bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of the Function Decomposition Method to Design of Solidification Processes
Authors: Hale S. W. , Keyhani M. , Frankel J. I. 
Published: January 2022

Abstract
In a unidirectional solidification design problem, the solidification velocity and liquid-side interfacial temperature gradient are of principle interest due to their effect on the morphology of the cast structure. The design challenge is the prediction of the temporal conditions at the boundaries such that the solidification velocity and liquid-side temperature gradient at the solid-liquid interface follow a prescribed scenario. This design problem requires the resolution of two inverse heat conduction problems: one in an expanding solid domain and the second in a shrinking liquid domain. Resolution of the solid domain results in a transient boundary condition that yields the prescribed solidification velocity, while resolution of the liquid domain results in a transient boundary condition that yields the prescribed interfacial temperature gradient.
An innovative and robust solution technique is proposed and demonstrated for resolution of the liquid-side temperature gradient design problem during unidirectional solidification. The technique, termed the Function Decomposition Method (FDM), is an innovative combination of function decomposition for the superposition of direct solutions, continuous least squares, and the weighted residual method which transforms the mildly ill-posed inverse heat conduction problem in the shrinking liquid region into a set of well-posed direct problems. To demonstrate its application, a set of test cases are presented which provide illustrative results highlighting the flexibility of the methodology.
Estimation of Transient Boundary Conditions in a Multimaterial: Computational and Experimental Analysis
Authors: Abboudi S. , Artioukhine E. A. , Riad H. 
Published: January 2022

Abstract
The goal of the proposed study is to analyze numerically and experimentally transient flux densities absorbed by specimen which is a typical thermal barrier. The studied composite material is obtained by thermal projection of a deposit of MCrAlY on a substrate in Copper. To solve this inverse heat conduction problem, we have used the implicit finite difference method for the direct problem and the iterative regularization method for the inverse problem. The developed numerical algorithm is based on the minimization of the residual functional which is the integrated difference between temperature histories measured and those calculated by solving the direct problem. The conjugate gradient method is used to solve the inverse problem. The residual functional gradient is computed by solving the adjoint problem and the optimal descent parameter is calculated by solving the problem for temperature variations. The heat flux evolution is approximated by cubic B-splines. The method is first validated with simulated numerically data and second validated experimentally by thermal cycling device. Temperature evolutions measured inside the specimen are used to solve the inverse problem.
Two-Phase Flow Pattern Identification From Fluctuating Components of Pressure and Void Fraction Signals
Authors: Teyssedou Alberto , Han Yanjie 
Published: January 2022

Abstract
This paper presents results on air-water flow pattern identification. The fluctuating components of void fraction are analyzed using the Probability Density Function (PDF). For bubbly and annular flows, the PDF’s show a single mode distribution. Double mode type PDF’s dominate the slug and churn flow regimes. Differential pressure and void signals are also analyzed using Power Spectrum Distribution Function (PSDF). The normalized PSDF’s for bubbly flows are broadband. For slug and churn flows, the PSDF’s show one dominant frequency with several smaller peaks.
For the churn-to-annular flow transition, the signals become more random with their spectrum shifting toward higher frequencies A single high frequency component characterizes annular flows. The average energy dissipation rate and the amplitude of the frequency components are used to develop a new flow pattern representation. This kind of representation allows different flow regime transitions to be better identified. Furthermore, by using an appropriate pressure transducer it should be possible to extend the application of the present technique to high-pressure steam-water systems.
Determination of Local Two-Phase Variables and Flow Pattern Characterization in an Upward-Flow, Rectangular Channel
Authors: Moujaes Samir F. , Sparks Jonathan C. 
Published: January 2022

