bluuebunny/crossref_metadata_2025 huggingface dataset:
Bayesian Logistic Injury Severity Score: A Method for Predicting Mortality Using International Classification of Disease‐9 Codes
Authors: Burd Randall S. , Ouyang Ming , Madigan David
Published: April 2008

Objectives: Owing to the large number of injury International Classification of Disease‐9 revision (ICD‐9) codes, it is not feasible to use standard regression methods to estimate the independent risk of death for each injury code. Bayesian logistic regression is a method that can select among a large numbers of predictors without loss of model performance. The purpose of this study was to develop a model for predicting in‐hospital trauma deaths based on this method and to compare its performance with the ICD‐9–based Injury Severity Score (ICISS).

Methods: The authors used Bayesian logistic regression to train and test models for predicting mortality based on injury ICD‐9 codes (2,210 codes) and injury codes with two‐way interactions (243,037 codes and interactions) using data from the National Trauma Data Bank (NTDB). They evaluated discrimination using area under the receiver operating curve (AUC) and calibration with the Hosmer‐Lemeshow (HL) h‐statistic. The authors compared performance of these models with one developed using ICISS.

Results: The discrimination of a model developed using individual ICD‐9 codes was similar to that of a model developed using individual codes and their interactions (AUC = 0.888 vs. 0.892). Inclusion of injury interactions, however, improved model calibration (HL h‐statistic = 2,737 vs. 1,347). A model based on ICISS had similar discrimination (AUC = .855) but showed worse calibration (HL h‐statistic = 45,237) than those based on regression.

Conclusions: A model that incorporates injury interactions had better predictive performance than one based only on individual injuries. A regression approach to predicting injury mortality based on injury ICD‐9 codes yields models with better predictive performance than ICISS.
Leukemia cutis presenting as localized cutaneous hyperpigmentation
Authors: Angulo Jorge , Haro Rosario , González‐Guerra Elena , Fariña Ma Carmen , Martín Lucía , Requena Luis
Published: April 2008

The usual clinical presentations of leukemia cutis include solitary infiltrated erythematous or violaceous plaques or nodules and multiple localized or generalized papules. On the other hand, cutaneous hyperpigmentation is a frequent finding in patients with malignancies, most of the cases because of chemotherapy or other drugs that the patient is taking. We present a case of cutaneous hyperpigmentation as the presenting sign of leukemia cutis. A 61‐year‐old male presented with cutaneous hyperpigmentation, which had appeared during the last chemotherapy cycle for treatment for biphenotypic leukemia. Cutaneous lesions consisted of bluish to brownish irregular well‐defined discoloration of the skin involving the upper part of the trunk and the temporal regions of the forehead. The patient was asymptomatic and the skin was not infiltrated at all. However, histopathologic study showed nodular infiltrates involving the full‐thickness of the dermis and destroying pre‐existing adnexa. This infiltrate was composed of atypical basophilic cells with large hyperchromatic nuclei and scant cytoplasm. Immunohistochemical studies showed intense immunoexpression for CD43, CD68, CD45RO and myeloperoxidase within these cells. A diagnosis of biphenotypic leukemia cutis was established. In our review of the literature we have not found any report of cutaneous hyperpigmentation as the presenting manifestation of leukemia cutis.
ORIGINAL ARTICLE: Treatment with Tumor Necrosis Factor Inhibitors and Intravenous Immunoglobulin Improves Live Birth Rates in Women with Recurrent Spontaneous Abortion
Authors: Winger Edward E. , Reed Jane L.
Published: April 2008

Problem  The purpose of this study was to investigate whether treatment with tumor necrosis factor (TNF) inhibitors combined with intravenous immunoglobulin (IVIG) increases live birth rates among women with recurrent spontaneous abortion (RSA) concurrently treated with anticoagulants (AC).

Method of study  Seventy‐five pregnancies in patients with a history of RSA were retrospectively evaluated. The population was divided into three groups: group I: 21 patients treated with AC (anticoagulants), group II: 37 patients treated with AC and IVIG, and group III: 17 patients treated with AC, IVIG and the TNF inhibitor Etanercept (Enbrel®) or Adalimumab (Humira®). In groups II and III, IVIG was administered at least once during the cycle of conception and/or at least once after a positive pregnancy test. In group III, either Adalimumab or Etanercept was administered by subcutaneous injection according to standard protocols. Statistical analysis of pregnancy outcome was performed using Fisher’s exact test.

Results  Patient populations in the three treatment groups were similar in terms of age, past miscarriages, inherited thrombophilia and autoimmunity. The live birth rate was 19% (4/21) in group I, 54% (20/37) in group II, and 71% (12/17) in group III. There was significant improvement in pregnancy outcome in group II versus group I (P = 0.0127) and in group III versus group I (P = 0.0026). The live birth rate in group III compared to group II was not significantly different (P = 0.3723). Side effects of AC, IVIG and TNF inhibitor treatment were minimal in these patients, and no birth defects were identified in their offspring.

