bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat and Charge Conductivities in Superlattices: Two-Scale Measuring and Modeling
Authors: Travkin V. S. , Catton I. 
Published: November 2021

Abstract
Conventional reasoning and established procedures for measurement of heat and charge conductivities at the continuum micrometer scale, or higher scales, results in a number of variables and physical entities being the subject of measurement. These variables themselves are not point values if to define them with the lower scale concepts. When the media overall properties are sought, their dependence on lower (smaller) scale physical phenomena and their mathematical descriptions need to be considered and incorporated into the higher (larger) scale description and mathematical modeling. This is not a new problem. How to treat or solve multi-scale problems is the issue. Effective scaled heat and charge conductivity are studied for a morphologically simple 1D layered heterostructure with the number of components being n ≥ 2, the effective scaled heat and charge conductivities. It is a two-scale media with the lower scale physics of energy and charge carriers being described by commonly used models. A continuum ↔ continuum description of ηm ↔ μm transport of electron-phonon energy fields, as well as the electromagnetic and temperature fields for ηm scale coupled with the microscale (μm) mathematical models are studied. The medium is heterogeneous because it has multiple phases, volumetric phases 1, 2, 3 .... and (n+m) phases that are the interfaces between volumetric phases. The fundamental peculiarities of interface transport and hierarchical mathematical coupling bring together issues that have never actually been addressed correctly. It is shown that accurate accounting for scale interactions and, as is inevitable in scaled problems, application of fundamental theorems to a scaled description of the Laplace and ▽ operators bring to the upper scales completely different mathematical governing equations and models. We have conducted and report some preliminary quantitative assessment of the differences between the static upper scale and transient nanoscale transport coefficients and show how the lattice morphology and its irregularities influence the effective conductivities.
Transient Radiation Element Method for Three-Dimensional Scattering, Absorbing, and Emitting Media
Authors: Guo Zhixiong , Kumar Sunil , Maruyama Shigenao 
Published: November 2021

Abstract
In this study transient radiative heat transfer is investigated in scattering, absorbing, and emitting media. The radiation element method is formulated for the first time to solve the transient radiative transfer equation in 3-D geometries. The sensitivity and accuracy of the method are examined. A good agreement of temporal transmittance predicted by the present method and Monte Carlo method is found. The characteristics of transient analysis are investigated via various problems of radiative transfer in inhomogeneous cubes. It is found that the transmitted signals are strongly affected by the inhomogeneous properties of the media through which the radiation has passed. In the position where the radiation travels a larger optical thickness, the broadening of the transmitted pulse width is more obvious and the magnitude of the transmittance is smaller.
Performance Modelling of Solid Oxide Fuel Cells
Authors: Cooper Richard J. , Billingham John , King Andrew C. , Kendall Kevin 
Published: November 2021

Abstract
Fuel cells are a clean and efficient alternative to existing methods of energy production. Solid oxide fuel cells produce electricity directly from the combustion of methane or other hydrocarbons. We present a mathematical model for a tubular solid oxide fuel cell, which includes consideration of advection, diffusion and electrochemical activity. The chemical reaction scheme includes both steam reforming and partial oxidation of methane, as well as carbon deposition on the anode surface. In the steady state, an asymptotic analysis is performed to find the composition of the exhaust gas. The results are compared with experimental data and good agreement is obtained.
The Feasibility of Using Photothermal Deflection Spectroscopy to Measure Thermal Contact Resistance in a Film on Substrate System
Authors: Foley Jason R. , Avedisian C. Thomas 
Published: November 2021

