bluuebunny/crossref_metadata_2025 huggingface dataset:
The Strength of High-Temperature Ag–In Joints Produced Between Copper by Fluxless Low-Temperature Processes
Authors: Wu Yuan-Yun , Lee Chin C.
Published: December 2013

Two copper (Cu) substrates were bonded using silver (Ag) and indium (In) and annealed at 200–250 °C to convert the joints into the solid solution (Ag) for enhanced strength and ductility. Cu–Cu pair was chosen so that the samples break in the joint during shear test. The upper Cu was electroplated with 15 μm Ag. The lower Cu was plated with 15 μm Ag, followed by In and 0.1 μm Ag to inhibit indium oxidation. Two designs were implemented, using 8 μm and 5 μm In, respectively. The Cu substrates were bonded at 180 °C in 100 mTorr vacuum without flux. Afterwards, samples were annealed at 200 °C for 1000 h (first design) and at 250 °C for 350 h (second design), respectively. Scanning electron microscope with energy dispersive X-ray analysis (SEM and EDX) results indicate that the joint of the first design is an alloy of mostly (Ag) with micron-size Ag2In and (ζ) regions, and that of second design has converted to a single (Ag) phase. Shear test results show that the samples are very strong. The breaking forces far exceed requirements in MIL-STD-883 H standards. Fracture incurs inside the joint and is a mix of brittle and ductile modes or only ductile mode. The joint solidus temperatures are 600 °C and 900 °C for the first and second designs, respectively.
Control of Polynomial Nonlinear Systems Using Higher Degree Lyapunov Functions
Authors: Yang Shuowei , Wu Fen
Published: December 2013

In this paper, we propose a new control design approach for polynomial nonlinear systems based on higher degree Lyapunov functions. To derive higher degree Lyapunov functions and polynomial nonlinear controllers effectively, the original nonlinear systems are augmented under the rule of power transformation. The augmented systems have more state variables and the additional variables represent higher order combinations of the original ones. As a result, the stabilization and L2 gain control problems with higher degree Lyapunov functions can be recast to the search of quadratic Lyapunov functions for augmented nonlinear systems. The sum-of-squares (SOS) programming is then used to solve the quadratic Lyapunov function of augmented state variables (higher degree in terms of original states) and its associated nonlinear controllers through convex optimization problems. The proposed control approach has also been extended to polynomial nonlinear systems subject to actuator saturations for better performance including domain of attraction (DOA) expansion and regional L2 gain minimization. Several examples are used to illustrate the advantages and benefits of the proposed approach for unsaturated and saturated polynomial nonlinear systems.
Distributed Full-State Observers With Limited Communication and Application to Cooperative Target Localization
Authors: Spinello Davide , Stilwell Daniel J.
Published: December 2013

We present a fully decentralized motion control algorithm for the coordination of platoons of mobile agents with highly restricted communication capabilities. In order to address very low bandwidth communication between agents and time varying communication network topologies, we utilize a distributed full-state observer onboard each agent. Agent motion and data fusion algorithms are implemented locally by each agent based on the state of the local full-state estimator. Although no separation principle exists between decentralized agent motion control and distributed data fusion in general, we introduce a gradient-based framework in which simultaneously we achieve asymptotic agreement among full-state estimators and convergence of desired agent motion.
Study on the Transfer Film Layer in Sliding Contact Between Polymer Composites and Steel Disks Using Nanoindentation
Authors: Chang Li , Friedrich Klaus , Ye Lin
Published: December 2013

In the present work, nanoindentation experiments were carried out to characterize the localized transfer film layer (TFL) on a steel disk, which resulted from a sliding contact of the latter against a polymer composite pin. It was found that the hybrid nanocomposites filled with both nanoparticles and traditional tribo-fillers were more effective to form durable TFLs on the steel counterpart, associated with desirable tribological properties of the sliding system, i.e., a low friction coefficient and a low wear rate. By studying the load-displacement behavior of polymeric TFLs on metallic substrates, the thickness of TFLs could be estimated, thus, allowing the comparison of TFLs formed under different sliding conditions in a quantitative way. Based on the experimental data, the effects of TFLs on the tribological performance of polymer composites were further discussed in terms of a “transfer film efficiency factor” λ, which was calculated by the ratio of the average thickness of the TFL to the surface roughness of the steel counterpart. The factor mainly considered the relative contributions of the TFL and the metallic counterface to the wear process of the polymer-on-metal system. Accordingly, the wear rate and the friction coefficient of the sliding system could be analyzed as a function of the transfer film efficiency factor, resulting in a Stribeck type diagram. The analyses provided new insight into the role of TFLs in polymer tribology.
Development of Chitosan and Polylactic Acid Based Methotrexate Intravitreal Micro-Implants to Treat Primary Intraocular Lymphoma: An In Vitro Study
Authors: Manna Soumyarwit , Augsburger James J. , Correa Zelia M. , Landero Julio A. , Banerjee Rupak K.
Published: December 2013

