bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer-Aided Tissue Engineering in Whole Bone Replacement Treatment
Authors: Wettergreen M. , Bucklen B. , Sun W. , Liebschner M. A. K.
Published: April 2008

Tissue engineering is developing into a less speculative field involving the careful interplay of numerous design parameters and multi-disciplinary professionals. Problem solving abilities and state of the art research tools are required to develop solutions for a wide variety of clinical issues. One area of particular interest is orthopaedic biomechanics, a field that is responsible for the treatment of over 700,000 vertebral fractures in the U.S alone last year. Engineers are currently lacking the technology and knowledge required to govern the subsistence of cells in vivo, let alone the knowledge to create a functional tissue replacement for a whole organ. Despite this, advances in Computer Aided Tissue Engineering (CATE) are continually growing. Using a combinatory approach to scaffold design, patient-specific implants may be constructed. Computer aided design (CAD), optimization of geometry using voxel finite element models or other optimization routines, creation of a library of architectures with specific material properties, rapid prototyping, and determination of a defect site using imaging modalities highlight the current availability of design resources. Our study represents a patient specific approach for constructing a complete vertebral body via building blocks. Though some of the methods described cannot be realized with current technology, namely complete construction of the vertebral body via FDM, the necessary advances are not far off. Computing power and CAD programs need to improve slightly to allow the rapid generation of complex models that would ease the fabrication of an appropriate number of building blocks. The main bottleneck of the process described in this study is the general lack of knowledge of human mechanobiology and the role of cellular interactions on artificial substrates including immune responses, and foreign body reactions. Assuming these biological parameters can be identified, a scaffold may be designed with a proper pore size and interconnectivity, microstructure, degradation rate, and surface chemistry. The advantage of the outlined process lies in adjustment of the vertebral compliance first, to ensure adequate load transfer, an important property for vertebral replacement. Subsequently, net biological properties can be fine tuned by simply scaling the final construct. Mixing and matching of geometries may be utilized to design asymmetric scaffolds, or scaffolds that exhibit a discontinuous microstructural stiffness with the goal of accentuating fluid flow. Finally, while these techniques lend themselves to the formulation of bone constructs, they can be used for other parts of the body as well that do not require load-bearing support.
Interconnecting Microfluidic Package and Hybrid Interface for Chip-Based Sensor
Authors: Palsandram Naveenkumar S. , Zhang Peng , Pepper Michael , Lee Moosung , Cho Hyoung J.
Published: April 2008

In realizing a portable chemical analysis system, adequate partitioning of a reusable component and a disposable is required. For successful implementation of micromachined sensors in an instrument, reliable methods for interconnection and interface are in great demand between these two major parts. In this work we investigated interconnection methods of micromachined chip devices and hybrid fluidic interface system. The interconnection method based on micromachining and injection molding techniques was developed and an interconnecting microfluidic package was designed, fabricated and tested. For the hybrid interface, sequencing of the chemical analysis was examined and accordingly, syringe containers, a peristaltic pump and pinch valves were assembled to compose a reliable meso-scale fluidic control unit. The system using the interconnecting package and the hybrid interface was tested for a chip-based sensor.
Effect of a Magnetic Field on the Heat Transfer Rate on Free Convection in a Rectangular Cavity
Authors: Gutierrez Gustavo , Medici Ezequiel
Published: April 2008

The interaction between magnetic fields and convection is an interesting phenomenon because of its many important engineering applications. Due to natural convection motion the electric conductive fluid in a magnetic field experiences a Lorenz force and its effect is usually to reduce the flow velocities. A magnetic field can be used to control the flow field and increase or reduce the heat transfer rate. In this paper, the effect of a magnetic field in a natural convection flow of an electrically conducting fluid in a rectangular cavity is studied numerically. The two side walls of the cavity are maintained at two different constant temperatures while the upper wall and the lower wall are completely insulated. The coupling of the Navier-Stokes equations with the Maxwell equations is discussed with the assumptions and main simplifications assumed in typical problems of magnetohydrodynamics. The nonlinear Lorenz force generates a rich variety of flow patterns depending on the values of the Grashof and Hartmann numbers. Numerical simulations are carried out for different Grashof and Hartmann numbers. The effect of the magnetic field on the Nusselt number is discussed as well as how convection can be suppressed for certain values of the Hartmann number under appropriate direction of the magnetic field.
Kinematic Variation and Modeling for Design in Ornithoptic Flight
Authors: Dietl John M. , Garcia Ephrahim
Published: April 2008

