bluuebunny/crossref_metadata_2025 huggingface dataset:
Late onset GM2 gangliosidosis presenting with motor neuron disease: An autopsy case
Authors: Yokoyama Teruo , Nakamura Seigo , Horiuchi Emiko , Ishiyama Miyako , Kawashima Rei , Nakamura Kazuo , Hasegawa Kazuko , Yagishita Saburo
Published: December 2013

Adult‐onset GM2 gangliosidosis is very rare and only three autopsy cases have been reported up to now. We report herein an autopsy case of adult‐onset GM2 gangliosidosis. The patient developed slowly progressive motor neuron disease‐like symptoms after longstanding mood disorder and cognitive dysfunction. He developed gait disturbance and weakness of lower limbs at age 52 years. Because of progressive muscle weakness and atrophy, he became bed‐ridden at age 65. At age of 68, he died. His neurological findings presented slight cognitive disturbance, slight manic state, severe muscle weakness, atrophy of four limbs and no extrapyramidal signs and symptoms, and cerebellar ataxia. Neuropathologically, mild neuronal loss and abundant lipid deposits were noted in the neuronal cytoplasm throughout the nervous system, including peripheral autonomic neurons. The most outstanding findings were marked neuronal loss and distended neurons in the anterior horn of the spinal cord, which supports his clinical symptomatology of lower motor neuron disease in this case. The presence of lipofuscin, zebra bodies and membranous cytoplasmic bodies (MCB) and the increase of GM2 ganglioside by biochemistry led to diagnosis of GM2 gangliosidosis.
Atrial Tachyarrhythmias Temporally Precede Fluid Accumulation in Implantable Device Patients
Authors: ANDRIULLI JOHN A. , MOORE HANS J. , HETTRICK DOUGLAS A. , OUSDIGIAN KEVIN T. , JOHNSON JAMES , MARKOWITZ STEVEN M.
Published: December 2013

Background

The complex relationship between heart failure and atrial tachyarrhythmias (AT/atrial fibrillation [AF]) is not well understood. We examined the temporal association between changes in intrathoracic impedance, suggesting thoracic fluid accumulation, and AT/AF occurrence in cardiac resynchronization therapy‐defibrillator and implantable cardioverter defibrillator (ICD) patients.

Methods

A retrospective analysis was conducted on stored implantable device data to identify patients with automatic monitoring of daily AT/AF burden and intrathoracic impedance. Daily population trends in AT/AF burden before and after a fluid index threshold crossing (FIC) were determined.

Results

A total of 73,018 patients (68 ± 12 years, 51% ICD, 75% male) were evaluated over 18.6 ± 11.5 months. Kaplan‐Meier analysis indicated a significantly higher probability of FIC events in the first month following the onset of persistent AT/AF when compared to a matched group without persistent AT/AF (hazard ratio [HR] 1.65, 95% confidence interval [CI] [1.58, 1.72], P < 0.001). Conversely, patients were significantly more likely to experience an episode of persistent AF in the first month after the FIC event (HR 1.32, 95% CI [1.08, 1.63], P = 0.008). The probability of a fluid index crossing within 30 days of the onset of persistent AT/AF was significantly lower in a subgroup of patients with adequate rate control (35.8% [34.3–37.4%] vs 42.0% [39.6–44.6%]; HR 1.24 [1.13–1.36]).

Conclusion

Thoracic fluid accumulation, as indicated by decreasing intrathoracic impedance, was more likely to occur immediately after the onset of persistent AT/AF, especially in the presence of inadequate rate control. Likewise, the onset of persistent AT/AF was more likely following a decrease in intrathoracic impedance.
Does exercise induce hypoalgesia through conditioned pain modulation?
Authors: Ellingson Laura D. , Koltyn Kelli F. , Kim Jee‐Seon , Cook Dane B.
Published: December 2013

Pain sensitivity decreases with exercise. The mechanisms that underlie this exercise‐induced hypoalgesia (EIH) are unclear. Our purpose was to investigate conditioned pain modulation (CPM) as a potential mechanism of EIH. Sixteen women completed pain testing during three sessions: painful exercise, nonpainful exercise, and quiet rest. Intensity and unpleasantness ratings to noxious heat stimuli were assessed at baseline and during and following each session. Results showed that pain sensitivity decreased significantly during both exercise sessions (p < .05), but not during quiet rest. Effect size calculations showed that the size of the hypoalgesic response was greater following painful exercise than nonpainful exercise. Our results suggest that exercise‐induced muscle pain may contribute to the magnitude of EIH. However, as pain sensitivity also decreased following nonpainful exercise, CPM is not likely the primary mechanism of EIH.
The influence of acculturation, medical mistrust, and perceived discrimination on knowledge about blood donation and blood donation status
Authors: Renzaho Andre M.N. , Polonsky Michael J.
Published: December 2013

Aim

The aim of this research was to assess whether perceived discrimination, the level of acculturation, and medical mistrust are associated with knowledge about blood donation processes and blood donation status.

Methods

This cross‐sectional study involved 425 African migrants recruited in Melbourne and Adelaide, Australia. Participants were surveyed face‐to‐face using bilingual workers to maximize the inclusion across different levels of literacy in the community.

