bluuebunny/crossref_metadata_2025_split huggingface dataset:
Supraphysiological Thermal Injury in Dunning AT-1 Prostate Tumor Cells
Authors: Bhowmick Sankha , Bischof John C. 
Published: January 2022

Abstract
Supraphysiological temperatures are generated by radiofrequency and microwave probes used for the treatment of prostate cancer (Montrosi et al., 1992) and benign prostatic hyperplasia (Larson et al., 1996). A quantitative understanding of the cellular mechanisms of tissue destruction due to these supraphysiological temperatures(&gt; 40°C) is necessary for optimal application of clinical therapeutic protocols on the prostate and other tissue systems. A multitude of biophysical and biochemical events take place at the cellular level due to thermal stress (Cravalho et al., 1992). Some of the events include hyperpermeability of the membrane, denaturation of proteins, changes in cytoskeleton, alteration of intracellular ionic concentration and nuclear degradation. This study quantifies membrane injury by measuring the dynamics of vital dye leakage (Calcein) and Propidium Iodide (PI) uptake in the AT-1 Dunning rat prostate tumor cell line. Membrane injury (using these two dyes) is compared to the clonogenicity of these cells after comparable thermal insult. An Arrhenius damage model has been constructed for each of these assays based on a damage parameter to obtain the activation Energy (E) and frequency factor (A), which may prove useful in obtaining insight into the mechanisms of damage associated with thermal injury.
Interstitial Electrolyte Infusion Creates a Liquid Electrode for Controlled Application of High Power Radiofrequency Energy
Authors: Hoey Michael F. , Paul Saurav 
Published: January 2022

Abstract
Conventional application of radiofrequency (RF) energy for thermotherapeutic ablation of pathological tissue is limited by tissue desiccation, high electrical impedance, and small lesion size. A new method has been developed which allows controllable production of small to large lesions. This technique modifies the electric field within the tissue by interstitially infusing hypertonic saline during the application of RF energy. The present study was conducted to determine the spread of saline in prostate and resultant impedance changes. A 26 gauge needle with 5mm exposed metal tip was inserted into the prostate of 10 canines. Impedance measurements were made between the two recording electrodes placed 12mm apart, with the infusion electrode at the center. Hypertonic saline (14.6% NaCl) with a 35% mixture of a radiocontrast agent (Hypaque) was continuously infused at 2 ml/min through the needle electrode into the tissue for 10 minutes. Fluoroscopic images were taken concomitantly with impedance measurements. The images were analyzed for intensity and spread of the saline concentration field. The developed concentration field was observed to modify the impedance characteristics, thereby indicating the creation of the saline-liquid electrode. This research has facilitated the development of RF hyperthermic treatment for benign prostatic hyperplasia in humans.
An Experimental Model for Investigating Mechanotransduction in Cells: Formation of 3-D Colonies and Differentiation of Cells in the Presence of a Force-Conducting Ligand
Authors: Bhatnagar Rajendra S. , Qian Jing Jing , Wedrychowska Anna , Smith Nancy 
Published: January 2022

Abstract
Microgravity profoundly affects the physiology of cells. The formation of 3-D arrays by cells in microgravity environments has provided novel approaches to tissue engineering. In order fully to understand the relationship between cells and their mechanical environment, it is crucial to replicate the physiological pathways involved in the transduction of mechanical energy to chemical work. Cell behavior is modulated by exogenous and biogenic mechanical forces. One of the major mechanisms that couple mechanical signals in these tissues to an intracellular apparatus for the regulation of cell behavior involves the conduction of mechanical signals via an extensive network of collagenous extracellular matrix. Specialized receptors connect cells to collagen fibers. The junction between the ECM, its receptor integrins, and the cells’ cytoskeleton plays a crucial role in cell differentiation and morphogenesis by serving as the agent for sensing the mechanical environment. We have developed an experimental model system that allows the coupling of cells to their mechanical environment through a force transducing ligand. This system has allowed us to construct 3-D colonies of cells in which cells appear to express highly differentiated function. Such systems are likely to be useful in studies on the behavior of biological systems in the microgravity environment of space.
Numerical Study of Mass Transfer Associated With Multiple Microcarriers in a Rotating-Wall Vessel
Authors: Gao Hongxia , Ayyaswamy Portonovo S. , Hu Howard H. , Zhu Mingyu , Ducheyne Paul 
Published: January 2022

