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Sample records for tightly closed flaws

  1. The detection of tightly closed flaws by nondestructive testing (NDT) methods. [fatigue crack formation in aluminum alloy test specimens

    Science.gov (United States)

    Rummel, W. D.; Rathke, R. A.; Todd, P. H., Jr.; Mullen, S. J.

    1975-01-01

    Liquid penetrant, ultrasonic, eddy current and X-radiographic techniques were optimized and applied to the evaluation of 2219-T87 aluminum alloy test specimens in integrally stiffened panel, and weld panel configurations. Fatigue cracks in integrally stiffened panels, lack-of-fusion in weld panels, and fatigue cracks in weld panels were the flaw types used for evaluation. A 2319 aluminum alloy weld filler rod was used for all welding to produce the test specimens. Forty seven integrally stiffened panels containing a total of 146 fatigue cracks, ninety three lack-of-penetration (LOP) specimens containing a total of 239 LOP flaws, and one-hundred seventeen welded specimens containing a total of 293 fatigue cracks were evaluated. Nondestructive test detection reliability enhancement was evaluated during separate inspection sequences in the specimens in the 'as-machined or as-welded', post etched and post proof loaded conditions. Results of the nondestructive test evaluations were compared to the actual flaw size obtained by measurement of the fracture specimens after completing all inspection sequences. Inspection data were then analyzed to provide a statistical basis for determining the flaw detection reliability.

  2. Detection of tightly closed flaws by nondestructive testing (NDT) methods in steel and titanium

    Science.gov (United States)

    Rummel, W. D.; Rathke, R. A.; Todd, P. H., Jr.; Tedrow, T. L.; Mullen, S. J.

    1976-01-01

    X-radiographic, liquid penetrant, ultrasonic, eddy current and magnetic particle testing techniques were optimized and applied to the evaluation of 4340 steel (180 KSI-UTS) and 6Al-4V titanium (STA) alloy specimens. Sixty steel specimens containing a total of 176 fatigue cracks and 60 titanium specimens containing a total of 135 fatigue cracks were evaluated. The cracks ranged in length from .043 cm (0.017 inch) to 1.02 cm (.400 inch) and in depth from .005 cm (.002 inch) to .239 cm (.094 inch) for steel specimens. Lengths ranged from .048 cm (0.019 inch) to 1.03 cm (.407 inch) and depths from 0.010 cm (.004 inch) to .261 cm (0.103 inch) for titanium specimens. Specimen thicknesses were nominally .152 cm (0.060 inch) and 0.635 cm (0.250 inch) and surface finishes were nominally 125 rms. Specimens were evaluated in the "as machined" surface condition, after etch surface and after proof loading in a randomized inspection sequence.

  3. Evaluating different closed loop graft preparation technique for tibial suspensory fixation in ACL reconstruction using TightRope™

    Directory of Open Access Journals (Sweden)

    Takahisa Sasho

    2018-04-01

    Full Text Available In most anterior cruciate ligament (ACL reconstructions, grafts are fixed to the femoral side first followed by the tibial side. Various techniques have been reported to achieve optimal tension on the grafts, but once the grafts are fixed it is difficult to adjust graft tension further. To enable post fixation tension control we have invented a new graft configuration using an adjustable loop-device (TightRopeTM, Arthrex, FL, USA on the tibial side. In this paper, biomechanical properties of this configuration using soft tissue were examined in terms of graft diameter and various suture techniques (referred to as base suture to make a closed circle to support TightRopeTM.Two experiments were conducted under different conditions. In each experiment, cyclic load, followed by a pull-to-failure load, was applied to the grafts and elongation and failure mode were recorded. (1 To evaluate the effects of diameter, 5.0 or 6.0 mm grafts were prepared by a single locking loop stitch as the base suture (SLL5, SLL6. (2 To evaluate different base sutures, 5.0 mm tendons were used, and grafts were prepared using five kinds of base sutures (SLL, ZLL: zigzag locking loop, DZLL: double zigzag locking loop, DK: double Krackow, DK w/o TR: double Krackow without TightRopeTM. In the first experiment, tearing was observed in 2 of 6 cases in the SLL5 test group, whereas no tearing was observed with SLL6. In the second experiment, no tearing was observed with DZLL or DK. Elongation was smaller in these two groups compared to the other groups. Mechanical strength decreases with a smaller graft diameter. Biomechanical properties differed with different base sutures and, among them, the double-zigzag-suture stitch and double Krackow provided less elongation and higher ultimate load in this graft configuration.

  4. Flaw detection device

    International Nuclear Information System (INIS)

    Sasahara, Toshihiko

    1998-01-01

    The present invention provides a device for detecting welded portions of a reactor pressure vessel. Namely, the device of the present invention comprises (1) a casing to be disposed on the surface to be detected, (2) a probe driving means loaded to the casing, (3) a probe driven along the surface to be detected and (4) a pressure reduction means for keeping the hollow portion in the casing to an evacuated atmosphere. The casing comprises a flexible suction edge to be tightly in contact with the surface to be tested for maintaining the air tight state, (6) a guide wheel for moving the casing along the surface to be tested and (7) a handle for performing transferring operation. The flaw detection device thus constituted has following features. The working efficiency upon conducting detection is improved. The influence of the weight of the device on the detection is small. The device can be applied on the surface of a nonmagnetic material. The efficiency for the flaw detection can be improved. (I.S.)

  5. Component flaw evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, K [Babcock and Wilcox Co., Lynchburg, VA (United States). Nuclear Power Div.

    1988-12-31

    This document deals with flaw evaluation during in-service inspection. These flaws can be divided into two groups: defects originating from the manufacturing fabrication stage or service-induced flaws. These are mainly caused by high cycle thermal fatigue and are influenced by the presence of stress corrosion cracking mechanisms such as nozzles or pump shaft. (TEC).

  6. Currency flaw severity. [Banknotes

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C.; Burnett, M.; Goodman, C.; Sherrod, R.; Schmoyer, R.; Harrison, C.; Uppuluri, R.

    1986-01-01

    A survey of currency flaw severity was carried out using 300 banknotes and 37 judges. Each judge assigned each note to one of five flaw severity categories. These categories correspond to severity grades of 1 to 5 with 1 equivalent to ''always accepted'' and 5 ''never accepted.'' An average flaw severity grade for each note was obtained by taking the mean of the severity grades assigned to that note by the 37 judges. Thus, each note has a single numerical real-number flaw grade between 1 and 5. Mathematical modeling of the currency flaw survey results is continuing with some very promising initial results. Our present model handles common excess ink and missing ink flaw types quite well. We plan to extend the model to ink level, mash, setoff and blanket impression flaw types.

  7. Flaw evaluation charts

    International Nuclear Information System (INIS)

    Korosec, D.; Vojvodic Tuma, J.

    1999-01-01

    The structural integrity of the primary components in pressurized water reactor nuclear power plant is very important in the respect of safe and efficient operation. These components have to be subjected to periodic controls. In the light of fracture mechanics concept, the acceptance criteria for defects (flaws) are developed. Flaw evaluation procedure is necessary, to evaluate the defects regarding their acceptability for further operation. The objective of the flaw evaluation charts is to provide a series of simple graphs as decision maps. that immediate decision may be taken regarding the acceptability of a detected defects, on the basis of ASME Code XI criteria.(author)

  8. Tight turns

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    The Italian National Institute for Nuclear Physics (INFN) has successfully tested the first model of a new fast-ramping curved dipole magnet. This is great news for CERN, which sees the advance as holding potential for the future of the SPS.   The first model of a new fast-ramping curved dipole magnet being prepared for cryogenic testing at the LASA laboratory (INFN Milano, Italy). On 16 July INFN introduced an innovative dipole magnet. With a length of some 4 metres, it can produce a 4.5 Tesla magnetic field and achieve a tighter bend than ever before (the bending radius has been squeezed to a remarkable 66.7 metres). This new magnet was designed in the first instance for GSI’s SIS300 synchrotron (in Germany), which will require 60 dipoles of this type. "Achieving such a tight bend demanded a major R&D effort," stressed Pasquale Fabbricatore, the spokesman of the INFN collaboration responsible for the magnet’s development. "We had to not o...

  9. Detecting flaws in welds

    International Nuclear Information System (INIS)

    Woodacre, A.; Lawton, H.

    1979-01-01

    An apparatus and a method for detecting flaws in welds in a workpiece, the portion of the workpiece containing the weld is maintained at a constant temperature and the weld is scanned by an infra red detector. The weld is then scanned again with the workpiece in contact with a cooling probe to produce a steeper temperature gradient across the weld. Comparison of the signals produced by each scan reveals the existence of defects in the welds. The signals may be displayed on an oscilloscope and the display may be observed by a TV camera and recorded on videotape. (UK)

  10. Flaws in Commercial Reading Materials.

    Science.gov (United States)

    Axelrod, Jerome

    Three flaws found in commercial reading materials, such as workbooks and kits, are discussed in this paper, and examples of the flaws are taken from specific materials. The first problem noted is that illustrations frequently provide the information that the learner is supposed to supply through phonetic or structural analysis; the illustrations…

  11. Tight closure and vanishing theorems

    International Nuclear Information System (INIS)

    Smith, K.E.

    2001-01-01

    applications of tight closure include Frobenius characterizations of certain singularities arising in the minimal model program and uniform bounds for global generation of adjoint linear series. Both of these applications are closely tied to vanishing theorems, and indeed, the Kodaira vanishing theorem itself has an equivalent formulation in terms of tight closure

  12. Statistical flaw detection: Application to flaws below curved surfaces

    International Nuclear Information System (INIS)

    Elsley, R.K.; Fertig, K.W.; Linebarger, R.S.; Richardson, J.M.

    1984-01-01

    This chapter presents a practical approach to the optimum detection of flaws in the presence of noise signals. A decision theoretic approach is used to derive a detection algorithm which is adapted to the noise environment in which a particular measurement is being made. An automatic procedure for characterizing the noises and developing the optimum detection algorithm is presented. The proposed method makes use of an explicit knowledge of the noise processes in order to design a flaw detection algorithm which optimally detects flaws in the presence of such noise. It is concluded that this approach will provide a number of advantages in practical testing situations, including the detection of smaller flaws, faster scanning due to the use of less highly focussed transducers, and less need for operator optimization of the measurement process. The described algorithms were implemented on the Digital Ultrasonic Instrument (DUI), which is a high speed all-digital instrument for performing sophisticated calculations on ultrasonic signals

  13. Determination of Flaw Size from Thermographic Data

    Science.gov (United States)

    Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

    2014-01-01

    Conventional methods for reducing the pulsed thermographic responses of delaminations tend to overestimate the size of the flaw. Since the heat diffuses in the plane parallel to the surface, the resulting temperature profile over the flaw is larger than the flaw. A variational method is presented for reducing the thermographic data to produce an estimated size for the flaw that is much closer to the true size of the flaw. The size is determined from the spatial thermal response of the exterior surface above the flaw and a constraint on the length of the contour surrounding the flaw. The technique is applied to experimental data acquired on a flat bottom hole composite specimen.

  14. PWR vessel flaw distribution development

    International Nuclear Information System (INIS)

    Rosinski, S.T.; Kennedy, E.L.; Foulds, J.R.; Kinsman, K.M.

    1990-01-01

    This paper reports on PWR pressure vessels which operate under NRC rules and regulatory guides intended to prevent failure of the vessels. Plants failing to meet the operating criteria specified under these rules and regulations are required to analytically demonstrate fitness for service in order to continue operation. The initial flaw size or distribution of initial vessel flaws is a key input to the required vessel integrity analyses. However, the flaw distribution assumed in the development of the NRC Regulations and recommended for the plant specific analyses is potentially over-conservative. This is because the distribution is based on the limited amount of vessel inspection data available at the time the criteria were being developed and does not take full advantage of the more recent and reliable domestic vessel inspection results. The U.S. Department of Energy is funding an effort through Sandia National Laboratories to investigate the possibility of developing a new flaw distribution based on the increased amount and improved reliability of domestic vessel inspection data. Results of Phase I of the program indicate that state-of-the-art NDE systems' capabilities are sufficient for development of a new flaw distribution that could ultimately provide life extension benefits over the presently required operating practice

  15. Flaw identification using acoustic emission

    International Nuclear Information System (INIS)

    Woodward, B.; McDonald, N.R.

    1975-01-01

    Acoustic emission 'signatures' contain information about the fine structure of metallurgical source events and their interpretation may provide a means of assessing the severity of internal flaws as well as surface flaws. The ultimate aim of this research on signature analysis is to develop a real time non-destructive testing technique having the capability of flaw recognition as well as flaw location in nuclear reactor components and structures under stress. Thus the requisite, unlike that in most acoustic emission work to date, is for a technique which affords discrimination between acoustic emission from different types of flaws propagating simultaneously. The approach described here requires detailed analysis of the emission signatures in terms of a specific statistical parameter, energy spectral density. In order to realise the full inspection potential of acoustic emission monitoring data obtained from zirconium and steel testpieces have been correlated with metallurgical condition and mechanical behaviour, since the nature of emission signatures is strongly affected by the physical characteristics and internal structure of the material. (Auth.)

  16. Methods to establish flaw tolerances

    International Nuclear Information System (INIS)

    Varga, T.

    1978-01-01

    Three conventional methods used to establish flaw tolerances are compared with new approaches using fracture mechanics. The conventional methods are those based on (a) non-destructive testing methods; (b) fabrication and quality assurance experience; and (c) service and damage experience. Pre-requisites of fracture mechanics methods are outlined, and summaries given of linear elastic mechanics (LEFM) and elastoplastic fracture mechanics (EPFM). The latter includes discussion of C.O.D.(crack opening displacement), the J-integral and equivalent energy. Proposals are made for establishing flaw tolerances. (U.K.)

  17. Prime tight frames

    DEFF Research Database (Denmark)

    Lemvig, Jakob; Miller, Christopher; Okoudjou, Kasso A.

    2014-01-01

    to suggest effective analysis and synthesis computation strategies for such frames. Finally, we describe all prime frames constructed from the spectral tetris method, and, as a byproduct, we obtain a characterization of when the spectral tetris construction works for redundancies below two.......We introduce a class of finite tight frames called prime tight frames and prove some of their elementary properties. In particular, we show that any finite tight frame can be written as a union of prime tight frames. We then characterize all prime harmonic tight frames and use thischaracterization...

  18. Design flaw could delay collider

    CERN Multimedia

    Cho, Adrian

    2007-01-01

    "A magnet for the Large Hadron Collider (LHC) failed during a key test at the European particle physics laboratory CERN last week. Physicists and engineers will have to repair the damaged magnet and retrofit others to correct the underlynig design flaw, which could delay the start-up of the mammouth subterranean machine." (1,5 page)

  19. Detector-device-independent quantum secret sharing with source flaws.

    Science.gov (United States)

    Yang, Xiuqing; Wei, Kejin; Ma, Haiqiang; Liu, Hongwei; Yin, Zhenqiang; Cao, Zhu; Wu, Lingan

    2018-04-10

    Measurement-device-independent entanglement witness (MDI-EW) plays an important role for detecting entanglement with untrusted measurement device. We present a double blinding-attack on a quantum secret sharing (QSS) protocol based on GHZ state. Using the MDI-EW method, we propose a QSS protocol against all detector side-channels. We allow source flaws in practical QSS system, so that Charlie can securely distribute a key between the two agents Alice and Bob over long distances. Our protocol provides condition on the extracted key rate for the secret against both external eavesdropper and arbitrary dishonest participants. A tight bound for collective attacks can provide good bounds on the practical QSS with source flaws. Then we show through numerical simulations that using single-photon source a secure QSS over 136 km can be achieved.

  20. Finite-element analysis of flawed and unflawed pipe tests

    International Nuclear Information System (INIS)

    James, R.J.; Nickell, R.E.; Sullaway, M.F.

    1989-12-01

    Contemporary versions of the general purpose, nonlinear finite element program ABAQUS have been used in structural response verification exercises on flawed and unflawed austenitic stainless steel and ferritic steel piping. Among the topics examined, through comparison between ABAQUS calculations and test results, were: (1) the effect of using variations in the stress-strain relationship from the test article material on the calculated response; (2) the convergence properties of various finite element representations of the pipe geometry, using shell, beam and continuum models; (3) the effect of test system compliance; and (4) the validity of ABAQUS J-integral routines for flawed pipe evaluations. The study was culminated by the development and demonstration of a ''macroelement'' representation for the flawed pipe section. The macroelement can be inserted into an existing piping system model, in order to accurately treat the crack-opening and crack-closing static and dynamic response. 11 refs., 20 figs., 1 tab

  1. RID-41 gamma flaw detector

    International Nuclear Information System (INIS)

    Glebov, V.N.; Zubkov, V.S.; Majorov, A.N.; Murashev, A.I.; Firstov, V.G.; Yampol'skij, V.V.; Goncharov, V.I.; Sakhanov, A.S.

    1978-01-01

    The design is described and the main characteristics are given of a universal stationary hose-type gamma flow detector with a 60 Co source from 3O to 4g0 Ci for high-productive control of thick-walled products from steel and other materials. The principal units of the instrument are a radiation head, a control panel, and a charge-exchange container. The flaw detector may be used both in shield chambers and in shop or mounting conditions on complying with due requirements of radiation protection. The high activity of the source at relatively small dimensions of its active part ensures good detection of defects. The high radioscopy rate permits to use the flaw detector in conditions of increased background radiation, e.g. during routine repairs and inspections at nuclear power plants. The instrument may also be used in radiometric complexes, and produces a considerable economic effect. This flaw-detector corresponds to ISO and IAEA requirements and may be delivered for export

  2. Flaw shape reconstruction – an experimental approach

    Directory of Open Access Journals (Sweden)

    Marilena STANCULESCU

    2009-05-01

    Full Text Available Flaws can be classified as acceptable and unacceptable flaws. As a result of nondestructive testing, one takes de decision Admit/Reject regarding the tested product related to some acceptability criteria. In order to take the right decision, one should know the shape and the dimension of the flaw. On the other hand, the flaws considered to be acceptable, develop in time, such that they can become unacceptable. In this case, the knowledge of the shape and dimension of the flaw allows determining the product time life. For interior flaw shape reconstruction the best procedure is the use of difference static magnetic field. We have a stationary magnetic field problem, but we face the problem given by the nonlinear media. This paper presents the results of the experimental work for control specimen with and without flaw.

  3. Eddy Current Flaw Characterization Using Neural Networks

    International Nuclear Information System (INIS)

    Song, S. J.; Park, H. J.; Shin, Y. K.

    1998-01-01

    Determination of location, shape and size of a flaw from its eddy current testing signal is one of the fundamental issues in eddy current nondestructive evaluation of steam generator tubes. Here, we propose an approach to this problem; an inversion of eddy current flaw signal using neural networks trained by finite element model-based synthetic signatures. Total 216 eddy current signals from four different types of axisymmetric flaws in tubes are generated by finite element models of which the accuracy is experimentally validated. From each simulated signature, total 24 eddy current features are extracted and among them 13 features are finally selected for flaw characterization. Based on these features, probabilistic neural networks discriminate flaws into four different types according to the location and the shape, and successively back propagation neural networks determine the size parameters of the discriminated flaw

  4. Ultrasonographic Detection of Tooth Flaws

    Science.gov (United States)

    Bertoncini, C. A.; Hinders, M. K.; Ghorayeb, S. R.

    2010-02-01

    The goal of our work is to adapt pulse-echo ultrasound into a high resolution imaging modality for early detection of oral diseases and for monitoring treatment outcome. In this talk we discuss our preliminary results in the detection of: demineralization of the enamel and dentin, demineralization or caries under and around existing restorations, caries on occlusal and interproximal surfaces, cracks of enamel and dentin, calculus, and periapical lesions. In vitro immersion tank experiments are compared to results from a handpiece which uses a compliant delay line to couple the ultrasound to the tooth surface. Because the waveform echoes are complex, and in order to make clinical interpretation of ultrasonic waveform data in real time, it is necessary to automatically interpret the signals. We apply the dynamic wavelet fingerprint algorithms to identify and delineate echographic features that correspond to the flaws of interest in teeth. The resulting features show a clear distinction between flawed and unflawed waveforms collected with an ultrasonic handpiece on both phantom and human cadaver teeth.

  5. Nuclear reactor pressure vessel flaw distribution development

    International Nuclear Information System (INIS)

    Kennedy, E.L.; Foulds, J.R.; Basin, S.L.

    1991-12-01

    Previous attempts to develop flaw distributions for probabilistic fracture mechanics analyses of pressurized water reactor (PWR) vessels have aimed at the estimation of a ''generic'' distribution applicable to all PWR vessels. In contrast, this report describes (1) a new flaw distribution development analytic methodology that can be applied to the analysis of vessel-specific inservice inspection (ISI) data, and (2) results of the application of the methodology to the analysis of flaw data for each vessel case (ISI data on three PWR vessels and laboratory inspection data on sections of the Midland reactor vessel). Results of this study show significant variation among the flaw distributions derived from the various data sets analyzed, strongly suggesting than a vessel-specific flaw distribution (for vessel integrity prediction under pressurized thermal shock) is preferred over a ''generic'' distribution. In addition, quantitative inspection system flaw sizing accuracy requirements have been identified for developing a flaw distribution from vessel ISI data. The new flaw data analysis methodology also permits quantifying the reliability of the flaw distribution estimate. Included in the report are identified needs for further development of several aspects of ISI data acquisition and vessel integrity prediction practice

  6. Flaw distribution development from vessel ISI data

    International Nuclear Information System (INIS)

    Foulds, J.R.; Kennedy, E.L.; Basin, S.L.; Rosinski, S.T.

    1991-01-01

    Previous attempts to develop flaw distributions for use in the structural integrity evaluation of pressurized water reactor (PWR) vessels have aimed at the estimation of a ''generic'' distribution applicable to all vessels. In contrast, this paper describes the analysis of vessel-specific in-service inspection (ISI) data for the development of a flaw distribution reliably representative of the condition of the particular vessel inspected. The application of the methodology may be extended to other vessels, but has been primarily developed for PWR reactor vessels. For this study, the flaw data analyzed included data obtained from three recently performed PWR vessel ISIs and from laboratory inspection of selected weldment sections of the Midland reactor vessel. The variability in both the character of the reviewed data (size range of flaws, number of flaws) and the UT (ultrasonic test) inspection system performance identified a need for analyzing the inspection results on a vessel-, or data set-specific basis. For this purpose, traditional histogram-based methods were inadequate, and a new methodology that can accept a very small number of flaws (typical of vessel-specific ISI results) and that includes consideration of inspection system flaw detection reliability, flaw sizing accuracy and flaw detection threshold, was developed. Results of the application of the methodology to each of the four PWR reactor vessel cases studied are presented and discussed

  7. Ultrasonic flaw detection in a monorail box beam

    Science.gov (United States)

    Zheng, Peng; Greve, David W.; Oppenheim, Irving J.

    2009-03-01

    A steel box beam in a monorail application is constructed with an epoxy grout wearing surface, precluding visual inspection of its top flange. This paper describes a sequence of experimental research tasks to develop an ultrasonic system to detect flaws (such as fatigue cracks) in that flange, and the results of a field test to demonstrate system performance. The problem is constrained by the fact that the flange is exposed only along its longitudinal edges, and by the fact that permanent installation of transducers at close spacing was deemed to be impractical. The system chosen for development, after experimental comparison of alternate technologies, features angle-beam ultrasonic transducers with fluid coupling to the flange edge; the emitting transducers create transverse waves that travel diagonally across the width of the flange, where an array of receiving transducers detect flaw reflections and flaw shadows. The system rolls along the box beam, surveying (screening) the top flange for the presence of flaws. In a first research task, conducted on a full-size beam specimen, we compared waves generated from different transducer locations, either the flange edge or the web face, and at different frequency ranges. At relatively low frequencies, such as 100 kHz, we observed Lamb wave modes, and at higher frequency, in the MHz range, we observed nearlylongitudinal waves with trailing pulses. In all cases we observed little attenuation by the wearing surface and little influence of reflection at the web-flange joints. At the conclusion of this task we made the design decision to use edgemounted transducers at relatively high frequency, with correspondingly short wavelength, for best scattering from flaws. In a second research task we conducted experiments at 55% scale on a steel plate, with machined flaws of different size, and detected flaws of target size for the intended application. We then compared the performance of bonded transducers, fluid

  8. Flaw evolution monitoring by acoustic emission technique

    International Nuclear Information System (INIS)

    Ghia, S.; Sala, A.; Lucia, A.

    1986-01-01

    Flaw evolution monitoring during mechanical fatigue test has been performed by acoustic emission (AE) technique. Testing on 1:5 reduced scale vessel containing fabrication defects was carried out in the frame of an European program for pressure component residual life evaluation. Characteristics of AE signals associated to flaw evolution are discussed

  9. Probabilistic analysis of flaw distribution on structure under cyclic load

    International Nuclear Information System (INIS)

    Kwak, Sang Log; Choi, Young Hwan; Kim, Hho Jung

    2003-01-01

    Flaw geometries, applied stress, and material properties are major input variables for the fracture mechanics analysis. Probabilistic approach can be applied for the consideration of uncertainties within these input variables. But probabilistic analysis requires many assumptions due to the lack of initial flaw distributions data. In this study correlations are examined between initial flaw distributions and in-service flaw distributions on structures under cyclic load. For the analysis, LEFM theories and Monte Carlo simulation are applied. Result shows that in-service flaw distributions are determined by initial flaw distributions rather than fatigue crack growth rate. So initial flaw distribution can be derived from in-service flaw distributions

  10. Labor security in radiation flaw detection

    International Nuclear Information System (INIS)

    Margulis, U.Ya.; Chistov, E.D.; Partolin, O.F.; Pertsov, V.A.; Momzhiev, B.N.; Sprygaev, I.F.

    1986-01-01

    Problems of ensuring safe labour conditions in radiation flaw detection are considered. Methods for ionizing radiation protection are given calculating techniques for shielding flaw detectors and stationary structures are presented as well. Safe methods of nondestructive testing of items under field conditions, in a shop and special laboratories using gamma- and X-ray flaw detectors, betatrons, electron accelerators are described. Attention is paid to the principles of radiation factor stantardization as well as radiation monitoring. Analysis of accidents and recommendations on their prevention and liquidation of accidental consequences are given

  11. Fundamentally Flawed: Extension Administrative Practice (Part 1).

    Science.gov (United States)

    Patterson, Thomas F., Jr.

    1997-01-01

    Extension's current administrative techniques are based on the assumptions of classical management from the early 20th century. They are fundamentally flawed and inappropriate for the contemporary workplace. (SK)

  12. Continuous Shearlet Tight Frames

    KAUST Repository

    Grohs, Philipp

    2010-10-22

    Based on the shearlet transform we present a general construction of continuous tight frames for L2(ℝ2) from any sufficiently smooth function with anisotropic moments. This includes for example compactly supported systems, piecewise polynomial systems, or both. From our earlier results in Grohs (Technical report, KAUST, 2009) it follows that these systems enjoy the same desirable approximation properties for directional data as the previous bandlimited and very specific constructions due to Kutyniok and Labate (Trans. Am. Math. Soc. 361:2719-2754, 2009). We also show that the representation formulas we derive are in a sense optimal for the shearlet transform. © 2010 Springer Science+Business Media, LLC.

  13. A time-domain synthetic aperture ultrasound imaging method for material flaw quantification with validations on small-scale artificial and natural flaws.

    Science.gov (United States)

    Guan, Xuefei; He, Jingjing; Rasselkorde, El Mahjoub

    2015-02-01

    A direct time-domain reconstruction and sizing method of synthetic aperture focusing technique (SAFT) is developed to improve the spatial resolution and sizing accuracy for phased-array ultrasonic inspections. The basic idea of the reconstruction algorithm is to coherently superimpose multiple A-scan measurements, incorporating the phase information of the sampling points. The algorithm involves data mapping and in-phase summation according to time-of-flight (TOF). Data mapping refers to the process of placing each of the sampling points to a two-/three-dimensional grid that represents the geometry model of the object being inspected. The value for each of the cells of the grid is a summation of all sampling points mapped into the cell. A sizing method based on the concept of 6 dB-drop is proposed to characterize the flaw boundary. The extents, orientation and the shape of the flaw can then be inferred to provide more information for life assessment calculations. Lab experiments are performed using a 10 MHz phased-array ultrasonic transducer to collect data from a cylinder material block with closely spaced artificial flaws and from a material block with a natural flaw. The developed method is used to process the experimental data to characterize the flaws. Using the developed method, the improvement of spatial resolution is observed. Results indicate that four closely spaced 0.794 mm-diameter flat-bottomed holes are clearly identified, and the quantification of size and orientation of the natural flaw is very close to the actual measurement made from digital microscopy after cutting the testing piece apart. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Midland reactor pressure vessel flaw distribution

    International Nuclear Information System (INIS)

    Foulds, J.R.; Kennedy, E.L.; Rosinski, S.T.

    1993-12-01

    The results of laboratory nondestructive examination (NDE), and destructive cross-sectioning of selected weldment sections of the Midland reactor pressure vessel were analyzed per a previously developed methodology in order to develop a flaw distribution. The flaw distributions developed from the NDE results obtained by two different ultrasonic test (UT) inspections (Electric Power Research Institute NDE Center and Pacific Northwest Laboratories) were not statistically significantly different. However, the distribution developed from the NDE Center's (destructive) cross-sectioning-based data was found to be significantly different than those obtained through the UT inspections. A fracture mechanics-based comparison of the flaw distributions showed that the cross-sectioning-based data, conservatively interpreted (all defects considered as flaws), gave a significantly lower vessel failure probability when compared with the failure probability values obtained using the UT-based distributions. Given that the cross-sectioning data were reportedly biased toward larger, more significant-appearing (by UT) indications, it is concluded that the nondestructive examinations produced definitively conservative results. In addition to the Midland vessel inspection-related analyses, a set of twenty-seven numerical simulations, designed to provide a preliminary quantitative assessment of the accuracy of the flaw distribution method used here, were conducted. The calculations showed that, in more than half the cases, the analysis produced reasonably accurate predictions

  15. Supersonic flaw detection device for nozzle

    International Nuclear Information System (INIS)

    Hata, Moriki.

    1996-01-01

    In a supersonic flaw detection device to be attached to a body surface of a reactor pressure vessel for automatically detecting flaws of a welded portion of a horizontally connected nozzle by using supersonic waves, a running vehicle automatically running along a circumferential direction of the nozzle comprises a supersonic flaw detection means for detecting flaws of the welded portion of the nozzle by using supersonic waves, and an inclination angle sensor for detecting the inclination angle of the running vehicle relative to the central axis of the nozzle. The running distance of the vehicle running along the circumference of the nozzle, namely, the position of the running vehicle from a reference point of the nozzle can be detected accurately by dividing the distance around the nozzle by the inclination angle detected by the inclination angle sensor. Accordingly, disadvantages in the prior art, for example, that the detected values obtained by using an encoder are changed by slipping or idle running of the magnet wheels are eliminated, and accurate flaw detection can be conducted. In addition, an operation of visually adjusting the reference point for the device can be eliminated. An operator's exposure dose can be reduced. (N.H.)

  16. Methodology for inferring initial flaw distribution

    International Nuclear Information System (INIS)

    Jouris, G.M.; Shaffer, D.H.

    1980-01-01

    It has been common practice in both deterministic and probabilistic assessment of the integrity of a pressure vessel to assume the presence of a rather large flaw (usually 1/4 the thickness of the vessel wall) in the belt-line region. Although it is highly unlikely that such a large flaw would be present, the assumption is adopted in order to be conservative. A more realistic approach, which can be incorporated in the probabilistic analysis of integrity, is to characterize the depth of a flaw as a random variable and thus allow the probabilities associated with the presence of various size flaws to be reflected in the final estimated probability of vessel failure. This is precisely the motivation for developing the methodology to obtain the distribution of initial flaw depth, which is presented in this paper. It should be mentioned that the methodology developed here is not an end in itself but rather provides an input distribution to be used in a comprehensive integrity assessment. (orig.)

  17. Real time automatic discriminating of ultrasonic flaws

    International Nuclear Information System (INIS)

    Suhairy Sani; Mohd Hanif Md Saad; Marzuki Mustafa; Mohd Redzwan Rosli

    2009-01-01

    This paper is concerned with the real time automatic discriminating of flaws from two categories; i. cracks (planar defect) and ii. Non-cracks (volumetric defect such as cluster porosity and slag) using pulse-echo ultrasound. The raw ultrasonic flaws signal were collected from a computerized robotic plane scanning system over the whole of each reflector as the primary source of data. The signal is then filtered and the analysis in both time and frequency domain were executed to obtain the selected feature. The real time feature analysis techniques measured the number of peaks, maximum index, pulse duration, rise time and fall time. The obtained features could be used to distinguish between quantitatively classified flaws by using various tools in artificial intelligence such as neural networks. The proposed algorithm and complete system were implemented in a computer software developed using Microsoft Visual BASIC 6.0 (author)

  18. Less-Tight versus Tight Control of Hypertension in Pregnancy

    NARCIS (Netherlands)

    Magee, Laura A.; von Dadelszen, Peter; Rey, Evelyne; Ross, Susan; Asztalos, Elizabeth; Murphy, Kellie E.; Menzies, Jennifer; Sanchez, Johanna; Singer, Joel; Gafni, Amiram; Gruslin, Andrée; Helewa, Michael; Hutton, Eileen; Lee, Shoo K.; Lee, Terry; Logan, Alexander G.; Ganzevoort, Wessel; Welch, Ross; Thornton, Jim G.; Moutquin, Jean-Marie

    2015-01-01

    BACKGROUND The effects of less-tight versus tight control of hypertension on pregnancy complications are unclear. METHODS We performed an open, international, multicenter trial involving women at 14 weeks 0 days to 33 weeks 6 days of gestation who had nonproteinuric preexisting or gestational

  19. Stress-induced light scattering method for the detection of latent flaws on fine polished glass substrates.

    Science.gov (United States)

    Sakata, Y; Sakai, K; Nonaka, K

    2014-08-01

    Fine polishing techniques, such as the chemical mechanical polishing treatment, are one of the most important technique to glass substrate manufacturing. Mechanical interaction in the form of friction occurs between the abrasive and the substrate surface during polishing, which may cause formation of latent flaws on the glass substrate surface. Fine polishing-induced latent flaws may become obvious during a subsequent cleaning process if glass surfaces are corroded away by chemical interaction with the cleaning liquid. Latent flaws thus reduce product yield. In general, non-destructive inspection techniques, such as the light-scattering methods, used to detect foreign matters on the glass substrate surface. However, it is difficult to detect latent flaws by these methods because the flaws remain closed. Authors propose a novel inspection technique for fine polishing-induced latent flaws by combining the light scattering method with stress effects, referred to as the stress-induced light scattering method (SILSM). SILSM is able to distinguish between latent flaws and particles on the surface. In this method, samples are deformed by an actuator and stress effects are induced around the tips of latent flaws. Due to the photoelastic effect, the refractive index of the material around the tip of a latent flaw is changed. This changed refractive index is in turn detected by a cooled charge-coupled device camera as variations in light scattering intensity. In this report, surface latent flaws are detected non-destructively by applying SILSM to glass substrates, and the utility of SILSM evaluated as a novel inspection technique.

  20. Tight junctions and human diseases.

    Science.gov (United States)

    Sawada, Norimasa; Murata, Masaki; Kikuchi, Keisuke; Osanai, Makoto; Tobioka, Hirotoshi; Kojima, Takashi; Chiba, Hideki

    2003-09-01

    Tight junctions are intercellular junctions adjacent to the apical end of the lateral membrane surface. They have two functions, the barrier (or gate) function and the fence function. The barrier function of tight junctions regulates the passage of ions, water, and various macromolecules, even of cancer cells, through paracellular spaces. The barrier function is thus relevant to edema, jaundice, diarrhea, and blood-borne metastasis. On the other hand, the fence function maintains cell polarity. In other words, tight junctions work as a fence to prevent intermixing of molecules in the apical membrane with those in the lateral membrane. This function is deeply involved in cancer cell biology, in terms of loss of cell polarity. Of the proteins comprising tight junctions, integral membrane proteins occludin, claudins, and JAMs have been recently discovered. Of these molecules, claudins are exclusively responsible for the formation of tight-junction strands and are connected with the actin cytoskeleton mediated by ZO-1. Thus, both functions of tight junctions are dependent on the integrity of the actin cytoskeleton as well as ATP. Mutations in the claudin14 and the claudin16 genes result in hereditary deafness and hereditary hypomagnesemia, respectively. Some pathogenic bacteria and viruses target and affect the tight-junction function, leading to diseases. In this review, the relationship between tight junctions and human diseases is summarized.

  1. Less-tight versus tight control of hypertension in pregnancy.

    Science.gov (United States)

    Magee, Laura A; von Dadelszen, Peter; Rey, Evelyne; Ross, Susan; Asztalos, Elizabeth; Murphy, Kellie E; Menzies, Jennifer; Sanchez, Johanna; Singer, Joel; Gafni, Amiram; Gruslin, Andrée; Helewa, Michael; Hutton, Eileen; Lee, Shoo K; Lee, Terry; Logan, Alexander G; Ganzevoort, Wessel; Welch, Ross; Thornton, Jim G; Moutquin, Jean-Marie

    2015-01-29

    The effects of less-tight versus tight control of hypertension on pregnancy complications are unclear. We performed an open, international, multicenter trial involving women at 14 weeks 0 days to 33 weeks 6 days of gestation who had nonproteinuric preexisting or gestational hypertension, office diastolic blood pressure of 90 to 105 mm Hg (or 85 to 105 mm Hg if the woman was taking antihypertensive medications), and a live fetus. Women were randomly assigned to less-tight control (target diastolic blood pressure, 100 mm Hg) or tight control (target diastolic blood pressure, 85 mm Hg). The composite primary outcome was pregnancy loss or high-level neonatal care for more than 48 hours during the first 28 postnatal days. The secondary outcome was serious maternal complications occurring up to 6 weeks post partum or until hospital discharge, whichever was later. Included in the analysis were 987 women; 74.6% had preexisting hypertension. The primary-outcome rates were similar among 493 women assigned to less-tight control and 488 women assigned to tight control (31.4% and 30.7%, respectively; adjusted odds ratio, 1.02; 95% confidence interval [CI], 0.77 to 1.35), as were the rates of serious maternal complications (3.7% and 2.0%, respectively; adjusted odds ratio, 1.74; 95% CI, 0.79 to 3.84), despite a mean diastolic blood pressure that was higher in the less-tight-control group by 4.6 mm Hg (95% CI, 3.7 to 5.4). Severe hypertension (≥160/110 mm Hg) developed in 40.6% of the women in the less-tight-control group and 27.5% of the women in the tight-control group (Phypertension. (Funded by the Canadian Institutes of Health Research; CHIPS Current Controlled Trials number, ISRCTN71416914; ClinicalTrials.gov number, NCT01192412.).

  2. Irradiation effects and the duplication of detected flaws in service

    International Nuclear Information System (INIS)

    Mager, T.R.

    1976-01-01

    ASME Code procedure for evaluating the acceptability of flaws detected during in-service inspection is revised. Critical crack size for instability is proposed as criteria for detected flaws in operating plants

  3. Reliably detectable flaw size for NDE methods that use calibration

    Science.gov (United States)

    Koshti, Ajay M.

    2017-04-01

    Probability of detection (POD) analysis is used in assessing reliably detectable flaw size in nondestructive evaluation (NDE). MIL-HDBK-1823 and associated mh18232 POD software gives most common methods of POD analysis. In this paper, POD analysis is applied to an NDE method, such as eddy current testing, where calibration is used. NDE calibration standards have known size artificial flaws such as electro-discharge machined (EDM) notches and flat bottom hole (FBH) reflectors which are used to set instrument sensitivity for detection of real flaws. Real flaws such as cracks and crack-like flaws are desired to be detected using these NDE methods. A reliably detectable crack size is required for safe life analysis of fracture critical parts. Therefore, it is important to correlate signal responses from real flaws with signal responses form artificial flaws used in calibration process to determine reliably detectable flaw size.

  4. Eddy current probe and method for flaw detection in metals

    Science.gov (United States)

    Watjen, John P.

    1987-06-23

    A flaw detecting system is shown which includes a probe having a pair of ferrite cores with in-line gaps in close proximity to each other. An insulating, non-magnetic, non-conducting holder fills the gaps and supports the ferrite cores in a manner such that the cores form a generally V-shape. Each core is provided with an excitation winding and a detection winding. The excitation windings are connected in series or parallel with an rf port for connection thereof to a radio frequency source. The detection windings, which are differentially wound, are connected in series circuit to a detector port for connection to a voltage measuring instrument. The ferrite cores at the in-line gaps directly engage the metal surface of a test piece, and the probe is scanned along the test piece. In the presence of a flaw in the metal surface the detection winding voltages are unbalanced, and the unbalance is detected by the voltage measuring instrument. The insulating holder is provided with a profile which conforms to that of a prominent feature of the test piece to facilitate movement of the probe along the feature, typically an edge or a corner.

  5. Stress intensities in flawed pressure vessels

    International Nuclear Information System (INIS)

    Smith, C.W.; Jolles, M.; Peters, W.H.

    1977-01-01

    A technique for determining the stess intensity factor (SIF) near pressure vessel flaws or cracks experimentally from photoelastic data for use in two-dimensional problems was developed in the 1950's. This technique was modified and extended to a variety of two-dimensional problems. The technique has been refined further and what has evolved may be regarded as a hybrid technique which affects a marriage between ''frozen stress'' photoelastic results and a simple least-squares digital computer program for estimating SIF values in three-dimensional problems. This technique, in its original modified form, has been shown to be applicable to a study of surface flaws and the applicability of the method to complex crack body geometries of current technological importance are discussed. The analytical foundations of the method are reviewed

  6. A new digital correlation flaw detection system

    International Nuclear Information System (INIS)

    Lee, B.B.; Furgason, E.S.

    1981-01-01

    A new portable digital random signal flaw detection system is described which uses a digital delay line to replace the acoustic delay line of the original random signal system. Using this new system, a comparison was made between the two types of transmit signals which have been used in previous systems--m-sequences and random signals. This comparison has not been possible with these previous correlation flaw detection systems. Results indicated that for high-speed short code operation, the m-sequences produced slightly lower range sidelobes than typical samples of a clipped random signal. For normal long code operation, results indicated that system performance is essentially equivalent in resolution and signal-to-noise ratio using either m-sequences or clipped and sampled random signals. Further results also showed that for normal long code operation, the system produces outputs equivalent in resolution to pulse-echo systems, but with the added benefit of signal-to-noise ratio enhancement

  7. Detection of flaws below curved surfaces

    International Nuclear Information System (INIS)

    Elsley, R.K.; Addison, R.C.; Graham, L.J.

    1983-01-01

    A measurement model has been developed to describe ultrasonic measurements made with circular piston transducers in parts with flat or cylindrically curved surfaces. The model includes noise terms to describe electrical noise, scatterer noise and echo noise as well as effects of attenuation, diffraction and Fresnel loss. An experimental procedure for calibrating the noise terms of the model was developed. Experimental measurements were made on a set of known flaws located beneath a cylindrically curved surface. The model was verified by using it to correct the experimental measurements to obtain the absolute scattering amplitude of the flaws. For longitudinal wave propagation within the part, the derived scattering amplitudes were consistent with predictions at internal angles of less than 30 0 . At larger angles, focusing and aberrations caused a lack of agreement; the model needs further refinement in this case. For shear waves, it was found that the frequency for optimum flaw detection in the presence of material noise is lower than that for longitudinal waves; lower frequency measurements are currently in progress. The measurement model was then used to make preliminary predictions of the best experimental measurement technique for the detection of cracks located under cylindrically curved surfaces

  8. Common methodological flaws in economic evaluations.

    Science.gov (United States)

    Drummond, Michael; Sculpher, Mark

    2005-07-01

    Economic evaluations are increasingly being used by those bodies such as government agencies and managed care groups that make decisions about the reimbursement of health technologies. However, several reviews of economic evaluations point to numerous deficiencies in the methodology of studies or the failure to follow published methodological guidelines. This article, written for healthcare decision-makers and other users of economic evaluations, outlines the common methodological flaws in studies, focussing on those issues that are likely to be most important when deciding on the reimbursement, or guidance for use, of health technologies. The main flaws discussed are: (i) omission of important costs or benefits; (ii) inappropriate selection of alternatives for comparison; (iii) problems in making indirect comparisons; (iv) inadequate representation of the effectiveness data; (v) inappropriate extrapolation beyond the period observed in clinical studies; (vi) excessive use of assumptions rather than data; (vii) inadequate characterization of uncertainty; (viii) problems in aggregation of results; (ix) reporting of average cost-effectiveness ratios; (x) lack of consideration of generalizability issues; and (xi) selective reporting of findings. In each case examples are given from the literature and guidance is offered on how to detect flaws in economic evaluations.

  9. Application of Fourier elastodynamics to direct and inverse problems for the scattering of elastic waves from flaws near surfaces

    International Nuclear Information System (INIS)

    Richardson, J.M.; Fertig, K.W. Jr.

    1983-01-01

    In order to inspect flaws which lie too close to the surface a Fourier elastodynamic formalism is proposed which enables one to decompose the elastodynamic system into separately charterizable parts by means of planes perpendicular to the z-axis. The process can be represented by a generalized transfer function relating the near-field scattered waves to the waves incident on a slab of material containing the flaw. The Fourier elastodynamics are applied to the characterization of the total scattering process involving a flaw at various distances from a plastic-water interface. An abbreviated discussion of Fourier elastodynamics is presented, and the results specialized to the case of spherical voids and inclusions bear an interface. Finally, the computational results for several ranges of temporal frequency and for a sequence of values of the distance from the flaw center to the interface are discussed

  10. Evaluation of flaws in carbon steel piping. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Gamble, R.M.; Mehta, H.S.; Yukawa, S.; Ranganath, S.

    1986-10-01

    The objective of this program was to develop flaw evaluation procedures and allowable flaw sizes for ferritic piping used in light water reactor (LWR) power generation facilities. The program results provide relevant ASME Code groups with the information necessary to define flaw evaluation procedures, allowable flaw sizes, and their associated bases for Section XI of the code. Because there are several possible flaw-related failure modes for ferritic piping over the LWR operating temperature range, three analysis methods were employed to develop the evaluation procedures. These include limit load analysis for plastic collapse, elastic plastic fracture mechanics (EPFM) analysis for ductile tearing, and linear elastic fracture mechanics (LEFM) analysis for non ductile crack extension. To ensure the appropriate analysis method is used in an evaluation, a step by step procedure also is provided to identify the relevant acceptance standard or procedure on a case by case basis. The tensile strength and toughness properties required to complete the flaw evaluation for any of the three analysis methods are included in the evaluation procedure. The flaw evaluation standards are provided in tabular form for the plastic collapse and ductile tearing modes, where the allowable part through flaw depth is defined as a function of load and flaw length. For non ductile crack extension, linear elastic fracture mechanics analysis methods, similar to those in Appendix A of Section XI, are defined. Evaluation flaw sizes and procedures are developed for both longitudinal and circumferential flaw orientations and normal/upset and emergency/faulted operating conditions. The tables are based on margins on load of 2.77 and 1.39 for circumferential flaws and 3.0 and 1.5 for longitudinal flaws for normal/upset and emergency/faulted conditions, respectively.

  11. Evaluation of flaws in carbon steel piping. Final report

    International Nuclear Information System (INIS)

    Zahoor, A.; Gamble, R.M.; Mehta, H.S.; Yukawa, S.; Ranganath, S.

    1986-10-01

    The objective of this program was to develop flaw evaluation procedures and allowable flaw sizes for ferritic piping used in light water reactor (LWR) power generation facilities. The program results provide relevant ASME Code groups with the information necessary to define flaw evaluation procedures, allowable flaw sizes, and their associated bases for Section XI of the code. Because there are several possible flaw-related failure modes for ferritic piping over the LWR operating temperature range, three analysis methods were employed to develop the evaluation procedures. These include limit load analysis for plastic collapse, elastic plastic fracture mechanics (EPFM) analysis for ductile tearing, and linear elastic fracture mechanics (LEFM) analysis for non ductile crack extension. To ensure the appropriate analysis method is used in an evaluation, a step by step procedure also is provided to identify the relevant acceptance standard or procedure on a case by case basis. The tensile strength and toughness properties required to complete the flaw evaluation for any of the three analysis methods are included in the evaluation procedure. The flaw evaluation standards are provided in tabular form for the plastic collapse and ductile tearing modes, where the allowable part through flaw depth is defined as a function of load and flaw length. For non ductile crack extension, linear elastic fracture mechanics analysis methods, similar to those in Appendix A of Section XI, are defined. Evaluation flaw sizes and procedures are developed for both longitudinal and circumferential flaw orientations and normal/upset and emergency/faulted operating conditions. The tables are based on margins on load of 2.77 and 1.39 for circumferential flaws and 3.0 and 1.5 for longitudinal flaws for normal/upset and emergency/faulted conditions, respectively

  12. Are tight gas resources overstated?

    Energy Technology Data Exchange (ETDEWEB)

    Roche, P.

    2004-11-01

    According to conventional wisdom, North America's tight gas resources are continuous, regional accumulations of water-free methane, trapped in low-permeability rock, and involving very little exploration risk. Backing up conventional wisdom, EnCana Corporation is investing heavily in technology-intensive and capital-intensive tight gas plays in Western Canada and the Rocky Mountain regions of the United States. On the other hand, a recent study in the Greater Green River Basin of southwestern Wyoming says that tight gas resources have been significantly overestimated, by as much as three to five times too high, and the risks of exploration are every bit as high as those for conventional exploration. This study essentially dismisses the whole idea of tight gas, or basin-centred gas as a myth, the authors being firmly convinced that tight gas formations should be viewed as conventional hydrocarbon systems, with the usual risks of exploration. This paper discusses the controversy created by this recent study and the implications for natural gas reserves on a basin and individual company level, and the risks associated with exploration. The views of EnCana Corporation, being the company most heavily involved in tight gas and coalbed methane, and those of John Masters, co-founder of Canadian Hunter Exploration Ltd., and discoverer of the blockbuster Elsmworth tight gas deposit in northeastern Alberta in the mid-1970s, are explained in considerable detail, in an effort to dismiss the doubters. EnCana officials and Masters argue that the points raised by the authors of the Greater Green River study do not hold water: Tight gas or basin gas is a distinct hydrocarbon formation, characterized by low permeability, therefore it is to be expected that the gas will take longer to come out of the ground. Neither is the role of water in basin-centred gas systems the major problem as claimed by the doubters. They also characterize it as imprudent to claim to know what the

  13. Nondestructive detection of surface flaws in materials by infrared thermography

    International Nuclear Information System (INIS)

    Ishii, Toshimitsu; Ooka, Norikazu; Eto, Motokuni; Hoshiya, Taiji; Okamoto, Yoshizo

    1999-01-01

    Infrared thermography is one of the useful remote sensing techniques applied to the nondestructive detection of surface flaws in materials. Radiation temperatures of the specimen surface and surrounding walls as well as the difference in them are crucial factors to detect surface flaws from thermal images, and it is essential that these factors be properly evaluated beforehand in order to detect the flaws by infrared thermography. In this study, the radiation temperature of nuclear graphite specimens heated uniformly was measured by infrared thermography to evaluate the radiation characteristics such as emissivity, radiosity coefficient and variation of radiation temperature. The influence of the temperature difference between the test specimen and its surroundings on the limit of detection of pinhole flaws was discussed on the basis of the thermal images of graphite specimen with surface flaws. It was found that the thermal image of a small flaw was clearly visible with increase in the temperature difference. (author)

  14. High-temperature flaw assessment procedure

    International Nuclear Information System (INIS)

    Ruggles, M.B.; Takahashi, Y.; Ainsworth, R.A.

    1991-08-01

    Described is the background work performed jointly by the Electric Power Research Institute in the United States, the Central Research Institute of Electric Power Industry in Japan and Nuclear Electric plc in the United Kingdom with the purpose of developing a high-temperature flaw assessment procedure for reactor components. Existing creep-fatigue crack-growth models are reviewed, and the most promising methods are identified. Sources of material data are outlined, and results of the fundamental deformation and crack-growth tests are discussed. Results of subcritical crack-growth exploratory tests, creep-fatigue crack-growth tests under repeated thermal transient conditions, and exploratory failure tests are presented and contrasted with the analytical modeling. Crack-growth assessment methods are presented and applied to a typical liquid-metal reactor component. The research activities presented herein served as a foundation for the Flaw Assessment Guide for High-Temperature Reactor Components Subjected to Creep-Fatigue Loading published separately. 30 refs., 108 figs., 13 tabs

  15. Preclinical animal anxiety research - flaws and prejudices.

    Science.gov (United States)

    Ennaceur, Abdelkader; Chazot, Paul L

    2016-04-01

    The current tests of anxiety in mice and rats used in preclinical research include the elevated plus-maze (EPM) or zero-maze (EZM), the light/dark box (LDB), and the open-field (OF). They are currently very popular, and despite their poor achievements, they continue to exert considerable constraints on the development of novel approaches. Hence, a novel anxiety test needs to be compared with these traditional tests, and assessed against various factors that were identified as a source of their inconsistent and contradictory results. These constraints are very costly, and they are in most cases useless as they originate from flawed methodologies. In the present report, we argue that the EPM or EZM, LDB, and OF do not provide unequivocal measures of anxiety; that there is no evidence of motivation conflict involved in these tests. They can be considered at best, tests of natural preference for unlit and/or enclosed spaces. We also argued that pharmacological validation of a behavioral test is an inappropriate approach; it stems from the confusion of animal models of human behavior with animal models of pathophysiology. A behavioral test is developed to detect not to produce symptoms, and a drug is used to validate an identified physiological target. In order to overcome the major methodological flaws in animal anxiety studies, we proposed an open space anxiety test, a 3D maze, which is described here with highlights of its various advantages over to the traditional tests.

  16. Fabrication Flaw Density and Distribution in Weld Repairs

    International Nuclear Information System (INIS)

    Doctor, Steven R.

    2009-01-01

    The Pacific Northwest National Laboratory (PNNL) is developing a generalized flaw distribution for the population of nuclear reactor pressure vessels and for piping welds in the U. S. operating reactors. The purpose of the generalized flaw distribution is to predict component-specific flaw densities. The estimates of fabrication flaws are intended for use in fracture mechanics structural integrity assessments. Structural integrity assessments, such as estimating the frequency of loss-of-coolant accidents, are performed by computer codes that require, as input, accurate estimates of flaw densities. Welds from four different cancelled reactor pressure vessels and a collection of archived pipes have been studied to develop empirical estimates of fabrication flaw densities. This paper describes the fabrication flaw distribution and characterization in the repair weld metal of vessels and piping. This work indicates that large flaws occur in these repairs which are complex in composition and sometimes include cracks on the ends of the repair cavities. Parametric analysis using an exponential fit is performed on the data. Construction records where available were reviewed. It is difficult to make conclusions due to the limited number of construction records reviewed. However, the records reviewed to date show a significant change in repair frequency over the years when the components in this study were fabricated. A description of repair flaw morphology is provided with a discussion of fracture mechanics significance.

  17. An intelligent software approach to ultrasonic flaw classification in weldments

    International Nuclear Information System (INIS)

    Song, Sung Jin; Kim, Hak Joon; Lee, Hyun

    1997-01-01

    Ultrasonic pattern recognition is the most effective approach to the problem of discriminating types of flaws in weldments based on ultrasonic flaw signals. In spite of significant progress on this methodology, it has not been widely used in practical ultrasonic inspection of weldments in industry. Hence, for the convenient application of this approach in many practical situations, we develop an intelligent ultrasonic signature classification software which can discriminate types of flaws in weldments using various tools in artificial intelligence such as neural networks. This software shows excellent performances in an experimental problem where flaws in weldments are classified into two categories of cracks and non-cracks.

  18. Flaw behavior in mechanically loaded clad plates

    International Nuclear Information System (INIS)

    Iskander, S.K.; Robinson, G.C.; Oland, C.B.

    1989-01-01

    A small crack near the inner surface of clad nuclear reactor pressure vessels is an important consideration in the safety assessment of the structural integrity of the vessel. Four-point bend tests on large plate specimens, conforming to ASTM specification for pressure vessel plates, alloy steels, quenched and tempered, Mn-Mo and Mn-Mo-Ni (A533) grade B six clad and two unclad with stainless steels 308, 309 and 312 weld wires, were performed to determine the effect of cladding upon the propagation of small surface cracks subjected to stress states. Results indicated that the tough surface layer composed of cladding and/or heat-affected zone has enhanced the load-bearing capacity of plates under conditions where unclad plates have ruptured. The results are interpreted in terms of fracture mechanics. The behavior of flaws in clad reactor pressure vessels is examined in the light of the test results. 11 refs., 8 figs., 2 tabs

  19. The Flaws of Fragmented Financial Standard Setting

    DEFF Research Database (Denmark)

    Mügge, Daniel; Perry, James

    2014-01-01

    rating, accounting, and derivatives trading, this article demonstrates why the appropriateness of the organizational architecture of global financial governance is necessarily contingent upon one’s understanding of how financial markets work. In particular, if financial markets are not anchored......In the half decade following the 2007 financial crisis, the reform of global financial governance was driven by two separate policy debates: one on the substantive content of regulations, the other on the organizational architecture of their governance. The separation of the two debates among...... policymakers has been mirrored in academia, where postcrisis analyses of financial governance have remained detached from reinvigorated discussions about the nature of financial markets. We argue that this separation is deeply flawed. Presenting an analysis of interactions between standards for banking, credit...

  20. Tightness of voter model interfaces

    Czech Academy of Sciences Publication Activity Database

    Sturm, A.; Swart, Jan M.

    2008-01-01

    Roč. 13, - (2008), s. 165-174 ISSN 1083-589X R&D Projects: GA ČR GA201/06/1323; GA ČR GA201/07/0237 Institutional research plan: CEZ:AV0Z10750506 Keywords : long range voter model * swapping voter model * interface tightness * exclusion process Subject RIV: BD - Theory of Information Impact factor: 0.392, year: 2008 http://www.emis.de/journals/EJP-ECP/_ejpecp/index.html

  1. Tight or sick building syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Thirumalaikolundusubramanian, P; Shanmuganadan, S [Madurai Kamaraj Univ. (India). Dept. of Geography; Uma, A [Madurai Medical Coll. (India). Dept. of Medicine and Microbiology

    1991-01-01

    Modern buildings are designed with the usual heating, air-conditioning and ventilation equipment. In most of these buildings, air is continuously recirculated and, as a result, workers suffer from tight or sick building syndrome. This syndrome is discussed with reference to symptoms of air contamination, ventilation system standards and research needs. The most common symptoms of tight building syndrome are eye, nose and throat irritation, headache, fatigue, sneezing, difficulty in wearing contact lenses, chest tightness, nausea, dizziness and dermatitis. Symptoms experienced by 50 doctors and 50 paramedical personnel working in an air-conditioned intensive care unit and operating theatres of the Government Rajaji Hospital, Madurai in India were studied by means of a questionnaire survey. In the present study, respiratory and ocular symptoms were observed more in those working in operating theatres and were believed to be due to excessive use of formaldehyde used for sterilization. Various suggestions were made to prevent sick building syndrome. Moreover, the physicians treating sick individuals should be aware of the symptoms caused by indoor air pollutants as sufferers invariably require a change of environment rather than drugs. (orig.).

  2. Evaluation of canister weld flaw depth for concrete storage cask

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Tae Chul; Cho, Chun Hyung [Korea Radioactive Waste Agency, Daejeon (Korea, Republic of); Jung, Sung Hun; Lee, Young Oh; Jung, In Su [Korea Nuclear Engineering and Service Corp, Daejeon (Korea, Republic of)

    2017-03-15

    Domestically developed concrete storage casks include an internal canister to maintain the confinement integrity of radioactive materials. In this study, we analyzed the depth of flaws caused by loads that propagate canister weld cracks under normal, off-normal and accident conditions, and evaluated the maximum allowable weld flaw depth needed to secure the structural integrity of the canister weld and to reduce the welding time of the internal canister lid of the concrete storage cask. Structural analyses for normal, off-normal and accident conditions were performed using the general-purpose finite element analysis program ABAQUS; the allowable flaw depth was assessed according to ASME B and PV Code Section XI. Evaluation results revealed an allowable canister weld flaw depth of 18.75 mm for the concrete storage cask, which satisfies the critical flaw depth recommended in NUREG-1536.

  3. Comparison of evaluation method for planar flaw in pressure tube

    International Nuclear Information System (INIS)

    Choi, Sung Nam; Kim, Hyung Nam; Yoo, Hyun Joo; Hwang, Won Gul

    2009-01-01

    CSA N285.4-94 requires the periodic inservice inspection and surveillance of pressure tubes in operating CANDU nuclear power reactors. If the inspection results reveal a flaw exceeding the acceptance criteria of the Code, the flaw must be evaluated to determine if the pressure is acceptable for continued service. Currently, the flaw evaluation methodology and acceptance criteria specified in CSA N285.8-05, 'Technical requirements for in-service evaluation of zirconium alloy pressure tubes in CANDU reactors'. The Code is applicable to zirconium alloy pressure tubes. The evaluation methodology for a crack-like flaw is similar to that of FFSG(Fitness For Service Guideline for Zirconium alloy pressure in operation CANDU) used now. The object of this paper is to address the fracture initiation and plastic collapse evaluation for the planar flaw as it applies to the pressure tube on Wolsong NPP.

  4. An interim report on shallow-flaw fracture technology development

    International Nuclear Information System (INIS)

    Pennell, W.E.; Bass, B.R.; Bryson, J.W.; McAfee, W.J.

    1995-01-01

    Shallow-flaw fracture technology is being developed for application to the safety assessment of radiation-embrittled nuclear reactor pressure vessels (RPVS) containing flaws. Fracture mechanics tests on RPV steel, coupled with detailed elastic-plastic finite-element analyses of the crack-tip stress fields, have shown that (1) constraint relaxation at the crack tip of shallow surface flaws results in increased data scatter but no increase in the lower-bound fracture toughness, (2) the nil ductility temperature (NDT) performs better than the reference temperature for nil ductility transition (RT NDT ) as a normalizing parameter for shallow-flaw fracture toughness data, (3) biaxial loading can reduce the shallow-flaw fracture toughness, (4) stress-based dual-parameter fracture toughness correlations cannot predict the effect of biaxial loading on shallow-flaw fracture toughness because in-plane stresses at the crack tip are not influenced by biaxial loading, and (5) a strain-based dual-parameter fracture toughness correlation can predict the effect of biaxial loading on shallow-flaw fracture toughness

  5. Thermal-shock experiments with flawed clad cylinders

    International Nuclear Information System (INIS)

    Cheverton, R.D.; Bryson, J.W.; Alexander, D.J.

