The influence of interband tunneling on leakage current in manganite/titanate heterojunction

International Nuclear Information System (INIS)

Han Peng; Jia Jinfeng

2008-01-01

The behavior of leakage current at reverse bias in p-La 0.9 Sr 0.1 MnO 3 /n-SrNb 0.01 Ti 0.99 O 3 heterojunction has been theoretically studied by calculating interband tunneling current with various doping densities and temperatures. Our results reveal that the reduction of leakage current with decrease of doping density and increase of temperature originates from properties of interband tunneling

Leakage current reduction of vertical GaN junction barrier Schottky diodes using dual-anode process

Science.gov (United States)

Hayashida, Tetsuro; Nanjo, Takuma; Furukawa, Akihiko; Watahiki, Tatsuro; Yamamuka, Mikio

2018-04-01

The origin of the leakage current of a trench-type vertical GaN diode was discussed. We found that the edge of p-GaN is the main leakage spot. To reduce the reverse leakage current at the edge of p-GaN, a dual-anode process was proposed. As a result, the reverse blocking voltage defined at the leakage current density of 1 mA/cm2 of a vertical GaN junction barrier Schottky (JBS) diode was improved from 780 to 1,190 V, which is the highest value ever reported for vertical GaN Schottky barrier diodes (SBDs).

Compilation of current literature on seals, closures, and leakage for radioactive material packagings

International Nuclear Information System (INIS)

Warrant, M.M.; Ottinger, C.A.

1989-01-01

This report presents an overview of the features that affect the sealing capability of radioactive material packagings currently certified by the US Nuclear Regulatory Commission. The report is based on a review of current literature on seals, closures, and leakage for radioactive material packagings. Federal regulations that relate to the sealing capability of radioactive material packagings, as well as basic equations for leakage calculations and some of the available leakage test procedures are presented. The factors which affect the sealing capability of a closure, including the properties of the sealing surfaces, the gasket material, the closure method and the contents are discussed in qualitative terms. Information on the general properties of both elastomer and metal gasket materials and some specific designs are presented. A summary of the seal material, closure method, and leakage tests for currently certified packagings with large diameter seals is provided. 18 figs., 9 tabs

Leakage current measurement in transformerless PV inverters

DEFF Research Database (Denmark)

Kerekes, Tamas; Sera, Dezso; Mathe, Laszlo

2012-01-01

Photovoltaic (PV) installations have seen a huge increase during the last couple of years. Transformerless PV inverters are gaining more share of the total inverter market, due to their high conversion efficiency, small weight and size. Nevertheless safety should have an important role in case...... of these tranformerless systems, due to the missing galvanic isolation. Leakage and fault current measurement is a key issue for these inverter topologies to be able to comply with the required safety standards. This article presents the test results of two different current measurement sensors that were suggested...

Leakage current of amorphous silicon p-i-n diodes made by ion shower doping

International Nuclear Information System (INIS)

Kim, Hee Joon; Cho, Gyuseong; Choi, Joonhoo; Jung, Kwan-Wook

2002-01-01

In this letter, we report the leakage current of amorphous silicon (a-Si:H) p-i-n photodiodes, of which the p layer is formed by ion shower doping. The ion shower doping technique has an advantage over plasma-enhanced chemical vapor deposition (PECVD) in the fabrication of a large-area amorphous silicon flat-panel detector. The leakage current of the ion shower diodes shows a better uniformity within a 30 cmx40 cm substrate than that of the PECVD diodes. However, it shows a higher leakage current of 2-3 pA/mm 2 at -5 V. This high current originates from the high injection current at the p-i junction

Correlation among ESDD, NSDD and leakage current in distribution insulators

International Nuclear Information System (INIS)

Montoya, G.; Ramirez, I.; Montoya, J.I.

2004-01-01

The maintenance of distribution networks is more effective if the insulation contamination levels are known. The selection of measuring methods of pollution levels is then crucial. The relationship between several evaluation methods of pollution levels and the operating behaviour of several insulator profiles in a polluted zone is described. Laboratory tests were carried out to reproduce pollution levels found in the field. The quantity of non-soluble materials deposited over the insulators' surface affect the magnitude of the leakage current generated over a contaminated insulator. The relationship that defines leakage current with respect to the equivalent salt deposit density (ESDD) level for a specific non-soluble material level is almost linear, from which it is possible to develop a relationship between them for each insulator. (author)

Leakage Currents in Low-Voltage PME and BME Ceramic Capacitors

Science.gov (United States)

Teverovsky, Alexander

2015-01-01

Introduction of BME capacitors to high-reliability electronics as a replacement for PME capacitors requires better understanding of changes in performance and reliability of MLCCs to set justified screening and qualification requirements. In this work, absorption and leakage currents in various lots of commercial and military grade X7R MLCCs rated to 100V and less have been measured to reveal difference in behavior of PME and BME capacitors in a wide range of voltages and temperatures. Degradation of leakage currents and failures in virgin capacitors and capacitors with introduced cracks has been studied at different voltages and temperatures during step stress highly accelerated life testing. Mechanisms of charge absorption, conduction and degradation have been discussed and a failure model in capacitors with defects suggested.

Leakage current measurements on pixelated CdZnTe detectors

International Nuclear Information System (INIS)

Dirks, B.P.F.; Blondel, C.; Daly, F.; Gevin, O.; Limousin, O.; Lugiez, F.

2006-01-01

In the field of the R and D of a new generation hard X-ray cameras for space applications we focus on the use of pixelated CdTe or CdZnTe semiconductor detectors. They are covered with 64 (0.9x0.9 mm 2 ) or 256 (0.5x0.5 mm 2 ) pixels, surrounded by a guard ring and operate in the energy ranging from several keV to 1 MeV, at temperatures between -20 and +20 o C. A critical parameter in the characterisation of these detectors is the leakage current per pixel under polarisation (∼50-500 V/mm). In operation mode each pixel will be read-out by an integrated spectroscopy channel of the multi-channel IDeF-X ASIC currently developed in our lab. The design and functionality of the ASIC depends directly on the direction and value of the current. A dedicated and highly insulating electronics circuit is designed to automatically measure the current in each individual pixel, which is in the order of tens of pico-amperes. Leakage current maps of different CdZnTe detectors of 2 and 6 mm thick and at various temperatures are presented and discussed. Defect density diagnostics have been performed by calculation of the activation energy of the material

Role of Ga vacancies in enhancing the leakage current of GaN Schottky barrier ultraviolet photodetectors

International Nuclear Information System (INIS)

De-Gang, Zhao; Shuang, Zhang; Wen-Bao, Liu; De-Sheng, Jiang; Jian-Jun, Zhu; Zong-Shun, Liu; Hui, Wang; Shu-Ming, Zhang; Hui, Yang; Xiao-Peng, Hao; Long, Wei

2010-01-01

The leakage current of GaN Schottky barrier ultraviolet photodetectors is investigated. It is found that the photodetectors adopting undoped GaN instead of lightly Si-doped GaN as an active layer show a much lower leakage current even when they have a higher dislocation density. It is also found that the density of Ga vacancies in undoped GaN is much lower than in Si-doped GaN. The Ga vacancies may enhance tunneling and reduce effective Schottky barrier height, leading to an increase of leakage current. It suggests that when undoped GaN is used as the active layer, it is necessary to reduce the leakage current of GaN Schottky barrier ultraviolet photodetector. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Fluorine-plasma surface treatment for gate forward leakage current reduction in AlGaN/GaN HEMTs

International Nuclear Information System (INIS)

Chen Wanjun; Zhang Jing; Zhang Bo; Chen, Kevin Jing

2013-01-01

The gate forward leakage current in AlGaN/GaN high electron mobility transistors (HEMTs) is investigated. It is shown that the current which originated from the forward biased Schottky-gate contributed to the gate forward leakage current. Therefore, a fluorine-plasma surface treatment is presented to induce the negative ions into the AlGaN layer which results in a higher metal—semiconductor barrier. Consequently, the gate forward leakage current shrinks. Experimental results confirm that the gate forward leakage current is decreased by one order magnitude lower than that of HEMT device without plasma treatment. In addition, the DC characteristics of the HEMT device with plasma treatment have been studied. (semiconductor devices)

Leakage Current Suppression with A Novel Six-Switch Photovoltaic Grid-Connected Inverter

DEFF Research Database (Denmark)

Wei, Baoze; Guo, Xiaoqiang; Guerrero, Josep M.

2015-01-01

In order to solve the problem of the leakage current in non-isolated photovoltaic (PV) systems, a novel six-switch topology and control strategy are proposed in this paper. The inductor-bypass strategy solves the common-mode voltage limitation of the conventional six-switch topology in case...... of unmatched inductances. And the stray capacitor voltage of the non-isolated photovoltaic system is free of high frequency ripples. Theoretical analysis and simulation are carried out to verify the proposed topology and its control strategy. Results indicate that the leakage current suppression can...

Optimization of process parameter variations on leakage current in in silicon-oninsulator vertical double gate mosfet device

Directory of Open Access Journals (Sweden)

K.E. Kaharudin

2015-12-01

Full Text Available This paper presents a study of optimizing input process parameters on leakage current (IOFF in silicon-on-insulator (SOI Vertical Double-Gate,Metal Oxide Field-Effect-Transistor (MOSFET by using L36 Taguchi method. The performance of SOI Vertical DG-MOSFET device is evaluated in terms of its lowest leakage current (IOFF value. An orthogonal array, main effects, signal-to-noise ratio (SNR and analysis of variance (ANOVA are utilized in order to analyze the effect of input process parameter variation on leakage current (IOFF. Based on the results, the minimum leakage current ((IOFF of SOI Vertical DG-MOSFET is observed to be 0.009 nA/µm or 9 ρA/µm while keeping the drive current (ION value at 434 µA/µm. Both the drive current (ION and leakage current (IOFF values yield a higher ION/IOFF ratio (48.22 x 106 for low power consumption application. Meanwhile, polysilicon doping tilt angle and polysilicon doping energy are recognized as the most dominant factors with each of the contributing factor effects percentage of 59% and 25%.

Reverse leakage current characteristics of InGaN/GaN multiple quantum well ultraviolet/blue/green light-emitting diodes

Science.gov (United States)

Zhou, Shengjun; Lv, Jiajiang; Wu, Yini; Zhang, Yuan; Zheng, Chenju; Liu, Sheng

2018-05-01

We investigated the reverse leakage current characteristics of InGaN/GaN multiple quantum well (MQW) near-ultraviolet (NUV)/blue/green light-emitting diodes (LEDs). Experimental results showed that the NUV LED has the smallest reverse leakage current whereas the green LED has the largest. The reason is that the number of defects increases with increasing nominal indium content in InGaN/GaN MQWs. The mechanism of the reverse leakage current was analyzed by temperature-dependent current–voltage measurement and capacitance–voltage measurement. The reverse leakage currents of NUV/blue/green LEDs show similar conduction mechanisms: at low temperatures, the reverse leakage current of these LEDs is attributed to variable-range hopping (VRH) conduction; at high temperatures, the reverse leakage current of these LEDs is attributed to nearest-neighbor hopping (NNH) conduction, which is enhanced by the Poole–Frenkel effect.

Modeling of leakage currents in high-k dielectrics

International Nuclear Information System (INIS)

Jegert, Gunther Christian

2012-01-01

Leakage currents are one of the major bottlenecks impeding the downscaling efforts of the semiconductor industry. Two core devices of integrated circuits, the transistor and, especially, the DRAM storage capacitor, suffer from the increasing loss currents. In this perspective a fundamental understanding of the physical origin of these leakage currents is highly desirable. However, the complexity of the involved transport phenomena so far has prevented the development of microscopic models. Instead, the analysis of transport through the ultra-thin layers of high-permittivity (high-k) dielectrics, which are employed as insulating layers, was carried out at an empirical level using simple compact models. Unfortunately, these offer only limited insight into the physics involved on the microscale. In this context the present work was initialized in order to establish a framework of microscopic physical models that allow a fundamental description of the transport processes relevant in high-k thin films. A simulation tool that makes use of kinetic Monte Carlo techniques was developed for this purpose embedding the above models in an environment that allows qualitative and quantitative analyses of the electronic transport in such films. Existing continuum approaches, which tend to conceal the important physics behind phenomenological fitting parameters, were replaced by three-dimensional transport simulations at the level of single charge carriers. Spatially localized phenomena, such as percolation of charge carriers across pointlike defects, being subject to structural relaxation processes, or electrode roughness effects, could be investigated in this simulation scheme. Stepwise a self-consistent, closed transport model for the TiN/ZrO 2 material system, which is of outmost importance for the semiconductor industry, was developed. Based on this model viable strategies for the optimization of TiN/ZrO 2 /TiN capacitor structures were suggested and problem areas that may

Modeling of leakage currents in high-k dielectrics

Energy Technology Data Exchange (ETDEWEB)

Jegert, Gunther Christian

2012-03-15

Leakage currents are one of the major bottlenecks impeding the downscaling efforts of the semiconductor industry. Two core devices of integrated circuits, the transistor and, especially, the DRAM storage capacitor, suffer from the increasing loss currents. In this perspective a fundamental understanding of the physical origin of these leakage currents is highly desirable. However, the complexity of the involved transport phenomena so far has prevented the development of microscopic models. Instead, the analysis of transport through the ultra-thin layers of high-permittivity (high-k) dielectrics, which are employed as insulating layers, was carried out at an empirical level using simple compact models. Unfortunately, these offer only limited insight into the physics involved on the microscale. In this context the present work was initialized in order to establish a framework of microscopic physical models that allow a fundamental description of the transport processes relevant in high-k thin films. A simulation tool that makes use of kinetic Monte Carlo techniques was developed for this purpose embedding the above models in an environment that allows qualitative and quantitative analyses of the electronic transport in such films. Existing continuum approaches, which tend to conceal the important physics behind phenomenological fitting parameters, were replaced by three-dimensional transport simulations at the level of single charge carriers. Spatially localized phenomena, such as percolation of charge carriers across pointlike defects, being subject to structural relaxation processes, or electrode roughness effects, could be investigated in this simulation scheme. Stepwise a self-consistent, closed transport model for the TiN/ZrO{sub 2} material system, which is of outmost importance for the semiconductor industry, was developed. Based on this model viable strategies for the optimization of TiN/ZrO{sub 2}/TiN capacitor structures were suggested and problem areas

A 200 mV low leakage current subthreshold SRAM bitcell in a 130 nm CMOS process

International Nuclear Information System (INIS)

Bai Na; Lü Baitao

2012-01-01

A low leakage current subthreshold SRAM in 130 nm CMOS technology is proposed for ultra low voltage (200 mV) applications. Almost all of the previous subthreshold works ignore the leakage current in both active and standby modes. To minimize leakage, a self-adaptive leakage cut off scheme is adopted in the proposed design without any extra dynamic energy dissipation or performance penalty. Combined with buffering circuit and reconfigurable operation, the proposed design ensures both read and standby stability without deteriorating writability in the subthreshold region. Compared to the referenced subthreshold SRAM bitcell, the proposed bitcell shows: (1) a better critical state noise margin, and (2) smaller leakage current in both active and standby modes. Measurement results show that the proposed SRAM functions well at a 200 mV supply voltage with 0.13 μW power consumption at 138 kHz frequency. (semiconductor integrated circuits)

Image artifacts in concurrent transcranial magnetic stimulation (TMS) and fMRI caused by leakage currents: modeling and compensation.

Science.gov (United States)

Weiskopf, Nikolaus; Josephs, Oliver; Ruff, Christian C; Blankenburg, Felix; Featherstone, Eric; Thomas, Anthony; Bestmann, Sven; Driver, Jon; Deichmann, Ralf

2009-05-01

To characterize and eliminate a new type of image artifact in concurrent transcranial magnetic stimulation and functional MRI (TMS-fMRI) caused by small leakage currents originating from the high-voltage capacitors in the TMS stimulator system. The artifacts in echo-planar images (EPI) caused by leakage currents were characterized and quantified in numerical simulations and phantom studies with different phantom-coil geometries. A relay-diode combination was devised and inserted in the TMS circuit that shorts the leakage current. Its effectiveness for artifact reduction was assessed in a phantom scan resembling a realistic TMS-fMRI experiment. The leakage-current-induced signal changes exhibited a multipolar spatial pattern and the maxima exceeded 1% at realistic coil-cortex distances. The relay-diode combination effectively reduced the artifact to a negligible level. The leakage-current artifacts potentially obscure effects of interest or lead to false-positives. Since the artifact depends on the experimental setup and design (eg, amplitude of the leakage current, coil orientation, paradigm, EPI parameters), we recommend its assessment for each experiment. The relay-diode combination can eliminate the artifacts if necessary.

Investigation of surface related leakage current in AlGaN/GaN High Electron Mobility Transistors

Energy Technology Data Exchange (ETDEWEB)

Kaushik, J.K., E-mail: janeshkaushik@sspl.drdo.in [Solid State Physics Laboratory, Delhi 110054 (India); Balakrishnan, V.R.; Mongia, D.; Kumar, U.; Dayal, S. [Solid State Physics Laboratory, Delhi 110054 (India); Panwar, B.S. [Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Muralidharan, R. [Indian Institute of Science, Bengaluru, Karnataka 560012 (India)

2016-08-01

This paper reports the study of surface-related mechanisms to explain the high reverse leakage current observed in the in-house fabricated Si{sub 3}N{sub 4} passivated AlGaN/GaN High Electron Mobility Transistors. We propose that the Si{sub 3}N{sub 4}/AlGaN interface in the un-gated regions provides an additional leakage path between the gate and source/drain and may constitute a large component of reverse current. This surface related leakage component of current exhibits both temperature and electric field dependence and its Arrhenius behavior has been experimentally verified using Conductance Deep Level Transient Spectroscopy and temperature dependent reverse leakage current measurements. A thin interfacial amorphous semiconductor layer formed due to inter diffusion at Si{sub 3}N{sub 4}/AlGaN interface has been presumed as the source for this surface related leakage. We, therefore, conclude that optimum Si{sub 3}N{sub 4} deposition conditions and careful surface preparation prior to passivation can limit the extent of surface leakage and can thus vastly improve the device performance. - Highlights: • Enhanced leakage in AlGaN/GaN High Electron Mobility Transistors after passivation • Experimental evidence of the presence of extrinsic traps at Si{sub 3}N{sub 4}/AlGaN interface • Electron hopping in shallower extended defects and band tail traps at the interface. • Reduction in current collapse due to the virtual gate inhibition by this conduction • However, limitation on the operating voltages due to decrease in breakdown voltage.

Determination of the Steady State Leakage Current in Structures with Ferroelectric Ceramic Films

Science.gov (United States)

Podgornyi, Yu. V.; Vorotilov, K. A.; Sigov, A. S.

2018-03-01

Steady state leakage currents have been investigated in capacitor structures with ferroelectric solgel films of lead zirconate titanate (PZT) formed on silicon substrates with a lower Pt electrode. It is established that Pt/PZT/Hg structures, regardless of the PZT film thickness, are characterized by the presence of a rectifying contact similar to p-n junction. The steady state leakage current in the forward direction increases with a decrease in the film thickness and is determined by the ferroelectric bulk conductivity.

Analyses on the measurement of leakage currents in CdZnTe radiation detectors

International Nuclear Information System (INIS)

Mescher, M.J.; Hoburg, J.F.; Schlesinger, T.E.; James, R.B.

1999-01-01

Models that place design constraints on devices which are used to measure the leakage currents in high-resistivity semiconductor materials are presented. If these design constraints are met, these models can then be used to quantitatively predict the surface sheet resistance of devices which are dominated by surface leakage currents. As a result, a means is provided to directly compare passivation techniques which are developed to decrease surface leakage currents. Furthermore, these models illustrate the necessity for inclusion of relevant geometrical data on sample size and shape and electrode configuration when reporting results of surface passivation techniques. These models specifically examine the case where a dc potential is applied across two electrodes on the surface of a semiconductor substrate which has a surface layer with lower resistivity than the bulk material. The authors describe several of the more common configurations used in analyzing passivation techniques for compounds of Cd 1-x Zn x Te (CZT) used for room-temperature radiation detection

On Leakage Current Measured at High Cell Voltages in Lithium-Ion Batteries

Energy Technology Data Exchange (ETDEWEB)

Vadivel, Nicole R.; Ha, Seungbum; He, Meinan; Dees, Dennis; Trask, Steve; Polzin, Bryant; Gallagher, Kevin G.

2017-01-01

In this study, parasitic side reactions in lithium-ion batteries were examined experimentally using a potentiostatic hold at high cell voltage. The experimental leakage current measured during the potentiostatic hold was compared to the Tafel expression and showed poor agreement with the expected transfer coefficient values, indicating that a more complicated expression could be needed to accurately capture the physics of this side reaction. Here we show that cross-talk between the electrodes is the primary contribution to the observed leakage current after the relaxation of concentration gradients has ceased. This cross-talk was confirmed with experiments using a lithium-ion conducting glass ceramic (LICGC) separator, which has high conductance only for lithium cations. The cells with LICGC separators showed significantly less leakage current during the potentiostatic hold test compared to cells with standard microporous separators where cross-talk is present. In addition, direct-current pulse power tests show an impedance rise for cells held at high potentials and for cells held at high temperatures, which could be attributed to film formation from the parasitic side reaction. Based on the experimental findings, a phenomenological mechanism is proposed for the parasitic side reaction which accounts for cross-talk and mass transport of the decomposition products across the separator.

Initial leakage current paths in the vertical-type GaN-on-GaN Schottky barrier diodes

Science.gov (United States)

Sang, Liwen; Ren, Bing; Sumiya, Masatomo; Liao, Meiyong; Koide, Yasuo; Tanaka, Atsushi; Cho, Yujin; Harada, Yoshitomo; Nabatame, Toshihide; Sekiguchi, Takashi; Usami, Shigeyoshi; Honda, Yoshio; Amano, Hiroshi

2017-09-01

Electrical characteristics of leakage current paths in vertical-type n-GaN Schottky barrier diodes (SBDs) on free-standing GaN substrates are investigated by using photon emission microscopy (PEM). The PEM mapping shows that the initial failure of the SBD devices at low voltages is due to the leakage current paths from polygonal pits in the GaN epilayers. It is observed that these polygonal pits originate from carbon impurity accumulation to the dislocations with a screw-type component by microstructure analysis. For the SBD without polygonal pits, no initial failure is observed and the first leakage appeals at the edge of electrodes as a result of electric field concentration. The mechanism of leakage at pits is explained in terms of trap assisted tunneling through fitting current-voltage characteristics.

Leakage current-induced effects in the silicon microstrip and gas electron multiplier readout chain and their compensation method

Science.gov (United States)

Zubrzycka, W.; Kasinski, K.

2018-04-01

Leakage current flowing into the charge sensitive amplifier (CSA) is a common issue in many radiation detection systems as it can increase overall system noise, shift a DC baseline or even lead a recording channel to instability. The commonly known leakage current contributor is a detector, however other system components like wires or an input protection circuit may become a serious problem. Compensation of the leakage current resulting from the electrostatic discharge (ESD) protection circuit by properly sizing its components is possible only for a narrow temperature range. Moreover, the leakage current from external sources can be significantly larger. Many applications, especially High Energy Physics (HEP) experiments, require a fast baseline restoration for high input hit rates by applying either a low-value feedback resistor or a high feedback resistance combined with a pulsed reset circuit. Leakage current flowing in the feedback in conjunction with a large feedback resistance supplied with a pulsed reset results in a significant voltage offset between the CSA input and output which can cause problems (e.g. fake hits or instability). This paper shows an issue referred to the leakage current of the ESD protection circuit flowing into the input amplifier. The following analysis and proposed solution is a result of the time and energy readout ASIC project realization for the Compressed Baryonic Matter (CBM) experiment at FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. This chip is purposed to work with microstrip and gaseous detectors, with high average input pulses frequencies (250 kHit/s per channel) and the possibility to process input charge of both polarities. We present measurements of the test structure fabricated in UMC 180 nm technology and propose a solution addressing leakage current related issues. This work combines the leakage current compensation capabilities at the CSA level with high, controllable value of the amplifier

Accurate characterization of organic thin film transistors in the presence of gate leakage current

Directory of Open Access Journals (Sweden)

Vinay K. Singh

2011-12-01

Full Text Available The presence of gate leakage through polymer dielectric in organic thin film transistors (OTFT prevents accurate estimation of transistor characteristics especially in subthreshold regime. To mitigate the impact of gate leakage on transfer characteristics and allow accurate estimation of mobility, subthreshold slope and on/off current ratio, a measurement technique involving simultaneous sweep of both gate and drain voltages is proposed. Two dimensional numerical device simulation is used to illustrate the validity of the proposed technique. Experimental results obtained with Pentacene/PMMA OTFT with significant gate leakage show a low on/off current ratio of ∼ 102 and subthreshold is 10 V/decade obtained using conventional measurement technique. The proposed technique reveals that channel on/off current ratio is more than two orders of magnitude higher at ∼104 and subthreshold slope is 4.5 V/decade.

Nanoscale leakage current measurements in metal organic chemical vapor deposition crystalline SrTiO3 films

International Nuclear Information System (INIS)

Rozier, Y.; Gautier, B.; Hyvert, G.; Descamps, A.; Plossu, C.; Dubourdieu, C.; Ducroquet, F.

2009-01-01

The properties of SrTiO 3 thin films, grown by liquid injection metal organic chemical vapor deposition on Si/SiO 2 , using a mixture of precursors, have been investigated at the nanoscale using an Atomic Force Microscope in the so-called Conductive Atomic Force Microscopy mode. Maps of the leakage currents with a nanometric resolution have been obtained on films elaborated at different temperatures and stoichiometries in order to discriminate the role of each parameter on the onset of leakage currents in the resulting layers. It appears that the higher the deposition temperature, the higher the leakage currents of the films. The mapping with a nanometric precision allows to show a heterogeneous behaviour of the surface with leaky grains and insulating boundaries. The study of films elaborated at the same temperature with different compositions supports the assumption that the leakage currents on Ti-rich layers are far higher than on Sr-rich layers

A new circuit technique for reduced leakage current in Deep Submicron CMOS technologies

Directory of Open Access Journals (Sweden)

A. Schmitz

2005-01-01

Full Text Available Modern CMOS processes in the Deep Submicron regime are restricted to supply voltages below 2 volts and further to account for the transistors' field strength limitations and to reduce the power per logic gate. To maintain the high switching performance, the threshold voltage must be scaled according with the supply voltage. However, this leads to an increased subthreshold current of the transistors in standby mode (VGS=0. Another source of leakage is gate current, which becomes significant for gate oxides of 3nm and below. We propose a Self-Biasing Virtual Rails (SBVR - CMOS technique which acts like an adaptive local supply voltage in case of standby mode. Most important sources of leakage currents are reduced by this technique. Moreover, SBVR-CMOS is capable of conserving stored information in sleep mode, which is vital for memory circuits. Memories are exposed to radiation causing soft errors. This well-known problem becomes even worse in standby mode of typical SRAMs, that have low driving performance to withstand alpha particle hits. In this paper, a 16-transistor SRAM cell is proposed, which combines the advantage of extremely low leakage currents with a very high soft error stability.

Image Artifacts in Concurrent Transcranial Magnetic Stimulation (TMS) and fMRI Caused by Leakage Currents: Modeling and Compensation

Science.gov (United States)

Weiskopf, Nikolaus; Josephs, Oliver; Ruff, Christian C; Blankenburg, Felix; Featherstone, Eric; Thomas, Anthony; Bestmann, Sven; Driver, Jon; Deichmann, Ralf

2009-01-01

Purpose To characterize and eliminate a new type of image artifact in concurrent transcranial magnetic stimulation and functional MRI (TMS-fMRI) caused by small leakage currents originating from the high-voltage capacitors in the TMS stimulator system. Materials and Methods The artifacts in echo-planar images (EPI) caused by leakage currents were characterized and quantified in numerical simulations and phantom studies with different phantom-coil geometries. A relay-diode combination was devised and inserted in the TMS circuit that shorts the leakage current. Its effectiveness for artifact reduction was assessed in a phantom scan resembling a realistic TMS-fMRI experiment. Results The leakage-current-induced signal changes exhibited a multipolar spatial pattern and the maxima exceeded 1% at realistic coil-cortex distances. The relay-diode combination effectively reduced the artifact to a negligible level. Conclusion The leakage-current artifacts potentially obscure effects of interest or lead to false-positives. Since the artifact depends on the experimental setup and design (eg, amplitude of the leakage current, coil orientation, paradigm, EPI parameters), we recommend its assessment for each experiment. The relay-diode combination can eliminate the artifacts if necessary. J. Magn. Reson. Imaging 2009;29:1211–1217. © 2009 Wiley-Liss, Inc. PMID:19388099

Space Vector Modulation Technique to Reduce Leakage Current of a Transformerless Three-Phase Four-Leg Photovoltaic System

Directory of Open Access Journals (Sweden)

F. Hasanzad

2017-06-01

Full Text Available Photovoltaic systems integrated to the grid have received considerable attention around the world. They can be connected to the electrical grid via galvanic isolation (transformer or without it (transformerless. Despite making galvanic isolation, low frequency transformer increases size, cost and losses. On the other hand, transformerless PV systems increase the leakage current (common-mode current, (CMC through the parasitic capacitors of the PV array. Inverter topology and switching technique are the most important parameters the leakage current depends on. As there is no need to extra hardware for switching scheme modification, it's an economical method for reducing leakage current. This paper evaluates the effect of different space vector modulation techniques on leakage current for a two-level three-phase four-leg inverter used in PV system. It proposes an efficient space vector modulation method which decreases the leakage current to below the quantity specified in VDE-0126-1-1 standard. furthermore, some other characteristics of the space vector modulation schemes that have not been significantly discussed for four-leg inverter, are considered, such as, modulation index, switching actions per period, common-mode voltage (CMV, and total harmonic distortion (THD. An extend software simulation using MATLAB/Simulink is performed to verify the effectiveness of the modulation technique.

Detection of defect states responsible for leakage current in ultrathin tantalum pentoxide (Ta2O5) films by zero-bias thermally stimulated current spectroscopy

International Nuclear Information System (INIS)

Lau, W.S.; Zhong, L.; Lee, A.; See, C.H.; Han, T.; Sandler, N.P.; Chong, T.C.

1997-01-01

Defect states responsible for leakage current in ultrathin (physical thickness 2 O 5 ) films were measured with a novel zero-bias thermally stimulated current technique. It was found that defect states A, whose activation energy was estimated to be about 0.2 eV, can be more efficiently suppressed by using N 2 O rapid thermal annealing (RTA) instead of using O 2 RTA for postdeposition annealing. The leakage current was also smaller for samples with N 2 O RTA than those with O 2 RTA for postdeposition annealing. Hence, defect states A are quite likely to be important in causing leakage current. copyright 1997 American Institute of Physics

Study of leakage current behaviour on artificially polluted surface of ceramic insulator

International Nuclear Information System (INIS)

Subba Reddy, B.; Nagabhushana, G.R.

2003-01-01

This paper presents the results of the study concerning to the leakage current behaviour on artificially polluted ceramic insulator surface. From the present study it was observed that there is a reasonably well-defined inception of current i.e. scintillations at a finite voltage. The corresponding voltages for extinction of the current are in the range of 0.8 kV to 2.1 kV. Obviously, the dry band formed in the immediate vicinity of the pin prevents smooth current flow as the voltage rises from zero. Only when the voltage is adequate it causes a flashover of the dray band and current starts flowing. As is common in similar current extinction phenomena, here also, the extinction voltages are significantly lower than the inception voltages. Further, the voltage-current curves invariably show hysteresis-the leakage currents are lower in the reducing portion of the voltage. This is obviously due to drying of the wet pollutant layer thereby increasing its resistance. It is believed that this is the first time that such a direct quantitative evidence of drying in individual half cycles is experimentally visualized

A transformerless single-phase symmetrical Z-source HERIC inverter with reduced leakage currents for PV systems

DEFF Research Database (Denmark)

Li, Kerui; Shen, Yanfeng; Yang, Yongheng

2018-01-01

and thus low leakage currents in PV applications. The symmetric Z-source HERIC inverter requires two extra active switches. Nevertheless, the operation frequency of the two switches is the line frequency, leading to negligible losses. More importantly, the performance in terms of low leakage currents...... and harmonics is improved. Experimental tests are performed to validate the analysis and performance of the proposed system....

Effect of the critical current density and the junction size on the leakage current of Nb/Al-AlOx/Nb superconducting tunnel junctions for radiation detection

International Nuclear Information System (INIS)

Joosse, K.; Nakagawa, Hiroshi; Akoh, Hiroshi; Takada, Susumu; Maehata, Keisuke; Ishibashi, Kenji.

1996-01-01

Nb/Al-AlO x /Nb superconducting tunnel junctions (STJ's) designed for X-ray detection have been fabricated. The behavior of the low-temperature subgap leakage current, which severely limits the energy resolution obtained in such devices, is investigated. From trends in the dependence of the leakage currents on the critical current density and the size of the STJ, as well as from the low-temperature current-voltage characteristics, and an analysis of the base electrode surface morphology, it is concluded that physical defects in the barrier region are the most probable cause of the leakage currents. Suggestions are given for optimization of the device processing. (author)

Leakage current transport mechanisms of La 0.67 Sr 0.33 MnO 3 ...

Indian Academy of Sciences (India)

limited current mechanism under forward bias while thermionic emission model under reverse bias. Analysis indicates that a modulating Schottky barrier exists at the LSMO/BTO interface, which dominates the leakage current transport properties ...

Correlation between dislocations and leakage current of p-n diodes on a free-standing GaN substrate

Science.gov (United States)

Usami, Shigeyoshi; Ando, Yuto; Tanaka, Atsushi; Nagamatsu, Kentaro; Deki, Manato; Kushimoto, Maki; Nitta, Shugo; Honda, Yoshio; Amano, Hiroshi; Sugawara, Yoshihiro; Yao, Yong-Zhao; Ishikawa, Yukari

2018-04-01

Dislocations that cause a reverse leakage current in vertical p-n diodes on a GaN free-standing substrate were investigated. Under a high reverse bias, dot-like leakage spots were observed using an emission microscope. Subsequent cathodoluminescence (CL) observations revealed that the leakage spots coincided with part of the CL dark spots, indicating that some types of dislocation cause reverse leakage. When etch pits were formed on the dislocations by KOH etching, three sizes of etch pits were obtained (large, medium, and small). Among these etch pits, only the medium pits coincided with leakage spots. Additionally, transmission electron microscopy observations revealed that pure screw dislocations are present under the leakage spots. The results revealed that 1c pure screw dislocations are related to the reverse leakage in vertical p-n diodes.

Power crowbar system coupled by a current transformer with very low leakage inductance

International Nuclear Information System (INIS)

Kitagawa, S.; Hirano, K.I.

1976-01-01

A reliable, efficient power crowbar system has been developed for fast pinch experiments. In order to reduce the effective impedance of series capacitor system, a current transformer with extremely low leakage inductance has been designed and used. Primary and secondary windings of the transformer are alternately arranged as closely as possible. As a result, the leakage inductance is reduced to 2 nH. It is demonstrated that a current of 390 kA, the rise time of which is 4.5 μsec, is sustained for 100 μsec. Much larger system is being built, which maintains a current of 1 MA over 1 msec. The life of crowbar gap switches is prolonged by the aid of a mechanically-driven metal-to-metal contact switch. Another crowbar switch system with a high coulomb rating is under consideration, in which a gap switch is used together with a saturable reactor and a current transformer

Ultrathin silicon dioxide layers with a low leakage current density formed by chemical oxidation of Si

Science.gov (United States)

Asuha,; Kobayashi, Takuya; Maida, Osamu; Inoue, Morio; Takahashi, Masao; Todokoro, Yoshihiro; Kobayashi, Hikaru

2002-10-01

Chemical oxidation of Si by use of azeotrope of nitric acid and water can form 1.4-nm-thick silicon dioxide layers with a leakage current density as low as those of thermally grown SiO2 layers. The capacitance-voltage (C-V) curves for these ultrathin chemical SiO2 layers have been measured due to the low leakage current density. The leakage current density is further decreased to approx1/5 (cf. 0.4 A/cm2 at the forward gate bias of 1 V) by post-metallization annealing at 200 degC in hydrogen. Photoelectron spectroscopy and C-V measurements show that this decrease results from (i) increase in the energy discontinuity at the Si/SiO2 interface, and (ii) elimination of Si/SiO2 interface states and SiO2 gap states.

