bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical and functional outcomes in Middle Eastern patients with idiopathic pulmonary fibrosis
Authors: Alhamad Esam H. , Masood Mohamed , Shaik Shaffi Ahmad , Arafah Maha
Published: May 2008

Background:  Baseline clinical and physiological variables have been described as relevant predictors of survival among patients with idiopathic pulmonary fibrosis (IPF). However, substantial heterogeneity in both survival time and mortality has been observed with many of these predictive factors. The incidence and mortality rates of IPF vary from country to country, with race potentially contributing to such variations.

Objective:  We sought to describe baseline clinical features to determine their predictive value among Middle Eastern patients diagnosed with IPF.

Methods:  We retrospectively examined 61 patients diagnosed with IPF at a university hospital in Riyadh, Saudi Arabia.

Results:  At presentation, most patients exhibited either dyspnea or cough. The median survival time for all patients was 92 months. Diminished survival was significantly associated with finger clubbing (P = 0.01). Factors not influencing survival were age, gender, percent predicted forced vital capacity, percent predicted forced expiratory volume in 1 s, percent predicted total lung capacity, percent predicted diffusion capacity of the lung for carbon monoxide and resting oxygen saturation.

Conclusions:  Finger clubbing is a significant predictive variable and was associated with a 5‐fold increase in mortality. Other baseline demographic characteristics as well as pulmonary function tests were not predictive of prognosis in Middle Eastern patients with IPF. It appears that IPF patients of Middle Eastern descent have a longer median survival curve compared to other races.

Please cite this paper as: Alhamad EH, Masood M, Shaik SA and Arafah M. Clinical and functional outcomes in Middle Eastern patients with idiopathic pulmonary fibrosis. The Clinical Respiratory Journal 2008; 2: 220–226.
A SUCCESSFUL ANAEMIA MANAGEMENT ALGORITHM THAT ACHIEVES AND MAINTAINS OPTIMUM HAEMOGLOBIN STATUS
Authors: Benton Sharon
Published: May 2008

The paper describes the need for the introduction of an anaemia management algorithm. It discussed the problems which the unit had in constant reviewing and re‐prescribing ESA to maintain optimum haemoglobin levels for the unit's patients. The method used to create and use the algorithm is explained. The findings demonstrate the beneficial effects of using the algorithm. The paper concludes with the recommendation that algorithms should be more widely used for better treatment outcomes.
NURSES' KNOWLEDGE AND PRACTICE OF VASCULAR ACCESS INFECTION CONTROL IN HAEMODIALYSIS PATIENTS IN THE REPUBLIC OF IRELAND
Authors: Higgins Margaret , Evans David S.
Published: May 2008

Vascular access hygiene is an integral component of haemodialysis care. Ensuring nurses possess sufficient knowledge and utilise recommended guidelines on infection control is essential for safe practice and patient safety. The study aimed to investigate nurses' knowledge and practice of vascular access infection control among adult haemodialysis patients in the Republic of Ireland.

A confidential self‐completion questionnaire was sent to all 190 qualified nurses employed in nine haemodialysis units in the Republic of Ireland, which assessed knowledge and behaviour in infection control.

Although 92% of respondents reported that policies had been developed by their units and 47% had received infection control education in the previous year, knowledge and adherence to best practice demonstrated significant scope for improvement. The study recommended the development of standard guidelines and regular reviews and updates of policies. Systems should also be developed to ensure a high level of compliance.
PATIENT EXPERIENCE OF DIALYSIS REFUSAL OR WITHDRAWAL—A REVIEW OF THE LITERATURE
Authors: Noble Helen , Meyer Julienne , Bridges Jackie , Kelly Daniel , Johnson Barbara , DipCommNurs, SRN, HV
Published: May 2008

Aim. The aim of this literature review was to advance understanding of dialysis refusal and withdrawal in relation to the experiences of patients and carers and to explore the trajectory to death of those abating dialysis.

Method. Databases searched included CINAHL, Medline, PsycINFO, British Nursing Index, International Bibliography of the Social Sciences, ASSIA and Cancerlit. Forty‐four quantitative papers and two qualitative papers were identified.

Findings. The patient and carer experience is rarely explored in the literature but issues related to ‘Making decisions to withhold/forego or withdraw treatment’, ‘Length of survival without dialysis’, Prevalence of symptoms in end‐stage renal disease’, ‘The utilisation of Advance Directives’ and ‘The impact on families’ throw some light on the phenomena of dialysis refusal and withdrawal.

