bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Thermal Runaway in Solid Foams
Authors: Goldfarb Igor , Goldshtein Vladimir , Kuzmenko Grigory 
Published: March 2022

Abstract
The phenomenon of the spontaneous insulation fires is investigated. An original physical model is based on the classical cell approach of multiphase media. The real complex media is modelled by a set of the identical parallel capillaries containing the thin film of the combustible fluid spread over their inner surface. The dynamics of the thermal explosion in this multiphase medium is studied. An advanced mathematical technique (integral manifold method) is used for qualitative analysis of the system dynamics. The classification of the possible scenarios of the thermal runaway is obtained analytically. Peculiarities of the dynamical regimes are investigated and their dependence on physical system parameters is analyzed. The research is focused on the regime with delay. Lower and upper analytical estimates for the delay time have been gained. The theoretical delay times estimations were verified when compared to those found experimentally. This comparison demonstrates sufficient qualitative and quantitative agreement.
Some Aspects of Particle Agglomeration in Simulated Slurry Fuels
Authors: Choudhury P. Roy 
Published: March 2022

Abstract
A series of experiments and analyses with JP-10 slurries, prepared with inert particles ranging in size from 0.3 μm to 2 μm, have been performed to study the influence of particle size, mass loading and droplet diameter on particle agglomeration in a slurry fuel. Particle mass loadings of 20% and 50% in droplets ranging in size from 100 μm to 3000 μm were studied analytically. Inert SiC and Al2O3 particles were chosen to avoid the complexities associated with reacting solids. Similarly, slurries were prepared without any chemical additives which could decompose. The choice of non-stabilized slurry with inert particles was made in order to isolate the problem under study, and not to cloud the issue of particle agglomeration due to burning particles and secondary reactions involving chemical stabilizers. Scanning Electron Microscopic (SEM) studies of the residues from burning and also evaporating droplets suggest that instead of using the usual very small particles (1 μm or smaller), intermediate size particles (∼ 3 μm) should be used in preparing the slurries. Intermediate size particles are affected neither by any interacting forces nor by chemical cementation caused by fuel decomposition at the particle surface heated by flame radiation. Therefore, the intermediate size particles are expected to minimize particle agglomeration. Analysis corroborates the fact that fuel decomposition is negligible at the surface of small particles. Also the solid mass loading between 20% and 50% seems to have a very small effect on fuel decomposition at the particle surface.
Because of increased mass and heat transfer rates in a flow field, analysis predicts a lower degree of fuel decomposition when droplets are exposed to flow.
Particle Temperature Response to Transient Thermal Perturbations in a Dilute Suspension Including Radiation Heat Transfer
Authors: Coimbra C. F. M. , Edwards D. K. , Rangel R. H. 
Published: March 2022

Abstract
The thermal response of particles subjected to time-dependent temperature perturbations in the surrounding medium, including radiation heat transfer, is studied. The continuous medium containing the dispersion of particles is assumed to be weakly participating, having a small but non-zero absorption coefficient. The particles in suspension are either in Stokes flow or stationary, so that the mechanisms of heat transfer between the particles and the continuous phase are of diffusive and radiative nature only. The general solution for the temperature response of the particles to time-dependent perturbations in the continuous phase is derived. The method used to derive the general solution consists of including the radiative effects in an integro-differential equation that describes the temperature history of the particles. A fractional-differential operator is then applied to the radiation-diffusion equation. The resulting equation is solved exactly by the method of variation of parameters for the temperature potential between the particles and the medium. Linear and harmonic perturbations are analyzed and discussed.
The Influence of Fuel Feed Unsteadiness and Spatial Nonuniformity on Spray Diffusion Flames
Authors: Greenberg J. B. 
Published: March 2022

