bluuebunny/crossref_metadata_2025 huggingface dataset:
Calibration With Respect to the Beam Direction of a Non Contact Point Sensor
Authors: Steiner Dvir
Published: April 2008

Accurate calibration is required for high-precision mechanical stages used for inspection of mechanical parts. Because of the high cost involved in purchasing and maintaining Coordinate Measuring Machines (CMM), it is common that a dedicated or reconfigurable inspection machine is designed and built to give a solution for a specific inspection task. High precision stages and high precision sensors that are needed for this task can be purchased as off the shelf products. However, when precision is needed, the assembly of the sensor to a linear stage becomes a complex task. This task becomes even more complex when using a non-contact probe since them are more unknowns added to the problem. In this paper we give a method for calculating the angle between the probe beam and the motion stage. The calculation is done directly from the measurements obtained by the non calibrated system. Using the calculated angle, the inverse of the affine transform resulting from the lack of perpendicularity between the probe beam and the motion stage can be determined and can be fixed in software. The method utilizes a high precision cylinder for the task. By using the proposed method, the assembly of a non contact probe to a linear motion stage becomes as simple as bolting down the bolts on the sensor connection panel. The method has been verified by computer simulation, with and without random noise added to the measurements. The results are presented via graphs and tables at the end of this paper.
Optimization of the Design of Complex Energy Conversion Systems Using Mathematical Programing and Genetic Algorithms
Authors: Ahadi-Oskui Turang , Tsatsaronis George
Published: April 2008

The paper presents two different optimization methods for the cost-effective design of energy conversion systems. Starting point of the optimization is a complex superstructure that allows several alternative design specifications for a combined-cycle-based cogeneration plant to be studied. Depending on the user specified demands for electricity and process steam, the optimization algorithm performs a simultaneous structural and process variable optimization of the design, to minimize the levelized total costs of the plant products. Mathematical programming and specialized genetic algorithms are used as optimization algorithms. These do not only differ largely in their optimization approach but also have different requirements for the modeling of the superstructure. Several optimization cases are presented to examine the applicability of both algorithms on the present optimization problem. A concluding comparison reveals the advantages and disadvantages of each optimization method.
Modal Analysis of Metallic Nanocantilevers With FCC Lattice Using Atomic Approximation Method
Authors: Amiri Farshid , Mahboobi Seyed Hanif , Pishkenari Hossein Nejat , Meghdari Ali
Published: April 2008

In this research, we will use an accelerator for MD simulations, called Atomic Approximation Method, which leads to more efficient simulations without harming the physical properties in simulations. The main idea of this method is to define a virtual material with lower number of atoms, which has the same physical properties as the original material. To demonstrate the validity of the proposed technique the modal analysis results are compared with the ones of the conventional molecular dynamics method. It is shown that this method accelerates conventional MD simulations significantly.
Dynamic Finite Element Modeling of Electrostatically Actuated Micro Structures Considering Squeeze Film Damping Effect
Authors: Ahmadian M. T. , Borhan Hoseinali , Zand M. Moghimi
Published: April 2008

Developing a transient fully-meshed model of coupled-domain microsystems is of paramount importance not only for accurate simulation and design but also for creating more accurate low-order or macro dynamic models. So in this paper, a complete nonlinear finite element model for coupled-domain MEMS devices considering electrostatic and squeeze film effects is presented. For this purpose, we use the Galerkin weighted-residual technique for developing the finite element model that capture the original microsystem's nonlinear behaviors, such as the structural dynamics, the squeeze-film damping, the electrostatic actuation and the geometric nonlinearity caused by inherent residual stresses. In addition, using the Newmark's nonlinear solution, technique, the extracted dynamic equilibrium equations are discretised and simulated. The system dynamic behavior is successfully modeled by using the developed nonlinear finite element model and finally some simulated results of electrostatic microactuator behaviors are verified with experimental findings and are in very good agreement.
Closed-Loop Finite Element Modeling for Analysis of Smart Structures in ANSYS Environment
Authors: Mahboobi Seyed Hanif , Abedian Ali , Shahidi Alireza , Meghdari Ali
Published: April 2008

It would be promising if one can simulate the closed-loop behavior of a smart system in an available FEM software such as "ANSYS". The ANSYS/Multiphysics software has the ability of coupling different physical domains and also modeling smart materials such as piezoelectric and piezoresistives, i.e. it has the capability of modeling smart structures. The dynamic modeling of the controlled structures is then realized by the ANSYS programming tool. This aspect highly facilitates the overall system behavior analysis and at the same time various control methods can be tested without noticing the time consuming structural analysis involved. In this research work, it is tried the mentioned idea to be implemented and some control strategies for the structural active damping to be examined.
Heat Transfer Augmentation Using Fins of Various Cross Section Under Steady State
Authors: Parekh Ashok D. , Banerjee Jyotirmay , Maisuria Mahendra B. , Patel Vimal K.
Published: April 2008