Conclusions. Little is known about those patients who withdraw from or decide not to commence dialysis. Empirical studies related to those who opt not to embark on dialysis are limited to four worldwide. There is an urgent need for further research to determine the experiences and needs of this population and a more patient‐centred approach is required, consistent with modern palliative medicine.
BUTTONHOLE CANNULATION: SHOULD THIS BECOME THE DEFAULT TECHNIQUE FOR DIALYSIS PATIENTS WITH NATIVE FISTULAS? Summary of the EDTNA/ERCA Journal Club discussion Autumn 2007
Authors: Murcutt Gareth
Published: May 2008

The paper discussed during autumn 2007 was a report entitled ‘Cannulating in haemodialysis: rope‐ladder or buttonhole technique?’ published in Nephrology Dialysis Transplantation. The authors agreed to follow the discussion and respond to points raised. Twenty‐three expert contributors from 13 different countries provided evidence, opinion and historical insights into vascular access techniques for chronic haemodialysis patients. All contributors who had introduced the buttonhole technique for patients with native arterio‐venous fistulas (AVFs) had found benefits for patients in terms of ease of cannulation, reduced pain and even reduced aneurysm formation. The discussion included expert advice on needling protocols, track formation and the sharp versus blunt needles debate. The buttonhole technique is virtually unheard of in some countries and the discussion covered some of the potential barriers to its introduction and offered advice on also how to overcome some of these issues.
CE: Continuing Education Article VASCULAR ACCESS MANAGEMENT 1: AN OVERVIEW
Authors: McCann Margaret , Einarsdóttir Hildur , Van Waeleghem Jean‐Pierre , Murphy F. , Sedgewick J.
Published: May 2008

Vascular access for renal replacement therapy (RRT) is seen as one of the most challenging areas confronting the nephrology multidisciplinary team. The vascular access of choice is the arterio‐venous fistula (AVF) followed by the arterio‐venous graft (AVG) and central venous catheter (CVC). A successful vascular access programme requires forward planning ensuring that enough time is available for the preservation of the access site, its creation and maturation. Successful cannulation of the vascular access requires on the part of the nephrology nurse, clinical expertise and knowledge on the management of different types of vascular access including different cannulation techniques.
CAN USING A QUESTIONNAIRE FOR ASSESSMENT OF HOME VISITS TO PERITONEAL DIALYSIS PATIENTS MAKE A DIFFERENCE TO THE TREATMENT OUTCOME?
Authors: Kazancioglu Rumeyza , Ozturk Savas , Ekiz Serpil , Yucel Lamia , Dogan Sevel
Published: May 2008

Training provided by dialysis nurses to the patients is of great importance in peritoneal dialysis (PD). This study aimed to examine how PD patients continue with the training and practice taught in this unit and correlate these data with the incidence of peritonitis.

Home visits were paid to 32 patients. A form including questions about ‘knowledge and skill’ and dialysis environment was filled in for each patient. Answers were graded out of 100 points and were reported as average, percentage and minimum‐maximum values.

The mean ‘knowledge and skill’ criterion scoring was 79.8 ±14.0, and the mean score for the dialysis environment was 87.7 ±10.9. There was a significant correlation between the ‘knowledge and skill’ and environmental scores. Meaningful correlations were detected between the ‘knowledge and skill’ score as well as the environmental score with the rate of peritonitis. Training is of vital importance in PD practice, but results show that the dialysis environment is as important as the patient's knowledge or skill in exchanges.
NEW CHOICES FOR PATIENTS NEEDING KIDNEY TRANSPLANTATION ACROSS ANTIBODY BARRIERS
Authors: Higgins Rob , Hathaway Mark , Lowe David , Zehnder Daniel , Krishnan Nithya , Hamer Rizwan , Briggs David
Published: May 2008

Antibodies in the blood of a kidney transplant recipient can provide a barrier to transplantation, which is additional to the usual possibility of cellular rejection. The antibodies most frequently encountered are ABO (blood group) and human leucocyte antigen (HLA) (tissue‐type) antibodies. About 250 living donor transplants each year in the United Kingdom have been stopped because of an antibody barrier. It is now possible to offer a choice of treatment modalities to these people, including exchange transplantation and antibody‐incompatible transplantation. It is likely that both schemes will complement each other and both are available in the United Kingdom.
A case of HIV co‐infected with hepatitis B virus precore/core deletion mutant treated by entecavir
Authors: Fukushima Koji , Ueno Yoshiyuki , Inoue Jun , Wakui Yuta , Obara Noriyuki , Kimura Osamu , Kido Osamu , Nakagome Yu , Kakazu Eiji , Matsuda Yasunori , Kogure Takayuki , Kondo Yasuteru , Nagasaki Futoshi , Yamagiwa Yoko , Ashino Yugo , Shimosegawa Tooru
Published: May 2008

We report a case of a HIV and hepatitis B virus (HBV)‐co‐infected patient to whom entecavir (ETV) was administered initially before the notification regarding the potential mutagenesis effect on HIV against the nucleoside analog. Since initial evaluations indicated the advanced stage of chronic hepatitis B and preserved numbers of peripheral CD4+ lymphocytes without the manifestation of immunodeficiency, priority was given to the management of HBV. We started HBV therapy with ETV at a dose of 0.5 mg daily without using any HIV drugs. The viral loads of both HBV and HIV‐1 decreased gradually during the 5 months following the initial administration of ETV. HBV was well controlled by the gradual replacement of ETV with highly‐active antiretroviral therapy against HIV with a regimen including atazanavir, emtricitabine, and tenofovir. HBV was genotyped as A2 with the quasispecies pool consisting of the −1G precore/core deletion mutant strain.
Clinical and endoscopic features of gastric varices secondary to splenic vein occlusion
Authors: Sato Takahiro , Yamazaki Katsu , Akaike Jun , Toyota Jouji , Karino Yoshiyasu , Ohmura Takumi
Published: May 2008

Aim:  This study provides a retrospective evaluation of cases with gastric varices secondary to splenic vein occlusion.

