique. The investigation was carried out on two cold drawn wires deformed to a true strain of 2.31 and 3.10 and annealed at 250°C for annealing times ranging from 10 s to 1 hr. The physical phenomena during annealing were characterized and analyzed using optical microscopy and measurement of microhardness. A unified approach, through the use of microhardness data, for the analysis of the restoration kinetics of recovery, recrystallization, and grain growth has been proposed. In this approach, a JMAK (Johnson-Mehl-Avrami-Kolmogrov) model was expressed in terms of microhardness data, and the results showed that the modified model linked the different restoration kinetics and provided the critical time for the transition from recovery to recrystallization, and to grain growth. The model compared favorably with conventional models, which treat the different restoration kinetics separately. Exponents of about 0.4 for recovery, 4.0 for recrystallization, and 0.5 for grain growth, were obtained. The results also showed that the JMAK exponent, n, is of the same order of magnitude as the grain growth exponent, 1/p.
Lead-Free Solder-Joint Reliability of a Photonic Device Under Transient and Steady State Loadings
Authors: Dauksher Walter , Lau John
Published: May 2008

Three solders, 63wt%Sn-37wt%Pb, 80wt%Au-20wt%Sn and 95.5wt%Sn-3.9wt%Ag-0.6wt%Cu, are studied as interconnect materials in a vertical-cavity surface-emitting laser, or VCSEL. While the Au-Sn alloy is a lead-free solder material that had been previously identified as a candidate material for this device, the Sn-Ag-Cu solder (henceforth SAC solder) is presently the leading lead-free solder candidate for numerous packaging types. In the present study, thermal-structural analysis evaluates the solder alloys in the context of in-service operating conditions. Specifically, the thermal analysis determines the in-service temperature distributions, as influenced by each solder alloy, due to power generation within the VCSEL and due to convective boundary conditions. Subsequently, these thermal profiles are used as the thermal loads in an evaluation of the creep response in the solder materials. Emphasis is placed on the relaxation of stresses and on the creep strains developed during a 24 hour power-on condition.
Ethernet-Based Intelligent Switching of Controllers for Performance Improvement in an Industrial Plant
Authors: Tang P. L. , de Silva C. W.
Published: May 2008

This paper presents an Ethernet-based intelligent system for remote switching of the controllers of an industrial plant with the objective of on-line improvement of the performance of the plant. The plant considered in the present paper is an industrial fish-processing machine, which operates using one of several adaptive controllers. The scheme utilizes a remote supervisor, which incorporates knowledge-based decision making to continuously monitor the performance of the plant. The performance metrics deduced from the observations are then used to infer the best adaptive controller for the plant under the existing conditions. A knowledge-based system that incorporates both human expertise and analytical knowledge regarding the plant and the controllers is developed. The proposed intelligent switching is implemented in real-time for controlling the hydraulic-actuated cutter of the fish-processing machine. A client/server supervisory control architecture for remote networked-based controller switching is developed. Switching has to be done in such a manner that the transition from one controller to another takes place in a smooth manner. Proper design of the intelligent switching system is key to achieving this objective.
Optimization of Coal Mill Using an MPC Type Controller
Authors: Jankowski Robert , Doman´ski Paweł D. , S´wirski Konrad
Published: May 2008

The article presents the question of optimization of a ventilation coal mill on the basis of a predictive optimizing controller with a receding horizon, which is an extension of the standard linear MPC (Model Predictive Control) type controllers. The controller has been realized in a digital version operating with a certain sampling period dependent upon the process dynamics. All calculations of the control rules are performed in one cycle which enables the controller to operate in the running mode. On the basis of a right optimization procedure the controller regulates the correction of settings, which are introduced to classic control structures in a fuzzy control system. The non-linear process model, implemented in the controller, is based on the basis of fuzzy neural networks. This structure enables to design, learn and tune NARMAX type models (Nonlinear Auto Regressive Moving Average with auXiliary input) [1]. The process model uses fuzzy rules, where fuzzy rules figure on the side, which helps to avoid sharp switching between them. The consequences of the rules take the form of differential equations of the linear ARX type models. The use of neural networks ensures a fast and efficient implementation and effective learning and tuning. The problem of control is based in on a periodically performed optimization of the performance index, defined on the basis of the assumed project goals. The aim of the controller operation is to eliminate undesired events occurring during mill operation. Such events are: instability of temperature value of air-dust mix after the mill, excessive fluctuation of air temperature before the mill and positioning of primary and secondary air dampers outside the control range. These goals are realized through appropriate control of the primary air damper and revolving speed of the mill. The implementation carried out of the described controller in a digital automatic control system on 8 ventilation mills of a 360 MW brown coal fired boiler. This article presents the results obtained and a carried out analysis.
Investigation of White Layers Formed in Conventional and Cryogenic Hard Turning of Steels
Authors: Zurecki Zbigniew , Ghosh Ranajit , Frey John H.
Published: May 2008

