bluuebunny/crossref_metadata_2025 huggingface dataset:
Sibling Cases of Henoch–Schönlein Purpura in Two Families and Review of Literature
Authors: ZHANG YANG , GU WEIZHONG , MAO JIANHUA
Published: June 2008

Abstract:  The etiology and pathogenesis of Henoch–Schönlein purpura is unknown and few studies about familial cases of this disease have been reported. In this study, four Henoch–Schönlein purpura patients coming from two Chinese families were described. No genetic and environmental factors were found to be responsible for the occurrence of the four cases of HSP in tow families in this study.
Comparative Study on the Sustained Efficacy of Diphencyprone Immunotherapy Versus Cryotherapy in Viral Warts
Authors: CHOI MYEUNG HOON , SEO SOO HONG , KIM IL HWAN , SON SANG WOOK
Published: June 2008

Abstract:  This study compared the sustained clearance rate of viral warts treated with topical diphencyprone (DCP) therapy (group A) versus cryotherapy (group B). After 12 months follow‐up, 93.3% (42/45) of group A and 76.3% (29/38) of group B presented sustained clinical clearance. Our data suggest that topical DCP therapy may lead to the induction of the long‐term immunity to human papillomavirus (HPV).
Epidemiology of Atopic Dermatitis in Primary Schoolchildren in Turkey
Authors: ERGIN ŞENIZ , ÖZŞAHIN AYSUN , ERDOĞAN BERNA ŞANLI , AKTAN ŞEBNEM , ZENCIR MEHMET
Published: June 2008

Abstract:  The present study aimed to investigate the prevalence of atopic dermatitis in primary schoolchildren in Denizli, Turkey, and to determine the possible risk factors for atopic dermatitis in home environment. A self‐administered questionnaire was handled to the parents of 2,100 children aged 7 to 15 years, from three randomized primary schools and 1,644 (78.9%) completed and returned the questionnaire. The questionnaire included the United Kingdom Working Party diagnostic criteria and asked about conditions that could affect the course of atopic dermatitis. The prevalence of atopic dermatitis and coexisting factors that may affect the course of the disease were evaluated in 1,644 children (825 girls and 819 boys). The prevalence of atopic dermatitis was detected as 4.9%. Passive smoking, heating systems either in the house or in the child’s bedroom, and the number of people living in the house had no significant effect (p > 0.005). The difference in prevalence of atopic dermatitis between developed and developing countries is striking. The determination of the factors that have an influence in this issue will probably enable us to change the course and frequency of atopic dermatitis.
Cutaneous Features Associated with Microcephalic Osteodysplastic Primordial Dwarfism Type II
Authors: WEBBER NAOMI , O’TOOLE EDEL A. , PAIGE DAVID G. , ROSSER ELISABETH
Published: June 2008

Abstract:  We present an 18‐month‐old Pakistani girl who had short stature, craniofacial dysmorphism, and multiple café‐au‐lait spots. After consultation with the geneticists, microcephalic osteodysplastic primordial dwarfism type II was diagnosed (MIM210720). The presence of consanguinity in reported families is suggestive of autosomal recessive inheritance.
The Use of Naltrexone in the Management of Severe Generalized Pruritus in Biliary Atresia: Report of a Case
Authors: CHANG YUCHI , GOLKAR LINDA
Published: June 2008

Abstract:  Generalized pruritus secondary to cholestasis is a difficult dermatologic condition to treat. We present a case of a 17‐month‐old child with congenital biliary atresia with generalized pruritus refractory to treatment with oral antihistamines, topical steroids, cholestyramine, and rifampin but improved remarkably with the addition of naltrexone. Naltrexone is a well‐tolerated medication with little adverse effects. We believe that naltrexone may be an effective adjuvant treatment in the management of cholestatic pruritus in the pediatric population.
Transgrediens et Progrediens Palmoplantar Keratoderma (Greither Disease) and Confluent and Reticulated Papillomatosis of Gougerot and Carteaud in the Same Patient: A Coincidental Finding?
Authors: GREGORIOU STAMATIS , RIGOPOULOS DIMITRIS , CHARISSI CHRISTINA , AGIASOFITOU EFI , NIKOLAKIS GEORGE , KONTOCHRISTOPOULOS GEORGE
Published: June 2008

Abstract: A 13‐year‐old patient with typical findings of transgrediens et progrediens palmoplantar keratoderma that developed confluent and reticulated papillomatosis of Gougerot and Carteaud is presented. Although coexistence of the two disorders might be coincidental, the possibility of common pathogenetic pathways resulting in alterations of keratinization could be of investigational interest.
Multiple Deep Granuloma Annulare Limited to the Cephalic Segment in Childhood
Authors: NETO PIMENTAL DALVA REGINA , MICHALANY NILCEO , DE ABREU MARILDA APARECIDA MILANES MORGADO , ALCHORNE MAURICIO
Published: June 2008

Abstract:  Deep granuloma annulare is a rare variance of granuloma annulare. We present a 4‐year‐old boy with 30 lesions located only in the scalp with spontaneous regression of all lesions.
IgA Nephropathy in a Girl with Psoriasis and Seronegative Arthritis
Authors: WASILEWSKA ANNA , ZOCH‐ZWIERZ WALENTYNA MARIA , TENDERENDA EDYTA , SZYNAKA BEATA
Published: June 2008