Conclusion  In women with RSA, addition of either IVIG or a TNF inhibitor + IVIG to the AC regimen appears to improve live birth rates compared to the treatment with AC alone. The positive effect of IVIG and TNF inhibitor therapy on pregnancy outcome merits further study in prospective clinical trials.
Characterization of Aquifex aeolicus 4‐diphosphocytidyl‐2C‐methyl‐d‐erythritol kinase – ligand recognition in a template for antimicrobial drug discovery
Authors: Sgraja Tanja , Alphey Magnus S. , Ghilagaber Stephanos , Marquez Rudi , Robertson Murray N. , Hemmings Jennifer L. , Lauw Susan , Rohdich Felix , Bacher Adelbert , Eisenreich Wolfgang , Illarionova Victoria , Hunter William N.
Published: April 2008

4‐Diphosphocytidyl‐2C‐methyl‐d‐erythritol kinase (IspE) catalyses the ATP‐dependent conversion of 4‐diphosphocytidyl‐2C‐methyl‐d‐erythritol (CDPME) to 4‐diphosphocytidyl‐2C‐methyl‐d‐erythritol 2‐phosphate with the release of ADP. This reaction occurs in the non‐mevalonate pathway of isoprenoid precursor biosynthesis and because it is essential in important microbial pathogens and absent from mammals it represents a potential target for anti‐infective drugs. We set out to characterize the biochemical properties, determinants of molecular recognition and reactivity of IspE and report the cloning and purification of recombinant Aquifex aeolicus IspE (AaIspE), kinetic data, metal ion, temperature and pH dependence, crystallization and structure determination of the enzyme in complex with CDP, CDPME and ADP. In addition, 4‐fluoro‐3,5‐dihydroxy‐4‐methylpent‐1‐enylphosphonic acid (compound 1) was designed to mimic a fragment of the substrate, a synthetic route to 1 was elucidated and the complex structure determined. Surprisingly, this ligand occupies the binding site for the ATP α‐phosphate not the binding site for the methyl‐d‐erythritol moiety of CDPME. Gel filtration and analytical ultracentrifugation indicate that AaIspE is a monomer in solution. The enzyme displays the characteristic α/β galacto‐homoserine‐mevalonate‐phosphomevalonate kinase fold, with the catalytic centre positioned in a deep cleft between the ATP‐ and CDPME‐binding domains. Comparisons indicate a high degree of sequence conservation on the IspE active site across bacterial species, similarities in structure, specificity of substrate recognition and mechanism. The biochemical characterization, attainment of well‐ordered and reproducible crystals and the models resulting from the analyses provide reagents and templates to support the structure‐based design of broad‐spectrum antimicrobial agents.
Nuclear localization of human spermine oxidase isoforms – possible implications in drug response and disease etiology
Authors: Murray‐Stewart Tracy , Wang Yanlin , Goodwin Andrew , Hacker Amy , Meeker Alan , Casero Jr Robert A.
Published: April 2008

The recent discovery of the direct oxidation of spermine via spermine oxidase (SMO) as a mechanism through which specific antitumor polyamine analogues exert their cytotoxic effects has fueled interest in the study of the polyamine catabolic pathway. A major byproduct of spermine oxidation is H2O2, a source of toxic reactive oxygen species. Recent targeted small interfering RNA studies have confirmed that SMO‐produced reactive oxygen species are directly responsible for oxidative stress capable of inducing apoptosis and potentially mutagenic DNA damage. In the present study, we describe a second catalytically active splice variant protein of the human spermine oxidase gene, designated SMO5, which exhibits substrate specificities and affinities comparable to those of the originally identified human spermine oxidase‐1, SMO/PAOh1, and, as such, is an additional source of H2O2. Importantly, overexpression of either of these SMO isoforms in NCI‐H157 human non‐small cell lung carcinoma cells resulted in significant localization of SMO protein in the nucleus, as determined by confocal microscopy. Furthermore, cell lines overexpressing either SMO/PAOh1 or SMO5 demonstrated increased spermine oxidation in the nucleus, with accompanying alterations in individual nuclear polyamine concentrations. This increased oxidation of spermine in the nucleus therefore increases the production of highly reactive H2O2 in close proximity to DNA, as well as decreases nuclear spermine levels, thus altering the protective roles of spermine in free radical scavenging and DNA shielding, and resulting in an overall increased potential for oxidative DNA damage in these cells. The results of these studies therefore have considerable significance both with respect to targeting polyamine oxidation as an antineoplastic strategy, and in regard to the potential role of spermine oxidase in inflammation‐induced carcinogenesis.
Brain-Regulated Metabolic Suppression during Hibernation: A Neuroprotective Mechanism for Perinatal Hypoxia–Ischemia
Authors: Nathaniel Thomas I.
Published: April 2008