Abstract
Local, time-averaged measurements of gas void fraction, gas velocity, gas bubble diameter, and bubble passage frequency in a rectangular channel (15.0 × 1.25 cm) are presented. Profiles of the gas velocity and the void fraction were characterized for the different flow regimes along the cross-sectional, transverse axes. Use of the average slug interval technique and a flow regime map, generated on coordinates of superficial velocities have been determined to be useful tools for characterizing two-phase flows and are in good agreement with established flow regime maps for both round and rectangular channels, especially for the bubble-to-slug transition. An alternative method using the centerline gas void fractions is also used to characterize the flow regimes and shows some promise where these values range from 8.0% to 57.0%.
Flow Pattern of Gas-Liquid Two-Phase Annular Flow in a Spiral Tube
Authors: Asano Hitoshi , Takenaka Nobuyuki , Fujii Terushige , Arakawa Tetsuya , Matsubayashi Masahito 
Published: January 2022

Abstract
To clarify the effect of the centrifugal force on the phase distribution of gas-liquid two-phase flow in a coiled tube, air-water two-phase annular flows in a spiral tube were visualized by a thermal neutron radiography method, and the two-dimensional void fraction distributions were measured from the obtained images by some image processing methods. An aluminum tube coiled in a plane and placed vertically was used as the test section. As a result, inversion, that is whether the liquid phase tends to flow at the inside or outside, of the spiral tube, could be determined. The condition of the inversion was correlated by body force on the gas and the liquid phases, that is, the centrifugal force and gravity.
Tomographic Measurement of the Liquid Hold-Up in a Structured Packing
Authors: Schmitz D. , Petritsch G. , Mewes D. , Moser F. 
Published: January 2022

Abstract
The high resolution which can be obtained by computer assisted tomography is used to investigate the liquid distribution and void fraction of the structured packing OPTIFLOW by Sulzer CHEMTECH. With a spatial resolution of 0.4 mm it is possible to detect the thin liquid films on structured packings. The experimental set-up consists of a custom-built second generation tomograph. The liquid and void fraction distribution in the structured packing with a quiescent gaseous phase is visualized. The water/air system is used. The liquid distributor consists of a perforated plate. The measured average hold-up of the packing is in good agreement with empirical correlations.
Monitoring Fluidization Dynamics for Detection of Changes in Fluidized Bed Composition and Operating Conditions
Authors: van Ommen J. Ruud , Schouten Jaap C. , van den Bleek Cor M. 
Published: January 2022

Abstract
In many industrial applications of gas-solids fluidized beds, the hydrodynamics of the bed can change over time, either by imposed alterations (e.g., a grade change) or by unwanted phenomena (e.g., agglomeration). In both cases, it is worthwhile to have an on-line monitoring method for detecting these changes quickly. In this paper, such a method, based on the short-term predictability of fluidized bed pressure fluctuations, is examined. Its sensitivity has been investigated by experiments with small step changes in the superficial gas velocity and by experiments with a gradual change in the particle size distribution of the solids in the bed. For both types of experiments, it is shown that the monitoring method detects changes in the excess gas velocity as small as 0.01 m/s. Furthermore, it is demonstrated that the method is well able to indicate if a stationary hydrodynamic state has been reached after a change in the particle size distribution (a ‘grade change’).
A Multi-Phase Flow Research Facility to Study Oil-Water-Gas Flow Systems
Authors: Ching Chan Y. , Wang Guanjun , Marshall Alfred R. 
Published: January 2022

Abstract
A new flow loop has been constructed at Memorial University of Newfoundland (MUN) to investigate oil-water-gas flows. The facility will initially support the development of an electroquasistatic multiphase flow meter (MPFM) to measure the individual oil-water-gas flow rates of unprocessed oil well streams. The flow loop is a 65 m recirculating open circuit system, and is constructed of 3-inch diameter pipe. There are clear horizontal and vertical test sections for flow visualization. Instrumentation includes several pressure and temperature transducers, and flow meters on the gas and liquid lines to measure the individual gas and liquid flow rates. Electro-pneumatic control valves arc installed on the liquid and air lines to facilitate control of the flow conditions, and a wide range of flow regimes can be generated. Operational control of the loop is implemented through a fully integrated computer system, which also handles the data acquisition. Quantitative flow visualization techniques, in combination with hot-film anemometry measurements are being used to study and characterize the different flow regimes. A new way of presenting flow maps that incorporates the pipe diameter and loop pressure is discussed. Preliminary results indicate that hot-film anemometry is a viable technique to obtain local volume fraction, and convection velocities of the gas slugs/bubbles. A block matching correlation technique is being developed to identify the different flow regimes, and estimate the velocity vectors of the different phases using consecutive frames from flow visualization.
Liquid-Liquid and Gas-Liquid Flow Patterns in a Torus Reactor
Authors: Benzemel Hafid , Rosant Jean-Michel , Legrand Jack 
Published: January 2022