Abstract:  IgA nephropathy is one of the most common forms of glomerulonephritis, but the coexistence of IgA nephropathy and psoriasis is very rare, especially in children. Herein we report the case of an 8‐year‐old girl with both psoriasis and IgA nephropathy who responded to treatment with cyclosporine A for both conditions.
Maternal cells are not resp for erythema tox neon
Authors: DROITCOURT CATHERINE , KHOSROTEHRAN KIARASH , HALABY EUGÉNIE , ARACTINGI SÉLIM
Published: June 2008

Letters to the Editor are welcomed for publication (subject to editing). Letters must be signed by all authors, typewritten double spaced, and must not exceed two pages of text including references. Two copies of all letters should be submitted along with one copy on disk. Letters should not duplicate material submitted or published in other journals. Prepublication proofs will not be provided.
Child‐Onset Cutaneous Lymphadenoma
Authors: SIDBURY ROBERT
Published: June 2008

Letters to the Editor are welcomed for publication (subject to editing). Letters must be signed by all authors, typewritten double spaced, and must not exceed two pages of text including references. Two copies of all letters should be submitted along with one copy on disk. Letters should not duplicate material submitted or published in other journals. Prepublication proofs will not be provided.
Child Onset Cutaneous Cymphodenia
Authors: KIM DAE SUK , KIM DO YOUNG , KWON YEON SOOK , CHUNG KEE YANG
Published: June 2008

Letters to the Editor are welcomed for publication (subject to editing). Letters must be signed by all authors, typewritten double spaced, and must not exceed two pages of text including references. Two copies of all letters should be submitted along with one copy on disk. Letters should not duplicate material submitted or published in other journals. Prepublication proofs will not be provided.
Acrodermatitis Enteropathica‐like Syndrome Secondary to Branched‐chain Amino Acid Deficiency in Inborn Errors of Metabolism
Authors: ÖZTÜRK YEŞIM
Published: June 2008

Letters to the Editor are welcomed for publication (subject to editing). Letters must be signed by all authors, typewritten double spaced, and must not exceed two pages of text including references. Two copies of all letters should be submitted along with one copy on disk. Letters should not duplicate material submitted or published in other journals. Prepublication proofs will not be provided.
Apoptosis and Necrosis in the Ischemic Zone Adjacent to Third Degree Burns
Authors: Singer Adam J. , McClain Steve A. , Taira Breena R. , Guerriero Jennifer L. , Zong Wexing
Published: June 2008

Objectives:  Burns are characterized by a central zone of necrosis surrounded by a zone of potentially reversible ischemia. The authors explored the contribution of necrosis and apoptosis to cell death in the zone of ischemia.

Methods:  A previously established rat contact thermal injury model that utilizes a brass comb to produce four distinctive burns sites separated by three “interspaces” of unburned skin was used. The interspaces represent the zone of stasis or ischemia while the burn sites represent the zone of coagulation. With this model, most unburned interspaces progress to necrosis over 2 to 3 days. Full‐thickness 3‐mm biopsies were obtained from the interspaces, burns, and normal skin controls at 30 minutes, 24 hours, and 48 hours after injury. Slides were stained with hematoxylin and eosin as well as activated cleaved caspase‐3 (CC3a) for evidence of apoptosis and high‐mobility group box 1 (HMGB1) for evidence of necrosis.

Results:  Necrosis was not seen at 30 minutes, but was found in a large number of cells within the epidermis, sebaceous glands, and follicles at 24 and 48 hours. Faint nuclear CC3a staining indicative of apoptosis was present in a minority of cells within the epidermis, dermal fibroblasts, dermal follicles, and dermal sebaceous glands at 30 minutes and to a lesser degree at 24 and 48 hours.

Conclusions:  Both early apoptosis and delayed necrosis are present in the zone of ischemia, contributing to injury progression. Necrosis appears to play a larger role than apoptosis in injury progression in the comb burn model.
Untreated Hypertension and the Emergency Department: A Chance to Intervene?
Authors: Umscheid Craig A. , Maguire Maureen G. , Pines Jesse M. , Everett Worth W. , Baren Jill M. , Townsend Raymond R. , Mines Daniel , Szyld Demian , Gross Robert
Published: June 2008

Objectives:  Untreated hypertension (HTN) is a major public health problem. Screening for untreated HTN in the emergency department (ED) may lead to appropriate treatment of more patients. The authors investigated the accuracy of identifying HTN in the ED, the proportion of ED patients with untreated HTN, patient characteristics predicting untreated HTN, and provider documentation of untreated HTN.

Methods:  The authors performed a retrospective cross‐sectional study on a random sample of 2,061 adults treated at an urban academic ED. The validity of six candidate definitions of HTN in the ED was assessed in a subsample using outpatient clinic records as the reference standard. “Untreated HTN” was HTN without a HTN medication listed in the ED history. “Documentation of untreated HTN was documentation of HTN as a visit problem, specific referral for HTN, or ED discharge with a HTN” information sheet or a HTN medication. Multivariable logistic regression was used to determine associations.