Extended surfaces or fins are used to enhance the heat transfer rate between a solid and adjoining fluid. An experimental investigation is carried out in the present work to establish the heat transfer characteristic for fins made of varying material and varying cross section. Three different fin sections, circular, square and triangular are considered for the study. Aluminum, brass and copper fins with varying cross section along the length are tested under steady state. Experimental set up consists of a constant temperature bath to maintain desired thermal boundary condition at one end of the fin. Copper constantan thermocouples are used to measure the temperature at different sections of the fin. The experimental results of temperature distribution of the fins are compared with the analytical and numerical results. The effectiveness of fins along the length for all section and materials is also compared.
Applications of Virtual Engineering in Combustion Equipment Development and Engineering
Authors: Jian Christopher Q. , Lorra Michael A. , McCorkle Douglas , Bryden K. Mark
Published: April 2008

The implementation of a virtual engineering system at John Zink Company, LLC is starting to change the engineering and development processes for industrial combustion equipment. This system is based on the virtual engineering software called VE-Suite being developed at the Virtual Reality Applications Center (VRAC) of Iowa State University. The goal of the John Zink virtual engineering system is to provide a virtual platform where product design, system engineering, computer simulation, and pilot plant test converge in a virtual space to allow engineers to make sound engineering decisions. Using the virtual engineering system, design engineers are able to inspect the layout of individual components and the system integration through an immersive stereo 3D visualization interface. This visualization tool allows the engineer not only to review the integration of subsystems, but also to review the entire plant layout and to identify areas where the design can be improved. One added benefit is to significantly speed up the design review process and improve the turn around time and efficiency of the review process. Computational Fluid Dynamics (CFD) is used extensively at John Zink to evaluate, improve, and optimize various combustion equipment designs and new product development. Historically, design and product development engineers relied on CFD experts to interpret simulation results. With the implementation of the virtual engineering system, engineers at John Zink are able to assess the performance of their designs using the CFD simulation results from a first person perspective. The virtual engineering environment provided in VE-Suite greatly enhances the value of CFD simulation and allows engineers to gain much needed process insights in order to make sound engineering decisions in the product design, engineering, and development processes. Engineers at John Zink are now focusing on taking the virtual engineering system to the next level: to allow for real-time changes in product design coupled with high-speed computer simulation along with test data to optimize product designs and engineering. It is envisioned that, when fully implemented, the virtual engineering system will be integrated into the overall engineering process at John Zink to deliver products of the highest quality to its customers and significantly shorten the development cycle time for a new generation of highly efficient and environmentally friendly combustion products.
A Method of Decomposing Wave Motions
Authors: Feeny B. F.
Published: April 2008

A method is presented for decomposing wave motion into its principle components. The basic idea is a generalization of proper orthogonal decomposition. The method involves the representation of real oscillatory signals as complex phasors. The relationship between complex modes and wave motion is explored. From an ensemble of complex signals, a complex correlation matrix is formed, and its complex eigensolution is the basis of the decomposition (like a complex singular value decomposition). The complex eigenvectors contain standing and traveling characteristics. A traveling index is proposed to quantify the relative degree of traveling and standing in a waveform. A method of dissecting a wave mode into its traveling and standing parts is also proposed. From the complex modes and modal coordinates, frequencies, wavelengths, and characteristic wave speeds can be obtained. The method is applied to traveling and standing-wave examples.
Modeling of Halide Chemical Vapor Deposition of SiC
Authors: Wang Rong , Ma Ronghui , Dhanaraj Govindhan , Chen Yi , Dudley Michael
Published: April 2008

Halide chemical vapor deposition is used to grow thick SiC epilayers at high growth rate. In this paper we present simulation of HCVD process in a horizontal hot wall reactor. A reaction mechanism for Si-C-Cl-H system is proposed for deposition of SiC using SiCl4/C3H8/H2 mixture. A model for transport of momentum and energy is developed to determine the gas field velocity and temperature distribution. Chemical reactions in the gas phase and on the substrate surface are incorporated into the transport model for predicting gas species transport and deposition. The effects of graphite etching are also accounted for in the model. Numerical simulation is performed to predict growth rate of the film as a function of temperature and gaseous species flow rates.
Bubble Departure and Convection in Large Aspect Ratio Microchannels
Authors: Fogg David W. , Cheng Ching-Hsiang , Goodson Ken E.
Published: April 2008

