bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between a family history of malignancy and the incidence of laryngeal carcinoma in the Liaoning province of China
Authors: Li X.‐Y. , Guo X. , Feng S. , Li X.‐T. , Wei H.‐Q. , Yang H.‐A. , Ren Z. , Jiang X.‐J.
Published: April 2009

Objective:  The purpose of this study was to determine the contribution of family history of malignancy to the incidence of laryngeal squamous cell carcinoma.

Design:  We performed a retrospective review of classified statistics from the detailed information of cases and matched controls.

Setting:  First Hospital of China Medical University in the Liaoning province of China, between October 2005 and November 2007.

Participants:  A total of 288 previously untreated patients with laryngeal cancer and 296 control subjects with non‐malignant diseases were analysed by use of a hospital‐based case–control study.

Main outcome measures:  Incidence rates and family history of malignancy.

Results:  Single‐factor logistic regression analysis indicated that the odds ratio value of a family history of malignancy was 2.0 (95% confidence interval: 1.3–3.2). Multiple logistic regression analysis confirmed this result, with an odds ratio value of 2.3 (95% confidence interval: 1.2–4.5). There was significant association between a family history of malignancy and the development of laryngeal squamous cell carcinoma.

Conclusions:  A family history of malignancy plays an important role in and is an independent risk factor for the incidence of laryngeal carcinoma.
An evidence‐based approach to the management of the adult with nasal obstruction
Authors: Fraser L. , Kelly G.
Published: April 2009

Background:  Nasal obstruction is a common presenting symptom to the otolaryngology clinic. A variety of structural and mucosal abnormalities can interrupt the subjective sensation of nasal airflow.

Methods:  This review was based on a literature search last performed on 1 October 2008. Current texts and the MEDLINE, EMBASE and COCHRANE databases were searched using the subject heading nasal obstruction in combination with classification, diagnosis, therapy, drug therapy and surgery. Results were limited to include clinical trials, randomised controlled trials, meta‐analyses, systematic reviews and review articles. Relevant references from selected articles were also reviewed.

Conclusion:  We present an evidence‐based approach to history‐taking and clinical examination of an adult patient with nasal obstruction and provide an overview of management of the most common causative conditions.
Causes of deafness in British Bangladeshi children: a prevalence twice that of the UK population cannot be accounted for by consanguinity alone
Authors: Bajaj Y. , Sirimanna T. , Albert D.M. , Qadir P. , Jenkins L. , Cortina‐Borja M. , Bitner‐Glindzicz M.
Published: April 2009

Objective:  To study the causes and prevalence of sensorineural deafness in Bangladeshi children resident in East London.

Methods:  This was a cross sectional survey of children of Bangladeshi origin living in East London with bilateral sensorineural hearing loss of 40 db HL or more. In this study, 134 patients were included. The study looked primarily at the causes of sensorineural hearing loss in this population.

Results:  The prevalence of deafness in Bangladeshi children in East London is approximately 3.86 per 1000 [95% confidence intervals (CI) 3.20, 4.65] which is significantly greater than the average UK prevalence of 1.65 per 1000. The prevalence of deafness in these Bangladeshi children belonging to non‐consanguineous families only, the prevalence falls to 2.73 per 1000 (95% CI 2.19, 3.41). In 60% cases the cause of deafness was genetic. The single most common cause of sensorineural hearing loss in this population was mutations in the GJB2 gene (Connexin 26) in 20 of these patients (17%). Parents were consanguineous in 33% of the families.

Conclusion:  This study concludes that prevalence of sensorineural deafness in Bangladeshi children is at least 2.3 times the national average. This study also concludes that genetic causes are the common cause of deafness in this ethnic group, with nearly 30% of children with non‐syndromic deafness having mutations in GJB2. Although parental consanguinity was very high in this population it did not account for the whole increase in prevalence.
Complications following gastrostomy tube insertion in patients with head and neck cancer: a prospective multi‐institution study, systematic review and meta‐analysis
Authors: Grant D.G. , Bradley P.T. , Pothier D.D. , Bailey D. , Caldera S. , Baldwin D.L. , Birchall M.A.
Published: April 2009

Objectives:  To measure morbidity and mortality rates following insertion of gastrostomy tubes in head and neck cancer patients. To determine evidence for any relationship between gastrostomy insertion technique and complication rates.

Design:  A prospective cohort study and qualitative systematic review.

Setting:  Multi‐cancer networks in the South West of England, Hampshire and the Isle of White.

Participants:  One hundred and seventy‐two patients with head and neck cancer undergoing gastrostomy tube insertion between 2004 and 2005. Percutaneous endoscopic gastrostomy (PEG) was performed in 121 patients. Fifty‐one patients had radiologically inserted gastrostomy (RIG). Twenty‐seven studies reporting outcomes following 2353 gastrostomy procedures for head and neck cancer.

Main outcome measures:  Post‐procedure mortality, major and minor complications.