Results:  The preferred definition of HTN in the ED had sensitivity of 86% (95% confidence interval [CI] = 80% to 90%), specificity of 78% (95% CI = 69% to 85%), and accuracy of 83% (95% CI = 78% to 87%). Of the 42% (95% CI = 40% to 44%) of ED patients with HTN, 43% (95% CI = 39% to 46%) had untreated HTN. Patients who were younger and male, without primary care physicians, with fewer prior ED visits, and without cardiovascular comorbidities, had higher odds of untreated HTN. Of those with untreated HTN, 8% (95% CI = 5% to 11%) had their untreated HTN documented.

Conclusions:  Untreated HTN was common in the ED but rarely documented. Providers can use ED blood pressures along with patient characteristics to identify those with untreated HTN for referral to primary care.
Predictive Value of T‐wave Abnormalities at the Time of Emergency Department Presentation in Patients with Potential Acute Coronary Syndromes
Authors: Lin Kathy B. , Shofer Frances S. , McCusker Christine , Meshberg Emily , Hollander Judd E.
Published: June 2008

Objectives:  T‐wave abnormalities on electrocardiograms (ECGs) are common, but their ability to predict 30‐day cardiovascular outcomes at the time of emergency department (ED) presentation is unknown. The authors determined the association between T‐wave abnormalities on the presenting ECG and cardiovascular outcomes within 30 days of presentation in patients with potential acute coronary syndromes (ACSs).

Methods:  This was a secondary analysis of a prospective cohort study of ED patients that presented with a potential ACS. Patients were excluded if they had a prior myocardial infarction, ST‐segment elevation or depressions, right or left bundle branch block, or Q‐waves on the initial ECG. Data included demographics, medical and cardiac history, and ECG findings including the presence or absence of T‐wave flattening, inversions of 1–5 mm, and inversions >5 mm. Investigators followed the hospital course for admitted patients, and 30‐day follow‐up was performed on all patients. The main outcome was a composite of death, acute myocardial infarction, revascularization, coronary stenosis greater than 50%, or a stress test with reversible ischemia.

Results:  Of 8,298 patient visits, 5,582 met criteria for inclusion: 4,166 (74.6%) had no T‐wave abnormalities, 721 (12.9%) had T‐wave flattening in two or more leads, 659 (11.8%) had T‐wave inversions of 1–5 mm, and 36 (0.64%) had T‐wave inversions >5 mm. The composite endpoint was more common in patients with T‐wave flattening (8.2% vs. 5.7%; p = 0.0001; relative risk [RR] = 1.4; 95% confidence interval [CI] = 1.1 to 1.9), T‐wave inversions 1–5 mm (13.2% vs. 5.7%; p = 0.0001; RR = 2.4; 95% CI = 1.8 to 3.1), and T‐wave inversions >5 mm (19.4% vs. 5.7%; p = 0.0001; RR = 3.4; 95% CI = 1.7 to 6.1), or any T‐wave abnormality (10.8% vs. 5.7%; p = 0.0001; RR = 1.9; 95% CI = 1.6 to 2.3), even after adjustment for initial troponin. This association also existed in the subset of patients without known coronary artery disease.

Conclusions:  In patients with potential ACS presenting to the ED, T‐wave abnormalities are associated with higher rates of 30‐day cardiovascular events.
Critical molecular regions for elicitation of the sweetness of the sweet‐tasting protein, thaumatin I
Authors: Ohta Keisuke , Masuda Tetsuya , Ide Nobuyuki , Kitabatake Naofumi
Published: June 2008

Thaumatin is an intensely sweet‐tasting protein. To identify the critical amino acid residue(s) responsible for elicitation of the sweetness of thaumatin, we prepared mutant thaumatin proteins, using Pichia pastoris, in which alanine residues were substituted for lysine or arginine residues, and the sweetness of each mutant protein was evaluated by sensory analysis in humans. Four lysine residues (K49, K67, K106 and K163) and three arginine residues (R76, R79 and R82) played significant roles in thaumatin sweetness. Of these residues, K67 and R82 were particularly important for eliciting the sweetness. We also prepared two further mutant thaumatin I proteins: one in which an arginine residue was substituted for a lysine residue, R82K, and one in which a lysine residue was substituted for an arginine residue, K67R. The threshold value for sweetness was higher for R82K than for thaumatin I, indicating that not only the positive charge but also the structure of the side chain of the arginine residue at position 82 influences the sweetness of thaumatin, whereas only the positive charge of the K67 side chain affects sweetness.
Generalist predators in organically and conventionally managed grass‐clover fields: implications for conservation biological control
Authors: Birkhofer K , Fließbach A , Wise D.H , Scheu S
Published: June 2008