The growth and departure of vapor bubbles governs pressure drop and thermal resistance of two-phase microchannel heat sinks. Little data is available for the growth, departure, and convection of bubbles in microchannels. The current study uses isothermal air injection to simulate the nucleation and growth of bubbles in high aspect microchannels with Dh≈48μm and aspect ratios from 20 to 40 with 1 < ReH < 10. Liquid pressure drop and flow rate are measured during bubble growth along with the time history of the bubble geometry obtained from a high speed video imaging system at rates up to 50,000 frames per second. Bubble departure is found to vary linearly with aspect ratio divided by inlet Reynolds number, while the convection velocity depends on the normalized bubble width and normalized liquid film thickness. A scaling analysis identifies the increase in axial pressure drop due to bubble confinement as the driving force for both bubble departure and convection.
Ground Excitation and Resonance in Liquid-Filled Tanks
Authors: Yang N. , Warner G. M. , Nayeb-Hashemi H. , Olia M.
Published: April 2008

Recent research has demonstrated that natural frequencies associated with some circumferential modes inn fluid filled tanks may be close to the frequency of earthquake excitation. This can lead to a resonance phenomenon, and consequently failure of the tanks. In this paper, we perform natural frequency analysis of fluid-filled tanks, using finite element analysis. The problem is solved for different geometries and water levels of tanks. Results are provided for circular, cylindrical tanks and cylindrical tanks with coaxial walls and a fluid annulus. Combinations of parameters most likely to cause resonance are presented.
Comparison of the Monte Carlo Method Applied to the Absorption-Line Blackbody Distribution With a Conventional WSGG Model
Authors: Maurente Andre´ , Vielmo Hora´cio A. , Franc¸a Francis H. R.
Published: April 2008

This paper presents results of radiation heat transfer obtained from two gas models: the Absorption-Line Blackbody (ALB) distribution function and a conventional weighted-sum-of-gray-gases (WSGG) model. A typical cylindrical combustion chamber is considered. For the first model, the radiative exchanges are computed with the Monte Carlo, since the ALB distribution function can be directly related to the Monte Carlo cumulative distribution function. For the WSGG model, the radiation heat transfer is solved with the zonal method. Two gaseous mixtures are considered, and represent typical products of stoichiometric combustion of fuel oil and methane. While the Monte Carlo and the zonal solutions match for a gray gas, considerable departures are observed for the gas spectral using the ALB and the WSGG models.
Stability and Fatigue Analysis of Long-Span Continuous Band Saw Blades
Authors: Brown Darren , Glancey Jim
Published: April 2008

Long span, unsupported, continuous steel band saw blades are commonly used for cutting in a number of industries worldwide. A model of the stresses generated in the blade under several loading scenarios are developed and used to evaluate the potential for fatigue failure with different support pulley and blade designs. Torsional blade stability is modeled and used to determine the critical in-plane cutting force above which the blade will twist. The effects of blade thickness and tension on stability are examined. Results indicate that stability can be improved with increasing thickness and tension at the expense of fatigue life. For spans greater than 1.5m, blade tensions required for stability are not practical, and suggest that a blade guide is necessary to achieve required cutting forces.
Self-Propulsion of a Capsule on a Viscous Surface
Authors: McLellan Mark , Fan Mingxuan , Feng Z. C.
Published: April 2008

We propose a mechanical model for a capsule containing a piezoelectric actuator. The interfacial interaction between the capsule and a surface is assumed to be viscous. Nonlinearity in the interfacial force such as shear thickening is assumed to be present. When periodic excitations are applied to the piezoelectric actuator, the capsule is shown to propel itself. The self-propulsion is confirmed through an experimental setup.
A Robotic System for Real-Time Resin Flow Modification During Vacuum-Assisted Resin Transfer Molding
Authors: Kasprzak Scott , Nasr John , Fuqua Michael , Glancey Jim
Published: April 2008

To complement existing resin flow control strategies currently under development for Vacuum-Assisted Resin Transfer Molding (VARTM), and to provide the ability to react to unexpected changes in resin behavior during injection, a new technique for resin flow manipulation has been investigated. This approach consists of a semi-cylindrical shaped vacuum chamber placed on a mold which, when evacuated, increases the permeability of the region under the chamber by lifting the bag atop the mold. A finite element model has been developed to predict the resin flow within the mold while using the external chamber. Laboratory testing has shown significant modification in resin flow with reduced injection time. Using the external chamber, a robotic system has been prototyped that identifies dry regions forming during injection via computer vision, deploys the vacuum chamber over the mold with a robotic arm, and actuates the chamber in order to modify and correct the resin flow within the mold. Test results using lab-scale molds with large variations in preform permeabilities indicate that the robotic system can correct and/or modify the resin flow within a mold in real time, thus eliminating dry, unimpregnated regions. This computer-based method has the potential to significantly enhance molded part quality and consistency by eliminating resin starved regions within a molded composite part.
Enhancement of Machinability of AISI1045 Steel Using Molybdenum Disulphide as a Solid Lubricant
Authors: Reddy N. Suresh Kumar , Rao P. Venkateswara
Published: April 2008

