bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational Assessment of Remaining Load Carrying Capacity of Pipes With Areal Surface Defects
Authors: Sˇpaniel Miroslav , Novotny´ Ctirad , Ru˚zˇicˇka Milan , Petrosˇ Jaroslav , Pavelkova´ Romana
Published: July 2010

This paper reports on two criteria for burst pressure prediction of pipe with the areal surface defect. The criteria deal with not circumferential defects in internally pressured pipes without significant global bending loads. On the basis of the experimental analysis relatively simple methodologies of prediction were designed. They are based on finite element (FE) analysis and representing transition between analytical approaches and full failure simulations employing material failure models. Concept of presented methodologies is based on similarity of stress, strain and material state when plastic collapse starts in the defect domain. The similarity is expressed in terms of simple one-parametric criteria: (i) geometry and topology of the domain at which the plastic state of material is reached, (ii) amount of specific energy dissipated by plastic deformation in the regions, where the ratio of energy dissipated by plastic deformation compared to elastic stress energy is too high. Calibration of these methodologies is based on burst tests of DN800 pipes made of X60 steel with artificial defects. The ranges of defects dimensions are: longitudinal from 120 mm to 340 mm; circumferential from 60 mm to 180 mm; remaining thickness from 2.7 mm to 6.1 mm.
Numerical Investigation Into End Condition Effects on the Response of Reinforced Concrete Columns to Airblast
Authors: Hansen Eric , Tennant Darren , Levine Howard
Published: July 2010

Dynamic finite element analysis using explicit time integration is a useful tool for evaluating the response of reinforced concrete columns to both near-contact and offset charges. Typical analyses model a single column in the structure in order to decrease analysis times and isolate the target column response from the general structural response. The effects, if any, of the assumed boundary conditions at the isolated column ends on the column response to the airblast loads are not fully understood at this time. This paper attempts to provide a more complete understanding of such end condition effects by investigating the response of a single column model with a variety of end conditions and comparing these responses to those of a column in a much larger structural model.
An Integrated Approach for Monitoring Gas Accumulation in Safety Related Systems
Authors: Ezekoye L. Ike , Griffin Ryan D. , Turkowski William M. , Williams Gregory R.
Published: July 2010

Gas intrusion into safety related systems, such as the Emergency Core Cooling System (ECCS), Decay Heat Removal (DHR) and Containment Spray (CS) system in nuclear power plants is undesirable and has led to pump binding and damaging water hammer events. Furthermore, total or momentary loss of hydraulic performance in safety related pumps has occurred, which has led to pump damage rendering the pumps unable to perform their safety functions or reduce the pump discharge pressure and flow capacity to the point that the system cannot perform its design function. Extreme cases of water hammer can result in physical damage to system piping, components and supports, and possible relief valve lifting events with consequential loss of inventory. The U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter GL-2008-01, “Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems,” requiring U.S. utilities to demonstrate that suitable design, operation and testing measures are in place to maintain licensing commitments. GL-2008-01 outlines a number of actions that are detailed in nature, such as establishing pump void tolerance limits, establishing limits on pump suction void fractions, assuring adequate system venting capability, identifying all possible sources of gas intrusion, preventing vortex formation in tanks and determining acceptable limits of gas in system discharge piping. Regarding one of these issues, GL-2008-01 indicates that the amount of gas that can be ingested without significant impact on pump operability and reliability is not well established and is known to depend on pump design, gas dispersion and flow rate. Each U.S. nuclear power plant licensee is required to evaluate their ECCS, DHR and CS system design, operation and test procedures to assure that gas intrusion is minimized and monitored in order to maintain system operability and compliance with the requirements of the U.S. code of federal regulations 10 CFR 50 Appendix B. Typically, gases get into the safety related systems through a number of mechanisms, such as maintenance, gas desorption, vortex activities, cavitation, etc. This paper discusses the sources of gas into safety related systems and the challenges associated with management of gas voids in these systems. A number of technologies exist that can detect the gas that accumulates in the safety related piping. These technologies are discussed and an integrated approach for monitoring gas accumulation in safety related pipes is presented. Issues such as methods to get rid of gases and venting periodicity are discussed. Industry efforts to address the management of gases in these systems are also presented.
New Safety Assessment System for Corroded Underground Pipelines
Authors: Sza´vai Szabolcs , Lenkey Gyo¨ngyve´r B.
Published: July 2010

The most important question for the user is if pipelines having metal loss defect could be operated safely, if any pipe sections should be repaired or replaced, and how much is the reserved safety against a possible failure. There are several engineering methods for determining the safety margin of operation but those are usually quite conservative. For this reason Lenkey has proposed safety diagrams based on finite element analysis of external corrosion defects in underground pipelines [4]. These safety diagrams could be used to determine safety factors in a less conservative way for critical situations during the pipeline operation. The FEM calculations have been verified by burst tests carried out on several pipe sections. In the present paper the results of some further analyses are presented about the difference between the measured, numerically and analytically determined failure pressure values.
Recent Concepts for the Welding of High Strain Pipelines
Authors: Newbury Brian D. , Hukle Martin W. , Crawford Mark D. , Sleigh Joshua , Altstadt Steven A. , Gordon J. Robin , Lillig Daniel B.
Published: July 2010

