bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-Sample Test of High Dimensional Means Under Dependence
Authors: Tony Cai T. , Liu Weidong , Xia Yin 
Published: August 2013

SummaryThe paper considers in the high dimensional setting a canonical testing problem in multivariate analysis, namely testing the equality of two mean vectors. We introduce a new test statistic that is based on a linear transformation of the data by the precision matrix which incorporates the correlations between the variables. The limiting null distribution of the test statistic and the power of the test are analysed. It is shown that the test is particularly powerful against sparse alternatives and enjoys certain optimality. A simulation study is carried out to examine the numerical performance of the test and to compare it with other tests given in the literature. The results show that the test proposed significantly outperforms those tests in a range of settings.
Canine pyoderma gangrenosum: a case series of two dogs
Authors: Simpson Deborah L. , Burton Gregory G. , Hambrook Lydia E. 
Published: August 2013

BackgroundPyoderma gangrenosum (PG) is a rare disease, which, to the best of the authors' knowledge, has been the subject of only one case report in the peer‐reviewed veterinary literature.Hypothesis/ObjectivesTo describe the history, clinical signs, diagnostic findings and treatment outcome in two cases of canine PG.AnimalsTwo client‐owned dogs presented to a private veterinary referral practice between 2008 and 2010 who received a diagnosis of PG by specialist veterinary dermatologists.MethodsMedical records were analysed to retrieve relevant information.ResultsBoth dogs were treated with prednisolone; this was combined with ciclosporin in case 1 and azathioprine in case 2. Case 2 had a more complete response of lesions to treatment and a longer survival time after diagnosis (763 days) than case 1 (81 days).Conclusions and clinical importancePyoderma gangrenosum is a rare disease distinguished by rapid progression of painful, necrolytic, cutaneous ulcers with irregular, violaceous undermined borders. Azathioprine with glucocorticoids may lead to a better outcome than ciclosporin and glucocorticoids (currently the first‐line treatment in humans and the only reported treatment in dogs).
Factors influencing selection of drinking water technologies for urban informal settlements in Kampala
Authors: Isoke Jennifer , van Dijk Meine Pieter 
Published: August 2013

AbstractAccess to drinking water in urban informal settlements of developing countries still remains a challenge for the poor and depends on technology selected. This paper determines the score on criteria used for technology selection by two major stakeholders in the water service delivery chain, the users and the utility. The criteria are: affordability to connect, affordability of consumption, method of payment, ease of operation, ease of spare parts acquisition, access distance, access time, generating sufficient water continuously, service coverage, the possibility of cost recovery and security of installation (SOI). The study was carried out in Bwaise II and Kisenyi III, two informal settlements in Kampala, the capital of Uganda. Through a household survey and semistructured interviews of key informants, data were collected for the score on these criteria of four piped water distribution technologies: public water points (PWPs) with conventional meters, PWPs with prepaid meters, house connections and yard taps. Using multicriteria methods and preference elicitation by pair wise ranking, the most preferred factor for technology selection from the users' point of view is affordability to connect, while from the utility's point of view, it is SOI. These preferences were confirmed by data from focus group discussions and in‐depth interviews.
Application of a drainage film reduces fibroblast ingrowth into large‐pored polyurethane foam during negative‐pressure wound therapy in an in vitro model
Authors: Wiegand Cornelia , Springer Steffen , Abel Martin , Wesarg Falko , Ruth Peter , Hipler Uta‐Christina 
Published: August 2013

