bluuebunny/crossref_metadata_2025 huggingface dataset:
Microscopic Observation of Energy Propagation in Polymeric Fluids Crossing a Barrier
Authors: Aouf Rashad , Ilic Vojislav
Published: August 2009

A major challenge facing tumour treatment procedures, including hyperthermia, is the inadequate modelling of the bio-heat transfer process. Therefore, an accurate mathematical bio-heat transfer model has to precisely quantify the temperature distribution within a complex geometry of a tumour tissue, in order to help optimize unwanted side effects for patients and minimize (avoid) collateral tissue damage. This study examines the three-dimensional molecular dynamics (MDs) simulation of a Lennard-Jones fluid in the hope of contributing to the understanding of the propagation of a thermal wave in fluids causing phase change i.e. irreversible gelation. It is intended to establish, from such information, a useful benchmark for application to large scale phenomena involving macro scale heat transfer. Specifically, this study examines assemblies of N particles (N = 500 atoms) and analyses the microscopic simulation of double well interaction with permanent molecular bond formation at various temperatures within the range 1–2.5Kb/εT. The dynamics of the fluid is also being studied under the influence of a temperature gradient, dt/dx, where neighbouring particles (i.e. atoms/molecules) are randomly linked by permanent bonds to form clusters of different sizes. The atomic/molecular model consist of an isothermal source and sink whose particles are linked by springs to lattice sites to avoid melting, and a bulk of 500 atoms/molecules in the middle representing the Lennard-Jones fluid. Then, this study simulates the energy propagation following the temperature gradient between the heat source and heat sink at T1 = 2.5 and T2 = 1.5 respectively. The potential equation involved in this study is given by the Finitely Extensible Non Elastic (FENE) and Lennard-Jones (LJ) interaction potential. It is observed that the atoms of the bulk start to form a large cluster (∼ 300 atoms) with long time of simulation estimated by 106 time steps where τ = SQRT(ε/mσ2) and Δt = 10−3. It is also obtained that the potential energy of 13.65KbT across a barrier to establish permanent bonds giving rise to irreversible gel formation. All the parameters used in this study are expressed in Lennard-Jones units.
3-D FEM Stress Analysis and Strength of Adhesive-Rivets Combination Joints Under Static and Impact In-Plane Bending Moments
Authors: Nogaito Ryo , Sawa Toshiyuki , Karami Atsushi
Published: August 2009

Stress distributions in adhesive-rivets combination joints subjected static bending moments are calculated using three-dimensional finite-element calculations. The stress propagation and stress distribution subjected to impact bending moments are also calculated using three-dimensional FEM calculations. In the FEM calculations, the effects of number, position and diameter of rivets, and Young’s modulus of the rivet on the stress distributions at the adhesive interface are examined from fail-safe design standpoints. From the FEM results, the maximum value of peel stress decreases as the position of rivets in the axial direction is decreased and the position of rivets in the width direction increases in the joints with two and four rivets. It is also found that the results on the stress distributions in the joints under the static bending moments show the same tendency of the joints under the impact in-plane bending moments. Concerning the effect of Young’s modulus of the rivet, it is not seen on the peel stress under the static in-plane bending moments. For the verification of the FEM calculations, the experiments were carried out to measure the strain response under both static and impact load conditions. Fairly good agreements are observed between the FEM calculations and the measured results.
Tool Wear Estimation in Drilling Using Acoustic Emission Signal by Multiple Regression and GMDH
Authors: Sudev L. J. , Ravindra H. V.
Published: August 2009

The cutting tool is the only element in a machine tool that requires frequent changes due to failure. Drill bit wear can cause catastrophic failure that can result in considerable damage to the work piece and the machine tool. Hence, there is an imperative need to keep a watch on the condition of the cutting tools during the machining process. Over the years, a wide variety of on-line or off-line techniques have been investigated for monitoring abnormal cutting tools. A variety of signals such as tool-tip temperature, forces, power, thrust, torque, vibrations, shock pulse, Acoustic Emission (AE) etc., have been used for monitoring tool failure by on-line technique. The detection and monitoring of AE is commonly used to predict tool failure. Present work involves estimation tool flank wear in drilling based on AE parameters viz., RMS, energy, signal strength, count and frequency by empirical methods of analysis like Multiple Regression Analysis and Group Method of Data Handling (GMDH). The experimental work consisted of drilling S.G Cast iron using high-speed steel drill bit and measuring AE parameters from the workpiece using AE measuring system for different cutting conditions. Machining was stopped at regular intervals of time and tool flank wear was measured by Toolmakers microscope. The experimental data were subjected to simpler methods of analysis to obtain a clear insight of the signals involved. The study of AE-time plots showed a similarity with three phases of tool wear, which implies that the measured AE parameters can be related to tool wear. Multiple Regression Analysis and Drilling is a major material removal process in manufacturing. Infact, the drills have been used widely in industry since the industrial revolution. It was estimated that 40% of all the metal removal operations in the aerospace industry is by drilling. Similar to the other cutting tools, after a certain limit, drill wear can cause catastrophic failure that can result in considerable damage to the work piece even to the machine tool [1]. GMDH methods were successful in estimating flank wear based on measured AE parameters. By Multiple Regression Analysis better estimation was obtained at lower cutting conditions. Three criterion functions of GMDH viz., Regularity, Unbiased and Combined were used for estimation with 50%, 62.5% and 75% of data in the training set. Estimation was done upto Level-4. The results of GMDH estimation showed that regularity criterion functions correlates well for the set of input variables compared with unbiased and combined criteria and least error of estimation was found when 75% of data was used in the training set. The optimum level of estimation increased with the increase in the percentage of data in the training set. Comparison of the performance of Multiple Regression Analysis and GMDH indicated that estimation by regularity criterion of GMDH had an edge over Multiple Regression Analysis.
Wind Driven Rain (WDR) Forces on Equipment and Structures
Authors: Norman Charles R.
Published: August 2009