Results:  In the present series, mortality rates were 1.0% (1/121) for PEG and 3.9% (2/51) for RIG. Overall major complication rates following PEG and RIG were 3.3% (4/121) and 15.6% (9/51) respectively. In our systematic review and meta‐analysis of 2379 head and neck cancer patients, we observed fatality rates of 2.2% (95% CI 0.014–0.034) following PEG and 1.8% (95% CI 0.010–0.032) following RIG. Furthermore, major complication rates following PEG were 7.4% (95% CI 5.9–9.3%) and 8.9% (95% CI 7.0–11.2%) after RIG.

Conclusions:  Procedure related mortality rates following gastrostomy in head and neck cancer patients are higher than those in mixed patient populations. Major complication rates following RIG in head and neck cancer patients are greater than those following PEG. Major complications following PEG in patients with head and neck cancer appear no worse than in mixed pathology groups. We have identified that RIG is associated with increased morbidity and mortality in patients who are ineligible for PEG. The serious nature of the complications associated with gastrostomy particularly in patients with head and neck cancer requires careful consideration by the referring physician.
Microsatellite markers associated with genes expressed in developing wings of Bicyclus anynana butterflies
Authors: BELDADE PATRÍCIA , VAN’T HOF ARJÈN E. , JERÓNIMO MARIA ADELINA , LONG ANTHONY D.
Published: April 2009

Deriving useful microsatellite markers in lepidopterans has been challenging when relying on scans of genomic DNA libraries, presumably due to repetitiveness in their genomes. We assayed 96 of 320 microsatellites identified in silico from a collection of Bicyclus anynana ESTs, in 11 independent individuals from a laboratory population. From the 68 successful assays, we identified 40 polymorphic markers including 22 with BLAST‐based annotation. Nine of 12 selected polymorphic markers tested in a panel of 24 wild‐caught individuals converted to successful assays and were all polymorphic. We discuss how microsatellite discovery in ESTs is an efficient strategy with important attendant advantages.
Development of a cultivation‐independent approach for the study of genetic diversity of Sinorhizobium meliloti populations
Authors: TRABELSI DARINE , PINI FRANCESCO , BAZZICALUPO MARCO , BIONDI EMANUELE G. , AOUANI MOHAMMED E. , MENGONI ALESSIO
Published: April 2009

The development of a species‐specific marker for the analysis of the genetic polymorphism of the nitrogen‐fixing symbiotic bacterium Sinorhizobium meliloti directly from environmental DNA is reported. The marker is based on terminal‐restriction fragment length polymorphism (T‐RFLP) methodology targeting specifically the 16S‐23S Ribosomal Intergenic Spacer of S. meliloti. Species‐specificity and polymorphism of the marker were tested on DNA extracted from soil samples and from a collection of 130 S. meliloti bacterial isolates. These primers and the T‐RFLP approach proved useful for the detection and analysis of polymorphism of S. meliloti populations.
Development of ISSR markers for genetic diversity studies in Vaccinium angustifolium
Authors: Debnath Samir C.
Published: April 2009

Understanding of the genetic relationship within wild lowbush blueberry (Vaccinium angustifolium Ait.) germplasm is important to establish a broad genetic base for safeguarding and for future use of the existing genetic resources. The objective of this study was to assess the genetic variability within 43 wild lowbush blueberry clones, collected from 10 communities of four Canadian provinces, and the cultivar ‘Fundy’ by using inter simple sequence repeat (ISSR) markers, with the hope to establish a reference set of lowbush blueberry germplasm for blueberry conservation, breeding and research. Thirteen primers generated 242 polymorphic ISSR‐PCR bands. A substantial degree of genetic similarity was found among the wild collections. Cluster analysis by the unweighted pair‐group method with arithmetic averages (UPGMA) separated the 41 genotypes into two main clusters, and identified the three remaining clones as outliers. Furthermore, within one main cluster, the genotypes tended to form sub‐clusters that were in agreement with the principal coordinate (PCO) analysis. Geographical distribution contributed to 27% of total variation as revealed by analysis of molecular variance (AMOVA). The ISSR‐PCR method was simple, fast and relatively inexpensive to produce useful DNA fragments and detected a sufficient degree of polymorphism to differentiate among lowbush blueberry clones, making this technology valuable for germplasm management and the more efficient choice of parents in current blueberry breeding program.
Chronic hepatitis C in patients co‐infected with human immunodeficiency virus in Japan: a retrospective multicenter analysis
Authors: Yotsuyanagi Hiroshi , Kikuchi Yoshimi , Tsukada Kunihisa , Nishida Kyouji , Kato Michio , Sakai Hironori , Takamatsu Junki , Hige Shuhei , Chayama Kazuaki , Moriya Kyoji , Koike Kazuhiko
Published: April 2009

Aim:  A nationwide survey in Japan revealed that nearly one‐fifth of human immunodeficiency virus (HIV)‐positive patients are co‐infected with hepatitis C virus (HCV). We conducted a study to further analyze the features of liver disease in HIV–HCV co‐infected patients.

Methods:  We analyzed 297 patients from eight hospitals belonging to the HIV/AIDS Network of Japan.