Hypoxic–ischemic brain injury in the perinatal period is a major cause of chronic disability and acute mortality in newborns. Despite numerous therapeutic strategies that reduce hypoxia–ischemia-induced damage in different experimental animal models, most of them have failed to translate to clinical therapies. This challenge calls for an urgent need to explore novel approaches to develop effective therapies for the clinical management of perinatal hypoxia–ischemia brain injury. This review focuses on studies that investigate neuroprotective related events during mammalian hibernation, characterized by dramatic reductions in several parameters including body temperature, oxygen consumption and heart rate, such that it is difficult to tell if the hibernating animal is dead or alive. The first part of this article reviews the mechanisms of metabolic suppression related events during hibernation. In the second part, hypoxic–ischemic events in the perinatal brain are discussed, and in turn, contrasted with brains experiencing metabolic suppression during mammalian hibernation. In the last part of this article, the diverse neuroprotective adaptations of hibernators and the mechanisms that might be involved in mammalian hibernation, and how they could in turn, contribute to neurprotection during perinatal hypoxia–ischemia related injuries are discussed. This article appraises the novel idea that knowledge of the central mechanisms involved in the regulatory metabolic suppression, during which; hibernators switch themselves off without dissolving their brains could represent brain neuroprotective strategy for the clinical management of perinatal hypoxia–ischemia brain injuries in newborns.
A homozygous mutation in a Chinese man with Crigler–Najjar syndrome type II and a family genetic analysis
Authors: WU Jian Xin , CHENG Guang Yu , HUANG Jian
Published: April 2008

OBJECTIVE:  To investigate the family genetic background of a 22‐year‐old man with Crigler–Najjar syndrome type II (CN‐II).

METHODS:  After the proband (patient) with CN‐II was diagnosed by liver function tests, a low calorie intake test and an oral phenobarbital enzyme‐induction trial, blood samples were collected from 11 family members for identifying DNA gene groups. Exons 1–5 of the UGT1A1 gene were amplified by polymerase chain reaction (PCR) and mutations of the UGT1A1 gene were screened by a direct DNA sequencing.

RESULTS:  The serum unconjugated bilirubin increased in the proband from 156.4 µmol/L to 243.5 µmol/L after he started a low calorie intake, and it decreased to 51.8 µmol/L within a month of taking oral phenobarbital daily. Both functional tests and ultrasonographic images of the liver were normal except for the unconjugated hyperbilirubinemia. A missense mutation of Tyr486Asp at exon 5 in the UGT1A1 gene and a homozygous mutation were confirmed in the proband. Heterozygous mutations were found in his parents, his younger sister and three great‐uncles, while no mutation of the UGT1A1 gene was detected in the remaining four family members.

CONCLUSION:  A missense mutation of Tyr486Asp is considered to be the cause of the CN‐II in this patient. It is a recessive trait that is autosomally inherited in this family. No influence of the mutation was found on the response elements for phenobarbital in the promoter region.
Commercializing air traffic control: Have the reforms worked?
Authors: McDougall Glen , Roberts Alasdair
Published: April 2008

Abstract: Air navigation service providers (ANSPs) play a critical role in the operation of a modern economy. Many countries have restructured their ANSPs by granting managerial and financial autonomy and creating new mechanisms for regulation and accountability to major consumers of air navigation services. These reforms have exemplified principles often associated with the New Public Management. The United States is the major exception to this international trend. Commercialization has allowed significant improvements in service quality without substantial increases in cost of service or erosion of safety standards. Other public interest considerations have also been protected. These performance benefits can be attributed to key decisions on the governance of new air navigation service organizations.

Sommaire: Les fournisseurs de services de navigation aérienne jouent un rôle crucial dans le fonctionnement d'une économie moderne. De nombreux pays ont restructuré leurs fournisseurs de services en leur accordant une autonomie financière et de gestion, et en créant de nouveaux mécanismes de réglementation et d'imputabilité envers les principaux consommateurs de services de navigation aérienne. Ces réformes ont illustré les principes souvent associés à la Nouvelle gestion publique. Les États‐Unis sont la principale exception à cette tendance internationale. La commercialisation a permis d'apporter d'importantes améliorations à la qualité des services sans entraîner pour autant d'augmentations substantielles des coûts de services, ou une érosion des normes de sécurité. D'autres considérations d'intérêt public ont également été protégées. Ces avantages en termes de performance peuvent être attribués à des décisions clés en matière de gouvernance des nouveaux organismes de services de navigation aérienne.
Horizontalité et gouvernance décentralisée: les conditions de collaboration dans le contexte de l'action communautaire
Authors: Burlone Nathalie , Andrew Caroline , Chiasson Guy , Harvey Jean
Published: April 2008

Sommaire: Cet article s'interroge sur les formes de gouvernance qui caractérisent le secteur communautaire en s'appuyant sur l'étude de deux cas de partenariats locaux initiés par l'organisme Québec en forme (QEF) dans les régions de l'Outaouais et de la Mauricie. La participation croissante des organismes communautaires à la prestation des services publics met en relief l'importance de la collaboration et du partenariat interorganisationnels dans le cadre d'une gouvernance plus horizontale. L'article présente certaines difficultés posées par la construction d'une telle gouvernance dans le secteur communautaire. Le poids des structures de pouvoir traditionnelles, de même que les innovations proposées dans la littérature sur la gouvernance et l'horizontalité (élargissement des partenariats, développement de nouveaux objectifs partagés, etc.), ont beaucoup de difficultéà prendre assise dans la pratique communautaire.