Engineers design ASME vessels, towers, stacks, tanks, equipment and other structures for wind loads using ASCE 07 “Minimum Design Loads for Buildings and Other Structures”. During heavy rains, additional forces are added to these calculations and this paper presents a computational method to address them. The resultant wind driven rain (WDR) forces in pounds per square foot (psf) can be greater than dry air forces. The method includes wind velocity, rainfall intensity, catch ration, and effects of the structures. During hurricanes, consideration of these WDR forces is especially important for preventing damages and failures. Examples of vessels, tall towers and stacks are presented.
A GPU-Based Implementation of a Cone Convex Complementarity Approach for Simulating Rigid Body Dynamics With Frictional Contact
Authors: Tasora Alessandro , Negrut Dan , Anitescu Mihai
Published: August 2009

In the context of simulating the frictional contact dynamics of large systems of rigid bodies, this paper reviews a novel method for solving large cone complementarity problems by means of a fixed-point iteration algorithm. The method is an extension of the Gauss-Seidel and Gauss-Jacobi methods with over-relaxation for symmetric convex linear complementarity problems. Convergent under fairly standard assumptions, the method is implemented in a parallel framework by using a single instruction multiple data computation paradigm promoted by the Compute Unified Device Architecture library for graphical processing unit programming. The framework supports the analysis of problems with a large number of rigid bodies in contact. Simulation thus becomes a viable tool for investigating the dynamics of complex systems such as ground vehicles running on sand, powder composites, and granular material flow.
A Microfluidic Device for Wear Detection in Lubricants
Authors: Murali Srinidhi V. , Xia Xinggao , Jagtiani Ashish V. , Carletta Joan , Zhe Jiang
Published: August 2009

We present the design, fabrication and testing of a microfluidic device for metal wear detection in lubrication oils. The detection is based upon the capacitance Coulter counting principle, that is, on the change in a microchannel’s capacitance caused by the presence of a metal particle in the microchannel. Preliminary testing on the microfluidic device using 20 μm aluminum particles has demonstrated the feasibility of using this microfluidic device for detection and counting of micro metal particles in non conductive lubricant oil. This microfluidic device is promising for online oil debris detection by the use of multiple detection microfluidic channels.
Shape Optimization of Power Plant Ducting Using CFD
Authors: Avvari Ramesh , Jayanti Sreenivas , Gowrisankar S.
Published: August 2009

Power plant ducting generally designed with simple shapes has to undergo many changes of shape to accommodate interfacing equipment associated with plant operation leading to higher pressure drop, higher power consumption and flow maldistribution zones having higher or lower velocities. To redress this situation, baffles, guide vanes and other internals are used to streamline the flow through ducts, especially in bends. A basic disadvantage in coal fired plants of using baffles is that they get punctured / eroded due to impact of high velocity ash particles in flue gas ducting, and the effectiveness of baffles is lost in short duration. To overcome the above disadvantages, a new method is developed to change the shape of the duct in such a way that a more streamlined flow is maintained across any cross section. The velocity profile, obtained using computational fluid dynamics (CFD) calculations, across the cross-section is examined at several locations along the duct. Wherever high velocity compared to average velocity is found, the cross-section is increased and where the velocity is low, the cross-section is reduced. A new grid is created through the revised cross-section and a fresh CFD analysis is made to identify zones of flow maldistribution. The flow simulation is done in an iterative manner, alternately calculating the flow domain and modifying the local cross-section based on the local velocity distribution. The method has been found to be more robust and led, after a few iterations, to a shape of the duct which resulted in a significant reduction in the pressure drop without using any baffles or inserts.
Square Foot Manufacturing: Event-Driven Manufacturing by Means of Multifunctional Work Spaces
Authors: Redlich Tobias , Wulfsberg Jens P. , Lehmann Jo¨rg , Bruhns Franz-Ludwig
Published: August 2009