During soaring forward flight, larger birds such as raptors generate most of their lift in a manner consistent with the lift generated by fixed-wing aircraft. However, in flapping flight there is an additional flow field that must be superimposed to account for thrust generated. The aerodynamic forces can be analyzed using conventional strip theory techniques and integrated across the wingspan and over the entire flapping cycle. Oscillating wing pitch causes the lift vector to contribute to forward thrust and effects useful angles of attack. This paper seeks to predict which kinematic parameters of flapping flight will allow for sustained forward flight. Using a mathematical model for flapping flight and a genetic algorithm, kinematic parameters are selected that provide sufficient lift and thrust while attenuating aerodynamic power consumption. The results show that separate degrees of freedom are necessary for twisting and heaving motions to yield acceptable flight conditions.
Robust Time-Optimal Command Shaping for Piezoelectric Actuators: STM Application
Authors: Xu Y. , Meckl P. H.
Published: April 2008

A scanning tunneling microscope (STM) uses a piezoelectric actuator to perform constant-velocity scanning motion. Many feedback strategies have been proposed, but their achievable scan rate is substantially limited by the turnaround transients in the scan path. Therefore, a robust time-optimal command shaping technique with an iterative search procedure is introduced in this paper to improve the scan speed of piezoactuators, and is applicable to a general class of systems without rigid-body mode. Furthermore, a time-energy-optimal formulation is presented to reduce the in-maneuver oscillation. The hysteresis nonlinearity of piezoactuators is compensated using the proposed continuous numerical inversion algorithm. Finally, the closed-loop simulation shows the performance robustness in the presence of hysteresis cancellation error and natural frequency perturbation.
Characterization and Optimization of Berdut Technology for a Magnetically Levitated Train
Authors: Medici Ezequiel , Serrano David , Robles Jeffrey
Published: April 2008

Berdut Technology is a novel magnetic levitation system suitable for high speed train applications. This technology combines magnets and electromagnets to obtain levitation and propulsion. A Berdut array of permanent magnets is used to provide the levitation via skates that are located on both sides of the vehicle. Both the rails and the skates are based on permanent magnets therefore no energy is required for levitation. A linear motor located along the center of the vehicle provides the propulsion. Both, skate and linear motor use the same concept and working principle. The paper is divided into two parts: the first part describes the skate levitation, while the second part describes the linear motor. Finite element method was chosen to model and simulate both the skate levitation and the linear motor. Energy dissipation resulting from hysteresis and eddy current losses in the skate was determined. Stiffness and damping characteristics for the levitation skates are presented and validated. The efficiency and thrust force for the linear motor model are also presented along with experiments performed to validate the simulations. Once, validated the models are used to design a Maglev suspension and a linear motor for high-speed train applications.
Experimental and Numerical Investigation of Melting in the Presence of a Magnetic Field: Simulation of Low Gravity Environment
Authors: Zhang H. , Sun H. , Charmchi M. , Veilleux D. , Faghri M.
Published: April 2008

An experimental and numerical study is presented on melting behavior of a pure metal in the presence of a static magnetic field. When a transverse magnetic field is present and the working fluid is electrically conductive, the resulting Lorentz forces will dampen the convective flows. Buoyancy driven flow is the focus of this study. Hartmann number, a dimensionless parameter proportional to the strength of magnetic field, dominates the convection flow suppression. The effects of the magnetic strength on melting rate and on the profile of solid/melt interface are studied. The experiments are conducted with pure Gallium as phase change material (PCM) inside a rectangular test cell. The solid/melt interface at the side center position is measured by an ultrasound device and its profile is mapped via the florescent light shadowgraphy. Temperature measurements and volume expansion/contraction tracking are used to verify the experimental result. The results show that the magnetic strength has a remarkable effect on the melting rate and the interface profile. The numerical simulation fits very well with the experimental data especially, at larger Hartmann numbers.
Life Cycle Product Design (at “Factor 10” Level): A Case Study Involving Innovative Mechanical Design of a Remote Area Ground Water Pumping System
Authors: Dartnall W. John , Johnston Stephen
Published: April 2008

For humanity to be able to meet its needs without compromising the ability of future generations to meet their own, we must create a sustainable and customised service economy. For all the people of the world to be able to share in this goal, including both marginal operators in economically developed countries and most farmers in currently less economically developed countries, we need to increase resource productivity by a factor of 10. This paper describes a conceptual design process in which the designer is looking to achieve this factor 10 improvement at a system design level. Order of magnitude upgrading, on the performance of existing products, calls for an innovative approach to the design process. We outline a methodology, “Trend-Morph-PDS”, and show in a case study how it has been applied to the development of a ground-water pumping system. This type of system is in demand in geographically remote areas, where low well yield rates are typical, and rather complicated wind or solar pumps are commonly used for these “low-yield-well pumps”. The large number of products on the market demonstrates a wide and often conflicting range of trends in terms of design/development: long life/short life; high efficiency/low efficiency; problematic maintenance; absence of product range rationalisation. There is, however, a general trend towards replacement of mechanical with electrical-electronic systems. We argue that it would be possible to replace the currently dominant types of electrically driven submersible pump with a well designed mechanical system that has approximately twice the efficiency of its competitors and five times the design life. We recognise the commercial importance of the initial system cost, and we see no reason why our system should cost more than those of our existing competitors. Our case study indicates that factor 10 improvement in resource productivity is achievable in this application.
A New Dynamic State Space Model for the Cylindrical Grinding Process
Authors: Lee Cheol W.
Published: April 2008