Abstract: This article examines the forms of governance that characterize the community sector, referring to two case studies of local partnerships initiated by the group “Québec en forme” (QEF) in the Outaouais and Mauricie regions. The increasing participation of community organizations in the delivery of public services highlights the importance of cross‐jurisdictional cooperation and partnerships within the framework of a more horizontal governance. The article presents some of the challenges surrounding governance construction in the community sector. The weight of traditional power structures, as well as the innovations proposed in the literature on governance and the implementation of a horizontal approach (securing broader partnerships, developing new shared objectives, etc.), are not easily adopted in community practice.
Effect of Surface Roughness on Single Cryogen Droplet Spreading
Authors: Liu Jie , Franco Walfre , Aguilar Guillermo
Published: April 2008

Cryogen spray cooling is an auxiliary procedure to dermatologic laser surgery, which consists of precooling the superficial skin layer (epidermis) during laser irradiation of subsurface targets to avoid nonspecific epidermal thermal damage. While previous studies have investigated the interaction of cryogen sprays with microscopically smooth human skin models, it is important to recognize that real human skin surface is far from smooth. With the objective to provide physical insight into the interaction between cryogen sprays and human skin, we study the effect of surface roughness on the impact dynamics of single cryogen droplets falling on skin models of various roughnesses (0.5–70μm). We first develop a theoretical model to predict the maximum spread diameter (Dm) following droplet impingement based on a similarity approximation to the solution of a viscous boundary layer that incorporates friction as the major source of viscous dissipation on a rough surface. Then, we measure the droplet diameter, impact velocity, and Dm of cryogen droplets falling by gravity onto skin models. Experimental data prove that the proposed model predicts Dm with good accuracy, suggesting that the effects of surface roughness and friction on Dm are properly taken into account for the range of surface roughness studied herein.
Control of Vortex Shedding of Circular Cylinder in Shallow Water Flow Using an Attached Splitter Plate
Authors: Akilli Huseyin , Karakus Cuma , Akar Atakan , Sahin Besir , Tumen N. Filiz
Published: April 2008

In the present work, passive control of vortex shedding behind a circular cylinder by splitter plates of various lengths attached on the cylinder base is experimentally investigated in shallow water flow. Detailed measurements of instantaneous and time-averaged flow data of wake flow region at a Reynolds number of Re=6300 were obtained by particle image velocimetry technique. The length of the splitter plate was varied from L∕D=0.2 to L∕D=2.4 in order to see the effect of the splitter plate length on the flow characteristics. Instantaneous and time-averaged flow data clearly indicate that the length of the splitter plate has a substantial effect on the flow characteristics. The flow characteristics in the wake region of the circular cylinder sharply change up to the splitter plate length of L∕D=1.0. Above this plate length, small changes occur in the flow characteristics.
Mixing Flow Characteristics in a Vessel Agitated by the Screw Impeller With a Draught Tube
Authors: Tsui Yeng-Yung , Hu Yu-Chang
Published: April 2008

The circulating flow in a vessel induced by rotating impellers has drawn a lot of interests in industries for mixing different fluids. It used to rely on experiments to correlate the performance with system parameters because of the theoretical difficulty to analyze such a complex flow. The recent development of computational methods makes it possible to obtain the entire flow field via solving the Navier–Stokes equations. In this study, a computational procedure, based on multiple frames of reference and unstructured grid methodology, was used to investigate the flow in a vessel stirred by a screw impeller rotating in a draught tube. The performance of the mixer was characterized by circulation number, power number, and nondimensionalized mixing energy. The effects on these dimensionless parameters were examined by varying the settings of tank diameter, shaft diameter, screw pitch, and the clearance between the impeller and the draught tube. Also investigated was the flow system without the draught tube. The flow mechanisms to cause these effects were delineated in detail.
Friction Factor Measurements in an Equally Spaced Triangular Array of Circular Tubes
Authors: Vassallo Peter , Symolon Paul
Published: April 2008

Friction factor data for adiabatic cross flow of water in a staggered tube array were obtained over a Reynolds number range (based on hydraulic diameter and gap velocity) of about 10,000–250,000. The tubes were 12.7mm(0.5in.) outer diameter in a uniformly spaced triangular arrangement with a pitch-to-diameter ratio of 1.5. The friction factor was compared to several literature correlations and was found to be best matched by the Idelchik correlation. Other correlations were found to significantly vary from the test data. Based on the test data, a new correlation is proposed for this tube bundle geometry, which covers the entire Reynolds number range tested.
Three-Dimensional Modeling of Hydraulic Fractures in Layered Media: Part I—Finite Element Formulations
Authors: Advani S. H. , Lee T. S. , Lee J. K.
Published: April 2008

A comprehensive model represented by a set of equations governing the mechanics of planar hydraulic fracture propagation in a multi-layered reservoir is presented. A general-purpose integral formulation for the formation elasticity is developed along with a numerical scheme for mode I fracture response evaluation of an arbitrarily shaped planar pressurized crack in a layered medium. Non-Newtonian fluid flow in the hydraulically induced fracture is governed by a two-dimensional nonlinear partial differential equation. Finite element formulations for the governing equations as well as calibrative examples illustrating the computational features of the model are presented. Numerical schemes for determining the moving fracture front and coupling of the fluid flow and structural/fracture responses are also developed.
Ramp Wave Analysis of the Solid/Vapor Heat Pump
Authors: Shelton S. V. , Wepfer W. J. , Miles D. J.
Published: April 2008

