bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low Cost Plastic Packaging of the Network Interface Unit
Authors: Zimmerman M. A. 
Published: March 2022

Abstract
The Network Interface Unit is a module of electronics mounted on the side of homes which carries broadband information, including voice, video, and data. The packaging goals are to provide for environmental protection along with EMI shielding for the electronics with inherent reliability’s providing for up to 20 years in life, at extremely low costs.
The packaging approach involves providing a double enclosure concept utilizing injection molded plastics. The design provides for snap-fit features which allows for mounting of the printed circuit board and a one-time-only snap-fit of the inside enclosure with no seals, screws, or gaskets to minimize assembly costs. The inside plastic components provide for fire resistance (UL-94-5VA), high heat resistance, and shielding while the outside plastic enclosure provides for chemical resistance, impact resistance, (low temperature) and ultraviolet resistance. The outside enclosure provides for a hinge and skirt which allows for shielding of the internal plastic components against ultraviolet exposure. There is also a tongue and groove seal which provides for moisture resistance.
“Thick” Plastic Packages With “Small” Chips vs “Thin” Packages With “Large” Chips: Experimental Evaluation of Their Propensity to Moisture-Induced Failures
Authors: Ilyas Qazi S. , Suhir Ephraim 
Published: March 2022

Abstract
A simple model reflecting the combined effect of the chip width, the pad with, and the underchip thickness of the molding compound on the propensity of a plastic electronic package to a moisture-induced failure was presented last year in the ASME conference (EEP-Vol. 16, Structural Analysis in Microelectronics and Fiber Optics - 1996). In this model, it was shown that “thick” packages (such as MQFP, SQFP) with “small” or “medium” size chips are less prone to moisture induced failure than “thin” packages (such as TQFP) with relatively large chips. An experiment was performed to examine the validity of this theoretical model. The purpose of this paper is to document the experimental data. The obtained results appear to support the suggested model.
Comparison of Different Solder Systems Based on Propensity for Damage
Authors: Sarihan Vijay 
Published: March 2022

Abstract
Very often need arises for evaluation of solder systems based not just on their reflow temperatures but on their capacity to withstand damage. Is there an inherent advantage from fatigue considerations in choosing one system over another? If so can we predict this difference.
Damage and it’s accumulation resulting in fatigue failure of solder interconnects is difficult to predict because of complex time and temperature dependence of solder behavior. Strain based solder fatigue description, like Coffin Manson, is not adequate as the fatigue life of the solder may also be a function of stresses. To circumvent the inherent drawback of the strain-based approach and for a more accurate prediction of stresses and inelastic strains, a dissipated energy based damage index approach, using a finite strain, nonlinear Finite Element Method (FEM), has been developed by the author for damage and fatigue life prediction. Instead of looking at complex tensorial responses of stress and strain it is proposed to look at the response in terms of the scalar damage.
The damage index method based approach is used here for comparing two different solder systems. The solder systems chosen are a high lead Pb97Sn3 system and the Sn60Pb40 eutectic alloy. In order to avoid biasing the evaluation for the melting point of the solder alloy, a new equivalent temperature cycle method is proposed. The response of the solder system to this equivalent temperature cycle is proposed as a fair methodology to distinguish the inherent differences in solder systems based on their propensity for damage.
Experimental Observation of Fatigue-Creep Fracture Development in Solder Joints of Different Standoffs
Authors: Liu D. R. 
Published: March 2022

Abstract
During its service, an electronic module often experiences a wide range of temperature variations. This would cause a large thermal strain in the solder joints which connect components to a printed wire board (PWB) in the electronic module if the difference of the coefficients of thermal expansion between the components and the PWB is large. On the other hand, the temperature range experienced by the solder material is typically about 50% to 80% of its melting temperature. Under this circumstance, the solder joints would experience repeated creep. The accumulation of the creep damage would fracture the joints. Eventually, they would fail by the separation of the joint.
Mechanism of Thermo-Solutal Transport and Segregation in High Pressure Liquid-Encapsulated Czochralski Crystal Growth
Authors: Zou Y. F. , Wang G.-X. , Zhang H. , Prasad V. 
Published: March 2022