Results

In the adjusted model, the scores for knowledge about blood donation were positively associated with a longer stay in Australia (β = 0.12, p = 0.001), significantly higher among those with a tertiary education (β = 0.75; p = 0.049), those who came from rural areas (β = 1.54, p = 0.015), and Christians (β = 1.83, p < 0.01) but significantly lower among those from the western African region (β = −1.10, p = 0.032). Scores for knowledge about blood donation were lower among those who were marginalized (β = −1.01, p = 0.026). Medical mistrust and perceived discrimination were not associated with knowledge about blood donation. Participants who were traditionally orientated were 69% less likely to have ever given blood than those who were bicultural or integrated (odds ratio [OR]: 0.31, p = 0.044), whereas the effects of perceived discrimination and medical mistrust were not significant. We also examined whether to restrict the analysis to those who had given blood in Australia postmigration and found that the level of acculturation and medical mistrust were not significant but that perceived discrimination, especially personal discrimination, mattered (OR = 0.63, p = 0.005).

Conclusion

Efforts to increase blood donation among African migrants need to address the issues related to perceived personal discrimination as an important intervention target.
FDG‐PET IN HEALTHY AND EPILEPTIC LAGOTTO ROMAGNOLO DOGS AND CHANGES IN BRAIN GLUCOSE UPTAKE WITH AGE
Authors: Jokinen Tarja S. , Haaparanta‐Solin Merja , Viitmaa Ranno , Grönroos Tove J. , Johansson Jarkko , Bergamasco Luciana , Snellman Marjatta , Metsähonkala Liisa
Published: December 2013

Regional cerebral metabolism and blood flow can be measured noninvasively with positron emission tomography (PET). 2‐[18F]fluoro‐2‐deoxy‐D‐glucose (FDG) widely serves as a PET tracer in human patients with epilepsy to identify the seizure focus. The goal of this prospective study was to determine whether juvenile or adult dogs with focal‐onset epilepsy exhibit abnormal cerebral glucose uptake interictally and whether glucose uptake changes with age. We used FDG‐PET to examine six Lagotto Romagnolo dogs with juvenile epilepsy, two dogs with adult‐onset epilepsy, and five control dogs of the same breed at different ages. Three researchers unaware of dog clinical status visually analyzed co‐registered PET and magnetic resonance imaging (MRI) images. Results of the visual PET analyses were compared with electroencephalography (EEG) results. In semiquantitative analysis, relative standard uptake values (SUV) of regions of interest (ROI) drawn to different brain regions were compared between epileptic and control dogs. Visual analysis revealed areas of hypometabolism interictally in five out of six dogs with juvenile epilepsy in the occipital, temporal, and parietal cortex. Changes in EEG occurred in three of these dogs in the same areas where PET showed cortical hypometabolism. Visual analysis showed no abnormalities in cerebral glucose uptake in dogs with adult‐onset epilepsy. Semiquantitative analysis detected no differences between epileptic and control dogs. This result emphasizes the importance of visual analysis in FDG‐PET studies of epileptic dogs. A change in glucose uptake was also detected with age. Glucose uptake values increased between dog ages of 8 and 28 weeks and then remained constant.
ULTRASOUND ELASTOGRAPHY OF THE LIVER, SPLEEN, AND KIDNEYS IN CLINICALLY NORMAL CATS
Authors: White Jennifer , Gay John , Farnsworth Raelynn , Mickas Matt , Kim KwangGi , Mattoon John
Published: December 2013

A large amount of overlap exists in the B‐mode ultrasound appearance of normal and abnormal liver, spleen, and kidney tissues in cats. Therefore, invasive tissue sampling procedures remain the standard method for diagnosing diseases in these organs. The purpose of our study was to assess the feasibility of ultrasound elastography as a technique for improving noninvasive characterization of the feline liver, spleen, and kidneys. Elastography was performed on 10 unsedated, clinically healthy cats. Numeric (strain) values (0 = softest to 255 = firmest) assigned to color pixels within regions of interest resulted in median scores (interquartile ranges) of body wall, 207.50 (189.75–224.00); liver, 119.00 (105.00–138.25); spleen, 127.50 (121–00–142.00); right renal cortex, 83.50 (64.00–130.00); right renal near field, 125.50 (110.75–139.75); left renal cortex, 77.50 (52.00–116.25); and left renal near field, 126.00 (114.00–145.25). Strain values were not different between organs. Body wall median was the only significantly different value (P< 0.05). Strain ratio values of body wall:organ were as follows: liver, 1.76 (1.38–2.00); spleen, 1.68 (1.47–1.83); right renal cortex, 2.31 (1.61–3.15); right renal near field, 1.62 (1.41–2.01); left renal cortex, 2.66 (1.45–4.13); and left renal near field, 1.51 (1.29–1.89). Subjectively, hepatic and splenic parenchymal tissues were homogeneous in compressibility and similar in elasticity to one another. Renal cortical tissue was softer compared to medullary tissue. Findings indicated that ultrasound elastography is a feasible technique for objectively and subjectively characterizing the feline liver, spleen, and kidneys. Further research is needed in cats with confirmed diseases of these organs, to compare the diagnostic sensitivity of ultrasound elastography vs. B‐mode ultrasonography.
Ongoing Activity of Toscana Virus Genotype A and West Nile Virus Lineage 1 Strains in Turkey: A Clinical and Field Survey
Authors: Ocal M. , Orsten S. , Inkaya A. C. , Yetim E. , Acar N. P. , Alp S. , Erisoz Kasap O. , Gunay F. , Arsava E. M. , Alten B. , Ozkul A. , Us D. , Niedrig M. , Ergunay K.
Published: December 2013