This paper presents Square Foot Manufacturing (SFM) as new approach to realize changeability in the manufacturing process. SFM encompasses a down scaled manufacturing plant for machining small parts; it has reconfigurable structure and holds micro machining units (MMU) that are reduced in function and flexible in adjustment. Because they are sufficiently small it is easy to move these machine tools between individual operation steps and it is feasible to use more than one of them simultaneously machining one work piece.
Modeling of Kinetic to Electrical Energy Conversion via Capacitive MEMS With Switchable Dielectric
Authors: Kempitiya Asantha , Hella Mona M. , Borca-Tasciuc Diana A.
Published: August 2009

Wireless distributed micro-sensor systems have numerous applications, from equipment diagnostic and control to real time biomedical monitoring. A major obstacle in developing autonomous micro-sensor networks is the need for local, autonomous electric power supply, since using a battery is often not a viable solution. This work investigates a novel micro-power generator converting ambient vibrations to electrical energy via electrostatic transduction employing a comb-like variable capacitor, with a switchable dielectric constant. The micro-generator is designed to operate in an inplane, gap closing, and charge constrained configuration. Enhanced power levels are obtained by pulling a high dielectric constant liquid between the capacitor gaps via electrochemical force effect at maximum capacitance position. The effects of squeeze film damping and variable electrostatic force induced by the varying spatial distribution of dielectric medium are taken into account. In this configuration the microgenerator exhibits high quality factors, thus providing an output power higher of approximately 168 μW.
Effects of Mechanical Vibration on Matrix Production and Proliferation of Three-Dimensional Cultured Chondrocytes
Authors: Takagi Yuta , Shiraishi Toshihiko , Morishita Shin , Takeuchi Ryohei , Saito Tomoyuki , Mikuni-Takagaki Yuko
Published: August 2009

This paper describes the effects of vibration stimulation on chondrocytes in three-dimensional culture in relation to the production of regenerative cartilage tissue, using collagen artificial skin as a carrier and supplementation with hyaluronic acid (used in the conservative treatment of osteoarthritis), and the mechanism of the adaptive response of chondrocytes to mechanical loading. The experimental condition imitates an environment of articular cartilage in vivo that chondrocytes are completely surrounded by the extracellular matrix and receives mechanical stimulation for the weight-bearing mechanics. Chondrocytes were isolated from articular cartilage of porcine metatarsophalangeal joints. Experiments were performed under four different culture conditions: control condition, in which chondrocytes were cultured with atelocollagen gel and collagen artificial skins, and no vibration (HA−Vib−); HA−Vib+, in which chondrocytes were cultured in atelocollagen gel and collagen artificial skins with vibration treatment for 2 weeks; HA+Vib−, in which chondrocytes were cultured in medium containing 0.1% hyaluronic acid; and HA+Vib+, in which chondrocytes were cultured in medium containing 0.1% hyaluronic acid with vibration treatment for 2 weeks. Histologic analysis was conducted at 14 days of culture. The proliferation of chondrocytes was obtained by counting the number of cells with a hemocytometer after 3, 7, 10, and 14 days of culture. The expression of Sox 9 and β-catenin was detected by western blotting analysis. Sox 9 has been reported of involvement in transcription of type IX collagen that binds cartilage-specific type II collagen fibrils. β-catenin plays an important role of signaling pathways of cell proliferation although the relationship between β-catenin and mechanical vibration stimulation has not been clarified yet. The obtained results are as follows. The mechanical vibration enhanced the thickness of extracellular matrix of chondrocytes in histologic section at 14 days of culture and increased the expression of Sox 9. In addition, the mechanical vibration significantly increased the number of chondrocytes after 10 days of culture and promoted the expression of β-catenin. These results show that mechanical vibration promotes the matrix production and proliferation of chondrocytes and that a part of important signaling pathways in relation to mechanical vibration stimulation and proliferation of chondrocytes has been revealed.
Nonlinear Vibration of Micromachined Resonators With Attached Excitation/Detection Electrostatic Comb-Drives
Authors: Hassanpour Pezhman A. , Esmailzadeh Ebrahim , Cleghorn William L. , Mills James K.
Published: August 2009

Micromachined beams are widely used as resonant structures. The electrostatic interdigitated comb-drives are commonly utilized for exciting/detecting the vibration of these resonators. Recent investigations into the analytical model of the resonator have shown that the added mass due to the comb-drive not only alters the natural frequencies of the resonator, but also changes the mode shapes of vibration. In this paper, the analytical model is extended to include the nonlinear effects due to the stretching of the beam. The generalized orthogonality condition along with the method of assumed-modes summation and the method of multiple scales has been used to study the primary and internal resonance of micro-beam resonators.
Piezoelectric PZT Semi-Ordered Nanotubes Arrays by Wetting of Porous Alumina Template
Authors: Butcher Brian J. , O’Neal Chad B.
Published: August 2009