Methods:  Our study group consisted of 14 patients. The clinical manifestations, diagnostic methods and therapeutic modalities were analyzed retrospectively.

Results:  Eleven patients had co‐existing pancreatic diseases: seven with chronic pancreatitis, three with cancer of the pancreatic body or tail and one with severe acute pancreatitis. Among the three remaining patients, one had advanced left renal cancer, one had myeloproliferative disease and the third had splenic vein occlusion due to an obscure cause. A diagnosis of gastric varices was made following endoscope gastroduodenoscopy or endoscopic color Doppler ultrasonography (ECDUS), and splenic vein occlusions were diagnosed from enhanced computed tomography in all cases. Specific findings of gastric varices secondary to splenic vein occlusion were based on ECDUS color flow images of gastric variceal flow that clearly depicted round cardiac and fundal regions at the center, with varices expanding to the curvatura ventriculi major of the gastric body. For three cases with gastric variceal bleeding, endoscopic injection sclerotherapy using a mixture of histoacryl and lipiodol (70% histoacryl solution) was performed, after which no further bleeding from gastric varices was detected. Due to a high risk of gastric variceal rupture, splenectomy was performed in two cases and splenic arterial embolization in another two cases.

Conclusion:  ECDUS color flow images of gastric variceal flow depicted specific findings of gastric varices secondary to splenic vein occlusion. Treatment should take into account the diseases underlying these conditions.
Optimal duration of additional therapy after biochemical and virological responses to lamivudine in patients with HBeAg‐negative chronic hepatitis B: a randomized trial
Authors: Enomoto Masaru , Tamori Akihiro , Kohmoto Madoka Toyama , Hayashi Takehiro , Morikawa Hiroyasu , Jomura Hisato , Sakaguchi Hiroki , Habu Daiki , Kawada Norifumi , Shiomi Susumu , Nishiguchi Shuhei
Published: May 2008

Aim:  The endpoint of treatment with nucleoside analogs remains unclear for patients with hepatitis B e antigen (HBeAg)‐negative chronic hepatitis B. We report the results of a randomized trial to determine the optimal duration of additional therapy after response to lamivudine in HBeAg‐negative patients.

Methods:  Twenty‐two patients with HBeAg‐negative chronic hepatitis B who exhibited biochemical and virological responses to lamivudine were enrolled. When patients responded to treatment, they were randomly assigned to receive 12 more months of therapy (Group A, 11 patients) or 24 more months of therapy (Group B, 11 patients).

Results:  The baseline characteristics of the patients were similar in the two groups. Biochemical and virological responses were obtained in all patients within 6 months. Drug resistance developed in one patient in Group A during month 7 of additional therapy, and in five patients in Group B from months 13–23 of additional therapy. Ten patients in Group A and six in Group B completed the protocol and were included in analysis. Eight of the 10 patients in Group A experienced relapse between months 2 and 14 after the discontinuation of therapy, while three of the six patients in Group B experienced relapse between months 2 and 24. There was no difference in cumulative relapse rate between the groups (P = 0.275).

Conclusion:  Additional therapy with lamivudine for longer than 12 months after biochemical and virological responses in patients with HBeAg‐negative chronic hepatitis B could increase the risk of drug resistance, but did not reduce the rate of relapse.
Prediction of Solid Particle Erosive Wear of Elbows in Multiphase Annular Flow-Model Development and Experimental Validations
Authors: Mazumder Quamrul H. , Shirazi Siamack A. , McLaury Brenton S.
Published: May 2008

Erosion damage in the pipe wall due to solid particle impact can cause severe problems in fluid handling industries. Repeated impact of the suspended small solid particles to the inner wall of process equipment and piping removes material from the metal surface. The reduced wall thickness of high pressure equipment and piping can no longer withstand the operating pressure that they were originally designed for and may cause premature failure of the system components. This results in production downtime, safety, and environmental hazards with significant loss to the industry and economy. Prediction of erosion in single-phase flow with sand is a difficult problem due to the effect of different parameters and their interactions that cause erosion. The complexity of the problem increases significantly in multiphase flow where the spatial distribution of the liquid and gas phases and their corresponding velocities change continuously. Most of the currently available erosion prediction models are developed for single-phase flow using empirical data with limited accuracy. A mechanistic model has been developed for predicting erosion in elbows in annular multiphase flow (gas-liquid-solid) considering the effects of particle velocities in gas and liquid phases of the flow. Local fluid phase velocities in multiphase flow are used to calculate erosion rates. The effects of erosion due to impacts of solid particles entrained in the liquid and gas phases are computed separately to determine the total erosion rate. Erosion experiments were conducted to evaluate the model predictions. Comparing the model predicted erosion rates with experimental erosion data showed reasonably good agreement validating the model.
Technical Basis and Application of New Rules on Fracture Control of High Pressure Hydrogen Vessel in ASME Section VIII, Division 3 Code
Authors: Rana Mahendra D. , Rawls George B. , Sims J. Robert , Upitis Elmar
Published: May 2008