Abstract
A mathematical model is formulated to describe the fluctuations of spray diffusion flames brought on by fuel feed unsteadiness and spatial nonuniformity. The spray is modelled using the sectional approach. An analytic solution is developed and utilized for computing the dynamics of the flame envelope under various operating conditions, such as liquid fuel volatility and droplet size, expressed through a vaporization Damkohler number. Calculated data reveal the way in which the underlying alternate waves of liquid and gaseous fuel lead to flame growth, collapse and distortion. This behaviour influences the temperature field temporally and spatially, and produces regions that are periodically hotter and colder. The ramifications of these results on combustion efficiency and pollutant production are discussed.
Transfer Process in Multisolid Two-Chamber Recirculated Reactor
Authors: Goldman Y. , Shavit A. , Dayan Y. 
Published: March 2022

Abstract
Prepyrolysis of coal as a precursor to its utilization in a power plant or gas turbine is experimentally investigated. The pyrolyzer, 800 mm in diameter and 1500 mm in height, consists of two concentric chambers. Coarse char particles, used like inert medium (“sand” in the sequel). The char is heated in the outer chamber by an external source of heat, such as hot gases. The inner chamber is used for the pyrolysis process of fine coal powder (50 micron), that is fed into it. The heat required for the endothermic pyrolysis process is supplied by the circulating char. Cold tests conducted on the apparatus indicate that the parameters most influencing solid circulation between the chambers are: the aerosol nature of the flow, the sand seals area, and the superficial velocity. The tests show that the intensive recirculation process exists only under very limited range of flow conditions. Outside this range of conditions, sand “bridges” are formed at the seals preventing proper operation. These bridges can be destroyed by strong fluidization at the inner chamber wall. Results of cold and hot tests, including parametric study of the pyrolzer performance, will be presented. The feasibility of the suggested scheme for mild gasification, of a precursor to its combustion in a power plant, will be discussed.
Measurements of Fully-Developed Augmented Convection in a Symmetrically Grooved Channel
Authors: Wirtz R. A. , Huang Feng , Greiner Miles 
Published: March 2022

Abstract
Measurements of fully-developed augmented convection and pressure drop of air flow in an isothermal, symmetrically grooved channel are reported for channel Reynolds numbers ranging from 800 to 5,000. Grooves, oriented transverse to the flow, are of triangular shape with dimensions that are comparable to the hydraulic diameter of the channel. The grooved section is designed to excite instabilities in the flow leading to increased mixing at sub-transitional Reynolds numbers.
Local heat transfer measurements are made using a holographic interferometer. Interferograms, representative of the cross-span-average temperature of the air in the channel, are analyzed to produce data records of the air temperature distribution and the local heat flux along the grooved walls. Heat flux distributions are spatially averaged to produce a correlation of fully-developed Colburn j-factor for this surface configuration. A performance evaluation of the grooved surface applied to a simple heat exchanger shows that it provides thermal performance which is comparable to other surfaces commonly employed in compact heat exchangers.
Turbulent Heat Transfer in a Steam Turbine Bypass Pipe Flow
Authors: Amano R. S. , Draxler G. R. , Golembiewski J. M. 
Published: March 2022

Abstract
The main goal of this study is to investigate the evaporation process of a coolant (water droplets) which is injected through spray nozzles mounted on a steam turbine bypass pipeline in a co-generator system. The study includes several important factors: (1) the effects of elbows on the flow pattern and evaporation process of the water particles; (2) heat transfer that affects the steam temperature and also the evaporation rates; and (3) the effects of insertion of a perforated plate in the flow path on the evaporation process.
Modeling of the high-pressure turbulent steam flow was based on a non-staggered finite volume method in 3-D, turbulent, compressible, two-phase dispersed flow formulations. Computations were performed by separating the entire pipeline system into four sections, each of which was generated in a 3-D grid system for more efficient computations by maintaining a sufficiently large number of meshes for each section. Flow calculations were made in each region separately by patching the end conditions from one pipe to the inlet conditions of the next one.
Through this research, numerous data have been acquired and analyzed for heat transfer mechanisms of the cooling water droplets in the pipeline system. The accuracy of the computations were validated by comparing them with theoretical models, and were shown to be quite reliable.
Measurement of Thermal Gradients and Fluctuations Using Liquid Crystals
Authors: Mukherjee D. K. , Prasad V. , Tan H. 
Published: March 2022

