bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redesign of Spherical Acrylic Submersible for Manned Operation to 3000 ft (914.4 m) Ocean Depth
Authors: Das Partha S. 
Published: November 2021

Abstract
Harbor Branch Oceanographic Institution (HBOI) is using its spherical acrylic manned submersible for ocean exploration for last 3 decades. However, the development of tiny shear cracks at the interface areas of these submersibles following only few hundred dives require frequent, expensive repairs. To overcome this crack generation problem, a two-Phase research program is initiated at HBOI. In the Phase I of this study, a detailed nonlinear 3-D Finite Element Analysis (FEA) is performed at first to increase the understanding of the mechanical behavior at the interface of this submersible and then various analyses are carried out to develop a guidelines for redesigning the spherical acrylic submersible. Complete redesigning of the bottom of acrylic submersible is only presented here in details, as the discussion on the top of acrylic submersible is presented earlier.
Based on the new design guidelines, in the Phase II of this study, a new spherical acrylic submersible is fabricated at HBOI. Brief discussion of the experimental results on the new submersible is also presented here. A significant reduction in peak stresses and a very small relative displacement at the gasket/acrylic interface which are believed to be two of the main causes for crack development at the interface areas clearly indicate a major improvement in the new design of the acrylic submersible, as they are also suggested by the extensive FEA results. This improvement in design is expected to extend the crack free cyclic fatigue life of the acrylic submersible at 3000 ft (914.4 m) ocean depth significantly.
Predicting the Large Deflection Path of End-Loaded Tapered Cantilever Beams
Authors: Parkinson Matthew B. , Roach Gregory M. , Howell Larry L. 
Published: November 2021

Abstract
A simple (quadratic) mathematical model for predicting the deflection path of both non-tapered and continuously tapered cantilever beams loaded with a vertical end force is presented. It is based on the proposition that the path is a function of the ratio of the endpoints’ moments of inertia. The model is valid for both small and large (the tip makes a 70 degree angle with the horizontal) deflections. This was verified through physical testing, comparison to solution of the Bernoulli-Euler equation, and results obtained through nonlinear finite element analysis. Predicted endpoint deflections were found to be accurate within 1.8% of the actual deflection path for moment of inertia ratios varying from 1:1 to 1000:1.
Effect of Electric Field on Flow Pattern in Flow Boiling of R-134a: A Visualization Study
Authors: Salehi Mohsen , Molki Majid , Ohadi Michael 
Published: November 2021

Abstract
An experimental study was performed to qualitatively investigate the effect of an applied electric field on two-phase flow patterns in convective flow boiling of R-134a inside a channel. The experiments were performed in a horizontal channel with 3 mm hydraulic diameter. Inlet vapor qualities of 5%, 40%, and 80% at a flow Reynolds number of 1000 and heat flux of 20 kW/m2 are reported here. The flow regimes were analyzed by a high-speed digital camera. The camera could provide a frames speed of up to 3025 frames/s. The electric field was maintained between the upper and lower walls of the channel. The current visualization study suggests some definitive characteristics of the flow regime and the mechanism behind the EHD-enhanced convective boiling in a narrowly-spaced channel. It is found that at the lower range of applied potential, the flow patterns change from stratified wavy flow to a plug flow type with large slugs spanning the height of the channel. At the higher range of applied potential, a new flow regime took place. This flow pattern was associated with the cross motion of the liquid inside the channel. One reason for heat transfer enhancement can be attributed to the strong heat/momentum transfer between the vapor slugs and liquid cross motions.
Surface Tension Driven Film Flow due to Condensation With a Vapor Borne Surfactant
Authors: Qiao R. , Yuan Z. , Herold K. E. 
Published: November 2021