A theramlly driven heat pump using a solid/vapor adsorption/desorption compression process in a vapor compression cycle is thermodynamically analyzed. The cycle utilizes a simple heat transfer fluid circulating loop for heating and cooling of two solid adsorbent beds. This heat transfer fluid loop also serves to transmit heat recovered from the adsorbing bed being cooled to the desorbing bed being heated. This heat recovery process greatly improves the efficiency of the single-stage solid/vapor adsorption process without the complication of a two-stage cycle. During the heating and cooling processes a thermal wave profile travels through the beds. Previous studies of this cycle used a square wave model to simulate the thermal wave front. This paper utilizes a more physically realistic ramp wave model to overcome the shortcomings of the square wave model. The ramp wave model is integrated into a thermodynamic cycle which provides detailed information on the performance of the beds as well as the COP and the heating and cooling outputs of the heat pump system. Significant cycle design and operating parameters are varied to determine their effect on cycle performance.
Computer Simulation of Solid Electrolyte Fuel Cells
Authors: Dunbar W. R. , Gaggioli R. A.
Published: April 2008

This paper presents the results of mathematical modeling of the performance of solid electrolyte fuel cells. The system of fundamental physical equations has been solved using a computer program which was developed expressly for this purpose, in order to simulate the performance of arrays of fuel cells for which experimental data exists in the literature. The comparison of experimental data and simulated performance is excellent. The results of the simulation show the influence of each irreversible process within the fuel cell, quantitatively; that is, the relative importance of each source of inefficiency—and the consequent voltage loss—is determined. Because certain rate constants (for diffusion and for chemical kinetics) employed in the model were obtained by regression, it cannot be claimed that the ability to fit the experimental data is a definitive test of the model; more work is needed for that purpose. Nevertheless, it is shown that (a) modeling of fuel cells on the basis of basic physical principles is a worthwhile venture, (b) the model presented here simulates performance well and warrants further development, and (c) it not only simulates the overall performance of the cells, but also provides the important breakdown of the effects of each irreversibility in the cells. Furthermore, specific recommendations are made in this paper for improving the model.
Breakdown of the Exergy Balance in a Glass Furnace
Authors: De Lucia M. , Manfrida G.
Published: April 2008

An exergy balance for an industrial glass furnace was constructed on the basis of measured thermodynamic variables. The experimental data were collected for different operating modes, especially in relation to oxygen enrichment. Losses were classified as belonging to one of three categories: 1) chemical reaction, 2) dissipation of heat (by radiation or sensible heat) to the environment, 3) heat transfer. Using this method, optimum conditions, with reference to oxygen enrichment of the combustion air, can be determined and the processes where the bulk of input exergy is destroyed can be identified. These results allow the designer to select modifications to furnace design and/or changes in operating modes that will be effective in enhancing plant efficiency. The last step is a thermoeconomic cost evaluation of the tested plant.
Wall Contact Forces on Helically Buckled Tubulars in Inclined Wells
Authors: Chen Y. C. , Cheatham J. B.
Published: April 2008

Wall forces on helically buckled pipe can cause large frictional forces that may prevent movement of the pipe in steeply inclined holes. A method of analyzing the dependency of the wall contact force on axial force and hole inclination is presented. The concept of an apparent wall force is introduced to explain phenomena associated with helix pitch variations during axial force unloading in inclined wells. Results of this analysis can have applications in friction modeling of buckled pipe in inclined holes.
Three-Dimensional Map Generation From Side-Scan Sonar Images
Authors: Cuschieri J. M. , Hebert M.
Published: April 2008

The generation of three-dimensional (3-D) images and map building are essential components in the development of an autonomous underwater system. Although the direct generation of 3-D images is more efficient than the recovery of 3-D data from 2-D information, at present for underwater applications where sonar is the main form of remote sensing, the generation of 3-D images can only be achieved by either complex sonar systems or with systems which have a rather low resolution. In this paper an overview is presented on the type of sonar systems that are available for underwater remote sensing, and then a technique is presented which demonstrates how through simple geometric reasoning procedures, 3-D information can be recovered from side scan-type (2-D) data. Also presented is the procedure to perform map building on the estimated 3-D data.
Upper Ball Joint Force Variations due to Riser Tensioner and Vessel Motions—Part II: Analysis and Computer Simulation
Authors: Kozik T. J. , Lowell J. E. , Ertas A.
Published: April 2008

An analysis of the variation of forces acting on the upper ball joint of a riser string due to the drill ship motion and riser tensioner dynamic has been conducted. The analysis includes the effect of breakaway torque on the tensioner sheaves while assuming vessel and upper ball joint motion to be independent. General equation for the tensioner cable forces and for the forces exerted on the riser upper ball joint by the ship joint-tensioner system derived in Part I are solved. The variation in the tensioner cable forces is compared to data generated in field operation.
General Equations for Pressure Drop for Laminar Flow in Ducts of Arbitrary Cross Sections
Authors: Yilmaz T.
Published: April 2008

