bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow in a “Cover-Plate” Preswirl Rotor–Stator System
Authors: Karabay H. , Chen J.-X. , Pilbrow R. , Wilson M. , Owen J. M.
Published: May 2009

This paper describes a combined theoretical, computational, and experimental study of the flow in an adiabatic preswirl rotor–stator system. Preswirl cooling air, supplied through nozzles in the stator, flows radially outward, in the rotating cavity between the rotating disk and a cover-plate attached to it, leaving the system through blade-cooling holes in the disk. An axisymmetric elliptic solver, incorporating the Launder–Sharma low-Reynolds-number k–ε turbulence model, is used to compute the flow. An LDA system is used to measure the tangential component of velocity, Vφ, in the rotating cavity of a purpose-built rotating-disc rig. For rotational Reynolds numbers up to 1.2 × 106 and preswirl ratios up to 2.5, agreement between the computed and measured values of Vφ is mainly very good, and the results confirm that free-vortex flow occurs in most of the rotating cavity. Computed values of the preswirl effectiveness (or the nondimensional temperature difference between the preswirl and blade-cooling air) agree closely with theoretical values obtained from a thermodynamic analysis of an adiabatic system.
LDV Study of Developing Flows Through a Smooth Duct With a 180 deg Straight-Corner Turn
Authors: Liou T.-M. , Chen C.-C.
Published: May 2009

In view of the lack of velocity field data for flow through turbine blade internal cooling passages, laser-Doppler velocimetry measurements are presented for the flow development in a two-pass smooth rectangular duct of aspect ratio 1.1 with a 180 deg straight-corner turn with and without duct rotation. The test duct had a curvature axis normal to the rotational axis. The Reynolds number based on the bulk mean velocity and hydraulic diameter was 1.4 × 104 and the rotation numbers were 0 and 0.082. Characteristics such as the upstream and downstream extents of the sharp-turn effect on the main flow profile, curvature induced Dean vortices inside the turn, turning geometry-induced separating bubble immediately downstream of the turn, and the resulting double-peak mean velocity profiles in the second pass are used to describe the developing mean flow for the case without rotation. High turbulence levels and significantly more nonuniform flow after the sharp turn in the front part of the second pass explain previously reported work showing higher but nonuniform heat transfer after that turn. Rotating the duct augments and shifts the peaks of the streamwise mean velocity and turbulence intensity profiles toward the trailing and leading walls of the first and second passes, respectively. In addition, the duct rotation skews the separating bubble and reduces its size to about 75 percent of its stationary counterpart.
A Shock Loss Model for Supersonic Compressor Cascades
Authors: Bloch G. S. , Copenhaver W. W. , O’Brien W. F.
Published: May 2009

Loss models used in compression system performance prediction codes are often developed from the study of two-dimensional cascades. In this paper, compressible fluid mechanics has been applied to the changes in shock geometry that are known to occur with back pressure for unstarted operation of supersonic compressor cascades. This physics-based engineering shock loss model is applicable to cascades with arbitrary airfoil shapes. Predictions from the present method have been compared to measurements and Navier–Stokes analyses of the LO30-4 and L030-6 cascades, and very good agreement was demonstrated for unstarted operation. A clear improvement has been demonstrated over previously published shock loss models for unstarted operation, both in the accuracy of the predictions and in the range of applicability. The dramatic increase in overall loss with increasing inlet flow angle is shown to be primarily the result of increased shock loss, and much of this increase is caused by the detached bow shock. For a given Mach number, the viscous profile loss is nearly constant over the entire unstarted operating range of the cascade, unless a shock-induced boundary layer separation occurs near stall. Shock loss is much more sensitive to inlet Mach number than is viscous profile loss.
A Study of Acoustic Resonance in a Low-Speed Multistage Compressor
Authors: Camp T. R.
Published: May 2009

Measurements are presented of a resonant acoustic phenomenon occurring in a low-speed multistage compressor. The results show that this phenomenon shares many characteristics with acoustic resonance as measured in high-speed compressors. These similarities include a rotating pressure field, several acoustic frequencies corresponding to different circumferential modes, step changes in frequency as the flow rate is increased, and acoustic frequencies that are independent of flow coefficient, shaft speed, and the axial length of the compression system. The paper includes measurements of the helical structure of the rotating pressure field and of the variation in amplitude of the acoustic signal over a stator exit plane.
Computation and Measurement of the Flow in Axial Flow Fans With Skewed Blades
Authors: Beiler M. G. , Carolus T. H.
Published: May 2009