Abstract
The mechanism of dopant transport and segregation in high pressure liquid-encapsulated Czochralski (HPLEC) grown III-V compound crystals (e.g., GaAs, InP) has been numerically studied using an integrated model, MASTRAPP. Based on the physics of the growth processes, a two-time-level scheme has been implemented where dopant transport and growth are simulated at a small time-scale while flow and temperature solutions are obtained from quasi-static calculations. Detailed numerical analyses are performed under the conditions of pure crystal rotation, pure thermally-driven natural convection, and pure crucible rotation as well as for mixed flow with all of these forces present simultaneously. The dopant transport and segregation in these cases are well correlated to the corresponding melt flow pattern. Very weak radial segregation is predicted for pure crystal rotation because the resulting melt flow leads to a fairly flat solute boundary layer. The natural convection, on the other hand, produces a non-uniform boundary layer along the melt/crystal interface. This leads to a strong radial segregation with a high concentration along the central axis of the crystal. The crucible rotation has a similar effect. The combined effect of all of these flow mechanisms produces a strong radial segregation, whose extent depends on the relative strength of the driving forces. The crystal rotation is helpful in suppressing the radial segregation. In all of these cases, strong melt flows lead to thin boundary layers that result in decreased longitudinal segregation. The pulling rate also has a strong influence on segregation and the slower the crystal is grown, the lesser is the effect. On the other hand, the effect of variation in partition coefficient is weak when its value is low. The predictions agree well with the experimental observations reported in the literature.
Interface Propagation and Free Convection in Alloy Solidification
Authors: Simpson James E. , Garimella Suresh V. 
Published: March 2022

Abstract
The unidirectional solidification of a dilute alloy (tin-bismuth) in a two-dimensional rectangular cavity is investigated. A uniform computational grid is employed. A vorticity-vector potential representation is used for the governing equations for the velocity field. The interface compatibility conditions for vorticity and vector potential are developed and discussed. The energy equation is solved for the temperature field, while the species equation is solved for the solute distribution. The constitutive equations are solved using a true transient method. The solution scheme incorporates an Alternating Direction Implicit (ADI) approximation for the vorticity while the conjugate gradient method is employed for the vector potential equation. The results obtained from the numerical simulations compare very well with experimental results for directional solidification in the literature in terms of the propagation of the solidification front as well as the free convection flow patterns in the liquid.
Numerical Simulation of Continuous Microwave Hybrid Heating Process
Authors: Zhang Qiong , Jackson Tom H. , Ungan Aydin 
Published: March 2022

Abstract
This study developed a numerical model to simulate a continuous hybrid microwave heating process using a single-mode microwave resonant cavity. A hybrid heating process combines the volumetric energy deposition from microwaves with a convective heat flux at the surface. This combination of heating mechanisms may be used to produce more uniform temperature distributions than either method alone. A Finite Difference Time Domain (FDTD) technique was used to model the electric field distribution. The field strength data allowed power deposition to be approximated and the control volume method was used to solve the energy equation. Temperature dependence of dielectric properties was simulated through an iterative process. This simulation showed that hybrid heating schemes can be used to increase uniformity of the temperature distribution and reduce incidences of thermal runaway.
Pulsed Laser-Induced Ablation of Absorbing Liquids and Acoustic-Transient Generation
Authors: Kim Dongsik , Grigoropoulos Costas P. 
Published: March 2022