As a part of an ongoing activity to develop ASME Code rules for the hydrogen infrastructure, the ASME Boiler and Pressure Vessel Code Committee approved new fracture control rules for Sec. VIII, Division 3 vessels in 2006. These rules have been incorporated into new Article KD-10 in Division 3. The new rules require determining fatigue-crack-growth rate and fracture resistance properties of materials in high pressure hydrogen gas. Test methods have been specified to measure these fracture properties, which are required to be used in establishing the vessel fatigue life. An example has been given to demonstrate the application of these new rules.
Experimental and Numerical Investigation of Plain and Gouged Dents in Steel Pipes Subjected to Pressure and Moment Loading
Authors: Błachut J. , Iflefel I. B.
Published: May 2008

Six laboratory scale, mild steel pipes with the outside diameter-to-wall-thickness ratio, Do∕t≅40, were dented to about 15–20% of outside diameter Do, by a hemispherical indenter with its diameter to pipe’s outside diameter ratio, 2a∕Do≅0.41. Three pipes had surface gouges running axially in them, and the remaining three were gouge free. Five of them were then collapsed by a bending moment followed by pressure burst tests. Experimental test data has been used to benchmark the finite element results, details of which are given in this paper. Good agreement between experimental and numerical results was obtained in the modeling of denting, but not so well in the modeling of bending—indicating the need for further work in order to address the discrepancies.
Influence of Laser Peening Parameters on Residual Stress Field of 304 Stainless Steel
Authors: Ling Xiang , Peng Weiwei , Ma Gang
Published: May 2008

A nonlinear elastic-plastic finite element method is established to predict the residual compressive stress distribution induced by laser peening (LP) in AISI 304 stainless steel. The dynamic material property at a high strain rate (106∕s) is considered when building the two-dimensional finite element model. Effects of the laser power density, laser spot size, laser pulse duration, multiple LP processes, and one-/two-sided peening on the compressive stress field in the stainless steel are evaluated for optimizing the process. The numerical results have a good agreement with the data by x-ray diffraction method, and the compressive stresses induced by LP are greater than the tensile residual stresses that result from the welding process. Peening, in general, is an effective method for protecting stainless steel weldments against stress corrosion crack (SCC). The present work provides the basis for studying the mechanism on enhancing the SCC resistance in the weld joint of Type 304 stainless steel by LP.
Stress Concentration Factors for Oblique Holes in Pressurized Thick-Walled Cylinders
Authors: Nihous Gérard C. , Kinoshita Christopher K. , Masutani Stephen M.
Published: May 2008

Elastic stress concentration factors (SCFs) for internally pressurized thick cylindrical vessels with oblique circular crossholes are reported. Results of finite-element analyses for two wall ratios (k equal to 2.25 and 4.5) and a range of crosshole ratios (d from 0.1 to 0.5) show that SCFs sharply increase with the inclination α of the crosshole axis. These findings are consistent with earlier empirical design guidelines based on experimental investigations.
A CFD Study of the Flow Field, Resultant Force, and Aerodynamic Torque on a Symmetric Disk Butterfly Valve in a Compressible Fluid
Authors: Leutwyler Zachary , Dalton Charles
Published: May 2008

Butterfly valve performance coefficients are necessary for predicting the required torque necessary to operate the valve along with other essential parameters necessary for ensuring the safe operation. The availability of performance coefficients for compressible flow is limited, and experimental testing can be cost prohibitive. The capability of using computational fluid dynamics is a test to determine its viability for determining performance coefficients. The flow field, resultant force, and aerodynamic torque on a symmetric disk butterfly valve are studied computationally at disk positions 45deg and 70deg over a range of operating pressures. The range of pressure ratios was chosen to include subsonic and supersonic flow states. The flow fields were predicted using the k-epsilon renormalization group theory (RNG) turbulence model. The computational results were obtained using CFX 10 and were performed on an SGI ALTIX 330. The flow field is illustrated using velocity contours colored by a Mach number, and the effects of the disk position and pressure ratio are illustrated using disk pressure profiles. The computational predictions for the aerodynamic torque coefficients are compared to test data at both 45deg and 70deg. A simplistic model used to predict the resultant force acting on the disk is compared against the computational results to obtain a better understanding of the resultant force trend throughout the stroke. The numerical results were generally in good agreement with test data, although a few disparities existed.
3D Modeling of Fluid-Structure Interaction With External Flow Using Coupled LBM and FEM
Authors: Kwon Y. W. , Jo J. C.
Published: May 2008

Three-dimensional fluid-structure interaction was modeled using the coupled lattice Boltzmann and finite element methods. The latter technique was applied to model a structural behavior while the former was used to model a fluid field. For computationally efficient modeling of an external flow over embedded pipes with their interaction, the pipes were modeled using 3D beam elements rather than shell elements. This paper presented an algorithm on how to couple 3D beam elements with the lattice Boltzmann grids so that the fluid-structure interaction could be properly modeled at the outer surfaces of the pipes. Some numerical examples were analyzed using the developed technique, and the fluid-structure interaction characteristics were examined through the examples.
Experimental Investigation on Mechanical Properties of Plastic Pipes Reinforced by Cross Helically Steel Wires
Authors: Zheng Jinyang , Lu Yubin , Xiang Li , Lin Xiufeng , Zhu Yancong , Xu Ping , Chen Defu , He Xiaolian , Shao Taiqing
Published: May 2008

