bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Modeling of Heat Transfer and Water Shedding in Automotive Evaporator Louvered Fins
Authors: Wang DeMing , Zhang Chao 
Published: November 2021

Abstract
A mathematical model has been developed to simulate mass and heat transfer of humid air flows at the airside of automobile air conditioning evaporators. The phenomenon of water condensation and water shedding in louvered fins are modeled based on extension of the existing Eulerian two-fluid method which treats water and air as two continuous media. A species transport equation for the mass fraction of water vapor in humid air is solved. The condensation of water from the air mixture translates into a sink term for the vapor transport equation and an equal source in the continuity equation for the volume fraction of liquid water in the two-fluid system of equations. A critical element in modeling the condensate transport in louvered fins calls for a surface tension force sub-model, since the surface tension force is the primary resistance against water shedding and draining. A formulation is proposed to evaluate the surface tension force based on searching for the most probable liquid-air interface where sharp gradient of water volume fraction exists. Numerical aspect of the implementation is discussed. In order to validate the model and demonstrate the applicability of the present methodology, a six-louver two-dimensional test case is established. The relative influence of the stopping force on liquid distribution pattern and flow was illustrated. The simulation is then carried out on a full-scale 2-D louvered fin design for different operating conditions. This study has demonstrated the feasibility of modeling “wet” heat transfer and water shedding in evaporator fins with an Eulerian two-fluid based method.
Modeling Non-Equilibrium CO Oxidation in Combustion Systems
Authors: Adams Bradley R. , Cremer Marc A. , Wang Dave H. 
Published: November 2021

Abstract
Performance of industrial and utility combustion systems is becoming increasingly affected by limits on pollutant emissions such as NOx and CO. CO emissions impact design and operation of combustion systems, particularly when coupled with NOx reduction technologies that involve lower temperature operation or staged firing. Lower combustion temperatures or delayed mixing of fuel and air helps minimize NOx formation, but can increase CO concentrations and minimize CO oxidation rates. Reacting computational fluid dynamics (CFD) models have been shown to be useful in evaluating and optimizing performance of these new technologies and operating conditions. These CFD models have traditionally used equilibrium chemistry models to predict specie concentrations throughout the combustor, however equilibrium assumptions for CO oxidation at lower temperatures is inaccurate. A non-equilibrium CO model is required to accurately predict the oxidation of CO at temperatures lower than ∼1150 K. This paper reviews the development of a non-equilibrium CO model and integration with a reacting CFD model. The use of the resulting model is illustrated on two combustion systems — a waste gas incinerator and a cyclone-fired utility boiler. Results show that low temperature CO oxidation can be accurately predicted with the use of the non-equilibrium CO model.
Experimental and Numerical Investigation of Air-Particle Two-Phase Flow in Centrifugal Separator
Authors: Kang H. J. , Zheng B. , Lin C. X. , Ebadian M. A. 
Published: November 2021

Abstract
The velocity distributions inside a centrifugal separator with outside and inside diameters of 152.4 mm (6″) and 76.2 mm (3″), respectively, have been investigated experimentally and numerically to obtain optimum separation efficiency. Two 12.7 mm (1/2-inch) holes were drilled on the external surface of the separator to measure the velocity distribution in the separator. Two direction velocities (tangential direction along the cylinder surface and axial along the vertical direction) were measured to compare with the numerical simulation results. A 6060P Pitot probe was employed to obtain the velocity distribution. The dust samples (a mixture of steel particle and dust) from the dust collection box were analyzed using a Phillips XL30 Scanning Electron Microscope.
FLUENT code is used as the numerical solver for this fully three-dimensional problem. The fluid flow in the separator is assumed to be steady and incompressible turbulent flow. The standard k–ε model was employed in this study. Non-uniform, unstructured grids are chosen to discretize the entire computation domain. Almost 100,000 cells are used to discretize the whole separator. The constant velocity profile is imposed on the inlet plane. The pressure boundary condition is adopted at outlet plane. Comparing the velocity distribution and separation efficiency from the experiment and the numerical modeling shows that the experimental results and the estimated data agree fairly well and with a deviation within ±10%.
Composite Isogrid Structures With Integral Passive Damping
Authors: Chen Yu , Gibson Ronald F. 
Published: November 2021

