bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linear and Geometrically Nonlinear Behavior of Metal/Polysilicon Plate Microstructures Subjected to Temperature Changes
Authors: Dunn Martin L. , Zhang Yanhang , Bright Victor M. 
Published: November 2021

Abstract
We study the deformation behavior of a series of gold/polysilicon MEMS plate structures fabricated by the MUMPS surface micromachining process and subjected to uniform temperature changes from 100°C to room temperature. We measured, using an interferometric microscope, full-field deformed shapes of a series of square (L×L) gold (0.5 μm thick)/polysilicon (1.5 μm thick) plate structures of sizes ranging from L = 150 μm to L = 300 μm. In general, we observed three regimes of deformation as characterized by the average curvature as a function of temperature change: i) linear thermoelastic response independent of plate size, ii) geometrically nonlinear thermoelastic response that depends on plate size, and iii) bifurcations in the curvature-temperature response that also depend on plate size. We modeled the deformation response both analytically and with the finite element method. Good qualitative and quantitative agreement was obtained between predictions and measurements in all three deformation regimes. Good agreement was also obtained between measurements and predictions of the spatial nonuniformity of the curvature across the plate.
Three-Dimensional Silicone Device Fabrication and Interconnection Scheme for Microfluidic Applications Using Sacrificial Wax Layers
Authors: Dharmatilleke Saman , Henderson H. Thurman 
Published: November 2021

Abstract
A simple room-temperature procedure is reported herein for formation of true three-dimensionality of “microfluidic components” and complete microfluidic systems in silicone elastomer, this is achieved by molding the plastic to simply encapsulate a pre-formed network of sacrificial wax threads or other connected wax configurations which are ultimately to become micro channels, microfluidic components and cavities in the plastic motherboard. When these wax sacrificial areas are etched away with acetone, precise cavities, channels, and capillaries result with direct arbitrary three-dimensionality. This method leads also to a simple and effective external interconnection scheme where ordinary fused silica tubes may be press-fitted into the surface opening to withstand high pressure. An array of micro channels having circular cross sections with diameters of 100, 150 and 200 microns, membrane type valves, pinch valves, mixing chambers and reservoirs for fluid storage were molded in silicone elastomer using wax filaments. The wax filaments were dissolved in acetone after the silicone elastomer became hardened, leaving the micro channels, valves, mixing chambers and reservoirs in the silicone elastomer. This scheme gives the flexibility of allowing multi stacks of components (motherboards) while being able to control the channel lengths within the stacks as desired.
Micro-to-Macro Fluidic Interconnectors With an Integrated Polymer Sealant
Authors: Tsai Jr-Hung , Lin Liwei 
Published: November 2021

Abstract
Micro-to-macro fluidic interconnectors with integrated polymer sealants have been successfully demonstrated. Two types of sealing processes, discrete and integrated, have been developed as the post fabrication processes to build interconnectors for microfluidic systems. In the demonstrating examples, capillary tubes of 320μm in outer diameter have been connected to a microfluidic system with microchannels of 100μm wide, 20μm deep and 800μm long by using Mylar (a polyester film by DuPont) as the sealant. The interconnection was completed on fluidic ports of 350μm in diameter. Both leakage and pull-out tests have been conducted to prove functionalities and to characterize performances of the interconnectors. The pressure test result indicates that no leakage is observed up to 190KPa. The pull-out test results show 100% survival rate under a 2 Newton pulling force.
Characterization of a MEMS-Fabricated Mixing Device
Authors: Lee Yi-Kuen , Tabeling Patrick , Shih Chiang , Ho Chih-Ming 
Published: November 2021

Abstract
This paper discusses the fabrication and the characterization of a MEMS-based micromixer. Active perturbations provided by a pressure source/sink system are used to enhance the mixing between two fluid streams. From our preliminary test, it appears that an effective mixing is possible through the generation of chaotic-like distortions at the interface between two streams. A numerical simulation based on a kinematical model reveals a similar behavior under the same condition.
Key Reliability Factors for IC and MEMS Packaging
Authors: Ghaffarian Reza 
Published: November 2021

