bluuebunny/crossref_metadata_2025 huggingface dataset:
Prospective evaluation of complications associated with jugular venous catheter use in a veterinary hospital
Authors: Adamantos S. , Brodbelt D. , Moores A. L.
Published: April 2010

Objectives: To prospectively investigate the incidence of mechanical and infectious complications associated with the use of jugular catheters and risk factors for these complications.

Methods: Data was collected over a 6‐month period and risk factors associated with the occurrence of mechanical or inflammatory complications were investigated.

Results: One hundred catheters were placed over a 6‐month period, totalling 393 catheter days. Complications were seen in 39% of catheters with a total of 51 complications. Forty‐one of these complications were mechanical. A total of 10 inflammatory or infectious complications were identified in eight catheters (a total of 0·03 infectious complications per catheter day). Complications were more likely to occur in patients requiring more than one attempt for placement and patients that were ASA status 3 to 5. Infectious complications were more likely in patients not having general anaesthesia for placement, those having medical rather than surgical disease and those placed out of theatre. No association was found between the skill of the person placing the catheter and risk of complication.

Clinical Significance: Mechanical complications are frequently associated with jugular catheter placement. Identification of risk factors for complications is important and warrants further study.
An epidemiological study of environmental factors associated with canine obesity
Authors: Courcier E. A. , Thomson R. M. , Mellor D. J. , Yam P. S.
Published: April 2010

Objectives: To assess the relationships between socioeconomic and other environmental factors with canine obesity.

Methods: This was a cross‐sectional questionnaire study of dog owners attending five primary veterinary practices in the UK. Owners were asked about dog age, neuter status, feeding habits, dog exercise, household income and owner age. The body condition score of the dogs was also assessed. Factors hypothesised to be associated with obesity were investigated.

Results: In total, data from 696 questionnaires were evaluated. Out of those data evaluated, 35·3% of dogs (n=246) were classed as an ideal body shape, 38·9% (n=271) were overweight, 20·4% (n=142) were obese and 5·3% (n=37) were underweight. Identified risk factors associated with obesity included owner age, hours of weekly exercise, frequency of snacks/treats and personal income.

Clinical Significance: Environmental risk factors associated with canine obesity are multifactorial and include personal income, owner age, frequency of snacks/treats and amount of exercise the dog receives. Awareness about health risks associated with obesity in dogs is significantly less in people in lower income brackets. This phenomenon is recognised in human obesity.
Religion and Country Music
Authors: Hayes John
Published: April 2010

Country music as a commercial genre began in a society where religion exerted considerable cultural influence – the U.S. South of the 1920s. Musicians of the white working‐class recorded songs for national record companies, who codified their oeuvres into a form they called “hillbilly” music, or what we know as the first country music. Hillbilly music bore the clear imprint of working‐class religion, a folk form of Protestantism that took shape in the late nineteenth century. Over the music’s subsequent history, folk Protestantism receded as an influence as the white working‐class went through drastic economic change and dislocation. Country music after the mid‐1950s sang less of longings defined by religion and more of secular working‐class life. In the 1970s, a newer, national Protestant movement – evangelicalism – made some inroads, primarily in the personal lives of country musicians. More recently, the quasi‐religion of U.S. nationalism has informed popular country music songs, even as a distinct regional or working‐class character has faded from the music, in fan base, image, or personal background of musicians.
Partial Colocalization of Oxidized, N‐formylkynurenine‐containing Proteins in Mitochondria and Golgi of Keratinocytes†
Authors: Ehrenshaft Marilyn , Bonini Marcelo G. , Feng Li , Chignell Colin F. , Mason Ronald P.
Published: April 2010

Proteins are the dominant cellular target for oxidative reactions because they comprise the majority of macromolecules. Posttranslational oxidative protein modifications include fragmentation, aggregation and alteration of specific amino acid residues. The amino acids and amino acid residues most susceptible to oxidative modification are those containing sulfur and those with aromatic rings. Tryptophan reacts with radicals, ozone and singlet oxygen to form the end product N‐formylkynurenine (NFK). We recently described a novel anti‐NFK antiserum and validated its use in immunological assays for the specific detection of NFK in isolated proteins and protein mixtures. Here we photo‐oxidize rose bengal‐containing HaCaT keratinocyte cells and examine the results using fluorescent confocal microscopy and staining with anti‐NFK antiserum and markers for both Golgi and mitochondria. We show that photosensitization mediates the accumulation of NFK and that NFK can be detected in photosensitized cells with only slightly decreased viability. Additionally, we detect NFK‐modified proteins in both Golgi and mitochondria of photosensitized cells. These experiments demonstrate that we have developed a tool for the specific detection of oxidized tryptophan residues in cells and suggest that this tool could be useful in tracking the fate of these oxidized proteins.
One‐electron Oxidation of a Pyrenyl Photosensitizer Covalently Attached to DNA and Competition Between its Further Oxidation and DNA Hole Injection
Authors: Yun Byeong Hwa , Dedon Peter C. , Geacintov Nicholas E. , Shafirovich Vladimir
Published: April 2010