Influence of the gate edge on the reverse leakage current of AlGaN/GaN HEMTs

Directory of Open Access Journals (Sweden)

YongHe Chen

2015-09-01

Full Text Available By comparing the Schottky diodes of different area and perimeter, reverse gate leakage current of AlGaN/GaN high mobility transistors (HEMT at gate bias beyond threshold voltage is studied. It is revealed that reverse current consists of area-related and perimeter-related current. An analytical model of electric field calculation is proposed to obtain the average electric field around the gate edge at high revers bias and estimate the effective range of edge leakage current. When the reverse bias increases, the increment of electric field is around the gate edge of a distance of ΔL, and perimeter-related gate edge current keeps increasing. By using the calculated electric field and the temperature-dependent current-voltage measurements, the edge gate leakage current mechanism is found to be Fowler-Nordheim tunneling at gate bias bellows -15V caused by the lateral extended depletion region induced barrier thinning. Effective range of edge current of Schottky diodes is about hundred to several hundred nano-meters, and is different in different shapes of Schottky diodes.

Process effects on leakage current of Si-PIN neutron detectors with porous microstructure

Energy Technology Data Exchange (ETDEWEB)

Yu, Baoning; Zhao, Kangkang; Yang, Taotao [Beijing University of Technology, Chaoyang District, Pingleyuan 100, 100124 Beijing (China); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, 215123 Suzhou (China); Jiang, Yong; Fan, Xiaoqiang [Institute of Nuclear Physics and Chemistry, CAEP, Mianshan Road 64, 621900 Mianyang (China); Lu, Min [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, 215123 Suzhou (China); Han, Jun [Beijing University of Technology, Chaoyang District, Pingleyuan 100, 100124 Beijing (China)

2017-06-15

Using the technique of Microfabrication, such as deep silicon dry etching, lithography, etc. Si-PIN neutron detectors with porous microstructure have been successfully fabricated. In order to lower the leakage current, the key fabrication processes, including the Al windows opening, deep silicon etching and the porous side wall smoothing, have been optimized. The cross-section morphology and current-voltage characteristics have been measured to evaluate the microfabrication processes. With the optimized conditions presented by the measurements, a neutron detector with a leakage current density of 2.67 μA cm{sup -2} at a bias of -20 V is obtained. A preliminary neutron irradiation test with {sup 252}Cf neutron source has also been carried out. The neutron irradiation test shows that the neutron detection efficiency of the microstructured neutron detectors is almost 3.6 times higher than that of the planar ones. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Band to Band Tunneling (BBT) Induced Leakage Current Enhancement in Irradiated Fully Depleted SOI Devices

Science.gov (United States)

Adell, Phillipe C.; Barnaby, H. J.; Schrimpf, R. D.; Vermeire, B.

2007-01-01

We propose a model, validated with simulations, describing how band-to-band tunneling (BBT) affects the leakage current degradation in some irradiated fully-depleted SOI devices. The dependence of drain current on gate voltage, including the apparent transition to a high current regime is explained.

The optimal design of 15 nm gate-length junctionless SOI FinFETs for reducing leakage current

International Nuclear Information System (INIS)

Liu, Xi; Wu, Meile; Jin, Xiaoshi; Chuai, Rongyan; Lee, Jung-Hee; Lee, Jong-Ho

2013-01-01

Junctionless (JL) transistors need to be heavily doped to have large drain current in the ON-state, which engenders the effect of band-to-band tunneling (BTBT) in the OFF-state simultaneously. It causes an obvious increase of the leakage current in the OFF-state. This paper presents an effective method of reducing the leakage current by changing the geometrical shape and dimension of the oxide layer under the edge of the gate. The optimal design of 15 nm gate-length JL silicon-on-insulator FinFETs with the triple-gate structure is performed for reducing the effect of BTBT through simulation and analysis by this means. (paper)

Influence of process parameters on threshold voltage and leakage current in 18nm NMOS device

Science.gov (United States)

Atan, Norani Binti; Ahmad, Ibrahim Bin; Majlis, Burhanuddin Bin Yeop; Fauzi, Izzati Binti Ahmad

2015-04-01

The process parameters are very crucial factor in the development of transistors. There are many process parameters that influenced in the development of the transistors. In this research, we investigate the effects of the process parameters variation on response characteristics such as threshold voltage (VTH) and sub-threshold leakage current (IOFF) in 18nm NMOS device. The technique to identify semiconductor process parameters whose variability would impact most on the device characteristic is realized through the process by using Taguchi robust design method. This paper presents the process parameters that influenced in threshold voltage (VTH) and sub-threshold leakage current (IOFF) which includes the Halo Implantation, Compensation Implantation, Adjustment Threshold voltage Implantation and Source/Drain Implantation. The design, fabrication and characterization of 18nm HfO2/TiSi2 NMOS device is simulated and performed via a tool called Virtual Wafer Fabrication (VWF) Silvaco TCAD Tool known as ATHENA and ATLAS simulators. These two simulators were combined with Taguchi L9 Orthogonal method to aid in the design and the optimization of the process parameters to achieve the optimum average of threshold voltage (VTH) and sub-threshold leakage current, (IOFF) in 18nm device. Results from this research were obtained; where Halo Implantation dose was identified as one of the process parameter that has the strongest effect on the response characteristics. Whereby the Compensation Implantation dose was identified as an adjustment factor to get the nominal values of threshold voltage VTH, and sub-threshold leakage current, IOFF for 18nm NMOS devices equal to 0.302849 volts and 1.9123×10-16 A/μm respectively. The design values are referred to ITRS 2011 prediction.

Comparison of the Standard of Air Leakage in Current Metal Duct Systems in the World

Science.gov (United States)

Di, Yuhui; Wang, Jiqian; Feng, Lu; Li, Xingwu; Hu, Chunlin; Shi, Junshe; Xu, Qingsong; Qiao, Leilei

2018-01-01

Based on the requirements of air leakage of metal ducts in Chinese design standards, technical measures and construction standards, this paper compares the development history, the classification of air pressure levels and the air tightness levels of air leakage standards of current Chinese and international metal ducts, sums up the differences, finds shortage by investigating the design and construction status and access to information, and makes recommendations, hoping to help the majority of engineering and technical personnel.

Leakage current analysis of a single-phase transformer-less PV inverter connected to the grid

DEFF Research Database (Denmark)

Ma, Lin; Tang, F.; Zhou, F.

2009-01-01

Due to the large surface of the PV generator, its stray capacity with respect to the ground reaches values that can be quite high. When no transformer is used in a grid-connected PV system, common-mode current, which caused by the common mode voltage, can flow through the stray capacitance between...... the PV array and the ground. It is quite harmful to the body safety and PV system. In order to avoid leakage current, different inverter topologies that generate no varying common-mode voltages, such as bipolar pulse-width modulation (PWM) full-bridge topology, NPC topology have been proposed. From...... the safety and energy saving viewpoint, it is necessary to develop a higher efficiency topology. In this paper, the generation mechanism of common mode current is discussed. Then different methods used to eliminate the leakage current are compared. Finally, the full-bridge which generates no varying common...

Current leakage relaxation and charge trapping in ultra-porous low-k materials

International Nuclear Information System (INIS)

Borja, Juan; Plawsky, Joel L.; Gill, William N.; Lu, T.-M.; Bakhru, Hassaram

2014-01-01

Time dependent dielectric failure has become a pivotal aspect of interconnect design as industry pursues integration of sub-22 nm process-technology nodes. Literature has provided key information about the role played by individual species such as electrons, holes, ions, and neutral impurity atoms. However, no mechanism has been shown to describe how such species interact and influence failure. Current leakage relaxation in low-k dielectrics was studied using bipolar field experiments to gain insight into how charge carrier flow becomes impeded by defects within the dielectric matrix. Leakage current decay was correlated to injection and trapping of electrons. We show that current relaxation upon inversion of the applied field can be described by the stretched exponential function. The kinetics of charge trapping events are consistent with a time-dependent reaction rate constant, k=k 0 ⋅(t+1) β−1 , where 0 < β < 1. Such dynamics have previously been observed in studies of charge trapping reactions in amorphous solids by W. H. Hamill and K. Funabashi, Phys. Rev. B 16, 5523–5527 (1977). We explain the relaxation process in charge trapping events by introducing a nonlinear charge trapping model. This model provides a description on the manner in which the transport of mobile defects affects the long-tail current relaxation processes in low-k films

The analysis of leakage current in MIS Au/SiO{sub 2}/n-GaAs at room temperature

Energy Technology Data Exchange (ETDEWEB)

Altuntas, H., E-mail: altunhalit@gmail.com [Cankiri Karatekin University, Department of Physics, Faculty of Science (Turkey); Ozcelik, S. [Gazi University, Department of Physics, Faculty of Science (Turkey)

2013-10-15

The aim of this study is to determine the reverse-bias leakage current conduction mechanisms in Au/SiO{sub 2}/n-GaAs metal-insulator-semiconductor type Schottky contacts. Reverse-bias current-voltage measurements (I-V) were performed at room temperature. The using of leakage current values in SiO{sub 2} at electric fields of 1.46-3.53 MV/cm, ln(J/E) vs. {radical}E graph showed good linearity. Rom this plot, dielectric constant of SiO{sub 2} was calculated as 3.7 and this value is perfect agreement with 3.9 which is value of SiO{sub 2} dielectric constant. This indicates, Poole-Frenkel type emission mechanism is dominant in this field region. On the other hand, electric fields between 0.06-0.73 and 0.79-1.45 MV/cm, dominant leakage current mechanisms were found as ohmic type conduction and space charge limited conduction, respectively.

Investigation of leakage current and breakdown voltage in irradiated double-sided 3D silicon sensors

International Nuclear Information System (INIS)

Betta, G.-F. Dalla; Mendicino, R.; Povoli, M.; Sultan, D.M.S.; Ayllon, N.; Hoeferkamp, M.; McDuff, H.; Seidel, S.; Boscardin, M.; Zorzi, N.; Mattiazzo, S.

2016-01-01

We report on an experimental study aimed at gaining deeper insight into the leakage current and breakdown voltage of irradiated double-sided 3D silicon sensors from FBK, so as to improve both the design and the fabrication technology for use at future hadron colliders such as the High Luminosity LHC. Several 3D diode samples of different technologies and layout are considered, as well as several irradiations with different particle types. While the leakage current follows the expected linear trend with radiation fluence, the breakdown voltage is found to depend on both the bulk damage and the surface damage, and its values can vary significantly with sensor geometry and process details.

A Labview Based Leakage Current Monitoring System For HV Insulators

Directory of Open Access Journals (Sweden)

N. Mavrikakis

2015-10-01

Full Text Available In this paper, a Labview based leakage current monitoring system for High Voltage insulators is described. The system uses a general purpose DAQ system with the addition of different current sensors. The DAQ system consists of a chassis and hot-swappable modules. Through the proper design of current sensors, low cost modules operating with a suitable input range can be employed. Fully customizable software can be developed using Labview, allowing on-demand changes and incorporation of upgrades. Such a system provides a low cost alternative to specially designed equipment with the added advantage of maximum flexibility. Further, it can be modified to satisfy the specifications (technical and economical set under different scenarios. In fact, the system described in this paper has already been installed in the HV Lab of the TEI of Crete whereas a variation of it is currently in use in TALOS High Voltage Test Station.

Carbon nanotube feedback-gate field-effect transistor: suppressing current leakage and increasing on/off ratio.

Science.gov (United States)

Qiu, Chenguang; Zhang, Zhiyong; Zhong, Donglai; Si, Jia; Yang, Yingjun; Peng, Lian-Mao

2015-01-27

Field-effect transistors (FETs) based on moderate or large diameter carbon nanotubes (CNTs) usually suffer from ambipolar behavior, large off-state current and small current on/off ratio, which are highly undesirable for digital electronics. To overcome these problems, a feedback-gate (FBG) FET structure is designed and tested. This FBG FET differs from normal top-gate FET by an extra feedback-gate, which is connected directly to the drain electrode of the FET. It is demonstrated that a FBG FET based on a semiconducting CNT with a diameter of 1.5 nm may exhibit low off-state current of about 1 × 10(-13) A, high current on/off ratio of larger than 1 × 10(8), negligible drain-induced off-state leakage current, and good subthreshold swing of 75 mV/DEC even at large source-drain bias and room temperature. The FBG structure is promising for CNT FETs to meet the standard for low-static-power logic electronics applications, and could also be utilized for building FETs using other small band gap semiconductors to suppress leakage current.

Liquid helium boil-off measurements of heat leakage from sinter-forged BSCCO current leads under DC and AC conditions

International Nuclear Information System (INIS)

Cha, Y.S.; Niemann, R.C.; Hull, J.R.; Youngdahl, C.A.; Lanagan, M.T.; Nakade, M.; Hara, T.

1995-06-01

Liquid helium boil-off experiments are conducted to determine the heat leakage rate of a pair of BSCCO 2223 high-temperature superconductor current leads made by sinter forging. The experiments are carried out in both DC and AC conditions and with and without an intermediate heat intercept. Current ranges are from 0-500 A for DC tests and 0-1,000 A rms for AC tests. The leads are self-cooled. Results show that magnetic hysteresis (AC) losses for both the BSCCO leads and the low-temperature superconductor current jumper are small for the current range. It is shown that significant reduction in heat leakage rate (liquid helium boil-off rate) is realized by using the BSCCO superconductor leads. At 100 A, the heat leakage rate of the BSCCO/copper binary lead is approximately 29% of that of the conventional copper lead. Further reduction in liquid helium boil-off rate can be achieved by using an intermediate heat intercept. For example, at 500 K, the heat leakage rate of the BSCCO/copper binary lead is only 7% of that of the conventional copper lead when an intermediate heat intercept is used

Conduction mechanism of leakage current due to the traps in ZrO2 thin film

Science.gov (United States)

Seo, Yohan; Lee, Sangyouk; An, Ilsin; Song, Chulgi; Jeong, Heejun

2009-11-01

In this work, a metal-oxide-semiconductor capacitor with zirconium oxide (ZrO2) gate dielectric was fabricated by an atomic layer deposition (ALD) technique and the leakage current characteristics under negative bias were studied. From the result of current-voltage curves there are two possible conduction mechanisms to explain the leakage current in the ZrO2 thin film. The dominant mechanism is the space charge limited conduction in the high-electric field region (1.5-5.0 MV cm-1) while the trap-assisted tunneling due to the existence of traps is prevailed in the low-electric field region (0.8-1.5 MV cm-1). Conduction caused by the trap-assisted tunneling is found from the experimental results of a weak temperature dependence of current, and the trap barrier height is obtained. The space charge limited conduction is evidenced, for different temperatures, by Child's law dependence of current density versus voltage. Child's law dependence can be explained by considering a single discrete trapping level and we can obtain the activation energy of 0.22 eV.

Capacitor Property and Leakage Current Mechanism of ZrO2 Thin Dielectric Films Prepared by Anodic Oxidation

Science.gov (United States)

Kamijyo, Masahiro; Onozuka, Tomotake; Shinkai, Satoko; Sasaki, Katsutaka; Yamane, Misao; Abe, Yoshio

2003-07-01

Polycrystalline ZrO2 thin film capacitors were prepared by anodizing sputter-deposited Zr films. Electrical measurements are performed for the parallel-plate anodized capacitors with an Al-ZrO2-Zr (metal-insulator-metal) structure, and a high capacitance density (0.6 μF/cm2) and a low dielectric loss of nearly 1% are obtained for a very thin-oxide capacitor anodized at 10 V. In addition, the leakage current density of this capacitor is about 1.8 × 10-8 A/cm2 at an applied voltage of 5 V. However, the leakage current is somewhat larger than that of a low-loss HfO2 capacitor. The leakage current density (J) of ZrO2 capacitors as a function of applied electric field (E) was investigated for several capacitors with different oxide thicknesses, by plotting \\ln(J) vs E1/2 curves. As a result, it is revealed that the conduction mechanism is due to the Poole-Frenkel effect, irrespective of the oxide thickness.

Analysis of Gas Leakage and Current Loss of Solid Oxide Fuel Cells by Screen Printing

DEFF Research Database (Denmark)

Jia, Chuan; Han, Minfang; Chen, Ming

2017-01-01

Two types of anode supported solid oxide fuel cell (SOFC) NiO-YSZ/YSZ/GDC/LSCF with the same structure and different manufacturing process were tested. Gas leakage was suspected for cells manufactured with screen printing technique. Effective leak current densities for both types of cells were...... calculated. Their performances of electrochemical impedance spectroscopy (EIS) were compared and distribution function of relaxation times (DRT) technique was also used to find the clue of gas leakage. Finally, thinning and penetrating holes were observed in electrolyte layer, which confirmed the occurrence...

The study of human bodies' impedance networks in testing leakage currents of electrical equipments

Science.gov (United States)

Zhang, Zhaohui; Wang, Xiaofei

2006-11-01

In the testing of electrical equipments' leakage currents, impedance networks of human bodies are used to simulate the current's effect on human bodies, and they are key to the preciseness of the testing result. This paper analyses and calculates three human bodies' impedance networks of measuring electric burn current, perception or reaction current, let-go current in IEC60990, by using Matlab, compares the research result of current effect thresholds' change with sine wave's frequency published in IEC479-2, and amends parameters of measuring networks. It also analyses the change of perception or reaction current with waveform by Multisim.

Polarization retention loss in PbTiO3 ferroelectric films due to leakage currents

NARCIS (Netherlands)

Morelli, A.; Venkatesan, Sriram; Palasantzas, G.; Kooi, B. J.; De Hosson, J. Th. M.

2007-01-01

The relationship between retention loss in single crystal PbTiO3 ferroelectric thin films and leakage currents is demonstrated by piezoresponse and conductive atomic force microscopy measurements. It was found that the polarization reversal in the absence of an electric field followed a stretched

Conduction mechanism of leakage current due to the traps in ZrO2 thin film

International Nuclear Information System (INIS)

Seo, Yohan; Lee, Sangyouk; An, Ilsin; Jeong, Heejun; Song, Chulgi

2009-01-01

In this work, a metal-oxide-semiconductor capacitor with zirconium oxide (ZrO 2 ) gate dielectric was fabricated by an atomic layer deposition (ALD) technique and the leakage current characteristics under negative bias were studied. From the result of current–voltage curves there are two possible conduction mechanisms to explain the leakage current in the ZrO 2 thin film. The dominant mechanism is the space charge limited conduction in the high-electric field region (1.5–5.0 MV cm −1 ) while the trap-assisted tunneling due to the existence of traps is prevailed in the low-electric field region (0.8–1.5 MV cm −1 ). Conduction caused by the trap-assisted tunneling is found from the experimental results of a weak temperature dependence of current, and the trap barrier height is obtained. The space charge limited conduction is evidenced, for different temperatures, by Child's law dependence of current density versus voltage. Child's law dependence can be explained by considering a single discrete trapping level and we can obtain the activation energy of 0.22 eV

Study of surface leakage current of AlGaN/GaN high electron mobility transistors

International Nuclear Information System (INIS)

Chen, YongHe; Zhang, Kai; Cao, MengYi; Zhao, ShengLei; Zhang, JinCheng; Hao, Yue; Ma, XiaoHua

2014-01-01

Temperature-dependent surface current measurements were performed to analyze the mechanism of surface conductance of AlGaN/GaN channel high-electron-mobility transistors by utilizing process-optimized double gate structures. Different temperatures and electric field dependence have been found in surface current measurements. At low electric field, the mechanism of surface conductance is considered to be two-dimensional variable range hopping. At elevated electric field, the Frenkel–Poole trap assisted emission governs the main surface electrons transportation. The extracted energy barrier height of electrons emitting from trapped state near Fermi energy level into a threading dislocations-related continuum state is 0.38 eV. SiN passivation reduces the surface leakage current by two order of magnitude and nearly 4 orders of magnitude at low and high electric fields, respectively. SiN also suppresses the Frenkel–Poole conductance at high temperature by improving the surface states of AlGaN/GaN. A surface treatment process has been introduced to further suppress the surface leakage current at high temperature and high field, which results in a decrease in surface current of almost 3 orders of magnitude at 476 K

Leakage Current Degradation Due to Ion Drift and Diffusion in Tantalum and Niobium Oxide Capacitors

Directory of Open Access Journals (Sweden)

Kuparowitz Martin

2017-06-01

Full Text Available High temperature and high electric field applications in tantalum and niobium capacitors are limited by the mechanism of ion migration and field crystallization in a tantalum or niobium pentoxide insulating layer. The study of leakage current (DCL variation in time as a result of increasing temperature and electric field might provide information about the physical mechanism of degradation. The experiments were performed on tantalum and niobium oxide capacitors at temperatures of about 125°C and applied voltages ranging up to rated voltages of 35 V and 16 V for tantalum and niobium oxide capacitors, respectively. Homogeneous distribution of oxygen vacancies acting as positive ions within the pentoxide layer was assumed before the experiments. DCL vs. time characteristics at a fixed temperature have several phases. At the beginning of ageing the DCL increases exponentially with time. In this period ions in the insulating layer are being moved in the electric field by drift only. Due to that the concentration of ions near the cathode increases producing a positively charged region near the cathode. The electric field near the cathode increases and the potential barrier between the cathode and insulating layer decreases which results in increasing DCL. However, redistribution of positive ions in the insulator layer leads to creation of a ion concentration gradient which results in a gradual increase of the ion diffusion current in the direction opposite to the ion drift current component. The equilibrium between the two for a given temperature and electric field results in saturation of the leakage current value. DCL vs. time characteristics are described by the exponential stretched law. We found that during the initial part of ageing an exponent n = 1 applies. That corresponds to the ion drift motion only. After long-time application of the electric field at a high temperature the DCL vs. time characteristics are described by the exponential

Leakage current phenomena in Mn-doped Bi(Na,K)TiO_3-based ferroelectric thin films

International Nuclear Information System (INIS)

Walenza-Slabe, J.; Gibbons, B. J.

2016-01-01

Mn-doped 80(Bi_0_._5Na_0_._5)TiO_3-20(Bi_0_._5K_0_._5)TiO_3 thin films were fabricated by chemical solution deposition on Pt/TiO_2/SiO_2/Si substrates. Steady state and time-dependent leakage current were investigated from room temperature to 180 °C. Undoped and low-doped films showed space-charge-limited current (SCLC) at high temperatures. The electric field marking the transition from Ohmic to trap-filling-limited current increased monotonically with Mn-doping. With 2 mol. % Mn, the current was Ohmic up to 430 kV/cm, even at 180 °C. Modeling of the SCLC showed that all films exhibited shallow trap levels and high trap concentrations. In the regime of steady state leakage, there were also observations of negative differential resistivity and positive temperature coefficient of resistivity near room temperature. Both of these phenomena were confined to relatively low temperatures (below ∼60 °C). Transient currents were observed in the time-dependent leakage data, which was measured out to several hundred seconds. In the undoped films, these were found to be a consequence of oxygen vacancy migration modulating the electronic conductivity. The mobility and thermal activation energy for oxygen vacancies was extracted as μ_i_o_n ≈ 1.7 × 10"−"1"2 cm"2 V"−"1 s"−"1 and E_A_,_i_o_n ≈ 0.92 eV, respectively. The transient current displayed different characteristics in the 1 mol. % Mn-doped films which were not readily explained by oxygen vacancy migration.

Suppression of Lateral Diffusion and Surface Leakage Currents in nBn Photodetectors Using an Inverted Design

Science.gov (United States)

Du, X.; Savich, G. R.; Marozas, B. T.; Wicks, G. W.

2018-02-01

Surface leakage and lateral diffusion currents in InAs-based nBn photodetectors have been investigated. Devices fabricated using a shallow etch processing scheme that etches through the top contact and stops at the barrier exhibited large lateral diffusion current but undetectably low surface leakage. Such large lateral diffusion current significantly increased the dark current, especially in small devices, and causes pixel-to-pixel crosstalk in detector arrays. To eliminate the lateral diffusion current, two different approaches were examined. The conventional solution utilized a deep etch process, which etches through the top contact, barrier, and absorber. This deep etch processing scheme eliminated lateral diffusion, but introduced high surface current along the device mesa sidewalls, increasing the dark current. High device failure rate was also observed in deep-etched nBn structures. An alternative approach to limit lateral diffusion used an inverted nBn structure that has its absorber grown above the barrier. Like the shallow etch process on conventional nBn structures, the inverted nBn devices were fabricated with a processing scheme that only etches the top layer (the absorber, in this case) but avoids etching through the barrier. The results show that inverted nBn devices have the advantage of eliminating the lateral diffusion current without introducing elevated surface current.

Negative charging effect of traps on the gate leakage current of an AlGaN/GaN HEMT

Energy Technology Data Exchange (ETDEWEB)

Kim, J. J.; Lim, J. H.; Yang, J. W. [Chonbuk National University, Jeonju (Korea, Republic of); Stanchina, W. [University of Pittsburgh, Pittsburgh, PA (United States)

2014-08-15

The negative charging effect of surface traps on the gate leakage current of AlGaN/GaN high electron mobility transistors (HEMTs) was investigated. The gate leakage current could be decreased by two orders of magnitude by using a photo-electrochemical process to treat of the source and the drain region, but current flowed into the gate even at a negative voltage in a limited region when the measurement was executed with a gate voltage sweep from negative to positive voltage. Also the electrical characteristics of the HEMT were degraded by pulsed operation of the gate. Traps newly generated on the surface were regarded as sources for the current that flowed against the applied voltage, and the number of traps was estimated. Also, a slow transient in the drain current was confirmed based on the results of delayed sweep measurements.

The Leakage Current Improvement of a Ni-Silicided SiGe/Si Junction Using a Si Cap Layer and the PAI Technique

International Nuclear Information System (INIS)

Chang Jian-Guang; Wu Chun-Bo; Ji Xiao-Li; Ma Hao-Wen; Yan Feng; Shi Yi; Zhang Rong

2012-01-01

We investigate the leakage current of ultra-shallow Ni-silicided SiGe/Si junctions for 45 nm CMOS technology using a Si cap layer and the pre-amorphization implantation (PAI) process. It is found that with the conventional Ni silicide method, the leakage current of a p + (SiGe)—n(Si) junction is large and attributed to band-to-band tunneling and the generation-recombination process. The two leakage contributors can be suppressed quite effectively when a Si cap layer is added in the Ni silicide method. The leakage reduction is about one order of magnitude and could be associated with the suppression of the agglomeration of the Ni germano-silicide film. In addition, the PAI process after the application of a Si cap layer has little effect on improving the junction leakage but reduces the sheet resistance of the silicide film. As a result, the novel Ni silicide method using a Si cap combined with PAI is a promising choice for SiGe junctions in advanced technology. (cross-disciplinary physics and related areas of science and technology)

Leakage Current Suppression with A Novel Six-Switch Photovoltaic Grid-Connected Inverter

OpenAIRE

Wei, Baoze; Guo, Xiaoqiang; Guerrero, Josep M.; Savaghebi, Mehdi

2015-01-01

In order to solve the problem of the leakage current in non-isolated photovoltaic (PV) systems, a novel six-switch topology and control strategy are proposed in this paper. The inductor-bypass strategy solves the common-mode voltage limitation of the conventional six-switch topology in case of unmatched inductances. And the stray capacitor voltage of the non-isolated photovoltaic system is free of high frequency ripples. Theoretical analysis and simulation are carried out to verify the propos...

Calculation of Leakage Inductance for High Frequency Transformers

DEFF Research Database (Denmark)

Ouyang, Ziwei; Jun, Zhang; Hurley, William Gerard

2015-01-01

Frequency dependent leakage inductance is often observed. High frequency eddy current effects cause a reduction in leakage inductance. The proximity effect between adjacent layers is responsible for the reduction of leakage inductance. This paper gives a detailed analysis of high frequency leakag...

Total dose effects on the shallow-trench isolation leakage current characteristics in a 0.35microm SiGe BiCMOS technology

International Nuclear Information System (INIS)

Niu, G.; Mathew, S.J.; Banerjee, G.; Cressler, J.D.; Clark, S.D.; Palmer, M.J.; Subbanna, S.

1999-01-01

The effects of gamma irradiation on the Shallow-Trench Isolation (STI) leakage currents in a SiGe BiCMOS technology are investigated for the first time, and shown to be strongly dependent on the irradiation gate bias and operating substrate bias. A positive irradiation gate bias significantly enhances the STI leakage, suggesting a strong field assisted nature of the charge buildup process in the STI. Numerical simulations also suggest the existence of fixed positive charges deep in the bulk along the STI/Si interface. A negative substrate bias, however, effectively suppresses the STI leakage, and can be used to eliminate the leakage produced by the charges deep in the bulk under irradiation

Enhanced ground bounce noise reduction in a low-leakage CMOS multiplier

Science.gov (United States)

Verma, Bipin Kumar; Akashe, Shyam; Sharma, Sanjay

2015-09-01

In this paper, various parameters are used to reduce leakage power, leakage current and noise margin of circuits to enhance their performance. A multiplier is proposed with low-leakage current and low ground bounce noise for the microprocessor, digital signal processors (DSP) and graphics engines. The ground bounce noise problem appears when a conventional power-gating circuit transits from sleep-to-active mode. This paper discusses a reduction in leakage current in the stacking power-gating technique by three modes - sleep, active and sleep-to-active. The simulation results are performed on a 4 × 4 carry-save multiplier for leakage current, active power, leakage power and ground bounce noise, and comparison made for different nanoscales. Ground bounce noise is limited to 90%. The leakage current of the circuit is decimated up to 80% and the active power is reduced to 31%. We performed simulations using cadence virtuoso 180 and 45 nm at room temperature at various supply voltages.

Motor current and leakage flux signature analysis technique for condition monitoring

International Nuclear Information System (INIS)

Pillai, M.V.; Moorthy, R.I.K.; Mahajan, S.C.

1994-01-01

Till recently analysis of vibration signals was the only means available to predict the state of health of plant equipment. Motor current and leakage magnetic flux signature analysis is acquiring importance as a technique for detection of incipient damages in the electrical machines and as a supplementary technique for diagnostics of driven equipment such as centrifugal and reciprocating pumps. The state of health of the driven equipment is assessed by analysing time signal, frequency spectrum and trend analysis. For example, the pump vane frequency, piston stroke frequency, gear frequency and bearing frequencies are indicated in the current and flux spectra. By maintaining a periodic record of the amplitudes of various frequency lines in the frequency spectra, it is possible to understand the trend of deterioration of parts and components of the pump. All problems arising out of inappropriate mechanical alignment of vertical pumps are easily identified by a combined analysis of current, flux and vibration signals. It is found that current signature analysis technique is a sufficient method in itself for the analysis of state of health of reciprocating pumps and compressors. (author). 10 refs., 4 figs

New Leakage Current Particulate Matter Sensor for On-Board Diagnostics

Directory of Open Access Journals (Sweden)

Jiawei Wang

2016-01-01

Full Text Available Structure and principle of the new leakage current particulate matter (PM sensor are introduced and further study is performed on the PM sensor with the combination of numerical simulation and bench test. High voltage electrode, conductive shell, and heaters are all built-in. Based on the principle of Venturi tube and maze structure design, this sensor can detect transient PM concentrations. Internal flow field of the sensor and distribution condition of PM inside the sensor are analyzed through gas-solid two-phase flow numerical simulation. The experiment was also carried out on the whole sensor system (including mechanical and electronic circuit part and the output signals were analyzed. The results of simulation and experiment reveal the possibility of PM concentration (mass detection by the sensor.

Permanent supervision of leakage currents in low voltage installations; Supervisao permanente de correntes de fuga em instalacoes BT

Energy Technology Data Exchange (ETDEWEB)

Muhm, Helmut [W. Bender GmbH (Germany)

2010-09-15

Electromagnetic compatibility (EMC) is a premise for the electrical installations operate free of disturbances and reliably. Therefor, It is important detect dispersed leakage currents. This article show the corrective measures of this problem.

Temperature-dependent leakage current behavior of epitaxial Bi0.5Na0.5TiO3-based thin films made by pulsed laser deposition

Science.gov (United States)

Hejazi, M. M.; Safari, A.

2011-11-01

This paper discusses the electrical conduction mechanisms in a 0.88 Bi0.5Na0.5TiO3-0.08 Bi0.5K0.5TiO3-0.04 BaTiO3 thin film in the temperature range of 200-350 K. The film was deposited on a SrRuO3/SrTiO3 substrate by pulsed laser deposition technique. At all measurement temperatures, the leakage current behavior of the film matched well with the Lampert's triangle bounded by three straight lines of different slopes. The relative location of the triangle sides varied with temperature due to its effect on the density of charge carriers and un-filled traps. At low electric fields, the ohmic conduction governed the leakage mechanism. The calculated activation energy of the trap is 0.19 eV implying the presence of shallow traps in the film. With increasing the applied field, an abrupt increase in the leakage current was observed. This was attributed to a trap-filling process by the injected carriers. At sufficiently high electric fields, the leakage current obeyed the Child's trap-free square law suggesting the space charge limited current was the dominant mechanism.

Junction leakage measurements with micro four-point probes

DEFF Research Database (Denmark)

Lin, Rong; Petersen, Dirch Hjorth; Wang, Fei

2012-01-01

We present a new, preparation-free method for measuring the leakage current density on ultra-shallow junctions. The junction leakage is found by making a series of four-point sheet resistance measurements on blanket wafers with variable electrode spacings. The leakage current density is calculated...... using a fit of the measured four-point resistances to an analytical two-sheet model. The validity of the approximation involved in the two-sheet model is verified by a comparison to finite element model calculations....

Research and development of a high-temperature helium-leak detection system (joint research). Part 1 survey on leakage events and current leak detection technology

Energy Technology Data Exchange (ETDEWEB)

Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Urakami, Masao; Saisyu, Sadanori [Japan Atomic Power Co., Tokyo (Japan)

2003-03-01

In High Temperature Gas-cooled Reactors (HTGR), the detection of leakage of helium at an early stage is very important for the safety and stability of operations. Since helium is a colourless gas, it is generally difficult to identify the location and the amount of leakage when very little leakage has occurred. The purpose of this R and D is to develop a helium leak detection system for the high temperature environment appropriate to the HTGR. As the first step in the development, this paper describes the result of surveying leakage events at nuclear facilities inside and outside Japan and current gas leakage detection technology to adapt optical-fibre detection technology to HTGRs. (author)

First principle leakage current reduction technique for CMOS devices

CSIR Research Space (South Africa)

Tsague, HD

2015-12-01

Full Text Available This paper presents a comprehensive study of leakage reduction techniques applicable to CMOS based devices. In the process, mathematical equations that model the power-performance trade-offs in CMOS logic circuits are presented. From those equations...

The effect of cathode bias (field effect) on the surface leakage current of CdZnTe detectors

DEFF Research Database (Denmark)

Bolotnikov, A.E.; Chen, C.M.H.; Cook, W.R.

2003-01-01

Surface resistivity is an important parameter of multi-electrode CZT detectors such as coplanar-grid, strip, or pixel detectors. Low surface resistivity results in a high leakage current and affects the charge collection efficiency in the areas near contacts. Thus, it is always desirable to have ...

Effects of vacuum ultraviolet irradiation on trapped charges and leakage currents of low-k organosilicate dielectrics

Energy Technology Data Exchange (ETDEWEB)

Zheng, H.; Guo, X.; Pei, D.; Shohet, J. L. [Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Ryan, E. T. [GLOBALFOUNDRIES, Albany, New York 12203 (United States); Nishi, Y. [Stanford University, Stanford, California 94305 (United States)

2015-05-11

Vacuum ultraviolet (VUV) photoemission spectroscopy is utilized to investigate the distribution of trapped charges within the bandgap of low dielectric constant (low-k) organosilicate (SiCOH) materials. It was found that trapped charges are continuously distributed within the bandgap of porous SiCOH and the center of the trapped states is 1.3 eV above the valence band of the tested sample. By comparing photoemission spectroscopic results before and after VUV exposure, VUV irradiation with photon energies between 7.6 and 8.9 eV was found to deplete trapped charge while UV exposure with photon energies less than 6.0 eV induces more trapped charges in tested samples. Current-Voltage (IV) characteristics results show that the reliability of dielectrics is improved after VUV irradiation with photon energies between 7.6 and 8.9 eV, while UV exposure results in an increased level of leakage current and a decreased breakdown voltage, both of which are harmful to the reliability of the dielectric. This work shows that VUV irradiation holds the potential to substitute for UV curing in microelectronic processing to improve the reliability of low-k dielectrics by mitigating the leakage currents and trapped charges induced by UV irradiation.