Abstract
In this paper we extend the theory of photothermal deflection spectroscopy for an isotropic film-on-substrate system to include the thermal contact resistance between the two materials and absorption of energy in the film and substrate. The model is formulated as a three-domain system (gas, film and substrate) with coupling conditions at the various interfaces, including a thermal contact resistance. Closed form expressions are obtained for the temperatures in each domain.
The analysis for probe beam deflection is confirmed by comparison to well-known limits of infinite film thickness, zero film thickness, zero contact resistance, and a thin absorbing layer at the surface of the film. The formulations are tested against NIST standard reference materials (SRM) using numerically generated beam deflection data to extract thermal diffusivity of a bulk material, and of two SRMs pressed together to extract thermal contact resistance. The results show the feasibility of using to determine the thermal contact resistance of a layered sample from beam deflection data.
A Review of Micro Heat Exchanger Flow Physics, Fabrication Methods and Applications
Authors: Bowman W. Jerry , Maynes Daniel 
Published: November 2021

Abstract
A review of the literature in the area of micro heat exchangers is presented to provide a concise overview of the recent advances in this field of study. The review is divided into six sections. The first section reviews research focused on understanding friction and heat transfer in microchannels. The second section deals with heat exchanger design, optimization and comparison studies. The third section deals with fabrication methods used for constructing micro heat exchangers. The fourth section reviews applications of micro heat exchangers. The last two sections of the paper deal with miscellaneous topics and other reviews on the subject. The total review focuses on advances made after the early 1990’s.
Thermal Modeling of a Liquid-Cooled Electric Machine
Authors: Jih Edward , Chen Kanghua , Abraham Thomas , Liang Feng 
Published: November 2021

Abstract
The future of the Hybrid Electric Vehicle and Fuel Cell Electric Vehicle is very promising for the automotive industry. In order to take a full advantage of those vehicles, a better thermal performance of the electric motor is required. A series of CFD analyses were performed in this study for the design of a liquid-cooled PM electric motor. Based on the results of this study, the thermal contact resistance of thermal interface between stator & housing is critical for the design of this PM electric motor. The effect of thermal conductivity of slot filling epoxy & stator core lamination on the peak temperature of stator winding is small. Improving the heat transfer capability of the air gap between stator & rotor can reduce the peak rotor temperature. The cooling of rotor magnet at the higher rotor speed is essential since the rotor temperature increases significantly due to higher power loss at rotor.
Reconstruction of the Temperature Profile Along an Optical Fiber Thermometer
Authors: Jones Matthew R. 
Published: November 2021

Abstract
A blackbody optical fiber thermometer consists of an optical fiber whose sensing tip is given a metallic coating. The sensing tip of the fiber forms an isothermal cavity, and the emission from this cavity is approximately equal to the emission from a blackbody. Temperature readings are obtained by measuring the spectral radiative flux at the end of the fiber at two wavelengths. The ratio of these measurements is used to infer the temperature at the sensing tip. However, readings from blackbody optical fiber thermometers are corrupted by self-emission when extended portions of the probe are exposed to elevated temperatures. This paper describes an alternative approach for using blackbody optical fiber thermometers that avoids the problems due to self-emission. In the alternative approach, an inverse method incorporating spectral measurements is used to reconstruct the temperature profile along the fiber. A genetic algorithm is used as the basis for the inversion method.
Turbulent Heat Transfer Over a Free Rotating Disk: Analytical and Numerical Predictions Using Solutions of Direct and Inverse Problems
Authors: Shevchuk I. V. 
Published: November 2021

Abstract
All known analytical solutions of the integral equation of the turbulent thermal boundary layer for a rotating disk have been obtained for the case of direct problem. This means finding the Nusselt number at a given distribution of the wall temperature. This distribution is described by power law and is monotone (derivative of wall temperature with respect to the radial coordinate does not change its sign). Outlined in this paper is an analytical form of non-monotone distribution of the wall temperature, which provided a new analytical solution for the turbulent Nusselt number including earlier known equations as a specific particular case. The solution is based on the integral method, which proved to be more precise than known Dorfman’s approach. Chosen for validation of the proposed method were turbulent heat transfer experiments of Northrop and Owen (1988). Predictions presented include analytical studies using inverse and direct problem solutions as well as numerical simulations using polynomial approximations of the experimental wall temperature distributions.
Analysis and Multi-Disciplinary Optimization of Internal Coolant Networks in Turbine Blades
Authors: Martin Thomas J. , Dulikravich George S. 
Published: November 2021