The photosensitized hole injection and guanine base damage phenomena have been investigated in the DNA sequence, 5′‐d(CATG1PyCG2TCCTAC) with a site‐specifically positioned pyrene‐like (Py) benzo[a]pyrene 7,8‐diol 9,10‐epoxide‐derived N2‐guanine adduct (G1Py). Generation of the Py radical cation and subsequent hole injection into the DNA strand by a 355 nm nanosecond laser pulses (∼4 mJ cm−2) results in the transformation of G1Py to the imidazolone derivative Iz1Py and a novel G1Py* photoproduct that has a mass larger by 16 Da (M+16) than the mass (M) of G1Py. In addition, hole transfer and the irreversible oxidation of G2, followed by the formation of Iz2 was observed (Yun et al. [2007], J. Am. Chem. Soc., 129, 9321). Oxygen‐18 and deuterium isotope labeling methods, in combination with an extensive analysis of the MS/MS fragmentation patterns of the individual dGPy* nucleoside adduct and other data show that dGPy* has an unusual structure with a ruptured cyclohexenyl ring with a carbonyl group at the rupture site and intact guanine and pyrenyl residues. The formation of this product competes with hole injection and thus diminishes the efficiency of oxidation of guanines within the oligonucleotide strand by at least 15% in comparison with that in the dGPy nucleoside adduct.
Insights From Internet‐Based Remote Intrathoracic Impedance Monitoring as Part of a Heart Failure Disease Management Program
Authors: Mullens Wilfried , Oliveira Leonardo P. J. , Verga Tanya , Wilkoff Bruce L. , Wilson Tang Wai Hong
Published: April 2010

Changes in intrathoracic impedance (Z) leading to crossing of a derived fluid index (FI) threshold has been associated with heart failure (HF) hospitalization. The authors developed a remote monitoring program as part of HF disease management and prospectively examined the feasibility and resource utilization of monitoring individuals with an implanted device capable of measuring Z. An HF nurse analyzed all transmitted data daily, as they were routinely uploaded as part of quarterly remote device monitoring, and called the patient if the FI crossed the threshold (arbitrarily defined at 60 Ω) to identify clinically relevant events (CREs) that occurred during this period (eg, worsening dyspnea or increase in edema or weight). A total of 400 uploads were completed during the 4‐month study period. During this period, 34 patients (18%) had an FI threshold crossing, averaging 0.52 FI threshold crossings per patient‐year. Thirty‐two of 34 patients contacted by telephone (94%) with FI threshold crossing had evidence of CREs during this period. However, only 6 (18%) had HF hospitalizations, 19 (56%) had reported changes in HF therapy, and 13 (38%) reported drug and/or dietary plan nonadherence. The average data analysis time required was 30 min daily when focusing on those with FI threshold crossing, averaging 8 uploads for review per working day and 5 telephone follow‐ups per week. Our pilot observations suggested that Internet‐based remote monitoring of Z trends from existing device interrogation uploads is feasible as part of a daily routine of HF disease management.Congest Heart Fail. 2010;16:159–163. © 2010 Wiley Periodicals, Inc.
Masked Hypertension Defined by Ambulatory Blood Pressure Monitoring Is Associated With an Increased Serum Glucose Level and Urinary Albumin‐Creatinine Ratio
Authors: Ishikawa Joji , Hoshide Satoshi , Eguchi Kazuo , Schwartz Joseph E. , Pickering Thomas G. , Shimada Kazuyuki , Kario Kazuomi
Published: April 2010

J Clin Hypertens(Greenwich). 2010;12:578–587. © 2010 Wiley Periodicals, Inc.

The authors evaluated the relationship of hypertensive target organ damage to masked hypertension assessed by ambulatory blood pressure (BP) and home blood pressure (HBP) monitoring in 129 participants without taking antihypertensive medication. Masked hypertension was defined as office BP ≤140/90 mm Hg and 24‐hour ambulatory BP ≥130/80 mm Hg. The masked hypertensive participants defined by 24‐hour ambulatory BP (n=13) had a higher serum glucose level (126 vs 96 mg/dL, P=.001) and urinary albumin‐creatinine ratio (38.0 vs 7.5 mg/gCr, P<.001) than the normotensive participants (n=74); however, these relationships were not observed when the authors defined groups using HBP (≥135/85 mm Hg). Masked hypertension by both 24‐hour ambulatory BP and HBP had a higher urinary albumin‐creatinine ratio than normotension by both 24‐hour ambulatory BP and HBP (62.1 vs 7.4 mg/gCr, P=.001), and than masked hypertension by HBP alone (9.3 mg/gCr, P=.009). Masked hypertension defined by 24‐hour ambulatory BP is associated with an increased serum glucose level and urinary albumin‐creatinine ratio, but these relationships are not observed in masked hypertension defined by HBP.
Assessment of Endothelial Function by Means of Flow‐Mediated Changes Using Pulse Wave Velocity
Authors: Rusak Eduardo J. , Bellido Claudio A. , Iavicoli Oscar R. , Vazquez Sonia T. , Duarte Mariano , Lerman Jorge
Published: April 2010

J Clin Hypertens (Greenwich). 2010;12:495–501. © 2010 Wiley Periodicals, Inc.