Effect of incorporation of nitrogen atoms in Al2O3 gate dielectric of wide-bandgap-semiconductor MOSFET on gate leakage current and negative fixed charge

Science.gov (United States)

Kojima, Eiji; Chokawa, Kenta; Shirakawa, Hiroki; Araidai, Masaaki; Hosoi, Takuji; Watanabe, Heiji; Shiraishi, Kenji

2018-06-01

We performed first-principle calculations to investigate the effect of incorporation of N atoms into Al2O3 gate dielectrics. Our calculations show that the defect levels generated by VO in Al2O3 are the origin of the stress-induced gate leakage current and that VOVAl complexes in Al2O3 cause negative fixed charge. We revealed that the incorporation of N atoms into Al2O3 eliminates the VO defect levels, reducing the stress-induced gate leakage current. Moreover, this suppresses the formation of negatively charged VOVAl complexes. Therefore, AlON can reduce both stress-induced gate leakage current and negative fixed charge in wide-bandgap-semiconductor MOSFETs.

Apparatus for detecting leakage of liquid sodium

Science.gov (United States)

Himeno, Yoshiaki

1978-01-01

An apparatus for detecting the leakage of liquid sodium includes a cable-like sensor adapted to be secured to a wall of piping or other equipment having sodium on the opposite side of the wall, and the sensor includes a core wire electrically connected to the wall through a leak current detector and a power source. An accidental leakage of the liquid sodium causes the corrosion of a metallic layer and an insulative layer of the sensor by products resulted from a reaction of sodium with water or oxygen in the atmospheric air so as to decrease the resistance between the core wire and the wall. Thus, the leakage is detected as an increase in the leaking electrical current. The apparatus is especially adapted for use in detecting the leakage of liquid sodium from sodium-conveying pipes or equipment in a fast breeder reactor.

Analysis of Reverse-Bias Leakage Current Mechanisms in Metal/GaN Schottky Diodes

Directory of Open Access Journals (Sweden)

P. Pipinys

2010-01-01

Full Text Available Temperature-dependent reverse-bias current-voltage characteristics obtained by other researchers for Schottky diodes fabricated on GaN are reinterpreted in terms of phonon-assisted tunneling (PhAT model. Temperature dependence of reverse-bias leakage current is shown could be caused by the temperature dependence of electron tunneling rate from traps in the metal-semiconductor interface to the conduction band of semiconductor. A good fit of experimental data with the theory is received in a wide temperature range (from 80 K to 500 K using for calculation the effective mass of 0.222 me. and for the phonon energy the value of 70 meV. The temperature and bias voltages dependences of an apparent barrier height (activation energy are also explicable in the framework of the PhAT model.

Direct observation of the leakage current in epitaxial diamond Schottky barrier devices by conductive-probe atomic force microscopy and Raman imaging

Science.gov (United States)

Alvarez, J.; Boutchich, M.; Kleider, J. P.; Teraji, T.; Koide, Y.

2014-09-01

The origin of the high leakage current measured in several vertical-type diamond Schottky devices is conjointly investigated by conducting probe atomic force microscopy and confocal micro-Raman/photoluminescence imaging analysis. Local areas characterized by a strong decrease of the local resistance (5-6 orders of magnitude drop) with respect to their close surrounding have been identified in several different regions of the sample surface. The same local areas, also referenced as electrical hot-spots, reveal a slightly constrained diamond lattice and three dominant Raman bands in the low-wavenumber region (590, 914 and 1040 cm-1). These latter bands are usually assigned to the vibrational modes involving boron impurities and its possible complexes that can electrically act as traps for charge carriers. Local current-voltage measurements performed at the hot-spots point out a trap-filled-limited current as the main conduction mechanism favouring the leakage current in the Schottky devices.

Stress-induced leakage current characteristics of PMOS fabricated by a new multi-deposition multi-annealing technique with full gate last process

International Nuclear Information System (INIS)

Wang Yanrong; Yang Hong; Xu Hao; Luo Weichun; Qi Luwei; Zhang Shuxiang; Wang Wenwu; Zhu Huilong; Zhao Chao; Chen Dapeng; Ye Tianchun; Yan Jiang

2017-01-01

In the process of high- k films fabrication, a novel multi deposition multi annealing (MDMA) technique is introduced to replace simple post deposition annealing. The leakage current decreases with the increase of the post deposition annealing (PDA) times. The equivalent oxide thickness (EOT) decreases when the annealing time(s) change from 1 to 2. Furthermore, the characteristics of SILC (stress-induced leakage current) for an ultra-thin SiO 2 /HfO 2 gate dielectric stack are studied systematically. The increase of the PDA time(s) from 1 to 2 can decrease the defect and defect generation rate in the HK layer. However, increasing the PDA times to 4 and 7 may introduce too much oxygen, therefore the type of oxygen vacancy changes. (paper)

Inverse temperature dependence of reverse gate leakage current in AlGaN/GaN HEMT

International Nuclear Information System (INIS)

Kaushik, J K; Balakrishnan, V R; Muralidharan, R; Panwar, B S

2013-01-01

The experimentally observed inverse temperature dependence of the reverse gate leakage current in AlGaN/GaN HEMT is explained using a virtual gate trap-assisted tunneling model. The virtual gate is formed due to the capture of electrons by surface states in the vicinity of actual gate. The increase and decrease in the length of the virtual gate with temperature due to trap kinetics are used to explain this unusual effect. The simulation results have been validated experimentally. (paper)

PERFORMANCE OF LEAKAGE POWER MINIMIZATION TECHNIQUE FOR CMOS VLSI TECHNOLOGY

Directory of Open Access Journals (Sweden)

T. Tharaneeswaran

2012-06-01

Full Text Available Leakage power of CMOS VLSI Technology is a great concern. To reduce leakage power in CMOS circuits, a Leakage Power Minimiza-tion Technique (LPMT is implemented in this paper. Leakage cur-rents are monitored and compared. The Comparator kicks the charge pump to give body voltage (Vbody. Simulations of these circuits are done using TSMC 0.35µm technology with various operating temper-atures. Current steering Digital-to-Analog Converter (CSDAC is used as test core to validate the idea. The Test core (eg.8-bit CSDAC had power consumption of 347.63 mW. LPMT circuit alone consumes power of 6.3405 mW. This technique results in reduction of leakage power of 8-bit CSDAC by 5.51mW and increases the reliability of test core. Mentor Graphics ELDO and EZ-wave are used for simulations.

Effects of doping on ferroelectric properties and leakage current behavior of KNN-LT-LS thin films on SrTiO3 substrate

Science.gov (United States)

Abazari, M.; Safari, A.

2009-05-01

We report the effects of Ba, Ti, and Mn dopants on ferroelectric polarization and leakage current of (K0.44Na0.52Li0.04)(Nb0.84Ta0.1Sb0.06)O3 (KNN-LT-LS) thin films deposited by pulsed laser deposition. It is shown that donor dopants such as Ba2+, which increased the resistivity in bulk KNN-LT-LS, had an opposite effect in the thin film. Ti4+ as an acceptor B-site dopant reduces the leakage current by an order of magnitude, while the polarization values showed a slight degradation. Mn4+, however, was found to effectively suppress the leakage current by over two orders of magnitude while enhancing the polarization, with 15 and 23 μC/cm2 remanent and saturated polarization, whose values are ˜70% and 82% of the reported values for bulk composition. This phenomenon has been associated with the dual effect of Mn4+ in KNN-LT-LS thin film, by substituting both A- and B-site cations. A detailed description on how each dopant affects the concentrations of vacancies in the lattice is presented. Mn-doped KNN-LT-LS thin films are shown to be a promising candidate for lead-free thin films and applications.

Study of radiation-induced leakage current between adjacent devices in a CMOS integrated circuit

Institute of Scientific and Technical Information of China (English)

Ding Lili; Guo Hongxia; Chen Wei; Fan Ruyu

2012-01-01

Radiation-induced inter-device leakage is studied using an analytical model and TCAD simulation.There were some different opinions in understanding the process of defect build-up in trench oxide and parasitic leakage path turning on from earlier studies.To reanalyze this problem and make it beyond argument,every possible variable is considered using theoretical analysis,not just the change of electric field or oxide thickness independently.Among all possible inter-device leakage paths,parasitic structures with N-well as both drain and source are comparatively more sensitive to the total dose effect when a voltage discrepancy exists between the drain and source region.Since N-well regions are commonly connected to the same power supply,these kinds of structures will not be a problem in a real CMOS integrated circuit.Generally speaking,conduction paths of inter-device leakage existing in a real integrated circuit and under real electrical circumstances are not very sensitive to the total ionizing dose effect.

Inner volume leakage during integrated leakage rate testing

International Nuclear Information System (INIS)

Glover, J.P.

1987-01-01

During an integrated leak rate test (ILRT), the containment structure is maintained at test pressure with most penetrations isolated. Since penetrations typically employ dual isolation, the possibility exists for the inner isolation to leak while the outer holds. In this case, the ILRT instrumentation system would indicate containment out-leakage when, in fact, only the inner volume between closures is being pressurized. The problem is compounded because this false leakage is not readily observable outside of containment by standard leak inspection techniques. The inner volume leakage eventually subsides after the affected volumes reach test pressure. Depending on the magnitude of leakage and the size of the volumes, equalization could occur prior to the end of the pretest stabilization period, or significant false leakages may persist throughout the entire test. Two simple analyses were performed to quantify the effects of inside volume leakages. First, a lower bound for the equalization time was found. A second analysis was performed to find an approximate upper bound for the stabilization time. The results of both analyses are shown

On Probability Leakage

OpenAIRE

Briggs, William M.

2012-01-01

The probability leakage of model M with respect to evidence E is defined. Probability leakage is a kind of model error. It occurs when M implies that events $y$, which are impossible given E, have positive probability. Leakage does not imply model falsification. Models with probability leakage cannot be calibrated empirically. Regression models, which are ubiquitous in statistical practice, often evince probability leakage.

Direct observation of the leakage current in epitaxial diamond Schottky barrier devices by conductive-probe atomic force microscopy and Raman imaging

International Nuclear Information System (INIS)

Alvarez, J; Boutchich, M; Kleider, J P; Teraji, T; Koide, Y

2014-01-01

The origin of the high leakage current measured in several vertical-type diamond Schottky devices is conjointly investigated by conducting probe atomic force microscopy and confocal micro-Raman/photoluminescence imaging analysis. Local areas characterized by a strong decrease of the local resistance (5–6 orders of magnitude drop) with respect to their close surrounding have been identified in several different regions of the sample surface. The same local areas, also referenced as electrical hot-spots, reveal a slightly constrained diamond lattice and three dominant Raman bands in the low-wavenumber region (590, 914 and 1040 cm −1 ). These latter bands are usually assigned to the vibrational modes involving boron impurities and its possible complexes that can electrically act as traps for charge carriers. Local current–voltage measurements performed at the hot-spots point out a trap-filled-limited current as the main conduction mechanism favouring the leakage current in the Schottky devices. (paper)

On the problem of internal optical loss and current leakage in laser heterostructures based on AlGaInAs/InP solid solutions

International Nuclear Information System (INIS)

Veselov, D. A.; Shashkin, I. S.; Bakhvalov, K. V.; Lyutetskiy, A. V.; Pikhtin, N. A.; Rastegaeva, M. G.; Slipchenko, S. O.; Bechvay, E. A.; Strelets, V. A.; Shamakhov, V. V.; Tarasov, I. S.

2016-01-01

Semiconductor lasers based on MOCVD-grown AlGaInAs/InP separate-confinement heterostructures are studied. It is shown that raising only the energy-gap width of AlGaInAs-waveguides without the introduction of additional barriers results in more pronounced current leakage into the cladding layers. It is found that the introduction of additional barrier layers at the waveguide–cladding-layer interface blocks current leakage into the cladding layers, but results in an increase in the internal optical loss with increasing pump current. It is experimentally demonstrated that the introduction of blocking layers makes it possible to obtain maximum values of the internal quantum efficiency of stimulated emission (92%) and continuouswave output optical power (3.2 W) in semiconductor lasers in the eye-safe wavelength range (1400–1600 nm).

On the problem of internal optical loss and current leakage in laser heterostructures based on AlGaInAs/InP solid solutions

Energy Technology Data Exchange (ETDEWEB)

Veselov, D. A., E-mail: dmitriy90@list.ru; Shashkin, I. S.; Bakhvalov, K. V.; Lyutetskiy, A. V.; Pikhtin, N. A.; Rastegaeva, M. G.; Slipchenko, S. O.; Bechvay, E. A.; Strelets, V. A.; Shamakhov, V. V.; Tarasov, I. S. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

2016-09-15

Semiconductor lasers based on MOCVD-grown AlGaInAs/InP separate-confinement heterostructures are studied. It is shown that raising only the energy-gap width of AlGaInAs-waveguides without the introduction of additional barriers results in more pronounced current leakage into the cladding layers. It is found that the introduction of additional barrier layers at the waveguide–cladding-layer interface blocks current leakage into the cladding layers, but results in an increase in the internal optical loss with increasing pump current. It is experimentally demonstrated that the introduction of blocking layers makes it possible to obtain maximum values of the internal quantum efficiency of stimulated emission (92%) and continuouswave output optical power (3.2 W) in semiconductor lasers in the eye-safe wavelength range (1400–1600 nm).

Millennial-scale Agulhas Current variability and its implications for salt-leakage through the Indian–Atlantic Ocean Gateway

NARCIS (Netherlands)

Simon, M.H.; Arthur, K.L.; Hall, I.R.; Peeters, F.J.C.; Loveday, B.R.; Barker, S.; Zahn, R.

2013-01-01

The inter-ocean exchange of warm and salt-enriched waters around South Africa (Agulhas leakage), may have played an important role in the mechanism of deglaciations. Paleoceanographic reconstructions from the Agulhas leakage corridor show that leakage maxima occurred during glacial terminations.

Leakage current suppression with a combination of planarized gate and overlap/off-set structure in metal-induced laterally crystallized polycrystalline-silicon thin-film transistors

Science.gov (United States)

Chae, Hee Jae; Seok, Ki Hwan; Lee, Sol Kyu; Joo, Seung Ki

2018-04-01

A novel inverted staggered metal-induced laterally crystallized (MILC) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) with a combination of a planarized gate and an overlap/off-set at the source-gate/drain-gate structure were fabricated and characterized. While the MILC process is advantageous for fabricating inverted staggered poly-Si TFTs, MILC TFTs reveal higher leakage current than TFTs crystallized by other processes due to their high trap density of Ni contamination. Due to this drawback, the planarized gate and overlap/off-set structure were applied to inverted staggered MILC TFTs. The proposed device shows drastic suppression of leakage current and pinning phenomenon by reducing the lateral electric field and the space-charge limited current from the gate to the drain.

Sistem Proteksi Arus Bocor Menggunakan Earth Leakage Circuit Breaker Berbasis Arduino

Directory of Open Access Journals (Sweden)

Syukriyadin Syukriyadin

2017-02-01

Full Text Available Touching a live part of electrical equipment either intentionally or unintentionally can cause an electric shock. The touch can occur directly or indirectly and results in the flow of electric current through the human body to the ground. This electric current is known as the leakage current and can have fatal effects on the human body such as burns, cramps, faint and death. This paper aims to design a prototype protection model of the earth leakage circuit breaker device based on Arduino (ELCBA to protect the human body from the electrical hazards. The performance of the ELCBA is investigated by detecting the earth leakage current to the grounding system (TN.  The prototype is designed and simulated by using Proteus software. Based on the response test carried out on the prototype, it can be concluded that the ELCBA can operate properly to disconnect the electric circuit if the leakage current is detected greater than or equal to 30 mA with a time delay of 15 ms and to reclose the circuit again after 5 minutes.

Land-use Leakage

Energy Technology Data Exchange (ETDEWEB)

Calvin, Katherine V.; Edmonds, James A.; Clarke, Leon E.; Bond-Lamberty, Benjamin; Kim, Son H.; Wise, Marshall A.; Thomson, Allison M.; Kyle, G. Page

2009-12-01

Leakage occurs whenever actions to mitigate greenhouse gas emissions in one part of the world unleash countervailing forces elsewhere in the world so that reductions in global emissions are less than emissions mitigation in the mitigating region. While many researchers have examined the concept of industrial leakage, land-use policies can also result in leakage. We show that land-use leakage is potentially as large as or larger than industrial leakage. We identify two potential land-use leakage drivers, land-use policies and bioenergy. We distinguish between these two pathways and run numerical experiments for each. We also show that the land-use policy environment exerts a powerful influence on leakage and that under some policy designs leakage can be negative. International “offsets” are a potential mechanism to communicate emissions mitigation beyond the borders of emissions mitigating regions, but in a stabilization regime designed to limit radiative forcing to 3.7 2/m2, this also implies greater emissions mitigation commitments on the part of mitigating regions.

Evaluation of Information Leakage from Cryptographic Hardware via Common-Mode Current

Science.gov (United States)

Hayashi, Yu-Ichi; Homma, Naofumi; Mizuki, Takaaki; Sugawara, Takeshi; Kayano, Yoshiki; Aoki, Takafumi; Minegishi, Shigeki; Satoh, Akashi; Sone, Hideaki; Inoue, Hiroshi

This paper presents a possibility of Electromagnetic (EM) analysis against cryptographic modules outside their security boundaries. The mechanism behind the information leakage is explained from the view point of Electromagnetic Compatibility: electric fluctuation released from cryptographic modules can conduct to peripheral circuits based on ground bounce, resulting in radiation. We demonstrate the consequence of the mechanism through experiments where the ISO/IEC standard block cipher AES (Advanced Encryption Standard) is implemented on an FPGA board and EM radiations from power and communication cables are measured. Correlation Electromagnetic Analysis (CEMA) is conducted in order to evaluate the information leakage. The experimental results show that secret keys are revealed even though there are various disturbing factors such as voltage regulators and AC/DC converters between the target module and the measurement points. We also discuss information-suppression techniques as electrical-level countermeasures against such CEMAs.

A Minimum Leakage Quasi-Static RAM Bitcell

Directory of Open Access Journals (Sweden)

Adam Teman

2011-05-01

Full Text Available As SRAMs continue to grow and comprise larger percentages of the area and power consumption in advanced systems, the need to minimize static currents becomes essential. This brief presents a novel 9T Quasi-Static RAM Bitcell that provides aggressive leakage reduction and high write margins. The quasi-static operation method of this cell, based on internal feedback and leakage ratios, minimizes static power while maintaining sufficient, albeit depleted, noise margins. This paper presents the concept of the novel cell, and discusses the stability of the cell under hold, read and write operations. The cell was implemented in a low-power 40 nm TSMC process, showing as much as a 12× reduction in leakage current at typical conditions, as compared to a standard 6T or 8T bitcell at the same supply voltage. The implemented cell showed full functionality under global and local process variations at nominal and low voltages, as low as 300 mV.

Macrophage migration inhibitory factor induces vascular leakage via autophagy

Directory of Open Access Journals (Sweden)

Hong-Ru Chen

2015-01-01

Full Text Available Vascular leakage is an important feature of acute inflammatory shock, which currently has no effective treatment. Macrophage migration inhibitory factor (MIF is a pro-inflammatory cytokine that can induce vascular leakage and plays an important role in the pathogenesis of shock. However, the mechanism of MIF-induced vascular leakage is still unclear. In this study, using recombinant MIF (rMIF, we demonstrated that MIF induced disorganization and degradation of junction proteins and increased the permeability of human endothelial cells in vitro. Western blotting analysis showed that rMIF treatment induced LC3 conversion and p62 degradation. Inhibition of autophagy with a PI3K inhibitor (3-MA, a ROS scavenger (NAC or autophagosomal-lysosomal fusion inhibitors (bafilomycin A1 and chloroquine rescued rMIF-induced vascular leakage, suggesting that autophagy mediates MIF-induced vascular leakage. The potential involvement of other signaling pathways was also studied using different inhibitors, and the results suggested that MIF-induced vascular leakage may occur through the ERK pathway. In conclusion, we showed that MIF triggered autophagic degradation of endothelial cells, resulting in vascular leakage. Inhibition of MIF-induced autophagy may provide therapeutic targets against vascular leakage in inflammatory shock.

Forest Carbon Leakage Quantification Methods and Their Suitability for Assessing Leakage in REDD

Directory of Open Access Journals (Sweden)

Sabine Henders

2012-01-01

Full Text Available This paper assesses quantification methods for carbon leakage from forestry activities for their suitability in leakage accounting in a future Reducing Emissions from Deforestation and Forest Degradation (REDD mechanism. To that end, we first conducted a literature review to identify specific pre-requisites for leakage assessment in REDD. We then analyzed a total of 34 quantification methods for leakage emissions from the Clean Development Mechanism (CDM, the Verified Carbon Standard (VCS, the Climate Action Reserve (CAR, the CarbonFix Standard (CFS, and from scientific literature sources. We screened these methods for the leakage aspects they address in terms of leakage type, tools used for quantification and the geographical scale covered. Results show that leakage methods can be grouped into nine main methodological approaches, six of which could fulfill the recommended REDD leakage requirements if approaches for primary and secondary leakage are combined. The majority of methods assessed, address either primary or secondary leakage; the former mostly on a local or regional and the latter on national scale. The VCS is found to be the only carbon accounting standard at present to fulfill all leakage quantification requisites in REDD. However, a lack of accounting methods was identified for international leakage, which was addressed by only two methods, both from scientific literature.

Modeling valve leakage

International Nuclear Information System (INIS)

Bell, S.R.; Rohrscheib, R.

1994-01-01

The American Society of Mechanical Engineers (ASME) Code requires individual valve leakage testing for Category A valves. Although the U.S. Nuclear Regulatory Commission (USNRC) has recognized that it is more appropriate to test containment isolation valves in groups, as allowed by 10 CFR 50, Appendix J, a utility seeking relief from these Code requirements must provide technical justification for the relief and establish a conservative alternate acceptance criteria. In order to provide technical justification for group testing of containment isolation valves, Illinois Power developed a calculation (model) for determining the size of a leakage pathway in a valve disc or seat for a given leakage rate. The model was verified experimentally by machining leakage pathways of known size and then measuring the leakage and comparing this value to the calculated value. For the range of values typical of leakage rate testing, the correlation between the experimental values and calculated values was quote good. Based upon these results, Illinois Power established a conservative acceptance criteria for all valves in the inservice testing (IST) program and was granted relief by the USNRC from the individual leakage testing requirements of the ASME Code. This paper presents the results of Illinois Power's work in the area of valve leakage rate testing

Effect of gamma irradiation on leakage current in CMOS read-out chips for the ATLAS upgrade silicon strip tracker at the HL-LHC

CERN Document Server

Stucci, Stefania Antonia; Lynn, Dave; Kierstead, James; Kuczewski, Philip; van Nieuwenhuizen, Gerrit J; Rosin, Guy; Tricoli, Alessandro

2017-01-01

The increase of the leakage current of NMOS transistors in detector readout chips in certain 130 nm CMOS technologies during exposure to ionising radiation needs special consideration in the design of detector systems, as this can result in a large increase of the supply current and power dissipation. As part of the R&D; program for the upgrade of the ATLAS inner detector tracker for the High Luminosity upgrade of the LHC at CERN, a dedicated set of irradiations have been carried out with the $^60$Co gamma-ray source at the Brookhaven National Laboratory. Measurements will be presented that characterise the increase in the digital leakage current in the 130 nm-technology ABC130 readout chips. The variation of the current as a function of time and total ionising dose has been studied under various conditions of dose rate, temperature and power applied to the chip. The range of variation of dose rates and temperatures has been set to be close to those expected at the High Luminosity LHC, i.e. in the range 0...

Experimental investigation of localized stress-induced leakage current distribution in gate dielectrics using array test circuit

Science.gov (United States)

Park, Hyeonwoo; Teramoto, Akinobu; Kuroda, Rihito; Suwa, Tomoyuki; Sugawa, Shigetoshi

2018-04-01

Localized stress-induced leakage current (SILC) has become a major problem in the reliability of flash memories. To reduce it, clarifying the SILC mechanism is important, and statistical measurement and analysis have to be carried out. In this study, we applied an array test circuit that can measure the SILC distribution of more than 80,000 nMOSFETs with various gate areas at a high speed (within 80 s) and a high accuracy (on the 10-17 A current order). The results clarified that the distributions of localized SILC in different gate areas follow a universal distribution assuming the same SILC defect density distribution per unit area, and the current of localized SILC defects does not scale down with the gate area. Moreover, the distribution of SILC defect density and its dependence on the oxide field for measurement (E OX-Measure) were experimentally determined for fabricated devices.

Leakage current analysis for dislocations in Na-flux GaN bulk single crystals by conductive atomic force microscopy

Science.gov (United States)

Hamachi, T.; Takeuchi, S.; Tohei, T.; Imanishi, M.; Imade, M.; Mori, Y.; Sakai, A.

2018-04-01

The mechanisms associated with electrical conduction through individual threading dislocations (TDs) in a Na-flux GaN crystal grown with a multipoint-seed-GaN technique were investigated by conductive atomic force microscopy (C-AFM). To focus on individual TDs, dislocation-related etch pits (DREPs) were formed on the Na-flux GaN surface by wet chemical etching, after which microscopic Pt electrodes were locally fabricated on the DREPs to form conformal contacts to the Na-flux GaN crystal, using electron beam assisted deposition. The C-AFM data clearly demonstrate that the leakage current flows through the individual TD sites. It is also evident that the leakage current and the electrical conduction mechanism vary significantly based on the area within the Na-flux GaN crystal where the TDs are formed. These regions include the c-growth sector (cGS) in which the GaN grows in the [0001 ] direction on top of the point-seed with a c-plane growth front, the facet-growth sector (FGS) in which the GaN grows with {10 1 ¯ 1 } facets on the side of the cGS, the boundary region between the cGS and FGS (BR), and the coalescence boundary region between FGSs (CBR). The local current-voltage (I-V) characteristics of the specimen demonstrate space charge limited current conduction and conduction related to band-like trap states associated with TDs in the FGS, BR, and CBR. A detailed analysis of the I-V data indicates that the electrical conduction through TDs in the cGS may proceed via the Poole-Frenkel emission mechanism.

Suppression of photo-leakage current in amorphous silicon thin-film transistors by n-doped nanocrystalline silicon

International Nuclear Information System (INIS)

Lin, Hung-Chien; Ho, King-Yuan; Hsu, Chih-Chieh; Yan, Jing-Yi; Ho, Jia-Chong

2011-01-01

The reduction of photo-leakage current of amorphous silicon thin-film transistors (a-Si TFTs) is investigated and is found to be successfully suppressed by the use of an n-doped nanocrystalline silicon layer (n+ nc-Si) as an ohmic contact layer. The shallow-level defects of n+ nc-Si can become trapping centres of photo-induced electrons as the a-Si TFT is operated under light illumination. A lower oxygen concentration during n+ nc-Si deposition can increase the creation of shallow-level defects and improve the contrast ratio of active matrix organic light-emitting diode panels.

Sistem Proteksi Arus Bocor Menggunakan Earth Leakage Circuit Breaker Berbasis Arduino

OpenAIRE

Syukriyadin, Syukriyadin

2016-01-01

Touching a live part of electrical equipment either intentionally or unintentionally can cause an electric shock. The touch can occur directly or indirectly and results in the flow of electric current through the human body to the ground. This electric current is known as the leakage current and can have fatal effects on the human body such as burns, cramps, faint and death. This paper aims to design a prototype protection model of the earth leakage circuit breaker device based on Arduino (EL...

Artificial-Crack-Behavior Test Evaluation of the Water-Leakage Repair Materials Used for the Repair of Water-Leakage Cracks in Concrete Structures

Directory of Open Access Journals (Sweden)

Soo-Yeon Kim

2016-09-01

Full Text Available There are no existing standard test methods at home and abroad that can verify the performance of water leakage repair materials, and it is thus very difficult to perform quality control checks in the field of water leakage repair. This study determined that the key factors that have the greatest impact on the water leakage repair materials are the micro-behaviors of cracks, and proposed an artificial-crack-behavior test method for the performance verification of the repair materials. The performance of the 15 kinds of repair materials that are currently being used in the field of water leakage repair was evaluated by applying the proposed test method. The main aim of such a test method is to determine if there is water leakage by injecting water leakage repair materials into a crack behavior test specimen with an artificial 5-mm crack width, applying a 2.5 mm vertical behavior load at 100 cycles, and applying 0.3 N/mm2 constant water pressure. The test results showed that of the 15 kinds of repair materials, only two effectively sealed the crack and thus stopped the water leakage. The findings of this study confirmed the effectiveness of the proposed artificial-crack-behavior test method and suggest that it can be used as a performance verification method for checking the responsiveness of the repair materials being used in the field of water leakage repair to the repetitive water leakage behaviors that occur in concrete structures. The study findings further suggest that the use of the proposed test method makes it possible to quantify the water leakage repair quality control in the field.

Study on the low leakage current of an MIS structure fabricated by ICP-CVD

Energy Technology Data Exchange (ETDEWEB)

Tsai, S-Y; Hon, M-H [Department of Materials Science and Engineering, National Cheng Kung University, 1, Ta-Hsueh Road, Tainan, 701 Taiwan (China); Lu, Y-M, E-mail: ymlumit@yahoo.com.tw

2008-03-15

As the dimensions of electric devices continue to shrink, it is becoming increasingly important to understand how to obtain good quality gate oxide film materials wilth higher carrier mobility, lower leakage current and greater reliability. All of them have become major concerns in the fabrication of thin film oxide transistors. A novel film deposition method called Inductively Coupled Plasma-Chemical Vapor Deposition (ICP-CVD) has received attraction in the semiconductor industry, because it can be capable of generating high density plasmas at extremely low temperature, resulting in less ion bombardment of the material surface. In this work, we present the results of crystallized silicon dioxide films deposited by inductively coupled plasma chemical vapor deposition technique at an extremely low temperature of 90 deg. C. The value of the refractive index of the crystallized ICP-CVD SiO{sub 2} film depends on the r.f. power of the ICP system, and approximates to be 1.46. This value is comparable to that of SiO{sub 2} films prepared by thermal oxidation. As the r.f. power of ICP applied more than 1250 Watts, still only the (111) diffraction peak is observed by XRD, which implies a very strong preferred orientation or single crystal structure. Too low or too high r.f. power both produces amorphous SiO{sub 2} films. From the I-V curve, the MIS device with a SiO{sub 2} dielectric film has a lower leakage current density of 6.8x10{sup -8}A/cm{sup 2} at 1V as the film prepared at 1750 watts. The highest breakdown field in this study is 15.8 MV/cm. From the FTIR analysis, it was found that more hydrogen atoms incorporate into films and form Si-OH bonds as the r.f. power increases. The existence of Si-OH bonds leads to a poor reliability of the MIS device.

Defect generation and activation processes in HfO{sub 2} thin films: Contributions to stress-induced leakage currents

Energy Technology Data Exchange (ETDEWEB)

Oettking, Rolf; Leitsmann, Roman; Lazarevic, Florian; Plaenitz, Philipp [AQcomputare, Business Unit MATcalc, Chemnitz (Germany); Kupke, Steve; Roll, Guntrade; Slesazeck, Stefan [NaMLab gGmbH, Dresden (Germany); Nadimi, Ebrahim [AQcomputare, Business Unit MATcalc, Chemnitz (Germany); K.N. Toosi University of Technology, Faculty of Electrical Engineering, Tehran (Iran, Islamic Republic of); Trentzsch, Martin [Globalfoundries Dresden, Dresden (Germany); Mikolajick, Thomas [Technische Universitaet Dresden, Fakultaet Elektrotechnik und Informationstechnik, Institut fuer Halbleiter- und Mikrosystemtechnik, Dresden (Germany)

2015-03-01

An important source of degradation in thin dielectric material layers is the generation and migration of oxygen vacancies. We investigated the formation of Frenkel pairs (FPs) in HfO{sub 2} as the first structural step for the creation of new defects as well as the migration of preexisting and newly built oxygen vacancies by nudged elastic band (NEB) calculations and stress induced leakage current (SILC) experiments. The analysis indicates, that for neutral systems no stable intimate FPs are built, whereas for the charge states q = ± 2 FPs are formed at threefold and at fourfold coordinated oxygen lattice sites. Their generation and annihilation rate are in equilibrium according to the Boltzmann statistics. Distant FPs (stable defects) are unlikely to build due to high formation energies and therefore cannot be accounted for the measured gate leakage current increase of nMOSFETs under constant voltage stress. The negatively charged oxygen vacancies were found to be very immobile in contrast to positively charged V{sub 0}'s with a low migration barrier that coincides well with the experimentally obtained activation energy. We show that rather the activation of preexisting defects and migration towards the interface than the defect generation are the cause for the gate oxide degradation. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Carrier Transport of Silver Nanowire Contact to p-GaN and its Influence on Leakage Current of LEDs

Science.gov (United States)

Oh, Munsik; Kang, Jae-Wook; Kim, Hyunsoo

2018-03-01

The authors investigated the silver nanowires (AgNWs) contact formed on p-GaN. Transmission line model applied to the AgNWs contact to p-GaN produced near ohmic contact with a specific contact resistance (ρ sc) of 10-1˜10-4 Ω·cm2. Noticeably, the contact resistance had a strong bias-voltage (or current-density) dependence associated with a local joule heating effect. Current-voltage-temperature (I-V-T) measurement revealed a strong temperature dependence with respect to ρ sc, indicating that the temperature played a key role of an enhanced carrier transport. The local joule heating at AgNW/GaN interface, however, resulted in a generation of leakage current of light-emitting diodes (LEDs) caused by degradation of AgNW contact.

Leakage characterization of top select transistor for program disturbance optimization in 3D NAND flash

Science.gov (United States)

Zhang, Yu; Jin, Lei; Jiang, Dandan; Zou, Xingqi; Zhao, Zhiguo; Gao, Jing; Zeng, Ming; Zhou, Wenbin; Tang, Zhaoyun; Huo, Zongliang

2018-03-01

In order to optimize program disturbance characteristics effectively, a characterization approach that measures top select transistor (TSG) leakage from bit-line is proposed to quantify TSG leakage under program inhibit condition in 3D NAND flash memory. Based on this approach, the effect of Vth modulation of two-cell TSG on leakage is evaluated. By checking the dependence of leakage and corresponding program disturbance on upper and lower TSG Vth, this approach is validated. The optimal Vth pattern with high upper TSG Vth and low lower TSG Vth has been suggested for low leakage current and high boosted channel potential. It is found that upper TSG plays dominant role in preventing drain induced barrier lowering (DIBL) leakage from boosted channel to bit-line, while lower TSG assists to further suppress TSG leakage by providing smooth potential drop from dummy WL to edge of TSG, consequently suppressing trap assisted band-to-band tunneling current (BTBT) between dummy WL and TSG.

Estimation of leakage power and delay in CMOS circuits using parametric variation

Directory of Open Access Journals (Sweden)

Preeti Verma

2016-09-01

Full Text Available With the advent of deep-submicron technologies, leakage power dissipation is a major concern for scaling down portable devices that have burst-mode type integrated circuits. In this paper leakage reduction technique HTLCT (High Threshold Leakage Control Transistor is discussed. Using high threshold transistors at the place of low threshold leakage control transistors, result in more leakage power reduction as compared to LCT (leakage control transistor technique but at the scarifies of area and delay. Further, analysis of effect of parametric variation on leakage current and propagation delay in CMOS circuits is performed. It is found that the leakage power dissipation increases with increasing temperature, supply voltage and aspect ratio. However, opposite pattern is noticed for the propagation delay. Leakage power dissipation for LCT NAND gate increases up to 14.32%, 6.43% and 36.21% and delay decreases by 22.5%, 42% and 9% for variation of temperature, supply voltage and aspect ratio. Maximum peak of equivalent output noise is obtained as 127.531 nV/Sqrt(Hz at 400 mHz.

FNR demonstration experiments Part I: Beam port leakage currents and spectra

International Nuclear Information System (INIS)

Wehe, D.K.; King, J.S.