Results:  HCV genotypes 1, 2, 3, 4 and mixed genotypes were detected in 55.2, 13.7, 18.9, 0.9 and 11.3% of patients, respectively, in contrast to the fact that only genotypes 1 and 2 are detected in HCV mono‐infected patients in Japan. This is compatible with the transmission of HCV through imported blood products contaminated by HCV. Sixteen of 297 HIV–HCV co‐infected patients had advanced liver disease accompanied by ascites, hepatic encephalopathy or hepatocellular carcinoma. The average age of such patients was 41.1 ± 14.0 years, which was much younger than that of HCV mono‐infected patients with the same complications. The progression speed of liver disease estimated from the changes in the levels of serum albumin, bilirubin, or platelet was slower in patients who achieved sustained virological response with interferon treatment than in those who did not receive it. The overall sustained virological response rate to interferon treatment was 43.3%.

Conclusions:  Our findings suggest that liver disease is more advanced in HIV–HCV co‐infected patients than in HCV mono‐infected patients, and interferon treatment may retard the progression of liver disease in such patients.
New Trends in Asymptotic Approaches: Summation and Interpolation Methods
Authors: Andrianov Igor V. , Awrejcewicz Jan
Published: April 2009

In this review article, we present in some detail new trends in application of asymptotic techniques to mechanical problems. First we consider the various methods which allows for the possibility of extending the perturbation series application space and hence omiting their local character. While applying the asymptotic methods very often the following situation appears: an existence of the asymptotics ε → 0 implies an existence of the asymptotics ε → ∞ (or, in a more general sense, ε → a and ε → b). Therefore, an idea of constructing a single solution valid for a whole interval of parameter ε changes is very attractive. In other words, we discuss a problem of asymptotically equivalent function constructions possessing for ε → a and ε → b a known asymptotic behavior. The defined problems are very important from the point of view of both theoretical and applied sciences. In this work, we review the state-of-the-art, by presenting the existing methods and by pointing out their advantages and disadvantages, as well as the fields of their applications. In addition, some new methods are also proposed. The methods are demonstrated on a wide variety of static and dynamic solid mechanics problems and some others involving fluid mechanics. This review article contains 340 references.
The Role of Friction in Mechanical Joints
Authors: Gaul L. , Nitsche R.
Published: April 2009

Vibration properties of most assembled mechanical systems depend on frictional damping in joints. The nonlinear transfer behavior of the frictional interfaces often provides the dominant damping mechanism in a built-up structure and plays an important role in the vibratory response of the structure. For improving the performance of systems, many studies have been carried out to predict, measure, and/or enhance the energy dissipation of friction. This article reviews approaches for describing the nonlinear transfer behavior of bolted joint connections. It gives an overview of modeling issues. The models include classical and practical engineering models. Constitutive and phenomenological friction models describing the nonlinear transfer behavior of joints are discussed. The models deal with the inherent nonlinearity of contact forces (eg, Hertzian contact), and the nonlinear relationship between friction and relative velocity in the friction interface. The research activities in this area are a combination of theoretical, numerical, and experimental investigations. Various solution techniques commonly applied to friction-damped systems are presented and discussed. Recent applications are outlined with regard to the use of joints as semi-active damping devices for vibration control. Several application areas for friction damped systems due to mechanical joints and connections like shells and beams with friction boundaries are presented. This review article includes 134 references.
Assessment on Thermal Sensitivity of Fusable Links With a Wind Tunnel
Authors: Chow W. K. , Cheng Angus C. K.
Published: April 2009

This is a paper on exploring how codes on assessing thermal sensitivity of fusable links for controlling fire shutters can be established. Typical samples of fusable links were tested in a wind tunnel for studying the thermal response of sprinkler heads. In the test, the fusable link samples were loaded under 0.4 kgf. The working section of the tunnel was set at air temperature of 135°C and air speed of 2.54 ms−1. Results suggested that it is feasible to assess the thermal sensitivity of fusable links by following international testing standards.
Strut Interference Effects on Pitot Tube Velocity Measurements
Authors: Boetcher Sandra K. S. , Sparrow Ephraim M.
Published: April 2009

The possible impact of the presence of the strut portion of a Pitot tube on the efficacy of the tube as a velocity-measuring device has been evaluated by numerical simulation. At sufficiently low Reynolds numbers, there is a possibility that the precursive effects of the strut could alter the flow field adjacent to the static taps on the body of the Pitot tube and might even affect the impact pressure measured at the nose. The simulations were performed in dimensionless form with the Reynolds number being the only prescribed parameter, but the dimensions were taken from a short-shanked Pitot tube. Over the Reynolds number range from 1500 to 4000, a slight effect of the strut was identified. However, the variation due to the presence of the shank of the velocity measured by the Pitot tube operating in that range of Reynolds numbers was only 1.5%.
Minimum Heating Energy Requirements of Piccolo Tube Jet Impingement Thermal Anti-Icing System
Authors: Elangovan R. , Hung Kuohsing E.
Published: April 2009

A numerical procedure for estimating the heating energy requirements for thermal anti-icing system design and analysis is presented. The leading edge geometry of an airfoil, exposed to atmospheric cloud containing a known sub-cooled water droplet size distribution, is analyzed and the surface temperature distribution required for anti-icing the airfoil surface is presented. The airfoil geometry flow field, computed using a compressible potential flow code, was utilized in the droplet trajectory code to calculate the local water collection efficiency. The collection efficiency and the surface velocity at the boundary layer edge are utilized in the thermal energy transfer rate calculation at the airfoil surface.
Sparse Tensor Product Approximation for Radiative Transfer
Authors: Widmer Gisela , Hiptmair Ralf
Published: April 2009

