bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance and suitability of polymerase chain reaction for early detection of bacteria in platelet concentrates
Authors: Rood Ineke G.H. , Pettersson Annika , Savelkoul Paul H.M. , de Korte Dirk
Published: March 2011

BACKGROUND: In this study the applicability of a 16S rRNA real‐time reverse transcriptase polymerase chain reaction (RT‐PCR) and a Staphylococcus genus–specific PCR for screening of bacterial contamination in platelet concentrates (PCs) was determined.

STUDY DESIGN AND METHODS: A total of 336 sample bags, from PCs that were routinely tested in the BacT/ALERT (bioMérieux), were collected and frozen until testing by the PCR assays. Based on the BacT/ALERT results, 107 PCs were positive and 229 were negative for bacterial growth.

RESULTS: The analytical sensitivity of the 16S rRNA real‐time RT‐PCR ranged from 5 to 40 colony‐forming units (CFUs)/mL. The PCR detected five positive samples, four of which were also positive in the BacT/ALERT. The sensitivity of the test was 3.8%, and the specificity was 99.5%. The analytical sensitivity of the Staphylococcus genus–specific PCR ranged from 5 to 15 CFUs/mL. Thirty‐nine units that were BacT/ALERT positive for staphylococci were tested with this PCR. Six samples were positive with the PCR, five of which were also BacT/ALERT positive. The sensitivity of the Staphylococcus genus–specific PCR was 12.8%, and the specificity was 98.8%.

CONCLUSION: Despite the rapid availability of results compared to the BacT/ALERT, the analytical sensitivity of a generic or specific PCR assay is not high enough to be an alternative for the BacT/ALERT when PCs are screened on the day of production.
Impact of national transfusion indicators on appropriate blood usage in critically ill patients
Authors: Leal‐Noval Santiago Ramón , Arellano‐Orden Victoria , Maestre‐Romero Antonio , Muñoz‐Gómez Manuel , Fernández‐Cisneros Virginia , Ferrándiz‐Millón Carmen , Corcia Yael
Published: March 2011

BACKGROUND: The objective was to investigate the impact of three national blood transfusion indicators (NBTIs) specifically designed for critical care regarding the appropriate blood transfusion indications.

STUDY DESIGN AND METHODS: This was a prospective, single‐center study, carried out at a university hospital. A total of 1808 patients admitted to the intensive care unit (ICU) in 1 year were included.

RESULTS: The study consisted of four 90‐day periods (P). P1 was a control period with no intervention. P2 followed the inclusion of NBTIs into the ICU database, aimed at reinforcing NBTI knowledge. After presenting and discussing the results of P1 and P2, the early (P3) and late (P4) impacts of NBTI knowledge were evaluated. All patients who were transfused with at least 1 unit of any blood component (33.3%) were included. Thirteen percent of red blood cell transfusions (RBCTs) were given outside of NBTI protocols (13% deviation of NBTIs for RBCTs) without a significant change throughout the duration of the study. Most RBCTs (95%) were prescribed for a hemoglobin threshold of less than 90 g/L. There was a steady and significant improvement in the adherence to NBTI guidelines for platelet concentrate transfusions (PCTs) from 36% (P1) to 52% (P4; p < 0.01). In contrast, the lack of adherence to NBTI guidelines for fresh‐frozen plasma transfusions (FFPTs) remained high (74%) and stable throughout the study period. The most frequent reason for inappropriate use of FFPTs or PCTs was absence of severe bleeding.

CONCLUSION: The introduction of NBTI guidelines demonstrated a variable impact on the appropriateness of blood component transfusions in critically ill patients.
Transfusion‐transmitted visceral leishmaniasis caused by Leishmania (Leishmania) mexicana in an immunocompromised patient: a case report
Authors: Mestra Laureano , Lopez Liliana , Robledo Sara M. , Muskus Carlos E. , Nicholls Rubén S. , Vélez Iván Darío
Published: March 2011

BACKGROUND: Transfusion‐transmitted leishmaniasis is an increasing problem in areas where visceral and cutaneous leishmaniases are endemic.

CASE REPORT: This article reports a case of transfusion‐transmitted fatal visceral leishmaniasis (VL) caused by Leishmania (Leishmania) mexicana in a 42‐year‐old male resident of northwestern Colombia who after developing a terminal renal failure due to lupus nephritis received a renal transplant and multiple transfusions.

RESULTS: Multiple intracellular Leishmania amastigotes were demonstrated in both renal biopsy and marrow aspirates. Cultures of the parasite were obtained in NNN medium and the identification of the species was done both by direct immunofluorescence and polymerase chain reaction–restriction fragment length polymorphism.