Endothelial dysfunction is a leading cause of early development of cardiovascular diseases. Endothelial function can be assessed using ultrasound methods to watch the arterial flow‐mediated dilation. It is also possible to find changes in pulse wave velocity (PWV) after induced ischemia related to the vessel diameter changes. Pre‐ and post‐induced ischemia carotid‐radial PWV was recorded in 226 hypertensive patients (150 women [63.5±12.4 years old] and 76 men [63.2±11.8 years old] and 55 healthy patients (38 women [63.1±12.6 years old] and 17 men [54.8±12.8 years old]). The authors considered normal endothelial function a PWV reduction of 5% from baseline. To assess nondependent endothelial dilation the authors performed carotid‐radial PWV after sublingual administration of 5 mg of isosorbide dinitrate in a group of patients with abnormal flow‐mediated dilation. A significant PWV reduction of 9.8% in normal patients and only 1.2% among hypertensive patients (P<.0005) was found. After sublingual isosorbide dinitrate intake the authors observed a greater fall in PWV (14%) than that observed in healthy people after induced ischemia. Carotid‐radial PWV after induced ischemia decreased significantly in normal participants. No significant changes were observed in hypertensive patients. These results may offer a reliable tool to assess endothelial function in medium‐size arteries.
Health Economics Perspective of the Components of the Cardiometabolic Syndrome
Authors: Tamariz Leonardo , Palacio Ana , Yang Yadong , Parris Donald , Ben‐Joseph Rami , Florez Hermes
Published: April 2010

J ClinHypertens (Greenwich). 2010;12:549–555. © 2010 Wiley Periodicals, Inc.

The components of the cardiometabolic syndrome (CMS) increase the risk of coronary artery disease (CAD). The authors compared 12‐month costs of subjects with different number of components of the CMS. In claims data from a large health benefits company, 383,420 individuals with the first International Classification of Diseases, Ninth Revision codes for hypertension, diabetes, lipid abnormalities, and obesity were identified. Patients were stratified according to presence of CAD and the number of components of the CMS. Twelve‐month costs were added after the identification of the risk factor. Mean annual costs increased with the number of components of CMS both in those with and without CAD, even after adjusting for age, sex, and comorbidities (P<.01). Similar trends were seen for medical and pharmacy costs. The adjusted total annual health care cost in those with an isolated component of the CMS was $5564 (95% confidence interval: $5491–$5631) while in those with 4 components was $12,287 (95% confidence interval: $11,987–$12,587). Individuals with accumulating components of the CMS have higher health care costs regardless of age, sex, and other comorbidities.
Habitat‐mediated size selection in endangered Atlantic salmon fry: selectional restoration assessment
Authors: Bailey Michael M. , Kinnison Michael T.
Published: April 2010

Preservation of adaptive variation is a top priority of many species restoration programs, but most restoration activities are conducted without direct knowledge of selection that might foster or impair adaptation and restoration goals. In this study, we quantified geographic variation in selection on fry size of endangered Atlantic salmon (Salmo salar) during the 6‐week period immediately following stocking in the wild. We also used a model selection approach to assess whether habitat variables influence patterns of such selection. We found evidence for significant size‐selection in five out of six selection trials. Interestingly, the strength and pattern of selection varied extensively among sites, and model selection suggested that this variation in phenotypic selection was related to geographic variation in the presence of large woody debris and the slope of the stream gradient. The strong selection differentials we observed should be a concern for endangered salmon restoration, whether they reflect natural processes and an opportunity to maintain adaptation, or an indicator of the potentially deleterious phenotypic consequences of hatchery practices.
Individualized optimization of the screening interval for diabetic retinopathy: a new model
Authors: Mehlsen Jesper , Erlandsen Mogens , Poulsen Per Løgstrup , Bek Toke
Published: April 2010

Introduction: Screening programmes for diabetic retinopathy follow guidelines that ensure that vision‐threatening complications are detected even when the disease progression is fast. This implies that patients with slow disease progression will be recommended examinations more often than needed.

Method: On the basis of previously defined individual risk factors, multiple logistic regression was used to develop a model for individualized determination of the screening interval in diabetic retinopathy, while adjusting for the fact that in the data set used to construct the model, the screening interval acted as a time‐dependent confounder. The model was tested on 1372 patients screened during year 2000.

Results: It was possible to construct a model for calculating the optimal screening interval in low‐risk patients in whom the recommended screening interval was longer than 12 months. When the probability of reaching a treatment requiring event was set to 0.5%, none of the patients reached a treatment end‐point in a validation of the model, and the screening interval was prolonged on average 2.9 times in patients with type 1 diabetes and 1.2 times in those with type 2 diabetes. The predictive strength of the model depended on the number of variables included.

Conclusions: It is possible to construct a model for optimizing the examination interval during screening for diabetic retinopathy in low‐risk patients. The model can potentially be improved by identifying unknown or unmeasured confounders and by including knowledge of risk factors before and after the examination on the basis of which the prediction is made.
Annual transition of major depressive episode in university students using a structured self‐rating questionnaire
Authors: Uehara Toru , Takeuchi Kazuo , Kubota Fumio , Oshima Kihachi , Ishikawa Osamu
Published: April 2010

Introduction: Depression frequently affects college and university students worldwide. The authors’ purpose was to estimate the positive rate of major depressive episodes (MDE) using a structured self‐report according to annual changes among Japanese university students. Data of freshmen were compared with those of students of other grades.