Organically managed agroecosystems rely in part on biological control to prevent pest outbreaks. Generalist predators (Araneae, Carabidae and Staphylinidae) are a major component of the natural enemy community in agroecosystems. We assessed the seasonal dynamics of major generalist predator groups in conventionally and organically managed grass–clover fields that primarily differed by fertilisation strategy. We further established an experiment, manipulating the abundant wolf spider genus Pardosa, to identify the importance of these predators for herbivore suppression in the same system and growth period. Organic management significantly enhanced ground‐active spider numbers early and late in the growing season, with potentially positive effects of plant cover and non‐pest decomposer prey. However, enhancing spider numbers in the field experiment did not improve biological control in organically managed grass–clover fields. Similar to the survey results, reduced densities of Pardosa had no short‐term effect on any prey taxa; however, spider guild structure changed in response to Pardosa manipulation. In the presence of fewer Pardosa, other ground‐running spiders were more abundant; therefore, their impact on herbivore numbers may have been elevated, possibly cancelling increases in herbivore numbers because of reduced predation by Pardosa. Our results indicate positive effects of organic farming on spider activity density; however, our survey data and the predator manipulation experiment failed to find evidence that ground‐running spiders reduced herbivore numbers. We therefore suggest that a positive impact of organic fertilisers on wolf spiders in grass–clover agroecosystems may not necessarily improve biological control when compared with conventional farming.
Orbital venous malformation: percutaneous treatment using an electrolytically detachable fibred coil
Authors: Diolaiuti Sara , Iizuka Tateyuki , Schroth Gerhard , Remonda Luca , Laedrach Kurt , El‐Koussy Marwan , Frueh Beatrice E. , Goldblum David
Published: June 2008

Purpose:  To report the efficacy of percutaneous treatment of an orbital venous malformation with an electrolytically detachable fibred coil.

Methods:  We report an instance of radiography‐guided percutaneous treatment with an electrolytically detachable fibred coil in a 16‐year‐old boy with acute, spontaneous, painless proptosis on the left side, which progressed with time.

Results:  Magnetic resonance imaging, angiography and orbitophlebography revealed a low‐flow, intraorbital venous malformation. Percutaneous puncture and drainage were followed by a short remission. Following an acute recurrence, a single detachable fibred coil was deployed via a percutaneous approach under angiographic guidance. No radiological or clinical recurrences were observed over 4 years.

Conclusions:  Embolization of a deep orbital venous malformation with detachable fibred coils via a percutaneous approach can be highly effective, and may be considered before proceeding with open surgery.
Effective and Efficient Breakwater Design for Trading Vessels and FPSOS
Authors: Varyani Kamlesh , Hodgson Trevor , Pham Xuan
Published: June 2008

Breakwaters obviously need to fulfill their function (protecting sensitive structures or cargo) while at the same time remaining intact and imposing manageable loads onto supporting structure. It goes without saying that such breakwaters should be cost effective, so that complex designs with extensive welding may not be preferable. In this paper the authors discuss green water loading on breakwaters for trading vessels like container ships which have forward speed and FPSOs which have zero speed. Different generic designs of V shape, vane type, double skin with and without holes, and forward sloping forecastle (whaleback deck) breakwaters applied to trading vessels are discussed. Guidelines for modeling green water horizontal loading on breakwaters of FPSOs and trading vessels using computational fluid dynamics (CFD) techniques are provided. The paper will also include a review of breakwater design criteria in rules and regulations.
Effects of Avoidance of Heavy Weather on the Wave-Induced Load on Ships
Authors: Shu Zhi , Moan Torgeir
Published: June 2008

This paper is concerned with evaluating the effect of heavy weather avoidance on the long-term wave-induced loads on ships. Two hydrodynamic codes, VERES based on a 2D strip theory and WASIM based on a 3D Rankine panel method, are employed to calculate the wave-induced loads and motions on various vessels. Two models for heavy weather avoidance are envisaged. The first one is based on the assumption that operational criteria relevant to vertical acceleration, green water, and bottom slamming are fulfilled. The second one is based on the assumption that the sea state forecasts are available to the shipmaster and that rerouting is made. Based on the first model, the effect of the heavy weather avoidance on the long-term wave-induced hull girder loads is evaluated. In particular, the effect of hydrodynamic analysis methods and wave scatter diagram are also assessed. The calculated values are compared with those given in ship rules. The results show that several factors should be critically assessed in evaluating the accuracy of the ship rule values.
Ultimate Limit State Assessment of the M.V. Derbyshire Hull Structure
Authors: Paik Jeom Kee , Seo Jung Kwan , Kim Bong Ju
Published: June 2008

The Capesize bulk carrier, M.V. Derbyshire, sank in the North West Pacific during typhoon Orchid in September 1980 when she was on a voyage from Canada to Japan carrying fine iron ore concentrates. Since then, extensive investigations of the vessel sinking have previously been made in the literature primarily by the formal safety assessment technique to explore the loss causes, but serious speculation on the failure of hull structures has been lacking in such investigations. The present paper investigates the possibility of the vessel sinking initiated by the failure of hull structures rather than by other loss scenarios, such as hatch cover failure subsequent to water ingress into the cargo holds. Ultimate limit state assessments of individual stiffened panels and hulls of the M.V. Derbyshire under extreme bending moments during the last voyage in storm are made using ALPS/ULSAP and ALPS/HULL computer programs. It is concluded that the M.V. Derbyshire could have sunk by hull girder collapse with or even without unintended water ingress into cargo holds. Important insights and findings developed from the present study are summarized.
Structural Reliability of a Suezmax Oil Tanker Designed According to New Common Structural Rules
Authors: Soares C. Guedes , Parunov Joško
Published: June 2008