CONCLUSIONS: This is the first report of a VL case produced by L. (L.) mexicana in Colombia, which usually is a dermotropic species. Our report suggests that although leishmaniasis is transmitted by the bite of phlebotomine sand flies, Leishmania parasite may be transmitted by blood transfusion, complicating the clinical course of organ transplant and being fatal.
Solid‐State Compatibility in Two Regions of the System ZnO–CaO–P2O5
Authors: Carbajal Leticia , Sainz María Antonia , Serena Sara , Caballero Amador C. , Caballero Ángel
Published: March 2011

Solid‐state compatibilities in the rich tricalcium phosphate and rich zinc oxide regions of ZnO–CaO–P2O5 ternary system were established through experimental studies. These are of special interest: the tricalcium phosphate region, for further bioceramic applications, and the zinc oxide region for applications related to other fields. The objectives of this work were to establish the effect of zinc oxide on stability, phase transitions, and microstructure; therefore different compositions ranging from 0.96% to 84% mol of ZnO were thermal treated and quenched at 900°C. The crystalline phases and the microstructures were analyzed using X‐ray Diffraction (XRD) and Field‐Emission Scanning Electron Microscopy with Energy‐Dispersive Spectroscopy (FE‐SEM EDS). Moreover, refinement technique of lattice parameters using the FullProf 2k program and its graphical interface WinPLOTR enabled to establish the solid solution range of Zn2+ in β‐Ca3(PO4)2 on line joining Ca3(PO4)2–ZnO. The results allowed to determine four compatibility triangles: ZnO–Zn3(PO4)2–Zn2Ca(PO4)2, ZnO–Zn2Ca(PO4)2–Ca3(PO4)2, ZnO–Ca3(PO4)2–HAp, ZnO–HAp–CaO, and the three phase fields Zn3(PO4)2–ZnO, Ca3(PO4)2–HAp, and Ca3(PO4)2–ZnO in the system.
A Comprehensive Simulation Scheme for Tape Casting: From Flow Behavior to Anisotropy Development
Authors: Wonisch Andreas , Polfer Pit , Kraft Torsten , Dellert Armin , Heunisch Andreas , Roosen Andreas
Published: March 2011

A new simulation scheme for tape casting is presented and applied. The model allows considering both the macroscopic flow behavior and the orientation of individual particles inside the ceramic slurry. It is based on the smoothed particle hydrodynamics method, a particle‐based computational fluid dynamics solver, and Jeffery's equations of particle motion, which describe the rotation of rigid, ellipsoidal particles in a fluid. It is shown how different process parameters and the rheological behavior of the slurry influence its flow behavior, which in turn affects the orientation of nonspherical particles inside the slurry. The simulations predict that a preferred, anisotropic particle orientation develops in the green tapes, whose extent depends mainly on the powder properties. All simulations are performed with real tape‐casting data concerning geometry of casting unit, casting parameters, slurry rheology, and powder properties. The anisotropy results are confirmed by experimental analysis of cross sections of tape‐cast films made from different powders.
Restructuring Porous YSZ by Treatment in Hydrofluoric Acid for Use in SOFC Cathodes
Authors: Küngas Rainer , Kim Ju‐Sik , Vohs John M. , Gorte Raymond J.
Published: March 2011

The structure of porous yttria‐stabilized zirconia (YSZ) has been modified by infiltration with concentrated hydrofluoric acid for application in solid‐oxide fuel cell electrodes. Dissolution and precipitation of the YSZ greatly increased the surface area of the porous YSZ and formed sheets and pillars of YSZ within the structure that were largely stable to calcination at 1373 K. Electrodes made by infiltration of 35 wt% (20 vol%) La0.8Sr0.2FeO3 into the pore structure exhibited significantly lower impedances at 973 K, even after calcination to 1373 K.
Rare‐Earth‐Substituted Sr1−xLnxFe12O19 Hexagonal Ferrites
Authors: Seifert Daniela , Töpfer Jörg , Stadelbauer Markus , Grössinger Roland , Le Breton Jean‐Marie
Published: March 2011

A systematic study on the phase formation and magnetic properties of M‐type hexagonal ferrite solid solutions Sr1−xLnxFe12O19 with rare‐earth ions Ln=Pr, Nd, Sm, Eu, and Gd was performed. All ferrite samples were prepared by the mixed oxide route and characterized with a combination of powder XRD, microscopy, electron‐probe microanalysis, and thermal analysis. For Ln=Pr, Nd, and Sm, the formation of M‐type ferrite solid solutions with limited solubility of rare earths was observed. The lattice parameters of Sr1−xLnxFe12O19 exhibit a linear variation with x within the range of ferrite solid solution, i.e., c0 decreases with x. For Eu‐ and Gd‐containing samples substituted X‐type ferrites are observed. The solubility limits of the rare‐earth ions within the M‐type ferrite lattice range from x=0.46 for Pr to about x=0.17 for Sm. Eu and Gd can be substituted to lesser amounts in the X‐type ferrites. The saturation magnetization at T=5 K increases with increasing rare‐earth concentration for Pr, Nd, and Sm. Mössbauer spectrometry reveals signals originating from Fe3+ on five different crystallographic positions of the M‐type structure as well as ferrous ions on Fe 2a sites. The spectra of the hexagonal ferrites with different rare‐earth ions (La, Pr, Nd, Sm) are very similar and show systematic variations of the hyperfine fields with rare‐earth concentrations.
Compatibility of PVB of Mixed Organic Solvents in Alumina Slurries and its Effect on Morphology of Green Sheets
Authors: Furushima Ryoichi , Tanaka Satoshi , Kato Zenji , Shiomi Tomoo , Uematsu Keizo
Published: March 2011