Toscana virus (TOSV), West Nile virus (WNV) and tickborne encephalitis virus (TBEV) are among major viral pathogens causing febrile disease and meningitis/encephalitis. The impact of these viruses was investigated at a referral centre in Ankara Province, Central Anatolia in 2012, where previous reports suggested virus circulation but with scarce information on clinical cases and vector activity. Serum and/or cerebrospinal fluid samples from 94 individuals were evaluated, in addition to field‐collected arthropod specimens that included 767 sandflies and 239 mosquitoes. Viral nucleic acids in clinical samples and arthropods were sought via specific and generic nested/real‐time PCRs, and antibody responses in clinical samples were investigated via commercial indirect immunofluorescence tests (IIFTs) and virus neutralization. A WNV antigen assay was also employed for mosquitoes. WNV neuroinvasive disease has been identified in a 63‐year‐old male via RNA detection, and the WNV strain was characterized as lineage 1. TOSV infections were diagnosed in six individuals (6.3%) via RNA or IgM detection. Partial sequences in a 23‐year‐old female, presented with fever and transient pancytopenia, were characterized as TOSV genotype A. Febrile disease with arthralgia and/or peripheral cranial nerve involvement was noted in cases with TOSV infections. Previous WNV and TOSV exposures have been observed in 5.3% and 2.1% of the subjects, respectively. No confirmed TBEV exposure could be identified. Morphological identification of the field‐collected mosquitoes revealed Culex pipiens sensu lato (74.4%), Anopheles maculipennis (20.9%), An. claviger (2.1%) and others. Sandfly species were determined as Phlebotomus papatasi (36.2%), P. halepensis (27.3%), P. major s. l. (19.3%), P. sergenti (8.9%), P. perfiliewi (4.4%), P. simici (2.6%) and others. Viral infections in arthropods could not be demonstrated. TOSV genotype A and WNV lineage 1 activity have been demonstrated as well as serologically proven exposure in patients. Presence of sandfly and mosquito species capable of virus transmission has also been revealed.
Empirical Models for a Screw Expander Based on Experimental Data From Organic Rankine Cycle System Testing
Authors: Krishna Avadhanula Vamshi , Lin Chuen-Sen
Published: December 2013

The screw expander discussed in this work was part of a 50 kW organic Rankine cycle (ORC) system. The ORC was tested under different conditions in heat source and heat sink. In conjunction with collecting data for the ORC system, experimental data were also collected for the individual components of the ORC, viz. evaporator, preheater, screw expander, working fluid pump, and condenser. Experimental data for the screw expander were used to develop the two empirical models discussed in this paper for estimating screw expander performance. As the physical parameters of the screw expander discussed in this article are not known, a “black-box” approach was followed to estimate screw expander power output, based on expander inlet and outlet pressure and temperature data. Refrigerant R245fa was used as the working fluid in the ORC. The experimental data showed that the screw expander had ranges of pressure ratio (2.70 to 6.54), volume ratio (2.54 to 6.20), and power output (10 to 51.5 kW). Of the two empirical models, the first model is based on the polytropic expansion process, in which an expression for the polytropic exponent is found by applying regression curve-fitting analysis as a function of the expander pressure ratio and volume ratio. In the second model, an expression for screw expander work output is found by applying regression curve-fitting analysis as a function of the expander isentropic work output. The predicted screw expander power output using the polytropic exponent model was within ±10% of experimental values; the predicted screw expander power output using the isentropic work output model was within ±7.5% of experimental values.
Enhanced Whole-Arm Robot Teleoperation Using a Semi-Autonomous Control Policy
Authors: Lin Hsien-I , Chen Chi-Li
Published: December 2013

Previous work in robot teleoperation focused on the movement of a robot's end-effector by a human operator. However, a lack of pose control in teleoperation resulted in the robot arm frequently colliding with obstacles. Furthermore, even with pose control, it is still difficult for the robot to quickly and accurately move to the target due to mechanical discrepancies between human and robot. This paper proposes a semi-autonomous method to teleoperate the robot arm by integrating whole-arm teleoperation in joint-space control and autonomous end-effector position control. The proposed method is validated through experimental work on a robot arm with 6 degrees of freedom, with results showing significant improvement in human control for reaching for objects safely, quickly, and accurately.
Effect of Stabilized Water-Diesel Emulsions on External Combustion Characteristics
Authors: Hamdan Mohammad O. , Selim Mohamed Y. E. , Al Omari S.-A. B. , Elnajjar Emad , Ghannam Mamdouh
Published: December 2013