The stationary monochromatic radiative transfer equation is stated in five dimensions, with the intensity depending on both a position in a three-dimensional domain as well as a direction. In order to overcome the high dimensionality of the problem, we propose and analyse a new multiscale Galerkin Finite Element discretizaton that, under strong regularity assumptions on the solution, reduces the complexity of the problem to the number of degrees of freedom in space only (up to logarithmic terms). The sparse tensor product approximation adapts the idea of so-called ‘Sparse Grids’ for the product space of functions on the physical domain and the unit sphere. We present some details of the sparse tensor product construction including a convergence result that shows that, assuming strong regularity of the solution, the method converges with essentially optimal asymptotic rates while its complexity grows essentially only as that for a linear transport problem. Numerical experiments in a translation invariant setting in non-scattering media agree with predictions of theory and demonstrate the superior performance of the sparse tensor product method compared to the discrete ordinates method.
Measurement of Thermal Accommodation Coefficients Using Laser-Induced Incandescence
Authors: Daun K. J. , Mercier P. H. , Smallwood G. J. , Liu F. , Le Page Y.
Published: April 2009

Laser-induced incandescence (LII) is used to measure the thermal accommodation coefficient between soot sampled from a well-characterized flame and various monatomic and polyatomic gases. These measurements show that the thermal accommodation coefficient between soot and monatomic gases increases with molecular mass due to the decreasing speed of incident gas molecules and corresponding decrease in surface deformation rate, and that energy is transferred preferentially from the surface to the translational mode of the polyatomic gas molecules over internal energy modes.
Gasification of Coal and Dairy Manure With Air-Steam as Oxidizing Agent
Authors: Gordillo Gerardo , Annamalai Kalyan
Published: April 2009

The animal waste from feedlots (called feedlot biomass, FB) and dairy farms (called dairy biomass, DB) can contribute to surface or ground water contamination and air pollution problems with the release of greenhouse gases (CH4). In the present study, the feasibility of onsite gasification of DB with an air-steam mixture for production of H2 rich syngas (a mixture of H2 and CO) is considered. The composition of gases produced by DB is predicted using a) mass conservation and b) chemical equilibrium for adiabatic systems where heat produced by partial oxidation is used to strip H2 from steam. Coal is used as standard fuel for comparison of gasification performance of DB with coal. A model is developed to estimate the ideal production of CH4, H2, CO, CO2, N2 and H2S, and other compounds are assumed to be in trace amounts. The parameters investigated are equivalence ratio (1 to 10), air-steam ratio (0.1 to 1), and reaction temperature (600–1500 K). With the predicted composition of gases, the HHV of gas mixtures and the energy conversion efficiency are estimated. The predicted results show that higher ERs yield to elevated concentrations of CO and CH4, high HHV mixtures and energy conversion efficiency, and low percentages of H2 and CO2. On the other hand, lower air-steam ratios produce more H2, CO2, and CH4 but less CO under equilibrium or mass conservation methods. The results suggest that it is possible to obtain concentrations of H2 from 0 to 50%, CO from 0 to 45%, and CH4 from 0 to 45% approximately. The current results provide operational parameters for a gasifier fired with DB and a mixture of air and steam as oxidizers. Experiments are currently in progress to determine the actual composition of gases released from gasifier.
Performance Testing of 5cc Glow-Ignition Four-Stroke Engine
Authors: Ogawa Toshinori , Kawaguchi Yasuo
Published: April 2009

Although portable electric devices have become increasingly sophisticated and compact, the amount of energy required for their operation has increased and device performance may be restrained by the energy source in the near future. A small power source is also needed for mobile robots for home usage. Small, portable distributed power sources with higher energy density than the conventional battery are required. Since the energy density of hydrocarbon or hydrogen fuel is quite high compared to the battery, combustion micro engines that use these fuels are promising for this purpose. In this research, we focused on the small glow-ignition engine developed for model airplanes. Since the glow engine does not require an auxiliary electric circuit for ignition, it is suitable for lightweight miniature engines. However, unlike the spark-ignition engine, there is no equipment that controls the ignition timing. In the glow-ignition system, heat is supplied by the following three methods for ignition of the air-fuel mixture: (1) Heat produced from the compression of the air-fuel mixture; (2) Heat remaining in the element from the last explosion; and (3) Heat produced by the catalytic action of an ignition element. In such an ignition system, the combustion state may differ between cycles. In order to clarify the combustion process, a miniature pressure sensor was built into the cylinder head, and pressure fluctuation was measured. Analysis was conducted to detect cycle-to-cycle variation. The base engine used was a commercial glow-ignition four-stroke engine with a swept volume of 4.89 cc. This is a high-speed engine with a maximum engine speed exceeding 14,000 rpm. Although the nominal output was 368 W, the value measured by this research was much lower. Fuel consumption was measured by placing a fuel tank on an electronic balance. The fuel used for the experiment consisted of mainly methanol, nitromethane, and lubricant. Weight ratio of these components and air/fuel ratio were changed independently, and the effect on the combustion pressure was evaluated.
The Analysis of Non-Fourier Heat Transfer Mechanism on Thermal Conductivity for Nanofluids
Authors: Avsec Jurij , Oblak Maks
Published: April 2009