The heat produced during machining is critical in terms of workpiece quality. So, effective control of heat generated at the cutting zone is essential to ensure the workpiece quality in machining, which can be achieved by using coolants. As the coolants are relatively inaccessible to the machining zone due to the typical nature of the process, it has been attempted to study the performance of machining of AISI 1045 steel using molybdenum disulphide as a solid lubricant in the present work. The experimental set up (solid lubricant powder feeder) for molybdenum disulphide assisted machining was designed and built. After ensuring the set up for proper lubrication, experiments were conducted to see the influence of tool geometry (radial rake angle and nose radius) and cutting conditions (cutting speed and feed rate) on the considered machining response while machining AISI 1045 steel. In order to compare the performance of molybdenum disulphide with that of wet machining, the same set of conditions that were conducted with wet condition repeated using molybdenum disulphide as solid lubricant. Results indicate that there is a considerable improvement in the performance of milling AISI 1045 steel using molybdenum disulphide as a solid lubricant when compared with wet machining in terms of surface finish and chip thickness. The experimental results of this work will be used to obtain the relationship between cutting speed, feed rate, radial rake angle, and nose radius on the machining response i.e. surface roughness by modeling.
Vibration Control of Nonlinear Rotating Beam Using Piezoelectric Actuator and Sliding Mode Approach
Authors: Xue X. , Tang J.
Published: April 2008

In this research, we develop a general methodology for the vibration control of nonlinear rotating beam. The dynamic model of a rotating Euler-Bernoulli beam integrated with piezoelectric actuator is formulated. An integral sliding mode control design is proposed for the vibration suppression of the system with nonlinear coupling effects between the hub rotation and the beam transverse vibration. The sliding surface is constructed using part of the system states, and the rotating hub dynamics is treated as the internal dynamics of the system under the condition that the states of the zero dynamics are bounded. The robust stability of the proposed controller is also guaranteed. A series of simulation studies demonstrate that the proposed control method can effectively suppress the beam vibrations induced by the hub rotation and the external disturbance.
Dynamic Analysis of Orthotropic Laminated Composite Plate Under Axial Load on Elastic Foundation
Authors: Ahmadian M. T. , Pirbodaghi T.
Published: April 2008

In this paper, free vibration analysis of laminated composite plates is carried out using first shear deformation theory and finite element method. Effect of axial tension and compression forces on the natural frequencies of the structure is investigated. Applying elastic foundation under the laminated composite plates has enabled us to achieve desired frequencies. The displacements are based C° – nine plate bending element and each node has three degree of freedom. The equations of motion are derived using Hamilton's principle. Results indicate the tension forces will increase the natural frequency while the compression force reduces the natural frequency. The buckling force of plate is computed by increasing the absolute value of compressive force until the natural frequency tends to zero. Dynamic of moving mass in a circular path on the laminated composite plate is also investigated. Displacement of plate center reveals a sinusoidal pattern in time.
Pressure Based Exogenous Force Estimation
Authors: Kontz M. E. , Book W. J. , Frankel J. G.
Published: April 2008

Using pressure transducers to estimate the exogenous force acting on an end effector could be useful for a number of applications. These might include load estimation or diagnostics. In this case, it is motivated by haptic control of backhoes/excavators. Using pressure transducers is attractive from a cost point of view because they are relatively inexpensive and more importantly already present on many electro-hydraulic systems. Measuring the cylinder pressure and multiplying by the respective areas give the total force on each cylinder that is produced by the hydraulic pressure. Embedded in this force is cylinder and structural friction, gravitational forces, inertial/Coriolis/centrifugal forces and exogenous forces acting on the end effector. Particularly challenging is the friction inside the cylinders which is not only velocity dependent, but also pressure dependent. The friction increases as the pressure inside the cylinders push harder on the seal. This paper discusses how to remove the unwanted force components which result in an estimation of the exogenous force on the end effector. Experimental results are presented from a backhoe test-bed and the new method is compared with previous work related to this topic.
Experimental Identification of the Nonlinear Parameters of an Industrial Translational Guide
Authors: Dhupia Jaspreet , Powalka Bartosz , Ulsoy A. Galip , Katz Reuven
Published: April 2008

Prediction of machine dynamics at the design stage is a challenge due to lack of adequate methods for identifying and handling the nonlinearities in the machine joints, which appear as the nonlinear restoring force function of relative displacement and relative velocity across the joint. This paper discusses identification of such a nonlinear restoring force function for an industrial translational guide for use with the Nonlinear Receptance Coupling Approach (NLRCA) for evaluating machine dynamic characteristics. Translational guides are among the most commonly used joints in machine tools. Both a parametric and nonparametric technique has been employed to identify the nonlinearities. A novel parametric model based on Hertzian contact mechanics has been derived for the translational guide. This model includes the effect of joint geometry, material properties and preload. A nonparametric method based on two-dimensional Chebyshev polynomials is also used. The models derived from the two techniques, i.e., parametric and nonparametric, are fitted to the experimental data derived from static and dynamic tests to get the restoring force as a function of relative displacement and relative velocity across the joint. The resulting joint model exhibits a weakly nonlinear stiffness term and a viscous damping term. The results from both techniques are compared in the frequency domain. The advantages and disadvantages of parametric and nonparametric techniques are also discussed. The design of experiments for evaluating the nonlinearities in such industrial machine tool joints is a challenge, requiring careful alignment and calibration, because they are typically very stiff. This constrains the dynamic experiments to be carried out at high frequencies (e.g. 2000-7000Hz) where the experimental readings are very sensitive to errors in geometry and calibration.
Experimental Verification of Rarefied Gas Squeezed-Film Damping Models Used in MEMS
Authors: Mol Lukas , Rocha Luis A. , Cretu Edmond , Wolffenbuttel Reinoud F.
Published: April 2008