Although hard turning of steels has become an accepted industrial practice reducing the extent of grinding, many surface integrity aspects of hard turning require clarification. The striking result of hard turning is the tendency for forming white (non-etching) and dark (overtempered) layers at machined surface. White layers are often associated with residual tensile stresses leading to reduced fatigue strength and poor wear resistance. It has been reported that certain steel compositions, machining conditions, and tools enhance white layers, but no consensus was reached on the nature of white layer and the role of environmental factors. This study examines the impact of cryogenic, liquid nitrogen spray cooling, tool and work materials, as well as machining speed on white layer formation. Results are evaluated using XRD, SEM, EDS, AES, residual stress measurement and microhardness profiling. It is concluded that white layers are a purely thermomechanical phenomenon involving dissolution of low-alloy carbides into austenitic matrix, and catastrophic flow of that 1-phase material resulting in its nano-scale refinement. The depth and extent of the refinement are controlled by cooling, with the cryogenic nitrogen reducing white layer thickness, loss of hardness, and improving residual stress distribution.
Comparative Study of Spray and Multiple Micro Jets Cooling for High Power Density Electronic Applications
Authors: Fabbri Matteo , Jiang Shanjuan , Dhir Vijay K.
Published: May 2008

Direct cooling by means of jets and sprays has been considered a solution to the problem of cooling high power density electronic devices. Although both methods are capable of very high heat removal rates it is necessary to be able to decide which one is more convenient than the other when designing a cooling system for electronic applications. In this work the results of an investigation of the performances of sprays and arrays micro jets are reported. Experiments have been conducted using HAGO nozzles and orifice plates to create droplet sprays and arrays of micro jets, respectively. The liquid jets had diameters ranging from 50 to 150 μm and the pitches between the jets were 1, 2, and 3 mm. The test fluid was deionized water and the jet Reynolds number ranged between 90 and 2600. A comparison of the results obtained employing both sprays and jets has been carried out. The micro jets have dimensions of the same magnitude or smaller than those of the electronic components. The micro jet arrays give better heat transfer rates than the large diameter ones studied in the past and they use liquid mass flow rates similar to those used by the sprays.
Using White Light Interferometry for Mesoscale Part Inspection
Authors: Shilling K. Meghan , Kurfess Thomas R.
Published: May 2008

Measurement of LIGA parts is critical for characterization and understanding of process variables. Traditionally, measurement using coordinate metrology consists of collecting data points from all of the surfaces of a part (e.g., three dimensional data) and comparing these points with target geometry as defined in a CAD file. Systems such as coordinate measurement machines and laser scanners are often used to collect the data. Unfortunately, three dimensional data collection has proven to be quite difficult for mesoscale parts, such as those created using the LIGA process. The inspection techniques used for larger parts cannot be used for parts of this scale because of physical limitations or poor resolution. This paper targets the use of white light interferometry for the analysis of micro-components produced using the LIGA and stereolithography processes. Both of these processes often create parts that are designed to have a constant cross section with planar top and bottom surfaces. Assuming this geometric relationship holds true, the analysis of just the top or bottom surface of the part can provide useful information pertaining to process capability and part geometry. White light interferometry is well-suited to the measurement of these planar surfaces. This paper will discuss techniques used to analyze two dimensional part parameters using white light interferometry in combination with image processing techniques. Several case studies are included to show the abilities of the measurement and processing methods.
Three-Dimensional Finite Element Modeling of Hard Turning Processes
Authors: Marusich T. D. , McDaniel R. J. , Usui S. , Fleischmann J. A. , Kurfess T. R. , Liang S. Y.
Published: May 2008