1983-01-01

The goal of the NR-LEU experimental program has been to measure the changes in numerous reactor characteristics when the conventional HEU core is replaced by a complete LEU fueled core or by a single LEU element in the normal HEU core. We have observed comparisons in a) thermal flux intensity, spatial distribution and cadmium ratios, both in the core and in the light and heavy water reflectors, b) fast flux intensity and spectral shape at a special element within the core, c) the thermal leakage flux intensity at the exit positions of several beam ports and its spectral shape at one beam port, d) shim and control rod worths, e) temperature coefficient of reactivity, and f) xenon poison worth. The NR is a 2 MW light water pool reactor, reflected on three faces by light water and on one face by D 2 O, composed of MTR plate fuel elements. Figure shows a plan view of the core grid, D 2 O reflector tank, and beam ports. The conventional HEU fuel element contains eighteen MTR Al plates 30 in x 24 in x 0.06 in. The center 0.02 in of each plate is 93% U-235 enriched UAl x . A normal equilibrium HEU core loading is outlined. Each new HEU element contains ∼ 140 grams of U-235. The LEU low enrichment fuel retains the same plate and element geometry but the fuel is contained in a central 0.03 in thick UA l x matrix with 19.5% U-235 enrichment. Each new LEU element contains ov 167.3 grams U-235. In-core neutron fluxes were routinely mapped by a rhodium SPND and by many wire and foil activations. The same data, but in more restricted positions, were obtained through the light water reflector (south) and D 2 O reflector tank (north). Beam port leakage currents were measured during all power cycles, by transmission fission chambers at the exits of ports GI, and J, by a B3 detector at A-port, and by a prompt detector at the F-port exit. Thermal neutron spectra for both HEU and LEU cores were measured at I port using a single crystal silicon diffractometer. These measurements

Practical Leakage-Resilient Symmetric Cryptography

DEFF Research Database (Denmark)

Faust, Sebastian; Pietrzak, Krzysztof; Schipper, Joachim

2012-01-01

Leakage resilient cryptography attempts to incorporate side-channel leakage into the black-box security model and designs cryptographic schemes that are provably secure within it. Informally, a scheme is leakage-resilient if it remains secure even if an adversary learns a bounded amount of arbitr......Leakage resilient cryptography attempts to incorporate side-channel leakage into the black-box security model and designs cryptographic schemes that are provably secure within it. Informally, a scheme is leakage-resilient if it remains secure even if an adversary learns a bounded amount...

Model for Electromagnetic Information Leakage

OpenAIRE

Mao Jian; Li Yongmei; Zhang Jiemin; Liu Jinming

2013-01-01

Electromagnetic leakage will happen in working information equipments; it could lead to information leakage. In order to discover the nature of information in electromagnetic leakage, this paper combined electromagnetic theory with information theory as an innovative research method. It outlines a systematic model of electromagnetic information leakage, which theoretically describes the process of information leakage, intercept and reproduction based on electromagnetic radiation, and ana...

A Grid Connected Transformerless Inverter and its Model Predictive Control Strategy with Leakage Current Elimination Capability

Directory of Open Access Journals (Sweden)

J. Fallah Ardashir

2017-06-01

Full Text Available This paper proposes a new single phase transformerless Photovoltaic (PV inverter for grid connected systems. It consists of six power switches, two diodes, one capacitor and filter at the output stage. The neutral of the grid is directly connected to the negative terminal of the source. This results in constant common mode voltage and zero leakage current. Model Predictive Controller (MPC technique is used to modulate the converter to reduce the output current ripple and filter requirements. The main advantages of this inverter are compact size, low cost, flexible grounding configuration. Due to brevity, the operating principle and analysis of the proposed circuit are presented in brief. Simulation and experimental results of 200W prototype are shown at the end to validate the proposed topology and concept. The results obtained clearly verifies the performance of the proposed inverter and its practical application for grid connected PV systems.

ATR confinement leakage determination

International Nuclear Information System (INIS)

Kuan, P.; Buescher, B.J.

1998-01-01

The air leakage rate from the Advanced Test Reactor (ATR) confinement is an important parameter in estimating hypothesized accidental releases of radiation to the environment. The leakage rate must be determined periodically to assure that the confinement has not degraded with time and such determination is one of the technical safety requirements of ATR operation. This paper reviews the methods of confinement leakage determination and presents an analysis of leakage determination under windy conditions, which can complicate the interpretation of the determined leakage rates. The paper also presents results of analyses of building air exchange under windy conditions. High wind can enhance air exchange and this could increase the release rates of radioisotopes following an accident

Leakage pattern of linear accelerator treatment heads from multiple vendors

International Nuclear Information System (INIS)

Lonski, P.R.; Taylor, M.L.; Franich, R.D.; Harty, P.; Clements, N.; Kron, T.

2011-01-01

Full text: Patient life expectancy post-radiotherapy is becoming longer. Therefore, secondary cancers caused by radiotherapy treatment have more time to develop. Increasing attention is being given to out-of-field dose resulting from scatter and accelerator head leakage. Dose leakage from equivalent positions on Varian600C, Varian21-X, Siemens Primus and Elekta Synergy-II linacs were measured with TLD 1 00 H dosimeter chips and compared. Treatment parameters such as field size and beam energy were altered. Leakage doses are presented as a percentage of the dose to isocentre (5 Gy). Results illustrate significant variations in leakage dose between linac models where no model emits consistently lower amounts of radiation leakage for all treatment parameters. Results are shown below. Leakage through the collimator assembly in different units is varying as a function of location and unit design by more than a factor of 10. Differences are more pronounced in comparing Varian or Elekta models, which are fitted with an additional collimator separate from the MLC leaves, to the Siemens model, which uses MLC leaves as its only secondary collimator. Further measurements are currently being taken at the patient plane with a directional detector system to determine the spatial distribution of high leakage sources.

Universal leakage elimination

International Nuclear Information System (INIS)

Byrd, Mark S.; Lidar, Daniel A.; Wu, L.-A.; Zanardi, Paolo

2005-01-01

'Leakage' errors are particularly serious errors which couple states within a code subspace to states outside of that subspace, thus destroying the error protection benefit afforded by an encoded state. We generalize an earlier method for producing leakage elimination decoupling operations and examine the effects of the leakage eliminating operations on decoherence-free or noiseless subsystems which encode one logical, or protected qubit into three or four qubits. We find that by eliminating a large class of leakage errors, under some circumstances, we can create the conditions for a decoherence-free evolution. In other cases we identify a combined decoherence-free and quantum error correcting code which could eliminate errors in solid-state qubits with anisotropic exchange interaction Hamiltonians and enable universal quantum computing with only these interactions

Super high voltage Schottky diode with low leakage current for x- and γ-ray detector application

International Nuclear Information System (INIS)

Kosyachenko, L. A.; Sklyarchuk, V. M.; Sklyarchuk, O. F.; Maslyanchuk, O. L.; Gnatyuk, V. A.; Aoki, T.

2009-01-01

A significant improvement in x-/γ-ray detector performance has been achieved by forming both rectifying and near-Ohmic contacts by the deposition of Ni on opposite surfaces of semi-insulating CdTe crystals pretreated by special chemical etching and Ar-ion bombardment with different parameters. The reduced injection of the minority carriers from the near-Ohmic contact in the neutral part of the diode provides low leakage current even at high bias ( 2 at 2000 V and 293 K). The electrical properties of the detectors are well described quantitatively by the generation-recombination Sah-Noyce-Shockley theory excepting the high reverse voltage range where some injection of minority carriers takes place

Low-leakage-current AlGaN/GaN HEMTs on Si substrates with partially Mg-doped GaN buffer layer by metal organic chemical vapor deposition

International Nuclear Information System (INIS)

Li Ming; Wang Yong; Wong Kai-Ming; Lau Kei-May

2014-01-01

High-performance low-leakage-current AlGaN/GaN high electron mobility transistors (HEMTs) on silicon (111) substrates grown by metal organic chemical vapor deposition (MOCVD) with a novel partially Magnesium (Mg)-doped GaN buffer scheme have been fabricated successfully. The growth and DC results were compared between Mg-doped GaN buffer layer and a unintentionally one. A 1-μm gate-length transistor with Mg-doped buffer layer exhibited an OFF-state drain leakage current of 8.3 × 10 −8 A/mm, to our best knowledge, which is the lowest value reported for MOCVD-grown AlGaN/GaN HEMTs on Si featuring the same dimension and structure. The RF characteristics of 0.25-μm gate length T-shaped gate HEMTs were also investigated

[Bile leakage after liver resection: A retrospective cohort study].

Science.gov (United States)

Menclová, K; Bělina, F; Pudil, J; Langer, D; Ryska, M

2015-12-01

Many previous reports have focused on bile leakage after liver resection. Despite the improvements in surgical techniques and perioperative care the incidence of this complication rather keeps increasing. A number of predictive factors have been analyzed. There is still no consensus regarding their influence on the formation of bile leakage. The objective of our analysis was to evaluate the incidence of bile leakage, its impact on mortality and duration of hospitalization at our department. At the same time, we conducted an analysis of known predictive factors. The authors present a retrospective review of the set of 146 patients who underwent liver resection at the Department of Surgery of the 2nd Faculty of Medicine of the Charles University and Central Military Hospital Prague, performed between 20102013. We used the current ISGLS (International Study Group of Liver Surgery) classification to evaluate the bile leakage. The severity of this complication was determined according to the Clavien-Dindo classification system. Statistical significance of the predictive factors was determined using Fishers exact test and Students t-test. The incidence of bile leakage was 21%. According to ISGLS classification the A, B, and C rates were 6.5%, 61.2%, and 32.3%, respectively. The severity of bile leakage according to the Clavien-Dindo classification system - I-II, IIIa, IIIb, IV and V rates were 19.3%, 42%, 9.7%, 9.7%, and 19.3%, respectively. We determined the following predictive factors as statistically significant: surgery for malignancy (pBile leakage significantly prolonged hospitalization time (pbile leakage the perioperative mortality was 23 times higher (pBile leakage is one of the most serious complications of liver surgery. Most of the risk factors are not easily controllable and there is no clear consensus on their influence. Intraoperative leak tests could probably reduce the incidence of bile leakage. In the future, further studies will be required to improve

Condensate-polisher resin-leakage quantification and resin-transport studies

International Nuclear Information System (INIS)

Stauffer, C.C.; Doss, P.L.

1983-04-01

The objectives of this program were to: (1) determine the extent of resin leakage from current generation condensate polisher systems, both deep bed and powdered resin design, during cut-in, steady-state and flow transient operation, (2) analyze moisture separator drains and other secondary system samples for resin fragments and (3) document the level of organics in the secondary system. Resin leakage samples were obtained from nine-power stations that have either recirculating steam generators or once through steam generators. Secondary system samples were obtained from steam generator feedwater, recirculating steam generator blowdown and moisture separator drains. Analysis included ultraviolet light examination, SEM/EDX, resin quantification and infrared analysis. Data obtained from the various plants were compared and factors affecting resin leakage were summarized

Coolant leakage detecting device

International Nuclear Information System (INIS)

Yamauchi, Kiyoshi; Kawai, Katsunori; Ishihara, Yoshinao.

1995-01-01

The device of the present invention judges an amount of leakage of primary coolants of a PWR power plant at high speed. Namely, a mass of coolants contained in a pressurizer, a volume controlling tank and loop regions is obtained based on a preset relational formula and signals of each of process amount, summed up to determine the total mass of coolants for every period of time. The amount of leakage for every period of time is calculated by a formula of Karman's filter based on the total mass of the primary coolants for every predetermined period of time, and displays it on CRT. The Karman's filter is formed on every formula for several kinds of states formed based on the preset amount of the leakage, to calculate forecasting values for every mass of coolants. An adaptable probability for every preset leakage amount is determined based on the difference between the forecast value and the observed value and the scattering thereof. The adaptable probability is compared with a predetermined threshold value, which is displayed on the CRT. This device enables earlier detection of leakage and identification of minute leakage amount as compared with the prior device. (I.S.)

Leakage current behavior in lead-free ferroelectric (K,Na)NbO3-LiTaO3-LiSbO3 thin films

Science.gov (United States)

Abazari, M.; Safari, A.

2010-12-01

Conduction mechanisms in epitaxial (001)-oriented pure and 1 mol % Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrate were investigated. Temperature dependence of leakage current density was measured as a function of applied electric field in the range of 200-380 K. It was shown that the different transport mechanisms dominate in pure and Mn-doped thin films. In pure (KNN-LT-LS) thin films, Poole-Frenkel emission was found to be responsible for the leakage, while Schottky emission was the dominant mechanism in Mn-doped thin films at higher electric fields. This is a remarkable yet clear indication of effect of 1 mol % Mn on the resistive behavior of such thin films.

Data leakage quantification

NARCIS (Netherlands)

Vavilis, S.; Petkovic, M.; Zannone, N.; Atluri, V.; Pernul, G.

2014-01-01

The detection and handling of data leakages is becoming a critical issue for organizations. To this end, data leakage solutions are usually employed by organizations to monitor network traffic and the use of portable storage devices. These solutions often produce a large number of alerts, whose

Poloidal field leakage optimization in ETE

Energy Technology Data Exchange (ETDEWEB)

Shibata, Carlos Shinya; Montes, Antonio

1996-12-01

A very simple but efficient numerical algorithm is used to minimize the Ohmic coil field leakage into the plasma region of the tokamak ETE. After few interactions the code provides the positions and the current required for two pairs of compensation coils. Resulting optimum field intensity distribution is presented and commented. (author). 5 refs., 4 figs., 2 tabs.

Poloidal field leakage optimization in ETE

International Nuclear Information System (INIS)

Shibata, Carlos Shinya; Montes, Antonio.

1996-01-01

A very simple but efficient numerical algorithm is used to minimize the Ohmic coil field leakage into the plasma region of the tokamak ETE. After few interactions the code provides the positions and the current required for two pairs of compensation coils. Resulting optimum field intensity distribution is presented and commented. (author). 5 refs., 4 figs., 2 tabs

Radioactivity leakage monitoring system

International Nuclear Information System (INIS)

Nakajima, Takuichiro; Noguchi, Noboru.

1982-01-01

Purpose: To obtain a device for detecting the leakage ratio of a primary coolant by utilizing the variation in the radioactivity concentration in a reactor container when the coolant is leaked. Constitution: A measurement signal is produced from a radioactivity measuring instrument, and is continuously input to a malfunction discriminator. The discriminator inputs a measurement signal to a concentration variation discriminator when the malfunction is recognized and simultaneously inputs a measurement starting time from the inputting time to a concentration measuring instrument. On the other hand, reactor water radioactivity concentration data obtained by sampling the primary coolant is input to a concentration variation computing device. A comparator obtains the ratio of the measurement signal from the measuring instrument and the computed data signal from the computing device at the same time and hence the leakage rate, indicates the average leakage rate by averaging the leakage rate signals and also indicates the total leakage amount. (Yoshihara, H.)

Direct observation of the leakage current in epitaxial diamond Schottky barrier devices by conductive-probe atomic force microscopy and Raman imaging

OpenAIRE

Alvarez, Jose; Boutchich, M.; Kleider, J. P.; Teraji, T.; Koide, Y.

2014-01-01

The origin of the high leakage current measured in several vertical-type diamond Schottky devices is conjointly investigated by conducting probe atomic force microscopy (CP-AFM) and confocal micro-Raman/Photoluminescence (PL) imaging analysis. Local areas characterized by a strong decrease of the local resistance (5-6 orders of magnitude drop) with respect to their close surrounding have been identified in several different regions of the sample surface. The same local areas, also referenced ...

Prediction of leakage current of non-ceramic insulators in early aging period

Energy Technology Data Exchange (ETDEWEB)

El-Hag, Ayman H. [Electrical Engineering Department, American University of Sharjah, Sharjah (United Arab Emirates); Jahromi, Ali Naderian [Kinectrics Inc., Transmission and Distribution Technologies, Toronto (Canada); Sanaye-Pasand, Majid [Electrical and Computer Engineering Department, University of Tehran (Iran)

2008-10-15

The paper presents a neural network based prediction technique for the leakage current (LC) of non-ceramic insulators during salt-fog test. Nearly 50 distribution class silicone rubber (SIR) insulators with three different voltage classes have been tested in a salt-fog chamber, where the LC has been continuously recorded for at least 100 h. A boundary for early aging period is defined by the rate of change of the LC instead of a fixed threshold value. Consequently, the Gaussian radial basis network has been adopted to predict the level of LC at the early stage of aging of the SIR insulators and is compared with a classical network. The initial values of LC and its rate of change at 10 min intervals for the first 5 h are selected as the input to the network, and the final value of LC of the early aging period is considered as the output of the network. It is found that Gaussian radial basis function network with a random optimizing training method is an appropriate network to predict the LC with a 3.5-5.3% accuracy, if the training data and the testing data are selected from the same type of SIR insulators. (author)

Preventive testing and leakage detection in pipe-lines of steam condensers and generators of a PWR type reactor

International Nuclear Information System (INIS)

Canalini, A.; Carvalho, N.C. de

1985-01-01

The non-destructive methods: Spum, Helium and Hydrostatic used in leakage detection in condenser pipelines for PWR type reactors are presented. The time, costs, sensitivity, resources necessary and personnel development factors are considered to choose adequated method, in function of nuclear power plant conditions. The leakage tests are applied in pressurized systems or vacuum. Eddy Current testing is used in condensers and steam generators aiming to avoid leakage in these equipments. The spume testing for leakage detection in condenser pipelines - which operation - and hydrostatic testing for leakage detection through reaming with shutdown - were most efficients. The Helium testing applied in pressurized systems or submitted to vacuum systems presented satisfactory results. The Eddy Current testing in condenser and steam generator pipelines reached desired objective, reducing leakage in the first and preserving the integrity in the second. (M.C.K.) [pt

Indoor-Outdoor Air Leakage of Apartments and Commercial Buildings

Energy Technology Data Exchange (ETDEWEB)

Price, P.N.; Shehabi, A.; Chan, R.W.; Gadgil, A.J.

2006-06-01

We compiled and analyzed available data concerning indoor-outdoor air leakage rates and building leakiness parameters for commercial buildings and apartments. We analyzed the data, and reviewed the related literature, to determine the current state of knowledge of the statistical distribution of air exchange rates and related parameters for California buildings, and to identify significant gaps in the current knowledge and data. Very few data were found from California buildings, so we compiled data from other states and some other countries. Even when data from other developed countries were included, data were sparse and few conclusive statements were possible. Little systematic variation in building leakage with construction type, building activity type, height, size, or location within the u.s. was observed. Commercial buildings and apartments seem to be about twice as leaky as single-family houses, per unit of building envelope area. Although further work collecting and analyzing leakage data might be useful, we suggest that a more important issue may be the transport of pollutants between units in apartments and mixed-use buildings, an under-studied phenomenon that may expose occupants to high levels of pollutants such as tobacco smoke or dry cleaning fumes.

Systematic review of methods to predict and detect anastomotic leakage in colorectal surgery.

Science.gov (United States)

Hirst, N A; Tiernan, J P; Millner, P A; Jayne, D G

2014-02-01

Anastomotic leakage is a serious complication of gastrointestinal surgery resulting in increased morbidity and mortality, poor function and predisposing to cancer recurrence. Earlier diagnosis and intervention can minimize systemic complications but is hindered by current diagnostic methods that are non-specific and often uninformative. The purpose of this paper is to review current developments in the field and to identify strategies for early detection and treatment of anastomotic leakage. A systematic literature search was performed using the MEDLINE, Embase, PubMed and Cochrane Library databases. Search terms included 'anastomosis' and 'leak' and 'diagnosis' or 'detection' and 'gastrointestinal' or 'colorectal'. Papers concentrating on the diagnosis of gastrointestinal anastomotic leak were identified and further searches were performed by cross-referencing. Computerized tomography CT scanning and water-soluble contrast studies are the current preferred techniques for diagnosing anastomotic leakage but suffer from variable sensitivity and specificity, have logistical constraints and may delay timely intervention. Intra-operative endoscopy and imaging may offer certain advantages, but the ability to predict anastomotic leakage is unproven. Newer techniques involve measurement of biomarkers for anastomotic leakage and have the potential advantage of providing cheap real-time monitoring for postoperative complications. Current diagnostic tests often fail to diagnose anastomotic leak at an early stage that enables timely intervention and minimizes serious morbidity and mortality. Emerging technologies, based on detection of local biomarkers, have achieved proof of concept status but require further evaluation to determine whether they translate into improved patient outcomes. Further research is needed to address this important, yet relatively unrecognized, area of unmet clinical need. Colorectal Disease © 2013 The Association of Coloproctology of Great Britain

Improving off-state leakage characteristics for high voltage AlGaN/GaN-HFETs on Si substrates

Science.gov (United States)

Moon, Sung-Woon; Twynam, John; Lee, Jongsub; Seo, Deokwon; Jung, Sungdal; Choi, Hong Goo; Shim, Heejae; Yim, Jeong Soon; Roh, Sungwon D.

2014-06-01

We present a reliable process and design technique for realizing high voltage AlGaN/GaN hetero-junction field effect transistors (HFETs) on Si substrates with very low and stable off-state leakage current characteristics. In this work, we have investigated the effects of the surface passivation layer, prepared by low pressure chemical vapor deposition (LPCVD) of silicon nitride (SiNx), and gate bus isolation design on the off-state leakage characteristics of metal-oxide-semiconductor (MOS) gate structure-based GaN HFETs. The surface passivated devices with gate bus isolation fully surrounding the source and drain regions showed extremely low off-state leakage currents of less than 20 nA/mm at 600 V, with very small variation. These techniques were successfully applied to high-current devices with 80-mm gate width, yielding excellent off-state leakage characteristics within a drain voltage range 0-700 V.

Analysis of reverse gate leakage mechanism of AlGaN/GaN HEMTs with N2 plasma surface treatment

Science.gov (United States)

Liu, Hui; Zhang, Zongjing; Luo, Weijun

2018-06-01

The mechanism of reverse gate leakage current of AlGaN/GaN HEMTs with two different surface treatment methods are studied by using C-V, temperature dependent I-V and theoretical analysis. At the lower reverse bias region (VR >- 3.5 V), the dominant leakage current mechanism of the device with N2 plasma surface treatment is the Poole-Frenkel emission current (PF), and Trap-Assisted Tunneling current (TAT) is the principal leakage current of the device which treated by HCl:H2O solution. At the higher reverse bias region (VR current of the device with N2 plasma surface treatment is one order of magnitude smaller than the device which treated by HCl:H2O solution. This is due to the recovery of Ga-N bond in N2 plasma surface treatment together with the reduction of the shallow traps in post-gate annealing (PGA) process. The measured results agree well with the theoretical calculations and demonstrate N2 plasma surface treatment can reduce the reverse leakage current of the AlGaN/GaN HEMTs.

Microdose Induced Drain Leakage Effects in Power Trench MOSFETs: Experiment and Modeling

Science.gov (United States)

Zebrev, Gennady I.; Vatuev, Alexander S.; Useinov, Rustem G.; Emeliyanov, Vladimir V.; Anashin, Vasily S.; Gorbunov, Maxim S.; Turin, Valentin O.; Yesenkov, Kirill A.

2014-08-01

We study experimentally and theoretically the micro-dose induced drain-source leakage current in the trench power MOSFETs under irradiation with high-LET heavy ions. We found experimentally that cumulative increase of leakage current occurs by means of stochastic spikes corresponding to a strike of single heavy ion into the MOSFET gate oxide. We simulate this effect with the proposed analytic model allowing to describe (including Monte Carlo methods) both the deterministic (cumulative dose) and stochastic (single event) aspects of the problem. Based on this model the survival probability assessment in space heavy ion environment with high LETs was proposed.

Impact of the Indonesian Throughflow on Agulhas leakage

Directory of Open Access Journals (Sweden)

D. Le Bars

2013-09-01

Full Text Available Using ocean models of different complexity we show that opening the Indonesian Passage between the Pacific and the Indian oceans increases the input of Indian Ocean water into the South Atlantic via the Agulhas leakage. In a strongly eddying global ocean model this response results from an increased Agulhas Current transport and a constant proportion of Agulhas retroflection south of Africa. The leakage increases through an increased frequency of ring shedding events. In an idealized two-layer and flat-bottom eddy resolving model, the proportion of the Agulhas Current transport that retroflects is (for a wide range of wind stress forcing not affected by an opening of the Indonesian Passage. Using a comparison with a linear model and previous work on the retroflection problem, the result is explained as a balance between two mechanisms: decrease retroflection due to large-scale momentum balance and increase due to local barotropic/baroclinic instabilities.

Predicting Envelope Leakage in Attached Dwellings

Energy Technology Data Exchange (ETDEWEB)

Faakye, O. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Arena, L. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Griffiths, D. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States)

2013-07-01

The most common method for measuring air leakage is to use a single blower door to pressurize and/or depressurize the test unit. In detached housing, the test unit is the entire home and the single blower door measures air leakage to the outside. In attached housing, this 'single unit', 'total', or 'solo' test method measures both the air leakage between adjacent units through common surfaces as well air leakage to the outside. Measuring and minimizing this total leakage is recommended to avoid indoor air quality issues between units, reduce energy losses to the outside, reduce pressure differentials between units, and control stack effect. However, two significant limitations of the total leakage measurement in attached housing are: for retrofit work, if total leakage is assumed to be all to the outside, the energy benefits of air sealing can be significantly over predicted; for new construction, the total leakage values may result in failing to meet an energy-based house tightness program criterion. The scope of this research is to investigate an approach for developing a viable simplified algorithm that can be used by contractors to assess energy efficiency program qualification and/or compliance based upon solo test results.

Subsea Hydraulic Leakage Detection and Diagnosis

OpenAIRE

Stavenes, Thomas

2010-01-01

The motivation for this thesis is reduction of hydraulic emissions, minimizing of process emergency shutdowns, exploitation of intervention capacity, and reduction of costs. Today, monitoring of hydraulic leakages is scarce and the main way to detect leakage is the constant need for filling of hydraulic fluid to the Hydraulic Power Unit (HPU). Leakage detection and diagnosis has potential, which would be adressed in this thesis. A strategy towards leakage detection and diagnosis is given....

Electrical current leakage and open-core threading dislocations in AlGaN-based deep ultraviolet light-emitting diodes

International Nuclear Information System (INIS)

Moseley, Michael; Allerman, Andrew; Crawford, Mary; Wierer, Jonathan J.; Smith, Michael; Biedermann, Laura

2014-01-01

Electrical current transport through leakage paths in AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) and their effect on LED performance are investigated. Open-core threading dislocations, or nanopipes, are found to conduct current through nominally insulating Al 0.7 Ga 0.3 N layers and limit the performance of DUV-LEDs. A defect-sensitive phosphoric acid etch reveals these open-core threading dislocations in the form of large, micron-scale hexagonal etch pits visible with optical microscopy, while closed-core screw-, edge-, and mixed-type threading dislocations are represented by smaller and more numerous nanometer-scale pits visible by atomic-force microscopy. The electrical and optical performances of DUV-LEDs fabricated on similar Si-doped Al 0.7 Ga 0.3 N templates are found to have a strong correlation to the density of these nanopipes, despite their small fraction (<0.1% in this study) of the total density of threading dislocations

Reducing leakage current in semiconductor devices

Energy Technology Data Exchange (ETDEWEB)

Lu, Bin; Matioli, Elison de Nazareth; Palacios, Tomas Apostol

2018-03-06

A semiconductor device includes a first region having a first semiconductor material and a second region having a second semiconductor material. The second region is formed over the first region. The semiconductor device also includes a current blocking structure formed in the first region between first and second terminals of the semiconductor device. The current blocking structure is configured to reduce current flow in the first region between the first and second terminals.

Issues behind Competitiveness and Carbon Leakage

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

This report explores the vulnerability of heavy industry to carbon leakage and competitiveness loss. It reviews the existing literature on competitiveness and carbon leakage under uneven climate policies. It also suggests a statistical method to track carbon leakage, and applies this methodology to Phase I of the EU emissions trading scheme, for various industrial activities: iron and steel, cement, aluminium and refineries. Finally, it reviews measures to mitigate carbon leakage, as discussed in Australia, Canada, Europe, New Zealand and the US.

Leakage monitoring device and method

International Nuclear Information System (INIS)

Yamada, Izumi; Matsui, Yuji; Fujimori, Haruo.

1995-01-01

In a water leakage monitor for a steam generator, output signals from an acoustic sensor disposed in the vicinity of a region to be monitored is subjected to phasing calculation (beam forming calculation) to determine the distribution of a sound source intensity distribution. A peak is retrieved based on the distribution of the sound source intensity distribution. A correction coefficient depending on the position of the peak is multiplied to the sound source intensity. The presence or absence of leakage is determined based on the degree of the sound source intensity after the completion of correction. Namely, a relative value of sound source intensity for each of the portions in the region to be monitored is determined, and the point of the greatest sound source intensity is assumed as a leaking point, to determine the position of the leakage. An absolute value of the sound source intensity at the leaking point is determined by such a constitution that a correction coefficient depending on the position is multiplied to the intensity of the position of the peak in the distribution of the sound intensity. A threshold value for the determination of the presence or absence of the leakage can be set if a relation between an amount of the leakage previously determined experimentally and the intensity of the sound source. Then, a countermeasure can easily be taken after the detection of the leakage and a restoring operation can be carried out rapidly after the occurrence of leakage while avoiding unnecessary shutdown. (N.H.)

Modelling of illuminated current–voltage characteristics to evaluate leakage currents in long wavelength infrared mercury cadmium telluride photovoltaic detectors

International Nuclear Information System (INIS)

Gopal, Vishnu; Qiu, WeiCheng; Hu, Weida

2014-01-01

The current–voltage characteristics of long wavelength mercury cadmium telluride infrared detectors have been studied using a recently suggested method for modelling of illuminated photovoltaic detectors. Diodes fabricated on in-house grown arsenic and vacancy doped epitaxial layers were evaluated for their leakage currents. The thermal diffusion, generation–recombination (g-r), and ohmic currents were found as principal components of diode current besides a component of photocurrent due to illumination. In addition, both types of diodes exhibited an excess current component whose growth with the applied bias voltage did not match the expected growth of trap-assisted-tunnelling current. Instead, it was found to be the best described by an exponential function of the type, I excess  = I r0  + K 1 exp (K 2 V), where I r0 , K 1 , and K 2 are fitting parameters and V is the applied bias voltage. A study of the temperature dependence of the diode current components and the excess current provided the useful clues about the source of origin of excess current. It was found that the excess current in diodes fabricated on arsenic doped epitaxial layers has its origin in the source of ohmic shunt currents. Whereas, the source of excess current in diodes fabricated on vacancy doped epitaxial layers appeared to be the avalanche multiplication of photocurrent. The difference in the behaviour of two types of diodes has been attributed to the difference in the quality of epitaxial layers

Pancreatic anastomosis leakage management following pancreaticoduodenectomy how could be manage the anastomosis leakage after pancreaticoduodenectomy?

Directory of Open Access Journals (Sweden)

Seyed Abbas Tabatabei

2015-01-01

Full Text Available Background: Pancreatic anastomosis leakage and fistula formation following pancreaticoduodenectomy (Whipple′s procedure is a common complication. Delay in timely diagnosis and proper management is associated with high morbidity and mortality. To report our experience with management of pancreatic fistula following Whipple′s procedure. Materials and Methods: In this retrospective study, medical records of 90 patients who underwent Whipple′s procedure from 2009 to 2013 at our medical center were reviewed for documents about pancreatic anastomosis leakage and fistula formation. Results: There were 15 patients who developed pancreatico-jejunal anastomosis leakage. In 6 patients (3 males and 3 females the leakage was mild (conservative therapy was administered, but in 9 patients (6 males and 3 females, there was severe leakage. For the latter group, surgical intervention was done (2 cases underwent re-anastomosis and for 7 cases pancreatico-jejunal stump ligation was done along with drainage of the location. Conclusion: In severe pancreatic anastomotic leakage, it is better to intervene surgically as soon as possible by debridement of the distal part of the pancreas and ligation of the stump with nonabsorbable suture. Furthermore, debridement of the jejunum should be done, and the stump should be ligated thoroughly along with drainage.

Colorectal Anastomotic Leakage: New perspectives

NARCIS (Netherlands)

F. Daams (Freek)

2014-01-01

markdownabstract__Abstract__ This thesis provides new perspectives on colorectal anastomotic leakages. In both experimental and clinical studies, aspects of prevention, early identification, treatment and consequences of anastomotic leakage are discussed.

Radiofrequency radiation leakage from microwave ovens

International Nuclear Information System (INIS)

Lahham, A.; Sharabati, A.

2013-01-01

This work presents data on the amount of radiation leakage from 117 microwave ovens in domestic and restaurant use in the West Bank, Palestine. The study of leakage is based on the measurements of radiation emissions from the oven in real-life conditions by using a frequency selective field strength measuring system. The power density from individual ovens was measured at a distance of 1 m and at the height of centre of door screen. The tested ovens were of different types, models with operating powers between 1000 and 1600 W and ages ranging from 1 month to >20 y, including 16 ovens with unknown ages. The amount of radiation leakage at a distance of 1 m was found to vary from 0.43 to 16.4 μW cm -1 with an average value equalling 3.64 μW cm -2 . Leakages from all tested microwave ovens except for seven ovens (∼6 % of the total) were below 10 μW cm -2 . The highest radiation leakage from any tested oven was ∼16.4 μW cm -2 , and found in two cases only. In no case did the leakage exceed the limit of 1 μWcm -1 recommended by the ICNIRP for 2.45-GHz radiofrequency. This study confirms a linear correlation between the amount of leakage and both oven age and operating power, with a stronger dependence of leakage on age. (authors)

Study of the tunnelling initiated leakage current through the carbon nanotube embedded gate oxide in metal oxide semiconductor structures

International Nuclear Information System (INIS)

Chakraborty, Gargi; Sarkar, C K; Lu, X B; Dai, J Y

2008-01-01

The tunnelling currents through the gate dielectric partly embedded with semiconducting single-wall carbon nanotubes in a silicon metal-oxide-semiconductor (MOS) structure have been investigated. The application of the gate voltage to such an MOS device results in the band bending at the interface of the partly embedded oxide dielectric and the surface of the silicon, initiating tunnelling through the gate oxide responsible for the gate leakage current whenever the thickness of the oxide is scaled. A model for silicon MOS structures, where carbon nanotubes are confined in a narrow layer embedded in the gate dielectric, is proposed to investigate the direct and the Fowler-Nordheim (FN) tunnelling currents of such systems. The idea of embedding such elements in the gate oxide is to assess the possibility for charge storage for memory device applications. Comparing the FN tunnelling onset voltage between the pure gate oxide and the gate oxide embedded with carbon nanotubes, it is found that the onset voltage decreases with the introduction of the nanotubes. The direct tunnelling current has also been studied at very low gate bias, for the thin oxide MOS structure which plays an important role in scaling down the MOS transistors. The FN tunnelling current has also been studied with varying nanotube diameter

Minority Carrier Tunneling and Stress-Induced Leakage Current for p+ gate MOS Capacitors with Poly-Si and PolySi0.7Ge0.3 Gate Material

NARCIS (Netherlands)

Houtsma, V.E.; Holleman, J.; Salm, Cora; de Haan, I.R.; Schmitz, Jurriaan; Widdershoven, F.P.; Widdershoven, F.P.; Woerlee, P.H.

1999-01-01

In this paper the I-V conduction mechanism for gate injection (-V g), Stress-Induced Leakage Current (SILC) characteristics and time-to-breakdown (tbd) of PMOS capacitors with p+-poly-Si and poly-SiGe gate material on 5.6, 4.8 and 3.1 nm oxide thickness are studied. A model based on Minority Carrier

The effect of cathode bias (field effect) on the surface leakage current of CdZnTe detectors

International Nuclear Information System (INIS)

Bolotnikov, A.E.; Hubert Chen, C.M.; Cook, W.R.; Harrison, F.A.; Kuvvetli, I.; Schindler, S.M.; Stahle, C.M.; Parker, B.H.

2003-01-01

Surface resistivity is an important parameter of multi-electrode CZT detectors such as coplanar-grid, strip, or pixel detectors. Low surface resistivity results in a high leakage current and affects the charge collection efficiency in the areas near contacts. Thus, it is always desirable to have the surface resistivity of the detector as high as possible. In the past the most significant efforts were concentrated to develop passivation techniques for CZT detectors. However, as we found, the field-effect caused by a bias applied on the cathode can significantly reduce the surface resistivity even though the detector surface was carefully passivated. In this paper we illustrate that the field-effect is a common feature of the CZT multi-electrode detectors, and discuss how to take advantage of this effect to improve the surface resistivity of CZT detectors

Using provenance of terrigenous sediment to reconstruct the Agulhas Leakage during the Early and Late Pleistocene

Science.gov (United States)

Pearson, B.; Franzese, A. M.