Abstract
The experimental and image processing technique presented here seeks to provide time accurate information on local temperature and gradient fluctuations. Thermochromic liquid crystals (TLC) are used to map instantaneous two dimensional temperature fields. The color response of the liquid crystals is tracked by a CCD camera. A synchronization circuit is designed to correlate the perceived color of two different bands of TLC with the thermocouple measured temperature. An XI1 based algorithm is then used to extract quantitative information from the transient video images. Results on a rotational flowfield are presented to show the utility of the technique.
Consecutive-Photo Method to Measure Vapor Volume Flow Rate During Boiling From a Wire Immersed in Saturated Liquid
Authors: Ammerman C. N. , You S. M. 
Published: March 2022

Abstract
A photographic measurement technique is developed to quantify the vapor volume flow rate departing from a wire during boiling. The vapor flow rate is determined by measuring the volume of bubbles after departure from the boiling surface in consecutive frames of high-speed video. The measurement technique is more accurate and easier to implement than a previously developed photographic/laser Doppler anemometry (LDA) method. Use of the high-speed camera in place of a standard video camera eliminates the requirement for LDA-acquired bubble velocity measurements. The consecutive-photo method requires relatively few video images to be analyzed to obtain steady-state vapor volume flow rates. The volumetric flow rate data are used to calculate the latent heat transfer and, indirectly, sensible heat transfer which comprise the nucleate boiling heat flux. The measurement technique is applied to a 75-μm platinum wire immersed in saturated FC-72.
High Temperature Heat Flux Calibration
Authors: Langley Lawrence W. 
Published: March 2022

Abstract
Today heat flux sensors are available with temperature ratings up to 800°C. In many situations these sensors do not have to be cooled at all, and therefore do not produce aerodynamic or thermal disturbances. However, the variation of their sensitivity with temperature can be an important source of error.
The High Temperature Heat Flux Calibration System described here is designed to perform calibrations of heat flux sensors at ambient temperatures up to 816°C and heat fluxes up to 341 watts/cm2. The response of the sensor being calibrated is compared with that of a reference sensor, with the two sensors located on opposite sides of a thin heated flat plate.
Calibrations with this system are performed in a vacuum of about 1 torr, effectively eliminating convective heat transfer and heated flat plate oxidation. A controlled temperature heated stage is provided for the sensor on test, and a constant temperature cooled stage for the reference sensor. The heated flat plate is powered by direct current, and shielded from the sensors during warm-up by a bifurcated water-cooled graphite shutter. After the temperature of the heated flat plate has stabilized, the shutter is opened. This exposes the sensor on test and the reference sensor simultaneously to steep wavefronts of heat flux. After a few seconds the shutter is closed again and power to the heated flat plate is cut off.
All functions of the calibration system are performed under control of Labview® software. After mounting the sensor to be tested, the operator enters a list of desired temperatures and heat fluxes. Tests are then performed automatically in the sequence which will utilize the resources of the system most efficiently. At the end of the test sequence, calculations are performed and a report of calibration results is generated and printed. During the test the operator may monitor system functions and intervene at any point if desired.
Problems encountered in the design of this system and typical results of calibrations performed during its development will be presented.
Free and Mixed Convection in a Doubly Layered Porous Medium
Authors: Jendoubi S. , Kulacki F. A. 
Published: March 2022

Abstract
Convection in a horizontal, doubly layered porous medium has been investigated numerically. Both natural and mixed convection are considered for steady state heating from above. For natural convection, the effects of Rayleigh number on the Nusselt number are investigated. For mixed convection where a uniform flow enters at the side wall, the effects of both Rayleigh number and Peclet number are studied. The effects of the thickness of one layer as well as the length of the heated zone are also examined. Further, the permeability and the thermal conductivity ratios of the lower layer to the upper layer are varied from 0.1 to 100.0 and from 0.2 to 5.0, respectively.
Transient Temperature Measurements in a Simulated RTCVD Reactor
Authors: Horton J. F. , Peterson J. E. 
Published: March 2022