Existing compact parallel-plate squeeze-film models including rarefaction and border effects are verified using the experimental results of a new electrostatic MEMS actuation technique that enables full gap positioning. Measurements at high Knudsen numbers ranging from 0.03 to 0.18 are performed and results compared to the models. The simulation errors are confirmed to be lower than 20%. The experiments also indicate that both gas rarefaction and border effects have to be included in any model.
Electrical Resistivity Characterization and Modeling of Carbon Nanofiber-Polymer Suspension
Authors: Hsiao Kuang-Ting , Gadalla Peter , Donovan Francis M.
Published: April 2008

Carbon nanofibers (CNFs) and carbon nanotubes (CNTs) are considered as potential fillers for improving the mechanical, thermal, and electrical properties of polymer and polymer composites. One of the applications is to enhance the electrical conductivity of polymer by using CNFs as fillers. This kind of treatment will be useful in the situations where electrostatic dissipation capability of the polymer part is important. This paper presents an investigation of the electrical resistivities of CNF/polymer suspensions of different CNF concentrations, i.e., 2.0wt%, 3.0wt%, 4.5wt%, and 6.0wt%. For determining the electrical resistivities of the CNF/polymer suspensions, a DC-sensor was constructed and used in the experiments. The experimental results indicate that the electrical resistivity of the CNF-polyester suspension decreases as CNF weight fraction increases. In addition, the results show a dramatic decrease of the resistivity when the measurement time prolongs. An empirical model to predict the electrical resistivity evolution of the CNF/polyester suspension was proposed in this paper. Good agreement between the empirical model predictions and the experimental results was found.
Modeling and Simulation of Hydromechanically Constant Power Controlled Swash Plate Pumps
Authors: Kassem Saad A. , Anis Yasser H.
Published: April 2008

This paper presents a theoretical study of the performance of constant power operated swash plate pumps equipped with hydromechanical controllers incorporating either pivoted levers or two feedback springs. Mathematical models of these controllers are derived and used to simulate the static and dynamic characteristics of a small pump of 40 cc/rev geometric volume. Results show that the controller with the pivoted lever renders better static and dynamic characteristics compared to the controllers with feedback springs. Results also show that changing the power through varying the lever arm length is preferable than varying the valve spring initial compression, when the dynamic characteristics of the pumps with controllers of pivoted levers are considered. The effect of the valve spring initial compression on the static performance of a pump incorporating a controller with two feedback springs is also investigated.
Non-Iterative Solution of Ordinary and Partial Differential Equations Using Spreadsheets
Authors: Fakheri Ahmad , Naraghi Mohammad H.
Published: April 2008

Typically, in a basic course, the equations are derived and the solutions are presented in tabular or chart from. Spreadsheets provide an attractive option, as most students have access to and are familiar with their use. In this paper, a classic algorithm, called Thomas algorithm, used for the solution of set of algebraic equations whose coefficient matrix is tri-diagonal, is adopted to spreadsheets. It is used to obtain solutions to a number of classical problems in fluid mechanics and heat transfer non-iteratively, and in some cases where the governing equations are non-linear via some iterations. Without needing much programming skills, or needing to learn specialized software, undergraduate students can use this approach and easily obtain the solution to many otherwise difficult problems and study the impact of different parameters.
Implementing Support for Management of Mechatronic Product Data in PLM Systems: Two Case Studies
Authors: Bergsjo¨ Dag , Malmqvist Johan , Stro¨m Mikael
Published: April 2008

In this study, product information models of two different companies both developing advanced mechatronic products are described, compared, and implemented in demonstrators. This has been done in order to investigate to what extent currently available PLM systems can manage this integration. The study shows that requirements for mechatronic product data are rather similar in the two companies. Differences involve the amount of product data generated in a development project, but there are also other differences related to development traditions. The contribution of the study is an evaluation of how integrated information models for mechatronic development can be managed in PLM systems. It is concluded that this can be done, however this requires a modified approach to software engineering.
Robust Stability Analysis of “Unstructured” Convex Combinations of Matrices With Applications
Authors: Yedavalli Rama K.
Published: April 2008