Abstract
This paper presents the theoretical methodology, conceptual demonstration, and validation of a fully automated computer program for the inverse design and optimization of internal convectively cooled three-dimensional axial gas turbine blades. A parametric computer model of the three-dimensional internal cooling network was developed, including the automatic generation of computational grids. A boundary element computer program was written to solve the steady-state non-linear heat conduction equation inside the internally cooled and thermal barrier-coated turbine blade. A finite element algorithm was written to model an arbitrary network of internal coolant passages for the calculation of the internal heat transfer coefficients, pressure losses, local flow rates, the effects of centrifugal pumping, heating of the coolant fluid, and forced convection from the thermal model of the solid to the coolant fluid. The heat conduction and internal flow analyses were iteratively coupled to account for the heat balance between the blade and the coolant fluid. The computer-automated design and optimization system was demonstrated on the second high-pressure turbine blade row of the Pratt & Whitney F100 engine. The internal cooling configuration and local heat transfer enhancements (boundary layer trip strips and pin fins) inside the three-dimensional blade were optimized for maximum cooling effectiveness and durability against corrosion and thermo-mechanical fatigue.
Cooling Effectiveness on Film Cooled Turbine Blades
Authors: Derrar M. , Nagler J. , Koschel W. W. 
Published: November 2021

Abstract
This paper presents experiments on the cooling effectiveness obtained for two different injection locations on the suction side of a turbine blade at transonic flow conditions. Previous results of a computational analysis and flow visualization indicated that a separation bubble is present on the suction side at a location x/L = 0.43 and the location x/L = 0.575 corresponds to a shock-boundary interaction zone [9]. The scientific interest is primarily focused on the realization of high film cooling efficiencies and its relevant parameters under these flow conditions. Streamwise aligned as well as inclined angled film coolant hole configurations have been investigated for each location. Due to the high number of interacting parameters the experimental simulation of turbine blade film cooling is extremely complex, which can only be solved by a simultaneous modeling using the experimentally measured results. Test rig, instrumentation and data analysis are described in detail. The goal of the investigations is to determine the optimum location of the film coolant injection.
Heat Transfer of a Chordwise-Oriented Internal Cooling Passage Around a Turbine Airfoil
Authors: Chyu M. K. , Ojo O. B. , Yen C. H. , Nordlund R. S. 
Published: November 2021

Abstract
An innovative design of closed-loop cooling system for a stator airfoil consists of a number of internal cooling passages wrapping around both pressure and suction sides of the airfoil. The cooling passages feature (1) jet impingement post a sharp 90-degree turn at the passage inlet, (2) turbulators on the outermost wall, and (3) a nearly 180-degree turn in the trailing edge. In addition, the passage has an irregular cross-section and varies throughout its entire length. A series of heat transfer tests have been performed at Re = 17,000 ∼ 61,000, compared to this tests which uses a new approach, so-called the hybrid liquid crystal technique. The magnitude of local heat transfer coefficient rises sharply in three regions. The first maximum occurs in the region subjected to direct jet impingement as the flow turns into the channel. Compounded with the inlet effect, this maximum, in fact, is the highest heat transfer coefficient over the entire passage. The second and third peaks, both are comparable in magnitude, locate near the trailing edge of the airfoil where the flow experiences a 180-degree turn and near the passage exit with a 90-degree turn. The average value of heat transfer coefficient over the entire passage is about 1.9∼ 2.5 times higher than that with fully developed turbulent flow in a straight channel. This level of enhancement is comparable to that of the conventional ribturbulators with a 90-degree angle-of-attack.
Characteristics of Continuous CVD of Silicon With a Moving Susceptor
Authors: Yoo Hoseon , Jaluria Yogesh 
Published: November 2021