This paper presents general equations for pressure drop calculations for developed and developing laminar flow in ducts of arbitrary cross sections. The results obtained from these equations compare well with the theoretically calculated values available in the literature for circular, rectangular, triangular, elliptical, polygonal, casped, corner and side ducts. The maximum deviations by these comparisons are 7.3 and −4.0 percent, respectively. Besides these, the equations yield satisfactory results for eccentric and concentric annular ducts.
High-Pressure Ignition of Oil Sands Samples in Oxygen Atmospheres Containing Various Concentrations of Diluents
Authors: Mehta S. A. , Karim G. A.
Published: April 2008

In-situ recovery of oil from oil sands deposits by combustion requires the injection of vast quantities of oxygen into the bed of deposits. Accordingly, there is a need to establish the ignition characteristics of high-grade Athabasca oil sands in environments containing pure oxygen at high-pressure and including the role of the presence of various diluents with the oxygen. A high-pressure constant volume bomb with a water calorimeter was employed as the test apparatus over the pressure range of 0.1 MPa to 4.0 MPa at ambient temperature. The role of the presence of the diluents, helium, nitrogen and carbon dioxide, with the oxygen, was also considered. Controlled ignition was achieved by employing electrically fusable nickel-chromium wire looped around the sample. Moreover, the presence of an ignition promotor such as benzoic acid was also considered. The paper presents the results of an experimental program that examined the effects of changes in the pressure, amounts of diluents and ignition energy on the ignition limits and subsequent combustion processes at ambient initial temperature. Moreover, the morphological changes to the samples at various stages of the process were also examined and discussed.
High-Temperature Steam Supply: Configuration Design for Temperature Control Stability
Authors: Mumm J. P. , Orozco J.
Published: April 2008

The main objective of this investigation is to report on the development and testing of a numerical code to simulate the operating characteristics of a steam-powered propulsion system. The test specifications permitted a temperature variation of 135 K (75°F) from the nominal temperature 1144 K (1600°F). Due to the extreme temperature and pressure involved, any overshoot would severly shorten the life of the facility. The predicted performance of the system was then evaluated for temperature stability. The code was also used to determine the modifications required to stabilize temperature variations. Testing was performed to better understand the dynamics of the process operation. The experimental data verified the predictions of the numerical code.
Comparison of Mass and Heat Transfer Coefficients of Liquid-Desiccant Mixtures in a Packed Column
Authors: Ertas A. , Anderson E. E. , Kavasogullari S.
Published: April 2008

In order to analyze the performance of packed columns for dehumidification processes, calculation of the mass and heat transfer coefficients of the packing material used in the column is necessary. This paper is concerned with the interface transfer of heat and mass when air is brought into contact with the liquid desiccant mixtures. A theoretical study of heat and mass transfer analysis in an air-desiccant dehumidification contact system (packed column) employing liquid-desiccants, namely calcium chloride (CaCl2), lithium chloride (LiCl), and a new liquid-desiccant mixture (Cost-Effective Liquid Desiccant, CELD) consisting of 50 percent lithium chloride and 50 percent calcium chloride is studied. Mass and heat transfer coefficients for the gas and liquid phase, by use of 0.5-in., 1-in., 1.5-in., and 2-in. ceramic Rasching rings, are calculated. The findings for the three liquid desiccants are compared and discussed.
Moment Closure Model for Nitrogen Oxide Formation in Pulverized Coal Combustion Furnaces
Authors: Jang D. S. , Acharya S.
Published: April 2008

A moment closure model has been developed to model fuel-bound NO formation in a turbulent pulverized coal flame in a furnace. The effect of turbulence on combustion is accounted for by solving transport equations of fluctuating species correlations arising due to turbulent fluctuations. Correlation between fluctuating species concentration and fluctuating temperature is neglected. The predicted results show reasonable overall agreement with experimental data.
The Drag and Added-Mass Coefficients of Various Buffers Vibrating Axially in Water
Authors: Aso K. , Kan K. , Doki H. , Mori M.
Published: April 2008

In order to analyze the longitudinal vibration of a pipe-string for mining mineral resources at deep-sea bottoms, the fluid forces acting on the buffer and pump-module attached to the pipe-string must be evaluated in advance. In this study, first, a new method was developed for determining the drag and added-mass coefficients of a buffer vibrating axially, and then both coefficients for various shapes of buffers were determined. The results obtained on the spherical buffer-models proved to be in fairly good agreement with those by Sarpkaya and showed the validity of the new method. Furthermore, the results of other buffer-models indicated that there was a good correlation between those coefficients and Keulegan-Carpenter number, KC, and that as KC increases, the drag coefficient decreases exponentially and the added-mass coefficient increases or decreases linearly according to the shapes of the buffer models.
A Theoretical Analysis of a Self-Propelled Backward-Bent Duct Wave Energy Conversion System
Authors: McCormick M. E.
Published: April 2008