Hard turning processes promise affordable fabrication of machined components with high dimensional accuracy requirements. In an effort to achieve the desired economics a vast array of process variables must be considered including tool material, geometry, edge preparation, wear, speed and feed selection, while maintaining part quality. One method to reduce the number of necessary experiments is through accurate and reliable modeling. A three-dimensional finite element model is presented which includes fully adaptive unstructured mesh generation, tight thermo-mechanically coupling, deformable tool-chip-workpiece contact, interfacial heat transfer across the tool-chip boundary, momentum effects at high speeds and constitutive models appropriate for high strain rate, finite deformation analyses. The model is applied to nose turning of hardened steel workpieces, HRc 60. Metal cutting tests are performed, cutting forces collected, and validation comparison is made.
A Continuous Improvement/Management-by-Objectives Approach to Evaluating University Faculty
Authors: Zahraee Mohammad A.
Published: May 2008

This paper discusses the design, analysis and implementation of a faculty evaluation system to be used in both departments of Electrical Engineering Technology and Manufacturing Engineering Technologies and Supervision at Purdue University Calumet. The System, based on a faculty member’s continuous improvement plan, builds on the Management-by-Objectives approach, which reflects the Human Resource practice of performance plans and evaluations in corporate America. This new system, being outcome based, asks faculty to set goals and objectives with some degree of flexibility and is in line with the accreditation requirement changes of Accreditation Board for Engineering and Technology (ABET).
Using Videotape to Add an Asynchronous Delivery Option to Regular Classroom Instruction
Authors: Blake John W.
Published: May 2008

Student schedules are often at odds, forcing them to miss needed classes due to time conflicts. Departments have limited faculty resources, and cannot offer courses every term at times to meet every need. This paper describes the use of instruction via videotape to offer students an option for taking courses when they cannot attend at the scheduled time. Delivery of instruction by videotape is not new; this paper describes efforts to adapt this method to specific circumstances and student needs. This has resulted in higher course enrollments when videotape and traditional sections are combined for teaching load purposes, and has permitted students to complete graduation requirements when, without this option, they would have been delayed due to scheduling conflicts.
Identification of Spindle Integrated Force Sensor’s Transfer Function for Modular End Mills
Authors: Park Simon S. , Altintas Yusuf
Published: May 2008

A spindle integrated cutting force system is studied in the paper. Piezoelectric force sensors are embedded to the spindle housing. The transfer function between the force experienced at the end mill and measured at the spindle integrated force sensor varies depending on the stick out length of the end mill. The paper proposes a method which predicts the transfer function of the overall system by coupling the receptances of the analytically modeled end mill and experimentally measured spindle structures. The experimentally proven method allows automated calibration of the spindle integrated force system whenever a tool change occurs.
Thermodynamic, Tribological and Chemical Interdiffusion Study of Ultra-Hard Ceramic AlMgB14 in the Machining of Aerospace Alloys
Authors: Bedekar Vikram , Bhat Deepak G. , Batzer Stephen A. , Walker Larry , Allard L. F.
Published: May 2008

There has been a growing concern about the reactivity at the tool/work-piece interface during machining, leading to lower tool life. The problem is more severe especially in the case of aerospace alloys such as Ti-6Al-4V and stainless steels. Recently, a new ultra hard ceramic material, AlMgB14, was reported with properties that show considerable promise as a cutting tool material for machining titanium alloys [1]. This paper investigates the chemical wear behavior of AlMgB14, in the machining of aerospace alloys. The mechanical properties of AlMgB14 are compared with leading cutting tool materials (WC-Co, Al2O3SiCw-TiC and Al2O3-TiC), which are used extensively in machining titanium and ferrous alloys. Materials characterization of candidate tool materials shows that AlMgB14 exhibits superior hardness, fracture toughness and abrasive wear resistance as compared to the other cutting tool materials. We also report on a study of chemical reactivity of tool materials (AlMgB14 and WC-6%Co) in machining various alloys such as Ti-6Al-4V and Fe-18Ni-8Cr. The chemical reactivity was investigated using diffusion tests conducted in vacuum at 1000°C for 120 hrs. Transverse sections of couples were characterized using electron probe micro analysis (EPMA), to determine the extent of diffusion zones. The results show that AlMgB14 shows considerably less reactivity with titanium alloys when compared with cemented carbide cutting tools. It was also observed that the boride reacts significantly with the iron based Fe-18Ni-8Cr alloy. The paper also reports on the evaluation of the free energy of formation of AlMgB14 using the thermochemical software program FactSage™.
Micro-Control Characteristics of Conical Shell Sections
Authors: Chai W. K. , Tzou H. S. , Higuchi K.
Published: May 2008