Abstract
This paper presents preliminary results from an analysis of the damping properties of a composite isogrid panel with an embedded viscoelastic layer by means of a finite element method (FEM) implementation of the modal strain energy method (MSE). Modal analysis shows that significant shear deformation occurs in the region between the ribs and the face skin because of the stiffness mismatch between the two. Since the performance of a viscoelastic polymer damping material is optimized by subjecting the material to shear deformation, such damping materials can be placed at the interface between the ribs and the skin in order to significantly improve the damping properties of composite isogrid structures. It is shown that the shear strain energy density (energy per volume) near the edges of the panel in the damping layer is much higher than that at the center area for the first free-free vibration mode. As a first attempt at improvement of damping, the effect of using different amounts of damping materials on the loss factor of the isogrid panel is also studied.
Decisive Factors in Advanced Centrifugal Compressor Design and Development
Authors: Japikse David 
Published: November 2021

Abstract
The design of advanced turbomachinery has been practiced in the last half of the previous century with increasing degrees of sophistication while continuously advancing levels of efficiency and regimes of stable operation. This trend of development is not complete; products have not reached a level of full maturity. There is considerable room for further development of most turbomachinery products today when looked at with the perspective of the broadest possible design world. Modern design no longer concerns itself only with efficiency and stability, but adds significant issues of weight, life, cost of manufacturing, marketability, and so forth. Decisive factors in each area are considered in this paper and consideration is given to developing trends.
Stress-Induced Martensitic Phase Transformations in NiTi Shape Memory Alloys During Dynamic Loading
Authors: Miller David A. , Thissell W. Richards , Gray George T. , Macdougall Duncan A. S. 
Published: November 2021

Abstract
This research explores the near-adiabatic, high strain rate stress-induced martensitic phase transformation in NiTi shape memory alloys using both a compressive and tensile Split Hopkinson Pressure Bar (SHPB). The results of the dynamic loading tests are presented with emphasis on the loading rate, stress-strain response, specimen temperature and post-test microstructural evaluation. In addition to the large strain rates, tensile specimens of various geometries are tested to large strain levels such that void growth and failure mechanisms are identified. The dynamically loaded specimens failed in a mixed mode, ductile void growth followed by transgranular failure. The void growth in incipient failure specimens showed ductile void growth throughout the specimen cross-section.
A Basis Function Method for Controlling Payload Vibration Using Command Shaping Control of a Multiple Axis Robot Maneuver
Authors: Agostini Michael J. , Parker Gordon G. 
Published: November 2021

Abstract
Several manufacturing assembly operations exist which require the robotic repositioning of flexible payloads. One example is aligning body panels during automobile assembly. These operations can limit throughput due to the need for relatively slow trajectories that don’t excite payload vibration. Several methods exist for generating residual vibration-free trajectories for single axis maneuver of flexible payloads, but there currently is not a general method for multiple axis maneuvers with nonlinear combinations of the inputs driving system vibration. In this paper a trajectory generation method is developed minimizing the energy transferred to the payload at resonant frequencies. Simulation and experimental results are presented demonstrating the approach.
Deployment Behavior of Modularized Structures
Authors: Ishimura Kosei , Natori M. C. 
Published: November 2021

Abstract
Deployment behavior of modularized structures is numerically analyzed from the viewpoint of synchronism. Elastic panels with single and double accordion folding patterns are examined as examples of modularized structures. Through computer simulations, it is shown that asynchronous deployments are caused by inertia forces. To improve the synchronism of the deployment, autonomous distributed control method is proposed. Control rules are driven based on equations of heat conduction and wave propagation. It is confirmed that simple autonomous distributed control can improve the synchronism of the deployment.
Vibration and Stability Control of Spinning Flexible Shaft via Integration of Smart Materials Technology
Authors: Song Ohseop , Librescu Liviu , Jeong Nam-Heui 
Published: November 2021