Abstract
During the last decade, research and development of microelectromechanical systems (MEMS) has shown a significant promise for a variety of commercial applications including automobile and medical purposes. For example, accelerometers are widely used for air bag in automobile and pressure sensors for various industrial applications. Some of the MEMS devices have potential to become the commercial-off-the-shelf (COTS) components. While high reliability/harsh environmental applications including aerospace require much more sophisticated technology development, they would achieve significant cost savings if they could utilize COTS components in their systems.
This paper reviews the current status of IC and MEMS packaging technology with emphasis on reliability, compares the norm for IC packaging reliability evaluation and identifies challenges for development of reliability methodologies for MEMS, and finally proposes the use of COTS MEMS in order to start generating statistically meaningful reliability data as a vehicle for future standardization of reliability test methodology for MEMS packaging.
The Influences of the Material Properties on Ceramic Micro-Stereolithography
Authors: Sun Cheng , Zhang Xiang 
Published: November 2021

Abstract
Micro-stereolithography (μSL) was recently introduced in the fabrication of complex 3D ceramic microstructures. Light scattering is found to be the key factor influencing the micro-stereolithography of ceramics. In this work, numerical simulation based on the Monte-Carlo ray tracing method has been developed to investigate the influences of the important materials properties on the ceramic micro-stereolithography. It is found that the scattering are strongest when size of the ceramic powders approaches to the laser wavelength (0.3 μm). It also found that the higher the refractive index contrast between the particle and the solution, the stronger the light scattering. High laser intensity is required to fabricate high UV absorption ceramic materials to compensate the laser energy absorbed by the ceramic particle. μSL from three typical ceramic powders are examined by numerical model. The numerical model have been demonstrated as an efficient tool to optimize the micro-stereolithography process.
Cellular Automaton Approach on Micro Solidification Process of Two Phase Alloy in Horizontal Casting
Authors: Tsuta Toshio , Iwamoto Takeshi 
Published: November 2021

Abstract
A mathematical model of micro morphology generation in solidification process has been developed using cellular automaton approach, and heterogeneous nucleations from the wall and the grain growth kinetics are simulated by using the Monte-Carlo simulation. In the next place, the change in the micro morphology from the dendritic to the equiaxial, has been analyzed in the same way, under the condition that the liquid metal in the vessel is excited from magnetic stirrer. The results are compared with those obtained by the experiments on horizontal, continuous casting and the applicability of the method has been verified.
A Closed Loop Full-Scale Automotive Climatic Wind Tunnel for Vehicle Environment Simulation
Authors: Abdul Ghani S. A. A. , Aroussi A. , Rice E. 
Published: November 2021

Abstract
This paper describes the simulation of vehicle natural climatic environment in a closed loop full-scale automotive climatic wind tunnel. The tunnel simulates wind, rain, and temperature for several road conditions. It generates under controlled heat loading, wind speeds of up to 50kph with different approach boundary conditions, rainfalls from drizzle to cloudburst and road inclines up to 15° in any direction. The design and optimization process of the tunnel functions is outlined and examples of its use in vehicle development are given. The size constraint and the need for a compact design are important features of the tunnel. The tunnel provides an important test bed for close scrutiny of the relationship between rain ingress, vehicle speed, road condition, heat loading and vehicle geometry. The tunnel can also be used to study vehicle thermal management, vehicle thermal comfort, engine cold starting, and wipers efficiency in severe cold weather. Computational Fluid Dynamic (CFD) simulation is used to optimize and asses the performance of a number of key tunnel components. The resulting tunnel is approximately 9.5m in length, 9.5 m in height and 3 m in width.
Challenges in Controlling Active Suspensions for High-Speed Off-Road Vehicles
Authors: Efatpenah Keyanoush , Beno Joseph H. , Nichols Steven P. , Longoria Raul G. 
Published: November 2021