Standard allowable stress-based pipeline designs (strain demand ≤ 0.5%) are now giving way to more complex strain-based designs (strain demand higher than 0.5%) as the locations of future pipelines move into regions of increased strain demand. The increase in required levels of strain demand are attributed to seismic activity, soil movement, soil liquefaction, frost heave, thaw settlement, ice scour or a combination thereof. Pipelines in high strain demand regions are typically limited by the strain capacity of the girth weld. As strain-based pipeline design has matured, it has become evident that specific material properties (both weld metal and line pipe), defect size, defect location, misalignment, and operating pressure each affect the strain capacity of the pipeline. This paper reviews proposed design and testing methodologies for the qualification of strain-based design welding procedures. These methods have been applied in the development and qualification of welding procedures for the construction of pipelines subject to longitudinal tensile strains in excess of 2%. Strain-based design requires considerably more effort than traditional design in terms of girth weld qualification and testing. To ensure adequate girth weld strain capacity for strain-based design the testing includes large scale and full-scale pressurized testing for design validation.
Buckling of Thin-Walled Long Steel Cylinders Under Bending
Authors: Houliara Sotiria , Karamanos Spyros A.
Published: July 2010

The present paper investigates structural response and buckling of long unstiffened thin-walled cylindrical steel shells, subjected to bending moments, with particular emphasis on their stability design. The cylinder response is characterized by cross-sectional ovalization, followed by buckling (bifurcation instability), which occurs on the compression side of the cylinder wall. Using a nonlinear finite element technique the bifurcation moment is calculated, the post-buckling response is determined, and imperfection sensitivity with respect to the governing buckling mode is examined. The results show that the buckling moment capacity is affected by cross-sectional ovalization. It is also shown that buckling of bent elastic long cylinders can be described quite accurately through a simple analytical model, which considers the ovalized pre-buckling configuration and results in closed-form expressions. Using this analytical solution, the incorporation of the ovalization effects in the design of thin-walled cylinders under bending is discussed, in the framework of the provisions of the new European Standard EN1993-1-6.
Research on Aseismatic Measures of Gas Pipeline Crossing a Fault for Strain-Based Design
Authors: Gu Xiaoting , Zhang Hong
Published: July 2010

There are a lot of researches on qualitative aseismatic measures for buried gas pipeline crossing movable faults. But a few of them are quantitative, especially in the size and shape of the trench. In this paper, based on strain-based pipeline design method and finite element method, a new strain analysis model for buried large diameter gas pipeline is presented that deals quantitatively with the pipeline strain influencing factors, such as the size and shape of the trench, buried pipe depth, crossing angle between pipeline and fault, pipe diameter and wall thickness, mechanical properties of original soil and back fill soil, inner pipeline pressure. In this model, the pipeline is simulated by pipe element and elbow element, soil-pipe interaction is reduced to 3 dimensional soil spring. By means of FEM software ABAQUS, detail analysis is performed for a real design case of pipeline crossing a movable fault in the second west-east gas pipeline project of China, and optimized pipeline crossing fault scheme is proposed which can minimize the pipeline strain and limit it in allowable value.
Suggestions to Consider Including as Part of an Appendix to Section 6000 of the ASME High Pressure Systems Standard
Authors: Fryer D. M.
Published: July 2010

The original planned Scope for Section 6000 of the ASME High Pressure Systems Standard intended including guidance for users of the standard for estimating the amount of confined energy that might be released if there were a sudden and catastrophic failure of a pressure containing chamber; and also to provide information on various ways to confine or at least protect personnel and other equipment from the shock wave resulting from such a catastrophic failure. Unfortunately, such “how to” guidance was not included in the subsequent standard. This paper includes suggestions for creating Appendix type “how to” information for estimating several confined energy release situations and how these energy levels can be used to estimate shock wave frontal pressures that have to be defended against. The examples used herein include release energies of pressurized liquid, pressurized gas, and pressurized vaporizing liquid like fluid.
Determination of Fracture Arrest Stress
Authors: Staats Jeremy C. , Osage David A.
Published: July 2010