Rocket fairings, turbine blades, load carrying structure for solid rocket motor case, inter-stage joint, satellite-rocket joint etc., usually take the shape of conical shell sections. Conical shell has a large load carrying capacity per unit weight due to its high-strength, high-rigidity and light-weight properties. This paper is to evaluate spatially distributed microscopic control characteristics of distributed actuator patches bonded on conical shell surfaces. The converse effect of piezoelectric materials has been recognized as one of the best electromechanical effects for precision distributed control applications. The resultant control forces and micro-control actions induced by the distributed actuators depend on applied voltages, geometrical (e.g., spatial segmentation and shape) and material (i.e., various actuator materials) properties [8]. Mathematical models and modal domain governing equations of the conical shell section laminated with distributed actuator patches are presented first, followed by the formulations of distributed control forces and micro-control actions which can be refined to longitudinal/circumferential membrane and bending control components. Spatially distributed electromechanical microscopic actuation characteristics and control effects resulting from various longitudinal/circumferential actions of actuator patches are then evaluated.
Deformation Behavior of Intrusion Bending for Steel Pipes
Authors: Sano Tetsuaki , Naoi Hisashi
Published: May 2008

We have investigated the intrusion bending for steel pipes for several years. The bending machine consists of three parts. They are called pusher, guide cylinder and gyro. The aim of this investigation is to reveal the effect of size and strength of materials, pushing forces and so on. That we study in this report are as follows: (1) The effect of bending radius ratio on ovality of outer diameter and eccentricity of wall thickness, and (2) the effect of ratio of wall thickness to outer diameter on ovality of outer diameter and eccentricity of wall thickness. The conclusions of this study are summarized as follows. (1) The ovality of outer diameter and the eccentricity of wall thickness increase as the bending radius ratio decreases. (2) The ovality of outer diameter decreases and the eccentricity of wall thickness increase as thickness outside diameter ratio increases.
Tether System Designed for Flip-Chip Bonded MEMS
Authors: Laws Alexander , Faheem Faheem , Zhang Huantong , Lee Y. C.
Published: May 2008

Flip-chip bonding is important to integrate MEMS devices with other components or to make novel devices. The use of tethers when flip-chip bonding is valuable because it enables the release of the MEMS based device prior to bonding. Releasing the device prior to bonding allows the possibility to bond to a substrate that includes materials that are incompatible with the release process, increase yield since any devices lost during release are not bonded, and avoid damage to the bond. This paper presents a set of design rules for devices created with the MUMPs process that can be implemented to allow the device to be tether flip-chip bonded. The rules outline the design of tethers, mechanical stops, and locking bumps, which work as a system to keep the device from slipping or twisting during bonding, but break free from the donor substrate after bonding. Examples of success, reasons for past failures and the solutions are presented.
Frequency Response of a Base Excited System With Hydraulic Mount
Authors: Christopherson J. , Nakhaie Jazar G.
Published: May 2008

This paper investigates the frequency response analysis of a hydraulic suspension system undergoing base excitation. The nonlinearity of the hydraulic suspension due to the decoupler action is taken into account and the effects of utilizing an inertia track in the design of the hydraulic mount are also considered. The analysis focuses on the development of the equations of motion for a three degree of freedom system, and the development of an appropriate model based on the equations of motion for the system, which is essential for utilization is an optimization procedure. The analysis was conducted using common numerical procedures such that the nonlinear effects of the model may be reasonably approximated.
Miniature Corrugated Diaphragm for Fiber-Optic-Linked Pressure Sensing (FOLPS)
Authors: Noh Hong-Seok , Kim Sangkyung , Hesketh Peter J. , Mao Hua , Wong Lid
Published: May 2008

