bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of Evaporating Spray and Comparison With Droplet Temperature Measurement Obtained by Rainbow Refractometer
Authors: Gemci Tevfik , Hom James , Chigier Norman 
Published: November 2021

Abstract
Both experimental and computational work are important in the study of spray evaporation and combustion; therefore, it is essential that a link between the two areas be established. In this study, measurements of a full cone spray using phase-Doppler interferometry and Rainbow Refractometry are presented and compared with computational results. The computation results were acquired using a KIVA-3V code, which is specifically designed to analyze transient, two- and three-dimensional, chemically reactive fluid flows with sprays.
Specifically, in this study, the droplet size, velocity and temperature distributions were measured at various locations within the full cone spray. Using the same initial and boundary conditions, computation results were obtained at corresponding locations and compared with the experimental results. The experimental and computational results agree very well and indicate similar droplet size, velocity and temperature distributions at the corresponding locations. Additionally, the cooling rates and movement of the droplets show the same trends.
Atomization of Liquid by Two-Phase Gas-Liquid Flow Through a Nozzle
Authors: Lörcher M. , Mewes D. 
Published: November 2021

Abstract
A liquid or a suspension is divided into small droplets by atomization. The mean goal is either the equal distribution of the droplets, or the generation of large surface areas of the liquid phase in order to increase heat- and mass-transfer. In two-phase atomization the spatial and time distribution of the mean droplet diameter of the spray depend on the total pressure upstream of the nozzle, the volumetric flow rate of the liquid and the gas, as well as on the flow regime in the nozzle. Thus the radial and axial profile of the void fraction inside the nozzle are measured with an electrical measurement technique. In addition, the flow in the nozzle is visualized by a high-speed camera. Three flow regimes are identified. These are bubbly flow, plug flow, and annular flow.
At the smallest cross section of the nozzle critical mass flow is observed. A literature review on models to calculate the critical mass flow is given. The calculated and the measured mass flow rates are compared.
Pressure Drop Fluctuation and Flow Regime Identification for Air-Water Two-Phase Flow
Authors: Bai Bofeng , Wu Tiejun , Guo Liejin , Chen Xuejun 
Published: November 2021

Abstract
The fluctuating pressure drop for air-water two-phase flow was measured in the vertical upward section of U-type tube with 0.05m I.D. The feature of the fluctuations was extracted by means of statistical and chaotic theories. The influence of liquid superficial velocity on the features was also investigated. The results showed that the mean, root mean square, fractal dimension of pressure drop fluctuations is function of flow regimes. The fractal dimension can be larger than 1.5 in annular flow with great liquid superficial velocity which is reported for the first time. Furthermore, the present paper provided a feasible solution, which the gas-liquid two-phase flow regimes can be recognized automatically and objectively on basis of the combination of the Counter Propagation Network (CPN) and the FFT coefficients of the differential pressure fluctuations. The recognition possibility is determined by the clustering results of the Kohonen layer in the CPN. With the presented test cases, the possibility can be greater than 90 percent for different liquid phase velocity.
Segregation During Magnetically-Stabilized Liquid-Encapsulated Growth of Compound Semiconductor Crystals
Authors: Ma Nancy , Bliss David F. , Bryant George G. 
Published: November 2021

Abstract
During the magnetically-stabilized liquid-encapsulated Czochralski (MLEC) process, a single compound semiconductor crystal is grown by the solidification of an initially molten semiconductor (melt) contained in a crucible. The melt is doped with an element in order to vary the electrical and/or optical properties of the crystal. During growth, the so-called melt-depletion flow caused by the opposing relative motions of the encapsulant-melt interface and the crystal-melt interface can be controlled with an externally applied magnetic field. The convective dopant transport during growth driven by this melt motion produces non-uniformities of the dopant concentration in both the melt and the crystal. This paper presents a model for the unsteady transport of a dopant during the MLEC process with an axial magnetic field. Dopant distributions in the crystal and in the melt at several different stages during growth are presented.
Investigation of Heat Transfer in a Building Integrated Photovoltaic System
Authors: Zhu Zuojin , Yang Hongxing , Wu Qingsong 
Published: November 2021