A new dynamic state space model is proposed for the in-process estimation and prediction of part qualities in the plunge cylindrical grinding process. A through review on various grinding models in literature reveals a hidden dynamic relationship among the grinding conditions, the grinding power, the surface roughness, and the part size due to the machine dynamics and the wheel wear, based on which a nonlinear state space equation is derived. After the model parameters are determined according to the reported values in literature, several simulations are run to verify that the model makes good physical sense. Since some of the output variables, such as the actual part size, may or may not be measured in industry applications, the observability is tested for different sets of outputs in order to see how each set of on-line sensors affects the observability of the model. The proposed model opens a new way of estimating the part qualities such as the surface roughness and the actual part size based on application of the state estimation algorithm to the measured outputs such as the grinding power. In addition, a long term prediction of the part qualities in batch grinding processes would be realized by simulation of the proposed model. Possible applications to monitoring and control of grinding processes are discussed along with several technical challenges lying ahead.
Estimating Parameters of a Packed Bed by Least Squares and Markov Chain Monte Carlo
Authors: Emery A. F. , Valenti E.
Published: April 2008

Most parameter estimation is based upon the assumption of normally distributed errors using least squares and the confidence intervals are computed from the sensitivities and the statistics of the residuals. For nonlinear problems, the assumption of a normal distribution of the parameters may not be valid. Determining the probability density distribution can be difficult, particularly when there is more than one parameter to be estimated or there is uncertainty about other parameters. An alternative approach is Bayesian inference, but the numerical computations can be expensive. Markov Chain Monte Carlo (MCMC) may alleviate some of the expense. The paper describes the application of MCMC to estimate the mass flow rate, the heat transfer coefficient, and the specific heat of a packed bed regenerator.
Preliminary Concepts for Deployable Wings on Small UAVs Using Compliance
Authors: Landon Steven D. , Magleby Spencer P. , Howell Larry L.
Published: April 2008

Advances in technology for Unmanned Air Vehicles (UAVs) have given rise to increasingly smaller UAVs and a growing need for adaptable UAV wing structures. Deployable, or collapsible, wings offer space savings and broaden the number of possible applications for UAVs. Aerial surveillance applications, such as military reconnaissance, law enforcement, forestry, map making, pipeline surveillance, and border patrol typically demand a UAV that can be carried and deployed by a single user in an isolated field. This paper provides a framework of deployable wing concepts using compliant mechanisms. Compliant mechanisms offer reduced part count, decreased need for lubrication, efficient manufacturability, and space savings compared to traditional joint systems. The design space for compliant deployable wings is explored, concepts are categorized into classes based on motion type, and opportunities are identified for creating new concepts. A method is presented for selecting and evaluating concepts for specific applications. A product development project illustrates selection of a deployable wing design for a particular application, and the paper concludes with suggestions for further work.
Market Strategy Skills: A Learner-Centered Approach
Authors: Bauer Candice
Published: April 2008

Market strategy skills are essential for engineers. A lesson plan that teaches introductory market strategy skills to engineering students is developed. The lesson plan is designed for junior level undergraduate students to meet some of the Accreditation Board for Engineering and Technology (ABET) 2005-2006 Criteria 3 (program outcomes and assessment). The challenge is to convey market strategies using a learner-centered approach into an engineering course. The first lesson is to demonstrate the difference between concurrent engineering and “over-the-wall” engineering. After this exercise, a discussion on key terms in product development and marketing is conducted. The key terms that are defined are core competence, continuous innovation, discontinuous innovation, dominant design, acceptability, adaptability, market entry, barriers, first to market, and late to market. Case studies are used to teach students basic marketing terms helping them to understand how to design products to solve for a need within constraints (ABET Criteria 3C), techniques to identify and solve problems (ABET Criteria 3E), and how engineering impacts society (ABET Criteria 3H). The fully developed lesson plans, best practices, and student responses are presented.
Molecular Dynamics Simulations of Dislocation Nucleation From Bicrystal Interfaces in FCC Metals
Authors: Spearot Douglas E. , Jacob Karl I. , McDowell David L.
Published: April 2008