This paper presents new insight into the robust stability analysis of families of matrices described by convex combinations of Hurwitz stable 'vertex' matrices. Significant new insight is provided that removes many misconceptions that currently prevail in this problem formulation. In this connection, careful distinction is made between 'Structured' and 'Unstructured' convex combinations of matrices. The convex combinations arising from an uncertain matrix with interval parameters is labeled as 'structured' convex combinations whereas the convex combinations of 'user specified' Hurwitz stable vertex matrices are labeled as 'unstructured' convex combinations. It is clearly shown that the convex combination property in matrix case is dictated more by the nature of the 'vertex' matrices rather than by simply assigning values to the coefficients of the combination. From this analysis, it is clearly established that 'structured' and 'unstructured' convex combinations are two entirely different problem formulations and one is not a special case of the other as it is currently believed. Thus even the solution algorithms for checking the stability of these matrix families are different. After establishing this distinction, this paper then concentrates on the 'unstructured' case and provides a 'vertex solution' to a specific three vertex convex combination problem. The algorithm is illustrated with several examples. This contribution suggests that there is still considerable research needed to appreciably enhance the knowledge base in the important area of robust stability analysis of matrix families which arise in various applications.
On-Off Control for Full-Gap Positioning of Parallel-Plate Electrostatic MEMS
Authors: Mol Lukas , Rocha Luis A. , Cretu Edmond , Wolffenbuttel Reinoud F.
Published: April 2008

Electrostatic parallel-plate actuators are classically limited to displacements up to 1/3 of the gap due to the pull-in effect [1],[2]. A closed-loop feedback based method presented in [3] is recently introduced to overcome this limitation. Optimized structures are designed to minimize residual position ripple while maintaining bandwidth, effectively reducing the required device size by a factor three.
Investigation of a Bioinspired Whisker-Like Fluid Motion Sensor
Authors: Hill Jonathan , Bart-Smith Hilary , Barbier C. , Humphrey J. A. C.
Published: April 2008

Sensors and sensing technologies to obtain flow information at near real time for the control of new underwater morphing structure applications are being investigated. Inspiration for a new type of fluid motion sensor finds its origin in the vibrissae (whiskers) of seals. Recent research has shown the remarkable sensitivity and specificity of these biological sensors to detect hydrodynamic trails left by potential prey. The impressive sensory performance characteristics of seal whiskers suggest the developmental potential for corresponding synthetic fluid motion sensors. An analytical study of the dynamic response of a synthetic whisker-like beam has been carried out to understand its response to predefined vortical flow fields. A parametric study has been conducted to examine how the geometrical and material parameters (i.e. length, cross-section, and stiffness) can be manipulated to produce characteristic responses for different applications. This theoretical understanding is being used in a companion experimental study to develop a synthetic whisker-like sensor. The performance characteristics of the experimental sensor are compared to the beam model predictions.
Macromechanical/Micromechanical Characterization of Welds in Aluminum by Combined Experimental/Numerical Approach
Authors: Thoppul Srinivasa D. , Gibson Ronald F.
Published: April 2008

In this paper, elastic moduli of both the base metal and weld zone are estimated for aluminum welds by combined experimental/numerical approaches based on vibration testing, static testing and Finite Element (FE) methods. The general approach used is to indirectly determine the elastic properties by combining either experimental modal vibration analysis data or static 3-point bend test data with the corresponding finite element analytical model. Two types of welded joints, A1 6061 arc welded and A1 6111 spot friction welded (SFW) lap joints were considered. Modal vibration characteristics obtained from the experiments were compared with the corresponding FE model results at the macromechanical level, and the weld zone modulus was indirectly determined so as to give the best agreement between predicted and measured modal frequencies. The results indicate a modulus reduction of 15 % to 45 % for the weld zone depending on whether it is two sided or one side arc welded sample, and whether only the first mode or several modes are used, but results are inconclusive for the SFW samples due to uncertainty about modeling of weld zone material and/or geometric properties.
Nonlinear Robust Control Design for a Supercavitating Vehicle
Authors: Mao X. , Wang Q.
Published: April 2008

Supercavitating vehicles can achieve very high speed but also pose technical challenges in maneuvering, system stability and control. Compared to a fully-wetted vehicle for which substantial lift is generated due to vortex shedding off the hull, the supercavitating vehicles are enveloped by gas surface thus the lift is provided by control surface deflections of cavitator and fins, as well as planing force between the vehicle and the cavity. The nonlinearity in the modeling of cavitator, fin, and in particular, the planing force make the control design more challenging. In this paper, a sliding-mode based controller is designed for the longitudinal dynamics of a supercavitating vehicle model. The stability and robustness of the final design are analyzed by the Lyapunov method and verified using simulation. A high-gain observer is also designed to estimate the vertical velocity of the supercavitating vehicle, which is not directly measurable, and then simulation results are presented for the (partial) output-feedback sliding-mode controller.
Design of Spatial Electronic Circuit Carrier by the Example of a Miniature Robot
Authors: Kaiser Ingo A. , Frank Ursula , Gausemeier Juergen , Pook Sebastian
Published: April 2008