A numerical analysis of the flow in axial flow fans with skewed blades has been conducted to study the three-dimensional flow phenomena pertaining to this type of blade shape. The particular fans have a low pressure rise and are designed without stator. Initial studies focused on blades skewed in the circumferential direction, followed by investigations of blades swept in the direction of the blade chord. A Navier–Stokes code was used to investigate the flow. The simulation results of several fans were validated experimentally. The three-dimensional velocity field was measured in the fixed frame of reference with a triple sensor hot-film probe. Total pressure distribution measurements were performed with a fast response total pressure probe. The results were analyzed, leading to a design method for fans with swept blades. Forward swept fans designed accordingly exhibited good aerodynamic performance. The sound power level, measured on an acoustic fan test facility, improved.
Development of Hub Corner Stall and Its Influence on the Performance of Axial Compressor Blade Rows
Authors: Hah C. , Loellbach J.
Published: May 2009

A detailed investigation has been performed to study hub corner stall phenomena in compressor blade rows. Three-dimensional flows in a subsonic annular compressor stator and in a transonic compressor rotor have been analyzed numerically by solving the Reynolds-averaged Navier–Stokes equations. The numerical results and the existing experimental data are interrogated to understand the mechanism of compressor hub corner stall. Both the measurements and the numerical solutions for the stator indicate that a strong twisterlike vortex is formed near the rear part of the blade suction surface. Low-momentum fluid inside the hub boundary layer is transported toward the suction side of the blade by this vortex. On the blade suction surface near the hub, this vortex forces fluid to move against the main flow direction and a limiting stream surface is formed near the hub. The formation of this vortex is the main mechanism of hub corner stall. When the aerodynamic loading is increased, the vortex initiates further upstream, which results in a larger corner stall region. For the transonic compressor rotor studied in this paper, the numerical solution indicates that a mild hub corner stall exists at 100 percent rotor speed. The hub corner stall, however, disappears at the reduced blade loading, which occurs at 60 percent rotor design speed. The present study demonstrates that hub corner stall is caused by a three-dimensional vortex system and that it does not seem to be correlated with a simple diffusion factor for the blade row.
Optimisation of a Porous Electroosmotic Pump, Used in Thermal Cooling System of Power Electronics
Authors: Berrouche Y. , Avenas Y. , Schaeffer C. , Wang P. , Chang H.-C.
Published: May 2009

The liquid cooling of electronic components is generally implemented by a mechanical pump, which requires a minimal maintenance to ensure the reliability of the device. To solve this problem, it is proposed to replace the mechanical pump by a static one, for example an electro-osmotic (EO) pump. In this paper, firstly we present the theory of the electro-osmosis phenomena, and a model of a porous EO pump. Then an optimization of a porous EO pump made of sintered silica is presented. It was found that for any porous EO pump the optimum operating point of the pump is determined by controlling the diameter of the effective pore radius of the porous silica and the Debye length. Using deionised (DI) water as pumping liquid, the EO pump generates 13.6 ml/min and 2 kPa at 150 V applied voltage. The power consumed by the pump is less than 0.4 W. The EO pump works without any bubbles in the hydraulic circuit. This design can be used to cool 47 W of power generated by the power components with a forced convection without evaporation and 270 W with evaporation.
The Surface Roughness Effect on the Hydrostatic Thrust Spherical Bearings Performance: Part 3 of 5 — Recessed Clearance Type of Bearings
Authors: Yacout Ahmad W.
Published: May 2009

The study deals with the surface roughness and the predominant centripetal inertia terms due to the shaft rotation of the externally pressurized thrust spherical bearings. The solutions are presented for the recessed clearance type of bearings, hemispherical and partial hemispherical seats, with capillary tube and orifice restrictors. Expressions for the pressure distribution, load carrying capacity, volume flow rate, frictional torque, friction factor, power losses and stiffness factor are obtained. The study shows the combined effects of the centripetal inertia and the surface roughness on the bearing performance. An optimum design based on the minimum power losses and the optimal restrictor dimensions is theoretically examined. The conventional four cases of this type of bearings, dependant on the eccentricity ratio in the previous studies, have been reduced to three cases only. In addition, a unified solution for this type of bearings is developed. Finally, a general solution for the hydrostatic thrust spherical bearings is produced where it could be applied to the, un-recessed and the recessed - hemispherical, partial hemispherical - clearance and fitted types of bearings. This general solution considers the fitted type of bearings as a special case of the clearance type. A comparison between the results calculated by the general solution and the private solution for both of the fitted type and the un-recessed clearance type of bearings is performed.
The Surface Roughness Effect on the Dynamic Stiffness and Damping Characteristics of the Hydrostatic Thrust Spherical Bearings: Part 5 of 5 — Clearance Type of Bearings
Authors: Yacout Ahmad W.
Published: May 2009