A Polyethylene (PE) pipe reinforced by a cross-winding steel wire (PSP) is a new type of plastic-matrix steel composite pipe, which has excellent performance. Its short-time burst pressure, strain, critical buckling pressure, and failure mode under various temperatures were investigated. Experimental results show that PSP has an increase of short-time burst pressure at room temperature up to 129%, ring stiffness up to 19%, and critical buckling pressure up to 57% in comparison with a comparable PE pipe. Failure modes of PSP subjected to internal pressure under various temperatures are found to be ductile burst and excessive deformation, and their transition temperature is about 45°C. Moreover, at the same pressure, the radial expansion ratio of PSP only bearing radial force is much larger than that of PSP bearing both radial and axial forces.
A Time-Reversal Defect-Identifying Method for Guided Wave Inspection in Pipes
Authors: Deng Fei , Wu Bin , He Cunfu
Published: May 2008

The temporal-spatial focusing effect of the time-reversal method on the guided wave inspection in pipes was investigated theoretically in the current research with a transfer function. The amplitude of the time-reversed wave propagating along the pipes was not only determined by the characteristics of the defect and the location for observation but also by the location of the time-reversal transducers. Especially, the quantity of transducers distributed around the pipe in the circumferential direction was found to be important in applying such time-reversal method. The results demonstrate that the time-reversal method can be used to enhance the inspection energy for the guided wave inspection in pipes and to locate the defects in the circumferential directions. Once the time-reversed signals obtained from the guided wave inspection are applied on a numerical model, the defects can be recognized by the motion of the time-reversed wave transmitting along the pipe model. Numerical simulation and experimental results are provided in this paper to illustrate the validity of such defect-identifying method.
Toward An Ultrasonic Sensor for Pressure Vessels
Authors: Sandman J. S. , Tittmann B. R.
Published: May 2008

The focus of this paper is an ultrasonic position indication system that is capable of determining one-dimensional target location in a high-temperature steel container with gaseous medium. The combination of the very high acoustical impedance of steel (45.4MRayl) and the very low impedance of a gas, for example, ambient air (0.0004MRayl), causes significant reflections at the interfaces. The strategy of this investigation was to develop an ultrasonic transducer capable of replacing a small portion of pressure vessel wall. In building such a transducer, acoustic matching layers for the steel-gas interface, a mechanically and acoustically competent housing, an efficient piezoelectric element, and appropriate backing materials are developed and tested. The results include a successful housing design, high- temperature acoustic matching layers, and subsequent successful wave forms with good signal-to-noise ratio. Target location through 9.6in.(24.5cm) of ambient air was possible, with a steel pressure boundary 0.456in.(1.160cm) thick, and the use of one matching layer. Our transducer was tested repeatedly to 340°C without apparent degradation. In addition to the experimental results, this investigation includes numerical simulations. Sample wave forms were predicted one dimensionally with the coupled acoustic piezoelectric analysis, a finite element program that predicts wave forms based on Navier’s equation for elastic wave propagation.
Ultrasonic Circumferential Guided Wave for Pitting-Type Corrosion Imaging at Inaccessible Pipe-Support Locations
Authors: Shivaraj K. , Balasubramaniam Krishnan , Krishnamurthy C. V. , Wadhwan R.
Published: May 2008

A higher order cylindrically guided ultrasonic wave was used for the detection and sizing of hidden pitting-type corrosion in the hidden crevice regions (between the pipe and the pipe supports) without lifting or disturbing the structural layout arrangement of the pipelines. The higher order circumferential guided waves were generated using a piezoelectric crystal based transducer, located at the accessible top region of the pipes, in a pulse-echo mode. By studying the experimental parameters such as dispersion, particle displacement, and wavelength of the ultrasonic guided wave modes, an appropriate higher order mode was selected for excitation using an appropriately designed acrylic angle wedge that conforms to the pipe’s outer curvature. A manual pipe crawler was designed with a provision for holding the wedge, and the essential hardware such as data acquisition card, encoder, etc., was integrated with the system so that the corrosion was mapped in real time during the scanning of the pipes. The system was validated on pipes ranging from 6in.to24in. outer diameters of wall thicknesses up to 12mm, by mapping defects as small as 1.5mm diameter and 25% penetration wall thickness. A 2D finite element model using ABAQUS® was used to understand the wave propagation in pipe wall and its interaction with pinhole-type defects.
Prediction of Failure Pressures in Pipelines With Corrosion Defects
Authors: Oliveros J. , Alamilla J. L. , Astudillo E. , Flores O.
Published: May 2008

The mathematical model to predict failure pressures in corroded pipelines proposed in this work is based on the analysis of the original model by Cronin and Pick. New definitions and interpretations in order to obtain this new model are given. As a consequence of this, the model can be more adequately interpreted and easier to apply under practical conditions. The new model and the finite element method are applied to predict failure pressures for pipelines with corrosion defects of elliptic and irregular geometries, and the predictions are similar. The model is used to predict the failure pressure in actual defects and compared to results of experimental tests and the original model. This study shows that pressures predicted by the model presented here are comparable to those of experimental tests.
Safety and Loss Management System for Pipelines
Authors: Abes Jake
Published: May 2008