Abstract
The mechanisms of pulsed laser-induced ablation of strongly absorbing solutions and generation of acoustic transients are described in this paper. Aqueous solutions of K2CrO4 are irradiated by a KrF excimer laser (λ = 248 nm, FWHM = 24 ns) with moderate energy density below the plasma-formation threshold. The ablation process including the vapor cavity formation and the acoustic-wave propagation is visualized by laser flash photography. The generated pressure transients are measured using a broadband piezoelectric pressure transducer. Simultaneous optical transmission detection is also carried out in order to elucidate the vapor-phase kinetics. The mechanisms of liquid ablation and acoustic-pulse generation are investigated based on the thermoelastic behavior of the liquid medium and the evaporation dynamics. The results show that the ablation is initiated by cavitation driven by the tensile component of the produced thermoelastic stress. Three distinct stages are identified in the ablation process: the initial stage with negligible surface deformation and ejection of a small amount of vapor, the second stage with violent vapor plume and bulk liquid jet ejection that is accompanied by significant surface deformation, and the final stage of large scale hydrodynamic motion. The pressure transient is generated thermoelastically at low laser fluences, but the contribution of the vapor phase expansion and / or recoil momentum exerted by the ablation plume becomes dominant at high laser fluences.
Laser Heating of Metal Targets Including the Influence of the Background Pressure
Authors: Jeong S. H. , Greif R. , Russo R. E. 
Published: March 2022

Abstract
Unsteady vaporization of a metal target due to nanosecond pulsed laser heating when an ambient gas of finite pressure exists was studied numerically. A one dimensional model for target heating and for the gasdynamic flow of the vapor was employed including an analysis of the vapor motion inside the Knudsen Layer (KL). For single pulse laser heating of an aluminum target, it was found that the threshold laser fluence for evaporation of the target is greatly dependent upon the target surface reflectivity. The threshold laser fluence predicted by a thermal evaporation model is larger than the values obtained experimentally. The local Mach number of the vapor at the edge of the KL becomes equal to unity at the beginning of evaporation only when the ambient pressure is sufficiently small; for large ambient pressures, the Mach number of the vapor during the early period of evaporation decreases first and then increases to a local sound velocity. An acceleration of the gasdynamic flow during the early period of evaporation was found and attributed to the unsteady adiabatic expansion.
Condensation Heat Transfer of R-134a in Helicoidal Pipe
Authors: Zaki M. , Liu Y. Z. , Xin R. C. , Dong Z. F. , Ebadian M. A. 
Published: March 2022

Abstract
Following the Montreal Act/Protocol of 1990, which calls for the complete phase out of chloroflorocarbon (CFC) production by the year 2000, increasing attention has been placed in recent years to improving the thermodynamic performance of heat exchangers by using non-azeotropic refrigerant as the working fluid. As a result, the currently used refrigerant, R-12, should be replaced with R-134a. However, R-134a is thermodynamically about 20 to 30 percent less efficient than R-12 in heat exchangers. Helically coiled tubes provide a simple and effective means of augmenting heat transfer. However, the effective design of a helically coiled condenser for refrigeration and air conditioning applications requires knowledge of the optimum configuration of helical coil geometry and the data on condensation heat transfer coefficients to achieve the maximum heat transfer rate. Therefore, an experimental study of condensation of pure R-134a refrigerant inside a helicoidal pipe has been carried out. Experimental heat transfer data are reported in this paper for the condensation of R134a in a helicoidal pipe that measured 12.7 mm at the inner tube and 25.4 mm at the outer tube. The test section was well insulated from the surroundings by two layers of fabric glass. The heat transfer coefficient was calculated from the measured fluid temperatures based on the energy conservation principle.
Experimental Study of Two-Phase Flow in a Hemispherical Annular Gap With Boiling on One Side of the Channel
Authors: Liu Y. C. , Shih Y. C. , Cheung F. B. 
Published: March 2022