Abstract
Within this paper problems related with the vibration and stability control of circular flexible shafts spinning about their rotational axis are addressed. Due to the occurrence, as a result of the spinning speed, of gyroscopic forces in the system, the rotating shaft can experience, in some conditions, instabilities of the same nature as any nonconservative system, namely divergence and flutter instabilities. Whereas the former instability is of a static character, the latter one is of dynamic character and the results of its occurrence are catastrophic.
By including collocated sending and actuating capabilities via integration in the system of piezoelectric devices and of a feedback control law, it is shown that a dramatic enhancement of both the free dynamic response and of the stability behavior from both the divergence and flutter points of view can be achieved.
This implies that via the implementation of this technology an increase of the spinning speed can be achieved without the occurrence of these instabilities. Numerical simulations documenting these findings are provided and pertinent conclusions are outlined. It is also worthy to mention that the shaft is modeled as a thin-walled cylinder made of an anisotropic material and incorporating a number of non-classical features.
Effect of Regenerative Process on the Sample Stability of a Multiple Delay Differential Equation
Authors: Fofana M. S. 
Published: November 2021

Abstract
In this paper, explicit analytical expressions for the stability behaviour of a single degree of freedom turning model have been derived. The regenerative chatter due to chip thickness and feed rate variations, a delay in the spring stiffness coefficient and the probabilistic property of the displacement process of the chatter induced by the earlier tool cuts in the undeformed chip thickness have been taken into account. A characteristic equation for the linearized stability at equilibrium machining is presented, and regions of stable and unstable machining for multiple fixed time delays are captured in the parameter plane of two model parameters. By a combined use of the classical Hopf bifurcation theorem and the centre manifold, equations governing stochastic chattering, which are infinite in character, are reduced to two-dimensional ordinary differential equations. The integral averaging method and the Lyapunov exponent have been employed to explicitly derive the required analytical expressions.
Nonlinear Modeling and Experimental Verification of a MDOF Hydraulic Engine Mount
Authors: Geisberger Aaron A. , Khajepour Amir , Golnaraghi M. Farid 
Published: November 2021

Abstract
This paper has made several contributions to hydraulic mount modeling. A continuous nonlinear decoupler model is developed to capture the amplitude dependent behavior of a typical hydraulic mount over low and high frequency ranges. The decoupler model also demonstrates decoupler resonance, which degrades high frequency characteristics of a generic hydraulic mount. In addition, this paper is the first to introduce a lumped parameter MDOF (Multi Degree Of Freedom) fluid column system that is shown to improve high frequency characteristics. Model parameters are identified by isolating components in an experimental test apparatus and applying system identification techniques. Model simulation results are validated with measured data over the full range of standard excitation conditions.
On Adaptive-Passive Vibration Suppression Using Distributed-Parameter Absorbers
Authors: Jalili Nader 
Published: November 2021

Abstract
A semi-active vibration absorber with adaptive capability is presented to improve wide band vibration suppression characteristics of harmonically excited structures. The absorber subsection consists of a double-ended cantilever beam carrying an intermediate lumped mass. The adaptive capability is achieved through concurrent adjustment of the position of the moving mass, along the beam, to comply with the desired optimal performance. If such an absorber is attached to a vibrating body, it effectively absorbs vibrations at all frequencies that belong to the absorber frequency bandwidth. Numerical simulations are provided to verify the effectiveness of the proposed absorption scheme. It is shown that the tuning strategy tries to follow and match the absorber natural frequency with the excitation frequency. The optimally tuned absorber provides considerable vibration suppression improvement over the passive and de-tuned absorbers, for wide band excitation disturbances.
Search-Based Selection of Sample Points for Form Error Estimation
Authors: Badar M. Affan , Raman Shivakumar , Pulat P. Simin 
Published: November 2021