Management systems have had long widespread acceptance in many industries for various applications: notably, quality, safety, and environment. In recent years, the North American onshore pipeline industry has started adopting management system principles for the management of pipeline integrity. This paper discusses the rationale for adopting a systems approach to safety and presents a safety and loss management system template that may be used for the full life cycle of a pipeline, from concept to abandonment.
Mechanical Properties of Cold Bend Pipes
Authors: Sen M. , Cheng J. J. R. , Murray D. W. , Zhou J.
Published: May 2008

Cold bends are frequently required in energy pipelines in order to change the vertical and horizontal orientations of the pipeline route. They are produced by plastically bending a pipe joint in a cold bending machine by creating a series of uniformly spaced incremental bends. This procedure acts to reduce the moment capacity and buckling strain of the pipe, and studying the changes in pipe properties caused by cold bending is valuable in assessing the level of this strength reduction. Accordingly, the initial imperfections and material transformations of five full-scale cold bend pipes were assessed in this research program. The imperfections were measured at several locations around the circumference of the specimens, along the entire bend length. It was determined that the distribution of imperfections was similar in shape to a sine function, and their amplitude ranged from 0.3mmto1.0mm. Tension coupon tests were conducted on the intrados, extrados, and virgin materials of the specimens. It was revealed that the extrados material exhibited an increase in yield strength due to work hardening and that the intrados material demonstrated a reduction in yield strength due to the Bauschinger effect. It was established that the imperfections, and material transformations in the specimens were predominantly unaffected by the incremental-bend magnitude or spacing that was employed during the cold bending procedure.
Thermodynamically Consistent Anisotropic Plasticity Model
Authors: Lukyanov Alexander A.
Published: May 2008

The objective of this paper is to consider the thermodynamically consistent anisotropic plasticity model based on full decomposition of stress tensor into generalized deviatoric part and generalized spherical part of stress tensor. Two fundamental tensors αij and βij, which represent anisotropic material properties, are defined and can be considered as generalizations of the Kronecker delta symbol, which plays the main role in the theory of isotropic materials. Using two fundamental tensors αij and βij, the concept of total generalized “pressure” and pressure corresponding to the volumetric deformation is redefined. It is shown that the formulation of anisotropic plasticity in the case of incompressible plastic flow must be considered independently from the generalized hydrostatic pressure. Accordingly, a modification to the anisotropic Hill criterion is introduced. Based on experimental research, which has been published, the modified Hill (1948, “A Theory of the Yielding and Plastic Flow of Anisotropic Metals,” Proc. R. Soc. London, Ser. A, 193(1033), pp. 281–297;1950, Mathematical Theory of Plasticity, Clarendon, Oxford) criterion for anisotropic elastoplasticity is validated. The results are presented and discussed, and future studies are outlined.
On the Estimation of Failure Rates of Multiple Pipeline Systems
Authors: Caleyo F. , Alfonso L. , Alcántara J. , Hallen J. M.
Published: May 2008

In this work, the statistical methods for the reliability of repairable systems have been used to produce a methodology capable to estimate the annualized failure rate of a pipeline population from the historical failure data of multiple pipeline systems. The proposed methodology provides point and interval estimators of the parameters of the failure intensity function for two of the most commonly applied stochastic models: the homogeneous Poisson process and the power law process. It also provides statistical tests for assessing the adequacy of the stochastic model assumed for each system and testing whether all systems have the same model parameters. In this way, the failure data of multiple pipeline systems are only merged in order to produce a generic failure intensity function when all systems follow the same stochastic model. This allows statistical and tolerance uncertainties to be addressed adequately. The proposed methodology is outlined and illustrated using real-life failure data of oil and gas pipeline systems.
Asymptotic Analysis for Buckling of Undersea Corroded Pipelines
Authors: Xue Jianghong
Published: May 2008

This paper deals with the buckling phenomenon of undersea corroded pipelines. The corrosion degree of the pipelines is characterized by two parameters: the angular extension and the corrosion depth. Previous work has shown that symmetric and antisymmetric buckling modes occur in pipelines when the corrosion is uniformly extended over part of pipelines along the circumferential direction. The presented research analyzes the stability condition in pipelines with generalized corrosion. Using WKB theory for asymptotic expansion, the buckling mode and the eigenfunctions are derived for the corroded pipelines subjected to external hydrostatic pressure. Furthermore, asymptotic solutions are derived for pipelines with constant corrosion and compared with validated solutions obtained in previous work using equilibrium analysis. It shows that the buckling modes and buckling pressure from asymptotic analysis are identical to the exact solutions. Symmetric and antisymmetric buckling modes are found to occur for pipelines when the corrosion is not uniform but symmetric about its centerline.
Failure of X52 Wrinkled Pipelines Subjected to Monotonic Axial Deformation
Authors: Zhang Y. , Das S.
Published: May 2008