Primary intraocular lymphoma (PIOL) is an uncommon but clinically and pathologically distinct form of non-Hodgkin's lymphoma. It provides a therapeutic challenge because of its diverse clinical presentations and variable clinical course. Currently available treatments for PIOL include intravenous multiple drug chemotherapy, external beam radiation therapy, and intravitreal methotrexate (MTX) injection. Each intravitreal injection of MTX is associated with potentially toxic peaks and subtherapeutic troughs of intraocular MTX concentration. Repetitive injections are required to maintain therapeutic levels of MTX in the eye. A sustained release drug delivery system is desired for optimized therapeutic release (0.2–2.0 μg/day) of MTX for over a period of 1 month to achieve effective treatment of PIOL. This study reports development of a unique intravitreal micro-implant, which administers therapeutic release of MTX over a period of 1 month. Chitosan (CS) and polylactic acid (PLA) based micro-implants are fabricated for different MTX loadings (10%, 25%, and 40% w/w). First, CS and MTX mixtures are prepared for different drug loadings, and lyophilized in Tygon® tubing to obtain CS-MTX fibers. The fibers are then cut into desired micro-implant lengths and dip coated in PLA for a hydrophobic surface coating. The micro-implant is characterized using optical microscopy, scanning electron microscopy (SEM), time of flight-secondary ion mass spectroscopy (ToF-SIMS), and differential scanning calorimetry (DSC) techniques. The release rate studies are carried out using a UV-visible spectrophotometer. The total release durations for 10%, 25%, and 40% w/w uncoated CS-MTX micro-implants are only 19, 29, and 32 h, respectively. However, the therapeutic release durations for 10%, 25%, and 40% w/w PLA coated CS-MTX micro-implants significantly improved to 58, 74, and 66 days, respectively. Thus, the PLA coated CS-MTX micro-implants are able to administer therapeutic release of MTX for more than 50 days. The release kinetics of MTX from the coated micro-implants is explained by (a) the Korsmeyer–Peppas and zero order model fit (R2 ∼ 0.9) of the first 60% of the drug release, which indicates the swelling of polymer and initial burst release of the drug; and (b) the first order and Higuchi model fit (R2 ∼ 0.9) from the tenth day to the end of drug release, implying MTX release in the therapeutic window depends on its concentration and follows diffusion kinetics. The PLA coated CS-MTX micro-implants are able to administer therapeutic release of MTX for a period of more than 1 month. The proposed methodology could be used for improved treatment of PIOL.
How Bone Tissue and Cells Experience Elevated Temperatures During Orthopaedic Cutting: An Experimental and Computational Investigation
Authors: Dolan Eimear B. , Vaughan Ted J. , Niebur Glen L. , Casey Conor , Tallon David , McNamara Laoise M.
Published: December 2013

During orthopaedic surgery elevated temperatures due to cutting can result in bone injury, contributing to implant failure or delayed healing. However, how resulting temperatures are experienced throughout bone tissue and cells is unknown. This study uses a combination of experiments (forward-looking infrared (FLIR)) and multiscale computational models to predict thermal elevations in bone tissue and cells. Using multiple regression analysis, analytical expressions are derived allowing a priori prediction of temperature distribution throughout bone with respect to blade geometry, feed-rate, distance from surface, and cooling time. This study offers an insight into bone thermal behavior, informing innovative cutting techniques that reduce cellular thermal damage.
Agent-Based Modeling Traction Force Mediated Compaction of Cell-Populated Collagen Gels Using Physically Realistic Fibril Mechanics
Authors: Reinhardt James W. , Gooch Keith J.
Published: December 2013

Agent-based modeling was used to model collagen fibrils, composed of a string of nodes serially connected by links that act as Hookean springs. Bending mechanics are implemented as torsional springs that act upon each set of three serially connected nodes as a linear function of angular deflection about the central node. These fibrils were evaluated under conditions that simulated axial extension, simple three-point bending and an end-loaded cantilever. The deformation of fibrils under axial loading varied <0.001% from the analytical solution for linearly elastic fibrils. For fibrils between 100 μm and 200 μm in length experiencing small deflections, differences between simulated deflections and their analytical solutions were <1% for fibrils experiencing three-point bending and <7% for fibrils experiencing cantilever bending. When these new rules for fibril mechanics were introduced into a model that allowed for cross-linking of fibrils to form a network and the application of cell traction force, the fibrous network underwent macroscopic compaction and aligned between cells. Further, fibril density increased between cells to a greater extent than that observed macroscopically and appeared similar to matrical tracks that have been observed experimentally in cell-populated collagen gels. This behavior is consistent with observations in previous versions of the model that did not allow for the physically realistic simulation of fibril mechanics. The significance of the torsional spring constant value was then explored to determine its impact on remodeling of the simulated fibrous network. Although a stronger torsional spring constant reduced the degree of quantitative remodeling that occurred, the inclusion of torsional springs in the model was not necessary for the model to reproduce key qualitative aspects of remodeling, indicating that the presence of Hookean springs is essential for this behavior. These results suggest that traction force mediated matrix remodeling may be a robust phenomenon not limited to fibrils with a precise set of material properties.
Parametric Instability in a Taut String With a Periodically Moving Boundary
Authors: Wu K. , Zhu W. D.
Published: December 2013