Atomistic simulations are used to study dislocation nucleation from <001> tilt bicrystal interfaces in copper subjected to a tensile deformation. Specifically, three interface misorientations are examined, including the Σ5 (310) interface, which has a high density of coincident atomic sites. The initial interface configurations, which are discussed in terms of structural units, are refined using energy minimization techniques. Molecular dynamics simulations are then used to deform each interface in tension. The role of boundary conditions and their effect on the inelastic deformation response is discussed in detail. Molecular dynamics simulations show that the interface structural units are directly involved in the partial dislocation nucleation process. The maximum tensile strength of the Σ5 (310) interface shows a modest increase in the case where lateral confinement of the interface is an important consideration.
Simplified Manufacturing Through a Metamorphic Process for Compliant Ortho-Planar Mechanisms
Authors: Carroll Daniel W. , Magleby Spencer P. , Howell Larry L. , Todd Robert H. , Lusk Craig P.
Published: April 2008

Most simplified manufacturing processes generally result in two-dimensional features. However, most products are three-dimensional. Devices that could be manufactured through simplified manufacturing processes, but function in a three-dimensional space, would be highly desirable — especially if they require little assembly. Compliant ortho-planar metamorphic mechanisms (COPMMS) can be fabricated through simplified manufacturing processes, and then metamorphically transformed into a new configuration where they are no longer bound by the limitations of ortho-planar behavior. The main contributions of this paper are the suggestion of COPMM definitions, an investigation into the morphing process, and the description of a COPMM design process. This work also contributes a case study in designing COPMMs to meet particular design objectives.
Flue-Gas Versus Fuel-Injection Recirculation: Effects on Structure and Pollutant Emissions
Authors: Qubbaj Ala R.
Published: April 2008

In this study, a co-flow methane/air diffusion flame at Reynolds number of 6000 was numerically simulated. The co-flow air and fuel streams were diluted with Nitrogen in the range of 0% to 20%. The thermal and composition fields in the far-burner reaction zone (close to the exhaust) were computed, and the effects of diluent’s addition to the air stream (simulating FGR) and to the fuel stream (simulating FIR) were investigated. The results show that air-side dilution is very effective up to 5% diluent’s addition. For which, 95% and 65% drops in NO and CO emissions, respectively, along with a 16% increase in temperature, are predicted compared to the baseline case (0% dilution). However, beyond 5% dilution, no effect (reaction) has been predicted. On the other hand, the fuel-side dilution has shown an effect for all simulated diluent’s addition (i.e. 0%–20%). However, that effect is not systematic neither on temperature, CO or NO concentrations. For a similar 5% dilution to the fuel-side, a 14% increase in NO and a 97% decrease in CO are predicted, along with a 5.6% increase in temperature. The simulated results revealed that air-side dilution (simulating FGR) has a dramatic greater effectiveness in NO reduction, whereas, fuel-side dilution (simulating FIR) has a greater effectiveness in CO reduction. Besides, the results suggest an important role for Prompt-NO Fenimore mechanism.
Evaluation of Friction Stir Welds
Authors: Adapa S. , Chu T. P. , Schneider J. A.
Published: April 2008

An Image correlation technique to evaluate the structural properties and behavior of the Friction Stir Welds (FSW) is presented. The technique used is Sub-Pixel Digital Image Correlation (SPDIC). Four weld samples made of Al-2219 and Al-2195 alloys but different surface treatments are tested under tensile loads and the digital images of these samples are correlated using SPDIC. Stress-strain graphs and strain contours are obtained from the results. From the stress-strain graphs the structural properties and the behavior of the weld material are determined. The results indicate that SPDIC is a steadfast tool to determine the structural behavior and material properties of the weld samples.
Flow Structure and Heat Transfer During Free Liquid Jet Impingement Over a Rotating Disk
Authors: Lallave Jorge , Rahman Muhammad M.
Published: April 2008

The aim of this computational study was to characterize the flow structure and convective heat transfer for a free liquid jet impinging on a rotating and uniformly heated solid wafer of finite thickness and radius. The main focus considered was the effect of cooling by adding a secondary rotational flow with jet impingement. The model covers the entire fluid region (impinging jet and flow spreading out over the rotating surface) and the solid disk as a conjugate problem. Calculations were done for various standard microelectronics materials, namely aluminum, copper, silver, Constantan, and silicon; at Reynolds number ranging from 445 to 1800, under a broad rotational rate range from 125 to 6000 rpm, and range of wafer thickness from 0.2 to 2 mm, respectively. The working fluids used for this simulation included water (H2O), ammonia (NH3), flouroinert (FC-77), and (MIL-7808) oil. In the present work only laminar liquid flow was considered for Ekman number range from 5.52 × 10−6 to 2.65 × 10−4. The nozzle to disk radius ratio (rd/dn) of 6.333 was kept constant for this study. Plate materials with higher thermal conductivity maintained a more uniform temperature distribution at the solid-fluid interface. Higher Reynolds numbers increased the Nusselt number and local heat transfer coefficient distributions reducing the wall to fluid temperature difference over the entire interface. In general, the rotational rate increases the local Nusselt number values over the entire solid-fluid interface. However, at high rate of rotation, the local Nusselt number decreases because the fluid tends to separate from the rotating disk surface. It was also found that wafer thickness beyond 1 mm did not change significantly the average solid-fluid dimensionless interface temperature and Nusselt number distributions.
ARCTIC: A Rotary Compressor Thermally Insulated µCooler
Authors: Heppner Joshua D. , Walther David C. , Pisano Albert P.
Published: April 2008