    1989-01-01

    The life expectancy of LWR pressure vessels is influenced by a reduction in fracture toughness that is the result of radiation damage. As the fracture toughness decreases, the probability of propagation of preexisting flaws (sharp, crack-like defects) in the wall of the vessel increases. The probability of propagation is also influenced by the type of loading condition and the type of flaws that might exist. A loading condition of particular concern is referred to as pressurized thermal shock (PTS), and a flaw of particular concern for PTS loading conditions is a shallow surface flaw. A sudden cooling (thermal shock) of the inner surface of the vessel results in relatively high tensile stresses and relatively low fracture toughness at the inner surface. In addition, the attenuation of the fast-neutron fluence also results in relatively low fracture toughness at the inner surface. Under some circumstances, this combination of high stress and low toughness at the inner surface makes it possible for very shallow surface flaws to propagate. The PTS issue has been under investigation for quite some time, but thus far possible beneficial effects, other than thermal resistance, of the cladding on the inner surface of the vessel have not been included in the analysis of flaw behavior. This document discusses this effect of cladding on surface flaws and crack propagation

  6. Nuclear reactor pressure vessel-specific flaw distribution development

    International Nuclear Information System (INIS)

    Rosinski, S.T.

    1992-01-01

    Vessel integrity predictions performed through fracture mechanics analysis of a pressurized thermal shock event have been shown to be significantly sensitive to the overall flaw distribution input. It has also been shown that modem vessel in-service inspection (ISI) results can be used for development of vessel flaw distribution(s) that are more representative of US vessels. This paper describes the development and application of a methodology to analyze ISI data for the purpose of flaw distribution determination. The resultant methodology considers detection reliability, flaw sizing accuracy, and flaw detection threshold in its application. Application of the methodology was then demonstrated using four recently acquired US PWR vessel inspection data sets. Throughout the program, new insight was obtained into several key inspection performance and vessel integrity prediction practice issues that will impact future vessel integrity evaluation. For example, the potential application of a vessel-specific flaw distribution now provides at least one method by which a vessel-specific reference flaw size applicable to pressure-temperature limit curves determination can be estimated. This paper will discuss the development and application of the methodology and the impact to future vessel integrity analyses

  7. High-temperature flaw assessment procedure

    International Nuclear Information System (INIS)

    Ruggles, M.B.; Takahashi, Y.; Ainsworth, R.A.

    1989-08-01

    The current program represents a joint effort between the Electric Power Research Institute (EPRI) in the USA, the Central Research Institute of Electric Power Industry (CRIEPI) in Japan, and the Central Electricity Generating Board (CEGB) in the UK. The goal is to develop an interim high-temperature flaw assessment procedure for high-temperature reactor components. This is to be accomplished through exploratory experimental and analytical studies of high-temperature crack growth. The state-of-the-art assessment and the fracture mechanics database for both types 304 and 316 stainless steels, completed in 1988, serve as a foundation for the present work. Work in the three participating organizations is progressing roughly on schedule. Results to-date are presented in this document. Fundamental tests results are discussed in Section 2. Section 3 focuses on results of exploratory subcritical crack growth tests. Progress in subcritical crack growth modeling is reported in Section 4. Exploratory failure tests are outlined in Section 5. 21 refs., 70 figs., 7 tabs

  8. Flaws in the Concept of Nuclear Deterrance

    Directory of Open Access Journals (Sweden)

    John Scales Avery

    2012-04-01

    Full Text Available The concept of nuclear deterrence is seriously flawed, and it violates the fundamental ethical principles of all major religions. Besides being morally unacceptable, nuclear weapons are also illegal according to a historic 1996 decision of the International Court of Justice, a ruling that reflects the opinion of the vast majority of the worldʼs peoples. Even a small nuclear war would be an ecological catastrophe, not only killing civilian populations indiscriminately in both belligerent and neutral countries, but also severely damaging global agriculture and making large areas of the earth permanently uninhabitable through radioactive contamination. The danger of accidental nuclear war continues to be very great today, and the danger of nuclear terrorism is increasing. In this perilous situation, it is necessary for the nuclear nations to acknowledge that the concept of deterrence has been a mistake, which is threatening the lives of all human beings as well as threatening devastation of the biosphere. Acknowledging that the policy of nuclear deterrence has been a grave error can reduce risk of nuclear weapons proliferation.

  9. The behavior of shallow flaws in reactor pressure vessels

    International Nuclear Information System (INIS)

    Rolfe, S.T.

    1991-11-01

    Both analytical and experimental studies have shown that the effect of crack length, a, on the elastic-plastic toughness of structural steels is significant. The objective of this report is to recommend those research investigations that are necessary to understand the phenomenon of shallow behavior as it affects fracture toughness so that the results can be used properly in the structural margin assessment of reactor pressure vessels (RPVs) with flaws. Preliminary test results of A 533 B steel show an elevated crack-tip-opening displacement (CTOD) toughness similar to that observed for structural steels tested at the University of Kansas. Thus, the inherent resistance to fracture initiation of A 533 B steel with shallow flaws appears to be higher than that used in the current American Society of Mechanical Engineers (ASME) design curves based on testing fracture mechanics specimens with deep flaws. If this higher toughness of laboratory specimens with shallow flaws can be transferred to a higher resistance to failure in RPV design or analysis, then the actual margin of safety in nuclear vessels with shallow flaws would be greater than is currently assumed on the basis of deep-flaw test results. This elevation in toughness and greater resistance to fracture would be a very desirable situation, particularly for the pressurized-thermal shock (PTS) analysis in which shallow flaws are assumed to exist. Before any advantage can be taken of this possible increase in initiation toughness, numerous factors must be analyzed to ensure the transferability of the data. This report reviews those factors and makes recommendations of studies that are needed to assess the transferability of shallow-flaw toughness test results to the structural margin assessment of RPV with shallow flaws. 14 refs., 8 figs

  10. Analysis of portable gamma flaw detectors concerning radiation hygiene

    International Nuclear Information System (INIS)

    Makarova, T.V.

    1982-01-01

    Design and shields of gamma flaw detectors as one of the main factors responsible for personnel dose were studied. The analysis was conducted using the results of radiation hygienic surveys of gamma flaw detection laboratories functioning constantly in Estonia. It is shown that recently the replacement of GUP apparatuses by flaw detectors of RID and ''Gamma-RID'' (types which have design and shielding advantages is observed. However personnel doses have not reduced considerably for the last 10 years. This fact is attributed to design disadvantages of the RID and ''Gamma-RID'' apparatuses the removing of which will give the decreasing of annual personnel dose by 80 %

  11. Estimating probable flaw distributions in PWR steam generator tubes

    International Nuclear Information System (INIS)

    Gorman, J.A.; Turner, A.P.L.

    1997-01-01

    This paper describes methods for estimating the number and size distributions of flaws of various types in PWR steam generator tubes. These estimates are needed when calculating the probable primary to secondary leakage through steam generator tubes under postulated accidents such as severe core accidents and steam line breaks. The paper describes methods for two types of predictions: (1) the numbers of tubes with detectable flaws of various types as a function of time, and (2) the distributions in size of these flaws. Results are provided for hypothetical severely affected, moderately affected and lightly affected units. Discussion is provided regarding uncertainties and assumptions in the data and analyses

  12. Diagnosing the tight building syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, S.A.

    1987-12-01

    Formaldehyde is but one of many chemicals capable of causing the tight building syndrome or environmentally induced illness (EI). The spectrum of symptoms it may induce includes attacks of headache, flushing, laryngitis, dizziness, nausea, extreme weakness, arthralgia, unwarranted depression, dysphonia, exhaustion, inability to think clearly, arrhythmia or muscle spasms. The nonspecificity of such symptoms can baffle physicians from many specialties. Presented herein is a simple office method for demonstrating that formaldehyde is among the etiologic agents triggering these symptoms. The very symptoms that patients complain of can be provoked within minutes, and subsequently abolished, with an intradermal injection of the appropriate strength of formaldehyde. This injection aids in convincing the patient of the cause of the symptoms so he can initiate measure to bring his disease under control.

  13. Invasive tightly coupled processor arrays

    CERN Document Server

    LARI, VAHID

    2016-01-01

    This book introduces new massively parallel computer (MPSoC) architectures called invasive tightly coupled processor arrays. It proposes strategies, architecture designs, and programming interfaces for invasive TCPAs that allow invading and subsequently executing loop programs with strict requirements or guarantees of non-functional execution qualities such as performance, power consumption, and reliability. For the first time, such a configurable processor array architecture consisting of locally interconnected VLIW processing elements can be claimed by programs, either in full or in part, using the principle of invasive computing. Invasive TCPAs provide unprecedented energy efficiency for the parallel execution of nested loop programs by avoiding any global memory access such as GPUs and may even support loops with complex dependencies such as loop-carried dependencies that are not amenable to parallel execution on GPUs. For this purpose, the book proposes different invasion strategies for claiming a desire...

  14. Detection of plane, poorly oriented wide flaws using focused transducers

    International Nuclear Information System (INIS)

    Vadder, D. de; Azou, P.; Bastien, P.; Saglio, R.

    1976-01-01

    The detection of plane, poorly oriented, wide flaws by ultrasonic non destructive testing is distinctly improved when using focused transducers. An increased echo can be obtained crossing the defect limit [fr

  15. Ductile fracture of cylindrical vessels containing a large flaw

    Science.gov (United States)

    Erdogan, F.; Irwin, G. R.; Ratwani, M.

    1976-01-01

    The fracture process in pressurized cylindrical vessels containing a relatively large flaw is considered. The flaw is assumed to be a part-through or through meridional crack. The flaw geometry, the yield behavior of the material, and the internal pressure are assumed to be such that in the neighborhood of the flaw the cylinder wall undergoes large-scale plastic deformations. Thus, the problem falls outside the range of applicability of conventional brittle fracture theories. To study the problem, plasticity considerations are introduced into the shell theory through the assumptions of fully-yielded net ligaments using a plastic strip model. Then a ductile fracture criterion is developed which is based on the concept of net ligament plastic instability. A limited verification is attempted by comparing the theoretical predictions with some existing experimental results.

  16. Flaw evaluation of pressure vessel in pressurized water reactor

    International Nuclear Information System (INIS)

    Park, Ki Sung; Kim, Min Geol; Jeon, Chae Hong; Rhim, Soon Hyung; Kim, Seung Tae

    1999-01-01

    Flaw evaluation should be performed to determine the acceptance of a surface or a subsurface flaw detected during the in-service inspection without any repair or replacement. In this paper, the evaluation methodology and procedure were established according to ASME code Sec. XI and the evaluation program was coded. Using this program, a field engineer who doesn't have enough knowledge on fracture mechanics may be able to perform prompt and accurate flaw evaluation on site and decide whether a detected flaw be allowable or not. Analysis results were compared with those obtained from Westinghouse program called KCAL and FCG. Both results made good agreement and accuracy of the program developed in this paper was verified.=20

  17. Improved criteria for the repair of fabrication flaws

    International Nuclear Information System (INIS)

    Doctor, S.R.; Schuster, G.J.; Simonen, F.A.

    2003-01-01

    Section III of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code for nuclear power plant components requires radiographic examinations (RT) of welds and requires repairs for RT indications that exceed code acceptable sizes. This paper describes research that has generated data on welding flaws, which indicated that the largest flaws occur in repaired welds. The fabrication flaws were detected in material removed from cancelled nuclear power plants using high sensitivity Nondestructive Examination (NDE) and validated by complementary NDE and destructive testing. Evidence suggests that repairs are often for small and benign RT indications at locations buried within the vessel or pipe wall. Probabilistic fracture mechanics calculations are described in this paper to predict the increases in vessel failure probabilities caused by the repair-induced flaws. Calculations address failures of embrittled vessel welds for pressurized thermal shock (PTS) transients. In this case small flaws, which are relatively common, can cause brittle fracture, such that the rarely encountered repair flaws of large sizes gave only modestly increased failure probabilities. The paper recommends the use of more discriminating ultrasonic examinations in place of RT examinations along with repair criteria based on a fitness-for-purpose approach that minimize the number of unjustified repairs. (author)

  18. A study on the dimensioning of flaws by acoustical holography

    International Nuclear Information System (INIS)

    Yamamoto, Michio; Ando, Tomozumi; Enami, Koji; Yajima, Minoru; Fukui, Shigetaka.

    1978-01-01

    As a means of evaluating the safety of flawed pressure vessels and other structures against fracture, fracture mechanics has come to be applied. For the application of fracture mechanics it is necessary to get information concerning the sizes and shapes of flaws. The ultrasonic flaw detection method that is widely used as a nondestructive inspection method cannot measure the sizes and shapes of flaws accurately. Considering that acoustical holography is an useful means for the dimensioning of flaws, we performed basic tests on this method and obtained the following results: (1) The measured values of artificial flaws (flat bottom drilled holes: 5 - 36 mm) made on a steel plate of 150 mm thick showed a good linear relation with their actual sizes and scatter in the measured values was +-3 - 6 mm. (2) The measured values of fatigue cracks (length: 5 - 57 mm) introduced into a steel plate of 150 mm thick also showed a good linear relation with their actual sizes and scatter in the measured values was +-3 mm. (3) It was found that acoustical holography can also be applied to heavy section cast steels. (4) The method of correcting distortion caused by curved surface was investigated by computer-aided simulation and it was considered that such distortion can be corrected by radial scanning of a transducer. (author)

  19. Tightly Secure Signatures From Lossy Identification Schemes

    OpenAIRE

    Abdalla , Michel; Fouque , Pierre-Alain; Lyubashevsky , Vadim; Tibouchi , Mehdi

    2015-01-01

    International audience; In this paper, we present three digital signature schemes with tight security reductions in the random oracle model. Our first signature scheme is a particularly efficient version of the short exponent discrete log-based scheme of Girault et al. (J Cryptol 19(4):463–487, 2006). Our scheme has a tight reduction to the decisional short discrete logarithm problem, while still maintaining the non-tight reduction to the computational version of the problem upon which the or...

  20. Effect of combined loading on pipe flaw evaluation criteria

    International Nuclear Information System (INIS)

    Miura, Naoki; Chung Yeonki

    1999-01-01

    Considering a rational maintenance rule of Light Water Reactor piping, reliable flaw evaluation criteria are essential to determine how a detected flaw is detrimental to continuous plant operation. Ductile fracture is one of the dominant failure modes to be considered for carbon steel piping, and can be analyzed by the elastic-plastic fracture mechanics. Currently the analytical results are provided as flaw evaluation criteria using load correction factors such like the Z-factor in ASME Code Section 6. The present correction factors were conventionally determined taken a conservatism and a simplicity into account, however, the effect of internal pressure which would be an important factor under an actual plant condition was not adequately considered. Recently, a J-estimation scheme, 'LBB.ENGC' for ductile fracture analysis of circumferentially through-wall-cracked pipes subjected to combined loading was newly developed to have a better prediction with more realistic manner. This method is explicitly incorporated the contribution of both bending and tension due to internal pressure by means of the scheme compatible with an arbitrary combined loading history. In this paper, the effect of internal pressure on the flaw evaluation criteria was investigated using the new J-estimation scheme. A correction factor based on the new J-estimation scheme was compared with the present correction factors, and the predictability of the current flaw evaluation criteria was quantitatively evaluated in consideration of internal pressure. (author)

  1. Evaluation of flawed-pipe experiments: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Gamble, R.M.

    1986-11-01

    The purpose of this work was to perform elastic plastic fracture mechanics evaluations of experimental data that have become available from the NRC Degraded Pipe Program, Phase II (DPII) and other NRC and EPRI sponsored programs. These evaluations were used to assess flaw evaluation procedures for austenitic and ferritic steel piping. The results also have application to leak before break fracture mechanics analysis. An improved relationship was developed for computing the J-Integral for pipes containing throughwall flaws and loaded in pure bending. The results from several DPII experiments were compared to predictions based on new J estimation scheme solutions for circumferential, finite length part-throughwall flaws in pipes with bending loading. Comparisons of experimental maximum loads with those predicted using procedures in Paragraph IWB-3640, Section XI of the ASME Code indicate that the Code flaw evaluation procedures and allowables for austenitic steel pipe are appropriate and conservative. However, the comparisons also indicate that the base metal Code allowable loads may be about 15 to 20% high for small diameter piping (less than 8-inch diameter) at allowable a/t larger than about 0.5. The work further indicates that there is justification for reducing the conservatism in IWB-3640 allowable flaw sizes and loads for austenitic steel pipe with submerged or shielded metal arc welds.

  2. Steam and electroheating remediation of tight soils

    Energy Technology Data Exchange (ETDEWEB)

    Balshaw-Biddle, K.; Oubre, C.L.; Ward, C.H. [eds.; Dablow, J.F. III; Pearce, J.A.; Johnson, P.C.

    2000-07-01

    In the past few decades the need for soil remediation has become urgent, even more necessary--innovative, cost effective methods. Steam and Electroheating Remediation of Tight Soils presents the results of a field study testing the cleanup of semi-volatile fuels from tight soils using combination of hydraulic fracturing and soil heating technologies.

  3. Probabilistic assessment of critically flawed LMFBR PHTS piping elbows

    International Nuclear Information System (INIS)

    Balkey, K.R.; Wallace, I.T.; Vaurio, J.K.

    1982-01-01

    One of the important functions of the Primary Heat Transport System (PHTS) of a large Liquid Metal Fast Breeder Reactor (LMFBR) plant is to contain the circulating radioactive sodium in components and piping routed through inerted areas within the containment building. A significant possible failure mode of this vital system is the development of cracks in the piping components. This paper presents results from the probabilistic assessment of postulated flaws in the most-critical piping elbow of each piping leg. The criticality of calculated maximum sized flaws is assessed against an estimated material fracture toughness to determine safety factors and failure probability estimates using stress-strength interference theory. Subsequently, a different approach is also employed in which the randomness of the initial flaw size and loading are more-rigorously taken into account. This latter approach yields much smaller probability of failure values when compared to the stress-strength interference analysis results

  4. Detecting accuracy of flaws by manual and automatic ultrasonic inspections

    International Nuclear Information System (INIS)

    Iida, K.

    1988-01-01

    As the final stage work in the nine year project on proving tests of the ultrasonic inspection technique applied to the ISI of LWR plants, automatic ultrasonic inspection tests were carried out on EDM notches, surface fatigue cracks, weld defects and stress corrosion cracks, which were deliberately introduced in full size structural components simulating a 1,100 MWe BWR. Investigated items are the performance of a newly assembled automatic inspection apparatus, detection limit of flaws, detection resolution of adjacent collinear or parallel EDM notches, detection reproducibility and detection accuracy. The manual ultrasonic inspection of the same flaws as inspected by the automatic ultrasonic inspection was also carried out in order to have comparative data. This paper reports how it was confirmed that the automatic ultrasonic inspection is much superior to the manual inspection in the flaw detection rate and in the detection reproducibility

  5. Improved flaw detection and characterization with difference thermography

    Science.gov (United States)

    Winfree, William P.; Zalameda, Joseph N.; Howell, Patricia A.

    2011-05-01

    Flaw detection and characterization with thermographic techniques in graphite polymer composites is often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, variations in fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These variations result in a noise floor that increases the difficulty of detecting and characterizing deeper flaws. The paper investigates comparing thermographic responses taken before and after a change in state in a composite to improve the detection of subsurface flaws. A method is presented for registration of the responses before finding the difference. A significant improvement in the detectability is achieved by comparing the differences in response. Examples of changes in state due to application of a load and impact are presented.

  6. Statistical flaw strength distributions for glass fibres: Correlation between bundle test and AFM-derived flaw size density functions

    International Nuclear Information System (INIS)

    Foray, G.; Descamps-Mandine, A.; R’Mili, M.; Lamon, J.

    2012-01-01

    The present paper investigates glass fibre flaw size distributions. Two commercial fibre grades (HP and HD) mainly used in cement-based composite reinforcement were studied. Glass fibre fractography is a difficult and time consuming exercise, and thus is seldom carried out. An approach based on tensile tests on multifilament bundles and examination of the fibre surface by atomic force microscopy (AFM) was used. Bundles of more than 500 single filaments each were tested. Thus a statistically significant database of failure data was built up for the HP and HD glass fibres. Gaussian flaw distributions were derived from the filament tensile strength data or extracted from the AFM images. The two distributions were compared. Defect sizes computed from raw AFM images agreed reasonably well with those derived from tensile strength data. Finally, the pertinence of a Gaussian distribution was discussed. The alternative Pareto distribution provided a fair approximation when dealing with AFM flaw size.

  7. Advanced Signal Processing for Thermal Flaw Detection; TOPICAL

    International Nuclear Information System (INIS)

    VALLEY, MICHAEL T.; HANSCHE, BRUCE D.; PAEZ, THOMAS L.; URBINA, ANGEL; ASHBAUGH, DENNIS M.

    2001-01-01

    Dynamic thermography is a promising technology for inspecting metallic and composite structures used in high-consequence industries. However, the reliability and inspection sensitivity of this technology has historically been limited by the need for extensive operator experience and the use of human judgment and visual acuity to detect flaws in the large volume of infrared image data collected. To overcome these limitations new automated data analysis algorithms and software is needed. The primary objectives of this research effort were to develop a data processing methodology that is tied to the underlying physics, which reduces or removes the data interpretation requirements, and which eliminates the need to look at significant numbers of data frames to determine if a flaw is present. Considering the strengths and weakness of previous research efforts, this research elected to couple both the temporal and spatial attributes of the surface temperature. Of the possible algorithms investigated, the best performing was a radiance weighted root mean square Laplacian metric that included a multiplicative surface effect correction factor and a novel spatio-temporal parametric model for data smoothing. This metric demonstrated the potential for detecting flaws smaller than 0.075 inch in inspection areas on the order of one square foot. Included in this report is the development of a thermal imaging model, a weighted least squares thermal data smoothing algorithm, simulation and experimental flaw detection results, and an overview of the ATAC (Automated Thermal Analysis Code) software that was developed to analyze thermal inspection data

  8. Detecting and revising flaws in OWL object property expressions

    CSIR Research Space (South Africa)

    Keet, CM

    2012-10-01

    Full Text Available to the ontologist's intention. However, the more one can do, the higher the chance modelling flaws are introduced; hence, an unexpected or undesired classification or inconsistency may actually be due to a mistake in the object property box, not the class axioms. We...

  9. According to Jim: The Flawed Normal Curve of Intelligence

    Science.gov (United States)

    Gallagher, James J.

    2008-01-01

    In this article, the author talks about the normal curve of intelligence which he thinks is flawed and contends that wrong conclusions have been drawn based on this spurious normal curve. An example is that of racial and ethnic differences wherein some authors maintain that some ethnic and racial groups are clearly superior to others based on…

  10. Detecting and Preventing Type flaws at Static Time

    DEFF Research Database (Denmark)

    Bodei, Chiara; Brodo, Linda; Degano, Pierpaolo

    2010-01-01

    A type flaw attack on a security protocol is an attack where an honest principal is cheated on interpreting a field in a message as the one with a type other than the intended one. In this paper, we shall present an extension of the LYSA calculus to cope with types, by using tags to represent...

  11. Ultrasonic imaging of material flaws exploiting multipath information

    Science.gov (United States)

    Shen, Xizhong; Zhang, Yimin D.; Demirli, Ramazan; Amin, Moeness G.

    2011-05-01

    In this paper, we consider ultrasonic imaging for the visualization of flaws in a material. Ultrasonic imaging is a powerful nondestructive testing (NDT) tool which assesses material conditions via the detection, localization, and classification of flaws inside a structure. Multipath exploitations provide extended virtual array apertures and, in turn, enhance imaging capability beyond the limitation of traditional multisensor approaches. We utilize reflections of ultrasonic signals which occur when encountering different media and interior discontinuities. The waveforms observed at the physical as well as virtual sensors yield additional measurements corresponding to different aspect angles. Exploitation of multipath information addresses unique issues observed in ultrasonic imaging. (1) Utilization of physical and virtual sensors significantly extends the array aperture for image enhancement. (2) Multipath signals extend the angle of view of the narrow beamwidth of the ultrasound transducers, allowing improved visibility and array design flexibility. (3) Ultrasonic signals experience difficulty in penetrating a flaw, thus the aspect angle of the observation is limited unless access to other sides is available. The significant extension of the aperture makes it possible to yield flaw observation from multiple aspect angles. We show that data fusion of physical and virtual sensor data significantly improves the detection and localization performance. The effectiveness of the proposed multipath exploitation approach is demonstrated through experimental studies.

  12. Ultrasonic simulation studies for sizing of planar flaws in thick carbon steel welds

    International Nuclear Information System (INIS)

    Prakash, Alok

    2015-01-01

    Ultrasonic non-destructive testing typically involves detection of flaws that may affect the integrity of component under test. Once detected, the flaw is sized for its critical dimensions and its nature. The detection of flaw in the component by ultrasonic test is based on the principle of echo or reflection. Once the echo from a flaw is received, there are several approaches for analyzing the signal so that more and accurate information is obtained on the size of the flaw and its nature. The 6dB drop method is commonly used for sizing of flaws. This technique is based on determining the end points where the ultrasonic signal amplitude from the flaw drops to half of the peak amplitude. Though this method works well for large flaws whose size is larger than the beam width, it has a tendency to oversize the flaw which is smaller than the beam dimensions. In addition to beam divergence, flaw sizing also depends upon the orientation of the flaw with respect to incident sound beam. The paper describes the results of simulation studies on ultrasonic response from planar flaws of various orientations, their imaging and the methodology to be adopted for their accurate depth sizing. The paper also describes the experimental results to validate the flaw sizing approach

  13. Tight connection between fission gas discharge channels

    International Nuclear Information System (INIS)

    Jung, W.; Peehs, M.; Rau, P.; Krug, W.; Stechemesser, H.

    1978-01-01

    The invention is concerned with the tight connection between the fission gas discharge channel, leading away from the support plate of a gas-cooled reactor, and the top of the fuel element suspended from this support plate. The closure is designed to be gas-tight for the suspended as well as for the released fuel element. The tight connection has got an annular body resting on the core support plate in the mouth region of the fission gas discharge channel. This body is connected with the fission gas discharge channel in the fuel element top fitting via a gas-tight part and supported by a compression spring. Care is taken for sealing if the fuel element is removal. (RW) [de

  14. Applicability of Alignment and Combination Rules to Burst Pressure Prediction of Multiple-flawed Steam Generator Tube

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myeong Woo; Kim, Ji Seok; Kim, Yun Jae [Korea University, Seoul (Korea, Republic of); Jeon, Jun Young [Doosan Heavy Industries and Consruction, Seoul (Korea, Republic of); Lee, Dong Min [Korea Plant Service and Engineering, Technical Research and Development Institute, Naju (Korea, Republic of)

    2016-05-15

    Alignment and combination rules are provided by various codes and standards. These rules are used to determine whether multiple flaws should be treated as non-aligned or as coplanar, and independent or combined flaws. Experimental results on steam generator (SG) tube specimens containing multiple axial part-through-wall (PTW) flaws at room temperature (RT) are compared with assessment results based on the alignment and combination rules of the codes and standards. In case of axial collinear flaws, ASME, JSME, and BS7910 treated multiple flaws as independent flaws and API 579, A16, and FKM treated multiple flaws as combined single flaw. Assessment results of combined flaws were conservative. In case of axial non-aligned flaws, almost flaws were aligned and assessment results well correlate with experimental data. In case of axial parallel flaws, both effective flaw lengths of aligned flaws and separated flaws was are same because of each flaw length were same. This study investigates the applicability of alignment and combination rules for multiple flaws on the failure behavior of Alloy 690TT steam generator (SG) tubes that widely used in the nuclear power plan. Experimental data of burst tests on Alloy 690TT tubes with single and multiple flaws that conducted at room temperature (RT) by Kim el al. compared with the alignment rules of these codes and standards. Burst pressure of SG tubes with flaws are predicted using limit load solutions that provide by EPRI Handbook.

  15. Determination of K-factors for arbitrarily shaped flaws at pressure vessel nozzle corners

    International Nuclear Information System (INIS)

    Bryson, J.W.

    1979-01-01

    Photoelastic and finite element studies are being conducted to determine Mode I stress intensity factor distributions along arbitrarily shaped flaw fronts at pressure vessel nozzle corners. Comparisons of results from NOZ-FLAW, BIGIF, and the photoelastic studies showed that (1) good agreement was obtained between NOZ-FLAW and the photoelastically determined K 1 's for the deep flaw in an ITV model, (2) good agreement was obtained between NOZ-FLAW BIGIF for shallow and moderately deep flaws in a BWR model, and (3) less satisfactory agreement was obtained between NOZ- FLAW and the photoelastic results for the BWR models, particularly for moderately deep to deep flaws. Attempts are presently being made at understanding and explaining the discrepancies between the two

  16. On flaw tolerance of nacre: a theoretical study

    Science.gov (United States)

    Shao, Yue; Zhao, Hong-Ping; Feng, Xi-Qiao

    2014-01-01

    As a natural composite, nacre has an elegant staggered ‘brick-and-mortar’ microstructure consisting of mineral platelets glued by organic macromolecules, which endows the material with superior mechanical properties to achieve its biological functions. In this paper, a microstructure-based crack-bridging model is employed to investigate how the strength of nacre is affected by pre-existing structural defects. Our analysis demonstrates that owing to its special microstructure and the toughening effect of platelets, nacre has a superior flaw-tolerance feature. The maximal crack size that does not evidently reduce the tensile strength of nacre is up to tens of micrometres, about three orders higher than that of pure aragonite. Through dimensional analysis, a non-dimensional parameter is proposed to quantify the flaw-tolerance ability of nacreous materials in a wide range of structural parameters. This study provides us some inspirations for optimal design of advanced biomimetic composites. PMID:24402917

  17. Acoustic emission/flaw relationships for inservice monitoring of LWRs

    International Nuclear Information System (INIS)

    Hutton, P.H.; Kurtz, R.J.; Friesel, M.A.; Skorpik, J.R.; Dawson, J.F.

    1991-10-01

    The program concerning Acoustic Emission/Flaw Relationships for Inservice Monitoring of LWRs was initiated in FY76 with the objective of validating the application of acoustic emission (AE) to monitor nuclear reactor pressure-containing components during operation to detect cracking. The program has been supported by the US Nuclear Regulatory Commission, Office of Nuclear Regulatory Research. Research and development has been performed by Pacific Northwest Laboratory, operated for the Department of Energy by Battelle Memorial Institute. The program has shown the feasibility of continuous, on-line AE monitoring to detect crack growth and produced validated methods for applying the technology. Included are relationships for estimating flaw severity from AE data and field applications at Watts Bar Unit 1 Reactor, Limerick Unit 1 Reactor, and the High Flux Isotope Reactor. This report discusses the program scope and organization, the three program phases and the results obtained, standard and code activities, and instrumentation and software developed under this program

  18. Reconstructing flaw image using dataset of full matrix capture technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tae Hun; Kim, Yong Sik; Lee, Jeong Seok [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2017-02-15

    A conventional phased array ultrasonic system offers the ability to steer an ultrasonic beam by applying independent time delays of individual elements in the array and produce an ultrasonic image. In contrast, full matrix capture (FMC) is a data acquisition process that collects a complete matrix of A-scans from every possible independent transmit-receive combination in a phased array transducer and makes it possible to reconstruct various images that cannot be produced by conventional phased array with the post processing as well as images equivalent to a conventional phased array image. In this paper, a basic algorithm based on the LLL mode total focusing method (TFM) that can image crack type flaws is described. And this technique was applied to reconstruct flaw images from the FMC dataset obtained from the experiments and ultrasonic simulation.

  19. AE/flaw characterization for nuclear pressure vessels

    International Nuclear Information System (INIS)

    Hutton, P.H.; Kurtz, R.J.; Pappas, R.A.

    1984-01-01

    This chapter discusses the use of acoustic emission (AE) detected during continuous monitoring to identify and evaluate growing flaws in pressure vessels. Off-reactor testing and on-reactor testing are considered. Relationships for identifying acoustic emission (AE) from crack growth and using the AE data to estimate flaw severity have been developed experimentally by laboratory testing. The purpose of the off-reactor vessel test is to evaluate AE monitoring/interpretation methodology on a heavy section steel vessel under simulated reactor operating conditions. The purpose of on-reactor testing is to evaluate the capability of a monitor system to function in the reactor environment, calibrate the ability to detect AE signals, and to demonstrate that a meaningful criteria can be established to prevent false alarms. An expanded data base is needed from application testing and methodology standardization

  20. Probabilistic assessment of flaw evaluation procedures for pressure vessel integrity

    International Nuclear Information System (INIS)

    Shaffer, D.H.; Bamford, W.H.; Jouris, G.M.

    1980-01-01

    Prudent design procedures, in order to err in the direction of conservative over-strength rather than risky under-strength, have taken bounding values rather than best estimates for material parameters, and wherever possible, used conservative input for the calculations. The growing data base for this work is now beginning to allow an assessment of the conservatism that has been incorporated into the design procedure. Quantitative estimates of the variability associated with crack growth rates and fracture toughness have been generated in connection with other studies, and it would be useful to incorporate such information into an overall assessment of the design margins that are prescribed. In addition to getting an estimate of the conservatism in the current procedure, this study should provide a useful insight into the relative degree of margin that is introduced at each stage of the flaw evaluation process. Identification of the step by step margins should lead to more effective data collection programs from which information for adequately controlling the design conservatism can be obtained. The study will also provide valuable guidance in fixing revised design reference curves and safety factors so that adequate overall margins can be maintained without excess conservatism. This study is limited to vessel rupture in a brittle mode, and examples for illustration are particularly related to the beltline region of a reactor pressure vessel. The methodology, however, is applicable to all regions for which the required stress analyses, operating history, and material parameters are available. The work being carried out here is in consonance with ASME Section XI on Flaw Evaluation Procedures. It is concerned both with flaws under normal operating conditions and flaws under faulted conditions. (author)

  1. Recent changes in French flaw evaluation procedures: RSE-M

    Energy Technology Data Exchange (ETDEWEB)

    Faidy, C. [Electricite de France (EDF-SEPTEN), 69 - Villeurbanne (France)

    2001-07-01

    After a general presentation of the RSE-M, the French Code which describes the rules for in-service inspection of nuclear power plant components, this paper will be focused on the major new developments of the flaw evaluation procedure: critical crack size evaluation, material properties, safety factors and the major validation tasks done to support the RSE-M, edition 2000. The paper will conclude on on-going development in this area. (author)

  2. Recent changes in French flaw evaluation procedures: RSE-M

    International Nuclear Information System (INIS)

    Faidy, C.

    2001-01-01

    After a general presentation of the RSE-M, the French Code which describes the rules for in-service inspection of nuclear power plant components, this paper will be focused on the major new developments of the flaw evaluation procedure: critical crack size evaluation, material properties, safety factors and the major validation tasks done to support the RSE-M, edition 2000. The paper will conclude on on-going development in this area. (author)

  3. Development of automatic flaw detection systems for magnetic particle examination

    International Nuclear Information System (INIS)

    Shirai, T.; Kimura, J.; Amako, T.

    1988-01-01

    Utilizing a video camera and an image processor, development was carried out on automatic flaw detection and discrimination techniques for the purpose of achieving automated magnetic particle examination. Following this, fluorescent wet magnetic particle examination systems for blade roots and rotor grooves of turbine rotors and the non-fluorescent dry magnetic particle examination system for butt welds, were developed. This paper describes these automatic magnetic particle examination (MT) systems and the functional test results

  4. An introduction to finite tight frames

    CERN Document Server

    Waldron, Shayne F D

    2018-01-01

    This textbook is an introduction to the theory and applications of finite tight frames, an area that has developed rapidly in the last decade. Stimulating much of this growth are the applications of finite frames to diverse fields such as signal processing, quantum information theory, multivariate orthogonal polynomials, and remote sensing. Key features and topics: * First book entirely devoted to finite frames * Extensive exercises and MATLAB examples for classroom use * Important examples, such as harmonic and Heisenberg frames, are presented in preliminary chapters, encouraging readers to explore and develop an intuitive feeling for tight frames * Later chapters delve into general theory details and recent research results * Many illustrations showing the special aspects of the geometry of finite frames * Provides an overview of the field of finite tight frames * Discusses future research directions in the field Featuring exercises and MATLAB examples in each chapter, the book is well suited as a textbook ...

  5. Hermetic compartments leak-tightness enhancement

    International Nuclear Information System (INIS)

    Murani, J.

    2000-01-01

    In connection with the enhancement of the nuclear safety of the Jaslovske Bohunice V-1 NPP actions for the increase of the leak tightness are performed. The reconstruction has been done in the following directions: hermetic compartments leak tightness enhancement; air lock installation; installation of air lock in SP 4 vent system; integrated leakage rate test to hermetic compartments with leak detection. After 'major' leaks on the hermetic boundary components had been eliminated, since 1994 works on a higher qualitative level began. The essence of the works consists in the detection and identification of leaks in the structural component of the hermetic boundary during the planned refueling outages. The results of the Small Reconstruction and gradual enhancement of leak tightness are presented

  6. Estimation of Back-Surface Flaw Depth by Laminated Piezoelectric Highpolymer Film

    Directory of Open Access Journals (Sweden)

    Akinobu YAMAMOTO

    2009-08-01

    Full Text Available Piezoelectric thin films have been used to visualize back surface flaws in plates. If the plate with a surface flaw is deformed, the strain distribution appears on the other surface reflecting the location and the shape of the flaw. Such surface strain distribution can be transformed into the electric potential distribution on the piezoelectric film mounted on the plate surface. This paper deals with a NDE technique to estimate the depth of a back-surface flaw from the electric potential distribution on a laminated piezoelectric thin film. It is experimentally verified that the flaw depth can be exactly estimated by the peak height of the electric potential distribution.

  7. Modeling the X-ray Process, and X-ray Flaw Size Parameter for POD Studies

    Science.gov (United States)

    Koshti, Ajay M.

    2014-01-01

    Nondestructive evaluation (NDE) method reliability can be determined by a statistical flaw detection study called probability of detection (POD) study. In many instances, the NDE flaw detectability is given as a flaw size such as crack length. The flaw is either a crack or behaving like a crack in terms of affecting the structural integrity of the material. An alternate approach is to use a more complex flaw size parameter. The X-ray flaw size parameter, given here, takes into account many setup and geometric factors. The flaw size parameter relates to X-ray image contrast and is intended to have a monotonic correlation with the POD. Some factors such as set-up parameters, including X-ray energy, exposure, detector sensitivity, and material type that are not accounted for in the flaw size parameter may be accounted for in the technique calibration and controlled to meet certain quality requirements. The proposed flaw size parameter and the computer application described here give an alternate approach to conduct the POD studies. Results of the POD study can be applied to reliably detect small flaws through better assessment of effect of interaction between various geometric parameters on the flaw detectability. Moreover, a contrast simulation algorithm for a simple part-source-detector geometry using calibration data is also provided for the POD estimation.

  8. Approximate equiangular tight frames for compressed sensing and CDMA applications

    Science.gov (United States)

    Tsiligianni, Evaggelia; Kondi, Lisimachos P.; Katsaggelos, Aggelos K.

    2017-12-01

    Performance guarantees for recovery algorithms employed in sparse representations, and compressed sensing highlights the importance of incoherence. Optimal bounds of incoherence are attained by equiangular unit norm tight frames (ETFs). Although ETFs are important in many applications, they do not exist for all dimensions, while their construction has been proven extremely difficult. In this paper, we construct frames that are close to ETFs. According to results from frame and graph theory, the existence of an ETF depends on the existence of its signature matrix, that is, a symmetric matrix with certain structure and spectrum consisting of two distinct eigenvalues. We view the construction of a signature matrix as an inverse eigenvalue problem and propose a method that produces frames of any dimensions that are close to ETFs. Due to the achieved equiangularity property, the so obtained frames can be employed as spreading sequences in synchronous code-division multiple access (s-CDMA) systems, besides compressed sensing.

  9. The influence of finite-length flaw effects on PTS analyses

    International Nuclear Information System (INIS)

    Keeney-Walker, J.; Dickson, T.L.

    1993-01-01

    Current licensing issues within the nuclear industry dictate a need to investigate the effects of cladding on the extension of small finite-length cracks near the inside surface of a vessel. Because flaws having depths of the order of the combined clad and heat affected zone thickness dominate the frequency distribution of flaws, their initiation probabilities can govern calculated vessel failure probabilities. Current pressurized-thermal-shock (PTS) analysis computer programs recognize the influence of the inner-surface cladding layer in the heat transfer and stress analysis models, but assume the cladding fracture toughness is the same as that for the base material. The programs do not recognize the influence cladding may have in inhibiting crack initiation and propagation of shallow finite-length surface flaws. Limited experimental data and analyses indicate the cladding can inhibit the propagation of certain shallow flaws. This paper describes an analytical study which was carried out to determine (1) the minimum flaw depth for crack initiation under PTS loading for semicircular surface flaws in a clad reactor pressure vessel and (2) the impact, in terms of the conditional probability of vessel failure, of using a semicircular surface flaw as the initial flaw and assuming that the flaw cannot propagate in the cladding. The analytical results indicate that for initiation a much deeper critical crack depth is required for the finite-length flaw than for the infinite-length flaw, except for the least severe transient. The minimum flaw depths required for crack initiation from the finite-length flaw analyses were incorporated into a modified version of the OCA-P code. The modified code was applied to the analysis of selected PTS transients, and the results produced a substantial decrease in the conditional probability of failure. This initial study indicates a significant effect on probabilistic fracture analyses by incorporating finite-length flaw results

  10. Absolute tightness: the chemists hesitate to invest

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    The safety requirements of industries as nuclear plants and the strengthening of regulations in the field of environment (more particularly those related to volatile organic compounds) have lead the manufacturers to build absolute tightness pumps. But these equipments do not answer all the problems and represent a high investment cost. In consequence, the chemists hesitate to invest. (O.L.)

  11. Flaw distributions and use of ISI data in RPV integrity evaluations

    International Nuclear Information System (INIS)

    Dimitrijevic, V.; Ammirato, F.

    1993-01-01

    A probabilistic method for developing post-inspection flaw distributions has been developed that explicitly accounts for the capability of the inspection procedure to detect and size flaws. This methodology has been used to develop flaw distributions for calculating reactor vessel failure probability under postulated pressurized thermal shock (PTS) conditions. Realistic flaw distributions are important because plant-specific PTS safety assessments are very sensitive to assumptions made about major flaw parameters such as density, size, shape, and location. PTS analysis made in the past do not consider ISI. Two main reasons are (1) lack of a general and approved methodology which provides directions for involvement of ISI results in developing new flaw parameters and (2) lack of confidence in the capability of ISI procedures to detect critical flaws that may be present near the clad-to-base metal interface of the vessel, the location of most concern for PTS conditions. Recent developments in ISI practice, however, have led to substantial improvement in ISI capability and provide a basis for using ISI data to develop plant-specific post-inspection flaw distributions for vessel integrity evaluations. The key components of this evaluation are (1) the generic (preinspection) flaw distribution, (2) a probabilistic flaw detection model, and (3) Bayesian updating of the prior flaw distribution with the detection model to develop a post-inspection flaw distribution. Destructive analysis of RPV weld material was performed to develop data to support the pre-inspection flaw distributions. Since the probability of detection (POD) plays such an important role in the analysis and a high POD is needed to make significant reductions in probability of failure, a procedure was developed to achieve and demonstrate POD greater than 0.9 by using a combination of independent inspection techniques

  12. Ultrasonic signal processing for sizing under-clad flaws

    International Nuclear Information System (INIS)

    Shankar, R.; Paradiso, T.J.; Lane, S.S.; Quinn, J.R.

    1985-01-01

    Ultrasonic digital data were collected from underclad cracks in sample pressure vessel specimen blocks. These blocks were weld cladded under different processes to simulate actual conditions in US Pressure Water Reactors. Each crack was represented by a flaw-echo dynamic curve which is a plot of the transducer motion on the surface as a function of the ultrasonic response into the material. Crack depth sizing was performed by identifying in the dynamic curve the crack tip diffraction signals from the upper and lower tips. This paper describes the experimental procedure, digital signal processing methods used and algorithms developed for crack depth sizing

  13. Evaluation of flaws or service induced cracks in pressure vessels

    International Nuclear Information System (INIS)

    Riccardella, P.C.; Copeland, J.F.; Gilman, J.

    1987-01-01

    An overview of the ASME flaw evaluation procedures for nuclear pressure vessels is presented, with emphasis on fatigue crack growth evaluations. Environmental and load-rate effects are further considered with respect to new crack growth data and a time-dependent crack growth model. This new crack growth model is applied to evaluate feedwater nozzle cracking in boiling water reactors and is compared to current and past ASME crack growth curves. The time-dependent model bounds the observed cracking and indicates that more detailed consideration of material susceptibility, in terms of sulfur content and product form, is needed

  14. Windows Vista Kernel-Mode: Functions, Security Enhancements and Flaws

    Directory of Open Access Journals (Sweden)

    Mohammed D. ABDULMALIK

    2008-06-01

    Full Text Available Microsoft has made substantial enhancements to the kernel of the Microsoft Windows Vista operating system. Kernel improvements are significant because the kernel provides low-level operating system functions, including thread scheduling, interrupt and exception dispatching, multiprocessor synchronization, and a set of routines and basic objects.This paper describes some of the kernel security enhancements for 64-bit edition of Windows Vista. We also point out some weakness areas (flaws that can be attacked by malicious leading to compromising the kernel.

  15. MILITARY RESEARCH: Researchers Target Flaws in Ballistic Missile Defense Plan.

    Science.gov (United States)

    Malakoff, D; Cho, A

    2000-06-16

    More than three dozen scientists journeyed to Washington, D.C., this week to warn lawmakers that a proposed $60 billion U.S. missile defense system, designed to knock incoming warheads out of the sky, is technically flawed because it can't pick out real warheads from decoys. Pentagon officials heatedly deny a new report by one scientist that contractors have rigged trials to hide the problem, although they admit that some tests were simplified to save time. In the wake of these events, a leading Democrat is urging President Bill Clinton to delay a pending decision on building the system.

  16. Improving horizontal completions on heterogeneous tight shales

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Rivera, Roberto; Deenadayalu, Chaitanya; Chertov, Maxim; Novalo Hartanto, Ricardo; Gathogo, Patrick [Schlumberger (United States); Kunjir, Rahul [University of Utah (United States)

    2011-07-01

    Evaluation of the two formation characteristics conducive to economic well production is important when tight shale formation characterization and completion design are being considered. This paper presents the basic understanding required to improve the efficiency of horizontal completions in oil and gas producing shales. Guidelines are defined for effective perforation and fracturing to improve the efficiency and sustainability of horizontal completions using extensive laboratory characterization of mechanical properties on core, core/log integration and continuous mapping of these properties by logging-while-drilling (LWD) methods. The objective is to improve completion design efficiency. This is accomplished by suitable selection of perforation intervals based on an understanding of the relevant physical processes and rock characterization. Conditions at two reservoir regions, the near-wellbore and the far-wellbore, are outlined and are essential to completion design. From the study, it can be concluded that tight shales are strongly anisotropic and cannot be approximated using isotropic models.

  17. Tight fitting garter springs-MODAR

    Energy Technology Data Exchange (ETDEWEB)

    Kazimer, D. [Bruce Power, Tiverton, Ontario (Canada)

    2011-07-01

    Annulus spacers are used in CANDU reactors to maintain the annular gap between two tubes - an inner pressure tube (PT) and the outer calandria tube (CT). Typically four annulus spacers are used in one fuel channel assembly, each at a specified axial position. Bruce Unit 8 and many other CANDU units were constructed with tight-fitting garter springs (TFGS). The TFGS were not designed to be detected or relocated by the conventional tool, Spacer Location And Repositioning (SLAR) processes. Due to non-optimal 'As Left' construction locations for the Bruce Unit 8 TFGS, PT/CT contact has been predicted to occur well prior to its End of Life (EOL). Bruce Power entered a Project with AECL-CRL to design, manufacture and test and implement a new tooling system that would detect and reposition tight fitting annulus spacers. (author)

  18. Surface Passivation in Empirical Tight Binding

    OpenAIRE

    He, Yu; Tan, Yaohua; Jiang, Zhengping; Povolotskyi, Michael; Klimeck, Gerhard; Kubis, Tillmann

    2015-01-01

    Empirical Tight Binding (TB) methods are widely used in atomistic device simulations. Existing TB methods to passivate dangling bonds fall into two categories: 1) Method that explicitly includes passivation atoms is limited to passivation with atoms and small molecules only. 2) Method that implicitly incorporates passivation does not distinguish passivation atom types. This work introduces an implicit passivation method that is applicable to any passivation scenario with appropriate parameter...

  19. Equiangular tight frames and unistochastic matrices

    Czech Academy of Sciences Publication Activity Database

    Goyeneche, D.; Turek, Ondřej

    2017-01-01

    Roč. 50, č. 24 (2017), č. článku 245304. ISSN 1751-8113 R&D Projects: GA ČR GA17-01706S Institutional support: RVO:61389005 Keywords : equiangular tight frames * unistochastic matrices * SIC POVM Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 1.857, year: 2016

  20. Rotating flux-focusing eddy current probe for flaw detection

    Science.gov (United States)

    Wincheski, Russell A. (Inventor); Fulton, James P. (Inventor); Nath, Shridhar C. (Inventor); Simpson, John W. (Inventor); Namkung, Min (Inventor)

    1997-01-01

    A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks about circular fasteners and other circular inhomogeneities in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil, The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. By rotating the probe in a path around a circular fastener such as a rivet while maintaining a constant distance between the probe and the center of a rivet, the signal due to current flow about the rivet can be held constant. Any further changes in the current distribution, such as due to a fatigue crack at the rivet joint, can be detected as an increase in the output voltage above that due to the flow about the rivet head.

  1. Gun bore flaw image matching based on improved SIFT descriptor

    Science.gov (United States)

    Zeng, Luan; Xiong, Wei; Zhai, You

    2013-01-01

    In order to increase the operation speed and matching ability of SIFT algorithm, the SIFT descriptor and matching strategy are improved. First, a method of constructing feature descriptor based on sector area is proposed. By computing the gradients histogram of location bins which are parted into 6 sector areas, a descriptor with 48 dimensions is constituted. It can reduce the dimension of feature vector and decrease the complexity of structuring descriptor. Second, it introduce a strategy that partitions the circular region into 6 identical sector areas starting from the dominate orientation. Consequently, the computational complexity is reduced due to cancellation of rotation operation for the area. The experimental results indicate that comparing with the OpenCV SIFT arithmetic, the average matching speed of the new method increase by about 55.86%. The matching veracity can be increased even under some variation of view point, illumination, rotation, scale and out of focus. The new method got satisfied results in gun bore flaw image matching. Keywords: Metrology, Flaw image matching, Gun bore, Feature descriptor

  2. Stepped frequency imaging for flaw monitoring: Final report

    International Nuclear Information System (INIS)

    Hildebrand, B.P.

    1988-09-01

    This report summarizes the results of research into the usefulness of stepped frequency imaging (SFI) to nuclear power plant inspection. SFI is a method for producing ultrasonic holographic images without the need to sweep a two-dimensional aperture with the transducer. Instead, the transducer may be translated along a line. At each position of the transducer the frequency is stepped over a finite preselected bandwidth. The frequency stepped data is then processed to synthesize the second dimension. In this way it is possible to generate images in regions that are relatively inaccessible to two-dimensional scanners. This report reviews the theory and experimental work verifying the technique, and then explores its possible applications in the nuclear power industry. It also outlines how this new capability can be incorporated into the SDL-1000 Imaging System previously developed for EPRI. The report concludes with five suggestions for uses for the SFI method. These are: monitoring suspect or repaired regions of feedwater nozzles; monitoring pipe cracks repaired by weld overlay; monitoring crack depth during test block production; imaging flaws where access is difficult; and imaging flaws through cladding without distortion

  3. Amplitude-independent flaw length determination using differential eddy current

    Science.gov (United States)

    Shell, E.

    2013-01-01

    Military engine component manufacturers typically specify the eddy current (EC) inspection requirements as a crack length or depth with the assumption that the cracks in both the test specimens and inspected component are of a similar fixed aspect ratio. However, differential EC response amplitude is dependent on the area of the crack face, not the length or depth. Additionally, due to complex stresses, in-service cracks do not always grow in the assumed manner. It would be advantageous to use more of the information contained in the EC data to better determine the full profile of cracks independent of the fixed aspect ratio amplitude response curve. A specimen with narrow width notches is used to mimic cracks of varying aspect ratios in a controllable manner. The specimen notches have aspect ratios that vary from 1:1 to 10:1. Analysis routines have been developed using the shape of the EC response signals that can determine the length of a surface flaw of common orientations without use of the amplitude of the signal or any supporting traditional probability of detection basis. Combined with the relationship between signal amplitude and area, the depth of the flaw can also be calculated.

  4. A methodology for determining fabrication flaws in a reactor pressure vessel

    International Nuclear Information System (INIS)

    Schuster, G.J.; Doctor, S.R.; Simonen, F.A.

    1996-01-01

    The Pacific Northwest National Laboratory (PNNL) conducted a program with the major objective of estimating the rate of occurrence of fabrication flaws in US light-water reactor pressure vessels (RPVs). In this study, RPV mate4rial was examined using the Synthetic Aperture Focusing Technique for Ultrasonic Testing (SAFT-UT) to detect and characterize flaws created during fabrication. The inspection data obtained in this program has been analyzed to address the rates of flaw occurrence

  5. Radiation flaw detector for testing non-uniform surface bodies of revolution

    International Nuclear Information System (INIS)

    Valevich, M.I.

    1984-01-01

    Radiation flaw detector for testing bodies of revolution with non-uniform surface, welded joints, etc., based on spatial filtration and differentiation of ionizing radiation flux has been described. The calculation of the most important unit of flaw detector - integrators - is made. Experimental studies of the sensitivity have shown, that the radiation flaw detector can be used for rapid testing of products with the sensitivity comparable with the sensitivity of radiographic testing of steel

  6. Flaw-size measurement in a weld samples by ultrasonic frequency analysis

    International Nuclear Information System (INIS)

    Adler, L.; Cook, K.V.; Whaley, H.L. Jr.; McClung, R.W.

    1975-01-01

    An ultrasonic frequency-analysis technique was developed and applies to characterize flaws in an 8-in. (203-mm) thick heavy-section steel weld specimen. The technique applies a multitransducer system. The spectrum of the received broad-band signal is frequency analyzed at two different receivers for each of the flaws. From the two spectra, the size and orientation of the flaw are determined by the use of an analytic model proposed earlier. (auth)

  7. Method for the detection of flaws in a tube proximate a contiguous member

    International Nuclear Information System (INIS)

    Holt, A.E.; Wehrmeister, A.E.; Whaley, H.L.

    1979-01-01

    A method for deriving the eddy current signature of a flaw in a tube proximate a contiguous member which is obscured in a composite signature of the flaw and contiguous member comprises subtracting from the composite signature a reference eddy current signature generated by scanning a reference or facsimile tube and contiguous member. The method is particularly applicable to detecting flaws in the tubes of heat exchangers of fossil fuel and nuclear power plants to enable the detection of flaws which would otherwise be obscured by contiguous members such as support plates supporting the tubes. (U.K.)

  8. Bounding the conservatism in flaw-related variables for pressure vessel integrity analyses

    International Nuclear Information System (INIS)

    Foulds, J.R.; Kennedy, E.L.

    1993-01-01

    The fracture mechanics-based integrity analysis of a pressure vessel, whether performed deterministically or probabilistically, requires use of one or more flaw-related input variables, such as flaw size, number of flaws, flaw location, and flaw type. The specific values of these variables are generally selected with the intent to ensure conservative predictions of vessel integrity. These selected values, however, are largely independent of vessel-specific inspection results, or are, at best, deduced by ''conservative'' interpretation of vessel-specific inspection results without adequate consideration of the pertinent inspection system performance (reliability). In either case, the conservatism associated with the flaw-related variables chosen for analysis remains examination (NDE) technology and the recently formulated ASME Code procedures for qualifying NDE system capability and performance (as applied to selected nuclear power plant components) now provides a systematic means of bounding the conservatism in flaw-related input variables for pressure vessel integrity analyses. This is essentially achieved by establishing probabilistic (risk)-based limits on the assigned variable values, dependent upon the vessel inspection results and on the inspection system unreliability. Described herein is this probabilistic method and its potential application to: (i) defining a vessel-specific ''reference'' flaw for calculating pressure-temperature limit curves in the deterministic evaluation of pressurized water reactor (PWR) reactor vessels, and (ii) limiting the flaw distribution input to a PWR reactor vessel-specific, probabilistic integrity analysis for pressurized thermal shock loads

  9. Experimental verification on limit load estimation method for pipes with an arbitrary shaped circumferential surface flaw

    International Nuclear Information System (INIS)

    Li, Yinsheng; Hasegawa, Kunio; Miura, Naoki; Hoshino, Katsuaki

    2010-01-01

    When a flaw is detected in stainless steel pipes during in-service inspection, the limit load criterion given in the codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants or ASME Boiler and Pressure Vessel Code Section XI can be applied to evaluate the integrity of the pipe. However, in these codes, the limit load criterion is only provided for pipes containing a flaw with uniform depth, although many flaws with complicated shape such as stress corrosion cracking have been actually detected in pipes. In order to evaluate the integrity of the flawed pipes for general case, a limit load estimation method has been proposed by authors considering a circumferential surface flaw with arbitrary shape. The plastic collapse bending moment and corresponding stress are obtained by dividing the surface flaw into several segmented sub-flaws. In this paper, the proposed method was verified by comparing with experimental results. Four-point bending experiments were carried out for full scale stainless steel pipes with a symmetrical or non-symmetrical circumferential flaw. Estimated failure bending moments by the proposed method were found to be in good agreement with the experimental results, and the proposed method was confirmed to be effective for evaluating bending failure of pipes with flaw. (author)

  10. Breakdown pressures and characteristic flaw sizes during fluid injection experiments in shale at elevated confining pressures.

    Science.gov (United States)

    Chandler, M.; Mecklenburgh, J.; Rutter, E. H.; Taylor, R.; Fauchille, A. L.; Ma, L.; Lee, P. D.

    2017-12-01

    Fracture propagation trajectories in gas-bearing shales depend on the interaction between the anisotropic mechanical properties of the shale and the anisotropic in-situ stress field. However, there is a general paucity of available experimental data on their anisotropic mechanical, physical and fluid-flow properties, especially at elevated confining pressures. A suite of mechanical, flow and elastic measurements have been made on two shale materials, the Whitby mudrock and the Mancos shale (an interbedded silt and mudstone), as well as Pennant sandstone, an isotropic baseline and tight-gas sandstone analogue. Mechanical characterization includes standard triaxial experiments, pressure-dependent permeability, brazilian disk tensile strength, and fracture toughness determined using double-torsion experiments. Elastic characterisation was performed through ultrasonic velocities determined using a cross-correlation method. Additionally, we report the results of laboratory-scale fluid injection experiments for the same materials. Injection experiments involved the pressurisation of a blind-ending central hole in a dry cylindrical sample. Pressurisation is conducted under constant volume-rate control, using silicon oils of varying viscosities. Breakdown pressure is not seen to exhibit a strong dependence on rock type or orientation, and increases linearly with confining pressure. In most experiments, a small drop in the injection pressure record is observed at what is taken to be fracture initiation, and in the Pennant sandstone this is accompanied by a small burst of acoustic energy. The shale materials were acoustically quiet. Breakdown is found to be rapid and uncontrollable after initiation if injection is continued. A simplified 2-dimensional model for explaining this is presented in terms of the stress intensities at the tip of a pressurised crack, and is used alongside the triaxial data to derive a characteristic flaw size from which the fractures have initiated

  11. Device for providing a leak-tight penetration for electric cables through a reactor vault roof

    International Nuclear Information System (INIS)

    Eyral, M.; Mahe, A.

    1979-01-01

    The device for providing a cable penetration through the vault roof of a liquid sodium cooled fast reactor comprises a vertical tube closed at the top end by a flange-plate. Electric cables connected to measuring and detecting instruments are passed through the flange-plate which is joined to the reactor vault roof in leak-tight manner and enclosed within a removable hood. At least one horizontal plate is mounted within the vertical tube and provided with orifices for the leak-tight passage of the cables. Cable storage reels are placed within the tube and can be locked in position or released by controlled mechanical means

  12. Tight Reference Frame–Independent Quantum Teleportation

    Directory of Open Access Journals (Sweden)

    Dominic Verdon

    2017-01-01

    Full Text Available We give a tight scheme for teleporting a quantum state between two parties whose reference frames are misaligned by an action of a finite symmetry group. Unlike previously proposed schemes, ours requires no additional tokens or data to be passed between the participants; the same amount of classical information is transferred as for ordinary quantum teleportation, and the Hilbert space of the entangled resource is of the same size. In the terminology of Peres and Scudo, our protocol relies on classical communication of unspeakable information.

  13. Tightly sealed facility of excellent in durability

    International Nuclear Information System (INIS)

    Shirano, Kenji; Chatani, Michio; Ebe, Shinji; Shimizu, Masatoshi; Seguchi, Tadao; Fukushima, Susumu; Hirata, Masaru; Shiosawa, Ken-ichi.

    1992-01-01

    It is found that a cross linked methacryl resin using an appropriate amount of a cross linking monomer also has a useful characteristic of an excellent chemical resistance and excellent γ-ray resistance. Then in the present invention, a cross linked methacryl resin molding product comprising 60 to 98 % by weight of methyl methacrylate units and 2 to 40 % by weight of cross linking monomer units is used as a material for transparent partition walls. A tightly sealed facility having the transparent partition wall materials of excellent radiation resistance in addition to acid resistance can be attained. (T.M.)

  14. Accomplishments: AE characterization program for remote flaw evaluation

    International Nuclear Information System (INIS)

    Hutton, P.H.; Schwenk, E.B.; Kurtz, R.J.