This paper presents miniature (diameter less than 1.5 mm) corrugated parylene/Cr/parylene diaphragms that provide ultra sensitive load-deflection (±100 μm for ±1kPa) and reflective surface for optical sensing. The design, fabrication, and test results of the ultra low pressure transducer for biomedical applications are reported here. The diaphragms have been attached to stainless steel tubes that are suitable for most endoscopes.
Simulations of Heat Conduction in Sub-Micron Silicon-on-Insulator Transistors Accounting for Phonon Dispersion and Polarization
Authors: Narumanchi Sreekant V. J. , Murthy Jayathi Y. , Amon Cristina H.
Published: May 2008

In recent years, the Boltzmann transport equation (BTE) has begun to be used for predicting thermal transport in dielectrics and semicondutors at sub-micron scales. Most studies make a gray assumption and do not account for phonon dispersion or polarization in any detail. In this study, the problem of heat generation in a sub-micron silicon-on-insulator (SOI) transistor is addressed. A model, based on the solution to the BTE incorporating full phonon dispersion effects, is presented and used to study the SOI self-heating problem. A structured finite volume approach is used to solve the BTE. The results from the full phonon dispersion model are compared to predictions using the Fourier diffusion equation and also to predictions from the solution to the BTE using a semi-gray model which appears in literature. Significant differences are found between the models and confirm the need for an accounting for phonon dispersion and polarization effects.
A Virtual Velocity Sensor for Improved Transient Performance of Electrostatically-Actuated MEMS
Authors: Maithripala D. H. S. , Berg Jordan M. , Dayawansa W. P.
Published: May 2008

Electrostatically-actuated MEMS devices suffer from a non-linear bifurcation phenomenon called “snap-through” or “pull-in.” This bifurcation severely limits the operating region of such devices. Control schemes have been proposed to eliminate snapthrough. These stabilizing controllers can be implemented using relatively straight forward current and voltage measurements. However, in order to alter the transient behavior of the system, for example to reduce settling time, or to minimize the likelihood of contacting the bottom electrode, the controller should also include terms dependent on the velocity of the movable electrode. Direct sensing of this velocity during normal device operation is typically not feasible. In this paper we show how the electrode velocity may be indirectly sensed using only capacitance and voltage measurements. Our approach is based on well known techniques of nonlinear observer design, and provides arbitrary fast linear error dynamics. Simulation results show excellent performance.
Failure Diagnosis in Rotory Dynamic Systems Based on Finite Element Prediction Model
Authors: Shirkhodaie Amir , Blair Julian , Heard Kemba
Published: May 2008

Machinery such as steam turbines, compressors, and generators are rotating machines. Over the years these machines have become very complex, due to the increased need for higher speed rotating machinery. Overtime these machines develop excessive dynamic stresses if they are ran at speeds near to their natural frequencies or under abnormal operating conditions. Many technological advances in the aerospace and automotive industries can be held accountable for these faster speeds. Currently, machinery diagnostics is being used to monitor rotating machinery and determine their condition while in operation. To determine how a system will behave under certain operation conditions, a physics-based model of the system can be modeled and analyzed using finite element analysis. These results will provide stress, deformation, flexibility, stiffness, and vibration characteristics of the system. These results can show where the critical points are on the system and how the system’s load is distributed. By using finite element techniques engineers can simulate the behavior of the system under different loading conditions, which can justify the selection of a particular design alternative, and ultimately save time and money. This paper discusses our technical approach used to develop a physics-based model of a rotor dynamic system and discusses results of this research effort.
Supervisory Robust Control of Hybrid Electric Vehicles
Authors: Pisu Pierluigi , Rizzoni Giorgio , Silani Enrico
Published: May 2008

The control problems that arise in connection with hybrid powertrains are significant, and pose great challenges to power-train control engineers. Big obstacles to the control design are the model complexity, and the necessity of a knowledge “a priori” of torque and velocity profiles for optimal fuel consumption and exhaust emissions. The aim of this paper is to propose a robust approach to the development of supervisory control strategies for hybrid-electric drivetrains. The objective is to determine an output feedback controller that minimize fuel consumption with respect to a family of possible torque/power input profiles, e.g. urban driving cycles. Sufficient conditions for the existence of a robust controller satisfying stability, L2 gain attenuation between inputs and outputs of interst, and input/output bound constraints are derived by means of a set of linear matrix inequalities (LMIs).
Development of a Computer Model for Induction Hardening of Steel
Authors: Yuan Jiankun , Kang Jinwu , Rong Yiming , Sisson Richard D.
Published: May 2008

