bluuebunny/crossref_metadata_2025 huggingface dataset:
Nivolumab in the Treatment of Refractory Pediatric Hodgkin Lymphoma
Authors: Foran Alexandra E. , Nadel Helen R. , Lee Anna F. , Savage Kerry J. , Deyell Rebecca J.
Published: November 2016

The programmed death-1 (PD-1) pathway of immune evasion is exploited by many malignancies to limit host T-cell-mediated immune responses. Nivolumab is a PD-1-blocking monoclonal antibody that disrupts this pathway and is FDA approved for the treatment of metastatic melanoma, renal cell carcinoma, and squamous non–small cell lung cancer. In this case report, we describe the first published pediatric experience of nivolumab in refractory classic Hodgkin lymphoma. In this patient with primary refractory disease and high disease burden, cytokine release syndrome requiring inotropic support developed following the first infusion of nivolumab. The patient subsequently demonstrated a dramatic clinical response with resolution of fevers, transfusion independence, improvement in functional status, and very good partial response on PET/CT following a single dose. Nivolumab was continued with corticosteroid and antihistamine premedication without further adverse events and clinical benefit was sustained at 11 months after therapy initiation, despite evidence of slow radiographic disease progression.
Longitudinal Evaluation of Johns Hopkins Fall Risk Assessment Tool and Nurses' Experience
Authors: Hur Eun Young , Jin Yinji , Jin Taixian , Lee Sun-Mi
Published: November 2016

The Johns Hopkins Fall Risk Assessment Tool (JHFRAT) is relatively new in Korea, and it has not been fully evaluated. This study revealed that the JHFRAT had good predictive validity throughout the hospitalization period. However, 2 items (fall history and elimination patterns) on the tool were not determinants of falls in this population. Interestingly, the nurses indicated those 2 items were the most difficult items to assess and needed further training to develop the assessment skills.
Lipid Supplements and Clinical Aspects of Tear Film in Habitual Lens Wearers
Authors: Rohit Athira , Willcox Mark D. P. , Stapleton Fiona
Published: November 2016

Purpose

To establish the effect of lipid supplements on the tear lipid layer and their influence on lens wear comfort in habitual lens wearers.

Methods

Forty habitual soft contact lens wearers were recruited to a double-masked, randomized crossover trial. An emulsion drop containing phosphatidylglycerine (Systane Balance; Alcon) and a saline drop as a placebo or a liposomal spray containing phosphatidylcholine (Tears again; BioRevive) and a saline spray as a placebo were used three times a day for 2 weeks with 48 hours washout between each intervention. Ocular comfort, lipid layer grade, and stability of the tear film using a Tearscope and tear evaporation rate using a modified VapoMeter were assessed after 6 hours of lens wear with lenses in situ.

Results

Neither of the lipid supplements improved lens wear comfort compared to baseline. The noninvasive surface drying time significantly reduced with the placebo spray at day 1 (P = .002) and day 14 (P = .01) whereas the lipid spray had no effect. With the lipid drop and placebo, noninvasive surface drying time was unchanged compared to baseline (P > .05) on day 1, but by day 14, noninvasive surface drying time was reduced with the lipid drop (P = .02) and placebo (P < .001). Symptomatic wearers showed shorter noninvasive surface drying time compared to asymptomatic wearers with the spray treatment on both days (P = .03) but not with the lipid drop (P = .64). The placebo drop significantly changed the lipid layer distribution (P = .03) with a higher percentage of thinner patterns compared to the baseline distribution at day 14. A weak but significant correlation was shown between ocular comfort and noninvasive surface drying time (r = −0.21, P = .003) and tear evaporation rate (r = 0.19, P = .008). Ocular comfort was not associated with lipid layer patterns (r = 0.13, P = .06).

Conclusions

Ocular comfort during contact lens wear improved with increased tear film stability and a reduced tear evaporation rate. However, the lipid supplements did not improve ocular comfort from baseline.
Early rehabilitation after stroke
Authors: Bernhardt Julie , Godecke Erin , Johnson Liam , Langhorne Peter
Published: November 2016

Purpose of review

Early rehabilitation is recommended in many guidelines, with limited evidence to guide practice. Brain neurobiology suggests that early training, at the right dose, will aid recovery. In this review, we highlight recent trials of early mobilization, aphasia, dysphagia and upper limb treatment in which intervention is commenced within 7 days of stroke and discuss future research directions.

Recent findings

Trials in this early time window are few. Although the seminal AVERT trial suggests that a cautious approach is necessary immediately (<24 h) after stroke, early mobility training and mobilization appear well tolerated, with few reasons to delay initiating some rehabilitation within the first week. The results of large clinical trials of early aphasia therapy are on the horizon, and examples of targeted upper limb treatments with better patient selection are emerging.