Methods: During 9 years from 2001, 11,164 freshmen filled out the Diagnostic and Statistical Manual for Mental Disorders (DSM) scale for depression every April. During the 8 years from 2002, the same survey was administered to 31,454 students of other grades as a regular examination.

Results: The positive rates of MDE were 1.2–2.0% among freshmen; they were 0.8–1.3% among students in other grades. Regarding data after 2005–2007 for female freshmen, the decrease from 2004 to 2007 was significant (P<0.05); from 2002 to 2007 (P<0.05). In 2001, and during 2005–2007, positive rates tended to be higher in male than in female students. Comparisons of MDE of freshmen and students of the other grades showed significant differences in 2005, 2006 (P<0.05), and 2009 (P<0.01). Male freshmen showed higher rates than males of the other grades in 2005, 2006 (P<0.05), 2007, and 2009 (P<0.01).

Discussion: The MDE rates among university students were similar to those among the general population in Japan, and lower than those in Western countries. Among male freshmen, rates of MDE were particularly high. The reason for the recent decrease of MDE among female freshmen remains unclear. Sociocultural factors or selection bias should be considered.
Finite Element Analysis of Engine Bore Distortions During Boring Operation
Authors: Kakade N. N. , Chow J. G.
Published: April 2010

Bore geometry is the major factor affecting oil comsumption, piston ring wear, and frictional losses in an engine. As such, auto industries have been constantly striving to develop better machining technologies to produce engine bores with greater precision. Experimental studies have shown that the bore distortion as a result of machining is mainly caused by temperatures and stresses created during cutting. Consequently, optimization of machining conditions so as to minimize both bore temperature gradients as well as mechanical stresses while machining should lead to the production of better bore geometry. This research develops a model aimed at simulating bore distortions caused by temperature changes and stresses generated during machining using finite element technique. The commercial finite element package ANSYS has been used along with the CAD package I-DEAS to simulate the boring process on DEC-VAX computers. The simulation procedure developed can be used to obtain a better understanding of the boring process, in particular, to determine distortion trends for different cutting conditions.
Rezoning and Dynamic Substructuring Techniques in FEM Simulations of Welding Processes
Authors: Brown S. B. , Song H.
Published: April 2010

Distortion and residual stresses cause significant problems in the welding of large structures. Prediction of these phenomena would provide substantial assistance to the design and fabrication of welding. Unfortunately, the complexity of structural interactions during welding and the severe nonlinearities associated with the welding process limit the application of weld simulations. This presentation develops rezoning and dynamic substructuring techniques that make the finite element welding simulation of large structures more tractable. Both techniques exploit the fact that only a local zone around the welding electrode is nonlinear during welding. We therefore model the local nonlinear zone around the electrode or heat source with a dense finite element mesh. The rest of the larger structure is modeled using both a coarser mesh and substructures. The model is then redefined incrementally to represent the motion of the electrode through the larger structure. The redefinition is performed on the deformed geometry of the previous increment, achieving a step-wise coupled thermo-mechanical analysis. The techniques are applied to a two-dimensional plate welding example, achieving significant reductions in model size. Computer memory requirements and analysis times achieve close to order-of-magnitude reductions. Three-dimensional welding simulations should experience greater reductions in analysis time. Although developed for welding applications, the rezoning and dynamic substructuring techniques can also be used for other analyses involving a small nonlinear zone translating within a larger elastic body.
Tool-Work Thermocouple Temperature Measurements—Theory and Implementation Issues
Authors: Stephenson D. A.
Published: April 2010

Since cutting tools wear by temperature-activated mechanisms, it would be desirable to make tool temperature measurements during machinability tests. However, none of the laboratory methods for measuring temperatures reported in the literature is simple and reliable enough for routine testing. The method which is most promising is the tool-work thermocouple method, which yields a repeatable result which correlates well with tool wear for many materials. This method is not normally used in machinability testing because it is not clear what temperature the method actually measures and because, as conventionally described, it cannot be used for roughing cuts at high cutting speeds. The purpose of this paper is to extend both the theoretical understanding and range of application of the tool-work thermocouple method. The question of what temperature is measured by the method is answered by analyzing the electrical potential distribution in a cutting tool due to a distributed interfacial emf. It is shown that in general the tool-work thermocouple temperature differs from the average interfacial temperature, but that for tungsten carbide tools the difference is usually small. The isolation of the tool-work thermocouple circuit is also considered. Methods of measuring signals without introducing insulation between the chuck and workpiece and reducing the machining system stiffness are described. Finally, methods of minimizing measurement errors due to secondary junctions are discussed. Sample signals from machinability tests on steels are used to illustrate significant points.
Criteria for Outward Curling of Tubes
Authors: Kitazawa K.
Published: April 2010