AbstractNegative‐pressure wound therapy (NPWT) is an advantageous treatment option in wound management to promote healing and reduce the risk of complications. NPWT is mainly carried out using open‐cell polyurethane (PU) foams that stimulate granulation tissue formation. However, growth of wound bed tissue into foam material, leading to disruption of newly formed tissue upon dressing removal, has been observed. Consequently, it would be of clinical interest to preserve the positive effects of open‐cell PU foams while avoiding cellular ingrowth. The study presented analyzed effects of NPWT using large‐pored PU foam, fine‐pored PU foam, and the combination of large‐pored foam with drainage film on human dermal fibroblasts grown in a collagen matrix. The results showed no difference between the dressings in stimulating cellular migration during NPWT. However, when NPWT was applied using a large‐pored PU foam, the fibroblasts continued to migrate into the dressing. This led to significant breaches in the cell layers upon removal of the samples after vacuum treatment. In contrast, cell migration stopped at the collagen matrix edge when fine‐pored PU foam was used, as well as with the combination of PU foam and drainage film. In conclusion, placing a drainage film between collagen matrix and the large‐pored PU foam dressing reduced the ingrowth of cells into the foam significantly. Moreover, positive effects on cellular migration were not affected, and the effect of the foam on tissue surface roughness in vitro was also reduced.
Study on the Seismic Response of High-Speed Rotational Disk-Shaft System
Authors: Ito Tomohiro , Hatta Masayoshi , Shintani Atsuhiko , Nakagawa Chihiro 
Published: August 2013

Recently, huge earthquakes occurred in the world, such as Great East Japan Earthquake in Japan or huge earthquake in New Zealand in 2011. In Niigata-ken Chuetsuoki earthquake in 2007, turbine blade collisions with the casing were found. Therefore, it is very important to clarify the seismic response behaviors of the high-speed rotational shaft like turbine shafts, because high-speed rotation will cause characteristic dynamic effects, such as gyro moment.
In this study, seismic responses of a disk-shaft system are evaluated analytically. The disk-shaft system is treated as an elastic shaft with a rigid disk. In this analysis, gyroscopic effects of a rotating disk are also considered. Equations of motion are derived for the translational and rotational motions when the system is subjected to both horizontal and vertical seismic excitations. Response behaviors of a rotating disk-shaft system are evaluated for sinusoidal excitations and seismic wave excitations. In the sinusoidal excitations, excitation frequencies and rotational speed are varied, and in the seismic wave excitations, seismic responses are evaluated for the waves with various predominant frequencies.
Large Vessel Nozzle Penetration Geometric Optimisation Study in 3D Incorporating Design of Experiments Techniques
Authors: Towse Adam , Martin Michael , Allen Adrian , Andrews Chris 
Published: August 2013

This paper describes the results of an optimisation study into the effects of changing geometrical variables local to the nozzle entry on a large pressure vessel. The purpose of the study was to quantify the effects of altering the geometry, and thereby provide trade-offs between key responses such as primary strength and shakedown performance.
A 3D Finite Element model was built of a 90 degree sector of the pressure vessel which was sufficiently detailed to allow the thermal and structural effects of the vessel remote from the nozzle to be included. Specifically, this included the thermal and structural influence of the closure head and bolting assembly. The model was then parameterised for 5 independent variables, including the extent of the nozzle reinforcement, crotch corner fillet radius and nozzle thickness. The parameterised model was then subjected to a number of thermal and structural transient analyses during Level A operation, as well as a representative strength loadcase.
A full factorial design study was undertaken, comprising of separate 243 analysis runs covering the 5 independent variables at 3 levels. A number of output metrics were monitored, and the effects on the output metrics resulting from changes to the inputs were quantified. Due to the full factorial nature of the experimental design, interactions between variables could also be investigated.
The response for each output metric was then fitted to a response surface, which allows a polynomial (meta-model) of each metric to be calculated. These responses were input to a simple Excel chart which allows the designers to perform rapid what-if design scenarios, and see the resulting effects of their changes on the responses. This allows the trade-offs between responses, for example shakedown and strength trade-off for shell thickness, to be easily seen and quantified.
Residual Stress Predictions on a 29″ Narrow Gap Dissimilar Metal Weld and Comparison With a 14″ Configuration
Authors: Courtin Stéphan , Ficquet Xavier , Lê Thi Thuy Trang , Gilles Philippe , Yescas Miguel 
Published: August 2013