The paper aims at quantifying the changes in notional reliability levels that result from redesigning an existing suezmax tanker to comply with new Common Structural Rules (CSR) requirement for ultimate vertical bending moment capacity. The probability of structural failure is calculated using a first-order reliability method. The evaluation of the wave-induced load effects that occur during long-term operation of the ship in the seaway is carried out in accordance to International Association of Classification Societies (IACS) recommended procedure. Comparative analysis of long-term distributions of vertical wave bending moment calculated by two independent computer seakeeping codes is performed. The still-water loads are defined on the basis of a statistical analysis of loading conditions from the loading manual. The ultimate collapse bending moment of the midship cross section, which is used as the basis for the reliability formulation, is evaluated by CSR single-step procedure and by program HULLCOLL for progressive collapse analysis of ship hull-girders. The reliability assessment is performed for as-built and corroded states of the existing ship and a reinforced design configuration complying with CSR. It is shown that hull-girder failure probability of suezmax tanker reinforced according to new CSR is reduced several times. Sensitivity analysis and a parametric study are performed to investigate the variability of results to the change of parameters of pertinent random variables within their plausible ranges.
Impact of Residential Fuel Cell System Parameters on Its Economic Assessment
Authors: Millette J. , Dostie M. , Morneau J.-F.
Published: June 2008

This study evaluates different fuel cell system configurations for residential applications from an economic standpoint. The evaluation is made using a Monte Carlo simulation for different building types, heating systems, and rate structures. Electric and thermal energy produced and used, energy from the grid, and gas consumption are evaluated using a frequency energy model. This frequency model is based on detailed energy consumption measurements. Sensitivity analysis shows that the parameters defining the potential residential market are building type, utility rates, and heating systems. These are not related to fuel cell system characteristics. In general, the systems offering the lower annual net payment are fuel cells with Pnom about 1kW, no battery, cogeneration system for space heating and domestic hot water heating.
High Power Density Solid Oxide Fuel Cells for Auxiliary Power Unit Applications
Authors: Draper Robert , DiGiuseppe Gianfranco
Published: June 2008

High power density (HPD) solid oxide fuel cells (SOFCs) possess the attributes of reduced ohmic polarization and greater active area per unit volume, relative to current state-of-the-art cylindrical SOFCs. Several variations of the basic “flattened tube” HPD geometry are being analyzed and tested. For example, the HPD10 cell enjoys a 58% gain in power density over current practice. In this variation, ten air channels are separated by nine ribs that connect the flat faces of the cell. Other cell geometries, such as the delta cell, and advanced cell materials are under consideration and have the potential for further improvement in power density. The higher power density makes the application of HPD SOFCs to compact auxiliary power units (APUs) attractive. This paper reviews geometric and performance characteristics for HPD cells and presents a conceptual design for an APU of 5kW net output.
Fuel Cells and Cogeneration
Authors: Parise J. A. R. , Vargas J. V. C. , Marques R. Pitanga
Published: June 2008

Although historically grown as independent energy technologies, fuel cell and cogeneration may adequately work to each other’s benefit. Some fuel cells deliver heat at sufficiently high temperatures, which can be certainly used as heat sources for cogeneration or trigeneration schemes. The paper presents an overview of the innumerable fuel cell system configurations for simultaneous production of (i) heat and power, (ii) cooling and electricity, and (iii) cooling, heat, and electricity. The survey includes combined power cycles (also called hybrid systems) where the fuel cell works together with other thermodynamic cycles to produce, with a high fuel-to-electricity efficiency, electricity alone. A large number of cogeneration arrangements are mentioned. Some are described in detail. A brief analysis of benefits and drawbacks of such systems was undertaken. The review was limited to articles published in archival periodicals, proceedings, and a few technical reports, theses, and books.
Impact of Materials and Design on Solid Oxide Fuel Cell Stack Operation
Authors: Diethelm Stefan , Van herle Jan , Wuillemin Zacharie , Nakajo Arata , Autissier Nordahl , Molinelli Michele
Published: June 2008

Planar SOFC stack technology based on a unique concept (SOFConnex™) uses structured gas distribution layers between unprofiled metal sheet interconnects and thin Ni-YSZ anode supported electrolyte cells. The layers are flexible both in material and design and allow to implement new configurations relatively simply; manifolding can be internal, external, or combined. Together with thin stack components, independent of the supplier, the SOFConnex™ stacking approach allows compact planar assembly with low cost potential and adequate power density. Different cell and flow designs have been realized. With a basic flow configuration, short stacks (50cm2 cell active area) were assembled and tested, power density at 800°C reaching 0.5W∕cm2 at 0.7V average cell voltage (1.5kWe∕L, 0.36Ωcm2 area specific resistance), for 65% fuel utilization and 35% lower heating value electrical efficiency. Short stacks were thermally cycled and operated with both hydrogen and syngas. Degradation was essentially Ohmic (confirmed from impedance spectroscopy on stacks) and at first mainly due to the cathode-electrolyte interfacial reaction, performance loss was subsequently strongly reduced after cathode replacement. Using multiple voltage probes with additional interconnects allowed to separately monitor current collection losses during polarization. With an improved design in terms of sealing, postcombustion control and flow field, stacks up to 1kWe have been operated.
Combination of Biological Processes and Fuel Cells to Harvest Solar Energy
Authors: Ihrig Dieter F. , Heise H. Michael , Brunert Ulrich , Poschmann Martin , Kuckuk Ruediger , Stadtlander Klaus
Published: June 2008