Piezoelectric nanotubes are applicable to many areas including sensors, actuators, and energy storage. Before these applications can be realized using nanoscale components, a study is needed to characterize the piezoelectric-properties of nanotube geometries versus the piezoelectric-properties of a thin-film of the same material (not shown here). The material used in this study is (PZT) lead-zirconate-titanate, PbZr0.5Ti0.48O3. In this work, 200nm diameter PZT structures are manufactured by a template wetting procedure. These ceramic nanotubes are brittle but hold up well inside the alumina template structure. Having an array of nanometer-sized piezoelectric-tubes has been hypothesized to give comparable results to that of thin-films of the same material. The research described in this paper is a preliminary step towards testing this hypothesis via characterization and later producing piezoelectric-nanoscale-sensors, which are both small and efficient.
An Evolving Network Model of Airway Smooth Muscle Crossbridge Dynamics and Length Adaptation
Authors: Ijpma G. , Al-Jumaily A. M. , Cairns S. P.
Published: August 2009

The main driving mechanism in asthmatic attacks is the contraction of airway smooth muscle (ASM). Physiological loading of ASM by normal breathing and deep inspiration has been shown to reduce ASM contractile force. Our research involves the development of a mathematical model to describe the dynamic behavior of ASM. In this model length adaptation is described by an evolving filament network of passive and active elements in parallel with a soft glassy material. Contractile forces are described by the evolving force length characteristics of some of the network links. It is envisaged that the model will bridge the gap between passive ASM dynamics and contractile dynamics. The model will be validated using experimental data from testing of ASM tissues in vitro.
Behavior and Mechanisms of Bolt Self-Loosening Under Transverse Load Due to Vibrations of a Washer Along an Arc
Authors: Fujioka Yasuo
Published: August 2009

Self-loosening mechanisms of a bolt were investigated by Finite Element Method, under the assumption of a twist at the center of a circular joined structure in which the bolt was set along a certain pitch circle. In this structure, the bolt is loosened by combining the translational and rotational external loads. In the case of a large pitch circle structures in which self-loosening occurs, the directions of friction shear forces on the threads were along concentric circles; however, the instantaneous center of rotation was located one-side near the thread surface, and the center was eccentric with the axis of the bolt. If the radius of the pitch circle is set smaller, the instantaneous center of rotation moves closer to the center of the bolt, and finally reaches to the same position at the center of the bolt. On the other hand, the directions of friction shear forces on pitch diameter of one thread were calculated theoretically using the inclination and friction on a pressure flank. The results were in good agreement with FE analysis. By considering these mechanisms, it was estimated that the number of occurrence of self-loosening in one vibration cycle changes at the border when the diameter value of the pitch circle equals that of the screw threads. If the diameter of the pitch circle becomes smaller than that of the screw threads, the number changes from two to one. With the exception of torsional center-fastened structures, since the pitch circle is very small, self-loosening of general joined structures will occur twice in one vibration cycle.
Effects of Mechanical Vibration on Proliferation and Differentiation of Neural Stem Cells
Authors: Suzuki Kei , Shiraishi Toshihiko , Morishita Shin , Kanno Hiroshi
Published: August 2009

Neural stem cells have been studied to promote neurogenesis in regenerative therapy. The control of differentiation of neural stem cells to nerve cells and the increase of the number of nerve cells are needed. For the purpose of them, it is important to investigate not only chemical factors but also mechanical factors such as hydrostatic pressure in brain and mechanical vibration in walking. In this study, sinusoidal inertia force was applied to cultured neural stem cells and the effects of mechanical vibration on the cells were investigated. After the cells were cultured in culture plates for one day and adhered on the cultured plane, vibrating group of the culture plates was set on an aluminum plate attached to an exciter and cultured under sinusoidal excitation for 24 hours a day during 26 days. The amplitude of the acceleration on the culture plate was set to 0.25 G and the frequency was set to 25 Hz. The time evolution of cell density was obtained by counting the number of cells at every 3 or 4 days. The expression of Akt, phosphorylated Akt (p-Akt), MAPK, and phosphorylated MAPK (p-MAPK) was detected by western blotting analysis at 7 days of culture to understand the mechanism of cell proliferation. Akt and MAPK are part of signaling pathways in relation to cell proliferation. The phosphorylation of Akt suppresses apoptosis and the phosphorylation of MAPK activates cell division. The gene expression of MAP-2, NFH, GFAP, and nestin was detected by real-time RT-PCR analysis at 7 days of culture to obtain a ratio of differentiation of neural stem cells to nerve or glia cells. MAP-2 and NFH are nerve cell markers, GFAP is a glia cell marker, and nestin is a stem cell marker. The results obtained are as follows. The cell density of the vibrating group was three times higher than that of the non-vibrating group at 26 days of culture. p-Akt was enhanced by the mechanical vibration while p-MAPK was not. There is no significant difference of the gene expression level of MAP-2, NFH, GFAP, and nestin between the vibrating and non-vibrating groups. These results suggest that the mechanical vibration promotes the proliferation of neural stem cells and its cause is likely the suppression of apoptosis but not the activation of cell division, and that the mechanical vibration at the experimental condition does not affect the differentiation of neural stem cells to nerve or glia cells.
On the Determination of Etching (or Growth) Rates of Single Crystals
Authors: Chang Chia-Ou , Chang Chien Wen-Tien , Chang Guo-En , Chen Po-Chih , Shieh Fa-Hwa
Published: August 2009