This study has theoretically analyzed the surface roughness, centripetal inertia and recess volume fluid compressibility effects on the dynamic behavior of a restrictor compensated hydrostatic thrust spherical clearance type of bearing. The stochastic Reynolds equation, with centripetal inertia effect, and the recess flow continuity equation with recess volume fluid compressibility effect have been derived to take into account the presence of roughness on the bearing surfaces. On the basis of a small perturbations method, the dynamic stiffness and damping coefficients have been evaluated. In addition to the usual bearing design parameters the results for the dynamic stiffness and damping coefficients have been calculated for various frequencies of vibrations or squeeze parameter (frequency parameter) and recess volume fluid compressibility parameter. The study shows that both of the surface roughness and the centripetal inertia have slight effects on the stiffness coefficient and remarkable effects on the damping coefficient while the recess volume fluid compressibility parameter has the major effect on the bearing dynamic characteristics. The cross dynamic stiffness showed the bearing self-aligning property and the ability to oppose whirl movements. The orifice restrictor showed better dynamic performance than that of the capillary tube.
Waste Heat From Chemical Factories and Paper Factories
Authors: Okamoto Satoru
Published: May 2009

The aim of this study is to know the real state of waste heat from the industry. The study was conducted for making data base of waste heat from internal industries through the investigation of high energy consumption industries aiming at grasping the condition of exhaust heat from main factories of two types of chemical industry and paper industry as accurately as possible in 2002. Questionnaire survey was made about chemical factories and paper factories in Shikoku Area in Japan and those replies were received. The data base was made by using those data.
A Nonequilibrium Thermal Model for Rapid Heating and Pyrolysis of Organic Composites
Authors: Zhou Jianhua , Zhang Yuwen , Chen J. K. , Smith D. E.
Published: May 2009

A nonequilibrium heat transfer model is developed to predict the through-thickness transient temperature variation in organic composites subjected to intensive heating. In addition to heat conduction, the model incorporates four important mechanisms: rate-dependent pyrolysis, pyrolysis byproduct outgassing, irradiance-dependent convection heat loss, and radiation heat loss. The heat conduction in the solid part is considered to be one-dimensional, and the compressible gas flow in the pyrolysis region is treated as two-dimensional. Both the shape of the gas flow channel and the gas addition velocity from the channel wall are evaluated based on the decomposition reaction rate. An iterative numerical procedure is formulated to solve the coupled heat transfer and gas flow equations. Numerical results, including the through-thickness temperature transients, the continually changing gas channel, and the pressure distribution in the decomposition gas are obtained and discussed.
A Methodology to Evaluate Artificial Neural Network Training Used to Estimate Transformer Failure Probability
Authors: Susemihl Enrique A. , Xu Shuzhen
Published: May 2009

In a previous paper [1] the authors presented a methodology to estimate the probability of failure of power transformers due to paper insulation degradation. The methodology was based on the identification of patterns in indirect measurements by means of an artificial neural network (ANN). The parameters measured were the amounts of dissolved gases and other chemical in the transformer oil. The failure probability was then estimated from the population life data. The methods presented in this paper are useful to estimate the quantitity of cases required for the training of the ANN to achieve acceptable predicted values, which is particularly important when the available data is limited.
Reliability Analysis of Water Mist Systems
Authors: Xu Shuzhen , Susemihl Enrique A.
Published: May 2009

This paper presents some preliminary results from a reliability study of water mist systems conducted at FM Global. The study includes a detailed Failure Modes and Effects Analysis (FMEA) to identify all the major potential failure modes, which include demand, quiescent and operational failures. Various fault trees are thus constructed for the typical water mist system configurations to evaluate the failure probabilities. However, due to the short history of industrial application of water mist systems, no specific reliability data are available. Therefore, in the calculation of system failure probability, the component failure data are obtained from other applications. The failure probabilities and the confidence bounds of the typical water mist systems listed in the Standard 750 of the National Fire Protection Association are compared in the paper. The major failure modes identified through an importance analysis are also presented.
Modeling of an Integrated Wind Energy Building
Authors: Pedersen William E. , Pope Daniel N.
Published: May 2009

This study presents the design and modeling of an integrated wind energy building. It is proposed that a building be constructed with an integral wind turbine that takes advantage of the funneling of wind from the building structure and the low pressure area above or leeward of the building. Computational Fluid Dynamics (CFD) was used to evaluate different building geometries and wind potentials. Preliminary investigations using two dimensional numerical modeling in both the horizontal and vertical planes are presented. Three dimensional analyses are also presented of promising geometries from the two dimensional preliminary results. While additional modeling efforts will be necessary to optimize this system, results indicate a significant improvement in performance over free standing turbines, allowing for utilization of wind power in geographic regions that have traditionally not been feasible.
A Micromachined Silicon Flexure for Tunable External Cavity Diode Laser
Authors: Chuang Ho-Chiao , Jime´nez-Marti´nez Ricardo , Braun Simon , Anderson Dana Z. , Bright Victor M.
Published: May 2009

We present a novel external cavity diode laser design developed for atomic physics which employs a micromachined silicon flexure to sweep the laser frequency and a volume holographic reflection grating (VHG) to provide the optical feedback. The advantages of using a silicon flexure are its simple microfabrication process and reduction of the overall size of the laser system. The results demonstrate an optimized threshold current reduction from 59mA to 43mA, a frequency sweeping range of 2.069 GHz, and 87Rb, 85Rb (Rubidium) D2 line absorption at 780 nm.
Excitation of Structural Resonance Due to a Bearing Failure
Authors: Leishear Robert A. , Stefanko David B. , Newton Jerald D.
Published: May 2009