Abstract
This paper deals with continuous chemical vapor deposition of silicon in a horizontal cold wall reactor, focusing on a moving susceptor. A two-dimensional numerical model, accounting for variable properties, thermal diffusion, radiative exchange among surfaces, and conjugate heat transfer between the gas and susceptor, is developed and validated. Scale analysis for the susceptor energy balance makes it possible to identify the characteristic parameters and infer their qualitative effects a priori, which proves to be consistent with numerical predictions. The results show that the present continuous system is characterized by two newly defined parameters: conductance ratio and susceptor parameter. A pair of performance curves that relate the deposition efficiency to each parameter successfully provide susceptor-related design conditions. It is also revealed that there exists an optimum length of heating zone that maximizes the deposition efficiency.
Localized Electron Evolution Induced by Femtosecond Laser Pulses in Water
Authors: Fan C. H. , Sun J. , Longtin J. P. 
Published: November 2021

Abstract
Optical breakdown by ultrashort laser pulses in dielectrics presents an efficient method to deposit laser energy into materials that otherwise exhibit minimal absorption at low laser intensities. During optical breakdown, a high density of free electrons is formed in the material, which dominates energy absorption, and, in turn, the material removal rate during ultrafast laser-material processing. Classical models assume spatially uniform electron population and constant laser intensity in the focal region, which results in a time-dependent expressions only, i.e., the rate equations, to predict electron evolution induced by nanosecond and picosecond pulses. For femtosecond pulses, however, the small spatial extent of the pulse requires that the pulse propagation be considered, which results in inhomogeneous plasma and localized electron formation during optical breakdown. In this work, a femtosecond breakdown model is combined with the classical rate equations to determine both time- and position-dependent electron density during femtosecond optical breakdown in water. The model exhibits good agreement when compared with experimental results. For other transparent or moderately absorbing dielectric media, the model also shows promise for determining the time- and position-dependent electron evolution induced by ultrashort laser pulses. Another interesting result is that the maximum electron density formed during femtosecond-laser-induced optical breakdown can exceed the conventional limit imposed by the plasma frequency.
Application of Affordable Composite Materials and Processes on UCAV (Extended Abstract)
Authors: Schwedt Steve J. 
Published: November 2021

Abstract
The Unmanned Combat Air Vehicle (UCAV) program is an Advanced Technology Demonstration Program funded by DARPA and the Air Force. As a part of the program two demonstration air vehicles were fabricated and assembled for flight test and for demonstrating the affordability of UCAVs. Using advanced design and manufacturing toolsets, the first vehicle, 27 feet long with a 34-foot wingspan, was designed and delivered in 18 months. In addition, unique fabrication, tooling, and assembly techniques were used to produce these vehicles. This presentation will discuss the techniques used that led to the success of the program.
A Micro/Macro Integrated Model for Melt Flow and Non-Equilibrium Solidification for Thermal Spraying
Authors: Wang X. Y. , Zhang H. , Zheng L. L. , Sampath S. 
Published: November 2021

Abstract
In this paper, a micro/macro-integrated model based on the VOF scheme is presented that accounts for free surface movement, thermal contact resistance, and fluid instability. A sub-model is developed to include the non-equilibrium solidification phenomena at the solid/liquid interface. In the combined model, the free surface location and movement are captured by the VOF technique, and the movement of the solidification interface is determined from the energy balance and the kinetic correlation of the interface velocity and temperature on the interface. The melt flow is incorporated into the microscopic model through interpolation of melt velocities on the macroscopic grids using prescribed velocity profiles. To improve the efficiency of the integration between the melt flow and microscopic model, a relational database has been developed and applied to the integrated micro/macro model. Three velocity profiles, e.g., linear, parabolic, and cubic velocity profiles, are investigated and the results were compared with that from the diffusion model.
Performance Evaluation of Serrated Plate Fins for Under-Carriage Electronics Cooling in Transportation Application
Authors: Shwaish Ibraheem K. , Murthy Jayathi Y. , Amon Cristina H. , Bains Diep 
Published: November 2021