An analysis of a self-propelled Backward-Bent Duct Barge (BBDB) wave energy conversion system operating at an averaged forward speed is presented. The energy required to propel the system is a parasitic energy of the wave energy conversion subsystem. The analysis includes a feedback between the internal water motions and the floating body dynamics. The performance of the BBDB operating in a design (head) sea is shown to be far superior to both a BBDB in a following sea and a fixed BBDB in a following sea. For this comparison, a 35.6-m long system having a 9.91-m beam and displacing 500 metric tons is studied. The system is also shown to have a positive drift in head seas.
Development of Micromechanics Finite Element for Analysis of Composites With Local Damage
Authors: Kwon Y. W. , Byun K. Y.
Published: April 2008

An analysis model is presented to analyze continuous fiber-reinforced composite structures with some local damage such as matrix cracks. Two separate material properties of fiber and matrix are used in the analysis model instead of a smeared-out global anisotropic material property. Stresses acting on fibers and stresses acting on matrix are computed directly. If there are local matrix cracks in the direction perpendicular to the fiber orientation in a composite structure, the broken matrix is modeled not to sustain any tensile stress in the fiber direction. A finite element formulation is derived for the analysis model. Some numerical problems are presented to test the proposed analysis model.
A Comparison of the Dynamic Transient Anti-Plane Shear Crack Energy Release Rate for Standard Linear Solid and Power-Law-Type Viscoelastic Materials
Authors: Herrmann J. M. , Walton J. R.
Published: April 2008

The problem of a semi-infinite mode III crack that suddenly begins to propagate at a constant speed is considered for a general linear viscoelastic body. It is shown that the results of an earlier paper for the Laplace transforms of the stress and displacement with the Laplace transform variable s being real and positive are valid, with minor modification, for complex values of s such that Re(s)>0. Therefore, these Laplace transforms can be inverted by means of a Bromwich path integral. Under the assumption that a Barenblatt-type failure zone exists at the crack tip, the energy release rate (ERR) and the work done in the failure zone (WFZ) are calculated through numerical inversion of Laplace transforms. The ERR and WFZ for the standard linear solid and power law material models are contrasted and also compared with the elastic and quasi-static results. The graphs and table illustrate considerable differences in the ERR and WFZ for these different models. These differences may be important to predictions of stable versus unstable crack speeds based upon a critical ERR fracture criterion.
Local Stress Distribution in the Vicinity of Loading Points in Flexural Test of Orthotropic Beams
Authors: Yoshida H. , Ogasa T. , Uemura M.
Published: April 2008

The two-dimensional stress distributions in orthotopic composite beam under 4-point flexure are analyzed by replacing the concentrated load by distributing pressure in the vicinity of loading nose and by expanding the stress function for compatability equation in terms of Fourier series. The validity of analytical results is verified experimentally by using the photoelastic film-coating technique on unidirectional reinforced plastics. It is shown that the local stress distributions around the loading points are complicated and are very different from those predicted by elementary beam theory; and hence, the reliability of flexural strength and interlaminar shear strength defined by elementary beam theory are in question. It is suggested that the 4-point flexure is reasonable and recommendable as a standard testing method compared with the 3-point flexural one.
A Numerical Comparison of Current Mathematical Models of Twisted Wire Cables Under Axisymmetric Loads
Authors: Jolicoeur C. , Cardou A.
Published: April 2008

Several mathematical models are currently available to predict the mechanical behavior of twisted wire cables and ACSR electrical conductors subjected to axisymmetric loads. The equations for each model are presented in a standardized form in the linear case and the differences illustrated are shown. Numerical results obtained with each model are presented in tabular form and a comparison made with experimental results reported in the literature.
Buckling of Laminated Cylindrical Panels Under Uniaxial Compression
Authors: Chandrashekhara K.
Published: April 2008

Buckling characteristics of anisotropic laminated cylindrical panels are presented using an isoparametric nine-noded rectangular element. Kinematic relations, extended to include the first-order shear deformation theory, are utilized in the formulation. Numerical results are presented for laminated cylindrical panels under uniaxial compression loading to illustrate the influence of panel sizes, orientation of layers, material properties, and boundary conditions on the buckling loads. Results for plates are also presented as special cases and are compared with the available solutions.
Optimal Design of a Pilot OTEC Power Plant in Taiwan
Authors: Tseng C. H. , Kao K. Y. , Yang J. C.
Published: April 2008

In this paper, an optimal design concept has been utilized to find the best designs for a complex and large-scale ocean thermal energy conversion (OTEC) plant. The OTEC power plant under this study is divided into three major subsystems consisting of power subsystem, seawater pipe subsystem, and containment subsystem. The design optimization model for the entire OTEC plant is integrated from these subsystems under the considerations of their own various design criteria and constraints. The mathematical formulations of this optimization model for the entire OTEC plant are described. The design variables, objective function, and constraints for a pilot plant under the constraints of the feasible technologies at this stage in Taiwan have been carefully examined and selected. The numerical optimization method called Sequential Quadratic Programming (SQP) is selected to obtain the optimum results. The main purpose of this paper is to demonstrate the design procedure with the optimization techniques for engineering and economics in the OTEC plant so that anyone else can build upon their models according to their needs.
Condensation of a Downward Flowing Vapor on a Horizontal Cylinder Embedded in a Porous Medium
Authors: Orozco J.
Published: April 2008