Biomass production by micro-algae is by a factor of 10 more efficient than by plants, by which an economic process of solar energy harvesting can be established. Owing to the very low dry mass content of algal suspensions, the most promising way of their conversion to a high exoergic and transportable form of energy is the anaerobic production of biogas. On account of this, we are developing such processes including a micro-algal reactor, methods for micro-algal cell separation and biomass treatment, and a subsequent two-stage anaerobic fermentation process. First results from parts of this development work are shown. The continuous feeding of the anaerobic process over several weeks using micro-algal biomass is discussed in more details. The biogas is composed of methane, higher hydrocarbons, carbon dioxide, and hydrogen sulphide. Using steam reforming, it can be converted to a mixture of carbon dioxide and hydrogen. These gases can be separated using membrane technology. It is possible to form a closed carbon cycle by recycling the carbon dioxide to the micro-algal process. The transportable and storable hydrogen product is a valuable energy source and can be converted to electrical energy and heat using fuel cells. The simulation of such a process will be explicated.
Optimizing the Performance of a Single PEM Fuel Cell
Authors: Zhang Zhuqian , Wang Xia , Zhang Xinxin , Jia Li
Published: June 2008

A three-dimensional steady-state electrochemical mathematical model is developed where the mass, fluid, and thermal transport processes are considered, as well as the electrochemical reaction phenomena. The influences of the parameters of interest, which include porosity, permeability, and the thickness of the gas diffusion layer, and the inlet gas stoichiometric ratio on the performance of fuel cells are identified. By applying the Powell algorithm, the optimum values of multiple parameters are obtained while optimizing the potential of the electrolyte phase at the membrane/cathode interface at a typical value of the cell voltage. Compared with the reference case, the optimized results, such as the oxygen mole fraction and the local current density distribution, provide useful information for a better design of fuel cells.
State of the Art: Hydrogen storage
Authors: Cumalioglu I. , Ertas A. , Ma Y. , Maxwell T.
Published: June 2008

Hydrogen is often considered to be the ultimate energy source for vehicles. However, if hydrogen is to fuel practical vehicles, then the development of fuel cell and hydrogen fueled engine technology must be accompanied by significant improvements in hydrogen storage techniques. Compressed hydrogen storage tanks, liquid hydrogen storage tanks, and containment systems for hydrides are examined to compare their advantages, disadvantages, and potential for onboard and stationary hydrogen storage systems. Each technique reviewed possesses specific shortcomings; thus, none can adequately satisfy the requirements of a hydrogen based economy.
Exergy Analysis of a Gas Turbine Cycle With Steam Generation for Methane Conversion Within Solid Oxide Fuel Cells
Authors: Granovskii Mikhail , Dincer Ibrahim , Rosen Marc A.
Published: June 2008

The combination of fuel cells with conventional mechanical power generation technologies (heat engines) promotes effective transformation of the chemical energy of fuels into electrical work. The implementation of solid oxide fuel cells (SOFCs) within gas turbine systems powered by natural gas (methane) requires an intermediate step of methane conversion to a mixture of hydrogen and carbon monoxide. State-of-the-art Ni-YSZ (yttria-stabilized zirconia) anodes permit methane conversion directly on anode surfaces, and contemporary designs of SOFC stacks allow this reaction to occur at elevated pressures. An exergy analysis of a gas turbine cycle integrated with SOFCs with internal reforming is conducted. As the efficiency of a gas turbine cycle is mainly defined by the maximum temperature at the turbine inlet, this temperature is fixed at 1573K for the analysis. In the cycle considered, the high-temperature gaseous flow from the turbine heats the input flows of natural gas and air, and is used to generate pressurized steam, which is mixed with natural gas at the SOFC stack inlet to facilitate its conversion. This technological design permits avoidance of the generally accepted recirculation of the reaction products around the anodes of SOFCs, which reduces the capacity of the SOFC stack and the entire combined power generation system correspondingly. At the same time, the thermal efficiency of the combined cycle is shown to remain high and reach 65–85% depending on the SOFC stack efficiency. The thermodynamic efficiency of the SOFC stack is defined as the ratio of electrical work generated to the methane oxidized (through the intermediate conversion). For a given design and operating condition of the SOFC stack, an increase in the thermodynamic efficiency of a SOFC is attained by increasing the fuel cell active area. Achieving the highest thermodynamic efficiency of the SOFC stack leads to a significant and nonproportional increase in the stack size and cost. For the proposed steam generating scheme, increasing the load of the SOFC stack is accompanied by a decrease in steam generation, a reduction in the steam to methane ratio at the anode inlet, and an increased possibility of catalyst coking. Accounting for these factors, the range of appropriate operating conditions of the SOFC stack in combination with steam generation within a gas turbine cycle is presented.
Infrared Thermography and Thermoelectrical Study of a Solid Oxide Fuel Cell
Authors: Ju Gang , Reifsnider Kenneth , Huang Xinyu
Published: June 2008