If we define the slowness curve by the normal vector of the material point of the crystal surface divided by the growth (or etching) rate of that point. Frank’s theorem states that, in the course of crystal’s growing or etching, each point of the boundary surface moves along its own straight line (or the characteristic line) which is parallel to the normal of the slowness curve. Since he didn’t find out the speed of the crystal surface point advancing along this characteristic, the etched crystal shape can not be determined quantitatively. In this paper we derive the equation in explicit form expressing the surface moving speed along the characteristics in terms of the microscopic parameters (in atomic size) and variables such as step density, step flux, and step height. Not all the microscopic variables are measurable, so we have to drive certain equations relating the microscopic variables to the macroscopic ones (such as the orientations of the crystal boundary lattice plane, slopes of the characteristic lines, etching rates, and so on) through the kinematics theory of particles. One measurement of the macroscopic variables at any particular instant is enough to determine not only the etching (or growth) rates of the crystal but also the etched crystal shape of any subsequent instant.
Force Transfer Behavior of Mechanically Fastened Structures in Light Weight Design
Authors: Friedrich C. , Koch D. , Dinger G.
Published: August 2009

Light weight design gets more and more important regarding mass inertia of moved component systems. By this reason new products are using more and more light materials which exhibit an increased sensitivity due to force transmission in component contact zones. This paper gives an overview about related criteria when designing fastened component systems with transverse loading. Numeric stress analysis with FEA calculates a detailed stress distribution with significant inhomogeneities. The reasons for increased sensitivity of light materials get obvious. Often bolted joints are used to realize friction-based transverse force transmission – design criteria which become important in light weight design are shown (e.g. self loosening). Forces can also be transmitted in axial direction; an example is proposed with an effective mechanical fastening system of long composite components without adhesives. Finally, conclusions for future engineering design are drawn.
Experimental Study of the Effects of Thermal Coating and Oxygenated Additives on Diesel Engine Performance and Pollutant Emissions
Authors: Ramu P. , Saravanan C. G.
Published: August 2009

In internal combustion engines, approximately one third of the total fuel input energy was converted into useful work and two-third has loss through exhaust gas and cooling system. Recently research has been focused on the reduction of diesel emitted pollutants due to strict emission regulations. In this study, the effect of ceramic coating to cylinder head, valves and piston crown on diesel engine performance and exhaust emission is examined. Ceramic layers were made by ZrO2-Al2O3 by using plasma coating method thickness to about 200 microns. The ceramic coated diesel engine was tested in a single cylinder, four stroke and water cooled DI diesel engine. Second part of the investigation was carried out with the fuel additive di iso propyl ether with thermal barrier coated diesel engine. The results indicate that there is reduction in fuel consumption, NOx emission and slightly increases the thermal efficiency of the engine. The combined effect of coating and fuel additive has significantly reduced the NOx emission.
Time Saving Simulation of Long Train Derailment
Authors: Durali Mohammad , Jalili Mohammad Mahdi
Published: August 2009

This article presents a new method in determining long train derailment. A new strategy for building train models with large number of wagons has been developed. Previous studies have shown that in a train model, some of the details in the model of the wagons neighboring the wagon under study play minor role in dynamic behavior of the spotted wagon. To reduce the size of the overall model, one would tend to eliminate some of the details of the complex neighboring model having minor effect on overall behavior and trade a small approximation in results for large saving in computation time. In this research this idea is used to develop a train model with one full detail wagon model linked in a train model with a large number of wagons having 3 degrees of freedom. The 3 degrees of freedom wagon models are considered to have yaw, lateral and longitudinal motions. The detailed wagon model has 48 degrees of freedom including nonlinear springs, dampers and friction on sliding surfaces. Nonlinear equations of motion for train were developed using Newton-Euler method. The model was then used to simulate train behavior in passing a bend or applying severe brakes at different speeds. The results show very good agreement with the results of models with full degrees of freedoms in all wagons. The computation time is tremendously decreased in the new method.
Numerical Simulation of Internal Flow and Spray of Liquid Phase LPG (Liquefied Petroleum Gas) Injection
Authors: Xu Boyan , Qi Yunliang , Cai Shaoli , Geng Deqiang
Published: August 2009

Cavitation and flashing formed inside and outside of an injector, respectively, have significant effect on liquid phase LPG (Liquefied Petroleum Gas) injection. Numerical simulations of internal flow of the liquid phase LPG inside different injector nozzles were performed using the FIRE CFD code. The results showed that the cavitation always occurred at the inlet corner of the nozzle with negative pressure and higher velocity regardless the nozzle geometries. The relationships between vapor void fraction at the exit of the nozzle and injection pressure were also investigated for different nozzle geometries. The spray of the liquid phase LPG was further simulated by using the results of the internal flow as initial conditions. During the simulation of the spray, the effect of superheat degree on evaporation was considered and a modified evaporation equation was employed. The comparison of the simulation with experimental results showed that, with the injection pressure increasing, spray tip penetration increased but SMD (Sauter mean diameter) decreased.
Multi-Objective Optimization of Piezoelectric Microactuator Using Genetic Algorithms
Authors: Esteki H. , Hasannia A.
Published: August 2009