Abstract
The phenomenon of nature convection boiling on the outer surface of a heated hemispherical vessel surrounded by a thermal insulation structure was investigated experimentally. The objectives were to observe the behavior of the boiling-induced two-phase motion in the annular gap between the vessel and the insulation structure and to determine the flow effect on the rate of boiling. High-speed photographic records revealed the presence of violent cyclic ejection of the vapor masses generated by boiling on the vessel outer surface which resulted in a buoyancy-driven, upward, concurrent two-phase flow through the channel. When boiling was taking place at high heat flux levels, the flow was found to be three-dimensional with swirl formation. Measurements of the local boiling heat fluxes and the local wall superheats were made under steady-state boiling conditions covering the entire range of nucleate boiling with special emphasis on the high-heat-flux regime.
Thermal Hydraulic Instabilities During Startup Transients in Two Heated Parallel Channels
Authors: Paniagua J. C. , Rohatgi U. S. , Prasad V. 
Published: March 2022

Abstract
In multiple channel systems, channel dynamics can be coupled to one another and be independent of the remaining flow loop or one unstable channel may dominate the transients and make the multiple parallel channel system behave as one single channel. In the single channel case, the whole loop participates in the flow oscillations, whereas in a two parallel channel system the flow oscillations occur in the channels and can be out-of-phase. Previous studies indicated the instabilities are due to condensation in a low pressure natural circulation two parallel channel loop at low powers and inlet subcoolings. A thermal hydraulics computer code was developed to simulate the geysering instability and is based on integral methods where local properties are based on local pressures and the vapor generation model is adjusted accordingly to reflect the vapor generation rate necessary to initiate the instability. This is an important modeling feature since local vapor generation rate depends on local saturation temperature. The code is designed to simulate startup transients in two heated parallel channel natural circulation systems with subcooled water as an initial condition. The numerical simulations illustrated flow reversal in the individual channels, which is a thermal hydraulic feature of condensation-induced geysering.
Evaluation of Prompt Nucleation of Bubbles in Annular Fuel Elements During the Initial Depressurization Transient of a DEGB LOCA
Authors: Smith Allen C. 
Published: March 2022

Abstract
In the first moments of a DEGB LOCA, the depressurization wave may result in the system pressure falling below the saturation pressure of the coolant resulting in bubble formation. Immediate formation of bubbles might result in flow instability, with the affected fuel element unable to survive the LOCA. Nucleation of bubbles can occur by either pressure undershoot, or liquid superheat in the boundary layer adjacent to hot surfaces. This investigation developed a method for evaluating the possibility of occurrence of bubble formation as a result of this initial depressurization. The method developed was based on bubble nucleation models and experimental results. The results show that the superheat required for prompt nucleation, within the initial period between the depressurization wave and the re-pressurization wave, is much greater than the available superheat in the subject fuel element, either measured experimentally or calculated by RELAP. Accordingly, prompt nucleation would not occur in the subject fuel element in this initial time period.
Flow Boiling Heat Transfer of Kerosene Inside Ribbed Tube
Authors: Cheng Lixin , Chen Tingkuan , Luo Yushan 
Published: March 2022

Abstract
Results of a study on flow boiling heat transfer enhancement of kerosene with ribbed tube (rib pitch 9 mm, rib height 0.4 ∼ 0.6 mm, rib width 3.9 mm) are reported. Experiments of upward flow boiling heat transfer in smooth tube and ribbed tube at a pressure 2 bar were performed for a range of heat flux (28.5 ∼ 93.75 kW/m2), mass flux (410 ∼ 810 kg/m2 s) and equilibrium mass quality (0 ∼ 0.3) respectively. Heat transfer coefficients in the ribbed tube are improved by a factor of 1.4 ∼ 1.6 as compared with the smooth tube. A correlation of flow boiling heat transfer coefficients is proposed for the enhanced ribbed tube. Phenomenon and mechanism of flow boiling heat transfer with kerosene are discussed.
Experimental Investigation of Metallic Fibrous Heat Sinks for External Cooling of an Electronic Package
Authors: Angirasa D. , Pyrtle F. , Peterson G. P. 
Published: March 2022