One of the most challenging problems in SOFC is the thermal compatibility of materials. Mechanical failure, or cathode delamination induced performance degradation, is related to local heat generations. An accurate measurement of spatial temperature distribution with correlated electric current provides good information for fuel cell performance and thermal management. Because insufficient ability of measuring electric current introduced heat generation, infrared thermography, instead of thermocouple, was used to measure the instantaneous cathode surface temperature response to the electric current in an operating electrolyte supported planar solid oxide fuel cell (LSCF-6ScSZ-NiO). The numerical model was built to study the coupled current and temperature relation by incorporating the temperature dependent material properties, i.e., Ohmic resistance and activation resistance, as a global function in the model. The thermal and electric fields were solved simultaneously. The measured and the predicted results agreed to each other well. The cathode polarization overpotential tended to increase with the current at the low current densities, but the simulated polarization-current curve exhibited a decreased slope under higher current densities that is ascribed to the local temperature increases due to the current.
Kinematics Under Extreme Waves
Authors: Stansberg Carl Trygve , Gudmestad Ove T. , Haver Sverre K.
Published: June 2008

Nonlinear contributions in near-surface particle velocities under extreme crests in random seas can be important in the prediction of wave loads. Four different prediction methods are compared in this paper. The purpose is to observe and evaluate differences in predicted particle velocities under high and extreme crests, and how well they agree with measurements. The study includes linear prediction, a second-order random wave model, Wheeler’s method [1970, “Method for Calculating Forces Produced by Irregular Waves,” JPT, J. Pet. Technol., pp. 359–367] and a new method proposed by Grue et al. [2003, “Kinematics of Extreme Waves in Deep Water,” Appl. Ocean Res., 25, pp. 355–366]. Comparison to laboratory data is also made. The whole wave-zone range from below still water level up to the free surface is considered. Large nonlinear contributions are identified in the near-surface velocities. The results are interpreted to be correlated with the local steepness kA. Some scatter between the different methods is observed in the results. The comparison to experiments shows that among the methods included, the second-order random wave model works best in the whole range under a steep crest in deep or almost deep water, and is therefore recommended. The method of Grue et al. works reasonably well for z>0, i.e., above the calm water level, while it overpredicts the velocities for z<0. Wheeler’s method, when used with a measured or a second-order input elevation record, predicts velocities fairly well at the free surface z=ηmax, but it underpredicts around z=0 and further below. The relative magnitude of this latter error is slightly smaller than the local steepness kA0 and can be quite significant in extreme waves. If Wheeler’s method is used with a linear input, the same error occurs in the whole range, i.e., also at the free surface.
On the Occurrence of Abnormal Waves in an Offshore Tank
Authors: Antão E. M. , Soares C. Guedes
Published: June 2008

A set of wave data generated in an offshore tank is studied. The set of the largest waves in those sea states is studied with respect to steepness, asymmetry, and nonlinearity. It was possible to find some waves that were classified as abnormal or freak according to presently accepted criteria. Their statistics connected to steepness and nonlinearity was determined. Comparison of the nonlinearity as well as statistics of the largest waves in the offshore tank and at sea was performed so as to identify any limitation in reproduction of the properties of large waves in model basins.
Background of ABS Buckling Strength Assessment Criteria for Cylindrical Shells in Offshore Structures
Authors: Sun Hai-Hong , Tan Pao-Lin
Published: June 2008

Cylindrical shells, unstiffened or stiffened with rings and/or stringers, are commonly used in offshore structures as main loading-carrying members. Comprehensive theoretical work and experimental studies on the buckling behavior of cylindrical shells have been carried out in the past. The increasing offshore application of stiffened cylindrical shells has raised some new challenges that need to be addressed. This paper provides the fundamental principles and technical background of the ABS buckling strength assessment criteria for cylindrical shells applied in offshore structures. The accuracy of ABS buckling criteria for assessing the cylindrical shells is established by benchmarking the results against an extensive database of test results assembled by American Bureau of Shipping. The results are also compared against current recognized offshore standards, such as API Bulletins 2U and DnV CN30.1. It is demonstrated that the ABS criteria provide very effective and sufficiently accurate predictions for the cylindrical shell buckling calculations.
Ultimate Strength of Transverse Plate Assemblies Under Uniaxial Loads
Authors: Luís Rui M. , Witkowska Malgorzata , Soares C. Guedes
Published: June 2008

This paper addresses the influence of adjacent plates on the strength of a single plate by studying the strength of panels composed of three and five plates transversely connected and loaded along the longitudinal direction,. The influence of adjacent plates is studied in two limiting cases of the shapes of initial imperfections in those plates. First, a comparison between the strength of panels having asymmetric imperfections in adjacent plate elements and of single plates is made, which allows evaluating the ability of the single plate to properly simulate the panel strength. Following this, the results obtained for a panel model having symmetric imperfections in adjacent plates are confronted with the results of the asymmetric imperfections. The asymmetrical and symmetrical models of the panel give, respectively, the lowest and highest strengths possible (imperfections in adjacent plates with different amplitudes have intermediate strengths), allowing to establish limits to the variation of the strength. The results show that using a single plate for assessing the strength of a panel made of those plates can be conservative or nonconservative, depending on the plate slenderness and shape of initial deflections. It is concluded that for design purposes, it will in general be enough to consider assemblies of three plates, as the results for five plate assemblies are not much different.
Are There Different Kinds of Rogue Waves?
Authors: Liu Paul C. , MacHutchon Keith R.
Published: June 2008