Abstract
Efficient part feature verification through coordinate metrology requires prudent sample point selection as well as accurate zone fitting. Selection of a large sample size typically results in higher accuracy of sampling. This paper suggests search-based methods for reducing the sample size in form verification while maintaining required accuracy. Specifically, we illustrate the use of region elimination search methods for straightness verification and the tabu search technique for flatness. The corresponding form error is then obtained using the least squares and/or the minimum zone methods. Preliminary example analysis is presented to demonstrate the methodology.
Thermal Evaluation of GaAs-Based RF Power Amplifier Packages for Handheld Portable Applications
Authors: Adams V. H. , Lee T. Y. Tom , Hause J. V. 
Published: November 2021

Abstract
This study characterizes the thermal performance of the Thermally Enhanced Plastic Very Thin Fine Pitch Quad Flat No Lead Package (HP-VFQFP-N) family for GaAs-based RF power amplifier applications. This package uses perimeter lands on the bottom of the package to provide electrical contact to the printed wiring board (PWB). The package also provides thermal enhancement by having the die attach paddle exposed on the bottom of the package surface to provide an efficient conduction path when soldered directly to the printed wiring board. Thermal model assumptions and development for the 0.5 mm pitch HP-VFQFP-N package are provided. Due to the relatively low thermal conductivity of GaAs, power dissipation in the individual stage areas on the die were modeled instead of uniform surface heat flux or uniform heat generation rate approximations. A conjugate heat transfer problem, in which radiative losses from the exposed surfaces of the package and PWB to the external environment were accounted for, was solved for horizontal natural convection cooling. The model is benchmarked with infrared thermal imaging measurements obtained for a 20 I/O, 0.5 mm pitch, 4 mm HP-VFQFP-N package with a 2-Stage GaAs Power Amplifier (PA) integrated circuit (IC). Predictions for junction-to-ambient thermal resistance were within 10% of measured values.
Parametric studies were performed for HP-VFQFP-N sizes of 4, 5, and 6 mm with GaAs die sizes from 1.465 × 1.369 mm to 2.7 × 2.354. IC layout considerations and associated power distribution on the die were also examined. 2-Stage PA, 3-Stage PA, and 3-Stage Dual-Band PA IC configurations were examined. Some improvement in thermal performance was noted with increasing package size (for the same IC configuration/die size). GaAs die size had minimal impact on thermal performance of the QFN package but the IC layout/power distribution significantly impacted product/package thermal performance. Additional studies were performed to evaluate mold compound and die attach thermal conductivity effects on package thermal performance.
An Analytical Design Method for Milling Cutters With Non-Constant Pitch to Increase Stability
Authors: Budak Erhan 
Published: November 2021

Abstract
Chatter vibrations result in reduced productivity, poor surface finish and decreased cutting tool life. Milling cutters with non-constant pitch angles can be very effective in improving the stability of the process against chatter. In this paper, an analytical stability model and a design method are presented for non-constant pitch cutters. An explicit relation is obtained between the stability limit and the pitch variation which leads to a simple equation for optimal pitch angles. A certain pitch variation is effective for limited frequency and speed ranges which are also predicted by the model. The improved stability, productivity and surface finish are demonstrated by several examples.
On Modeling the Rolling Contact Fatigue Performance Based on Residual Stresses Generated by Superfinish Hard Turning
Authors: Agha Salah R. , Liu C. Richard 
Published: November 2021