In flex-tensional piezoactuators, due to the low displacement of piezostacks, a compliant mechanism is used to amplify displacement of piezostack. In this paper, optimization of a compliant mechanism with corner-filleted flexure hinges is carried out using real-coded genetic algorithms (GAs) to avoid trapping in local optimums. The objective functions are displacement amplification and stiffness of mechanism and design variables are cross-sectional size and material used. The constraints which are applied on mechanism are based on piezostack dimensions and manufacturing limits. Displacement amplification and stiffness are calculated using strain energy and Castigliano’s displacement theorem.
Enhancing the Learning of Surface Wave Dynamics in a Modern Mechanical Engineering Program
Authors: Goharzadeh Afshin , Molki Arman
Published: August 2009

This paper outlines a proposed low-cost experimental setup for characterization of surface waves that was designed and fabricated in conjunction with a senior design project. The proposed experimental setup will enhance the student’s learning of surface waves at water-air interface inside an open transparent channel. The experimental study is based on the flow visualization of water waves combined with measurement of water level using a conductance wave height probe. The detail of the data acquisition system and the characteristics of the wave probes are presented. Finally a teaching strategy for implementing the water wave experimental setup in a Mechanical Engineering curriculum is discussed.
Analysis of Optically Induced Fluid Flows in Electric Fields
Authors: Judokusumo Edward , Kumar Aloke , Williams Stuart , Wereley Steve
Published: August 2009

In this paper we demonstrate opto-electrothermal pumping in a very simple setup consisting primarily of parallel electrodes and explore the characteristics of such flows with different optical intensity patterns. For our parallel electrode configuration setup, ITO-coated electrodes were used to generate electric fields. The optical illumination system uses a laser beam (continuous wave, 1,064 nm). The experiments are analyzed in terms of existing analytical models for electrothermal flows. Microvortices created using the electric field and focused laser beam resembles a sink/source type flow with the laser spot as the center of the sink/source. The flow velocity is characterized as a function of the AC signal frequency and the strength of electric field. At larger frequencies (f > 1 MHz), the velocity of the vortices decreases and around f > 5 MHz, Brownian motion dominates fluid flow. The line illumination is created by holographically stretching the point illumination. The line is about 28 μm in length. Result of this experiment is determined by means of visualization only. The creation of these vortices can not only be used to create microfluidic pumps but also also show immense promise as microfluidic mixers without utilizaing any invasive components.
Local Geometric Projection-Based Noise Reduction for Vibration Signal Analysis in Rolling Bearings
Authors: Yan Ruqiang , Gao Robert X. , Lee Kang B. , Fick Steven E.
Published: August 2009

This paper presents a noise reduction technique for vibration signal analysis in rolling bearings, based on local geometric projection (LGP). LGP is a non-linear filtering technique that reconstructs one dimensional time series in a high-dimensional phase space using time-delayed coordinates, based on the Takens embedding theorem. From the neighborhood of each point in the phase space, where a neighbor is defined as a local subspace of the whole phase space, the best subspace to which the point will be orthogonally projected is identified. Since the signal subspace is formed by the most significant eigen-directions of the neighborhood, while the less significant ones define the noise subspace, the noise can be reduced by converting the points onto the subspace spanned by those significant eigen-directions back to a new, one-dimensional time series. Improvement on signal-to-noise ratio enabled by LGP is first evaluated using a chaotic system and an analytically formulated synthetic signal. Then analysis of bearing vibration signals is carried out as a case study. The LGP-based technique is shown to be effective in reducing noise and enhancing extraction of weak, defect-related features, as manifested by the multifractal spectrum from the signal.
Fabrication, Characterization and Microsensing of Whispering-Gallery Mode Micro-Coupling Systems
Authors: Ma Qiulin , Rossmann Tobias , Guo Zhixiong
Published: August 2009

An optical micro-coupling system of whispering-gallery mode usually consists of a resonator (e.g. a sphere) and a coupler (e.g. a taper). In this report, silica microspheres of 50–500 μm in diameter are fabricated by hydrogen flame fusing of an end of a single mode fiber or fiber taper. Fiber tapers are fabricated by the method of heating and pulling that meets an adiabatic condition. Taper’s waist diameter can routinely be made less than 1 μm and almost zero transmission loss in a taper is achieved which allows an effective and phase-matched coupling for a wide range sizes of microspheres. Both resonators and couplers’ surface microstructure and shapes are examined by scanning electronic microscopy. Three regimes of coupling are achieved, enabling a good flexibility to control Q value and coupling efficiency of a micro-coupling system. Whispering gallery mode shift is used to demonstrate a novel temperature micro-sensor. Its sensitivity determined from actual experimental results agrees well with the theoretical value. A concept of using the photon’s cavity ring down (CRD) in the microsphere to make a novel high-sensitivity trace gas micro-sensor is proposed. The CRD time constant when ammonia is chosen as the analyte gas is predicted using the simulated absorption lines.
Effects of Radiation and Variable Thermal Conductivity on the MHD Flow of a Viscoelastic Fluid and Heat Transfer Over a Stretching Porous Sheet
Authors: Anuradha P. , Krishnambal S.
Published: August 2009