Pressure vessel components constructed to the ASME B&PV Code, Section VIII, Divisions 1 and 2 that are not subject to Post Weld Heat Treatment (PWHT) have a fracture arrest stress value set equal to 10% of the Ultimate Tensile Strength (UTS) of the material. The fracture arrest stress designates an applied stress value for a material at or below which crack propagation would cease in a component with a small flaw. The fracture arrest stress value in the code is based upon work conducted by T. S. Robertson [1] and William S Pellini [2]. This work included testing of base metal and welded joints without significant constraint. Pellini concluded that for welded plates without constraint, localized residual stress fields, resulting from restraint of longitudinal shrinkage during cooling of the weld metal, act in a direction parallel to the weld and thus can only propagate cracks oriented in a direction normal to the localized residual stress (i.e. perpendicular to the weld joint). The perpendicular cracks may propagate into the base metal; however, these cracks will arrest due to lower or negligible residual stresses outside of the weld zone in the base metal. Therefore, for manufacture of components welded without significant constraint, i.e. manufacture of ships and atmospheric storage tanks, the fracture arrest stress value equal to 10% of the UTS appears to be valid. In the manufacture of pressure vessels, the geometrical constraint of typical weld joints results in a different residual stress distribution that have stress components that are orientated both parallel and perpendicular to the weld. Due to the presence of residual stresses perpendicular to the weld, small cracks parallel to the weld joint may result in unstable crack propagation or brittle fracture because they remain in the residual stress field. Therefore, the use of a fracture arrest stress value equal to 10% of the UTS detailed in paragraph 3.11.5.1 of the ASME Section VIII, Division 2, Part 3 criteria document may not be valid. A review of the work conducted by Robertson and Pellini and current code rules is provided and compared to fracture assessments results using procedures from API 579-1/ASME FFS-1 and ASME Section VIII, Division 2, Part 3.
Fatigue Life Prediction of Notched Components Based on Multiaxial Local Stress-Strain Approach
Authors: Qiu Baoxiang , Gao Zengliang , Wang Xiaogui
Published: July 2010

A multiaxial local stress-strain approach based on the Armstrong-Frederick type cyclic plasticity theory was proposed to perform the stress analysis and the fatigue analysis on the notched components. A robust cyclic plasticity model was adopted to describe the non-Masing behavior of 16MnR steel. The incremental form of the multiaxial local stress-strain approach was formulated with the incremental constitutive relations and the incremental Neuber’s rule. The multiaxial stress-strain state at the notch root of notched components subjected to proportional and nonproportional loading was predicted by the multiaxial approximate approach. On the basis of the multiaxial local stress-strain state and the Fatemi-Socie criterion, the fatigue lives of the notched components were predicted. The analytical results show that the proposed multiaxial local stress-strain method can describe the multiaxial stress state at the notch root very well, and the predicted fatigue lives correlate well with the experimental data.
Determination of the Stress Intensity Factors for Axisymmetric Cylindrical Interface Crack by an Eigenvalue Method
Authors: Weng Lin , Gao Zengliang , Wang Xiaogui
Published: July 2010

An eigenvalue method was proposed to study the stress intensity factors associated with the oscillating stress singularity for the axisymmetric cylindrical interface crack of the fiber/matrix composites. The fiber is a transversely isotropic material and the matrix is isotropic. Based on the fundamental equations of the spacial axisymmetric problem and the assumption of first-order approximation of the singular stress field, the discrete characteristic equation was derived using the displacement functions in the form of separated variables and the technique of meshless method. The eigenvalue is relative to the order of stress singularity, and the associated eigenvector is with respect to the displacement angular variations. The stress angular variations were derived by introducing the displacement angular variations into the constitutive relations. A finite element fiber/matrix model was used to verify the validation of the proposed eigenvalue method. The numerical results of the order of stress singularity and normalized stress angular variations are in good agreement with those obtained by the eigenvalue method. Based on the order of stress singularity and stress angular variations obtained by the eigenvalue method, as well as the numerical singular stress fields obtained by the finite element method (FEM), the stress intensity factors were determined successfully with the linear extropolation method.
Fatigue Crack Growth and Remaining Life Assessment of 2024 Aluminum With Variation in Microstructure
Authors: Kermanidis Alexis T. , Pantelakis Spiros G.
Published: July 2010

The LTSM-F crack growth model is implemented in the present work for the assessment of crack growth and remaining fatigue life of 2024 aluminium alloy with different microstructure. The effect of microstructure in the crack growth analysis is simulated by means of respective yield strength and fracture toughness values of the material. The analytical results obtained are compared against experimental results performed on a series of fatigue crack growth specimens of the alloy under constant amplitude and irregular loading including overload and real stress histories. The analytical results demonstrate the potential of the model to account for crack growth behaviour under irregular loading conditions of dissimilar microstructures.
Numerical Prediction of Constraint Effect of Creep Crack Growth
Authors: Yatomi Masataka , Nikbin Kamran M.
Published: July 2010

This paper presents the effect of constraint on creep crack growth (CCG) using FE analysis based on the stress and strain rate state at the crack tip. The comparison is made by modelling C(T) specimen tests under plane stress and plane strain conditions using creep properties of three different steels (C-Mn steel, P91 steel, and 316H austenitic steel). In addition, in order to examine the constraint effect on CCG due to geometry single edge notch specimen (SENT), centre cracked tension specimen (CCT) and three point bending (3PB) specimen have also been analysed. In all cases it is found that when the reference stress under plane strain conditions is higher than the yield stress, there is little difference between CCG rates under plane stress and plane strain.
Comparison of Parent and Butt Fusion Material Properties of High Density Polyethylene
Authors: Shim D.-J. , Krishnaswamy P. , Focht E.
Published: July 2010