Parametric instability in a taut string with a periodically moving boundary, which is governed by a one-dimensional wave equation with a periodically varying domain, is investigated. Parametric instability usually occurs when coefficients in governing differential equations of a system periodically vary, and the system is said to be parametrically excited. Since the governing partial differential equation of the string with a periodically moving boundary can be transformed to one with a fixed domain and periodically varying coefficients, the string is parametrically excited and instability caused by the periodically moving boundary is classified as parametric instability. The free linear vibration of a taut string with a constant tension, a fixed boundary, and a periodically moving boundary is studied first. The exact response of the linear model is obtained using the wave or d'Alembert solution. The parametric instability in the string features a bounded displacement and an unbounded vibratory energy, and parametric instability regions in the parameter plane are classified as period-i (i≥1) parametric instability regions, where period-1 parametric instability regions are analytically obtained using the wave solution and the fixed point theory, and period-i (i>1) parametric instability regions are numerically calculated using bifurcation diagrams. If the periodic boundary movement profile of the string satisfies certain condition, only period-1 parametric instability regions exist. However, parametric instability regions with higher period numbers can exist for a general periodic boundary movement profile. Three corresponding nonlinear models that consider coupled transverse and longitudinal vibrations of the string, only the transverse vibration, and coupled transverse and axial vibrations are introduced next. Responses and vibratory energies of the linear and nonlinear models are calculated for both stable and unstable cases using three numerical methods: Galerkin's method, the explicit finite difference method, and the implicit finite difference method; advantages and disadvantages of each method are discussed. Numerical results for the linear model can be verified using the exact wave solution, and those for the nonlinear models are compared with each other since there are no exact solutions for them. It is shown that for parameters in the parametric instability regions of the linear model, the responses and vibratory energies of the nonlinear models are close to those of the linear model, which indicates that the parametric instability in the linear model can also exist in the nonlinear models. The mechanism of the parametric instability is explained in the linear model and through axial strains in the third nonlinear model.
Survival Probability Determination of Nonlinear Oscillators Subject to Evolutionary Stochastic Excitation
Authors: Spanos Pol D. , Kougioumtzoglou Ioannis A.
Published: December 2013

A novel approximate analytical technique for determining the survival probability and first-passage probability density function (PDF) of nonlinear/hysteretic oscillators subject to evolutionary stochastic excitation is developed. Specifically, relying on a stochastic averaging/linearization treatment of the problem, approximate closed form expressions are derived for the oscillator nonstationary marginal, transition, and joint-response amplitude PDFs and, ultimately, for the time-dependent oscillator survival probability. The developed technique exhibits considerable versatility, as it can handle readily cases of oscillators exhibiting complex hysteretic behaviors as well as cases of evolutionary stochastic excitations with time-varying frequency contents. Further, it exhibits notable simplicity since, in essence, it requires only the solution of a first-order nonlinear ordinary differential equation (ODE) for the oscillator nonstationary response variance. Thus, the computational cost involved is kept at a minimum level. The classical hardening Duffing and the versatile Preisach (hysteretic) oscillators are considered in a numerical examples section, in which comparisons with pertinent Monte Carlo simulations data demonstrate the reliability of the proposed technique.
Compact Gravity Driven and Capillary-Sized Thermosyphon Loop for Power Electronics Cooling
Authors: Agostini Francesco , Gradinger Thomas , Cottet Didier
Published: December 2013

A novel two-phase thermosyphon based on automotive technology is presented as a valid solution for the cooling of power-electronic semiconductor modules. A horizontal evaporator configuration is investigated. This solution is based on a 90 deg-shaped thermosyphon that allows an optimal geometrical arrangement of the cooler with limited volume occupancy, reduced air pressure drop, and weight as well as optimal thermal performance compared with standard heat-sink technology. The 90 deg-shape refers to the mutual arrangement of the evaporator body and the condenser, which are in a horizontal and vertical position, respectively. The evaporator cools three power modules with a total power loss between 500 and 1500 W. Experimental results are presented for inlet air temperatures ranging from 20 to 50 °C and for different air volume flow rates between 200 and 400 m3/h. The working fluid is refrigerant R245fa. The maximum thermal resistance (cooler base to air) attained values between 40 and 50 K/kW.
Extension of the Combustion Stability Range in Dry Low NOx Lean Premixed Gas Turbine Combustor Using a Fuel Rich Annular Pilot Burner
Authors: Rosentsvit L. , Levy Y. , Erenburg V. , Sherbaum V. , Ovcharenko V. , Chudnovsky B. , Herszage A. , Talanker A.
Published: December 2013