Abstract
The literature includes several useful control approaches for active suspension of off-road vehicles. Some of these approaches rely on preview (look-ahead) of the terrain, while others require knowledge of certain variables that have proven difficult to measure reliably for off-road applications. Sky-hook damping is a widely accepted active suspension control law.
Experimental and analytical research with active suspension systems for on- and off-road vehicles have successfully demonstrated substantial improvement in ride quality. The paper begins with a short discussion of a bond graph model of an off-road vehicle equipped with an electromechanical active suspension. The bond graph model facilitated the development of a SIMULINK model used for simulation. Comparison of simulation and experimental results has validated the model, especially for high-frequency terrain inputs. The paper examines how specific examples of off-road conditions challenge control algorithm development. Simulations demonstrate that sky-hook damping (without modification) with gains selected for very high attenuation of high-frequency terrain disturbances do not perform well in response to large displacement, low-frequency inputs and cause suspension bottoming out. By modifying the basic control laws and selecting appropriate controller gains, excellent ride performance was achieved in recent field tests under general terrain conditions.
Effects of Process Conditions on Shrinkage and Warpage: Experiments and Simulations
Authors: Wang James T. , Yoon C. K. 
Published: November 2021

Abstract
In the injection mold process, a pressure gradient exists from the polymer entrance to the last-fill location. At different planar locations of a part, when the polymer melt cools down to the transition temperature and freezes (changes from liquid to solid) at different pressures, shrinkage at the various locations will be different. If cooling channels are not arranged properly, the mold wall temperatures on the cavity and core sides can be different. This unbalanced cooling can also cause the melt at the upper and lower halves of the cavity to shrink differently, because they freeze at different times and different pressures. These two types of non-uniform shrinkage will cause parts to warp.
Reducing shrinkage and warpage is one of the top priorities for improving the quality of injection molded parts. In addition to part design and material properties, process conditions are the most important determinants of part quality. In this paper, the relationship between process conditions and in-cavity residual stress will be studied. In-cavity residual stress is the driving force that causes parts to deform after they are taken out of the mold. The effects of process conditions on injection-molded part quality (in terms of shrinkage and warpage) will be discussed. Different packing pressure levels, together with unbalanced cooling from mold wall temperatures, will be examined. Deformation of injection molded parts will be measured. Comparisons between experimental and numerical simulation results will be reported.
Macro Modeling of Reactive Infiltration Using Level Set Finite Element Formulations
Authors: Balagangadhar Dinesh , Rajesh Gopalaswamy 
Published: November 2021

Abstract
The process of reactive melt infiltration can be used to fabricate ceramics and ceramic matrix composites. This process involves a liquid metal being allowed to infiltrate a medium with which the liquid reacts to form a resultant ‘matrix’ along with the already present reinforcing fibers. The authors’ previous work on this area revealed that the transient porosity and permeability of a porous medium can be determined for certain geometries from the reaction kinetics and coupled heat and mass transfer problem occurring at the pore level. But the formulation at the macro level, which is essential to optimize the process, has been limited. Towards this end, this paper solves the macro reactive flow problem in a porous medium analytically as well as numerically. The focus of this article will be on the solutions for the advance (displacement) of the ‘infiltration front’ with progressive chemical reaction occurring between the medium and the infiltrant. A finite element formulation is used to solve the problem computationally; a level set formulation is used to track the infiltration front during the process. Excellent agreement is obtained between the analytical and computational solutions thereby validating the level set finite element formulations.
On the Equivalence of the Stress and Displacement Methods in Planar Anisotropic Elasticity
Authors: Gao Xin-Lin , Rowlands Robert E. 
Published: November 2021

