bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solar Thermal Power Technology: Present Status and Ideas for the Future
Authors: Goswami D. Yogi 
Published: November 2021

Abstract
Rapid industrial developments and the resulting need for additional electrical power in major population centers of the world such as India, China and Brazil, have created a need and an opportunity for power from clean and renewable sources of energy. The need to develop and use resources such as solar energy, wind, and biomass has assumed even greater importance in view of the concern for environmental damage that could occur if all of the anticipated power demand in the expanding economies were met by fossil fuels.
Recent advances in wind energy technology have made it economically competitive with fossil-fuel-generated electricity, wherever sufficient wind resource is available. Solar thermal power can be economically competitive when compared with coal-generated electricity if environmental costs are accounted for (Goswami, 1994). However, without considering such environmental costs (a realistic scenario for developing countries like India and China) solar power may not be competitive at present because of the high capital costs. The potential exists for reducing these expenses by improving the performance of thermal power systems. The system performance can be improved by employing new and innovative ideas in thermal power cycles. This article reviews some of these ideas and research needs to make solar thermal power cost competitive.
A Constitutive Model for Cyclic Loading and Relaxation
Authors: Garmestani H. 
Published: November 2021

Abstract
A new model is proposed which incorporates inelastic flow during cyclic loading and relaxation processes. The model is an extension of Hart’s constitutive model for inelastic flow and is based on the non-steady state condition for the frictional glide process. A new state variable is introduced here as a microhardness parameter which represents the strength or the average lifetime of the mobile dislocations relative to the frictional glide viscous drag process. The evolution of the microhardness parameter is very similar to that proposed for the hardness parameter except that the recovery plays a major role. The results show that the model can predict the transient behavior for both cyclic loading and the reloading phenomena during inelastic deformation and load relaxation.
Dynamics of Vehicles Subjected to Extreme Steering
Authors: Forouhar Farshid A. 
Published: November 2021

Abstract
This simulation study examined the influence of first order suspension design attributes on minimum lateral acceleration required to overturn a vehicle (lateral acceleration at roll, “LAR”). When subjected to extreme “step-steer” maneuvers, many sport utility vehicles (SUVs) tip-up on two wheels. Lateral accelerations achieved during these tests, however, rarely approach corresponding values of LAR. Moreover, in many cases, transient dynamics during initial phases of the tests do not explain this discrepancy. To address why vehicles overturn in such circumstances, a lateral/directional model was developed. Phase-plane analyses of lateral/directional response uncovered an oscillatory mode of response that explains observed oscillations that, in turn, significantly influence the likelihood of overturn. Results of analyses also indicated inherently high sensitivity to initial conditions of the final outcome of extreme step-steer maneuvers.
An Optimum Design Approach Using Active and Semi-Active Suspensions for 3-D Vehicle Models
Authors: Bouazara M. , Richard M. J. 
Published: November 2021

Abstract
The primary purpose of this paper is to analyze the effects of vibrations on the comfort and stability of road vehicles as observed in the variation of different parameters such as suspension coefficients, road disturbances and the seat position. The conducting of this study required the development of a mathematical model to simulate the dynamic behavior of a 3-D vehicle. This model makes it possible to efficiently use various types of non-linear suspensions such as active and semi-active suspensions. The results obtained from the simulation of the 3-D vehicle demonstrated that the use of active and semi-active suspension models on road vehicles proved to be beneficial for comfort without unduly compromising stability.
Design Sensitivity Analysis Applied to Injection Molding Process: Injection Pressure and Multi-Gate Location Optimization
Authors: Kabanemi Kalonji K. , Hétu Jean-François , Derdouri Abdessalem 
Published: November 2021

Abstract
In this work, we develop a numerical simulation method to optimize the injection molding process using the design sensitivity analysis (DSA). The optimization concerns the filling stage and focuses on the number and location of gates in a mold cavity as well as the injection pressure, considered as one of the key processing parameters, in order to minimize the fill time. Since the problem to be solved involves transient flow with free surfaces, the direct differentiation method is used to evaluate the sensitivities of the Hele-Shaw, filling fraction and the energy equations with respect to the design variables used in the analysis. The mesh domain parameterization is coped with using B-spline functions. Sensitivity equations are solved by means of finite element method. The proposed numerical approach is combined with the sequential linear and quadratic programming method of the DOT optimization tools to find the new design variables at each iteration. Starting with any initial gate locations and injection pressure profile, the method enables us to find the optimal gate locations together with the optimal injection pressure profile. Finally, numerical results involving complex mold geometries are presented and discussed to assess the validity and robustness of the proposed method.
Identification of Preform Permeability Distribution in Resin Transfer Molding
Authors: Minaie B. , Chen Y. F. , Mescher A. M. 
Published: November 2021