Abstract
Preliminary results of an experimental study to test the effectiveness of metallic fibrous heat sinks for electronic cooling applications are presented. In these initial measurements, low heat inputs were employed. Within a higher range of porosity of the aluminum fibrous sinks, lower porosities lead to lower thermal resistance and higher heat transfer rates. Over a range of Reynolds number, the surface to ambient temperature difference remains fairly constant indicating the possibility that, with the use of fibrous heat sinks, low velocities are enough to keep the surface temperature to a desired value.
An Experimental Study of Upward Flame Spread in a Vertical Corner Wall Fire
Authors: Powell Amy M. , Kulkarni Anil K. 
Published: March 2022

Abstract
This paper presents results of an experimental investigation of upward flame spread on a vertical corner wall. The corner wall flame spread phenomenon differs from that for a plain vertical wall primarily because of the radiative and flow interaction between the walls. An experimental apparatus, capable of being set at corner angles of 60°, 90°, and 135° was designed and constructed. Samples, measuring 1.20 m by 0.30 m, of plywood, particle board, and hardboard were tested. Three burner configurations were used during experimentation — an arrow configuration, a line configuration, and a point source. Flame height as a function of time was measured during each run. Several trends were observed including — the significance of the burner configuration when determining flame shapes; the relationship between radiative interaction and different corner angles; and the capability of each material to sustain flame growth once the burner was turned off. Also, the pyrolysis front was noted at the conclusion of each test run using the charred region apparent on the sample, which revealed the dependence of the shape of pyrolysis front on the burner configuration. The study allows insight into various aspects of corner fire spread and provides data for validating flame spread models.
A Numerical Analysis of a Conical Swirl-Stabilized Spray Burner
Authors: Stojkovic Boris D. , Acharya Sumanta , Morgan Tim G. , Zanca Kevin J. , Graf Michael J. , Gutmark Ephraim 
Published: March 2022

Abstract
Numerical calculations of the droplet dispersion in a conical spray burner are presented. A commercial CFD code, FLUENT, is used to execute the numerical calculations. The burner has the shape of a cone, which is offset in four places. These four gaps allow for secondary air injection into the burner region, and provide a high level of swirl. The fuel spray, together with coaxial primary air, in both co-swirl (primary air swirling in the same direction as the secondary air), and counter-swirl configuration are introduced at the base of the burner. Results indicate that the counter-swirl configuration leads to uneven fuel distribution and local pockets of high stoichiometry. Increasing the swirl ratio between the primary and secondary stream enhances the central recirculation region that is likely to promote flame stability, but adversely affects the mixing and fuel distribution. Increasing air to fuel flow momentum ratio leads to low droplet dispersion but higher turbulent level.
Vapor Condensation Processes Associated With Premixed Flame Quenching
Authors: Ezekoye O. A. 
Published: March 2022

Abstract
Although unsteady flame quenching is a classical combustion problem, several key features of the process have yet to be understood. As an example, for an unsteadily propagating flame (away from the flammability limits) stagnating on a cold wall, there has not been conclusive experimental and theoretical agreement on the effects of varying the thermal boundary conditions on the flame extinction process. Characterization of the flame quenching problem is exacerbated by the length scales over which it occurs. The flame quenching distance for single sided flame quenching at atmospheric pressures is on the order of hundreds of micrometers, and thus few diagnostics can be used to determine the extent to which the flame propagates towards a specified temperature wall. The most meaningful diagnostics to date for such processes have been heat transfer measurements of the wall heat flux as the flame quenches. These diagnostics although second hand, provide information about the flame trajectory during a given quenching process. Even in the absence of detailed species description of the quenching process, several interesting features are noted as a result of the evolution of major species. The effect of water condensation during flame quenching which is examined in this study has been neglected in many studies of flame quenching. It is shown that coupling water condensation to the quenching process modifies both the extinction chemistry and also the wall heat flux measurement.