AREVA has developed narrow gap weld techniques to perform junctions between low alloy steel heavy section components and austenitic stainless steel piping systems. In parallel, for a good understanding of welding and post weld heat treatment consequences, numerical welding simulation has already demonstrated its relevance to predict residual stress fields in welded components [1].
This paper presents Finite Element (FE) simulations of a 29″ multipass narrow gap Dissimilar Metal Weld (DMW) configuration, the welding simulation including non linear kinematic hardening models, phase transformations and visco-plastic calculations for reproducing the post weld heat treatment.
The numerical results are compared to measurements obtained by the deep hole drilling technique [2]. This work gives another evidence of the relevance of the numerical welding simulation. Particularly, the comparison with a 14″ configuration [3] gives some elements to assess on the validity of both numerical and experimental techniques and on the weld thickness effect.
Prediction of Lower Bound Fracture Toughness in the Transition Temperature Region by T33-Stress
Authors: Lu Kai , Meshii Toshiyuki 
Published: August 2013

It is well known that the fracture toughness Jc in the ductile-to-brittle transition temperature region depends highly on the specimen thickness (hereafter, TST). The TST effect on Jc, which Wallin [1] described as Jc (∝ KJc2) ∝ B(-1/2) (Jc was calculated from the equations outlined in ASTM E1820 [2], KJc was derived from Jc as KJc = (Jc·E′)1/2; E′ = E/(1−ν2), B: TST), has been reproduced by Anderson et al. [3] based on the weakest link model. However, as Anderson et al. [3] themselves admit, Jc does not decrease indefinitely with B. On the other hand, Meshii et al. [4–6] tried to explain this TST effect on Jc as a mechanical issue. They obtained the same relationship, Jc ∝ B(-1/2) from the fracture toughness test for a non-standard CT and 3PB specimen (non-standard on the point that planar configuration was identical and thickness to width ratio B/W was varied from 0.25 to 0.5) and the stress intensity factor (SIF) corresponding to fracture load Pc denoted as Kc (Kc was calculated from the equations outlined in ASTM E399 [7]), was almost constant for TST. They also reproduced the experimental tendency by large strain FEA under the assumption based on their experimental observation that Kc was independent of TST. In addition, they expressed the TST effect on Jc by correlating Jc with the out-of-plane elastic T-stress T33.
We thought that if TST effect on Jc is a mechanical issue, the lower bound Jc for TST could be predicted by FEA under some assumption such as Kc = constant for TST, and the TST corresponding to the lower bound Jc could be predicted by T33. However, before proceeding to this prediction, we thought we have to understand the candidate assumption for prediction more deeply, i.e, understand why Kc was constant for TST.
Thus in this work, we attempted to explain the reason why Kc was constant for TST. Our idea was to apply the well-known “planar” failure criterion to our out-of-plane TST issue. After demonstrating our idea was valid, the lower bound Jc of carbon S55C for non-standard 3PB specimen was predicted based on this planar failure criterion and the large strain elastic-plastic FEA. The results showed that Jc showed a lower bound for specimen of B/W ≥ 1.5. In addition, it was shown that this threshold B/W could be estimated by the elastic out-of-plane T33.
Consideration of Environmentally Assisted Fatigue in Austenitic Stainless Steel: Calculation and Practical Application
Authors: Reese Sven H. , Seichter Johannes , Klucke Dietmar 
Published: August 2013

The influence of LWR coolant environment to the lifetime of materials has been discussed recent years. Nowadays the consideration of environmentally assisted fatigue is under consideration in Codes and Standards like ASME and the German KTA Rules (e.g. Standard No. 3201.2 and Standard No. 3201.4) by means of so called attention thresholds. Basic calculation procedures in terms of quantifying the influence of LWR coolant environment by the Fen correction factor were proposed by Higuchi and others and are given in NUREG/CR-6909.
This paper deals with the application of the proposed assessment procedures of ANL and the application to plant conditions. Therefore conservative assessment procedures are introduced without assuming the knowledge of detailed stress and strain calculations or temperature transients. Additionally, detailed assessment procedures based on Finite-Element calculations, respecting in-service temperature measurements including thermal reference transients and complex operational loading conditions are carried out. Fatigue evaluation of a PWR primary circuit component is used in order to evaluate the influence of plant like conditions numerically.
Conclusions regarding the practical application are drawn by means of comparing the ANL approach considering laboratory conditions, conservative assessment procedures for the determination of cumulative fatigue usage factors of plant components and detailed assessment procedures. Plant like loading conditions, complex component geometries, loading scenarios and reference temperature transients shall be taken into account. Practical issues like the determination of the mean temperature or the strain rate have to be considered adequately.
Evaluation of Cumulative Damage From Drop to Puncture Conditions
Authors: Choi Woo-Seok , Lee Sanghoon , Bang Kyoung-Sik , Lee Ju-Chan , Seo Ki-Seog 
Published: August 2013