Induction hardening is an important manufacturing process to control the mechanical properties of metal parts where surface hardness is enhanced while the core retains the toughness. This paper presents the modeling and simulation of the induction hardening processes with the finite element analysis. A coupled electromagnetic-thermal analysis is applied to the induction heating process. The temperature distributions in parts are obtained in heating and quenching process. The induction heating and quenching are highly nonlinear processes because the materials properties of the parts are temperature dependent. The final hardening process involves the determination of martensite volume content and hardness value. An algorithm is utilized to determine the volume fraction of diffusion controlled metal phase transformation and martensite content. Finally, the hardness value is converted from martensite content. Results for a complex surface hardening are presented. The effects of input power, frequency and air gap on final hardened pattern are systematically studied.
Local Space-Time Adaptive Discontinuous Galerkin Finite Element Methods for Time-Dependent Waves
Authors: Thompson Lonny L. , He Dantong
Published: May 2008

Local space-time adaptive methods are developed including high-order accurate nonreflecting boundary conditions (NRBC) for time-dependent waves. The time-discontinuous Galerkin (TDG) variational method is used to divide the time-interval into space-time slabs, the solution advanced from one slab to the next. Within each slab, a continuous space-time mesh is used which enables local sub-time steps. By maintaining orthogonality of the space-time mesh and pre-integrating analytically through the time-slab, we obtain an efficient yet robust local space-time adaptive method. Any standard spatial element may be used together with standard spatial mesh generation and visualization methods. Recovery based error estimates are used in both space and time dimensions to determine the number and size of local space-time elements within a global time step such that both the spatial and temporal estimated error is equally distributed throughout the space-time approximation. The result is an efficient and reliable adaptive strategy which distributes local space-time elements where needed to accurately track time-dependent waves over large distances and time. Numerical examples of time-dependent acoustic radiation are given which demonstrate the accuracy, reliability and efficiency gained from this new technology.
Understanding Solidification Kinetics and Microstructural Development of a Lead-Free Composite Solder
Authors: Lin D. C. , Kuo C. Y. , Srivatsan T. S. , Wang G.-X.
Published: May 2008

This paper presents and discusses the solidification of Sn-Ag eutectic solder and the effect of cooling rate on its microstructure formation with and without addition of nanosized copper powders. The composite solder mixture was mechanically mixed, and subsequently melted in an aluminum crucible placed in a temperature-controlled furnance, prior to promoting solidification. For all cases significant undercooling of the melt was observed prior to solidification. A reduction in the solidification temperature occurred by the addition of copper nanopowders. Optical microscopy observations revealed the microstructure of solders, in the as-solidified condition, to be appreciably altered by the addition of nanosized copper powders. The copper nanopowders were precipitated as an intermetallic compound. The average size of the intermetallic compound decreased as the cooling rate increased. These results suggest that adding nanosize metallic powders may significantly alter and/or improve solder joint properties.
Electro-Magnetic-Acoustic Transducers for Automatic Monitoring and Health Assessment of Transmission Lines
Authors: Shoureshi Rahmat A. , Lim Sun-Wook , Chenoweth Michael
Published: May 2008

This paper presents analysis, design, development, and experimental verification of a non-destructive monitoring system for diagnostics of electric conductors based on the concept of Electro-Magnetic-Acoustic Transducers (EMAT). Electric conductors, in general, are exposed to harsh environments. Such conductors include electric transmission lines and ground mat risers. For automatic failure detection and assessment of mechanical integrity of these conductors, in addition to an effective transducer, feature extraction and pattern recognition techniques have to be employed. Details of the sensor design, neural-based signature analysis, feature extraction, and results of fault detection techniques are presented. Design of an experimental testbed for performance verification of the sensor and successful implementation of fault classifications are described and results are delineated.
On the Safety of Infeeding Commercial Tree Chippers
Authors: Brickman Dennis B.
Published: May 2008