Abstract
Two-phase liquid/liquid and gas/liquid flows in a circular torus reactor have been experimentally studied. The goal was to determine the flow structure inside the torus for various volume ratios of the two phases and various circulation velocities. The observed flow patterns are either stratified, dispersed or mixed flows. For the lower rotational speeds, stratified flow is obtained. For the higher speeds, one phase is dispersed within the other, corresponds to the dispersed flow regime. For the moderate speeds, both stratified and dispersed flows coexist in the torus reactor; this defines the mixed flow regime.
Measurement of Temperature Distribution of a Flat-Plate Heat Pipe Using Thermochromic Liquid Crystal and Color Imaging Techniques
Authors: Sun Jinhui , Liu Chang Yu 
Published: January 2022

Abstract
An experimental study on the performance of a flat-plate heat pipe was conducted by measuring the surface temperature distribution using thermochromic liquid crystals (TLC). Single wide-band liquid crystals were coated on the heat pipe and the colors exhibited by the liquid crystals were captured using a color video camera and calibrated using thermocouples. Comparative experiments were performed on the heat pipe and a heat pipe shell (without working fluid) under steady state and transient conditions. The full-field temperature visualization revealed a number of hot spots in the condenser section under both steady state and transient operation conditions. These hot spots are caused by non-uniformity in the wick structure of the heat pipe.
Frequency Response Calibration of Cold-Wire Sensors
Authors: Wroblewski Donald E. , Xie Qi 
Published: January 2022

Abstract
Cold-wire sensors, used for measurements of temperature fluctuations in turbulent flows, can suffer greatly from reduced frequency response, at high frequencies as a result of the wire’s thermal inertia and at low frequencies as a result of end conduction between the wire and the thermally massive support prongs. The frequency response of two platinum cold wires (1.27 μm diameter, 0.8 mm length and 1.27 μm, 0.76 mm length) was measured using the movement of the instantaneous hot-cold interface of a heated turbulent boundary layer, combined with a conditional sampling and averaging technique. The method proved suitable for measuring the plateau-level response due to end conduction, but exhibited significant scatter in the indirect measurements of the wire time constant. Variations of the time constant with velocity, over the range 5 to 15 m/s, were consistent with the thermal behavior exhibited by hot-wire sensors. For situations in which the cold wire will be used in boundary-layer applications, this method is attractive since the response can be determined in situ, without the need for specialized equipment or facilities.
Numerical Analysis of a Radiant Heat Flux Calibration System
Authors: Jiang Shanjuan , Horn Thomas J. , Dhir V. K. 
Published: January 2022

Abstract
A radiant heat flux gage calibration system exists in the Flight Loads Laboratory at NASA’s Dryden Flight Research Center. This calibration system must be well understood if the heat flux gages calibrated in it are to provide useful data during radiant heating ground tests or flight tests of high speed aerospace vehicles. A part of the calibration system characterization process is to develop a numerical model of the flat plate heater element and heat flux gage, which will help identify errors due to convection, heater element erosion, and other factors.
A 2-dimensional mathematical model of the gage-plate system has been developed to simulate the combined problem involving convection, radiation and mass loss by chemical reaction. A fourth order finite difference scheme is used to solve the steady state governing equations and determine the temperature distribution in the gage and plate, incident heat flux on the gage face, and flat plate erosion. Initial gage heat flux predictions from the model are found to be within ±7% of experimental results.
Discussion of Non-Equilibrium Heat Transfer in Biological Systems
Authors: Xu Lisa X. , Liu Jing 
Published: January 2022