Abstract
This paper presents a numerical scheme that directly calculates the permeability field of the preform during the Resin Transfer Molding (RTM) process. The measured filling front locations as well as the corresponding inlet conditions are used in the proposed scheme to calculate the permeability field. The proposed scheme employs a numerical optimization algorithm to minimize a cost function that leads to the permeability filed of the preform. A time step independent RTM filling algorithm is utilized as a computational kernel to generate the cost function for the subsequent iterative minimization. The proposed permeability identification scheme is applied to test problems that involve isotropic and anisotropic permeability distribution within the perform. The results from these test problems verify the applicability of the proposed scheme.
CAE Simulation and Verification of Wire Sweep for BGA 436
Authors: Jong Wen-Ren , Chen You-Ren 
Published: November 2021

Abstract
The microelectronics industry continues to grow rapidly in size and importance. As thinner and denser IC packages become, packaging process becomes more challenging and troublesome. The ball grid array (BGA) technology uses substrate and solder balls to replace the traditional leadframe, which offers many advantages over fine pitch technology. These include better assembly yield, superior electrical performance, and higher I/O density. However, the high density of bonding wires form a separating layer which will hold back the molding compound flowing through these regions.
The paper presents the simulation of melt-front advancement and wire sweep for BGA 436. The results has been verified by the experimental studies. It is found that the high-density of wires has played a very important role in performing the CAE analysis. It shows that the melt-front advancement can be precisely predicted by CAE simulation software with proper consideration of wire density. With the accurate simulation of melt-front advancement, the CAE results can be further used to perform further engineering analysis. The wire sweep of the package demonstrates the use of CAE analysis, which also shows very good agreement with the experimental study.
Stress Intensity Factors for Cracks Within and Near to Bondlines in Soft Incompressible Materials
Authors: Smith C. W. , Gloss K. T. , Constantinescu D. M. , Liu C. T. 
Published: November 2021

Abstract
Using a polyurethane photoelastic material, thick test specimens of several configurations with bonded end tabs are examined for measuring stress intensity factors (SIFs) for cracks within and near to bondlines in bonded photoelastic models. Effects of specimen height, glued end tabs, bondline and crack size and location are studied and analyzed using a two parameter model for extracting the SIFs and results are compared with cracked, homogeneous model results.
Mixed Mode I/II Fracture and Fatigue Crack Growth Along 63Sn-37Pb Solder/Brass Interface
Authors: Nayeb-Hashemi H. , Yang Pinghu 
Published: November 2021

Abstract
Solder joints are extensively used in electronic packaging. They provide critical electrical and mechanical connections. Single edge notched sandwich specimens, which were made of two blocks of brass joined with a 63Sn-37Pb solder layer, were prepared for fatigue and fracture study of the joint under mixed mode loading. Mode I and mixed mode I/II fracture toughness, fatigue crack thresholds, and fatigue crack growth rates (FCGR) were measured at room temperature using a four point bending test setup.
It was found that the fracture toughness of the joint increased and FCGR decreased upon the introduction of mode II component. The interface fracture toughness was higher than that of reported for pure solder. The data of FCGR correlated well with the power law relation of da / dN = C* (ΔG)m. It was also observed that both fracture toughness and FCGR were a function of thickness of solder layer. When the solder layer thickness increased from 0.1mm to 1.0mm, the fracture toughness decreased substantially and FCGR increased slightly.
For mode I loading, fatigue crack propagated inside the solder layer. However, for mixed mode loading, once a crack initiated, it changed its direction toward the interface and then propagated along the interface. These observations were related to local mode I and mode II stress fields. Fracture surface showed sign of rubbing under mixed mode loading with elongated cavities at the crack tip. However, under mode I loading, fracture surface was covered with equi-ax voids.
Prediction for Post-Forming Spring Back of CICC in the Superconducting Tokamak Fusion Device via Virtual Manufacturing
Authors: Suh Yeong Sung , Ahn Jong Sung , Choi Sun Woong , Park Hyun Ki , Kim Yong Jin , Kim Kee Man 
Published: November 2021

Abstract
To construct the CICC for the superconducting Tokamak fusion device, the 3-roll bending, that inherently has a difficulty to form the coil with accurate radius of curvature, is used for continuous winding. In order to obtain precise dimension, a trial-an-error operation is inevitable. To reduce the effort of tryout, a relation between travel of the bending roller and spring back displacement was obtained via virtual manufacturing. The radius of CICC after forming was expressed as a function of the bend-roll travel. Next, the variation of the CICC cross-section (reduction of the conduit cross-section) was investigated during the first turn and during conduit bending with largest curvature. With largest curvature, the cross-sectional area was not much reduced. Finally, the residual stress on the CICC before roll bending was measured in order to examine the influence of the original residual stress on the final deformation behavior. The principal stress and von Mises stress were measured at the surface of CICC using specially designed strain gauge. The measured values were considered in the virtual forming. The results indicate that the residual stresses generated during the fabrication of the CICC (before coiling) do not have much influence on the final stress state.
Yield Function for Structural Porous Metals
Authors: Alam M. Khairul , Ahmed Shatil S. , Kuriger Rex J. 
Published: November 2021