This study presents an experimental investigation of emulsified fuels with water content of 10%, 20% and 30% by volume, using a small furnace under steady combustion conditions. Pure diesel is used as a baseline in the conducted external combustion for comparison purposes. The study found that water content in the emulsion has strong impact on the flame temperature, the flame heat release and the combustion efficiency. The 20% water-diesel emulsion showed a lower flame temperature and higher combustion efficiency. Using the proper water-diesel emulsion, 20%, the heat release rate of the emulsified fuels is comparable to the one obtained in the pure diesel case. The highest flame temperature and heat flux transfer to water jacket is achieved at pure diesel (0% water content). The optimum water content in diesel emulsion strongly depends on the liquid fuel nozzle design.
Superadiabatic Radiant Porous Burner With Preheater and Radiation Corridors
Authors: Vandadi Vahid , Park Chanwoo , Kaviany Massoud
Published: December 2013

The thermal efficiency of radiant porous burners is less than 25% because most of the combustion heat is lost by flue gas. Here, we present a new radiant burner design to recuperate the heat of the exit flue gas using a preheater to increase the inlet air temperature and raise the flame temperature locally above adiabatic temperature (superadiabatic) at fuel-lean conditions. The superadiabatic heat is then conducted through embedded radiation corridors and is radiated, at a higher temperature than the flue gas, to target. This paper presents the results of the superadiabatic radiant porous burner from a numerical analysis using a zero-order combustion reaction model for methane/air mixture and non-thermal equilibrium formulation. The thermal efficiency over 40% is predicted.
Two-Dimensional Temperature Measurement in Free Boundary Environment by Using Moiré Deflectometry With Monochrome LED Lamp
Authors: Chen Chien-Chih , Wu Ying-Yan , Ting Chen-Ching
Published: December 2013

This article develops low cost moiré deflectometry for two-dimensional temperature measurement in free boundary environment. Experimental setup uses a red monochrome LED lamp with wavelength range of 625–635 nm as light source. In process, the light first runs through the convex lens and then propagates to the parabolic mirror with diameter of 406 mm and f/4.5 for generating the parallel light. The parallel light further propagates to test object and through two gratings with both pitch 254 lpi which are printed by laser printer. Behind the two gratings, a CCD camera is applied to capture the image, the distorted fringes. Based on the moiré deflectometry theory, the two-dimensional temperature distribution in free boundary environment can be determined in terms of the captured fringe shift analysis. This work has successfully measured the two-dimensional temperature distribution in free boundary environment with heat source models of 40–95 °C vertical wall, 60 W light bulb, and burning candle flame. The measured temperature deviations between moiré deflectometry and thermocouple thermometer are all less than 5%.
Experimental Investigation of Flow Condensation in Microgravity
Authors: Lee Hyoungsoon , Park Ilchung , Konishi Christopher , Mudawar Issam , May Rochelle I. , Juergens Jeffrey R. , Wagner James D. , Hall Nancy R. , Nahra Henry K. , Hasan Mohammad M. , Mackey Jeffrey R.
Published: December 2013

Future manned missions to Mars are expected to greatly increase the space vehicle’s size, weight, and heat dissipation requirements. An effective means to reducing both size and weight is to replace single-phase thermal management systems with two-phase counterparts that capitalize upon both latent and sensible heat of the coolant rather than sensible heat alone. This shift is expected to yield orders of magnitude enhancements in flow boiling and condensation heat transfer coefficients. A major challenge to this shift is a lack of reliable tools for accurate prediction of two-phase pressure drop and heat transfer coefficient in reduced gravity. Developing such tools will require a sophisticated experimental facility to enable investigators to perform both flow boiling and condensation experiments in microgravity in pursuit of reliable databases. This study will discuss the development of the Flow Boiling and Condensation Experiment (FBCE) for the International Space Station (ISS), which was initiated in 2012 in collaboration between Purdue University and NASA Glenn Research Center. This facility was recently tested in parabolic flight to acquire condensation data for FC-72 in microgravity, aided by high-speed video analysis of interfacial structure of the condensation film. The condensation is achieved by rejecting heat to a counter flow of water, and experiments were performed at different mass velocities of FC-72 and water and different FC-72 inlet qualities. It is shown that the film flow varies from smooth-laminar to wavy-laminar and ultimately turbulent with increasing FC-72 mass velocity. The heat transfer coefficient is highest near the inlet of the condensation tube, where the film is thinnest, and decreases monotonically along the tube, except for high FC-72 mass velocities, where the heat transfer coefficient is enhanced downstream. This enhancement is attributed to both turbulence and increased interfacial waviness. One-ge correlations are shown to predict the average condensation heat transfer coefficient with varying degrees of success, and a recent correlation is identified for its superior predictive capability, evidenced by a mean absolute error of 21.7%.
Investigation of Precipitation Fouling in Corrugated Plate Heat Exchangers
Authors: Zhang Guanmin , Li Guanqiu , Li Wei , Kukulka David
Published: December 2013