This study was undertaken to investigate and understand the behavior of a wrinkled energy pipeline when subjected to sustained monotonic axial compressive deformation. This study involved both experimental and numerical investigations. Two full-scale laboratory tests with moderate and high internal pressures on X52 grade steel pipes with a diameter-to-thickness ratio of 45 show that this pipeline is extremely ductile and did not rupture under axisymmetric compressive axial deformation. However, they fail due to the excessive cross-sectional deformation and the final deformed shape looks like an accordion due to the formation of multiple wrinkles. Subsequently, a detailed parametric study using a numerical technique was undertaken to determine the failure condition and failure mode of this pipeline for various realistic internal pressures and diameter-to-thickness ratios. A nonlinear finite element method was used for the numerical study. The numerical model was validated with the data obtained from the two full-scale tests. The parametric study shows that the X52 linepipe loses its integrity due to the rupture in the pipe wall if the internal pressure is low and/or if the pipe has a small diameter-to-thickness ratio. This paper presents and discusses the results obtained both from the experimental and numerical parametric studies.
Analysis of Laminations in X52 Steel Pipes by Nonlinear by Finite Element
Authors: González Jorge Luis , Morales Alfredo
Published: May 2008

Hydrogen induced cracking is of great interest in the mechanical integrity assessment of sour gas pipelines. Multiple stepwise cracks with internal pressure called laminations are often observed in pipelines and their interaction and coalescence may significantly affect the residual strength of the pipes. In this work, the interacting fields of noncoplanar pressurized laminations in the wall of a pipe under pressure are analyzed by nonlinear finite element, considering an isotropic hardening law and the real tensile properties of the X52 steel. The results are presented as the evolution of the stress fields in the interlaminar region as a function of the pressure inside the laminations. It is found that for two approaching stepwise laminations, the critical pressure follows a hyperbolic type law. It is observed that for two cracks with lengths of less than 6.35 mm, the interlaminar region resists a critical pressure between 110 Mpa and 124 Mpa, respectively, for thicknesses 15.8 mm and 25.4 mm. The critical pressure is defined as the pressure inside the lamination that causes plastification of the interlaminar region.
The European Creep Collaborative Committee (ECCC) Approach to Creep Data Assessment
Authors: Holdsworth Stuart
Published: May 2008

The European Creep Collaborative Committee (ECCC) approach to creep data assessment has now been established for almost ten years. The methodology covers the analysis of rupture strength and ductility, creep strain, and stress relaxation data, for a range of material conditions. This paper reviews the concepts and procedures involved. The original approach was devised to determine data sheets for use by committees responsible for the preparation of National and International Design and Product Standards, and the methods developed for data quality evaluation and data analysis were therefore intentionally rigorous. The focus was clearly on the determination of long-time property values from the largest possible data sets involving a significant number of observations in the mechanism regime for which predictions were required. More recently, the emphasis has changed. There is now an increasing requirement for full property descriptions from very short times to very long and hence the need for much more flexible model representations than were previously required. There continues to be a requirement for reliable long-time predictions from relatively small data sets comprising relatively short duration tests, in particular, to exploit new alloy developments at the earliest practical opportunity. In such circumstances, it is not feasible to apply the same degree of rigor adopted for large data set assessment. Current developments are reviewed.
Collapse of Thick Tubes Pressurized From Outside: An Accurate Predictive Formula
Authors: Corradi Leone , Ghielmetti Christian , Luzzi Lelio
Published: May 2008

Several engineering applications require cylindrical shells subjected to external pressure, and an increasing need for tubes of significant thickness has been experienced in recent years. So far, little study has been devoted to very stocky tubes, and a great amount of uncertainty exists on some important aspects, such as the consequences of imperfections on their failure pressure. This can only be computed by performing numerical analyses that consider both material (plasticity) and geometric (large displacement) nonlinearities. Such a procedure is feasible, but its use for design purposes is cumbersome, and handy alternatives are worth searching. In this paper, a comparatively simple formula is proposed, based on an interpretation of the relative role that plasticity and instability play in the thick tube range. The formula depends on a crucial coefficient, which can be defined so as to provide safe but reasonably accurate approximations to the collapse pressures computed numerically for tubes made of different metals. The proposal may be useful for preliminary design purposes and can be considered as a first contribution toward a precise assessment of the collapse behavior of tubes in a thickness range so far overlooked.
Performance of a Novel Semiclosed Gas-Turbine Refrigeration Combined Cycle
Authors: Boza Joseph J. , Lear William E. , Sherif S. A.
Published: May 2008

A thermodynamic performance analysis was performed on a novel cooling and power cycle that combines a semiclosed gas turbine called the high-pressure regenerative turbine engine (HPRTE) with an absorption refrigeration unit. Waste heat from the recirculated combustion gas of the HPRTE is used to power the absorption refrigeration cycle, which cools the high-pressure compressor inlet of the HPRTE to below ambient conditions and also produces excess refrigeration depending on ambient conditions. Two cases were considered: a small engine with a nominal power output of 100kW and a large engine with a nominal power output of 40MW. The cycle was modeled using traditional one-dimensional steady-state thermodynamics, with state-of-the-art polytropic efficiencies and pressure drops for the turbomachinery and heat exchangers, and curve fits for properties of the LiBr-water mixture and the combustion products. The small engine was shown to operate with a thermal efficiency approaching 43% while producing 50% as much 5°C refrigeration as its nominal power output (roughly 50tons) at 30°C ambient conditions. The large engine was shown to operate with a thermal efficiency approaching 62% while producing 25% as much 5°C refrigeration as its nominal power output (roughly 20,000tons) at 30°C ambient conditions. Thermal efficiency stayed relatively constant with respect to ambient temperature for both the large and small engines. It decreased by only 3–4% as the ambient temperature was increased from 10°Cto35°C in each case. The amount of external refrigeration produced by the engine sharply decreased in both engines at around 35°C, eventually reaching zero at roughly 45°C in each case for 5°C refrigeration. However, the evaporator temperature could be raised to 10°C (or higher) to produce external refrigeration in ambient temperatures as high as 50°C.
Optimal Allocation of Heat Exchanger Inventory of a Two-Stage Vapor Compression Cycle for Maximum Coefficient of Performance
Authors: Morales M. J. , Sherif S. A.
Published: May 2008