The US nuclear power industry is seeking U. S. Nuclear Regulatory Commission (USNRC) approval to use high density polyethylene (HDPE) in safety-related applications. The USNRC has granted approval for the use of HDPE for safety-related service water applications, with limitations, to Catawba (Duke Energy Corp.) and Callaway (Union Electric Co.) based on separate relief requests submitted by the licensees. The nuclear industry continues to show increasing interest in utilizing HDPE in safety-related piping systems. In order to evaluate and maintain the structural integrity of HDPE pipes, the material properties and the fracture resistance behavior must be fully characterized. Although there has been extensive work on material property development of HDPE, most of the investigations have been focused on the parent (base) material. Hence, the material property and fracture resistance behavior of the butt fusion region have not been comprehensively investigated. In this paper, tensile, dynamic mechanical analysis (DMA), and slow crack growth (SCG) tests have been performed for PE 4710 HDPE material. Specimens were machined from both parent piping material and butt fusion regions. The test results indicate that the tensile and DMA properties show no significant differences between parent and butt fusion materials. However, in terms of SCG resistance, the time to failure for butt fusion material was an order of magnitude lower than that of the parent material.
A Means of Avoiding Sulfur Recovery Reaction Furnace Fired Tube Boiler Failures
Authors: Porter Mike , Martens Dennis , McGuffie Sean , Wheeler John
Published: July 2010

One of the common causes of premature tube failure in fired tube boilers — technically described as film boiling — is overheating of the tubes caused by steam blanketing. Current literature contains a significant amount of information on this problem, but not much in the way of definitive guidance for avoiding the problem. General “rules of thumb” are available for identifying the heat flux limit required to avoid the problem as in Martens et al [1]. Unfortunately, the values presented by different sources are often in disagreement. This paper will look at a sulfur recovery unit (SRU) Claus waste heat boiler application and, through the use of Computational Fluid Dynamics (CFD), develop a means of predicting the conditions that lead to steam blanketing and resultant tube failure. Local heat flux conditions at gas side discontinuities (such as the tube inlet ceramic ferrule terminations) combined with associated local water side steam entrainment, and steam generation with coupled velocity effects are discussed.
Opportunities for Permanent Corrosion Monitoring of Pipelines Using Guided Wave Tomography
Authors: Bloom Joost G. P. , Heerens Gert-Jan , Volker Arno W. F.
Published: July 2010

Corrosion and erosion are two major degradation mechanisms of piping systems and pipelines that both lead to wall thickness loss. To ensure sufficient integrity levels of these assets NDE is currently conducted at time based intervals often associated with shut downs. However, both economical and social requirements are pushing the industry to higher levels of availability, reliability and safety of installations at minimum costs. Using permanent sensors that continuously monitor the wall thickness of assets over large areas allows improvement of the availability of installations at lower inspection costs. Because when inline data is continuously available the maintenance can be planned (just) in time at the most optimal moment. Therefore, the permanent sensors will save inspection costs and minimize unplanned maintenance. This can not be achieved with the current method of periodic inspections even when this is done risk based, because some corrosion processes behave unpredictable. This paper demonstrates a system which is able to monitor the wall thickness of pipe lines over large areas in an economical attractive way using a limited number of low-power ultrasonic transducers. The transducers excite specific guided wave modes with a phase velocity that strongly depends on the wall thickness. By applying tomographic inversion to the travel time of these wave modes along different paths, a wall thickness map with 100% coverage can be obtained. Experimental results on a 10″ steel pipe with a wall thickness (WT) of 8 mm show that this system is able to detect and size defects with a depth of 10% and diameter of 15 cm. The area covered in this case was the complete wall of a pipe with a length of 4 m. This paper further explains the advantages and the performance of this system. Furthermore, it will give an outlook of the possible applications.
Effect of Machining Process on Stable Crack Growth
Authors: Mourad Abdel-Hamid I. , Abu-Assi Aladdin
Published: July 2010

This paper aims to present an experimental evidence of the effect of machining process on stable crack growth behaviour (SCG) through AISI 4340 low alloy steel. Brittle fracture behaviour had been discovered in a batch of compact tension CT specimens, unlike previous batches that had shown ductile (stable crack growth) behaviour. This was unexpected, and indeed, was anomalous. An investigation was thus carried out to understand what processes that have affected the behaviour. Such anomalous brittle behaviour was observed while performing the fracture test on the affected specimen. The load-load displacement (P-ΔLL) curves show that the “normal” specimen exhibiting stable crack growth and the non-linear region, in the anomalous curve of the anomalous specimens, is rather limited. This indicates very limited, if any, stable crack growth. Fracture tests were carried out on CT specimens with different heat treatments to find the cause of this unexpected embrittlement. Microhardness measurements, tensile tests and microscopic (SEM) examination were also carried out and reported. The results suggest that, a great attention is needed during machining process to avoid accidental changes in the properties and to avoid misleading experimental results.
Determination of J-R Curve for X60 Pipeline Steel Using SENT Specimens and Normalization Method
Authors: Zhu Xian-Kui , Cravero Sebastian , Ruggieri Claudio
Published: July 2010