Abstract
The stress formalism of Lekhnitskii and the displacement formalism of Eshelby, Read and Shockley (ERS) are firstly recapitulated and compared for problems of planar anisotropic elasticity. It is explicitly demonstrated that for such problems the two formalisms lead to the identical characteristic equation and thus are equivalent. An alternative displacement formulation method is then presented for the same problems using an extended version of Green’s theorem. This approach introduces a displacement function, which satisfies a fourth-order partial differential equation whose characteristic equation is identical with that obtained using the methods of Lekhnitskii and ERS. The new approach is proved to be equivalent to those of Lekhnitskii and ERS for problems of planar anisotropic elasticity. The present displacement function method exhibits similarities with the Airy stress function method.
Heat Transfer Enhancement by Turbulent Impinging Jets
Authors: Kumagai M. , Amano R. S. , Jensen M. K. 
Published: November 2021

Abstract
A numerical and experimental investigation on cooling of a solid surface was performed by studying the behavior of an impinging jet onto a fixed flat target. The local heat transfer coefficient distributions on a plate with a constant heat flux were computationally investigated with a normally impinging axisymmetric jet for nozzle diameter of 4.6mm at H/d = 4 and 10, with the Reynolds numbers of 10,000 and 40,000. The two-dimensional cylindrical Navier-Stokes equations were solved using a two-equation k-ε turbulence model. The finite-volume differencing scheme was used to solve the thermal and flow fields. The predicted heat transfer coefficients were compared with experimental measurements. A universal function based on the wave equation was developed and applied to the heat transfer model to improve calculated local heat transfer coefficients for short nozzle-to-plate distance (H/d = 4). The differences between H/d = 4 and 10 due to the correlation among heat transfer coefficient, kinetic energy and pressure were investigated for the impingement region. Predictions by the present model show good agreement with the experimental data.
Dimensionless Parameters for the Optimization of Annular-Finned Tubes
Authors: Cortés Cristóbal , Arauzo Inmaculada , Campo Antonio 
Published: November 2021

Abstract
This paper addresses the problem of optimizing an array of annular fins starting from an empirical fit of the average convection coefficient that recognizes the influence of the fin spacing. A dimensionless formulation is proposed to reduce the number of independent parameters to only four, being applicable to a rather generic situation. The formulation is illustrated with a parametric study encompassing the ranges of interest of the variables: Reynolds number, thermal conductivity ratio, volume constraint and fin spacing and thickness. Applied to the standard designs of annular-finned heat exchangers, the method predicts fully coherent points of optimum thermal performance. A sequence is suggested to integrate the optimization process within the design calculations of heat exchangers, and several graphs are presented which are suitable to this purpose. The method can be applied to the design and scaling calculations of annular-finned tube bundles for gas-liquid or gas-gas applications.
Eight-Ton Advanced GAX Cycle Prototype Results
Authors: Anand G. , Erickson Donald C. 
Published: November 2021

Abstract
The advanced Vapor eXchange Generator Absorber heat eXchange (VX GAX) cycle has similar components as the basic GAX cycle but is a three-pressure cycle and makes more complete use of the GAX temperature overlap. Less external heat is supplied to the generator, and the cycle efficiency is increased.
A breadboard prototype of a gas-fired heat pump using the VX GAX cycle has been developed and tested. A higher COP was achieved using reliable and cost effective components.
This paper presents the VX GAX cycle breadboard design concept, the hardware realization, and the performance achieved. Several novel concepts were incorporated to achieve the design objectives of higher efficiency and capacity, lower cost, compactness, avoidance of code restrictions, and operability from 49°C (120°F) summer to −8°C (17°F) winter ambient conditions.
The prototype results have confirmed the high performance capability of the advanced GAX cycle. At 35°C (95°F) ambient air-cooled conditions, a gas-cooling COP of 0.85 was achieved at design capacity. This is a 20% improvement relative to current basic GAX chillers. The eight-ton capacity is ideal for small-scale commercial applications and provides economy of scale. The wide ambient operating range is key to year-round operation and attractive payback in all climate zones. The demonstrated improvement in both system performance and cost is key to achieving nationwide mass-market status.
The Role of Surfactant Adsorption Rate in Heat and Mass Transfer Enhancement in Absorption Heat Pumps
Authors: Koenig Michael S. , Grossman Gershon , Gommed Khaled 
Published: November 2021