2017-12-01

The Agulhas Current, the strongest western boundary current in the southern hemisphere, is uniquely characterized by its strong retroflection. The current carries water southward from the Indian Ocean toward the cape of South Africa, before turning back on itself. At this point of retroflection, some of the current's flow escapes into the southern Atlantic Ocean. This transfer of water from the Indian Ocean to Atlantic Ocean makes up the Agulhas Leakage. The Leakage occurs in a series of eddies and rings located in the Cape Basin south of the African continent. Scientific literature demonstrates that relatively buoyant leakage water has been a determining factor varying strength of the Atlantic Meridional Ocean Current (AMOC), during glacial-interglacial cycles. It has been demonstrated that radiogenic isotope, major, and trace element concentrations serve as a proxy for terrigenous sediment provenance in the Agulhas region. Current understanding is that terrigenous sediment provenance is older during warmer periods of deposition. This corresponds to more input from southeastern African end members, and thus a stronger Agulhas Current, during warming periods in the paleoclimate record. Conversely, younger terrigenous sediment deposited during colder periods, such as the Last Glacial Maximum, suggests a weaker Agulhas Current, and less Agulhas Leakage. In 2016, on the International Ocean Discovery Program Expedition 361, sediment cores were drilled at 6 sites in the Greater Agulhas region. A major goal of the expedition was to expand knowledge of the relation between changes in the Agulhas System and changes in paleoclimate, southern African climate, and AMOC. We analyzed sediment from Expedition 361 Site U1479 (35°03.53'S; 17°24.06'E; 2615 mbsl) located where the Agulhas Leakage occurs. We measured Argon, strontium isotope ratios, ɛNd, trace and major element concentrations on the <2 micron clay fraction. Preliminary results foretell promising findings. For

Geochemical Implications of CO2 Leakage Associated with Geologic Storage: A Review

Energy Technology Data Exchange (ETDEWEB)

Harvey, Omar R.; Qafoku, Nikolla; Cantrell, Kirk J.; Brown, Christopher F.

2012-07-09

Leakage from deep storage reservoirs is a major risk factor associated with geologic sequestration of carbon dioxide (CO2). Different scientific theories exist concerning the potential implications of such leakage for near-surface environments. The authors of this report reviewed the current literature on how CO2 leakage (from storage reservoirs) would likely impact the geochemistry of near surface environments such as potable water aquifers and the vadose zone. Experimental and modeling studies highlighted the potential for both beneficial (e.g., CO2 re sequestration or contaminant immobilization) and deleterious (e.g., contaminant mobilization) consequences of CO2 intrusion in these systems. Current knowledge gaps, including the role of CO2-induced changes in redox conditions, the influence of CO2 influx rate, gas composition, organic matter content and microorganisms are discussed in terms of their potential influence on pertinent geochemical processes and the potential for beneficial or deleterious outcomes. Geochemical modeling was used to systematically highlight why closing these knowledge gaps are pivotal. A framework for studying and assessing consequences associated with each factor is also presented in Section 5.6.

How to attribute market leakage to CDM projects

NARCIS (Netherlands)

Vöhringer, F.; Kuosmanen, T.K.; Dellink, R.B.

2006-01-01

Economic studies suggest that market leakage rates of greenhouse gas abatement can reach the two-digit percentage range. Although the Marrakesh Accords require Clean Development Mechanism (CDM) projects to account for leakage, most projects neglect market leakage. Insufficient leakage accounting is

Ion induced intermixing and consequent effects on the leakage currents in HfO{sub 2}/SiO{sub 2}/Si systems

Energy Technology Data Exchange (ETDEWEB)

Manikanthababu, N.; Saikiran, V.; Pathak, A.P.; Rao, S.V.S.N. [University of Hyderabad, School of Physics, Hyderabad (India); Chan, T.K.; Vajandar, S.; Osipowicz, T. [National University of Singapore, Department of Physics, Centre for Ion Beam Applications (CIBA), Singapore (Singapore)

2017-05-15

Atomic layer deposited (ALD) samples with layer stacks of HfO{sub 2} (3 nm)/SiO{sub 2} (0.7 nm)/Si were subjected to 120 MeV Au ion irradiation at different fluences to study intermixing effects across the HfO{sub 2}/SiO{sub 2} interface. High-resolution Rutherford backscattering spectrometry (HRBS) and X-ray reflectivity (XRR) measurements confirm an increase in the interlayer thickness as a result of SHI induced intermixing effects. Current-voltage (I-V) measurements reveal an order of magnitude difference in the leakage current density between the pristine and irradiated samples. This can be explained by considering the increased physical thickness of interlayer (HfSiO). Furthermore, the samples were subjected to rapid thermal annealing (RTA) process to analyze annealing kinetics. (orig.)

Excessive leakage measurement using pressure decay method in containment building local leakage rate test at nuclear power plant

Energy Technology Data Exchange (ETDEWEB)

Lee, Won Kyu; Kim, Chang Soo; Kim, Wang Bae [KHNP, Central Research Institute, Daejeon (Korea, Republic of)

2016-06-15

There are two methods for conducting the containment local leakage rate test (LLRT) in nuclear power plants: the make-up flow rate method and the pressure decay method. The make-up flow rate method is applied first in most power plants. In this method, the leakage rate is measured by checking the flow rate of the make-up flow. However, when it is difficult to maintain the test pressure because of excessive leakage, the pressure decay method can be used as a complementary method, as the leakage rates at pressures lower than normal can be measured using this method. We studied the method of measuring over leakage using the pressure decay method for conducting the LLRT for the containment building at a nuclear power plant. We performed experiments under conditions similar to those during an LLRT conducted on-site. We measured the characteristics of the leakage rate under varies pressure decay conditions, and calculated the compensation ratio based on these data.

First-principles simulations of the leakage current in metal-oxide-semiconductor structures caused by oxygen vacancies in HfO2 high-K gate dielectric

International Nuclear Information System (INIS)

Mao, L.F.; Wang, Z.O.

2008-01-01

HfO 2 high-K gate dielectric has been used as a new gate dielectric in metal-oxide-semiconductor structures. First-principles simulations are used to study the effects of oxygen vacancies on the tunneling current through the oxide. A level which is nearly 1.25 eV from the bottom of the conduction band is introduced into the bandgap due to the oxygen vacancies. The tunneling current calculations show that the tunneling currents through the gate oxide with different defect density possess the typical characteristic of stress-induced leakage current. Further analysis shows that the location of oxygen vacancies will have a marked effect on the tunneling current. The largest increase in the tunneling current caused by oxygen vacancies comes about at the middle oxide field when defects are located at the middle of the oxide. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Mechanism of leakage of ion-implantation isolated AlGaN/GaN MIS-high electron mobility transistors on Si substrate

Science.gov (United States)

Zhang, Zhili; Song, Liang; Li, Weiyi; Fu, Kai; Yu, Guohao; Zhang, Xiaodong; Fan, Yaming; Deng, Xuguang; Li, Shuiming; Sun, Shichuang; Li, Xiajun; Yuan, Jie; Sun, Qian; Dong, Zhihua; Cai, Yong; Zhang, Baoshun

2017-08-01

In this paper, we systematically investigated the leakage mechanism of the ion-implantation isolated AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) on Si substrate. By means of combined DC tests at different temperatures and electric field dependence, we demonstrated the following original results: (1) It is proved that gate leakage is the main contribution to OFF-state leakage of ion-implantation isolated AlGaN/GaN MIS-HEMTs, and the gate leakage path is a series connection of the gate dielectric Si3N4 and Si3N4-GaN interface. (2) The dominant mechanisms of the leakage current through LPCVD-Si3N4 gate dielectric and Si3N4-GaN interface are identified to be Frenkel-Poole emission and two-dimensional variable range hopping (2D-VRH), respectively. (3) A certain temperature annealing could reduce the density of the interface state that produced by ion implantation, and consequently suppress the interface leakage transport, which results in a decrease in OFF-state leakage current of ion-implantation isolated AlGaN/GaN MIS-HEMTs.

Visual Inspection of Water Leakage from Ground Penetrating Radar Radargram

Science.gov (United States)

Halimshah, N. N.; Yusup, A.; Mat Amin, Z.; Ghazalli, M. D.

2015-10-01

Water loss in town and suburban is currently a significant issue which reflect the performance of water supply management in Malaysia. Consequently, water supply distribution system has to be maintained in order to prevent shortage of water supply in an area. Various techniques for detecting a mains water leaks are available but mostly are time-consuming, disruptive and expensive. In this paper, the potential of Ground Penetrating Radar (GPR) as a non-destructive method to correctly and efficiently detect mains water leaks has been examined. Several experiments were designed and conducted to prove that GPR can be used as tool for water leakage detection. These include instrument validation test and soil compaction test to clarify the maximum dry density (MDD) of soil and simulation studies on water leakage at a test bed consisting of PVC pipe burying in sand to a depth of 40 cm. Data from GPR detection are processed using the Reflex 2D software. Identification of water leakage was visually inspected from the anomalies in the radargram based on GPR reflection coefficients. The results have ascertained the capability and effectiveness of the GPR in detecting water leakage which could help avoiding difficulties with other leak detection methods.

VISUAL INSPECTION OF WATER LEAKAGE FROM GROUND PENETRATING RADAR RADARGRAM

Directory of Open Access Journals (Sweden)

N. N. Halimshah

2015-10-01

Full Text Available Water loss in town and suburban is currently a significant issue which reflect the performance of water supply management in Malaysia. Consequently, water supply distribution system has to be maintained in order to prevent shortage of water supply in an area. Various techniques for detecting a mains water leaks are available but mostly are time-consuming, disruptive and expensive. In this paper, the potential of Ground Penetrating Radar (GPR as a non-destructive method to correctly and efficiently detect mains water leaks has been examined. Several experiments were designed and conducted to prove that GPR can be used as tool for water leakage detection. These include instrument validation test and soil compaction test to clarify the maximum dry density (MDD of soil and simulation studies on water leakage at a test bed consisting of PVC pipe burying in sand to a depth of 40 cm. Data from GPR detection are processed using the Reflex 2D software. Identification of water leakage was visually inspected from the anomalies in the radargram based on GPR reflection coefficients. The results have ascertained the capability and effectiveness of the GPR in detecting water leakage which could help avoiding difficulties with other leak detection methods.

Geochemical monitoring for detection of CO_{2} leakage from subsea storage sites

Science.gov (United States)

García-Ibáñez, Maribel I.; Omar, Abdirahman M.; Johannessen, Truls

2017-04-01

Carbon Capture and Storage (CCS) in subsea geological formations is a promising large-scale technology for mitigating the increases of carbon dioxide (CO2) in the atmosphere. However, detection and quantification of potential leakage of the stored CO2 remains as one of the main challenges of this technology. Geochemical monitoring of the water column is specially demanding because the leakage CO2 once in the seawater may be rapidly dispersed by dissolution, dilution and currents. In situ sensors capture CO2 leakage signal if they are deployed very close to the leakage point. For regions with vigorous mixing and/or deep water column, and for areas far away from the leakage point, a highly sensitive carbon tracer (Cseep tracer) was developed based on the back-calculation techniques used to estimate anthropogenic CO2 in the water column. Originally, the Cseep tracer was computed using accurate discrete measurements of total dissolved inorganic carbon (DIC) and total alkalinity (AT) in the Norwegian Sea to isolate the effect of natural submarine vents in the water column. In this work we assess the effect of measurement variables on the performance of the method by computing the Cseep tracer twice: first using DIC and AT, and second using partial pressure of CO2 (pCO2) and pH. The assessment was performed through the calculation of the signal to noise ratios (STNR). We found that the use of the Cseep tracer increases the STNR ten times compared to the raw measurement data, regardless of the variables used. Thus, while traditionally the pH-pCO2 pair generates the greatest uncertainties in the oceanic CO2 system, it seems that the Cseep technique is insensitive to that issue. On the contrary, the use of the pCO2-pH pair has the highest CO2 leakage detection and localization potential due to the fact that both pCO2 and pH can currently be measured at high frequency and in an autonomous mode.

Simulation of leakage through mechanical sealing device

Science.gov (United States)

Tikhomorov, V. P.; Gorlenko, O. A.; Izmerov, M. A.

2018-03-01

The procedure of mathematical modeling of leakage through the mechanical seal taking into account waviness and roughness is considered. The percolation process is represented as the sum of leakages through a gap between wavy surfaces and percolation through gaps formed by fractal roughness, i.e. the total leakage is determined by the slot model and filtration leakage. Dependences of leaks on the contact pressure of corrugated and rough surfaces of the mechanical seal elements are presented.

Combined approach to reduced duration integrated leakage rate testing

International Nuclear Information System (INIS)

Galanti, P.J.

1987-01-01

Even though primary reactor containment allowable leakage rates are expressed in weight percent per day of contained air, engineers have been attempting to define acceptable methods to test in < 24 h as long as these tests have been performed. The reasons to reduce testing duration are obvious, because time not generating electricity is time not generating revenue for the utilities. The latest proposed revision to 10CFR50 Appendix J, concerning integrated leakage rate testing (ILRTs), was supplemented with a draft regulatory guide proposing yet another method. This paper proposes a method that includes elements of currently accepted concepts for short duration testing with a standard statistical check for criteria acceptance. Following presentation of the method, several cases are presented showing the results of these combined criteria

RF capacitance-voltage characterization of MOSFETs with high-leakage dielectric

NARCIS (Netherlands)

Schmitz, Jurriaan; Cubaynes, F.N; Cubaynes, F.N.; Havens, R.J.; de Kort, R.; Scholten, A.J.; Tiemeijer, L.F.

2003-01-01

We present a MOS Capacitance-Voltage measurement methodology that, contrary to present methods, is highly robust against gate leakage current densities up to 1000 A/cm/sup 2/. The methodology features specially designed RF test structures and RF measurement frequencies. It allows MOS parameter

Carbon leakage from a Nordic perspective

Energy Technology Data Exchange (ETDEWEB)

Naess-Schmidt, S.; Hansen, Martin Bo; Sand Kirk, J. [Copenhagen Economics, Copenhagen (Denmark)

2012-02-15

Carbon pricing is generally considered a highly effective tool in reducing carbon emissions. Putting a price on carbon provides incentives for users and producers of fossil fuels to reduce consumption and develop low carbon products and processes. However, pursuing an ambitious climate policy can lead to carbon leakage, which refers to a situation where unilateral or regional climate change policy drives the relocation of industry investments and installations, and associated emissions, to third countries. This report by Copenhagen Economics has been commissioned by the Nordic Council of Ministers to give an overview of the industries at risk of carbon leakage in the Nordic countries, and estimate the expected extent of carbon leakage from unilateral climate policies in the Nordic countries. The report also assesses available policy options that may reduce the risk of carbon leakage, such as exemptions from energy tax and exemptions from quota obligations under green certificate schemes. The key drivers of carbon leakage are identified, which include energy intensity, product differentiation, transportation costs and capital intensity. The analysis suggests that industries such as paper and pulp, iron and steel, aluminium, cement, pharmaceuticals, chemicals, and fertilizers are most at risk of carbon leakage in the Nordic manufacturing sector. (Author)

Support calculations for management of PRISE leakage accidents

Energy Technology Data Exchange (ETDEWEB)

Matejovic, P.; Vranka, L. [Nuclear Power Plants Research Inst. Vuje, Trnava (Slovakia)

1997-12-31

Accidents involving primary-to-secondary leakage (PRISE) caused by rupture of one or a few tubes are well known design basis events in both, western and VVER NPPs. Operating experience and in-service inspections of VVER-440 units have demonstrated also the potential for large PRISE leaks in the case of the steam generator (SG) primary collector cover lift-up (Rovno NPP). Without performing any countermeasure for limitation of SG collector cover lift-up, a full opening results in PRISE leak with an equivalent diameter 107 mm. Although this accident was not considered in the original design, this event is usually analysed as DBA too. Different means are available for detection and mitigation of PRISE leakage in NPPs currently in operation (J.Bohunice V-1 and V-2) or under construction (Mochovce) in Slovakia. 8 refs.

Support calculations for management of PRISE leakage accidents

Energy Technology Data Exchange (ETDEWEB)

Matejovic, P; Vranka, L [Nuclear Power Plants Research Inst. Vuje, Trnava (Slovakia)

1998-12-31

Accidents involving primary-to-secondary leakage (PRISE) caused by rupture of one or a few tubes are well known design basis events in both, western and VVER NPPs. Operating experience and in-service inspections of VVER-440 units have demonstrated also the potential for large PRISE leaks in the case of the steam generator (SG) primary collector cover lift-up (Rovno NPP). Without performing any countermeasure for limitation of SG collector cover lift-up, a full opening results in PRISE leak with an equivalent diameter 107 mm. Although this accident was not considered in the original design, this event is usually analysed as DBA too. Different means are available for detection and mitigation of PRISE leakage in NPPs currently in operation (J.Bohunice V-1 and V-2) or under construction (Mochovce) in Slovakia. 8 refs.

Roxby Downs water leakage

International Nuclear Information System (INIS)

1996-01-01

The Environment, Resource and development Committee has been asked by Parliament to examine 'a massive leakage of water at Roxby Downs' and to make recommendations 'as to further action'. It has also been specifically asked to comment on 'the desirability of the Department of Mines and Energy having prime responsibility for environmental matters in relation to mining operations'. This report begins with a description of the Olympic Dam operations near Roxby Downs and with a brief overview of the regulations controlling those operations. The site of the leakage the Olympic Dam tailings retention system is then described in greater detail. Part 3 describes how the system was originally designed, modified and approved. It ends with a series of findings about the adequacy of the original design (including the monitoring systems built into it) and of the approvals process. Recommendations are then made about how future approvals should be handled. Part 4 of the report outlines how the tailings retention system was built and operated and how the massive leakage from it was detected and reported. Findings about the adequacy of the management of the system and about the initial reactions to the leakage are then made, together with recommendations designed to improve future management of the system. 25 refs., 15 figs

Coolant leakage detection device

International Nuclear Information System (INIS)

Ito, Takao.

1983-01-01

Purpose: To surely detect the coolant leakage at a time when the leakage amount is still low in the intra-reactor inlet pipeway of FBR type reactor. Constitution: Outside of the intra-reactor inlet piping for introducing coolants at low temperature into a reactor core, an outer closure pipe is furnished. The upper end of the outer closure pipe opens above the liquid level of the coolants in the reactor, and a thermocouple is inserted to the opening of the upper end. In such a structure, if the coolants in the in-reactor piping should leak to the outer closure pipe, coolants over-flows from the opening thereof, at which the thermocouple detects the temperature of the coolants at a low temperature, thereby enabling to detect the leakage of the coolants at a time when it is still low. (Kamimura, M.)

Horizontal H 2-air turbulent buoyant jet resulting from hydrogen leakage

KAUST Repository

El-Amin, Mohamed; Sun, Shuyu

2012-01-01

The current article is devoted to introducing mathematical and physical analyses with numerical investigation of a buoyant jet resulting from hydrogen leakage in air from a horizontal round source. H 2-air jet is an example of the non

Experimental evaluation of clinical colon anastomotic leakage.

Science.gov (United States)

Pommergaard, Hans-Christian

2014-03-01

Colorectal anastomotic leakage remains a frequent and serious complication in gastrointestinal surgery. Patient and procedure related risk factors for anastomotic leakage have been identified. However, the responsible pathophysiological mechanisms are still unknown. Among these, ischemia and insufficient surgical technique have been suggested to play a central role. Animal models are valuable means to evaluate pathophysiological mechanisms and may be used to test preventive measures aiming at reducing the risk of anastomotic leakage, such as external anastomotic coating. The aim of this thesis was to: Clarify the best suited animal to model clinical anastomotic leakage in humans; Create animal models mimicking anastomotic leakage in humans induced by insufficient surgical technique and tissue ischemia; Determine the best suited coating materials to prevent anastomotic leakage. This study is a systematic review using the databases MEDLINE and Rex. MEDLINE was searched up to October 2010 to identify studies on experimental animal models of clinical colon anastomotic leakage. From the Rex database, textbooks on surgical aspects as well as gastrointestinal physiology and anatomy of experimental animals were identified. The results indicated that the mouse and the pig are the best suited animals to evaluate clinical anastomotic leakage. However, the pig model is less validated and more costly to use compared with the mouse. Most frequently, rats are used as models. However, extreme interventions are needed to create clinical leakage in these animals. The knowledge from this study formed the basis for selecting the animal species most suited for the models in the next studies. STUDY 2: In this experimental study, technically insufficient colonic anastomoses were performed in 110 C57BL/6 mice. The number of sutures in the intervention group was reduced to produce a suitable leakage rate. Moreover, the analgesia and suture material were changed in order to optimize the

Analysis of ONKALO water leakage mapping results

Energy Technology Data Exchange (ETDEWEB)

Ahokas, H.; Nummela, J; Turku, J. [Poeyry Finland Oy, Vantaa (Finland)

2014-04-15

As part of the programme for the final disposal of spent nuclear fuel, an analysis has been compiled of water leakage mapping performed in ONKALO. Leakage mapping is part of the Olkiluoto Monitoring Programme (OMO) and the field work has been carried out by Posiva Oy. The main objective of the study is to analyse differences detected between mapping campaigns carried out typically twice a year in 2005-2012. Differences were estimated to be caused by the differences in groundwater conditions caused by seasonal effects or by differences between the years. The effect of technical changes like shotcreting, postgrouting, ventilation etc. on the results was also studied. The development of the visualisation of mapping results was also an objective of this work. Leakage mapping results have been reported yearly in the monitoring reports of Hydrology with some brief comments on the detected differences. In this study, the development of the total area and the number of different leakages as well as the correlation of changes with shotcreting and grouting operations were studied. In addition, traces of fractures on tunnel surfaces, and the location of rock bolts and drain pipes were illustrated together with leakage mapping. In water leakage mapping, the tunnel surfaces are visually mapped to five categories: dry, damp, wet, dripping and flowing. Major changes were detected in the total area of damp leakages. It is likely that the increase has been caused by the condensation of warm ventilation air on the tunnel surfaces and the corresponding decrease by the evaporation of moisture into the dry ventilation air. Shotcreting deep in ONKALO may also have decreased the total area of damp leakages. Changes in the total area and number of wet leakages correlate at least near the surface with differences in yearly precipitation. It is possible that strong rains have also caused a temporary increase in wet leakages. Dripping and wet leakages have been observed on average more

Analysis of ONKALO water leakage mapping results

International Nuclear Information System (INIS)

Ahokas, H.; Nummela, J; Turku, J.

2014-04-01

As part of the programme for the final disposal of spent nuclear fuel, an analysis has been compiled of water leakage mapping performed in ONKALO. Leakage mapping is part of the Olkiluoto Monitoring Programme (OMO) and the field work has been carried out by Posiva Oy. The main objective of the study is to analyse differences detected between mapping campaigns carried out typically twice a year in 2005-2012. Differences were estimated to be caused by the differences in groundwater conditions caused by seasonal effects or by differences between the years. The effect of technical changes like shotcreting, postgrouting, ventilation etc. on the results was also studied. The development of the visualisation of mapping results was also an objective of this work. Leakage mapping results have been reported yearly in the monitoring reports of Hydrology with some brief comments on the detected differences. In this study, the development of the total area and the number of different leakages as well as the correlation of changes with shotcreting and grouting operations were studied. In addition, traces of fractures on tunnel surfaces, and the location of rock bolts and drain pipes were illustrated together with leakage mapping. In water leakage mapping, the tunnel surfaces are visually mapped to five categories: dry, damp, wet, dripping and flowing. Major changes were detected in the total area of damp leakages. It is likely that the increase has been caused by the condensation of warm ventilation air on the tunnel surfaces and the corresponding decrease by the evaporation of moisture into the dry ventilation air. Shotcreting deep in ONKALO may also have decreased the total area of damp leakages. Changes in the total area and number of wet leakages correlate at least near the surface with differences in yearly precipitation. It is possible that strong rains have also caused a temporary increase in wet leakages. Dripping and wet leakages have been observed on average more

Signal attenuation due to cavity leakage

International Nuclear Information System (INIS)

Sherman, M.H.; Modera, M.P.

1988-01-01

The propagation of sound waves in fluids requires information about three properties of the system: capacitance (compressibility), resistance (friction), and inductance (inertia). Acoustical design techniques to date have tended to ignore the frictional effects associated with airflow across the envelope of the acoustic cavity (e.g., resistive vents). Since such leakage through the cavity envelope is best expressed with a power law dependence on the pressure, standard Fourier techniques that rely on linearity cannot be used. In this article, the theory relevant to nonlinear leakage is developed and equations presented. Potential applications of the theory to techniques for quantifying the leakage of buildings are presented. Experimental results from pressure decays in a full-scale test structure are presented and the leakage so measured is compared with independent measurements to demonstrate the technique

Alopecia associated with unexpected leakage from electron cone

Energy Technology Data Exchange (ETDEWEB)

Wen, B.C.; Pennington, E.C.; Hussey, D.H.; Jani, S.K.

1989-06-01

Excessive irradiation due to unexpected leakage was found on a patient receiving electron beam therapy. The cause of this leakage was analyzed and the amount of leakage was measured for different electron beam energies. The highest leakage occurred with a 6 x 6 cm cone using a 12 MeV electron beam. The leakage dose measured along the side of the cone could be as great as 40%. Until the cones are modified or redesigned, it is advised that all patient setups be carefully reviewed to assure that no significant patient areas are in the side scatter region.

Automation of unit for leakage test

OpenAIRE

LYCHKOVSKAYA V.S.; TSYGANKOV A.S.; GRINBERG G.M.; STANOVOVA O.A.

2015-01-01

Federal state educational standard requirements for training of university students have been considered. Leakage test procedures for components of aerospace vehicles have been described. Automation procedures of existing laboratory leakage test units have been outlined.

Low dislocation density InAlN/AlN/GaN heterostructures grown on GaN substrates and the effects on gate leakage characteristics

Energy Technology Data Exchange (ETDEWEB)

Kotani, Junji, E-mail: kotani.junji-01@jp.fujitsu.com; Yamada, Atsushi; Ishiguro, Tetsuro; Tomabechi, Shuichi; Nakamura, Norikazu [Fujitsu Laboratories Ltd., 10-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0197 (Japan)

2016-04-11

This paper reports on the electrical characterization of Ni/Au Schottky diodes fabricated on InAlN high-electron-mobility transistor (HEMT) structures grown on low dislocation density free-standing GaN substrates. InAlN HEMT structures were grown on sapphire and GaN substrates by metal-organic vapor phase epitaxy, and the effects of threading dislocation density on the leakage characteristics of Ni/Au Schottky diodes were investigated. Threading dislocation densities were determined to be 1.8 × 10{sup 4 }cm{sup −2} and 1.2 × 10{sup 9 }cm{sup −2} by the cathodoluminescence measurement for the HEMT structures grown on GaN and sapphire substrates, respectively. Leakage characteristics of Ni/Au Schottky diodes were compared between the two samples, and a reduction of the leakage current of about three to four orders of magnitude was observed in the forward bias region. For the high reverse bias region, however, no significant improvement was confirmed. We believe that the leakage current in the low bias region is governed by a dislocation-related Frenkel–Poole emission, and the leakage current in the high reverse bias region originates from field emission due to the large internal electric field in the InAlN barrier layer. Our results demonstrated that the reduction of dislocation density is effective in reducing leakage current in the low bias region. At the same time, it was also revealed that another approach will be needed, for instance, band modulation by impurity doping and insertion of insulating layers beneath the gate electrodes for a substantial reduction of the gate leakage current.

Leakage and field emission in side-gate graphene field effect transistors

Energy Technology Data Exchange (ETDEWEB)

Di Bartolomeo, A., E-mail: dibant@sa.infn.it; Iemmo, L.; Romeo, F.; Cucolo, A. M. [Physics Department “E.R. Caianiello,” University of Salerno, via G. Paolo II, 84084 Fisciano (Italy); CNR-SPIN Salerno, via G. Paolo II, 84084 Fisciano (Italy); Giubileo, F. [CNR-SPIN Salerno, via G. Paolo II, 84084 Fisciano (Italy); Russo, S.; Unal, S. [Physics Department, University of Exeter, Stocker Road 6, Exeter, Devon EX4 4QL (United Kingdom); Passacantando, M.; Grossi, V. [Department of Physical and Chemical Sciences, University of L' Aquila, Via Vetoio, 67100 Coppito, L' Aquila (Italy)

2016-07-11

We fabricate planar graphene field-effect transistors with self-aligned side-gate at 100 nm from the 500 nm wide graphene conductive channel, using a single lithographic step. We demonstrate side-gating below 1 V with conductance modulation of 35% and transconductance up to 0.5 mS/mm at 10 mV drain bias. We measure the planar leakage along the SiO{sub 2}/vacuum gate dielectric over a wide voltage range, reporting rapidly growing current above 15 V. We unveil the microscopic mechanisms driving the leakage, as Frenkel-Poole transport through SiO{sub 2} up to the activation of Fowler-Nordheim tunneling in vacuum, which becomes dominant at higher voltages. We report a field-emission current density as high as 1 μA/μm between graphene flakes. These findings are important for the miniaturization of atomically thin devices.

Analytical models for the 2DEG concentration and gate leakage current in AlGaN/GaN HEMTs

Science.gov (United States)

Ahmed, Nadim; Dutta, Aloke K.

2017-06-01

In this paper, we present a completely analytical model for the 2DEG concentration in AlGaN/GaN HEMTs as a function of gate bias, considering the donor-like trap states present at the metal/AlGaN interface to be the primary source of 2DEG carriers. To the best of our knowledge, this is a completely new contribution of this work. The electric field in the AlGaN layer is calculated using this model, which is further used to model the gate leakage current under reverse bias. We have modified the existing TTT (Thermionic Trap-Assisted Tunneling) current model, taking into account the effect of both metal/AlGaN interface traps as well as AlGaN bulk traps. The gate current under forward bias is also modeled using the existing thermionic emission model, approximating it by its Taylor series expansion. To take into account the effect of non-zero drain-source bias (VDS), an empirical fitting parameter is introduced in order to model the channel voltage in terms of VDS. The results of our models have been compared with the experimental data reported in the literature for three different devices, and the match is found to be excellent for both forward and reverse bias as well as for zero and non-zero VDS.

Pickering unit 1 containment leakage characterization

International Nuclear Information System (INIS)

Zakaib, G.D.

1994-01-01

Results of the design pressure test carried out on Pickering Reactor Building number 1 during late 1992 showed that the leakage rate of the building was close to the safety analysis value of 2.7% contained mass per hour at the design pressure of 41.4 kPa(g) and was significantly higher than that reported after the previous test conducted in the spring of 1987. This unexpected finding initiated the longest and the most comprehensive containment leakage investigation ever undertaken by Ontario Hydro. A thorough investigation of leakage behaviour by repeated testing, inspections, leak search and analysis was launched. The extensive leak search effort included items such as: leak source detection by soap solution application, use of ultrasonic detectors, fogging and tracer gas techniques, systematic systems isolation, thermal imaging of the exterior, and quantification of leak sites by flowmeter and bagging. Using a specially designed volumetric technique, the root cause of the problem was finally confirmed as being due to 'pressure dependent laminar leakage' through the hairline cracks in the dome concrete. Structural analysis indicated that the thermal gradients and pressure loading combined to cause the cracking early in the structure's operating history and that overall structural integrity has not been compromised. Leakage rate analysis using a new fluid mechanics model augmented by the effect of thermal strains indicated that the leakage could be significantly less under certain transient temperature gradient conditions. Several options for repairing the dome were considered by a multidisciplinary team and it was finally decided to apply a specially engineered multilayer elastomeric coating to the exterior concrete surface. When the unit was re-tested in October 1993, a dramatic ten-fold improvement in leakage rate (down to 0.25%/h at design pressure) was observed. This is lower than even the commissioning results and comparable to the performance of newer units

Leakage Resilient Secure Two-Party Computation

DEFF Research Database (Denmark)

Damgård, Ivan Bjerre; Hazay, Carmit; Patra, Arpita

2012-01-01

we initiate the study of {\\em secure two-party computation in the presence of leakage}, where on top of corrupting one of the parties the adversary obtains leakage from the content of the secret memory of the honest party. Our study involves the following contributions: \\BE \\item {\\em Security...... and returns its result. Almost independently of secure computation, the area of {\\em leakage resilient cryptography} has recently been evolving intensively, studying the question of designing cryptographic primitives that remain secure even when some information about the secret key is leaked. In this paper...

Why the CDM can reduce carbon leakage

International Nuclear Information System (INIS)

Kallbekken, S.

2006-04-01

Carbon leakage is an important concern because it can reduce the environmental effectiveness of the Kyoto Protocol. The Clean Development Mechanism, one of the flexibility mechanisms allowed under the protocol, has the potential to reduce carbon leakage significantly because it reduces the relative competitive disadvantage to Annex B countries of restricting greenhouse gas emissions. The economic intuition behind this mechanism is explored in a theoretical analysis. It is then analyzed numerically using a CGE model. The results indicate that, assuming appropriate accounting for leakage and under realistic assumptions on CDM activity, the CDM has the potential to reduce the magnitude of carbon leakage by around three fifths

Accelerated fuel depreciation as an economic incentive for low-leakage fuel management

International Nuclear Information System (INIS)

Downar, T.J.

1986-01-01

An analysis is presented which evaluates the tax depreciation advantage which results from the increased rate of fuel depletion achieved in the current low-leakage fuel-management LWR core reload designs. An analytical fuel-cycle cost model is used to examine the important cost parameters which are then validated using the fuel-cycle cost code CINCAS and data from the Maine Yankee PWR. Results show that low-leakage fuel management, through the tax depreciation advantage from accelerated fuel depletion, provides an improvement of several percent in fuel-cycle costs compared to traditional out-in fuel management and a constant fuel depletion rate. (author)

Analysis of neutron leakage effect in the determination of macrogroup constants

International Nuclear Information System (INIS)

Martinez, A.S.; Vieira, H.D.

1986-01-01

A method to include the neutron leakage in the macrogroup constants calculation is presented. The method leads to independent equations for neutron flux and neutron current density. The results that have been gotten with the present method are very precise despite its simplicity. (Author) [pt

Particle and radiation leakage importance: definition, analysis, and interpretation

International Nuclear Information System (INIS)

Cacuci, D.G.; Wagschal, J.J.; Yaari, A.

1982-01-01

The concept of leakage importance function has been introduced and analyzed for physical systems governed by the Boltzmann transport equation. This leakage importance function represents a measure of the relative importance of source particles located at every point in phase space in contributing to the leakage and provides insight regarding the specific physical process that leads to leakage. The equation satisfied by the leakage importance function has been derived by using adjoint operators. It has been shown that procedures that are customarily used to derive an equation obeyed by an importance function suitable for an integral parameter such as a detector response or an eigenvalue lead to difficulties when directly applied to derive an equation obeyed by the leakage importance function. This is because, although leakage is also an integral parameter (i.e., a functional of the forward flux density), leakage is expressed in terms of a surface integral rather than in terms of volume integrals such as those appearing in expressions of detector responses or eigenvalues. Therefore, a procedure that departs from the customary course has been devised to derive the equation satisfied by the leakage importance function

Leakage current characterization for estimating the conditions of non-ceramic insulators' surfaces

Energy Technology Data Exchange (ETDEWEB)

El-Hag, Ayman H. [Electrical Engineering Department, American University of Sharjah, Sharjah (United Arab Emirate)

2007-03-15

In this work both detection of the beginning of dry-band arcing and correlating the average value of leakage current (LC) with non-ceramic insulator surface damage have been investigated. Silicone rubber insulators were tested in salt-fog under different voltage and conductivity levels. The autocorrelation function (ACF) was calculated for both the fundamental and third harmonic components of LC during the early aging period (EAP). It has been observed that distinct differences exist in the behavior of both the fundamental and that of the third harmonic components of the LC during EAP. Although the fundamental component of the LC begins to grow immediately after starting the test, the third harmonic requires a much longer period of time to begin. Dry-band arcing is highly correlated with distortion in the LC and hence to its third harmonic component. But it has been observed that the level of the fundamental component of LC at which the third harmonic component started to increase is different from one case to another. As such, it is more appropriate to use the ACF of the third harmonic component of LC as an indication of dry-band arcing rather than a simple threshold value. Moreover, the average value of LC during late aging period (LAP) was correlated with the damage of non-ceramic insulators. It has been found that the average level of both the fundamental and third harmonic component of LC is well correlated with the different degrees of damage of non-ceramic insulators' surface. (author)

International Market Leakage from China’s Forestry Policies

Directory of Open Access Journals (Sweden)

Xin Hu

2014-11-01

Full Text Available Carbon leakage can be a problem when seeking to reduce carbon emissions through forest policy. International market leakage is mainly caused by supply and demand imbalances in the timber market. This paper selects China, which is implementing forestry policy changes, as the research object. We begin by offering a brief analysis of China’s forestry policy changes, such as the logging quota and Six Key Forestry Programs to determine whether those policies affect timber supply. Second, through the use of three shock variables, carbon leakage is simulated under different scenarios by the Global Trade Analysis Project (GTAP model. The results reveal that the magnitude of leakage caused by implementing China’s forestry policies is between 79.7% and 88.8% with carbon leakage mainly displaced to Russia, Southeast Asia, and the EU. Two effective scenarios for reducing market leakage are presented: forest tenure reform and fast growing forest projects to improve domestic timber production, and raising tariffs on timber imports to reduce imports.