Experimental and theoretical investigations of precipitation fouling performance have been performed inside four corrugated plate heat exchangers (PHE). They have different geometry parameters, such as plate height, plate spacing, and plate angle. Heat transfer coefficient and friction factor have been obtained in the clean tests with the range of Reynolds number of 600–6000. Three precipitation fouling experiments focused on temperature influences and geometric designs have been performed. PHE with the largest hydraulic diameter and height to pitch ratio shows the best anti-fouling performance. Scanning electron microscope is used to investigate the microscopic structures of precipitation fouling. A type of Teflon coated plate has been used for testing the anti-fouling characteristic of PHEs. The coated plates show well anti-fouling performance comparing with the common SS-304 plates. A semi-empirical fouling model using Prandtl analogy has been established. The model predictions agree well with experimental data.
Experimental Study on Heat Transfer of Supercritical Kerosene in a Vertical Upward Tube
Authors: Huang Dan , Li Wei , Zhang Wei , Xu Guo-Qiang , Tao Zhi
Published: December 2013

A research on the heat transfer performance of kerosene flowing in a vertical upward tube at supercritical pressure is presented. In the experiments, insights are offered on the effects of the factors such as mass flow rate, heat flux and pressure. It is found that increasing the mass flow rate could enhance the heat transfer performances, while increasing the working pressure will deteriorate the heat transfer. Besides, the effect of heat flux on heat transfer is complicated. Based on the analysis of experimental data, enhancement of heat transfer occurs when the inner wall temperature of tube is higher than pseudo-critical temperature while the bulk fluid temperature is lower than the pseudo-critical temperature. At the supercritical conditions, heat transfer is influenced by the significant changes in thermo-physical properties, thus accurate evaluations of the thermo-physical properties become the key for the supercritical heat transfer calculations. The extended corresponding-state principle could be used for evaluating the density and the transport properties of kerosene, including its viscosity and thermal conductivity, at different temperatures and pressures. In order to obtain the numerical values of the heat capacity, a Soave–Redlich–Kwong (SRK) equation of state is used. The correlation for predicting heat transfer in kerosene at supercritical pressure is established, the calculation results from this correlation are in good agreement with the experimental results.
On Why the Flipped Classroom Model May Be the Optimum for Heat Transfer Education
Authors: Kobus Chris J.
Published: December 2013

Much has been made of recent news that the field of heat transfer has fewer teaching professors now than in years past. It remains a challenging field for many college students who then tend to go into other engineering applications. But this trend can be reversed by utilizing modern educational tools in a flipped class model that takes advantage of and optimizes both online delivery in concert with classroom activities. Specifically, the flipped classroom model allows for the use of graphical visualization of heat transfer (a phenomena that for the most part is outside our visual spectrum) in an online format and active learning exercises that engage students in the classroom. This paper will explain how both sides of this educational equation may be the optimal method for heat transfer content delivery.
True-Temperature Reconstruction From Combined Conduction and Transient Thermocouple Temperature Lag Errors in Single-Phase Convection
Authors: Kobus Chris J.
Published: December 2013

Much research has been performed on steady-state conduction errors in temperature sensors due to heat transfer to or from vessel walls through which those sensors are mounted. Furthermore, another large body of research exists for temperature errors due to transient lag error due to physical sensors measuring their own temperatures which lag the true fluid temperature that they are immersed in because of convective heat transfer limitations. Not readily available in the archival literature is the reconstruction of the true fluid temperature when both conduction and transient lag errors are present simultaneously. The paper will show how such a condition can indeed be modeled utilizing the integral technique. The salient feature of the integral technique is its simplicity, and this application again validates why the integral technique is still a valuable tool — even in a time of computation heat transfer models — not only as a research tool but as an educational one as well.
Three-Dimensional Mathematical Model of Multiphase Combustion in Full Oxygen Blast Furnace
Authors: Jiang Zeyi , Xie Yan , Jin Peng , Xue Qingguo , Zhang Xinxin
Published: December 2013

The complicated combustion of pulverized coal, free coke and cycle gas in the raceway of full oxygen blast furnace (FOBF) is different from the process in a traditional blast furnace. The differences of free nitrogen, cycle gas mixture, increased coal rate and decreased blast temperature contribute to the complexity of reductive conditions with temperature and composition. A three-dimensional CFD model considering the processes in the regions of raceway, blowpipe, deadman and dropping-zone is developed to describe the kinetic, thermal and chemical behaviors of the fuel combustion. The qualitative and quantitative analysis is conducted to evaluate the effects of operating conditions including temperature of cycle gas, injecting rate and particle diameter of pulverized coal. Simulation results show that large amount of pulverized coal injection (PCI) and also cycle gas injection is feasible with the high oxygen concentration for oxygen blast furnace. The coal injecting rate is a sensitive parameter for the combustion effect in raceway and corresponding measures must be considered for the enhancement of PCI. FOBF process could construct stronger reductive atmosphere than traditional blast furnace, which is beneficial to improve the productivity.
A Numerical Model to Reduce Thermal Residual Stress During Cooling and Annealing Process of Large Optical Glass Production
Authors: Ma Yefeng , Wu Nan , Zhang Song , Zheng Lili , Zhang Hui
Published: December 2013