Abstract
The importance of heat and mass transfer additives in absorption chillers and heat pumps has been recognized for over three decades. However, a universally accepted model for the mechanisms responsible for enhanced absorption rates has yet to be proposed. The Marangoni effect — an instability arising from gradients in surface tension at the liquid-vapor interface — is generally accepted as the cause of the convective flows that enhance transfer rates. Certain surfactant additives can significantly improve absorption rates and thus reduce the overall transfer area required by a given machine. Any means available that can increase the efficiency and acceptability of absorption machines is to be welcomed, as this technology provides an alternative to vapor compression systems which is both environmentally friendly and more versatile with regards to energy sources.
This study investigates the rate at which a surfactant additive adsorbs at a liquid-vapor interface. The residence time of the falling liquid solution in an absorber is quite short. An effective additive must not only reduce the surface tension of the solution; it must do so quickly enough to cause the Marangoni instability within the short absorption process time. The entrance region of an absorber features a freshly exposed interface at which no surfactant has adsorbed.
A numerical model is used to analyze surfactant relaxation rates in a static film of additive-laced solution. Kinetic parameters for the combination of the working pair LiBr-H2O and the additive 2-ethyl-1-hexanol are derived from data in the literature for static and dynamic surface tension measurements. Bulk, interfacial and boundary parameters influencing relaxation rates are discussed for surfactant adsorption occurring in the absence of absorption, as well as for concurrent adsorption and stable vapor absorption. Initial solution conditions and absorption driving force are shown to impact the potential for instability in the effect they have on the rate of interfacial additive adsorption.
Exhaust Energy Recovery for Control of a Homogeneous Charge Compression Ignition Engine
Authors: Martinez-Frias Joel , Aceves Salvador M. , Flowers Daniel , Smith J. Ray , Dibble Robert 
Published: November 2021

Abstract
This work investigates a purely thermal control system for HCCI engines, where thermal energy from exhaust gas recirculation (EGR) and compression work in the supercharger are either recycled or rejected as needed. HCCI engine operation is analyzed with a detailed chemical kinetics code, HCT (Hydrodynamics, Chemistry and Transport), which has been extensively modified for application to engines. HCT is linked to an optimizer that determines the operating conditions that result in maximum brake thermal efficiency, while meeting the restrictions of low NOx and peak cylinder pressure. The results show the values of the operating conditions that yield optimum efficiency as a function of torque for a constant engine speed (1800 rpm). For zero torque (idle), the optimizer determines operating conditions that result in minimum fuel consumption. The optimizer is also used for determining the maximum torque that can be obtained within the operating restrictions of NOx and peak cylinder pressure. The results show that a thermally controlled HCCI engine can successfully operate over a wide range of conditions at high efficiency and low emissions.
An Investigation Into the Drying of Distribution Transformers Using the Hot Air Vacuum Method
Authors: Gopalan R. , Al-Jumaily A. M. , Leece P. 
Published: November 2021

Abstract
A hot air vacuum method with considerable difference in design and constructional features as compared with the conventional process of a normal convection oven has been built and operated for drying transformers up to 1000 kVA, 33 kV. Moisture-equilibrium charts for kraft paper were used for designing the drying system. A high temperature air circulation fan placed inside the vacuum chamber simplified the construction and using air ducts directed at the transformer inside the autoclave improved the heat transfer capability and reduced the heating time for the transformer. A dry vacuum pump used for moisture removal eliminated the need for condensing water vapour before exhausting it into the atmosphere. A mathematical model for predicting the heating and vacuum cycle for distribution transformers in the autoclave has been presented with reasonably accurate results. Experimental results give a 1% or less moisture content in the insulation after dryout in about 10–12 hours. This indicates energy savings over a conventional air circulation process of about 70%.