Abstract
Heat transfer in a building integrated photovoltaic (BIPV) system has been investigated experimentally and numerically. A mathematical model is proposed for the numerical prediction, where an alternative of temperature, the cumulative variable, is defined as a temperature integration along the wall height of the BIPV system. The system which was consisted of eighteen west facing BP PV panels and a heavy concrete wall was experimentally studied to measure the electricity generation rate and thermal regulation effects. The eighteen PV panels were arranged in three modes and installed on the building wall with an thermal regulation gap, which enables natural convection for the ventilation of the PV panels. The experiments were controlled by a computer, so that data from sensors can be collected and recorded by a data logger automatically. However, the instantaneous outdoor wind speed was estimated by the Discrete Hillbert Transformer with sample input selected from the data observed by the Observatory in Hong Kong in June of 1989. The measured results of four days from the twelfth to sixteenth of June in 1999 had been compared with the numerical results. It is found that the maximum of the average temperature of PV panels has exceeded 50°C, but the maximum conversion efficiency of solar energy is less than 10%, close to 6.76%. A good agreement has been obtained between the measurements and predictions for the four days of investigation. It is concluded that the model for heat transfer analysis could be applied for the long term run of this BIPV system.
A New Approach for Large Non-Linear Integer Optimization Suitable for Implementation on a Distributed Collection of Computers
Authors: Nickel Ronald H. , Mikolic-Torreira Igor , Tolle Jon W. 
Published: November 2021

Abstract
We present a new methodology called Multi-Indenture, Multi-Echelon Readiness-Based Sparing (MIMERBS) for solving large, non-linear integer optimization problems that arise in determining the retail and wholesale sparing policies that support the aircraft operating from a deployed aircraft carrier. MIMERBS determines the minimum cost mix of spare parts that meets required levels of expected aircraft availability. The size (thousands of variables), the nonlinear relationship between spare parts and aircraft availability, and the requirement that the variables be integers make this problem hard.
We provide a concise description of the MIMERBS model and present data to show how it improves on earlier sparing models. This improvement comes at the price of significant computationally complexity, which in turn makes the optimization problem hard to solve.
We describe how we integrated an interior point method with a direct search algorithm to solve this optimization problem. This hybrid algorithm is well suited for implementation on a home-made virtual super-computer made up of several dozen Windows NT computers connected by an office LAN. A description of the virtual super-computer is given in a separate paper. We report on three specific cases we solved using the MIMERBS model, having from 1,000 to 8,000 optimization variables.
A “Boundary Layer” Method for Obtaining an Approximate Equation for the Unsteady Velocity-Time History of Flow Startup in a Pipe
Authors: Janna William S. , Hochstein John I. 
Published: November 2021

Abstract
An incompressible fluid volume is initially at rest in a pipe. A valve is suddenly opened and the fluid accelerates from rest to the steady state velocity. The equation describing the accelerating motion is a first order nonlinear equation containing friction, pressure drop and kinetic energy terms. The solution to this equation yields a relationship between average velocity and time. The traditional solution method involves assuming friction factor is a constant, and equal to the steady state value. The equation can be solved numerically using a difference scheme, which does not involve assuming a constant friction factor. In this study, a method of generating a velocity-time equation in polynomial form is developed to obtain an alternative solution. The method is used to solve two specific examples and the results obtained are compared with the numerical solution method. The comparison yields a small error, and so the polynomial approximation method can be used as an alternative technique to describe the motion of an accelerating fluid volume.
Railroad Vehicle Glazing Standard Development
Authors: Lamond James H. , Liao Sam S. C. 
Published: November 2021