Early rehabilitation trials are complex, particularly those that intervene across acute and rehabilitation care settings, but these trials are important if we are to optimize recovery potential in the critical window for repair. Concerted efforts to standardize ‘early’ recruitment, appropriately stratify participants and implement longer term follow-up is needed. Trial standards are improving. New recommendations from a recent Stroke Recovery and Rehabilitation Roundtable will help drive new research.
The use of haptic interfaces and web services in crystallography: an application for a `screen to beam' interface
Authors: Bruno Andrew E. , Soares Alexei S. , Owen Robin L. , Snell Edward H.
Published: November 2016

Haptic interfaces have become common in consumer electronics. They enable easy interaction and information entry without the use of a mouse or keyboard. The work presented here illustrates the application of a haptic interface to crystallization screening in order to provide a natural means for visualizing and selecting results. By linking this to a cloud-based database and web-based application program interface, the same application shifts the approach from `point and click' to `touch and share', where results can be selected, annotated and discussed collaboratively. In the crystallographic application, given a suitable crystallization plate, beamline and robotic end effector, the resulting information can be used to close the loop between screening and X-ray analysis, allowing a direct and efficient `screen to beam' approach. The application is not limited to the area of crystallization screening; `touch and share' can be used by any information-rich scientific analysis and geographically distributed collaboration.
Överlåtaren: a fast way to transfer and orthogonalize two-dimensional off-specular reflectivity data
Authors: Adlmann F. A. , Pálsson G. K. , Bilheux J. C. , Ankner J. F. , Gutfreund P. , Kawecki M. , Wolff M.
Published: November 2016

Reflectivity measurements offer unique opportunities for the study of surfaces and interfaces, and specular reflectometry has become a standard tool in materials science to resolve structures normal to the surface of a thin film. Off-specular scattering, which probes lateral structures, is more difficult to analyse, because the Fourier space being probed is highly anisotropic and the scattering pattern is truncated by the interface. As a result, scattering patterns collected with (especially time-of-flight) neutron reflectometers are difficult to transform into reciprocal space for comparison with model calculations. A program package is presented for a generic two-dimensional transformation of reflectometry data into q space and back. The data are represented on an orthogonal grid, allowing cuts along directions relevant for theoretical modelling. This treatment includes background subtraction as well as a full characterization of the resolution function. The method is optimized for computational performance using repeatable operations and standardized instrument settings.
“Together We Can”: Redefining Work in Nairobi's Urban Transportation Sector
Authors: Ference Meghan
Published: November 2016

Workers in Kenya's informal transportation sector are employed in what anthropologists, sociologists, psychologists, and organizational scholars call “dirty work,” or occupations that are tainted morally, socially, or physically. Although the operators of matatu, minibus taxis, carry a large portion of the Kenya population daily, they face stigmatization and discrimination, which can result in a decrease in lifechances and in some cases even death. In this article, I focus on the outcomes of the occupational stigma that matatu workers experience, and I argue that although the informal transportation workers of Nairobi's matatu sector are stigmatized symbolically and institutionally, they are also increasingly able to contest these perceptions of their work in ways that are having a powerful impact on the workers personally and collectively. The way that workers are reframing the meaning of their labor using a worker‐run union is having an impact on worker identity and sociability leading to an inclusiveness, characteristic of what theorists describe as cosmopolitanism. This process is important for anthropologists to understand as more people are finding work in undesirable and/or informal employment sectors due to the global economic crisis.
The Ties that Bind: Mexicana Caretakers and Aging Americans Construct Kinship
Authors: Ibarra María
Published: November 2016

In this paper, I examine how close care relations, sometimes resulting in kinship, are made between Mexican immigrant women employed as private care providers by aging Anglo‐Americans. This study is based on ethnographic fieldwork in Santa Barbara, California, between 2009 and 2011 and focuses on the informal care market. I discuss three case studies, applying insights from the new kinship literature, and I focus on one extended case to show how it reflects and challenges traditional notions of family in the United States. At a time when questions about what constitutes appropriate intimacy in paid care are rife, studies such as this are crucial to better understand the contexts in which other forms of kin relations may be created and solidified.
A multicellular organism with embedded cell clusters from the Ediacaran Weng'an biota (Doushantuo Formation, South China)
Authors: Cunningham John A. , Vargas Kelly , Marone Federica , Bengtson Stefan , Donoghue Philip C. J.
Published: November 2016

Three‐dimensional analyses of the early Ediacaran microfossils from the Weng'an biota (Doushantuo Formation) have focused predominantly on multicellular forms that have been interpreted as embryos, and yet they have defied phylogenetic interpretation principally because of absence of evidence from other stages in their life cycle. It is therefore unfortunate that the affinities of the various other Doushantuo microfossils have been neglected. A new conical fossil that is preserved at a cellular level is described here. The fossil contains distinct cell clusters that are characterized and analysed in three dimensions. These clusters are often exposed at the specimen surface, and the fossil preserves many hemispherical craters that are interpreted as positions where clusters have left the organism. The cell clusters may be either reproductive propagules or infesting organisms. Similar clusters are found in a variety of Doushantuo organisms including putative animal embryos and algae.
Negotiating Mutuality Through Peace Accords: Kaduna State As A Case Study
Authors: Musa Gerald M.
Published: November 2016