A numerical study on the effects of radiation and variable thermal conductivity on the flow and heat transfer in the boundary layer of a viscoelastic fluid (Walters’ liquid B’ model) over a stretching porous sheet in the presence of a magnetic field is studied. The momentum differential equation is solved exactly. Two cases of sheet surface conditions are considered — (i) PST case involving prescribed surface temperature and (ii) PHF case involving prescribed heat flux at the surface. The energy equation is solved with the application of the shooting technique using the fourth order Runge-Kutta integration scheme. Numerical results are obtained for various values of non-dimensional parameters — which include among others, the Prandtl number (P), the Eckert number (E) and the Radiation number (N). The significant conclusions are: (1) the momentum boundary layer can be minimized by considering the sheet to be influenced by a continuous suction of the fluid through the porous boundary and by choosing large values for the viscoelastic parameter and the magnetic parameter (2) an ideal combination for faster cooling of the thermal boundary layer would be to consider the suction velocity of the fluid along with a large value for the Prandtl number combined with small values for Radiation and Eckert numbers.
Optimization of a Military Vehicle Space Frame Subject to High Impact Loading
Authors: Thota Jagadeep , Trabia Mohamed B. , O’Toole Brendan J.
Published: August 2009

Space frames are usually used to enhance structural strength of the vehicle while reducing its overall weight. These frames are comprised of beams connected together at joints. Recently, space frames are incorporated in military vehicles. However, space frames in this case are subjected to different types of loading than what is encountered in civilian vehicles such as, projectile and land mine attacks. In this paper, a finite element model for the upper half of the space frame of an armored vehicle is developed. The space frame is composed of hollow square cross-section bars and angle sections and is enclosed by uniform-thickness armor, except at the turret. The vehicle is subjected to high impact load that simulates an impact of a projectile. The model is parameterized to minimize the mass of the space frame and vehicle armor by varying the cross-sectional parameters of the beam members and joints, and the thickness of the armor plate, while maintaining the overall structural integrity of the space frame. This problem is solved using the Successive Heuristic Quadratic Approximation (SHQA). This algorithm combines successive quadratic approximation with an adaptive random search within varying search space. The entire optimization process is carried out within MATLAB environment. Results show significant reduction of the mass of the vehicle.
Failure of Three Cementless Modular Total Hip Arthroplasty Prostheses: A Retrieval Analysis
Authors: Paliwal Manish , Allan D. Gordon , Filip Peter
Published: August 2009

The reasons leading to the in vivo failure of three titanium alloy modular implants in cementless total hip arthroplasty were investigated. The implantation period ranged from 18 months to over three years. Two were fractured in vivo and the other was retrieved secondary to aseptic loosening after 18 months in service. Macroscopic examination showed close topographical similarities between the two fractured implants. Dark elliptical striations on the fractured site indicated the occurrence of low cycle fatigue. Light Microscopy and Scanning Electron Microscopy confirmed the presence of fretting, pitting, plastic deformation, and stress-induced corrosion cracking. In two of the three implants, EDS confirmed metal ion traces in the tissue around the implant. However, nothing unusual was found in the third unfractured implant. Taper performance is influenced by metallurgy, the load carried and the effect of the local microenvironment. Methods to reduce the impact of these factors may reduce the incidence of taper related failure.
Large Eddy Simulations of a Three-Row Leading Edge Film Cooling Geometry
Authors: Sreedharan Sai Shrinivas , Tafti Danesh K.
Published: August 2009

A three-row leading edge film cooling geometry is investigated using Large-Eddy Simulations (LES) at a freestream Reynolds number of 32,000 and blowing ratio of 0.5 with lateral injection of 45° to the surface and 90° compound injection. The stagnation jet interacts with the mainstream through the generation of ring vortices which quickly breakdown and convect along the cylinder surface. The coolant penetrates the mainstream both laterally and normal to the surface resulting in increased mixing and turbulence generation. As the coolant loses transverse and lateral momentum it is pushed back to the surface in the stagnation region after which it convects downstream along the blade surface. Surface coverage is uniform but weak with spanwise-averaged effectiveness ranging from 0.1 to 0.3 in the stagnation region. The primary off-stagnation coolant and mainstream interaction is through the generation of a counter-rotating vortex pair in the immediate wake, but which quickly degenerates to a single vortex which entrains free-stream fluid near the surface at the aft-end of the jet. In contrast to the stagnation row, the coolant stays in close proximity to the surface and does not undergo a large lateral displacement along the spanwise pitch. As a consequence it provides good local coverage along its trajectory but barely covers half the lateral pitch. Hence, spanwise-averaged effectiveness is of the same order as at stagnation starting at 0.3 downstream of injection to 0.1 about 6d downstream.
Plastic Yield Conditions for Adhesive Contacts
Authors: Wu Yu-Chiao , Adams George G.
Published: August 2009