The normalization method is adopted in this paper to determine J-R curves for X60 pipeline steel using single-edge notched tension (SENT) specimens. A resistance curve procedure associated with the normalization method is developed to estimate crack extension, calculate crack growth corrected J-integral and generate a J-R curve directly using load-displacement data from a single test on SENT specimens. Based on experimental data for a typical pin-loaded SENT specimen, J-R curve for X60 pipeline steel is obtained by the normalization method and the conventional elastic unloading compliance method. The results show that the normalization method is simple and cost-effective, and can obtain J-R curves equivalent to the unloading compliance method in use of SENT specimens.
Prediction of Radiation Embrittlement for Highly Irradiated Reactor Pressure Vessel Steels
Authors: Matsuzawa Hiroshi
Published: July 2010

There are 53 (fifty-three) nuclear power plants (both PWR and BWR type) are now under operating in Japan, and the oldest plant has been operating more than thirty years. These plants will be operated until sixty years for operation periods, and will be verified the integrity for assessment of nuclear plants for every ten years in Japan. Reactor Pressure Vessels (RPVs) are required to evaluate the reduction of fracture toughness and the increase of the reference temperature in the transition region. As the operating period will be longer, the prediction for these material properties will be more important. Recently the domestic prediction formula of embrittlement was revised based on the database of domestic plant surveillance test results for thirty years olds as the JEAC4201-2007 [7]. The adequacy for this prediction formula using for sixty year periods is verified by use of the results of the material test reactors (MTRs), but the effects of the accelerated irradiation on embrittlement has not been clear now. So, JNES started the national project, called as “PRE” project on 2005 in order to investigate how flux influences on the ΔRTNDT. In this project the RPV materials irradiated in the actual PWR plant have been re-irradiated in the OECD/Halden test reactor by several different fluxes up to the high fluence region, and the microstructual change for these materials will be investigated in order to make clear the cause of the irradiation embrittlement. In this paper the overall scheme of this project and the summary of the updated results will be presented.
Development of Reactive Flow Models for Energetic Materials
Authors: Littlefield David L. , Walls Kenneth C. , Lambert David E.
Published: July 2010

In order to make the process of material model development more systematic for energetic materials, we have developed a procedure that makes use of nonlinear optimization to derive optimal values of parameters in the material models. A framework has been developed that makes use of the optimization software package DAKOTA driving the hydrocode CTH (both CTH and DAKOTA are developed and maintained at Sandia National Laboratories). CTH was used to model a set of characterization experiments that were used as the basis for the calibration of a particular model; for example, the cylinder test was used to calibrate the JWL equation of state, and the wedge test for the HVRB reactive burn model. As a verification test of the framework, we have determined material model constants for TNT and compared them to values published in the literature.
Comparison of Component Fatigue Test Data With Proposed EAF Methodologies for Austenitic Stainless Steel
Authors: Nayal Rim , Charkas Hasan
Published: July 2010

The U.S. Nuclear Regulatory Commission (NRC) currently requires evaluation of the effect of environmental fatigue for both license renewal and new plants. NRC required the use of methodology in EPRI MRP-47, Rev. 1 addressing NUREG/CR-5704, be used for license renewal of stainless steel (SS) components, and NUREG/CR-6909 for use in new plants. These two methodologies are based on applying an environmental correction factor (Fen) on the number of in-air design cycles. These factors are applied to the fatigue usage from each individual range of stress (or range of strain). The focus of this paper is to compare the two aforementioned methodologies; this includes comparison of the fatigue curve as well as the comparison of the environmental correction factors (Fen). Fatigue test results data reported by others are also compared with these two methodologies. It is important to evaluate the impact of using any of those methodologies on the design fatigue life of the components. It is concluded that NUREG/CR-5704 is more severe than NUREG/CR-6909 in the LCF (low-cycle fatigue) regime, while NUREG/CR-6909 is more severe elsewhere, and both NUREG’s extremely underestimate fatigue life in PWR environment. It is also concluded that the current ASME-code fatigue curve for stainless steel reasonably estimates fatigue life in an LWR environment with reasonable margins.
Post Autofrettage Thermal Treatment and Its Effect on Re-Yielding of High Strength Pressure Vessel Steels
Authors: Troiano E. , Underwood J. H. , Parker A. P. , Mossey C.
Published: July 2010

The autofrettage process of a thick walled pressure vessel involves applying tensile plastic strain at the bore of the vessel which reverses during unloading and results in favorable compressive residual stresses at the bore and prolongs the fatigue life of the component. In thick walled pressure vessels this process can be accomplished with either a hydraulic or mechanical overloading process. The Bauschinger effect, which is observed in many of the materials used in thick walled pressure vessels, is a phenomenon which results in lower compressive residual stresses than those predicted with classic ideal isotropic hardening. The phenomenon is a strong function of the amount of prior tensile plastic strain. A novel idea which involves a multiple autofrettage process has been proposed by the present authors. This process requires a low temperature post autofrettage thermal treatment which effectively returns the material to its original yield conditions without affecting its residual stress state. Details of this low temperature thermal treatment are proprietary. A subsequent second autofrettage process generates a significantly lower amount of plastic strain during the tensile re-loading and results in higher compressive residual stresses. This paper reports the details of exploratory tests involving tensile and compressive loading of a test coupon, followed by a low temperature post plastic straining thermal treatment, and subsequent re-loading in tension and compression. Finally results of a full scale Safe Maximum Pressure (SMP) test of pressure vessels are presented; these tests indicate a significant increase (11%) in SMP.
A Study on Safer Operation of Impulsively Loaded Vessels
Authors: Asahina Joseph K. , Kitamura Ryusuke
Published: July 2010