After some violent and protracted ethno‐religious conflicts, Christians and Muslims in Kaduna State signed a peace agreement known as the Kaduna Peace Declaration in 2002. This agreement, which was facilitated by nongovernmental organizations and endorsed by the government, emphasized the need for peaceful coexistence and cooperation between Christians and Muslims. Although the peace agreement is an essential instrument for restoring peace where there have been incessant conflicts, the peace agreement in itself is not sufficient to support sustainable peace. There is therefore a need to reinforce the peace process with what the philosopher Martin Buber called “genuine dialogue.” This article interprets what genuine dialogue is in the context of Kaduna State, where ethno‐religious conflicts have deep political roots. Furthermore, the article asserts that genuine dialogue must be inclusive, mutual, and transparent in order to be effective.
Singing Peace, Harmonizing Discordant Tunes: Tracking a Transnational Trajectory of Peace
Authors: Olaoluwa Senayon
Published: November 2016

Adopting a transnational approach that places Africa at the center of inquiry, this study traces a trajectory of peacebuilding discourse through the music of popular artists African China in Nigeria and Brenda Fassie in South Africa. It adopts a nonlinear, weblike structure that links different national spaces in the discussion of different stages in the peace trajectory. The essay identifies three stages of peacebuilding in the artists’ interventions. These stages begin with a prelude of violent conflict (early warning); they continue with the call by the artists to all stakeholders to take any measures necessary to make peace (even negotiation); and end in a final, celebratory stage that usually leads toward restoration of peace for freedom and development. In reading the lyrics, performances, and popular artists’ use of their celebrity through the prism of the three‐stage trajectory toward peace, this study contends that the inclusive, multiform mode of communication provided through popular culture is key to both freedom and development.
Electrical Suppression of Film Boiling During Quenching
Authors: Shahriari Arjang , Hermes Mark , Bahadur Vaibhav
Published: November 2016

Boiling heat transfer impacts the performance of various industrial processes like quenching, desalination and steam generation. At high temperatures, boiling heat transfer is limited by the formation of a vapor layer at the solid-liquid interface (Leidenfrost effect), where the low thermal conductivity of the vapor layer inhibits heat transfer. Interfacial electrowetting (EW) fields can disrupt this vapor layer to promote liquid-surface wetting. This concept works for a variety of quenching media including water and organic solvents. We experimentally analyze EW-induced disruption of the vapor layer, and measure the resulting enhanced cooling during quenching. Imaging is employed to visualize the fluid-surface interactions and understand boiling patterns in the presence of an electrical voltage. It is seen that EW fundamentally changes the boiling pattern, wherein, a stable vapor layer is replaced by intermittent wetting of the surface. This switch in the heat transfer mode substantially reduces the cool down time. An order of magnitude increase in the cooling rate is observed. An analytical model is developed to extract instantaneous voltage dependent heat transfer rates from the cooling curve. The results show that electric fields can alter and tune the traditional cooling curve. Overall, this study presents a new concept to control the mechanical properties and metallurgy, by electrical control of the quench rate.
Two-Phase Heat Transfer Behaviors of R-134a Refrigerant and Air-Water Mixture in a 1 mm Internal Diameter Tube
Authors: Saisorn Sira , Wongwises Somchai , Wongpromma Pakorn , Benjawun Phakkhanan , Suriyawong Adirek
Published: November 2016

Flow boiling of R-134a refrigerant was experimentally conducted in a test section which is a stainless steel tube having internal diameter of 1 mm. The DC power supply was connected to the test section to provide constant surface heat flux conditions. Flow pattern and heat transfer data were obtained for a mass flux range of 252–820 kg/m2s, a heat flux range of 1–21 kW/m2 and a saturation pressure of 8 bar. The flow visualization results showed four different flow patterns including slug flow, throat-annular flow, churn flow, and annular flow. The flow boiling heat transfer behaviors were also compared with those based on non-boiling two-phase air-water flow in the same test section under constant surface heat flux conditions. For non-boiling two-phase flow experiment, an air-water T-shaped mixer was served to introduce fluids smoothly along the test section. The results indicated that based on the same gas and liquid Reynolds numbers, flow boiling tends to have Nusselt number higher than that for non-boiling gas-liquid flow.
Heat Sink Performance Improvement by Way of Nanofluids
Authors: Zúñiga-Cerroblanco J. L. , Gonzalez-Valle C. Ulises , Lorenzini-Gutierrez Daniel , Hernandez-Guerrero Abel , Cervantes de Gortari Jaime
Published: November 2016

The new generation of integrated-circuit chips demands novel cooling techniques for enhancing device performance. Air-cooling techniques are not sufficient anymore to reach the necessary dissipation for these devices while liquid-cooling techniques have proved to be an efficient solution. The addition of nanoparticles to conventional cooling fluid changes its thermo-physical properties based on the type of the particle material, base fluid, particle volume fraction and size, pumping power, etc. The present study proposes a flow field pattern for a nanofluid-cooled heat sink in order to improve the heat transfer and the flow distribution based on a new design. Al2O3 - water nanofluid is the working fluid. The results show the comparison between the simple conventional use of water and the use of a nanofluid, by way of implementing critical factors for performance evaluation: thermal resistance, temperature uniformity, highest base temperature, and pressure drop. The analysis enables to determine that the heat sink thermal performance is definitely improved by the use of a nanofluid.
Performance Characterization of an Additively Manufactured Titanium (Ti64) Heat Exchanger for an Air-Water Cooling Application
Authors: Arie M. A. , Shooshtari A. H. , Dessiatoun S. V. , Ohadi M. M.
Published: November 2016