The paper features the mathematical model representing the analytical calculation of thermal conductivity for nanofluids. The mathematical model was developed on the basis of statistical nano-mechanics. We have made the detailed analysis of the influence of temperature dependence on thermal conductivity for nanofluids. On this basis are taken into account the influences such as formation of nanolayer around nanoparticles, the Brown motion of solid nanoparticles and influence of diffusive-ballistic heat transport. The analytical results obtained by statistical mechanics are compared with the experimental data and they show relatively good agreement.
Effects of Geometrical Parameters in the DS Method for the Growth of Large Sized Polycrystal Silicon
Authors: Hwang Jung-Hoon , Kim Youn-Jea , Shur Joong-Won , Yoon Dae-Ho
Published: April 2009

Polycrystalline silicon (Si) wafers share more than 60% of the photovoltaic market due to its cost advantage compared to the mono-crystalline silicon wafers. Several solidification processes have been developed by industries, including casting, heat exchanger method and electromagnetic casting. However, the market growth using mono- and polycrystalline Si wafers might be saturated due to the shortage of Si feedstock. One of the methods to solve this issue is to make higher quality polycrystalline Si wafers which are capable of producing higher efficiency solar cells. In this work, the effects of changing several geometrical parameters were evaluated to improve the directional solidification (DS) method and to satisfy the above-mentioned main targets. The developed DS method has the advantages of the small heat loss, short cycle time and efficient directional solidification. Based on the fluid dynamics model, the numerical simulation was performed on the thermal characteristics during the DS process. Using a commercial CFD code, Fluent, the heat transfer characteristics in the DS system are calculated, and the results are graphically depicted.
Optimization of Micro-Channel Features in a Ceramic Heat Exchanger
Authors: Wilson Merrill A. , Lewinsohn Charles , Cutts James , Chen Yitung , Ponyavin Valery
Published: April 2009

It has been proposed that compact ceramic heat exchangers can be used for high temperature, corrosive applications. This paper discusses the development and optimization of a microchannel heat exchanger for the decomposition of sulfuric acid as part of the hydrogen producing sulfur iodine thermo-chemical cycle. The optimization process combines thermal-hydraulic and structural modeling (UNLV) with empirical performance and validation testing (Ceramatec, Inc.). Within the designs investigated, the micro-channel features were varied to adjust the cross-sectional profiles and the “tortuosity” of the serpentine flow paths to increase the thermal performance while maintaining low pressure drops and thermo-mechanical stresses within system. The results of these coupled optimization efforts and the associated overall performance improvement will be reported.
Active Heating/Cooling Requirements for Divers in Water at Varying Temperatures
Authors: Bardy Erik R. , Mollendorf Joseph C. , Pendergast David R.
Published: April 2009

The active heating/cooling requirements to thermally sustain a human subject submerged in 10, 20, 30 and 40 °C water was measured using a system that circulated water through a zoned tubesuit garment. Water at 30 °C was circulated through the garment at a flow rate of about 0.5 L/min to each of six body regions and the outlet temperatures were measured. In addition, skin and core temperature, heat flux, and oxygen consumption was measured. The subject wore either a 6.5 mm or a 3 mm foam neoprene wetsuit. Body temperatures and heat fluxes reached steady state after 30–90 minutes and the immersions lasted 2–4 hours and core and skin temperatures remained within set thermal limits. In both wetsuits there was a linear correlation between the thermal exchange of the tubesuit and water temperature. While in the 6.5 mm wetsuit −214 to 242 W of heating (−) or cooling (+) was necessary in 10 to 40 °C water, respectively. While wearing the 3 mm wetsuit −462 to 342 W was necessary in 10 to 40 °C water, respectively. It was therefore concluded that a subject can be kept in thermal balance and comfort in 10–40 °C water with active heating/cooling.
High-Temperature Emission Characteristics of Open-Cellular Porous Plates
Authors: Krittacom Bundit , Kamiuto Kouichi
Published: April 2009

Spectral or total normal emittances of an isothermal, plane-parallel, open-cellular porous plate placed on an opaque substrate were investigated theoretically. The equation of transfer governing the radiation field was solved using Barkstrom’s finite difference method and our improved P1 approximation. The necessary radiative properties of open-cellular porous materials such as the extinction coefficient, the albedo and the asymmetry factor of a scattering phase function were evaluated using Kamiuto’s model. Emission characteristics of three kinds of open–cell foam including Alumino-Silicate, Cordierite and Ni–Cr foams were examined. Obtained theoretical results were compared with available experimental data. A comparison between numerical predictions based on Barkstrom’s method and available spectral or total normal emittance data reported in literature shows satisfactory agreements within an experimental uncertainty. Moreover, it is found that our improved P1 approximation yields good results in predicting spectral or total normal emittances of isothermal, open-cellular porous plates.
External Forced Convection Enhancement Using a Corona Discharge
Authors: Go David B. , Maturana Raul A. , Fisher Timothy S. , Garimella Suresh V.
Published: April 2009