Abstract
In absorption chillers, it is well known that the presence of small amounts of alcohol can enhance the absorber heat and mass transfer significantly. Similar enhancement is also observed in the condenser. Among the theories to explain such phenomena, the recently described Vapor Surfactant theory provides the most comprehensive explanation of the available data. According to this theory, the surfactant arrives at the liquid surface primarily from the vapor. As the water vapor flows toward eventual absorption/condensation, it carries the vapor borne surfactant toward the surface. Once the surfactant arrives at the surface, it tends to concentrate there due to its low solubility and low diffusivity in the liquid as well as the natural affinity of a surfactant for the surface. Non-uniform surface concentration of the surfactant leads to surface tension forces in the liquid surface layer that drive the surface flows often observed. These Marangoni flows are what enhance the heat and mass transfer processes. Although it was often theorized that Marangoni flow plays a role in enhancement, the important role of the vapor has not been well understood. A number of previous attempts have been made to compute Marangoni flow but all such attempts have assumed that the surfactant transport in the liquid is the key. This paper presents calculations of liquid film flows driven by the surfactant as it arrives at the surface from the vapor. This completely new model involves several very interesting features.
A two-dimension numerical simulation of such a flow is reported here. The geometry is a thin film (3mm × 10cm) of liquid water with a small patch of cooling centered on the bottom side. The upper surface is exposed to steam+surfactant vapor so that condensation will occur. The model computes the surface concentration of surfactant and relates that to the surface tension. Calculations show that the condensation rate is much higher when Marangoni convection is occurring, even if the surfactant concentration in the vapor is very small (120ppm). This is in accordance with observations in absorption chillers. The result helps to clarify understanding of surfactant-induced enhancement of heat and mass transfer in absorption chillers.
Thermoeconomic Analysis of a Dual-Purpose Power and Desalination Plant
Authors: Uche Javier , Serra Luis , Valero Antonio 
Published: November 2021

Abstract
Thermoeconomic analysis techniques are very convenient tools to be applied in the analysis of highly complex systems as it is proved in this paper. A thermoeconomic analysis has been applied to an actual dual-purpose power and desalination plant considering the dual plant as a whole system. Probably due to its complexity, this type of plants are usually analyzed separately, considering the power and the desalination plant as two independent systems, thus neglecting component interactions and avoiding the potential energy saving derived from the combined analysis.
The most important aim of this paper consists on checking the validity of thermoeconomic analysis when applied to actual complex energy systems.
Thus, this paper contains some of the most important results of a research work [1] in which a critical analysis of thermoeconomic applications when applied to actual complex energy systems, as a dual plant is. The paper is focused on (a) the thermoeconomic diagnosis of the plant operation, in which the interactions between the plant components have been studied and quantified in terms of additional fuel consumption, efficiency variation, and so on; (b) the optimization of the plant by maximizing the installation benefit, which is a consequence of the thermoeconomic cost analysis..
Life Cycle Assessment of a Solid Oxide Fuel Cell Integrated With a Gas Turbine
Authors: Olausson Pernilla L. 
Published: November 2021

Abstract
The solid oxide fuel cell (SOFC), alone and integrated with a gas turbine (SOFC/GT), is known for its high electrical efficiency and low emissions during operation. Before the SOFC/GT operation phase, the process life cycle also includes the extraction of ores, production of materials and components, and demolition, all these together with their intervening transports. By performing a life cycle assessment (LCA) for the SOFC/GT, the total environmental impact of the process is established and environmental “hot spots” are found.
The results of the LCA of the SOFC/GT process showed that the most contributing phase to environmental impact, within all investigated impact categories during the life cycle, is the production of the SOFC-module. The pyrolysis processes of raw materials and the assemblage of the SOFC sub-components require an extended amount of energy. Of course, both these processes are carried out under laboratory circumstances, but even when the use of energy is reduced by 50%, this phase is more dominant than other power producing processes. Further effort has to be put into development of materials and manufacturing processes in order to reduce the resources used during the production phase of the SOFC.
Optimal Operation in CHP Systems: Using Mathematical Programming and Heuristic Rules
Authors: Iversen Frank Krogh , Nielsen Anders Busk , Nielsen Mads Pagh , Andersen Jens , Grue Jeppe , Bach Inger 
Published: November 2021