Optical glass has been widely used in optical device manufacturing due to its high degree of physical and chemical homogeneity, which is considered as one of most important indicators of optical performance. Thermal stress during production has a significant impact on the optical homogeneity of the glass and it is primarily generated from temperature difference at different parts of the glass during annealing process which includes coarse and fine phases. Accumulation of thermal residual stress at early cooling stage will not only cause the cracking of the glass during process, but also affect the following fine annealing, especially, for the symmetric pattern of stress distribution. This paper focuses on mitigating of radiation influence and controlling cooling rate during coarse annealing in order to reduce thermal residual stress in the process. Numerical models are established to simulate the coarse process and investigate the homogeneity of temperature distribution at different conditions. Simulation results show that the coarse annealing process can be optimized through changing glass configuration and cooling rate.
Transient Internal Forced Convection Under Arbitrary Time-Dependent Heat Flux
Authors: Fakoor-Pakdaman M. , Andisheh-Tadbir M. , Bahrami Majid
Published: December 2013

A new all-time model is developed to predict transient laminar forced convection heat transfer inside a circular tube under arbitrary time-dependent heat flux. Slug flow condition is assumed for the velocity profile inside the tube. The solution to the time-dependent energy equation for a step heat flux boundary condition is generalized for arbitrary time variations in surface heat flux using a Duhamel’s integral technique. A cyclic time-dependent heat flux is considered and new compact closed-form relationships are proposed to predict: i) fluid temperature distribution inside the tube ii) fluid bulk temperature and iii) the Nusselt number. A new definition, cyclic fully-developed Nusselt number, is introduced and it is shown that in the thermally fully-developed region the Nusselt number is not a function of axial location, but it varies with time and the angular frequency of the imposed heat flux. Optimum conditions are found which maximize the heat transfer rate of the unsteady laminar forced-convective tube flow. We also performed an independent numerical simulation using ANSYS to validate the present analytical model. The comparison between the numerical and the present analytical model shows great agreement; a maximum relative difference less than 5.3%.
A Parametric Study of the Accuracy of Several Radiative Transport Solution Methods for a Set of 2-D Benchmark Problems
Authors: Tencer John , Howell John R.
Published: December 2013

Several of the most popular deterministic radiation transport methods for heat transfer are compared. Relative solution error is compared as a function of optical thickness and scattering albedo. The test problems are chosen to represent a range of problem types. Problems with discontinuous boundary conditions are included to evaluate ‘ray effects’ for discrete ordinates solutions. A brief derivation and a statement of the governing equations for each method is included so that the details of the precise method used is clear. All solutions are generated using finite element discretization. Where applicable, any stabilization used is included in the statement of the governing equations.
Modal Analysis of Inclined Jet Film Cooling Flows With Density Variation
Authors: Kalghatgi Prasad , Acharya Sumanta
Published: December 2013

Thermal and hydrodynamic flow field over a flat surface cooled with a single round inclined film cooling jet and fed by a plenum chamber is numerically investigated using Large Eddy Simulation (LES) and validated with published measurements. The calculations are done for a free stream Reynolds number Re = 16000, density ratio of coolant to free stream fluid ρj/ρ∞ = 2.0 and blowing ratio BR = ρjV/ρ∞V = 1.0. A short delivery tube with aspect ratio l/D = 1.75 and 35° inclination is considered. The evolution of the Kelvin-Helmholtz (K-H), hairpin and Counter-Rotating Vortex Pair (CVP) vortical structures are discussed to identify their origins. Modal analysis of the complete 3D flow and temperature field is carried out using a Dynamic Mode Decomposition (DMD) technique. The modal frequencies are identified, and the specific modal contribution towards the cooling wall temperature fluctuation is estimated on the film cooling wall. The low and intermediate frequency modes associated with streamwise and hairpin flow structures are found to have largest contribution (in-excess of 28%) towards wall temperature (or cooling effectiveness) fluctuations. The high frequency Kelvin-Helmholtz mode contributes towards initial mixing in the region of film cooling hole away from the wall. The individual modal temperature fluctuations on the wall and their corresponding hydrodynamic flow structures are presented and discussed.
On Fluid Flow and Heat Transfer in a Pipe With a U-Bend
Authors: Cvetkovski Christopher G. , Mozaffari Hoda S. , Reitsma Stanley , Bolisetti Tirupati , Ting David S.-K.
Published: December 2013

Vertical ground source heat pumps operate by pumping a heat transfer fluid through a pipe buried in the ground. There is a U-Bend at its deepest point to return the fluid to the surface. Incidentally, the U-Bend does more than packing the extensive length of the heat transferring conduit within a single compact borehole. Large flow structures called Dean’s vortices are generated in the bend and these, along with the resulting turbulence produced, are known to significantly enhance the heat transfer processes, and hence, shorten the required length. This study examines the specific roles of Reynolds and Dean numbers on the flow structure and the resulting heat transfer in a pipe with a U-Bend. Water flowing in a pipe without and with heated wall was simulated using FLUENT. The model was verified based on available data in the literature. The efficacy of the local heat transfer rate along the pipe was cast with respect to the subtle changes in the flow characteristics under varying Reynolds number and Dean number.
Two Carrier Heat Transfer Modeling for Heat Assisted Magnetic Recording
Authors: Zuckerman Neil , Fang Jin
Published: December 2013