An ionic wind is formed when air ions generated by a corona discharge are accelerated by an electric field and exchange momentum with neutral air molecules, causing air flow. Because ionic winds can generate flow with no moving parts, they offer an attractive method for enhancing the heat transfer from a surface that would otherwise only be cooled by natural convection and/or radiation. In the presence of an external, flat plate flow, ionic winds distort the boundary layer such that local heat transfer is enhanced at the wall, and recent work has suggested that integrating such devices can be useful for cooling electronic components locally. In this work, corona discharges are generated between a steel wire and copper tape electrode pair on a flat plate, perpendicular to the bulk flow direction such that the discharge is in the direction of the bulk flow. The corona discharge current is characterized, and a corona glow and spark discharge are visualized. Experimental studies of the heat transfer from a heated flat plate are conducted using an infrared camera which indicated both upstream and downstream cooling along the entire length of the wire. Heat transfer coefficients are increased by more than 200% above those obtained from bulk flow alone and are correlated to the fourth root of the corona current. Preliminary parametric studies demonstrate the influence of the electrode-pair configuration on the cooling enhancement and suggest improved geometric designs.
Local Heat Transfer Characteristics of Flows Induced by Multiple Piezoelectrically Actuated Vibrating Cantilevers
Authors: Kimber Mark L. , Garimella Suresh V.
Published: April 2009

Piezoelectric fans have been shown to provide substantial enhancements in heat transfer over natural convection while consuming very little power. The local heat transfer coefficients induced by multiple piezoelectric fans operating simultaneously in close proximity are determined experimentally. The fans vibrate close to an electrically heated stainless steel foil, and the entire temperature field is observed by means of an infrared camera. A vibration amplitude of 10 mm is considered, with the distance from the heat source to the fan tip chosen to vary from 0.01 to 2.0 times the amplitude, and the distance between the fans, or pitch, varying from 0.5 to 4.0 times the amplitude. The two-dimensional contours of the local heat transfer coefficient are compared to those observed for a single fan under similar conditions. Results show that the benefit of adding a second fan is highest at an intermediate pitch that is equal to the vibration amplitude. Constructive interference is observed under these conditions yielding a local performance increase over isolated fan operation. For a large fan pitch, separate contours surrounding each fan are similar to those of a single fan, but their performance is lower than that of the corresponding single fan. For a small fan pitch the cooling obtained with the fan pair is similar to that with just one fan, suggesting minimal benefit from adding the second fan in this case.
Optimization of Microporous Structures in Enhancing Pool Boiling Heat Transfer of Saturated R-123, FC-72 and Water
Authors: Kim Joo H. , Kashinath Madhav R. , Kwark Sang M. , You Seung M.
Published: April 2009

The present research is an experimental study for the enhancement of boiling heat transfer using microporous coating techniques. The effects of different metal particle sizes in the coating compound for microporous coatings on pool boiling performance of refrigerants and water are investigated. All boiling tests were performed with 1×1cm2 test heaters in the horizontal, upward-facing orientation under increasing heat flux conditions at atmospheric pressure in saturated R-123, FC-72, and water. Results showed that the enhanced surface by microporous coating technique significantly augmented both nucleate boiling heat transfer coefficient and critical heat flux of FC-72 and R-123 over a plain surface. However, the enhancement of boiling performance for water was comparatively insignificant compared to the other liquids.
CFD Model of the Thermal Inkjet Droplet Ejection Process
Authors: Ruiz O. E.
Published: April 2009

Numerical simulations of the thermal inkjet (TIJ) droplet ejection process are performed. The computational approach is based on a volume of fluid (VOF) formulation. This method allows determining the coupled flow and thermal fields in the firing chamber in addition to the phase change processes that take place during the drive bubble formation, expansion, and collapse. The drive bubble pressure is a result of the phase change heat transfer during the heating pulse and is not imposed by a pressure heuristic approach. A commercially available TIJ architecture was chosen as a baseline to assess the computational model predictions of ejected droplet volume and droplet velocity during a firing cycle. These computational model predictions were compared to experimental results demonstrating an excellent agreement. The transient histories of pressure in the vapor bubble, temperature, and heat transfer rate to the fluid are analyzed to explain some of the relevant physical processes observed.
Characterization and Quantification of Charge and Heat Transfer in a Solid Oxide Fuel Cell Anode
Authors: Grew Kyle N. , Joshi Abhijit S. , Peracchio Aldo A. , Chiu Wilson K. S.
Published: April 2009

The development of a more efficient and power dense solid oxide fuel cell (SOFC) requires better treatment of irreversibilities that exist in present SOFC designs. Loss due to material resistance, or Joule heating, is one such loss that substantially hinders present SOFC designs. This work examines two dimensional (2D) continuum electronic charge and heat transfer models of the SOFC to examine how Joule heating can be characterized and quantified in terms of the common and easily measured microstructure properties of tortuosity, Ni mean free path, and Ni contiguity. By modeling these processes at the pore scale, presently lacking in the literature, this work uses a direct approach to develop a working understanding of how to quantify the SOFC microstructure geometric features with respect to ohmic performance. It has been found that while the pore tortuosity has little correlation to ohmic performance, the Ni mean free path and contiguity were found to be excellent measures of a 2D anode microstructure’s ohmic performance.
Flow Boiling Inside a Single Circular Minichannel: Measurement of Local Heat Transfer Coefficient
Authors: Cavallini Alberto , Bortolin Stefano , Del Col Davide , Matkovic Marko , Rossetto Luisa
Published: April 2009