    1978-01-01

    The purpose of the program is to develop an experimental/analytical evaluation of the feasibility of detecting and analyzing flaw growth in reactor pressure boundaries by means of continuously monitoring acoustic emission (AE). The investigation is devoted exclusively to ASTM Type A533, Grade B, Class 1 material. The basic approach to interpretive model development is through laboratory testing of 1 to 1 1 / 2 inch (25.4 to 38 mm) thick fracture mechanics specimens in both fatigue and fracture at both room temperature and 550 0 F (288 0 C). Seven parameters are measured for each AE signal and related to fracture mechanics functions. AE data from fracture testing of 6 inch (152 mm) wall pressure vessels are also incorporated in analysis

  15. Design Flaws and Service System Breakdowns: Learning from Systems Thinking

    Directory of Open Access Journals (Sweden)

    David Ing

    2014-12-01

    Full Text Available In what ways might systems thinking be helpful to designers?  In the 21st century, the types of project with which designers have become engaged has expanded to include service systems.  Service systems are typically composites of mechanisms, organisms, human beings and ecologies.  Systems thinking is a perspective with theories, methods and practices that enables transcending disciplinary boundaries.  Application of systems thinking in designing a service system can aid in surfacing potential flaws and/or anticipating future breakdowns in functions, structures and/or processes. Designers and systems thinkers should work together to improve the nature of service systems.  As a starter set into these conversations, seven conditions are proposed as a starting context.  These conditions are presented neither as rigourously defined nor as exhaustive, but as an entry point into future joint engagement.

  16. 'Moral distress'--time to abandon a flawed nursing construct?

    Science.gov (United States)

    Johnstone, Megan-Jane; Hutchinson, Alison

    2015-02-01

    Moral distress has been characterised in the nursing literature as a major problem affecting nurses in all healthcare systems. It has been portrayed as threatening the integrity of nurses and ultimately the quality of patient care. However, nursing discourse on moral distress is not without controversy. The notion itself is conceptually flawed and suffers from both theoretical and practical difficulties. Nursing research investigating moral distress is also problematic on account of being methodologically weak and disparate. Moreover, the ultimate purpose and significance of the research is unclear. In light of these considerations, it is contended that the notion of moral distress ought to be abandoned and that concerted attention be given to advancing inquiries that are more conducive to improving the quality and safety of moral decision-making, moral conduct and moral outcomes in nursing and healthcare domains. © The Author(s) 2013.

  17. China’s Flawed Banking Market Structure Must be Rectified

    Institute of Scientific and Technical Information of China (English)

    于永臻

    2007-01-01

    There is great disparity between China’s banking management efficiency and the top international standard,with relatively low efficiency in credit monetary allocation.In this paper,Yu Yongzhen sets out the hypothesis that"medium-sized banks promote competition".He believes that an important reason for the low efficiency of Chinese banking is the seriously flawed banking market structure.Namely,credit market shares are highly concentrated in the hands of the four major state-owned banks,with very few shares held by medium-sized banks or the badly undeveloped small banks.Full development of medium-sized banks plays a key role in the promotion of competition and efficiency in banking.

  18. Profitable failure: antidepressant drugs and the triumph of flawed experiments.

    Science.gov (United States)

    McGoey, Linsey

    2010-01-01

    Drawing on an analysis of Irving Kirsch and colleagues' controversial 2008 article in "PLoS [Public Library of Science] Magazine" on the efficacy of SSRI antidepressant drugs such as Prozac, I examine flaws within the methodologies of randomized controlled trials (RCTs) that have made it difficult for regulators, clinicians and patients to determine the therapeutic value of this class of drug. I then argue, drawing analogies to work by Pierre Bourdieu and Michael Power, that it is the very limitations of RCTs -- their inadequacies in producing reliable evidence of clinical effects -- that help to strengthen assumptions of their superiority as methodological tools. Finally, I suggest that the case of RCTs helps to explore the question of why failure is often useful in consolidating the authority of those who have presided over that failure, and why systems widely recognized to be ineffective tend to assume greater authority at the very moment when people speak of their malfunction.

  19. An corrective method to correct of the inherent flaw of the asynchronization direct counting circuit

    International Nuclear Information System (INIS)

    Wang Renfei; Liu Congzhan; Jin Yongjie; Zhang Zhi; Li Yanguo

    2003-01-01

    As a inherent flaw of the Asynchronization Direct Counting Circuit, the crosstalk, which is resulted from the randomicity of the time-signal always exists between two adjacent channels. In order to reduce the counting error derived from the crosstalk, the author propose an effective method to correct the flaw after analysing the mechanism of the crosstalk

  20. Advances in flaw evaluation procedures and acceptance criteria for reactor piping

    International Nuclear Information System (INIS)

    Gamble, R.M.; Zahoor, A.; Norris, D.M.

    1986-01-01

    During the past several years, intergranular stress corrosion cracks (IGSCC) have been detected in stainless steel piping in boiling water reactors (BWRs) and have resulted in an increased number of flaw evaluations. To reduce the outage time associated with evaluating IGSCC, various research and ASME code groups have spent significant effort to provide utility personnel with efficient means to detect, classify, and size flaws, and to determine suitability for return to service for flawed stainless steel piping. One of the several nondestructive evaluation technologies that has received considerable attention is fracture mechanics, the discipline that considers the failure of flawed material. Fracture mechanics can be used to answer two key questions concerning return to service of flawed pipe: (a) what is the largest flaw size that can be returned to service and still maintain adequate safety margins at the applied loads, and (b) how much operating time remains before the crack reaches the largest allowable size? The purpose of this paper is to provide an overview of the recently developed ASME code Section XI flaw size evaluation procedure and acceptance criteria for stainless steel piping and their application by BWR owners to efficiently determine if flaws found by nondestructive examination are acceptable for continued service

  1. Advances in flaw evaluation procedures and acceptance criteria for reactor piping

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, R.M.; Zahoor, A.; Norris, D.M.

    1986-01-01

    During the past several years, intergranular stress corrosion cracks (IGSCC) have been detected in stainless steel piping in boiling water reactors (BWRs) and have resulted in an increased number of flaw evaluations. To reduce the outage time associated with evaluating IGSCC, various research and ASME code groups have spent significant effort to provide utility personnel with efficient means to detect, classify, and size flaws, and to determine suitability for return to service for flawed stainless steel piping. One of the several nondestructive evaluation technologies that has received considerable attention is fracture mechanics, the discipline that considers the failure of flawed material. Fracture mechanics can be used to answer two key questions concerning return to service of flawed pipe: (a) what is the largest flaw size that can be returned to service and still maintain adequate safety margins at the applied loads, and (b) how much operating time remains before the crack reaches the largest allowable size. The purpose of this paper is to provide an overview of the recently developed ASME code Section XI flaw size evaluation procedure and acceptance criteria for stainless steel piping and their application by BWR owners to efficiently determine if flaws found by nondestructive examination are acceptable for continued service.

  2. Feasibility study on application of volume acid fracturing technology to tight gas carbonate reservoir development

    Directory of Open Access Journals (Sweden)

    Nianyin Li

    2015-09-01

    Full Text Available How to effectively develop tight-gas carbonate reservoir and achieve high recovery is always a problem for the oil and gas industry. To solve this problem, domestic petroleum engineers use the combination of the successful experiences of North American shale gas pools development by stimulated reservoir volume (SRV fracturing with the research achievements of Chinese tight gas development by acid fracturing to propose volume acid fracturing technology for fractured tight-gas carbonate reservoir, which has achieved a good stimulation effect in the pilot tests. To determine what reservoir conditions are suitable to carry out volume acid fracturing, this paper firstly introduces volume acid fracturing technology by giving the stimulation mechanism and technical ideas, and initially analyzes the feasibility by the comparison of reservoir characteristics of shale gas with tight-gas carbonate. Then, this paper analyzes the validity and limitation of the volume acid fracturing technology via the analyses of control conditions for volume acid fracturing in reservoir fracturing performance, natural fracture, horizontal principal stress difference, orientation of in-situ stress and natural fracture, and gives the solution for the limitation. The study results show that the volume acid fracturing process can be used to greatly improve the flow environment of tight-gas carbonate reservoir and increase production; the incremental or stimulation response is closely related with reservoir fracturing performance, the degree of development of natural fracture, the small intersection angle between hydraulic fracture and natural fracture, the large horizontal principal stress difference is easy to form a narrow fracture zone, and it is disadvantageous to create fracture network, but the degradable fiber diversion technology may largely weaken the disadvantage. The practices indicate that the application of volume acid fracturing process to the tight-gas carbonate

  3. Development of an Intelligent Ultrasonic Signature Classification Software for Discrimination of Flaws in Weldments

    International Nuclear Information System (INIS)

    Kim, H. J.; Song, S. J.; Jeong, H. D.

    1997-01-01

    Ultrasonic pattern recognition is the most effective approach to the problem of discriminating types of flaws in weldments based on ultrasonic flaw signals. In spite of significant progress in the research on this methodology, it has not been widely used in many practical ultrasonic inspections of weldments in industry. Hence, for the convenient application of this approach in many practical situations, we develop an intelligent ultrasonic signature classification software which can discriminate types of flaws in weldments based on their ultrasonic signals using various tools in artificial intelligence such as neural networks. This software shows the excellent performance in an experimental problem where flaws in weldments are classified into two categories of cracks and non-cracks. This performance demonstrates the high possibility of this software as a practical tool for ultrasonic flaw classification in weldments

  4. Ultrasonic Transducer Design for the Axial Flaw Detection of Dissimilar Metal Weld

    International Nuclear Information System (INIS)

    Yoon, Byung Sik; Kim, Yong Sik; Yang, Seung Han

    2011-01-01

    Dissimilar metal welds in nuclear power plant are known as very susceptible to PWSCC flaws, and periodically inspected by the qualified inspector and qualified procedure during in-service inspection period. According to field survey data, the majority of their DMWs are located on tapered nozzle or adjacent to a tapered component. These types of configurations restrict examination access and also limit examination volume coverage. Additionally, circumferential scan for axially oriented flaw is very difficult to detect located on tapered surface because the transducer can't receive flaw response from reflector for miss-orientation. To overcome this miss-orientation, it is necessary adapt skewed ultrasonic transducer accommodate tapered surface. The skewed refracted longitudinal ultrasonic transducer designed by modeling and manufactured from the modelling result for axial flaw detection. Experimental results showed that the skewed refracted longitudinal ultrasonic transducer get higher flaw response than non-skewed refracted longitudinal ultrasonic transducer

  5. Development of technology on natural flaw fabrication and precise diagnosis for the major components in NPPs

    International Nuclear Information System (INIS)

    Han, Jung Ho; Choi, Myung Sik; Lee, Doek Hyun; Hur, Do Haeng

    2002-01-01

    The objective of this research is to develop a fabrication technology of natural flaw specimen of major components in NPPs and a technology of precise diagnosis for failure and degradation of components using natural flaw specimen. 1) Successful development of the natural flaw fabrication technology of SG tube 2) Evaluation of ECT signal and development of precise diagnosis using natural flaws. - Determination of length, depth, width, and multiplicity of fabricated natural flaws. - Informations about detectability and accuracy of ECT evaluation on various kinds of defects are collected when the combination of probe and frequency is changed. - An advanced technology for precise ECT evaluation is established. 3) Application of precise ECT diagnosis to failure analysis of SG tube in operation. - Fretting wear of KSNP SG. - ODSCC at tube expanded region of KSNP SG. - Determination of through/non-through wall of axial crack

  6. Estimation of the number of physical flaws from periodic ISI data of SG tubes using effective POD

    International Nuclear Information System (INIS)

    Lee, Jae Bong; Park, Jai Hak; Kim, Hong Deok; Chung, Han Sub

    2008-01-01

    It is necessary to know the number of flaws and their size distribution in order to calculate the probability of failure or to estimate the amount of leakage through the tube wall of steam generators. But In-Service Inspection (ISI) flaw data is different from the physical flaw data. In case of a single inspection, it is easy to estimate the number of physical flaws using the POD curve. However, we may be faced with some difficulties in obtaining the number of physical flaws from the periodic in-service inspection data. In this study a method for estimating the number of physical flaws from periodic in-service inspection data is proposed. In order to calculate the number of physical flaws with periodic ISI data, both probabilities of detecting and missing flaws should be considered. And flaw initiation and growth history must be known also. The flaw initiation and growth history can be inferred from appropriate probabilistic flaw growth rate. Two inference methods are proposed and compared. One is Monte Carlo simulation method and the other is transition (stochastic) matrix method. The effective POD, the total possibility of detection considering both probabilities of detecting and missing flaws for each flaw size, can be calculated using above two inference methods. And two methods are compared and the usefulness and convenience are evaluated from several applications

  7. Evaluation of Effect by Internal Flow on Ultrasonic Testing Flaw Sizing in Piping

    International Nuclear Information System (INIS)

    Lee, Jeong Seok; Yoon, Byung Sik; Kim, Yong Sik

    2013-01-01

    In this study, the ultrasonic amplitude difference between air filled and water filled piping in nuclear power plant is compared by modeling approach. In this study, ultrasonic amplitude differences between air and water filled pipe are evaluated by modeling approach. Consequently, we propose the following results. The ultrasonic amplitude difference between air and water filled condition is measured by lower than 1 dB in modeling calculation. The flaw length sizing error between air and water filled condition shows same results based on 12 dB drop method even thought the amplitude difference is 1 dB. Most of the piping welds in nuclear power plants are inspected periodically using ultrasonic techniques to detect service-induced flaws such as IGSCC cracking. The inspection results provide information such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these information. Specially, the amplitude of flaw response is very important to estimate the flaw size. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing methodology. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error

  8. Equiangular tight frames and unistochastic matrices

    International Nuclear Information System (INIS)

    Goyeneche, Dardo; Turek, Ondřej

    2017-01-01

    We demonstrate that a complex equiangular tight frame composed of N vectors in dimension d , denoted ETF ( d , N ), exists if and only if a certain bistochastic matrix, univocally determined by N and d , belongs to a special class of unistochastic matrices. This connection allows us to find new complex ETFs in infinitely many dimensions and to derive a method to introduce non-trivial free parameters in ETFs. We present an explicit six-parametric family of complex ETF(6,16), which defines a family of symmetric POVMs. Minimal and maximal possible average entanglement of the vectors within this qubit–qutrit family are described. Furthermore, we propose an efficient numerical procedure to compute the unitary matrix underlying a unistochastic matrix, which we apply to find all existing classes of complex ETFs containing up to 20 vectors. (paper)

  9. Evaluation of tight-pitch PWR cores

    International Nuclear Information System (INIS)

    Correa, F.; Driscoll, M.J.; Lanning, D.D.

    1979-08-01

    The impact of tight pinch cores on the consumption of natural uranium ore has been evaluated for two systems of coupled PWR's namely one particular type of thorium system - 235 U/UO 2 : Pu/ThO 2 : 233 U/ThO 2 - and the conventional recycle-mode uranium system - 235 U/UO 2 : Pu/UO 2 . The basic parameter varied was the fuel-to-moderator volume ratio (F/M) of the (uniform) lattice for the last core in each sequence. Although methods and data verification in the range of present interest, 0.5 (current lattices) 1.0, the EPRI-LEOPARD and LASER programs used for the thorium and uranium calculations, respectively, were successfully benchmarked against several of the more pertinent experiments

  10. Surface Passivation in Empirical Tight Binding

    Science.gov (United States)

    He, Yu; Tan, Yaohua; Jiang, Zhengping; Povolotskyi, Michael; Klimeck, Gerhard; Kubis, Tillmann

    2016-03-01

    Empirical Tight Binding (TB) methods are widely used in atomistic device simulations. Existing TB methods to passivate dangling bonds fall into two categories: 1) Method that explicitly includes passivation atoms is limited to passivation with atoms and small molecules only. 2) Method that implicitly incorporates passivation does not distinguish passivation atom types. This work introduces an implicit passivation method that is applicable to any passivation scenario with appropriate parameters. This method is applied to a Si quantum well and a Si ultra-thin body transistor oxidized with SiO2 in several oxidation configurations. Comparison with ab-initio results and experiments verifies the presented method. Oxidation configurations that severely hamper the transistor performance are identified. It is also shown that the commonly used implicit H atom passivation overestimates the transistor performance.

  11. Naturally fractured tight gas reservoir detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-06-01

    Building upon the partitioning of the Greater Green River Basin (GGRB) that was conducted last quarter, the goal of the work this quarter has been to conclude evaluation of the Stratos well and the prototypical Green River Deep partition, and perform the fill resource evaluation of the Upper Cretaceous tight gas play, with the goal of defining target areas of enhanced natural fracturing. The work plan for the quarter of November 1-December 31, 1998 comprised four tasks: (1) Evaluation of the Green River Deep partition and the Stratos well and examination of potential opportunity for expanding the use of E and P technology to low permeability, naturally fractured gas reservoirs, (2) Gas field studies, and (3) Resource analysis of the balance of the partitions.

  12. Random walks and polygons in tight confinement

    International Nuclear Information System (INIS)

    Diao, Y; Ernst, C; Ziegler, U

    2014-01-01

    We discuss the effect of confinement on the topology and geometry of tightly confined random walks and polygons. Here the walks and polygons are confined in a sphere of radius R ≥ 1/2 and the polygons are equilateral with n edges of unit length. We illustrate numerically that for a fixed length of random polygons the knotting probability increases to one as the radius decreases to 1/2. We also demonstrate that for random polygons (walks) the curvature increases to πn (π(n – 1)) as the radius approaches 1/2 and that the torsion decreases to ≈ πn/3 (≈ π(n – 1)/3). In addition we show the effect of length and confinement on the average crossing number of a random polygon

  13. Tight gas sand tax credit yields opportunities

    International Nuclear Information System (INIS)

    Lewis, F.W.; Osburn, A.S.

    1991-01-01

    The U.S. Internal Revenue Service on Apr. 1, 1991, released the inflation adjustments used in the calculations of Non-Conventional Fuel Tax Credits for 1990. The inflation adjustment, 1.6730, when applied to the base price of $3/bbl of oil equivalent, adjusts the tax credit to $5.019/bbl for oil and 86.53 cents/MMBTU for gas. The conversion factor for equivalent fuels is 5.8 MMBTU/bbl. Unfortunately, the tax credit for tight formation gas continues to be unadjusted for inflation and remains 52 cents/MMBTU. As many producers are aware, the Omnibus Budget Reconciliation Act of 1990 expanded the dates of eligibility and the usage for-Non-Conventional Fuel Tax Credits. Among other provisions, eligible wells may be placed in service until Jan. 1, 1992, and once in place may utilize the credit for production through Dec. 31, 2002. Both dates are 2 year extensions from previous regulations

  14. Formation and ridging of flaw leads in the eastern Canadian Beaufort Sea. Special Session C06 on: “Physical, biological and biogeochemical processes associated with young thin ice types”

    Science.gov (United States)

    Prinsenberg, S. J.

    2009-12-01

    Formation and ridging of flaw leads in the eastern Canadian Beaufort Sea. Simon Prinsenberg1 and Yves Graton2 1Bedford Inst. of Oceanography, Fisheries and Oceans Canada P.O. Box1006, Dartmouth, Nova Scotia, B2Y 4A2, Canada prinsenbergs@mar.dfo-mpo.gc.ca 2Inst. National de la Recherche Scientifique-Eau, INRS-ETE University of Quebec at Quebec City, Quebec yvesgratton@eteinrs.ca During the winter of 2008, the flaw lead south of Banks Island repeatedly opened and closed representing an elongated region where periodically the large ice growth stimulates the densification of the surface layer due to salt rejection and instigates a local circulation pattern that will affect the biological processes of the region. Helicopter-borne sensors were available to monitor the aftermath of one of the rapid closing of the flaw lead into extensive elongated rubble field using a Canadian Ice breaker, CCGS Amundsen, as a logistic base. After the wind reversed a new open flaw lead 20km wide restarting a new flaw lead formation cycle. Ice thickness and surface roughness data were collected from the rubble field and adjacent open flaw lead with an Electromagnetic-Laser system. The strong wind event of April 4-5 2009 generated a large linear 1.5km wide ice rubble field up to 8-10m thick when the 60cm thick, 18km wide flaw lead was crunched into land-fast by the 1.5m thick offshore pack ice. It is expected that during rapid ice growth in a flaw lead, salt rejection increase the density of the surface water layer producing a surface depression (Low) and cyclonic circulation. In contrast at depth, the extra surface dense water produces a high in the horizontal pressure field and anti-cyclonic circulation which remains after the rapid ice growth within the flaw lead stops. One of such remnants may have been observed during the CFL-IPY winter survey.

  15. Microstructure, flaw tolerance, and reliability of Ce-TZP and Y-TZP ceramics

    International Nuclear Information System (INIS)

    Readey, M.J.; McCallen, C.L.

    1995-01-01

    Ce-TZP and Y-TZP ceramics were heat-treated for various times and temperatures in order to vary the microstructure. Flaw tolerance was investigated using the indentation-strength test. Reliability was quantified using conventional two-parameter Weibull statistics. Some Ce-TZP specimens were indented at slightly elevated temperatures where no transformation was observed. Results indicated that the Ce-TZP specimens were extremely flaw tolerant, and showed a relatively high Weibull modulus that scaled with both R-curve behavior and flaw tolerance. Y-TZP, on the other hand, with very little if any R-curve behavior or flaw tolerance, had a low Weibull modulus. The results also show that flaw history, i.e., whether or not a transformation zone exists along the wake of the crack, has a significant influence on strength. Strength was much less dependent on initial crack size when the crack had an associated transformation zone, whereas strength was highly dependent on cracks typical of natural processing defects. It is argued that the improvement in reliability, flaw tolerance, and dependence on flaw history are all ramifications of pronounced R-curve behavior

  16. Development of an intelligent system for ultrasonic flaw classification in weldments

    International Nuclear Information System (INIS)

    Song, Sung-Jin; Kim, Hak-Joon; Cho, Hyeon

    2002-01-01

    Even though ultrasonic pattern recognition is considered as the most effective and promising approach to flaw classification in weldments, its application to the realistic field inspection is still very limited due to the crucial barriers in cost, time and reliability. To reduce such barriers, previously we have proposed an intelligent system approach that consisted of the following four ingredients: (1) a PC-based ultrasonic testing (PC-UT) system; (2) an effective invariant ultrasonic flaw classification algorithm; (3) an intelligent flaw classification software; and (4) a database with abundant experimental flaw signals. In the present work, for performing the ultrasonic flaw classification in weldments in a real-time fashion in many real word situations, we develop an intelligent system, which is called the 'Intelligent Ultrasonic Evaluation System (IUES)' by the integration of the above four ingredients into a single, unified system. In addition, for the improvement of classification accuracy of flaws, especially slag inclusions, we expand the feature set by adding new informative features, and demonstrate the enhanced performance of the IUES with flaw signals in the database constructed previously. And then, to take care of the increased redundancy in the feature set due to the addition of features, we also propose two efficient schemes for feature selection: the forward selection with trial and error, and the forward selection with criteria of the error probability and the linear correlation coefficients of individual features

  17. Detection and Characterization of Flaws in Sprayed on Foam Insulation with Pulsed Terahertz Frequency Electromagnetic Waves

    Science.gov (United States)

    Winfree, William P.; Madaras, Eric I.

    2005-01-01

    The detection and repair of flaws such as voids and delaminations in the sprayed on foam insulation of the external tank reduces the probability of foam debris during shuttle ascent. The low density of sprayed on foam insulation along with it other physical properties makes detection of flaws difficult with conventional techniques. An emerging technology that has application for quantitative evaluation of flaws in the foam is pulsed electromagnetic waves at terahertz frequencies. The short wavelengths of these terahertz pulses make them ideal for imaging flaws in the foam. This paper examines the application of terahertz pulses for flaw detection in foam characteristic of the foam insulation of the external tank. Of particular interest is the detection of voids and delaminations, encapsulated in the foam or at the interface between the foam and a metal backing. The technique is shown to be capable of imaging small voids and delaminations through as much as 20 cm of foam. Methods for reducing the temporal responses of the terahertz pulses to improve flaw detection and yield quantitative characterizations of the size and location of the flaws are discussed.

  18. Variable flaw shape analysis for a reactor vessel under pressurized thermal shock loading

    International Nuclear Information System (INIS)

    Yang, C.Y.; Bamford, W.H.

    1984-01-01

    A study has been conducted to characterize the response of semi-elliptic surface flaws to thermal shock conditions which can result from safety injection actuation in nuclear reactor vessels. A methodology was developed to predict the behavior of a flaw during sample pressurized thermal shock events. The effects of a number of key variables on the flaw propagation were studied, including fracture toughness of the material and its gradient through the thickness, irradiation effects, effects of warm prestressing, and effects of the stainless steel cladding. The results of these studies show that under thermal shock loading conditions the flaw always tends to elongate along the vessel inside surface from the initial aspect ratio. However, the flaw shape always remains finite rather than becoming continuously long, as has often been assumed in earlier analyses. The final shape and size of the flaws were found to be rather strongly dependent on the effects of warm prestressing and the distribution of neutron flux. The improved methodology results in a more accurate and more realistic treatment of flaw shape changes during thermal shock events and provides the potential for quantifying additional margins for reactor vessel integrity analyses

  19. Self-propelled x-ray flaw detector

    International Nuclear Information System (INIS)

    Ershov, L.S.; Krasilnikov, S.B.; Lozovoi, L.N.; Losev, J.F.; Morgovsky, L.Y.; Pelix, E.A.; Khakimyanov, R.R.

    1988-01-01

    A self-propelled X-ray flaw detector for radiographic inspection of welded joints in pipelines comprises a carriage mounting a motor, a detector having two Geiger counters, a pulsed X-ray generator, and an exposure and carriage electronic control system. A memory unit in the control system has four storage elements containing information about the motion of the carriage. As the carriage moves in direction A, first one and then the other of the Geiger counters receives radiation from an isotope source positioned near a joint, and by means of logic circuitry in the control system, the information in the storage elements is modified to stop the carriage and to operate a timer to expose the weld. During exposure the X-rays may interfere with the information in the storage elements, but by means of a square-wave generator and the logic circuitry, the stored information is correctly reset in order to eliminate false operation of the memory unit. (author)

  20. Enron Flaws In Organizational Architecture And Its Failure

    Directory of Open Access Journals (Sweden)

    Nguyen

    2015-08-01

    Full Text Available A series of corporate scandals at the beginning of last decade has given rise to the doubt on the efficiency of corporate governance practice in the United States. Of these scandals the collapse of Enron has exceptionally captured the public concern. It was the once seventh-largest company in the United States 1. It was rated the most innovative large company in America in Fortunes Most Admired Companies survey 2. In August 2000 its stock reached a peak of nearly 70 billion 3. However within a year its stock had become almost useless papers 2. It just was unbelievable for many people. What went wrong Was it due to the failure of corporate governance in general Actually the central factor leading to the collapse of Enron was the failure in its organizational architecture. This paper starts by providing an overview of corporate governance system with an emphasis on the corporate organizational architecture as its important facet. Then it discusses flaws in the organizational architecture of Enron and argues that these eventually led to the breakdown of the whole corporate governance system at Enron. Finally some implications and lessons for the practice of corporate governance are presented.

  1. Flaw assessment procedure for high temperature reactor components

    International Nuclear Information System (INIS)

    Ainsworth, R.A.; Takahashi, Y.

    1990-01-01

    An interim high-temperature flaw assessment procedure is described. This is a result of a collaborative effort between Electric Power Research Institute in the USA, Central Research Institute of Electric Power Industry in Japan, and Nuclear Electric plc in the UK. The procedure addresses preexisting defects subject to creep-fatigue loading conditions. Laws employed to calculate the crack growth per cycle are defined in terms of fracture mechanics parameters and constants related to the component material. The crack growth laws may be integrated to calculate the remaining life of a component or to predict the amount of crack extension in a given period. Fatigue and creep crack growth per cycle are calculated separately, and the total crack extension is taken as the simple sum of the two contributions. An interaction between the two propagation modes is accounted for in the material properties in the separate calculations. In producing the procedure, limitations of the approach have been identified. Some of these limitations are to be addressed in an extension of the current collaborative program. 20 refs

  2. Design of Friction Stir Welding Tool for Avoiding Root Flaws.

    Science.gov (United States)

    Ji, Shude; Xing, Jingwei; Yue, Yumei; Ma, Yinan; Zhang, Liguo; Gao, Shuangsheng

    2013-12-12

    In order to improve material flow behavior during friction stir welding and avoid root flaws of weld, a tool with a half-screw pin and a tool with a tapered-flute pin are suggested. The effect of flute geometry in tool pins on material flow velocity is investigated by the software ANSYS FLUENT. Numerical simulation results show that high material flow velocity appears near the rotational tool and material flow velocity rapidly decreases with the increase of distance away from the axis of the tool. Maximum material flow velocity by the tool with the tapered-flute pin appears at the beginning position of flute and the velocity decreases with the increase of flow length in flute. From the view of increasing the flow velocity of material near the bottom of the workpiece or in the middle of workpiece, the tool with the half-screw pin and the tool with the tapered-flute pin are both better than the conventional tool.

  3. Global Coal Trade. From Tightness to Oversupply

    International Nuclear Information System (INIS)

    Cornot-Gandolphe, Sylvie

    2013-01-01

    Over the past four years, international coal trade has been reshaped by China's surging imports. China, which was still a net exporter in 2008, became the world's first coal importer in 2011, taking over the position that Japan has occupied for three decades. Its imports have continued their rising trend and reached a record level in 2012, despite the country's economic slowdown. China imported 289 million tons of coal in 2012, up 30% over 2011. It now accounts for 23% of global imports. Although China is the world's largest coal producer, several factors have contributed to the sudden rise in its imports, including the higher cost of domestic coal relative to international prices and bottlenecks in transporting domestic coal to south-eastern provinces. More recently, another event shook the international coal business: the United States have been back on the market. The collapse of U.S. gas prices, to $4/million Btu in 2011 and even $2.75/million Btu in 2012, linked with the 'shale gas revolution', has made coal uncompetitive in the electricity sector, its main outlet on the U.S. market. U.S. coal demand dropped 4% in 2011 and 11% in 2012. The reduction in domestic demand has forced U.S. miners to look for overseas outlets. Their exports surged by 31% in 2011 and 16% in 2012. They reached 112 million tons in 2012, more than twice the level of 2009. The United States, which almost disappeared from the international steam coal market in the 2000's, have regained a larger share of the total coal export market, 9% in 2012, against 6% in 2009. These developments, although not directly linked, have a huge impact on the global market and pricing of coal. Chinese imports have helped the market to quickly recover from its low level of 2008-2009. The speed and magnitude of China's coal imports even shifts the market from a sluggish to a tight situation. Prices started to rise after their collapse in the second half of 2008 caused by the economic and financial crisis

  4. Cracking and Failure in Rock Specimen Containing Combined Flaw and Hole under Uniaxial Compression

    Directory of Open Access Journals (Sweden)

    Xiang Fan

    2018-01-01

    Full Text Available Flaw is a key factor influencing failure behavior of a fractured specimen. In the present study, rectangular-flawed specimens were prepared using sandstone to investigate the effect of flaw on failure behavior of rock. Open flaw and cylindrical hole were simultaneously precut within rock specimens using high-pressure water jet cutting technology. Five series of specimens including intact, single-hole-alone, two-hole-alone, single-hole and two-flaw, and two-hole and single-flaw blocks were prepared. Uniaxial compressive tests using a rigid servo control instrument were carried out to investigate the fracture processes of these flawed specimens. It is observed that during loading, internal stress always intensively distributed at both sidewalls of open hole, especially at midpoint of sidewalls, so rock crumb flaking was firstly observed among all sandstone specimens containing single hole or two holes. Cracking around open hole is associated with the flaw inclination angle which was observed in Series III and V. Crack easily initiated at the tips of flaw with inclination angles of 0°, 30°, and 60° but hard for 90° in Series III and V. Rock burst was the major failure mode among most tested specimens, which generally induced new cracks and finally created crater shape. Additionally, due to extrusion between blocks, new shear or tensile cracks were generated and the rock specimen surface spalled. Eventually, four typical failure processes including rock crumb flaking, crack initiation and propagation, rock burst, and second rupture, were summarized.

  5. Comparison of three flaw-location methods for automated ultrasonic testing

    International Nuclear Information System (INIS)

    Seiger, H.

    1982-01-01

    Two well-known methods for locating flaws by measurement of the transit time of ultrasonic pulses are examined theoretically. It is shown that neither is sufficiently reliable for use in automated ultrasonic testing. A third method, which takes into account the shape of the sound field from the probe and the uncertainty in measurement of probe-flaw distance and probe position, is introduced. An experimental comparison of the three methods indicates that use of the advanced method results in more accurate location of flaws. (author)

  6. Behavior of deep flaws in a thick-wall cylinder under thermal shock loading

    International Nuclear Information System (INIS)

    Cheverton, R.D.

    1979-01-01

    Behavior of inner-surface flaws in thick-walled vessels was studied in a 991-mm OD x 152 mm wall x 1220 mm length cylinder with toughness properties similar to those for HSST Plate. The initial temperature of 93 0 C and a thermal shock medium of liquid nitrogen (-197 0 C) were employed. The initial flaw selected was a sharp, 16 mm deep, long (1220 mm) axial crack. Crack arrest methodology was shown to be valid for deep flaws under severe thermal shock

  7. Tightness Entropic Uncertainty Relation in Quantum Markovian-Davies Environment

    Science.gov (United States)

    Zhang, Jun; Liu, Liang; Han, Yan

    2018-05-01

    In this paper, we investigate the tightness of entropic uncertainty relation in the absence (presence) of the quantum memory which the memory particle being weakly coupled to a decohering Davies-type Markovian environment. The results show that the tightness of the quantum uncertainty relation can be controlled by the energy relaxation time F, the dephasing time G and the rescaled temperature p, the perfect tightness can be arrived by dephasing and energy relaxation satisfying F = 2G and p = 1/2. In addition, the tightness of the memory-assisted entropic uncertainty relation and the entropic uncertainty relation can be influenced mainly by the purity. While in memory-assisted model, the purity and quantum correlation can also influence the tightness actively while the quantum entanglement can influence the tightness slightly.

  8. Improved Density Functional Tight Binding Potentials for Metalloid Aluminum Clusters

    Science.gov (United States)

    2016-06-01

    unlimited IMPROVED DENSITY-FUNCTIONAL TIGHT BINDING POTENTIALS FOR METALLOID ALUMINUM CLUSTERS by Joon H. Kim June 2016 Thesis Advisor...DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE IMPROVED DENSITY-FUNCTIONAL TIGHT BINDING POTENTIALS FOR METALLOID ALUMINUM CLUSTERS 5. FUNDING...repulsive potentials for use in density-functional tight binding (DFTB) simulations of low-valence aluminum metalloid clusters . These systems are under

  9. Naturally fractured tight gas reservoir detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-04-30

    In March, work continued on characterizing probabilities for determining natural fracturing associated with the GGRB for the Upper Cretaceous tight gas plays. Structural complexity, based on potential field data and remote sensing data was completed. A resource estimate for the Frontier and Mesa Verde play was also completed. Further, work was also conducted to determine threshold economics for the play based on limited current production in the plays in the Wamsutter Ridge area. These analyses culminated in a presentation at FETC on 24 March 1999 where quantified natural fracture domains, mapped on a partition basis, which establish ''sweet spot'' probability for natural fracturing, were reviewed. That presentation is reproduced here as Appendix 1. The work plan for the quarter of January 1, 1999--March 31, 1999 comprised five tasks: (1) Evaluation of the GGRB partitions for structural complexity that can be associated with natural fractures, (2) Continued resource analysis of the balance of the partitions to determine areas with higher relative gas richness, (3) Gas field studies, (4) Threshold resource economics to determine which partitions would be the most prospective, and (5) Examination of the area around the Table Rock 4H well.

  10. Potential evaluation of CO2 storage and enhanced oil recovery of tight oil reservoir in the Ordos Basin, China.

    Science.gov (United States)

    Tian, Xiaofeng; Cheng, Linsong; Cao, Renyi; Zhang, Miaoyi; Guo, Qiang; Wang, Yimin; Zhang, Jian; Cui, Yu

    2015-07-01

    Carbon -di-oxide (CO2) is regarded as the most important greenhouse gas to accelerate climate change and ocean acidification. The Chinese government is seeking methods to reduce anthropogenic CO2 gas emission. CO2 capture and geological storage is one of the main methods. In addition, injecting CO2 is also an effective method to replenish formation energy in developing tight oil reservoirs. However, exiting methods to estimate CO2 storage capacity are all based on the material balance theory. This was absolutely correct for normal reservoirs. However, as natural fractures widely exist in tight oil reservoirs and majority of them are vertical ones, tight oil reservoirs are not close. Therefore, material balance theory is not adaptive. In the present study, a new method to calculate CO2 storage capacity is presented. The CO2 effective storage capacity, in this new method, consisted of free CO2, CO2 dissolved in oil and CO2 dissolved in water. Case studies of tight oil reservoir from Ordos Basin was conducted and it was found that due to far lower viscosity of CO2 and larger solubility in oil, CO2 could flow in tight oil reservoirs more easily. As a result, injecting CO2 in tight oil reservoirs could obviously enhance sweep efficiency by 24.5% and oil recovery efficiency by 7.5%. CO2 effective storage capacity of Chang 7 tight oil reservoir in Longdong area was 1.88 x 10(7) t. The Chang 7 tight oil reservoir in Ordos Basin was estimated to be 6.38 x 10(11) t. As tight oil reservoirs were widely distributed in Songliao Basin, Sichuan Basin and so on, geological storage capacity of CO2 in China is potential.

  11. The use of fracture mechanics for the evaluation of NDE flaw acceptance standards

    Energy Technology Data Exchange (ETDEWEB)

    Alicino, A; Capurro, E; Ansaldo, Sp; Corvi, A [Ansaldo SpA, Genoa (Italy)

    1988-12-31

    This document deals with the use of fracture mechanics criteria to evaluate the Non Destructive Examination (NDE) flaw acceptance standards. The communication discusses the general schemes and the guidelines of the activity carried out. (TEC).

  12. Fracture behaviour assessment of a flawed pressure vessel in the hydro-test

    Energy Technology Data Exchange (ETDEWEB)

    Sarkimo, M; Rintamac, R

    1988-12-31

    This document deals with the fracture properties of a flawed pressure vessel. The experiment was carried out within the Nordic Countries on a vessel in a Finnish refinery. The instrumentation used included acoustic emission. Some results are provided. (TEC).

  13. Calculation and evaluation methodology of the flawed pipe and the compute program development

    International Nuclear Information System (INIS)

    Liu Chang; Qian Hao; Yao Weida; Liang Xingyun

    2013-01-01

    Background: The crack will grow gradually under alternating load for a pressurized pipe, whereas the load is less than the fatigue strength limit. Purpose: Both calculation and evaluation methodology for a flawed pipe that have been detected during in-service inspection is elaborated here base on the Elastic Plastic Fracture Mechanics (EPFM) criteria. Methods: In the compute, the depth and length interaction of a flaw has been considered and a compute program is developed per Visual C++. Results: The fluctuating load of the Reactor Coolant System transients, the initial flaw shape, the initial flaw orientation are all accounted here. Conclusions: The calculation and evaluation methodology here is an important basis for continue working or not. (authors)

  14. Development of a shallow-flaw fracture assessment methodology for nuclear reactor pressure vessels

    International Nuclear Information System (INIS)

    Bass, B.R.; Bryson, J.W.; Dickson, T.L.; McAfee, W.J.; Pennell, W.E.

    1996-01-01

    Shallow-flaw fracture technology is being developed within the Heavy-Section Steel Technology (HSST) Program for application to the safety assessment of radiation-embrittled nuclear reactor pressure vessels (RPVs) containing postulated shallow flaws. Cleavage fracture in shallow-flaw cruciform beam specimens tested under biaxial loading at temperatures in the lower transition temperature range was shown to be strain-controlled. A strain-based dual-parameter fracture toughness correlation was developed and shown to be capable of predicting the effect of crack-tip constraint on fracture toughness for strain-controlled fracture. A probabilistic fracture mechanics (PFM) model that includes both the properties of the inner-surface stainless-steel cladding and a biaxial shallow-flaw fracture toughness correlation gave a reduction in probability of cleavage initiation of more than two orders of magnitude from an ASME-based reference case

  15. Digital Rock Studies of Tight Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Silin, Dmitriy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-07

    This technical report summarizes some recently developed approaches to studies of rock properties at a pore scale. Digital rock approach is complementary to laboratory and field studies. It can be especially helpful in situations where experimental data are uncertain, or are difficult or impossible to obtain. Digitized binary images of the pore geometries of natural rocks obtained by different imaging techniques are the input data. Computer-generated models of natural rocks can be used instead of images in a case where microtomography data are unavailable, or the resolution of the tools is insufficient to adequately characterize the features of interest. Simulations of creeping viscous flow in pores produce estimates of Darcy permeability. Maximal Inscribed Spheres calculations estimate two-phase fluid distribution in capillary equilibrium. A combination of both produce relative permeability curves. Computer-generated rock models were employed to study two-phase properties of fractured rocks, or tight sands with slit-like pores, too narrow to be characterized with micro-tomography. Various scenarios can simulate different fluid displacement mechanisms, from piston-like drainage to liquid dropout at the dew point. A finite differences discretization of Stokes equation is developed to simulate flow in the pore space of natural rocks. The numerical schemes are capable to handle both no-slip and slippage flows. An upscaling procedure estimates the permeability by subsampling a large data set. Capillary equilibrium and capillary pressure curves are efficiently estimated with the method of maximal inscribed spheres both an arbitrary contact angle. The algorithms can handle gigobytes of data on a desktop workstation. Customized QuickHull algorithms model natural rocks. Capillary pressure curves evaluated from computer-generated images mimic those obtained for microtomography data.

  16. US production of natural gas from tight reservoirs

    International Nuclear Information System (INIS)

    1993-01-01

    For the purposes of this report, tight gas reservoirs are defined as those that meet the Federal Energy Regulatory Commission's (FERC) definition of tight. They are generally characterized by an average reservoir rock permeability to gas of 0.1 millidarcy or less and, absent artificial stimulation of production, by production rates that do not exceed 5 barrels of oil per day and certain specified daily volumes of gas which increase with the depth of the reservoir. All of the statistics presented in this report pertain to wells that have been classified, from 1978 through 1991, as tight according to the FERC; i.e., they are ''legally tight'' reservoirs. Additional production from ''geologically tight'' reservoirs that have not been classified tight according to the FERC rules has been excluded. This category includes all producing wells drilled into legally designated tight gas reservoirs prior to 1978 and all producing wells drilled into physically tight gas reservoirs that have not been designated legally tight. Therefore, all gas production referenced herein is eligible for the Section 29 tax credit. Although the qualification period for the credit expired at the end of 1992, wells that were spudded (began to be drilled) between 1978 and May 1988, and from November 5, 1990, through year end 1992, are eligible for the tax credit for a subsequent period of 10 years. This report updates the EIA's tight gas production information through 1991 and considers further the history and effect on tight gas production of the Federal Government's regulatory and tax policy actions. It also provides some high points of the geologic background needed to understand the nature and location of low-permeability reservoirs

  17. Vector fields in a tight laser focus: comparison of models.

    Science.gov (United States)

    Peatross, Justin; Berrondo, Manuel; Smith, Dallas; Ware, Michael

    2017-06-26

    We assess several widely used vector models of a Gaussian laser beam in the context of more accurate vector diffraction integration. For the analysis, we present a streamlined derivation of the vector fields of a uniformly polarized beam reflected from an ideal parabolic mirror, both inside and outside of the resulting focus. This exact solution to Maxwell's equations, first developed in 1920 by V. S. Ignatovsky, is highly relevant to high-intensity laser experiments since the boundary conditions at a focusing optic dictate the form of the focus in a manner analogous to a physical experiment. In contrast, many models simply assume a field profile near the focus and develop the surrounding vector fields consistent with Maxwell's equations. In comparing the Ignatovsky result with popular closed-form analytic vector models of a Gaussian beam, we find that the relatively simple model developed by Erikson and Singh in 1994 provides good agreement in the paraxial limit. Models involving a Lax expansion introduce a divergences outside of the focus while providing little if any improvement in the focal region. Extremely tight focusing produces a somewhat complicated structure in the focus, and requires the Ignatovsky model for accurate representation.

  18. Air-tight disposing device for solid radioactive waste

    International Nuclear Information System (INIS)

    Aoyama, Saburo.

    1976-01-01

    Object: In a construction for air-tightly connecting radioactive material handling equipment with a radioactive waste container through a vinyl bag, to use a multi-stage expansion tube to introduce the radioactive waste into the waste container in safe and positive manner. Structure: During normal operation in the radioactive material handling equipment, a multi-stage expansion cylinder is extended by operation of a remote shaft to suitably throw the waste in a state with a vinyl bag protected, whereas when the waste is disposed away from the equipment, the multi-stage expansion cylinder is contracted and received into a holder, and the vinyl bag is heated and sealed at a given position and cut, after which a cover of an outer container for disposal is closed and carried out. The vinyl bag remained on the side of the holder after sealed and cut is put into the waste container after a fresh vinyl bag, in which another waste container is received, has been secured to the holder. (Taniai, N.)

  19. Development of the Automated Ultrasonic Testing System for Inspection of the flaw in the Socket Weldment

    International Nuclear Information System (INIS)

    Lee, Jeong Ki; Park, Moon Ho; Park, Ki Sung; Lee, Jae Ho; Lim, Sung Jin

    2004-01-01

    Socket weldment used to change the flow direction of fluid nay have flaws such as lack of fusion and cracks. Liquid penetrant testing or Radiography testing have been applied as NDT methods for flaw detection of the socket weldment. But it is difficult to detect the flaw inside of the socket weldment with these methods. In order to inspect the flaws inside the socket weldment, a ultrasonic testing method is established and a ultrasonic transducer and automated ultrasonic testing system are developed for the inspection. The automated ultrasonic testing system is based on the portable personal computer and operated by the program based Windows 98 or 2000. The system has a pulser/receiver, 100MHz high speed A/D board, and basic functions of ultrasonic flaw detector using the program. For the automated testing, motion controller board of ISA interface type is developed to control the 4-axis scanner and a real time iC-scan image of the automated testing is displayed on the monitor. A flaws with the size of less than 1mm in depth are evaluated smaller than its actual site in the testing, but the flaws larger than 1mm appear larger than its actual size on the contrary. This tendency is shown to be increasing as the flaw size increases. h reliable and objective testing results are obtained with the developed system, so that it is expected that it can contribute to safety management and detection of repair position of pipe lines of nuclear power plants and chemical plants

  20. Evaluation of flaws in ferritic piping: ASME Code Appendix J, Deformation Plasticity Failure Assessment Diagram (DPFAD)

    International Nuclear Information System (INIS)

    Bloom, J.M.

    1991-08-01

    This report summarizes the methods and bases used by an ASME Code procedure for the evaluation of flaws in ferritic piping. The procedure is currently under consideration by the ASME Boiler and Pressure Vessel Code Committee of Section 11. The procedure was initially proposed in 1985 for the evaluation of the acceptability of flaws detected in piping during in-service inspection for certain materials, identified in Article IWB-3640 of the ASME Boiler and Pressure Vessel Code Section 11 ''Rules for In-service Inspection of Nuclear Power Plant Components.'' for which the fracture toughness is not sufficiently high to justify acceptance based solely on the plastic limit load evaluation methodology of Appendix C and IWB-3641. The procedure, referred to as Appendix J, originally included two approaches: a J-integral based tearing instability (J-T) analysis and the deformation plasticity failure assessment diagram (DPFAD) methodology. In Appendix J, a general DPFAD approach was simplified for application to part-through wall flows in ferritic piping through the use of a single DPFAD curve for circumferential flaws. Axial flaws are handled using two DPFAD curves where the ratio of flaw depth to wall thickness is used to determine the appropriate DPFAD curve. Flaws are evaluated in Appendix J by comparing the actual pipe applied stress with the allowable stress with the appropriate safety factors for the flaw size at the end of the evaluation period. Assessment points for circumferential and axial flaws are plotted on the appropriate failure assessment diagram. In addition, this report summarizes the experimental test predictions of the results of the Battelle Columbus Laboratory experiments, the Eiber experiments, and the JAERI tests using the Appendix J DPFAD methodology. Lastly, this report also provides guidelines for handling residual stresses in the evaluation procedure. 22 refs., 13 figs., 5 tabs

  1. Measurement of flaw size in a weld sample by ultrasonic frequency analysis

    International Nuclear Information System (INIS)

    Whaley, H.L. Jr.; Adler, L.; Cook, K.V.; McClung, R.W.

    1975-05-01

    An ultrasonic frequency analysis technique has been developed and applied to the measurement of flaws in an 8-in.-thick heavy-section steel specimen belonging to the Pressure Vessel Research Committee program. Using the technique the flaws occurring in the weld area were characterized in quantitative terms of both dimension and orientation. Several modifications of the technique were made during the study to include the application of several transducers and to consider ultrasonic mode conversion. (U.S.)

  2. A robust indicator based on singular value decomposition for flaw feature detection from noisy ultrasonic signals

    Science.gov (United States)

    Cui, Ximing; Wang, Zhe; Kang, Yihua; Pu, Haiming; Deng, Zhiyang

    2018-05-01

    Singular value decomposition (SVD) has been proven to be an effective de-noising tool for flaw echo signal feature detection in ultrasonic non-destructive evaluation (NDE). However, the uncertainty in the arbitrary manner of the selection of an effective singular value weakens the robustness of this technique. Improper selection of effective singular values will lead to bad performance of SVD de-noising. What is more, the computational complexity of SVD is too large for it to be applied in real-time applications. In this paper, to eliminate the uncertainty in SVD de-noising, a novel flaw indicator, named the maximum singular value indicator (MSI), based on short-time SVD (STSVD), is proposed for flaw feature detection from a measured signal in ultrasonic NDE. In this technique, the measured signal is first truncated into overlapping short-time data segments to put feature information of a transient flaw echo signal in local field, and then the MSI can be obtained from the SVD of each short-time data segment. Research shows that this indicator can clearly indicate the location of ultrasonic flaw signals, and the computational complexity of this STSVD-based indicator is significantly reduced with the algorithm proposed in this paper. Both simulation and experiments show that this technique is very efficient for real-time application in flaw detection from noisy data.

  3. Fracture evaluation of an in-service piping flaw caused by microbiologically induced corrosion

    International Nuclear Information System (INIS)

    Rudland, D.L.; Scott, P.M.; Wilkowski, G.M.; Rahman, S.

    1996-01-01

    A pipe fracture experiment was conducted on a section of 6-inch nominal diameter pipe which was degraded by microbiologically induced corrosion (MIC) at a circumferential girth weld. The pipe was a section of one of the service water piping systems to one of the emergency diesel generators at the Haddam Neck (Connecticut Yankee) plant. The experimental results will help validate future ASME Section XI pipe flaw evaluation criteria for other than Class 1 piping. A critical aspect of this experiment was an assessment of the degree of conservatism embodied in the ASME definition of flaw size. The ASME flaw size definition assumes a rectangular shaped, constant depth flaw with a depth equal to its maximum depth for its entire length. Since most service flaws are irregular in shape, this definition may be overly conservative. Results from several fracture prediction models are compared with the experimental results. These results show that, for this case, the ASME Appendix H criteria significantly underpredicted the experimental maximum moment, while other fracture prediction models provided good predictions when accurate pipe, weld and flaw dimensions were used

  4. Tearing stability analysis of an axial surface flaw in thick-walled pressure vessels

    International Nuclear Information System (INIS)

    Zahoor, A.; Ghassemi, B.B.

    1991-01-01

    This paper presents two fracture mechanics models for evaluation of an axial surface flaw in pressure vessels. The surface flaw is located on the outside surface of the vessel. The first model assumes yielding of the remaining ligament directly ahead of the flaw. The second model assumes contained yielding ahead of the flaw and uses a linear elastic fracture mechanics solution. The former model is suitable for cases where the combination of material toughness, flaw size, and load is such that initiation of flaw growth follows ligament yielding. The latter model is suitable for low-toughness materials where initiation of crack growth and potential tearing instability may occur prior to the yielding of the ligament. Both models are suitable for thick-walled vessels. The paper discusses the applicability regime for both models. The models are then applied to a test vessel and the predicted failure pressure is compared against the pressure attained in the test. Results show that both models can be applied successfully. In particular, the contained yielding model when used with the plane-stress assumption can give reasonable predictions even for cases that involve yielding of the ligament. (orig.)

  5. Magnetite Core-Shell Nanoparticles in Nondestructive Flaw Detection of Polymeric Materials.

    Science.gov (United States)

    Hetti, Mimi; Wei, Qiang; Pohl, Rainer; Casperson, Ralf; Bartusch, Matthias; Neu, Volker; Pospiech, Doris; Voit, Brigitte

    2016-10-04

    Nondestructive flaw detection in polymeric materials is important but difficult to achieve. In this research, the application of magnetite nanoparticles (MNPs) in nondestructive flaw detection is studied and realized, to the best of our knowledge, for the first time. Superparamagnetic and highly magnetic (up to 63 emu/g) magnetite core-shell nanoparticles are prepared by grafting bromo-end-group-functionalized poly(glycidyl methacrylate) (Br-PGMA) onto surface-modified Fe 3 O 4 NPs. These Fe 3 O 4 -PGMA NPs are blended into bisphenol A diglycidylether (BADGE)-based epoxy to form homogeneously distributed magnetic epoxy nanocomposites (MENCs) after curing. The core Fe 3 O 4 of the Fe 3 O 4 -PGMA NPs endows the MENCs with magnetic property, which is crucial for nondestructive flaw detection of the materials, while the shell PGMA promotes colloidal stability and prevents NP aggregation during curing. The eddy current testing (ET) technique is first applied to detect flaws in the MENCs. Through the brightness contrast of the ET image, surficial and subsurficial flaws in MENCs can be detected, even for MENCs with low content of Fe 3 O 4 -PGMA NPs (1 wt %). The incorporation of Fe 3 O 4 -PGMA NPs can be easily extended to other polymer and polymer-based composite systems and opens a new and very promising pathway toward MNP-based nondestructive flaw detection in polymeric materials.

  6. Analytical solution for stress, strain and plastic instability of pressurized pipes with volumetric flaws

    International Nuclear Information System (INIS)

    Cunha, Sérgio B.; Netto, Theodoro A.

    2012-01-01

    The mechanical behavior of internally pressurized pipes with volumetric flaws is analyzed. The two possible modes of circumferentially straining the pipe wall are identified and associated to hypothesized geometries. The radial deformation that takes place by bending the pipe wall is studied by means of axisymmetric flaws and the membrane strain developed by unequal hoop deformation is analyzed with the help of narrow axial flaws. Linear elastic shell solutions for stress and strain are developed, the plastic behavior is studied and the maximum hoop stress at the flaw is related to the undamaged pipe hoop stress by means of stress concentration factors. The stress concentration factors are employed to obtain equations predicting the pressure at which the pipe fails by plastic instability for both types of flaw. These analytical solutions are validated by comparison with burst tests on 3″ diameter pipes and finite element simulations. Forty-one burst tests were carried out and two materials with very dissimilar plastic behavior, carbon steel and austenitic stainless steel, were used in the experiments. Both the analytical and the numerical predictions showed good correlation with the experimentally observed burst pressures. - Highlights: ► An analytical model for the burst of a pipe with a volumetric flaw is developed. ► Deformation, strain and stress are modeled in the elastic and plastic domains. ► The model is comprehensively validated by experiments and numerical simulations. ► The burst pressure model’s accuracy is equivalent to finite element simulations.

  7. Tearing stability analysis of an axial surface flaw in thick-walled pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.; Ghassemi, B.B. (NOVETECH Corp., Rockville, MD (USA))

    1991-04-01

    This paper presents two fracture mechanics models for evaluation of an axial surface flaw in pressure vessels. The surface flaw is located on the outside surface of the vessel. The first model assumes yielding of the remaining ligament directly ahead of the flaw. The second model assumes contained yielding ahead of the flaw and uses a linear elastic fracture mechanics solution. The former model is suitable for cases where the combination of material toughness, flaw size, and load is such that initiation of flaw growth follows ligament yielding. The latter model is suitable for low-toughness materials where initiation of crack growth and potential tearing instability may occur prior to the yielding of the ligament. Both models are suitable for thick-walled vessels. The paper discusses the applicability regime for both models. The models are then applied to a test vessel and the predicted failure pressure is compared against the pressure attained in the test. Results show that both models can be applied successfully. In particular, the contained yielding model when used with the plane-stress assumption can give reasonable predictions even for cases that involve yielding of the ligament. (orig.).

  8. Evaluation of Fatigue Crack Initiation for Volumetric Flaw in Pressure Tube

    International Nuclear Information System (INIS)

    Choi, Sung Nam; Yoo, Hyun Joo

    2005-01-01

    CAN/CSA.N285.4-94 requires the periodic inservice inspection and surveillance of pressure tubes in operating CANDU nuclear power reactors. If the inspection results reveal a flaw exceeding the acceptance criteria of the Code, the flaw must be evaluated to determine if the pressure is acceptable for continued service. Currently, the flaw evaluation methodology and acceptance criteria specified in CSA-N285.05-2005, 'Technical requirements for in-service evaluation of zirconium alloy pressure tubes in CANDU reactors'. The Code is applicable to zirconium alloy pressure tubes. The evaluation methodology for a crack-like flaw is similar to that of ASME B and PV Sec. XI, 'Inservice Inspection of Nuclear Power Plant Components'. However, the evaluation methodology for a blunt volumetric flaw is described in CSA-N285.05-2005 code. The object of this paper is to address the fatigue crack initiation evaluation for the blunt volumetric flaw as it applies to the pressure tube at Wolsong NPP

  9. Flaw evaluation methodology for class 2, 3 components in light water reactors

    International Nuclear Information System (INIS)

    Miura, Naoki; Kashima, Koichi; Miyazaki, Katsumasa; Hasegawa, Kunio; Oritani, Naohiko

    2006-01-01

    It is quite important to validate the structural integrity of operating plant components as aged LWR plants are gradually increasing in Japan. The rules on fitness-for-service for nuclear power plants constituted by the JSME provides flaw evaluation methodology. They are mainly focused on Class 1 components, while flaw evaluation criteria for Class 2, 3 components are not consolidated. As such, they also required from the viewpoints of in-service inspection request, reduction of operating cost and systematization of consistent code/standard. In this study, basic concept of flaw evaluation for Class 2, 3 piping was considered, and it is concluded that the same evaluation procedure as Class 1 piping in the current rules is applicable. Some technical issues on practical flaw evaluation for Class 2, 3 piping were listed up, and a countermeasure for each issue was devised. Especially, both allowable flaw sizes in acceptance standards and critical flaw sizes in acceptance criteria have to be determined in consideration of degraded fracture toughness. (author)

  10. A study on the measurement of flaw sizes by acoustical holography

    International Nuclear Information System (INIS)

    Yamamoto, M.; Ando, T.; Enami, K.; Yajima, M.; Fukui, S.

    1978-01-01

    As a means of evaluating the safety of flawed pressure vessels and other structures against fracture, fracture mechanics has come to be applied. For the application of fracture mechanics it is necessary to get information concerning the sizes and shapes of flaws. The ultrasonic flaw detection method which is widely used as a nondestructive inspection method cannot measure the sizes and shapes of flaws accurately. Considering that acoustical holography is an useful means for the measurement of flaws, we performed basic tests on this method and obtained the following results: (1) The measured values of artificial flaws (flat bottom drilled holes: 5 -- 36 mm) made on a steel plate with a thickness of 150 mm showed a good linear relation with their actual sizes and scatter in the measured values was +-3 -- 6 mm. (2) The measured values of fatigue cracks (length: 5 -- 57 mm) introduced into a steel plate with thickness of 150 mm also showed a good linear relation with their actual sizes and scatter in the measured values was +-3 mm. (3) It was found that acoustical holography can also be applied to heavy section cast steels. (4) The method of correcting distortion caused by curved surface was investigated by computer-aided simulation and it was considered that such distortion can be corrected by radial scanning of a transducer. (auth.)

  11. Air tightness measurements in older Danish single-family houses

    DEFF Research Database (Denmark)

    Mortensen, Lone Hedegaard; Bergsøe, Niels Christian

    2017-01-01

    of the building envelope of older buildings despite the fact that the air tightness has a major influence on the energy use. In connection with renovation of the Danish building stock, the coming years will see increased focus on the air tightness of the building envelope like in other countries. This paper...

  12. Differences between tight and loose cultures : A 33-nation study

    NARCIS (Netherlands)

    Gelfand, M.J.; Raver, R.L.; Nishii, L.; Leslie, L.M.; Lun, J.; Lim, B.C.; Van de Vliert, E.

    2011-01-01

    With data from 33 nations, we illustrate the differences between cultures that are tight (have many strong norms and a low tolerance of deviant behavior) versus loose (have weak social norms and a high tolerance of deviant behavior). Tightness-looseness is part of a complex, loosely integrated

  13. Dielectric response of molecules in empirical tight-binding theory

    Science.gov (United States)

    Boykin, Timothy B.; Vogl, P.

    2002-01-01

    In this paper we generalize our previous approach to electromagnetic interactions within empirical tight-binding theory to encompass molecular solids and isolated molecules. In order to guarantee physically meaningful results, we rederive the expressions for relevant observables using commutation relations appropriate to the finite tight-binding Hilbert space. In carrying out this generalization, we examine in detail the consequences of various prescriptions for the position and momentum operators in tight binding. We show that attempting to fit parameters of the momentum matrix directly generally results in a momentum operator which is incompatible with the underlying tight-binding model, while adding extra position parameters results in numerous difficulties, including the loss of gauge invariance. We have applied our scheme, which we term the Peierls-coupling tight-binding method, to the optical dielectric function of the molecular solid PPP, showing that this approach successfully predicts its known optical properties even in the limit of isolated molecules.

  14. Long term corrosion protection sleeve for tightly closed barrels with highly radioactive contents

    International Nuclear Information System (INIS)

    Koester, R.; Smailos, E.; Schwarzkopf, W.; Kiesow, A.