The purpose of this study is to investigate how the heat exchanger inventory allocation plays a role in maximizing the thermal performance of a two-stage refrigeration system with two evaporators. First, the system is modeled as a Carnot refrigerator and a particular heat transfer parameter is kept constant as the heat exchanger allocation parameter is allowed to vary. The value of the heat exchanger allocation parameter corresponding to the maximum coefficient of performance (COP) is noted. The results are compared to those of a non-Carnot refrigerator with isentropic and nonisentropic compression. It is found that the Carnot refrigerator can be used to predict the value of the heat exchanger allocation parameter where the maximum COP occurs for a non-Carnot refrigerator. In order to improve the accuracy of that prediction, the predicted value of the heat exchanger allocation parameter has to be inputted into the set of equations used for the non-Carnot refrigerator. This study is useful in designing a low-cost, high-performance refrigeration system.
Thermoelectric Model of a Tubular SOFC for Dynamic Simulation
Authors: Jiang Wei , Fang Ruixian , Dougal Roger A. , Khan Jamil A.
Published: May 2008

A one-dimensional transient model of a tubular solid oxide fuel cell stack is proposed in this paper. The model developed in the virtual test bed (VTB) computational environment is capable of dynamic system simulation. This model is based on the electrochemical and thermal modeling, accounting for the voltage losses and temperature dynamics. The single cell is discretized using a finite volume method where all the governing equations are solved for each finite volume. The temperature, the current density, and the gas concentration distribution along the axial direction of the cell are presented. The dynamic behavior of electrical characteristics and temperature under the variable load is simulated and analyzed. For easy implementation in the VTB platform, the nonlinear governing equations are discretized in resistive companion form. The developed model is validated with experimental results and can be used for dynamic performance evaluation and design optimization of the cell under variable operating conditions and geometric condition.
The Examination of Liquid, Solid, and Gas Products Obtained by the Pyrolysis of the Three Different Peat and Reed Samples
Authors: Sutcu H.
Published: May 2008

Samples from four different parts of the peat deposits in the Yeniçağa (Bolu, Turkey) region were pyrolyzed in a fix-bed pipe type furnace at a heating rate of 2°C∕min and at a temperature of 600°C. The analyses for the structure of the liquid products obtained were performed by elemental analysis, H1-NMR spectroscopy and Fourier transform infrared spectroscopy. The structure of the solid products was determined by proximate and ultimate analyses, while the composition of gas products was found by gas chromatography.
Monitoring of Energetic and Exergetic Performance Analysis of Salihli Geothermal District Heating System
Authors: Ozgener Leyla , Ozgener Onder
Published: May 2008

This study deals with a monitoring and assessment of energetic and exergetic analysis of Salihli Geothermal District Heating System (SGDHS) in Manisa, Turkey. In the analysis, actual system yearly average data of latest heating season are used to assess the district heating system exergetic performance. New exergetic model is improved and compared with old exergetic model results throughout the SGDHS. The new exergy losses occur particularly due to the fluid flow, taking place in the reinjection of thermal water (e.g., geothermal fluid), pumps, and the heat exchanger, as well as the natural direct discharge of the system.
Response to Comment on "Brain IRS2 Signaling Coordinates Life Span and Nutrient Homeostasis"
Authors: Taguchi Akiko , White Morris F.
Published: May 2008

Differences in reported life span of mice heterozygous for a null allele of the insulin receptor substrate–2 (Irs2) might involve the effects of diet, breeding strategies, and genetic background on insulin-like signaling cascades. A better understanding will emerge from studies focusing on the coordination of nutrient homeostasis and life span by insulin-like signaling in specific peripheral tissues and the central nervous system.
The Microbial Engines That Drive Earth's Biogeochemical Cycles
Authors: Falkowski Paul G. , Fenchel Tom , Delong Edward F.
Published: May 2008

Virtually all nonequilibrium electron transfers on Earth are driven by a set of nanobiological machines composed largely of multimeric protein complexes associated with a small number of prosthetic groups. These machines evolved exclusively in microbes early in our planet's history yet, despite their antiquity, are highly conserved. Hence, although there is enormous genetic diversity in nature, there remains a relatively stable set of core genes coding for the major redox reactions essential for life and biogeochemical cycles. These genes created and coevolved with biogeochemical cycles and were passed from microbe to microbe primarily by horizontal gene transfer. A major challenge in the coming decades is to understand how these machines evolved, how they work, and the processes that control their activity on both molecular and planetary scales.