bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Algorithm Simulation for Deposited Structure of Atoms
Authors: Miyazaki Koji , Hijikata Kunio , Inoue Takayoshi 
Published: March 2022

Abstract
Molecular simulations using a genetic algorithm are conducted in the present study to investigate stable structures of clusters and deposited atoms on a substrate. First, the total potential energy of a n-atoms cluster is calculated for various atom configurations, where an icosahedron is found to be the stablest structure of a 13-atoms cluster. Secondly, stable structures of deposited atoms on a solid surface are investigated. The simulation shows that deposited atoms have either an island or a layer structure, depending on the combination of intermolecular potentials between the deposited and substrate atoms. In addition, a new idea of introducing a temperature concept into the simulation is proposed and evaluated, for examining temperature effects on the stable atom structures. The present solutions agree qualitatively with results from molecular dynamics simulations as well. In spite of demanding a little computing power, calculations can be expected to simulate most well-known stable molecular structures. From the study, it is confirmed that the genetic algorithm is an effective technique for examining stable structures of clusters and thin film.
Direct Contact Melting Process on a Spherical Heating Wall With an Arbitrary Temperature Distribution
Authors: Oka Mineo 
Published: March 2022

Abstract
Direct contact melting process takes place in a lot of technological processes. One of the important applications is in the thermal storage system. In this system, phase change material is stored in small spherical capsules. Diameter of the capsule is about 4 inches. Millions of capsules are packed in a thermal storage tank. Capsules are heated and cooled through brine. Direct contact takes place in the melting process of the thermal storage system. In this system, latent heat energy is used effectively. This paper presents a theoretical study of the direct contact melting process on a spherical heating wall that has arbitrary temperature distribution. Governing system of equations with heat convection terms is solved analytically. It is shown that it can be transformed into ordinary differential equations system by a similarity transformation. Temperature is solved using perturbation method. This solution is valid for almost all practical Stefan number. Analytical solution is obtained for a typical temperature distribution. It is shown that melting rate is enhanced by more than 10% by the effect of temperature distribution.
Thermophotovoltaic Energy Conversion Technology Development at NASA Lewis Research Center
Authors: Wilt David M. , Chubb Donald L. 
Published: March 2022

Abstract
NASA Lewis Research Center (LeRC) has had an ongoing research program in TPV since the late 1980’s. This effort has included both in-house research programs on critical components such as photovoltaic cells (PV) and emitter materials, as well as an active contracting effort directed toward system and component development. Of particular note is the in-house development of thin film selective emitters fabricated from rare-earth yttrium aluminum garnets (YAG). These emitters have demonstrated in-band emittances of &gt; 0.7 with low out of band emittances (∼0.2). Rare earth elements have a unique valency which allows them to behave as isolated atoms even when at solid state densities (i.e. produce line emission rather than grey body emission). Each element has a characteristic emission frequency (wavelength) and YAG selective emitters with emissions peaks ranging from 0.98μm to &gt; 2μm have been demonstrated. In addition, it has been demonstrated that two rare earth elements can be added to the same emitter for increased the power density.
Also developed at LeRC is a Monolithically Interconnected Module (MIM) consisting of many small InGaAs cells series interconnected on a single InP substrate. An infrared reflector placed on the rear surface of the substrate returns unabsorbed photons to the emitter for recycling. The MIM design has many advantages such as: high output voltages and low currents, improved reliability, minimized losses associated with emitter non-uniformity (i.e. variation in view factor, temperature, etc.), high output power density, simplified system design and simplified thermal management. MIM devices with excellent photoresponses and IR reflectivity’s &gt; 82% have been demonstrated.
The contracted efforts include a TPV system development by Tecogen, Inc., based on ytterbia fibrous selective emitters and silicon PV devices. Two (2) prototype TPV systems were constructed, each including recuperators, non-premixed combustor designs, dielectric interference filters and PERL silicon TPV PV cells. Emitters temperatures of 2000K were routinely achieved and both systems have logged many hours of testing. Also under contract development are solar powered TPV systems, InGaAsSb PV devices and plasma-sprayed selective emitters.
Numerical Simulation of Molten Carbonate Fuel-Cell Power-Generation Systems
Authors: He W. , Chen Q. 
Published: March 2022