Abstract
To study the nature of the previously observed wave like behaviors of heat propagation in biological materials, the approach of simulating the non-homogeneous biological material as a de-formable porous medium was taken. It was shown that, the wave-like heat conduction in the bologna meat can be caused by the propagation of water in the porous medium due to thermal expansions and pressure gradients applied to the meat during measurements. Thus, in contrast to the previous thermal wave interpretation, the mechanisms of the observed phenomena may be attributed to the thermal non-equilibrium between solid and liquid in the biological material rather than the pure conduction.
Growth and Differentiation of Osteoblasts on Hollow Biocompatible Ceramic Microcarriers Under Microgravity Conditions
Authors: Qiu Qing-Qing , Ducheyne Paul , Ayyaswamy Portonovo S. 
Published: January 2022

Abstract
In our recent studies with osteoblasts in the simulated microgravity environment of rotating-wall vessels (RWVs), we have observed the formation of cell aggregates and glass surface layers. In those studies, surface modified bioactive glass particles were employed as microcarriers. The growth and coverage of cells on the glass microcarriers were observed to be limited. We have also studied this problem from a numerical modeling viewpoint. Our numerical analysis of the particle dynamics in RWVs has revealed that the limited coverage noted in the experiments may be attributable to both the high shear stress imparted to the particle surface and the collisions experienced by the microcarrier with the outer wall of the vessel. The high shear stress and wall collisions arise primarily as a result of the high density of the microcarrier material. Here, we report the development of novel hollow bioceramic microspheres with an apparent density in the range 0.8 ∼ 1.0 g/cm3. These microcarriers alleviate the aforementioned problems. The hollow ceramic microspheres have an inner shell with composition of 58–72% SiO2, 28–42% Al2O3 (in % by weight) and a porous calcium phosphate surface. This surface was deposited using a fine particle sedimentation method. The hollow microspheres were sintered at 800°C for 1h. FTIR analysis indicated that crystalline calcium hydroxyapatite (HA) was present in the porous surface. Particle trajectory analyses in both an inertial frame and a rotating frame have shown that these microspheres remain suspended in the RWV environment during the entire cell culture period without experiencing collisions with the outer wall of the vessel. Furthermore, the shear stress imparted on the microsphere surface is low (∼ 0.6 dyn/cm2. Our cell culture studies in the HARV employing the hollow microcarriers have shown that osteoblastic cells form 3-D aggregates. Extensive extracellular matrix and mineralization were also observed in these aggregates.
Temperature Distribution in Prostate During Transurethral Radio Frequency Thermotherapy Treatment of Benign Prostatic Hyperplasia
Authors: Zhu Liang , Mi Zhengxin , Xu Lisa X. 
Published: January 2022

Abstract
The heating pattern of a radio frequency (RF) electrode catheter and its induced temperature field in prostate during transurethral thermal therapy treatment were investigated in this study. Experiments were performed in a tissue-equivalent phantom gel to quantitatively examine the volumetric heating produced by a RF electrode catheter for transurethral prostatic thermotherapy. The specific absorption rate (SAR) of RF energy in the gel was measured from the initial transient temperatures at various locations within the gel. An expression for the SAR was proposed and its unknown parameters in this expression were determined by comparing the predicted and measured SAR values. The SAR distribution was then used in conjunction with the Pennes bioheat transfer equation to model the temperature field in prostate during the thermotherapy treatment. The prostatic tissue temperature rise and its relation to the effect of blood perfusion were analyzed. Blood perfusion is found to be an important factor for removal of heat especially at the higher RF heating level. The minimum RF power required to achieve a maximum tissue temperature above 45 °C is in the range from 14 W to 60 W depending on the local blood perfusion rate (0.2 ∼ 1.5 ml/gm/min). An empirical expression for the detailed temperature field within the prostate for various blood perfusion rates and RF power levels was also provided for clinical purposes.
Protective Clothing Containing Encapsulated Phase Change Materials
Authors: Colvin David P. , Bryant Yvonne G. 
Published: January 2022