Abstract
The American Public Transportation Association’s (APTA) Passenger Railroad Equipment Safety Standard (PRESS) Task Force initiated a testing program to develop a new railroad vehicle glazing standard. The program was coordinated and funded through the Federal Railroad Administration (FRA). This paper presents the procedures and results of this testing program. The test program used an air cannon to project various sizes of steel balls at speeds between 30 and 125 miles per hour and a 24-pound cinder block at 30 miles per hour to impact different glazing samples (glass laminates and polycarbonates) in the vertical position with the impactors striking at 90 degrees to the samples. With the cinder block, the impacts had to occur between the corner of the block and the samples. A pendulum system was used to impact the samples at slower speeds. The ballistic tests consisted of a 0.22-caliber long rifle, 40-grain bullet at speeds between 960 and 1163 feet per second. The pass/fail criteria were dislodgment of the glazing from the frame, or spall penetrating one mil aluminum foil witness plate placed 6 inches behind the samples. Based on this test program and input from the rail industries, a new glazing standard was developed.
Nonlinear Behavior of Sandwich Panels With Delamination Inside Face Sheets Based on Refined Higher Order Core Theory
Authors: Li R. , La Saponara V. , Kardomateas G. A. 
Published: November 2021

Abstract
Sandwich construction, consisting of two stiff face sheets and a soft core of a foam or low strength honeycomb type while designed principally as efficient integral structures, can lose this quality when delaminations occur inside the face sheets, especially under compressive loading condition. A refined higher order core theory is developed for the core that accounts for the nonlinear distortion of the plane of section of the core and the compressibility in the vertical direction, and for the skins in which part of the transverse deflections is related to the core nonlinear distortion. Based on this core theory, nonlinear behavior of sandwich beams/panels with delaminated faces is studied. The nonlinear governing equations, boundary conditions, and continuity conditions are formulated for the compressed sandwich structure which includes initial imperfection and delamination in the face sheets. Solution arc length parameterization within Newton continuation method is employed in solving the bifurcation and nonlinear eigenvalue problems for critical loads and postbuckling behavior of the sandwich structure. The results suggest that delaminations inside face sheets have considerable influence on the global and local behavior of the whole sandwich con structure.
A New Approach for the Numerical Integration of Nonlinear Dynamic Systems
Authors: Zheng Zhao Chang , Su Zhi Xiao , Han Ray P. S. , Xu Zefang 
Published: November 2021

Abstract
In this paper, the exact solution of a linearlized equation is employed as initial conditions for the next timestep in the numerical integration of the end displacement and velocity. This exact solution is calculated by means of the Duhamel integration. The system equations are satisfied continuously and not discretely as done traditionally. The essential difference of the present method from other works is that the performance of dynamics systems can be traced continuously. Comparisons between the proposed method with traditional techniques are presented. Examples investigated include the large amplitude nonlinear vibration of a simple pendulum of a conservation system, the period of vibration and chaos in the forced vibration of the Duffing oscillator and forced vibration of the van der Pol oscillator of a non-conservation system. The results obtained indicate that the accuracy of the proposed method supersede that of the traditional techniques.
Modal Analysis in Coupled Vibration of Serpentine Belt Drive System
Authors: Zu Jean W. , Zhang Lixin 
Published: November 2021

Abstract
The modal analysis of linear prototypical serpentine belt drive systems is performed in this study. The entire system is divided into two subsystems: one with a single belt and its motion is not coupled to the rest of the system in the linear analysis; the other with the remaining components. The explicit exact characteristic equation for eigenvalues is derived, which does not use the iteration approach. The response of serpentine belt drive systems to arbitrary excitations is obtained as a superposition of orthogonal eigenfunctions. The exact solution without using eigenfunction expansion is derived when the excitations are non-resonance harmonic.
Finite Element Simulation of Damage in Dynamically Loaded Weldments
Authors: Moraes Ricardo , Nicholson David 
Published: November 2021