Compatibility of poly(vinyl butyral) (PVB) to mixed organic solvents of xylene and isopropyl alcohol (IPA) was studied viscometrically in alumina slurry, and the influence on the structure of green sheets was examined by a confocal laser scanning microscopy. The PVB molecule had both butyral (hydrophobic) group and hydroxyl (hydrophilic) group. The various mixed solvents including xylene and IPA were prepared by changing the each concentration. The intrinsic viscosity of a PVB molecule in a mixed organic solvent was higher than that in the plain solvent. The homogeneous green sheets were obtained from their slurries with mixed solvents. The high intrinsic viscosity indicated the expanded conformation of the PVB molecule in the mixed solvents. The results showed that the expanded conformation of the PVB molecule in the solvents was effective for dispersion of alumina particles. The control of the compatibility of the PVB molecule and the mixed organic solvents was an important factor for fabricating the homogeneous green sheets.
Grain‐Boundary Enthalpies of Cubic Yttria‐Stabilized Zirconia
Authors: Chen Shushu , Costa Gustavo C. C. , Wang Shizhong , Munir Zuhair A. , Kim Sangtae , Navrotsky Alexandra
Published: March 2011

The change in enthalpy with grain size of dense nanograined yttria‐stabilized zirconia (YSZ) was measured by oxide melt solution calorimetry of cubic 10 YSZ and 15 YSZ dense nanograined ceramic samples prepared by spark plasma sintering of nanopowders. The derived grain‐boundary enthalpies are 0.68 J/m2 for 10 YSZ and 0.64 J/m2 for 15YSZ, with an estimated uncertainty of about+0.13 J/m2, arising mostly from the roughly +20% uncertainty in interface area calculated from the particle size distribution. These values are similar to a previous value of 0.73 ± 0.19 J/m2 for 8 YSZ, suggesting a possible weak concentration dependence (decrease of grain‐boundary energy with increasing dopant concentration) that may not be outside experimental error. Previously published interface enthalpies of 0.6–1.0 J/m2 for partially agglomerated nanopowders of 8, 10, and 12 YSZ, are in general agreement with the present data on densified nanoceramics. These data, taken together, suggest the ratio of surface to interface energy increases slightly with doping level, providing a slightly higher driving force for densification and pore elimination as the yttria content is increased.
Urinary tract infections owing to ESBL‐producing bacteria: microorganisms change – clinical pattern does not
Authors: Özçakar Zeynep Birsin , Yalçınkaya Fatoş , Kavaz Aslı , Kadıoğlu Gülsüm , Elhan Atilla H , Aysev Derya , Güriz Haluk , Ekim Mesiha
Published: March 2011

Aim:  Urinary tract infections (UTIs) caused by extended‐spectrum beta lactamase (ESBL)‐producing bacteria have become a growing problem worldwide. The aim of this study was to investigate the clinical and radiological findings in patients with community‐acquired UTIs owing to ESBL‐producing bacteria.

Methods:  Files of the patients that had UTI owing to ESBL‐producing bacteria, between January 2008 and December 2009, were retrospectively evaluated.

Results:  One hundred and eleven UTI episodes in 94 patients were included. Seventy‐five per cent of the patients had recurrent UTIs. Ultrasound, dimercaptosuccinic acid (DMSA) scintigraphy and voiding cystourethrography (VCUG) were found abnormal in 36%, 46% and 31% of the patients, respectively. Overall, 68% of the patients had ≥1 underlying predisposing factor for UTI. Male patients and acute pyelonephritis (APN) episodes were more frequent at small ages. The rate of female patients and cystitis episodes predominated with increasing age. Ultrasound, DMSA scintigraphy, VSUG and UT abnormalities were more frequent in patients with APN, and lower UT disturbances were more frequent in patients with cystitis.

Conclusion:  UTIs owing to ESBL‐producing bacteria begin to replace UTIs owing to non‐ESBL‐producing bacteria. However, the clinical pattern of these infections does not seem to be different. Thus, our aim should be to correct underlying predisposing factors in general in order to prevent infections owing to ESBL‐producing bacteria.
On minor black holes in galactic nuclei
Authors: McKernan B. , Ford K. E. S. , Yaqoob T. , Winter L. M.
Published: March 2011

Small- and intermediate-mass black holes should be expected in galactic nuclei as a result of stellar evolution, minor mergers and gravitational dynamical friction. If these minor black holes accrete as X-ray binaries or ultraluminous X-ray sources (ULXs) and are associated with star formation, they could account for observations of many low-luminosity active galactic nuclei (AGN) or low-ionization nuclear emission regions (LINERs). Accreting and inspiralling intermediate-mass black holes could provide a crucial electromagnetic counterpart to strong gravitational wave signatures, allowing tests of strong gravity. Here we discuss observational signatures of minor black holes in galactic nuclei, and we demonstrate that optical line ratios observed in LINERs or transition-type objects can be produced by an ionizing radiation field from ULXs. We conclude by discussing constraints from existing observations as well as candidates for future study.
Decreased motor unit discharge rate in the potentiated human tibialis anterior muscle
Authors: Inglis J. G. , Howard J. , McIntosh K. , Gabriel D. A. , Vandenboom R.
Published: March 2011

Aim  The purpose of this study was to examine the influence of post‐activation potentiation (PAP), the transient increase in low‐frequency isometric force observed after muscle activity, on motor unit discharge rates measured during submaximal contractions.

Methods  A quadrifilar needle electrode was inserted into the tibialis anterior muscle to determine discharge rate of individual motor units while monopolar electrodes were used to monitor the root‐mean‐square (RMS) and mean power frequency (MPF) of the surface EMG signal. Control (unpotentiated) and experimental (potentiated) measures were obtained during a 5 s voluntary contraction at 50% of maximal. In between these measures, subjects performed a 10 s maximal voluntary contraction (MVC) to induce PAP.