    1986-01-01

    The application of the corrosion resistant layer on the container body is achieved by blasting plating and by a special design of weld seams on the lid or floor stopper. The corrosion protection layer completely surrounds the container, is additionally applied to the layers in the area of the lid and bottom surface of one floor or lid plate, which consists of another material as corrosion protection layer and which has a diameter a little greater than the hollow cylinder container body. (orig./PW) [de

  15. The tightness of the globe valves in the exploitations practice of the gas pipe-lines

    International Nuclear Information System (INIS)

    Pietrak, T.; Rudzki, Z.; Surmacz, W.

    2006-01-01

    Technological units of the Transit Gas Pipeline (i.e. Compressor Stations, Valve Stations, Stations or National Network Service Installations) have been fitted with Ball Valves as shut-off devices (block valves). Internal tightness of the valves' seat becomes major factor in securing proper service conditions during normal pipeline operation as well as for isolating of pipeline sections in emergency situations (loss of pipeline integrity or uncontrolled gas escape). Internal tightness of the valves is being inspected during scheduled maintenance of the pipeline units. Any leak revealed during inspection is being repaired, following instructions provided in the Manufacturer's Valve Manual. After a time, some cases have been identified, when repair of the revealed leak was found to be difficult, despite close following of the repair manuals. The paper presents analysis of the issue and corrective actions taken accordingly. (authors)

  16. Three-dimensional measurement of a tightly focused laser beam

    Directory of Open Access Journals (Sweden)

    Xiangsheng Xie

    2013-02-01

    Full Text Available The spatial structure of a tightly focused light field is measured with a double knife-edge scanning method. The measurement method is based on the use of a high-quality double knife-edge fabricated from a right-angled silicon fragment mounted on a photodetector. The reconstruction of the three-dimensional structures of tightly focused spots is carried out with both uniform and partially obstructed linearly polarized incident light beams. The optical field distribution is found to deviate substantially from the input beam profile in the tightly focused region, which is in good agreement with the results of numerical simulations.

  17. On the feasibility of detecting flaws in artificial heart valves

    NARCIS (Netherlands)

    Lepelaars, E.S.A.M.; Ooijen, van W.D.R.; Tijhuis, A.G.

    2000-01-01

    Investigates the feasibility of detecting defects in certain artificial heart valves by determining the electromagnetic behavior of some simple models with the aid of thin-wire integral equations. The idea is to use the stationary current that occurs at late times after the excitation of a closed

  18. Derivation of Elastic Stress Concentration Factor Equations for Debris Fretting Flaws in Pressure Tubes of Pressurized Heavy Water Reactors

    International Nuclear Information System (INIS)

    Kim, Jong Sung; Oh, Young Jin

    2014-01-01

    If volumetric flaws such as bearing pad fretting flaws and debris fretting flaws are detected in the pressure tubes of pressurized heavy water reactors during in-service inspection, the initiation of fatigue cracks and delayed hydrogen cracking from the detected volumetric flaws shall be assessed by using elastic stress concentration factors in accordance with CSA N285.8-05. The CSA N285.8-05 presents only an approximate formula based on linear elastic fracture mechanics for the debris fretting flaw. In this study, an engineering formula considering the geometric characteristics of the debris fretting flaw in detail was derived using two-dimensional finite element analysis and Kinectrics, Inc.'s engineering procedure with slight modifications. Comparing the application results obtained using the derived formula with the three-dimensional finite element analysis results, it is found that the results obtained using the derived formula agree well with the results of the finite element analysis

  19. Development and application of an LWR reactor pressure vessel-specific flaw distribution

    International Nuclear Information System (INIS)

    Rosinski, S.T.; Kennedy, E.L.; Foulds, J.R.

    1991-01-01

    Previous efforts by the US Department of Energy have shown that the PWR reactor vessel integrity predictions performed through probabilistic fracture mechanics analysis for a pressurized thermal shock event are significantly sensitive to the overall flaw distribution input. It has also been shown that modern vessel in-service inspection (ISI) results can be used for development of vessel flaw distribution(s) that are more representative of US vessels. This paper describes the development and application of a methodology to analyze ISI data for the purpose of flaw distribution determination. The resultant methodology considers detection reliability, flaw sizing accuracy, and flaw detection threshold in its application. Application of the methodology was then demonstrated using four recently acquired US PWR vessel inspection data sets. The methodology helped provide original insight into several key inspection performance and vessel integrity prediction practice issues that will impact future vessel integrity evaluation. This paper briefly discusses the development and application of the methodology and the impact to future vessel integrity analyses

  20. Application of elastic and elastic-plastic fracture mechanics methods to surface flaws

    Science.gov (United States)

    McCabe, Donald E.; Ernst, Hugo A.; Newman, James C., Jr.

    Fuel tanks that are a part of the External Tank assembly for the Space Shuttle are made of relatively thin 2219-T87 aluminum plate. These tanks contain about 917 m of fusion weld seam, all of which is nondestructively inspected for flaws and all those found are repaired. The tanks are subsequently proof-tested to a pressure that is sufficiently severe to cause weld metal yielding in a few local regions of the weld seam. The work undertaken in the present project was to develop a capability to predict flaw growth from undetected surface flaws that are assumed to be located in the highly stressed regions. The technical challenge was to develop R-curve prediction capability for surface cracks in specimens that contain the flaws of unusual sizes and shapes deemed to be of interest. The test techniques developed and the elastic-plastic analysis concepts adopted are presented. The flaws of interest were quite small surface cracks that were narrow-deep ellipses that served to exacerbate the technical difficulties involved.

  1. Effect of combined loading due to bending and internal pressure on pipe flaw evaluation criteria

    International Nuclear Information System (INIS)

    Miura, Naoki; Sakai, Shinsuke

    2006-01-01

    Considering a rational maintenance rule of Light Water Reactor piping, reliable flaw evaluation criteria are essential to determine how a detected flaw is detrimental to continuous plant operation. Ductile fracture is one of the dominant failure modes to be considered for carbon steel piping, and can be analyzed by the elastic-plastic fracture mechanics. Some analytical efforts have been provided as flaw evaluation criteria using load correction factors such like the Z-factors in the JSME codes on fitness-for-service for nuclear power plants or the ASME boiler and pressure vessel code section XI. The present correction factors were conventionally determined taken conservatism and simplicity into account, however, the effect of internal pressure which would be an important factor under an actual plant condition was not adequately considered. Recently, a J-estimation scheme, 'LBB. ENGC' for ductile fracture analysis of circumferentially through-wall-cracked pipes subjected combined loading was newly developed to have a better prediction with more realistic manner. This method is explicitly incorporated the contribution of both bending and tension due to internal pressure by means of the scheme compatible with an arbitrary combined loading history. In this paper, the effect of internal pressure on the flaw evaluation criteria was investigated using the new J-estimation scheme. A correction factor based on the new J-estimation scheme was compared with the present correction factors, and the predictability of the current flaw evaluation criteria was quantitatively evaluated in consideration of internal pressure. (author)

  2. Biaxial loading and shallow-flaw effects on crack-tip constraint and fracture-toughness

    International Nuclear Information System (INIS)

    Pennell, W.E.; Bass, B.R.; Bryson, J.W.; McAfee, W.J.; Theiss, T.J.; Rao, M.C.

    1993-01-01

    Uniaxial tests of single-edged notched bend (SENB) specimens with both deep- and shallow-flaws have shown elevated fracture-toughness for the shallow flaws. The elevation in fracture-toughness for shallow flaws has been shown to be the result of reduced constraint at the crack-tip. Biaxial loading has the potential to increase constraint at the crack-tip and thereby reduce some of the shallow-flaw, fracture-toughness elevation. Biaxial fracture-toughness tests have shown that the shallow-flaw, fracture-toughness elevation is reduced but not eliminated by biaxial loading. Dual-parameter, fracture-toughness correlations have been proposed to reflect the effect of crack-tip constraint on fracture-toughness. Test results from the uniaxial and biaxial tests were analyzed using the dual-parameter technology. Discrepancies between analysis results and cleavage initiation site data from fractographic examinations indicate that the analysis models are in need of further refinement. Addition of a precleavage, ductile-tearing element to the analysis model has the potential to resolve the noted discrepancies

  3. Regulation No. 0-31 on handling of radiation flaw-detectors

    International Nuclear Information System (INIS)

    1975-01-01

    The regulation contains mandatory design, commissioning, and operational requirements for laboratories using flaw-detectors emitting ionizing radiation; also, design, manufacturing, and operational requirements for the production of any type of X-ray or gamma-ray flaw-detectors. Laboratories carrying out non-destructive testing are either stationary or mobile. Conceptual and operating designs are elaborated, including the building and the laboratory lay-outs, the mains, water supply, and sewerage system technological lay-out, explanatory comments, and a lay-out of the shielding equipment. Approbated designs are implemented, and the laboratories commissioned to representatives of the State Sanitary Inspectorate. Licences are issued by the Ministry of Public Health (MPH) and the Committee on Peaceful Uses of Atomic Energy (CPUAE). Any flaw-detector has to conform to the Bulgarian State Standards and be coordinated with the MPH, the CPUAE, and the Central Laboratory for Nuclear Flaw-Detection (CLNFD). The laboratories are required to have operational instructions, an emergency plan, and to keep technological and dosimetric records. The latter are provided and processed by the relevant service at the Research Institute of Radiobiology and Radiation Hygiene. For operations involving of flaw-detectors, presence of at least two workers is required. (G.G.)

  4. Simulating the x-ray image contrast to setup techniques with desired flaw detectability

    Science.gov (United States)

    Koshti, Ajay M.

    2015-04-01

    The paper provides simulation data of previous work by the author in developing a model for estimating detectability of crack-like flaws in radiography. The methodology is developed to help in implementation of NASA Special x-ray radiography qualification, but is generically applicable to radiography. The paper describes a method for characterizing the detector resolution. Applicability of ASTM E 2737 resolution requirements to the model are also discussed. The paper describes a model for simulating the detector resolution. A computer calculator application, discussed here, also performs predicted contrast and signal-to-noise ratio calculations. Results of various simulation runs in calculating x-ray flaw size parameter and image contrast for varying input parameters such as crack depth, crack width, part thickness, x-ray angle, part-to-detector distance, part-to-source distance, source sizes, and detector sensitivity and resolution are given as 3D surfaces. These results demonstrate effect of the input parameters on the flaw size parameter and the simulated image contrast of the crack. These simulations demonstrate utility of the flaw size parameter model in setting up x-ray techniques that provide desired flaw detectability in radiography. The method is applicable to film radiography, computed radiography, and digital radiography.

  5. A study on the development of a real-time intelligent system for ultrasonic flaw classification

    International Nuclear Information System (INIS)

    Song, Sung Jin; Kim, Hak Joon; Lee, Hyun; Lee, Seung Seok

    1998-01-01

    In spite of significant progress in research on ultrasonic pattern recognition it is not widely used in many practical field inspection in weldments. For the convenience of field application of this methodology, following four key issues have to be suitably addressed; 1) a software where the ultrasonic pattern recognition algorithm is efficiently implemented, 2) a real-time ultrasonic testing system which can capture the digitized ultrasonic flaw signal so the pattern recognition software can be applied in a real-time fashion, 3) database of ultrasonic flaw signals in weldments, which is served as a foundation of the ultrasonic pattern recognition algorithm, and finally, 4) ultrasonic features which should be invariant to operational variables of the ultrasonic test system. Presented here is the recent progress in the development of a real-time ultrasonic flaw classification by the novel combination of followings; an intelligent software for ultrasonic flaw classification in weldments, a computer-base real-time ultrasonic nondestructive evaluation system, database of ultrasonic flaw signals, and invariant ultrasonic features called 'normalized features.'

  6. On tight multiparty Bell inequalities for many settings

    OpenAIRE

    Zukowski, Marek

    2006-01-01

    A derivation method is given which leads to a series of tight Bell inequalities for experiments involving N parties, with binary observables, and three possible local settings. The approach can be generalized to more settings. Ramifications are presented.

  7. Western tight gas sands advanced logging workshop proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, J B; Carroll, Jr, H B [eds.

    1982-04-01

    An advanced logging research program is one major aspect of the Western Tight Sands Program. Purpose of this workshop is to help BETC define critical logging needs for tight gas sands and to allow free interchange of ideas on all aspects of the current logging research program. Sixteen papers and abstracts are included together with discussions. Separate abstracts have been prepared for the 12 papers. (DLC)

  8. Hamstring tightness and Scheuermann's disease a pilot study.

    Science.gov (United States)

    Fisk, J W; Baigent, M L

    1981-06-01

    The lateral radiographs of the dorsal spines of 20 patients presenting with mainly low back pain are studied. These patients had clinically evident loss of flexion in the low dorsal spine and very tight hamstring muscles. 85% of them showed definite evidence of previous Scheuermann's Disease. The possibility that tight hamstrings may be an important factor in the aetiology of this disease is discussed, and a further large scale study is proposed.

  9. Contraption and Prediction of Exhalation Tight Brownstone in Exhalation Cistern

    OpenAIRE

    XhingZhiwang, -; Xuchao, -

    2012-01-01

    The reservoir connate water saturation is high and gas wells generally produce water which seriously affects the productivity of gas wells in Xujiahe tight sandstone gas reservoirs in Sichuan Basin. Take the sixth formation for example, there are 39 wells producing water unequally in the 42 commissioning wells, and the excessive water production leads to the production of the gas well declining rapidly. Studying of the mechanism of water production in tight sandstone gas reservoirs and predic...

  10. Regulation of Tight Junctions in Upper Airway Epithelium

    Directory of Open Access Journals (Sweden)

    Takashi Kojima

    2013-01-01

    Full Text Available The mucosal barrier of the upper respiratory tract including the nasal cavity, which is the first site of exposure to inhaled antigens, plays an important role in host defense in terms of innate immunity and is regulated in large part by tight junctions of epithelial cells. Tight junction molecules are expressed in both M cells and dendritic cells as well as epithelial cells of upper airway. Various antigens are sampled, transported, and released to lymphocytes through the cells in nasal mucosa while they maintain the integrity of the barrier. Expression of tight junction molecules and the barrier function in normal human nasal epithelial cells (HNECs are affected by various stimuli including growth factor, TLR ligand, and cytokine. In addition, epithelial-derived thymic stromal lymphopoietin (TSLP, which is a master switch for allergic inflammatory diseases including allergic rhinitis, enhances the barrier function together with an increase of tight junction molecules in HNECs. Furthermore, respiratory syncytial virus infection in HNECs in vitro induces expression of tight junction molecules and the barrier function together with proinflammatory cytokine release. This paper summarizes the recent progress in our understanding of the regulation of tight junctions in the upper airway epithelium under normal, allergic, and RSV-infected conditions.

  11. Flaw evaluation of thermally aged cast stainless steel in light-water reactor applications

    International Nuclear Information System (INIS)

    Lee, S.; Kuo, P.T.; Wichman, K.; Chopra, O.

    1997-01-01

    Cast stainless steel may be used in the fabrication of the primary loop piping, fittings, valve bodies, and pump casings in light-water reactors. However, this material is subject to embrittlement due to thermal aging at the reactor temperature, that is 290 o C (550 o F). The Argonne National Laboratory (ANL) recently completed a research program and the results indicate that the lower-bound fracture toughness of thermally aged cast stainless steel is similar to that of submerged arc welds (SAWs). Thus, the US Nuclear Regulatory Commission (NRC) staff has accepted the use of SAW flaw evaluation procedures in IWB-3640 of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code to evaluate flaws in thermally aged cast stainless steel for a license renewal evaluation. Alternatively, utilities may estimate component-specific fracture toughness of thermally aged cast stainless steel using procedures developed at ANL for a case-by-case flaw evaluation. (Author)

  12. Determination of Flaw Size and Depth From Temporal Evolution of Thermal Response

    Science.gov (United States)

    Winfree, William P.; Zalameda, Joseph N.; Cramer, Elliott; Howell, Patricia A.

    2015-01-01

    Simple methods for reducing the pulsed thermographic responses of flaws have tended to be based on either the spatial or temporal response. This independent assessment limits the accuracy of characterization. A variational approach is presented for reducing the thermographic data to produce an estimated size for a flaw that incorporates both the temporal and spatial response to improve the characterization. The size and depth are determined from both the temporal and spatial thermal response of the exterior surface above a flaw and constraints on the length of the contour surrounding the delamination. Examples of the application of the technique to simulation and experimental data acquired are presented to investigate the limitations of the technique.

  13. Experimental study on flaw detectability of remote field eddy current testing

    International Nuclear Information System (INIS)

    Kamimura, T.; Fukui, S.; Iwahashi, Y.; Yamada, H.

    1988-01-01

    For the purpose of comprehending the effect in practical use of the remote field eddy current (RFEC) testing that becomes noticeable for the ISI technique of steel tubes, its flaw detectability was clarified through a model test. This study used straight and bending tubes of 3.8 mm in wall thickness and 31.8 mm in outside diameter. These tubes were inspected from their inside. After relations among the pickup coil output, coil distance, testing frequency, etc. were measured, a probe of the practical use type was manufactured to investigate its flaw detectability by means of simulated flaws. The authors discuss how it has been found that light local wall thinning on the outside surfaces can be detected by this technique and its effect in practical use can be expected with small influences due to magnetic permeability variations of tube materials, bending of tubes, etc

  14. Characterization of flaws in a tube bundle mock-up for reliability studies

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Bakhtiari, S.

    1997-01-01

    As part of an assessment of in-service inspection of steam generator tubes, the authors will assemble a steam generator mock-up for round robin studies and use as a test bed in evaluating emerging technologies. Progress is reported on the characterization of flaws that will be part of the mock-up. Eddy current and ultrasonic techniques are being evaluated as a means to characterize the flaws in the mock-up tubes before final assembly. Twenty Inconel 600 tubes with laboratory-grown cracks, typical of those to be used in the mock-up, were provided by Pacific Northwest National Laboratory for laboratory testing. After the tubes were inspected with eddy current and ultrasonic techniques, they were destructively analyzed to establish the actual depths, lengths, and profiles of the cracks. The analysis of the results will allow the best techniques to be used for characterizing the flaws in the mock-up tubes

  15. Characterization of flaws in a tube bundle mock-up for reliability studies

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Bakhtiari, S.

    1996-10-01

    As part of an assessment of in-service inspection of steam generator tubes, the authors will assemble a steam generator mock-up for round robin studies and use as a test bed in evaluating emerging technologies. Progress is reported on the characterization of flaws that will be part of the mock-up. Eddy current and ultrasonic techniques are being evaluated as a means to characterize the flaws in the mock-up tubes before final assembly. Twenty Inconel 600 tubes with laboratory-grown cracks, typical of those to be used in the mock-up, were provided by Pacific Northwest National Laboratory for laboratory testing. After the tubes were inspected with eddy current and ultrasonic techniques, they were destructively analyzed to establish the actual depths, lengths, and profiles of the cracks. The analysis of the results will allow the best techniques to be used for characterizing the flaws in the mock-up tubes

  16. Flaw density examinations of a clad boiling water reactor pressure vessel segment

    International Nuclear Information System (INIS)

    Cook, K.V.; McClung, R.W.

    1986-01-01

    Flaw density is the greatest uncertainty involved in probabilistic analyses of reactor pressure vessel failure. As part of the Heavy-Section Steel Technology (HSST) Program, studies have been conducted to determine flaw density in a section of reactor pressure vessel cut from the Hope Creek Unit 2 vessel [nominally 0.7 by 3 m (2 by 10 ft)]. This section (removed from the scrapped vessel that was never in service) was evaluated nondestructively to determine the as-fabricated status. We had four primary objectives: (1) evaluate longitudinal and girth welds for flaws with manual ultrasonics, (2) evaluate the zone under the nominal 6.3-mm (0.25-in.) clad for cracking (again with manual ultrasonics), (3) evaluate the cladding for cracks with a high-sensitivity fluorescent penetrant method, and (4) determine the source of indications detected

  17. Flaw characterization through nonlinear ultrasonics and wavelet cross-correlation algorithms

    Science.gov (United States)

    Bunget, Gheorghe; Yee, Andrew; Stewart, Dylan; Rogers, James; Henley, Stanley; Bugg, Chris; Cline, John; Webster, Matthew; Farinholt, Kevin; Friedersdorf, Fritz

    2018-04-01

    Ultrasonic measurements have become increasingly important non-destructive techniques to characterize flaws found within various in-service industrial components. The prediction of remaining useful life based on fracture analysis depends on the accurate estimation of flaw size and orientation. However, amplitude-based ultrasonic measurements are not able to estimate the plastic zones that exist ahead of crack tips. Estimating the size of the plastic zone is an advantage since some flaws may propagate faster than others. This paper presents a wavelet cross-correlation (WCC) algorithm that was applied to nonlinear analysis of ultrasonically guided waves (GW). By using this algorithm, harmonics present in the waveforms were extracted and nonlinearity parameters were used to indicate both the tip of the cracks and size of the plastic zone. B-scans performed with the quadratic nonlinearities were sensitive to micro-damage specific to plastic zones.

  18. Mode Selection for Axial Flaw Detection in Steam Generator Tube Using Ultrasonic Guided Wave

    International Nuclear Information System (INIS)

    Yoon, Byung Sik; Yang, Seung Han; Guon, Ki Il; Kim, Yong Sik

    2009-01-01

    The eddy current testing method is mainly used to inspect steam generator tube during in-service inspection period. But the general problem of assessing the structural integrity of the steam generator tube using eddy current inspection is rather complex due to the presence of noise and interference signal under various conditions. However, ultrasonic testing as a nondestructive testing tool has become quite popular and effective for the flaw detection and material characterization. Currently, ultrasonic guided wave is emerging technique in power industry because of its various merits. But most of previous studies are focused on detection of circumferential oriented flaws. In this study, the steam generator tube of nuclear power plant was selected to detect axially oriented flaws and investigate guided wave mode identification. The longitudinal wave mode is generated using piezoelectric transducer frequency from 0.5 MHz, 1.0 MHz, 2.25MHz and 5MHz. Dispersion based STFT algorithm is used as mode identification tool

  19. Origin and type of flaws in heat engine ceramic materials and components

    International Nuclear Information System (INIS)

    Govila, R.K.

    1995-01-01

    A number of ceramic materials such as Silicon Nitrides and Carbides, Sialons, Whisker-Reinforced Ceramic Composites and Partially-Stabilized Zirconias (PSZs) have been developed for use as structural components in heat engine applications. The reliability and durability of a structural engine component is critically dependent on the size, density of distribution and location of flaws. This information is critical for the processing and design engineers in order to design structural components using suitable materials and thus minimize stress intensity. In general, the failure initiating flaws are associated or produced due to material impurity, processing methods and parameters, and fabrication techniques (machining and grinding). Examples of each type of flaws associated with material impurity, processing methods and fabrication techniques are illustrated

  20. Analytical solution for stress, strain and plastic instability of pressurized pipes with volumetric flaws

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Sergio B., E-mail: sbcunha@petrobras.com.br [PETROBRAS/TRANSPETRO, Av. Pres. Vargas 328 - 7th floor, Rio de Janeiro, RJ 20091-060 (Brazil); Netto, Theodoro A., E-mail: tanetto@lts.coppe.ufrj.br [COPPE, Federal University ot Rio de Janeiro, Ocean Engineering Department, PO BOX 68508, Rio de Janeiro - RJ (Brazil)

    2012-01-15

    The mechanical behavior of internally pressurized pipes with volumetric flaws is analyzed. The two possible modes of circumferentially straining the pipe wall are identified and associated to hypothesized geometries. The radial deformation that takes place by bending the pipe wall is studied by means of axisymmetric flaws and the membrane strain developed by unequal hoop deformation is analyzed with the help of narrow axial flaws. Linear elastic shell solutions for stress and strain are developed, the plastic behavior is studied and the maximum hoop stress at the flaw is related to the undamaged pipe hoop stress by means of stress concentration factors. The stress concentration factors are employed to obtain equations predicting the pressure at which the pipe fails by plastic instability for both types of flaw. These analytical solutions are validated by comparison with burst tests on 3 Double-Prime diameter pipes and finite element simulations. Forty-one burst tests were carried out and two materials with very dissimilar plastic behavior, carbon steel and austenitic stainless steel, were used in the experiments. Both the analytical and the numerical predictions showed good correlation with the experimentally observed burst pressures. - Highlights: Black-Right-Pointing-Pointer An analytical model for the burst of a pipe with a volumetric flaw is developed. Black-Right-Pointing-Pointer Deformation, strain and stress are modeled in the elastic and plastic domains. Black-Right-Pointing-Pointer The model is comprehensively validated by experiments and numerical simulations. Black-Right-Pointing-Pointer The burst pressure model's accuracy is equivalent to finite element simulations.

  1. Potential change in flaw geometry of an initially shallow finite-length surface flaw during a pressurized-thermal-shock transient

    International Nuclear Information System (INIS)

    Shum, D.K.; Bryson, J.W.; Merkle, J.G.

    1993-09-01

    This study presents preliminary estimates on whether an shallow, axially oriented, inner-surface finite-length flaw in a PWR-RPV would tend to elongate in the axial direction and/or deepen into the wall of the vessel during a postulated PTS transient. Analysis results obtained based on the assumptions of (1) linear-elastic material response, and (2) cladding with same toughness as the base metal, indicate that a nearly semicircular flaw would likely propagate in the axial direction followed by propagation into the wall of the vessel. Note that these results correspond to initiation within the lower-shelf fracture toughness temperature range, and that their general validity within the lower-transition temperature range remains to be determined. The sensitivity of the numerical results aid conclusions to the following analysis assumptions are evaluated: (1) reference flaw geometry along the entire crack front and especially within the cladding region; (2) linear-elastic vs elastic-plastic description of material response; and (3) base-material-only vs bimaterial cladding-base vessel-model assumption. The sensitivity evaluation indicates that the analysis results are very sensitive to the above assumptions

  2. Influence of circumferential flaw length on internal burst pressure of a wall-thinned pipe

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, Masataka, E-mail: tsuji-m@u-fukui.ac.jp [Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, Fukui (Japan); Meshii, Toshiyuki [Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, Fukui (Japan)

    2013-02-15

    Highlights: ► The effect of θ on p{sub f} was examined by experimental analysis and FEA. ► Here θ is the circumferential angle of a flaw, p{sub f} is the internal burst pressure. ► p{sub f} decreased as θ increased in some cases. ► The effect of θ on p{sub f} should be taken into consideration in evaluating p{sub f}. -- Abstract: This paper examines the effect of the circumferential angle of a flaw θ on the internal burst pressure p{sub f} of pipes with artificial wall-thinned flaws. The effect of θ has conventionally been regarded as unimportant in the evaluation of the p{sub f} of wall-thinned straight pipes. Therefore, a burst pressure equation for an axial crack inside a cylinder (Fig. 1, left), such as Kiefner's equation (Kiefner et al., 1973), has been widely applied (ANSI/ASME B31.G., 1991; Hasegawa et al., 2011). However, the following implicit assumptions notably exist when applying the equation to planar flaws in situations with non-planar flaws. 1)The fracture mode of the non-planar flaw under consideration is identical to that of the crack. 2)The effect of θ on p{sub f}, which is not considered for an axial crack, is small or negligible. However, the experimental results from the systematic burst tests for carbon steel pipes with artificial wall-thinned flaws examined in this paper showed that these implicit assumptions may be incorrect. In this paper the experimental results are evaluated in further detail. The purpose of the evaluation was to clarify the effect of θ on p{sub f}. Specifically, the significance of the flaw configuration (axial length δ{sub z} and wall-thinning ratio t{sub 1}/t) was studied for its effects on θ and p{sub f}. In addition, a simulation of this effect was conducted using a large strain elastic-plastic Finite Element Analysis (FEA) model. As observed from the experimental results, θ tended to affect p{sub f} in cases with large δ{sub z}, and t{sub 1}/t was also correlated with a decrease in p{sub f

  3. Evaluating empirical/analytical techniques to predict structural integrity of pipe containing surface flaws

    International Nuclear Information System (INIS)

    Reuter, W.G.; Server, W.L.

    1982-01-01

    Data from flat-plate specimens containing either triangular-, ellipsoidal- or rectangular-shaped surface flaws were evaluated by several potential analytical techniques. These techniques were modified as needed to predict conditions for initiation of subcritical crack growth, for the defect to penetrate the 6.4 mm (0.25 in.) wall thickness, and for instability (plastic or unstable). The modified analytical techniques developed from the plate specimens were then used to make predictions which are compared with test results obtained from pipe specimens containing triangular-shaped surface flaws

  4. Probabilistic calibration of safety coefficients for flawed components in nuclear engineering

    International Nuclear Information System (INIS)

    Ardillon, E.; Pitner, P.; Barthelet, B.; Remond, A.

    1996-01-01

    The rules that are currently under application to verify the acceptance of flaws in nuclear components rely on deterministic criteria supposed to ensure the safe operating of plants. The interest of having a precise and reliable method to evaluate the safety margins and the integrity of components led Electricite de France to launch an approach to link directly safety coefficients with safety levels. This paper presents a probabilistic methodology to calibrate safety coefficients in relation to reliability target values. The proposed calibration procedure applies to the case of a ferritic flawed pipe using the R6 procedure for assessing the integrity of the structure. (authors). 5 refs., 5 figs

  5. Internal Rot Detection with the Use of Low-Frequency Flaw Detector

    Science.gov (United States)

    Proskórnicki, Marek; Ligus, Grzegorz

    2014-12-01

    The issue of rot detection in standing timber or stocked wood is very important in forest management. Rot flaw detection used for that purpose is represented by invasive and non-invasive devices. Non-invasive devices are very accurate, but due to the cost and complicated operation they have not been applied on a large scale in forest management. Taking into account the practical needs of foresters a prototype of low-frequency flaw was developed. The principle of its operation is based on the difference in acoustic wave propagation in sound wood and wood with rot.

  6. Imaging flaws in thin metal plates using a magneto-optic device

    Science.gov (United States)

    Wincheski, B.; Prabhu, D. R.; Namkung, M.; Birt, E. A.

    1992-01-01

    An account is given of the capabilities of the magnetooptic/eddy-current imager (MEI) apparatus in the case of aging aircraft structure-type flaws in 2024-T3 Al alloy plates. Attention is given to images of cyclically grown fatigue cracks from rivetted joints in fabricated lap-joint structures, electrical discharge machining notches, and corrosion spots. Although conventional eddy-current methods could have been used, the speed and ease of MEI's use in these tests is unmatched by such means. Results are displayed in real time as a test piece is scanned, furnishing easily interpreted flaw images.

  7. Probabilistic calibration of safety coefficients for flawed components in nuclear engineering

    International Nuclear Information System (INIS)

    Ardillon, E.; Pitner, P.; Barthelet, B.; Remond, A.

    1995-01-01

    The current rules applied to verify the flaws acceptance in nuclear components rely on deterministic criteria supposed to ensure the plant safe operation. The interest in have a precise and reliable method to evaluate the safety margins and the integrity of components led Electricite de France to launch an approach to link directly safety coefficients with safety levels. This paper presents a probabilistic methodology to calibrate safety coefficients in relation do reliability target values. The proposed calibration procedure applies to the case of a ferritic flawed pipe using the R 6 procedure for assessing the structure integrity. (author). 5 refs., 5 figs., 1 tab

  8. Twenty years of fracture mechanics and flaw evaluation applications in the ASME Nuclear Code

    International Nuclear Information System (INIS)

    Riccardella, P.C.

    1991-01-01

    The paper presents a retrospective on the development and applications of fracture mechanics-based toughness requirements and flaw evaluation methodology in Sections III and XI of the ASME Code. Section III developments range from the rules and requirements for thick section Class 1 pressure vessels to thinner section components in other Classes. Section XI applications include flaw acceptance standards and evaluation methodology for various components ranging from pressure vessels to thins section piping of carbon and austenitic steels. The experience gained in operating plant applications of these rules and procedures are also discussed

  9. Human zonulin, a potential modulator of intestinal tight junctions.

    Science.gov (United States)

    Wang, W; Uzzau, S; Goldblum, S E; Fasano, A

    2000-12-01

    Intercellular tight junctions are dynamic structures involved in vectorial transport of water and electrolytes across the intestinal epithelium. Zonula occludens toxin derived from Vibrio cholerae interacts with a specific intestinal epithelial surface receptor, with subsequent activation of a complex intracellular cascade of events that regulate tight junction permeability. We postulated that this toxin may mimic the effect of a functionally and immunologically related endogenous modulator of intestinal tight junctions. Affinity-purified anti-zonula occludens toxin antibodies and the Ussing chamber assay were used to screen for one or more mammalian zonula occludens toxin analogues in both fetal and adult human intestine. A novel protein, zonulin, was identified that induces tight junction disassembly in non-human primate intestinal epithelia mounted in Ussing chambers. Comparison of amino acids in the active zonula occludens toxin fragment and zonulin permitted the identification of the putative receptor binding domain within the N-terminal region of the two proteins. Zonulin likely plays a pivotal role in tight junction regulation during developmental, physiological, and pathological processes, including tissue morphogenesis, movement of fluid, macromolecules and leukocytes between the intestinal lumen and the interstitium, and inflammatory/autoimmune disorders.

  10. The media of sociology: tight or loose translations?

    Science.gov (United States)

    Guggenheim, Michael

    2015-06-01

    Sociologists have increasingly come to recognize that the discipline has unduly privileged textual representations, but efforts to incorporate visual and other media are still only in their beginning. This paper develops an analysis of the ways objects of knowledge are translated into other media, in order to understand the visual practices of sociology and to point out unused possibilities. I argue that the discourse on visual sociology, by assuming that photographs are less objective than text, is based on an asymmetric media-determinism and on a misleading notion of objectivity. Instead, I suggest to analyse media with the concept of translations. I introduce several kinds of translations, most centrally the distinction between tight and loose ones. I show that many sciences, such as biology, focus on tight translations, using a variety of media and manipulating both research objects and representations. Sociology, in contrast, uses both tight and loose translations, but uses the latter only for texts. For visuals, sociology restricts itself to what I call 'the documentary': focusing on mechanical recording technologies without manipulating either the object of research or the representation. I conclude by discussing three rare examples of what is largely excluded in sociology: visual loose translations, visual tight translations based on non-mechanical recording technologies, and visual tight translations based on mechanical recording technologies that include the manipulation of both object and representation. © London School of Economics and Political Science 2015.

  11. A study on the extraction of feature variables for the pattern recognition for welding flaws

    International Nuclear Information System (INIS)

    Kim, J. Y.; Kim, C. H.; Kim, B. H.

    1996-01-01

    In this study, the researches classifying the artificial and natural flaws in welding parts are performed using the pattern recognition technology. For this purpose the signal pattern recognition package including the user defined function was developed and the total procedure including the digital signal processing, feature extraction, feature selection and classifier selection is treated by bulk. Specially it is composed with and discussed using the statistical classifier such as the linear discriminant function classifier, the empirical Bayesian classifier. Also, the pattern recognition technology is applied to classification problem of natural flaw(i.e multiple classification problem-crack, lack of penetration, lack of fusion, porosity, and slag inclusion, the planar and volumetric flaw classification problem). According to this results, if appropriately teamed the neural network classifier is better than stastical classifier in the classification problem of natural flaw. And it is possible to acquire the recognition rate of 80% above through it is different a little according to domain extracting the feature and the classifier.

  12. Modeling validation to structural flaws in the foundations of oil tanks

    International Nuclear Information System (INIS)

    Couto, Larissa Goncalves; Leite, Sandro Passos

    2014-01-01

    This paper presents the modeling of an experiment used to study the application of backscattered neutrons in the identification of structural flaws in the foundations of oil tanks. This modeling was a preliminary validation procedure of the method of calculation, performed with the radiation transport code MCNP, to study the application of backscattered neutrons as inspection tool. (author)

  13. Flawed Implementation or Inconsistent Logics? Lessons from Higher Education Reform in Ukraine

    Science.gov (United States)

    Shaw, Marta A.

    2013-01-01

    This article investigates two competing explanations of why reforms associated with the Bologna process brought disappointing results in Ukraine. The lack of anticipated benefits from the reforms may stem either from a flawed implementation of the Bologna process, or from more fundamental differences between the models of higher education…

  14. Acoustic emission and estimation of flaw significance in reactor pressure boundaries

    International Nuclear Information System (INIS)

    Hutton, P.H.; Kurtz, R.J.

    1982-01-01

    The work discussed is intended to establish the feasibility of using acoustic emission (AE) to detect and evaluate growing flaws in nuclear reactor pressure boundaries. Basic AE identification and interpretation methods have grown out of Phase 1. Phases 2 and 3 to test and demonstrate developed methodology on a vessel test and on a reactor are in progress

  15. Stabilized transistor transformer for self-moving Sirena-1 X-ray flaw detector

    International Nuclear Information System (INIS)

    Krasil'nikov, S.B.; Kristalinskij, A.L.; Lozovoj, L.N.; Markov, S.N.; Sindalovskij, E.I.

    1986-01-01

    Electric circuit of stabilized transistor transformer for self-moving ''Sirena'' type X-ray flaw detector is described. Specifications of the transformer and results of the experimental studies, which can be used when tuning and adjusting the transformer under industrial conditions

  16. Crack propagation from a filled flaw in rocks considering the infill influences

    Science.gov (United States)

    Chang, Xu; Deng, Yan; Li, Zhenhua; Wang, Shuren; Tang, C. A.

    2018-05-01

    This study presents a numerical and experimental study of the cracking behaviour of rock specimen containing a single filled flaw under compression. The primary aim is to investigate the influences of infill on crack patterns, load-displacement response and specimen strength. The numerical code RFPA2D (Rock Failure Process Analysis) featured by the capability of modeling heterogeneous materials is employed to develop the numerical model, which is further calibrated by physical tests. The results indicate that there exists a critical infill strength which controls crack patterns for a given flaw inclination angle. For case of infill strength lower than the critical value, the secondary or anti-cracks are disappeared by increasing the infill strength. If the infill strength is greater than the critical value, the filled flaw has little influence on the cracking path and the specimen fails by an inclined crack, as if there is no flaw. The load-displacement responses show specimen stiffness increases by increasing infill strength until the infill strength reaches its critical value. The specimen strength increases by increasing the infill strength and almost keeps constant as the infill strength exceeds its critical value.

  17. Intentionally Flawed Manuscripts as Means for Teaching Students to Critically Evaluate Scientific Papers

    Science.gov (United States)

    Ferenc, Jaroslav; Cervenák, Filip; Bircák, Erik; Juríková, Katarína; Goffová, Ivana; Gorilák, Peter; Huraiová, Barbora; Plavá, Jana; Demecsová, Loriana; Duríková, Nikola; Galisová, Veronika; Gazdarica, Matej; Puškár, Marek; Nagy, Tibor; Nagyová, Sona; Mentelová, Lucia; Slaninová, Miroslava; Ševcovicová, Andrea; Tomáška, Lubomír

    2018-01-01

    As future scientists, university students need to learn how to avoid making errors in their own manuscripts, as well as how to identify flaws in papers published by their peers. Here we describe a novel approach on how to promote students' ability to critically evaluate scientific articles. The exercise is based on instructing teams of students to…

  18. CLEAVAGE FRACTURE ANALYSIS OF CLADDED BEAMS WITH AN EMBEDDED FLAW UNDER FOUR-POINT BENDING

    International Nuclear Information System (INIS)

    Yin, Shengjun; Williams, Paul T; Bass, Bennett Richard

    2008-01-01

    Semi-large scale embedded flaw beams were tested at Nuclear Research Institute (NRI) Rez in the Czech Republic for the 6th Network for Evaluating Structural Components (NESC-VI) project. The experiments included, among others, a series of semi-large scale tests on cladded beam specimens containing simulated sub-clad flaws. Oak Ridge National Laboratory (ORNL) conducted numerical studies to analyze the constraint issues associated with embedded flaws using various fracture mechanics methods, including T-Stress, hydrostatic stress based QH stress, and the Weibull stress model. The recently developed local approach using the modified Weibull stress model combined with the Master Curve methodology was also utilized to predict the failure probability (Pf) of semi-large scale beams. For this study, the Weibull statistical model associated with the Master Curve methodology was employed to stochastically simulate the fracture toughness data using the available Master Curve reference temperature T0 for the tested base material from the 'aged' WWER-440 Reactor Pressure Vessel (RPV). The study was also conducted to investigate the sensitivity of predicated probability of failure of semi-large scale beams with embedded flaw with different Weibull shape parameters, m

  19. Advantages of using 192Ir γ-ray flaw detector for some products

    International Nuclear Information System (INIS)

    Qin Xiqi

    1989-01-01

    This paper describes the advantages of 192 Ir γ-ray flaw detector made in China in welding seam testings. The authors made a comparison between 192 Ir γ-ray and X-ray machine. 192 Ir γ-ray machine showed many advantages, such as shorter working hours and less labour intensity

  20. Closing remarks

    International Nuclear Information System (INIS)

    Reig, J.

    2007-01-01

    Good afternoon. Before providing the closing remarks on behalf of the NEA, I would like to take this opportunity and make some personal reflections, if you allow me Mr. Chairman. I have had the opportunity to take part in the three workshops on public communication organised by the NEA. In the first one in Paris in 2000, representing my country, Spain, and in the two last ones in Ottawa in 2004 and Tokyo today, on behalf of the NEA. The topics for the three workshops follow a logical order, first the focus was on investing in trust in a time when public communication was becoming a big challenge for the regulators. Second, maintaining and measuring public confidence to assess how credible regulators are in front of the public; and finally here in Tokyo, transparency, which is a basic element to achieve trust and credibility. In my view, a regulatory decision has three main components, it has to be technically sound. legally correct and well communicated. The emphasis in the early years was in the technical matters, till legal issues became a key element to achieve the political acceptance from governments and local authorities. Finally the public communication aspects resulted into a major effort and challenge to achieve social acceptance. (author)

  1. Methods and means of the radioisotope flaw detection of the nuclear power reactors components

    International Nuclear Information System (INIS)

    Dekopov, A.S.; Majorov, A.N.; Firsov, V.G.

    1979-01-01

    Methods and means are considered for the radioisotopic flaw detection of the nuclear reactors pressure vessels and structural components of the reactor circuit. Methods of control are described as in the technological process of fabrication of the power reactors assemblies as during the systematic-preventive repair of the nuclear power station equipment during exploitation. Methodological base is given of the technology of radiation control of welded joints of the pressure vessel branch piper of the WWER-440 and WWER-1000 reactors in the process of assembling and exploitation and joining pipes with the pipe-plate of the steamgenerator in the process of fabrication. Methods of the radioisotope flaw detection in the process of exploitation take into consideration the influence of the radioisotope background, and ensure obtaining of the demanded by the rules of control, sensitivity. Methods of control of welded joints of the steamgenerator of nuclear power plants are based on the simultaneous examination of all joints with application of the shaped radiographic plate-holders. Special gamma-flaw-detection equipment is developed for control of the welded joints of the main branch-pipes. Design peculiarities are given of the installation for flaw detection. These installations are equipped with the system for emergency return of the radiation source into the storage position from the position for exposure. They have automatic exposure-meters for determination of the exposure time. Successfull exploitation of such installations in the Finland during assembling equipment for the nuclear reactor of the nuclear power plant ''Loviisa-1'' and in the USSR on the Novovoronezh nuclear power plant has shown possibility for detection of flaws having dimensions about 1% of the equipment used. For control of welded joints of pipes with pipe-plates at the steam generators, portable flaw-detectors are used. Sensitivity of these flaw-detectors towards detection of the wire standards has

  2. Proposal of limit moment equation applicable to planar/non-planar flaw in wall thinned pipes under bending

    International Nuclear Information System (INIS)

    Tsuji, Masataka; Meshii, Toshiyuki

    2011-01-01

    Highlights: → A limit moment equation applicable to planar/non-planar flaw of 0 ≤ θ ≤ π found in wall thinned straight pipes was proposed. → An idea to rationally classify planar/non-planar flaw in wall thinned pipes was proposed. → The equation based on the experimental observation focused on the fracture mode. - Abstract: In this paper, a limit bending moment equation applicable to all types of planar and non-planar flaws in wall-thinned straight pipes under bending was proposed. A system to rationally classify the planar/non-planar flaws in wall-thinned pipes was suggested based on experimental observations focused on the fracture mode. The results demonstrate the importance of distinguishing between axial and circumferential long flaws in wall-thinned pipes.

  3. Characterization of type, position and dimension of flaws by transit time locus curves of ultrasonic inspections - ALOK. Pt. 2

    International Nuclear Information System (INIS)

    Grohs, B.; Barbian, O.A.; Kappes, W.; Paul, H.

    1981-01-01

    With automatic ultrasonic testing, flaws can be detected and described and thus characterized according to their type, position and dimensions. During scanning of a test object, the flaws are registered by many different pathways and many different acoustic irradiation directions. The transit time locus curve represents the distance between the relfecting points of a flaw and the source in dependence of the probe position; hence, information on flaw position and dimensions can be derived from this curve. If the sound velocity is known, the transit path can then be calculated from the transit time. This requires, above all, a constant sound velocity along the whole transit path. Various methods are presented for reconstructing the flaw border in the plane of incidence. (orig./RW) [de

  4. Experimental study on reflooding in advanced tight lattice PWR

    International Nuclear Information System (INIS)

    Hori, K.; Kodama, J.; Teramae, T.

    2000-01-01

    This paper is related to the experimental study on the feasibility of core cooling by re-flooding in a large break loss of coolant accident (LOCA) for the advanced tight lattice pressurized water reactor (PWR). The tight lattice core design should be adopted to improve the conversion ratio. Major one of the key questions of such tight lattice core is the cooling capability under the re-flood condition in a large break LOCA. Forced feed bottom re-flooding experiments have been performed by use of a 4x4 triangular array rod bundle. The rod gap is 0.5 mm, 1.0 mm, or 1.5 mm. The measured peak temperature is below around 1273 K even in case of 1.0/0.5 mm rod gap. And, the evaluation based on the experimental results of rod temperatures and core pressure drop also shows that the core cooling under re-flooding condition is feasible. (author)

  5. Probabilistic Fracture Mechanics of Reactor Pressure Vessels with Populations of Flaws

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Backman, Marie [Univ. of Tennessee, Knoxville, TN (United States); Williams, Paul [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hoffman, William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Dickson, Terry [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bass, B. Richard [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Klasky, Hilda [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-01

    This report documents recent progress in developing a tool that uses the Grizzly and RAVEN codes to perform probabilistic fracture mechanics analyses of reactor pressure vessels in light water reactor nuclear power plants. The Grizzly code is being developed with the goal of creating a general tool that can be applied to study a variety of degradation mechanisms in nuclear power plant components. Because of the central role of the reactor pressure vessel (RPV) in a nuclear power plant, particular emphasis is being placed on developing capabilities to model fracture in embrittled RPVs to aid in the process surrounding decision making relating to life extension of existing plants. A typical RPV contains a large population of pre-existing flaws introduced during the manufacturing process. The use of probabilistic techniques is necessary to assess the likelihood of crack initiation at one or more of these flaws during a transient event. This report documents development and initial testing of a capability to perform probabilistic fracture mechanics of large populations of flaws in RPVs using reduced order models to compute fracture parameters. The work documented here builds on prior efforts to perform probabilistic analyses of a single flaw with uncertain parameters, as well as earlier work to develop deterministic capabilities to model the thermo-mechanical response of the RPV under transient events, and compute fracture mechanics parameters at locations of pre-defined flaws. The capabilities developed as part of this work provide a foundation for future work, which will develop a platform that provides the flexibility needed to consider scenarios that cannot be addressed with the tools used in current practice.

  6. Effect of combined loading due to bending and internal pressure on pipe flaw evaluation criteria

    International Nuclear Information System (INIS)

    Miura, Naoki; Sakai, Shinsuke

    2008-01-01

    Considering a rule for the rationalization of maintenance of Light Water Reactor piping, reliable flaw evaluation criteria are essential for determining how a detected flaw will be detrimental to continuous plant operation. Ductile fracture is one of the dominant failure modes that must be considered for carbon steel piping and can be analyzed by elastic-plastic fracture mechanics. Some analytical efforts have provided various flaw evaluation criteria using load correction factors, such as the Z-factors in the JSME codes on fitness-for-service for nuclear power plants and the section XI of the ASME boiler and pressure vessel code. The present Z-factors were conventionally determined, taking conservativity and simplicity into account; however, the effect of internal pressure, which is an important factor under actual plant conditions, was not adequately considered. Recently, a J-estimation scheme, LBB.ENGC for the ductile fracture analysis of circumferentially through-wall-cracked pipes subjected to combined loading was developed for more accurate prediction under more realistic conditions. This method explicitly incorporates the contributions of both bending and tension due to internal pressure by means of a scheme that is compatible with an arbitrary combined-loading history. In this study, the effect of internal pressure on the flaw evaluation criteria was investigated using the new J-estimation scheme. The Z-factor obtained in this study was compared with the presently used Z-factors, and the predictability of the current flaw evaluation criteria was quantitatively evaluated in consideration of the internal pressure. (author)

  7. Fracture assessment of shallow-flaw cruciform beams tested under uniaxial and biaxial loading conditions

    International Nuclear Information System (INIS)

    Bass, B.R.; McAfee, W.J.; Williams, P.T.; Pennell, W.E.

    1999-01-01

    A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed for application to the safety assessment of RPVs containing postulated shallow surface flaws. Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow, surface flaws. The cruciform beam specimens were developed at Oak Ridge National Laboratory (ORNL) to introduce a far-field, out-of-plane biaxial stress component in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock or pressure-temperature loading of an RPV. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for an RPV material. The cruciform fracture toughness data were used to evaluate fracture methodologies for predicting the observed effects of biaxial loading on shallow-flaw fracture toughness. Initial emphasis was placed on assessment of stress-based methodologies, namely, the J-Q formulation, the Dodds-Anderson toughness scaling model, and the Weibull approach. Applications of these methodologies based on the hydrostatic stress fracture criterion indicated an effect of loading-biaxiality on fracture toughness; the conventional maximum principal stress criterion indicated no effect. A three-parameter Weibull model based on the hydrostatic stress criterion is shown to correlate with the experimentally observed biaxial effect on cleavage fracture toughness by providing a scaling mechanism between uniaxial and biaxial loading states. (orig.)

  8. Flawed foundations of associationism? Comments on Machado and Silva (2007).

    Science.gov (United States)

    Gallistel, C R

    2007-10-01

    A. Machado and F. J. Silva have spotted an important conceptual problem in scalar expectancy theory's account of the 2-standard-interval time-left experiment. C. R. Gallistel and J. Gibbon (2000) were aware of it but did not discuss it for historical and sociological reasons, owned up to in this article. A problem of broader significance for psychology, cognitive science, neuroscience, and the philosophy of mind concerns the closely related concepts of a trial and of temporal pairing, which are foundational in associative theories of learning and memory. Association formation is assumed to depend on the temporal pairing of the to-be-associated events. In modeling it, theorists have assumed continuous time to be decomposable into trials. But life is not composed of trials, and attempts to specify the conditions under which two events may be regarded as temporally paired have never succeeded. Thus, associative theories of learning and memory are built on conceptual sand. Undeterred, neuroscientists have defined the neurobiology-of-memory problem as the problem of determining the cellular and molecular mechanism of association formation, and connectionist modelers have made it a cornerstone of their efforts. More conceptual analysis is indeed needed. Copyright 2007 APA, all rights reserved.

  9. Numerical simulation of flow behavior in tight lattice rod bundle

    International Nuclear Information System (INIS)

    Yu Yiqi; Yang Yanhua; Gu Hanyang; Cheng Xu; Song Xiaoming; Wang Xiaojun

    2009-01-01

    The Numerical investigation is performed on the air turbulent flow in triangular rod bundle array. Based on the experimental data, the eddy viscosity turbulent model and the Reynold stress turbulent model are evaluated to simulate the flow behavior in the tight lattice. The results show that SSG Reynolds Stress Model has shown superior predictive performance than other Reynolds-stress models, which indicates that the simulation of the anisotropy of the turbulence is significant in the tight lattice. The result with different Reynolds number and geometry shows that the magnitude of the secondary flow is almost independent of the Reynolds number, but it increases with the decrease of the P/D. (authors)

  10. Expression patterns of tight junction components induced by CD24 in an oral epithelial cell-culture model correlated to affected periodontal tissues.

    Science.gov (United States)

    Ye, P; Yu, H; Simonian, M; Hunter, N

    2014-04-01

    Previously we demonstrated uniformly strong expression of CD24 in the epithelial attachment to the tooth and in the migrating epithelium of the periodontitis lesion. Titers of serum antibodies autoreactive with CD24 peptide correlated with reduced severity of periodontal disease. Ligation of CD24 expressed by oral epithelial cells induced formation of tight junctions that limited paracellular diffusion. In this study, we aimed to reveal that the lack of uniform expression of tight junction components in the pocket epithelium of periodontitis lesions is likely to contribute to increased paracellular permeability to bacterial products. This is proposed as a potential driver of the immunopathology of periodontitis. An epithelial culture model with close correspondence for expression patterns for tight junction components in periodontal epithelia was used. Immunohistochemical staining and confocal laser scanning microscopy were used to analyse patterns of expression of gingival epithelial tight junction components. The minimally inflamed gingival attachment was characterized by uniformly strong staining at cell contacts for the tight junction components zona occludens-1, zona occludens-2, occludin, junction adhesion molecule-A, claudin-4 and claudin-15. In contrast, the pocket epithelium of the periodontal lesion showed scattered, uneven staining for these components. This pattern correlated closely with that of unstimulated oral epithelial cells in culture. Following ligation of CD24 expressed by these cells, the pattern of tight junction component expression of the minimally inflamed gingival attachment developed rapidly. There was evidence for non-uniform and focal expression only of tight junction components in the pocket epithelium. In the cell-culture model, ligation of CD24 induced a tight junction expression profile equivalent to that observed for the minimally inflamed gingival attachment. Ligation of CD24 expressed by gingival epithelial cells by lectin

  11. Tight Temporal Bounds for Dataflow Applications Mapped onto Shared Resources

    NARCIS (Netherlands)

    Alizadeh Ara, H.; Geilen, M.; Basten, T.; Behrouzian, A.R.B.; Hendriks, M.; Goswami, D.

    2016-01-01

    We present an analysis method that provides tight temporal bounds for applications modeled by Synchronous Dataflow Graphs and mapped to shared resources. We consider the resource sharing effects on the temporal behaviour of the application by embedding worst case resource availability curves in the

  12. Ultra-Tightly Coupled GNSS/INS for small UAVs

    DEFF Research Database (Denmark)

    Olesen, Daniel; Jakobsen, Jakob; Knudsen, Per

    2017-01-01

    This paper describes an ultra-tight integration of a Global Navigation Satellite System ( GNSS) receiver and an Inertial Navigation System ( INS) for small Unmanned Aerial Vehicles ( UAVs). The system is based on a low-cost and low-weight GNSS Intermediate Frequency ( IF) sampler which has been...

  13. Management of Small Urethrocutaneous Fistula by Tight Ligation ...

    African Journals Online (AJOL)

    After identifying the fistulous opening, the fistula tract was circumferentially and meticulously dissected ,then the dissected tract was lifted up and the base was ligated tightly with 5/0 vicryl, the external epithelium of the dissected tract was fulgurated with the diathermy, then a second layer of local soft tissue was secured over ...

  14. A characterization of tight and dual generalized translation invariant frames

    DEFF Research Database (Denmark)

    Jakobsen, Mads Sielemann; Lemvig, Jakob

    2015-01-01

    such systems form tight frames, and when two GTI Bessel systems form dual frames for L2(G). In particular, this offers a unified approach to the theory of discrete and continuous frames and, e.g., yields well known results for discrete and continuous Gabor and wavelet systems....

  15. Envelopes of Sets of Measures, Tightness, and Markov Control Processes

    International Nuclear Information System (INIS)

    Gonzalez-Hernandez, J.; Hernandez-Lerma, O.

    1999-01-01

    We introduce upper and lower envelopes for sets of measures on an arbitrary topological space, which are then used to give a tightness criterion. These concepts are applied to show the existence of optimal policies for a class of Markov control processes

  16. Local thermal-hydraulic behaviour in tight 7-rod bundles

    International Nuclear Information System (INIS)

    Cheng, X.; Yu, Y.Q.

    2009-01-01

    Advanced water-cooled reactor concepts with tight lattices have been proposed worldwide to improve the fuel utilization and the economic competitiveness. In the present work, experimental investigations were performed on thermal-hydraulic behaviour in tight hexagonal 7-rod bundles under both single-phase and two-phase conditions. Freon-12 was used as working fluid due to its convenient operating parameters. Tests were carried out under both single-phase and two-phase flow conditions. Rod surface temperatures are measured at a fixed axial elevation and in various circumferential positions. Test data with different radial power distributions are analyzed. Measured surface temperatures of unheated rods are used for the assessment of and comparison with numerical codes. In addition, numerical simulation using sub-channel analysis code MATRA and the computational fluid dynamics (CFD) code ANSYS-10 is carried out to understand the experimental data and to assess the validity of these codes in the prediction of flow and heat transfer behaviour in tight rod bundle geometries. Numerical results are compared with experimental data. A good agreement between the measured temperatures on the unheated rod surface and the CFD calculation is obtained. Both sub-channel analysis and CFD calculation indicates that the turbulent mixing in the tight rod bundle is significantly stronger than that computed with a well established correlation.

  17. Trapping of Rydberg atoms in tight magnetic microtraps

    NARCIS (Netherlands)

    Boetes, A.Q.G.; Skannrup, R.V.; Naber, J.; Kokkelmans, S.J.J.M.F.; Spreeuw, R.J.C.

    2018-01-01

    We explore the possibility to trap Rydberg atoms in tightly confining magnetic microtraps. The trapping frequencies for Rydberg atoms are expected to be influenced strongly by magnetic-field gradients. We show that there are regimes where Rydberg atoms can be trapped. Moreover, we show that

  18. Dielectric constant of graphene-on-polarized substrate: A tight ...

    Indian Academy of Sciences (India)

    Sivabrata Sahu

    Corresponding author. E-mail: gcr@iopb.res.in. Published online 24 June 2017. Abstract. We report here a microscopic tight-binding theoretical study of the dynamic dielectric response of graphene-on-polarizable substrate with impurity. The Hamiltonian consists of first, second and third nearest- neighbour electron hopping ...

  19. Dielectric constant of graphene-on-polarized substrate: A tight ...

    Indian Academy of Sciences (India)

    2017-06-24

    Jun 24, 2017 ... We report here a microscopic tight-binding theoretical study of the dynamic dielectric response of graphene-on-polarizable substrate with impurity. The Hamiltonian consists of first, second and third nearest neighbour electron hopping interactions besides doping and substrate-induced effects on graphene.

  20. Loosen up? Cultural tightness and national entrepreneurial activity

    NARCIS (Netherlands)

    Harms, Rainer; Groen, Arend J.

    The level of entrepreneurship between countries differs consistently. A source of this variance lies in national culture differences. Recently, the cultural dimension “tightness” has been introduced in the literature. Tightness refers to the degree to which a nation has strong norms and a low

  1. Prediction of Gas Leak Tightness of Superplastically Formed Products

    NARCIS (Netherlands)

    Snippe, Q.H.C.; Meinders, Vincent T.; Barlat, F; Moon, Y.H.; Lee, M.G.

    2010-01-01

    In some applications, in this case an aluminium box in a subatomic particle detector containing highly sensitive detecting devices, it is important that a formed sheet should show no gas leak from one side to the other. In order to prevent a trial-and-error procedure to make this leak tight box, a

  2. Sit-Tight Syndrome and Tenure Elongation in African Politics ...

    African Journals Online (AJOL)

    The post-independence politics of African countries has been dominated by the phenomenon of sit-tight African heads of state and government who had acceeded to office by election or coup d'etat. This paper examines this recurring problem in post-independence African politics by examining its general and specific ...

  3. Unconventional Tight Reservoirs Characterization with Nuclear Magnetic Resonance

    Science.gov (United States)

    Santiago, C. J. S.; Solatpour, R.; Kantzas, A.

    2017-12-01

    The increase in tight reservoir exploitation projects causes producing many papers each year on new, modern, and modified methods and techniques on estimating characteristics of these reservoirs. The most ambiguous of all basic reservoir property estimations deals with permeability. One of the logging methods that is advertised to predict permeability but is always met by skepticism is Nuclear Magnetic Resonance (NMR). The ability of NMR to differentiate between bound and movable fluids and providing porosity increased the capability of NMR as a permeability prediction technique. This leads to a multitude of publications and the motivation of a review paper on this subject by Babadagli et al. (2002). The first part of this presentation is dedicated to an extensive review of the existing correlation models for NMR based estimates of tight reservoir permeability to update this topic. On the second part, the collected literature information is used to analyze new experimental data. The data are collected from tight reservoirs from Canada, the Middle East, and China. A case study is created to apply NMR measurement in the prediction of reservoir characterization parameters such as porosity, permeability, cut-offs, irreducible saturations etc. Moreover, permeability correlations are utilized to predict permeability. NMR experiments were conducted on water saturated cores. NMR T2 relaxation times were measured. NMR porosity, the geometric mean relaxation time (T2gm), Irreducible Bulk Volume (BVI), and Movable Bulk Volume (BVM) were calculated. The correlation coefficients were computed based on multiple regression analysis. Results are cross plots of NMR permeability versus the independently measured Klinkenberg corrected permeability. More complicated equations are discussed. Error analysis of models is presented and compared. This presentation is beneficial in understanding existing tight reservoir permeability models. The results can be used as a guide for choosing

  4. Development of flaw evaluation and acceptance procedures for flaw indications in the cooling water system at the Savannah River site K reactor

    International Nuclear Information System (INIS)

    Tandon, S.; Bamford, W.H.; Cowfer, C.D.; Ostrowski, R.