Vibration due to a bearing failure in a pump created significant vibrations in a fifteen foot by fifteen foot by eight feet tall mounting platform due to excitation of resonant frequencies. In this particular application, an 18,000 pound pump was mounted to a structural steel platform. When bearing damage commenced, the platform vibrated with sufficient magnitude that conversations could not be heard within forty feet of the pump. Vibration analysis determined that the frequency of the bearing was coincident to one of the natural frequencies of the pump, which was, in turn, coincident to one of the natural frequencies of the mounting platform. This coincidence of frequencies defines resonance. Resonance creates excessive vibrations when the natural frequency of a structure is coincident to an excitation frequency. In this well documented case, the excitation frequency was related to ball bearing failures. The pump is a forty foot long vertical pump used to mix nuclear waste in 1,300,000 gallon tanks. A 300 horsepower drive motor is mounted to a structural steel platform on top of the tank. The pump hangs down into the tank from above to mix the waste and is inaccessible after installation. Initial awareness of the problem was due to increased noise from the pump. Initial vibration analysis indicated that the vibration levels of the bearing were within the expected range for this type of bearing, and the resonant condition was not obvious. Further analysis consisted of disassembly of the motor to inspect the bearings and extensive vibration monitoring. Vibration data for the bearings was obtained from the manufacturer and compared to measured vibration plots for the pump and mounting platform. Vibration data measured along the length of the pump was available from full scale testing, and vibrations were also measured at the installed pump. One of the axial frequencies of the pump, the platform frequency in the vertical direction, and the ball spin frequency for the bearing were multiples of each other. This resonant condition was detected before other damage occurred, and further damage due to the resonant condition was prevented through vibration analysis.
Free Bending Vibrations of Integrally-Stiffened and/or Stepped-Thickness Rectangular Plates or Panels With a Non-Central Plate Stiffener
Authors: Yuceoglu U. , Gemalmayan N. , Sunar O.
Published: May 2009

The present study is primarily concerned with the “Free Bending Vibrations of Integrally-Stiffened and/or Stepped-Thickness Plates or Panels with a Non-Central Plate Stiffener”. The general theoretical formulation is based on the “Mindlin Plate Theory”. The plate elements of the system are considered to be made of dissimilar orthotropic materials with unequal thicknesses. The transverse shear deformations and the transverse and the rotary moments of inertia of plate elements are included in the analysis. The damping effects, however, are neglected. The dynamic equations of the orthotropic “Mindlin Plates” in combination with the stress resultant-displacement expressions are algebraically manipulated. They are eventually reduced to a set of the “Governing System of the First Order Ordinary Differential Equations” in the “state vectors” form. The resulting differential equations system is numerically integrated by making use of the “Modified Transfer Matrix Method (MTMM) (with Interpolation Polynomials)”. The mode shapes with their dimensionless natural frequencies are presented for various support conditions in the “isotropic” Al-Alloy and in the “orthotropic” composite cases. Additionally, the effect of some of the important parameters such as (“Stiffener Position Ratio”, “Thickness Ratio”, “Stiffener Length (or Width) Ratio)” on the dimensionless natural frequencies are investigated and plotted. Based on the numerical results, some brief but important conclusions are presented.
An Alternative Protocol for Determining Viscoelastic Material Properties Based on Tensile Tests Without the Use of Poisson’s Ratios
Authors: Shtark Abraham , Grosbein Hagay , Sameach Guy , Hilton Harry H.
Published: May 2009

Analytical and experimental protocols are formulated and outlined in detail wherein unidirectional tensile creep or relaxation experiments are performed on viscoelastic specimen. A combination of a photogrametric system and a tensile testing machine provides stress data in the loaded direction and strains in both longitudinal and transverse directions. The data is integrated through the use of the integral constitutive relations, and produce values for the creep compliance parameters. Subsequently, the viscoelastic Young’s, shear and bulk moduli are determined without the use of viscoelastic Poisson’s ratios. Experimental results indicate strong time, stress and stress history dependencies of viscoelastic PRs. Current experimental results are compared with traditional methods based on assumed time independent Poisson ratios. Maximum errors in strain values from 160% to 205% for the constant PR approach are demonstrated when its results are compared to results for the experimental time interval.
Networked Assembly of Nonlinear Physical System Models
Authors: Motato Eliot , Radcliffe Clark J.
Published: May 2009