Results  All subjects data are reported as means ± SEM (n = 10). Compared to baseline values measured prior to the MVC, isometric twitch force measured immediately after the MVC was increased by 260 ± 16% (day 3). Motor unit discharge rate in the potentiated tibialis anterior muscle decreased by approx. 10%, from 20.3 ± 0.8 (before) to 18.3 ± 0.99 pps (P = 0.01) (after). Moreover, the MPF was decreased by approx. 9% (from 58.1 ± 2.84 to 53.6 ± 2.85 Hz; P = 0.01) in the potentiated tibialis anterior. On the other hand, consistent with the absence of fatigue during the MVC, the RMS signal was not altered in the potentiated tibialis anterior (0.29 ± 0.03 vs. 0.33 ± 0.04 mV; P = 0.07).

Conclusion  Motor unit discharge rates determined during a brief, submaximal contraction were decreased in the potentiated human tibialis anterior muscle.
Incretin physiology beyond glucagon‐like peptide 1 and glucose‐dependent insulinotropic polypeptide: cholecystokinin and gastrin peptides
Authors: Rehfeld J. F.
Published: March 2011

Gastrin and cholecystokinin (CCK) are homologous hormone systems known to regulate gastric acid secretion, gallbladder emptying, and cell growth in the pancreas and stomach. They are, however, also involved in the development and secretory functions of pancreatic islet cells. For instance, foetal and neonatal islets express significant amounts of gastrin, and human as well as porcine islet cells express the gastrin/CCK‐B receptor abundantly. Therefore, exogenous gastrin and CCK peptides stimulate insulin and glucagon secretion in man. Accordingly, endogenous hypergastrinaemia is accompanied by islet cell hyperplasia and increased insulin secretion. Conventionally, the effect of gastrointestinal hormones on insulin secretion (the incretin effect) has been defined and quantified in relation to oral versus intravenous glucose loadings. Under these unphysiological conditions, the release of gastrin and CCK and, hence, their effect on insulin secretion are modest in comparison with the effects of glucose‐dependent insulinotropic polypeptide and glucagon‐like peptide 1 (GLP‐1). Consequently, the interest of CCK and gastrin in incretin research has for decades been limited. A few years ago, however, it was suggested that gastrin together with epidermal growth factor or later GLP‐1 might stimulate beta cell growth and secretion. Recent studies have shown that the combination of gastrin and GLP‐1 actually restores normoglycaemia in diabetic mice. Therefore, a short review of the incretin system in a broader functional context that includes gastrin and CCK peptides may be timely.
Morphological features of elderly patients with obstructive sleep apnoea syndrome: a prospective controlled, comparative cohort study
Authors: Tagaya M. , Nakata S. , Yasuma F. , Noda A. , Hamajima N. , Katayama N. , Otake H. , Teranishi M. , Nakashima T.
Published: March 2011

Clin. Otolaryngol. 2011, 36, 139–146

Objectives:  To investigate the pharyngeal morphologic features and its pathogenic role on obstructive sleep apnoea syndrome in the elderly population.

Design:  Prospective controlled, comparative cohort study.

Setting:  Territory referral centre.

Participants:  We enroled 320 consecutive patients with complaints of snoring who visited Nagoya University Hospital from January 2004 to December 2007. We also collected 26 control subjects aged over 60 years from community‐dwelling people.

Main outcome measures:  We underwent a morphological evaluation, measurement of nasal resistance, assessment of daytime sleepiness and nocturnal polysomnography.

Results and conclusions:  Two hundred and ninety‐two patients were analysed. The constitution ratio of men, the body mass index and Epworth sleepiness scale were decreased with ageing. Tonsil size was reduced progressively with ageing. Retroglossal space was wider, and soft palate was lower in ≥60 year group than in <40 year group. Retroglossal space was wide in elderly patients with sleep apnoea compared with control subjects. Tonsil size was not correlated to apnoea/hypopnoea index in ≥60 year group unlike the other generations. Modified Mallampati Score and tongue size were significantly but mildly correlated only in ≥60 year group. Width of fauces was correlated in all the groups. Multiple regression analysis showed that body mass index, age, gender, tonsil size and width of fauces were independent factors for apnoea/hypopnoea index.

Conclusions:  Morphologically, the tonsil could play a minor role but the width of fauces could play relatively a major role. Additionally, wide retroglossal space, low positional soft palate and large tongue size may be characteristics for elderly patients of obstructive sleep apnoea syndrome.
Inequality as an Explanation for Obesity in the United States
Authors: Lee Hedwig
Published: March 2011

Over the past several decades, there has been a sharp increase in obesity across all population groups in the United States. In fact, the United States has one of the highest rates of obesity compared to other countries throughout the world. Obesity has become a national public health concern because it is related to a number of negative health, social, psychological, and economic outcomes. It is particularly concerning because racial/ethnic minorities and populations with the least education and highest poverty rates bear the largest burden of obesity. In addition, disparities in obesity tend to be gendered, with women experiencing the largest disparities in obesity by income, education, and race/ethnicity. In this review, I describe how social inequality is linked to obesity in the United States. I highlight elements of disadvantage at the individual‐, family‐, school‐, and neighborhood‐level that are linked to energy intake and expenditure, which are directly related to obesity, and draw from evidence and theories from multiple fields of the social and medical sciences. I also highlight the important role stress may play in linking disadvantage to obesity, particularly for women. I argue that understanding the complex mechanisms and processes that link social inequality to obesity requires multidisciplinary and multilevel frameworks.
Politics and Celebrity: A Sociological Understanding
Authors: McKernan Brian
Published: March 2011