Abstract
The motion of multiple microcarriers in the liquid cell culture medium of a NASA designed Slow Turning Lateral Vessel (STLV) has been numerically investigated. The associated mass transfer has been studied using a ‘sink-model’. A finite element method is employed to directly simulate the motion of a number of solid microcarrier particles. The motion of the combined fluid-particle system is simulated by using a procedure in which the positions of the microcarriers and of the unstructured mesh grids are updated explicitly, while the velocity and pressure of the fluid and the velocity of the microcarriers are determined implicitly. The migration of the particles is affected by the interaction between them and with the walls. The hydrodynamic forces on the microcarrier particles are also evaluated. The mass transfer is treated as a post-processing procedure by solving the binary mass transfer equation. We provide results for the oxygen mass fraction distribution as a function of time taking into account its consumption by the cells grown on the microcarriers.
Experimental and Numerical Investigations of Microcarrier Motions in Simulated Microgravity
Authors: Meaney David F. , Johnston Eric D. , Litt Mitchell , Pollack Solomon R. 
Published: January 2022

Abstract
We are interested in studying the cell/microcarrier motions within the NASA rotating bioreactor system, with the eventual goal of using this description to understand the attachment of cells on microcarriers and the assembly of these cell/bead constructs into three dimensional tissue. In this study, we used both experimental imaging tools and numerical analysis to study the motions of typical microcarrier beads used in the High Aspect Ratio Vessel (HARV). Experimental studies demonstrate that physical properties of the microcarrier beads affect directly the primary radial motion of these particles, and also show that these beads interact and aggregate with each other over time. Numerical analyses using the appropriate governing equations and a Runga-Kutta solution method show that computed results agree with experimental observations on both primary and secondary particle trajectories. From the numerical analysis, we develop an analytical description of a typical particle trajectory in the laboratory frame and develop an experimental apparatus to track a single particle temporally in the bioreactor. Results from this study provide insight into the motion and aggregation of particles in the rotary culture bioreactors over time, and can lead to a better control of the bioreactor mechanical environment.
Dynamic Optimization of Start-up and Load-Increasing Processes in Power Plants: Methodology and Application
Authors: Bausa Jens , Tsatsaronis George 
Published: January 2022

Abstract
The fast start-up and load-increasing of power plants is a complex task involving several restrictions that have to be fulfilled simultaneously. An important restriction is the maximum allowed thermal stress of the steam generator pipes and the steam turbines caused by temperature gradients.
In this paper the start-up process is treated as a dynamic optimization problem. Any appropriate objective function can be used in this optimization problem. Examples include the minimization of fuel consumption, or the minimization of the time required to reach the desired load. The maximum allowable temperature and pressure gradients in major plant components appear as additional constraints.
A general methodology for solving these problems is presented: The dynamic process model, consisting of first-order ordinary differential equations (ODEs) and algebraic equations, is discretized over the time horizon using well established methods for the solution of ODEs. Thus, the continuous dynamic optimization problem is transformed into a large-scale non-linear parameter optimization problem with up to 20,000 optimization parameters and constraints. Such parameter optimization problems can be solved with appropriate sequential quadratic programming (SQP) methods that have become available lately.
The application of this method is demonstrated by optimizing the process of rapid load-increase in a single-pressure combined-cycle power plant on the base of a simplified model.
Using Component Effectiveness for a More Comprehensive Analysis of High Temperature Fuel Cells
Authors: Haynes Comas L. , Wepfer William J. 
Published: January 2022