ASME published Code Case 2564 [1] in January 2008 on impulsively loaded vessels, which is the first design guidance of this kind worldwide. The authors participated in the Task Group of Sec. VIII, Div. 3 [2] and were also intimately engaged in development, design and operation of detonation chambers DAVINCH®. DAVINCH® is an acronym for Detonation of Ammunition in Vacuum INtegrated CHamber, utilized for destruction of old non-stockpile chemical weapons, which were recovered from underground and sea in several areas of Japan, China, and Belgium. The quantity destroyed to-date has reached as high as 4,500 items. Figure 1, and 2 show the installations of DV65 at Port Kanda, Japan and DV50 at Poelkapelle, Belgium, with maximum capacity of 65kg and 50 kg TNT-equivalent respectively.
A Comparison of Failure Load Assessment Methods for Thin-Walled Tubes With Cracks
Authors: Kim Hyun Su , Oh Chang Kyun , Jin Tae Eun
Published: July 2010

Heat exchangers in fossil and nuclear power plants comprise thousands of thin-walled tubes. Operational experience shows that cracks have been frequently detected in the tubes. Since the structural integrity of the heat exchangers is crucial from the viewpoint of safety and reliability, the integrity evaluation of the cracked tubes is quite important. The failure modes of the cracked tubes are determined herein in accordance with Section XI of ASME Code. In addition, failure loads are evaluated using various methods and compared with test data in order to determine an optimum estimation method. The analysis results show that the failure mode of the cracked tubes is plastic collapse. Also, the predicted failure loads by finite element limit analyses agree very well with the corresponding test data, whereas the analytical approaches are significantly under predictive depending on the crack type and size. It is, therefore, considered that the finite element limit load approach can be applied to the practical integrity evaluation and the establishment of an optimum inspection strategy for managing the heat exchanger tubes.
Considerations of Alloy 617 Application in the Gen IV Nuclear Reactor Systems: Part II—Metallurgical Property Challenges
Authors: Ren Weiju
Published: July 2010

Alloy 617 is currently considered as a leading candidate material for high temperature components in the Gen IV Nuclear Reactor Systems. Because of the unprecedented severe working conditions beyond its commercial service experience required by the Gen IV systems, the alloy faces various challenges in both mechanical and metallurgical properties. Following a previous paper discussing the mechanical property challenges, this paper is focused on the challenges and issues in metallurgical properties of the alloy for the intended nuclear application. Considerations are given in details about its metallurgical stability and aging evolution, aging effects on mechanical properties, potential Co hazard, and internal oxidation. Some research and development activities are suggested with discussions on viability to satisfy the Gen IV Nuclear Reactor System needs.
In situ direct visualization of irradiated electron-beam patterns on unprocessed resists using atomic force microscopy
Authors: Koop H. , Zech M. , Karrai K. , Schnurbusch D. , Müller M. , Gründl T. , Amann M.-C. , Holleitner A. W.
Published: July 2010

The authors introduce an in situ characterization method of resists used for electron-beam lithography. The technique is based on the application of an atomic force microscope, which is directly mounted below the cathode of an electron-beam lithography system. They demonstrate that patterns irradiated by the electron beam can be efficiently visualized and analyzed in surface topography directly after the electron-beam exposure. This in situ analysis takes place without any development or baking steps and gives access to the chemical (or latent) image of the irradiated resist.
Quantification of Shiga Toxin-Converting Bacteriophages in Wastewater and in Fecal Samples by Real-Time Quantitative PCR
Authors: Imamovic Lejla , Ballesté Elisenda , Jofre Juan , Muniesa Maite
Published: July 2010

Shiga toxin-converting bacteriophages (Stx phages) are involved in the pathogenicity of some enteric bacteria, such as
Escherichia coli
O157:H7. Stx phages are released from their bacterial hosts after lytic induction and remain free in the environment. Samples were analyzed for the presence of free Stx phages by an experimental approach based on the use of real-time quantitative PCR (qPCR), which enables
stx
to be detected in the DNA from the viral fraction of each sample. A total of 150 samples, including urban raw sewage samples, wastewater samples with fecal contamination from cattle, pigs, and poultry, and fecal samples from humans and diverse animals, were used in this study. Stx phages were detected in 70.0% of urban sewage samples (10 to 10
3
gene copies [GC] per ml) and in 94.0% of animal wastewater samples of several origins (10 to 10
10
GC per ml). Eighty-nine percent of cattle fecal samples were positive for Stx phages (10 to 10
5
GC per g of sample), as were 31.8% of other fecal samples of various origins (10 to 10
4
GC per g of sample). The
stx
2
genes and
stx
2
variants were detected in the viral fraction of some of the samples after sequencing of
stx
2
fragments amplified by conventional PCR. The occurrence and abundance of Stx phages in the extraintestinal environment confirm the role of Stx phages as a reservoir of
stx
in the environment.
ArgR-Regulated Genes Are Derepressed in the
Legionella
-Containing Vacuole
Authors: Hovel-Miner Galadriel , Faucher Sebastien P. , Charpentier Xavier , Shuman Howard A.
Published: July 2010