Miniaturization, high reliability and low manufacturing costs require close spatial integration of mechanics and electronics. New production technologies such as MID (Molded Interconnect Devices), with which spatial electronic circuit carriers can be manufactured, offer intriguing possibilities. However, these production technologies already determine the product concepts. The product and the production system development must be interrelated. This development will be shown through the example of a miniature robot. The miniature robot is supposed to be manufactured in large quantity. It is to act as an experimental object for swarm intelligence and multi-agent applications of computer science, as well as using the Technology MID. A new methodology is necessary for the design of systems with MID. This paper describes first a procedural model for the integrated design of 3-D molded interconnect devices. And then it presents the specification techniques for the constant cross-domain description of such systems, from the principal solution to prototypes. The procedure and the application of the specification techniques are shown through the example of the housing of an autonomous miniature robot.
A Study of Composite Strengthening Through Application of an Electric Field
Authors: Sierakowski Robert L. , Telichev Igor Y. , Zhupanska Olesya I.
Published: April 2008

This paper studies effects of an electric field on the mechanical response of unidirectional carbon fiber polymer matrix composites. The existing experimental evidence suggests that exposure of a composite material to the electromagnetic field leads to changes in the material's strength and resistance to delamination. We have analyzed the effects promoting this phenomenon: coupling of mechanical and electromagnetic fields and Joule heat effects and develop an experimental setup for impact tests of the composites carrying an electric current. Experimental results of low velocity impact tests on unidirectional carbon fiber polymer composite plates carrying a DC electric current show that electrified composites fail at higher impact load. Moreover, a larger electric field leads to a larger impact load that may be sustained by the composite. Finally, analysis of the Joule heat effects reveals that it is not a primary mechanism for the strengthening phenomenon observed in the experiments.
Smart Material Electrohydrostatic Actuator for Intelligent Transportation Systems
Authors: Rupinsky Michael J. , Dapino Marcelo J.
Published: April 2008

Future intelligent transportation systems require actuation systems that are lightweight, compact and have a large power density. Due to their solid-state operation, fast frequency response, and high power-to-weight ratio, electrohydrostatic actuators based on smart materials are attractive as a replacement for conventional hydraulic actuators. This paper is focused on the development of a smart material pump for EHAs in which mechanical vibrations produced by a magnetostrictive terbiumiron-dysprosium alloy are rectified by means of diode-type mechanical reed valves. A maximum blocked pressure differential of 1100 psi is achieved with a power consumption of 84 W. A linear dynamic system model of the magnetostrictive pump is presented. The linear model quantifies the maximum pressure and electromechanical coupling of the magnetostrictive pump and facilitates the determination of system parameters from simple experimental measurements.
Robustness Evaluation of Mapping Techniques for Automated Servo Robot Design
Authors: Hansen Michael R. , Andersen Torben O.
Published: April 2008

Work has been carried out to investigate some of the important design parameters and performance criteria that should be addressed when designing servo mechanisms and, subsequently, to put forward a computationally efficient design procedure. Emphasis is put on the handling of the discrete design variables. A two-stage approach is presented that uses dimensionless parameters that maps data bases of commecially available components. At the first stage the dimensionless parameter are allowed to assume any value. At the second stage the dimensionless parameters are pushed towards integer values by means of penalization techniques. A three-degree of freedom open chain spatial mechanism is used as the fixed mechanism topology of the study. Each drive consists of an inverter driven servo motor attached to a planetary gear. In the optimization the design are evaluated based on a typical working cycle involving the positioning of a certain payload. The design criteria include costs of drives and structural components, tool point precision, fatigue in welded details, over heating and stalling of the motors and gears as well as time of operation. The work is a continuation of previous work and emphasis in this paper is on the robustness of the method and the organization of the data bases.
Micro and Nanofluidic Transport Using Advanced Photonic Devices
Authors: Yang Allen , Mandal Sudeep , Erickson David
Published: April 2008

A number of emerging "optofluidic[1]" technologies exploit the exploitation of the high optical intensities and field gradients present in nanophotonic and optoelectronic devices to accomplish tunable particle trapping and ultrafine propulsion. While well developed theory for exists for freespace optical transport techniques (e.g. optical tweezing), there exists a considerable lack of fundamental understanding of the coupling of the electromagnetic fields and fluid/transport dynamics within these nano-environment. In this work we will present our recent theoretical, experimental and numerical work geared towards developing a better understanding and exploitation of these systems.
Stress Analysis for Novices Using Autodesk Inventor
Authors: Dues Joseph Francis
Published: April 2008