The Hertz contact theory allows the onset of yielding to be predicted for those contacts in which the effect of adhesion can be neglected. However in microscale contacts, such as those which occur in MEMS, yielding will occur for lower loads than predicted by the Hertz theory. For such cases, the JKR, DMT, and Greenwood-Johnson theories extend the Hertz theory to include the effect of adhesion. The present study provides yield conditions for the JKR, DMT, and Greenwood-Johnson theories of adhesion. Attention is first focused on the initiation of yield along the axis of symmetry of the contact. The results show that the critical loads for the three adhesion theories are close together, but differ significantly from that predicted by Hertz. In fact it is possible for yielding to occur due to adhesion alone, without an external applied load. A curve-fit formula is given to express the yield load as a function of an adhesion parameter for different Poisson’s ratios. Results are also obtained for the onset of plastic deformation away from the axis of symmetry using the Greenwood-Johnson theory of adhesion.
Designing and Fabricating a PZT Strain Sensor for Soil Applications
Authors: Soman Joel , O’Neal Chad B.
Published: August 2009

This research focuses on designing, fabricating, and testing a strain sensor for different soil applications. Using finite element modeling and analysis, the initial dimensions of the diaphragm were designed, and a diaphragm diameter of 1.35 cm with a thickness of 300 μm was chosen. The fabrication process of the sensor prototype is discussed in this paper along with the design for specific test benches to test the electrical and mechanical characteristics at different stages of fabrication. Displacement tests on the sensor diaphragm were performed and the corresponding voltages produced were tabulated. A maximum displacement of 250 μm was achieved producing a maximum voltage of 7.3 mV. The voltage produced by the sensor was recorded using LabVIEW, and its values were tabulated and plotted against corresponding displacement and strain magnitudes.
Dynamic Analysis of Electrically Actuated Rectangular Microplates With Nonlinear Plate Theory Under Squeeze-Film Damping Effect
Authors: Tajalli S. Ahmad , Moghimi Zand Mahdi , Ahmadian Mohammad Taghi
Published: August 2009

In this paper, dynamic behavior and pull-in phenomenon of electrically actuated rectangular micro plates under the effect of squeeze-film damping and nonlinear electrostatic force is studied. Finite element method is implemented in order to drive weak formulations of linear and nonlinear micro plate equations of motion based on classical plate theory (CPT) (for thin microplates with moderate nonlinearity) and squeeze-film damping based on Reynolds nonlinear equation. Finally, an efficient reduced-order model contingent on singular value decomposition method (SVD) is used to study dynamic pull-in phenomenon. This model is constructed by the global basis functions achieved from a few runs of FEM and can reduce simulation time. Validating the macro model results with full FEM simulation shows that this model is effective.
A Self-Powered Wireless Health and Environment Monitoring System
Authors: Singh Ajay , Koomson Vincent , Yu Jaewook , Nejat Goldie
Published: August 2009

The objective of our work is to develop a novel self-powered multi-modal wireless health monitoring sensory system architecture consisting of: (i) wearable devices to continuously monitor the vital signs of a person, and (ii) environmental sensory devices which can monitor the environment and also act as multi-hop routers providing data paths from the wearable devices to a main processing unit. Together these devices can provide effective remote health monitoring of a person and also inform the person of important information. In this paper, we address the significant issue of energy depletion for the devices, which can lead to critical interruptions in monitoring, by proposing a flexible unique vibration-based energy harvesting scheme to support our architecture. This active energy harvesting scheme will allow for continuous remote monitoring of the person and his/her environment in various situations. Experimental results demonstrate the potential utilization of electromagnetic and piezoelectric vibration-based harvesting techniques for the proposed application.
Feasibility of Delivering a Novel Synthetic Membrane Anchor to the Deep Lungs
Authors: El-Aklouk E. , Al-Jumaily A. M. , Henry S.
Published: August 2009

Over recent years, respiratory drug delivery research has broadened to include a wide range of potential applications such as delivering drugs not only into the lung but across it. This includes both current and novel therapies. Comprehensive characterisation of drug delivery to the lungs is a complex task involving the determination of delivered and deposited dose. The main aim of this research is to study the feasibility of nebulising a new novel synthetic molecule that spontaneously and stably incorporate into the lipid bi-layers including cell membranes to a size suitable for delivery to the deep lungs. An electronic inverted microscope is used to view the particles nebulised by a jet nebulizer. A high speed video camera is mounted onto the microscope to view the magnified (400x) particles as they fly at 500 frames per second. Extensive image analysis and particle detection algorithms show that the new synthetic membrane anchor can be nebulised to an appropriate size (3 to 12 microns) and hence can be used as a carrier of target specific medication to the lungs. This may include the delivery of cancer, pulmonary disease and inhalation damage drugs to specific sites where treatment is required. The molecule could also be used for diagnostic purposes as a site specific marker for a particular disease in the lungs.