The present work is concerned with improving combustion stability in lean premixed (LP) gas turbine combustors by injecting free radicals into the combustion zone. The work is a joint experimental and numerical effort aimed at investigating the feasibility of incorporating a circumferential pilot combustor, which operates under rich conditions and directs its radicals enriched exhaust gases into the main combustion zone as the means for stabilization. The investigation includes the development of a chemical reactors network (CRN) model that is based on perfectly stirred reactors modules and on preliminary CFD analysis as well as on testing the method on an experimental model under laboratory conditions. The study is based on the hypothesis that under lean combustion conditions, combustion instability is linked to local extinctions of the flame and consequently, there is a direct correlation between the limiting conditions affecting combustion instability and the lean blowout (LBO) limit of the flame. The experimental results demonstrated the potential reduction of the combustion chamber's LBO limit while maintaining overall NOx emission concentration values within the typical range of low NOx burners and its delicate dependence on the equivalence ratio of the ring pilot flame. A similar result was revealed through the developed CHEMKIN-PRO CRN model that was applied to find the LBO limits of the combined pilot burner and main combustor system, while monitoring the associated emissions. Hence, both the CRN model, and the experimental results, indicate that the radicals enriched ring jet is effective at stabilizing the LP flame, while keeping the NOx emission level within the characteristic range of low NOx combustors.
The Flat Plate Fin of Constant Thickness, Straight Base, and Symmetrical Shape
Authors: Rivera-Alvarez Alejandro , Ordonez Juan C.
Published: December 2013

A plate fin is an extended surface made from a plate. Classical longitudinal and radial fins are particular cases of plate fins with very simple shapes and no curvature. In this paper, the problem of a flat plate fin of constant thickness, straight base, and symmetrical shape given by a proposed power law is considered. Particular attention is paid to some basic shapes: rectangular, triangular, convex parabolic, concave parabolic, convergent trapezoidal, and divergent trapezoidal. One- and two-dimensional analyses are conducted for every shape and comparison of results is carried through the usage of a proposed shape factor. Beyond shape, temperature fields and performance for the considered plate fins are shown to be dependent on a set of three Biot numbers characterizing the ratio between conduction resistances through every direction and convection resistance at the fin surface. Effectiveness and shape factor are found to be hierarchically organized by an including-figure rule. For the rectangular, zero-tip, and convergent trapezoidal cases, effectiveness is limited by a maximum possible value of Bit-1/2, and two-dimensional effects are very small. For the divergent trapezoidal case instead, effectiveness can be larger than Bit-1/2, and one-dimensional over-estimation of the actual heat transfer can be substantially large.
Fluid Pattern and Optimum Design of Sump Based on CFD
Authors: Cheng Li , Liu Chao
Published: December 2013

The open sump is a typical inlet passage for small to middle-sized pumping station. It is important for the efficiency and safe operation of pumps that the open sump has an optimum design. The flow through the sump and into the pump is calculated using CFD. The incompressible N-S equations are solved by the finite volume method. The RNG k-ε turbulence model and the SIMPLEC algorithm for pressure-velocity coupling are used. Many different designs for the open sump are considered, the results of which are compared based on common criteria to evaluate the sump performance. Design values for the width, the depth of submergence and the bellmouth shape are derived.
Taguchi Methodology to Optimize the Design of a MR-Brake With Permanent Magnet
Authors: Erol Ozan , Gurocak Hakan
Published: December 2013

Magnetorheological (MR) brakes provide variable friction torque by electronically changing the viscosity of a magnetic fluid inside the actuator. The MR-brakes have many desirable characteristics, such as high torque-to-volume ratio, inherent stability and ease of control. However, the design process of such an actuator is complex and time consuming due to many parameters involved in the design, including geometric and physical factors and their interactions.

The first contribution of this research is a new optimization approach where we combined the Taguchi optimization method with parameterized magnetic finite element analysis. Unlike other optimization techniques, this method can identify the dominant parameters of the design and investigate their interactions with the design output while reducing the search space and the design time. The second contribution is the design optimization of a novel MR-brake, which incorporates a serpentine flux path and a permanent magnet. To the best of our knowledge, this is the first such MR-brake. The new MR-brake design provides a fail-safe feature while reducing the volume by decreasing the number of coil turns required. Results showed that some of the geometric parameters and the current have the most significant effect on the torque output out of the 12 design parameters.
Dynamic Stability of Axially Moving Plates With Periodically Varying Speeds Under Partially Distributed Edge Tensions
Authors: Young T. H. , Huang S. J. , Liu A. C.
Published: December 2013