Engineering design is evolving into a global strategy that distributes model information through computer networks. This strategy requires companies to provide dynamic models of supplied physical components. Component models are transmitted through the Internet to a common location and then assembled to obtain a product dynamic model. Internet connection permitting, real-time, automated assembly of models requires four characteristics. Specifically, physical models must have a unique standard format, the exchange of model information must be executed in a single-query transmission, the models must describe only external behavior, and the assembly process must be recursive. The Modular Modeling Method (MMM) is an energy based model distribution and assembly algorithm that satisfies these four requirements. The MMM distributes and assembles linear and affine physical systems models using dynamic matrices. Though the MMM procedure can be used for a large class of systems, the dynamic matrices cannot be used to represent nonlinear behavior. A more general nonlinear model representation is required. This work is an extension of the MMM algorithm to assemble physical systems models characterized by analytic nonlinearities. This is a more general procedure that uses Volterra transfer functions to represent nonlinear behavior. Any analytic nonlinear system can be represented through a Volterra model. The reason why we use Volterra models instead ODEs is because Volterra models are only in function of input and output variables. This characteristic facilitates their use in an energy based model assembly method such as the MMM procedure. A procedure to assemble standard Volterra models using conservation energy principle is described. Even though there are extensive literature about gluing models, these techniques do not have all the characteristics needed by the MMM procedure. Using the approach proposed here, complex model assemblies can be executed recursively while hiding the topology and characteristics of their structural model subassemblies.
Analysis of Formation of Vapor Columns in Film Boiling
Authors: Tomar G. , Biswas G. , Sharma A.
Published: May 2009

Boiling is an effective means of enhancing heat transfer from a heated surface. Above a critical superheat and heat flux (Leidenfrost point) stable film boiling is observed. In the film boiling regime, bubble formation occurs periodically in space and time. The site of bubble growth is called a node and the site between two nodes is called an antinode. The spacing between two consecutive nodes is given by the most dangerous Taylor wavelength (Berenson, 1961). An increase in the superheat results in an increase in the frequency of bubble formation and its subsequent detachment. Reimann and Grigull (1975) in their experiments observed that above a critical heat flux, bifurcation from the periodic bubble formation occurs and at the nodes, stable column formation takes place. However, at the antinodes, periodic bubble formation is still observed. On further increasing the heat flux, thin slender vapor columns form at the nodes and antinodes. Bubble formation and detachment in such cases take place from the tip of these stable columns. Numerical simulations of bubble growth in film boiling have been attempted using Volume of Fluid (VOF) methods as well Level Set (LS) methods. We here use a Coupled Level Set and Volume of Fluid (CLSVOF) method to perform simulations of saturated film boiling of water at near critical pressure (21.9MPa). In these simulations, we show that the initial film thickness plays a key role in the prediction of the critical superheat above which stable vapor columns are observed to be formed. Capillary pressure leads to snap-off of the leftover-stem of vapor after bubble detachment. Formation of stable columns is a result of balance between the inertial pressure due to the vapor influx into the column and the capillary pressure.
Preferred Vehicle Scaling
Authors: Jonson Michael L.
Published: May 2009

Properly designed and geometrically similar small-scale models can provide insight into component and system performance of large vehicles for a variety of engineering disciplines for a fraction of the cost compared to full scale fabrication and testing. Using the density, specific heat, magnetic permeability of the fluid, the rotation rate, and the size, the author provides non-dimensional performance properties broadly encompassing the hydrodynamic, acoustic, electro-magnetic, thermal, and structural fields. The preferred numbers based on a geometric series as devised by Renard are introduced. The author then provides a method for defining a mean and standard deviation of a size differences from a standard geometric series. In particular, statistics for customary and metric material specifications of sheet metal, square and round stock, electrical wire, fasteners, beams, and pipes are quantified. The study concludes that preferred numbers are best for standard material sizes and scales and suggests potential procedures for improving systems engineering.
Analysis on the Effect of Input Impact Profiles in Drop Test
Authors: Zhou Jiang , Niraula Ratna P. , Aung Kendrick
Published: May 2009

The objective of this paper is to develop an analytical or mathematical predicative model for the evaluation of dynamic response of a structural element in a microelectronic or an optoelectronic product to an impact load occurring as a result of drop or shock test. Closed-form theoretical solution was obtained to simulate the board level drop test. The block diagram based SIMULINK analysis was introduced to determine the response with various impact configurations for the system level drop test as well. This study will help reliability engineers to design the impact input profiles and obtain the desired responses, and to calibrate and validate finite element analysis results quickly for both board level and system level drop test. It was found that time durations of the input profiles play an important role in the dynamic response. The system response can be designed by carefully choosing the impact time duration. Certain input pulse time results in the response with very low ringing after first or second peaks.
Photonic Control of a Free-Floating Parabolic Membrane Shell
Authors: Shih Hui-Ru , Tzou Horn-Sen , Zheng Wei
Published: May 2009