Abstract
The main goal of the current investigation is to accommodate combined damage softening and thermal softening in structures that experience ductile fracture [1] due to an impulsive loading. A constitutive model first introduced by Johnson-Cook [2], which is sensitive to strain rate effects and temperature softening, is extended to explain the proposed idea. Equations are derived through continuum mechanics theory. Continuum Damage Mechanics (CDM) was first introduced by Kachanov [3] during the fifties. Since then, the topic has been under development by many authors.
Numerical simulations are performed in the explicit finite element impact code LS-DYNA [4]. Constitutive equations for a viscoplastic model with damage and thermal softening are implemented in the code using a User Defined Subroutine UMAT. The Continuum Damage Mechanics (CDM) model is based on the Bonora formulation [5]. The combined material model, named UMAT 41, is added to the program static library using Digital Visual Fortran (FORTRAN 90). Using the User Defined Material, the solution of an explosive charge and of projectile impact applied to a ring-stiffened welded structure is analyzed to predict fracture.
Ring-stiffened structures are widely used in ships, submarines and aircraft, which are subject to explosive or projectile attack. Results obtained using models with and without damage softening agree very well with previously published data with respect to crack paths. However, the time histories and thresholds are sensitive to the model used [6]. Projectile impact is also presented in this work.
Nonuniform Temperature Distribution in Electronic Devices Cooled by Flow in Parallel Microchannels
Authors: Hetsroni G. , Mosyak A. , Segal Z. 
Published: November 2021

Abstract
We fabricated a novel thermal microsystems (simulating a computer chip) consisting of a heater, microchannels, inlet and outlet plena and we studied the effect of the geometry on the flow and heat transfer. The vapor - water two-phase flow patterns were observed in the parallel microchannels through a microscope and high-speed video camera. It was observed that hydraulic instabilities occur. Existence of a periodic annular flow was also observed, which consist of a symmetrically distributed liquid ring surrounding the vapor core. Along the microchannel axis, the periodic dry zone appears and develops. The thermal visualization and temperature measurements of the heated device were carried out using infrared thermography. As long as the flow was single phase liquid, the forced convection heat transfer resulted in a moderate irregularity on the heated chip. These temperature differences do not cause damage to the device. The steady-state heat transfer for different types of microchannels has been studied also at the range of heat flux where phase change of the working fluid from liquid to vapor took place. Under conditions of flow boiling in microchannels, a significant enhancement of heat transfer was established. In the case of uniform heat flux the hydraulic instabilities lead to irregularity of temperature distribution on the heated chip. In the case of nonuniform heat flux the irregularity increased drastically.
Thermal-Mechanical Analysis of an NCA Type of Chip-on-Glass Assemblies
Authors: Cheng Hsien-Chie , Lee Ming-Hsiao , Chiang Kuo-Ning , Chang Chung-Wen 
Published: November 2021

Abstract
Since the electrical conduction in the COG assembly using a non-conductive adhesive takes place through the connection of the bump and the electrodes, the contact resistance can be applied to the evaluation of the design quality as well as the overall reliability of the particular assembly. It should be further noted that as reported in the literature (e.g., see Liu, 1996; Kristiansen et al, 1998; Nicewarner, 1999; Timsit, 1999), the contact resistance between the bump and the electrode on the substrate strongly depends on the contact stress and the contact area. A higher reliability of the packaging somewhat relies on better contact stability as well as larger bonding stresses.
In order to explore the physical contact behaviors of a non-conductive adhesive type of COG assemblies, the contact pressure during manufacturing process sequences and during the temperature variation are extensively investigated using a three-dimensional nonlinear finite element model. The so-called death-birth simulation technique is applied to model the manufacturing process sequences. The typical COG assemblies associated with two types of micro-bumps that are made of different materials: metal and composite are considered as the test vehicle. The contact stress between the electrode and the bump is extensively compared at each manufacturing sequence as well as at elevated temperature in order to investigate the corresponding mechanical interaction. Furthermore, the adhesion stresses of the adhesive are also evaluated to further investigate the possibilities of cracking or delamination within the adhesive and in its interfaces with the die and with the substrate. At last, a parametric finite element model is performed over number of geometry/material design parameters to investigate their impact on the contact/adhesion stresses so as to attain a better reliability design.
Interfacial Versus Cohesive Failure on Underfill-Aluminum Interface: Effects of Interface Roughness
Authors: Yao Qizhou , Qu Jianmin 
Published: November 2021