This paper investigates the dynamic stability of an axially moving web which translates with periodically varying speeds and is subjected to partially distributed tensions on two opposite edges. The web is modeled as a rectangular plate simply supported at two opposite edges where the tension is applied, and free at the other two edges. The plate is assumed to possess internal damping, which obeys the Kelvin-Voigt model. The moving speed of the plate is expressed as the sum of a constant speed and a periodical perturbation with a zero mean. Due to the periodically varying speed of the moving plate, terms with time-dependent coefficients appear in the equations of motion, which may bring about parametric instability under certain situations. First, the in-plane stresses of the plate due to the partially distributed edge tensions is determined exactly by the theory of plane elasticity. Then, the dependence on the spatial coordinates in the equations of motion is eliminated by the Galerkin method, which results in a set of discretized system equations in time. Finally, the method of multiple scales is utilized to solve this set of system equations analytically if the periodical perturbation of the moving speed is much smaller as compared with the average speed of the plate, from which the stability boundaries of the moving plate are obtained. Numerical results reveal that only combination resonances of the sum-type appear between modes having the same symmetry class in the transverse direction. Unstable regions of main resonances are generally larger than those of sum-type resonances.
A Numerical Simulation Approach for Atmospheric Pollution Evolution at Urban Scale to Help Traffic Control Decision Making
Authors: Basso Davide , Cravero Carlo
Published: December 2013

For a town with complex orography and frequently varying winds, like Genova on the Italian Northern coast, the need for a simulation environment to predict the pollutant evolution according to a given traffic load, would be of utmost importance. A simulation approach based on 3D CFD has been developed keeping in mind the final application: it use for decision making. Several meshes have been set up and their effects on the solution evaluated in order to strike a balance between the quality of physical modelling and the computational resources required to handle it. The aim is that of getting useful results in a short timescale (one/two days). The evolution of the 3D flow and the pollutants has been simulated for two reference days with a time resolution of one hour. The effect of the daily evolution of the wind, heat release and pollution emission (traffic) over 24 hours is highlighted and discussed.
Experimental Analysis of Emulsified Palm Oil Methyl Ester Towards Alternative Diesel Fuel
Authors: Debnath Biplab K. , Sahoo Niranjan , Saha Ujjwal K.
Published: December 2013

Palm oil methyl ester (POME) produced from crude palm oil have some excellent properties which makes it a feasible alternative to diesel fuel. However, its higher oxygen content makes it nitrogen oxide emission prone when burned in diesel engines. This problem can be resolved by emulsifying POME with distilled water in the presence of suitable surfactant. Two phase water in oil emulsion is prepared by using ultrasonic bath sonication. SPAN 80, a lipophilic surfactant is used for 1% by volume to prepare the emulsion. Water quantity in the emulsion is varied by 5% and 10% by volume and stability study is performed. It is found that emulsion with 5% water is more stable. Thereafter, POME emulsion samples are prepared with 5% water and tested in a variable compression ratio diesel engine. The performance and emission characteristics are investigated for a set of loads and compression ratios (CR). The experimental observations show that 5% water in POME produce 3.5% lower brake thermal efficiency and 11% higher brake specific fuel consumption as compared to baseline diesel. Furthermore, the exhaust gas temperature and other emissions like oxides of carbon, oxides of nitrogen and hydrocarbon for the emulsified POME are found to be lower than the baseline diesel.
Heavy Truck 5th Wheel Modeling Techniques in Finite Element and Their Effect on Stress Distribution
Authors: Cinar Ali
Published: December 2013

Finite element analysis has been used widely in the automotive industry to evaluate design alternatives. Especially when there is no prototype part for rig or vehicle testing, CAE (Computer Aided Engineering) is the only tool to evaluate whether the design meets its target or not. Truck chassis, 5th wheel table and its reinforcement has been modeled for stress calculations under 5th wheel forces. Various FE modeling techniques have been evaluated, including assembly loads and contact modeling, and their effect on the stress distribution has been demonstrated. The aim of this paper is to demonstrate the important parameters that effect stress distribution on the critical areas under the 5th wheel.
Non-Linear Observer-Based Control of Flexible-Joint Manipulators Used in Machine Processing
Authors: Qin Jinna , Léonard François , Abba Gabriel
Published: December 2013

This paper proposes to use a non-linear observer to build the state and the external force of flexible manipulator robots during their machining (composite materials) processes or Friction Stir Welding (FSW) processes. These two different processes have a problem in common: the flexibility of the robot can not be neglected, that is to say, the errors due to the deformation of the links should be taken into account. However, in most industrial robots, the real positions and velocities of each link are not measured, so in this study, an observer is proposed to reconstruct the real angular positions and velocities of links by using the measured angular positions and the velocities of actuators. A simulation by Matlab/Simulink has been carried out with a 2 axis Robot during its machining processes: the proposed observer showed great performances in estimating the state of the robot (position and velocity). Then, in order to improve the tracking accuracy in the tool frame, the state of the external force along the forward direction (x) and its normal direction (y) are required, while they are also not measured by our robot. A disturbance observer has been added to reconstruct the processing force. A good precision during the proposed processes have been obtained using the latter. This study contributes to solve the problem from the point of view of accuracies during the machining processes.
Fractal Orifices for Flowmetering
Authors: Nicolleau Franck C. G. A. , Beck Stephen B. M. , Nowakowski Andrzej F.
Published: December 2013