Abstract
Based upon experimental results from numerous Small Business Innovation Research (SBIR) programs for USAF, NASA, NAVY, NSF and USMC, new protective clothing are being developed that provide significant enhancements in thermal storage and comfort using encapsulated phase change material With a paraffinic phase change core and a polymer outer shell whose latent phase change can be designed to occur at a selected temperature, particles of microencapsulated phase material (microPCM) can range from 3–100 microns in diameter and be added to textile fibers, composites, foams, coatings and liquid coolants. Much larger 1–3 mm macroencapsulated phase change material (macroPCM) particles can also be included within clothing to provide significant improvements in breathable thermal cooling under conditions of high humidity. When microPCM particles of 10–50 microns diameter are added to a flexible matrix such as foams, new materials are created that can provide both enhanced thermal storage and insulation within the same thickness. Enhancements of thermal capacitance of textile fibers and foams can reach 10X or 1,000 % compared to unfilled fibers and materials. The resulting clothing can provide greatly enhanced thermal protection in both hot and cold environments with both low bulk and thickness. Firefighters, race drivers, skin divers and snow skiers are discovering significant protective advantages with these new materials. For example, waterproof and breathable arctic gloves have been shown to provide superior protection to commercially-available ski wear that is less susceptible to loss of thermal resistance with localized compression.
Breast Tissue Cryosurgery With Antifreeze Proteins
Authors: Pham Linda D. , Rubinsky Boris 
Published: January 2022

Abstract
Antifreeze proteins (AFP) are chemical compounds which can modify ice crystal structure to a needle-like form. They have been shown to enhance destruction of frozen cells. The goal of this study was to determine if these antifreeze proteins can destroy cells in frozen breast tissue and thereby serve as chemical adjuvants to breast cryosurgery. Fresh, normal human breast tissue was injected with solutions of phosphate buffered saline (PBS) or PBS with 10 mg/ml antifreeze protein of type I (AFP-I) then frozen with a cooling rate of 5 °C/min to various subzero temperatures, on a special cryosurgery apparatus. Cell viability was examined with a two stain fluorescent dye test. The results show that a significant percentage of breast cells survive freezing to high subzero temperatures, typical of the temperature on the margin of a frozen cryolesion. The results also show that AFP have the ability to significantly increase cellular destruction in the high subzero temperature range.
Modular Dynamic Model of Multi-Shaft Gas Turbine and Validation Test
Authors: Bianchi M. , Peretto A. , Spina P. R. 
Published: January 2022

Abstract
The paper deals with the development of a component module library necessary to study multi-shaft gas turbine power plants.
In particular the paper presents:
- the features of the software environment used to develop the gas turbine modular dynamic model;
- for each gas turbine component, the whole form of the dynamic physical equations and their simplified final expression suitable for the software environment requirements;
- the procedure relative to the building of the gas turbine modules.
In order to validate the created gas turbine modules, the transient behavior of a twin-shaft industrial gas turbine, simulated by connecting the new modules, was compared with experimental data available in literature. The values obtained by the simulation turn out to be in agreement with the experimental data.
Modified Forms of the First and the Second Law of Thermodynamics
Authors: Sohrab Siavash H. 
Published: January 2022

Abstract
A scale-invariant statistical theory of fields is presented that leads to invariant definition of density, velocity, temperature, and pressure. The definition of Boltzmann constant is introduced as kk = k = mkvkc = 1.381 × 10−23 J/K, suggesting that Kelvin absolute temperature scale is equivalent to a length scale. Two new state variables called the reversible Qrev = TS and the reversible work Wrev = PV are introduced. The modified forms of the first and second law of thermodynamics are presented. The microscopic definition of heat (work) is presented as the kinetic energy due to random (peculiar) translational, rotational, and pulsational motions. The Gibbs free energy of an element at scale β is identified as the total system energy at scale (β-1), thus leading to an invariant form of the first law of thermodynamics Uβ = Qβ − Wβ + NeβUβ-1.