Legionella pneumophila
is an intracellular pathogen that infects protozoa in aquatic environments and when inhaled by susceptible human hosts replicates in alveolar macrophages and can result in the often fatal pneumonia called Legionnaires' disease. The ability of
L. pneumophila
to replicate within host cells requires the establishment of a specialized compartment that evades normal phagolysosome fusion called the
Legionella
-containing vacuole (LCV). Elucidation of the biochemical composition of the LCV and the identification of the regulatory signals sensed during intracellular replication are inherently challenging.
l
-Arginine is a critical nutrient in the metabolism of both prokaryotic and eukaryotic organisms. We showed that the
L. pneumophila
arginine repressor homolog, ArgR, is required for maximal intracellular growth in the unicellular host
Acanthamoeba castellanii
. In this study, we present evidence that the concentration of
l
-arginine in the LCV is sensed by ArgR to produce an intracellular transcriptional response. We characterized the
L. pneumophila
ArgR regulon by global gene expression analysis, identified genes highly affected by ArgR, showed that ArgR repression is dependent upon the presence of
l
-arginine, and demonstrated that ArgR-regulated genes are derepressed during intracellular growth. Additional targets of ArgR that may account for the
argR
mutant's intracellular multiplication defect are discussed. These results suggest that
l
-arginine availability functions as a regulatory signal during
Legionella
intracellular growth.
Identification and Heterologous Expression of Genes Involved in Anaerobic Dissimilatory Phosphite Oxidation by
Desulfotignum phosphitoxidans
Authors: Simeonova Diliana Dancheva , Wilson Marlena Marie , Metcalf William W. , Schink Bernhard
Published: July 2010

Desulfotignum phosphitoxidans
is a strictly anaerobic, Gram-negative bacterium that utilizes phosphite as the sole electron source for homoacetogenic CO
2
reduction or sulfate reduction. A genomic library of
D. phosphitoxidans
, constructed using the fosmid vector pJK050, was screened for clones harboring the genes involved in phosphite oxidation via PCR using primers developed based on the amino acid sequences of phosphite-induced proteins. Sequence analysis of two positive clones revealed a putative operon of seven genes predicted to be involved in phosphite oxidation. Four of these genes (
ptxD-ptdFCG
) were cloned and heterologously expressed in
Desulfotignum balticum
, a related strain that cannot use phosphite as either an electron donor or as a phosphorus source. The
ptxD-ptdFCG
gene cluster was sufficient to confer phosphite uptake and oxidation ability to the
D. balticum
host strain but did not allow use of phosphite as an electron donor for chemolithotrophic growth. Phosphite oxidation activity was measured in cell extracts of
D. balticum
transconjugants, suggesting that all genes required for phosphite oxidation were cloned. Genes of the phosphite gene cluster were assigned putative functions on the basis of sequence analysis and enzyme assays.
A Novel Heme
a
Insertion Factor Gene Cotranscribes with the
Thermus thermophilus
Cytochrome
ba
3
Oxidase Locus
Authors: Werner Carolin , Richter Oliver-Matthias H. , Ludwig Bernd
Published: July 2010

Studying the biogenesis of the
Thermus thermophilus
cytochrome
ba
3
oxidase, we analyze heme
a
cofactor insertion into this membrane protein complex. Only three proteins linked to oxidase maturation have been described for this extreme thermophile, and in particular, no evidence for a canonical Surf1 homologue, required for heme
a
insertion, is available from genome sequence data. Here, we characterize the product of an open reading frame,
cbaX
, in the operon encoding subunits of the
ba
3
-type cytochrome
c
oxidase. CbaX shares no sequence identity with any known oxidase biogenesis factor, and CbaX homologues are found only in the
Thermaceae
group. In a series of
cbaX
deletion and complementation experiments, we demonstrate that the resulting
ba
3
oxidase complexes, affinity purified via an internally inserted His tag located in subunit I, are severely affected in their enzymatic activities and heme compositions in both the low- and high-spin sites. Thus, CbaX displays typical features of a generic Surf1 factor essential for binding and positioning the heme
a
moiety for correct assembly into the protein scaffold of oxidase subunit I.
Proliferative Effects of Chishao on Injured Peripheral Neurons
Authors: Fang Wen-Kuei , Weng Yi-Jiun , Chang Mu-Hsin , Lin Chien-Chung , Chen Yueh-Sheng , Hsu Hsi-Hsien , Tsai Fuu-Jen , Tsai Chang-Hai , Kuo Wu-Hsien , Lu Chung Yen , Huang Chih-Yang
Published: July 2010