    1993-01-01

    This paper describes the methodology used in determining the criteria for acceptance of inspection indications in the K-Reactor Cooling Water System at the Savannah River Plant. These criteria have been developed in a manner consistent with the development of similar criteria in the ASME Code Section XI for commercial light water reactors, but with a realistic treatment of the operating conditions in the cooling water system. The technical basis for the development of these criteria called ''Acceptance Standards'' is contained in this paper. A second portion of this paper contains the methodology used in the construction of flaw evaluation charts which have been developed for each specific line size in the cooling water system. The charts provide the results of detailed fracture mechanics calculations which have been completed to determine the largest flaw which can be accepted in the cooling water system without repair. These charts are designed for use in conjunction with in-service inspections of the cooling water system, and only require inspection results to determine acceptability

  5. Computational reduction of specimen noise to enable improved thermography characterization of flaws in graphite polymer composites

    Science.gov (United States)

    Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

    2014-05-01

    Flaw detection and characterization with thermographic techniques in graphite polymer composites are often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These result in a "noise" floor that increases the difficulty of detecting and characterizing deeper flaws. A method is presented for computationally removing a significant amount of the "noise" from near surface porosity by diffusing the early time response, then subtracting it from subsequent responses. Simulations of the thermal response of a composite are utilized in defining the limitations of the technique. This method for reducing the data is shown to give considerable improvement characterizing both the size and depth of damage. Examples are shown for data acquired on specimens with fabricated delaminations and impact damage.

  6. Development of portable phased array UT system for real-time flaw imaging

    International Nuclear Information System (INIS)

    Goto, M.

    1995-01-01

    Many functions and features of phased array UT technology must be useful for NDE in the industrial field. Some phased array UT systems have been developed for the inspection of nuclear pressure vessel and turbine components. However, phased array UT is still a special NDE technique and it has not been used widely in the past. The reasons of that are system size, cost, operator performance, equipment design and others. TOSHIBA has newly developed PC controlled portable phased array system to solve those problems. The portable phased array UT system is very compact and light but it is able to drive up to 32-channel linear array probe, to display real-time linear/sector B-scan, to display accumulated B-scan with an encoder and to display profile overlaid B-scan. The first applications were turbine component inspections for precise flaw investigation and flaw image data recording

  7. Evaluation of J-integral estimation scheme for flawed throughwall pipes

    Energy Technology Data Exchange (ETDEWEB)

    Zahoor, A.

    1987-02-01

    The accuracy of the EPRI J-integral estimation scheme for pipes with throughwall cracks and subjected to pure bending was assessed using available experimental data on circumferentially flawed throughwall pipes. The evaluations were performed using elastic plastic J-integral (J) and tearing modulus (T) analysis methods. The results indicated that the EPRI J estimation scheme solutions are unnecessarily conservative compared to results from pipe experiments. As a result of these evaluations an improved J estimation scheme is developed, which is shown to have improved accuracy compared to the original EPRI J estimation scheme. These results imply that the flaw evaluation procedures in the ASME Code on austenitic piping welds are conservative. These results also have applications to the leak before break fracture mechanics analyses.

  8. Evaluation of J-integral estimation scheme for flawed throughwall pipes

    International Nuclear Information System (INIS)

    Zahoor, A.

    1987-01-01

    The accuracy of the EPRI J-integral estimation scheme for pipes with throughwall cracks and subjected to pure bending was assessed using available experimental data on circumferentially flawed throughwall pipes. The evaluations were performed using elastic plastic J-integral (J) and tearing modulus (T) analysis methods. The results indicated that the EPRI J estimation scheme solutions are unnecessarily conservative compared to results from pipe experiments. As a result of these evaluations an improved J estimation scheme is developed, which is shown to have improved accuracy compared to the original EPRI J estimation scheme. These results imply that the flaw evaluation procedures in the ASME Code on austenitic piping welds are conservative. These results also have applications to the leak before break fracture mechanics analyses. (orig.)

  9. Computational Reduction of Specimen Noise to Enable Improved Thermography Characterization of Flaws in Graphite Polymer Composites

    Science.gov (United States)

    Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

    2014-01-01

    Flaw detection and characterization with thermographic techniques in graphite polymer composites are often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These result in a "noise" floor that increases the difficulty of detecting and characterizing deeper flaws. A method is presented for computationally removing a significant amount of the "noise" from near surface porosity by diffusing the early time response, then subtracting it from subsequent responses. Simulations of the thermal response of a composite are utilized in defining the limitations of the technique. This method for reducing the data is shown to give considerable improvement characterizing both the size and depth of damage. Examples are shown for data acquired on specimens with fabricated delaminations and impact damage.

  10. Visualization of flaws within heavy section ultrasonic test blocks using high energy computed tomography

    International Nuclear Information System (INIS)

    House, M.B.; Ross, D.M.; Janucik, F.X.; Friedman, W.D.; Yancey, R.N.

    1996-05-01

    The feasibility of high energy computed tomography (9 MeV) to detect volumetric and planar discontinuities in large pressure vessel mock-up blocks was studied. The data supplied by the manufacturer of the test blocks on the intended flaw geometry were compared to manual, contact ultrasonic test and computed tomography test data. Subsequently, a visualization program was used to construct fully three-dimensional morphological information enabling interactive data analysis on the detected flaws. Density isosurfaces show the relative shape and location of the volumetric defects within the mock-up blocks. Such a technique may be used to qualify personnel or newly developed ultrasonic test methods without the associated high cost of destructive evaluation. Data is presented showing the capability of the volumetric data analysis program to overlay the computed tomography and destructive evaluation (serial metallography) data for a direct, three-dimensional comparison

  11. Arc-discharge system for nondestructive detection of flaws in thin ceramic coatings

    International Nuclear Information System (INIS)

    Scott, G.W.; Davis, E.V.

    1978-04-01

    The feasibility of nondestructively detecting small cracks or holes in plasma-sprayed ceramic coatings with an electric arc-discharge system was studied. We inspected ZrO 2 coatings 0.46 mm (0.018 in.) thick on Incoloy alloy 800 substrates. Cracks were artificially induced in controlled areas of the specimens by straining the substrates in tension. We designed and built a system to scan the specimen's surface at approximately 50 μm (0.002 in.) clearance with a sharp-pointed metal-tipped probe at high dc potential. The system measures the arc currents occurring at flaws, or plots a map of the scanned area showing points where the arc current exceeds a preset threshold. A theoretical model of the probe-specimen circuit shows constant dc potential to be the best choice for arc-discharge inspection of insulating coatings. Experimental observations and analysis of the data disclosed some potential for flaw description

  12. Continuous AE monitoring of nuclear plants to detect flaws - status and future

    International Nuclear Information System (INIS)

    Hutton, P.H.

    1986-01-01

    This paper gives a brief commentary on the evolution of acoustic emission (AE) technology for continuous monitoring of nuclear reactors and the current status. The technical work described to support the status description has the objective of developing and validating the use of AE to detect, locate, and evaluate growing flaws in reactor pressure boundaries. The future of AE for continuous monitoring is discussed in terms of envisioned applications and further accomplishments required to achieve them. 12 refs.

  13. A procedure to detect flaws inside large size marble blocks by ultrasound

    OpenAIRE

    Bramanti, Mauro; Bozzi, Edoardo

    1999-01-01

    In stone and marble industry there is considerable interest in the possibility of using ultrasound diagnostic techniques for non-destructive testing of large size blocks in order to detect internal flaws such as faults, cracks and fissures. In this paper some preliminary measurements are reported in order to acquire basic knowledge of the fundamental properties of ultrasound, such as propagation velocity and attenuation, in the media here considered. We then outline a particular diagnostic pr...

  14. Detection and characterization of flaws in segments of light water reactor pressure vessels

    International Nuclear Information System (INIS)

    Cook, K.V.; Cunningham, R.A. Jr.; McClung, R.W.

    1988-01-01

    Studies have been conducted to determine flaw density in segments cut from light water reactor )LWR) pressure vessels as part of the Oak Ridge National Laboratory's Heavy-Section Steel Technology (H SST) Program. Segments from the Hope Creek Unit 2 vessel and the Pilgrim Unit 2 Vessel were purchased from salvage dealers. Hope Creek was a boiling water reactor (BWR) design and Pilgrim was a pressurized water reactor (PWR) design. Neither were ever placed in service. Objectives were to evaluate these LWR segments for flaws with ultrasonic and liquid penetrant techniques. Both objectives were successfully completed. One significant indication was detected in a Hope Creek seam weld by ultrasonic techniques and characterized by further analyses terminating with destructive correlation. This indication [with a through-wall dimension of ∼6 mm (∼0.24 in.)] was detected in only 3 m (10 ft) of weldment and offers extremely limited data when compared to the extent of welding even in a single pressure vessel. However, the detection and confirmation of the flaw in the arbitrarily selected sections implies the Marshall report estimates (and others) are nonconservative for such small flaws. No significant indications were detected in the Pilgrim material by ultrasonic techniques. Unfortunately, the Pilgrim segments contained relatively little weldment; thus, we limited our ultrasonic examinations to the cladding and subcladding regions. Fluorescent liquid penetrant inspection of the cladding surfaces for both LWR segments detected no significant indications [i.e., for a total of approximately 6.8 m 2 (72 ft 2 ) of cladding surface]. (author)

  15. Automated eddy-current installation AVD-01 for detecting flaws in fuel element cans

    International Nuclear Information System (INIS)

    Varvaritsa, V.P.; Martishchenko, L.G.; Popov, V.K.; Romanov, M.L.; Shlepnev, I.O.; Shmatok, V.P.

    1986-01-01

    This paper describes an automated installation for eddy-current flaw detection in thin-walled pipes with small diameter; its unified transport system makes it possible to use the installation in inspection lines and production lines of fuel elements. The article describes the structural diagrams of the installation and presents the results of investigations connected with the selection for establishing the optimum regimes and sensitivity of feedthrough transducers with focusing screens

  16. Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Holditch; A. Daniel Hill; D. Zhu

    2007-06-19

    The objectives of this project are to develop and test new techniques for creating extensive, conductive hydraulic fractures in unconventional tight gas reservoirs by statistically assessing the productivity achieved in hundreds of field treatments with a variety of current fracturing practices ranging from 'water fracs' to conventional gel fracture treatments; by laboratory measurements of the conductivity created with high rate proppant fracturing using an entirely new conductivity test - the 'dynamic fracture conductivity test'; and by developing design models to implement the optimal fracture treatments determined from the field assessment and the laboratory measurements. One of the tasks of this project is to create an 'advisor' or expert system for completion, production and stimulation of tight gas reservoirs. A central part of this study is an extensive survey of the productivity of hundreds of tight gas wells that have been hydraulically fractured. We have been doing an extensive literature search of the SPE eLibrary, DOE, Gas Technology Institute (GTI), Bureau of Economic Geology and IHS Energy, for publicly available technical reports about procedures of drilling, completion and production of the tight gas wells. We have downloaded numerous papers and read and summarized the information to build a database that will contain field treatment data, organized by geographic location, and hydraulic fracture treatment design data, organized by the treatment type. We have conducted experimental study on 'dynamic fracture conductivity' created when proppant slurries are pumped into hydraulic fractures in tight gas sands. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially; we pump proppant/frac fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. From such tests, we expect to gain new insights into some of the critical

  17. Flaw evaluation of Nd:YAG laser welding based plume shape by infrared thermal camera

    International Nuclear Information System (INIS)

    Kim, Jae Yeol; Yoo, Young Tae; Yang, Dong Jo; Song, Kyung Seol; Ro, Kyoung Bo

    2003-01-01

    In Nd:YAG laser welding evaluation methods of welding flaw are various. But, the method due to plume shape is difficult to classification od welding flaw. The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. At the present time, some methods are studied for measurement of plume shape by using high-speed camera and photo diode. This paper describes the machining characteristics of SM45C carbon steel welding by use of an Nd:YAG laser. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. In this study, plume shape was measured by infrared thermal camera that is non-contact/non-destructive thermal measurement equipment through change of laser generating power, speed, focus. Weld was performed on bead-on method. Measurement results are compared as two equipment. Here, two results are composed of measurement results of plume quantities due to plume shape by infrared thermal camera and inspection results of weld bead include weld flaws by ultrasonic inspector.

  18. Ligament rupture and unstable burst behaviors of axial flaws in steam generator U-bends

    Energy Technology Data Exchange (ETDEWEB)

    Bahn, Chi Bum, E-mail: bahn@pusan.ac.kr [Pusan National University, 2 Busandaehak-ro 63 beon-gil, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Oh, Young-Jin [KEPCO Engineering & Construction Co. Inc., Seongnam 463-870 (Korea, Republic of); Majumdar, Saurin [Argonne National Laboratory, Lemont, IL 60439 (United States)

    2015-11-15

    Highlights: • Ligament rupture and unstable burst pressure tests were conducted with U-bends. • In general, U-bends showed higher ligament rupture and burst pressures than straight tubes. • U-bend test data was bounded by 90% lower limit of the probabilistic models for straight tubes. • Prediction models for straight tubes could be conservatively applied to U-bends. - Abstract: Incidents of U-bend cracking in steam generator (SG) tubes have been reported, some of which have led to tube rupture. Experimental and analytical modeling efforts to determine the failure criteria of flawed SG U-bends are limited. To evaluate structural integrity of flawed U-bends, ligament rupture and unstable burst pressure tests were conducted on 57 and 152 mm bend radius U-bends with axial electrical discharge machining notches. In general, the ligament rupture and burst pressures of the U-bends were higher than those of straight tubes with similar notches. To quantitatively address the test data scatter issue, probabilistic models were introduced. All ligament rupture and burst pressures of U-bends were bounded by 90% lower limits of the probabilistic models for straight tubes. It was concluded that the prediction models for straight tubes could be applied to U-bends to conservatively evaluate the ligament rupture and burst pressures of U-bends with axial flaws.

  19. Ligament rupture and unstable burst behaviors of axial flaws in steam generator U-bends

    International Nuclear Information System (INIS)

    Bahn, Chi Bum; Oh, Young-Jin; Majumdar, Saurin

    2015-01-01

    Highlights: • Ligament rupture and unstable burst pressure tests were conducted with U-bends. • In general, U-bends showed higher ligament rupture and burst pressures than straight tubes. • U-bend test data was bounded by 90% lower limit of the probabilistic models for straight tubes. • Prediction models for straight tubes could be conservatively applied to U-bends. - Abstract: Incidents of U-bend cracking in steam generator (SG) tubes have been reported, some of which have led to tube rupture. Experimental and analytical modeling efforts to determine the failure criteria of flawed SG U-bends are limited. To evaluate structural integrity of flawed U-bends, ligament rupture and unstable burst pressure tests were conducted on 57 and 152 mm bend radius U-bends with axial electrical discharge machining notches. In general, the ligament rupture and burst pressures of the U-bends were higher than those of straight tubes with similar notches. To quantitatively address the test data scatter issue, probabilistic models were introduced. All ligament rupture and burst pressures of U-bends were bounded by 90% lower limits of the probabilistic models for straight tubes. It was concluded that the prediction models for straight tubes could be applied to U-bends to conservatively evaluate the ligament rupture and burst pressures of U-bends with axial flaws.

  20. Gamma flaw detectors for radiographic control of welded joint quality under mounting conditions

    International Nuclear Information System (INIS)

    Khoroshev, V.N.; Galash, T.F.; Andreev, V.L.; Grigor'ev, V.M.; Medvedev, N.E.

    1978-01-01

    Main characteristics are presented of gamma flaw detector models used for radiographic control of the quality of welded steel and pipeline joints during assembly. Specially developed experimental models, operating with 75 Se, 90 Sr, 170 Tm, 137 Cs and 192 Ir sources are considered. The new instruments have been made on a single structural base, which creates a foundation for standardizing individual units of radiation heads, manual control panels, containers, exterior packings, devices and accessories, maintenance techniques, and repair techniques. They are distinguished by small sizes and weight, possibility of using a set of radiation sources ensuring control of 3-40 mm thick joints, and reliable protection. Special devices permit to reduce 2-3-folds the time needed for installing and orienting the flaw detectors. The expected economic effect from implementation of the new gamma flaw detectors into industry will amount to 1.5-10.0 thousand roubles per annum for one detector at approximate cost of each detector equal to 3.5-6.0 thousand roubles

  1. Flaw tolerance vs. performance: A tradeoff in metallic glass cellular structures

    International Nuclear Information System (INIS)

    Chen, Wen; Liu, Ze; Robinson, Hannah Mae; Schroers, Jan

    2014-01-01

    Stochastic cellular structures are prevalent in nature and engineering materials alike. They are difficult to manipulate and study systematically and almost always contain imperfections. To design and characterize various degrees of imperfections in perfect periodic, stochastic and natural cellular structures, we fabricate a broad range of metallic glass cellular structures from perfectly periodic to highly stochastic by using a novel artificial microstructure approach based on thermoplastic replication of metallic glasses. For these cellular structures, precisely controlled imperfections are implemented and their effects on the mechanical response are evaluated. It is found that the mechanical performance of the periodic structures is generally superior to that of the stochastic structures. However, the stochastic structures experience a much higher tolerance to flaws than the periodic structure, especially in the plastic regime. The different flaw tolerance is explained by the stress distribution within the various structures, which leads to an overall 'strain-hardening' behavior of the stochastic structure compared to a 'strain-softening' behavior in the periodic structure. Our findings reveal how structure, 'strain-hardening' and flaw tolerance are microscopically related in structural materials

  2. On self-propagating methodological flaws in performance normalization for strength and power sports.

    Science.gov (United States)

    Arandjelović, Ognjen

    2013-06-01

    Performance in strength and power sports is greatly affected by a variety of anthropometric factors. The goal of performance normalization is to factor out the effects of confounding factors and compute a canonical (normalized) performance measure from the observed absolute performance. Performance normalization is applied in the ranking of elite athletes, as well as in the early stages of youth talent selection. Consequently, it is crucial that the process is principled and fair. The corpus of previous work on this topic, which is significant, is uniform in the methodology adopted. Performance normalization is universally reduced to a regression task: the collected performance data are used to fit a regression function that is then used to scale future performances. The present article demonstrates that this approach is fundamentally flawed. It inherently creates a bias that unfairly penalizes athletes with certain allometric characteristics, and, by virtue of its adoption in the ranking and selection of elite athletes, propagates and strengthens this bias over time. The main flaws are shown to originate in the criteria for selecting the data used for regression, as well as in the manner in which the regression model is applied in normalization. This analysis brings into light the aforesaid methodological flaws and motivates further work on the development of principled methods, the foundations of which are also laid out in this work.

  3. An engineering approach for examining crack growth and stability in flawed structures

    International Nuclear Information System (INIS)

    Shih, C.F.; German, M.D.; Kumar, V.

    1981-01-01

    Progress made in two research programmes, sponsored by the Electric Power Research Institute (EPRI), to identify viable parameters for characterising crack initiation and continued extension are summarised. An engineering/design methodology, based on these parameters, for the assessment of crack growth and instability in engineering structures which are stressed beyond the regime of applicability of linear elastic fracture mechanics is developed. The ultimate goal in the development of such a methodology is to establish an improved basis for analysing the effect of flaws (postulated or detected) on the safety margins of pressure boundary components of light water-cooled type nuclear steam supply systems. The methodology can also be employed for structural integrity analyses of other engineering components. Extensive experimental and analytical investigations undertaken to evaluate potential criteria for crack initiation and growth and the selection of the final criteria for analysing crack growth and stability in flawed structures are summarised. The experimental and analytical results obtained to date suggest that parameters based on the J-integral and the crack tip opening displacement, delta, are the most promising. This is not surprising since, from a theoretical basis, the two approaches are similar if certain conditions are met. An engineering/design approach for the assessment of crack growth and instability in flawed structures is outlined. (author)

  4. Tight binding simulation study on zigzag single-walled carbon nanotubes

    Science.gov (United States)

    Sharma, Deepa; Jaggi, Neena; Gupta, Vishu

    2018-01-01

    Tight binding simulation studies using the density functional tight binding (DFTB) model have been performed on various zigzag single-walled carbon-nanotubes (SWCNTs) to investigate their electronic properties using DFTB module of the Material Studio Software version 7.0. Various combinations of different eigen-solvers and charge mixing schemes available in the DFTB Module have been tried to chalk out the electronic structure. The analytically deduced values of the bandgap of (9, 0) SWCNT were compared with the experimentally determined value reported in the literature. On comparison, it was found that the tight binding approximations tend to drastically underestimate the bandgap values. However, the combination of Anderson charge mixing method with standard eigensolver when implemented using the smart algorithm was found to produce fairly close results. These optimized model parameters were then used to determine the band structures of various zigzag SWCNTs. (9, 0) Single-walled Nanotube which is extensively being used for sensing NH3, CH4 and NO2 has been picked up as a reference material since its experimental bandgap value has been reported in the literature. It has been found to exhibit a finite energy bandgap in contrast to its expected metallic nature. The study is of utmost significance as it not only probes and validates the simulation route for predicting suitable properties of nanomaterials but also throws light on the comparative efficacy of the different approximation and rationalization quantum mechanical techniques used in simulation studies. Such simulation studies if used intelligently prove to be immensely useful to the material scientists as they not only save time and effort but also pave the way to new experiments by making valuable predictions.

  5. Preconditioning Filter Bank Decomposition Using Structured Normalized Tight Frames

    Directory of Open Access Journals (Sweden)

    Martin Ehler

    2015-01-01

    Full Text Available We turn a given filter bank into a filtering scheme that provides perfect reconstruction, synthesis is the adjoint of the analysis part (so-called unitary filter banks, all filters have equal norm, and the essential features of the original filter bank are preserved. Unitary filter banks providing perfect reconstruction are induced by tight generalized frames, which enable signal decomposition using a set of linear operators. If, in addition, frame elements have equal norm, then the signal energy is spread through the various filter bank channels in some uniform fashion, which is often more suitable for further signal processing. We start with a given generalized frame whose elements allow for fast matrix vector multiplication, as, for instance, convolution operators, and compute a normalized tight frame, for which signal analysis and synthesis still preserve those fast algorithmic schemes.

  6. Empirical tight-binding parameters for solid C60

    International Nuclear Information System (INIS)

    Tit, N.; Kumar, V.

    1993-01-01

    We present a tight-binding model for the electronic structure of C 60 using four (1s and 3p) orbitals per carbon atom. The model has been developed by fitting the tight-binding parameters to the ab-initio pseudopotential calculation of Troullier and Martins (Phys. Rev. B46, 1754 (1992)) in the face-centered cubic (Fm3-bar) phase. Following this, calculations of the energy bands and the density of electronic states have been carried out as a function of the lattice constant. Good agreement has been obtained with the observed lattice-constant dependence of T c using McMillan's formula. Furthermore, calculations of the electronic structure are presented in the simple cubic (Pa3-bar) phase. (author). 43 refs, 3 figs, 1 tab

  7. Critical heat flux experiments in tight lattice core

    Energy Technology Data Exchange (ETDEWEB)

    Kureta, Masatoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-12-01

    Fuel rods of the Reduced-Moderation Water Reactor (RMWR) are so designed to be in tight lattices as to reduce moderation and achieve higher conversion ratio. As for the BWR type reactor coolant flow rate is reduced small compared with the existing BWR, so average void fraction comes to be langer. In order to evaluate thermo hydraulic characteristics of designed cores, critical heat flux experiments in tight lattice core have been conducted using simulated high pressure coolant loops for both the PWR and BWR seven fuel rod bundles. Experimental data on critical heat flux for full bundles have been accumulated and applied to assess the critical power of designed cores using existing codes. Evaluated results are conservative enough to satisfy the limiting condition. Further experiments on axial power distribution effects and 37 fuel rod bundle tests will be performed to validate thermohydraulic characteristics of designed cores. (T. Tanaka)

  8. Critical heat flux experiments in tight lattice core

    International Nuclear Information System (INIS)

    Kureta, Masatoshi

    2002-01-01

    Fuel rods of the Reduced-Moderation Water Reactor (RMWR) are so designed to be in tight lattices as to reduce moderation and achieve higher conversion ratio. As for the BWR type reactor coolant flow rate is reduced small compared with the existing BWR, so average void fraction comes to be langer. In order to evaluate thermo hydraulic characteristics of designed cores, critical heat flux experiments in tight lattice core have been conducted using simulated high pressure coolant loops for both the PWR and BWR seven fuel rod bundles. Experimental data on critical heat flux for full bundles have been accumulated and applied to assess the critical power of designed cores using existing codes. Evaluated results are conservative enough to satisfy the limiting condition. Further experiments on axial power distribution effects and 37 fuel rod bundle tests will be performed to validate thermohydraulic characteristics of designed cores. (T. Tanaka)

  9. Tight multilattices calculated by extended-cell cylindrization

    Energy Technology Data Exchange (ETDEWEB)

    Segev, M; Carmona, S

    1983-01-01

    Among the common features of advanced LWR concepts are the tightness of lattices and the symbiotic setting of different fuels. Such symbioses often come in the form of multilattices, whose numerically-repeated unit is a configuration of several pins, typically with one pin type at the center and pins of a second type surrounding the center pin. If this extended-cell (EC) unit is cylindricized, then a simple transport calculation of the unit will be possible. If the lattice of such units is tight, there is further an a priori reason to expect the cylindrization to introduce only a small distortion of the true neutron fluxes in the lattice. A strict numerical validation of the EC cylindrization approximation is impractical, but similar validations can be carried out for regular lattices, viewed as being made up of multicell units whose centers are moderators and whose peripheries are fuel pins. In these comparisons the EC cylindrization approximation gives good results.

  10. Tight Network Topology Dependent Bounds on Rounds of Communication

    OpenAIRE

    Chattopadhyay, Arkadev; Langberg, Michael; Li, Shi; Rudra, Atri

    2016-01-01

    We prove tight network topology dependent bounds on the round complexity of computing well studied $k$-party functions such as set disjointness and element distinctness. Unlike the usual case in the CONGEST model in distributed computing, we fix the function and then vary the underlying network topology. This complements the recent such results on total communication that have received some attention. We also present some applications to distributed graph computation problems. Our main contri...

  11. Integral tightness measurements at the Paks-1 nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Taubner, R.; Techy, Z. (Villamosenergiaipari Kutato Intezet, Budapest (Hungary))

    1983-01-01

    The containment system experiments of the Paks-1 nuclear reactor are described. The integrated tightness measurements of the hermetic system were completed in 1982. The principles and methods and the evaluation of the results of the measurements are discussed. Some features of the filtration characteristics are demonstrated using relative values and a method enabling the description of the physical contents of the characteristics by flow technical functions is outlined.

  12. Quantum tight-binding chains with dissipative coupling

    International Nuclear Information System (INIS)

    Mogilevtsev, D; Slepyan, G Ya; Garusov, E; Kilin, S Ya; Korolkova, N

    2015-01-01

    We present a one-dimensional tight-binding chain of two-level systems coupled only through common dissipative Markovian reservoirs. This quantum chain can demonstrate anomalous thermodynamic behavior contradicting Fourier law. Population dynamics of individual systems of the chain is polynomial with the order determined by the initial state of the chain. The chain can simulate classically hard problems, such as multi-dimensional random walks. (paper)

  13. Thermography Control of Heat Insulation and Tightness of Buildings,

    Science.gov (United States)

    1980-11-01

    construction. The method is pedagogical . Results from thermography studies are suitable for use when giving experience feedback. (Excellent complement...visual inspection Instrument Various tools and measures. Principle The construction is opened, and the workmanship of insulation and tight- ness is...most IR cameras. At -196 C (77K) it is sensitive within the wavelength range 0 - 5.6 jam. The lower - 24 - FIGURE 3: Photography with IR camera, AGA

  14. Tightly localized stationary pulses in a multilevel atomic system

    International Nuclear Information System (INIS)

    Liu, Xiong-Jun; Oh, C. H.; Liu, Xin; Liu, Zheng-Xin; Kwek, L. C.

    2007-01-01

    We show that the pulse matching phenomenon can be obtained in the general multilevel system with electromagnetically induced transparency. For this we find a different way to create tightly localized stationary pulses by using counterpropagating pump fields. The present process is a spatial compression of excitation so that it allows us to shape and further intensify the localized stationary pulses, without using standing waves of pump fields or spatially modulated pump fields

  15. Evaluation of Manual Ultrasonic Examinations Applied to Detect Flaws in Primary System Dissimilar Metal Welds at North Anna Power Station

    International Nuclear Information System (INIS)

    Anderson, Michael T.; Diaz, Aaron A.; Doctor, Steven R.

    2012-01-01

    During a recent inservice inspection (ISI) of a dissimilar metal weld (DMW) in an inlet (hot leg) steam generator nozzle at North Anna Power Station Unit 1, several axially oriented flaws went undetected by the licensee's manual ultrasonic testing (UT) technique. The flaws were subsequently detected as a result of outside diameter (OD) surface machining in preparation for a full structural weld overlay. The machining operation uncovered the existence of two through-wall flaws, based on the observance of primary water leaking from the DMW. Further ultrasonic tests were then performed, and a total of five axially oriented flaws, classified as primary water stress corrosion cracking (PWSCC), were detected in varied locations around the weld circumference.

  16. Tight junction regulates epidermal calcium ion gradient and differentiation

    International Nuclear Information System (INIS)

    Kurasawa, Masumi; Maeda, Tetsuo; Oba, Ai; Yamamoto, Takuya; Sasaki, Hiroyuki

    2011-01-01

    Research highlights: → We disrupted epidermal tight junction barrier in reconstructed epidermis. → It altered Ca 2+ distribution and consequentially differentiation state as well. → Tight junction should affect epidermal homeostasis by maintaining Ca 2+ gradient. -- Abstract: It is well known that calcium ions (Ca 2+ ) induce keratinocyte differentiation. Ca 2+ distributes to form a vertical gradient that peaks at the stratum granulosum. It is thought that the stratum corneum (SC) forms the Ca 2+ gradient since it is considered the only permeability barrier in the skin. However, the epidermal tight junction (TJ) in the granulosum has recently been suggested to restrict molecular movement to assist the SC as a secondary barrier. The objective of this study was to clarify the contribution of the TJ to Ca 2+ gradient and epidermal differentiation in reconstructed human epidermis. When the epidermal TJ barrier was disrupted by sodium caprate treatment, Ca 2+ flux increased and the gradient changed in ion-capture cytochemistry images. Alterations of ultrastructures and proliferation/differentiation markers revealed that both hyperproliferation and precocious differentiation occurred regionally in the epidermis. These results suggest that the TJ plays a crucial role in maintaining epidermal homeostasis by controlling the Ca 2+ gradient.

  17. Vitamin D and Depression: A Systematic Review and Meta-Analysis Comparing Studies with and without Biological Flaws

    OpenAIRE

    Simon Spedding

    2014-01-01

    Efficacy of Vitamin D supplements in depression is controversial, awaiting further literature analysis. Biological flaws in primary studies is a possible reason meta-analyses of Vitamin D have failed to demonstrate efficacy. This systematic review and meta-analysis of Vitamin D and depression compared studies with and without biological flaws. The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The literature search was un...

  18. Empirical tight-binding modeling of ordered and disordered semiconductor structures; Empirische Tight-Binding-Modellierung geordneter und ungeordneter Halbleiterstrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Mourad, Daniel

    2010-11-30

    In this thesis, we investigate the electronic and optical properties of pure as well as of substitutionally alloyed II-VI and III-V bulk semiconductors and corresponding semiconductor quantum dots by means of an empirical tight-binding (TB) model. In the case of the alloyed systems of the type A{sub x}B{sub 1-x}, where A and B are the pure compound semiconductor materials, we study the influence of the disorder by means of several extensions of the TB model with different levels of sophistication. Our methods range from rather simple mean-field approaches (virtual crystal approximation, VCA) over a dynamical mean-field approach (coherent potential approximation, CPA) up to calculations where substitutional disorder is incorporated on a finite ensemble of microscopically distinct configurations. In the first part of this thesis, we cover the necessary fundamentals in order to properly introduce the TB model of our choice, the effective bond-orbital model (EBOM). In this model, one s- and three p-orbitals per spin direction are localized on the sites of the underlying Bravais lattice. The matrix elements between these orbitals are treated as free parameters in order to reproduce the properties of one conduction and three valence bands per spin direction and can then be used in supercell calculations in order to model mixed bulk materials or pure as well as mixed quantum dots. Part II of this thesis deals with unalloyed systems. Here, we use the EBOM in combination with configuration interaction calculations for the investigation of the electronic and optical properties of truncated pyramidal GaN quantum dots embedded in AlN with an underlying zincblende structure. Furthermore, we develop a parametrization of the EBOM for materials with a wurtzite structure, which allows for a fit of one conduction and three valence bands per spin direction throughout the whole Brillouin zone of the hexagonal system. In Part III, we focus on the influence of alloying on the electronic

  19. First-principles real-space tight-binding LMTO calculation of electronic structures for atomic clusters

    International Nuclear Information System (INIS)

    Xie, Z.L.; Dy, K.S.; Wu, S.Y.

    1997-01-01

    A real-space scheme has been developed for a first-principles calculation of electronic structures and total energies of atomic clusters. The scheme is based on the combination of the tight-binding linear muffin-tin orbital (TBLMTO) method and the method of real-space Green close-quote s function. With this approach, the local electronic density of states can be conveniently determined from the real-space Green close-quote s function. Furthermore, the full electron density of a cluster can be directly calculated in real space. The scheme has been shown to be very efficient due to the incorporation of the method of real-space Green close-quote s function and Delley close-quote s method of evaluating multicenter integrals. copyright 1996 The American Physical Society

  20. Pore Structure and Limit Pressure of Gas Slippage Effect in Tight Sandstone

    Science.gov (United States)

    You, Lijun; Xue, Kunlin; Kang, Yili; Liao, Yi

    2013-01-01

    Gas slip effect is an important mechanism that the gas flow is different from liquid flow in porous media. It is generally considered that the lower the permeability in porous media is, the more severe slip effect of gas flow will be. We design and then carry out experiments with the increase of backpressure at the outlet of the core samples based on the definition of gas slip effect and in view of different levels of permeability of tight sandstone reservoir. This study inspects a limit pressure of the gas slip effect in tight sandstones and analyzes the characteristic parameter of capillary pressure curves. The experimental results indicate that gas slip effect can be eliminated when the backpressure reaches a limit pressure. When the backpressure exceeds the limit pressure, the measured gas permeability is a relatively stable value whose range is less than 3% for a given core sample. It is also found that the limit pressure increases with the decreasing in permeability and has close relation with pore structure of the core samples. The results have an important influence on correlation study on gas flow in porous medium, and are beneficial to reduce the workload of laboratory experiment. PMID:24379747

  1. Electromagnetic methods for measuring materials properties of cylindrical rods and array probes for rapid flaw inspection

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Haiyan [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    The case-hardening process modifies the near-surface permeability and conductivity of steel, as can be observed through changes in alternating current potential drop (ACPD) along a rod. In order to evaluate case depth of case hardened steel rods, analytical expressions are derived for the alternating current potential drop on the surface of a homogeneous rod, a two-layered and a three-layered rod. The case-hardened rod is first modeled by a two-layer rod that has a homogeneous substrate with a single, uniformly thick, homogeneous surface layer, in which the conductivity and permeability values differ from those in the substrate. By fitting model results to multi-frequency ACPD experimental data, estimates of conductivity, permeability and case depth are found. Although the estimated case depth by the two-layer model is in reasonable agreement with the effective case depth from the hardness profile, it is consistently higher than the effective case depth. This led to the development of the three-layer model. It is anticipated that the new three-layered model will improve the results and thus makes the ACPD method a novel technique in nondestructive measurement of case depth. Another way to evaluate case depth of a case hardened steel rod is to use induction coils. Integral form solutions for an infinite rod encircled by a coaxial coil are well known, but for a finite length conductor, additional boundary conditions must be satisfied at the ends. In this work, calculations of eddy currents are performed for a two-layer conducting rod of finite length excited by a coaxial circular coil carrying an alternating current. The solution is found using the truncated region eigenfunction expansion (TREE) method. By truncating the solution region to a finite length in the axial direction, the magnetic vector potential can be expressed as a series expansion of orthogonal eigenfunctions instead of as a Fourier integral. Closed-form expressions are derived for the electromagnetic

  2. A dynamic fatigue study of soda-lime silicate and borosilicate glasses using small scale indentation flaws

    International Nuclear Information System (INIS)

    Dabbs, T.P.; Lawn, B.R.; Kelly, P.L.

    1982-01-01

    The dynamic fatigue characteristics of two glasses, soda-lime silicate and borosilicate, in water have been studied using a controlled indentation flaw technique. It is argued that the indentation approach offers several advantages over more conventional fatigue testing procedures: (i) the reproducibility of data is relatively high, eliminating statistics as a basis of analysis: (ii) the flaw ultimately responsible for failure is well defined and may be conveniently characterised before and after (and during, if necessary) the strength test; (iii) via adjustment of the indentation load, the size of the flaw can be suitably predetermined. Particular attention is devoted to the third point because of the facility it provides for systematic investigation of the range of flaw sizes over which macroscopic crack behaviour remains applicable. The first part of the paper summarises the essential fracture mechanics theory of the extension of an indentation flaw to failure. In the next part of the paper the results of dynamic fatigue tests on glass rods in distilled water are described. Data are obtained for Vickers indentation loads in the range 0.05 to 100 N, corresponding to contact dimensions of 2 to 100 μm. Finally, the implications of the results in relation to the response of 'natural' flaws are discussed. (author)

  3. Vitamin D and depression: a systematic review and meta-analysis comparing studies with and without biological flaws.

    Science.gov (United States)

    Spedding, Simon

    2014-04-11

    Efficacy of Vitamin D supplements in depression is controversial, awaiting further literature analysis. Biological flaws in primary studies is a possible reason meta-analyses of Vitamin D have failed to demonstrate efficacy. This systematic review and meta-analysis of Vitamin D and depression compared studies with and without biological flaws. The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The literature search was undertaken through four databases for randomized controlled trials (RCTs). Studies were critically appraised for methodological quality and biological flaws, in relation to the hypothesis and study design. Meta-analyses were performed for studies according to the presence of biological flaws. The 15 RCTs identified provide a more comprehensive evidence-base than previous systematic reviews; methodological quality of studies was generally good and methodology was diverse. A meta-analysis of all studies without flaws demonstrated a statistically significant improvement in depression with Vitamin D supplements (+0.78 CI +0.24, +1.27). Studies with biological flaws were mainly inconclusive, with the meta-analysis demonstrating a statistically significant worsening in depression by taking Vitamin D supplements (-1.1 CI -0.7, -1.5). Vitamin D supplementation (≥800 I.U. daily) was somewhat favorable in the management of depression in studies that demonstrate a change in vitamin levels, and the effect size was comparable to that of anti-depressant medication.

  4. Vitamin D and Depression: A Systematic Review and Meta-Analysis Comparing Studies with and without Biological Flaws

    Directory of Open Access Journals (Sweden)

    Simon Spedding

    2014-04-01

    Full Text Available Efficacy of Vitamin D supplements in depression is controversial, awaiting further literature analysis. Biological flaws in primary studies is a possible reason meta-analyses of Vitamin D have failed to demonstrate efficacy. This systematic review and meta-analysis of Vitamin D and depression compared studies with and without biological flaws. The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA guidelines. The literature search was undertaken through four databases for randomized controlled trials (RCTs. Studies were critically appraised for methodological quality and biological flaws, in relation to the hypothesis and study design. Meta-analyses were performed for studies according to the presence of biological flaws. The 15 RCTs identified provide a more comprehensive evidence-base than previous systematic reviews; methodological quality of studies was generally good and methodology was diverse. A meta-analysis of all studies without flaws demonstrated a statistically significant improvement in depression with Vitamin D supplements (+0.78 CI +0.24, +1.27. Studies with biological flaws were mainly inconclusive, with the meta-analysis demonstrating a statistically significant worsening in depression by taking Vitamin D supplements (−1.1 CI −0.7, −1.5. Vitamin D supplementation (≥800 I.U. daily was somewhat favorable in the management of depression in studies that demonstrate a change in vitamin levels, and the effect size was comparable to that of anti-depressant medication.

  5. Diagenesis and reservoir quality of the Lower Cretaceous Quantou Formation tight sandstones in the southern Songliao Basin, China

    Science.gov (United States)

    Xi, Kelai; Cao, Yingchang; Jahren, Jens; Zhu, Rukai; Bjørlykke, Knut; Haile, Beyene Girma; Zheng, Lijing; Hellevang, Helge

    2015-12-01

    later than the tight rock formation (with the porosity close to 10%). However, thicker sandstone bodies (more than 2 m) constitute potential hydrocarbon reservoirs.

  6. Energy spectrum of two-dimensional tight-binding electrons in a spatially varying magnetic field

    International Nuclear Information System (INIS)

    Oh, G.Y.; Lee, M.H.

    1996-01-01

    The electronic energy spectrum of a two-dimensional lattice in a spatially varying magnetic field is studied within the framework of the tight-binding model by using the scheme of the transfer matrix. It is found that, in comparison with the case of a uniform magnetic field, the energy spectrum exhibits more complicated behavior; band broadening (or gap closing) and band splitting (or gap opening) occur depending on characteristic parameters of the lattice. The origin of these phenomena lies in the existence of direct touching and indirect overlapping between neighboring subbands. Dependence of direct touching and indirect overlapping, and thus the electronic band structure together with the density of states, on characteristic parameters of the lattice is elucidated in detail. copyright 1996 The American Physical Society

  7. Flow and Transport in Tight and Shale Formations: A Review

    KAUST Repository

    Salama, Amgad

    2017-09-18

    A review on the recent advances of the flow and transport phenomena in tight and shale formations is presented in this work. Exploration of oil and gas in resources that were once considered inaccessible opened the door to highlight interesting phenomena that require attention and understanding. The length scales associated with transport phenomena in tight and shale formations are rich. From nanoscale phenomena to field-scale applications, a unified frame that is able to encounter the varieties of phenomena associated with each scale may not be possible. Each scale has its own tools and limitations that may not, probably, be suitable at other scales. Multiscale algorithms that effectively couple simulations among various scales of porous media are therefore important. In this article, a review of the different length scales and the tools associated with each scale is introduced. Highlights on the different phenomena pertinent to each scale are summarized. Furthermore, the governing equations describing flow and transport phenomena at different scales are investigated. In addition, methods to solve these equations using numerical techniques are introduced. Cross-scale analysis and derivation of linear and nonlinear Darcy\\'s scale laws from pore-scale governing equations are described. Phenomena occurring at molecular scales and their thermodynamics are discussed. Flow slippage at the nanosize pores and its upscaling to Darcy\\'s scale are highlighted. Pore network models are discussed as a viable tool to estimate macroscopic parameters that are otherwise difficult to measure. Then, the environmental aspects associated with the different technologies used in stimulating the gas stored in tight and shale formations are briefly discussed.

  8. Flow and Transport in Tight and Shale Formations: A Review

    KAUST Repository

    Salama, Amgad; El-Amin, Mohamed; Kumar, Kundan; Sun, Shuyu

    2017-01-01

    A review on the recent advances of the flow and transport phenomena in tight and shale formations is presented in this work. Exploration of oil and gas in resources that were once considered inaccessible opened the door to highlight interesting phenomena that require attention and understanding. The length scales associated with transport phenomena in tight and shale formations are rich. From nanoscale phenomena to field-scale applications, a unified frame that is able to encounter the varieties of phenomena associated with each scale may not be possible. Each scale has its own tools and limitations that may not, probably, be suitable at other scales. Multiscale algorithms that effectively couple simulations among various scales of porous media are therefore important. In this article, a review of the different length scales and the tools associated with each scale is introduced. Highlights on the different phenomena pertinent to each scale are summarized. Furthermore, the governing equations describing flow and transport phenomena at different scales are investigated. In addition, methods to solve these equations using numerical techniques are introduced. Cross-scale analysis and derivation of linear and nonlinear Darcy's scale laws from pore-scale governing equations are described. Phenomena occurring at molecular scales and their thermodynamics are discussed. Flow slippage at the nanosize pores and its upscaling to Darcy's scale are highlighted. Pore network models are discussed as a viable tool to estimate macroscopic parameters that are otherwise difficult to measure. Then, the environmental aspects associated with the different technologies used in stimulating the gas stored in tight and shale formations are briefly discussed.

  9. Ischemic preconditioning enhances integrity of coronary endothelial tight junctions

    International Nuclear Information System (INIS)

    Li, Zhao; Jin, Zhu-Qiu

    2012-01-01

    Highlights: ► Cardiac tight junctions are present between coronary endothelial cells. ► Ischemic preconditioning preserves the structural and functional integrity of tight junctions. ► Myocardial edema is prevented in hearts subjected to ischemic preconditioning. ► Ischemic preconditioning enhances translocation of ZO-2 from cytosol to cytoskeleton. -- Abstract: Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiac TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood–heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs–Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC enhanced the translocation of ZO-2 from cytosol to cytoskeleton. In conclusion, TJs occur in

  10. Intestinal epithelial barrier function and tight junction proteins with heat and exercise

    DEFF Research Database (Denmark)

    Dokladny, Karol; Zuhl, Micah N; Moseley, Pope L

    2016-01-01

    A single layer of enterocytes and tight junctions (intercellular multiprotein complexes) form the intestinal epithelial barrier that controls transport of molecules through transcellular and paracellular pathways. A dysfunctional or "leaky" intestinal tight junction barrier allows augmented perme...

  11. Textual and language flaws: problems for Spanish doctors in producing abstracts in English

    Directory of Open Access Journals (Sweden)

    Lourdes Divasson Cilveti

    2006-04-01

    Full Text Available Scientific journals are the primary source of information for researchers. The number of articles currently indexed in databases is so large that it has become almost impossible to read every relevant article in a particular field. Thus, research paper abstracts (RPAs have acquired increasing importance. Several studies have shown that they are the skipping point, particularly among non-native English speakers. To our knowledge, little research has been carried out on RPA writing by Spanish doctors. It is thus the objective of this article to analyse the way abstracts are structured and linguistically realized by these professionals. We selected 30 RPAs written in English by Spanish speaking doctors from three leading Spanish journals on internal medicine. We recorded their textual level flaws by measuring the degree of informativeness with regard to three main variables: move patterning, ordering and structuring, and their language use flaws under two broad categories: ortho-typographic and grammatical. Length, use of hedges and keywords were also identified. 86.6% of the abstracts were informative, 13.3% uninformative while none of them could be classified as highly informative. With regard to the authors' use of language, over 70% presented some kind of flaws: 21.55% of these mistakes were ortho-typographic while 78.44% were grammatical. Our results support the need of designing specific units geared on the one hand towards explicit teaching of structured abstracts and on the other, towards the difficulties found by doctors because they lack language competence. They would also benefit from clearer guidelines from journal editors.

  12. Does an inter-flaw length control the accuracy of rupture forecasting in geological materials?

    Science.gov (United States)

    Vasseur, Jérémie; Wadsworth, Fabian B.; Heap, Michael J.; Main, Ian G.; Lavallée, Yan; Dingwell, Donald B.

    2017-10-01

    Multi-scale failure of porous materials is an important phenomenon in nature and in material physics - from controlled laboratory tests to rockbursts, landslides, volcanic eruptions and earthquakes. A key unsolved research question is how to accurately forecast the time of system-sized catastrophic failure, based on observations of precursory events such as acoustic emissions (AE) in laboratory samples, or, on a larger scale, small earthquakes. Until now, the length scale associated with precursory events has not been well quantified, resulting in forecasting tools that are often unreliable. Here we test the hypothesis that the accuracy of the forecast failure time depends on the inter-flaw distance in the starting material. We use new experimental datasets for the deformation of porous materials to infer the critical crack length at failure from a static damage mechanics model. The style of acceleration of AE rate prior to failure, and the accuracy of forecast failure time, both depend on whether the cracks can span the inter-flaw length or not. A smooth inverse power-law acceleration of AE rate to failure, and an accurate forecast, occurs when the cracks are sufficiently long to bridge pore spaces. When this is not the case, the predicted failure time is much less accurate and failure is preceded by an exponential AE rate trend. Finally, we provide a quantitative and pragmatic correction for the systematic error in the forecast failure time, valid for structurally isotropic porous materials, which could be tested against larger-scale natural failure events, with suitable scaling for the relevant inter-flaw distances.

  13. Tight focusing of radially polarized circular Airy vortex beams

    Science.gov (United States)

    Chen, Musheng; Huang, Sujuan; Shao, Wei

    2017-11-01

    Tight focusing properties of radially polarized circular Airy vortex beams (CAVB) are studied numerically. The light field expressions for the focused fields are derived based on vectorial Debye theory. We also study the relationship between focal profiles, such as light intensity distribution, radius of focal spot and focal length, and the parameters of CAVB. Numerical results demonstrate that we can generate a radially polarized CAVB with super-long focal length, super-strong longitudinal intensity or subwavelength focused spot at the focal plane by properly choosing the parameters of incident light and high numerical aperture (NA) lens. These results have potential applications for optical trapping, optical storage and particle acceleration.

  14. Tight-Binding Parametrization for Photonic Band Gap Materials

    International Nuclear Information System (INIS)

    Lidorikis, E.; Sigalas, M.M.; Soukoulis, C.M.; Economou, E.N.; Soukoulis, C.M.

    1998-01-01

    The idea of the linear combination of atomic orbitals method, well known from the study of electrons, is extended to the classical wave case. The Mie resonances of the isolated scatterer in the classical wave case are analogous to the atomic orbitals in the electronic case. The matrix elements of the two-dimensional tight-binding (TB) Hamiltonian are obtained by fitting to ab initio results. The transferability of the TB model is tested by reproducing accurately the band structure of different 2D lattices, with and without defects, and at two different dielectric contrasts. copyright 1998 The American Physical Society

  15. Tight Bound on Randomness for Violating the CHSH Inequality

    OpenAIRE

    Teng, Yifeng; Yang, Shenghao; Wang, Siwei; Zhao, Mingfei

    2015-01-01

    Free will (or randomness) has been studied to achieve loophole-free Bell's inequality test and to provide device-independent quantum key distribution security proofs. The required randomness such that a local hidden variable model (LHVM) can violate the Clauser-Horne-Shimony-Holt (CHSH) inequality has been studied, but a tight bound has not been proved for a practical case that i) the device settings of the two parties in the Bell test are independent; and ii) the device settings of each part...

  16. Quantum correlations are tightly bound by the exclusivity principle.

    Science.gov (United States)

    Yan, Bin

    2013-06-28

    It is a fundamental problem in physics of what principle limits the correlations as predicted by our current description of nature, based on quantum mechanics. One possible explanation is the "global exclusivity" principle recently discussed in Phys. Rev. Lett. 110, 060402 (2013). In this work we show that this principle actually has a much stronger restriction on the probability distribution. We provide a tight constraint inequality imposed by this principle and prove that this principle singles out quantum correlations in scenarios represented by any graph. Our result implies that the exclusivity principle might be one of the fundamental principles of nature.

  17. Tight glycemic control in the ICU - is the earth flat?

    Science.gov (United States)

    Steil, Garry M; Agus, Michael S D

    2014-06-27

    Tight glycemic control in the ICU has been shown to reduce mortality in some but not all prospective randomized control trials. Confounding the interpretation of these studies are differences in how the control was achieved and underlying incidence of hypoglycemia, which can be expected to be affected by the introduction of continuous glucose monitoring (CGM). In this issue of Critical Care, a consensus panel provides a list of the research priorities they believe are needed for CGM to become routine practice in the ICU. We reflect on these recommendations and consider the implications for using CGM today.

  18. Containment leak-tightness enhancement at VVER 440 NPPs

    International Nuclear Information System (INIS)

    Prandorfy, M.

    2001-01-01

    The hermetic compartments of VVER 440 NPPs fulfil the function of the containment used at NPPs all over the word. The purpose of the containment is to protect the NPP personal against radioactive impact as well as to prevent radioactive leakage to the environment during a lost of coolant accident. Leak-tightness enhancement in NPPs with VVER 440/213 and VVER 440/230 reactors is an important safety issue. New procedures, measures and methods were adopted at NPPs in Mochovce, J. Bohunice, Dukovany and Paks for leak identification and sealing works performed by VUEZ Levice. (authors)

  19. Tight aspect ratio tokamak power reactor with superconducting TF coils

    International Nuclear Information System (INIS)

    Nishio, S.; Tobita, K.; Konishi, S.; Ando, T.; Hiroki, S.; Kuroda, T.; Yamauchi, M.; Azumi, M.; Nagata, M.

    2003-01-01

    Tight aspect ratio tokamak power reactor with super-conducting toroidal field (TF) coils has been proposed. A center solenoid coil system and an inboard blanket were discarded. The key point was how to find the engineering design solution of the TF coil system with the high field and high current density. The coil system with the center post radius of less than 1 m can generate the maximum field of ∼ 20 T. This coil system causes a compact reactor concept, where the plasma major and minor radii of 3.75 m and 1.9 m, respectively and the fusion power of 1.8 GW. (author)

  20. OLIFE: Tight Binding Code for Transmission Coefficient Calculation

    Science.gov (United States)

    Mijbil, Zainelabideen Yousif

    2018-05-01

    A new and human friendly transport calculation code has been developed. It requires a simple tight binding Hamiltonian as the only input file and uses a convenient graphical user interface to control calculations. The effect of magnetic field on junction has also been included. Furthermore the transmission coefficient can be calculated between any two points on the scatterer which ensures high flexibility to check the system. Therefore Olife can highly be recommended as an essential tool for pretesting studying and teaching electron transport in molecular devices that saves a lot of time and effort.

  1. Containment leak-tightness enhancement at VVER 440 NPPs

    International Nuclear Information System (INIS)

    Prandorfy, M.

    2000-01-01

    The hermetic compartments of WWER 440 NPPs fulfil the function of the containment used at NPPs all over the world. The purpose of the containment is to protect the NPP personnel against radioactive impact as well as to prevent radioactive leakage to the. environ ent during a lost of coolant accident. Leak-tightness enhancement in NPPs with WWER 440/213 and WWER 440/230 reactors is an important safety issue. New procedures, measures and methods were adopted at NPPs in Mochovce, Jaslovske Bohunice, Dukovany and PAKS for leak identification and sealing works performed by VUEZ Levice. (authors)

  2. Ductile growth of crack like flawing during hydrotest; Propagacao dutil de defeitos planares durante teste hidrostatico

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Jose C; Donato, Guilherme V [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Silva, Marcinei S. da; Bastian, Fernando L [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE); Lima, Romulo S. de [PETROBRAS/AB-RE, Rio de Janeiro, RJ (Brazil)

    2003-07-01

    In this paper effects of hydrostatic testing on ductile propagation of crack like flaw defects were evaluated in API X-60 steel. The model used was based on the J-tearing theory, supported by elastic - plastic fracture mechanics. The J-initiation resistance values (JIc) were determined by fracture mechanic tests using potential drop technique and compact test specimen. The JIc values were also determined from flow stress and Charpy V-notch at plateau, which are both usually available in mill-test data. Despite of being based on small database it seems it could be extended and it will be useful for future analysis. (author)

  3. Modelling molecular adsorption on charged or polarized surfaces: a critical flaw in common approaches.

    Science.gov (United States)

    Bal, Kristof M; Neyts, Erik C

    2018-03-28

    A number of recent computational material design studies based on density functional theory (DFT) calculations have put forward a new class of materials with electrically switchable chemical characteristics that can be exploited in the development of tunable gas storage and electrocatalytic applications. We find systematic flaws in almost every computational study of gas adsorption on polarized or charged surfaces, stemming from an improper and unreproducible treatment of periodicity, leading to very large errors of up to 3 eV in some cases. Two simple corrective procedures that lead to consistent results are proposed, constituting a crucial course correction to the research in the field.

  4. The shallow flaw effect and the local approach to cleavage fracture

    International Nuclear Information System (INIS)

    Moinereau, D.

    1996-10-01

    The capability of Beremin model to explain the shallow flaw effect in cleavage fracture is evaluated. Numerous two-dimensional finite element calculations are performed on several cracked specimens (cladded and un-cladded specimens with different values of a/W ratio) submitted to mechanical or thermal loading. The behavior of different specimens is examined using the Weibull stress σ w versus stress intensity factor K J curves. The stress fields and plastic zones at the crack tip are also compared on respective cracked specimens. (K.A.)

  5. Focussed probes ultrasonic follow-up of actual flaw growth during fatigue testing

    International Nuclear Information System (INIS)

    Cinotti, C.; Dufresne, J.; Prot, A.C.; Touffait, A.M.; Saglio, R.

    1979-01-01

    A programme was undertaken to follow-up the growth of actual flaws purposely introduced during the welding process of five test specimens. The aim of this programme is to measure the actual size of the cracks which develop from the known defects during the fatigue testing. The sizing method is based on the use of focussed probes, which allow good accuracy and repeatability, as well as good sensitivity. Examples are given of the first results: sizing before testing, then step by step during the fatigue testing and also under compression. This last point is very important in view of the ultrasonic testing during periodic in-service inspection

  6. Development of flaw assesment methodology for elevated temperature components of FBR plants

    International Nuclear Information System (INIS)

    Shimakawa, Takashi; Takahashi, Yukio; Miura, Naoki; Nakayama, Yasunari; Sawai, Tatsuaki; Tooya, Yuuji

    1999-01-01

    Fracture mechanics is applicable for the safety assessment of FBR component if a crack is assumed to exist. Inelastic response should be taken into account due to high temperature operation of FBR components. However, methodology for the application of inelastic fracture mechanics has not been established sufficiently. CRIEPI has been conducted research projects to develop a flaw assessment guideline for FBR components. This guideline consists of evaluation methods for creep-fatigue crack propagation, ductile fracture and sodium leak rate. The summary of evaluation methods on creep-fatigue crack and ductile fracture is presented in this paper. (author)

  7. Use of Master Curve technology for assessing shallow flaws in a reactor pressure vessel material

    International Nuclear Information System (INIS)

    Bass, Bennett Richard; Taylor, Nigel

    2006-01-01

    In the NESC-IV project an experimental/analytical program was performed to develop validated analysis methods for transferring fracture toughness data to shallow flaws in reactor pressure vessels subject to biaxial loading in the lower-transition temperature region. Within this scope an extensive range of fracture tests was performed on material removed from a production-quality reactor pressure vessel. The Master Curve analysis of this data is reported and its application to the assessment of the project feature tests on large beam test pieces.

  8. RSE-M code progress in the field of examination evaluation and flaw acceptance criteria

    International Nuclear Information System (INIS)

    Barthelet, B.; Le Delliou, P.; Heliot, J.; Faidy, C.; Drubay, B.

    1995-01-01

    The RSE-M Code provides rules and requirements for in service inspection of light water cooled nuclear power plants. The code first edition was established by EDF and published in 1990 by AFCEN. In 1992, a second RSE-M project was launched by EDF and FRAMATOME with the objective to address a 1995 edition more completed considering the needs of owners, users, manufacturers and inspectors. This paper focuses on evaluation of examination results and presents the work done in the field of flaw acceptance criteria over the last three years. (author). 5 refs., 3 figs

  9. Probabilistic Estimation of Critical Flaw Sizes in the Primary Structure Welds of the Ares I-X Launch Vehicle

    Science.gov (United States)

    Pai, Shantaram S.; Hoge, Peter A.; Patel, B. M.; Nagpal, Vinod K.

    2009-01-01

    The primary structure of the Ares I-X Upper Stage Simulator (USS) launch vehicle is constructed of welded mild steel plates. There is some concern over the possibility of structural failure due to welding flaws. It was considered critical to quantify the impact of uncertainties in residual stress, material porosity, applied loads, and material and crack growth properties on the reliability of the welds during its pre-flight and flight. A criterion--an existing maximum size crack at the weld toe must be smaller than the maximum allowable flaw size--was established to estimate the reliability of the welds. A spectrum of maximum allowable flaw sizes was developed for different possible combinations of all of the above listed variables by performing probabilistic crack growth analyses using the ANSYS finite element analysis code in conjunction with the NASGRO crack growth code. Two alternative methods were used to account for residual stresses: (1) The mean residual stress was assumed to be 41 ksi and a limit was set on the net section flow stress during crack propagation. The critical flaw size was determined by parametrically increasing the initial flaw size and detecting if this limit was exceeded during four complete flight cycles, and (2) The mean residual stress was assumed to be 49.6 ksi (the parent material s yield strength) and the net section flow stress limit was ignored. The critical flaw size was determined by parametrically increasing the initial flaw size and detecting if catastrophic crack growth occurred during four complete flight cycles. Both surface-crack models and through-crack models were utilized to characterize cracks in the weld toe.

  10. The influence of long-range residual stress on plastic collapse of pressurised pipes with and without flaws

    International Nuclear Information System (INIS)

    Wu, Gui-Yi; Smith, David J.; Pavier, Martyn J.

    2013-01-01

    Structural integrity assessments of pressurised pipes include plastic collapse as a potential failure mode. This paper uses analytical and numerical models to explore the effect of the end conditions of the pipe on the collapse pressure. The pipe is open-ended and two bounding conditions are addressed: one where axial loading is applied to the ends of the pipe and the other where a fixed axial displacement is applied. The fixed axial displacement condition represents long-range or fit-up residual stress. It is common practice to treat long-range residual stress in the same way as axial loading, leading to the conclusion that such long-range residual stress reduces the collapse pressure. Pipes in a number of states are considered: pipes with no flaws, pipes with fully circumferential flaws and pipes with part circumferential flaws. The flaws consist of either a crack or a slot on the external surface of the pipe. For the axial load condition, the collapse pressure for a flawed pipe is reduced when higher magnitudes of tensile or compressive axial loads are applied. For the fixed displacement condition however, the magnitude of the displacement may have little or no effect on the collapse pressure. The results of the work indicate that substantially conservative assessments may be made of the collapse pressures of pipes containing flaws, when long-range residual stress is taken to be a form of axial loading. -- Highlights: • The effect of end conditions on the collapse pressure of a pipe has been explored. • Fixed displacement conditions represent long-range residual stress. • Long-range residual stress is commonly thought to contribute to plastic collapse. • We show long-range residual stress has no influence on collapse for flawed pipes. • It is therefore possible to reduce conservatism in structural integrity assessment

  11. Comparative testing of women's tights, which are realized in the Ukrainian market

    OpenAIRE

    Мартосенко, Марина Григорьевна; Браилко, Анна Сергеевна

    2015-01-01

    Assortment of women's tights represented on the Ukrainian market is diverse: medical and corrective tights, classic thin and warm, simple and exclusive, ornamental and sports, for pregnant women and moisturizing effect. The size, density, pattern, material composition, visual appearance, matching fashion trends, colors, pricing policy – all these are criteria for the selection of women's tights.With such huge and diverse range of women's tights in the Ukrainian market, the problem of quality ...