Abstract
High temperature fuel cells will enable power systems to have unprecedented levels of operation. Second Law studies are an effective means of analyzing these promising cells. The “non Carnot-limited” label applied to fuel cells must first be understood in its proper perspective, however. Electric and voltage efficiencies are often used for fuel cell evaluation, but a component effectiveness was developed for better insight into cell performance.
The performance indices were compared via a simulation of Westinghouse Electric’s tubular solid oxide fuel cells. Component effectiveness profiles showed a realistic, decreasing approach to reversible operation. In contrast, electric and voltage efficiencies showed a uniform increase in performance. These latter efficiencies only account for electrochemical losses. High temperature fuel cell operation involves significant heat transfer, however, and thus thermal irreversibilities. Component effectiveness accounts for all forms of entropy generation, and it will be used in subsequent design analyses of high temperature fuel cells.
Modeling of a Heat Pump With Evaporator Air Dehumidification for Reduced Frost Formation
Authors: Martínez-Frías Joel , Aceves Salvador M. 
Published: January 2022

Abstract
This paper presents an analysis of a heat pump that uses a solid desiccant dehumidifier to reduce the humidity of the ambient air that flows into the evaporator, with the purpose of decreasing frost formation on the evaporator. The heat pump is analyzed by adding a dehumidifier model to a previously developed heat pump model that includes frost formation. The dehumidifier reduces the amount of energy required for evaporator defrosting, but introduces the need for energy for regenerating the desiccant. The purpose of the analysis is to search for operating conditions and optimum dehumidifier designs for which the use of the dehumidifier results in energy savings.
The results show that the use of a dehumidifier may result in net energy savings if the energetic cost of defrosting the evaporator is high. Other benefits of dehumidification include an increase of the time intervals between defrost cycles, a better stability in the conditions in the controlled space, and the potential for increased reliability and reduced maintenance of the heat pump.
Comprehensive Modeling of Reed Valve Impact Velocity in Scroll Compressors
Authors: Lifson Alexander , Bush James W. 
Published: January 2022

Abstract
Scroll compressors are becoming popular in refrigeration applications where high pressure ratio operation is required. To achieve competitive efficiency and minimize discharge temperature, a discharge valve is often mandatory in these applications. However, the discharge valve brings with it its own reliability risk. Operation of the valve in scroll compressors in many ways is similar to rotary or reciprocating compressors, but there are specific features of the scroll compression process requiring special consideration in scroll wrap design.
This paper addresses a risk with scroll compressor discharge valve reeds in the form of sudden backflow at the time of porting which occurs at the end of discharge process. The mechanisms responsible for valve impact are evaluated and ways to minimize and to even virtually eliminate them are presented. Computer simulation results quantify the effect of design and application variables on valve impact. Two levels of analysis are presented, first a more rigorous but computationally involved approach, then a simplified method more applicable for a quick estimate or evaluation of trends. A comparison between the two analyses is presented. Effects of clearance volume, discharge pressure, suction pressure, and scroll wrap geometry on valve impact are considered. It is shown that discharge pressure and volumetric flow rate at porting have the greatest effect on the valve impact velocity against the scat. Design tradeoffs for minimizing valve impact also presented.
Refinery Waste Heat Powered Absorption Refrigeration: Cycle Specification and Design
Authors: Erickson Donald C. , Anand G. , Papar Riyaz A. , Tang Jingsong 
Published: January 2022