Over the last decade, rapid development of additive manufacturing techniques has allowed the fabrication of innovative designs which could not have been manufactured using conventional fabrication technologies. One field that can benefit from such technology is heat exchanger fabrication, as heat exchanger design has become more and more complex due to the demand for higher performance systems. One specific heat exchanger design that has shown significant performance enhancement potential over conventional designs and can greatly benefit from additive manufacturing technology is a manifold-microchannel heat exchanger. It is a design that combines careful fluid distribution through appropriate manifolds with an enhanced heat transfer surface design to achieve specific thermohydraulics performance expectations. Additive manufacturing allows fins as thin as 150 μm to be fabricated, which is an important enabler feature for the heat exchanger thermal performance. In addition, additive manufacturing allows the manifold and the microchannel sections to be fabricated as a single piece, which eliminates the need to fuse those sections together through a subsequent bonding process. As part of this work, we fabricated and experimentally tested a high-performance titanium alloy (Ti64) air-water heat exchanger that utilizes manifold-microchannel design. The heat exchanger was fabricated using direct metal laser sintering (DMLS) fabrication technique. The air-side implemented a manifold-microchannel design, while the water side used multiple rectangular channels in parallel. This was because the major thermal resistance occurs on the air side. The pressure drop and heat transfer performance of this heat exchanger were evaluated. The experimental results showed a noticeable performance reduction compared to the ones projected by numerical simulation due to an inaccuracy and low fidelity in printing of thin fin profile. However, despite this manufacturing inaccuracy, compared to a conventional wavy-fin surface, 15%–50% increase in heat transfer coefficient was possible for the same pressure drop value. Compared to a plain plate-fin surface, 95%–110% increase in heat transfer coefficient was possible for the same pressure drop value. The air-side heat transfer coefficient in the range of 100–450 W/m2K was achievable using manifold-microchannel technology for air-side pressure drop of 90–1800Pa. Since metal based additive manufacturing is still in the developmental stage, it is anticipated that with further refinement of the manufacturing process in future designs, the fabrication accuracy can be improved.
Numerical Simulation of Balling Phenomenon in Metallic Laser Melting Process
Authors: Liu Xin , Boutaous Mhamed , Xin Shihe , Siginer Dennis
Published: November 2016

As well known, the selective laser Sintering (SLS) is one of the most modern and innovative additive manufacturing technologies with general advantages and wide applications, as a non-contact process, which is flexible, and easily controlled. The choice of process parameters is quite important for laser melting in metallic powder bed. When these parameters are not correctly chosen, particles are either not sintering at all or joining into rather large droplets. This process is named as balling phenomenon, which is extremely unfavorable. In this paper, a 3D numerical model based on discrete element method is proposed in order to study the effect of parameters on the generation of balling droplets in laser melting process. A complex model is developed which couples all phenomena of full SLS process and results of simulations are compared with experimental works of other researchers taken from the literature.
Heat Transfer and Pressure Drop Characteristics of Condensation for R410A in a 3.78mm Circular Tube Under Normal and Micro Gravity
Authors: Zhang Jingzhi , Li Wei , Shih Tom I.-P. , Zhang Yonghai , Shi Yanping , Niu Yuzhen
Published: November 2016

Heat transfer and pressure drop characteristics of condensation for R410A inside horizontal tubes (dh = 3.78 mm) under normal and micro gravity are investigated numerically. The Volume of Fluid method is used to acquire liquid-vapor interface, while the low-Reynolds form of the Shear Stress Transport k∼ω (SST k∼ω) model is adopted to taking turbulent effect into account. The results indicate that the heat transfer coefficients decrease with increasing gravity accelerations, while the frictional pressure gradients increase with increases in gravity accelerations. The liquid film accumulates at the bottom of the tube, leading to a very thin liquid film attached to the upper part of inner tube wall. This accumulation effect decreases with decreases in gravitational accelerations. A more symmetrical liquid-vapor interface is obtained at lower gravity. The average liquid film thickness is nearly the same for different gravity accelerations at the same vapor quality (δave≈56 μm at x = 0.9 and δave≈230 μm at x = 0.5). The local heat transfer coefficients increase with increasing gravity at the top of the tube and decrease with increases in gravity at the bottom, while the bottom part of the tube has a limited contribution to the global heat transfer coefficient for stratified flow regime. The numerical data obtained under normal gravity agree well with well-known empirical correlations.
A Comparison of Numerical Strategies for Optimal Liquid Cooled Heat Sink Design
Authors: Kheirabadi Ali C. , Groulx Dominic
Published: November 2016