During safety assessments of transport packages, cumulative damages are naturally accumulated for assessments performed using physical tests specimens. However, the cumulative damages are not as easily accounted when assessments are by numerical simulations. While analysts are comfortable with simulating packages for single events, it is not yet common practice to incorporate the effect handed over from a former event to the next, in a series of sequential load events. Thus, many numerical simulations in SAR (Safety Analysis Report) represent just a single event in the series of sequential event comprising the required accident condition. These single event numerical simulations are then based on initial conditions different from the analogous physical test specimen, which could contribute to a growing disparity in results between assessments by physically testing compared to numerical simulation. The reason why analyses do not consider the cumulative damage is difficulties in delivering the final result of the previous analysis to the current analysis.
The hypothetical accident conditions described in the IAEA regulations include drop, puncture, fire, and water immersion conditions, which should be sequentially simulated. There can be cumulative damage between two accident conditions, such as drop and puncture, puncture and fire, and so forth. In this study, as the first step to consider cumulative damage, an analysis technology to perform a puncture analysis incorporating the final response field from a prior drop analysis is proposed. The necessity and validity of the proposed analysis technology are evaluated by a comparison with the results obtained by performing each analysis independently.
The Effect of Ovality and Thickness Variations on Stress Analysis of Tube Bends Under Internal Pressure
Authors: Chen Yu , Parker Jonathan 
Published: August 2013

Corrosion fatigue damage has resulted in the catastrophic failure of several riser and supply tubes in fossil boilers operating under sub-critical conditions. Most of the damage has been found on the neutral axis of tube bends and the damage mechanism was identified as corrosion fatigue. Significant stress concentrations will always be found associated with high tube ovality and significant thickness variations.
The purpose of this study is to demonstrate the effect tube bend geometry on the stress distributions developed due to the internal pressure. The work was performed to consider how the stresses present in tube bends vary with ovality and thickness variations (thinning/thickening). Ovality and thickness variations in tube bends, which are generally introduced during the bending process, were modeled into the three-dimensional finite element models (FEM). The finite element models considered five different degrees of ovalization of the cross-section at the center of the bend. For each model the maximum principal stress values and distribution of stresses within tube bends were evaluated. The finite element analysis (FEA) predictions were compared with the actual locations of corrosion damage on the tube bend and reasonably predicted where cracks should be expected to initiate and propagate, and where cracks should not be anticipated.
Hot Isostatically Pressed (HIPed) Large Bore Valves for a Pressurised Water Reactor (PWR) Application
Authors: Sulley John , Bohan Michael 
Published: August 2013