Leakage-resilient cryptography from minimal assumptions

DEFF Research Database (Denmark)

Hazay, Carmit; López-Alt, Adriana; Wee, Hoeteck

2013-01-01

We present new constructions of leakage-resilient cryptosystems, which remain provably secure even if the attacker learns some arbitrary partial information about their internal secret key. For any polynomial ℓ, we can instantiate these schemes so as to tolerate up to ℓ bits of leakage. While the...

Preadmission glucocorticoid use and anastomotic leakage after colon and rectal cancer resections: a Danish cohort study

Science.gov (United States)

Ostenfeld, Eva Bjerre; Erichsen, Rune; Baron, John A; Thorlacius-Ussing, Ole; Iversen, Lene Hjerrild; Riis, Anders H; Sørensen, Henrik Toft

2015-01-01

Objective To examine whether preadmission glucocorticoid use increases the risk of anastomotic leakage after colon and rectal cancer resections. Design A population-based cohort study. Setting Denmark (2001–2011). Participants We identified patients who had undergone a primary anastomosis after a colorectal cancer resection by linking medical registries. Participants who filled their most recent glucocorticoid prescription ≤90, 91–365 and >365 days before their surgery date were categorised as current, recent and former users, respectively. Main outcome measures We calculated 30-day absolute risk of anastomotic leakage and computed ORs using logistic regression models with adjustment for potential confounders. Results Of the 18 190 patients with colon cancer, anastomotic leakage occurred in 1184 (6.5%). Glucocorticoid use overall was not associated with an increased risk of leakage (6.4% vs 6.9% among never-users; OR 1.05; 95% CI 0.89 to 1.23). Categories of oral, inhaled or intestinal-acting glucocorticoids did not greatly affect risk of leakage. Anastomotic leakage occurred in 695 (13.2%) of 5284 patients with rectal cancer. Glucocorticoid use overall slightly increased risk of leakage (14.6% vs 12.8% among never-users; OR 1.36, 95% CI 1.08 to 1.72). Results did not differ significantly within glucocorticoid categories. Conclusions Preadmission glucocorticoids modestly increased the risk of anastomotic leakage mainly after rectal cancer resection. However, absolute risk differences were small and the clinical impact of glucocorticoid use may therefore be limited. PMID:26408282

Determination of Unidentified Leakage Using a Kalman Smoother

International Nuclear Information System (INIS)

Jang, Soek Bo; Heo, Gyunyoung; Ra, Insik; Han, Jeonghyun; Lee, Seon Woo

2008-01-01

Since the safety significance of leaks from the RCS can widely vary depending on the source of the leak as well as the leak rate, the detection of the leakage is an important issue. The leakage is classified into 1) identified leakage which is defined as leakage into closed systems such as pump seal or valve packing leaks that can be captured, and 2) unidentified leakage which is all other leakage. The unidentified leakage is typically determined by the RCS inventory balance method which is based on NUREG-1107. Since the accuracy of leak rate calculation is dependent of the plant operating condition, the change in the RCS temperature, inventory, and the transient operating condition should be avoided during the measurement period. Nevertheless, the operation of the makeup of the borated water into the RCS and the diversion of the inventory to the outside of the RCS boundary makes it difficult to maintain the plant stable over an hour. Due to the large fluctuation of the calculated leak rate, it is sometimes hard to know the trend of the leakage as well as the instantaneous leak rate. Any fluctuation of operating conditions can results in unreliable leak rate. This study proposes a new way of determining the unidentified leak rate using a Kalman filter and smoother technique. The proposed algorithm enhances the accuracy of the leak rate calculation not only for the steady state operations but also for transients in a well timed manner

Signal amplification and leakage current suppression in amorphous silicon p-i-n diodes by field profile tailoring

International Nuclear Information System (INIS)

Hong, W.S.; Zhong, F.; Mireshghi, A.; Perez-Mendez, V.

1999-01-01

The performance of amorphous silicon p-i-n diodes as radiation detectors in terms of signal amplitude can be greatly improved when there is a built-in signal gain mechanism. The authors describe an avalanche gain mechanism which is achieved by introducing stacked intrinsic, p-type, and n-type layers into the diode structure. They replaced the intrinsic layer of the conventional p-i-n diode with i 1 -p-i 2 -n-i 3 multilayers. The i 2 layer (typically 1 ∼ 3 microm) achieves an electric field > 10 6 V/cm, while maintaining the p-i interfaces to the metallic contact at electric fields 4 V/cm, when the diode is fully depleted. For use in photo-diode applications the whole structure is less than 10 microm thick. Avalanche gains of 10 ∼ 50 can be obtained when the diode is biased to ∼ 500 V. Also, dividing the electrodes to strips of 2 microm width and 20 microm pitch reduced the leakage current up to an order of magnitude, and increased light transmission without creating inactive regions

Superconducting coil configurations, with low flux leakage, for energy storage

International Nuclear Information System (INIS)

Vincent-Viry, O.; Mailfert, A.; Trassart, D.

2001-01-01

This paper presents two original types of SMES structures for energy storage. These two groups of SMES structures proceeded from an ideal structure: the full toroid, are modeled by the use of purely surface current densities. Their main advantage is to present no flux leakage, they give then satisfactory solution to the problem of energy storage. (orig.)

Detection device for pipeway water leakage in building

International Nuclear Information System (INIS)

Hanawa, Jun.

1988-01-01

Purpose: To rapidly detect pipeway leakage at predetermined areas over a wide range in a building. Constitution: If flooding should occur in a power plant building and left as it is, emergency core cooling system, as well as auxiliary equipments and electrical equipments of the system are flooded to make the safety shutdown of the plant impossible. The present invention copes with such a risk. That is, an inlet flow meter and as exit flow meter are disposed to the inlet and the exit of pipeways disposed in a predetermined region in the building and a flow rate difference detector between them is disposed. In this way, pipeway leakage is detected by detecting the flow rate difference between the inlet flow rate and the exit flow rate of the pipeway in the predetermined region. According to the present invention, if a pipeway in a predetermined region is raptured to cause water leakage, the pipeway leakage can rapidly be detected depending on the flow rate difference between the inlet flow rate and the exit flow rate. Further, the water leakage over the entire the predetermined region can be detected rapidly as compared with the conventional case of detecting the leakage at a restricted portion where the leakage detector is disposed. (Kamimura, M.)

RETRAN code analysis of Tsuruga-2 plant chemical volume control system (CVCS) reactor coolant leakage incident

International Nuclear Information System (INIS)

Kawai, Hiroshi

2002-01-01

In the Chemical Volume Control System (CVCS) reactor primary coolant leakage incident, which occurred in Tsuruga-2 (4-loop PWR, 3,423 MWt, 1,160 MWe) on July 12, 1999, it took about 14 hours before the leakage isolation. The delayed leakage isolation and a large amount of leakage have become a social concern. Effective procedure modification was studied. Three betterments were proposed based on a qualitative analysis to reduce the pressure and temperature of the primary loop as fast as possible by the current plant facilities while maintaining enough subcooling of the primary loop. I analyzed the incident with RETRAN code in order to quantitatively evaluate the leakage reduction when these betterments are adopted. This paper is very new because it created a typical analysis method for PWR plant behavior during plant shutdown procedure which conventional RETRAN transient analyses rarely dealt with. Also the event time is very long. To carry out this analysis successfully, I devised new models such as an Residual Heat Removal System (RHR) model etc. and simplified parts of the conventional model. Based on the analysis results, I confirmed that leakage can be reduced by about 30% by adopting these betterments. Then the Japan Atomic Power Company (JAPC) modified the operational procedure for reactor primary coolant leakage events adopting these betterments. (author)

Channel follower leakage restrictor

International Nuclear Information System (INIS)

Williamson, H.E.; Smith, B.A.

1977-01-01

An improved means is provided to control coolant leakage between the flow channel and the lower tie plate of a nuclear fuel assembly. The means includes an opening in the lower tie plate and a movable element adjacent thereto. The coolant pressure within the tie plate biases the movable means toward the inner surface of the surrounding flow channel to compensate for any movement of the flow channel away from the lower tie plate to thereby control the leakage of coolant flow from the fuel assemblies to the spaces among the fuel assemblies of the core. 9 figures

Current transport mechanisms in mercury cadmium telluride diode

Energy Technology Data Exchange (ETDEWEB)

Gopal, Vishnu, E-mail: vishnu-46@yahoo.com, E-mail: wdhu@mail.sitp.ac.cn [Institute of Defence Scientists and Technologists, CFEES Complex, Brig. S. K. Majumdar Marg, Delhi 110054 (India); Li, Qing; He, Jiale; Hu, Weida, E-mail: vishnu-46@yahoo.com, E-mail: wdhu@mail.sitp.ac.cn [National Lab for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); He, Kai; Lin, Chun [Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

2016-08-28

This paper reports the results of modelling of the current-voltage characteristics (I-V) of a planar mid-wave Mercury Cadmium Telluride photodiode in a gate controlled diode experiment. It is reported that the diode exhibits nearly ideal I-V characteristics under the optimum surface potential leading to the minimal surface leakage current. Deviations from the optimum surface potential lead to non ideal I–V characteristics, indicating a strong relationship between the ideality factor of the diode with its surface leakage current. Diode's I–V characteristics have been modelled over a range of gate voltages from −9 V to −2 V. This range of gate voltages includes accumulation, flat band, and depletion and inversion conditions below the gate structure of the diode. It is shown that the I–V characteristics of the diode can be very well described by (i) thermal diffusion current, (ii) ohmic shunt current, (iii) photo-current due to background illumination, and (iv) excess current that grows by the process of avalanche multiplication in the gate voltage range from −3 V to −5 V that corresponds to the optimum surface potential. Outside the optimum gate voltage range, the origin of the excess current of the diode is associated with its high surface leakage currents. It is reported that the ohmic shunt current model applies to small surface leakage currents. The higher surface leakage currents exhibit a nonlinear shunt behaviour. It is also shown that the observed zero-bias dynamic resistance of the diode over the entire gate voltage range is the sum of ohmic shunt resistance and estimated zero-bias dynamic resistance of the diode from its thermal saturation current.

Practical implementation of a higher order transverse leakage approximation

International Nuclear Information System (INIS)

Prinsloo, Rian H.; Tomašević

2011-01-01

Transverse integrated nodal diffusion methods currently represent the standard in full core neutronic simulation. The primary shortcoming in this approach, be it via the Analytic Nodal Method or Nodal Expansion Method, is the utilization of the quadratic transverse leakage approximation. This approach, although proven to work well for typical LWR problems, is not consistent with the formulation of nodal methods and can cause accuracy and convergence problems. In this work an improved, consistent quadratic leakage approximation is formulated, which derives from the class of higher order nodal methods developed some years ago. In this new approach, only information relevant to describing the transverse leak- age terms in the zero-order nodal equations are obtained from the higher order formalism. The method yields accuracy comparable to full higher order methods, but does not suffer from the same computational burden which these methods typically incur. (author)

Highly conducting leakage-free electrolyte for SrCoOx-based non-volatile memory device

Science.gov (United States)

Katase, Takayoshi; Suzuki, Yuki; Ohta, Hiromichi

2017-10-01

The electrochemical switching of SrCoOx-based non-volatile memory with a thin-film-transistor structure was examined by using liquid-leakage-free electrolytes with different conductivities (σ) as the gate insulator. We first examined leakage-free water, which is incorporated in the amorphous (a-) 12CaO.7Al2O3 film with a nanoporous structure (Calcium Aluminate with Nanopore), but the electrochemical oxidation/reduction of the SrCoOx layer required the application of a high gate voltage (Vg) up to 20 V for a very long current-flowing-time (t) ˜40 min, primarily due to the low σ [2.0 × 10-8 S cm-1 at room temperature (RT)] of leakage-free water. We then controlled the σ of the leakage-free electrolyte, infiltrated in the a-NaxTaO3 film with a nanopillar array structure, from 8.0 × 10-8 S cm-1 to 2.5 × 10-6 S cm-1 at RT by changing the x = 0.01-1.0. As the result, the t, required for the metallization of the SrCoOx layer under small Vg = -3 V, becomes two orders of magnitude shorter with increase of the σ of the a-NaxTaO3 leakage-free electrolyte. These results indicate that the ion migration in the leakage-free electrolyte is the rate-determining step for the electrochemical switching, compared to the other electrochemical process, and the high σ of the leakage-free electrolyte is the key factor for the development of the non-volatile SrCoOx-based electro-magnetic phase switching device.

Acoustic control of sodium leakage in valve gates of NPP

International Nuclear Information System (INIS)

Trykov, E.L.; Kovtun, S.N.; Anan'ev, A.A.; Yugov, S.I.

2014-01-01

Short description of sodium bench and acoustic investigation results on leakage monitoring of valves DN10 and DN40 are given. It is shown that acoustic method can be used successfully to control the leakages of sodium valves. Leakages on both type of valves increase the acoustic signal dispersion by 2-3 orders. For each type of valve acoustic system of leakage determination allows to conduct the preliminary graduation of signal dispersion on the sodium discharge rate. It make possible not only to record the leakage presence but also to determine the sodium discharge rate through the valve during the leakage [ru

Distributed public key schemes secure against continual leakage

DEFF Research Database (Denmark)

Akavia, Adi; Goldwasser, Shafi; Hazay, Carmit

2012-01-01

-secure against continual memory leakage. Our DPKE scheme also implies a secure storage system on leaky devices, where a value s can be secretely stored on devices that continually leak information about their internal state to an external attacker. The devices go through a periodic refresh protocol......In this work we study distributed public key schemes secure against continual memory leakage. The secret key will be shared among two computing devices communicating over a public channel, and the decryption operation will be computed by a simple 2-party protocol between the devices. Similarly...... against continual memory leakage, under the Bilinear Decisional Diffie-Hellman and $2$-linear assumptions. Our schemes have the following properties: 1. Our DPKE and DIBE schemes tolerate leakage at all times, including during refresh. During refresh the tolerated leakage is a (1/2-o (1),1)-fraction...

Heterogeneous neutron-leakage model for PWR pin-by-pin calculation

International Nuclear Information System (INIS)

Li, Yunzhao; Zhang, Bin; Wu, Hongchun; Shen, Wei

2017-01-01

Highlights: •The derivation of the formula of the leakage model is introduced. This paper evaluates homogeneous and heterogeneous leakage models used in PWR pin-by-pin calculation. •The implements of homogeneous and heterogeneous leakage models used in pin-cell homogenization of the lattice calculation are studied. A consistent method of cooperation between the heterogeneous leakage model and the pin-cell homogenization theory is proposed. •Considering the computational cost, a new buckling search scheme is proposed to reach the convergence faster. The computational cost of the newly proposed neutron balance scheme is much less than the power-method scheme and the linear-interpolation scheme. -- Abstract: When assembly calculation is performed with the reflective boundary condition, a leakage model is usually required in the lattice code. The previous studies show that the homogeneous leakage model works effectively for the assembly homogenization. However, it becomes different and unsettled for the pin-cell homogenization. Thus, this paper evaluates homogeneous and heterogeneous leakage models used in pin-by-pin calculation. The implements of homogeneous and heterogeneous leakage models used in pin-cell homogenization of the lattice calculation are studied. A consistent method of cooperation between the heterogeneous leakage model and the pin-cell homogenization theory is proposed. Considering the computational cost, a new buckling search scheme is proposed to reach the convergence faster. For practical reactor-core applications, the diffusion coefficients determined by the transport cross-section or by the leakage model are compared with each other to determine which one is more accurate for the Pressurized Water Reactor pin-by-pin calculation. Numerical results have demonstrated that the heterogeneous leakage model together with the diffusion coefficient determined by the heterogeneous leakage model would have the higher accuracy. The new buckling search

Earth current monitoring circuit for inductive loads

CERN Document Server

Montabonnet, V; Thurel, Y; Cussac, P

2010-01-01

The search for higher magnetic fields in particle accelerators increasingly demands the use of superconducting magnets. This magnet technology has a large amount of magnetic energy storage during operation at relatively high currents. As such, many monitoring and protection systems are required to safely operate the magnet, including the monitoring of any leakage of current to earth in the superconducting magnet that indicates a failure of the insulation to earth. At low amplitude, the earth leakage current affects the magnetic field precision. At a higher level, the earth leakage current can additionally generate local losses which may definitively damage the magnet or its instrumentation. This paper presents an active earth fault current monitoring circuit, widely deployed in the converters for the CERN Large Hadron Collider (LHC) superconducting magnets. The circuit allows the detection of earth faults before energising the circuit as well as limiting any eventual earth fault current. The electrical stress...

Radiation leakage in nuclear ship 'MUTSU'

International Nuclear Information System (INIS)

Ando, Yoshio; Miyasaka, Shun-ichi; Takeuchi, Kiyoshi.

1975-01-01

Associated with the radiation leakage in MUTSU occurred in September 1974, this report reviews the shielding design for MUTSU, radiation measurement and inspection activities by a survey group, and 2 dimensional analysis on the behavior of fast neutrons to shielding based on Ssub(N) codes. In the first part, the purpose and the structure of the primary and the secondary shields of MUTSU are briefly illustrated. In the second part, the progress of the series of affairs is explained, starting from zero power criticality experiment, through discovery of radiation leakage in output-increasing test, sending of a survey group for various measurement and inspection, and finally to the conclusion drawn by the survey group. In the third part, various numerical analyses performed to investigate into the leakage are illustrated with their results. The transport codes used were ANISN, TWOTRAN, SPAN, and PALLAS-2DCY. As a result of those inspection and calculation, it was found that the radiation leakage was due to fast neutrons coming through the gap between the reactor vessel and the primary shield. (Aoki, K.)

Leakage-Resilient Circuits without Computational Assumptions

DEFF Research Database (Denmark)

Dziembowski, Stefan; Faust, Sebastian

2012-01-01

Physical cryptographic devices inadvertently leak information through numerous side-channels. Such leakage is exploited by so-called side-channel attacks, which often allow for a complete security breache. A recent trend in cryptography is to propose formal models to incorporate leakage...... on computational assumptions, our results are purely information-theoretic. In particular, we do not make use of public key encryption, which was required in all previous works...... into the model and to construct schemes that are provably secure within them. We design a general compiler that transforms any cryptographic scheme, e.g., a block-cipher, into a functionally equivalent scheme which is resilient to any continual leakage provided that the following three requirements are satisfied...

Sustainable management of leakage from wastewater pipelines.

Science.gov (United States)

DeSilva, D; Burn, S; Tjandraatmadja, G; Moglia, M; Davis, P; Wolf, L; Held, I; Vollertsen, J; Williams, W; Hafskjold, L

2005-01-01

Wastewater pipeline leakage is an emerging concern in Europe, especially with regards to the potential effect of leaking effluent on groundwater contamination and the effects infiltration has on the management of sewer reticulation systems. This paper describes efforts by Australia, in association with several European partners, towards the development of decision support tools to prioritize proactive rehabilitation of wastewater pipe networks to account for leakage. In the fundamental models for the decision support system, leakage is viewed as a function of pipeline system deterioration. The models rely on soil type identification across the service area to determine the aggressiveness of the pipe environment and for division of the area into zones based on pipe properties and operational conditions. By understanding the interaction between pipe materials, operating conditions, and the pipe environment in the mechanisms leading to pipe deterioration, the models allow the prediction of leakage rates in different zones across a network. The decision support system utilizes these models to predict the condition of pipes in individual zones, and to optimize the utilization of rehabilitation resources by targeting the areas with the highest leakage rates.

Ship cabin leakage alarm based on ARM SCM

Science.gov (United States)

Qu, Liyan

2018-03-01

If there is a leakage in the cabin of a sailing ship, it is a major accident that threatens the personnel and property of the ship. If we can’t take timely measures, there will be a devastating disaster. In order to judge the leakage of the cabin, it is necessary to set up a leakage alarm system, so as to achieve the purpose of detecting and alarming the leakage of the cabin, and avoid the occurrence of accidents. This paper discusses the design of ship cabin leakage alarm system based on ARM SCM. In order to ensure the stability and precision of the product, the hardware design of the alarm system is carried out, such as circuit design, software design, the programming of SCM, the software programming of upper computer, etc. It is hoped that it can be of reference value to interested readers.

The effects of carbon prices and anti-leakage policies on selected industrial sectors in Spain – Cement, steel and oil refining

International Nuclear Information System (INIS)

Santamaría, Alberto; Linares, Pedro; Pintos, Pablo

2014-01-01

This paper assesses the impacts on the cement, steel and oil refining sectors in Spain of the carbon prices derived from the European Emissions Trading Scheme (EU ETS), and the potential effect on these sectors of the European Union anti-leakage policy measures. The assessment is carried out by means of three engineering models developed for this purpose. Our results show a high exposure to leakage of cement in coastal regions; a smaller risk in the steel sector, and non-negligible risk of leakage for the oil refining sector when carbon allowance prices reach high levels. We also find that the risk of leakage could be better handled with other anti-leakage policies than those currently in place in the EU. - Highlights: • We simulate the impact of carbon prices on the risk of leakage in the cement, steel and oil refining sectors. • We also assess the effectiveness of different anti-leakage policies in Europe. • Cement production in coastal areas is highly exposed. • The risk of leakage for steel and oil refining is smaller. • Anti-leakage policies should be modified to be efficient

Method to detect steam generator tube leakage

International Nuclear Information System (INIS)

Watabe, Kiyomi

1994-01-01

It is important for plant operation to detect minor leakages from the steam generator tube at an early stage, thus, leakage detection has been performed using a condenser air ejector gas monitor and a steam generator blow down monitor, etc. In this study highly-sensitive main steam line monitors have been developed in order to identify leakages in the steam generator more quickly and accurately. The performance of the monitors was verified and the demonstration test at the actual plant was conducted for their intended application to the plants. (author)

Risk factors, treatment and impact on outcomes of bile leakage after hemihepatectomy.

Science.gov (United States)

Zheng, Si-Ming; Li, Hong; Li, Gen-Cong; Yu, Dan-Song; Ying, Dong-Jian; Zhang, Bin; Lu, Cai-De; Zhou, Xin-Hua

2017-07-01

Risk factors for bile leakage after hemihepatectomy are unknown. A prospectively maintained database review identified patients undergoing hemihepatectomy between 1 January 2009 and 30 September 2014. Patients were divided into B/C and non-B/C bile leakage groups. Risk factors for bile leakage were predicted and assessments of their impact on patients were made. Bile leakage occurred in 91 of the 297 patients (30.6%); 64 cases were classified as grade B bile leakage (21.5%) and three cases as grade C bile leakage (1.0%). Multivariate analysis confirmed that elevated preoperative alanine transaminase (ALT), positive bile culture during surgery, hilar bile duct plasty, bilioenteric anastomosis and laparoscopic surgery were risk factors for B/C grade bile leakage (P bile leakage (P bile leakage (P bile leakage group were higher than those in the non-B/C bile leakage group (P bile leakage group also required prolonged hospitalization (P 0.05). Patient with elevated preoperative ALT, positive bile cultures during surgery, hilar bile duct plasty, bilioenteric anastomosis and laparoscopic surgery are more likely to complicate bile leakage. We should use biliary drainage such as preoperative PTBD, ENBD or intraoperative Kehr's T-tube drainage to reduce and treat bile leakage in patients with high risk of bile leakage. © 2015 Royal Australasian College of Surgeons.

The Impact of Statistical Leakage Models on Design Yield Estimation

Directory of Open Access Journals (Sweden)

Rouwaida Kanj

2011-01-01

Full Text Available Device mismatch and process variation models play a key role in determining the functionality and yield of sub-100 nm design. Average characteristics are often of interest, such as the average leakage current or the average read delay. However, detecting rare functional fails is critical for memory design and designers often seek techniques that enable accurately modeling such events. Extremely leaky devices can inflict functionality fails. The plurality of leaky devices on a bitline increase the dimensionality of the yield estimation problem. Simplified models are possible by adopting approximations to the underlying sum of lognormals. The implications of such approximations on tail probabilities may in turn bias the yield estimate. We review different closed form approximations and compare against the CDF matching method, which is shown to be most effective method for accurate statistical leakage modeling.

Leakage localization with an acoustic array that covers a wide area for pipeline leakage monitoring in a closed space

Energy Technology Data Exchange (ETDEWEB)

Park, Choon Su [Center for Safety Measurements, Division of Metrology for Quality of Life, Korea Research institute of Standards and Science, Daejeon (Korea, Republic of); Jeon, Jong Hoon [Hyundai Heavy Industry Co.,Ltd., Ulsan (Korea, Republic of); Park, Jin Ho [Korea Atomiv Energy Institute, Daejeon (Korea, Republic of)

2013-10-15

It is of great importance to localize leakages in complex pipelines for assuring their safety. A sensor array that can detect where leakages occur enables us to monitor a wide area with a relatively low cost. Beam forming is a fast and efficient algorithm to estimate where sources are, but it is generally made use of in free field condition. In practice, however, many pipelines are placed in a closed space for the purpose of safety and maintenance. This leads us to take reflected waves into account to the beam forming for interior leakage localization. Beam power distribution of reflected waves in a closed space is formulated, and spatial average is introduced to suppress the effect of reflected waves. Computer simulations and experiments ensure how the proposed method is effective to localize leakage in a closed space for structural health monitoring.

Gas-path leakage seal for a gas turbine

Science.gov (United States)

Wolfe, C.E.; Dinc, O.S.; Bagepalli, B.S.; Correia, V.H.; Aksit, M.F.

1996-04-23

A gas-path leakage seal is described for generally sealing a gas-path leakage-gap between spaced-apart first and second members of a gas turbine (such as combustor casing segments). The seal includes a generally imperforate foil-layer assemblage which is generally impervious to gas and is located in the leakage-gap. The seal also includes a cloth-layer assemblage generally enclosingly contacting the foil-layer assemblage. In one seal, the first edge of the foil-layer assemblage is left exposed, and the foil-layer assemblage resiliently contacts the first member near the first edge to reduce leakage in the ``plane`` of the cloth-layer assemblage under conditions which include differential thermal growth of the two members. In another seal, such leakage is reduced by having a first weld-bead which permeates the cloth-layer assemblage, is attached to the metal-foil-layer assemblage near the first edge, and unattachedly contacts the first member. 4 figs.

Calculation of transformers leakage reactance using electromagnetic energy technique

International Nuclear Information System (INIS)

Feiz, J.; Mohseni, H.; Sabet Marzooghi, S.; Naderian Jahromi, A.

2004-01-01

Determination of transformer leakage reactance using magnetic cores has long been an area of interest to engineers involved in the design of power and distribution transformers. This is required for predicting the performance of transformers before actual assembly of the transformers. In this paper a closed form solution technique applicable to the leakage reactance calculations for transformers is presented. An emphasis is on the development of a simple method to calculate the leakage reactance of the distribution transformers and smaller transformers. Energy technique procedure for computing the leakage reactances in distribution transformers is presented. This method is very efficient compared with the use of flux element and image technique and is also remarkably accurate. Examples of calculated leakage inductances and the short circuit impedance are given for illustration. For validation, the results are compared with the results obtained using test. This paper presents a novel technique for calculation of the leakage inductance in different parts of the transformer using the electromagnetic stored energy

Low voltage stress-induced leakage current and traps in ultrathin oxide (1.2 2.5 nm) after constant voltage stresses

Science.gov (United States)

Petit, C.; Zander, D.

2007-10-01

It has been shown that the low voltage gate current in ultrathin oxide metal-oxide-semiconductor devices is very sensitive to electrical stresses. Therefore, it can be used as a reliability monitor when the oxide thickness becomes too small for traditional electrical measurements to be used. In this work, we present a study on n-MOSCAP devices at negative gate bias in the direct tunneling (DT) regime. If the low voltage stress-induced leakage current (LVSILC) depends strongly on the low sense voltages, it also depends strongly on the stress voltage magnitude. We show that two LVSILC peaks appear as a function of the sense voltage in the LVSILC region and that their magnitude, one compared to the other, depends strongly on the stress voltage magnitude. One is larger than the other at low stress voltage and smaller at high stress voltage. From our experimental results, different conduction mechanisms are analyzed. To explain LVSILC variations, we propose a model of the conduction through the ultrathin gate oxide based on two distinctly different trap-assisted tunneling mechanisms: inelastic of gate electron (INE) and trap-assisted electron (ETAT).

Numerical Modeling of Methane Leakage from a Faulty Natural Gas Well into Fractured Tight Formations.

Science.gov (United States)

Moortgat, Joachim; Schwartz, Franklin W; Darrah, Thomas H

2018-03-01

Horizontal drilling and hydraulic fracturing have enabled hydrocarbon recovery from unconventional reservoirs, but led to natural gas contamination of shallow groundwaters. We describe and apply numerical models of gas-phase migration associated with leaking natural gas wells. Three leakage scenarios are simulated: (1) high-pressure natural gas pulse released into a fractured aquifer; (2) continuous slow leakage into a tilted fractured formation; and (3) continuous slow leakage into an unfractured aquifer with fluvial channels, to facilitate a generalized evaluation of natural gas transport from faulty natural gas wells. High-pressure pulses of gas leakage into sparsely fractured media are needed to produce the extensive and rapid lateral spreading of free gas previously observed in field studies. Transport in fractures explains how methane can travel vastly different distances and directions laterally away from a leaking well, which leads to variable levels of methane contamination in nearby groundwater wells. Lower rates of methane leakage (≤1 Mcf/day) produce shorter length scales of gas transport than determined by the high-pressure scenario or field studies, unless aquifers have low vertical permeabilities (≤1 millidarcy) and fractures and bedding planes have sufficient tilt (∼10°) to allow a lateral buoyancy component. Similarly, in fractured rock aquifers or where permeability is controlled by channelized fluvial deposits, lateral flow is not sufficiently developed to explain fast-developing gas contamination (0-3 months) or large length scales (∼1 km) documented in field studies. Thus, current efforts to evaluate the frequency, mechanism, and impacts of natural gas leakage from faulty natural gas wells likely underestimate contributions from small-volume, low-pressure leakage events. © 2018, National Ground Water Association.

Valve leakage inspection testing and maintenance process

International Nuclear Information System (INIS)

Aikin, J.A.; Reinwald, J.W.; Kittmer, C.A.

1991-01-01

In valve maintenance, packing rings that prevent leakage along the valve stem must periodically be replaced, either during routine maintenance or to correct a leak or valve malfunction. Tools and procedures currently in use for valve packing removal and inspection are generally of limited value due to various access and application problems. A process has been developed by AECL Research that addresses these problems. The process, using incompressible fluid pressure, quickly and efficiently confirms the integrity of the valve backseat, extracts hard-to-remove valve packing sets, and verifies the leak tightness of the repacked valve

A review on leakage rate tests for containment isolation systems

International Nuclear Information System (INIS)

Kim, In Goo; Kim, Hho Jung

1992-01-01

Wide experiences in operating containment isolation systems have been accumulated in Korea since 1978. Hence, it becomes necessary to review the operating data in order to confirm the integrity of containments with about 50 reactor-years of experience and to establish the future direction to the containment test program. The objectives of present work are to collect, consolidate and assess the leakage rate data, and then to find out dominant leakage paths and factors affecting integrated leakage rate test. General trends of overall leakage show that more careful surveillance during pre-operational test can reduce the containment leakage. Dominant leakage paths are found to be through air locks and large-sized valves, such as butterfly valves of purge lines, so that weighted surveillance and inspection on these dominant leakage paths can considerably reduce the containment leakage. The atmosphere stabilization are found to be the most important to obtain the reliable result. In order to get well stabilized atmosphere, temperature and flow rate of compressed air should be kept constant and it is preferable not to operate fan cooler during pressurizing the containment for test

Containment leakage rate testing requirements

International Nuclear Information System (INIS)

Arndt, E.G.

1992-01-01

This report presents the status of several documents under revision or development that provide requirements and guidance for testing nuclear power plant containment systems for leakage rates. These documents include the general revision to 10 CFR Part 50, Appendix J; the regulatory guide affiliated with the revision to Appendix J; the national standard that the regulatory guide endorses, ANSI/ANS-56.8, 'Containment System Leakage Rate Testing Requirements'; and the draft industry Licensing Topical Report, 'Standardized Program for Primary Containment Integrity Testing'. The actual or potential relationships between these documents are also explored

Radiologic assessment of spinal CSF leakage in spontaneous intracranial hypotension

International Nuclear Information System (INIS)

Han, Chang Jin; Kim, Ji Hyung; Kim, Jang Sung; Kim, Sun Yong; Suh, Jung Ho

1999-01-01

To assess the usefulness of imaging modalities in the detection of spinal CSF leakage in spontaneous intracranial hypotension. Fifteen patients who complained of postural headache without any preceding cause showed typical brain MR findings of intracranial hypotension, including radiologically confirmed CSF leakage. All fifteen underwent brain MRI and radionuclide cisternography. CT myelography was performed in eight patients and spinal MRI in six. Medical records, imaging findings and the incidence of spinal CSF leakage during each modality were retrospectively reviewed. CSF leakage was most common at the cervicothoracic junction, where in seven of 15 cases it was seen on radionuclide cisternography as increased focal paraspinal activity. Leakage was noted at the mid-tho-racic level in three patients, at the upper thoracic level in two, and at the cervical and lumbar levels in the remaining two. In two patients multiple CSF leaks were noted, and in all, early radioactive accumulation in the bladder was visualized. CT myelography revealed extrathecal and paraspinal contrast leakage in three of eight patients, and among those who underwent spinal MRI, dural enhancement was observed at the site of CSF leakage in all six, abnormal CSF signal in the neural foramen in one, and epidural CSF collection in one. Radionuclide cisternography is a useful method for the detection of CSF leakage in spontaneous intracranial hypotension. CT myelography and spinal MRI help determine the precise location of leakage

Electromagnetic Calculation and Plasma Leakage Rate Analysis of the Magnetically Confined Plasma Rocket

International Nuclear Information System (INIS)

Ni Zhipeng; Wang Liangbin; Li Jiangang; Chen Zhiyou; Zhang Yong; Wang Futang

2008-01-01

An electromagnetic calculation and the parameters of the magnet system of the magnetically confined plasma rocket were established. By using ANSYS code, it was found that the leakage rate depends on the current intensity of the magnet and the change of the magnet position.

Understanding and managing leakage in forest-based greenhouse-gas-mitigation projects.

Science.gov (United States)

Schwarze, Reimund; Niles, John O; Olander, Jacob

2002-08-15

A major concern about land use, land-use change and forestry (LULUCF) projects under the Clean Development Mechanism (CDM) is the potential for leakage. Leakage refers to a net increase of greenhouse-gas emissions in an area outside the project resulting from the CDM activity. This paper provides an overview of leakage, its definitions and its causes. It describes ways that LULUCF projects may suffer from leakage and attempts to assess the magnitude of leakage risks for different LULUCF project types. It also summarizes some of the approaches, both in terms of policies and project development, to address LULUCF leakage.

Detecting the leakage source of a reservoir using isotopes.

Science.gov (United States)

Yi, Peng; Yang, Jing; Wang, Yongdong; Mugwanezal, Vincent de Paul; Chen, Li; Aldahan, Ala

2018-07-01

A good monitoring method is vital for understanding the sources of a water reservoir leakage and planning for effective restoring. Here we present a combination of several tracers ( 222 Rn, oxygen and hydrogen isotopes, anions and temperature) for identification of water leakage sources in the Pushihe pumped storage power station which is in the Liaoning province, China. The results show an average 222 Rn activity of 6843 Bq/m 3 in the leakage water, 3034 Bq/m 3 in the reservoir water, and 41,759 Bq/m 3 in the groundwater. Considering that 222 Rn activity in surface water is typically less than 5000 Bq/m 3 , the low level average 222 Rn activity in the leakage water suggests the reservoir water as the main source of water. Results of the oxygen and hydrogen isotopes show comparable ranges and values in the reservoir and the leakage water samples. However, important contribution of the groundwater (up to 36%) was present in some samples from the bottom and upper parts of the underground powerhouse, while the leakage water from some other parts indicate the reservoir water as the dominant source. The isotopic finding suggests that the reservoir water is the main source of the leakage water which is confirmed by the analysis of anions (nitrate, sulfate, and chloride) in the water samples. The combination of these tracer methods for studying dam water leakage improves the accuracy of identifying the source of leaks and provide a scientific reference for engineering solutions to ensure the dam safety. Copyright © 2018 Elsevier Ltd. All rights reserved.

Indocyanine green staining facilitates detection of bleb leakage during trabeculectomy.