Microscale cooling to date relies largely on passive on-chip cooling in order to move heat from hot spots to alternate sites. Such passive cooling devices include capillary pump loops (CPL), heat pipes, and thermosiphons. Recent developments for active cooling systems include thermal electric coolers (TECs) for heat removal. This paper focuses on the design of an active microscale closed loop cooling system that uses a Rankine vapor compression cycle cooling system. In this design, a rotary compressor will generate the high pressure required for efficient cooling and will circulate the working fluid to move heat away from chip level hot spots to the ambient. The rotary compressor will leverage technology gained from the Rotary Engine Power System (REPS) program at the UC Berkeley, most specifically the 367 mm3 displacement platform. The advantage of a Wankel (Maillard) compressor is that it provides six compression strokes per revolution rather than a single compression stroke common to other popular compressors such as the rolling piston. The current Wankel compressor design will achieve a theoretical compression ratio of 8:1. The ARCTIC (A Rotary Compressor Thermally Insulated μCooler) system will be a microscale hybrid system consisting of some microfabricated (or MEMS) components including microchannels, in plane MEMS valves, and potentially MEMS temperature, pressure and flow sensors integrated with mesoscale, traditionally machined steel components, including the compressor itself. The system is designed to remove between 25-35 W of heat at 1000 rpm using R-134a but the system is easily scaleable through a speed increase or decrease of the compressor. Further, the current compressor design has a theoretical coefficient of performance (C.O.P.) of approximately 2, a significant improvement over comparable TECs with C.O.P.s of approximately .05-.1. Finally, a thermal circuit analysis determines that the time constant to achieve refrigeration temperature in 12 seconds is possible.
Stable Gain Scheduling Through Bumpless Transfer
Authors: Hencey Brandon , Alleyne Andrew
Published: April 2008

In this paper, a method of interpolating a priori designed controllers for gain scheduling using notions developed in anti-windup and bumpless transfer is discussed. In contrast with many approaches that guarantee stability by design of of the controllers as a set, it is often desirable to design and tune each controller individually and gain schedule the resulting controllers. Using the bumpless transfer techniques discussed, this paper puts forth a method of scheduling the controllers in a stable manner for sufficiently slow scheduling variables.
Residual Autocorrelation in Probabilistic Model-Based Diagnostics
Authors: Schwall Matthew L. , Gerdes J. Christian
Published: April 2008

The performance of model-based diagnostic techniques depends not only on the quality of the residuals generated using the models, but also on the method used to interpret the residuals. Robust residuals can often be interpreted deterministically, but noisy residuals can benefit from being interpreted probabilistically. A probabilistic framework enables the modeling of uncertainty and the relationship between multiple faults and multiple residuals. However, it is not well-suited for representing residual dynamics, and as a result, residuals must be assumed to not be autocorrelated. Since this condition is rarely met, this paper analyzes it to determine how residuals can be made to be fit the assumption, and the consequences when the assumption is violated. The paper demonstrates that fault probabilities determined using autocorrelated residuals are useful, but lack calibration. Two methods for removing autocorrelation are discussed and both are shown to result in probability estimates that trade refinement for calibration.
Monolithic 3-D Microfabrication of Mechanisms With Multiple Independently-Moving Parts
Authors: Cohen Adam L. , Wooden Susan M.
Published: April 2008

Microfabrication technology has matured to the point that sophisticated, highly-miniaturized mechanisms can now routinely be manufactured in a batch process in metal. These mechanisms may include a variety of distinct, individually-moving parts. Through the use of monolithic 3-D fabrication, the need for microscale assembly, normally a major cost barrier to volume production may be eliminated. We present the production of complex mechanisms produced using EFAB technology, a batch production process providing multiple layers of electrodeposited and planarized metals. Complex, integrated systems including hinges, flexures, bearings, gears, and drive chains have been produced. EFAB technology allows intricate mechanisms with features as small as 2 μm and overall sizes in the range of 10s of microns to millimeters to be designed using standard 3-D mechanical CAD tools. Air-driven turbines with roller bearings, self-assembled gear trains with three stages of 2:1 reduction gearing, and a concept demonstration of a modular, multi-functional instrument for minimally-invasive surgery are discussed. The latter device, measuring approximately 1 × 0.5 mm in cross section, uses microscale chains and pulleys to independently extend and retract both a hook-shaped instrument and microscale forceps. The design allows for stacking of additional tool modules as required. Highly-miniaturized instruments such as these can be attached at the end of a catheter and actuated remotely by the surgeon by applying pure tension through cables.
Conjugate Heat Transfer Analysis of Circular Microtube Under Time Varying Heat Source
Authors: Gari Abdullatif A. , Rahman Muhammad M.
Published: April 2008