Abstract
Instantaneous transient gas temperatures were measured in a simulated rapid thermal chemical vapor deposition (RTCVD) reactor. The gas flow consists of an axisymmetric jet impinging on a heated wafer. The jet momentum is opposed by buoyancy from the heated surface. Temperatures were found non-invasively by laser induced Rayleigh light scattering (RLS). A RLS diagnostic system measures temperature by sensing intensity of light scattered from a control volume. Intensity is related to gas molecular number density, and thus temperature can be found from the ideal gas law. The RLS system was calibrated first with measurements in the potential core of a heated jet, and then in the RTCVD test section operating at ambient temperature but reduced pressure. In both cases, the measured intensity of Rayleigh scattered light had low uncertainty. Measured molecular number density corresponded well with that theoretically predicted from the ideal gas law. Transient temperature measurements were then recorded at several radial locations above the wafer surface as it was heated from ambient temperature to 200°C. Operating conditions consisted of Reynolds number Re, = 60, maximum Grashof number GrH = 4.4 × 106, and maximum mixed convection parameter GrH/Rei2 = 1200. Uncertainty of mean transient temperature was ±2°, while temperature fluctuations were large (T′ ∼ 50°C). Both flow visualization and temperature measurements showed that the flow field consisted of buoyancy dominated recirculations, and was highly three dimensional.
Application of Transient Radiative Transfer Equation to Oceanographic Lidar
Authors: Mitra Kunal , Kumar Sunil 
Published: March 2022

Abstract
This paper examines the formulation of the different methods of solving the one-dimensional transient radiative transfer equation for ocean remote sensing. This work is particularly helpful in determining school of fishes inside the ocean for commercial purpose. In this technique a pulsed laser is focused into the ocean, and the time-dependent back-scattered flux is measured at different depths inside the ocean. A large number of parameters such as the spatial and temporal variability of optical properties inside the ocean, ocean depth, type of ocean water, presence of biological matters, etc. can significantly affect the radiative transport through oceans. But since the emphasis of the work is on the scattering phenomenon, important parameters associated with it, namely the scattering albedo and scattering phase function distribution, are considered in detail in this paper.
Microgasketing and Room Temperature Wafer Joining for Liquid-Filled MEMS Devices
Authors: Simon Jonathan , Huang Long-Sun , Sridharan Balaji , Kim Chang-Jin 
Published: March 2022

Abstract
A closed liquid reservoir in typical fluidic microdevices contain liquid volumes ranging from μl to ml. A new approach for liquid filling and sealing of multiple microdevices with a volume less than 1 nl is presented. A Teflon microgasketing technique combined with a room temperature curing UV epoxy adhesive is used to isolate liquid inside each lithographically defined area and permanently seal the device all in a batch fashion. The technique has been applied to successfully package an array of liquid-filled mercury microrelays, each of extremely small volume (&lt; nl). To ensure good penetration of the adhesive throughout the entire die of many microdevices, a method for adhesive distribution using wicking microchannels has been developed. The microgasketing technique is further combined with electroplated microriveting, another low-temperature wafer joining method, to provide sealing to the microriveting technique. Microgasketing is a quite general technique, as it can be combined with most low-temperature wafer joining methods and the reservoir area could contain liquid or gas and can be of a wide range of volumes and shapes.
A Novel Dual-Axial AFM Cantilever With Independent Piezoresistive Sensors for Simultaneous Detection of Lateral and Vertical Forces
Authors: Chui Benjamin W. , Kenny Thomas W. , Mamin H. Jonathon , Terris Bruce D. , Rugar Daniel 
Published: March 2022

Abstract
This paper describes a novel dual-axial AFM cantilever with independent piezoresistive sensors for simultaneous detection of lateral and vertical forces. The cantilever consists of a flat, triangular probe with a vertical direction of compliance, implanted with a piezoresistive layer to form a vertical deflection sensor. This probe is connected to the base by tall, narrow “ribs” that give the structure lateral compliance. Embedded on the side-walls of some of the ribs are a second set of piezoresistors that form a lateral deflection sensor. A special ion implant at approximately 45 degrees to the vertical is used to create the piezoresistive sensors and electrical connections. Both the vertical and the lateral deflection sensors exhibit measured piezoresistive sensitivities ΔR/R on the order of 5 × 10−7 per Å. The cantilever was successfully used to obtain AFM images of a known sample, yielding correlated z-signal and x-signal images of the sample topography.
A Microstructure for the In Situ Determination of Residual Strain
Authors: Pan Chi Shiang , Hsu Wensyang 
Published: March 2022