Abstract
The power generation system in Denmark is extensively based on small combined heat and power plants (CHP plants), which produce both electricity and district heating. This work deals with smaller plants spread throughout the country. Often a heat accumulator is used to enable electricity production, even when the heat demand is low. This system forms a very complex problem, both for dimensioning, designing and operation of CHP plants. The objective of the work is the development of a tool for the optimization of the operation of CHP plants. The optimization problem is a MINLP-problem of a very large scale. Therefore, a set of heuristic rules is formulated in order to reduce the size of the problem. Different cases are being tested, involving CHP producing units to cover the demand. The results show that it is of major importance to consider the operation of the plant in detail already in the design phase. It is of major importance to consider the optimization of the operation of a plant, even at the design stage, as it may cause the contribution margin to rise significantly, if the plant is designed on the basis of a detailed knowledge of the expected operation.
Influence of Different Sets of Measurements on Gas Turbine Field Performance Determination
Authors: Pinelli M. , Spina P. R. 
Published: November 2021

Abstract
The paper presents a method for evaluating the influence of different sets of measurements (in terms of number and kind) on gas turbine health determination. It is analyzed how the uncertainty of measurements and variations occurring on the characteristic parameters, which have to be fixed to solve the problem, affect the health parameter estimation. The study, which was developed for different combinations of measurements and fixed characteristic parameters, leads to the identification of:
- the best set of measurements for the determination of the gas turbine operating state;
- the most appropriate characteristic parameters to fix, depending on available measurements.
The Water Membrane Evaporator for Space Shuttle Heat Rejection: Membrane Performance and Plans for Pre-Prototype Testing
Authors: Ungar Eugene K. , Almlie Jay C. 
Published: November 2021

Abstract
The US Space Shuttle on-orbit waste heat rejection is currently accomplished through a combination of radiators and a Flash Evaporator System (FES). Three of the FES units have been rebuilt to date because of corrosion problems. In addition, the FES has experienced freeze-ups on-orbit.
As part of NASA’s Orbiter Upgrade Program, a Water Membrane Evaporator (WME) is being developed as a replacement for the FES. The WME will use hydrophobic micropore membrane technology to passively control a water liquid/vapor interface. Waste heat acquired from the Orbiter Freon-21 coolant loop will evaporate water at the interface. The water vapor will pass through the membrane and be vented to space. The WME program takes advantage of the recent advances in hydrophobic micropore membrane technology to provide a simpler and more robust heat rejection device than the current FES.
The WME design uses a hydrophobic and hydrophilic membrane layup over 60 rectangular stainless steel Freon-21 tubes in each of 80 small cores to perform the same function as the FES. The mass and volume of the WME design is comparable to that of the FES.
In the present work, the results of membrane performance tests are presented, the membrane physics are explored, and a membrane performance prediction is developed. The WME design is described in detail and the predicted performance of the WME design is compared to that of the FES.
Velocity Measurements and Visualizations of the Flow Driven by Laser-Induced Cavitation Bubbles in a Blood-Like Liquid
Authors: Molho Joshua I. , Hung Chiao-Chuan , Santiago Juan G. , Levine Marc-Alan , Esch Victor 
Published: November 2021

Abstract
A method for imaging and velocimetry of flows, in small volumes of blood-like liquid is presented. This method allows for imaging of fast moving blood flows (1 to 10 m/s) in volumes on the order of a cubic millimeter. A custom laser light source was developed that provides pulsed illumination at 640 nm. This light source is required by the transmission properties of the blood-like liquid and has other advantages for epi-fluorescence imaging. This custom-built PIV system was used to image the flow caused by a laser induced cavitation bubble. The measurements show the important features of this flow including the high-speed radial collapse of the bubble, the asymmetric collapse of the bubble caused by the presence of the fiber and the presence of a jet that traverses the bubble.
Electroosmotic Flow Field Measurements With Particle Image Velocimetry
Authors: Devasenathipathy Shankar , Molho Joshua I. , Mikkelsen James C. , Santiago Juan G. , Takehara Kohsei 
Published: November 2021