When a magnetic field is applied to a magnetic material it releases energy. It has been proven experimentally that this temperature rise could be as high as 20 K when a magnetic field of 10 T is applied. Heat is generated when the magnetic field is applied and cooling is produced when the magnetic field is released. The purpose of this study is to explore transient heat transfer coefficient when a fluid is circulated in the substrate through microchannels. Equations for the conservation of mass, momentum, and energy were solved in the fluid region. In the solid region, the transient heat conduction equation was solved. Gadolinium and water were picked as the magnetic material and working fluid respectively. The results are represented by plotting the variations of heat transfer coefficient and Nusselt number with time at various sections of the tube. The effects of the magnetic field strength, diameter of the microtube in the substrate, and Reynolds number were studied. It was found that the heat transfer coefficient changes with time in a periodic fashion when heating and cooling are generated in the system by repeated introduction and relaxation of the magnetic field. The results of this study will be useful for the development of microtube heat exchangers for a compact magnetic refrigerator.
Biporous Sintered Copper for Closed Loop Heat Pipe Evaporator
Authors: Semenic Tadej , Lin Ying-Yu , Catton Ivan
Published: April 2008

Parameters that determine a critical heat flux (CHF) inside a biporous evaporator (wick) for a closed loop heat pipe have been studied. In a present work, a biporous wick structure was sintered from copper powder 53–63μm diameter into clusters 500–710μm diameter; the clusters were then sintered into 20mm long and 3mm wide wicks with different wick thickness on copper bases with three different lengths (5mm, 7.5mm and 10mm). Total of six wicks were made and tested. Copper base(mm) to wick thickness(mm) ratios of the wicks tested are: 5/5, 7.5/5, 10/5, 5/3, 7.5/3 and 10/1.5. Narrow (3mm) wicks with different copper base lengths allowed sidewise observation of the boiling inside the wick at different heat loads. Best-performed 10/1.5 wick, second best was 5/3 and then following 7.5/3, 5/5, 7.5/5, 10/5. Tests were run at atmospheric pressure and absolute ethanol as working fluid.
Nanoscratching of Nylon-Based Ternary Nanocomposites
Authors: Dasari A. , Yu Z.-Z. , Mai Y.-W.
Published: April 2008

Recent developments in miniaturization of polymeric components for microelectromechanical systems (MEMS) and nanotechnology applications require that the load applied be very small in the range of μN and nN and the contact radius in nanometers to achieve certain purposes like nanofabrication, nanomachining or nanopatterning. So, it is necessary to understand the basic nanotribological mechanisms to describe the stress fields associated with the asperities, crack initiation and growth, material removal, etc. This study reveals the nano-scale nature of intimate contacts by using atomic force microscopy during nano-scratching of nylon 66/SEBS-g-MA/organoclay ternary nano-composites produced by different blending sequences and having contrasting microstructures using a standard diamond Berkovich indenter at a low load of 1 mN and a low sliding velocity of 1 μm/s. It is shown that the constraint effect of exfoliated organoclay on the nylon matrix material is much more important than on the dispersed soft domains in resisting the nanoscratch, as indicated by the lower scratch penetration depth. However, the absence of clay in the soft SEBS-g-MA phase promotes cavitation under these nanoscratch conditions. Conversely, the presence of organoclay in SEBS-g-MA restrains the cavitation of the latter, and its absence in the nylon matrix material is deleterious as indicated by the higher scratch penetration depth. The results presented also suggest that the ternary nanocomposites are preferred to the binary nano-composites, particularly the exfoliated nylon 66/organoclay nanocomposite. This research extends our basic knowledge and provides new insights of the nature of nano-scale processes that happen during nanoscratching of polymer nanocomposites. The outcome of the work also raises critical questions like, penetration depth versus morphology left behind the tip, which needs an in-depth understanding of a broad range of materials.
Design of Nanostructured Phononic Materials
Authors: Rupp Cory , Frenzel M. , Evgrafov A. , Maute K. , Dunn Martin L.
Published: April 2008