Abstract
This paper is concerned with the interfacial adhesion and failure of underfill materials in flip-chip packages. Debonding of polymer-metal interfaces often involves both interfacial and cohesive failure. Since the cohesive strength of polymers is usually much greater than the polymer-metal interfacial strength, cohesive failure near the interface is usually desired to enhance the interfacial adhesion. Roughened surfaces generally produce more cohesive failure, therefore, are used commonly in practice to obtain better adhesion. In this paper a fracture mechanics model is developed that can be used to quantitatively predict the amount of cohesive failure once the surface roughness data are given. An epoxy/Al interface was investigated using this fracture mechanics model. The predicted amount of cohesive failure as a function of surface roughness compares very well with the experimentally measured values. It is believed that this model can be extended to other polymer – metal interfaces.
Mathematical Model for Thermostatic Expansion Valve
Authors: Ding Yiwu , Agonafer Dereje , Schmidt Roger 
Published: November 2021

Abstract
A methodology to generate the mathematical model to simulate the steady-state operation of the thermostatic expansion valves is described. Such a model is necessary in understanding the operation of a refrigeration system used in cooling electronics. The model treats the mutual dependence between the valve’s throttling and control functions, and requires a few experimentally determined parameters. Specifically, the characteristic of the valve changes with the evaporating temperature, and a simple model to represent this influence on the valve is suggested.
Musculoskeletal Modeling Using a Bond Graph Approach
Authors: Wojcik Laura A. 
Published: November 2021

Abstract
The dynamic effects of muscle strength, timing of muscle activations, and body geometry have been modeled for a wide variety of human activities. These types of models require the development of complex system equations that account for the effects of rigid-body dynamics, musculotendon actuators, passive and active resistance to motion, and other physiological structures. One way in which model refinement can be expedited is through the use of bond graph modeling techniques. While bond graph techniques have been used extensively in a broad variety of applications, they have been used only sparingly in the field of biomechanics, despite the potential suitability of a modular, multidomain approach to the modeling of musculoskeletal function. This modular approach to dynamic systems modeling is particularly useful in an educational setting, where it allows students to fully understand interactions among the components of complex multidomain systems. In the current paper, bond graph modules representing muscle function and rigid-body motions of underlying bone structures are introduced. These modules can be used in conjunction with control models of neuromuscular function for the simulation of overall dynamic motor performance.
A Sensor Fusion Method for a Network of Highly Autonomous Sensors
Authors: Figueroa Fernando , Yuan Xiaojing 
Published: November 2021

Abstract
To date, data fusion and sensor management systems have largely been implemented with centralized and hierarchical architectures. Numerical and statistical methods are the most common data fusion methods found in these systems. Some recent research has taken on distributed and decentralized systems, while there are other efforts that try to apply qualitative reasoning. However, little has been done to apply qualitative reasoning as an inference mechanism in distributed and decentralized systems. Based on other work by the authors, a sensor may be treated as a highly autonomous (decentralized) unit. In this context, this paper describes a distributed sensor-data-fusion theory based on a qualitative theory to interpret measurements, and on qualitative procedures to reason and make decisions based on the measurement interpretations. In this manner, fusion is done at a high-qualitative level, thus making it possible the implementation of intuitive (effective) methods to monitor, diagnose, and compensate processes/systems and their sensors.