Many social commentators have denounced the election of entertainment celebrities such as Arnold Schwarzenegger, Jesse Venture, and Al Franken to political offices as indicative of American democracy’s collapse, treating the political victories by these celebrities as evidence of America’s preference for entertainment over political deliberation. This essay reviews the scholarly literature on celebrity and politics to provide a better understanding of this important topic. As the literature demonstrates, this conflation of celebrity and politics is not a recent phenomenon, as politicians have long employed dramaturgical elements to mobilize constituencies. Indeed, celebrities and politicians share many similarities. Both must construct public personalities appealing to their audiences and employ similar actors and strategies to help create these personalities. While some scholars working in this field agree with the concern that celebrity’s presence in politics inhibits serious political discourse, other scholars contend that the use of celebrity performances by politicians may actually attract a wider segment of society to meaningfully participate in politics. The essay concludes by suggesting that future works in this area should adopt a cultural sociology framework to empirically study the meaning of celebrity for different social groups in order to gain a stronger understanding of celebrity’s sociopolitical impact.
Asset Write‐downs: Evidence from 2001–2008
Authors: Spear Nasser A. , Taylor Alexandra M.
Published: March 2011

Accounting for asset write‐downs has received substantial media attention throughout the Global Financial Crisis and has been the subject of academic debate and numerous accounting regulations during the past three decades. This study provides evidence of the magnitude and frequency of quarterly asset write‐down activities for a sample of US firms between 2001 and 2008 and examines whether reported asset write‐downs mirror market and economic indicators during the sample period.
The Association Between Earnings and Returns and Macroeconomic Performance: Evidence from Australia, the US and China
Authors: Clinch Greg , Wei Zi
Published: March 2011

This paper provides some initial descriptive and exploratory results concerning the earnings‐returns relation in periods of poor versus strong macroeconomic performance. Based on data from three countries – Australia, the US and China – the results indicate some differences for US and Chinese firms, but not Australian firms. However the results for US and Chinese firms are somewhat contradictory – US (Chinese) firms generally exhibit a stronger (weaker) earnings‐returns association in periods of both negative and strongly positive macroeconomic performance. These differences appear largely attributable to reported profits and not to losses. No evidence is found that poor earnings news released during periods such as the Global Financial Crisis is ‘punished’ relative to other periods.
Audit Reports in Australia during the Global Financial Crisis
Authors: Xu Yang , Jiang Alicia Liwei , Fargher Neil , Carson Elizabeth
Published: March 2011

The Global Financial Crisis reduced economic growth, impacted equity and credit markets, and increased business risk. To the extent that this increased risk translates into greater uncertainty of companies’ ability to continue as going concerns, this should be reflected in audit reports. This paper investigates how the crisis impacted auditor reporting in Australia by examining the period 2005–2009. It finds that the main reason for audit report modification is going concern and that modification rates increased from 12% in 2005–2007 to 18% in 2008 and 22% in 2009. Serious audit report qualification rates remain around 3%.
Commentary: On the Desirability of Common Financial Reporting Standards for Business and Government
Authors: Holder William W.
Published: March 2011

An important financial reporting issue relates to the extent, if any, to which financial reporting standards should differ for businesses and governments. At a high level of abstraction little dispute exists that common financial reporting concepts for both types of organisations are appropriate (for example, financial reporting should provide useful information). As one focuses on more specific financial reporting objectives, however, the issue becomes more contentious. This paper addresses this issue by considering differences in financial reporting objectives between the types of organisations and evaluating whether such differences are of sufficient import to warrant substantially different financial reporting standards.
A New Method for Measuring Thermal Contact Conductance—Experimental Technique and Results
Authors: Woodland Simon , Crocombe Andrew D. , Chew John W. , Mills Stephen J.
Published: March 2011

Thermal contact conductance (TCC) is used to characterize heat transfer across interfaces in contact. It is important in thermal modeling of turbomachinery components and finds many other applications in the aerospace, microelectronic, automotive and metal working industries. In this paper, a new method for measuring TCC is described and demonstrated. A test rig is formed from an instrumented split tube with in-line washers and loading applied under controlled conditions. The experimental method and data analysis are described, and the effects on thermal contact conductance of important parameters such as the contact pressure, surface roughness, temperature, thermal conductivity, and material strength are investigated. Normalization of the TCC measured in the experimental program was carried out using appropriate surface and material parameters. The results of this normalization are used to compare the normalized experimental results with various models from the literature.
Reduction of Forced Response Levels for Bladed Disks by Mistuning: Overview of the Phenomenon
Authors: Petrov E. P.
Published: March 2011