The criteria for outward curling of circular metal tubes have been investigated experimentally and theoretically. The results are summarized as follows: (1) The critical bending radius, ρc exists. When the bending radius at die inlet ρ is larger than the ρc, the tube end fits well on the die surface. On the other hand, when ρ ≤ ρc, the tube end separates from the die surface and curling occurs. (2) It is found that there is a geometrical similarity law of the ρc. The ρc increases with increasing die angle. Furthermore, it is also clarified that the ρc is independent of the tube materials and lubrication.
Real-time Compensation for Time-variant Volumetric Errors on a Machining Center
Authors: Chen J. S. , Yuan J. X. , Ni J. , Wu S. M.
Published: April 2010

An error compensation system has been developed to enhance the time-variant volumetric accuracy of a 3-axis machining center by correcting the existing machine errors through sensing, metrology, and computer control techniques. A general methodology has been developed to synthesize both the geometric and thermal errors of machines into a time-variant volumetric error model. Instead of the well-known 21 geometric error components, 32 machine linkage errors are formulated as a 4D error field including the space domain and the time domain. Different types of models are proposed for different kinds of thermal error components. A compensation controller based on an IBM/PC has been linked with a CNC controller to compensate for machine errors in real time. This scheme has been implemented on a horizontal machining center and has been shown, using metrology instruments, to improve the machine accuracy by an order of magnitude. A cut workpiece inspected using a coordinate measuring machine (CMM) has also shown that dimension errors have been reduced from 92.4 μm to 18.9 μm in a dimension of 404 × 310 mm2 and the depth difference of milled surfaces has been reduced from 196 μm to 8 μm.
Multidisciplinary Optimization of a Radial Compressor for Microgas Turbine Applications
Authors: Verstraete T. , Alsalihi Z. , Van den Braembussche R. A.
Published: April 2010

A multidisciplinary optimization system and its application to the design of a small radial compressor impeller are presented. The method uses a genetic algorithm and artificial neural network to find a compromise between the conflicting demands of high efficiency and low centrifugal stresses in the blades. Concurrent analyses of the aero performance and stress predictions replace the traditional time consuming sequential design approach. The aerodynamic performance, predicted by a 3D Navier–Stokes solver, is maximized while limiting the mechanical stresses to a maximum value. The stresses are calculated by means of a finite element analysis, and controlled by modifying the blade camber, lean, and thickness at the hub. The results show that it is possible to obtain a significant reduction of the centrifugal stresses in the blades without penalizing the performance.
Shaping of Tip End-Plate to Control Leakage Vortex Swirl in Axial Flow Fans
Authors: Corsini Alessandro , Rispoli Franco , Sheard A. G.
Published: April 2010

This paper reports on quantitative tests of passive techniques for rotor-tip noise control in low-speed axial flow fans, based on blade-tip modifications involving the addition of antivortex appendages as end-plates. The end-plate thickness chordwise distribution is determined to control the chordwise evolution of the leakage vortex rotation number. The results confirm that the new end-plate configurations provide a mechanism by which leakage vortex bursting can be avoided. As such, the modified rotors represent an effective means of passive control of vortex breakdown.
Comparison of
Discharge Coefficient Measurements and Correlations for Orifices With Cross-Flow and
Rotation
Authors: Hüning Marcus
Published: April 2010

Gas turbines and jet engines consist of a network of connected cavities beside the main gas path called the secondary air system. These cavities, which are often surrounded by stationary and high angular speed rotating walls are exposed to varying pressure and temperature levels of air or oil contaminated air and are connected to each other by orifices or restrictors. It is vital to control the secondary flow to enable a reliable and efficient engine design, which meets component durability with a minimum of parasitic air consumption. It is essential to understand the flow physics as well as network interdependency in order to minimize the flow consumption and yet meeting engine operating requirements, as well as practical parts component design or manufacturing needs. In this connection, computer network codes containing model conceptions, which can accurately predict orifice flows, are essential. In an effort to provide usable further insight into flows across restrictors, such as orifices, this publication compares test results and orifice loss calculation models from the open literature with the aid of transformation laws and contour plots. The influence of different geometric features is incorporated into a model for the calculation of discharge coefficients. This publication is an extract of the underlying widespread and more detailed ASME paper (Huening, 2008, “Comparison of Discharge Coefficient Measurements and Correlations for Several Orifice Designs With Cross-Flow and Rotation Around Several Axes,” ASME Paper No. GT2008-50976). Minor errors, noticed during adapting, are corrected.
Effect of Roughness and Unsteadiness on the Performance of a New Low Pressure Turbine Blade at Low Reynolds Numbers
Authors: Montomoli Francesco , Hodson Howard , Haselbach Frank
Published: April 2010