Science.gov (United States)

Okazaki, Teruhiko; Kiuchi, Takahiro; Kawana, Keisuke; Oshika, Tetsuro

2007-03-01

To report a new technique to visualize bleb leakage using indocyanine green (ICG) staining during trabeculectomy. The ICG solution was widely applied over the filtering bleb including the conjunctival wound before completion of trabeculectomy. This procedure was performed in 48 eyes of 44 consecutive patients undergoing trabeculectomy between December 2004 and October 2005. Without staining, bleb leakage was not identified by the direct observation under the operating microscope. ICG staining clearly visualized aqueous leakage from the bleb in 5 eyes (10.4%). The bleb leakage in these eyes was easily repaired with 10-0 nylon sutures, and no eyes, including these 5 cases, showed bleb leakage after surgery. There were no intraoperative and postoperative complications related to ICG application. The application of ICG during trabeculectomy is a simple and useful technique to facilitate detection and repair of the bleb leakage.

On the leakage problem of MIM capacitors due to improper etching of titanium nitride

NARCIS (Netherlands)

Groenland, A.W.; Wolters, Robertus A.M.; Kovalgin, Alexeij Y.; Schmitz, Jurriaan

2010-01-01

In this work, Metal-insulator-metal (MIM) capacitor structures are fabricated in a technology using TiN as electrode material. The electrical characterization revealed devices with small and large leakage currents. Scanning Electron Microscopy (SEM) inspection showed a correlation between high

Detection method of internal leakage from valve using acoustic method

International Nuclear Information System (INIS)

Kumagai, Hiromichi; Kitajima, Akira; Suzuki, Akio.

1990-01-01

The objective of this study is to estimate the feasibility of the acoustic method for the internal leakage from the valves in power plants. From the experimental results, it was suggested that the acoustic method for the monitoring of leakage was feasible. When the background levels are higher than the acoustic signals from leakage, we can detect the leakage analyzing the spectrum of the remainders which take the background noise from the acoustic signals. (author)

Control room unfiltered in-leakage limit analysis of design-basis LOCA for Lungmen ABWR plant

International Nuclear Information System (INIS)

Tsai Chihming; Chang Chinjang; Yuann Yngruey

2014-01-01

In USNRC's Generic Letter 2003-01, 'Control Room Habitability,' it requests utilities provide information to demonstrate that the control room at each of their respective facilities complies with the current licensing and design bases, and applicable regulatory requirements, and that suitable design, maintenance and testing control measures are in place for maintaining this compliance. In particular, each utility is required to perform the control room in-leakage test to demonstrate that the unfiltered in-leakage rate is within that assumed in the licensing analyses. It must be ensured that the control room envelope habitability, in terms of radiation dose, is maintained during normal operations as well as design basis accidents. In view of this, a dose analysis has been performed to establish the control room unfiltered in-leakage limit which can be used as an acceptance criterion for the in-leakage test. The analysis in this study is for Lungmen ABWR plant. The plant has twin units, with each unit having its own control room. The TID-4844 source terms and associated methodology are used. The USNRC RADTRAD v3.03 code is employed for the transport calculation of radioactive materials in different paths, including control room in-leakage path. The radiological criterion on protection of the operators specified in 10 CFR 50, Appendix A, General Design Criterion 19 is followed. It's demonstrated that the performance of Lungmen control room with 500 cfm unfiltered in-leakage air could meet the radiological habitability acceptance criteria in case of radiation hazards. (author)

Measurement Methods to Determine Air Leakage Between Adjacent Zones

Energy Technology Data Exchange (ETDEWEB)

Hult, Erin L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dickerhoff, Darryl J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Price, Phillip N. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-09-01

Air leakage between adjacent zones of a building can lead to indoor air quality and energy efficiency concerns, however there is no existing standard for measuring inter-zonal leakage. In this study, synthesized data and field measurements are analyzed in order to explore the uncertainty associated with different methods for collecting and analyzing fan pressurization measurements to calculate interzone leakage.

Incidence and management of pancreatic leakage after pancreatoduodenectomy

NARCIS (Netherlands)

de Castro, S. M. M.; Busch, O. R. C.; van Gulik, T. M.; Obertop, H.; Gouma, D. J.

2005-01-01

Background: Optimal management of severe pancreatic leakage after pancreatoduodenectomy can reduce morbidity and mortality. Completion pancreatectomy may be adequate but leads to endocrine insufficiency. This study evaluated an alternative management strategy for pancreatic leakage. Methods: Outcome

Testing to determine the leakage behavior of inflatable seals subject to severe accident loadings

International Nuclear Information System (INIS)

Parks, M.B.

1988-01-01

Under the sponsorship of the United States Nuclear Regulatory Commission, Sandia National Laboratories is currently developing test validated methods to predict the pressure capacity, at elevated temperatures, of light water reactor (LWR) nuclear containment vessels subject to loads well beyond their design basis - the so-called severe accident. Scale model tests of containments with the major penetrations represented have been carried to functional failure by internal pressurization. Also, combined pressure and elevated temperature tests of typical compression seals and gaskets, a full size personnel airlock, and of typical electrical penetration assemblies (EPAs), have been conducted in order to better understand the leakage behavior of containment penetrations. Because inflatable seals are also a part of the pressure boundary of some containments, it is important to understand their leakage behavior as well. This paper discusses the results of tests that were performed to better define the leakage behavior of inflatable seals when subjected to loads well beyond their design basis

Regulatory analysis for the resolution of generic issue C---8, main steam isolation valve leakage and LCS [leakage control system] failure

International Nuclear Information System (INIS)

Graves, C.C.

1990-06-01

Generic Issue C-8 deals with staff concerns about public risk because of the incidence of leak test failures reported for main steam isolation valves (MSIVs) at boiling water reactors and the limitations of the leakage control systems (LCSs) for mitigating the consequences of leakage from these valves. If the MSIV leakage is greatly in excess of the allowable value in the technical specifications, the LCS would be unavailable because of design limitations. The issue was initiated in 1983 to assess (1) the causes of MSIV leakage failures, (2) the effectiveness of the LCS and alternative mitigation paths, and (3) the need for additional regulatory action to reduce public risk. This report presents the regulatory analysis for Generic Issue C-8 and concludes that no new regulatory requirements are warranted

Device for preventing leakage of coolant in nuclear fuel assembly

International Nuclear Information System (INIS)

Kobayashi, Yukio; Sekiguchi, Mamoru; Yoshida, Hideo.

1975-01-01

Object: To prevent leakage of coolant from between lower tie plate and channel box without causing deformation of the channel box and also without the possibility of disturbing the installation and removal of the box by the provision of a thin plate provided with leakage holes for the lower tie plate. Structure: Static water pressure within the lower tie plate is adapted to act upon the bear side of a flat plate for leakage prevention through leakage holes formed in the tie plate, thus urging the flat plate against the channel box inner surface. Meanwhile, static water pressure having been led through the leakage holes in the flat plate is adapted to press the flat plate in the vertical direction, thus urging the flat plate against the channel box inner surface and thereby preventing leakage of the coolant through a gap between the channel box and lower tie plate. (Yoshino, Y.)

An objective comparison of leakage between commonly used earplugs.

Science.gov (United States)

Alt, Jeremiah A; Collins, William O

2012-01-01

We sought to determine the efficacy of commonly used earplugs using an anatomically correct ear model. The total volume and rate of water that leaked past the earplug and subsequent defect in the tympanic membrane over separately measured 30, 60, 120, and 180-second intervals were recorded. Scenarios tested included a control with no earplug, custom molded earplug (Precision Laboratories, Orlando, FL), Mack's plug (Warren, MI), Doc's plug (Santa Cruz, CA), and cotton balls coated with petroleum jelly. All plugs tested resulted in less leakage at all time points when compared with no plug (P leakage when compared with the cotton ball coated with petroleum jelly (P leakage compared with the customized plug (P leakage than the cotton plug (P leakage rate (f(4,45) = 94 [P water exposure should be minimized, then use of earplugs, particularly the moldable variety, merits further consideration. Copyright © 2012 Elsevier Inc. All rights reserved.

The Value of Changing Position in the Detection of CSF Leakage in Spontaneous Intracranial Hypotension Using Tc-99m DTPA Scintigraphy: Two Case Reports.

Science.gov (United States)

Lu, Yu Yu; Wang, Hsin Yi; Lin, Ying; Lin, Wan Yu

2012-09-01

Radionuclide Cisternography (RNC) is of potential value in pointing out the sites of cerebrospinal fluid (CSF) leakage in patients with spontaneous intracranial hypotension (SIH). In the current report, we present two patients who underwent RNC for suspected CSF leakage. Both patients underwent magnetic resonance imaging (MRI) and RNC for evaluation. We describe a simple method to increase the detection ability of RNC for CSF leakage in patients with SIH.

Analysis of Co-Tunneling Current in Fullerene Single-Electron Transistor

Science.gov (United States)

KhademHosseini, Vahideh; Dideban, Daryoosh; Ahmadi, MohammadTaghi; Ismail, Razali

2018-05-01

Single-electron transistors (SETs) are nano devices which can be used in low-power electronic systems. They operate based on coulomb blockade effect. This phenomenon controls single-electron tunneling and it switches the current in SET. On the other hand, co-tunneling process increases leakage current, so it reduces main current and reliability of SET. Due to co-tunneling phenomenon, main characteristics of fullerene SET with multiple islands are modelled in this research. Its performance is compared with silicon SET and consequently, research result reports that fullerene SET has lower leakage current and higher reliability than silicon counterpart. Based on the presented model, lower co-tunneling current is achieved by selection of fullerene as SET island material which leads to smaller value of the leakage current. Moreover, island length and the number of islands can affect on co-tunneling and then they tune the current flow in SET.

Prediction of leakage in the fixed mechanical seal

Directory of Open Access Journals (Sweden)

Asheichik Anatoly A.

2017-01-01

Full Text Available The questions of influence of the shape of contact surfaces on leakages through rubber seals in fixed connection of subassemblies are considered in the article. It is known from practice of operation of seals of various designs that the shape of contact surfaces and consequently also the shape of diagram of stresses in a contact zone considerably influences on value of leaks Linking leakage magnitude and distribution of contact stresses enables, firstly, more precisely calculate the amount of leakage for existing seals, and, secondly, to optimize the shape of the seals in their design in each case. As the result of experimental studies on the introduction of the rubber gasket ring fixed indenters different profiles found that by optimizing the shape of the indenter magnitude of leakage can be reduced by 10 times.

Evaluation of the leakage behavior of inflatable seals subject to severe accident conditions

International Nuclear Information System (INIS)

Parks, M.B.

1989-11-01

Sandia National Laboratories, under the sponsorship of the United States Nuclear Regulatory Commission, is currently developing test validated methods to predict the pressure capacity of light water reactor containment buildings when subjected to postulated severe accident conditions. These conditions are well beyond the design basis. Scale model tests of steel and reinforced concrete containments have been conducted as well as tests of typical containment penetrations. As a part of this effort, a series of tests was recently conducted to determine the leakage behavior of inflatable seals. These seals are used to prevent leakage around personnel and escape lock doors of some containments. The results of the inflatable seals tests are the subject of this report. Inflatable seals were tested at both room temperature and at elevated temperatures representative of postulated severe accident conditions. Both aged (radiation and thermal) and unaged seals were included in the test program. The internal seal pressure at the beginning of each test was varied to cover the range of seal pressures actually used in containments. For each seal pressure level, the external (containment) pressure was increased until significant leakage past the seals was observed. Parameters that were monitored and recorded during the tests were the internal seal pressure, chamber pressure, leakage past the seals, and temperature of the test chamber and fixture to which the seals were attached. 8 refs., 34 figs., 7 tabs

Markovian Processes for Quantitative Information Leakage

DEFF Research Database (Denmark)

Biondi, Fabrizio

Quantification of information leakage is a successful approach for evaluating the security of a system. It models the system to be analyzed as a channel with the secret as the input and an output as observable by the attacker as the output, and applies information theory to quantify the amount...... and randomized processes with Markovian models and to compute their information leakage for a very general model of attacker. We present the QUAIL tool that automates such analysis and is able to compute the information leakage of an imperative WHILE language. Finally, we show how to use QUAIL to analyze some...... of information transmitted through such channel, thus effectively quantifying how many bits of the secret can be inferred by the attacker by analyzing the system’s output. Channels are usually encoded as matrices of conditional probabilities, known as channel matrices. Such matrices grow exponentially...

Reactor coolant pump seal leakage monitoring

International Nuclear Information System (INIS)

Stevens, D.M.; Spencer, J.W.; Morris, D.J.; James, W.; Shugars, H.G.

1986-01-01

Problems with reactor coolant pump seals have historically accounted for a large percentage of unscheduled outages. Studies performed for the Electric Power Research Institute (EPRI) have shown that the replacement of coolant pump seals has been one of the leading causes of nuclear plant unavailability over the last ten years. Failures of coolant pump seals can lead to primary coolant leakage rates of 200-500 gallons per minute into the reactor building. Airborne activity and high surface contamination levels following these failures require a major cleanup effort and increases the time and personnel exposure required to refurbish the pump seals. One of the problems in assessing seal integrity is the inability to accurately measure seal leakage. Because seal leakage flow is normally very small, it cannot be sensed directly with normal flow instrumentation, but must be inferred from several other temperature and flow measurements. In operating plants the leakage rate has been quantified with a tipping-bucket gauge, a device which indicates when one quart of water has been accumulated. The tipping-bucket gauge has been used for most rainfall-intensity monitoring. The need for a more accurate and less expensive gauge has been addressed. They have developed a drop-counter precipitation sensor has been developed and optimized. The applicability of the drop-counter device to the problem of measuring seal leakage is being investigated. If a review of system specification and known drop-counter performance indicates that this method is feasible for measuring seal leak rates, a drop-counter gauge will be fabricated and tested in the laboratory. If laboratory tests are successful the gauge will be demonstrated in a pump test loop at Ontario Hydro and evaluated under simulated plant conditions. 3 references, 2 figures

Leakage characterization of a piloted power operated relief valve

International Nuclear Information System (INIS)

Ezekoye, L.I.; Hess, M.D.

1995-01-01

In Westinghouse Pressurized Water Reactors (PWRs), power operated relief valves (PORVs) are used to provide overpressure protection of the Pressurizer. The valves are fail closed globe valves which means that power is required to open the valves and, on loss of power, the valves close. There are two ways to operate the PORVs. The more common way is to directly couple the disc to an actuator via a disc-stem assembly. The type of design is not the object of this paper. The other and less common way of operating a PORV is by piloting the main valve such that the opening or closing of a pilot valve opens and closes the main valve. This is the design of interest. In most plants, the PORVs are installed with a water loop seal while in some plants no water loop seals are used. It is generally accepted that loop seal installation minimizes valve seat leakage. In non-loop seal installation, the valve seat is exposed to steam which increases the potential for seat leakage. This paper describes the results of some tests performed with nitrogen and steam to characterize the leakage potential of a pilot operated PORV. The test results were compared with seat leakage tests of check valves to provide insight on the leakage testing of pilot operated valves and check valves. The paper also compares the test data with leakage estimates using the ASME/ANSI OM Code guidance on valve leakage

Comparing Natural Gas Leakage Detection Technologies Using an Open-Source "Virtual Gas Field" Simulator.

Science.gov (United States)

Kemp, Chandler E; Ravikumar, Arvind P; Brandt, Adam R

2016-04-19

We present a tool for modeling the performance of methane leak detection and repair programs that can be used to evaluate the effectiveness of detection technologies and proposed mitigation policies. The tool uses a two-state Markov model to simulate the evolution of methane leakage from an artificial natural gas field. Leaks are created stochastically, drawing from the current understanding of the frequency and size distributions at production facilities. Various leak detection and repair programs can be simulated to determine the rate at which each would identify and repair leaks. Integrating the methane leakage over time enables a meaningful comparison between technologies, using both economic and environmental metrics. We simulate four existing or proposed detection technologies: flame ionization detection, manual infrared camera, automated infrared drone, and distributed detectors. Comparing these four technologies, we found that over 80% of simulated leakage could be mitigated with a positive net present value, although the maximum benefit is realized by selectively targeting larger leaks. Our results show that low-cost leak detection programs can rely on high-cost technology, as long as it is applied in a way that allows for rapid detection of large leaks. Any strategy to reduce leakage should require a careful consideration of the differences between low-cost technologies and low-cost programs.

Determination of leakage areas in nuclear piping

Energy Technology Data Exchange (ETDEWEB)

Keim, E. [Siemens/KWU, Erlangen (Germany)

1997-04-01

For the design and operation of nuclear power plants the Leak-Before-Break (LBB) behavior of a piping component has to be shown. This means that the length of a crack resulting in a leak is smaller than the critical crack length and that the leak is safely detectable by a suitable monitoring system. The LBB-concept of Siemens/KWU is based on computer codes for the evaluation of critical crack lengths, crack openings, leakage areas and leakage rates, developed by Siemens/KWU. In the experience with the leak rate program is described while this paper deals with the computation of crack openings and leakage areas of longitudinal and circumferential cracks by means of fracture mechanics. The leakage areas are determined by the integration of the crack openings along the crack front, considering plasticity and geometrical effects. They are evaluated with respect to minimum values for the design of leak detection systems, and maximum values for controlling jet and reaction forces. By means of fracture mechanics LBB for subcritical cracks has to be shown and the calculation of leakage areas is the basis for quantitatively determining the discharge rate of leaking subcritical through-wall cracks. The analytical approach and its validation will be presented for two examples of complex structures. The first one is a pipe branch containing a circumferential crack and the second one is a pipe bend with a longitudinal crack.

Determination of leakage areas in nuclear piping

International Nuclear Information System (INIS)

Keim, E.

1997-01-01

For the design and operation of nuclear power plants the Leak-Before-Break (LBB) behavior of a piping component has to be shown. This means that the length of a crack resulting in a leak is smaller than the critical crack length and that the leak is safely detectable by a suitable monitoring system. The LBB-concept of Siemens/KWU is based on computer codes for the evaluation of critical crack lengths, crack openings, leakage areas and leakage rates, developed by Siemens/KWU. In the experience with the leak rate program is described while this paper deals with the computation of crack openings and leakage areas of longitudinal and circumferential cracks by means of fracture mechanics. The leakage areas are determined by the integration of the crack openings along the crack front, considering plasticity and geometrical effects. They are evaluated with respect to minimum values for the design of leak detection systems, and maximum values for controlling jet and reaction forces. By means of fracture mechanics LBB for subcritical cracks has to be shown and the calculation of leakage areas is the basis for quantitatively determining the discharge rate of leaking subcritical through-wall cracks. The analytical approach and its validation will be presented for two examples of complex structures. The first one is a pipe branch containing a circumferential crack and the second one is a pipe bend with a longitudinal crack

Assessing Agulhas leakage

NARCIS (Netherlands)

van Sebille, E.

2009-01-01

Agulhas leakage, the water that flows from the Indian Ocean to the Atlantic Ocean, plays an important role in the circulation of the Atlantic Ocean. The magnitude of this flux of warm and saline Indian Ocean water into the much colder and fresher Atlantic Ocean can be related to the strength of the

Helium/solid powder O-ring leakage correlation experiments using a radiotracer

International Nuclear Information System (INIS)

Bild, R.W.; Leisher, W.B.; Weissman, S.H.; Seya, M.

1984-01-01

UO 2 definitely leaked past the O-ring in three of the tests confirming the major results of the previous work. Continuous leakage at these levels may require additional precautions under present regulatory policies. The mechanism and the time and particle size dependence for the leakage are not known, but there is some indication leakage is more likely at low temperatures. It is possible leakage is due to movement of the O-ring during temperature or pressure cycling at the beginning or end of a test. The radiotracer method involves less labor and is much less susceptible to contamination than the previous method. Future work will investigate leakage past lubricated O-rings and time dependence of leakage. 1 reference, 1 table

Component external leakage and rupture frequency estimates

International Nuclear Information System (INIS)

Eide, S.A.; Khericha, S.T.; Calley, M.B.; Johnson, D.A.; Marteeny, M.L.

1991-11-01

In order to perform detailed internal flooding risk analyses of nuclear power plants, external leakage and rupture frequencies are needed for various types of components - piping, valves, pumps, flanges, and others. However, there appears to be no up-to-date, comprehensive source for such frequency estimates. This report attempts to fill that void. Based on a comprehensive search of Licensee Event Reports (LERs) contained in Nuclear Power Experience (NPE), and estimates of component populations and exposure times, component external leakage and rupture frequencies were generated. The remainder of this report covers the specifies of the NPE search for external leakage and rupture events, analysis of the data, a comparison with frequency estimates from other sources, and a discussion of the results

Analysis of Planar E+I and ER+I Transformers for Low-Voltage High-Current DC/DC Converters with Focus on Winding Losses and Leakage Inductance

DEFF Research Database (Denmark)

Pittini, Riccardo; Zhang, Zhe; Ouyang, Ziwei

2012-01-01

on winding resistance and leakage inductances which represent the main concerns related to low-voltage high-current applications. The PCB winding design has a one to one turn ratio with no interleaving between primary and secondary windings. The main goal was to determine if ER planar core could provide...... a significant advantage in terms of winding losses compared to planar E cores. Results from finite element analysis highlight that low frequency winding resistance is lower for the ER core since it is dominated by the lower mean turn length however, as the AC-resistance becomes dominating the winding eddy...... more realistic results when computing the winding AC-resistance....

Artificial-Crack-Behavior Test Evaluation of the Water-Leakage Repair Materials Used for the Repair of Water-Leakage Cracks in Concrete Structures

OpenAIRE

Soo-Yeon Kim; Sang-Keun Oh; Byoungil Kim

2016-01-01

There are no existing standard test methods at home and abroad that can verify the performance of water leakage repair materials, and it is thus very difficult to perform quality control checks in the field of water leakage repair. This study determined that the key factors that have the greatest impact on the water leakage repair materials are the micro-behaviors of cracks, and proposed an artificial-crack-behavior test method for the performance verification of the repair materials. The per...

Anastomotic leakage after anterior resection for rectal cancer

DEFF Research Database (Denmark)

Bulow, S.

2008-01-01

On the basis of the literature about anastomotic leakage after anterior resection for rectal cancer a review is presented of the frequency, potential risk factors and consequences of leakage. The risk factors are evaluated according to the level of scientific evidence of the individual background...

Developement of leakage localization technique by using acoustic signal

Energy Technology Data Exchange (ETDEWEB)

Kim, Y. H.; Jeon, J. H.; Seo, D. H.; Kim, K. W. [KAIST, Daejeon (Korea, Republic of)

2010-07-15

The objective of this research is to develop a leakage monitoring system for pipelines or valves in the secondary water system of a nuclear power plant. The system aims to detect the existence of leakage and to estimate the leak location, especially by utilizing the noise generated from the leak. It is safe, precise real-time alert system compared with the previous monitoring methods and tools such as the visual test and the thermal imaging camera. When there exists leakage in the pipeline or valves of nuclear power plant, the noise due to gas flow is radiated through leak region. That is, the secondary water system with leakage generates different noise from the system without leakage. This motivates us to measure and analyze the noise generated from the secondary water system, so as firstly to detect the existence of leakage, and secondly to estimate the leak location by using the noise source identification technique such as beamforming and acoustic holography. Especially the beamforming method models the signal from the noise source to estimate the location of source. Therefore, it is necessary to model the noise due to leakage which is dependent upon parameters. In the process of leak localization, the reflected wave due to interior walls and the measurement noise should be removed for the precise estimation. Therefore, we attempt to characterize the reflected wave and the measurement noise by modeling the interior sound field, thus to remove them and to localize the leak location with high precision

The concept of leakage in threat assessment.

Science.gov (United States)

Meloy, J Reid; O'Toole, Mary Ellen

2011-01-01

Leakage in the context of threat assessment is the communication to a third party of an intent to do harm to a target. Third parties are usually other people, but the means of communication vary, and include letters, diaries, journals, blogs, videos on the internet, emails, voice mails, and other social media forms of transmission. Leakage is a type of warning behavior that typically infers a preoccupation with the target, and may signal the research, planning, and implementation of an attack. Nomothetic data suggest that leakage occurs in a majority of cases of attacks on and assassinations of public figures, adult mass murders, adolescent mass murders, and school or campus shootings: very low-frequency, but catastrophic acts of intended and targeted violence. Idiographic or case data illustrate the various permutations of leakage. We discuss the operational importance of the concept, place it in the context of other warning behaviors, emphasize the need for further research, and outline risk management strategies for the mitigation of such acts of violence in both law enforcement and clinical mental health settings. Copyright © 2011 John Wiley & Sons, Ltd.

Leakage evaluation in the PCV (Primary Containment Vessel) using chemical and radiochemical data

International Nuclear Information System (INIS)

Maeda, Katsuji; Nagasawa, Katsumi

1998-01-01

Keeping the reliability of nuclear power plant operation, the primary coolant leakage in the PCV is strictly restricted by the Technical Specifications. It is very important to detect an indication of leakage and estimate the source of leakage to provide countermeasures. Usually the indication of leakage will be detected by increase of drain flow in the PCV sump. There are some possibilities of leakage sources in the PCV, such as reactor water, main steam, condensate, feedwater and closed cooling water. The leakage source contain different chemical and radiochemical species. This means that the leakage source can be presumed and detected by using chemical information from the PCV atmosphere and sump water. To detect the leakage indication and the source quickly and exactly, the PCV Leakage Detection Expert System has been developed. This paper describes how to evaluate the leakage indication and source in the PCV by using chemical and radiochemical data. (author)

Short-term effects of CO2 leakage on the soil bacterial community in a simulated gas leakage scenario.

Science.gov (United States)

Ma, Jing; Zhang, Wangyuan; Zhang, Shaoliang; Zhu, Qianlin; Feng, Qiyan; Chen, Fu

2017-01-01

The technology of carbon dioxide (CO 2 ) capture and storage (CCS) has provided a new option for mitigating global anthropogenic emissions with unique advantages. However, the potential risk of gas leakage from CO 2 sequestration and utilization processes has attracted considerable attention. Moreover, leakage might threaten soil ecosystems and thus cannot be ignored. In this study, a simulation experiment of leakage from CO 2 geological storage was designed to investigate the short-term effects of different CO 2 leakage concentration (from 400 g m -2 day -1 to 2,000 g m -2 day -1 ) on soil bacterial communities. A shunt device and adjustable flow meter were used to control the amount of CO 2 injected into the soil. Comparisons were made between soil physicochemical properties, soil enzyme activities, and microbial community diversity before and after injecting different CO 2 concentrations. Increasing CO 2 concentration decreased the soil pH, and the largest variation ranged from 8.15 to 7.29 ( p soil CO 2 concentration increased. The dominant phylum in the soil samples was Proteobacteria , whose proportion rose rapidly from 28.85% to 67.93%. In addition, the proportion of Acidobacteria decreased from 19.64% to 9.29% ( p soil ecosystems.

Lung protein leakage in feline septic shock.

Science.gov (United States)

Schützer, K M; Larsson, A; Risberg, B; Falk, A

1993-06-01

The aim of the present study was to explore lung microvascular leakage of protein and water in a feline model of septic shock, using a double isotope technique with external gamma camera detection and gravimetric lung water measurements. The experiments were performed on artificially ventilated cats. One group of cats (n = 8) was given an infusion of live Escherichia coli bacteria, and another group (n = 5) served as a control group receiving saline. Plasma transferrin was radiolabeled in vivo with indium-113m-chloride, and erythrocytes were labeled with technetium-99m. The distribution of these isotopes in the lungs was continuously measured with a gamma camera. A normalized slope index (NSI) was calculated, indicative of the transferrin accumulation corrected for changes in local blood volume that reflect protein leakage. In the septic group there was a protein leakage after bacterial infusion, with a NSI of 39 x 10(-4) +/- 5 x 10(-4) min-1 (mean +/- SEM), and the PaO2 diminished from 21 +/- 1 to 9.5 +/- 1 kPa. In control cats a slight protein leakage with a NSI of 9 +/- 10(-4) +/- 2 x 10(-4) min-1 was detected, probably caused by the operative procedure, but PaO2 did not change. Wet-to-dry-weight ratios of postmortem lungs were not significantly different between the groups. It was concluded that an intravenous infusion of live E. coli bacteria induces a lung capillary protein leakage without increased lung water and a concomitantly disturbed gas exchange.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the white test for the intraoperative detection of bile leakage.

Science.gov (United States)

Leelawat, Kawin; Chaiyabutr, Kittipong; Subwongcharoen, Somboon; Treepongkaruna, Sa-Ad

2012-01-01

We assess whether the White test is better than the conventional bile leakage test for the intraoperative detection of bile leakage in hepatectomized patients. This study included 30 patients who received elective liver resection. Both the conventional bile leakage test (injecting an isotonic sodium chloride solution through the cystic duct) and the White test (injecting a fat emulsion solution through the cystic duct) were carried out in the same patients. The detection of bile leakage was compared between the conventional method and the White test. A bile leak was demonstrated in 8 patients (26.7%) by the conventional method and in 19 patients (63.3%) by the White test. In addition, the White test detected a significantly higher number of bile leakage sites compared with the conventional method (Wilcoxon signed-rank test; P detection of bile leakage. Based on our study, we recommend that surgeons investigating bile leakage sites during liver resections should use the White test instead of the conventional bile leakage test.

Leakage-Resilient Cryptography from the Inner-Product Extractor

DEFF Research Database (Denmark)

Dziembowski, Stefan; Faust, Sebastian

2011-01-01

We present a generic method to secure various widely-used cryptosystems against arbitrary side-channel leakage, as long as the leakage adheres three restrictions: first, it is bounded per observation but in total can be arbitrary large. Second, memory parts leak independently, and, third, the ran...

Hunting the unknown: White-box database leakage detection

NARCIS (Netherlands)

Costante, E.; Hartog, den J.I.; Petkovic, M.; Etalle, S.; Pechenizkiy, M.; Atluri, V.; Pernul, G.

2014-01-01

Data leakage causes significant losses and privacy breaches worldwide. In this paper we present a white-box data leakage detection system to spot anomalies in database transactions. We argue that our approach represents a major leap forward w.r.t. previous work because: i) it significantly decreases

Biomembrane Permeabilization: Statistics of Individual Leakage Events Harmonize the Interpretation of Vesicle Leakage.

Science.gov (United States)

Braun, Stefan; Pokorná, Šárka; Šachl, Radek; Hof, Martin; Heerklotz, Heiko; Hoernke, Maria

2018-01-23

The mode of action of membrane-active molecules, such as antimicrobial, anticancer, cell penetrating, and fusion peptides and their synthetic mimics, transfection agents, drug permeation enhancers, and biological signaling molecules (e.g., quorum sensing), involves either the general or local destabilization of the target membrane or the formation of defined, rather stable pores. Some effects aim at killing the cell, while others need to be limited in space and time to avoid serious damage. Biological tests reveal translocation of compounds and cell death but do not provide a detailed, mechanistic, and quantitative understanding of the modes of action and their molecular basis. Model membrane studies of membrane leakage have been used for decades to tackle this issue, but their interpretation in terms of biology has remained challenging and often quite limited. Here we compare two recent, powerful protocols to study model membrane leakage: the microscopic detection of dye influx into giant liposomes and time-correlated single photon counting experiments to characterize dye efflux from large unilamellar vesicles. A statistical treatment of both data sets does not only harmonize apparent discrepancies but also makes us aware of principal issues that have been confusing the interpretation of model membrane leakage data so far. Moreover, our study reveals a fundamental difference between nano- and microscale systems that needs to be taken into account when conclusions about microscale objects, such as cells, are drawn from nanoscale models.

Leakage Current Waveforms and Arcing Characteristics of Epoxy Resin for Outdoor Insulators under Clean and Salt Fogs

Directory of Open Access Journals (Sweden)

Suwarno

2008-05-01

Full Text Available Ceramic outdoor insulators have been used in high voltage transmission lines since long time ago. Due to superiority in their resistance to pollution, recently, polymeric outdoor insulators are widely used. Epoxy resin is one polymer which shows good properties for outdoor insulation. During service, outdoor insulators may severe a certain degree of pollution which may reduce their surface resistance. Leakage current (LC usually increase and degradation may take place. This paper reports experimental results on the leakage current waveforms and arcing characteristics of epoxy resin under clean and salt fog. The samples used are blocks of epoxy resin with dimension of 250 x 50 x 20 mm3. The samples were put in a test chamber with dimension of 900x900x1200 mm3 with controllable humidity and pollution conditions. Clean and salt fog were generated according to IEC 60-1 and 507. The arcing experiment was done with incline plane test in accordance with IEC 587. AC voltage in the range from 5 kV to 50 kV with frequency of 50 Hz was applied. The LC waveforms up to flash over were measured. The magnitudes as well as harmonic content of the LC were analyzed. The correlation between LC waveforms and dry band arching phenomenon was elaborated. Visual observation of the arc on the sample surfaces was observed using a video camera. Experimental results indicated that LC magnitude on clean samples was slightly affected by humidity (RH. However, under salt fog, RH greatly affected the LC magnitude. The flashover voltage of clean samples under salt fog reduced significantly for fog conductivity of more than 1.2 mS/cm. Kaolin-polluted samples under salt fog showed an Ohmic behaviour. The LC magnitude was high and a large discrepancy of LC magnitude was observed for high applied voltage of larger than 25 kV. The largest LC magnitude was observed on salt-kaolin polluted samples under clean fog at high RH. LC waveforms analysis indicated that in general LC waveforms

Leakage limits for inflatable seals of sodium cooled fast breeder reactor

Energy Technology Data Exchange (ETDEWEB)

Sinha, N.K., E-mail: nksinha@igcar.gov.in; Raj, Baldev

2014-01-15

Highlights: • All possible types/modes of gas escape covered. • Limits include simultaneous contributions from bypass and permeation leakage modes. • Leakage of radioactive cover gas with fission products assumed. • Possibility of sodium frost deposition in sealed gap considered. • Cover gas activity decay during fuel handling and relative importance of types/modes of leakage considered for realistic results and simpler seal design. -- Abstract: Estimation and stipulation of allowable leakage for inflatable seals of 500 MWe Prototype Fast Breeder Reactor is depicted. Leakage limits are specified using a conservative approach, which assumes escape of radioactive cover gas with fission products across the seals in bypass and permeation modes and possibility of sodium frost deposition in sealed gaps because of permeation leakage of inflation gas. Procedures to arrive at the allowable leakages of argon cover gas (normal-operation/fuel-handling: 10{sup −3}/10{sup −2} scc/s/m length of seal) and argon inflation gas (10{sup −3} scc/s/m length of seal) is described.

Performance-based containment leakage testing

International Nuclear Information System (INIS)

Cybulskis, P.

1995-01-01

The U.S. Nuclear Regulatory Commission (NRC) is reviewing regulatory requirements in an effort to revise those that are marginal to safety but impose significant burdens on licensees. Identification of requirements marginal to safety and development and evaluation of alternatives utilize the NRC safety goals and insights from probabilistic risk assessments (PRAs). Since earlier studies found design-basis containment leakage to be a minor contributor to reactor accident risk, containment leakage testing has been selected as a candidate for change in regulations. This paper summarizes the technical analyses supporting the NRC proposal to amend Appendix J of 10 CFR Part 50 as its first effort to decrease unnecessary regulatory burdens on licensees

Marginal Leakage of Class V Composite Resin Restorations

Directory of Open Access Journals (Sweden)

Maryam Khoroushi

2018-01-01

Full Text Available >Introduction: Marginal leakage is one of the significant causes of restoration failure. This in-vitro study was conducted to compare cone beam computed tomography (CBCT and dye-penetration methods for determining marginal leakage at gingival surface of class V resin composite restorations.Materials and Methods: Class V cavities were prepared on the buccal surfaces of nineteen caries-free extracted human molar teeth. Cavities were conditioned and filled. The teeth were immersed in a 50% w/w aqueous silver nitrate solution for 24 h and were taken out and rinsed with distilled water. Then, they were put into a developing solution. Whole specimens were first viewed with CBCT and were then sectioned and evaluated by stereomicroscope.Results: Measurement of agreement between CBCT and stereomicroscope revealed that 15 (78.9% teeth had score 0, 1 (5.3% tooth had score 1, and 1 (5.3% tooth had score 2 in both techniques. Measurement of agreement between CBCT and stereomicroscope techniques, in the detection of marginal leakage, was 89.5% (Kappa coefficient = 0.627, P = 0.00. The Wilcoxon paired rank test revealed no significant difference between the results of CBCT and stereomicroscope in measuring the leakage at gingival margin (P = 0.157.Conclusion: Considering the limitations of the study, there was no significant difference between the results of CBCT and stereomicroscope in measuring the leakage at gingival margin of class V composite restorations. CBCT can be used noninvasively to detect the marginal leakage of gingival wall of class V composite restorations using aqueous silver nitrate solution as a tracer.