This study compares two common numerical strategies for modeling flow and heat transfer through mini- and micro-channel heat sinks: the unit cell approach and a complete three dimensional unified approach. Conjugate heat transfer and laminar flow through a copper-water heat sink over a 2×2 cm2 heat source have been modelled using the finite element method within COMSOL Multiphysics 5.0; with the primary objective being to identify the channel width at which the two models yield similar temperature and pressure predictions. Parametric studies that varied channel widths showed that as these widths were reduced, and the total number of channels increased, temperature and pressure predictions from both models converged to similar values. Relative differences as low as 5.4 and 1.6 % were attained at a channel width of 0.25 mm for maximum wall temperatures and channel pressure drops, respectively. Based upon its computational efficiency and conservative over prediction of wall temperatures, the unit cell approach is recommended as a superior design tool for parametric design studies at channel widths of less than 0.5 mm.
Analysis on Impact of Turbulence Parameters and Swirl Angle Variation on Isothermal Gas Turbine Combustor Flows
Authors: Kedukodi Sandeep , Gomez-Ramirez David , Ekkad Srinath V. , Moon Hee-Koo , Kim Yong , Srinivasan Ram
Published: November 2016

The current computational study deals with the isothermal fluid flow and heat transfer analysis of a gas turbine combustor subject to different boundary conditions. A 90 degree sector model was studied computationally in order to identify the impingement and peak heat transfer locations along the combustor liner in addition to heat transfer augmentation. Validation experiments were carried out for the full scale industrial swirler-fuel nozzle using PIV and IR thermography to obtain flow and heat transfer data. Inlet conditions into the swirler were set to a Reynolds number of 50000 and the outlet was set to atmospheric conditions. The swirler vanes provided a radially varying swirl to the flow entering into the combustor. The k-w SST turbulence model was employed to investigate the effects of different inlet turbulence parameters on the accuracy of the simulation, i.e., calculations with experimental inlet turbulent kinetic energy and deduced dissipation rate profiles, and prescribed constant turbulent intensity and length scale. It was observed that the former provided conforming results with the experiments at specific locations and improved convergence, while both cases showed discrepancy in velocity profiles within the central recirculation region of the combustor. The peak heat transfer and impingement location along the liner were in excellent agreement with the experimental data. However the peak magnitude prediction was over-predicted up to 27%. This discrepancy was attributed to the limitations of two-equation turbulence model predictions near the stagnation region. An additional study was performed to investigate the effect of different inlet swirl angles on the impingement location. It was observed that a higher swirl angle shifts the impingement location upstream. Overall, the present study provides a probe into the capability of steady RANS models to predict combustor swirling flows and wall heat transfer; and also aids in using the steady state results as initialization data for the future scale resolved turbulence model based simulations. In spite of the quantitative discrepancies, the liner heat transfer trends are expected to provide valuable insight to the industrial community in the design of combustor liners based on less expensive computational tools.
Evaluation of Heating Process of Apple, Eggplant, Zucchini and Potato by Means of Their Thermal Properties
Authors: Terres Hilario , Chavez Sandra , Lopez Raymundo , Lizardi Arturo , Lara Araceli
Published: November 2016

In this work, the heating process for apple, eggplant, zucchini and potato by means of evaluation of their thermal properties and the Biot number determined in experimental form is presented. The heating process is carried out using a solar cooker box-type as heating device. The thermal experimental properties determined are conductivity (k), density (D), specific heat (C), diffusivity (Dif) and the Biot number (Bi) for each product evaluated. In the experimentation, temperatures for center and surface in each product and water were measured in controlled conditions. For those measures, a device Compact Fieldpoint and thermocouples placed in the points studied were used. By using correlations with temperature as function, k, D and C were calculated, while by using equations in transitory state for the products modeled as sphere and cylinder was possible to estimate the Biot number after calculation of the heat transfer coefficient for each case. Results indicate the higher value for k, C and Dif correspond to zucchini (0.65 W/m °C, 4084.5 J/kg °C, 1.5 × 10−7 m2), while higher value for D correspond to potato (1197.5 kg/m3). The lowest values for k and C were obtained for potato (0.59 W/m °C, 3658.3 J/kg °C) while lowest values for D and Dif, correspond to zucchini (998.2 kg/m3) and potato (1.45 × 10−7 m2/s) respectively. The maximum and minimum values for Bi corresponded to potato (21.4) and zucchini (0.41) in respective way. The results obtained are very useful in applications for solar energy devices, where estimates for properties are very important to generate new results, for example, numerical simulations. Also, results could be used to evaluate the cooking power in solar cookers when the study object is oriented in that direction.
Evaluation of the Cover Glasses in Solar Cookers Box-Type Considering Conduction Heat Losses in Four Different Solar Cookers
Authors: Terres Hilario , Chavez Sandra , Lopez Raymundo , Lizardi Arturo , Lara Araceli
Published: November 2016