In this article we study the return to axi-symmetry for a flow generated after fractal plates in a circular wind tunnel. We consider two sets of plates: one orifice-like and one perforated-like. The mean velocity profiles are presented at different distances from the plate and we study the convergence of a flow rate based on these profiles. The return to axi-symmetry depends on how far was the original plate from an axi-symmetric design. It also depends on the level of iteration of the fractal pattern. In line with results for other flow properties [1, 2] It seems that there is not much to be gained by manufacturing fractal plates with more than three iteration levels.
Numerical Simulation on the Flow Pattern in Forebay of Pumping Station
Authors: Liu Chao , Lu Meining
Published: December 2013

Based on FLUENT software, the standard k–ε turbulence model is adopted to simulate 3D-flow field in the forebay of a combined sluice-pump station. Flow field of the diffusion channel and suction passage is obtained after numerical simulation. Results show that flow in the fore-bay appears side-direction and vortexes exist in it and inlet of the suction passage. According to the results, optimum measures such as changing the wing wall form, extending the sluice pier, adding tri-prisms are conducted on the basis of original design. The vortexes are eliminated finally. Flow in diffusion channel appears front inflow and is improved effectively.
Model Order Reduction for Stochastic Optimal Control
Authors: Nguyen Ngoc-Hien , Willcox Karen , Khoo Boo Cheong
Published: December 2013

This work presents an approach to solve stochastic optimal control problems in the application of flow quality management in reservoir systems. These applications are challenging because they require real-time decision-making in the presence of uncertainties such as wind velocity. These uncertainties must be accounted for as stochastic variables in the mathematical model. In addition, computational costs and storage requirements increase rapidly due to the stochastic nature of the simulations and optimisation formulations. To overcome these challenges, an approach is developed that uses the combination of a reduced-order model and an adjoint-based method to compute the optimal solution rapidly. The system is modelled by a system of stochastic partial differential equations. The finite element method together with collocation in the stochastic space provide an approximate numerical solution—the “full model”, which cannot be solved in real-time. The proper orthogonal decomposition and Galerkin projection technique are applied to obtain a reduced-order model that approximates the full model. The conjugate-gradient method with Armijo line-search is then employed to find the solution of the optimal control problem under the uncertainty of input parameters. Numerical results show that the stochastic control yields solutions that are above the bound of the set solutions of the deterministic control. Applying the reduced model to the stochastic optimal control problem yields a speed-up in computational time by a factor of about 80 with acceptable accuracy in comparison with the full model. Application of the optimal control strategy shows the potential effectiveness of this computational modeling approach for managing flow quality.
Modeling and Control of Flexible Second Order Systems With Damped Boundaries
Authors: Sirota Lea , Halevi Yoram
Published: December 2013

This paper considers the problem of modeling and control of non-conservative flexible systems, whose dynamics is described by the wave equation. Classical modal analysis failed so far when the boundaries included dampers. A new insight into the problem was obtained by infinite dimension transfer functions models, developed in previous works. Their special structure, consisting of delays and low order rational terms lead to the time domain interpretation of traveling waves. In this paper the Laplace modeling approach is used to represent the solution in a modal like fashion, i.e. an infinite sum of products of spatial and temporal functions. While this form is closely related to standing waves, it was shown to lead also to a traveling wave representation. The response is then used to investigate the behavior of the system under control with the absolute vibration suppression (AVS) controller, which was originally designed for tracking control. It is shown that the vibration suppression properties of this controller apply also to nonzero initial conditions.
Minimum Energy Control of Redundant Cartesian Manipulators
Authors: Halevi Yoram , Carpanzano Emanuele , Montalbano Giuseppe
Published: December 2013

In redundant manipulation systems the end-effector path does not completely determine the trajectories of all the individual degrees of freedom (dof). The redundancy is used in this paper to minimize energy consumption. A full electromechanical model is used, and the invested energy is calculated explicitly. The optimization includes also displacement limits via penalty functions that are included in the cost function. The solution is based on separating the system and the input into two parts. One that is completely determined by the end-effector path and the other that is driven by it, yet free for optimization. The boundary conditions are resolved in a similar manner, where the physical values are translated to the scaled down system by using a specific projection. Simulation results show that even with limited joint motion, the redundancy can lead to a considerable saving in energy.
Verification of a Finite Element Model of an Unmanned Aerial Vehicle Wing Torque Box via Experimental Modal Testing
Authors: Unlusoy Levent , Sahin Melin , Yaman Yavuz
Published: December 2013

In this study, the detailed finite element model (FEM) of an unmanned aerial vehicle wing torque box was verified by the experimental modal testing. During the computational studies the free-free boundary conditions were used and the natural frequencies and mode-shapes of the structure were obtained by using the MSC® Software. The results were then compared with the experimentally obtained resonance frequencies and mode-shapes. It was observed that the frequencies were in close agreement having an error within the range of 1.5–3.6%.
Experimental Analysis of Ring Stiffnesses of Pipes, Made of High Density Polyethylene, due to DIN 16961-2:2010-03 Standard
Authors: Palabiyik I. Mehmet , Yavuz A. Orhan , Gemici Zafer , Gökgöz Isminur
Published: December 2013