Abstract
This paper provides a dynamic simulation model for investigation of the characteristics of molten carbonate fuel cell (MCFC) systems. To achieve the accuracy of the system model, the essential component model (i.g. fuel cell stack) is first established in three-dimensional, dynamic form, and it is then simplified prior to incorporation into the system model. The development of simulation techniques, such as estimation of variable limits, connection between component models, definition of input variable variation, and selection of simulation time step, has resulted in successful simulations.
The stationary simulation results for the entire load range show that the fuel cell system has the highest efficiency at partial load (45% full load). The dynamic simulation results indicate the existence of dynamic interactions between the stack and reformer under load-up operation. Moreover, the investigation has evaluated the alternative operation strategy of providing fuel gas directly to the reformer combustor during load-up mode. This alternative strategy has significantly reduced the dynamic interactions. The model has also been used to select the location of the fuel flow control valve. These results can be used to improve MCFC system operation and control design.
Modeling and Experimental Verification of a Perforated Plate-Fin Absorber for Aqua-Ammonia Absorption Systems
Authors: Garrabrant Michael A. , Christensen Richard N. 
Published: March 2022

Abstract
Modeling with experimental verification is presented for a novel Perforated Plate-Fin Absorber (Perforated Fin Absorber), developed for utilization in aqua-ammonia absorption chillers and heat pumps. The Perforated Fin Absorber’s (PFA) unique construction provides high heat and mass transfer efficiencies and simple fabrication, necessary for the residential and small commercial absorption cooling markets.
The PFA is comprised of a perforated fin sandwiched between cooling channels augmented with offset strip fin. Counter flow, falling film absorption (solution down, vapor up) occurs in the perforated fin cavity. The perforations are sized and spaced to prevent flooding and provide solution distribution. Coolant flow in the offset-strip fin cavities is counter to the solution flow.
The PFA was modelled using a combined heat and mass transfer analysis. Two laboratory prototypes were constructed and tested over a range of solution flow rates and concentrations. The experimental data was utilized to verify and calibrate the design model. Experimental results verify that the PFA geometry provides very high absorption rates over a wide range of operating conditions.
Heat Transfer Coefficients of Zeotropic Refrigerant Mixtures and Their Pure Components in Horizontal Flow Boiling: An Experimental Study
Authors: Rohlin Peter 
Published: March 2022

Abstract
The paper deals with an experimental study of flow boiling heat transfer coefficients in horizontal tubes. The experiments are performed in an electrically heated thermosiphon loop with two different evaporator tube diameters. Measurements are performed with constant heat flux along the tube and at relatively low heat and mass fluxes. The gravitational forces will influence the flow pattern and incomplete wetting of the tube walls will occur in a great part of the measurements. The tests are performed with the pure substances R22, R142b, R32 and R134a as well as several mixtures of R22/R142b and R32/R134a. The two tube dimensions tested have quite different behavior in spite of having the same length and refrigerant distribution system.
A Chen-type correlation is chosen to predict the local heat transfer coefficients. The influences on the heat transfer coefficient of incomplete wetting are correlated by correcting the enhancement factor by a function of the Froude number. The correlations obtained for the two tube diameters and with pure refrigerants are then used as basis for the evaluation of the refrigerant mixture tests.
The degradation of the heat transfer coefficient for mixtures is discussed. The measured mixture heat transfer coefficients are well estimated by using Jung’s correlation for mixtures, if Jung’s enhancement factor is replaced by the enhancement factors evaluated from the tests and the real mixture transport properties are used or by the theoretically approached correlation by Granryd.
Refrigeration Lubricants for R-407C
Authors: Macaudière Sylvie , Rolotti Gustavo D. , Sanvi Pierre 
Published: March 2022

Abstract
Miscibility between refrigerants and lubricants has long been considered essential to the refrigeration cycle. Many compounds that have been proposed for use as lubricants for hydrofluorocarbons (HFC) have polar molecular structures in order to be fully miscible with the refrigerants. However, it seems difficult for these lubricants to maintain long term durability in rotary compressors when R-407C is used.
In order to overcome the durability problem, a new type of lubricant has been developed that sacrifices some of its miscibility in return for better anti-wear properties.
This paper presents new methods for selecting the best lubricant for future air conditioning applications.
The Development of Analytical Models for Predicting Viscoelastic Damping in Woven Fabric-Reinforced Polymer Matrix Composites
Authors: Guan Huimin , Gibson Ronald F. 
Published: March 2022

Abstract
This paper describes the development of a closed-form model and a finite element model for studying viscoelastic damping in woven fabric-reinforced polymer matrix composites. The closed-form model was obtained by first deriving an elastic solution based on the mechanics of materials theory, then applying the Elastic-Viscoelastic Correspondence Principle to the elastic solution. The damping loss factors were determined from the complex moduli. Three-dimensional finite element models with various mesh densities were constructed based on the actual geometry of a plain weave fabric-reinforced composite unit cell. Three different loading cases were designed to simulate extensional, shear and bending deformations of the unit cell. The strain energies stored in the fiber and matrix elements for each loading case were conveniently determined from the finite element analysis. A strain energy formulation was used to calculate the damping loss factors for each loading case. Experiments were conducted using an impulse-frequency response technique to measure damping in beam samples made of plain weave E-glass fabric-reinforced vinyl ester resin matrix composite. The predictions from both analytical models show reasonably good agreement with experimental data.
Ultrasonic and Acoustic Emission NDE of a Graphite/Epoxy T-Joint
Authors: Dayal Vinay 
Published: March 2022