Abstract
A micron-resolution particle image velocimetry (PIV) system has been developed to spatially and temporally resolve electroosmotic flow fields within microfluidic bioanalytical devices. A second diagnostic technique, particle tracking velocimetry (PTV) has been used to determine the distribution of electrophoretic mobilities of seed particles and thereby make the PIV measurements quantitative. This second particle tracking technique has been used to determine probability distribution functions of the seed particles. Results from simulations of electric fields yield local electric field strengths in the geometries of interest. The measured mean mobility of the seed particles (obtained from PTV measurements) is then multiplied by the local electric field vector to obtain the electrophoretic velocity. The variance on the particle mobility measurement influences the errors introduced in the electroosmotic flow measurements. After total particle velocities are measured within a microfluidic system of interest, the seed particle electrophoretic velocities are subtracted from the PIV total velocity data to obtain electroosmotic flow field velocities. Ensemble-averaged velocity field measurements for electroosmotic flow at the intersection of a cross-channel are presented.
Thermal Performance of a Residential Basement
Authors: Emery A. F. , Heerwagen D. R. , Kippenhan C. J. , Steele D. E. 
Published: November 2021

Abstract
This paper describes the measurement of ground and internal wall temperatures, local surface heat fluxes on the basement walls and floor, and overall heat losses for a concrete wall basement. The heat fluxes were measured with heat flux meters and mimic boxes. Daily and seasonal measured performances are displayed. A portion of the walls was covered with additional insulation. This allowed comparison of insulated and non-insulated basements and showed that a modest amount of insulation could reduce the annual heat loss by approximately 50%. The local fluxes are shown to vary significantly with depth and the insulation was most effective when applied to the upper wall surface which communicated with the ambient air through a relatively short path through the earth near grade level. Temperature stratification effects are shown to be important, especially with respect to floor heat fluxes.
Transferred-Substrate InGaAsP-Based Thermionic Emission Coolers
Authors: LaBounty Christopher J. , Robinson Gerry , Abraham Patrick , Shakouri Ali , Bowers John E. 
Published: November 2021

Abstract
Most optoelectronic devices are based on III-V semiconductors such as the InP/InGaAsP material system. Solid state refrigerators based on the same material system can be monolithically integrated with optoelectronics. Thermionic emission cooling in InGaAsP-based heterostructures has been shown experimentally to provide cooling power densities of several 100 W/cm2. Cooling by several degrees across thin films on the order of a micron thick has been demonstrated. Thermionic emission of hot electrons over heterobarriers allows for enhanced cooling power beyond what is possible from the bulk thermoelectric properties. The thermal resistance of the InP substrate between the hot side of the thin film cooler and the heat sink is found to be a limitation in cooler performance. Several possibilities are examined for replacing the InP substrate with a higher thermally conducting one such as silicon, copper, or even diamond, and a process for substrate transfer to a thin copper film has been developed. Three-dimensional simulations predict an order of magnitude improvement in the thermal resistance of the substrate. Experimental results of packaged InGaAsP coolers with copper substrates will be discussed.
Design of Thin-Film Thermoelectric Microcoolers
Authors: Yao D.-J. , Kim C.-J. , Chen G. 
Published: November 2021

Abstract
Thin-film thermoelectric devices have potentially higher efficiency than bulk ones due to quantum and classical size effects of electrons and phonons. In this paper, we discuss the design of thin-film thermoelectric microcoolers for achieving high performance. The devices considered are membrane structures based on electron transport along the film plane. A model is developed to include the effects of heat loss and leg shape. Design optimization is performed based on the modeling results.
Interplay Between Thermoelectric and Thermionic Effects in Heterostructures
Authors: Zeng Taofang , Chen Gang 
Published: November 2021