The parallel plate load test is used to measure “pipe stiffness” for HDPE pipe. Pipe stiffness is employed as a measure of pipe resistance to bending deformation as well as a quality control index for the manufacturing process. This work presents the results of a series of parallel plate tests conducted on profiled HDPE plastic pipes to determine ring stiffness values. During the study, all pipe samples were tested according to the DIN 16961 2:2010-03 standard. The nominal inside diameters of the test pipes were selected 500 and 600mm. These pipes compressed radially a constant load during 24 hours and deflection were measured by a comparator. Then experimental ring stiffness values were calculated by using these data.
Numerical Simulation of Well Trajectory While Drilling Isotropic and Anisotropic Formations
Authors: Tikhonov Vadim , Valiullin Khaydar , Ring Lev
Published: December 2013

In spite of research efforts to develop a numerical model for predicting wellbore trajectory, there isn’t an adequate model for simulating new hole creation and predicting wellbore curvature and build rates that accounts for bottomhole assembly (BHA) dynamics, geometric constraints, rock properties, and steering tool action.

This paper presents new, comprehensive 3D model of BHA dynamics for lateral and torsional modes of motion. This model includes the presence of stabilizers and sections with different geometric and mechanical properties along the BHA. It considers changes in trajectory due to action of bent subs or rotary steerable systems (RSS); allows for abrupt changes to friction factors during transitions from sliding to rolling motions in the wellbore; and accounts for the effects of the bit’s side-milling capacity and side load changes due to changes in the formation.

The DYNTUB software, an advanced simulation tool for predicting well trajectories while drilling, was developed based on this model. This paper presents a mathematical model for the BHA and the well trajectory, the numerical integration method, and the results calculated for various examples steering tools and formations.
A Comparison of Intelligent PID Position Controllers With Autotuners for a Pneumatic System
Authors: Dehghan Behrad , Surgenor Brian W.
Published: December 2013

This paper reports on a study whose objective is to explore the potential of intelligent algorithms such as fuzzy rules and neural networks (NN) as applied to the control of pneumatic servosystems. Current application is position control of a pneumatic gantry robot. Preliminary experiments with adaptive fuzzy and NN controllers showed improvement in tracking performance by upwards of 70%. This level of improvement was expected given the adaptive nature of both controllers. However, both methods also required significant effort to setup. An on-line autotuner was developed to improve the ease of implementation. Comparative results are given for five controllers: 1) manually tuned PID, 2) autotuned PID, 3) adaptive NN PID, 4) fuzzy adaptive PID and 5) autotuned fuzzy adaptive PID. Experiments were conducted at 2 different supply pressures and 3 different tracking frequencies. Once again the fuzzy adaptive PID controller improved performance over fixed gain PID, this time by upwards of 80%, even when both were given the benefit of autotuning.
Electro-Magneto-Fluid-Structural Coupling Problem: The Vibrating Viscometer
Authors: Badiane Doudou , Gasser Alain , Blond Eric , Bellière Luc , Vancayzeele Kevin
Published: December 2013

This study presents a viscosity sensor that converts the vibration amplitude at the resonance frequency of a needle immersed in viscous fluid, into electric current. The goal of this work is to provide a dedicated numerical tool for the sensor design, that couples fluid, structure and magnetism.
Dynamic Analysis of a Bladed Balance Ring Device
Authors: Urbiola-Soto Leonardo , Lopez-Parra Marcelo , Cuenca-Jimenez Francisco
Published: December 2013

Among the solutions to the rotor unbalance problem, the previous art shows the use of passive balancers. The liquid balance ring fall in this category, which basically consists of a hollow ring equipped with a number of anti-sloshing baffle boards inside the cavity. The liquid contained within the ring adopts an antagonist position to the unbalance, thus balancing the rotor. Nowadays, in regard to the shape of the baffles boards employed in liquid balance ring devices, the use of straight baffles is the standard practice. However, as the fluid is subjected to rotation, it makes sense to believe that there should be a better baffle shape to enhance the fluid-solid interaction and improve the balance ring dynamic performance. This research work introduces for the first time a balance ring with curved (forward and backward) blades that remarkably enhance the unbalance response of rotors in the transient and steady-state. A classical dynamics model of this novel bladed concept is introduced and employed in designing a liquid balance ring for high-speed performance. Experimental data showing good correlation between the model and tests is presented.
Numerical Simulation of the Cold Spray Deposition Process for Aluminium and Copper
Authors: Xie Jing , Nelias Daniel , Walter-le Berre Hélène , Ichikawa Yuji , Ogawa Kazuhiro
Published: December 2013