This paper describes a new experimental apparatus for the measurement of the local heat transfer coefficient during flow boiling inside a 0.96 mm internal diameter single round cross section minichannel and reports preliminary heat transfer data taken during flow boiling of R134a. As a peculiar characteristic of the present technique, the heat transfer coefficient is not measured by imposing the heat flux; instead, the boiling process is governed by controlling the inlet temperature of the heating secondary fluid. This paper also presents a methodology to determine the critical conditions during the flow boiling process when no heat flux is imposed.
Heat Transfer and Bubble Detachment in Subcooled Pool Boiling From a Microheater Array Under the Effect of a Nonuniform Electric Field
Authors: Liu Zan , Herman Cila , Kim Jungho
Published: April 2009

The effects of a nonuniform electric field on vapor bubble detachment and heat transfer rate were studied in pool boiling at different subcooled conditions for various wall temperatures. Dielectric fluid (FC-72) was used as the working fluid at 1 atm at earth gravity with two extreme gas concentration levels. An array of 3×3 independently controlled microheaters each 0.7×0.7 mm2 in size were maintained at constant temperature using electronic feedback loops, enabling the heat transfer from each heater to be determined. An electric field was applied between the horizontal upward facing microheater array, which was grounded, and a spherical, off-axis top electrode. Boiling heat transfer results with and without the electric field are presented in this study. Without the electric field, a single large “primary” bubble was observed to form due to the coalescence of the individual “satellite” bubbles which nucleated directly from each single heater array. Before its detachment, a dry spot formed underneath this primary bubble resulted in a reduction in heat transfer. With the electric field applied, three or more small “secondary” bubbles that nucleated and grew more rapidly and detached more frequently were observed. Due to the nonuniformity of the electric field, bubbles moved away from the top electrode (into the weaker region of the electric field) during their development. Higher overall heat transfer rates were measured from the heater array. In addition, the bubble behavior showed agreement with our previous investigation of injecting air bubbles into a stagnant, isothermal liquid through orifices.
Development of a Micro-Scale Differential Scanning Calorimeter for Single Cell Measurements
Authors: Zhao William G. , Solbrekken Gary L. , Mullen Steven F. , Benson James D. , Han Xu , Critser John K.
Published: April 2009

Cryopreservation is an effective way to store biological materials for an extended period of time. The process of freezing biological materials is rather traumatic, however, due to the water phase change that takes place. Successful cooling procedures have been developed for a limited number of cell types primarily through a large amount of experimentation. Fundamental cryobiological studies of cellular heat and mass transfer are currently under way in an attempt to develop an accurate model that will reduce the need for many costly experiments. The purpose of this paper is to describe the development of a tool that will allow more accurate measurements of the phase change temperature for a single cell (∼100 μm diameter) as it freezes. The resulting data will be used to improve the fundamental cryopreservation model. A proof-of-concept micro-scale DSC (μDSC) is designed and built using 250 μm × 250 μm × 500 μm thermoelectric elements. The elements are connected electrically in series to one another with metal electrodes that double as the sample and reference pans. The advantage of this configuration is that Peltier heating and cooling of the sample each have the same time constant, in contrast with macro-scale DSC machines. Thermocouples with 25 μm beads are attached to the pans providing the local temperature of the sample used for feedback control. The feedback temperature is used as the control signal for the power supply which supplies electric current to the thermoelectric structure described above. Initial experiments on the prototype μDSC indicate that the phase change of a single swine oocyte with a diameter of about 100 μm can be detected.
Wave Surface of Thermal Layer
Authors: Li Wei
Published: April 2009

This paper advances a new physics concept, wave elements developed in flow. A wave element is the wave surface of thermal layer between two temperatures in the fluid if the fluid is not at a uniform temperature. It is generated by density difference which results from temperature difference in the flow. At non-equilibrium conditions, temperature differences exist in each part of a fluid. When the fluid is in motion, wave elements are generated among molecule groups. Wave motion and Brownian motion may be the two basic forms of motion of molecules in flow. Brownian motion is controlled by temperature. Wave elements are caused by temperature differences and the motion of the fluid. The analysis is supported by the experimental data and is further confirmed by the relationship of continuity. The salient finding is that wave motion maybe the origin of flow, such as laminar flow and turbulence flow.
Convection in Underground Oil Caverns: The Role of Double Diffusion
Authors: Fernando H. J. S. , Ching C. Y. , Zhao Z. , Pol S. , Webb S. W.
Published: April 2009