Abstract
Serrated plate fins are commonly used in the cooling of under carriage electronics in people movers and other rail transportation systems. Here, a bank of electronic equipment consisting of diods, IGBT’s, and other power and control devices reside in an electronics box attached to the under-carriage. Plate fin heat sinks are typically attached to underside and along the sides of the box; typically flow through the heat sink is regulated by enclosing the sink in a channel with an open inlet and outlet for the flow. The heat sink is shown in Fig. 1. Even though water is used for cooling in Europe, the primary cooling fluid in the United State is forced air supplied by a blower and/or by the train motion. The problem is unsteady because of the train starts and stops, changing the load on the electronics and resulting in changes in the power dissipation.
Nanoscale Thermal Imaging of Thermionic Devices Using Scanning Thermal Microscopy
Authors: Tan Kwong-Luck , Miner Andrew , Fan Xiaofeng , LaBounty Chris , Zheng Gehong , Bowers John E. , Croke Edward T. , Shakouri Ali , Majumdar Arun 
Published: November 2021

Abstract
Ever increasing importance of cooling and precise temperature control in microelectronics and optoelectronics has driven recent development of integrated thermoelectric and thermionic cooling structures. Previous studies have investigated SiGe/Si superlattice thermionic coolers experimentally using thermocouples that were 50 μm in diameter. However, the relative size of these thermocouples as compared to the devices sizes (30–100 μm) makes surface and cross-section temperature measurement of the SiGe/Si superlattice thermionic coolers not possible. In this work, a sub 100 nm probe was used to measure the surface and cross-sectional temperature of the SiGe/Si superlattice thermionic coolers using scanning thermal microscopy. Two sets of superlattice thermionic coolers were used in this study and their cooling curves (temperature vs current) are presented. Each set consists of six devices of different sizes. A comparison of device cooling performance is examined. A mechanism for studying thermionic cooling in the superlattice coolers is discussed through an analysis of the cooler cross-section temperature profile.
Capillary Pumped Loop Heat Spreader for Electronics Cooling
Authors: Chung Jaewon , Grigoropoulos Costas P. , Greif Ralph 
Published: November 2021

Abstract
As cooling requirements for electronic devices, e.g. computer processor units, power modules, etc. increase beyond the capabilities of air-cooling, interest has moved to several alternatives such as thermoelectric coolers, impinging jets and heat exchangers with phase change. Included among these, the capillary pumped loop is a very competitive cooling device, because of its performance reliability, no power requirements and low manufacturing cost. In this paper, a heat spreader employing capillary pumped loop principles was made of aluminum and copper and tested. The copper CPL heat spreader with heat sinks and fans on the condenser (86mm thick, 60mm wide, 181mm long) has demonstrated a cooling capacity of 640W at atmospheric pressure in the vertical orientation and maintains a difference between TIHE (temperature of the interface between heater and evaporator) and TAMB (ambient temperature) lower than 100°C.
Development of a Health Monitoring Capability for FRP Using Optical Fiber Sensors
Authors: Cassino Christopher , Duke John , Borinski Jason 
Published: November 2021

Abstract
Fiber reinforced polymers (FRP) are an efficient and relatively inexpensive method of repairing or replacing deteriorating and damaged infrastructure. FRP sheets can be applied to spalling bridge sections to prevent further deterioration and increase stiffness. Pre-fabricated FRP decks can also be used to replace weak portions of the bridge superstructure. However, the effect of the environment on long-term durability of FRP and how the various mechanisms of deterioration initiate and develop are not known.
Systems for health monitoring are being sought as a means of managing transportation structures as assets in light of modern life cycle cost concepts. This paper will describe the efforts to develop a method to monitor the structural integrity of FRP materials utilizing an optical fiber sensor developed by Luna Innovations. This sensor is capable of detecting both transient, acoustic emission strain events as well as the accumulated strain in the components to which it is attached. The fact that this sensor is impervious to electromagnetic radiation makes it ideal for monitoring FRP in transportation applications.