Abstract
To reduce weight while maintaining high specific strength, Structural Porous Metals (SPM) are being developed. These materials are alloys containing an inert gas in distributed pores at very high pressures. The pores of gas are incorporated into SPM during processing. Since the pores are closed pores at high pressures, the material can be processed by standard methods such as rolling or forging without collapsing the gas pores. These materials must be treated as a composite material with special deformation behavior under applied stresses. It should be noted that, unlike solids, shear stresses can not be present in a gas medium in static equilibrium. This paper deals with the determination of the yield stress of structural porous metals. The yield function is calculated from the principle of virtual work. In this approach it is assumed that a constant amount of energy needed to deform the material to the yield point. In the case of SPM, the yield function must include the work needed to deform the gas pores as the material yields. The energy of deformation for the gas in the pores is evaluated according to the ideal gas law. The total work done in deforming the gas and the solid metal is taken into account in determination of the yield function of SPM. The result of the analysis is then compared with classic yield functions for monolithic alloys.
Effect of Promoter Orientation on Enhancement of Heat Transfer From Vertical Fins
Authors: Onbasioglu Seyhan U. , Onbasioglu Huseyin , Egrican Nilufer 
Published: November 2021

Abstract
The promoters redirect the flow and enhance the heat transfer both in laminar and turbulent cases. In the present study, the special care has been intensified first on the parameters such as the height and the pitch of the promoters and then the orientation of the repeated promoters with varying heights has been investigated. It is concluded that the enhancement of the heat transfer is sensitive to all of the parameters. Meanwhile, turbulence has been observed exceeding a certain value of the promoter height and the separation region occurring along the downstream plate has been analyzed. The flow and temperature fields have been obtained by means of a modified k-epsilon turbulence model developed for the present case. Results of the 3-D computations compare well with the experimental observations.
Heat Transfer Investigation of an Offset Strip Fin Using Liquid Crystals
Authors: Shin Seunghoon , Lavine Adrienne S. 
Published: November 2021

Abstract
The heat transfer characteristics of an offset strip fin are investigated by the transient liquid crystal method. It is found that there are various flow patterns that may occur, such as separation, reattachment, flow acceleration, expansion, and trailing vortex, and that the heat transfer is directly influenced by them. These flow patterns vary depending on the fin geometry and Reynolds number. For a sparsely stacked fin array (strip thickness-to-fin pitch, t/D &lt; 0.1), the heat transfer pattern is close to a flat plate in a free stream such that the heat transfer is high at the leading edge and decreases along the plate. A distinct pattern change occurs at ReDh ≈ 2300. The heat transfer is high at the leading edge, but decreases rapidly over the first 10–20% of the strip, then increases to a maximum at 25–30%, then decreases again over the rest of the strip. The maximum at 25–30% of the strip indicates flow reattachment there. The same trend is found in a densely stacked fin array (t/D = 0.25) but the pattern change occurs at much lower Reynolds number (ReDh ≈ 800). The influence of flow reattachment is comparable at these Reynolds numbers in both of the fin arrays but it becomes more significant in the densely stacked fin array as Reynolds number increases. It appears that this is due to more dominant flow separation and reattachment, caused by an adverse pressure field near the leading edge of the strip in the densely stacked fin array. The results indicate the importance of the fin pitch in understanding the flow and heat transfer characteristics of offset strip fins.
Absorption-Compression Heat Pump for Space Heating and Cooling Using Organic Fluids
Authors: Nogues M. , Valles M. , Bourouis M. , Boer D. , Coronas A. 
Published: November 2021