This paper presents a study of the performance of a high-lift profile for low pressure turbines at Reynolds numbers lower than in previous investigations. By following the results of Coull et al. (2008, “Velocity Distributions for Low Pressure Turbines,” ASME Paper No. GT2008-50589) on the design of high-lift airfoils, the profile is forward loaded. The separate and combined effects of roughness and wake passing are compared. On a front loaded blade, the effect of incidence becomes more important and the consequences in terms of cascade losses, is evaluated. The experimental investigation was carried out in the high speed wind tunnel of Whittle Laboratory, University of Cambridge. This is a closed-circuit continuous wind tunnel where the Reynolds number and Mach number can be fixed independently. The unsteadiness caused by wake passing in front of the blades is reproduced using a wake generator with rotating bars. The results confirm that the beneficial effect of unsteadiness on losses is present even at the lowest Reynolds number examined (Re3=20,000). This beneficial effect is reduced at positive incidence. With a front loaded airfoil and positive incidence, the transition occurs on the suction side close to the leading edge and this results in higher losses. This has been found valid for the entire Reynolds range investigated (20,000≤Re3≤140,000). Roughening the surface also had a beneficial effect on the losses but this effect vanishes at the lower Reynolds numbers, i.e., (Re3≤30,000), where the surface becomes hydraulically smooth. The present study suggests that a blade with as-cast surface roughness has a lower loss than a polished one.
Numerical Simulation of the Flow Pulsations Origin in Cascades of the Rear Blade Rows in a Gas Turbine Axial Compressor Using Low Calorific Fuel
Authors: Cyrus Vaclav , Polansky Jiri
Published: April 2010

Fatigue failure of the last three stator rows vanes (S17, EGV1, and EGV2) in the 17 stage gas turbine axial compressor occurred in the power plant where low calorific fuel syngas, was used. Causes of this dangerous phenomenon were flow pulsations with the frequency of 380–400 Hz that were found by the experimental investigation of the duty gas turbine. Mechanism of the flow unsteadiness origin was studied with the help of flow simulations in the 2D stator cascade system. Three numerical experiments were carried out. The first experiment investigated the flow simulation in the stator cascade system with a steady undisturbed inlet flow with increased turbulence intensity. Obtained data did not meet the standards of the actual compressor operations. In the remaining two numerical experiments, a purposely designed rotor cascade was located in front of the stator cascades. Shedding of vortex structures from the cascade profile surfaces at positive incidence angles is responsible for the flow pulsation origin. The interaction of rotor wakes/stator S17 cascade plays an important role in the investigated phenomenon, as follows from CFD data. Aerodynamic loading of both cascades is equal in the second group of numerical experiments. Computed results were in good qualitative agreement with the experimental ones. As the flow in rotor cascade was not separated, owing to the different aerodynamic loading of rotor and stator S17 cascades, the vortices shedding in stator cascade S17 had a significantly higher frequency of f=2200–2300 Hz than in other investigated cases.
Considerations of a Double-Wall Cooling Design to Reduce Sand Blockage
Authors: Land Camron C. , Joe Chris , Thole Karen A.
Published: April 2010

Gas turbine engines use innovative cooling techniques to keep metal temperatures down while pushing the main gas temperature as high as possible. Cooling technologies such as film-cooling and impingement-cooling are generally used to reduce metal temperatures of the various components in the combustor and turbine sections. As cooling passages become more complicated, ingested particles can block these passages and greatly reduce the life of hot section components. This study investigates a double-walled cooling geometry with impingement- and film-cooling. A number of parameters were simulated to investigate the success of using impingement jets to reduce the size of particles in the cooling passages. Pressure ratios typically ranged between those used for combustor liner cooling and for blade outer air seal cooling whereby both these locations typically use double-walled liners. The results obtained in this study are applicable to more intricate geometries where the need to promote particle breakup exists. Results indicated that ingested sand had a large distribution of particle sizes where particles greater than 150 μm are primarily responsible for blocking the cooling passages. Results also showed that the blockage from these large particles was significantly influenced and can be significantly reduced by controlling the spacing between the film-cooling and impingement-cooling plates.
On Nonholonomic Parametrization
Authors: Vujanovic B.
Published: April 2010

This paper is concerned with the problem of obtaining the differential equation of the trajectory of dynamical system. Time is eliminated by means of some first integral linear with respect to the velocities. As an example, the stability of rotation of a heavy asymmetric rigid body with a fixed point under the action of the Newtonian central force field is considered.
The Impact Between a Rigid Sphere and a Thin Layer
Authors: Conway H. D. , Lee H. C. , Bayer R. G.
Published: April 2010

A simple model is presented for studying the impact between a rigid sphere and a thin layer of relatively soft material supported on a rigid substrate. By assuming that the major loss of energy during impact is due to the plastic deformation of the layer, an approximate analysis is made for computing the energy loss for layer materials which obey an elastic, perfectly plastic stress-strain law. An analytical expression for the coefficient of restitution is derived, and a parameter which controls the rebound characteristics is identified. Experimental results show generally good agreement with the analysis.
Shock Thickness in Viscoplastic Solids
Authors: Kelly J. M. , Gillis P. P.
Published: April 2010

In this paper a system of constitutive relations for plane-strain finite deformation in strain-rate sensitive elastic-plastic materials is developed. A method is presented for computing the main features of steady-state one-dimensional plastic-strain waves by elementary numerical techniques in materials of this type. This method is applicable to a wide variety of material constitutive relations and provides an alternative to computing complete wave profiles for investigators interested primarily in the effects of certain numerical parameters on the principal features of waves. The method is illustrated by use of particular constitutive relations but is applicable to a much wider class of relations. Maximum normal stress, pressure, and shear stress are computed, using this method, as a function of wave speed. For two different plastic strain-rate relations the maximum plastic strain rate and total strain are computed as a function of wave speed. Making use of these results, estimates are provided for the wave-front thickness in terms of wave speed and the parameters of the particular viscoplastic constitutive equations used. These results suggest ways in which plastic wave experiments can be used to motivate the construction of constitutive equations for finite deformation in strain-rate sensitive plastic solids.
On the Stability of a Differential Equation With Application to Parametrically Excited Systems
Authors: Rand R. H. , Simon H.
Published: April 2010