There is clearly no immediate answer to the question posted by the title of this paper. Inasmuch as that there are not much definitively known about rogue waves and that there is still no universally accepted definition for rogue waves in the ocean, we think there might just be even more than one kind of rogue waves to contend with. While the conventional approach has generally designated waves with Hmax∕Hs greater than 2.2 as possible rogue waves, based on Rayleigh distribution considerations, there is conspicuously no provision as to how high the ratio of Hmax∕Hs can be and thus not known how high can a rogue wave be. In our analysis of wave measurements made from a gas-drilling platform in South Indian Ocean, offshore from Mossel Bay, South Africa, we found a number of cases that indicated Hmax∕Hs could be valued in the range between 4 and 10. If this were to be the case, then these records could be considered to be “uncommon” rogue waves, whereas a record of Hmax∕Hs in the range between 2 and 4 could be considered to comprise “typical” rogue waves. On the other hand, the spikes in the Hmax data could have been caused by equipment malfunction or some other phenomenon. Clearly, the question of whether or not there are different kinds of rogue waves cannot be readily answered by theoretical considerations alone and there is a crucial need for long-term wave time-series measurements for studying rogue waves.
Rogue Waves: Results of the MaxWave Project
Authors: Rosenthal W. , Lehner S.
Published: June 2008

Safety of shipping is an ever growing concern. In a summary, Faulkner investigated the causes of shipping casualties (2002, “Shipping Safety: A Matter of Concern,” Ingenia, The Royal Academy of Engineering, Marine Matters, pp. 13–20) and concluded that the numbers of unexplained accidents are far too high in comparison to other means of transport. From various sources, including insurers data over 30% of the casualties are due to bad weather (a fact that ships should be able to cope with) and a further 25% remain completely unexplained. The European project MaxWave aimed at investigating ship and platform accidents due to severe weather conditions using different radars and in situ sensors and at suggesting improved design and new safety measures. Heavy sea states and severe weather conditions have caused the loss of more than 200 large cargo vessels within the 20years between 1981 and 2000 (Table 1 in Faulkner). In many cases, single “rogue waves” of abnormal height as well as groups of extreme waves have been reported by crew members of such ships. The European Project MaxWave deals with both theoretical aspects of extreme waves and new techniques to observe these waves using different remote sensing techniques. The final goal is to improve the understanding of the physical processes responsible for the generation of extreme waves and to identify geophysical conditions in which such waves are most likely to occur. Two-dimensional sea surface elevation fields are derived from marine radar and space borne synthetic aperture radar data. Individual wave parameters such as maximum to significant wave height ratios and wave steepness, are derived from the sea surface topography. Several ship and offshore platform accidents are analyzed and the impact on ship and offshore design is discussed. Tank experiments are performed to test the impact of designed extreme waves on ships and offshore structures. This article gives an overview of the different work packages on observation of rogue waves, explanations, and consequences for design.
Analysis on the Hull Girder Ultimate Strength of a Bulk Carrier Using Simplified Method Based on an Incremental-Iterative Approach
Authors: Özgüç Özgür , Barltrop N. D. P.
Published: June 2008

The hull girder ultimate strength of a typical bulk carrier is analyzed using a simplified method based on an incremental—iterative approach. First, vertical bending moment is examined by seven different methods. The moment versus curvature curves and the values of the ultimate longitudinal moments at collapse states are determined for both hogging and sagging cases. Second, the ultimate strength under coupled vertical and horizontal bending moment is accounted. An interaction curve is obtained, which corresponds to the results of series of calculation for the ship hull subject to bending conditions with different angles of curvature. It is found that the interaction curve is asymmetrical because the hull cross section is not symmetrical with respect to the horizontal axis and the structural response of the elements under compression is different from that under tension due to nonlinearity caused by buckling. The angles of the resultant bending moment vector and that of the curvature vector are different in investigated cases. The interaction design equations proposed by other researches are also addressed to discuss the results presented by this study.
A Comparison Between the Design Point and Near-Stall Performance of an Axial Compressor
Authors: McDougall N. M.
Published: June 2008

Detailed measurements have been made within an axial compressor operating both at design point and near stall. Rotor tip clearance was found to control the performance of the machine by influencing the flow within the rotor blade passages. This was not found to be the case in the stator blade row, where hub clearance was introduced beneath the blade tips. Although the passage flow was observed to be altered dramatically, no significant changes were apparent in the overall pressure rise or stall point. Small tip clearances in the rotor blade row resulted in the formation of corner separations at the hub, where the blade loading was highest. More representative clearances resulted in blockage at the tip due to the increased tip clearance flow. The effects that have been observed emphasize both the three-dimensional nature of the flow within compressor blade passages, and the importance of the flow in the endwall regions in determining the overall compressor performance.
Stall Inception in Axial Compressors
Authors: McDougall N. M. , Cumpsty N. A. , Hynes T. P.
Published: June 2008

Detailed measurements have been made of the transient stalling process in an axial compressor stage. The stage is of high hub-casing ratio and stall is initiated in the rotor. If the rotor tip clearance is small stall inception occurs at the hub, but at clearances typical for a multistage compressor the inception is at the tip. The crucial quantity in both cases is the blockage caused by the endwall boundary layer. Prior to stall, disturbances rotate around the inlet flow in sympathy with rotating variations in the endwall blockage; these can persist for some time prior to stall, rising and falling in amplitude before the final increase, which occurs as the compressor stalls.