Communication antennas, optical mirrors, solar/optical reflectors, etc. often have the shape of parabolic shells or shells of revolution, due to their required focusing, aiming, or reflecting performance. In this paper, the wireless control of free-floating flexible parabolic shells using discrete photostrictive actuators is investigated. Parabolic shell of revolution is considered to be one of the most difficult geometry among all shell and non-shell structures. Because of this, an approximate way to estimate the dynamic behavior and light-induced control forces of a photostrictive coupled parabolic shell is presented. Based on the approximate spherical model, the effects of actuator locations as well as membrane and bending components on the control action are analyzed. The results obtained indicate that the control forces are location dependent. It is also shown by analysis that the membrane control action is much more significant than the bending control action. The validation of the approximate model is done by comparing the light-induced control forces of the photostrictive coupled shells obtained by the approximate equivalent spherical shell model and those obtained by the parabolic shell model. From the comparison, it can be concluded that there is only a slight difference between a spherical shell and a parabola for surface with an F/D (focal length to diameter ratio) of 1.00 or larger.
Nonlinear Response of a Sandwich Plate Subjected to Blast Load
Authors: Bas¸ Ali , Kazancı Zafer , Mecitog˘lu Zahit
Published: May 2009

Present work includes in-plane stiffness and inertia effects on the motion of a sandwich plate under blast load. The geometric nonlinearity effects are taken into account with the von Ka´rma´n large deflection theory of thin plates. All edges clamped boundary conditions are considered in the analyses. The equations of motion for the plate are derived by the use of the virtual work principle. Approximate solutions are assumed for the space domain and substituted into the equations of motion. Then the Galerkin Method is used to obtain the nonlinear differential equations in the time domain. The finite difference method is applied to solve the system of coupled nonlinear equations. The results of theoretical analyses are obtained.
Parametric Modeling Study of Nanoparticle Penetration Into Spherical Cell Clusters
Authors: Matveev Konstantin I. , Goodman Thomas T. , Chen Jingyang , Pun Suzie H.
Published: May 2009

Nanoparticle-based drug delivery is a promising cancer treatment method due to the ability to target tumor sites by preferential extravasation and to deliver higher loads of therapeutics. Although nanoparticle penetration in tumor tissue is limited due to diffusional restrictions, delivery can be improved by enzymatic degradation of extracellular matrix proteins at the tumor site. Here, a mathematical model describing transport of nanoparticles in non-uniformly porous spheroids is developed, accounting for binding of particles with cells and endocytosis. Results of parametric simulations for nanoparticle concentration inside spheroids highlight the influence of various system parameters. Preliminary experimental data show qualitative agreement with the theory. These results are useful for understanding nanoparticle delivery and for designing drug delivery strategies.
Study of Nanofluid Natural Convection Phenomena in Rectangular Enclosures
Authors: Wong Kau-Fui V. , Bon Bradley L. , Vu Santina , Samedi Sing
Published: May 2009

Buoyancy induced flows in rectangular enclosures using nanofluids were investigated. The effects of mass fraction concentration of nanoparticles, enclosure aspect ratio and inclination were observed. The nanofluid under investigation was a water-based alumina nanofluid. Since water exhibits an anomalous density extremum near 4°C the additional effect of buoyancy force reversal will also be observed. The opacity of nanofluid does not permit the use of particle image velocimetry, laser induced fluorescence or any other means of flow visualization or visual temperature measurement of the local fluid temperature. Therefore to investigate the temperature field a non-invasive method, namely ultrasound thermometry, will be used to observe the temperature field. The experimental enclosure was validated using water as the initial fluid; measured values of the local fluid temperature were compared with numerical simulations utilizing COMSOL Multiphysics. Nanofluid mass fractions of 10% and 25% were used for comparative purposes of the effects of concentration on the temperature field. Buoyancy force reversal effects were witnessed in both 10% and 25% concentrations. The nanofluid also prolonged the multicellular effects that occur in buoyancy inversion flows. A Rayleigh number inversion was observed for the 25% mass fraction nanofluid. The multicellular regime transitions to boundary layer regime at about Ra=1E+07 when the aspect ratio is 2.625 and at about Ra=2E+08 when the aspect ratio is 1.000, for different concentrations of nanofluid. For these concentrations of nanofluid and aspect ratio equal to 2.625, instability in the core region occurred at about Ra=1.2E+07.
In-Vitro Wall Shear Stress Measurements for Microfluid Flows by Using Second-Order SPE Micro-PIV
Authors: Chuang Han-Sheng , Wereley Steven T.
Published: May 2009

Conventional single pixel evaluation (SPE) significantly improves the spatial resolution of PIV measurements to the physical limit of a CCD camera based on the forward difference interrogation (FDI). This paper further enhances the computational algorithm to second-order accuracy by simply modifying the numerical scheme with the central difference interrogation (CDI). The proposed central difference scheme basically superposes the forward-time and the backward-time correlation domains, thus resulting in reduced bias error as well as rapid background noise elimination. An assessment of the CDI SPE algorithm regarding the measurement errors was achieved via numerous synthetic images subject to a four-roll mill flow. In addition, preliminary wall shear stress (WSS) measurements regarding different algorithms are also evaluated with an analytical turbulent boundary flow. CDI scheme showed a 0.32% error deviated from the analytical solution and improved the same error in FFT-based correlation correlation (FFT-CC) by 32.35%. To demonstrate the performance in practice, in-vitro measurements were implemented in a serpentine microchannel made of polydimethyl siloxane (PDMS) for both CDI SPE and spatial cross-correlation. A series of steady-state flow images at five specified regions of interest were acquired using micro-PIV system. Final comparisons of the WSS regarding the Pearson correlation coefficient, R2, between the numerical schemes and the simulations showed that an overall result was improved by CDI SPE due to the fine resolution and the enhanced accuracy.
Emerging Energy Development Demands on Water
Authors: Hightower Mike
Published: May 2009