The newly revealed phenomenon of reduction of forced response levels in a mistuned bladed disk to levels significantly (e.g., by a factor of 2 and more) lower than that of its tuned counterpart is studied in detail on an example of a realistic bladed disk. Statistical properties of the amplification factor of the mistuned forced response calculated with aero-effects included have been studied for cases of random blade mistuning and for mistuned blade rearrangements. The optimization search for the best mistuning patterns providing maximum forced response reduction effect have been performed and the robustness of the optimum mistuning patterns has been demonstrated. The combined effect of the aerodynamic and structural damping on the response reduction is assessed. It is shown that the new phenomenon is of major practical significance and has to be taken into account in analysis of the forced response and design decisions.
Correcting INS Drift in Terrain Surface Measurements
Authors: Chemistruck Heather M. , Binns Robert , Ferris John B.
Published: March 2011

Modern terrain measurement systems use an inertial navigation system (INS) to measure and remove vehicle movement from laser measurements of the terrain surface. Instrumental and environmental biases inherent in the INS produce noise and drift errors in these measurements. The evolution and implications of terrain surface measurement techniques and existing methods for correcting INS drift are reviewed as a framework for a new compensation method for INS drift in terrain surface measurements. Each measurement is considered a combination of the true surface and the error surface, defined on a Hilbert vector space, in which the error is decomposed into drift (global error) and noise (local error). The global and local subspaces are constructed such that the drift is modeled as a random walk process and the noise is a zero-mean process. This theoretical development is coupled with careful experimental design to identify the drift component of error and discriminate it from true terrain surface features, thereby correcting the INS drift. It is shown through an example that this new compensation method dramatically reduces the variation in the measured surfaces to within the resolution of the measurement system itself.
A Geometric Approach to Dynamically Feasible, Real-Time Formation Control
Authors: Maithripala D. H. A. , Maithripala D. H. S. , Jayasuriya S.
Published: March 2011

We propose a framework for synthesizing real-time trajectories for a wide class of coordinating multi-agent systems. The class of problems considered is characterized by the ability to decompose a given formation objective into an equivalent set of lower dimensional problems. These include the so called radar deception problem and the formation control problems that fall under formation keeping and/or formation reconfiguration tasks. The decomposition makes the approach scalable, computationally economical, and decentralized. Most importantly, the designed trajectories are dynamically feasible, meaning that they maintain the formation while satisfying the nonholonomic and saturation type velocity and acceleration constraints of each individual agent. The main contributions of this paper are (i) explicit consideration of second order dynamics for agents, (ii) explicit consideration of nonholonomic and saturation type velocity and acceleration constraints, (iii) unification of a wide class of formation control problems, and (iv) development of a real-time, distributed, scalable, computationally economical motion planning algorithm.
Integrated System ID and Control Design for an IC Engine Variable Valve Timing System
Authors: Ren Zhen , Zhu Guoming G.
Published: March 2011

This paper applies integrated system modeling and control design process to a continuously variable valve timing (VVT) actuator system that has different control input and cam position feedback sample rates. Due to high cam shaft torque disturbance and high actuator open-loop gain, it is also difficult to maintain the cam phase at the desired constant level with an open-loop controller for system identification. As a result, multirate closed-loop system identification becomes necessary. For this study, a multirate closed-loop system identification method, pseudo-random binary signal q-Markov Cover, was used for obtaining linearized system models of the nonlinear physical system at different engine operational conditions; and output covariance constraint (OCC) controller, an H2 controller, was designed based upon the identified nominal model and evaluated on the VVT test bench. Performance of the designed OCC controller was compared with that of the well-tuned baseline proportional-integral (PI) controller on the test bench. Results show that the OCC controller uses less control effort and has significant lower overshoot than those of PI ones.
Design Modifications for Energy Conservation of Sponge Iron Plants
Authors: Prasad A. K. , Prasad R. K. , Khanam S.
Published: March 2011

During the operation in the coal based sponge iron plant, a tremendous amount of heat is generated and significant part of this heat, associated with the waste gas, remains unutilized. It appears worth interesting to modify the process that facilitates the integration of heat available with the waste gas. In the present paper, for the utilization of heat of waste gas, two modifications, namely, case-1 and case-2, are proposed based on preheating of inlet streams. In case-1, preheating of feed material is considered, whereas in case-2, preheating of feed material as well as air is accounted. These cases are then compared with the existing waste heat recovery system of the plant based on coal consumption, operating and capital costs, profit, and payback period. It is found that both cases are better than the existing heat recovery system of the plant. However, case-2 is selected as the best heat recovery option. In comparison to the existing system, case-2 reduces coal and water consumption by 30.5% and 72.6%, respectively. Further, case-2 releases minimum waste gas to the atmosphere that makes the process environment friendly.
Analysis of Radiation Modeling for Turbulent Combustion: Development of a Methodology to Couple Turbulent Combustion and Radiative Heat Transfer in LES
Authors: Poitou Damien , El Hafi Mouna , Cuenot Bénédicte
Published: March 2011

Radiation exchanges must be taken into account to improve large eddy simulation (LES) prediction of turbulent combustion, in particular, for wall heat fluxes. Because of its interaction with turbulence and its impact on the formation of polluting species, unsteady coupled calculations are required. This work constitutes a first step toward coupled LES-radiation simulations, selecting the optimal methodology based on systematic comparisons of accuracy and CPU cost. Radiation is solved with the discrete ordinate method (DOM) and different spectral models. To reach the best compromise between accuracy and CPU time, the performance of various spectral models and discretizations (angular, temporal, and spatial) is studied. It is shown that the use of a global spectral model combined with a mesh coarsening (compared with the LES mesh) and a minimal coupling frequency Nit allows to compute one radiative solution faster than Nit LES iterations while keeping a good accuracy. It also appears that the impact on accuracy of the angular discretization in the DOM is very small compared with the impact of the spectral model. The determined optimal methodology may be used to perform unsteady coupled calculations of turbulent combustion with radiation.
Application of Nonlinear Turbulence Models for Marine Propulsors
Authors: Kaewkhiaw Prachakon , Tiaple Yodchai , Dechaumphai Pramote , Juntasaro Varangrat
Published: March 2011