The stability of the equation z¨ + (Δ + ε cos t)−mz = 0, where m is a positive integer, is studied by using Floquet theory and perturbations. The results are confirmed by a digital computer program based on Floquet theory. Physical examples involving parametric excitation for m = 1, 3 are cited from the literature.
Stress Relaxation in Combined Torsion-Tension
Authors: Goldberg W. , Lianis G.
Published: April 2010

In this paper we briefly examine the form of the isothermal constitutive relation of an isotropic simple material under stress-relaxation conditions. We then compare the predictions of the Signorini form of the Bernstein, Kearsley, Zapas elastic fluid theory and the Lianis constitutive equation for single-step stress-relaxation histories and show that they are identical. Using these theories, we develop theoretical expressions for the torque and axial force in combined torsion-tension stress relaxation. Experiments were performed on samples of an SBR polymer, and the observed response is compared with theoretical predictions.
A General Solution for the Elastic Quarter Space
Authors: Hete´nyi M.
Published: April 2010

The algorithmic procedure used by the author previously in the solution for the elastic quarter plane is extended in this paper for the elastic quarter space. Values of the stress components were evaluated on the top and side surfaces of the quarter space for four values of Poisson’s ratio μ = 1/2, 1/3, 1/6, and 0.
On the Relation Between Stress and Strain-Concentration Factors in Notched Members in Plane Stress
Authors: Byre Gowda C. V. , Topper T. H.
Published: April 2010

The validity of the relationship between stress and strain-concentration factors proposed by Neuber, i.e., the geometric mean of the stress and strain-concentration factors is equal to the linear elastic-stress-concentration factor, is investigated for plane-stress problems. The physically nonlinear plane-stress problem of an infinite plate with a circular hole is solved by a perturbation method. Applicability of the solution and the restrictions on the relationship are discussed with reference to theoretical and experimental results.
New Results for the Buckling Loads of Axially Compressed Cylindrical Shells Subject to Relaxed Boundary Conditions
Authors: Simmonds J. G. , Danielson D. A.
Published: April 2010

A set of accurate buckling equations recently developed by the authors is used to compute the buckling loads of axially compressed circular cylindrical shells subject to “relaxed,” incremental boundary conditions. Over a large range of values of the length to radius ratio, L/R, the buckling loads are essentially 1/2 of the classical value, as has been found by many previous investigators using the simplified Donnell buckling equations. However, it is shown that as L/R → 0 or as L/R → ∞, the buckling loads approach zero, in contrast to the behavior predicted by the Donnell equations. The correct behavior as L/R → 0, first discovered by Koiter, may be interpreted as the buckling of a ring-beam constrained between two rigid, concentric, frictionless cylinders. The behavior as L/R → ∞ simply represents Euler column buckling.
On the Stability of Linear Discrete Dynamic Systems
Authors: Walker J. A.
Published: April 2010

A technique is presented for studying the stability of equilibria of linear discrete dynamic systems involving general types of forces: elastic, nonconservative, dissipative, and gyroscopic. The techniqe is a generalization of the energy method, based upon a restricted version of the general method of Liapunov, and often allows stability to be determined in terms of unspecified parameters. For systems of n degrees of freedom, stability theorems are given which require the existence of an n × n symmetric matrix G having certain properties. Several examples are given to illustrate the method of construction of this matrix and the type of information which it may be expected to yield. In general the method and its results are quite similar to the energy method, but apply even when the energy function does not exist.
Singular Solutions to the Shallow Shell Equations
Authors: Sanders J. Lyell
Published: April 2010

The paper contains a theoretical investigation of those multivalued singular solutions to the shallow shell equations which correspond physically to concentrated loads and dislocations. Use of the shell equations in complex form permits a unified treatment of the load and dislocation problems. The analysis is limited to the case of shells with a quadratic middle surface, and Fourier transforms of the solutions are obtained. Complete solutions in closed form in the case of a shallow sphere are given in the Appendix, including some results not previously published.
Cutouts in Shallow Shells
Authors: Sanders J. Lyell
Published: April 2010

Integral representations of general solutions to the shallow shell equations are obtained by means of the Betti-Rayleigh principle. With the aid of these integral representations the cutout problem of shallow shells is reduced to a system of four coupled integral equations. The cutout can have an arbitrary shape. Cutouts with reinforced edges and other boundary-value problems for shallow shells can be reduced to integral equations by the method developed in the paper.
Low Buckling Loads of Axially Compressed Conical Shells
Authors: Baruch M. , Harari O. , Singer J.
Published: April 2010