A evaluation of the conduction heat loss over their cover for four different solar cookers box-type (1. Square solar cooker with inner reflectors placed in right angles, 2. Square solar cooker with inner reflector placed in different angles, 3. Rectangular solar cooker with inner reflectors placed in different angles and 4. Octagonal solar cooker with inner reflectors placed in right angles) is presented. In the heating process in a solar cooker box-type, the conduction heat loss in their cover is the most important in comparative with convection and radiation losses. The cover in solar cookers is made with clear glasses, which allows the inlet solar radiation inside of it. When the heating process happen, the temperature in the cover glasses is important and is important for this part. To evaluate the magnitude for the heat loss, controlled tests were planned, where a solar radiation simulator was used as energy source over the solar cookers considered. In the experiments, thermocouples to determine the gradient temperature for thickness among glasses were placed. In this activity, a Compact Field and LabView software were used. Also, in the experimental tests, thermographic imagines for some instants during the heating process were taken. According results, the conduction heat losses are bigger than 25 % of the inlet energy Flux in the cookers. The biggest values for temperature on the glasses correspond to the solar cooker 3, while minimum values are obtained for the solar cooker 1. The solar cooker 1 present the biggest conduction heat losses and the cooker 4, has the minimum values for the losses. Results of this work can be useful and important for design proposes which could impacts on save of money and cooking time.
Experimental Investigation of Evaporation Heat Transfer Inside Horizontal Micro-Fin Tubes
Authors: Chen Xu , Mi Pengfei , Childs Peter R. N. , Sokolova Ekaterina , Li Wei , Yan Yuying
Published: November 2016

Tubes with their features optimized to enhance heat transfer are routinely used in industry. A series of experimental investigations of evaporation heat transfer of widely used refrigerants inside a horizontal micro-fin cooper tube have been conducted and are reported here. The micro-fin tubes have different geometric parameters with inner diameter ranging from 4.98mm to 7.14mm. The helix angle of the tested tubes ranges from 18.858° to 35°. The apex angle of the tested tubes ranges from 11° to 40°. In addition, other geometric parameters of the tubes vary, such as the fin height, fin pitch and starts.

Evaporation heat transfer experiments were conducted with the tubes and the working fluids include R22, R32 and R410A. The evaporation experiments were taken at a constant temperature of 6 °C for R22 and R410A, but 10 °C for R32. Moreover, the working conditions of the experiments varied with the mass flux ranging from 100 kg/(m2.s) to 400 kg/(m2.s). For the evaporation experiments, the inlet vapor quality is set as 0.1, while the outlet vapor quality is set as 0.9.

The experimental data reveals that tubes with different geometric parameters have different heat transfer performance. The heat transfer coefficients, the reduced pressure and the changing trend of the heat transfer coefficients vary among these tubes. The experimental data has been compared with available models in the literature and an analysis of the effect of geometric parameters on the performance of the tubes undertaken. The influence of each geometric parameter on the heat transfer performance of the micro-fin tube has been analyzed and is reported.
Effect of Carbon Powder on the Fluid Properties of PAM Solution
Authors: Zhang Meng , Zhang Hong-Na , Li Si-Ning , Li Xiao-Bin , Li Feng-Chen
Published: November 2016

In order to obtain a fluid with both drag reducing and heat transfer enhanced abilities, we use viscoelastic fluid for drag reducing and stimulate the elastic turbulence for the sake of heat transfer enhancement. To further enhance the heat transfer, carbon powder particles were added to the viscoelastic fluid where Polyacrylamide Ethylene Glycol solution was served as the base fluid. Fluid properties were measured at different solution concentration, shear rate and temperature by the rotary rheometer and thermal conductivity meter including viscosity and heat conductivity coefficients. The results showed that the addition of the carbon powder could significantly change the viscoelastic fluid properties. As for the viscosity, the shear-thinning behavior still exists after adding the carbon powder. Moreover, the heat conductivity coefficients increase about 7.5% after adding the carbon powder and nearly linearly increase with the temperature and volume concentration of the carbon particle.
A CFD Study of the Thermo-Hydraulic Characteristics of Pillow-Plate Heat Exchangers
Authors: Piper Mark , Tran Julian M. , Kenig Eugeny Y.
Published: November 2016

Pillow-plate heat exchangers (PPHE) are manufactured as stacks of pillow plates, with a typical wavy surface. They represent a promising alternative to conventional equipment for the process industry; however, the lack of published design methods hinders their widespread application. Over the past years, our group has been intensively studying PPHE, using both theoretical and experimental methods. In the present contribution, the results of a CFD-based investigation of single-phase flow and heat transfer in both the inner and the outer pillow-plate channels are presented. In particular, the influence of using an advanced eddy viscosity turbulence model, namely, the elliptic blending k-ε model, on pressure drop and heat transfer in the outer channel is shown. Furthermore, a comparison between the thermo-hydraulic efficiencies of PPHE and pipes is undertaken, in order to identify the benefits of PPHE.
Prediction of Thermal Boundary Conductance at the Interface With Phonon Wave-Packet Simulations: The Roles of Vibrational Spectra Differences, Interface Bond Strength, and Inelastic Scattering
Authors: Choi ChangJin , Yorgason W. Tanner , Roberts Nicholas A.
Published: November 2016