The ability of a material containing a periodic arrangement of second-phase inclusions to prevent transmission of waves in certain frequency ranges is well known. This is true for all types of waves including acoustic, electromagnetic, and elastic. These forbidden regions are called band gaps. They arise as incident waves are effectively attenuated by interference among the scattered wave fields. Indeed much of current semiconductor technology revolves around band-gap engineering with regard to electron flow in the periodic potentials resulting from atoms in their lattice positions. The phenomena are also being heavily explored in the context of light via the development of photonic crystals. Things become more interesting if instead of thinking of periodic arrangements, one selectively removes some of the inclusions in the periodic geometry creating defects. If done right, this can result in a material microstructure that can guide waves through the material. Advances in nano and micromanufacturing technologies in the last couple of years have opened up the possibility to fabricate heterogeneous material systems with precise positional control of the constituent materials. For example, it is now possible to place thin-film materials precisely at a resolution of fractions of a micron. Depending on how it is done, one can envision designing a material so that a wave will be guided to a particular location and/or away from another and as a result damping or amplifying the wave locally. In this work we develop a topology optimization approach to design such nanostructured materials. We demonstrate the approach through the design of three multifunctional phononic composite materials composed of silicon and aluminum: i) a grating designed to stop wave propagation at a specified frequency, ii) a waveguide that bends the propagation path of an elastic wave, and iii) an elastic switch that switches an input signal between two output ports based on the state of the input signal.
Advanced Suspension Systems for Wheeled Military Vehicles
Authors: Vahdati Nader , Fah Yap Fook , Khiang Koh Yong , Hwee Kiew Woon
Published: April 2008

To allow wheeled military vehicles to travel at higher speeds on off highway roads, the primary suspension system needs to be semi-active or fully active. To develop a semi-active or a fully active suspension system for wheeled military vehicles, instead of the actual vehicle, a simpler and a better controlled system, meaning a quarter car test rig was used. The quarter car test rig consists of a tire, a spring, a Magneto-Rheological fluid (MR-fluid) damper, a double wishbone suspension system, and a mass representing a quarter car chassis. This paper documents the quarter car test rig design, its mathematical model, its MATLAB simulation results, and experimental test results collected on the actual test rig with the damper in the OFF state versus the semi-active state. The Ground-hook semi-active control policy was used to control the MR-fluid damper. This control policy significantly reduces the motion of the tire at its natural frequency.
Precise Prediction on Pull-In Instability of a Deformable Micro-Plate Actuated by Distributed Electrostatic Force and Approximate Closed-Form Solutions
Authors: Chao Paul C.-P. , Chiu Chi-Wei
Published: April 2008

This study is dedicated to perform nonlinear asymptotic analysis based on the continuous thin plate model of MEMS capacitive sensor/actuator in order to predict the pull-in voltages/positions more precisely than past works. In these past studies, only discrete models without residual stress were considered. A sensor/actuator is considered in structure of two parallel electrostatically-charged flexible square plates — one thin plate in persistent vibrations to reflect external pressure and another thick plate in relative still as the backplate. The dynamic model in the form of the partial differential equation for the parallel plates is first established based on the balance among plate flexibility, residual stress and electrostatic forces. Assuming harmonic deflection for the vibrating plate clamped on boundaries, Galerkin method is used to decompose the established system p.d.e. into discrete modal equations. Solving the discrete modal equations, plate deflection can be obtained. The pull-in position is next solved from the condition that as the pull-in occurs the electrostatic attraction force on the deflected plate exceeds the elastic restoring force by the deflected plate. It is found from analysis results for some case study that the pull-in position is 1.66 μm with air gap of 3.75 μm. This predicted pull-in position is smaller than the predict position from past works, two-thirds of the gap. In addition to theoretical analysis, experiments are also conducted to verify the correctness of the established model.
Effective Compliance of an Elastic Inhomogeneity With Non-Uniform Strain
Authors: Gorbatikh Larissa
Published: April 2008

A method is proposed to estimate contribution of an elastic inhomogeneity into the overall strain of the material for the case when strain inside the inhomogeneity is not uniform. Uniform strain is a common situation when the inhomogeneity has an ellipsoidal shape and placed into the uniform stress field. However, the assumption of uniformity is inadequate in many applications when geometrical irregularities of the inhomogeneity, surface effects as well as interactions with other inhomogeneities cause local strain variations in the medium. The proposed method may have far reaching implications when impact of local strain variations on the material overall elastic response is of interest. For example, it may bring insight on how to account for strong interactions between inhomogeneities when predicting material properties and how to mobilize these interactions to achieve better properties. It is well known that interactions may produce stiffening and toughening effects depending on the material microstructure. The compliance contribution tensor is found to be dependent on the boundary displacements of the inhomogeneity and material properties. To illustrate the method we calculated elastic compliances of (1) a circular inclusion with perfectly bonded interface (test problem), (2) a circular inclusion with partially debonded interface, and (3) two strongly interacting cracks in parallel setting.
Surface Roughness Modeling Based on Surface Roughness Feature Concept for High Speed Machining
Authors: Rami´rez M. de J. , Correa M. , Rodri´guez C. , Alique J. R.
Published: April 2008