Abstract
This paper deals with the Ultrasonic Non Destructive Testing of a T-Joint Graphite/Epoxy composite. The T-beam is then subjected to compression loading and Acoustic Emission recording is used to follow the buckling and delamination growth in such structures.
The Effect of Toughened Composites on Dynamic Behaviors of Composite Laminates Under the In-Plane Dynamic Load
Authors: Jia Hongyu , Rogers Craig A. 
Published: March 2022

Abstract
In order to investigate the effect of toughened composites on the dynamic behavior of the laminated composite plates under in-plane loading, a simply supported laminated composite plate under the axial in-plane dynamic load is studied. A model for symmetric cross-ply laminated composite plate is presented here. The gorvening equations of motion are obtained by using Lagrange equations. The laminated composite plates are made from various composite materials, such as, Graphite/Epoxy, Graphite/PEKK, Graphite/PEEK, and Kevlar/PEKK. This model considers the large strain, transverse inertia, and neglects the in-plane inertia. The static critical buckling load is determined. The static part and the amplitude of dynamic part of the load are less than the static critical buckling load. Dynamic buckling of the laminated composite plates is studied for dynamic instability regions and primary responses. Linear solution for dynamic instability region is obtained. Also, the linear natural frequencies are determined for different compressive loads and materials. Nonlinear solution for primary responses is also obtained. The effects of the toughened composites on the dynamic buckling responses of the plates are evaluated.
Boundary Element Method for High Frequency Acoustic Analysis
Authors: Raveendra Satha T. , Thompson James K. , Mollo Chris M. 
Published: March 2022

Abstract
A boundary element formulation based on energy flow is developed for the analysis of high frequency acoustic problems. Unlike traditionally modelled acoustic pressure and velocity variables, the variation of space-averaged energy density at high frequencies is rather smooth and therefore energy parameters are well suited for the description of acoustic behavior. The governing differential and integral equations based on energy variables are similar to the Helmholtz equations for acoustic problems based on pressure and velocity variables and thus the extension of existing solution techniques for the solution of integral equations based on energy flow parameters is rather straightforward.
Intelligent Tool Wear Estimation for Precision Cutting Tools
Authors: Suchorucov U. N. , Derevianchenco A. G. 
Published: March 2022

Abstract
This paper presents a new algorithm for the direct inspection of the cutting tool wear. The place of the direct inspection is discussed. It is shown hat direct inspection does not require to establish experimentally a number of correlations amongst the cutting process parameters for each particular cutting regime, the tool and the workpiece involved. The main difficulty associated with the direct methods is the graphical representation of the wear topology using the results of the measurements. The basic principles associated with such representation are discussed. The cutting tool is represented by a set of initial geometrical parameters which constitutes its initial shape. Then, this set is used for the comparison with that of the partially worn tool to distinguish the wear topology. A number of computer program for the built-in computers of CNC machine tools are developed on the base of the proposed approach.
Engaged Cutting Edge Effects on Tool-Wear and Tool-Life in Turning Operations Using Grooved Cutting Tools
Authors: Li P. X. , Stein D. , Ghosh R. , Jawahir I. S. 
Published: March 2022

Abstract
This paper presents a systematic approach to the assessment of tool-wear/tool-life and provides a new relationship between the effective engaged cutting edge and tool-wear in machining with grooved tools. It is found that the tool-wear patterns change with varying cutting edge angles and nose radii; both of which affect the engaged length of the cutting tool. Four different cutting edge angles and nose radii are tested. Tool-life is then validated by a new tool-life equation which includes the operational effects of the cutting edge angle and the tool nose radius.
Tool Path Generation Using C-Space for 5-Axis Machining
Authors: Morishige Koichi , Takeuchi Yoshimi , Kase Kiwamu 
Published: March 2022

Abstract
The paper deals with the method of tool path generation for 5-axis machining using a ball end mill. 5-axis machining has been used for aircraft parts as well as for complicated shapes such as molds and dies. However, most of the present CAM systems for 5-axis machining have limited functions in terms of tool collision, workpiece shapes and machining methods. For that reason, in many cases the optimal cutter location (CL) data cannot be obtained or considerable time is consumed. To solve this problem, we have applied a 3-dimensional configuration space (C-Space) and showed the relationship between all tool positions and postures and the existence of tool collision. The method of tool path generation devised in the study enables users to generate CL data reflecting their own machining strategy such as smooth change in tool posture and the state of machining without considering the gouging. The validity of this method was experimentally confirmed by successfully milling an impeller without tool collision occurring.
Investigation of a Special 6-6 Parallel Platform for Contour Milling
Authors: Abbasi Waheed A. , Ridgeway Shannon C. , Adsit Phillip D. , Crane Carl D. , Duffy Joseph 
Published: March 2022