Abstract
When electrons sweep through a double-heterojunction structure, there exist thermionic effects at the junctions and thermoelectric effects in the film. While both thermoelectric and thermionic effects have been studied for refrigeration and power generation applications separately, their interplay in heterostructures is not understood. This paper establishes a unified model including both thermionic and thermoelectric processes based on the Boltzmann transport equation for electrons, and the nonequilibrium interaction between electrons and phonons. Approximate solutions are obtained, leading to the electron temperature and Fermi level distributions inside heterostructures and discontinuities at the interfaces as a consequence of the highly nonequilibrium transport when the film thickness is much smaller than the electron mean free path. It is found that when the film thickness is smaller than the mean free path of electrons, the transport of electrons is controlled by thermionic emission. The coexistence of thermoelectric and thermionic effects may increase the power factor when the electron mean free path is comparable to the film thickness.
Leakage Flow and Heat Transfer Over Shrouded Turbine Blades
Authors: Xiao Yumin , Amano R. S. 
Published: November 2021

Abstract
In this paper a high efficiency labyrinth seal and the staggered labyrinth seal for shrouded blades was presented. The flows in the seal with single, double, and triple tip seals were simulated by solving the two-dimensional Reynolds-averaged Navier-Stokes equations (RANS) and a compressible k-ε turbulence model. A multi-zone technique was used to generate the grids in the complex flow channel. The calculation results showed that the presently proposed staggered labyrinth seal is more efficient than the typical one and the leakage flow rate is dominated by the minimum flow area and the pressure difference. Comparing the performance with the typical labyrinth seal, the present staggered labyrinth seal model can average the total pressure drop among the seals, while the typical one induces a sharp drop across the first tooth. It showed that the leakage flow rate varies as a function of the number of seals to the power of −0.45. For the cases of multiple-seals the space between two seals has little effect on the total mass flow rate. Finally, decreasing the wall temperature will result in an increase of leakage flow.
Thermoelastic Wave Induced by Pulsed Laser Heating
Authors: Wang Xinwei , Xu Xianfan 
Published: November 2021

Abstract
In this work, a generalized solution for the thermoelastic plane wave in a semi-infinite solid induced by pulsed laser heating is formulated in the form of Fourier series. The solution takes into account the non-Fourier effect in heat conduction and the coupling effect between temperature and strain rate, which play significant roles in ultra-short pulsed laser heating. Based on this solution, calculations are conducted to study stress waves induced by different laser parameters. It is found that with the same maximum surface temperature increase, a shorter pulsed laser induces a much stronger stress wave in a solid. The non-Fourier effect causes a higher surface temperature increase, but a weaker stress wave. The surface displacement accompanying thermal expansion shows a time delay to the laser pulse in femtosecond laser heating. On the contrary, surface displacement and heating occur simultaneously in nano- and picosecond laser heating. In femtosecond laser heating, results show that the coupling effect attenuates the stress wave and extends the duration of the stress wave. This may explain the minimal damage in ultra-short laser materials processing.
Thermal Modeling for the Consolidation Process of Thermoplastic Composite Filament Winding
Authors: Loos Alfred C. , Song Xiaolan 
Published: November 2021

Abstract
The quality of thermoplastic composites depends on the thermal history during processing. Therefore it is important to determine the temperature distribution in the composite during the fabrication process. The objective of this investigation was to develop a comprehensive thermal model of the thermoplastic filament winding process. The model was developed in two parts to calculate the temperature profiles in the towpreg and the composite substrate. A finite element heat transfer analysis for the composite-mandrel assembly was formulated in the polar coordinate system, which facilitates the description of the geometry and the boundary conditions. A four-node ‘sector element’ is used to describe the domain of interest. Sector elements were selected to give a better representation of the curved boundary shape which should improve accuracy with fewer elements compared to a finite element solution in the Cartesian-coordinate system. The second thermal analysis was a Cartesian coordinate, finite element model of the towpreg as it enters the nippoint. The results show that the calculated temperature distribution in the composite substrate compared well with temperature data measured during winding and consolidation. The analysis also agreed with the experimental observation that the melt region is formed on the surface of the incoming towpreg in the nippoint and not on the substrate.