The current study uses phonon wave-packet simulations and calculates the phonon transmission rate to explore the contributions of the mass and the bond energy differences on the thermal boundary conductance at the interface between two dissimilar materials. The impact of interdiffusion and interface bond strength on the thermal boundary conductance are also studied. Results show that the difference in mass and bond energy of materials results in a difference in phonon dispersion relations. Thus the frequency dependence of phonon transmission rate is observed at the interface. The interdiffusion allows high frequency phonons to contribute to phonon energy transport by inelastically scattering into multiple lower frequency phonons. Therefore the different energy distribution at the interface is observed for different wavevectors when there is interdiffusion between two materials which results in increased strain at the interface. It is also found that applying different bond strengths has little effect on thermal boundary conductance at the interface unless this interface bond strength deviates significantly from the commonly used mixing rules.
Cryogenic Temperature Monitoring via Optical PDMS Sensors
Authors: Frenkel Matthew , Guo Zhixiong
Published: November 2016

PDMS micro-sensors coated onto an electrical wire are used to measure dynamic temperature variation at cryogenic range based on optical whispering-gallery mode (WGM) frequency shift principle. We designed a lab cryogenic cell via filling liquid nitrogen to create a stable low temperature down to 95K. The electrical wire is current carrying to simulate a working electrical/electronic component/device. The temperature variation due to Joule heating is monitored. The sensors are tested for their real time temperature monitoring capabilities and accuracy in the cryogenic temperature regime of 95–140K.
Experimental Measurement of Flue Gas Temperature Versus Ash Accumulation
Authors: Shi Yuetao , Wang Xiaojuan , Chu Da , Sun Fengzhong , Guo Zhixiong
Published: November 2016

It is known that particle accumulation is beneficial for dust removal in industry. In order to understand better particle accumulation mechanism, experiments were carried out to analyze the influence of flue gas temperature and humidity on ash accumulation. It is found that the Engineering Acid Dew Temperature (EADT) of flue gas is an important parameter that determines the efficiency of particle accumulation. When the gas temperature is lower than the EADT, the sulfuric acid in the flue gas and ash humidity rise dramatically, which leads to particle accumulation. In order to improve the collection efficiency, the flue gas temperature can be controlled to trigger particle accumulation.
Metrics for Quantifying Surface Wetting Effects on Vaporization Processes at Nanostructured Hydrophilic Surfaces
Authors: Kunkle Claire M. , Carey Van P.
Published: November 2016

A static contact angle is most often used as a means of quantifying the wetting characteristics of the liquid phase in vaporization processes at a solid surface. This metric is often convenient to measure and intuitive in its interpretation, but when a surface is superhydrophilic, the resulting low contact angles are difficult to measure accurately from photographs of sessile droplet profiles or contact line regions. For droplets at ultra low contact angles, small changes of contact angle can produce very large changes in wetted surface area, which makes small uncertainties in contact angle result in large uncertainties in wetted area. For hydrophilic nanostructured surfaces, another disadvantage is that the relationship of the macroscopic (apparent) contact angle to the nanoscale interaction of the liquid and vapor contact line with the nanostructured surface is not always clear. In this study, a new wetting metric based on spreading characteristics of sessile droplets is proposed that can be easily measured for hydrophilic surfaces. This metric also has the advantage that it is a more direct and sensitive indicator of how a droplet spreads on the surface. The spread area directly impacts heat transfer interactions between the droplet and the surface, therefore affecting evaporation time. Consequently, a metric that more directly illustrates the spread area provides an indication of how the wetting will affect these mechanisms.

Use of the proposed new metric is explored in the context of evaporation and boiling applications with superhydrophilic surfaces. Characteristics of this metric are also compared to static contact angle and other choices of wetting metrics suggested in earlier studies, such as dynamic advancing and receding contact angles, and spreading coefficients. The effects of nanoscale structure and/or roughness on the proposed wetting metric are analyzed in detail. A model is developed that predicts the dependence of the proposed wetting parameter on intrinsic material wettability for rough, nano-structured surfaces. The model results demonstrate that the proposed metric is a more sensitive indicator of macroscopic wetting behavior than apparent contact angle when the surface is superhydrophilic. This characteristic of the proposed new metric is shown to have advantages over other wetting metrics in the specific case of superhydrophilic nanostructured surfaces. Application of the proposed wetting metric is demonstrated for some example nanostructured surfaces. The results of our study indicate that this proposed new metric can be particularly useful for characterizing the effects of variable wetting on vaporization processes on highly wetted nanostructured surfaces.
Numerical Evaluation of Multiple Phase Change Materials for Pulsed Electronics Applications
Authors: Gonzalez-Nino David , Boteler Lauren M. , Ibitayo Dimeji , Jankowski Nicholas R. , Quintero Pedro O.
Published: November 2016

A simple and easy to implement 1-D heat transfer modeling approach is presented in order to investigate the performance of various phase change materials (PCMs) under fast transient thermal loads. Three metallic (gallium, indium, and Bi/Pb/Sn/In alloy) and two organic (erythritol and n-octadecane) PCMs were used for comparison.

A finite-difference method was used to model the transient heat transfer through the system while a heat integration or post-iterative method was used to model the phase change. To improve accuracy, the material properties were adjusted at each iteration depending on the state of matter of the PCM. The model assumed that the PCM was in direct contact with the heat source, located on the top of the chip, without the presence of a thermal conductivity enhancement.