This paper explains the concepts to develop a Model of Surface Roughness in order to help researchers to model predictors for high speed machining, also a concept of a surface roughness feature (RaF) is introduced. A RaF is an information piece that shows the factors used by a Ra prediction technique associate with a specific geometric feature. The surface roughness information model is a repository of the RaFs designed to focus on particular workpiece geometries. The Ra predictor developer can design the content of the Ra information model according with his Ra prediction technique to be developed. Each RaF matches with a prediction technique to form RaF predictors and they are united to form a general Ra predictor for the entire workpiece profile.
Experimental Study on Frictional Performances of a Micro Capsule-Like Equipment Sliding in Off-Body Chitterling
Authors: Jie Li , Ping Huang
Published: April 2008

In this paper, experiments on frictional performances of micro capsule-like samples are carried out with sliding in one piece of off-body chitterlings, and the factors which influence on movement of the samples have been studied as well. The micro capsule-like samples are different in size, weight and material. Each sample is put into the same piece of cleaned-out chitterlings and then is driven by a piece of string attached on one end of the sample. The electrical signals are measured to detect the tensile force needed to driven the sample. By analyzing and comparing the data acquired, the influence of the parameters of the sample is discussed. The results of the experiments indicate that material, diameter and weight are of significant influence on the frictional force while length not.
Integration of Information Technology for Manufacturing Education
Authors: De Ciurana Joaquim , Garcia-Romeu Maria Luisa , Rodriguez Ciro A. , Vazquez Victor
Published: April 2008

This paper shows how information technology (IT) is integrated into the manufacturing education curriculum at the Instituto Tecnolo´gico y de Estudios Superiores de Monterrey in Mexico and the Universitat de Girona in Spain, with similar approaches that include: a) web-based manufacturing education tools, and b) advanced CAD/CAM/CAE, with emphasis on manufacturing process CAE. The paper describes the general structure of the mentioned approaches and their application through the following case studies in Spain: a) web-based machining advisor (including general process information and machining parameter specification) and Mexico: b) application of manufacturing process CAE for tooling development.
Advances of the Finite Element Modeling Markup Language
Authors: Michopoulos J. G. , Martin R. , Anto B.
Published: April 2008

Development of the finite element modeling Markup Language (femML) was motivated by the need to address data exchange issues associated with intra- and inter-application interoperability in the context of finite element modeling and analysis. This paper describes femML advances during the past four years and describes current status of various tools and technologies associated with femML. In particular, the current schema is described along with XSLT-based translation of femML to SVG and X3D for quick model visualization. Java, C++ and Visual Basic tools have been developed for model editing and visualization as well. The paper concludes with identification of standing issues to be resolved relative to femML’s evolution and the future directions and plans about further evolution of femML.
Manufacturing Execution Systems Interoperability and Web Services Technologies
Authors: Jimenez Guillermo , Molina Arturo , Canche Luis
Published: April 2008

Manufacturing Execution Systems (MES) rely between the shop floor and many systems that support the operation of a manufacturing enterprise such as Production and Inventory and Enterprise Resource Planning Tools. Interoperability with a multitude of platforms is thus one of the main problems to solve for implementation of a MES. This paper describes a software architecture based on the use of Web services technologies and discusses how interoperability issues are resolved in a much more seamless manner than with other previous middleware technologies.
Scope and Benefits of a New Comprehensive Diagnostic Approach for Pneumatic Systems and Components
Authors: Binder J. , Gerlach H. , Boehm C.
Published: April 2008

The use of diagnostics as a maintenance technology for motion systems can play a key role for the life cycle costs of a production facility. A new comprehensive diagnostic approach provides methods for pneumatic systems that continuously monitor and analyze sensor readings in the main supply line and within subsystems. Using different evaluation methods of pattern recognition, the source of deviations can be isolated to individual components. Unlike traditional component-based diagnostic solutions, this new approach is applicable to complete pneumatic systems and/or single pneumatic components for sensing and monitoring performance levels, information acquisition for optimized maintenance preventing unscheduled downtime and extending machine or process serviceability. In a comprehensive cost calculation, the cost savings over the life cycle of a production facility of an end user are revealed.
Waterjet Peening At 600MPa: A First Investigation
Authors: Hashsish M. , Chillman A. , Ramulu M.
Published: April 2008

An experimental study was conducted to explore the high-pressure waterjet (WJ) peening at 600MPa on the surface integrity and texture of metals. The concept of larger droplet size and multiple droplet impacts resulting from an ultra high-pressure waterjet (UHPWJ) was used to explore and develop the peening process. A combination of microstructure analysis, microhardness measurements, and profilometry were used in determining the depth of plastic deformation and surface texture that result from the surface treatment process. It was found that waterjet peening at 600MPa induces plastic deformation to greater depths in the sub-surface layer of metals than laser shock peening. The degree of plastic deformation and the state of material surface were found to be strongly dependent on the peening conditions and desired surface roughness. Based on these first investigation results, water peening at 600MPa may serve as a new method for introducing compressive residual stresses in engineering components.