This article presents the results of an investigation on condensation of a downward flowing vapor on a horizontal cylinder embedded in a vapor-saturated porous medium. The Brinkman model is used to describe theoretically the flow field in both the liquid and vapor phases. The resulting governing equation was integrated numerically with the help of the fourth-order Runge-Kutta method. The dependence of the condensate layer thickness and Nusselt number on the vapor velocity and on the permeability of the porous material is reported. Experiments were conducted to verify the theoretical findings, and good agreement was found between theory and experiment.
Upward Vertical Two-Phase Flow Through an Annulus—Part I: Single-Phase Friction Factor, Taylor Bubble Rise Velocity, and Flow Pattern Prediction
Authors: Caetano E. F. , Shoham O. , Brill J. P.
Published: April 2008

Upward gas-liquid flow through vertical concentric and fully eccentric annuli was studied both experimentally and theoretically. A flow system was designed and constructed for this study. The system consists of a 16-m long vertical annulus with 76.2-mm i.d. casing and 42.2-mm o.d. tubing. A comprehensive experimental investigation was conducted for both concentric and fully eccentric annuli configurations, using air-water and air-kerosene mixtures as the flowing fluids. Included were definition and classification of the existing flow patterns and development of flow pattern maps. Measurements of volumetric average liquid holdup and average total pressure gradient were made for each flow pattern for a wide range of flow conditions. Additional data include single-phase friction factor values and Taylor bubble rise velocities in a stagnant liquid column. Data analysis revealed that application of the hydraulic diameter concept for annuli configurations is not always adequate, especially at low Reynolds number flow conditions. A more rigorous approach was thus required for accurate prediction of the flow behavior, especially for two-phase flow. Part I of the study includes experimental data and analyses of single-phase friction factor, Taylor bubble rise velocity, and flow pattern transition boundaries.
Analysis of the Inflow and Pressure Buildup Under Impending Blowout Conditions
Authors: Miska S. , Luo F. , Schafer-Perini A.
Published: April 2008

In this study a technique is provided for determining formation pore pressure and flow properties based upon analysis of shut-in drill pipe pressure. Both radial and spherical transient flow of slightly compressible fluid are considered. Solutions are provided in dimensionless forms. A newly developed concept of effective (equivalent) flowing rate and time is applied to replace the unknown variable flow rate which takes place prior to shutting-in the well. Two numerical examples show how to utilize the information on pit gain, approximate flow-in time and the shut-in drill pipe pressure to determine formation fluid pressure. Fluid mobility (spherical flow) and formation transmissibility (radial flow) can also be determined from knowledge of shut-in drill pipe pressure as a function of time. Application of the proposed method is simple, and therefore, useful on the rig floor.
Thermal Stress Field in Plasma-Sprayed Ceramic Coatings
Authors: Ferrari M. , Harding J. H.
Published: April 2008

In the cooldown phase of the deposition process, plasma-sprayed ceramic barrier coatings generate large residual stresses. In this paper, a scheme for the analysis of the thermal stresses is given, which accounts for the nonuniformity of the temperature field, and for the microstructure of the coating. The considered microstructural data include the morphology and orientation pattern of the porosities. The case of a coated sphere is studied, as an application. In this connection, the coating structure is computer-simulated, and the temperature profile is numerically determined.
Delamination of Graphite/Epoxy Laminate During Drilling Operation
Authors: Sadat A. B. , Chan W. S. , Wang B. P.
Published: April 2008

Delamination due to drilling is one of the major concerns in machining a composite laminate. This paper employed NIKE2D finite element code to predict the critical load for delamination in drilling simulation. Good agreement is achieved with the approximation analytical solution and the finite element results for the case of the model using isotropic material property. A circular plate of quasi-isotropic graphite/epoxy laminate with and without an aluminum plate backing was investigated for drilling load-induced delamination. It is found that drilling force-caused delamination can be significantly increased as the uncut portion is beyond a quarter thickness of the entire laminate thickness with an aluminum backing plate. It is suggested that the drilling operation be controlled as the drill nears the exit plane.
Wind Evaporator Heat Pumps—Part II: Thermal Performance Results
Authors: O’Reilly J. M. , Monaghan P. F.
Published: April 2008

Wind evaporators are alternative evaporators for air source heat pumps which rely on wind-driven or natural convection to move air across the heat transfer surfaces. A fully automatic, computer-controlled test facility which allows side-by-side testing of wind evaporator and conventional heat pumps and monitoring of weather conditions has been designed and built at University College Galway. The aim of this paper is to quantify the advantages of wind evaporators by comparing the performance of a wind evaporator heat pump with that of a conventional heat pump over an extended testing period and by examining the relationship between weather conditions and heat pump performance. In this paper, results are presented in the form of plots of coefficient of performance (COP), compressor power, evaporator and condenser heat transfers and climatic variables against time. In addition, a testing period coefficient of performance has been calculated for each heat pump. The results show that wind speed is the dominant climatic variable affecting wind evaporator heat pump performance, and that frost growth does not significantly reduce this performance. Even at extremely low wind speeds, the COP of the wind evaporator heat pump is not significantly affected. After over 460 hr of testing, the testing period COP of the wind evaporator heat pump shows a 16 percent increase over that of the conventional heat pump. (Refer to Nomenclature in Part I of this paper.)