This paper presents an overview of the work undertaken by Rolls-Royce to introduce Hot Isostatically Pressed (HIP) large bore valve, 304 stainless steel, pressure boundaries into Pressurised Water Reactor (PWR) plant. It presents the work from a design justification/manufacturing quality assurance perspective, rather than from a pure metallurgical perspective.
Although the HIP process is not new, it was new in its application to Rolls-Royce designed nuclear reactor plant. As a consequence, Rolls-Royce has implemented an evolving, staged approach, starting with HIP bonding of solid valve seats into small bore valve pressure boundaries. This was followed by powder HIP consolidation of leak-limited, thin-walled toroids, and has culminated in the powder HIP consolidation of thick-walled components, such as large bore valves. The paper provides an overview of each of these stages, the method of manufacture for the valve pressure boundary components, and the approach taken with respect to justification.
Mechanical testing results of prolongations taken from a valve body and valve operating cylinder are presented. A range of test results is provided covering, as examples: tensile, charpy, and cantilever fatigue endurance tests.
The paper describes the benefits that Rolls-Royce has realised so far through the introduction of HIPed components. Structural integrity benefits are described, such as improved grain structure, mechanical properties, and ultrasonic inspection. Project-based benefits are also described, such as provision of an alternative strategic sourcing route, cost and lead-time reductions.
The paper details the quality assurance steps Rolls-Royce specify in order to provide HIPed products that meet the necessary quality requirements for application in a PWR environment.
On the Development of a New Bolt Spacing Formula
Authors: Do Tan Dan , Bouzid Abdel-Hakim , Dao Thien-My 
Published: August 2013

Bolted flange joints are extensively used to connect pressure vessels and piping equipment together. They are simple structures that offer the possibility of disassembly. However, they often experience leakage problems due to a loss of tightness as a result of a non-uniform distribution of gasket contact stresses in the radial and circumferential direction. Many factors contribute to such a failure; the flange and gasket stiffness and bolt spacing design combinations being a couple of them.
In our recent papers the effects of bolt spacing was investigated based on the theory of circular beams resting on a linear elastic foundation and based on the theory of ring on non-linear elastic foundation. The variations of the contact stress between bolts were of a concern. This paper is an extension of the work in which an analytical solution based on the theory of circular beams resting on a linear elastic foundation has been developed to determine flange bolt spacing. The relationship between bolt spacing, gasket compression modulus and flange thickness is deduced from an analysis that considers a maximum tolerated gasket contact stress difference between any two bolts.
Supplemental Stress and Fracture Mechanics Analyses of Pressurized Water Reactor Pressure Vessel Nozzles
Authors: Walter Matthew , Yin Shengjun , Stevens Gary L. , Sommerville Daniel , Palm Nathan , Heinecke Carol 
Published: August 2013

In past years, the authors have undertaken various studies of nozzles in both boiling water reactors (BWRs) and pressurized water reactors (PWRs) located in the reactor pressure vessel (RPV) adjacent to the core beltline region. Those studies described stress and fracture mechanics analyses performed to assess various RPV nozzle geometries, which were selected based on their proximity to the core beltline region, i.e., those nozzle configurations that are located close enough to the core region such that they may receive sufficient fluence prior to end-of-life (EOL) to require evaluation of embrittlement as part of the RPV analyses associated with pressure-temperature (P-T) limits. In this paper, additional stress and fracture analyses are summarized that were performed for additional PWR nozzles with the following objectives:
• To expand the population of PWR nozzle configurations evaluated, which was limited in the previous work to just two nozzles (one inlet and one outlet nozzle).
• To model and understand differences in stress results obtained for an internal pressure load case using a two-dimensional (2-D) axi-symmetric finite element model (FEM) vs. a three-dimensional (3-D) FEM for these PWR nozzles. In particular, the ovalization (stress concentration) effect of two intersecting cylinders, which is typical of RPV nozzle configurations, was investigated.
• To investigate the applicability of previously recommended linear elastic fracture mechanics (LEFM) hand solutions for calculating the Mode I stress intensity factor for a postulated nozzle corner crack for pressure loading for these PWR nozzles.
These analyses were performed to further expand earlier work completed to support potential revision and refinement of Title 10 to the U.S. Code of Federal Regulations (CFR), Part 50, Appendix G, “Fracture Toughness Requirements,” and are intended to supplement similar evaluation of nozzles presented at the 2008, 2009, and 2011 Pressure Vessels and Piping (PVP) Conferences. This work is also relevant to the ongoing efforts of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code, Section XI, Working Group on Operating Plant Criteria (WGOPC) efforts to incorporate nozzle fracture mechanics solutions into a revision to ASME B&PV Code, Section XI, Nonmandatory Appendix G.