Abstract
In an effort to increase the energy efficiency and reduce environmental emissions from refineries, the Commerce City Refinery of Ultramar Diamond Shamrock, the Office of Industrial Technologies at the U.S. Department of Energy and a team of contractors have collaborated to implement a novel project. A waste heat fired Absorption Refrigeration Unit (ARU) was designed, fabricated, installed and is currently completing a one year field test at the oil refinery in Denver, Colorado. Data is being gathered to document the performance and compare to the predictions.
The ARU is designed to provide refrigeration for two process streams at the refinery while being powered by waste heat from a third process stream. The refrigeration benefits the refinery by recovering salable product and increasing the capacity of the process units with no additional electrical demand. The constraints to be satisfied by the ARU design were very stringent: low temperature waste heat; very low refrigeration temperature; limited plot space; geographically separated streams; and very limited cooling water. In order to satisfy all these constraints and to make the economics more favorable, several new concepts were developed and incorporated in the ARU. This paper describes the various cycles considered and the qualitative and quantitative considerations involved in screening the cycles. The parametric analysis and optimization of the most promising cycle is presented.
Applications for Advanced Energy Conversion Applications
Authors: Lamp Thomas R. 
Published: January 2022

Abstract
Forest fires that endangered remote US Air Force sites equipped with radioisotope thermoelectric generators (RTGs) prompted the assessment of power generating systems that could be substituted for RTGs in small scale (10–120 watt) applications. Other non-RTG sites were also studied during the assessment. The power system assessment was conducted by the Air Force Research Laboratory (AFRL). The evaluations included engine-driven generators, solar, wind generators, propane thermoelectric generators (TEGs), batteries, fuel cells, and power systems based on advanced conversion technologies; such as, thermionics, free piston Stirling Engines (FPSE), alkali metal thermoelectric conversion (AMTEC), and thermophotovoltaics (TPV). The assessment team concluded that continued use of the RTGs is clearly the safest, most reliable, and most economical approach to supplying electrical power for remote, difficult to access locations. If political considerations force the replacement of the RTGs, the likely replacement is a hybrid system consisting of solar-PV with a propane-TEG for off-solar times. The transport of combustible fuels in Arctic environments is extremely expensive. It is this high logistics cost that signaled the need to consider the option of more efficient and cost effective power sources for the remote, Arctic applications. This paper summarizes AFRL contractual efforts involving two of the more attractive advanced conversion technologies: AMTEC and TPV. The information cited herein is the result of USAF sponsored programs and cooperative efforts with NASA Lewis Research Center (NASA-LeRC). This paper is not intended to reflect the progress and efforts of the energy conversion community as a whole.
Comparison of FEA and LPT Based Failure Analysis of P75 Graphite/934 Epoxy Composites
Authors: Rigas K. , Greif R. , Saigal A. 
Published: January 2022

Abstract
A comparison between a micro-mechanical finite element model (FEM) and the macro-mechanical laminated plate theory (LPT) has been undertaken to investigate the failure of an 8-ply [0/0/90/90]s P75 Graphite/934 Epoxy composite subjected to mechanical and thermal loads. This study deals with the initiation of failure, ultimate failure, and resulting stresses at each failure, as well as the effect of thermal residual stresses on the failure of the composite material. Thermal residual stresses develop as a result of the difference in the coefficients of thermal expansion of the fiber and the matrix, and the operating (75°F) and stress-free or cure temperature (350°F). Relationships between the boundary condition of the FEM and LPT are also explored. The ANSYS finite element program has been used in this research. The initiation of failure is based on the ultimate radial stress criterion developed by Bowles and Griffin. For LPT analysis, the first-ply failure and consequent failures are derived using the Tsai-Wu failure theory. The analyses indicate intermediate degradation of the laminate as the applied stress/strain is increased. This information is used to predict the loss in overall stiffness as a function of loading.
Residual Stress Measurement in Spot Welds and the Effect of Fatigue Loading Using High Sensitivity Moire Interferometry
Authors: Khanna Sanjeev K. , He Canlong , Agrawal Hari N. 
Published: January 2022