  12. Tight-binding tunneling amplitude of an optical lattice

    International Nuclear Information System (INIS)

    Arzamasovs, Maksims; Liu, Bo

    2017-01-01

    The particle in a periodic potential is an important topic in an undergraduate quantum mechanics curriculum and a stepping stone on the way to more advanced topics, such as courses on interacting electrons in crystalline solids, and graduate-level research in solid-state and condensed matter physics. The interacting many-body phenomena are usually described in terms of the second quantized lattice Hamiltonians which treat single-particle physics on the level of tight-binding approximation and add interactions on top of it. The aim of this paper is to show how the tight-binding tunneling amplitude can be related to the strength of the periodic potential for the case of a cosine potential used in the burgeoning field of ultracold atoms. We show how to approach the problem of computing the tunneling amplitude of a deep lattice using the JWKB (Jeffreys–Wentzel–Kramers–Brillouin, also known as semiclassical) approximation. We also point out that care should be taken when applying the method of the linear combination of atomic orbitals (LCAO) in an optical lattice context. A summary of the exact solution in terms of Mathieu functions is also given. (paper)

  13. Tight-binding tunneling amplitude of an optical lattice

    Science.gov (United States)

    Arzamasovs, Maksims; Liu, Bo

    2017-11-01

    The particle in a periodic potential is an important topic in an undergraduate quantum mechanics curriculum and a stepping stone on the way to more advanced topics, such as courses on interacting electrons in crystalline solids, and graduate-level research in solid-state and condensed matter physics. The interacting many-body phenomena are usually described in terms of the second quantized lattice Hamiltonians which treat single-particle physics on the level of tight-binding approximation and add interactions on top of it. The aim of this paper is to show how the tight-binding tunneling amplitude can be related to the strength of the periodic potential for the case of a cosine potential used in the burgeoning field of ultracold atoms. We show how to approach the problem of computing the tunneling amplitude of a deep lattice using the JWKB (Jeffreys-Wentzel-Kramers-Brillouin, also known as semiclassical) approximation. We also point out that care should be taken when applying the method of the linear combination of atomic orbitals (LCAO) in an optical lattice context. A summary of the exact solution in terms of Mathieu functions is also given.

  14. Maintaining leak tightness capability of Caorso BWR containment

    International Nuclear Information System (INIS)

    Barsanti, P.; Di Palo, L.; Grimaldi, G.

    1988-01-01

    In 1987 the local leak rate test (LLRT) results of the primary containment were revised, with the following main goals: to highlight recurring problems, leading to lack of leak tightness of the primary containment; to individuate the pertinent degradation mechanisms; to assess the corrective actions already implemented and to plan further improvements, if necessary; and to optimize the preventive maintenance program on the containment, particularly the inspection frequency. All LLRTs in the past operating period, both before (as found) and after (as left) maintenance were analyzed, in terms of leakage rate and equivalent area of leak, for each penetration. Corrective actions already implemented included replacement of some valves with better quality type one, passivation of the carbon steel pipes and improvement of the pertinent surveillance procedures. Long term corrective actions, now under consideration, will include the following: more extensive passivation of pipes, carrying humid air, so that oxidation could be drastically reduced; better chemistry control in fluid systems; extensive replacement of the butterfly valves presently used; implementation of the LLRT practice, such to quantitatively measure the leakage rate, also in presence of large leak; and reduction of the time interval between periodical tests, on the basis of the results of the previous ones. Following these guidelines, future overall leakage tests would be performed in as found condition, aimed to verify the effectiveness of the entire maintenance and testing program of the primary containment and of its capability to maintain leak tightness during the time between two subsequent tests

  15. Adaptive wavelet tight frame construction for accelerating MRI reconstruction

    Directory of Open Access Journals (Sweden)

    Genjiao Zhou

    2017-09-01

    Full Text Available The sparsity regularization approach, which assumes that the image of interest is likely to have sparse representation in some transform domain, has been an active research area in image processing and medical image reconstruction. Although various sparsifying transforms have been used in medical image reconstruction such as wavelet, contourlet, and total variation (TV etc., the efficiency of these transforms typically rely on the special structure of the underlying image. A better way to address this issue is to develop an overcomplete dictionary from the input data in order to get a better sparsifying transform for the underlying image. However, the general overcomplete dictionaries do not satisfy the so-called perfect reconstruction property which ensures that the given signal can be perfectly represented by its canonical coefficients in a manner similar to orthonormal bases, resulting in time consuming in the iterative image reconstruction. This work is to develop an adaptive wavelet tight frame method for magnetic resonance image reconstruction. The proposed scheme incorporates the adaptive wavelet tight frame approach into the magnetic resonance image reconstruction by solving a l0-regularized minimization problem. Numerical results show that the proposed approach provides significant time savings as compared to the over-complete dictionary based methods with comparable performance in terms of both peak signal-to-noise ratio and subjective visual quality.

  16. MANAGING TIGHT BINDING RECEPTORS FOR NEW SPEARATIONS TECHNOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    DARYLE H BUSCH RICHARD S GIVENS

    2004-12-10

    Much of the earth's pollution involves compounds of the metallic elements, including actinides, strontium, cesium, technetium, and RCRA metals. Metal ions bind to molecules called ligands, which are the molecular tools that can manipulate the metal ions under most conditions. This DOE-EMSP sponsored program strives (1) to provide the foundations for using the most powerful ligands in transformational separations technologies and (2) to produce seminal examples of their applications to separations appropriate to the DOE EM mission. These ultra tight-binding ligands can capture metal ions in the most competitive of circumstances (from mineralized sites, lesser ligands, and even extremely dilute solutions), but they react so slowly that they are useless in traditional separations methodologies. Two attacks on this problem are underway. The first accommodates to the challenging molecular lethargy by developing a seminal slow separations methodology termed the soil poultice. The second designs ligands that are only tight-binding while wrapped around the targeted metal ion, but can be put in place by switch-binding and removed by switch-release. We envision a kind of molecular switching process to accelerate the union between metal ion and tight-binding ligand. Molecular switching processes are suggested for overcoming the slow natural equilibration rate with which ultra tight-binding ligands combine with metal ions. Ligands that bind relatively weakly combine with metal ions rapidly, so the trick is to convert a ligand from a weak, rapidly binding species to a powerful, slow releasing ligand--during the binding of the ligand to the metal ion. Such switch-binding ligands must react with themselves, and the reaction must take place under the influence of the metal ion. For example, our generation 1 ligands showed that a well-designed linear ligand with ends that readily combine, forms a cyclic molecule when it wraps around a metal ion. Our generation 2 ligands are

  17. Evaluation of constraint methodologies applied to a shallow-flaw cruciform bend specimen tested under biaxial loading conditions

    International Nuclear Information System (INIS)

    Bass, B.R.; McAfee, W.J.; Williams, P.T.; Pennell, W.E.

    1998-01-01

    A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed for application to the safety assessment of RPVs containing postulated shallow surface flaws. Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow surface flaws. The cruciform beam specimens were developed at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, far-field. out-of-plane biaxial stress component in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock or pressure-temperature loading of an RPV. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. The cruciform fracture toughness data were used to evaluate fracture methodologies for predicting the observed effects of biaxial loading on shallow-flaw fracture toughness. Initial emphasis was placed on assessment of stress-based methodologies. namely, the J-Q formulation, the Dodds-Anderson toughness scaling model, and the Weibull approach. Applications of these methodologies based on the hydrostatic stress fracture criterion indicated an effect of loading-biaxiality on fracture toughness, the conventional maximum principal stress criterion indicated no effect

  18. Flux-focusing eddy current probe and rotating probe method for flaw detection

    Science.gov (United States)

    Wincheski, Buzz A.; Fulton, James P.; Nath, Shridhar C.; Simpson, John W.; Namkung, Min

    1994-11-01

    A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks about circular fasteners and other circular inhomogeneities in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil. The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. By rotating the probe in a path around a circular fastener such as a rivet while maintaining a constant distance between the probe and the center of a rivet, the signal due to current flow about the rivet can be held constant. Any further changes in the current distribution, such as due to a fatigue crack at the rivet joint, can be detected as an increase in the output voltage above that due to the flow about the rivet head.

  19. Residual stress improvement for pipe weld by means of induction heating pre-flawed pipe

    International Nuclear Information System (INIS)

    Umemoto, T.; Yoshida, K.; Okamoto, A.

    1980-01-01

    The intergranular stress corrosion cracking (IGSCC) has been found in type 304 stainless steel piping of several BWR plants. It is already well known that IGSCC is most likely to occur when three essential factors, material sensitization, high tensile stress and corrosive environment, are present. If the welding residual stress is sufficiently high (200 to approximately 400 MPa) in the inside piping surface near the welded joint, then it may be one of the biggest contributors to IGSCC. If the residual stress is reduced or reversed by some way, the IGSCC will be effectively mitigated. In this paper a method to improve the residual stress named IHSI (Induction Heating Stress Improvement) is explained. IHSI aims to improve the condition of residual stress in the inside pipe surface using the thermal stress induced by the temperature difference in pipe wall, that is produced when the pipe is heated from the outside surface by an induction heating coil and cooled on the inside surface by water simultaneously. This method becomes more attractive when it can be successfully applied to in-service piping which might have some pre-flaw. In order to verify the validity of IHSI for such piping, some experiments and calculations using finite element method were conducted. These results are mainly discussed in this paper from the view-points of residual stress, flaw behaviour during IHSI and material deterioration. (author)

  20. Elastodynamic models for extending GTD to penumbra and finite size flaws

    International Nuclear Information System (INIS)

    Djakou, A Kamta; Darmon, M; Potel, C

    2016-01-01

    The scattering of elastic waves from an obstacle is of great interest in ultrasonic Non Destructive Evaluation (NDE). There exist two main scattering phenomena: specular reflection and diffraction. This paper is especially focused on possible improvements of the Geometrical Theory of Diffraction (GTD), one classical method used for modelling diffraction from scatterer edges. GTD notably presents two important drawbacks: it is theoretically valid for a canonical infinite edge and not for a finite one and presents discontinuities around the direction of specular reflection. In order to address the first drawback, a 3D hybrid method using both GTD and Huygens secondary sources has been developed to deal with finite flaws. ITD (Incremental Theory of Diffraction), a method developed in electromagnetism, has also been developed in elastodynamics to deal with small flaws. Experimental validation of these methods has been performed. As to the second drawback, a GTD uniform correction, the UTD (Uniform Theory of Diffraction) has been developed in the view of designing a generic model able to correctly simulate both specular reflection and diffraction. A comparison has been done between UTD numerical results and UAT (Uniform Asymptotic Theory of Diffraction) which is another uniform solution of GTD. (paper)

  1. Validation of favor code linear elastic fracture solutions for finite-length flaw geometries

    International Nuclear Information System (INIS)

    Dickson, T.L.; Keeney, J.A.; Bryson, J.W.

    1995-01-01

    One of the current tasks within the US Nuclear Regulatory Commission (NRC)-funded Heavy Section Steel Technology Program (HSST) at Oak Ridge National Laboratory (ORNL) is the continuing development of the FAVOR (Fracture, analysis of Vessels: Oak Ridge) computer code. FAVOR performs structural integrity analyses of embrittled nuclear reactor pressure vessels (RPVs) with stainless steel cladding, to evaluate compliance with the applicable regulatory criteria. Since the initial release of FAVOR, the HSST program has continued to enhance the capabilities of the FAVOR code. ABAQUS, a nuclear quality assurance certified (NQA-1) general multidimensional finite element code with fracture mechanics capabilities, was used to generate a database of stress-intensity-factor influence coefficients (SIFICs) for a range of axially and circumferentially oriented semielliptical inner-surface flaw geometries applicable to RPVs with an internal radius (Ri) to wall thickness (w) ratio of 10. This database of SIRCs has been incorporated into a development version of FAVOR, providing it with the capability to perform deterministic and probabilistic fracture analyses of RPVs subjected to transients, such as pressurized thermal shock (PTS), for various flaw geometries. This paper discusses the SIFIC database, comparisons with other investigators, and some of the benchmark verification problem specifications and solutions

  2. Time-dependent leak behavior of flawed Alloy 600 tube specimens at constant pressure

    Energy Technology Data Exchange (ETDEWEB)

    Bahn, Chi Bum, E-mail: bahn@anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States); Majumdar, Saurin [Argonne National Laboratory, Argonne, IL 60439 (United States); Harris, Charles [United States Nuclear Regulatory Commission, Rockville, MD 20852 (United States)

    2011-10-15

    Leak rate testing has been performed using Alloy 600 tube specimens with throughwall flaws. Some specimens have shown time-dependent leak behavior at constant pressure conditions. Fractographic characterization was performed to identify the time-dependent crack growth mechanism. The fracture surface of the specimens showed the typical features of ductile fracture, as well as the distinct crystallographic facets, typical of fatigue crack growth at low {Delta}K level. Structural vibration appears to have been caused by the oscillation of pressure, induced by a high-pressure pump used in a test facility, and by the water jet/tube structure interaction. Analyses of the leak behaviors and crack growth indicated that both the high-pressure pump and the water jet could significantly contribute to fatigue crack growth. To determine whether the fatigue crack growth during the leak testing can occur solely by the water jet effect, leak rate tests at constant pressure without the high-pressure pump need to be performed. - Highlights: > Leak rate of flawed Alloy 600 tubing increased at constant pressure condition. > Fractography revealed two cases: ductile tearing and crystallographic facets. > Crystallographic facets are typical features of fatigue crack growth at low {Delta}K. > Fatigue source could be water jet-induced vibration and/or high-pressure pump pulsation.

  3. Reliability assessment of hydraulic cylinders considering service loads and flaw distribution

    International Nuclear Information System (INIS)

    Altamura, Alessandra; Beretta, Stefano

    2012-01-01

    Manufacturing process, service conditions and material properties are all necessary requirements to a good design of tubular mechanical components subjected to fatigue. The most common approach to this design is usually deterministic, where a fixed NDT threshold, related to flaw acceptance limit, is set. However many uncertainties are left aside, i.e. the failure probability related to the fatigue strength under applied loads. This paper addresses the reliability evaluation of tubular mechanical components carrying some flaws and subjected to cyclic internal pressure variation. The aim is comparing the probability of failure obtained under several assumptions. A reliability assessment model, based on a random variable approach, has been implemented by using the Monte Carlo method. The analysis of the results, from a case study based on load spectra measurements of hydraulic cylinders of earth moving machines, has consented to evaluate the most important factors influencing the fatigue life prediction of these components. Highlights: ► Reliability evaluation of tubular components subjected to variable internal pressure. ► The dispersion of the threshold controls the stochasticity of crack growth. ► A random variable model has been developed using Monte Carlo. ► Initial crack size and spectrum shape are key factors in reliability evaluation.

  4. Research on Automatic Positioning System of Ultrasonic Testing of Wind Turbine Blade Flaws

    Science.gov (United States)

    Liu, Q. X.; Wang, Z. H.; Long, S. G.; Cai, M.; Cai, M.; Wang, X.; Chen, X. Y.; Bu, J. L.

    2017-11-01

    Ultrasonic testing technology has been used essentially in non-destructive testing of wind turbine blades. However, it is fact that the ultrasonic flaw detection method has inefficiently employed in recent years. This is because the testing result will illustrate a small deviation due to the artificial, environmental and technical factors. Therefore, it is an urgent technical demand for engineers to test the various flaws efficiently and quickly. An automatic positioning system has been designed in this paper to record the moving coordinates and the target distance in real time. Simultaneously, it could launch and acquire the sonic wave automatically. The ADNS-3080 optoelectronic chip is manufactured by Agilent Technologies Inc, which is also utilized in the system. With the combination of the chip, the power conversion module and the USB transmission module, the collected data can be transmitted from the upper monitor to the hardware that could process and control the data through software programming. An experiment has been designed to prove the reliability of automotive positioning system. The result has been validated by comparing the result collected form LABVIEW and actual plots on Perspex plane, it concludes that the system possesses high accuracy and magnificent meanings in practical engineering.

  5. Insensitivity to Flaws Leads to Damage Tolerance in Brittle Architected Meta-Materials

    Science.gov (United States)

    Montemayor, L. C.; Wong, W. H.; Zhang, Y.-W.; Greer, J. R.

    2016-02-01

    Cellular solids are instrumental in creating lightweight, strong, and damage-tolerant engineering materials. By extending feature size down to the nanoscale, we simultaneously exploit the architecture and material size effects to substantially enhance structural integrity of architected meta-materials. We discovered that hollow-tube alumina nanolattices with 3D kagome geometry that contained pre-fabricated flaws always failed at the same load as the pristine specimens when the ratio of notch length (a) to sample width (w) is no greater than 1/3, with no correlation between failure occurring at or away from the notch. Samples with (a/w) > 0.3, and notch length-to-unit cell size ratios of (a/l) > 5.2, failed at a lower peak loads because of the higher sample compliance when fewer unit cells span the intact region. Finite element simulations show that the failure is governed by purely tensile loading for (a/w) meta-materials may give rise to their damage tolerance and insensitivity of failure to the presence of flaws even when made entirely of intrinsically brittle materials.

  6. Flaws in design, analysis and interpretation of Pfizer's antifungal trials of voriconazole and uncritical subsequent quotations.

    Science.gov (United States)

    Jørgensen, Karsten J; Johansen, Helle Krogh; Gøtzsche, Peter C

    2006-01-19

    We have previously described how a series of trials sponsored by Pfizer of its antifungal drug, fluconazole, in cancer patients with neutropenia handicapped the control drug, amphotericin B, by flaws in design and analysis. We describe similar problems in two pivotal trials of Pfizer's new antifungal agent, voriconazole, published in a prestigious journal. In a non-inferiority trial, voriconazole was significantly inferior to liposomal amphothericin B, but the authors concluded that voriconazole was a suitable alternative. The second trial used amphothericin B deoxycholate as comparator, but handicapped the drug by not requiring pre-medication to reduce infusion-related toxicity or substitution with electrolytes and fluid to reduce nephrotoxicity, although the planned duration of treatment was 84 days. Voriconazole was given for 77 days on average, but the comparator for only 10 days, which precludes a meaningful comparison. In a random sample of 50 references to these trials, we found that the unwarranted conclusions were mostly uncritically propagated. It was particularly surprising that relevant criticism raised by the FDA related to the first trial was only quoted once, and that none of the articles noted the obvious flaws in the design of the second trial. We suggest that editors ensure that the abstract reflects fairly on the remainder of the paper, and that journals do not impose any time limit for accepting letters that point out serious weaknesses in a study that have not been noted before.

  7. The Secret of Future Defeat: The Evolution of US Joint and Army Doctrine 1993-2006 and the Flawed Conception of Stability Operations

    Science.gov (United States)

    2007-05-24

    The Secret of Future Defeat: the Evolution of US Joint and Army Doctrine 1993-2006 and the Flawed Conception of Stability Operations A...4. TITLE AND SUBTITLE The Secret of Future Defeat: the Evolution of US Joint and 5a. CONTRACT NUMBER Army Doctrine 1993-2006 and the Flawed... The Secret of Future Defeat: the Evolution of US Joint and Army Doctrine 1993-2006 and the Flawed Conception of Stability Operations Approved by

  8. Experimental study and theoretical interpretation of saturation effect on ultrasonic velocity in tight sandstones under different pressure conditions

    Science.gov (United States)

    Li, Dongqing; Wei, Jianxin; Di, Bangrang; Ding, Pinbo; Huang, Shiqi; Shuai, Da

    2018-03-01

    Understanding the influence of lithology, porosity, permeability, pore structure, fluid content and fluid distribution on the elastic wave properties of porous rocks is of great significance for seismic exploration. However, unlike conventional sandstones, the petrophysical characteristics of tight sandstones are more complex and less understood. To address this problem, we measured ultrasonic velocity in partially saturated tight sandstones under different effective pressures. A new model is proposed, combining the Mavko-Jizba-Gurevich relations and the White model. The proposed model can satisfactorily simulate and explain the saturation dependence and pressure dependence of velocity in tight sandstones. Under low effective pressure, the relationship of P-wave velocity to saturation is pre-dominantly attributed to local (pore scale) fluid flow and inhomogeneous pore-fluid distribution (large scale). At higher effective pressure, local fluid flow gradually decreases, and P-wave velocity gradually shifts from uniform saturation towards patchy saturation. We also find that shear modulus is more sensitive to saturation at low effective pressures. The new model includes wetting ratio, an adjustable parameter that is closely related to the relationship between shear modulus and saturation.

  9. Evaluation on real-time dynamic performance of BDS in PPP, RTK, and INS tightly aided modes

    Science.gov (United States)

    Gao, Zhouzheng; Li, Tuan; Zhang, Hongping; Ge, Maorong; Schuh, Harald

    2018-05-01

    Since China's BeiDou satellite navigation system (BDS) began to provide regional navigation service for Asia-Pacific region after 2012, more new generation BDS satellites have been launched to further expand BDS's coverage to be global. In this contribution, precise positioning models based on BDS and the corresponding mathematical algorithms are presented in detail. Then, an evaluation on BDS's real-time dynamic positioning and navigation performance is presented in Precise Point Positioning (PPP), Real-time Kinematic (RTK), Inertial Navigation System (INS) tightly aided PPP and RTK modes by processing a set of land-borne vehicle experiment data. Results indicate that BDS positioning Root Mean Square (RMS) in north, east, and vertical components are 2.0, 2.7, and 7.6 cm in RTK mode and 7.8, 14.7, and 24.8 cm in PPP mode, which are close to GPS positioning accuracy. Meanwhile, with the help of INS, about 38.8%, 67.5%, and 66.5% improvements can be obtained by using PPP/INS tight-integration mode. Such enhancements in RTK/INS tight-integration mode are 14.1%, 34.0%, and 41.9%. Moreover, the accuracy of velocimetry and attitude determination can be improved to be better than 1 cm/s and 0.1°, respectively. Besides, the continuity and reliability of BDS in both PPP and RTK modes can also be ameliorated significantly by INS during satellite signal missing periods.

  10. Revenue Risk of U.S. Tight-Oil Firms

    Directory of Open Access Journals (Sweden)

    Luis Mª Abadie

    2016-10-01

    Full Text Available American U.S. crude oil prices have dropped significantly of late down to a low of less than $30 a barrel in early 2016. At the same time price volatility has increased and crude in storage has reached record amounts in the U.S. America. Low oil prices in particular pose quite a challenge for the survival of U.S. America’s tight-oil industry. In this paper we assess the current profitability and future prospects of this industry. The question could be broadly stated as: should producers stop operation immediately or continue in the hope that prices will rise in the medium term? Our assessment is based on a stochastic volatility model with three risk factors, namely the oil spot price, the long-term oil price, and the spot price volatility; we allow for these sources of risk to be correlated and display mean reversion. We then use information from spot and futures West Texas Intermediate (WTI oil prices to estimate this model. Our aim is to show how the development of the oil price in the future may affect the prospective revenues of firms and hence their operation decisions at present. With the numerical estimates of the model’s parameters we can compute the value of an operating tight-oil field over a certain time horizon. Thus, the present value (PV of the prospective revenues up to ten years from now is $37.07/bbl in the base case. Consequently, provided that the cost of producing a barrel of oil is less than $37.07 production from an operating field would make economic sense. Obviously this is just a point estimate. We further perform a Monte Carlo (MC simulation to derive the risk profile of this activity and calculate two standard measures of risk, namely the value at risk (VaR and the expected shortfall (ES (for a given confidence level. In this sense, the PV of the prospective revenues will fall below $22.22/bbl in the worst 5% of the cases; and the average value across these worst scenarios is $19.77/bbl. Last we undertake two

  11. Ischemic preconditioning enhances integrity of coronary endothelial tight junctions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhao [Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007 (United States); Jin, Zhu-Qiu, E-mail: zhu-qiu.jin@sdstate.edu [Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007 (United States)

    2012-08-31

    Highlights: Black-Right-Pointing-Pointer Cardiac tight junctions are present between coronary endothelial cells. Black-Right-Pointing-Pointer Ischemic preconditioning preserves the structural and functional integrity of tight junctions. Black-Right-Pointing-Pointer Myocardial edema is prevented in hearts subjected to ischemic preconditioning. Black-Right-Pointing-Pointer Ischemic preconditioning enhances translocation of ZO-2 from cytosol to cytoskeleton. -- Abstract: Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiac TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood-heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs-Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC

  12. Fatigue crack initiation at complex flaws in hydrided Zr-2.5%Nb samples from CANDU pressure tubes

    International Nuclear Information System (INIS)

    Stoica, L.; Radu, V.

    2016-01-01

    The paper addresses the phenomena which occur at locations where the oxide layer of the inner surface of CANDU tube pressure is damaged by the contact with the fuel element or due to the action of hard particles at the interface between the tube pressure and bearing pad of fuel element. In such situations generate defects, which most often are defects known as ''bearing pad fretting flaws'' or ''debris fretting flaws''. In this paper the experiments are completed in a series of previous works on the mechanical fatigue phenomenon on samples prepared from the pressure tube Zr-2.5% Nb alloy. The phenomenon of variable mechanical stress (or fatigue) may lead to initiation of cracks at the tip of volumetric flaws, according to the accumulation of hydrides, which then fractures and can propagate through the tube wall pressure due to the mechanism of type DHC (Delayed Hydride Cracking). (authors)

  13. Crude oil prices: Are our oil markets too tight?

    International Nuclear Information System (INIS)

    Simmons, M.R.

    1997-01-01

    The answer to the question posed in the title is that tightness in the market will surely prevail through 1997. And as discussed herein, with worldwide demand expected to continue to grow, there will be a strong call on extra oil supply. Meeting those demands, however, will not be straightforward--as many observers wrongly believe--considering the industry's practice of maintaining crude stocks at ''Just in time'' inventory levels. Further, impact will be felt from the growing rig shortage, particularly for deepwater units, and down-stream capacity limits. While these factors indicate 1997 should be another good year for the service industry, it is difficult to get any kind of consensus view from the oil price market. With most observers' information dominated by the rarely optimistic futures price of crude, as reflected by the NYMEX, the important fact is that oil prices have remained stable for three years and increased steadily through 1996

  14. The tightly bound nuclei in the liquid drop model

    Science.gov (United States)

    Sree Harsha, N. R.

    2018-05-01

    In this paper, we shall maximise the binding energy per nucleon function in the semi-empirical mass formula of the liquid drop model of the atomic nuclei to analytically prove that the mean binding energy per nucleon curve has local extrema at A ≈ 58.6960, Z ≈ 26.3908 and at A ≈ 62.0178, Z ≈ 27.7506. The Lagrange method of multipliers is used to arrive at these results, while we have let the values of A and Z take continuous fractional values. The shell model that shows why 62Ni is the most tightly bound nucleus is outlined. A brief account on stellar nucleosynthesis is presented to show why 56Fe is more abundant than 62Ni and 58Fe. We believe that the analytical proof presented in this paper can be a useful tool to the instructors to introduce the nucleus with the highest mean binding energy per nucleon.

  15. Critical heat flux in tubes and tight hexagonal rod lattices

    International Nuclear Information System (INIS)

    Erbacher, F.J.; Cheng Xu; Zeggel, W.

    1994-01-01

    The critical heat flux (CHF) in small-diameter tubes and in tight hexagonal 7-rod and 37-rod bundles was investigated in the KRISTA test facility, using Freon 12 as the working fluid. The measurements in tubes showed that the influence of the tube diameter on CHF cannot be described as suggested by earlier publications with sufficient accuracy. CHF in bundles is lower than in tubes under comparable conditions. The influence of spacers (grid spacers, wire wraps) on CHF was found to be governed by local steam qualities. A comparison of the test results with some CHF prediction methods showed that the look-up table method reproduces the test results in circular tubes most accurately. Combined with CHF look-up tables, subchannel analysis and Ahmad's fluid-to-fluid scaling law, Freon experiments have proven to be a suitable tool for CHF prediction in water-cooled rod bundles. (orig.) [de

  16. Tight junction proteins contribute to barrier properties in human pleura.

    Science.gov (United States)

    Markov, Alexander G; Voronkova, Maria A; Volgin, George N; Yablonsky, Piotr K; Fromm, Michael; Amasheh, Salah

    2011-03-15

    The permeability of pleural mesothelium helps to control the volume and composition of the liquid lubricating pleural surfaces. Information on pleural barrier function in health and disease, however, is scarce. Tissue specimens of human pleura were mounted in Ussing chambers for measurement of transmesothelial resistance. Expression of tight junction (TJ) proteins was studied by Western blots and immune fluorescence confocal microscopy. Both visceral and parietal pleura showed barrier properties represented by transmesothelial resistance. Occludin, claudin-1, -3, -5, and -7, were detected in visceral pleura. In parietal pleura, the same TJ proteins were detected, except claudin-7. In tissues from patients with pleural inflammation these tightening claudins were decreased and in visceral pleura claudin-2, a paracellular channel former, became apparent. We report that barrier function in human pleura coincides with expression of claudins known to be key determinants of epithelial barrier properties. In inflamed tissue, claudin expression indicates a reduced barrier function. Copyright © 2010 Elsevier B.V. All rights reserved.

  17. Trends in drug delivery through tissue barriers containing tight junctions.

    Science.gov (United States)

    Tscheik, Christian; Blasig, Ingolf E; Winkler, Lars

    2013-04-01

    A limitation in the uptake of many drugs is the restricted permeation through tissue barriers. There are two general ways to cross barriers formed by cell layers: by transcytosis or by diffusion through the intercellular space. In the latter, tight junctions (TJs) play the decisive role in the regulation of the barrier permeability. Thus, transient modulation of TJs is a potent strategy to improve drug delivery. There have been extensive studies on surfactant-like absorption enhancers. One of the most effective enhancers found is sodium caprate. However, this modulates TJs in an unspecific fashion. A novel approach would be the specific modulation of TJ-associated marvel proteins and claudins, which are the main structural components of the TJs. Recent studies have identified synthetic peptidomimetics and RNA interference techniques to downregulate the expression of targeted TJ proteins. This review summarizes current progress and discusses the impact on TJs' barrier function.

  18. Laser material processing with tightly focused cylindrical vector beams

    Energy Technology Data Exchange (ETDEWEB)

    Drevinskas, Rokas, E-mail: rd1c12@soton.ac.uk; Zhang, Jingyu; Beresna, Martynas; Gecevičius, Mindaugas; Kazansky, Peter G. [Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ (United Kingdom); Kazanskii, Andrey G. [Physics Department, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Svirko, Yuri P. [Physics Department, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Institute of Photonics, University of Eastern Finland, P.O.BOX 111, FI-80101 Joensuu (Finland)

    2016-05-30

    We demonstrate a comprehensive modification study of silica glass, crystalline silicon, and amorphous silicon film, irradiated by tightly focused cylindrical vector beams with azimuthal and radial polarizations. The evidence of the longitudinal field associated with radial polarization is revealed by second harmonic generation in z-cut lithium niobate crystal. Despite the lower threshold of ring-shaped modification of silicon materials, the modification in the center of single pulse radially polarized beam is not observed. The phenomenon is interpreted in terms of the enhanced reflection of longitudinal component at the interface with high-index contrast, demonstrating that the longitudinal component is inefficient for the flat surface modification. Enhanced interaction of the longitudinal light field with silicon nanopillar structures produced by the first pulse of double-pulse irradiation is also demonstrated.

  19. Tightly Coupled Multiphysics Algorithm for Pebble Bed Reactors

    International Nuclear Information System (INIS)

    Park, HyeongKae; Knoll, Dana; Gaston, Derek; Martineau, Richard

    2010-01-01

    We have developed a tightly coupled multiphysics simulation tool for the pebble-bed reactor (PBR) concept, a type of Very High-Temperature gas-cooled Reactor (VHTR). The simulation tool, PRONGHORN, takes advantages of the Multiphysics Object-Oriented Simulation Environment library, and is capable of solving multidimensional thermal-fluid and neutronics problems implicitly with a Newton-based approach. Expensive Jacobian matrix formation is alleviated via the Jacobian-free Newton-Krylov method, and physics-based preconditioning is applied to minimize Krylov iterations. Motivation for the work is provided via analysis and numerical experiments on simpler multiphysics reactor models. We then provide detail of the physical models and numerical methods in PRONGHORN. Finally, PRONGHORN's algorithmic capability is demonstrated on a number of PBR test cases.

  20. Tightly coupled transient analysis of EBR-II

    International Nuclear Information System (INIS)

    Makowitz, H.; Lehto, W.K.; Sackett, J.I.

    1988-01-01

    A Tightly Coupled transient analysis system for the Experimental Breeder Reactor-II (EBR-II) is currently being tested. The system consists of a faster than real time high fidelity reactor simulation, advanced graphics displays, expert system coupling, and real time data coupling via the EBR-II data acquisition system to and from the plant and the control system. The base, first generation software has been developed and is presently being tested. Various subsystem couplings and the total system integration are being checked out. This system should enhance the diagnostic and prognostic capability of EBR-II in the near term and provide automatic control during startup and power maneuvering in the future, as well as serve as a testbed for new control system development for advanced reactors

  1. Efficient self-consistency for magnetic tight binding

    Science.gov (United States)

    Soin, Preetma; Horsfield, A. P.; Nguyen-Manh, D.

    2011-06-01

    Tight binding can be extended to magnetic systems by including an exchange interaction on an atomic site that favours net spin polarisation. We have used a published model, extended to include long-ranged Coulomb interactions, to study defects in iron. We have found that achieving self-consistency using conventional techniques was either unstable or very slow. By formulating the problem of achieving charge and spin self-consistency as a search for stationary points of a Harris-Foulkes functional, extended to include spin, we have derived a much more efficient scheme based on a Newton-Raphson procedure. We demonstrate the capabilities of our method by looking at vacancies and self-interstitials in iron. Self-consistency can indeed be achieved in a more efficient and stable manner, but care needs to be taken to manage this. The algorithm is implemented in the code PLATO. Program summaryProgram title:PLATO Catalogue identifier: AEFC_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFC_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 228 747 No. of bytes in distributed program, including test data, etc.: 1 880 369 Distribution format: tar.gz Programming language: C and PERL Computer: Apple Macintosh, PC, Unix machines Operating system: Unix, Linux, Mac OS X, Windows XP Has the code been vectorised or parallelised?: Yes. Up to 256 processors tested RAM: Up to 2 Gbytes per processor Classification: 7.3 External routines: LAPACK, BLAS and optionally ScaLAPACK, BLACS, PBLAS, FFTW Catalogue identifier of previous version: AEFC_v1_0 Journal reference of previous version: Comput. Phys. Comm. 180 (2009) 2616 Does the new version supersede the previous version?: Yes Nature of problem: Achieving charge and spin self-consistency in magnetic tight binding can be very

  2. Zonulin, regulation of tight junctions, and autoimmune diseases.

    Science.gov (United States)

    Fasano, Alessio

    2012-07-01

    Recent studies indicate that besides digestion and absorption of nutrients and water and electrolytes homeostasis, another key function of the intestine is to regulate the trafficking of environmental antigens across the host mucosal barrier. Intestinal tight junctions (TJs) create gradients for the optimal absorption and transport of nutrients and control the balance between tolerance and immunity to nonself antigens. To meet diverse physiological challenges, intestinal epithelial TJs must be modified rapidly and in a coordinated fashion by regulatory systems that orchestrate the state of assembly of the TJ multiprotein network. While considerable knowledge exists about TJ ultrastructure, relatively little is known about their physiological and pathophysiological regulation. Our discovery of zonulin, the only known physiologic modulator of intercellular TJs described so far, has increased our understanding of the intricate mechanisms that regulate the intestinal epithelial paracellular pathway and has led us to appreciate that its upregulation in genetically susceptible individuals leads to autoimmune diseases. © 2012 New York Academy of Sciences.

  3. ADVANCED FRACTURING TECHNOLOGY FOR TIGHT GAS: AN EAST TEXAS FIELD DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Mukul M. Sharma

    2005-03-01

    The primary objective of this research was to improve completion and fracturing practices in gas reservoirs in marginal plays in the continental United States. The Bossier Play in East Texas, a very active tight gas play, was chosen as the site to develop and test the new strategies for completion and fracturing. Figure 1 provides a general location map for the Dowdy Ranch Field, where the wells involved in this study are located. The Bossier and other tight gas formations in the continental Unites States are marginal plays in that they become uneconomical at gas prices below $2.00 MCF. It was, therefore, imperative that completion and fracturing practices be optimized so that these gas wells remain economically attractive. The economic viability of this play is strongly dependent on the cost and effectiveness of the hydraulic fracturing used in its well completions. Water-fracs consisting of proppant pumped with un-gelled fluid is the type of stimulation used in many low permeability reservoirs in East Texas and throughout the United States. The use of low viscosity Newtonian fluids allows the creation of long narrow fractures in the reservoir, without the excessive height growth that is often seen with cross-linked fluids. These low viscosity fluids have poor proppant transport properties. Pressure transient tests run on several wells that have been water-fractured indicate a long effective fracture length with very low fracture conductivity even when large amounts of proppant are placed in the formation. A modification to the water-frac stimulation design was needed to transport proppant farther out into the fracture. This requires suspending the proppant until the fracture closes without generating excessive fracture height. A review of fracture diagnostic data collected from various wells in different areas (for conventional gel and water-fracs) suggests that effective propped lengths for the fracture treatments are sometimes significantly shorter than those

  4. Economic evaluation on tight sandstone gas development projects in China and recommendation on fiscal and taxation support policies

    OpenAIRE

    Zhen Yang; Lingfeng Kong; Min Du; Chenhui Zhao

    2016-01-01

    China is rich in tight sandstone gas resources (“tight gas” for short). For example, the Sulige Gasfield in the Ordos Basin and the Upper Triassic Xujiahe Fm gas reservoir in the Sichuan Basin are typical tight gas reservoirs. In the past decade, tight gas reserve and production both have increased rapidly in China, but tight gas reservoirs are always managed as conventional gas reservoirs without effective fiscal, taxation and policy supports. The potential of sustainable tight gas productio...

  5. Coalbed methane and tight gas no longer unconventional resources

    International Nuclear Information System (INIS)

    Gatens, M.

    2006-01-01

    Unconventional gas refers to natural gas contained in difficult-to-produce formations that require special drilling and completion techniques to achieve commercial production. It includes tight gas, coal seams, organic shales, and gas hydrates. Canada's vast unconventional gas resource is becoming an increasingly important part of the country's gas supply. The emergence of unconventional gas production in Canada over the past several years has made the unconventional increasingly conventional in terms of industry activity. It was suggested that in order to realize the potential for unconventional gas in Canada, all stakeholders should engage to ensure the development is environmentally responsible. Unconventional gas accounts for nearly one third of U.S. gas production. It also accounts for nearly 5 Bcf per day and growing. The impetus to this sudden growth has been the gradual and increasing contribution of tight sands and limes to Canadian production, which accounts for more than 4 Bcf per day. Coalbed methane (CBM) is at 0.5 Bcf per day and growing. In response to expectations that CBM will reach 2 to 3 Bcf per day over the next 2 decades, Canadian producers are placing more emphasis on unconventional resource plays, including organic shales and gas hydrates. As such, significant growth of unconventional gas is anticipated. This growth will be facilitated by the adoption of U.S..-developed technologies and new Canadian technologies. It was suggested that research and development will be key to unlocking the unconventional gas potential. It was also suggested that the already existing, strong regulatory structure should continue in order to accommodate this growth in a sustainable manner. figs

  6. Clinical benefits of tight glycaemic control: focus on the intensive care unit.

    Science.gov (United States)

    Mesotten, Dieter; Van den Berghe, Greet

    2009-12-01

    While stress hyperglycaemia has traditionally been regarded as an adaptive, beneficial response, it is clear that hyperglycaemia and hypoglycaemia are associated with increased risk of death in critically ill intensive care unit (ICU) patients. Recent studies on blood-glucose control failed to fully clarify whether this association is causal. Early proof-of-concept single-centre randomised controlled studies found that maintaining normoglycaemia by intensive insulin therapy, as compared with tolerating hyperglycaemia as an adaptive response, improved patient outcome. However, recent large multicentre studies VISEP, GLUCONTROL and NICE-SUGAR) could not confirm this survival benefit. Methodological disparity in the execution of the complex intervention of tight glycaemic control may have contributed significantly to the contradicting results. First, different target ranges for blood glucose were used in the control group of the GLUCONTROL and 'Normoglycemia in intensive care evaluation and survival using glucose algorithm' regulation' (NICE-SUGAR) studies. Second, problems to steer blood-glucose levels within target range in the intervention group resulted in a significant overlap of the treatment groups. Third, allowing inaccurate blood-glucose measurement devices, in combination with different blood sampling sites and types of infusion pumps, may have led to unnoticed swings in blood-glucose levels. Fourth, the level of expertise of the intensive care nurses with the therapy may have been variable due to low number of study patients per centre. Finally, the studies on tight blood-glucose control were done with vastly different nutritional and end-of-life strategies. The currently available studies do not allow to confidently recommend one optimal target for glucose in heterogeneous ICU patient groups and settings. Provided that adequate devices for blood-glucose measurement and insulin administration are available, together with an extensive experience of the

  7. Development of a Weibull model of cleavage fracture toughness for shallow flaws in reactor pressure vessel material

    Energy Technology Data Exchange (ETDEWEB)

    Bass, B.R.; Williams, P.T.; McAfee, W.J.; Pugh, C.E. [Oak Ridge National Lab., Heavy-Section Steel Technology Program, Oak Ridge, TN (United States)

    2001-07-01

    A primary objective of the United States Nuclear Regulatory Commission (USNRC) -sponsored Heavy-Section Steel Technology (HSST) Program is to develop and validate technology applicable to quantitative assessments of fracture prevention margins in nuclear reactor pressure vessels (RPVs) containing flaws and subjected to service-induced material toughness degradation. This paper describes an experimental/analytical program for the development of a Weibull statistical model of cleavage fracture toughness for applications to shallow surface-breaking and embedded flaws in RPV materials subjected to multi-axial loading conditions. The experimental part includes both material characterization testing and larger fracture toughness experiments conducted using a special-purpose cruciform beam specimen developed by Oak Ridge National Laboratory for applying biaxial loads to shallow cracks. Test materials (pressure vessel steels) included plate product forms (conforming to ASTM A533 Grade B Class 1 specifications) and shell segments procured from a pressurized-water reactor vessel intended for a nuclear power plant. Results from tests performed on cruciform specimens demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower-transition temperature region. A local approach methodology based on a three-parameter Weibull model was developed to correlate these experimentally-observed biaxial effects on fracture toughness. The Weibull model, combined with a new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the Weibull stress integral definition, is shown to provide a scaling mechanism between uniaxial and biaxial loading states for 2-dimensional flaws located in the A533-B plate material. The Weibull stress density was introduced as a matrice for identifying regions along a semi-elliptical flaw front that have a higher probability of cleavage initiation. Cumulative

  8. Development of a Weibull model of cleavage fracture toughness for shallow flaws in reactor pressure vessel material

    International Nuclear Information System (INIS)

    Bass, B.R.; Williams, P.T.; McAfee, W.J.; Pugh, C.E.

    2001-01-01

    A primary objective of the United States Nuclear Regulatory Commission (USNRC) -sponsored Heavy-Section Steel Technology (HSST) Program is to develop and validate technology applicable to quantitative assessments of fracture prevention margins in nuclear reactor pressure vessels (RPVs) containing flaws and subjected to service-induced material toughness degradation. This paper describes an experimental/analytical program for the development of a Weibull statistical model of cleavage fracture toughness for applications to shallow surface-breaking and embedded flaws in RPV materials subjected to multi-axial loading conditions. The experimental part includes both material characterization testing and larger fracture toughness experiments conducted using a special-purpose cruciform beam specimen developed by Oak Ridge National Laboratory for applying biaxial loads to shallow cracks. Test materials (pressure vessel steels) included plate product forms (conforming to ASTM A533 Grade B Class 1 specifications) and shell segments procured from a pressurized-water reactor vessel intended for a nuclear power plant. Results from tests performed on cruciform specimens demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower-transition temperature region. A local approach methodology based on a three-parameter Weibull model was developed to correlate these experimentally-observed biaxial effects on fracture toughness. The Weibull model, combined with a new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the Weibull stress integral definition, is shown to provide a scaling mechanism between uniaxial and biaxial loading states for 2-dimensional flaws located in the A533-B plate material. The Weibull stress density was introduced as a matrice for identifying regions along a semi-elliptical flaw front that have a higher probability of cleavage initiation. Cumulative

  9. Effects of Tight Versus Non Tight Control of Metabolic Acidosis on Early Renal Function After Kidney Transplantation

    Directory of Open Access Journals (Sweden)

    Farhad Etezadi

    2012-09-01

    Full Text Available Background Recently, several studies have been conducted to determine the optimal strategy for intraoperative fluid replacement therapy in renal transplantation surgery. Since infusion of sodium bicarbonate as a buffer seems to be safer than other buffer compounds (lactate, gluconate, acetatethat indirectly convert into it within the liver, We hypothesized tight control of metabolic acidosis by infusion of sodium bicarbonate may improve early post-operative renal function in renal transplant recipients. Methods:120 patients were randomly divided into two equal groups. In group A, bicarbonate was infused intra-operatively according to Base Excess (BE measurements to achieve the normal values of BE (5 to +5 mEq/L. In group B, infusion of bicarbonate was allowed only in case of severe metabolic acidosis (BE [less than or equal to] 15 mEq/L or bicarbonate [less than or equal to] 10 mEq/L or PH [less than or equal to] 7.15. Minute ventilation was adjusted to keep PaCO2 within the normal range. Primary end-point was sampling of serum creatinine level in first, second, third and seventh post-operative days for statistical comparison between groups. Secondary objectives were comparison of cumulative urine volumes in the first 24 h of post-operative period and serum BUN levels which were obtained in first, second, third and seventh post-operative days. Results:In group A, all of consecutive serum creatinine levels were significantly lower in comparison with group B. With regard to secondary outcomes, no significant difference between groups was observed. Conclusion:Intra-operative tight control of metabolic acidosis by infusion of Sodium Bicarbonate in renal transplant recipients may improve early post-operative renal function.

  10. Effects of tight versus non tight control of metabolic acidosis on early renal function after kidney transplantation

    Directory of Open Access Journals (Sweden)

    Etezadi Farhad

    2012-09-01

    Full Text Available Abstract Background Recently, several studies have been conducted to determine the optimal strategy for intra-operative fluid replacement therapy in renal transplantation surgery. Since infusion of sodium bicarbonate as a buffer seems to be safer than other buffer compounds (lactate, gluconate, acetatethat indirectly convert into it within the liver, We hypothesized tight control of metabolic acidosis by infusion of sodium bicarbonate may improve early post-operative renal function in renal transplant recipients. Methods 120 patients were randomly divided into two equal groups. In group A, bicarbonate was infused intra-operatively according to Base Excess (BE measurements to achieve the normal values of BE (−5 to +5 mEq/L. In group B, infusion of bicarbonate was allowed only in case of severe metabolic acidosis (BE ≤ −15 mEq/L or bicarbonate ≤ 10 mEq/L or PH ≤ 7.15. Minute ventilation was adjusted to keep PaCO2 within the normal range. Primary end-point was sampling of serum creatinine level in first, second, third and seventh post-operative days for statistical comparison between groups. Secondary objectives were comparison of cumulative urine volumes in the first 24 h of post-operative period and serum BUN levels which were obtained in first, second, third and seventh post-operative days. Results In group A, all of consecutive serum creatinine levels were significantly lower in comparison with group B. With regard to secondary outcomes, no significant difference between groups was observed. Conclusion Intra-operative tight control of metabolic acidosis by infusion of Sodium Bicarbonate in renal transplant recipients may improve early post-operative renal function.

  11. Is signal detection theory fundamentally flawed? A response to Balakrishnan (1998a, 1998b, 1999).

    Science.gov (United States)

    Treisman, Michel

    2002-12-01

    For nearly 50 years, signal detection theory (SDT; Green & Swvets, 1966; Macmillan & Creelman, 1991) has been of central importance in the development of psychophysics and other areas of psychology. The theory has recently been challenged by Balakrishnan (1998b), who argues that, within SDT, an alternative index is "better justified" than d' and who claims to show (1998a, 1999) that SDT is fundamentally flawed and should be rejected. His evidence is based on new nonparametric measures that he has introduced and applied to experimental data. He believes his results show that basic assumptions of SDT are not supported-in particular, that payoff and probability manipulations do not affect the position of the decision criterion. In view of the importance of SDT in psychology, these claims deserve careful examination. They are critically reviewed here. It appears that it is Balakrishnans arguments that fail, and not SDT

  12. Nickel-base alloy overlay weld with improved ultrasonic flaw detection by magnetic stirring welding

    International Nuclear Information System (INIS)

    Takashi, Hirano; Kenji, Hirano; Masayuki, Watando; Takahiro, Arakawa; Minoru, Maeda

    2001-01-01

    Ultrasonic flaw detection is more difficult in Nickel-base alloy welds containing dendrites owing to the decrease ultrasonic transmissibility they cause. The present paper discusses application of magnetic stirring welding as a means for reducing dendrite growth with consequent improvement in ultrasonic transmissibility. Single pass and multi-pass welding tests were conducted to determine optimal welding conditions. By PT and macro observation subsequent to welding was carried out, optimal operation conditions were clarified. Overlay welding tests and UT clearly indicated ultrasonic beam transmissibility in overlay welds to be improved and detection capacity to be greater through application of magnetic stirring welding. Optimal operation conditions were determined based on examination of temper bead effects in the heat affected zone of low alloy steel by application of magnetic stirring welding to the butt welded joints between low alloy and stainless steel. Hardness in this zone of low alloy steel after the fourth layer was less than 350 HV. (author)

  13. Engineering approach for examining crack growth and stability in flawed structures

    International Nuclear Information System (INIS)

    Shih, C.F.

    1980-01-01

    Progress made in two research programs sponsored by the Electric Power Research Institute (EPRI), to identify viable parameters for characterizing crack initiation and continued extension, and to develop an engineering/design methodology, based on these parameters, for the assessment of crack growth and instability in engineering structures which are stressed beyond the regime of applicability of linear elastic fracture mechanics is reported. The goal in the development of such methodology is to establish an improved basis for analyzing the effect of flaws (postulated or detected) on the safety margins of pressure boundary components of light water-cooled type nuclear steam supply systems. The methodology can also be employed for structural integrity analyses of other engineering structures

  14. The Seductive-Plausibility of Patent Hold-Up Myths — A Flawed Historiography of Patents

    DEFF Research Database (Denmark)

    Howells, John; Katznelson, Ron D

    In previous work we have shown that a flawed historiography of patents continues to be the basis for patent policy advocacy. We set out objective standards of evidence that allegations of development block due to assertion of patents must meet. We show the extent of the errors in the historical...... record in the aircraft, automobile, radio and incandescent lamp technologies. We then evaluate how they measure against the objective standards. We find many simple errors and that an absence of indicia of development block characterise scholarship alleging that assertion of patents blocked development...... of multiple case studies subjected to such standards justifies the rebuttable presumption that “pioneer patents have never blocked development”....

  15. The flaw-detected coating and its applications in R&M of aircrafts

    Science.gov (United States)

    Hu, Feng; Liu, Mabao; Lü, Zhigang

    2009-07-01

    A monitoring method called ICM (Intelligent Coating Monitoring), which is based mainly on the intelligent coating sensors, has the capability to monitor crack initiation and growth in fatigue test coupons has been suggested in this study. The intelligent coating sensor is normally consisted of three layers: driving layer, sensing layer and protective layer where necessary. Fatigue tests with ICM for various materials demonstrate the capability to detect cracks with lfuel tank of an aircraft), or (ii) to take advantage of early detection and apply less invasive life-extension repairs, as well as reduce interruption of service when flaws are detected. Implementation of ICM is expected to improve fleet management practices and modify damage tolerance assumptions.

  16. Flaw location and characterization in anisotropic materials by ultrasonic spectral analysis

    International Nuclear Information System (INIS)

    Adler, L.; Cook, K.V.; Simpson, W.A.; Lewis, D.K.

    1978-01-01

    A method of quantitatively determining size and location of flaws in anisotropic materials such as stainless steel welds is described. In previous work, it was shown that spectral analysis of a broad band ultrasonic pulse scattered from a defect can be used to determine size and orientation in isotropic materials if the velocity of sound in the material is known. In an anisotropic structural material (stainless steel weld, centrifugal cast pipe), the velocity (both shear and longitudinal) is direction-dependent. When anisotropy is not taken into account, defect location and defect size estimation is misjudged. It will be shown that the effect of this structural variation in materials must be considered to obtain the correct size and location of defects by frequency analysis. A theoretical calculation, including anisotropy, of the scattered field from defects will also be presented

  17. Experimental investigation of flawed pipes with respect to fracture behavior and development of crack opening area

    Energy Technology Data Exchange (ETDEWEB)

    Stoppler, W [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt

    1993-12-31

    The critical length of a longitudinal through-wall flaw, defined as that causing rupture, was first determined hydro-statically on large experimental vessels under internal pressure; the leak before rupture diagram for the base material of the vessel is established by experiment and calculation; it gives a limit between the two modes of failure, leakage or rupture (catastrophic failure), depending on slit length and loading conditions. Tests under pneumatic pressure were then carried out to investigate crack arrest, with notched discs made of a brittle material welded in the cylindrical part of the vessel, and cracks triggered by means of a small charged ignited over the notch. In the case of discs of a diameter smaller than the critical slit length, crack arrest occurred when the crack entered the tough material, while a disc corresponding to the critical crack length of the vessel led to rupture. 5 refs., 16 figs., 2 tabs.

  18. Security Flaws in an Efficient Pseudo-Random Number Generator for Low-Power Environments

    Science.gov (United States)

    Peris-Lopez, Pedro; Hernandez-Castro, Julio C.; Tapiador, Juan M. E.; Millán, Enrique San; van der Lubbe, Jan C. A.

    In 2004, Settharam and Rhee tackled the design of a lightweight Pseudo-Random Number Generator (PRNG) suitable for low-power environments (e.g. sensor networks, low-cost RFID tags). First, they explicitly fixed a set of requirements for this primitive. Then, they proposed a PRNG conforming to these requirements and using a free-running timer [9]. We analyze this primitive discovering important security faults. The proposed algorithm fails to pass even relatively non-stringent batteries of randomness such as ENT (i.e. a pseudorandom number sequence test program). We prove that their recommended PRNG has a very short period due to the flawed design of its core. The internal state can be easily revealed, compromising its backward and forward security. Additionally, the rekeying algorithm is defectively designed mainly related to the unpractical value proposed for this purpose.

  19. Gun Shows and Gun Violence: Fatally Flawed Study Yields Misleading Results

    Science.gov (United States)

    Hemenway, David; Webster, Daniel; Pierce, Glenn; Braga, Anthony A.

    2010-01-01

    A widely publicized but unpublished study of the relationship between gun shows and gun violence is being cited in debates about the regulation of gun shows and gun commerce. We believe the study is fatally flawed. A working paper entitled “The Effect of Gun Shows on Gun-Related Deaths: Evidence from California and Texas” outlined this study, which found no association between gun shows and gun-related deaths. We believe the study reflects a limited understanding of gun shows and gun markets and is not statistically powered to detect even an implausibly large effect of gun shows on gun violence. In addition, the research contains serious ascertainment and classification errors, produces results that are sensitive to minor specification changes in key variables and in some cases have no face validity, and is contradicted by 1 of its own authors’ prior research. The study should not be used as evidence in formulating gun policy. PMID:20724672

  20. Distributed system for parallel data processing of ECT signals for electromagnetic flaw detection in materials

    International Nuclear Information System (INIS)

    Guliashki, Vassil; Marinova, Galia

    2002-01-01

    The paper proposes a distributed system for parallel data processing of ECT signals for flaw detection in materials. The measured data are stored in files on a host computer, where a JAVA server is located. The host computer is connected through Internet to a set of client computers, distributed geographically. The data are distributed from the host computer by means of the JAVA server to the client computers according their requests. The software necessary for the data processing is installed on each client computer in advance. The organization of the data processing on many computers, working simultaneously in parallel, leads to great time reducing, especially in cases when huge amount of data should be processed in very short time. (Author)

  1. Temperature dependence of luminescence for different surface flaws in high purity silica glass

    International Nuclear Information System (INIS)

    Fournier, J.; Grua, P.; Neauport, J.; Fargin, E.; Jubera, V.; Talaga, D.; Del Guerzo, A.; Raffy, G.; Jouannigot, S.

    2013-01-01

    In situ temperature dependence of the Photoluminescence under 325 nm irradiation is used to investigate defect populations existing in different surface flaws in high purity fused silica. Five photoluminescence bands peaking at 1.9, 2.1, 2.3, 2.63 and 3.11 eV have been detected in the spectral area ranging from 1.6 up to 3.6 eV. The Gaussian deconvolution of spectra allows dividing the five luminescence bands in two categories. The former corresponds to bands showing a significant intensity enhancement while temperature decreases; the latter corresponds to bands remaining insensitive to the temperature evolution. Such a behavior brings new information on defects involved in laser damage mechanism at 351 nm in nanosecond regime. (authors)

  2. Ultrasonic Phased Array Techniques for Detection of Flaws of Stud Bolts in Nuclear Power Plants

    International Nuclear Information System (INIS)

    Lee, Joon Hyun; Choi, Sang Woo

    2006-01-01

    The reactor vessel body and closure head are fastened with the stud bolt that is one of crucial parts for safety of the reactor vessels in nuclear power plants. It is reported that the stud bolt is often experienced by fatigue cracks initiated at threads. Stud bolts are inspected by the ultrasonic technique during the overhaul periodically for the prevention of failure which leads to radioactive leakage from the nuclear reactor. The conventional ultrasonic inspection for stud bolts was mainly conducted by reflected echo method based on shadow effect. However, in this technique, there were numerous spurious signals reflected from every oblique surfaces of the thread. In this study, ultrasonic phased array technique was applied to investigate detectability of flaws in stud bolts and characteristics of ultrasonic images corresponding to different scanning methods, that is, sector and linear scan. For this purpose, simplified stud bolt specimens with artificial defects of various depths were prepared

  3. Fatigue flaw growth assessment and inclusion of stratification to the LBB assessment

    Energy Technology Data Exchange (ETDEWEB)

    Samohyl, P.

    1997-04-01

    The application of the LBB requires also fatigue flaw growth assessment. This analysis was performed for PWR nuclear power plants types VVER 440/230, VVER 440/213c, VVER 1000/320. Respecting that these NPP`s were designed according to Russian codes that differ from US codes it was needed to compare these approaches. Comparison with our experimental data was accomplished, too. Margins of applicability of the US methods and their modifications for the materials used for construction of Czech and Slovak NPP`s are shown. Computer code accomplishing the analysis according to described method is presented. Some measurement and calculations show that thermal stratifications in horizontal pipelines can lead to additive loads that are not negligible and can be dangerous. An attempt to include these loads induced by steady-state stratification was made.

  4. Diagram Size vs. Layout Flaws: Understanding Quality Factors of UML Diagrams

    DEFF Research Database (Denmark)

    Störrle, Harald

    2016-01-01

    , though, is our third goal of extending our analysis aspects of diagram quality. Method: We improve our definition of diagram size and add a (provisional) definition of diagram quality as the number of topographic layout flaws. We apply these metrics on 60 diagrams of the five most commonly used types...... of UML diagram. We carefully analyze the structure of our diagram samples to ensure representativeness. We correlate diagram size and layout quality with modeler performance data obtained in previous experiments. The data set is the largest of its kind (n-156). Results: We replicate earlier findings......, and extend them to two new diagram types. We provide an improved definition of diagram size, and provide a definition of topographic layout quality, which is one more step towards a comprehensive definition of diagram quality as such. Both metrics are shown to be objectively applicable. We quantify...

  5. Analysis of the failure performance of internally pressurized piping with surface flaws

    International Nuclear Information System (INIS)

    Iorio, A.F; Crespi, J.C.

    1987-01-01

    Due to frequent failures an Atucha I PHWR moderator circuit branch piping, made of stainless steel type AISI 347 (DIN 1.4550), studies have been made, involving the application of several fracture mechanics criteria, in order to determine the conditions of leak-before-break (L.BB) and the critical crack length of the piping. These studies lead to the conclusions that, for a straight pipe of outer diameter of 219 mm and 16 mm wall thickness, with a circumferential flaw and the principal stress being in the bending, the L.BB criteria are satisfied, being the critical crack length of the order of 400 mm. A better mechanical finishing and heat treatment was suggested in order to improve the resistance to crack initiation. (Author)

  6. Sampling flies or sampling flaws? Experimental design and inference strength in forensic entomology.

    Science.gov (United States)

    Michaud, J-P; Schoenly, Kenneth G; Moreau, G

    2012-01-01

    Forensic entomology is an inferential science because postmortem interval estimates are based on the extrapolation of results obtained in field or laboratory settings. Although enormous gains in scientific understanding and methodological practice have been made in forensic entomology over the last few decades, a majority of the field studies we reviewed do not meet the standards for inference, which are 1) adequate replication, 2) independence of experimental units, and 3) experimental conditions that capture a representative range of natural variability. Using a mock case-study approach, we identify design flaws in field and lab experiments and suggest methodological solutions for increasing inference strength that can inform future casework. Suggestions for improving data reporting in future field studies are also proposed.

  7. Developmental techniques for ultrasonic flaw detection and characterization in stainless steel

    International Nuclear Information System (INIS)

    Kupperman, D.S.

    1983-04-01

    Flaw detection and characterization by ultrasonic methods is particularly difficult for stainless steel. This paper focuses on two specific problem areas: (a) the inspection of centrifugally cast stainless steel (CCSS) and (b) the differentiation of intergranular stress-corrosion cracking (IGSCC) from geometrical reflectors such as the weld root. To help identify optimal conditions for the ultrasonic inspection of CCSS, the effect of frequency on propagation of longitudinal and shear waves was examined in both isotropic and anisotropic samples. Good results were obtained with isotropic CCSS and 0.5-MHz angle beam shear waves. The use of beam-scattering patterns (i.e. signal amplitude vs skew angle) as a tool for discriminating IGSCC from geometrical reflectors is also discussed

  8. Fatigue test results of straight pipe with flaws in inner surface

    International Nuclear Information System (INIS)

    Shibata, Katsuyuki; Oba, Toshihiro; Kawamura, Takaichi; Yokoyama, Norio; Miyazono, Shohachiro

    1981-01-01

    Fatigue and fracture tests of piping models with flaws in the inner surface were carried out to investigate the fatigue crack growth, coalescence of multiple cracks and fracture behavior. Two straight test pipes with and without weldment in the test section of SUS304L stainless steel were tested under almost the same test conditions. Three artificial defects were machined in the inner surface of the test section of the test pipes. The fatigue test were performed untill the cracks coalesced and grew through the thickness. Subsequently, a static load was imposed on test pipe which contained a large crack in the test section. The test results show that the fatigue crack growth is slower than that predicted by the method specified in the Section XI of ASME Boiler and Pressure Vessel Code, and that the test pipes can endure more than the static load of 3Sm without an unstable fracture. (author)

  9. An algorithm for analytical solution of basic problems featuring elastostatic bodies with cavities and surface flaws

    Science.gov (United States)

    Penkov, V. B.; Levina, L. V.; Novikova, O. S.; Shulmin, A. S.