Abstract
Recently, companies have been experimenting with parallel-mechanism based approaches for milling machines. This research presents an investigation into the development of a special 6-6 parallel mechanism for application to contour milling. The idea behind this approach is that existing non-CNC milling equipment can be augmented to increase its capability at a lower cost than purchasing traditional 5-axis machining centers. This paper presents the phase of research associated with developing a parametric kinestatic design methodology for a special 6-6 parallel mechanism (Kinestatic Platform, KP). This methodology was applied to the design specifications associated with 5-axis contour milling. The resulting kinestatic design’s dynamics were evaluated to determine the actuation requirements of each connector. A prototype connector was built to allow the evaluation of actuator response under simulated loading conditions. Joint stiffness and control strategy were of primary concern in evaluating the performance of the prototype connector. The parametric kinestatic design and control strategy results are presented. Several observations are evidenced from the research. Joint deflection is an obvious critical issue and the most difficult to quantify. A scheme is proposed detailing the concept of using a separate metrology frame to overcome difficulties associated with accurate connector length determination.
Explicit Dynamic Finite Element Analysis of Laminated Composite Automotive Structures Using a New Composite Plate Element
Authors: Cho Y. B. , Plaskacz E. J. , Averill R. C. , Kulak R. F. 
Published: March 2022

Abstract
Composite materials are being considered for use in the front end structures of vehicles to help reduce overall vehicle mass and, thus, improve fuel efficiency. Acceptance of composite material in structural members will depend on their ability to do crash energy management. Numerical simulations can greatly aid in the design of these critical structures and reduce the number of crash tests. A new finite element, which is based on laminated plate theory with cubic zig-zag approximations, was developed to model the relevant mechanics that occur in composite materials during crash events. The element was cast in the internal force format for use with explicit integration solvers. In the plate theory, the in-plane displacement fields in a laminate are assumed to be piecewise cubic functions and vary in a zig-zag fashion through the thickness of the laminate. The zig-zag functions are obtained by satisfying the continuity of transverse shear stresses at layer interfaces. This in-plane displacement field assumption accounts for discrete layer effects without increasing the number of degrees of freedom as the number of layers is increased. The transverse normal strain predictions are improved by assuming a constant variation of transverse normal stress through the thickness in a laminate. The finite element is developed with the topology of an eight-noded brick. Each node has five engineering degrees of freedom, three translations and two rotations. Thus, this element can be conveniently implemented into general purpose finite element codes. Consistent and lumped mass matrices are derived. The developed element is implemented into Argonne National Laboratory’s in-house code, NEPTUNE, which utilizes explicit direct integration method. In NEPTUNE the internal force vector is calculated from the developed element at each time step. Numerical performance of the current element is investigated in this research.
Steel Post Simulation for the Buffalo Guardrail System
Authors: Reid John D. 
Published: March 2022

Abstract
In previous research, a new guardrail system, called the “Buffalo Rail”, was designed and successfully tested that incorporated wood posts. With the aid of nonlinear finite element analysis, a steel post Buffalo Rail system was designed and successfully redirected a heavy duty 3/4-ton pickup truck.
Although work remains on the Buffalo Rail, it clearly has shown potential to increase the safety performance of guardrail system throughout the world.
Woven Fabric Composite Material Model With Material Nonlinearity for Nonlinear Finite Element Simulation
Authors: Tabiei A. , Jiang Y. 
Published: March 2022

Abstract
The objective of the current investigation is to develop a simple, yet generalized, model which considers the two-dimensional extent of woven fabric, and to have an interface with nonlinear finite element codes. A micromechanical composite material model for woven fabric with nonlinear stress-strain relations is developed and implemented in ABAQUS for nonlinear finite element structural analysis. Within the model a representative volume cell is assumed. Using the iso-stress and iso-strain assumptions the constitutive equations are averaged along the thickness direction. The cell is then divided into many subcells and an averaging is performed again by assuming uniform stress distribution in each subcell to obtain the effective stress-strain relations of the subcell. The stresses and strains within the subcells are combined to yield the effective stresses and strains in the representative cell. Then this information is passed to the finite element code at each material point of the shell element. In this manner structural analysis of woven composites can be performed. Also, at each load increment global stresses and strains are communicated to the representative cell and subsequently distributed to each subcell. Once stresses and strains are associated to a subcell they can be distributed to each constituent of the subcell i.e. fill, warp, and resin. Consequently micro-failure criteria (MFC) can be defined for each constituents of a subcell and the proper stiffness degradation can be modeled if desired. This material model is suitable for implicit as well explicit finite element codes to deal with problems such as crashworthiness, impact, and failure analysis under static loads.