Abstract
It was shown earlier [Agha and Liu, 1998, 1999, 2000] that different cutting conditions, within superfinish hard turning, would lead to significantly different rolling contact fatigue lives. In this study, residual stresses were measured. The rolling contact fatigue life was then modeled using a maximum modified equivalent stress that takes residual stresses into account. It is seen that the maximum modified equivalent stress is a better predictor than the maximum Hertzian stress, but, still not accurate, given the consistent repeatability of the tested workpieces [Agha and Liu, 2000]. The difference in the nature of residual stresses produced by grinding and hard turning is used to show why the inclusion of the maximum modified equivalent stress, its location and the volume at risk, improves the power of the model to predict the rolling contact fatigue lives of the hard turned surfaces. This model is the best up to date for predicting the fatigue life of a surface, especially when residual stress is a factor.
Changes in the Mechano-Electrochemical Environment in the Extracellular Matrix Surrounding Chondrocytes
Authors: Mow V. C. , Guo X. E. , Sun D. D. , Lai W. M. 
Published: November 2021

Abstract
The objective of this paper is to provide an overall discussion of the biomechanical factors that are required to analyze and interpret data from the explant experiments and to present a description of some of the mechano-electrochemical events in the extracellular matrix (ECM) surrounding chondrocytes occurring within cartilage explants during loading. Five common loading cases of cartilage explants are discussed: hydrostatic pressure, osmotic pressure, permeation, confined compression and unconfined compression. Details of such surface loadings on the internal ECM pressure, fluid and ion flows, deformation and electrical fields are given. Similarities and differences in these quantities due to these five types of loadings are specifically noted. For example, it is noted that there is no practical mechanical loading condition that can be achieved in the laboratory to produce effects that are equal to the effects of osmotic pressure loading within the ECM. Some counter-intuitive effects from these loadings are also described. Further, the significance of flow induced compression of the ECM is emphasized, since this frictional drag effect is likely to be one of the major effects of fluid flow through the porous-permeable ECM. Associated streaming potential and diffusion potential and their dependence on the fixed charge density, are discussed in relation to the fluid flow through the charged ECM and the flow-induced compaction effect. Understanding of the differences among these explant loading cases is important; this can provide clearer understanding of the metabolic responses from chondrocytes in explant loading experiments.
Loading Rate Effect on Translaminar Fracture Toughness of Hybrid Composite Laminate
Authors: Moy Paul , Tzeng Jerome 
Published: November 2021

Abstract
Fracture toughness properties of composite laminates were evaluated at a loading rate commonly observed in ordinance applications. The laminates are composed of IM7 graphite and a small volume fraction of S2 glass plies to form a cross-ply laminate. Fracture toughness appears to be very rate sensitive if the crack growth perpendicular to the plane dominated by glass/matrix property. Experimental data shows a 30–40% increase of fracture toughness for various layup as the loading rate was increase by 1000 times. The specimens examined under microscopic indicates the strengthening might due to different failure mechanism in the matrix. In addition, there is no visible rate effect if the crack propagation is perpendicular to the graphite dominant plane.
Modeling and Simulation of Pressure Oscillations in a Gas Pressure Regulator
Authors: Delenne Bruno , Mode Laurent 
Published: November 2021

Abstract
Pressure stability on gas networks is a major concern for designers and operators of Gaz de France transmission and distribution networks. Pressure level is controlled by pressure regulators. To improve the process control and optimise the design of pressure regulating stations (PRS), experimental and numerical studies have been carried out by the Research and Development Division.
The purpose of this paper is to provide an analytical model for pilot controlled gas pressure regulators and to determine the operating conditions that avoiding oscillating pressure regime. Frequency and amplitude of the oscillations depend on many parameters such as flow rate, inlet and outlet pressure mean levels, the downstream volume size, the length of the sensing line or diameter of the outlet pipe.
Particular attention is required to represent pressure loss and flow dynamics in pipes and process lines. The model has been developed under the ALLAN.® Simulation environment, a general software for the description and simulation of dynamic systems.
It turned out from simulations and measurements that the upstream pressure and the volume of the downstream buffer are very sensitive parameters that influence amplitude and frequency. From a qualitative point of view, numerical and experimental results are in good agreement.