The stability of simply supported conical shells under axial compression is investigated for 4 different sets of in-plane boundary conditions with a linear Donnell-type theory. The first two stability equations are solved by the assumed displacement, while the third is solved by a Galerkin procedure. The boundary conditions are satisfied with 4 unknown coefficients in the expression for u and v. Both circumferential and axial restraints are found to be of primary importance. Buckling loads about half the “classical” ones are obtained for all but the stiffest simple supports SS4 (v = u = 0). Except for short shells, the effects do not depend on the length of the shell. The physical reason for the low buckling loads in the SS3 case is explained and the essential difference between cylinder and cone in this case is discussed. Buckling under combined axial compression and external or internal pressure is studied and interaction curves have been calculated for the 4 sets of in-plane boundary conditions.
A Linear Compressibility Assumption for the Multiple Integral Representation of Nonlinear Creep of Polyurethane
Authors: Nolte K. G. , Findley W. N.
Published: April 2010

The assumption that volume changes associated with creep of a nonlinear viscoelastic material are only linearly dependent on the stress history is incorporated into a third-order multiple integral representation. This assumption reduces the number of independent kernel functions in the representation from 12 to 7. The traces of these independent kernels may be determined from two tension, two torsion, and one combined tension and torsion creep tests. Experiments on polyurethane are well represented by this method. The time-dependence of the kernel functions is expressed by time raised to a power with the power differing for different-order kernel functions.
The Ultimate Asymptote and Mean Flow Structure in Toms’ Phenomenon
Authors: Virk P. S. , Mickley H. S. , Smith K. A.
Published: April 2010

The maximum drag reduction in turbulent pipe flow of dilute polymer solutions is ultimately limited by a unique asymptote described by the experimental correlation: f−1/2=19.0log10(NRef1/2)−32.4 The semilogarithmic mean velocity profile corresponding to and inferred from this ultimate asymptote has a mixing-length constant of 0.085 and shares a trisection (at y+ ∼ 12) with the Newtonian viscous sublayer and law of the wall. Experimental mean velocity profiles taken during drag reduction lie in the region bounded by the inferred ultimate profile and the Newtonian law of the wall. At low drag reductions the experimental profiles are well correlated by an “effective slip” model but this fails progressively with increasing drag reduction. Based on the foregoing a three-zone scheme is proposed to model the mean flow structure during drag reduction. In this the mean velocity profile segments are (a) a viscous sublayer, akin to Newtonian, (b) an interactive zone, characteristic of drag reduction, in which the ultimate profile is followed, and (c) a turbulent core in which the Newtonian mixing-length constant applies. The proposed model is consistent with experimental observations and reduces satisfactorily to the Taylor-Prandtl scheme and the ultimate profile, respectively, at the limits of zero and maximum drag reductions.
Effects of Lumped Masses on the Stability of Fluid Conveying Tubes
Authors: Hill J. L. , Swanson C. P.
Published: April 2010

The effects of adding lumped masses to fluid conveying tubes are studied. The addition of the masses is accounted for by a discontinuous mass distribution. Solutions of the partial differential equation of motion with the discontinuous coefficient are sought approximately using Galerkin’s method. Numerical results are presented for the destabilizing fluid-flow velocity for a cantilevered tube. The numerical results compare favorably with experimental results.
Passivation of InGaAs using in situ molecular beam epitaxy Al2O3/HfO2 and HfAlO/HfO2
Authors: Chang P. , Lee W. C. , Huang M. L. , Lee Y. J. , Hong M. , Kwo J.
Published: April 2010

In 0.2 Ga 0.8 As was effectively passivated using in situ molecular beam epitaxy deposited Al2O3/HfO2 and HfO2–Al2O3(HfAlO)/HfO2. HfO2 3 ML (monolayer) thick was epitaxially grown on InGaAs, as monitored by reflection high-energy electron diffraction. Al2O3 3 nm thick and HfAlO 4 nm thick were used to cap 3 ML epitaxial HfO2 due to their superior thermal stability up to 800 °C. Well-behaved capacitance-voltage characteristics with small capacitance dispersion between 10 and 500 kHz were obtained in both Al2O3/HfO2/InGaAs/GaAs and HfAlO/HfO2/InGaAs/GaAs, with the capacitance effective thickness values of the dielectrics being 1.46 and 1.18 nm, respectively. Particularly, HfAlO/HfO2/InGaAs/GaAs exhibited low leakage current density (2.9×10−4 A/cm2) at |VG-VFB|=1, good thermal stability up to 800 °C, and an equivalent oxide thickness of 1 nm.
Growth, characterization, and uniformity analysis of 200 mm wafer-scale SrTiO3/Si
Authors: Gu X. , Lubyshev D. , Batzel J. , Fastenau J. M. , Liu W. K. , Pelzel R. , Magana J. F. , Ma Q. , Rao V. R.
Published: April 2010

SrTiO 3 / Si wafers with high crystalline quality and smooth surface morphology are highly desirable for developing novel devices such as next generation dynamic random access memory and oxide field effect devices. Very high quality STO/Si epiwafers with diameter of up to 200 mm have been prepared on a production molecular beam epitaxy platform. Reflection high-energy electron diffraction was used to ensure the excellent stoichiometric control, which has been confirmed by a wide range of characterization techniques including x-ray diffraction, atomic force microscopy, cross-sectional transmission electron microscopy, and Rutherford backscattering spectroscopy. The uniformity of the large scale SrTiO3/Si wafers has been investigated using multipoint characterization techniques, which reveal excellent material properties and uniformities.