Abstract
A new strain sensor with a compact structure has been designed, demonstrated, and characterized. The strain sensor composes of a pair of adjacent cantilever beams with different lengths connected by a short tip beam. Residual strain causes two beams to deflect and to magnify the deflection into optically measurable displacement of the tip beam. The analytical model to relate the measured displacement to residual strain has been derived, and its results are then verified by finite element modeling. The strain sensor does not need correction factor for the strain-displacement relation. The relation of the displacement and residual strain is linear, and the displacement is independent of both Young’s modulus and the thickness of the film. All three properties are not found simultaneously in previously reported strain sensors. Based on the same strain with the same calibrated displacement, our structural size can be smaller than other strain sensors. The strain sensor has been fabricated and demonstrated by using a wet SiO2 film, and undoped LPCVD polysilicon films without post annealing.
Nodal Simulation of Suspended MEMS With Multiple Degrees of Freedom
Authors: Vandemeer Jan E. , Kranz Michael S. , Fedder Gary K. 
Published: March 2022

Abstract
A mixed-domain schematic representation compatible with node-based behavioral simulators is developed for rapid design of suspended microelectromechanical systems (MEMS). Hierarchical models of several basic microelectromechanical elements are created. The components are interconnected to represent both devices and more complex systems. Using beams, masses, and electrostatic actuators as the fundamental building blocks, a nodal simulation of complete in-plane motion of a crab-leg resonator demonstrates the design approach. Electrical properties are included in the component models, enabling electrical and electromechanical signal analysis to be performed. This work is part of an continuing project that eventually will provide full six DOF models for a broad class of MEMS.
A Triangular Frequency-Tuning Comb Array
Authors: Lee Ki Bang , Cho Young-Ho 
Published: March 2022

Abstract
We present a new post-fabrication frequency-tuning method for laterally driven electrostatic microresonators using the DC-biased electrostatic tuning-comb structures arranged in a triangular shape. The tuning-comb structures adjust the resonant frequency of the microresonator using the linear electrostatic force, generated by the tuning-combs of linearly varied finger-length. The electrostatic tuning force and the associated frequency change, caused by the DC-biased triangular tuning-comb array, have been derived in terms of the tuning voltage A set of frequency-tunable microresonators has been designed and fabricated by the four-mask surface-micromachining process. The resonant frequency of the microfabricated microresonator has been measured at the reduced pressure of 1 torr in order to eliminate the air damping effect. The resonant frequency reduction of 80Hz is obtained for a tuning voltage increase of 20V. Possible source of the discrepancy between the theoretical estimates and experimental results has been discussed.
Boiling Heat Transfer From a Micro Heater
Authors: Hijikata Kunio , Yamamoto Norihiko , Takagi Shu 
Published: March 2022

Abstract
Heat transfer from a micro heater is investigated experimentally and numerically. The micro heaters made of Indium Tin Oxide (ITO) are set on a glass substrate immersed in FX3250 coolant. Two different sizes (50μm, 100μm) of heaters are used in the experiments to analyze the size effect. The effect of the surface deposited layer by Al2O3 is also investigated with changing the thickness of the layer. All the experiments are performed in both subcooled and saturated boiling. The boiling curves of different conditions are obtained and compared. The results show that there exists an optimum thickness of deposited layer for heat transfer enhancement. They also show that the present heat transfer process is quite different from that of usual boiling. The phenomena are dominated by heat conduction in the substrate and large portion of the generated heat is transferred to the liquid and then vapor bubble through the substrate around a heater. Further, a photograph of a liquid microlayer under a vapor bubble is taken and the relation between an unsteady bubble behavior and local temperature fluctuations is analyzed.