This paper addresses a commercial mobile tree chipper with a mechanical infeed system that is manually fed. OSHA records associated with commercial tree chipper accidents indicate tree workers have alleged that their arms have been pulled into the chipper feed wheels by branches during the feeding process. An infeed extension pan has been proposed to prevent a tree worker’s arm from being pulled into the chipper feed wheels if his gloved hand gets caught in the branches being fed into the chipper feed wheels if his gloved hand gets caught in the branches being fed into the infeed hopper. Experiments performed with human test subjects and an anthropomorphic dummy are presented under arm pull-in scenarios to study the safety implications of the proposed infeed extension pan.
Design, Construction, and Experimental Evaluation of a Monopropellant Powered Free Piston Hydraulic Pump
Authors: Raade Justin W. , McGee Timothy G. , Kazerooni H.
Published: May 2008

A monopropellant powered free piston hydraulic pump (FPHP) was designed as a human scale (1.0 to 3.0 kW) mobile robotics power supply. The FPHP utilized high concentration hydrogen peroxide, which decomposes into hot gas when exposed to a catalyst, as the monopropellant energy source. Energy was extracted from the hydrogen peroxide and transferred directly to hydraulic fluid by expanding the hot decomposition gas in an integrated piston/cylinder arrangement. The prototype FPHP successfully produced 50 W of hydraulic power by pumping hydraulic fluid at an average pressure of 6.5 MPa (940 psi) and flow rate of 0.48 liters/min (0.13 gallons/min).
Managing and Protecting Infrastructure Assets
Authors: Rees Daniel C. , Rubin Kenneth I.
Published: May 2008

The events of September 11th focused renewed attention on protection of our nation’s critical infrastructure. Utilities across the nation have an increased awareness of risks and are recognizing the potential vulnerability of their physical assets, and also the assets embodied in their employees, their knowledge base, their information technology and their customers. Utilities must now grapple with the possibility that their infrastructure assets may be targets of direct physical threats — or serve as conduits for indirect physical threats. As the concern for protecting our nation’s infrastructure intensifies, each utility is being asked to reassess its ability to provide safe and reliable services to customers and communities as a whole. However, improvements to protection of utility assets must be performed with constraints of limited capital and operating budgets. Security threats from terrorist and related events are relatively new to the utility industry, so standard industry-wide protocols are just now being developed. Serious security practices have evolved in some discrete areas, such as high-risk government buildings, nuclear power plants, and airline terminals. Utility infrastructure physical assets are typically dispersed, so, standard approaches to security (developed for enterprises with highly centralized assets, such as nuclear weapons production facilities) are difficult to apply. Managers must then face a balancing act between demands for security and the resources needed to enact and finance those actions. This paper describes the Vulnerability Self Assessment (VSAT™) methodology and software that provides a structured, cost-effective approach for utilities to assess their vulnerabilities and to establish a risk-based methodology for making necessary changes. The VSAT™ methodology groups utility assets into the classes of People (utility staff), Physical Plant, Knowledge Base, Information Technology Platform, and Customers. The methodology and software are flexible, customizable, and user friendly. VSAT™ software is equally applicable to deliberately caused or natural disasters. In addition to a library of prototypical assets, included in the software application are threat and countermeasure libraries. As users proceed through self-assessments, VSAT™ automatically documents the analysis process during each step. VSAT™ helps users identify critical asset(s) and potential single points of failure (SPFs). The VSAT™ process culminates in a series of risk-reduction-cost reports that presents findings in clear and concise ways. This is important, because the goal is business continuity and, at the end of the day, VSAT™ provides solutions that enable utilities to mitigate risks of business interruptions at least cost.
Distributions of Micro- and Nano-Sized Particles Under Decaying Turbulence in a Chamber
Authors: Zheng Z. Charlie , Zhang N.
Published: May 2008

Distributions of particles from micro- to nano-sizes in a rectangular chamber are investigated under the influence of an impulsively-started, decaying turbulence generated by a jet. The unsteady, compressible flowfield is simulated using a k-ε model and the related turbulence scales are analyzed. Stokes numbers, based on the turbulence microscales and integral scales, are used as the selection criteria for turbulence collision kernels. Population balance models are then used to calculate the particle size distributions. Histories of particle number density at several locations in the chamber have been compared with different initial particle sizes under different jet speeds. Lower coagulation rates have been shown to relate with lower jet speeds.