Abstract
Residual stress distribution has been determined in spot welds, which are generally used to join mild steel sheets. Various spot weld configurations were investigated using the full-field, experimental, optical technique of high sensitivity moiré interferometry. These stresses were found to be in the range 250–300 MPa (tensile) in the center and decreased to 40–100 MPa (tensile) at the edge of the weld nugget. Low cycle fatigue loading of the spot weld caused the residual stress to drop in the weld center by about 30% and increase at the edges by as much as 100%.
Identification of Free-Free Modes From Constrained Vibration Data for Flexible Multibody Models
Authors: Yi Tong Y. 
Published: January 2022

Abstract
This paper presents a method for identifying the free-free modes of an unconstrained structure by utilizing the available vibration data of the same constrained structure. In modal formulations for flexible body dynamics, modal data are primary known quantities that must be obtained either experimentally or analytically. For vibration measurements, the flexible body may be constrained differently than its actual conditions in the multibody system. To apply the experimentally obtained modal data to the flexible dynamic model, the available vibration data must be properly identified.
For a flexible body model in multibody systems, we may need a set of free-free modal data or constrained modal data depending upon the dynamic formulations. The identification of constrained modes from the free-free vibration data is straight forward, but the reverse process to determine the free-free modes from the constrained vibration data is difficult and expensive. The aim of this study is to extract, based on experimentally obtained vibration data, the necessary free-free frequencies and the associated modes for flexible bodies in multibody systems. In this paper, two different forms of constrained vibration data are considered. The first form is for structures supported by springs, and the second form is for structures supported by kinematic joints. The available vibration data may be either a complete set or an incomplete set.
Implementation and Application of Automatic Parametric Design of 2D Nonlinear FEA
Authors: Verderber Rudy R. 
Published: January 2022

Abstract
This paper presents implementation and application of automatic parametric design of 2D nonlinear FEA. Parametric design involves iterating on a FEA solver and preprocessor. Global quantities and linked database files provide the basis for analyzing the analyses. Parametric analysis of two disks contacting shows an expected relationship between interference, land height, and stress. Lastly, the assembly of press fit tubes shows the relationship between interference, contact area, and normal force.
Probabilistic Estimation of the Effect of Dimensional Tolerance for Turbine/Compressor Blade Attachment
Authors: Singh Murari P. 
Published: January 2022

Abstract
Root attachments of rotating blades of a turbine or a compressor often have multiple lobes. These lobes fit into a matching groove in a rotating disk. Dimension of these lobes, in general, will not be identical for each blade. However, these dimensions will be within manufacturing tolerance. The resulting dimensional fit becomes random in statistical sense within the specified tolerance. Thus precise dimension is unknown even if it is assured to be within the specified tolerance band.
This creates the possibility that for a given blade all the lobes might not be in contact i.e. there might be a gap in the joint. This also means that lobes will carry unequal load. The gap condition may be different for each blade. As the rotational speed increases, each gap will start closing and ideally will eventually close.
Description of a method to assess the influence of manufacturing tolerances on the reliability of such a joint for disk-blade assembly is presented. The resulting estimated stress as a function of rotating speed and tolerance stacking is also presented. The stress result is combined with probabilistic analysis that yields the probability for stress to be within a predetermined amount thus providing a measure of success.
Mechanical Properties of Cellular Polyurethanes Filled With Polyurethane Disperse Filler
Authors: Swisher Karena L. , Shutov Fyodor A. 
Published: January 2022

Abstract
Flexible polyurethane (PUR) foams have been filled with fine PUR powder produced from PUR foam automotive scrap. For pulverization the proprietary non-extrusion and non-cryogenic Pressure Shear Pulverization (PSP) process was used. The PSP process is based on the combined action of high shear stress and compression load at ambient temperatures. Mechanical behavior of filled PUR foams have been studied at various contents (up to 30 percent per polyol component) and size fractions (from 75 to 500 microns) of the PSP powder. Demonstrations showed improvement of compressive and cushioning properties are very critical in terms of size and content of the filler. The mechanism of the reinforcement effect is proposed based on capsulation of the PUR filler into the cell struts and walls of the flexible cellular PUR matrix.