The aim of the study was to evaluate the proliferative effects of chishao on neuron regeneration. A silicone rubber nerve guide across a 15-mm gap was filled with different concentrations of chishao (0–125 mg/ml) in the dissected sciatic nerve of the right leg in SD rats. The left legs were used as control. After eight weeks, the regenerated nerves showed dose-dependently activated fibroblast growth factor-2 (FGF-2) signaling with increased urokinase plasminogen activator (uPA), decreased plasminogen activator inhibitor-1 (PAI-1) and enhanced proliferative proteins, extracellular signal regulated kinase (ERK)- and c-Jun N-terminal kinase (JNK)-signalings. The results imply that applying an appropriate dose of chishao would be a potential approach for enhancing neuron regeneration.
Evaluation of Anti-Oxidant Capacity of Root of Scutellaria baicalensis Georgi, in Comparison with Roots of Polygonum multiflorum Thunb and Panax ginseng CA Meyer
Authors: Chan Enoch , Wong Cynthia Ying-Kat , Wan Chun-Wai , Kwok Ching-Yee , Wu Jian-Hong , Ng Kar-Man , So Chi-Hang , Au Alice Lai-Shan , Poon Christina Chui-Wa , Seto Sai-Wang , Kwan Yiu-Wa , Yu Peter Hoi-Fu , Chan Shun-Wan
Published: July 2010

In Chinese communities, regular consumption of Chinese-medicated diets (CMD) (usually in the form of soup) is a traditional practice to promote health and prevent disease development. The overall improvement of health conditions is believed to be correlated with the anti-oxidant potentials of these herbs. Huangqin, roots of Scutellaria baicalensis Georgi (Lamiaceae), is one of the herbs commonly used in CMD. In this study, the anti-oxidant capacities of Huangqin extracts (water, ethanol and ether extracts) were evaluated and compared to commonly used CMD herbs, Heshouwu, roots of Polygonum multiflorum Thunb (Polygonaceae) and Renshen (or Ginseng), roots of Panax ginseng CA Meyer (Araliaceae). The anti-oxidant capacities were measured by using both cell-free assay [ferric reducing/anti-oxidant power (FRAP)] and biological methods [2,2'-azobis–(2-amidinopropane) (AAPH)-induced haemolysis assay and H2O2 -induced cell damage on H9C2 cells]. Additionally, the total phenolic content was measured using Folin-Ciocalteu methods. Water extract of Huangqin has the highest anti-oxidant activities compared to the ethanol and ether extracts. A positive relationship between the anti-oxidant effects and total phenolic contents of extracts was demonstrated. This shows that Huangqin could be an effective dietary anti-oxidant that can be consumed regularly as a functional food for the prevention of oxidant/free radical-related diseases.
NOVEL FCS-BASED LAYOUT-FRIENDLY ACCURATE WIDE-BAND LOW-POWER CCII- REALIZATIONS
Authors: MOSTAFA HASSAN , MOHAMED HEWIDA , SOLIMAN A. M.
Published: July 2010

This paper presents two novel Floating Current Source (FCS)-based CMOS negative second generation current conveyor (CCII-) realizations suitable for very large scale implementation. The proposed realizations provide high voltage and current tracking accuracy, as well as large voltage and current transfer bandwidths. Simulation results show that the first proposed wide-band CCII- bandwidth is about 972 MHz. Targeting low-power dissipation, a second low-power version of the wide-band CCII- is proposed at the expense of lower bandwidth and accuracy. The proposed CCII- realizations are layout-friendly because they can be easily fabricated in a systematic modular layout fashion. In addition, a fair comparison is held between the proposed realizations and the only FCS-based CCII- realizations in the literature to show the strength of the proposed circuits. The proposed two CCII- realizations show excellent immunity to process variations and transistor mismatch. In addition, they are insensitive to the temperature variations. Finally, two common CCII- applications are presented.
CHOOSING BETWEEN DESIGN OPTIONS FOR REAL-TIME COMPUTERS TOLERATING A SINGLE FAULT
Authors: SAMET REFIK
Published: July 2010

This paper proposes a methodology for supporting the design of fault-tolerant computers for real-time applications. To this end, the paper first presents steps of fault tolerance and describes mechanisms that can be used to realize them. Then, the design options consisting of described mechanisms are proposed and a table summarizing them is designed. From that, the paper proposes a flowchart for choosing between the many various design options available for building a redundant computer system. Choosing an optimal design option is performed according to the number of redundant computers, the mode of operation of redundant computers, the computer failure mode and the severity of the real-time constraint. Finally, graphical models for sequencing the mechanisms of design options are proposed. The main merit of the proposed methodology includes a spectrum of design options of fault-tolerant mechanisms for real-time computers tolerating a single fault at a time and a guide for choosing between them.
A NOVEL ADAPTIVE CURRENT BIASED LINEAR RADIO-FREQUENCY POWER AMPLIFIER ON SIGE HBT PROCESS
Authors: WU TUO , CHEN HONGYI , QIAN DAHONG
Published: July 2010

A novel adaptive current biased CLASS-A/shallow AB RF power amplifier is demonstrated in this paper. By theoretical deduction, a prototype is described to improve the linearity of a linear PA. With the realization on Jazz 0.35 μm SiGe HBT process and test verification, the novel adaptive current biased RF power amplifier shows 3 ~ 7 dB improvement of the ACPR at the output power of 19 dBm to meet the demand of CDMA IS95 spectrum mask without debasing the efficiency.