Finite element analysis (FEA) is a numerical method for calculating stress and strain (and other quantities) in structures that cannot be easily analyzed any other way. FEA analysts use complex software to create a mathematic representation of the physical structure being studied, apply loads to the structure and then solve for the resulting displacements and stresses. In years past, FEA was performed by highly trained analysts with master's level engineering degrees or higher. Today, the combination of competitive market pressures, powerful computer hardware and well designed software has resulted in CAD designers being asked to perform FEA early in the design process. To enable these designers to perform FEA analysis, solid modeling software vendors have incorporated FEA into their solid modeling and design drafting packages. Autodesk Inventor Professional 9 now includes FEA capability from ANSYS, Inc. Earlier versions of this software (without FEA) were used at this University to instruct students in solid modeling and design drafting. With new and ever expanding software capabilities, faculty had to determine how to prepare engineering technology students to use the software appropriately. This paper begins with a discussion of the implementation of FEA in Inventor and strategies for educating engineering technology students in FEA. Then it describes an assignment that demonstrates the stress analysis capability of Inventor after the students have mastered solid modeling. This paper discusses the assignment and compares the results achieved by the students to the expected stress values. Each of the steps of the FEA procedure is examined; define the geometry and material, apply constraints, apply loads, solve and then interpret the results; and the likely areas of student error are discussed. Lastly is a description of the assessment, evaluation and planned improvements to the FEA assignments.
A W-Band Horn Antenna Using Self-Aligned 3D Plastic Embossing Process
Authors: Sammoura Firas , Lin Liwei
Published: April 2008

We have demonstrated a waveguide-fed, W-band horn antenna using a three-dimensional (3D), polymeric micro hot embossing process. Two cavity resonators were designed to reduce the impedance mismatch between the horn antenna and the feeding waveguide at a 90° bend. High Frequency Structure Simulator (HFSS) was used to simulate for the performance of the waveguide-fed horn antenna. The antenna directivity and return loss at 95GHz were simulated at 16.56dB and 14.5dB respectively. The measured performance shows impedance match better than 10dB between 76.5~101.7 GHz and 17.5dB at 95GHz. The 3dB beamwidths of the E- and H-plane patterns are 26° and 23° respectively and the total directivity is 17.33dB. The cross-polarized component in the E- or H-planes was 20dB lower than the peak of the corresponding co-polarized component indicating the antenna robustness in rejecting signals with undesired polirization. This plastic, low-cost manufacturing process opens up opportunities in replacing the expensive metallic components with integrated 3D polymeric manufacturing for current and future millimeter-wave systems.
Model Based Power-Split and Control for Electric Energy System in a Hybrid Electric Vehicle
Authors: Kumar Rajneesh , Yao Bin
Published: April 2008

In this paper, a configuration of electric energy storage system for Hybrid Electric Vehicles has been proposed that consists of a small battery and ultracapacitor pack coupled to the vehicle bus through dc-dc converters. The entire system, together with necessary power electronics pack, has been modeled and a Model Predictive Controller (MPC) has been designed for the purpose of power management of the linearized system. This controller has been simulated with the nonlinear plant for charging and discharging current profiles and is shown to be working well around the equilibrium point of the plant. Results show the effectiveness of this approach in keeping the battery current small and steady during fast transients and peak load conditions.
Accelerating Parameterizaton of Large-Scale Dynamic Models Through the Use of Activity Analysis
Authors: Sohns Bryon J. , Allison James , Fathy Hosam , Stein Jeffrey L.
Published: April 2008

Previous research presents both sensitivity-based and principal component-based techniques for improving the tractability of system identification. Both have proven viable, but the former may be computationally inefficient for large problems, and the latter require a change of realization that may compromise the physical meaning of the parameters to be identified. This paper proposes for the first time the use of activity analysis, an efficient and realization-preserving model reduction technique, for identification space reduction. Theoretical and numerical studies highlighting the viability of activity analysis versus the previous two methods are presented.
Aging Characterization of Nickel: Metal Hydride Batteries Using Electrochemical Impedance Spectroscopy
Authors: Chehab Zakaria , Serrao Lorenzo , Guezennec Yann G. , Rizzoni Giorgio
Published: April 2008

During a battery's lifetime, its performance slowly deteriorates because of the degradation of its electrochemical constituents. This degradation produces undesirable effects that include the loss of rated capacity, faster temperature rise during operation, less charge acceptance, higher internal resistance, lower voltage, and more frequent self-discharge. The most drastic effect is the loss of capacity. This paper presents a method to quantify the electrochemical process behind the aging of a battery by using electrochemical impedance spectroscopy as a tool to measure the change in battery parameters. While classical methods would relate battery age to impedance measurements at one specific frequency, this method measures the battery impedance at different frequencies and evaluates the variation in the frequency response spectrum with respect to battery age. The variation of the impedance spectrum from one experiment to another allows to get a better characterization of the aging process.