The realistic simulation of cavitation on a marine propeller is important for the efficient design of the propeller. However, the flow characteristic that occurred on the marine propeller is complicated and difficult to predict due to the combined effects of turbulence, cavitation, and multiphase phenomena. There is still currently no turbulence model that can predict these combined effects satisfactory. The nonlinear turbulence model is therefore modified and applied to predict the cavitation on a marine propeller for the first time in this work. It is found that the nonlinear turbulence model can predict the cavitation and hence the thrust and torque coefficients much more accurately than the existing Reynolds-averaged Navier–Stokes turbulence models including the Reynolds-stress model.
Direct Numerical Simulation of Single and Multiple Square Jets in Cross-Flow
Authors: Yao Y. , Maidi M.
Published: March 2011

Direct numerical simulations (DNSs) have been carried out for single and multiple square jets issuing normally into a cross-flow, with the primary aim of studying the flow structures and interaction mechanisms associated with the jet in cross-flow (JICF) problems. The single JICF configuration follows a similar study previously done by Sau et al. (2004, Phys. Rev. E, 69, p. 066302) and the multiple JICF configurations are arranged side-by-side in the spanwise direction with a jet-to-jet adjacent edge distance (H) for the twin-jet case and an additional third jet downstream along the centerline with a jet-to-jet adjacent edge distance (L) for the triple-jet case. Simulations are performed for two twin-jet cases with H=1D,2D, respectively, and for one triple-jet case with H=1D, L=2D, where D is the jet exit width. Flow conditions similar to Sau et al. are considered, i.e., the jet to the cross-flow velocity ratio R=2.5 and the Reynolds number 225, based on the freestream velocity and the jet exit width. For the single jet in cross-flow, the vortical structures from our DNS are in good qualitative agreement with the findings of Sau et al. For the side-by-side twin-jet configuration, results have shown that the merging process of the two initially separated counter-rotating vortex pairs (CRVPs) from each jet hole exit is strongly dependent on the jet-to-jet adjacent edge distance H with earlier merging observed for the case H=1D. Downstream, the flow is dominated by a larger CRVP structure, accompanied by a smaller inner vortex pair. The inner vortex pair is found not to survive in the far-field as it rapidly dissipates before exiting the computational domain. These observations are in good agreement with the experimental findings in the literature. Simulations of the triple-jet in cross-flow case have shown some complicated jet-jet and jet-cross-flow interactions with three vortex pairs observed downstream, significantly different from that seen in the twin-jet cases. The evidence of these flow structures and interaction characteristics could provide a valuable reference database for future in-depth flow physics studies of laboratory experimental and numerical investigations.
Thermal Management of a 15 kV/100 kVA Intelligent Universal Transformer
Authors: Warzoha Ronald , Fleischer Amy S.
Published: March 2011

The thermal management of power electronics presents a significant challenge to thermal engineers due to high power loads coupled with small footprints. Inadequate thermal dissipation of these loads can lead to excessively high equipment temperatures and subsequent system failure. In this study, a unique power electronics-based transformer, called the intelligent universal transformer (IUT), is thermally analyzed using the computational fluid dynamics software ICEPAK. The objective of this work is to examine the use of a finned heat pipe array for the power electronics in the IUT. A design sensitivity study was performed to determine the effect of the number of fins attached to the heat pipe array, the number of heat pipes in the heat pipe array, and the fin material on the steady-state operating temperature of the power electronics. It was determined that a set of 33 copper fins attached to an array of 36 heat pipes on each side of the containment unit is sufficient for continuous operation of the power electronics. This analysis and thermal management solution will be applicable not only to this situation but also to other high density power electronics applications.
Tip and Junction Vortices Generated by the Sail of a Yawed Submarine Model at Low Reynolds Numbers
Authors: Jiménez Juan M. , Smits Alexander J.
Published: March 2011

Results are presented on the behavior of the tip and junction vortices generated by the sail of a SUBOFF submarine model at yaw angles from 6 deg to 17 deg for a Reynolds number of 94×103 based on model length. The measurements were conducted in a water channel on a spanwise plane 1.3 chord lengths downstream from the trailing edge of the sail. In the vicinity of the sail hull junction, the presence of streamwise vortices in the form of horseshoe or necklace vortices locally dominates the flow. As the yaw angle is increased from 6 deg to 9 deg, the circulation of the sail tip vortex increases, and is in good accordance with predictions from finite wing theory. However, as the yaw angle is further increased, the sail boundary layer separates with an overall drop in circulation. In contrast, the circulation value for the junction vortex increases with yaw angle, and only drops slightly at the highest yaw angle.
Design Technology of Centrifugal Fan Impeller Based on Response Surface Methodology
Authors: Zhu Changyun , Qin Guoliang
Published: March 2011