The US Strategic Petroleum Reserve (SPR) stores oil in large underground salt caverns. This oil has compositional and thermal gradients induced by geothermal heating from both the bottom surface and side walls. Temperature layering has been recorded in SPR oil caverns, which is hypothesized to be predominantly due to double-diffusive layering that occurs when a stable compositional gradient is heated from below. Initial results of a laboratory experimental program aimed at studying dynamics of such double-diffusive layers in the context of SPR are described in this paper. Of particular interest are the thickness of convecting layers, layer evolution (migration/merging) and conditions for the formation/non-formation of double-diffusive layers.
The Dependence of Molecular Motion on the Dissociative Adsorption of H2 on Pt(111)
Authors: Tokumasu Takashi , Ito Daigo
Published: April 2009

The dependence of molecular motion on the dissociative adsorption mechanism of hydrogen molecule (H2) on platinum (Pt) surface was studied by Molecular Dynamics (MD) method. An interaction between atoms was considered by the Embedded Atom Method (EAM). A potential between an H atom and a Pt atom was determined from results of Density Functional Theory (DFT). Dissociation probabilities of three surface conditions, that is, (1) when the surface temperature is 300 K, (2) when the surface temperature is 0 K with allowing motion of the surface atoms and (3) when the surface temperature is 0 K with prohibiting motion of the surface atoms, were obtained. From results of the simulations, the effect of surface motion on dissociation probability was analyzed as a function of initial energy of the dissociating molecule or the surface conditions. First, it was concluded that the increase in the dissociation probability of the case (3) by the increase in the initial translational energy of H2 molecule is gentle compared with those of the other cases. Additionally, the minimum initial translational energy of H2 molecule of case (3) at which the H2 molecule can dissociate is the smallest among all of three cases. It was found that this is because the range of the dissociation barrier distribution for the case (3) is wider than those for the other cases due to the thermal motion of surface atoms. Moreover, the effect of translational and rotational motion of molecule on the dissociation probability was analyzed. It was concluded that the dissociation probability increases with the increase in the translational energy while it decreases with the increase in the rotational energy when the rotational energy is small.
Thermal Properties of Carbon Nanotube-Polymer Composites for Thermal Interface Material Applications
Authors: Razeeb Kafil M. , Munari Alessio , Dalton Eric , Punch Jeff , Roy Saibal
Published: April 2009

This work presents the thermal property study of single wall and multi wall carbon nanotubes (SWCNT and MWCNT) both in their purified and unpurified forms introduced to silicone elastomer to enhance the thermal diffusivity of this industrial polymer. An increase in thermal diffusivity was observed for incremental loading of both purified and unpurified single wall and multiwall CNT in epoxy at different percentages. An increase of thermal diffusivity as high as 130% was achieved for ∼2 wt% loading of both single wall and multi wall nanotubes. Electrical conductivity measurements showed a percolation threshold for 2% loading of multiwall CNT, below which the nanotube-epoxy composite behaved as an insulator — this is a key property for applications where electrical isolation is required. For single wall CNT-epoxy composite all the samples showed high resistance to the conduction of current. Thermal impedance measurements showed a strong dependency of contact resistance with percentage loading. Finally, the feasibility of deploying carbon nanotube-polymer composites as practical thermal interface materials for electronics thermal management is discussed.
Turbulence Measurements Over a Heated Two-Dimensional Hill
Authors: Houra T. , Tagawa M. , Nagano Y.
Published: April 2009

Experimental investigation has been made on the flow and thermal fields over a heated two-dimensional hill with a cosine-squared shape. The detailed turbulent characteristics were measured by a backscatter-type two-component LDV, a PIV system, a fine thermocouple and a cold-wire probe. In the reverse-flow region on the leeward side of the hill, the turbulence intensities and the Reynolds shear stress show much larger values than that in a canonical wall-bounded shear flow. The mean temperature maintains a relatively high value below the location where the horizontal mean velocity rapidly decreases. At the outer edge of the reverse-flow region, there exists a second maximum intensity of temperature fluctuations. The instantaneous temperature waveforms near the heated wall show very large amplitude consisting of high-frequency fluctuations superimposed on the low-frequency motions.
Time-Dependent Mixture Formation and Heat Transfer Over Irradiated Solid Combustibles in Sub-Atmospheric Pressure Enclosure
Authors: Nakamura Yuji
Published: April 2009

The aim of the present study is to elucidate the time-depended processes of combustible mixture formation, heat transfer from the heated solid surface and chemical reaction over irradiated solid combustibles in sub-atmospheric pressure enclosure. Final goal of this work is to explain observed ignition trend in sub-atmospheric pressure which is recently derived experimentally by author’s group, that is, required partial pressure of oxygen is “reduced” in sub-atmospheric range. Solid combustible is placed horizontally and irradiated from the bottom to induce an ignition spontaneously below the surface. Theoretical study based on available ignition theories and 3-D numerical simulation is performed. Classical ignition theory suggests that the observed pressure dependency of ignition is not what is given in the stagnation point flow field including the flow-associated heat loss, but in the pure diffusion field neglect any flow-induced heat loss. According to the 3-D numerical simulation, it is revealed that either pure diffusion situation or stagnation-point flow situation would be attained depending on the imposed condition. A reduction of irradiated energy could make longer ignition delay and physical process comes to play a role on ignition behavior. Under such condition, it is suspected that ignition mode would be close to what is observed in stagnation-point flow field, rather than the pure diffusion field. Feasibility study is needed to clarify this speculation.