Currently, electric power generation is one of the largest water withdrawal and use sectors in the U.S. Additionally, future energy development such as biofuels production, hydrogen fuel or synthetic fuels production, oil shale development, carbon sequestration, or nuclear power development could significantly increase water use and consumption. On the other hand, water resource development — distribution, treatment, and transmission — is one of the largest energy use sectors. As future demands for energy and water continue to increase, competition for water between the energy, domestic, agricultural, and industrial sectors, could significantly impact the availability of water supplies for energy development, thus impacting reliability and security of future energy production and electric power generation. Therefore, it is critical that water and energy resources planning and development be integrated and coordinated across state and regional boundaries. This paper provides a short overview of the emerging energy-water challenges and issues identified in a recent series of national workshops on energy and water related issues as well as summarizing the research and development needs to address these emerging energy and water challenges.
Using Passive RFID Technology for Mobile Robot Navigation and Environment Mapping
Authors: Milella Annalisa , Vanadia Paolo , Cicirelli Grazia , Distante Arcangelo
Published: May 2009

In this paper, the use of passive Radio Frequency Identification (RFID) as a support technology for mobile robot navigation and environment mapping is investigated. A novel method for localizing passive RFID tags in a geometric map of the environment using fuzzy logic is, first, described. Then, it is shown how a mobile robot equipped with RF antennas, RF reader, and a laser range finder can use such map for localization and path planning. Experimental results from tests performed in our institute suggest that the proposed approach is accurate in mapping RFID tags and can be effectively used for vehicle navigation in indoor environments.
A Novel Basis for Membrane Adaptive Optics: The Clamped Zernike Radial Polynomials
Authors: Ruggiero Eric J. , Inman Daniel J. , Marker Dan K.
Published: May 2009

The future of adaptive optics relies heavily on the development of membranous optical lenses. Large, deformable mirrors offer clear advantages over their glass counterparts: flexibility, low density, and minimal actuation for optical aberration correction. This paper develops a novel set of polynomials to describe incoming wavefront aberrations that is amiable to a membrane mirror’s mode shapes. The novel basis, named the clamped Zernike radial polynomials, conveniently delineates the image correction into four distinct actuation categories feasible with membrane optics.
An Alternative Field Test for Spot Air Conditioning Units
Authors: Wong Kau-Fui V. , Valde´s Diego , Goad Joshua , Losada Jesse
Published: May 2009

U.S. governmental standards require that newly produced air conditioners have a SEER (seasonal energy efficiency ratio) rating of over 13, Federal Register (2001), [1]. This rating is closely tied to the COP (coefficient of performance). In fact, the SEER is 3.792 times the COP. Since COP varies with temperature loads, a standard testing method requires the unit to be tested at standard conditions of temperature and humidity. This requires the use of expensive climate control chambers, where the system can be loaded to the specified temperatures. The scope of this paper proposes a simpler, less expensive method to test spot AC (air conditioning) units, as an alternative field test to ASHRAE (American Society of Heating, Refrigeration, and Air-Conditioning Engineers) Standard 128 (2001), [2]. By taking temperature measurements of the appropriate control volume, the COP can be calculated. To obtain steady state, the control volume will be treated as very large (or infinite), placing the unit to be tested outdoors or in a room big enough so that delta T will remain constant. Themocouples in conjunction with data logging software are used to take the temperature measurements, and the mass flow rate is measured by assuming uniform flow and placing a flow meter in the center of the air exhaust, on the evaporator side. The entire system can be assembled into a portable unit composed of a computer, thermocouples, flow meter and a digital multimeter, alternatively, a handheld relative humidity and temperature sensor can be used, ASHRAE (2003), [3]. This would allow not only testing of units before they go into production, but having technicians in the field test the efficiency of units already in operation. The need may be there since there could be a significant drop in the SEER between factory conditions and installed unit, due to variations in duct sizes, losses due to non-ideal installations. Owing to the fact that the COP varies with loading, and our testing method requires no artificial control over loading temperatures, the current study is being conducted to find if the AC unit can perform up to its rating. The second law COP at environmental loading conditions is also evaluated for each of the five AC units tested. The calculated COPII (based on exergy) of the AC units tested do not vary as much (percentage-wise) as the rated COP. Their relative detrimental effects to the environment are probably not that much different from each other.
Self-Powered Bacterial Transportation Systems in Low Reynolds Number Fluidic Environments
Authors: Steager Edward , Patel Jigarkumar , Kim Chang-Beom , Bith Socheth , Naik Chandan , Reber Lindsay , Kim Min Jun
Published: May 2009