    2018-03-01

    Herein we propose a methodology for structuring a full parametric analytical solution to problems featuring elastostatic media based on state-of-the-art computing facilities that support computerized algebra. The methodology includes: direct and reverse application of P-Theorem; methods of accounting for physical properties of media; accounting for variable geometrical parameters of bodies, parameters of boundary states, independent parameters of volume forces, and remote stress factors. An efficient tool to address the task is the sustainable method of boundary states originally designed for the purposes of computerized algebra and based on the isomorphism of Hilbertian spaces of internal states and boundary states of bodies. We performed full parametric solutions of basic problems featuring a ball with a nonconcentric spherical cavity, a ball with a near-surface flaw, and an unlimited medium with two spherical cavities.

  10. High-temperature flaw assessment procedure: A state-of-the-art survey

    International Nuclear Information System (INIS)

    Ruggles, M.B.; Takahashi, Y.

    1989-05-01

    High-temperature crack growth under cyclic, static, and combined loading is received with an emphasis on fracture mechanics aspects. Experimental studies of the effects of loading history, microstructure, temperature, and environment on crack growth behavior are described and interpreted. The experimental evidence is used to examine crack growth parameters and theoretical models for fatigue, creep, and creep-fatigue crack propagation at elevated temperatures. The limitations of both elastic and elastic-plastic fracture mechanics for high-temperature subcritical crack growth are assessed. Existing techniques for modeling critical crack growth/ligament instability failure are also presented. Related topics of defect modeling and engineering flaw assessment procedures, nondestructive evaluation methods, and probabilistic failure analysis are briefly discussed. 142 refs., 33 figs

  11. DEVELOPMENT OF TIGHT OIL RESOURCES IN USA: PROFITABILITY OF EXPLOITATION AND EFFECT OF MACROECONOMIC INDICATORS IN VOLATILE OIL PRICE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Kristina Strpić

    2017-01-01

    Full Text Available Large scale development of tight oil resources in US started after 2010. with following five-year period of favorable steady increase in crude oil price. During this relatively short expansion cycle, operating and capital expenses changed drastically for main tight oil plays due to technological improvements in both well drilling and completion, expansion of service sector as well as loose government monetary policy which allowed favorable financing. This paper analyzed trends in costs during expansion period, as well as correlation of oil price to number of operating rigs and production quotas. After 2008/2009. world financial crisis economy recovery in US was somewhat sluggish and it caused extreme volatile environment in both equity and commodity markets. In such volatile environment intra-day crude oil prices, as well as other commodities and equities, show significant reaction to monthly published macroeconomic indicator reports, which give better overviews of trends in economic recovery. Prior to announcement, these reports always have forecasted value determined by consensus among market analysts. Therefore, any positive or negative surprise in real value tends to influence price of oil. This paper investigated influence of such macroeconomic reports to closing intraday oil price, as well as effect of other important daily market indices. Analysis showed that only Producer Price Index (PPI, among other indicators, has statistical significance of affecting intraday closing oil price.

  12. Determination of Flaw Type and Location Using an Expert Module in Ultrasonic Nondestructive Testing for Weld Inspection

    Science.gov (United States)

    Shahriari, D.; Zolfaghari, A.; Masoumi, F.

    2011-01-01

    Nondestructive evaluation is explained as nondestructive testing, nondestructive inspection, and nondestructive examination. It is a desire to determine some characteristic of the object or to determine whether the object contains irregularities, discontinuities, or flaws. Ultrasound based inspection techniques are used extensively throughout industry for detection of flaws in engineering materials. The range and variety of imperfections encountered is large, and critical assessment of location, size, orientation and type is often difficult. In addition, increasing quality requirements of new standards and codes of practice relating to fitness for purpose are placing higher demands on operators. Applying of an expert knowledge-based analysis in ultrasonic examination is a powerful tool that can help assure safety, quality, and reliability; increase productivity; decrease liability; and save money. In this research, an expert module system is coupled with ultrasonic examination (A-Scan Procedure) to determine and evaluate type and location of flaws that embedded during welding parts. The processing module of this expert system is implemented based on EN standard to classify welding defects, acceptance condition and measuring of their location via echo static pattern and image processing. The designed module introduces new system that can automate evaluating of the results of A-scan method according to EN standard. It can simultaneously recognize the number and type of defects, and determine flaw position during each scan.

  13. Evaluation of ASME code flaw analysis procedure using the influence function method for application to PWR primary piping

    International Nuclear Information System (INIS)

    Hong, S.Y.; Yeater, M.L.

    1985-01-01

    This paper discusses stress intensity factor calculations and fatigue analysis for a PWR primary coolant piping system. The influence function method is applied to evaluate ASME Code Section XI Appendix A ''analysis of flaw indication'' for the application to a PWR primary piping. Results of the analysis are discussed in detail. (orig.)

  14. Investigation of the radiation leakage from X ray flaw detectors and the improvement measures for the unqualified products

    International Nuclear Information System (INIS)

    Li Yiachun; Wu Yi; Pang Hu; Bai Bin

    1997-01-01

    The authors introduce investigation methods and results for radiation leakage from X ray flaw detectors, which are used in Beijing area. Total 21 sets of flaw detectors made in 8 factories in Beijing, Shanghai etc. have been tested, of which 16 sets made in Beijing, Dandong and Japan are gas cooling flaw detectors, and rest 5 sets made in Shanghai and Germany are water or oil cooling detectors. The air Kerma rate of leakage radiation at 1 m from the X ray tube target were measured by Type FJ-347A X, γ dosimeter. It can be seen from the results that, compared with the trade standard ZBY315-83, 5 sets of water or oil cooling flaw detectors are all qualified. However, only two sets of gas cooling detectors are qualified, and the radiation leakage of another 14 sets are over the values specified in the standard. The reason is analyzed, and some advices about the measures of improving radiation protection structure design and production technology for the unqualified products have been proposed

  15. Statistical flaws in design and analysis of fertility treatment studies on cryopreservation raise doubts on the conclusions

    Science.gov (United States)

    van Gelder, P.H.A.J.M.; Nijs, M.

    2011-01-01

    Decisions about pharmacotherapy are being taken by medical doctors and authorities based on comparative studies on the use of medications. In studies on fertility treatments in particular, the methodological quality is of utmost importance in the application of evidence-based medicine and systematic reviews. Nevertheless, flaws and omissions appear quite regularly in these types of studies. Current study aims to present an overview of some of the typical statistical flaws, illustrated by a number of example studies which have been published in peer reviewed journals. Based on an investigation of eleven studies at random selected on fertility treatments with cryopreservation, it appeared that the methodological quality of these studies often did not fulfil the required statistical criteria. The following statistical flaws were identified: flaws in study design, patient selection, and units of analysis or in the definition of the primary endpoints. Other errors could be found in p-value and power calculations or in critical p-value definitions. Proper interpretation of the results and/or use of these study results in a meta analysis should therefore be conducted with care. PMID:24753877

  16. Statistical flaws in design and analysis of fertility treatment -studies on cryopreservation raise doubts on the conclusions.

    Science.gov (United States)

    van Gelder, P H A J M; Nijs, M

    2011-01-01

    Decisions about pharmacotherapy are being taken by medical doctors and authorities based on comparative studies on the use of medications. In studies on fertility treatments in particular, the methodological quality is of utmost -importance in the application of evidence-based medicine and systematic reviews. Nevertheless, flaws and omissions appear quite regularly in these types of studies. Current study aims to present an overview of some of the typical statistical flaws, illustrated by a number of example studies which have been published in peer reviewed journals. Based on an investigation of eleven studies at random selected on fertility treatments with cryopreservation, it appeared that the methodological quality of these studies often did not fulfil the -required statistical criteria. The following statistical flaws were identified: flaws in study design, patient selection, and units of analysis or in the definition of the primary endpoints. Other errors could be found in p-value and power calculations or in critical p-value definitions. Proper -interpretation of the results and/or use of these study results in a meta analysis should therefore be conducted with care.

  17. Design of Tunnel Magnetoresistive-Based Circular MFL Sensor Array for the Detection of Flaws in Steel Wire Rope

    Directory of Open Access Journals (Sweden)

    Liu Xiucheng

    2016-01-01

    Full Text Available Tunnel magnetoresistive (TMR devices have superior performances in weak magnetic field detection. In this study, TMR devices were first employed to form a circular magnetic flux leakage (MFL sensor for slight wire rope flaw detection. Two versions of this tailor-made circular TMR-based sensor array were presented for the inspection of wire ropes with the diameters of 14 mm and 40 mm, respectively. Helmholtz-like coils or a ferrite magnet-based magnetizer was selected to provide the proper magnetic field, in order to meet the technical requirements of the TMR devices. The coefficient of variance in the flaw detection performance of the sensor array elements was experimentally estimated at 4.05%. Both versions of the MFL sensor array were able to detect multiple single-broken wire flaws in the wire ropes. The accurate axial and circumferential positions of these broken wire flaws were estimated from the MFL scanning image results. In addition, the proposed TMR-based sensor array was applied to detect the MFL signal induced by slight surface wear defects. A mutual correlation analysis method was used to distinguish the signals caused by the lift-off fluctuation from the MFL scanning image results. The MFL sensor arrays presented in this study provide inspiration for the designing of tailor-made TMR-based circular sensor arrays for cylindrical ferromagnetic structural inspections.

  18. Fuel assembly leak tightness control on WWER-1000 reactor

    International Nuclear Information System (INIS)

    Ivanova, R.; Gerchev, N.; Mateev, A.

    2001-01-01

    The main index for integrity of the fuel rods cladding is the specific activity value of the primary coolant. This value determines the safe operation of the reactor. The limit for safe operation of WWER-1000 reactor is the value of the total activity of Iodine isotopes in the primary coolant 5.0x10 -3 Ci/l. The paper briefly describes the methodology for performing a fuel tightness test (sipping test) and shows the results from these tests performed during the period 1987 -1999 in units 5 and 6 at the Kozloduy NPP. An additional index related to the safe operation is defined to characterize the fuel cladding integrity Fuel Reliability Index (FRI). The FRI is defined as value of the average activity of 131 I in the primary coolant, corrected with a part of precipitated 235 U migration and fixed to the general permanent purification frequency. Two criteria (quantitative and statistic) are determined to qualify the fuel cladding integrity. The results from sipping tests show good reliability of the fuel irradiated in unit 5 and 6 at the Kozloduy NPP

  19. Nanoscale capacitance: A quantum tight-binding model

    Science.gov (United States)

    Zhai, Feng; Wu, Jian; Li, Yang; Lu, Jun-Qiang

    2017-01-01

    Landauer-Buttiker formalism with the assumption of semi-infinite electrodes as reservoirs has been the standard approach in modeling steady electron transport through nanoscale devices. However, modeling dynamic electron transport properties, especially nanoscale capacitance, is a challenging problem because of dynamic contributions from electrodes, which is neglectable in modeling macroscopic capacitance and mesoscopic conductance. We implement a self-consistent quantum tight-binding model to calculate capacitance of a nano-gap system consisting of an electrode capacitance C‧ and an effective capacitance Cd of the middle device. From the calculations on a nano-gap made of carbon nanotube with a buckyball therein, we show that when the electrode length increases, the electrode capacitance C‧ moves up while the effective capacitance Cd converges to a value which is much smaller than the electrode capacitance C‧. Our results reveal the importance of electrodes in modeling nanoscale ac circuits, and indicate that the concepts of semi-infinite electrodes and reservoirs well-accepted in the steady electron transport theory may be not applicable in modeling dynamic transport properties.

  20. Claudin-21 Has a Paracellular Channel Role at Tight Junctions

    KAUST Repository

    Tanaka, Hiroo; Yamamoto, Yasuko; Kashihara, Hiroka; Yamazaki, Yuji; Tani, Kazutoshi; Fujiyoshi, Yoshinori; Mineta, Katsuhiko; Takeuchi, Kosei; Tamura, Atsushi; Tsukita, Sachiko

    2016-01-01

    Claudin protein family members, of which there are at least 27 in humans and mice, polymerize to form tight junctions (TJs) between epithelial cells, in a tissue- and developmental stage-specific manner. Claudins have a paracellular barrier function. In addition, certain claudins function as paracellular channels for small ions and/or solutes by forming selective pores at the TJs, although the specific claudins involved and their functional mechanisms are still in question. Here we show for the first time that claudin-21, which is more highly expressed in the embryonic than the postnatal stages, acts as a paracellular channel for small cations, such as Na+, similar to the typical channel-type claudins claudin-2 and -15. Claudin-21 also allows the paracellular passage of larger solutes. Our findings suggest that claudin-21-based TJs allow the passage of small and larger solutes by both paracellular channel-based and some additional mechanisms. © 2016, American Society for Microbiology. All Rights Reserved.

  1. B-spline tight frame based force matching method

    Science.gov (United States)

    Yang, Jianbin; Zhu, Guanhua; Tong, Dudu; Lu, Lanyuan; Shen, Zuowei

    2018-06-01

    In molecular dynamics simulations, compared with popular all-atom force field approaches, coarse-grained (CG) methods are frequently used for the rapid investigations of long time- and length-scale processes in many important biological and soft matter studies. The typical task in coarse-graining is to derive interaction force functions between different CG site types in terms of their distance, bond angle or dihedral angle. In this paper, an ℓ1-regularized least squares model is applied to form the force functions, which makes additional use of the B-spline wavelet frame transform in order to preserve the important features of force functions. The B-spline tight frames system has a simple explicit expression which is useful for representing our force functions. Moreover, the redundancy of the system offers more resilience to the effects of noise and is useful in the case of lossy data. Numerical results for molecular systems involving pairwise non-bonded, three and four-body bonded interactions are obtained to demonstrate the effectiveness of our approach.

  2. Pre-Darcy flow in tight and shale formations

    Science.gov (United States)

    Dejam, Morteza; Hassanzadeh, Hassan; Chen, Zhangxin

    2017-11-01

    There are evidences that the fluid flow in tight and shale formations does not follow Darcy law, which is identified as pre-Darcy flow. Here, the unsteady linear flow of a slightly compressible fluid under the action of pre-Darcy flow is modeled and a generalized Boltzmann transformation technique is used to solve the corresponding highly nonlinear diffusivity equation analytically. The effect of pre-Darcy flow on the pressure diffusion in a homogenous formation is studied in terms of the nonlinear exponent, m, and the threshold pressure gradient, G1. In addition, the pressure gradient, flux, and cumulative production per unit area for different m and G1 are compared with the classical solution of the diffusivity equation based on Darcy flow. Department of Petroleum Engineering in College of Engineering and Applied Science at University of Wyoming and NSERC/AI-EES(AERI)/Foundation CMG and AITF (iCORE) Chairs in Department of Chemical and Petroleum Engineering at University of Calgary.

  3. Testing underground tanks for leak tightness at LLNL

    International Nuclear Information System (INIS)

    Henry, R.K.; Sites, R.L.; Sledge, M.

    1986-01-01

    Two types of tank systems are present at the Livermore Site: tanks and associated piping for the storage of fuel (forty-three systems), and tanks or sumps and associated piping for the retention of potentially contaminated wastewater (forty systems). The fuel systems were tested using commercially available test methods: Petro-Tite, Hunter Leak Lokator, Ezy-Chek, and Associated Environmental Systems (A.E.S.). In contrast to fuel tank systems, wastewater systems have containers that are predominantly open at the top and not readily testable. Therefore, a project to test and evaluate all available testing methods was initiated and completed. The commercial method Tank Auditor was determined to be appropriate for testing open-top tanks and sumps and this was the method used to test the majority of the open-top containers. Of the 81 tanks tested, 61 were found to be leak tight, 9 were shown to have leaks, and 11 yielded inconclusive results. Two tanks have not yet been tested because of operational constraints; they are sheduled to be tested within the next two months. Schedules are being developed for the retesting of tanks and for remedial actions

  4. Engineering feasibility of tight aspect ratio Tokamak (spherical torus) reactors

    International Nuclear Information System (INIS)

    Peng, Y-K.M.; Hicks, J.B.

    1990-01-01

    Engineering solutions are identified and analyzed for key high-power-density components of tight aspect ratio tokamak reactors (spherical torus reactors). The potentially extreme divertor heat loads can be reduced to about 3 MW/m 2 in expanded divertors using coils inside the demountable toroidal field coils. Given the long and narrow divertor channels, gaseous divertor targets become possible, which eliminate sputtering and increase the divertor life. The unshielded centre conductor post (CCP) of the toroidal field coil can be made of a single dispersion strengthened copper conductor cooled by high-velocity pressurized water to maintain acceptable copper temperature and strength. Damage and activation of the CCP at a neutron fluence of 10 MW-a/m 2 are also tolerable. Annual replacement of the centre post, the divertor assemblies and the blanket can be accomplished with vertical access for all torus components, which are modularized to reduce size and weight. The technical requirements of these solutions are shown to be comparable with, if not less demanding than, those estimated for conventional tokamak reactors. (author)

  5. Stability of spinor Fermi gases in tight waveguides

    International Nuclear Information System (INIS)

    Campo, A. del; Muga, J. G.; Girardeau, M. D.

    2007-01-01

    The two- and three-body correlation functions of the ground state of an optically trapped ultracold spin-(1/2) Fermi gas (SFG) in a tight waveguide [one-dimensional (1D) regime] are calculated in the plane of even- and odd-wave coupling constants, assuming a 1D attractive zero-range odd-wave interaction induced by a 3D p-wave Feshbach resonance, as well as the usual repulsive zero-range even-wave interaction stemming from 3D s-wave scattering. The calculations are based on the exact mapping from the SFG to a 'Lieb-Liniger-Heisenberg' model with delta-function repulsions depending on isotropic Heisenberg spin-spin interactions, and indicate that the SFG should be stable against three-body recombination in a large region of the coupling constant plane encompassing parts of both the ferromagnetic and antiferromagnetic phases. However, the limiting case of the fermionic Tonks-Girardeau gas, a spin-aligned 1D Fermi gas with infinitely attractive p-wave interactions, is unstable in this sense. Effects due to the dipolar interaction and a Zeeman term due to a resonance-generating magnetic field do not lead to shrinkage of the region of stability of the SFG

  6. Claudin-21 Has a Paracellular Channel Role at Tight Junctions

    KAUST Repository

    Tanaka, Hiroo

    2016-01-05

    Claudin protein family members, of which there are at least 27 in humans and mice, polymerize to form tight junctions (TJs) between epithelial cells, in a tissue- and developmental stage-specific manner. Claudins have a paracellular barrier function. In addition, certain claudins function as paracellular channels for small ions and/or solutes by forming selective pores at the TJs, although the specific claudins involved and their functional mechanisms are still in question. Here we show for the first time that claudin-21, which is more highly expressed in the embryonic than the postnatal stages, acts as a paracellular channel for small cations, such as Na+, similar to the typical channel-type claudins claudin-2 and -15. Claudin-21 also allows the paracellular passage of larger solutes. Our findings suggest that claudin-21-based TJs allow the passage of small and larger solutes by both paracellular channel-based and some additional mechanisms. © 2016, American Society for Microbiology. All Rights Reserved.

  7. Phononic crystals of spherical particles: A tight binding approach

    Energy Technology Data Exchange (ETDEWEB)

    Mattarelli, M., E-mail: maurizio.mattarelli@fisica.unipg.it [NiPS Laboratory, Dipartimento di Fisica, Università di Perugia, Via Pascoli, 06100 Perugia (Italy); Secchi, M. [CMM - Fondazione Bruno Kessler, Via Sommarive 18, 38123 Trento (Italy); Dipartimento di Fisica, Università di Trento, Via Sommarive 14, 38123 Trento (Italy); Montagna, M. [Dipartimento di Fisica, Università di Trento, Via Sommarive 14, 38123 Trento (Italy)

    2013-11-07

    The vibrational dynamics of a fcc phononic crystal of spheres is studied and compared with that of a single free sphere, modelled either by a continuous homogeneous medium or by a finite cluster of atoms. For weak interaction among the spheres, the vibrational dynamics of the phononic crystal is described by shallow bands, with low degree of dispersion, corresponding to the acoustic spheroidal and torsional modes of the single sphere. The phonon displacements are therefore related to the vibrations of a sphere, as the electron wave functions in a crystal are related to the atomic wave functions in a tight binding model. Important dispersion is found for the two lowest phonon bands, which correspond to zero frequency free translation and rotation of a free sphere. Brillouin scattering spectra are calculated at some values of the exchanged wavevectors of the light, and compared with those of a single sphere. With weak interaction between particles, given the high acoustic impedance mismatch in dry systems, the density of phonon states consist of sharp bands separated by large gaps, which can be well accounted for by a single particle model. Based on the width of the frequency gaps, tunable with the particle size, and on the small number of dispersive acoustic phonons, such systems may provide excellent materials for application as sound or heat filters.

  8. Fracture assessment of HSST Plate 14 shallow-flaw cruciform bend specimens tested under biaxial loading conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bass, B.R.; McAfee, W.J.; Williams, P.T.; Pennell, W.E.

    1998-06-01

    A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed for application to the safety assessment of RPVs containing postulated shallow surface flaws. Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow, surface flaws. The cruciform beam specimens were developed at Oak Ridge National Laboratory (ORNL) to introduce a far-field, out-of-plane biaxial stress component in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock or pressure-temperature loading of an RPV. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for an RPV material. The cruciform fracture toughness data were used to evaluate fracture methodologies for predicting the observed effects of biaxial loading on shallow-flaw fracture toughness. Initial emphasis was placed on assessment of stress-based methodologies, namely, the J-Q formulation, the Dodds-Anderson toughness scaling model, and the Weibull approach. Applications of these methodologies based on the hydrostatic stress fracture criterion indicated an effect of loading-biaxiality on fracture toughness; the conventional maximum principal stress criterion indicated no effect. A three-parameter Weibull model based on the hydrostatic stress criterion is shown to correlate the experimentally observed biaxial effect on cleavage fracture toughness by providing a scaling mechanism between uniaxial and biaxial loading states.

  9. School Closings in Philadelphia

    Science.gov (United States)

    Jack, James; Sludden, John

    2013-01-01

    In 2012, the School District of Philadelphia closed six schools. In 2013, it closed 24. The closure of 30 schools has occurred amid a financial crisis, headlined by the district's $1.35 billion deficit. School closures are one piece of the district's plan to cut expenditures and close its budget gap. The closures are also intended to make…

  10. Air Tight: Building Inflatables/Inflatable Construction: Planning and Details

    Science.gov (United States)

    Kennedy, Kriss J.

    2016-01-01

    A design-build seminar consisting of students from Physics, Mechanical and Civil Engineering, Robotic, Material Science, Art, and Architecture who will work together on a deployable "closed-loop" inflatable greenhouse for Mars in theory, and an Earth analogue physical mockup on campus.

  11. Surface passivation for tight-binding calculations of covalent solids

    International Nuclear Information System (INIS)

    Bernstein, N

    2007-01-01

    Simulation of a cluster representing a finite portion of a larger covalently bonded system requires the passivation of the cluster surface. We compute the effects of an explicit hybrid orbital passivation (EHOP) on the atomic structure in a model bulk, three-dimensional, narrow gap semiconductor, which is very different from the wide gap, quasi-one-dimensional organic molecules where most passivation schemes have been studied in detail. The EHOP approach is directly applicable to minimal atomic orbital basis methods such as tight-binding. Each broken bond is passivated by a hybrid created from an explicitly expressed linear combination of basis orbitals, chosen to represent the contribution of the missing neighbour, e.g. a sp 3 hybrid for a single bond. The method is tested by computing the forces on atoms near a point defect as a function of cluster geometry. We show that, compared to alternatives such as pseudo-hydrogen passivation, the force on an atom converges to the correct bulk limit more quickly as a function of cluster radius, and that the force is more stable with respect to perturbations in the position of the cluster centre. The EHOP method also obviates the need for parameterizing the interactions between the system atoms and the passivating atoms. The method is useful for cluster calculations of non-periodic defects in large systems and for hybrid schemes that simulate large systems by treating finite regions with a quantum-mechanical model, coupled to an interatomic potential description of the rest of the system

  12. Self-Consistent Optimization of Excited States within Density-Functional Tight-Binding.

    Science.gov (United States)

    Kowalczyk, Tim; Le, Khoa; Irle, Stephan

    2016-01-12

    We present an implementation of energies and gradients for the ΔDFTB method, an analogue of Δ-self-consistent-field density functional theory (ΔSCF) within density-functional tight-binding, for the lowest singlet excited state of closed-shell molecules. Benchmarks of ΔDFTB excitation energies, optimized geometries, Stokes shifts, and vibrational frequencies reveal that ΔDFTB provides a qualitatively correct description of changes in molecular geometries and vibrational frequencies due to excited-state relaxation. The accuracy of ΔDFTB Stokes shifts is comparable to that of ΔSCF-DFT, and ΔDFTB performs similarly to ΔSCF with the PBE functional for vertical excitation energies of larger chromophores where the need for efficient excited-state methods is most urgent. We provide some justification for the use of an excited-state reference density in the DFTB expansion of the electronic energy and demonstrate that ΔDFTB preserves many of the properties of its parent ΔSCF approach. This implementation fills an important gap in the extended framework of DFTB, where access to excited states has been limited to the time-dependent linear-response approach, and affords access to rapid exploration of a valuable class of excited-state potential energy surfaces.

  13. Aberrant methylation of GCNT2 is tightly related to lymph node metastasis of primary CRC.

    Science.gov (United States)

    Nakamura, Kazunori; Yamashita, Keishi; Sawaki, Hiromichi; Waraya, Mina; Katoh, Hiroshi; Nakayama, Nobukazu; Kawamata, Hiroshi; Nishimiya, Hiroshi; Ema, Akira; Narimatsu, Hisashi; Watanabe, Masahiko

    2015-03-01

    Glycoprotein expression profile is dramatically altered in human cancers; however, specific glycogenes have not been fully identified. A comprehensive real-time polymerase chain reaction (PCR) system for glycogenes (CRPS-G) identified several outstanding glycogenes. GCNT2 was of particular interest after GCNT2 expression and epigenetics were rigorously investigated in primary colorectal cancer (CRC). The highlights of this work can be summarized as follows: (i) Expression of GCNT2 was remarkably suppressed. (ii) Silenced expression of GCNT2 was reactivated by combined demethylating agents. (iii) Promoter DNA methylation of GCNT2 was silenced in CRC cell lines and tissues. Hypomethylation of GCNT2 variant 2 is tightly associated with lymph node metastasis in primary CRC. (iv) GCNT2 methylation level in the normal tissues also showed a close association with that in the tumor tissues and reflected lymph node metastasis. We identified aberrant expression of GCNT2, which can be explained by promoter DNA hypermethylation. Hypomethylation of the GCNT2 variant 2 reflected lymph node metastasis of CRC in the tumor and normal tissues. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  14. Critical power experiment with a tight-lattice 37-rod bundle

    International Nuclear Information System (INIS)

    Kureta, Masatoshi; Tamai, Hidesada; Ohnuki, Akira; Sato, Takashi; Liu, Wei; Akimoto, Hajime

    2006-01-01

    Since most of critical power or CHF data have been collected in tube, annulus, or BWR geometries under BWR flow conditions, critical power data for highly tight and triangular lattice bundles under low mass velocity are indispensable for thermal-hydraulic design of Reduced-Moderation Water Reactor. Large-scale thermal-hydraulic experiments which use a basic 37-rod bundle test section (rod diameter: 13.0 mm, gap width between rods: 1.3 mm) were therefore carried out in this study within range of 2-9 MPa in pressure and 150-1,000 kg/(m 2 ·s) in mass velocity. Fundamental characteristics of boiling transition were investigated through effects of flow parameter on critical power and those of rod number. It was confirmed that the fundamental characteristics in 37-rod bundle are similar to those in 7-rod bundle and in case of the BWR geometry. The results of the transverse non-uniform power distribution test and subchannel analysis suggest that the critical power becomes higher when the transverse local quality distribution closes to uniform. (author)

  15. Proton transfer along water bridges in biological systems with density-functional tight-binding

    Science.gov (United States)

    Reiss, Krystle; Wise, Abigail; Mazzuca, James

    2015-03-01

    When examining the dynamics of charge transfer in high dimensional enzymatic systems, the cost of quantum mechanical treatment of electrons increases exponentially with the size of the system. As a semi-empirical method, density-functional tight-binding aids in shortening these calculation times, but can be inaccurate in the regime where bonds are being formed and broken. To address these inaccuracies with respect to proton transfer in an enzymatic system, DFTB is being used to calculate small model systems containing only a single amino acid residue donor, represented by an imidazole molecule, and a water acceptor. When DFTB calculations are compared to B3LYP geometry calculations of the donor molecule, we observe a bond angle error on the order of 1.2 degrees and a bond length error on the order of 0.011 Å. As we move forward with small donor-acceptor systems, comparisons between DFTB and B3LYP energy profiles will provide a better clue as to what extent improvements need to be made. To improve the accuracy of the DFTB calculations, the internuclear repulsion term may be altered. This would result in energy profiles that closely resemble those produced by higher-level theory. Alma College Provost's Office.

  16. 3D micro-optical elements for generation of tightly focused vortex beams

    Directory of Open Access Journals (Sweden)

    Balčytis Armandas

    2015-01-01

    Full Text Available Orbital angular momentum carrying light beams are usedfor optical trapping and manipulation. This emerging trend provides new challenges involving device miniaturization for improved performance and enhanced functionality at the microscale. Here we discus a new fabrication method based on combining the additive 3D structuring capability laser photopolymerization and the substractive sub-wavelength resolution patterning of focused ion beam lithography to produce micro-optical elements capable of compound functionality. As a case in point of this approach binary spiral zone pattern based high numerical aperture micro-lenses capable of generating topological charge carrying tightly focused vortex beams in a single wavefront transformation step are presented. The devices were modelled using finite-difference time-domain simulations, and the theoretical predictions were verified by optically characterizing the propagation properties of light transmitted through the fabricated structures. The resulting devices had focal lengths close to the predicted values of f = 18 µm and f = 13 µm as well as topological charge ℓ dependent vortex focal spot sizes of ~ 1:3 µm and ~ 2:0 µm for ℓ = 1 and ℓ = 2 respectively.

  17. Dispersion relation and self-collimation frequency of spoof surface plasmon using tight binding model

    International Nuclear Information System (INIS)

    Bhattacharya, Sayak; Shah, Kushal

    2015-01-01

    The analytical dispersion relation of spoof surface plasmon (SSP) is known only in the low-frequency limit and thus cannot be used to describe various practically important characteristics of SSP in the high-frequency limit (such as multimodal nature, anisotropic propagation, self-collimation). In this article, we consider a square lattice of holes made on a perfect electric conductor and derive a closed form expression of the SSP dispersion relation in the high-frequency limit using a tight binding model. Instead of using prior knowledge of the band diagram along the entire first Brillouin zone (BZ) edge, we analytically determine the hopping parameters by using the eigenfrequencies only at the three high-symmetry points of the square lattice. Using this dispersion relation, we derive an expression for the self-collimation frequency of SSP. We show that this analytical formulation is also applicable to dielectric photonic crystals and can be used to predict the frequencies corresponding to centimetre-scale supercollimation and second band self-collimation in these structures. Finally, we show that our analytical results are in agreement with the simulation results for both SSP and photonic crystals. (paper)

  18. A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas

    International Nuclear Information System (INIS)

    Munafò, A.; Alfuhaid, S. A.; Panesi, M.; Cambier, J.-L.

    2015-01-01

    The objective of the present work is the development of a tightly coupled magneto-hydrodynamic model for inductively coupled radio-frequency plasmas. Non Local Thermodynamic Equilibrium (NLTE) effects are described based on a hybrid State-to-State approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electro-magnetic field and the gas properties (e.g., chemical composition and temperatures) are written as a coupled system of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that: (i) the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and (ii) non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients

  19. Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.

  20. Tightness of the thermal envelope of office and educational buildings; Klimaskaermens taethed i kontor- og undervisningsbygninger

    Energy Technology Data Exchange (ETDEWEB)

    Bergsoee, N.C. (SBi, Aalborg (Denmark)); Radisch, N.H.; Nickel, J.; Treldal, J. (Ramboell Danmark A/S, Koebenhavn (Denmark)); Bundesen, E.W.; Nielsen, Carsten (DanEjendomme, Hellerup (Denmark))

    2011-07-01

    In 2006 tightening of the energy regulations in the Danish Building Regulations were introduced including requirements regarding the tightness of the building envelope. The requirements are, with minor changes, continued in the current Building Regulations, BR10. During the past few years experience has been gained regarding both the actual execution of air tightness measurements and solutions that will lead to more air tight building envelopes. Experiences, however, are primarily related to single family houses. The report presents results of measurements in large buildings and discusses reasons for lack of knowledge and experience on the tightness of the building envelope in large buildings. Apparently, there is a need for dissemination of knowledge on the importance of a tight building envelope both in terms of energy consumption and indoor climate and in terms of the difficulties and costs associated with repairing leaks in a completed envelope. Air tightness must be brought into focus at an early stage in the planning process, and during the construction phase air tightness measurements should be performed, e.g. on facade sections or in parts of the building. The project team has attended a number of measurements in large buildings and further gained access to results of a large number of measurements. In summary, the results show that it is possible to achieve the required tightness, and in most buildings the results are better than the requirement of a maximum of 1.5 l/s per m{sub 2}. (Author)

  1. Tightness of M-estimators for multiple linear regression in time series

    DEFF Research Database (Denmark)

    Johansen, Søren; Nielsen, Bent

    We show tightness of a general M-estimator for multiple linear regression in time series. The positive criterion function for the M-estimator is assumed lower semi-continuous and sufficiently large for large argument: Particular cases are the Huber-skip and quantile regression. Tightness requires...

  2. Data analysis algorithms for flaw sizing based on eddy current rotating probe examination of steam generator tubes

    International Nuclear Information System (INIS)

    Bakhtiari, S.; Elmer, T.W.

    2009-01-01

    Computer-aided data analysis tools can help improve the efficiency and reliability of flaw sizing based on nondestructive examination data. They can further help produce more consistent results, which is important for both in-service inspection applications and for engineering assessments associated with steam generator tube integrity. Results of recent investigations at Argonne on the development of various algorithms for sizing of flaws in steam generator tubes based on eddy current rotating probe data are presented. The research was carried out as part of the activities under the International Steam Generator Tube Integrity Program (ISG-TIP) sponsored by the U.S. Nuclear Regulatory Commission. A computer-aided data analysis tool has been developed for off-line processing of eddy current inspection data. The main objectives of the work have been to a) allow all data processing stages to be performed under the same user interface, b) simplify modification and testing of signal processing and data analysis scripts, and c) allow independent evaluation of viable flaw sizing algorithms. The focus of most recent studies at Argonne has been on the processing of data acquired with the +Point probe, which is one of the more widely used eddy current rotating probes for steam generator tube examinations in the U.S. The probe employs a directional surface riding differential coil, which helps reduce the influence of tubing artifacts and in turn helps improve the signal-to-noise ratio. Various algorithms developed under the MATLAB environment for the conversion, segmentation, calibration, and analysis of data have been consolidated within a single user interface. Data acquired with a number of standard eddy current test equipment are automatically recognized and converted to a standard format for further processing. Because of its modular structure, the graphical user interface allows user-developed routines to be easily incorporated, modified, and tested independent of the

  3. Water-tight knee arthrotomy closure: comparison of a novel single bidirectional barbed self-retaining running suture versus conventional interrupted sutures.

    Science.gov (United States)

    Nett, Michael; Avelar, Rui; Sheehan, Michael; Cushner, Fred

    2011-03-01

    Standard medial parapatellar arthrotomies of 10 cadaveric knees were closed with either conventional interrupted absorbable sutures (control group, mean of 19.4 sutures) or a single running knotless bidirectional barbed absorbable suture (experimental group). Water-tightness of the arthrotomy closure was compared by simulating a tense hemarthrosis and measuring arthrotomy leakage over 3 minutes. Mean total leakage was 356 mL and 89 mL in the control and experimental groups, respectively (p = 0.027). Using 8 of the 10 knees (4 closed with control sutures, 4 closed with an experimental suture), a tense hemarthrosis was again created, and iatrogenic suture rupture was performed: a proximal suture was cut at 1 minute; a distal suture was cut at 2 minutes. The impact of suture rupture was compared by measuring total arthrotomy leakage over 3 minutes. Mean total leakage was 601 mL and 174 mL in the control and experimental groups, respectively (p = 0.3). In summary, using a cadaveric model, arthrotomies closed with a single bidirectional barbed running suture were statistically significantly more water-tight than those closed using a standard interrupted technique. The sample size was insufficient to determine whether the two closure techniques differed in leakage volume after suture rupture.

  4. Structural diagenesis in Upper Carboniferous tight gas sandstones. Lessons learned from the Piesberg analog study

    Energy Technology Data Exchange (ETDEWEB)

    Steindorf, P.; Hoehne, M.; Becker, S.; Hilgers, C. [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group (EMR); Koehrer, B. [Wintershall Holding GmbH, Barnstorf (Germany)

    2013-08-01

    Upper Carboniferous tight gas sandstone reservoirs in NW-Germany consist of thick successions of cyclothems. Our focus is the Westphalian D of the Piesberg quarry near Osnabrueck, which exposes cemented, faulted and jointed third-order coarse- to fine-grained sandstone cycles separated by anthracite coal seams. We characterize the rocks and the lateral variation of rock properties such as porosity to better constrain input data for reservoir modelling. Three cycles are exposed, each approximately 50 m thick. Rock types can be clearly distinguished by spectral gamma ray in the quarry. Sandstones are intensely compacted and cemented with quartz and generally characterized by low porosities < 8 % (Hepycnometry on plugs and cuttings). Porosities are secondary and mainly related to detrital carbonate dissolution. Around faults dissolution is higher and the porosities can increase to up to 25%. The normal faults show different throws in the quarry and bands of shale and coal have smeared into the fault at juxtaposed beds, which may result in compartments. They dominantly strike W-E and NNW-SSE, but subordinate NE-SW striking fault patterns are also present. Joints were analyzed in a 50 x 50 m section of the quarry wall using Lidar (Light detection and ranging) laser scanning, which allows the characterization of the lithology and quantitative measurement of bedding and fracture orientation data in inaccessible areas. NNE-SSW and W-E joint sets are accompanied by northeasterly and northwesterly striking sets. Around faults, fault planes and fractures are cemented with quartz veins, showing localized mass transport. Due to the intense cementation, the sandstones can reach uniaxial strengths of more than 100 MPa normal to bedding, and approximately 50 MPa parallel to bedding. Sandstone beds within and close to faults are leached by fluids, and their uniaxial strength is reduced by a factor of more than two. Our high resolution field data enables a better understanding of

  5. Transferable tight-binding model for strained group IV and III-V materials and heterostructures

    Science.gov (United States)

    Tan, Yaohua; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy B.; Klimeck, Gerhard

    2016-07-01

    It is critical to capture the effect due to strain and material interface for device level transistor modeling. We introduce a transferable s p3d5s* tight-binding model with nearest-neighbor interactions for arbitrarily strained group IV and III-V materials. The tight-binding model is parametrized with respect to hybrid functional (HSE06) calculations for varieties of strained systems. The tight-binding calculations of ultrasmall superlattices formed by group IV and group III-V materials show good agreement with the corresponding HSE06 calculations. The application of the tight-binding model to superlattices demonstrates that the transferable tight-binding model with nearest-neighbor interactions can be obtained for group IV and III-V materials.

  6. The approach to analysis of significance of flaws in ASME section III and section XI

    International Nuclear Information System (INIS)

    Cowan, A.

    1979-01-01

    ASME III Appendix G and ASME XI Appendix A describe linear elastic fracture mechanics methods to assess the significance of defects in thick-walled pressure vessels for nuclear reactor systems. The assessment of fracture toughness, Ksub(Ic), is based upon recommendations made by a Task Group of the USA Pressure Vessel Research Committee and is dependent upon correlations with drop weight and Charpy V-notch data to give a lower bound of fracture toughness Ksub(IR). The methods used in the ASME Appendices are outlined noting that, whereas ASME III Appendix G defines a procedure for obtaining allowable pressure vessel loadings for normal service in the presence of a defect, ASME XI Appendix A defines methods for assessing the significance of defects (found by volumetric inspection) under normal and emergency and faulted conditions. The methods of analysis are discussed with respect to material properties, flaw characterisation, stress analysis and recommended safety factors; a short discussion is given on the applicability of the data and methods to other materials and non-nuclear structures. (author)

  7. Model-assisted probability of detection of flaws in aluminum blocks using polynomial chaos expansions

    Science.gov (United States)

    Du, Xiaosong; Leifsson, Leifur; Grandin, Robert; Meeker, William; Roberts, Ronald; Song, Jiming

    2018-04-01

    Probability of detection (POD) is widely used for measuring reliability of nondestructive testing (NDT) systems. Typically, POD is determined experimentally, while it can be enhanced by utilizing physics-based computational models in combination with model-assisted POD (MAPOD) methods. With the development of advanced physics-based methods, such as ultrasonic NDT testing, the empirical information, needed for POD methods, can be reduced. However, performing accurate numerical simulations can be prohibitively time-consuming, especially as part of stochastic analysis. In this work, stochastic surrogate models for computational physics-based measurement simulations are developed for cost savings of MAPOD methods while simultaneously ensuring sufficient accuracy. The stochastic surrogate is used to propagate the random input variables through the physics-based simulation model to obtain the joint probability distribution of the output. The POD curves are then generated based on those results. Here, the stochastic surrogates are constructed using non-intrusive polynomial chaos (NIPC) expansions. In particular, the NIPC methods used are the quadrature, ordinary least-squares (OLS), and least-angle regression sparse (LARS) techniques. The proposed approach is demonstrated on the ultrasonic testing simulation of a flat bottom hole flaw in an aluminum block. The results show that the stochastic surrogates have at least two orders of magnitude faster convergence on the statistics than direct Monte Carlo sampling (MCS). Moreover, the evaluation of the stochastic surrogate models is over three orders of magnitude faster than the underlying simulation model for this case, which is the UTSim2 model.

  8. Toward Smart Aerospace Structures: Design of a Piezoelectric Sensor and Its Analog Interface for Flaw Detection

    Science.gov (United States)

    Boukabache, Hamza; Escriba, Christophe; Fourniols, Jean-Yves

    2014-01-01

    Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures' reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure's integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated. PMID:25365457

  9. Marine Protected Dramas: The Flaws of the Brazilian National System of Marine Protected Areas

    Science.gov (United States)

    Gerhardinger, Leopoldo C.; Godoy, Eduardo A. S.; Jones, Peter J. S.; Sales, Gilberto; Ferreira, Beatrice P.

    2011-04-01

    This article discusses the current problems and issues associated with the implementation of a National System of Marine Protected Areas in Brazil. MPA managers and higher governmental level authorities were interviewed about their perceptions of the implementation of a national MPA strategy and the recent changes in the institutional arrangement of government marine conservation agencies. Interviewees' narratives were generally pessimistic and the National System was perceived as weak, with few recognizable marine conservation outcomes on the ground. The following major flaws were identified: poor inter-institutional coordination of coastal and ocean governance; institutional crisis faced by the national government marine conservation agency; poor management within individual MPAs; problems with regional networks of marine protected areas; an overly bureaucratic management and administrative system; financial shortages creating structural problems and a disconnect between MPA policy and its delivery. Furthermore, a lack of professional motivation and a pessimistic atmosphere was encountered during many interviews, a malaise which we believe affects how the entire system is able to respond to crises. Our findings highlight the need for a better understanding of the role of `leadership' in the performance of socio-ecological systems (such as MPA networks), more effective official evaluation mechanisms, more localized audits of (and reforms if necessary to) Brazil's federal biodiversity conservation agency (ICMBio), and the need for political measures to promote state leadership and support. Continuing to focus on the designation of more MPAs whilst not fully addressing these issues will achieve little beyond fulfilling, on paper, Brazil's international marine biodiversity commitments.

  10. PowerPoint® Presentation Flaws and Failures: A Psychological Analysis

    Directory of Open Access Journals (Sweden)

    Stephen Michael Kosslyn

    2012-07-01

    Full Text Available Electronic slideshow presentations are often faulted anecdotally, but little empirical work has documented their faults. Three studies reported here document psychological causes of their flaws. In Study 1 we found that eight psychological principles are often violated in PowerPoint® presentations, across different fields—for example, academic research presentations generally were no better or worse than business presentations. In Study 2 we found that respondents reported having noticed, and having been annoyed by, specific problems in presentations arising from violations of particular psychological principles. Finally, in Study 3 we showed that observers are not highly accurate in recognizing when slides violated a specific psychological rule. Furthermore, even when they correctly identified the violation, they often could not explain the nature of the problem. In sum, the psychological foundations for effective slideshow presentation design are neither obvious nor necessarily intuitive, and presentation designers in all fields, from education to business to government, could benefit from explicit instruction in relevant aspects of psychology.

  11. Flaw assessment guide for high-temperature reactor components subject to creep-fatigue loading

    International Nuclear Information System (INIS)

    Ainsworth, R.A.; Takahashi, Y.

    1990-10-01

    A high-temperature flaw assessment procedure is described. This procedure is a result of a collaborative effort between Electric Power Research Institute in the United States, Central Research Institute of Electric Power Industry in Japan, and Nuclear Electric plc in the United Kingdom. The procedure addresses preexisting defects subject to creep-fatigue loading conditions. Laws employed to calculate the crack growth per cycle are defined in terms of fracture mechanics parameters and constants related to the component material. The crack-growth laws can be integrated to calculate the remaining life of a component or to predict the amount of crack extension in a given period. Fatigue and creep crack growth per cycle are calculated separately, and the total crack extension is taken as the simple sum of the two contributions. An interaction between the two propagation modes is accounted for in the material properties in the separate calculations. In producing the procedure, limitations of the approach have been identified. 25 refs., 1 fig

  12. Robust and reliable banknote authentification and print flaw detection with opto-acoustical sensor fusion methods

    Science.gov (United States)

    Lohweg, Volker; Schaede, Johannes; Türke, Thomas

    2006-02-01

    The authenticity checking and inspection of bank notes is a high labour intensive process where traditionally every note on every sheet is inspected manually. However with the advent of more and more sophisticated security features, both visible and invisible, and the requirement of cost reduction in the printing process, it is clear that automation is required. As more and more print techniques and new security features will be established, total quality security, authenticity and bank note printing must be assured. Therefore, this factor necessitates amplification of a sensorial concept in general. We propose a concept for both authenticity checking and inspection methods for pattern recognition and classification for securities and banknotes, which is based on the concept of sensor fusion and fuzzy interpretation of data measures. In the approach different methods of authenticity analysis and print flaw detection are combined, which can be used for vending or sorting machines, as well as for printing machines. Usually only the existence or appearance of colours and their textures are checked by cameras. Our method combines the visible camera images with IR-spectral sensitive sensors, acoustical and other measurements like temperature and pressure of printing machines.

  13. A surface flaw sizing study by time-of-flight ultrasonic technique

    International Nuclear Information System (INIS)

    Lamy, C.A.

    1990-07-01

    In this work, sizing of inclined slits and surface cracks in ferritic steel using the ultrasonic time-of-flight technique was studied. The surface cracks were vertical and inclined, nut the slits were only inclined. It was surface Rayleigh wave that was converted to shear wave mode in the material. The specimens with surface crack were submitted to a three four point loading fracture mechanics tests, so that the region of the crack tip became under an increasing tensile stress. Thus, the ultrasonic crack sizing could be compared to the material stress intensity factor (K) of the material for different loadings. Results show that the greater the slope and/or lenght of the slits the greater its subsizing. Vertical cracks int he parent metal are reliably and accuratly sized; in the weld the same remark held if one increases the gain of ultrasonic flaw detector to compensate for the weld attenuation phenomenon. Sizing of inclined cracks in the parent metal shows the same trends of the inclined slits, differing only in slopes over 30 sup(0) where the sizing in surface cracks is no longer reliable. A new appraisal procedure here proposed made reliable these results. The techniques employed in this work lead to reliable and accurate results for sizing of different slits and cracks. It should be noted however that good results are only obtained if a tensile stress state exists in the neighbourhood of the c rack tip. (author)

  14. A Bayesian approach to modeling and predicting pitting flaws in steam generator tubes

    International Nuclear Information System (INIS)

    Yuan, X.-X.; Mao, D.; Pandey, M.D.

    2009-01-01

    Steam generators in nuclear power plants have experienced varying degrees of under-deposit pitting corrosion. A probabilistic model to accurately predict pitting damage is necessary for effective life-cycle management of steam generators. This paper presents an advanced probabilistic model of pitting corrosion characterizing the inherent randomness of the pitting process and measurement uncertainties of the in-service inspection (ISI) data obtained from eddy current (EC) inspections. A Markov chain Monte Carlo simulation-based Bayesian method, enhanced by a data augmentation technique, is developed for estimating the model parameters. The proposed model is able to predict the actual pit number, the actual pit depth as well as the maximum pit depth, which is the main interest of the pitting corrosion model. The study also reveals the significance of inspection uncertainties in the modeling of pitting flaws using the ISI data: Without considering the probability-of-detection issues and measurement errors, the leakage risk resulted from the pitting corrosion would be under-estimated, despite the fact that the actual pit depth would usually be over-estimated.

  15. Simplified probabilistic approach to determine safety factors in deterministic flaw acceptance criteria

    International Nuclear Information System (INIS)

    Barthelet, B.; Ardillon, E.

    1997-01-01

    The flaw acceptance rules in nuclear components rely on deterministic criteria supposed to ensure the safe operating of plants. The interest of having a reliable method of evaluating the safety margins and the integrity of components led Electricite de France to launch a study to link safety factors with requested reliability. A simplified analytical probabilistic approach is developed to analyse the failure risk in Fracture Mechanics. Assuming lognormal distributions of the main random variables, it is possible considering a simple Linear Elastic Fracture Mechanics model, to determine the failure probability as a function of mean values and logarithmic standard deviations. The 'design' failure point can be analytically calculated. Partial safety factors on the main variables (stress, crack size, material toughness) are obtained in relation with reliability target values. The approach is generalized to elastic plastic Fracture Mechanics (piping) by fitting J as a power law function of stress, crack size and yield strength. The simplified approach is validated by detailed probabilistic computations with PROBAN computer program. Assuming reasonable coefficients of variations (logarithmic standard deviations), the method helps to calibrate safety factors for different components taking into account reliability target values in normal, emergency and faulted conditions. Statistical data for the mechanical properties of the main basic materials complement the study. The work involves laboratory results and manufacture data. The results of this study are discussed within a working group of the French in service inspection code RSE-M. (authors)

  16. Application of flaw detection methods for detection of fatigue processes in low-alloyed steel

    Directory of Open Access Journals (Sweden)

    Zbigniew H. śUREK

    2007-01-01

    Full Text Available The paper presents the investigations conducted in the Fraunhofer Institute (IZFP Saarbrücken by use of a BEMI microscope (BEMI= Barkhausenrausch- und Wirbelstrom-Mikroskopie or Barkhausen Noise and Eddy Current Microscopy. The ability to detect cyclic and contact fatigue load influences has been investigated. The measurement amplitudes obtained with Barkhausen Noise and Eddy Current probes havebeen analysed. Correlation of measurement results and material’s condition has been observed in case of the eddy current mode method for frequencies above 2 MHz (for contact-loaded material samples. Detection of material’s fatigue process (at 80 % fatiguelife in the sample subjected to series of high-cyclic loads has been proven to be practically impossible. Application of flaw detection methods in material fatigue tests requires modification of test methods and use of investigation methods relevant to physical parameters of the investigated material. The magnetic leakage field method, which has been abandoned by many researchers, may be of significant use in the material fatigue assessment and may provide new research prospects.

  17. Toward smart aerospace structures: design of a piezoelectric sensor and its analog interface for flaw detection.

    Science.gov (United States)

    Boukabache, Hamza; Escriba, Christophe; Fourniols, Jean-Yves

    2014-10-31

    Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures' reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure's integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated.

  18. Systematic reviews identify important methodological flaws in stroke rehabilitation therapy primary studies: review of reviews.

    Science.gov (United States)

    Santaguida, Pasqualina; Oremus, Mark; Walker, Kathryn; Wishart, Laurie R; Siegel, Karen Lohmann; Raina, Parminder

    2012-04-01

    A "review of reviews" was undertaken to assess methodological issues in studies evaluating nondrug rehabilitation interventions in stroke patients. MEDLINE, CINAHL, PsycINFO, and the Cochrane Database of Systematic Reviews were searched from January 2000 to January 2008 within the stroke rehabilitation setting. Electronic searches were supplemented by reviews of reference lists and citations identified by experts. Eligible studies were systematic reviews; excluded citations were narrative reviews or reviews of reviews. Review characteristics and criteria for assessing methodological quality of primary studies within them were extracted. The search yielded 949 English-language citations. We included a final set of 38 systematic reviews. Cochrane reviews, which have a standardized methodology, were generally of higher methodological quality than non-Cochrane reviews. Most systematic reviews used standardized quality assessment criteria for primary studies, but not all were comprehensive. Reviews showed that primary studies had problems with randomization, allocation concealment, and blinding. Baseline comparability, adverse events, and co-intervention or contamination were not consistently assessed. Blinding of patients and providers was often not feasible and was not evaluated as a source of bias. The eligible systematic reviews identified important methodological flaws in the evaluated primary studies, suggesting the need for improvement of research methods and reporting. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Systematization of simplified J-integral evaluation method for flaw evaluation at high temperature

    International Nuclear Information System (INIS)

    Miura, Naoki; Takahashi, Yukio; Nakayama, Yasunari; Shimakawa, Takashi

    2000-01-01

    J-integral is an effective inelastic fracture parameter for the flaw evaluation of cracked components at high temperature. The evaluation of J-integral for an arbitrary crack configuration and an arbitrary loading condition can be generally accomplished by detailed numerical analysis such as finite element analysis, however, it is time-consuming and requires a high degree of expertise for its implementation. Therefore, it is important to develop simplified J-integral estimation techniques from the viewpoint of industrial requirements. In this study, a simplified J-integral evaluation method is proposed to estimate two types of J-integral parameters. One is the fatigue J-integral range to describe fatigue crack propagation behavior, and the other is the creep J-integral to describe creep crack propagation behavior. This paper presents the systematization of the simplified J-integral evaluation method incorporated with the reference stress method and the concept of elastic follow-up, and proposes a comprehensive evaluation procedure. The verification of the proposed method is presented in Part II of this paper. (author)

  20. Toward Smart Aerospace Structures: Design of a Piezoelectric Sensor and Its Analog Interface for Flaw Detection

    Directory of Open Access Journals (Sweden)

    Hamza Boukabache

    2014-10-01

    Full Text Available Structural health monitoring using noninvasive methods is one of the major challenges that aerospace manufacturers face in this decade. Our work in this field focuses on the development and the system integration of millimetric piezoelectric sensors/ actuators to generate and measure specific guided waves. The aim of the application is to detect mechanical flaws on complex composite and alloy structures to quantify efficiently the global structures’ reliability. The study begins by a physical and analytical analysis of a piezoelectric patch. To preserve the structure’s integrity, the transducers are directly pasted onto the surface which leads to a critical issue concerning the interfacing layer. In order to improve the reliability and mitigate the influence of the interfacing layer, the global equations of piezoelectricity are coupled with a load transfer model. Thus we can determine precisely the shear strain developed on the surface of the structure. To exploit the generated signal, a high precision analog charge amplifier coupled to a double T notch filter were designed and scaled. Finally, a novel joined time-frequency analysis based on a wavelet decomposition algorithm is used to extract relevant structures signatures. Finally, this paper provides examples of application on aircraft structure specimens and the feasibility of the system is thus demonstrated.

  1. Use of flawed multiple-choice items by the New England Journal of Medicine for continuing medical education.

    Science.gov (United States)

    Stagnaro-Green, Alex S; Downing, Steven M

    2006-09-01

    Physicians in the United States are required to complete a minimum number of continuing medical education (CME) credits annually. The goal of CME is to ensure that physicians maintain their knowledge and skills throughout their medical career. The New England Journal of Medicine (NEJM) provides its readers with the opportunity to obtain weekly CME credits. Deviation from established item-writing principles may result in a decrease in validity evidence for tests. This study evaluated the quality of 40 NEJM MCQs using the standard evidence-based principles of effective item writing. Each multiple-choice item reviewed had at least three item flaws, with a mean of 5.1 and a range of 3 to 7. The results of this study demonstrate that the NEJM uses flawed MCQs in its weekly CME program.

  2. Acoustic Emission Behavior of Rock-Like Material Containing Two Flaws in the Process of Deformation Failure

    Directory of Open Access Journals (Sweden)

    Quan-Sheng Liu

    2015-01-01

    Full Text Available Many sudden disasters (such as rock burst by mining extraction originate in crack initiation and propagation. Meanwhile a large number of shock waves are produced by rock deformation and failure. With the purpose of investigating crack coalescence and failure mechanism in rock, experimental research of rock-like materials with two preexisting flaws was performed. Moreover, the AE technique and photographic monitoring were adopted to clarify further the procedure of the crack coalescence and failure. It reveals that AE location technique can record the moments of crack occurrences and follow the crack growth until final failure. Finally, the influence of different flaw geometries on crack initiation strength is analyzed in detail. This research provides increased understanding of the fracture mechanism of mining-induced disasters.

  3. Preliminary experimental results for a non-intrusive scheme for the detection of flaws in metal pipelines

    Science.gov (United States)

    Aydin, K.; Shinde, S.; Suhail, M.; Vyas, A.; Zieher, K. W.

    2002-05-01

    An acoustic pulse echo scheme for non-intrusive detection of flaws in metal pipelines has been investigated in the laboratory. The primary pulse is generated by a pulsed magnetic field enclosing a short section of a free pipe. The detection is by an electrostatic detector surrounding a short section of the pipe. Reflected pulses from thin areas, with a longitudinal extension of about one pipe radius and a reduction of the wall thickness of 40%, can be detected clearly.

  4. FDAAA legislation is working, but methodological flaws undermine the reliability of clinical trials: a cross-sectional study

    OpenAIRE

    Douglas H. Marin dos Santos; Álvaro N. Atallah

    2015-01-01

    The relationship between clinical research and the pharmaceutical industry has placed clinical trials in jeopardy. According to the medical literature, more than 70% of clinical trials are industry-funded. Many of these trials remain unpublished or have methodological flaws that distort their results. In 2007, it was signed into law the Food and Drug Administration Amendments Act (FDAAA), aiming to provide publicly access to a broad range of biomedical information to be made available on the ...

  5. Restaurants closed over Christmas

    CERN Multimedia

    2011-01-01

    The restaurants will be closed during the Christmas holiday period : please note that all three CERN Restaurants will be closed from 5 p.m. on Wednesday, 21 December until Wednesday, 4 January inclusive. The Restaurants will reopen on Thursday, 5 January 2012.

  6. FDAAA legislation is working, but methodological flaws undermine the reliability of clinical trials: a cross-sectional study

    Directory of Open Access Journals (Sweden)

    Douglas H. Marin dos Santos

    2015-06-01

    Full Text Available The relationship between clinical research and the pharmaceutical industry has placed clinical trials in jeopardy. According to the medical literature, more than 70% of clinical trials are industry-funded. Many of these trials remain unpublished or have methodological flaws that distort their results. In 2007, it was signed into law the Food and Drug Administration Amendments Act (FDAAA, aiming to provide publicly access to a broad range of biomedical information to be made available on the platform ClinicalTrials (available at https://www.clinicaltrials.gov. We accessed ClinicalTrials.gov and evaluated the compliance of researchers and sponsors with the FDAAA. Our sample comprised 243 protocols of clinical trials of biological monoclonal antibodies (mAb adalimumab, bevacizumab, infliximab, rituximab, and trastuzumab. We demonstrate that the new legislation has positively affected transparency patterns in clinical research, through a significant increase in publication and online reporting rates after the enactment of the law. Poorly designed trials, however, remain a challenge to be overcome, due to a high prevalence of methodological flaws. These flaws affect the quality of clinical information available, breaching ethical duties of sponsors and researchers, as well as the human right to health.

  7. FDAAA legislation is working, but methodological flaws undermine the reliability of clinical trials: a cross-sectional study.

    Science.gov (United States)

    Marin Dos Santos, Douglas H; Atallah, Álvaro N

    2015-01-01

    The relationship between clinical research and the pharmaceutical industry has placed clinical trials in jeopardy. According to the medical literature, more than 70% of clinical trials are industry-funded. Many of these trials remain unpublished or have methodological flaws that distort their results. In 2007, it was signed into law the Food and Drug Administration Amendments Act (FDAAA), aiming to provide publicly access to a broad range of biomedical information to be made available on the platform ClinicalTrials (available at https://www.clinicaltrials.gov). We accessed ClinicalTrials.gov and evaluated the compliance of researchers and sponsors with the FDAAA. Our sample comprised 243 protocols of clinical trials of biological monoclonal antibodies (mAb) adalimumab, bevacizumab, infliximab, rituximab, and trastuzumab. We demonstrate that the new legislation has positively affected transparency patterns in clinical research, through a significant increase in publication and online reporting rates after the enactment of the law. Poorly designed trials, however, remain a challenge to be overcome, due to a high prevalence of methodological flaws. These flaws affect the quality of clinical information available, breaching ethical duties of sponsors and researchers, as well as the human right to health.

  8. Combining usability evaluations to highlight the chain that leads from usability flaws to usage problems and then negative outcomes.