Abstract
The combination of compression and absorption technologies can provide heat pumps with high efficiency and a wide operating range. The aim of this research project lies in the development and testing of a gas-fired double effect absorption-compression heat pump working with organic pairs for space heating and cooling.
For these applications, the use of suitable organic working pairs makes possible heat pump operation at higher temperature lifts than that of conventional water-lithium bromide systems. In our research, the combination Methanol and Tetraethylenglycoldimethylether (TEGDME) has been selected as working pair. The heat pump is targeted to operate in both cooling and heating modes. Therefore, the basic structure of the heat pump is an absorption-compression double effect cycle for cooling mode, that can be switched to a single effect cycle, in order to achieve the required higher temperature lift for the heating operation.
The nominal working conditions for cooling are 5°C at the evaporator and 35 to 45°C at me absorber-condenser. These conditions can be achieved with a double effect absorption-compression cycle. Different solution circuit flow configurations as serial, parallel and reverse flow have been considered. The heating operation of the heat pump aims at a temperature of the useful delivered heat between 45 and 60°C for an evaporator temperature of 0°C. In order to achieve the required temperature lift with an attractive performance (COP in the heating mode higher than unity), the unit should operate as a single effect absorption-compression heat pump. The performance analysis was based on a thermodynamic model considering the equilibrium properties of the working pair and energy and mass balances in the different components. Results in both operating modes have been evaluated in terms of the solution flow rate, the coefficient of performance COP and the primary energy ratio PER. Very interesting performances are found even for high temperature lifts. The serial flow configuration has been selected due to its good performance and technological aspects.
This work forms part of the project CLIMABGAS. A prototype of this heat pump is under construction for a cooling power of 20 kW and a heating power of 24.5 kW.
Experimental Study of the Absorption Process of Organic Fluids in a Plate Heat Exchanger
Authors: Vallès M. , Bourouis M. , Boer D. , Nogués M. , Coronas A. , Villanova A. 
Published: November 2021

Abstract
In this paper, the absorption process in a plate heat exchanger with organic fluids has been experimentally investigated. It is well known that the absorber is the key component in absorption systems. The absorber studied consists of an adiabatic mixing chamber and a plate heat exchanger. In the mixing chamber, the solution that is poor in refrigerant is sprayed on the vapor refrigerant. Then, the two-phase mixture that is formed enters into the plate heat exchanger where the absorption process is completed by cooling the solution.
Experiments have been performed using the organic fluid mixtures: Methanol-Tetraethyleneglycol dimethylether (TEGDME) and Trifluoroethanol (TFE)-TEGDME. The effect of the solution mass flow rate, the absorber pressure and the cooling water temperature on the absorber performance has been analyzed. The results obtained are discussed in terms of the absorber load, subcooling of the solution at the outlet of the absorber, overall heat transfer coefficient and absorbed mass flux. The information achieved should serve to understand better the absorption process for such mixtures and design an absorber using plate heat exchangers for air conditioning applications.
Heat Transfer in an Oil-Injected Screw Compressor and in Its Discharge Pipe
Authors: Hammerl Klaus , Moser Johannes 
Published: November 2021

Abstract
Because of the extremely inhomogeneous oil distribution and the very short contact time of a few milliseconds between gas and oil, the heat transfer between the two phases inside a liquid injected screw compressor is strongly incomplete and the compression of gas runs almost adiabatic. To be able to judge the heat transfer inside the compressor, the air-oil mixture is withdrawn from the compressor and separated in such a way that the increase of the enthalpy of the oil can be determined. The final air temperature after compression is calculated via an energy balance. A similar schema is applied to the annular two phase flow in the discharge pipe following the compressor. The results show that the heat transfer from oil to air occurs mainly inside the pressure piping and the oil separator.
An Experimental and Computer Simulation Investigation of the Performance of a Heat Pump for Stratospheric Balloon Missions
Authors: Jiang Haobo , Borkowski Chris , Radermacher Reinhard , Didion Jeffrey 
Published: November 2021

Abstract
An environmental control system based on a heat pump was designed and built to provide a constant temperature environment for electronic packages used on stratospheric balloon missions. The major challenges in the design of this system are in creating the control hardware and control strategies for the heat pump, which is subjected to varying loads and environmental sink temperatures. The initial experiment and modeling effort, which will be used to develop an optimized hardware design and control strategy, is described.
An experiment was implemented to simulate the operating conditions the heat pump would experience in the stratosphere. The rarified environment of the stratosphere requires that the primary mode of heat exchange with the environment be radiative in nature. The heat pump was placed in a vacuum chamber to: 1) investigate the effect of the radiative coupling between the heat pump radiator/condenser and the environment (thermal source/sink) on the system performance, charge requirements, and temperature control of the evaporator, 2) investigate the effect of radiative cooling from the compressor shell on the compressor performance, and 3) determine if the compressor electronics heat exchanger could be sufficiently cooled by the heat pump suction line.
In addition to the experiment, a simple computer model was created to simulate the experimental heat pump. This model is compared against the experiment. The computer simulation predicted the performance of the heat pump at different heat loads, compressor speeds, space temperatures, and refrigerant charges. The predicted electric power agreed with the experimental results within −2% and 12%, and with evaporator and condenser temperature variations between 1K to 2K, and 3.5K to 6K respectively.