We have studied self-coordinated bacterial transportation systems using SU-8 microbarges in low Reynolds number fluidic environments. Flagellated Serratia marcescens bacteria were attached to microbarges using a blotting technique that creates a bacterial monolayer carpet. These bacterial carpets naturally self-coordinate to propel the microbarges in a manner that have been controlled by phototactic means. We additionally demonstrate phototactic control of these barges. Tracking algorithms were designed to study the motion of the microbarges.
Multiscale Constitutive Modeling of Polymer Materials
Authors: Valavala Pavan K. , Odegard Gregory M.
Published: May 2009

A nonlinear multiscale constitutive modeling framework is used to predict the elastic modulus of a glassy polymer. A set of seven molecular models with different molecular configurations is utilized to study the effect of the minimized potential energy level on the predicted elastic moduli. It is found that the average modulus from the seven models considered in the current study is seen to be in reasonable agreement with the experimentally observed value, given the statistical uncertainly in the data.
Promoting Effective Student Problem Solving
Authors: Bennett J. C.
Published: May 2009

If one were to ask most anyone what engineers do, they would say “solve problems.” And indeed, engineers do [but I would suggest that all people solve problems regardless of their chosen careers]. What are less obvious are [a] whether engineering students and graduates are effective problem solvers; [b] whether engineering education is facilitated effectively as a “problem to be solved” and [c] whether that engineering education intentionally facilitates the development by students of an effective problem solving approach. In this paper, it is argued that instructors use of effective problem solving in course development, preparation, and facilitation must include the explicit attention to the student development of effective problem solving procedures. In this paper, it is argued that students will become more effective problem solvers if instructors encourage them to use procedures that embrace ambiguity and if instructors more consistently expect them to apply the procedures to open-ended problems throughout the curriculum. As students move from well-defined problem solving to more complex problem solving, they will benefit from one general and effective problem-solving procedure that is sufficiently flexible to include the various and more specific procedures that students will encounter. With career paths continually evolving and with information generation growth ever expanding, such skills are absolutely critical to success, again regardless of career choice.
Processing and Characterization of Carbon Fiber/Epoxy Composites Reinforced With Graphite Nanoplatelets
Authors: Chen J. Y. , Cho J. , Daniel I. M.
Published: May 2009

The epoxy matrix in carbon fiber/epoxy composites was modified with graphite nanoplatelets to improve the matrix dominated mechanical properties of the composite. A prepreg-autoclave process was developed for preparation of nanoparticle-reinforced fiber composites. The in-plane shear modulus and longitudinal compressive strength were enhanced. The compressive strength of the composite was increased by 43% and 44%, and the in-plane shear modulus was improved by 7% and 15% for 3 wt% and 5 wt% of nanoparticle loadings, respectively. This mechanical enhancement is mainly attributed to the reinforcement of matrix phase by the nanoparticles. However, the substantially improved compressive strength is attributed in large part to the reduced waviness of the fibers in the uni-weave perform caused by the nanoparticles between layers.
Eco-Design Value Alignment: Keys to Success
Authors: Gheorghe Razvan , Ishii Kosuke
Published: May 2009

This article analyzes the eco-design challenges in the 21st century. In a world of globalization and outsourcing, environmental legislation became a main driver for doing eco-design. Eco-innovation and green money are concepts to create marketing advantages and differentiation from their competitors, transforming a legislative handicap into financial benefits and societal recognition. This paper introduces Life cycle Environmental Value Chain Analysis (LC-EVCA) and Environmental Worth Analysis (EWA) to identify the stake-holders implementing environmental improvement programs and the value relationships among them. Life cycle information and societal concerns are the keys to success for the eco-design value alignment. Philips environmental programs and a brief example illustrate how eco-design can be integrated into product development, and how both customer (society) and producers find themselves in a win-win situation.
Outcome Based Assessment and Continuous Improvement Model for Engineering Technology Programs
Authors: Verma Alok K.
Published: May 2009

Assessment and continuous improvement are essential and critical processes for higher education. Development and implementation of such processes are not only required by the Accreditation Board for Engineering and Technology (ABET) as part of the accreditation process but are also necessary for the maturation and development of any engineering technology program. The assessment and continuous improvement plan discussed here was developed at Old Dominion University (ODU) and implemented during the last accreditation cycle within the Engineering Technology Department. The plan is based on two cycles of assessment and evaluation, a short cycle of one year and a long term cycle of three years. The plan includes a variety of assessment methods and tools. In addition to assessing the achievement of program outcomes, the plan allows assessment of program objectives and goals. A method for individual course assessment is also presented. Issues related to institutionalization of the assessment process are also discussed.