In this work we show the structure and application of a two carrier thermal model applied to a near field transducer, representative of that used in Heat Assisted Magnetic Recording (HAMR). As part of the HAMR device operation, high energy non-thermalized electrons are initially excited by laser incidence on a gold nanostructure. The high energy electrons can travel in a ballistic fashion over longer distances than the optical thickness of gold, resulting in a spreading of the local heat. During their travel the hot electrons collide with lower-energy electrons, thermalizing the hot electrons via inelastic scattering. The thermalized electrons then transfer energy to the lattice due to electron-phonon coupling, as captured in the two carrier model. Starting with an electromagnetic solution for local heating in a sub-micron-scale microfabricated gold structure, the chosen modeling technique applies physical effects of unique interest at the nanometer scale, including brief ballistic transport of hot electrons, experimentally-verified interface thermal resistance, and electron-phonon temperature mismatch. By design, the model is built to use far-field boundary conditions from conventional one-carrier FEMs as well as lubrication-flow computational fluid dynamics. The fundamental governing equations of the two carrier model are two versions of Poisson’s Equation for heat diffusion, coupled by empirically determined terms. These equations are combined with equations for interfacial discontinuities in the temperature fields, yielding a third degree of freedom. The continuous fields are discretized using the finite difference method, and solved using algorithms developed for linear algebra, such as Gaussian Elimination, or non-direct iterative methods. Through use of the model we explore effects of ballistic electron transport length, electron-phonon coupling, as well as interfacial thermal resistance between gold and neighboring ceramics. The model results show the relative impact of the nanoscale heat transfer phenomena in a nanometer scale metal-ceramic structure, allowing us to identify the relative importance of design features and compare candidate designs.
Microtomography-Based Analysis of Pressure Drop and Heat Transfer Through Open Cell Metal Foams
Authors: Oliviero M. , Cunsolo S. , Harris W. M. , Iasiello M. , Chiu W. K. S. , Naso V. , Bianco N.
Published: December 2013

Their light weight, open porosity, high surface area per unit volume and thermal characteristics make metal foams a promising material for many industrial applications involving fluid flow and heat transfer.

Pressure drop and heat transfer of porous media have inspired a number of experimental and numerical studies. Many models have been proposed in the literature that correlate the pressure gradient and the heat transfer coefficient with the mean cell size and porosity. However, large differences exist among results predicted by different models. Most studies are based on idealized periodic cell structures.

In this study, the true 3-D micro-structure of the metal foam is obtained by employing x-ray computed microtomography (XCT). For comparison, ideal Kelvin foam structures are developed in the free-to-use software “Surface Evolver” surface energy minimization program. Pressure drop and heat transfer are then investigated using the CFD Module of COMSOL® Multiphysics code. A comparison between the numerical predictions from the real and ideal geometries is carried out.
Optical Whispering-Gallery Mode Phenomenon as a Composite Sensor With Applications to Direct On-Chip Thermal Sensing
Authors: Frenkel Matthew , Avellan Marlon , Guo Zhixiong
Published: December 2013

Optical Whispering-Gallery Mode (WGM) resonators can be fabricated with very high quality factors allowing for their use as high resolution sensors in a myriad of fields ranging from quantum electro-dynamics (QED) to pressure sensing. In this paper, we focus on integrating WGM as a dynamic temperature measurement device. The WGM sensors are fabricated onto the heating element, instead of acting as an indirect temperature sensor, allowing for direct monitoring of an area of interest. An adaptation to the WGM theoretical model, to include the thermal expansion of the composite system, is discussed and analyzed.
Numerical Study of the Effects of Different Buoyancy Models on Supercritical Flow and Heat Transfer
Authors: Xu X. Y. , Ma T. , Zeng M. , Wang Q. W.
Published: December 2013

Due to the dramatic changes in physical properties, the flow and heat transfer in supercritical fluid are significantly affected by buoyancy effects, especially when the ratio of inlet mass flux and wall heat flux is relatively small. In this study, the heat transfer of supercritical water in uniformly heated vertical tube is numerically investigated with different buoyancy models which are based on different calculation methods of the turbulent heat flux. The applicabilities of these buoyancy models are analyzed both in heat transfer enhancement and deterioration conditions. The simulation results show that these buoyancy models make few differences and give good wall temperature prediction in heat transfer enhancement condition when the ratio of inlet mass flux and wall heat flux is very small. With the increase of wall heat flux, the accuracy of wall temperature prediction reduces, and the differences between these buoyancy models become larger. No buoyancy model can currently make accurate wall temperature prediction in deterioration condition in this study.
An Evaluation of Energy Transfer Pathways in Thermal Transport Across Solid/Solid Interfaces
Authors: Wang Yan , Ruan Xiulin
Published: December 2013

Thermal transport across solid/solid interfaces has been extensively studied, but heat transfer pathways other than phonon transmission and electron-phonon nonequilibrium in the metal were usually neglected. In this work, we aim to build a general and unified model including both the above transport channels and others such as electron transmission and electron-interface coupling. For a general solid/solid system with electrons and phonons existing on both sides, an analytical solution to the interfacial thermal resistance is obtained. We show that the relative contribution from different transport channels depends on both the local condition at the interface and the bulk properties of each side of the interface. We find that for a metallic thin film deposited on a semiconductor substrate, the contribution of electron transmission to thermal transport is negligible when the semiconductor is not heavily doped even though the electronic interfacial thermal boundary resistance can be lower than the phononic counterpart at high temperatures. In contrast, the electron-interface channel plays an important role in the intrinsic to low-doped regime, where substrate phonons can remove heat efficiently from the interface.
Effect of Area Ratio on Thermal Spreading Resistance of a Cubic Heat Spreader
Authors: Thompson Scott M. , Ma Hongbin
Published: December 2013