An optimization strategy called response surface methodology (RSM) is applied to a centrifugal fan impeller optimization design in this paper. RSM is used to generate an approximated model of objective function, for which a second-order polynomial function is chosen. The Design of experiment (DOE) technique coupled with CFD analysis is then ran to generate the database. The least-squares regression method (LS) is used to determine the coefficient of the RSM function. Finally, the Genetic Algorithms (GA) is applied to the objective function in order to obtain the optimal configuration. This paper also presents a solution to the problem of imprecise fitting of second-order RSM model by dividing the zone into several subzones which is proved to be effective in this paper. The optimization result shows that RSM is an effective and feasible optimization strategy for the centrifugal fan impeller design, and the complexity of the objective function and the overall optimization time could be significantly reduced.
New Method and Algorithm of Three-Dimensional Turbine Guide Blade Rim Optimization
Authors: Boiko Anatoli , Govorushchenko Yuri , Burlaka Maksym
Published: March 2011

The new method and algorithm of three-dimensional turbine guide blade rim optimization were proposed using CFD-calculations, guide blade deformation and reasonable computation time consuming optimization approach. Verification of three-dimensional CFD-calculations results are presented by comparison with experimental data. The reasonableness of the isolated guide blade rim optimization of a turbine stage is justified. Two methods of the complex tangential lean implementation are compared. The parametric model is developed allowing conservation of the mass flow rate through the blade passage during optimization process. Both a bowing method and computational grids construction are realized in specialized program TOpGrid. The gained grids has been written in format CGNS (CFD General Notation System). The optimization approach is grounded on a combination of the DOE theory and Monte-Carlo method. The algorithm of optimization of guide blade rim is described. The examination of aerodynamic optimization efficiency with the developed algorithm of a guide blade rim at different a/l (a-throat of the channel, l-height of a blade) was carried out. The analysis of the results of the computation and physical explanation of reasons of a turbine blade passage efficiency rise is given.
Numerical Anaysis of a Thermopneumatic Micropump
Authors: Shahsavari S. , Shafii M. B. , Saidi M. H.
Published: March 2011

Thermopneumatic micropump is one type of positive displacement micropump, which has many applications due to its relatively large stroke volume, low working voltage, and simple fabrication in microscale. In this paper, a numerical study of heat transfer and fluid flow in a valveless thermopneumatically driven micropump is presented. For rectifying the bidirectional flow, a nozzle and a diffuser are used as the inlet and outlet channels of the chamber. Since the fluid flow is induced by the motion of a diaphragm, the numerical simulation includes fluid structure interaction, which requires applying a dynamic mesh. The domain of solution is divided into two sections; the actuator unit, which contains the secondary fluid, and the main chamber through which the working fluid is passing. The temperature distribution, the pressure variations, and the center deflection of the diaphragm are obtained. In order to validate the model, the numerical results are compared with some experimental data, which shows fair consistency. According to the results of the three dimensional simulation, the rectification efficiency for the nozzle and diffuser channels depends on the frequency.
Study on Improving the Flow in Forebay of the Pumping Station
Authors: Liu Chao , Zhou Jiren , Cheng Li , Jin Yan , Han Xu
Published: March 2011

The flow pattern in the forebay of pumping station is of very important influence on the operation of the pumps. The different kinds of unlike flow pattern, such as large scale circulations and vortices, are often found in the forebay of pumping station especially with multi-pumps. This paper takes the study on improving the flow pattern in the forebay to ensure a good flow condition for pumps operation. The computational results of three dimensional flow fields in an original designed forebay were obtained and a large circulation was found in the forebay on the side which caused serious problems to the operation of pumps. A typical combined means were applied to improve the flow motion. The computational results of the flow fields shows that the large circulation was eliminated and the flow distribution was improved, which was verified by the model test. The improved design has been successfully used to a large pumping station.
Investigation of Scramjet Inlet Flow Using a Flux-Splitting Solver
Authors: Holian D. M. , Mankbadi R. R.
Published: March 2011

A detailed analysis is carried out on a rectangular scramjet inlet to analyze the flow field. The focus is on examining boundary layer separation and shock interactions to ensure proper operation of the inlet. We developed herein a flux-splitting Navier Stokes solver to be used for optimizing the inlet geometry and operation conditions. The results seem to be in good agreement with that of FLUENT CFD software and explain the experimental results of Haberle (2008).
Microfluidic Pumping With Optically Induced Actuation of a Carbon Nanotube Membrane
Authors: Duff Joseph D. , Williams Stuart J. , Panchapakesan Balaji
Published: March 2011

We present the design; fabrication and testing of a Polydimethylsiloxane (PDMS)-based microfluidic pump with optically induced membrane actuation. The thin membrane consists of a layer of PDMS (100 μm) and a layer of carbon nanotubes (190 nm). An applied infrared laser opto-mechanically activates the film of carbon nanotubes (CNT), leading to membrane deformation and subsequent fluid motion. Photomechanical actuation offers an alternative way to drive microfluidic devices and provides distinct advantages over alternative methods. The advantages include simplistic, low-cost device fabrication, Wireless actuation, remote controllability electrical–mechanical decoupling, low noise and the elimination of electrical circuits. The performance of this pump in terms of pressure head and flow rate is substantially high. In addition, the micro pump is self-priming and insensitive to particles and bubbles in the pumped media.