Cold spray is a rapidly developing coating technology for depositing materials in the solid state. In this deposition process, the spray particles are accelerated to a high velocity by a high-speed gas flow, and then form a dense and high quality coating due to plastic deformation of particles impinged upon the solid surface of substrate. 2D and 3D modelling of particle impacting behaviours in cold spray deposition process by using ABAQUS/Explicit was conducted for four couples of materials (i.e. impacting particle/impacted substrate): copper/aluminium, aluminium/copper, copper/copper, and aluminium/aluminium. A systematic analysis of a single impact was carried out considering different parameters, such as the initial impact velocity, initial temperature and contact angle, which affect the deposition process and subsequently the mechanical properties of coating. Three numerical methods have been evaluated and their performances are discussed for various simulation settings: (i) modelling in a Lagrangian reference frame; (ii) modelling using adaptive remeshing in an Arbitrary Lagrangian Eulerian (ALE) reference frame; and (iii), modelling in a CEL reference frame. It is found that the Coupled Eulerian Lagrangian (CEL) method has more advantages to simulate the large deformation of materials, and is also more efficient to prevent the excessive distortion of the mesh. A comparison between simulation results and experimental data from the literature was performed. Nevertheless, the CEL method is implicitly isothermal for ABAQUS v6.10, whereas the modelling in the classical Lagrangian reference frame does include coupled thermo-mechanical effects with a local increase of the temperature near the interface — due to friction — and for the highly plastically deformed elements — due to the heat dissipation linked to plasticity. A local rise of temperature at the impact surface may also be observed for oblique impacts. Finally a first attempt to simulate the deposition of several particles is made with a 3D CEL model, resulting in the creation of porosity at the interface between particles.
Influence of Elevator Moving Pattern on the Contaminant Exclusion for an LCD Panel Delivery Facility
Authors: Lin Sheam-Chyun , Chang Cheng-Ju , Shih Hsien-Chang , Huang You-Min , Chen Chao-Chang , Luo Yu-Shan
Published: December 2013

Because of the increasing panel size, the difficulty on delivering the glass substrate has been enhanced dramatically and become a critical problem in the LCD manufacturing industry. Nowadays, most of panel fabrication factory utilize the fully-automated delivering technology instead of the traditional labor delivery for diminishing the possibility of polluted particles on the LCD board. Thus, this study investigates the flow patterns on maintaining the air quality inside the delivering facility with a moving elevator. Also, influence on the moving pattern of the elevator via numerical technique is the focus of this investigation. Firstly, CFD code Fluent is used to execute the CFD simulation and evaluate the flow patterns inside this delivery equipment. It is found that the inferior air is generated mainly by the increasing vortex inside the delivery equipment for an upward-moving elevator. On the contrary, the flow field becomes very smooth without obvious vortex phenomenon, and thus induces a better air quality when the elevator moves downward. However, a better uniform flow field occurred when the elevator is moving upward. In addition, the airflow uniformity is not effectively improved by reducing the elevator velocity and increasing the FFU airflow velocity. It is not evident for improving the pollute exclusion by reducing elevator moving velocity which slows down the transporting efficiency, so it is suggested that the moving speed of elevator should maintain at 0.16m/s. On another way, it is useful to enhance the capability of pollute exclusion by increasing the FFU’s air velocity, thus it is proposed to raise FFU velocity to 0.71m/s. Consequently, it is concluded that the moving pattern of elevator has an essential impact and can be utilized to improve the air quality inside the LCD delivery facility.
Effect of Plastic Anisotropy on the Collapse Load and the Distribution of Residual Stresses and Strains in a Thin Disk Subject to Thermo-Mechanical Loading
Authors: Alexandrov Sergei
Published: December 2013

Thin plates and disks with holes and embedded inclusions have many structural applications. Existing plane stress solutions for thin plates and disks have shown several qualitative features which are difficult to handle with the use of commercial numerical codes (non-existence of solutions, singular solutions, rapid growth of the plastic zone with a loading parameter). Moreover, elastic- and rigid-plastic solutions at the stage of loading are sensitive to the magnitude of material and process parameters. The distribution of residual stresses and strains after unloading is even more sensitive to these parameters. The present paper provides a semi-analytical solution for plastically anisotropic hollow disk loaded by pressure over its inner radius. The disk is also subject to thermal loading by a uniform temperature field.
Analysis on the Temperature Rise Produced by Plastic Deformation Heat for Nanoscale Orthogonal Cutting of Copper Workpiece
Authors: Lin Zone-Ching , Hsu Ying-Chih , Chen Liang-Kuang
Published: December 2013

The quasi-steady molecular statics nanoscale orthogonal cutting model developed by this paper not only can calculate cutting force, equivalent stress and equivalent strain, but also can calculate the temperature rise of the cut perfect crystal copper workpiece. This paper considers that during nanoscale orthogonal cutting, the temperature rise of the cut perfect crystal copper workpiece is produced by plastic deformation heat only. The calculation method of equivalent stress and equivalent strain uses three-dimensional quasi-steady molecular statics nanocutting model to calculate and simulate the phenomenon. The model for plastic deformation heat developed by this paper can be used to calculate the equivalent stress and equivalent strain of the cut copper workpiece. Furthermore, the calculation method of temperature rise of the cut workpiece produced by plastic deformation heat is developed. Afterwards the analysis of temperature distribution is also conducted. And the obtained temperature distribution of the cut copper workpiece computed by this paper is qualitatively compared with the temperature distribution obtained by molecular dynamics method in the reference.