A unique non-dimensional scheme has been employed to analytically determine the steady-state temperature field within a cubic heat spreader of unity aspect-ratio undergoing centralized, uniform heat flux with square footprint. This ‘square-on-square’ boundary value problem was solved using method of Fourier expansion. Plots of the heat spreader non-dimensional maximum temperature and non-dimensional thermal spreading resistance are provided for various Biot numbers, heat spreader thicknesses and a newly-defined ‘area ratio’ — the ratio of heater cross-sectional area to heat spreader cross-sectional area (i.e. footprint). The proposed solution is advantageous for determining optimal heat spreading configurations with low Biot numbers — typical of many electronics packaging applications and heat spreaders of very high effective thermal conductivity. The presented results indicate that the non-dimensional, maximum temperature increases as the area ratio decreases and that a limiting, non-dimensional thermal spreading resistance exists for relatively thick heat spreaders regardless of area ratio or Biot number. A critical, non-dimensional thickness was also found in which the non-dimensional, maximum temperature becomes near unity regardless of Biot number or area ratio.
Thermodynamic Analysis of Asphalt Solar Collector (ASC)
Authors: Medas Matthew , Mallick Rajib , Bhowmick Sankha
Published: December 2013

Hot mix asphalt (HMA) pavements are a potential source of extractable energy. Asphalt solar collectors (ASCs) have been designed and developed in the past as a means of extracting that energy. However, due to the variety of inefficiencies the potential for power generation has yet to be realized. This paper theoretically seeks to establish a better understanding of the performance and thermodynamic potential of the ASC. The ASC is compared to a solar water heater (SWH) through the use of (and modification to) the Hottel-Whillier-Bliss equation, a standard equation for the analysis of the SWH. Pipe spacing (W) plays a more significant role in affecting shape factor (S), Resistance Factor (FRes) and and the thermal and overall efficiency of the ASC. It was established that minimizing pipe spacing or addition of a spreader layer (SN values in the range of 1–5) helped improve the thermal and overall efficiencies. The efficiency of ASCs would be in the 1–5% range, but the use of conductive spreaders can help increase it to 10%. Through this comparative analysis, several design changes can be suggested in key areas to optimize the ASC for the maximization of efficiency.
Evaluation Analysis of CO2–Specific Correlations of Flow Boiling Heat Transfer Coefficients
Authors: Fang Xiande , Tian Lili , Zhou Zhanru , Li Dingkun , Shi Rongrong
Published: December 2013

Carbon dioxide (CO2 or R744) is an important alternative refrigerant. The two-phase flow boiling heat transfer characteristics of CO2 are quite different from those of conventional refrigerants due to its much higher working pressure. It is necessary to develop CO2-specific correlations of flow boiling heat transfer coefficients, and a number of them have been proposed. There is some literature to evaluate existing CO2-specific correlations. However, either the number of correlations or the number of data points used was limited. Hence, the results were often not consistent, even controversial. This work presents a comparative review of existing CO2-specific correlations of flow boiling heat transfer coefficients. Based on 2872 experimental data points of CO2 flow boiling heat transfer from 10 independent laboratories around the world, nine CO2-specific correlations of flow boiling heat transfer coefficients are analyzed and evaluated, which provides an in-depth understanding of the existing CO2-specific correlations. The Fang [1] correlation performs best, with a mean absolute deviation of 15.5%. More efforts should be made to better understand the mechanism of dryout and channel dimension effects.
Theoretical Predictions of Spectral Emissivity for Coal Ash Deposits
Authors: Liu Dong , Duan Yuan-Yuan , Yang Zhen
Published: December 2013

Ash deposits decrease the boiler efficiency, reduce the generating capacity and cause unscheduled outages. The radiative heat transfer is the major heat transfer mechanism in utility boilers; thus, the ash deposit emissivity is critical to boiler efficiency and safety. This paper presents a radiative transfer model to predict the spectral emissivities of coal ash deposits. The model includes the effects of the microstructure, chemical composition and temperature. Typical ash deposit microstructures are generated using diffusion-limited aggregation (DLA). The radiative properties are then calculated using the Generalized Multiparticle Mie-solution (GMM). The combined GMM and DLA model predicts spectral emissivity better than the original Mie theory and Tien’s dependent scattering theory with the average relative difference between predicted results and experimental data decreasing from 17.7% to 8.1% for sample 1 and from 16.5% to 4.2% for sample 2. Maxwell-Garnett effective medium theory is used to calculate the ash deposit optical constants based on the chemical compositions to include the effect of chemical composition. Increasing temperatures increase the particle diameters and particle volume fractions and, thus, the spectral emissivities. The spectral emissivity ultimately remains constant and less than one. The homogeneous slab model gives the upper limit of the ash deposit spectral emissivity.