Results show that the three metallic PCMs outperform organic PCMs during fast transient pulses in spite of the fact that two of the metallic PCMs (i.e. indium and Bi/Pb/Sn/In) have considerably lower volumetric heats of fusion than erythritol. This is due to the significantly higher thermal conductivity values of metals which allow faster absorption of the heat energy by the PCM, a critical need in high-energy short pulses. The most outstanding case studied in this paper, Bi/Pb/Sn/In having only 52% of erythritol’s heat of fusion, showed a maximum temperature 20°C lower than erythritol during a 32 J and 0.02 second pulse. This study has shown thermal buffering benefits by using a metallic PCM directly in contact with the heat source during short transient heat loads.
Visualization of Ice Formation Modes and Flow Blockage During Freezing of Water Flowing in a Microchannel
Authors: Jain Aakriti , Huang Yonghua , Weibel Justin A. , Garimella Suresh V.
Published: November 2016

Freezing in microchannels can be exploited for flow control in microfluidic applications where the use of traditional valve mechanisms is impractical. For liquid flow in a subcooled channel, freezing may initiate in dendritic, annular, or mixed modes of ice formation, depending on operational and geometric parameters. While these different modes have been observed anecdotally, the literature lacks a comprehensive parametric understanding of the ice formation behavior and the resulting time taken to block off flow in a channel. An experimental study is performed to visualize ice formation in water flowing through a subcooled circular microchannel (500 μm inner diameter) that is installed in a vacuum-insulatable, temperature-controlled test cell. The glass microchannel wall and transparent windows in the test cell and vacuum chamber allow for high-speed, high-magnification visualization of the freezing behavior. At flow rates of 0.5 ml/min, 1.0 ml/min, and 2.0 ml/min, dendritic and annular modes of ice formation are observed; the growth characteristics are presented as a function of the water flow rate.
Progress on the Development of a “Swiss-Roll” Fuel Reformer for Syngas Production
Authors: Chen Chien-Hua , Richard Bradley , Zheng Ying , Pearlman Howard , Trivedi Shrey , Koli Srushti , Lawson Andrew , Ronney Paul
Published: November 2016

A Thermal Partial Oxidation (TPOX) based “Swiss-Roll” Reformer is being developed to convert hydrocarbon fuels into hydrogen rich syngas for subsequent use in a solid oxide fuel cell (SOFC) for electrical power generation. The “Swiss-roll” reformer is an efficient countercurrent heat exchanger that recuperates heat from the hot reformate stream generated internal to the reformer and preheats the cold reactants prior to entrance into a central region where the high temperature reforming reactions occur. Effective heat recuperation enables super-adiabatic temperatures to be achieved within the reformer which drives the reformate composition towards chemical equilibrium without the need for catalysts and/or external energy. The simplicity, compactness, lack of catalysts and fuel flexibility of the reformer are attractive. In this work, experimental data obtained using a 3D printed Swiss-roll reformer is reported that shows the conversion of representative fuel (propane) to syngas. The associated temperature and species concentrations taken at different locations within the reformer are also reported. These measurements provide information on the effectiveness of the heat exchange process as well as the reforming reactions inside the compact TPOX reformer.
Numerical Investigation on Heat Transfer Enhancement of Supercritical CO2 Flowing in Heated Vertically Upward Tubes
Authors: Zhang Qian , Li Huixiong , Lei Xianliang , Kong Xiangfei , Liu Jialun , Zhang Weiqiang
Published: November 2016

Heat transfer enhancement (HTE) of supercritical CO2 flowing in heated vertical tube with an inner diameter of 6.32 mm was investigated numerically in present paper. The studies were performed for HTE cases with the pressure being 8.12 MPa, the mass flux being 400 and 1000 kg/m2s, and the heat flux being 30 and 50 kW/m2. Four turbulence models, including the RNG k-ε, the SST k-ω and two low-Reynolds number models (LB and LS), were evaluated with the experimental data collected from literatures. The SST k-ω model was shown to be the best among the four models, and then was used for the simulation in this study. The effect of five factors, including buoyancy, thermal acceleration, thermal conductivity, specific heat and viscosity of the fluid, on HTE were respectively analyzed according to the numerical results. It was shown that the buoyancy had a little negative influence on HTE and was negligible for the heat transfer. The thermal acceleration effect was detrimental to the HTE by accelerating the fluid near the wall and at the same time reducing the turbulence kinetic energy in the core of the flow. The rapid decrease of thermal conductivity of the fluid at the pseudo-critical region was also bad for HTE. Variation of the specific heat of the fluid had strong positive effect on the HTE. When most of the buffer layer was occupied by fluid with the large specific heat, the heat absorbing capability of the fluid was increased and more heat was carried away efficiently. Moreover, decrease in viscosity of the fluid with increasing temperature also significantly promoted the HTE because of the increase in flow turbulence and the reduction in thermal-conduction resistance. After that, the weight of above five factors effect on HTE was compared quantitatively.