    Science.gov (United States)

    Watbled, Ludivine; Marcilly, Romaric; Guerlinger, Sandra; Bastien, J-M Christian; Beuscart-Zéphir, Marie-Catherine; Beuscart, Régis

    2018-02-01

    Poor usability of health technology is thought to diminish work system performance, increase error rates and, potentially, harm patients. The present study (i) used a combination of usability evaluation methods to highlight the chain that leads from usability flaws to usage problems experienced by users and, ultimately, to negative patient outcomes, and (ii) validated this approach by studying two different discharge summary production systems. To comply with quality guidelines, the process of drafting and sending discharge summaries is increasingly being automated. However, the usability of these systems may modify their impact (or the absence thereof) in terms of production times and quality, and must therefore be evaluated. Here, we applied three successive techniques for usability evaluation (heuristic evaluation, user testing and field observation) to two discharge summary production systems (underpinned by different technologies). The systems' main usability flaws led respectively to an increase in the time need to produce a discharge summary and the risk of patient misidentification. Our results are discussed with regard to the possibility of linking the usability flaws, usage problems and the negative outcomes by successively applying three methods for evaluating usability (heuristic evaluation, user testing and in situ observations) throughout the system development life cycle. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Study on water leak-tightness of small leaks on a 1 inch cylinder valve

    International Nuclear Information System (INIS)

    Miyazawa, T.; Kasai, Y.; Inabe, N.; Aritomi, M.

    2002-01-01

    Practical thresholds for water leak-tightness of small leaks were determined by experimentation. Measurements for small leak samples were taken of air leakage rates and water leakage rates for identical leak samples in order to identify parameters that influence water leak-tightness threshold. Four types of leaks were evaluated: a fine wire inserted in an O-ring seal, a glass capillary tube, a stainless steel orifice, and a scratched valve stem on a 1 inch UF 6 cylinder valve. Experimental results demonstrated that the key parameter for water leak-tightness is the opening size of the leak hole. The maximum allowable hole size to achieve water leak-tightness ranged from 10 to 20 μm in diameter in this study. Experimental results with 1 inch UF 6 cylinder valve samples demonstrated that the acceptance criteria for preshipment leakage test, 1x10 -3 ref-cm 3 .s -1 , as prescribed in ANSI N14.5 is an appropriate value from the point of view of water leak-tightness for enriched UF 6 packages. The mechanism of water leak-tightness is plugging by tiny particles existing in water. The water used in experiments in this study contained far fewer particles than in water assumed to be encountered under accident conditions of transport. Therefore, the water leak-tightness threshold determined in this study is a conservative value in a practical evaluation. (author)

  10. Impact of Air Tightness on the Evaluation of Building Energy Performance in Lithuania

    Directory of Open Access Journals (Sweden)

    Jolanta Šadauskienė

    2014-08-01

    Full Text Available In order to fulfil the European Energy Performance of Buildings Directive (EPBD requirements for the reduction of energy consumption, European national requirements have been created for building envelope thermal properties and calculation methodology to determine if building energy efficiency is created. This is however not true in all methodologies. The necessity of building air tightness appears only for new A class buildings, and there are no requirements for air tightness for other building classes. Therefore, the aim of this work is to improve the methodology for the calculation of energy efficiency of buildings, while taking into account the air tightness of the buildings. In order to achieve this aim, the sum energy consumption of investigated buildings was calculated, energy efficiency classes were determined, air tightness of the buildings was measured, and reasons for insufficient air tightness were analyzed. Investigation results show that the average value of air tightness of A energy efficiency class buildings is 0.6 h−1. The results of other investigated buildings, corresponding to B and C energy efficiency classes, show insufficient air tightness (the average n50 value is 6 h−1; herewith, energy consumption for heating is higher than calculated, according to the energy efficiency methodology. This paper provides an energy performance evaluation scheme, under which performed evaluation of energy performance of buildings ensures high quality construction work, building durability, and the reliability of heat-loss calculations.

  11. A Critical Assessment of Child Custody Evaluations: Limited Science and a Flawed System.

    Science.gov (United States)

    Emery, Robert E; Otto, Randy K; O'Donohue, William T

    2005-07-01

    further scientific investigation. We see the system for resolving custody disputes as deeply flawed, for reasons that go beyond the problem of limited science. The coupling of the vague "best interests of the child" test with the American adversary system of justice puts judges in the position of trying to perform an impossible task, and it exacerbates parental conflict and problems in parenting and coparenting, which psychological science clearly shows to be key factors predicting children's psychological difficulties in response to their parents' separation and divorce. Our analysis of the flawed system, together with our desire to sharply limit custody disputes and custody evaluations, leads us to propose three reforms. First, we urge continued efforts to encourage parents to reach custody agreements on their own-in divorce mediation, through collaborative law, in good-faith attorney negotiations, in therapy, and in other forums. Some such efforts have been demonstrated to improve parent-parent and parent-child relationships long after divorce, and they embrace the philosophical position that, in the absence of abuse or neglect, parents themselves should determine their children's best interests after separation, just as they do in marriage. Second, we urge state legislatures to move toward adopting more clear and determinative custody rules, a step that would greatly clarify the terms of the marriage contract, limit the need for custody evaluations, and sharply narrow the scope of the evaluation process. We find particular merit in the proposed "approximation rule" (recently embraced by the American Law Institute), in which postdivorce parenting arrangements would approximate parenting involvement in marriage. Third and finally, we recommend that custody evaluators follow the law and only offer opinions for which there is an adequate scientific basis. Related to this, we urge professional bodies to enact more specific standards of practice on this and related issues

  12. Electro-optical properties of zigzag and armchair boron nitride nanotubes under a transverse electric field: Tight binding calculations

    Science.gov (United States)

    Chegel, Raad; Behzad, Somayeh

    2012-02-01

    The electro-optical properties of zigzag and armchair BNNTs in a uniform transverse electric field are investigated within tight binding approximation. It is found that the electric field modifies the band structure and splits band degeneracy where these effects reflect in the DOS and JDOS spectra. A decrease in the band gap, as a function of the electric field, is observed. This gap reduction increases with the diameter and it is independent of chirality. An analytic function to estimate the electric field needed for band gap closing is proposed which is in good agreement with DFT results. In additional, we show that the larger diameter tubes are more sensitive than small ones. Number and position of peaks in DOS and JDOS spectra for armchair and zigzag tubes with similar radius are dependent on electric field strength.

  13. Have recent earthquakes exposed flaws in or misunderstandings of probabilistic seismic hazard analysis?

    Science.gov (United States)

    Hanks, Thomas C.; Beroza, Gregory C.; Toda, Shinji

    2012-01-01

    In a recent Opinion piece in these pages, Stein et al. (2011) offer a remarkable indictment of the methods, models, and results of probabilistic seismic hazard analysis (PSHA). The principal object of their concern is the PSHA map for Japan released by the Japan Headquarters for Earthquake Research Promotion (HERP), which is reproduced by Stein et al. (2011) as their Figure 1 and also here as our Figure 1. It shows the probability of exceedance (also referred to as the “hazard”) of the Japan Meteorological Agency (JMA) intensity 6–lower (JMA 6–) in Japan for the 30-year period beginning in January 2010. JMA 6– is an earthquake-damage intensity measure that is associated with fairly strong ground motion that can be damaging to well-built structures and is potentially destructive to poor construction (HERP, 2005, appendix 5). Reiterating Geller (2011, p. 408), Stein et al. (2011, p. 623) have this to say about Figure 1: The regions assessed as most dangerous are the zones of three hypothetical “scenario earthquakes” (Tokai, Tonankai, and Nankai; see map). However, since 1979, earthquakes that caused 10 or more fatalities in Japan actually occurred in places assigned a relatively low probability. This discrepancy—the latest in a string of negative results for the characteristic model and its cousin the seismic-gap model—strongly suggest that the hazard map and the methods used to produce it are flawed and should be discarded. Given the central role that PSHA now plays in seismic risk analysis, performance-based engineering, and design-basis ground motions, discarding PSHA would have important consequences. We are not persuaded by the arguments of Geller (2011) and Stein et al. (2011) for doing so because important misunderstandings about PSHA seem to have conditioned them. In the quotation above, for example, they have confused important differences between earthquake-occurrence observations and ground-motion hazard calculations.

  14. The impacts of observing flawed and flawless demonstrations on clinical skill learning.

    Science.gov (United States)

    Domuracki, Kurt; Wong, Arthur; Olivieri, Lori; Grierson, Lawrence E M

    2015-02-01

    Clinical skills expertise can be advanced through accessible and cost-effective video-based observational practice activities. Previous findings suggest that the observation of performances of skills that include flaws can be beneficial to trainees. Observing the scope of variability within a skilled movement allows learners to develop strategies to manage the potential for and consequences associated with errors. This study tests this observational learning approach on the development of the skills of central line insertion (CLI). Medical trainees with no CLI experience (n = 39) were randomised to three observational practice groups: a group which viewed and assessed videos of an expert performing a CLI without any errors (F); a group which viewed and assessed videos that contained a mix of flawless and errorful performances (E), and a group which viewed the same videos as the E group but were also given information concerning the correctness of their assessments (FA). All participants interacted with their observational videos each day for 4 days. Following this period, participants returned to the laboratory and performed a simulation-based insertion, which was assessed using a standard checklist and a global rating scale for the skill. These ratings served as the dependent measures for analysis. The checklist analysis revealed no differences between observational learning groups (grand mean ± standard error: [20.3 ± 0.7]/25). However, the global rating analysis revealed a main effect of group (d.f.2,36 = 4.51, p = 0.018), which describes better CLI performance in the FA group, compared with the F and E groups. Observational practice that includes errors improves the global performance aspects of clinical skill learning as long as learners are given confirmation that what they are observing is errorful. These findings provide a refined perspective on the optimal organisation of skill education programmes that combine physical and observational practice

  15. Medicare payment data for spine reimbursement; important but flawed data for evaluating utilization of resources.

    Science.gov (United States)

    Menger, Richard P; Wolf, Michael E; Kukreja, Sunil; Sin, Anthony; Nanda, Anil

    2015-01-01

    Medicare data showing physician-specific reimbursement for 2012 were recently made public in the mainstream media. Given the ongoing interest in containing healthcare costs, we analyze these data in the context of the delivery of spinal surgery. Demographics of 206 leading surgeons were extracted including state, geographic area, residency training program, fellowship training, and academic affiliation. Using current procedural terminology (CPT) codes, information was evaluated regarding the number of lumbar laminectomies, lumbar fusions, add-on laminectomy levels, and anterior cervical fusions reimbursed by Medicare in 2012. In 2012 Medicare reimbursed the average neurosurgeon slightly more than an orthopedic surgeon for all procedures ($142,075 vs. $110,920), but this was not found to be statistically significant (P = 0.218). Orthopedic surgeons had a statistical trend illustrating increased reimbursement for lumbar fusions specifically, $1187 versus $1073 (P = 0.07). Fellowship trained spinal surgeons also, on average, received more from Medicare ($125,407 vs. $76,551), but again this was not statistically significant (P = 0.112). A surgeon in private practice, on average, was reimbursed $137,495 while their academic counterparts were reimbursed $103,144 (P = 0.127). Surgeons performing cervical fusions in the Centers for Disease Control West Region did receive statistically significantly less reimbursement for that procedure then those surgeons in other parts of the country (P = 0.015). Surgeons in the West were reimbursed on average $849 for CPT code 22,551 while those in the Midwest received $1475 per procedure. Medicare reimbursement data are fundamentally flawed in determining healthcare expenditure as it shows a bias toward delivery of care in specific patient demographics. However, neurosurgeons, not just policy makers, must take ownership to analyze, investigate, and interpret these data as it will affect healthcare reimbursement and delivery moving

  16. Development of a probe for inner profile measurement and flaw detection

    Science.gov (United States)

    Yoshizawa, Toru; Wakayama, Toshitaka; Kamakura, Yoshihisa

    2011-08-01

    It is one of the important necessities to precisely measure the inner diameter and/or the inner profile of pipes, tubes and other objects similar in shape. Especially in mechanical engineering field, there are many requests from automobile industry because the inner surface of engine blocks and other die casts are strongly required to be inspected and measured by non-contact methods (not by the naked eyes inspection using a borescope). If the inner diameter is large enough like water pipes or drain pipes, complicated and large equipment may be applicable. However, small pipes with a diameter ranging from 10mm to 100mm are difficult to be inspected by such a large instrument as is used for sewers inspection. And we have proposed an instrument which has no moving elements such as a rotating mirror or a prism for scanning a beam. Our measurement method is based on optical sectioning using triangulation. This optically sectioned profile of an inner wall of pipe-like objects is analyzed to produce numerical data of inner diameter or profile. Here, we report recent development of the principle and applications of the optical instrument with a simple and compact configuration. In addition to profile measurement, we found flaws and defects on the inner wall were also detected by using the similar principle. Up to now, we have developed probes with the diameter of 8mm to 25mm for small size objects and another probe (80 mm in diameter) for such a larger container with the dimensional size of 600mm.

  17. Swedish-Norwegian tradable green certificates: Scheme design flaws and perceived investment barriers

    International Nuclear Information System (INIS)

    Linnerud, Kristin; Simonsen, Morten

    2017-01-01

    The EU Commission recommends using market-based support schemes for renewable-electricity projects. One example is the Swedish-Norwegian tradable green certificate scheme. We examine whether design features in the Norwegian part of this scheme, specifically, the scheme's short duration and the way it is to be abruptly terminated, contribute to investors' perceptions of barriers. We apply econometric techniques on primary data collected in two surveys of Norwegian investors in hydropower, and we use real options theory to predict and interpret investors' responses. We show that: (1) immediately after the scheme was introduced, investors are eager to lock in future subsidies by investing immediately and concerned with factors that may delay the completion of their projects; (2) as the certificate deadline neared, investors have become increasingly pessimistic and concerned with economic and risk barriers. Investors in big hydropower plants with regulation reservoirs are particularly concerned with the risk of not completing their projects in time to gain the right to sell certificates. These findings are consistent with the predicted responses to the scheme design derived from real options theory. In contrast to earlier studies, we find no difference in responses to the scheme design across investor types. - Highlights: • The Swedish-Norwegian tradable green certificate scheme is intended to promote cost-efficiency. • We examine the optimism about and barriers against investing in new hydropower projects in Norway. • We find that scheme design may have contributed to barriers against Norwegian hydropower projects. • Thus, scheme design flaws may have prevented the scheme from working as intended. • These findings are consistent with real options theory predictions.

  18. Development of a multi-beam laser ultrasonic inspection system and its application on flaw sizing

    International Nuclear Information System (INIS)

    Chivavibul, Pornthep; Lin, Shan; Fukutomi, Hiroyuki; Higuchi, Sadao; Ogata, Takashi; Fukuchi, Tetsuo

    2006-01-01

    Laser ultrasonic technique is a powerful tool for non-contact, nondestructive testing of materials. It is expected to apply to where the conventional ultrasonic technique is not applicable. However, this technique suffers from low sensitivity. In order to overcome this shortcoming, a multi-beam laser ultrasonic system was developed to increase signal-to-noise ratio (SNR) and steer beam direction. The system consisted of eight pulsed Nd:YAG lasers used for ultrasonic generation, and a two-wave mixing interferometer with a long-pulsed Nd:YAG used for ultrasonic detection. Spatial and temporal control of the firing of the individual lasers permitted the generation of both phased array single pulse and narrow-band ultrasonic signals. The performance of developed system was verified using aluminum specimens with the wave generation in a slight ablation mode. A significant increase in sensitivity was obtained, with an increase in signal amplitude with no change in noise level. In the narrow band case, tone bursts were successfully generated in both surface and bulk waves. Beam steering of bulk waves was also performed, and the directivity was confirmed by visualization using a conventional transducer. The developed system was applied to flaw sizing using two techniques: shadow and short-path of diffraction (SPOD), using aluminum specimens with 2-mm, 5-mm, 8-mm slit depths. The shadow technique accurately measured the 5- and 8-mm slits, but not the 2-mm slit. The SPOD technique, carried out using a 5-MHz normal longitudinal transducer as a detector instead of TWN interferometer, accurately measured slits in all specimens with an error less than 0.5 mm. (author)

  19. Application of radiotracer method for tightness control and leakage localization in industrial objects

    International Nuclear Information System (INIS)

    Kras, J; Walis, L.; Myczkowski, S.

    2001-01-01

    Application of 82 Br in the form of gaseous CH 3 Br for tightness control and leakage localization in large industrial apparatus as chemical reactors, columns, vessels, pipelines etc. has been presented. The tracer has been prepared at the place of measurements in a specially designed mobile chemical reactor. The paper presents different variants of the method convenient for: tightness control of underground pipelines, leakage control of technological objects working in chemical and petrochemical industry, tightness control of large metal vessels localized underground and on surface. The radiometric devices used in mentioned variants have ben performed as well

  20. Tight Money, Real Interest Rates, and Inflation in Sub-Saharan Africa

    OpenAIRE

    Edward F. Buffie

    2003-01-01

    The consequences of tight monetary policy are analyzed in an optimizing currency-substitution model of a small, open economy that operates under an open capital account and a flexible exchange rate. There is a reasonably good fit between the dynamics generated by the model and the stylized facts in the tight-money episodes that occurred in Kenya in 1993 and Nigeria in 1989-91. The study's results shed light on two issues: why tight money has provoked stupendous increases in inflation and the ...

  1. Program to develop acoustic emission: flaw relationship for inservice monitoring of nuclear pressure vessels. Progress report No. 1, July 1, 1976--February 1, 1977

    International Nuclear Information System (INIS)

    Hutton, P.H.; Schwenk, E.B.

    1977-03-01

    This is a laboratory research program to characterize acoustic emission (AE) from flaw growth and noise from innocuous sources in A533B Class 1 pressure vessel steel. The objectives are: characterize AE from a limited range of defects and material property conditions of concern to reactor pressure vessel integrity; characterize AE from innocuous sources (including defects); develop criteria for distinguishing significant flaws from innocuous sources; and develop an AE flaw damage model to serve as a basis for relating in-service AE to pressure vessel integrity. The purpose of the program is to build an experimental evaluation of the feasibility of detecting and analyzing flaw growth in reactor pressure boundaries by continuously monitoring for AE. A detailed program plan in the form of an analysis-before-test document has been prepared and approved

  2. Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight, so ambient light will increase the noise and may even damage them.

    CERN Multimedia

    Nooren, G.

    2004-01-01

    Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight , so ambient light will increase the noise and may even damage them.

  3. Closed string field theory

    International Nuclear Information System (INIS)

    Strominger, A.

    1987-01-01

    A gauge invariant cubic action describing bosonic closed string field theory is constructed. The gauge symmetries include local spacetime diffeomorphisms. The conventional closed string spectrum and trilinear couplings are reproduced after spontaneous symmetry breaking. The action S is constructed from the usual ''open string'' field of ghost number minus one half. It is given by the associator of the string field product which is non-vanishing because of associativity anomalies. S does not describe open string propagation because open string states associate and can thereby be shifted away. A field theory of closed and open strings can be obtained by adding to S the cubic open string action. (orig.)

  4. Pipe closing device

    International Nuclear Information System (INIS)

    Klahn, F.C.; Nolan, J.H.; Wills, C.

    1979-01-01

    The closing device closes the upper end of a support tube for monitoring samples. It meshes with the upper connecting piece of the monitorung sample capsule, and loads the capsule within the bore of the support tube, so that it is fixed but can be released. The closing device consists of an interlocking component with a chamber and several ratchets which hang down. The interlocking component surrounds the actuating component for positioning the ratchets. The interlocking and actuating components are movable axially relative to each other. (DG) [de

  5. Examination of parameters affecting overload fracture behavior of flaw-tip hydrides in Zr-2.5Nb pressure tubes in Candu reactors

    International Nuclear Information System (INIS)

    Cui, J.; Shek, G.K.; Wang, Z.R.

    2007-01-01

    Service-induced flaws in Zr-2.5Nb alloy pressure tubes in Candu (Canada Deuterium Uranium Reactors) nuclear reactors are susceptible to a crack initiation and growth mechanism known as Delayed Hydride Cracking (DHC), which is a repetitive process that involves hydrogen diffusion, hydride precipitation, growth and fracture of a hydride region at the flaw-tip under a constant load. Crack initiation may also occur under another loading condition when the hydride region is subjected to an overload. An overload occurs when the hydride region at the flaw tip is loaded to a stress higher than that at which this region is formed such as when the reactor experiences a transient pressure higher than the normal operating pressure where the hydride region is formed. Flaw disposition requires justification that the hydride region overload will not fracture the hydride region, and initiate DHC. In this work, monotonically increasing load experiments were performed on unirradiated Zr-2.5Nb pressure tube specimens containing simulated debris frets (V-notch) and bearing pad frets (BPF, U-shape notch) to examine overload fracture behavior of flaw-tip hydrides formed under hydride ratcheting conditions. Hydride cracking in the overload tests was detected by the acoustic emission technique and confirmed by post-test metallurgical examination. Test results indicate that the resistance to overload fracture is affected by a number of parameters including hydride formation stress, flaw shape (V-notch vs. BPF) and flaw radius (0.015 mm vs. 0.1 mm). The notch-tip hydride morphologies were examined by optical microscopy and scanning electron microscopy (SEM) which show that they are affected by the hydride formation conditions, resulting in different overload fracture resistance. Finite element stress analyses were also performed to obtain flaw-tip stress distributions for interpretation of the test results. (authors)

  6. Is stellar multiplicity universal? Tight stellar binaries in the Orion Nebula Cluster

    Science.gov (United States)

    Duchêne, Gaspard; Lacour, S.; Moraux, E.; Goodwin, S.; Bouvier, J.

    2018-05-01

    We present a survey for the tightest visual binaries among 0.3-2 M⊙ members the Orion Nebula Cluster (ONC). Among 42 targets, we discovered 13 new 0{^''.}025-0{^''.}15 companions. Accounting for the Branch bias, we find a companion star fraction (CSF) in the 10-60 au range of 21^{+8}_{-5}%, consistent with that observed in other star-forming regions (SFRs) and twice as high as among field stars; this excess is found with a high level of confidence. Since our sample is dominated by disk-bearing targets, this indicates that disk disruption by close binaries is inefficient, or has not yet taken place, in the ONC. The resulting separation distribution in the ONC drops sharply outside 60 au. These findings are consistent with a scenario in which the initial multiplicity properties, set by the star formation process itself, are identical in the ONC and in other SFRs and subsequently altered by the cluster's dynamical evolution. This implies that the fragmentation process does not depend on the global properties of a molecular cloud, but on the local properties of prestellar cores, and that the latter are self-regulated to be nearly identical in a wide range of environments. These results, however, raise anew the question of the origin of field stars as the tight binaries we have discovered will not be destroyed as the ONC dissolves into the galactic field. It thus appears that most field stars formed in regions that differ from well-studied SFRs in the Solar neighborhood, possibly due to changes in core fragmentation on Gyr timescales.

  7. A surgical technique for lengthening tight hamstring muscles in patients with low back pain.

    Science.gov (United States)

    Anglès, F G; Manubens, X B; Anglès, F C

    1997-01-01

    An original technique for lengthening primary tight semitendinosus and semimembranosus muscles in their proximal portion is presented. The authors consider that primary shortening of these muscles rebounds on hip biomechanics and on the spine kinematics chain.

  8. PLANET-PLANET SCATTERING LEADS TO TIGHTLY PACKED PLANETARY SYSTEMS

    International Nuclear Information System (INIS)

    Raymond, Sean N.; Barnes, Rory; Veras, Dimitri; Armitage, Philip J.; Gorelick, Noel; Greenberg, Richard

    2009-01-01

    The known extrasolar multiple-planet systems share a surprising dynamical attribute: they cluster just beyond the Hill stability boundary. Here we show that the planet-planet scattering model, which naturally explains the observed exoplanet eccentricity distribution, can reproduce the observed distribution of dynamical configurations. We calculated how each of our scattered systems would appear over an appropriate range of viewing geometries; as Hill stability is weakly dependent on the masses, the mass-inclination degeneracy does not significantly affect our results. We consider a wide range of initial planetary mass distributions and find that some are poor fits to the observed systems. In fact, many of our scattering experiments overproduce systems very close to the stability boundary. The distribution of dynamical configurations of two-planet systems may provide better discrimination between scattering models than the distribution of eccentricity. Our results imply that, at least in their inner regions which are weakly affected by gas or planetesimal disks, planetary systems should be 'packed', with no large gaps between planets.

  9. Wounds caused by tight contact with the barrel-cylinder gap of revolvers.

    Science.gov (United States)

    Rogers, D R

    1984-06-01

    A case is presented in which the recognition of a tight cylinder gap contact wound was crucial. Experiments were carried out to reproduce the wound which was noted on the hand of a robbery suspect. Tight contact with the cylinder gap of a revolver produces a characteristic, readily recognizable wound. It is characterized by an L-shaped pattern of powder residue. Along one axis a searing burn may occur which may be deep and which may lead to significant tissue destruction.

  10. Adaptive tight frame based medical image reconstruction: a proof-of-concept study for computed tomography

    International Nuclear Information System (INIS)

    Zhou, Weifeng; Cai, Jian-Feng; Gao, Hao

    2013-01-01

    A popular approach for medical image reconstruction has been through the sparsity regularization, assuming the targeted image can be well approximated by sparse coefficients under some properly designed system. The wavelet tight frame is such a widely used system due to its capability for sparsely approximating piecewise-smooth functions, such as medical images. However, using a fixed system may not always be optimal for reconstructing a variety of diversified images. Recently, the method based on the adaptive over-complete dictionary that is specific to structures of the targeted images has demonstrated its superiority for image processing. This work is to develop the adaptive wavelet tight frame method image reconstruction. The proposed scheme first constructs the adaptive wavelet tight frame that is task specific, and then reconstructs the image of interest by solving an l 1 -regularized minimization problem using the constructed adaptive tight frame system. The proof-of-concept study is performed for computed tomography (CT), and the simulation results suggest that the adaptive tight frame method improves the reconstructed CT image quality from the traditional tight frame method. (paper)

  11. Active stretching for lower extremity muscle tightness in pediatric patients with lumbar spondylolysis.

    Science.gov (United States)

    Sato, Masahiro; Mase, Yasuyoshi; Sairyo, Koichi

    2017-01-01

    It was reported that hamstring muscle tightness may increase mechanical loading on the lumbar spine. Therefore, we attempt to decrease tightness in the leg muscles in pediatric patients. Forty-six pediatric patients with spondylolysis underwent rehabilitation. We applied active stretching to the hamstrings, quadriceps, and triceps surae. Tightness in each muscle was graded as good, fair, or poor. We educated each patient on how to perform active stretching at home. They were re-evaluated for muscle tightness 2 months later. Tightness at baseline and after 2 months was as follows: for the hamstrings, good in 3 patients, fair in 9, and poor in 34 and significant improved after 2 months (p<0.05), with improvement by least 1 grade seen in 86% of patients with fair or poor at baseline; for the quadriceps, 7, 3, and 30 patients had good, fair and poor, with significant improvements in 72% (p<0.05). For the triceps surae, 6, 3 and 10 patients had good, fair and poor, which improved significantly (p<0.05). Home-based active stretching was effective for relieving muscle tightness in the leg in a pediatric population. Adolescent athletes should perform such exercise to maintain flexibility and prevent lumbar disorders. J. Med. Invest. 64: 136-139, February, 2017.

  12. Injuries and disorders among young ice skaters: relationship with generalized joint laxity and tightness

    Directory of Open Access Journals (Sweden)

    Okamura S

    2014-08-01

    Full Text Available Shinobu Okamura,1 Naoki Wada,1 Masayuki Tazawa,1 Makoto Sohmiya,1 Yoko Ibe,1 Toru Shimizu,1 Shigeru Usuda,2 Kenji Shirakura1 1Department of Rehabilitation Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan; 2Department of Physical Therapy, Gunma University School of Health Science, Maebashi, Gunma, Japan Abstract: This study retrospectively investigated 192 teenage speed and figure skaters with prior injuries documented by an athletes’ questionnaire, who underwent a physical examination to assess their muscle tightness and generalized joint laxity. In all athletes, the degree of muscle tightness and joint laxity were measured by a standardized physical examination. A descriptive report of the types of injuries showed a predominance of fractures, ligament injuries, enthesitis, and lower back pain. Approximately 5% of all skaters tested positive for tightness, while 25.8% of figure skaters and 15.2% of speed skaters had generalized ligamentous laxity. Statistical testing showed an association between ankle sprains and muscle tightness, and an association between knee enthesitis and muscle tightness in skating athletes. There was also an association between lower back pain and generalized joint laxity, which held true only for the male skaters. Keywords: sports injury, skating, junior athlete, tightness, joint laxity, medical checkup

  13. Performance Improvement of Receivers Based on Ultra-Tight Integration in GNSS-Challenged Environments

    Directory of Open Access Journals (Sweden)

    Feng Qin

    2013-12-01

    Full Text Available Ultra-tight integration was first proposed by Abbott in 2003 with the purpose of integrating a global navigation satellite system (GNSS and an inertial navigation system (INS. This technology can improve the tracking performances of a receiver by reconfiguring the tracking loops in GNSS-challenged environments. In this paper, the models of all error sources known to date in the phase lock loops (PLLs of a standard receiver and an ultra-tightly integrated GNSS/INS receiver are built, respectively. Based on these models, the tracking performances of the two receivers are compared to verify the improvement due to the ultra-tight integration. Meanwhile, the PLL error distributions of the two receivers are also depicted to analyze the error changes of the tracking loops. These results show that the tracking error is significantly reduced in the ultra-tightly integrated GNSS/INS receiver since the receiver’s dynamics are estimated and compensated by an INS. Moreover, the mathematical relationship between the tracking performances of the ultra-tightly integrated GNSS/INS receiver and the quality of the selected inertial measurement unit (IMU is derived from the error models and proved by the error comparisons of four ultra-tightly integrated GNSS/INS receivers aided by different grade IMUs.

  14. Leakage detecting method and device for water tight vessel of wet-type container apparatus

    International Nuclear Information System (INIS)

    Tanaka, Yoshimi.

    1995-01-01

    The present invention provides a method of and a device for detecting leakage of a water tight vessel of a wet-type container apparatus for containing a reactor pressure vessel while immersing it water in a reactor container. Namely, in the wet-type container apparatus, the periphery of the pressure vessel is coated with a heat insulation material and the periphery of the heat insulation material is coated with a water tight vessel. The water tight vessel is immersed under water in the reactor container. As a method of detecting leakage of the wet-type container apparatus, gases mixed with helium are supplied into the water tight vessel at a pressure higher than the inner pressure of the reactor container at a lowest position of the reactor pressure vessel. A water level in the reactor container is determined so as to form a space at the top portion of the inside of the reactor container. The helium at the top portion is detected to monitor the leakage of the water tight vessel. With such procedures, even if the water tight vessel is ruptured at any position, helium mixed to the gases is released to water in the reactor container and rise up to the top space and detected by a helium leakage detection device. (I.S.)

  15. Current and historical perspectives on methodological flaws in processing umbilical cord blood.

    Science.gov (United States)

    Mehrishi, J N

    2013-11-01

    Umbilical cord blood (UCB) hematopoietic stem cells (HSC-CD34+) are valuable for treating malignant or nonmalignant disease. Processing UCB by HESPAN-6% and anti-CD34-Miltenyi particles provides insufficient cells for treating adults. Physicochemical-electrokinetic studies on UCB-mononuclear cells (MNCs) under conditions of delayed processing, ice or very low temperatures, and some cell separation media identified artifacts introduced by procedures. Adsorption of biomaterials from cell damage by temperature, degradation products after using enzymes, harsh reagents, dithiothreitol, and HESPAN affect cell properties and distribution. Miltenyi particles internalized by cells could release iron that accumulating in liver or spleen would then risk toxicity. Summary topics included the effects of temperature, HESPAN (fast sedimenting agent), glycoproteases, DNase, and dithiothreitol risk affecting cell receptors in recognition, "homing," leading to possible unintended iatrogenic bioeffects should such cells be transfused into humans. The loss of undetectable and uncaptured low CD34 antigen-bearing cells by Miltenyi particles seems to occur when the current methods of isolation of CD34+ cells and other cells are critically assessed. The purpose here is to highlight and suggest avoiding the procedural flaws involved. Preventing ice temperatures avoids ice-damaged platelets releasing biomaterials that are adsorbed on cells altering UBC-MNCs/HSC properties and cell loss. Omitting the positive selection with antibody-linked Miltenyi particles obviates the use of harsh reagents to release the cells. Internalized Miltenyi particles are a toxicity hazard that needs investigations. Achieving approximately 5% yields of CD34+ cells (153 × 10(5) /110 mL cord-placenta blood) is a major advance holding great promise, for the first time increasing the prospect of stem cell therapy of 70-kg adults, using a single UCB donation (with dose of 1.5 × 10(5) cells/kg) and

  16. Minding the close relationship.

    Science.gov (United States)

    Harvey, J H; Omarzu, J

    1997-01-01

    In this theoretical analysis, we argue that a process referred to as minding is essential for a couple to feel mutually close and satisfied in a close relationship over a long period Minding represents a package of mutual self-disclosure, other forms of goal-oriented behavior aimed at facilitating the relationship, and attributions about self's and other's motivations, intentions, and Mort in the relationship. Self-disclosure and attribution activities in minding are aimed at getting to know the other, trying to understand the other's motivations and deeper disposition as they pertain to the relationship, and showing respect and acceptance for knowledge gained about other. We link the concept of minding to other major ideas and literatures about how couples achieve closeness: self-disclosure and social penetration, intimacy, empathy and empathic accuracy, and love and self-expansion. We argue that the minding process articulated here has not previously been delineated and that it is a useful composite notion about essential steps in bonding among humans. We also argue that the minding concept stretches our understanding of the interface of attribution and close relationships. We present research possibilities and implications and consider possible alternative positions and counter arguments about the merits of the minding idea for close relationship satisfaction.

  17. Close binary stars

    International Nuclear Information System (INIS)

    Larsson-Leander, G.

    1979-01-01

    Studies of close binary stars are being persued more vigorously than ever, with about 3000 research papers and notes pertaining to the field being published during the triennium 1976-1978. Many major advances and spectacular discoveries were made, mostly due to increased observational efficiency and precision, especially in the X-ray, radio, and ultraviolet domains. Progress reports are presented in the following areas: observational techniques, methods of analyzing light curves, observational data, physical data, structure and models of close binaries, statistical investigations, and origin and evolution of close binaries. Reports from the Coordinates Programs Committee, the Committee for Extra-Terrestrial Observations and the Working Group on RS CVn binaries are included. (Auth./C.F.)

  18. Crack growth of throughwall flaw in Alloy 600 tube during leak testing

    International Nuclear Information System (INIS)

    Bahn, Chi Bum; Majumdar, Saurin

    2015-01-01

    Graphical abstract: - Highlights: • A series of leak testing was conducted at a constant pressure and room temperature. • The time-dependent increase in the leak rate was observed. • The fractography revealed slip offsets and crystallographic facets. • Time-dependent plasticity at the crack tip caused the slip offsets. • Fatigue by jet/structure interaction caused the crystallographic facets. - Abstract: We examined the issue of whether crack growth in a full thickness material can occur in a leaking crack. A series of leak tests was conducted at a room temperature and constant pressure (17.3 MPa) with Alloy 600 tube specimens containing a tight rectangular throughwall axial fatigue crack. To exclude a potential pulsation effect by a high pressure pump, the test water was pressurized by using high pressure nitrogen gas. Fractography showed that crack growth in the full thickness material can occur in the leaking crack by two mechanisms: time-dependent plasticity at the crack tip and fatigue induced by jet/structure interaction. The threshold leak rate at which the jet/structure interaction was triggered was between 1.3 and 3.3 L/min for the specific heat of the Alloy 600 tube tested

  19. Thermodynamic studies of a series of homologous HIV-1 TAR RNA ligands reveal that loose binders are stronger Tat competitors than tight ones.

    Science.gov (United States)

    Pascale, Lise; Azoulay, Stéphane; Di Giorgio, Audrey; Zenacker, Laura; Gaysinski, Marc; Clayette, Pascal; Patino, Nadia

    2013-06-01

    RNA is a major drug target, but the design of small molecules that modulate RNA function remains a great challenge. In this context, a series of structurally homologous 'polyamide amino acids' (PAA) was studied as HIV-1 trans-activating response (TAR) RNA ligands. An extensive thermodynamic study revealed the occurence of an enthalpy-entropy compensation phenomenon resulting in very close TAR affinities for all PAA. However, their binding modes and their ability to compete with the Tat fragment strongly differ according to their structure. Surprisingly, PAA that form loose complexes with TAR were shown to be stronger Tat competitors than those forming tight ones, and thermal denaturation studies demonstrated that loose complexes are more stable than tight ones. This could be correlated to the fact that loose and tight ligands induce distinct RNA conformational changes as revealed by circular dichroism experiments, although nuclear magnetic resonance (NMR) experiments showed that the TAR binding site is the same in all cases. Finally, some loose PAA also display promising inhibitory activities on HIV-infected cells. Altogether, these results lead to a better understanding of RNA interaction modes that could be very useful for devising new ligands of relevant RNA targets.

  20. Real time flaw detection and characterization in tube through partial least squares and SVR: Application to eddy current testing

    Science.gov (United States)

    Ahmed, Shamim; Miorelli, Roberto; Calmon, Pierre; Anselmi, Nicola; Salucci, Marco

    2018-04-01

    This paper describes Learning-By-Examples (LBE) technique for performing quasi real time flaw localization and characterization within a conductive tube based on Eddy Current Testing (ECT) signals. Within the framework of LBE, the combination of full-factorial (i.e., GRID) sampling and Partial Least Squares (PLS) feature extraction (i.e., GRID-PLS) techniques are applied for generating a suitable training set in offine phase. Support Vector Regression (SVR) is utilized for model development and inversion during offine and online phases, respectively. The performance and robustness of the proposed GIRD-PLS/SVR strategy on noisy test set is evaluated and compared with standard GRID/SVR approach.

  1. Identification of Flaws Responsible for Crack Initiation and Micromechanisms of Slow Crack Growth in the Delayed Fracture of Alumina.

    Science.gov (United States)

    1982-02-01

    A-"AIS012 CALIFORNIA UNdIV LOS ANSELES DEPT OF MATERIALS SCIEN--ETC F/S 11/6 IDENTIFICATION OF FLAWS RESPONSIBLE FOR CRACK INITIATION AM %I--ETC(U...Sines and Adams . 71 It might be thought that other compressive loading devices could serve the same purpoee. For example, a spherical joint instead of the...compressive strength can be 18 times the tensile strength as reported by Adams . 92 This is because the established criteria are damage criter- ia, not

  2. A general approach to flaw simulation in castings by superimposing projections of 3D models onto real X-ray images

    International Nuclear Information System (INIS)

    Hahn, D.; Mery, D.

    2003-01-01

    In order to evaluate the sensitivity of defect inspection systems, it is convenient to examine simulated data. This gives the possibility to tune the parameters of the inspection method and to test the performance of the system in critical cases. In this paper, a practical method for the simulation of defects in radioscopic images of aluminium castings is presented. The approach simulates only the flaws and not the whole radioscopic image of the object under test. A 3D mesh is used to model a flaw with complex geometry, which is projected and superimposed onto real radioscopic images of a homogeneous object according to the exponential attenuation law for X- rays. The new grey value of a pixel, where the 3D flaw is projected, depends only on four parameters: (a) the grey value of the original X-ray image without flaw; (b) the linear absorption coefficient of the examined material; (c) the maximal thickness observable in the radioscopic image; and (d) the length of the intersection of the 3D flaw with the modelled X-ray beam, that is projected into the pixel. A simulation of a complex flaw modelled as a 3D mesh can be performed in any position of the castings by using the algorithm described in this paper. This allows the evaluation of the performance of defect inspection systems in cases where the detection is known to be difficult. In this paper, we show experimental results on real X-ray images of aluminium wheels, in which 3D flaws like blowholes, cracks and inclusions are simulated

  3. Gas leak tightness of SiC/SiC composites at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hayasaka, Daisuke, E-mail: hayasaka@oasis.muroran-it.ac.jp [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Park, Joon-Soo. [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kishimoto, Hirotatsu [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kohyama, Akira [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan)

    2016-11-01

    Highlights: • NITE-SiC/SiC has extremely densified microstructure compared with other SiC/SiC composite like CVI. • Excellent helium and hydrogen gas-leak tightness of SiC/SiC composites by DEMO-NITE method from prototype industrialization production line was presented. • The excellence against stainless steel and Zircaloy at elevated temperature, together with generic excellent properties of SiC will be inevitable for innovative blanket and divertors for DEMO- and power- fusion reactors. - Abstract: SiC/SiC composite materials are attractive candidates for high heat flux components and blanket of fusion reactor, mainly due to their high temperature properties, radiation damage tolerance and low induced radioactivity. One of the challenges for SiC/SiC application in fusion reactors is to satisfy sufficient gas leak tightness of hydrogen and helium isotopes. Although many efforts have been carried-out, SiC/SiC composites by conventional processes have not been successful to satisfy the requirements, except SiC/SiC composites by NITE-methods. Toward the early realization of SiC/SiC components into fusion reactor systems process development of NITE-process has been continued. Followed to the brief introduction of recently developed DEMO-NITE process, baseline properties and hydrogen and helium gas leak tightness is presented. SiC/SiC claddings with 10 mm in diameter and 1 mm in wall thickness are tested by gas leak tightness system developed. The leak tightness measurements are done room temperature to 400 °C. Excellent gas leak tightness equivalent or superior to Zircaloy claddings for light water fission reactors is confirmed. The excellent gas leak tightness suggests nearly perfect suppression of large gas leak path in DEMO-NITE SiC/SiC.

  4. NRC closing remarks

    International Nuclear Information System (INIS)

    Coffman, F.

    1994-01-01

    This section contains the edited transcript of the NRC closing remarks made by Mr. Franklin Coffman (Chief, Human Factors Branch, Office of Nuclear Regulatory Research) and Dr. Cecil Thomas (Deputy Director, Division of Reactor Controls and Human Factors, Office of Nuclear Reactor Regulation). This editing consisted of minimal editing to correct grammar and remove extraneous references to microphone volume, etc

  5. Comments on "A Closed-Form Solution to Tensor Voting: Theory and Applications".

    Science.gov (United States)

    Maggiori, Emmanuel; Lotito, Pablo; Manterola, Hugo Luis; del Fresno, Mariana

    2014-12-01

    We comment on a paper that describes a closed-form formulation to Tensor Voting, a technique to perceptually group clouds of points, usually applied to infer features in images. The authors proved an analytic solution to the technique, a highly relevant contribution considering that the original formulation required numerical integration, a time-consuming task. Their work constitutes the first closed-form expression for the Tensor Voting framework. In this work we first observe that the proposed formulation leads to unexpected results which do not satisfy the constraints for a Tensor Voting output, hence they cannot be interpreted. Given that the closed-form expression is said to be an analytic equivalent solution, unexpected outputs should not be encountered unless there are flaws in the proof. We analyzed the underlying math to find which were the causes of these unexpected results. In this commentary we show that their proposal does not in fact provide a proper analytic solution to Tensor Voting and we indicate the flaws in the proof.

  6. Production of Natural Gas and Fluid Flow in Tight Sand Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Maria Cecilia Bravo

    2006-06-30

    This document reports progress of this research effort in identifying relationships and defining dependencies between macroscopic reservoir parameters strongly affected by microscopic flow dynamics and production well performance in tight gas sand reservoirs. These dependencies are investigated by identifying the main transport mechanisms at the pore scale that should affect fluids flow at the reservoir scale. A critical review of commercial reservoir simulators, used to predict tight sand gas reservoir, revealed that many are poor when used to model fluid flow through tight reservoirs. Conventional simulators ignore altogether or model incorrectly certain phenomena such as, Knudsen diffusion, electro-kinetic effects, ordinary diffusion mechanisms and water vaporization. We studied the effect of Knudsen's number in Klinkenberg's equation and evaluated the effect of different flow regimes on Klinkenberg's parameter b. We developed a model capable of explaining the pressure dependence of this parameter that has been experimentally observed, but not explained in the conventional formalisms. We demonstrated the relevance of this, so far ignored effect, in tight sands reservoir modeling. A 2-D numerical simulator based on equations that capture the above mentioned phenomena was developed. Dynamic implications of new equations are comprehensively discussed in our work and their relative contribution to the flow rate is evaluated. We performed several simulation sensitivity studies that evidenced that, in general terms, our formalism should be implemented in order to get more reliable tight sands gas reservoirs' predictions.

  7. Tight junction-associated MARVEL proteins marveld3, tricellulin, and occludin have distinct but overlapping functions.

    Science.gov (United States)

    Raleigh, David R; Marchiando, Amanda M; Zhang, Yong; Shen, Le; Sasaki, Hiroyuki; Wang, Yingmin; Long, Manyuan; Turner, Jerrold R

    2010-04-01

    In vitro studies have demonstrated that occludin and tricellulin are important for tight junction barrier function, but in vivo data suggest that loss of these proteins can be overcome. The presence of a heretofore unknown, yet related, protein could explain these observations. Here, we report marvelD3, a novel tight junction protein that, like occludin and tricellulin, contains a conserved four-transmembrane MARVEL (MAL and related proteins for vesicle trafficking and membrane link) domain. Phylogenetic tree reconstruction; analysis of RNA and protein tissue distribution; immunofluorescent and electron microscopic examination of subcellular localization; characterization of intracellular trafficking, protein interactions, dynamic behavior, and siRNA knockdown effects; and description of remodeling after in vivo immune activation show that marvelD3, occludin, and tricellulin have distinct but overlapping functions at the tight junction. Although marvelD3 is able to partially compensate for occludin or tricellulin loss, it cannot fully restore function. We conclude that marvelD3, occludin, and tricellulin define the tight junction-associated MARVEL protein family. The data further suggest that these proteins are best considered as a group with both redundant and unique contributions to epithelial function and tight junction regulation.

  8. Flaw preparations for HSST program vessel fracture mechanics testing: mechanical-cyclic pumping and electron-beam weld-hydrogen-charge cracking schemes

    International Nuclear Information System (INIS)

    Holz, P.P.

    1980-06-01

    The purpose of the document is to present schemes for flaw preparations in heavy section steel. The ability of investigators to grow representative sharp cracks of known size, location, and orientation is basic to representative field testing to determine data for potential flaw propagation, fracture behavior, and margin against fracture for high-pressure-, high-temperature-service steel vessels subjected to increasing pressurization and/or thermal shock. Gaging for analytical stress and strain procedures and ultrasonic and acoustic emission instrumentation can then be applied to monitor the vessel during testing and to study crack growth. This report presents flaw preparations for HSST fracture mechanics testing. Cracks were grown by two techniques: (1) a mechanical method wherein a premachined notch was sharpened by pressurization and (2) a method combining electron-beam welds and hydrogen charging to crack the chill zone of a rapidly placed autogenous weld. The mechanical method produces a naturally occurring growth shape controlled primarily by the shape of the machined notch; the welding-electrochemical method produces flaws of uniform depth from the surface of a wall or machined notch. Theories, details, discussions, and procedures are covered for both of the flaw-growing schemes

  9. Delayed Hydride Cracking Mechanism in Zirconium Alloys and Technical Requirements for In-Service Evaluation of Zr-2.5Nb Tubes with Flaws

    International Nuclear Information System (INIS)

    Kim, Young Suk

    2007-01-01

    In association with periodic inspection of CANDU nuclear power plant components, Canadian Standards Association issued CSA N285.8 in 2005 as technical requirements for in-service evaluation of zirconium alloy pressure tubes in CANDU reactors. This first version, CSA N285.8 involves procedures for, firstly, the evaluation of pressure tube flaws, secondly, the evaluation of pressure tube to calandria tube contact and, thirdly, the assessment of a reactor core, and material properties and derived quantities. The evaluation of pressure tube flaws includes delayed hydride cracking evaluation the procedures of which are stipulated based on the existing delayed hydride cracking models. For example, the evaluation of flaw-tip hydride precipitation during reactor cooldown involves a procedure to calculate the equilibrium hydrogen equivalent concentration in solution at the flaw tip, Htipas follows: Htip=Hfexp[- (VH delta no.)/RT], where Hf is the total bulk hydrogen equivalent concentration, VH partial molar volume of hydrogen in zirconium, δ a difference in hydrostatic stress between the bulk and the crack tip. When Htip ≥TSSP at temperature, then flaw-tip hydride is predicted to precipitate. Eq. (1) suggests that hydrogen concentration at the crack tip would increase due to an work energy given by the difference in the hydrostatic stress

  10. OCA-II, a code for calculating the behavior of 2-D and 3-D surface flaws in a pressure vessel subjected to temperature and pressure transients

    International Nuclear Information System (INIS)

    Ball, D.G.; Drake, J.B.; Cheverton, R.D.; Iskander, S.K.

    1984-02-01

    The OCA-II computer code, like its predecessor OCA-I, performs the thermal, stress, and linear elastic fracture-mechanics analysis for long flaws on the surface of a cylinder that is subjected to thermal and pressure transients. OCA-II represents a revised and expanded version of OCA-I and includes as new features (1) cladding as a discrete region, (2) a finite-element subroutine for calculating the stresses, and (3) the ability to calculate stress intensity factors for certain three-dimensional flaws, for two-dimensional circumferential flaws on the inner surface, and for both axial and circumferential flaws on the outer surface. OCA-I considered only inner-surface flaws. An option is included in OCA-II that permits a search for critical values of fluence or nil-ductility reference temperature corresponding to a specified failure criterion. These and other features of OCA-II are described in the report, which also includes user instructions for the code

  11. A study on the effect of flaw detection probability assumptions on risk reduction achieved by non-destructive inspection

    International Nuclear Information System (INIS)

    Cronvall, O.; Simola, K.; Männistö, I.; Gunnars, J.; Alverlind, L.; Dillström, P.; Gandossi, L.

    2012-01-01

    Leakages and ruptures of piping components lead to reduction or loss of the pressure retaining capability of the system, and thus contribute to the overall risk associated with nuclear power plants. In-service inspection (ISI) aims at verifying that defects are not present in components of the pressure boundary or, if defects are present, ensuring that these are detected before they affect the safe operation of the plant. Reliability estimates of piping are needed e.g., in probabilistic safety assessment (PSA) studies, risk-informed ISI (RI-ISI) applications, and other structural reliability assessments. Probabilistic fracture mechanics models can account for ISI reliability, but a quantitative estimate for the latter is needed. This is normally expressed in terms of probability of detection (POD) curves, which correlate the probability of detecting a flaw with flaw size. A detailed POD curve is often difficult (or practically impossible) to obtain. If sufficient risk reduction can be shown by using simplified (but reasonably conservative) POD estimates, more complex PODs are not needed. This paper summarises the results of a study on the effect of piping inspection reliability assumptions on failure probability using structural reliability models. The main interest was to investigate whether it is justifiable to use a simplified POD curve. Further, the study compared various structural reliability calculation approaches for a set of analysis cases. The results indicate that the use of a simplified POD could be justifiable in RI-ISI applications.

  12. Closing the loop.

    Science.gov (United States)

    Dassau, E; Atlas, E; Phillip, M

    2010-02-01

    The dream of closing the loop is actually the dream of creating an artificial pancreas and freeing the patients from being involved with the care of their own diabetes. Insulin-dependent diabetes (type 1) is a chronic incurable disease which requires constant therapy without the possibility of any 'holidays' or insulin-free days. It means that patients have to inject insulin every day of their life, several times per day, and in order to do it safely they also have to measure their blood glucose levels several times per day. Patients need to plan their meals, their physical activities and their insulin regime - there is only very small room for spontaneous activities. This is why the desire for an artificial pancreas is so strong despite the fact that it will not cure the diabetic patients. Attempts to develop a closed-loop system started in the 1960s but never got to a clinical practical stage of development. In recent years the availability of continuous glucose sensors revived those efforts and stimulated the clinician and researchers to believe that closing the loop might be possible nowadays. Many papers have been published over the years describing several different ideas on how to close the loop. Most of the suggested systems have a sensing arm that measures the blood glucose repeatedly or continuously, an insulin delivery arm that injects insulin upon command and a computer that makes the decisions of when and how much insulin to deliver. The differences between the various published systems in the literature are mainly in their control algorithms. However, there are also differences related to the method and site of glucose measurement and insulin delivery. SC glucose measurements and insulin delivery are the most studied option but other combinations of insulin measurements and glucose delivery including intravascular and intraperitoneal (IP) are explored. We tried to select recent publications that we believe had influenced and inspired people interested

  13. Outer membrane components of the Tad (tight adherence) secreton of Aggregatibacter actinomycetemcomitans.

    Science.gov (United States)

    Clock, Sarah A; Planet, Paul J; Perez, Brenda A; Figurski, David H

    2008-02-01

    Prokaryotic secretion relies on proteins that are widely conserved, including NTPases and secretins, and on proteins that are system specific. The Tad secretion system in Aggregatibacter actinomycetemcomitans is dedicated to the assembly and export of Flp pili, which are needed for tight adherence. Consistent with predictions that RcpA forms the multimeric outer membrane secretion channel (secretin) of the Flp pilus biogenesis apparatus, we observed the RcpA protein in multimers that were stable in the presence of detergent and found that rcpA and its closely related homologs form a novel and distinct subfamily within a well-supported gene phylogeny of the entire secretin gene superfamily. We also found that rcpA-like genes were always linked to Aggregatibacter rcpB- or Caulobacter cpaD-like genes. Using antisera, we determined the localization and gross abundances of conserved (RcpA and TadC) and unique (RcpB, RcpC, and TadD) Tad proteins. The three Rcp proteins (RcpA, RcpB, and RcpC) and TadD, a putative lipoprotein, localized to the bacterial outer membrane. RcpA, RcpC, and TadD were also found in the inner membrane, while TadC localized exclusively to the inner membrane. The RcpA secretin was necessary for wild-type abundances of RcpB and RcpC, and TadC was required for normal levels of all three Rcp proteins. TadC abundance defects were observed in rcpA and rcpC mutants. TadD production was essential for wild-type RcpA and RcpB abundances, and RcpA did not multimerize or localize to the outer membrane without the expression of TadD. These data indicate that membrane proteins TadC and TadD may influence the assembly, transport, and/or function of individual outer membrane Rcp proteins.

  14. Pressure drop characteristics in tight-lattice bundles for reduced-moderation water reactors

    International Nuclear Information System (INIS)

    Tamai, Hidesada; Kureta, Masatoshi; Yoshida, Hiroyuki; Akimoto, Hajime

    2004-01-01

    The reduced-moderation water reactor (RMWR) consists of several distinctive structures; a triangular tight-lattice configuration and a double-flat core. In order to design the RMWR core from the point of view of thermal-hydraulics, an evaluation method on pressure drop characteristics in the rod bundles at the tight-lattice configuration is required. In this study, calculated results by the Martinelli-Nelson's and Hancox's correlations were compared with experimental results in 4 x 5 rod bundles and seven-rod bundles. Consequently, the friction loss in two-phase flows becomes smaller at the tight-lattice configuration with the hydraulic diameter less than about 3 mm. This reason is due to the difference of the configuration between the multi-rod bundle and the circular tube and due to the effect of the small hydraulic diameter on the two-phase multiplier. (author)

  15. LDA+U and tight-binding electronic structure of InN nanowires

    Science.gov (United States)

    Molina-Sánchez, A.; García-Cristóbal, A.; Cantarero, A.; Terentjevs, A.; Cicero, G.

    2010-10-01

    In this paper we employ a combined ab initio and tight-binding approach to obtain the electronic and optical properties of hydrogenated Indium nitride (InN) nanowires. We first discuss InN band structure for the wurtzite structure calculated at the LDA+U level and use this information to extract the parameters needed for an empirical tight-binging implementation. These parameters are then employed to calculate the electronic and optical properties of InN nanowires in a diameter range that would not be affordable by ab initio techniques. The reliability of the large nanowires results is assessed by explicitly comparing the electronic structure of a small diameter wire studied both at LDA+U and tight-binding level.

  16. ARTHROSCOPIC TREATMENT OF ACROMIOCLAVICULAR JOINT DISLOCATION BY TIGHT ROPE TECHNIQUE (ARTHREX®)

    Science.gov (United States)

    GÓmez Vieira, Luis Alfredo; Visco, Adalberto; Daneu Fernandes, Luis Filipe; GÓmez Cordero, Nicolas Gerardo

    2015-01-01

    Presenting the arthroscopic treatment by Tight Rope - Arthrex® system for acute acromioclavicular dislocation and to evaluate results obtained with this procedure. Methods: Between August 2006 and May 2007, 10 shoulders of 10 patients with acute acromioclavicular dislocation were submitted to arthroscopic repair using the Tight Rope - Arthrex® system. Minimum follow-up was 12 months, with a mean of 15 months. Age ranged from 26 to 42, mean 34 years. All patients were male. Radiology evaluation was made by trauma series x-ray. The patients were assisted in the first month weekly and after three months after the procedure. Clinical evaluation was based on the University of California at Los Angeles (UCLA) criteria. Results: All patients were satisfied after the arthroscopic procedure and the mean UCLA score was 32,5. Conclusion: The arthroscopic treatment by Tight Rope – Arthrex® system for acute acromioclavicular dislocation showed to be an efficient technique. PMID:26998453

  17. Modulation of Tight Junction Structure and Function by Kinases and Phosphatases Targeting Occludin

    Directory of Open Access Journals (Sweden)

    Max Johannes Dörfel

    2012-01-01

    Full Text Available Tight junctions (TJs typically represent the most apical contacts in epithelial and endothelial cell layers where they play an essential role in the separation of extracellular or luminal spaces from underlying tissues in the body. Depending on the protein composition, TJs define the barrier characteristics and in addition maintain cell polarity. Two major families of integral membrane proteins form the typical TJ strand network, the tight junction-associated MARVEL protein (TAMP family members occludin, tricellulin, and MarvelD3 as well as a specific set of claudins. Occludin was the first identified member of these tetraspanins and is now widely accepted as a regulator of TJ assembly and function. Therefore, occludin itself has to be tightly regulated. Phosphorylation of occludin appears to be of central importance in this context. Here we want to summarize current knowledge on the kinases and phosphatases directly modifying occludin, and their role in the regulation of TJ structure, function, and dynamics.

  18. Loose and Tight GNSS/INS Integrations: Comparison of Performance Assessed in Real Urban Scenarios.

    Science.gov (United States)

    Falco, Gianluca; Pini, Marco; Marucco, Gianluca

    2017-01-29

    Global Navigation Satellite Systems (GNSSs) remain the principal mean of positioning in many applications and systems, but in several types of environment, the performance of standalone receivers is degraded. Although many works show the benefits of the integration between GNSS and Inertial Navigation Systems (INSs), tightly-coupled architectures are mainly implemented in professional devices and are based on high-grade Inertial Measurement Units (IMUs). This paper investigates the performance improvements enabled by the tight integration, using low-cost sensors and a mass-market GNSS receiver. Performance is assessed through a series of tests carried out in real urban scenarios and is compared against commercial modules, operating in standalone mode or featuring loosely-coupled integrations. The paper describes the developed tight-integration algorithms with a terse mathematical model and assesses their efficacy from a practical perspective.

  19. Two-Finger Tightness: What Is It? Measuring Torque and Reproducibility in a Simulated Model.

    Science.gov (United States)

    Acker, William B; Tai, Bruce L; Belmont, Barry; Shih, Albert J; Irwin, Todd A; Holmes, James R

    2016-05-01

    Residents in training are often directed to insert screws using "two-finger tightness" to impart adequate torque but minimize the chance of a screw stripping in bone. This study seeks to quantify and describe two-finger tightness and to assess the variability of its application by residents in training. Cortical bone was simulated using a polyurethane foam block (30-pcf density) that was prepared with predrilled holes for tightening 3.5 × 14-mm long cortical screws and mounted to a custom-built apparatus on a load cell to capture torque data. Thirty-three residents in training, ranging from the first through fifth years of residency, along with 8 staff members, were directed to tighten 6 screws to two-finger tightness in the test block, and peak torque values were recorded. The participants were blinded to their torque values. Stripping torque (2.73 ± 0.56 N·m) was determined from 36 trials and served as a threshold for failed screw placement. The average torques varied substantially with regard to absolute torque values, thus poorly defining two-finger tightness. Junior residents less consistently reproduced torque compared with other groups (0.29 and 0.32, respectively). These data quantify absolute values of two-finger tightness but demonstrate considerable variability in absolute torque values, percentage of stripping torque, and ability to consistently reproduce given torque levels. Increased years in training are weakly correlated with reproducibility, but experience does not seem to affect absolute torque levels. These results question the usefulness of two-finger tightness as a teaching tool and highlight the need for improvement in resident motor skill training and development within a teaching curriculum. Torque measuring devices may be a useful simulation tools for this purpose.

  20. An improved method for predicting brittleness of rocks via well logs in tight oil reservoirs

    Science.gov (United States)

    Wang, Zhenlin; Sun, Ting; Feng, Cheng; Wang, Wei; Han, Chuang

    2018-06-01

    There can be no industrial oil production in tight oil reservoirs until fracturing is undertaken. Under such conditions, the brittleness of the rocks is a very important factor. However, it has so far been difficult to predict. In this paper, the selected study area is the tight oil reservoirs in Lucaogou formation, Permian, Jimusaer sag, Junggar basin. According to the transformation of dynamic and static rock mechanics parameters and the correction of confining pressure, an improved method is proposed for quantitatively predicting the brittleness of rocks via well logs in tight oil reservoirs. First, 19 typical tight oil core samples are selected in the study area. Their static Young’s modulus, static Poisson’s ratio and petrophysical parameters are measured. In addition, the static brittleness indices of four other tight oil cores are measured under different confining pressure conditions. Second, the dynamic Young’s modulus, Poisson’s ratio and brittleness index are calculated using the compressional and shear wave velocity. With combination of the measured and calculated results, the transformation model of dynamic and static brittleness index is built based on the influence of porosity and clay content. The comparison of the predicted brittleness indices and measured results shows that the model has high accuracy. Third, on the basis of the experimental data under different confining pressure conditions, the amplifying factor of brittleness index is proposed to correct for the influence of confining pressure on the brittleness index. Finally, the above improved models are applied to formation evaluation via well logs. Compared with the results before correction, the results of the improved models agree better with the experimental data, which indicates that the improved models have better application effects. The brittleness index prediction method of tight oil reservoirs is improved in this research. It is of great importance in the optimization of