Quantifying information leakage of randomized protocols

DEFF Research Database (Denmark)

Biondi, Fabrizio; Legay, Axel; Malacaria, Pasquale

2015-01-01

The quantification of information leakage provides a quantitative evaluation of the security of a system. We propose the usage of Markovian processes to model deterministic and probabilistic systems. By using a methodology generalizing the lattice of information approach we model refined attackers...... capable to observe the internal behavior of the system, and quantify the information leakage of such systems. We also use our method to obtain an algorithm for the computation of channel capacity from our Markovian models. Finally, we show how to use the method to analyze timed and non-timed attacks...

Quantifying Information Leakage of Randomized Protocols

DEFF Research Database (Denmark)

Biondi, Fabrizio; Wasowski, Andrzej; Legay, Axel

2013-01-01

The quantification of information leakage provides a quantitative evaluation of the security of a system. We propose the usage of Markovian processes to model and analyze the information leakage of deterministic and probabilistic systems. We show that this method generalizes the lattice...... of information approach and is a natural framework for modeling refined attackers capable to observe the internal behavior of the system. We also use our method to obtain an algorithm for the computation of channel capacity from our Markovian models. Finally, we show how to use the method to analyze timed...

Studies of axial-leakage simulations for homogeneous and heterogeneous EBR-II core configurations

International Nuclear Information System (INIS)

Grimm, K.N.; Meneghetti, D.

1985-08-01

When calculations of flux are done in less than three dimensions, leakage-absorption cross sections are normally used to model leakages (flows) in the dimensions for which the flux is not calculated. Since the neutron flux is axially dependent, the leakages, and hence the leakage-absorption cross sections, are also axially dependent. Therefore, to obtain axial flux profiles (or reaction rates) for individual subassemblies, an XY-geometry calculation delineating each subassembly has to be done at several axial heights with space- and energy-dependent leakage-absorption cross sections that are appropriate for each height. This report discusses homogeneous and heterogeneous XY-geometry calculations at various axial locations and using several differing assumptions for the calculation of the leakage-absorption cross section. The positive (outward) leakage-absorption cross sections are modeled as actual leakage absorptions, but the negative (inward) leakage-absorption cross sections are modeled as either negative leakage absorptions (+-B 2 method) or positive downscatter cross sections [the Σ/sub s/(1 → g) method]. 3 refs., 52 figs., 10 tabs

Influence of fuel assembly loading pattern and fuel burnups upon leakage neutron flux spectra from light water reactor core (Joint research)

International Nuclear Information System (INIS)

Kojima, Kensuke; Okumura, Keisuke; Kosako, Kazuaki; Torii, Kazutaka

2016-01-01

At the decommissioning of light water reactors (LWRs), it is important to evaluate an amount of radioactivity in the ex-core structures such as a reactor containment vessel, radiation shieldings, and so on. It is thought that the leakage neutron spectra in these radioactivation regions, which strongly affect the induced radioactivity, would be changed by different reactor core configurations such as fuel assembly loading pattern and fuel burnups. This study was intended to evaluate these effects. For this purpose, firstly, partial neutron currents on the core surfaces were calculated for some core configurations. Then, the leakage neutron flux spectra in major radioactivation regions were calculated based on the provided currents. Finally, influence of the core configurations upon the neutron flux spectra was evaluated. As a result, it has been found that the influence is small on the spectrum shapes of neutron fluxes. However, it is necessary to pay attention to the facts that intensities of the leakage neutron fluxes are changed by the configurations and that intensities and spectrum shapes of the leakage neutron fluxes are changed depending on the angular direction around the core. (author)

A Framework to Estimate CO2 Leakage associated with Geological Storage in Mature Sedimentary Basins

Science.gov (United States)

Celia, M. A.; Bachu, S.; Gasda, S.

2002-12-01

Geological storage of carbon dioxide requires careful risk analysis to avoid unintended consequences associated with the subsurface injection. Most negative consequences of subsurface injection are associated with leakage of the injected CO2 out of the geological formation into which it is injected. Such leakage may occur through natural geological features, including fractures and faults, or it may occur through human-created pathways such as existing wells. Possible leakage of CO2 through existing wells appears to be especially important in mature sedimentary basins that have been explored intensively and exploited for hydrocarbon production. In the Alberta Basin of western Canada, more than 300,000 oil and gas wells have been drilled, while in the state of Texas in the United States, more than 1,500,000 wells have been drilled. Many of these wells have been abandoned, and the information available to describe their current state is highly variable and sometimes nonexistent. Because these wells represent possible direct conduits from the injection zone to the land surface, a comprehensive assessment of leakage potential associated with these wells needs to be pursued. Analysis of leakage potential associated with existing wells must combine a data mining component with a multi-level modeling effort to assess leakage potential in a probabilistic framework. Information available for existing wells must be categorized and analyzed, and general leakage characteristics associated with wells of varying properties must be quantified. One example of a realistic target formation is the Viking Formation in Alberta, which is overlain by a thick shale layer and contains hydrocarbon in some locations. The existence of hydrocarbon in the formation indicates that the overlying shale layer is an effective barrier to flow, and therefore this is a good candidate formation for CO2 storage. However, the formation and its cap rock are punctured by approximately 180,000 wells, with

Trade study of leakage detection, monitoring, and mitigation technologies to support Hanford single-shell waste retrieval

International Nuclear Information System (INIS)

Hertzel, J.S.

1996-03-01

The U.S. Department of Energy has established the Tank Waste Remediation System to safely manage and dispose of low-level, high-level, and transuranic wastes currently stored in underground storage tanks at the Hanford Site in Eastern Washington. This report supports the Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) Milestone No. M-45-08-T01 and addresses additional issues regarding single-shell tank leakage detection, monitoring, and mitigation technologies and provide an indication of the scope of leakage detection, monitoring, and mitigation activities necessary to support the Tank Waste Remedial System Initial Single-shell Tank Retrieval System project

A PD-SOI based DTI-LOCOS combined cross isolation technique for minimizing TID radiation induced leakage in high density memory

International Nuclear Information System (INIS)

Qiao Fengying; Pan Liyang; Wu Dong; Liu Lifang; Xu Jun

2014-01-01

In order to minimize leakage current increase under total ionizing dose (TID) radiation in high density memory circuits, a new isolation technique, combining deep trench isolation (DTI) between the wells, local oxidation of silicon (LOCOS) isolation between the devices within the well, and a P-diffused area in order to limit leakage at the isolation edge is implemented in partly-depleted silicon-on-insulator (PD-SOI) technology. This radiation hardening technique can minimize the layout area by more than 60%, and allows flexible placement of the body contact. Radiation hardened transistors and 256 Kb flash memory chips are designed and fabricated in a 0.6 μm PD-SOI process. Experiments show that no obvious increase in leakage current is observed for single transistors under 1 Mrad(Si) radiation, and that the 256 Kb memory chip still functions well after a TID of 100 krad(Si), with only 50% increase of the active power consumption in read mode. (semiconductor devices)

Uncertainty Analysis of In leakage Test for Pressurized Control Room Envelop

Energy Technology Data Exchange (ETDEWEB)

Lee, J. B. [KHNP Central Research Institute, Daejeon (Korea, Republic of)

2013-10-15

In leakage tests for control room envelops(CRE) of newly constructed nuclear power plants are required to prove the control room habitability. Results of the in leakage tests should be analyzed using an uncertainty analysis. Test uncertainty can be an issue if the test results for pressurized CREs show low in leakage. To have a better knowledge of the test uncertainty, a statistical model for the uncertainty analysis is described here and a representative uncertainty analysis of a sample in leakage test is presented. A statistical method for analyzing the uncertainty of the in leakage test is presented here and a representative uncertainty analysis of a sample in leakage test was performed. By using the statistical method we can evaluate the test result with certain level of significance. This method can be more helpful when the difference of the two mean values of the test result is small.

Uncertainty Analysis of In leakage Test for Pressurized Control Room Envelop

International Nuclear Information System (INIS)

Lee, J. B.

2013-01-01

In leakage tests for control room envelops(CRE) of newly constructed nuclear power plants are required to prove the control room habitability. Results of the in leakage tests should be analyzed using an uncertainty analysis. Test uncertainty can be an issue if the test results for pressurized CREs show low in leakage. To have a better knowledge of the test uncertainty, a statistical model for the uncertainty analysis is described here and a representative uncertainty analysis of a sample in leakage test is presented. A statistical method for analyzing the uncertainty of the in leakage test is presented here and a representative uncertainty analysis of a sample in leakage test was performed. By using the statistical method we can evaluate the test result with certain level of significance. This method can be more helpful when the difference of the two mean values of the test result is small

Toward Understanding Tip Leakage Flows in Small Compressor Cores Including Stator Leakage Flow

Science.gov (United States)

Berdanier, Reid A.; Key, Nicole L.

2017-01-01

The focus of this work was to provide additional data to supplement the work reported in NASA/CR-2015-218868 (Berdanier and Key, 2015b). The aim of that project was to characterize the fundamental flow physics and the overall performance effects due to increased rotor tip clearance heights in axial compressors. Data have been collected in the three-stage axial research compressor at Purdue University with a specific focus on analyzing the multistage effects resulting from the tip leakage flow. Three separate rotor tip clearances were studied with nominal tip clearance gaps of 1.5 percent, 3.0 percent, and 4.0 percent based on a constant annulus height. Overall compressor performance was previously investigated at four corrected speedlines (100 percent, 90 percent, 80 percent, and 68 percent) for each of the three tip clearance configurations. This study extends the previously published results to include detailed steady and time-resolved pressure data at two loading conditions, nominal loading (NL) and high loading (HL), on the 100 percent corrected speedline for the intermediate clearance level (3.0 percent). Steady detailed radial traverses of total pressure at the exit of each stator row are supported by flow visualization techniques to identify regions of flow recirculation and separation. Furthermore, detailed radial traverses of time-resolved total pressures at the exit of each rotor row have been measured with a fast-response pressure probe. These data were combined with existing three-component velocity measurements to identify a novel technique for calculating blockage in a multistage compressor. Time-resolved static pressure measurements have been collected over the rotor tips for all rotors with each of the three tip clearance configurations for up to five loading conditions along the 100 percent corrected speedline using fast-response piezoresistive pressure sensors. These time-resolved static pressure measurements reveal new knowledge about the

Radiation leakage dose from Elekta electron collimation system.

Science.gov (United States)

Pitcher, Garrett M; Hogstrom, Kenneth R; Carver, Robert L

2016-09-08

This study provided baseline data required for a greater project, whose objective was to design a new Elekta electron collimation system having significantly lighter electron applicators with equally low out-of field leakage dose. Specifically, off-axis dose profiles for the electron collimation system of our uniquely configured Elekta Infinity accelerator with the MLCi2 treatment head were measured and calculated for two primary purposes: 1) to evaluate and document the out-of-field leakage dose in the patient plane and 2) to validate the dose distributions calculated using a BEAMnrc Monte Carlo (MC) model for out-of-field dose profiles. Off-axis dose profiles were measured in a water phantom at 100 cm SSD for 1 and 2 cm depths along the in-plane, cross-plane, and both diagonal axes using a cylindrical ionization chamber with the 10 × 10 and 20 × 20 cm2 applicators and 7, 13, and 20 MeV beams. Dose distributions were calculated using a previously developed BEAMnrc MC model of the Elekta Infinity accelerator for the same beam energies and applicator sizes and compared with measurements. Measured results showed that the in-field beam flatness met our acceptance criteria (± 3% on major and ±4% on diagonal axes) and that out-of-field mean and maximum percent leakage doses in the patient plane met acceptance criteria as specified by the International Electrotechnical Commission (IEC). Cross-plane out-of-field dose profiles showed greater leakage dose than in-plane profiles, attributed to the curved edges of the upper X-ray jaws and multileaf collimator. Mean leakage doses increased with beam energy, being 0.93% and 0.85% of maximum central axis dose for the 10 × 10 and 20 × 20 cm2 applicators, respectively, at 20 MeV. MC calculations predicted the measured dose to within 0.1% in most profiles outside the radiation field; however, excluding model-ing of nontrimmer applicator components led to calculations exceeding measured data by as much as 0.2% for some regions

Reactor coolant pressure boundary leakage detection system

International Nuclear Information System (INIS)

Dissing, E.; Svansson, L.

1980-01-01

This study deals with a system for monitoring the leakage of reactor coolant. This system is based primarily on the detection of the 13 N content in the containment atmosphere. 13 N is produced from the oxygen of the reactor water via the recoil proton nuclear process Hl+016/yields/ 13 N+ 4 He. The generation is therefore independent of fuel element leakage and of the corrosion product content in the water. It is solely related to the neutron flux level in the reactor core. Typical figures for the equilibrium 13 N concentration in the containment atmosphere following a 4 kg/minute coolant leakage are 5 kBq m/sup -3/ and 7 kBq m/sup -3/ for BWR and PWR respectively. These levels are readily measured with a 10 liter Ge(Li) flow detector assembly operated at elevated pressure. 8 refs

Reactor coolant pressure boundary leakage detection system

International Nuclear Information System (INIS)

Dissing, E.; Svansson, L.

1980-01-01

This study deals with a system for monitoring the leakage of reactor coolant. This system is based primarily on the detection of the N13 content in the containment atmosphere. N13 is produced from the oxygen of the reactor water via the recoil proton nuclear process Hl+016/yields/Nl3+He4. The generation is therefore independent of fuel element leakage and of the corrosion product content in the water. It is solely related to the neutron flux level in the reactor core. Typical figures for the equilibrium N13 concentration in the containment atmosphere following a 4 kg/minute coolant leakage are 5 kBq m/sup -3/ and 7 kBq m/sup -3/ for BWR and PWR respectively. These levels are readily measured with a 10 liter Ge(Li) flow detector assembly operated at elevated pressure. 8 refs

Reactor coolant pressure boundary leakage detection system

International Nuclear Information System (INIS)

Dissing, E.; Svansson, L.

1979-08-01

The present paper deals with a system for monitoring the leakage of reactor coolant. This system is based primarily on the detection of the N13 content in the containment atmosphere. N13 is produced from the oxygen of the reactor water via the recoil proton nuclear process H1+016 → N13+He4. The generation is therefore independent of fuel element leakage and of the corrosion product content in the water. It is solely related to the neutron flux level in the reactor core. Typical figures for the equilibrium N13 concentration in the containment atmosphere following a 4 kg/minute coolant leakage are 5 kBq m -3 and 7 kBq m -3 for BWR and PWR respectively. These levels are readily measured with a 10 liter Ge (Li) flow detector assembly operated at elevated pressure. (Auth.)

LMFBR technology. FFTF cover-gas leakage calculation

International Nuclear Information System (INIS)

Deboi, H.

1974-01-01

The FFTF LMFBR is intended to have a near zero release of radioactive gases during normal reactor operation with 1% failed fuel. This report presents calculations which provide an approximation of these cover gas leakages. Data from ongoing static and dynamic seal leak tests at AI are utilized. Leakage through both elastomeric and metallic seals in all sub-assemblies and penetrations comprising the reactor cover gas containment during reactor operation system are included

Some possible causes and probability of leakages in LMFBR steam generators

International Nuclear Information System (INIS)

Bolt, P.R.

1984-01-01

Relevant operational experience with steam generators for process and conventional plant and thermal and fast reactors is reviewed. Possible causes of water/steam leakages into sodium/gas are identified and data is given on the conditions necessary for failure, leakage probability and type of leakage path. (author)

Fractal modeling of fluidic leakage through metal sealing surfaces

Science.gov (United States)

Zhang, Qiang; Chen, Xiaoqian; Huang, Yiyong; Chen, Yong

2018-04-01

This paper investigates the fluidic leak rate through metal sealing surfaces by developing fractal models for the contact process and leakage process. An improved model is established to describe the seal-contact interface of two metal rough surface. The contact model divides the deformed regions by classifying the asperities of different characteristic lengths into the elastic, elastic-plastic and plastic regimes. Using the improved contact model, the leakage channel under the contact surface is mathematically modeled based on the fractal theory. The leakage model obtains the leak rate using the fluid transport theory in porous media, considering that the pores-forming percolation channels can be treated as a combination of filled tortuous capillaries. The effects of fractal structure, surface material and gasket size on the contact process and leakage process are analyzed through numerical simulations for sealed ring gaskets.

[Detection of marginal leakage of Class V restorations in vitro by micro-CT].

Science.gov (United States)

Gu, Lin-juan; Zhao, Xin-yi; Li, Shi-bao

2012-09-01

To evaluate the reliability and superiority of micro-CT in marginal leakage assessment of Class V restorations. Class V preparations with gingival margins in dentin and occlusal in enamel were made in sixteen extracted non-carious human molars and restored with dental bonding agents and composite resin. All teeth were then immersed in 50% ammonia-silver nitrate solution for 12 hours, followed by developing solution for 8 hours. Each restoration was scanned by a micro-CT and silver leakage was measured and three-dimensional image of the silver leakage alone cavity wall were reconstructed. Afterward, all restorations were sectioned and examined for leakage depth using a microscope. The silver leakage depth of each restoration obtained by micro-CT and microscope were compared for equivalency. The silver leakage depths in gingival wall obtained with micro-CT (0.78 mm) and microscope (0.74 mm) showed no significant difference (P > 0.05), while the judgment of leakage depths in occlusal wall in micro-CT image (0.40 mm) was affected by adjacent enamel structure, giving less leakage depths compared to microscope (0.72 mm)(P leakages showed channels on their way to spreading. Micro-CT can detect precisely the silver leakage in the dentin wall of a restoration and display its three-dimensional shape fully. Enamel structure affects the detection of the silver leakage next to it.

Reanastomosis with Stapler in Duodenojejunal Junction Anastomosis Leakage: A Case Report

Directory of Open Access Journals (Sweden)

Ahmet Seker

2013-04-01

Full Text Available After anastomosis leakages, treatment of patient gets more difficult and mortality rates increase. At lower level gastrointestinal anastomosis leakages, because of always there is an ostomy alternative, digestion problems are seen lesser. But at upper level gastrointestinal system anastomosis leakages, when it is taken account of nutrient condition of patient, requirement of making anastomos increases. So moratlity rates increase. At this article we aimed to present a different technique that we administered on management of a patient who had duodenojejunal junction anastomosis leakage.

Study on detecting leachate leakage of municipal solid waste landfill site.

Science.gov (United States)

Liu, Jiangang; Cao, Xianxian; Ai, Yingbo; Zhou, Dongdong; Han, Qiting

2015-06-01

The article studies the detection of the leakage passage of leachate in a waste landfill dam. The leachate of waste landfill has its own features, like high conductivity, high chroma and an increasing temperature, also, the horizontal flow velocity of groundwater on the leakage site increases. This article proposes a comprehensive tracing method to identify the leakage site of an impermeable membrane by using these features. This method has been applied to determine two leakage sites of the Yahu municipal solid waste landfill site in Pingshan District, Shenzhen, China, which shows that there are two leachate leakage passages in the waste landfill dam A between NZK-2 and NZK-3, and between NZK-6 and NZK-7. © The Author(s) 2015.

Investigation of Turbulent Tip Leakage Vortex in an Axial Water Jet Pump with Large Eddy Simulation

Science.gov (United States)

Hah, Chunill; Katz, Joseph

2012-01-01

Detailed steady and unsteady numerical studies were performed to investigate tip clearance flow in an axial water jet pump. The primary objective is to understand physics of unsteady tip clearance flow, unsteady tip leakage vortex, and cavitation inception in an axial water jet pump. Steady pressure field and resulting steady tip leakage vortex from a steady flow analysis do not seem to explain measured cavitation inception correctly. The measured flow field near the tip is unsteady and measured cavitation inception is highly transient. Flow visualization with cavitation bubbles shows that the leakage vortex is oscillating significantly and many intermittent vortex ropes are present between the suction side of the blade and the tip leakage core vortex. Although the flow field is highly transient, the overall flow structure is stable and a characteristic frequency seems to exist. To capture relevant flow physics as much as possible, a Reynolds-averaged Navier-Stokes (RANS) calculation and a Large Eddy Simulation (LES) were applied for the current investigation. The present study reveals that several vortices from the tip leakage vortex system cross the tip gap of the adjacent blade periodically. Sudden changes in local pressure field inside tip gap due to these vortices create vortex ropes. The instantaneous pressure filed inside the tip gap is drastically different from that of the steady flow simulation. Unsteady flow simulation which can calculate unsteady vortex motion is necessary to calculate cavitation inception accurately even at design flow condition in such a water jet pump.

Leakage potential through mechanical penetrations in a severe accident environment

International Nuclear Information System (INIS)

Koenig, L.N.

1986-01-01

This paper reviews the findings of an ongoing program, Integrity of Containment Penetrations Under Severe Accident Loads. The program is concerned with the leakage modes as well as the magnitude of leakage through mechanical penetrations in a containment building subject to a severe accident. Seal and gasket tests are used to evaluate the effect of radiation aging, thermal aging, seal geometry, and seal squeeze on seals and gaskets subjected to a hypothesized severe accident. The effects on leakage of the structural response of equipment hatches, personnel airlocks, and drywell heads subjected to severe accident pressures are studied by experiments and analyses. The data gathered during this program will be used to develop methodologies for predicting leakage

Technology evaluation for space station atmospheric leakage

Energy Technology Data Exchange (ETDEWEB)

Lemon, D.K.; Friesel, M.A.; Griffin, J.W.; Skorpik, J.R.; Shepard, C.L.; Antoniak, Z.I.; Kurtz, R.J.

1990-02-01

A concern in operation of a space station is leakage of atmosphere through seal points and through the walls as a result of damage from particle (space debris and micrometeoroid) impacts. This report describes a concept for a monitoring system to detect atmosphere leakage and locate the leak point. The concept is based on analysis and testing of two basic methods selected from an initial technology survey of potential approaches. 18 refs., 58 figs., 5 tabs.

Field size dependent mapping of medical linear accelerator radiation leakage

International Nuclear Information System (INIS)

Vu Bezin, Jérémi; De Vathaire, Florent; Diallo, Ibrahima; Veres, Attila; Lefkopoulos, Dimitri; Chavaudra, Jean; Deutsch, Eric

2015-01-01

The purpose of this study was to investigate the suitability of a graphics library based model for the assessment of linear accelerator radiation leakage. Transmission through the shielding elements was evaluated using the build-up factor corrected exponential attenuation law and the contribution from the electron guide was estimated using the approximation of a linear isotropic radioactive source. Model parameters were estimated by a fitting series of thermoluminescent dosimeter leakage measurements, achieved up to 100 cm from the beam central axis along three directions. The distribution of leakage data at the patient plane reflected the architecture of the shielding elements. Thus, the maximum leakage dose was found under the collimator when only one jaw shielded the primary beam and was about 0.08% of the dose at isocentre. Overall, we observe that the main contributor to leakage dose according to our model was the electron beam guide. Concerning the discrepancies between the measurements used to calibrate the model and the calculations from the model, the average difference was about 7%. Finally, graphics library modelling is a readily and suitable way to estimate leakage dose distribution on a personal computer. Such data could be useful for dosimetric evaluations in late effect studies. (paper)

Biomembrane Permeabilization: Statistics of Individual Leakage Events Harmonize the Interpretation of Vesicle Leakage

Czech Academy of Sciences Publication Activity Database

Braun, S.; Pokorná, Šárka; Šachl, Radek; Hof, Martin; Heerklotz, H.; Hoernke, M.

2018-01-01

Roč. 12, č. 1 (2018), s. 813-819 ISSN 1936-0851 R&D Projects: GA ČR GA17-03160S Institutional support: RVO:61388955 Keywords : leakage * dye release * pore Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 13.942, year: 2016

Climate Policy and Carbon Leakage

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

This report explores the effects of the EU emissions trading scheme on the aluminium sector (i.e. competitiveness loss and carbon leakage). With its very high electricity intensity, primary aluminium stands out in the heavy industry picture: a sector whose emissions are not capped in the present EU ETS, European aluminium smelters still stand to lose profit margins and, possibly, market shares, as electricity prices increase following CO2 caps on generators' emissions - the famous pass-through of CO2 prices into electricity prices. The analysis includes a method of quantification of this issue, based on two indicators: profit margins and trade flows. As the EU is at the forefront of such policy, the paper provides policy messages to all countries on how trade exposed energy-intensive industries can be 'moved' by carbon constraint. This also is a contentious topic in Australia, Japan, New Zealand, and the US, where ambitious climate policies -- including cap-and-trade systems -- are currently debated.

Detection of urinary leakage after radical retropubic prostatectomy by contrast enhanced ultrasound - do we still need conventional retrograde cystography?

Science.gov (United States)

Schoeppler, Gita M; Buchner, Alexander; Zaak, Dirk; Khoder, Wael; Staehler, Michael; Stief, Christian G; Reiser, Maximilian F; Clevert, Dirk-Andre

2010-12-01

To prospectively evaluate the accuracy of transvesical contrast-enhanced ultrasound (CEUS) as an alternative method for the detection of anastomotic leakage after radical retropubic prostatectomy (RRP) in comparison with the current standard method of conventional retrograde cystography (CG). Forty-three patients underwent RRP for histologically proven localized prostate cancer. The vesico-urethral anastomosis was evaluated 8 days after RRP by CG and CEUS. Any peri-anastomotic leakage was assessed and determined in CG and CEUS as follows: no extravasation (EV), small leakage (≤0.5 cm), moderate leakage (>0.5 cm to ≤2 cm), large leakage (>2 cm diameter of EV seen). In total, 21 (49%) patients showed a watertight anastomosis. Ten (23%), two (4.7%) and ten (23%) patients showed a small, intermediate and large EV, respectively. In 31 cases (72%) there was 100% agreement of CG and CEUS for detection of no, moderate and large EV, respectively. In nine cases a small and in two cases a moderate EV was categorized as watertight anastomosis by CEUS. Only in one case did CG detect a small EV where a large EV was detected in CEUS. The agreement between both methods was 95% for detecting absence or large leakages. CEUS is a promising imaging modality that seems to be equivalent to CG for detecting the presence of a large anastomotic leakage that is clinically relevant for postoperative persistence of the indwelling catheter. CEUS could be a cheap and time-saving alternative to the CG without exposure of the patient to radiation. © 2010 THE AUTHORS. JOURNAL COMPILATION © 2010 BJU INTERNATIONAL.

N13 - based reactor coolant pressure boundary leakage system

International Nuclear Information System (INIS)

Dissing, E.; Marbaeck, L.; Sandell, S.; Svansson, L.

1980-05-01

A system for the monitoring of leakage of coolant from the reactor coolant pressure boundary and auxiliary systems to the reactor containment, based on the detection of the N13 content in the atmosphere, has been tested. N13 is produced from the oxyegen of the reactor water via the recoil photon nuclear process H1 + 016 + He4. The generation of N13 is therefore independent of fuel element leakage and of the corrosion product content in the water. In the US AEC regulatory guide 1.45 has a leakage increase of 4 liter/ min been suggested as the response limit. The experiments carried out in Ringhals indicate, that with the accomplishment of minor improvements in the installation, a 4 liter/min leakage to the containment will give rise to a signal with a random error range of +- 0.25 liter/min, 99.7 % confidence level. (author)

Management and prevention of chylous leakage after laparoscopic lymphadenectomy.

Science.gov (United States)

Han, L-P; Zhang, H-M; Abha, H-D; Liu, T; Zhang, X-P

2014-01-01

To investigate the development and management of chylous leakage after laparoscopic retroperitoneal lymphadenectomy. From July 2006 to September 2013, 13 cases of chylous leakage after the laparoscopic lymphadenectomy (6 cases of renal cell carcinoma, 4 cases of gastric cancer, 2 cases of ovarian cancer, 1 case of endometrial cancer) were studied to analyze the occurrence, development and management of chylous leakage. In 3 cases (2 cases of renal cell carcinoma, 1 case of gastric cancer) massive amount of milky fluid drainage was be seen after the first two days post operation. Dietary intervention, TPN (total parenteral nutrition), somatostatin therapy, maintenance of continuous drainage helped to successfully manage the condition in about 1 month duration. In the remaining 10 cases, chylous leakage appeared after restoring normal diet. Managed with changes in diet and maintenance of unobstructed drainage, they were cured in about 2 weeks after treatment. There was significant reduction in drain output, ultrasonography did not reveal presence of free fluid collection in abdomen, and the patients were in good condition without signs and symptoms of infections. Chylous leakage is a rare complication of retroperitoneal lymph node dissection. Surgeons should be familiar with laparoscopic techniques, relevant anatomy and be aware of the fact that the effect of CO2 pressure and use of ultrasonic knife to occlude the lymphatic vessel can transiently block the leakage making the surgeon overlook them. Routine placement of indwelling drainage tube, immediate diagnosis, dietary modification, TPN, somatostatin and drainage are the modalities of conservative management.

Simulation and experimental research of heat leakage of cryogenic transfer lines

Science.gov (United States)

Deng, B. C.; Xie, X. J.; Pan, W.; Jiang, R. X.; Li, J.; Yang, S. Q.; Li, Q.

2017-12-01

The heat leakage of cryogenic transfer lines directly influences the performance of large-scale helium refrigerator. In this paper, a thermal model of cryogenic transfer line considering numerical simulation of support coupled with MLI was established. To validate the model, test platform of cryogenic transfer lines with the merits of disassembly outer pipe and changeable easily multi-layer insulation has been built. The experimental results of heat leakage through overall length of cryogenic transfer lines, support and multi-layer insulation were obtained. The heat leakages of multi-layer insulation, a support and the overall leakage are 1.02 W/m, 0.44 W and 1.46 W/m from experimental data, respectively. The difference of heat leakage of MLI between experiment and simulation were less than 5%. The temperature distribution of support and MLI obtained in presented model in good agreement with experimental data. It is expected to reduce the overall heat leakage of cryogenic transfer lines further by optimizing structure of support based on the above thermal model and test platform in this paper.

Pad use and patient reported bother from urinary leakage after radical prostatectomy.

Science.gov (United States)

Wallerstedt, Anna; Carlsson, Stefan; Nilsson, Andreas E; Johansson, Eva; Nyberg, Tommy; Steineck, Gunnar; Wiklund, N Peter

2012-01-01

To better understand clinically significant definitions of urinary incontinence we investigated the relationship between urinary leakage and patient reported bother from urinary leakage. A consecutive series of 1,411 men who underwent radical prostatectomy at Karolinska University Hospital, Stockholm, Sweden, from 2002 to 2006 were invited to complete a study specific questionnaire with questions on pad status, urinary leakage and bother from urinary leakage. Questionnaires were received from 1,179 men with a followup of greater than 1 year (median 2.2). Results showed that even a small amount of urinary leakage resulted in a high risk of urinary bother. Of 775 survivors 46 (6%) reporting 0 pads indicated moderate or much bother compared to 38 of 123 (31%) who reported using a security pad. When comparing the 2 groups, the risk of bother from urinary leakage was more than 5 times higher in the safety pad vs the 0 pad group (RR 5.2, 95% CI 3.5-7.7). As the number of pads increased, we noted a higher bother risk. Cross-tabulation of pad use and urinary leakage revealed wide variation in pad requirements despite the same answer to urinary leakage questions. If the definition of continence is based on pad use, for example safety pads, a certain number of men who report moderate or much bother from urinary leakage will be defined as continent. Our results also show that for each stated rate of urinary leakage men prove to have a major variation in the pad requirement. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

On designing of a low leakage patient-centric provider network.

Science.gov (United States)

Zheng, Yuchen; Lin, Kun; White, Thomas; Pickreign, Jeremy; Yuen-Reed, Gigi

2018-03-27

When a patient in a provider network seeks services outside of their community, the community experiences a leakage. Leakage is undesirable as it typically leads to higher out-of-network cost for patient and increases barrier for care coordination, which is particularly problematic for Accountable Care Organization (ACO) as the in-network providers are financially responsible for quality of care and outcome. We aim to design a data-driven method to identify naturally occurring provider networks driven by diabetic patient choices, and understand the relationship among provider composition, patient composition, and service leakage pattern. By doing so, we learn the features of low service leakage provider networks that can be generalized to different patient population. Data used for this study include de-identified healthcare insurance administrative data acquired from Capital District Physicians' Health Plan (CDPHP) for diabetic patients who resided in four New York state counties (Albany, Rensselaer, Saratoga, and Schenectady) in 2014. We construct a healthcare provider network based on patients' historical medical insurance claims. A community detection algorithm is used to identify naturally occurring communities of collaborating providers. For each detected community, a profile is built using several new key measures to elucidate stakeholders of our findings. Finally, import-export analysis is conducted to benchmark their leakage pattern and identify further leakage reduction opportunity. The design yields six major provider communities with diverse profiles. Some communities are geographically concentrated, while others tend to draw patients with certain diabetic co-morbidities. Providers from the same healthcare institution are likely to be assigned to the same community. While most communities have high within-community utilization and spending, at 85% and 86% respectively, leakage still persists. Hence, we utilize a metric from import-export analysis to

AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors with reduced leakage current and enhanced breakdown voltage using aluminum ion implantation

Energy Technology Data Exchange (ETDEWEB)

Sun, Shichuang [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Fu, Kai, E-mail: kfu2009@sinano.ac.cn, E-mail: cqchen@mail.hust.edu.cn; Yu, Guohao; Zhang, Zhili; Song, Liang; Deng, Xuguang; Li, Shuiming; Sun, Qian; Cai, Yong; Zhang, Baoshun [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Qi, Zhiqiang; Dai, Jiangnan; Chen, Changqing, E-mail: kfu2009@sinano.ac.cn, E-mail: cqchen@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

2016-01-04

This letter has studied the performance of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors on silicon substrate with GaN buffer treated by aluminum ion implantation for insulating followed by a channel regrown by metal–organic chemical vapor deposition. For samples with Al ion implantation of multiple energies of 140 keV (dose: 1.4 × 10{sup 14} cm{sup −2}) and 90 keV (dose: 1 × 10{sup 14} cm{sup −2}), the OFF-state leakage current is decreased by more than 3 orders and the breakdown voltage is enhanced by nearly 6 times compared to the samples without Al ion implantation. Besides, little degradation of electrical properties of the 2D electron gas channel is observed where the maximum drain current I{sub DSmax} at a gate voltage of 3 V was 701 mA/mm and the maximum transconductance g{sub mmax} was 83 mS/mm.

Effects of sub-seabed CO2 leakage: Short- and medium-term responses of benthic macrofaunal assemblages.

Science.gov (United States)

Amaro, T; Bertocci, I; Queiros, A M; Rastelli, E; Borgersen, G; Brkljacic, M; Nunes, J; Sorensen, K; Danovaro, R; Widdicombe, S

2018-03-01

The continued rise in atmospheric carbon dioxide (CO 2 ) levels is driving climate change and temperature shifts at a global scale. CO 2 Capture and Storage (CCS) technologies have been suggested as a feasible option for reducing CO 2 emissions and mitigating their effects. However, before CCS can be employed at an industrial scale, any environmental risks associated with this activity should be identified and quantified. Significant leakage of CO 2 from CCS reservoirs and pipelines is considered to be unlikely, however direct and/or indirect effects of CO 2 leakage on marine life and ecosystem functioning must be assessed, with particular consideration given to spatial (e.g. distance from the source) and temporal (e.g. duration) scales at which leakage impacts could occur. In the current mesocosm experiment we tested the potential effects of CO 2 leakage on macrobenthic assemblages by exposing infaunal sediment communities to different levels of CO 2 concentration (400, 1000, 2000, 10,000 and 20,000 ppm CO 2 ), simulating a gradient of distance from a hypothetic leakage, over short-term (a few weeks) and medium-term (several months). A significant impact on community structure, abundance and species richness of macrofauna was observed in the short-term exposure. Individual taxa showed idiosyncratic responses to acidification. We conclude that the main impact of CO 2 leakage on macrofaunal assemblages occurs almost exclusively at the higher CO 2 concentration and over short time periods, tending to fade and disappear at increasing distance and exposure time. Although under the cautious perspective required by the possible context-dependency of the present findings, this study contributes to the cost-benefit analysis (environmental risk versus the achievement of the intended objectives) of CCS strategies. Copyright © 2018. Published by Elsevier Ltd.

Contrast media for radiological examination in gastrointestinal tract leakage

NARCIS (Netherlands)

A.Z. Ginai (Abida)

1987-01-01

textabstractThe aim of this investigation has been to find a safe and suitable contrast medium for radiological evaluation of the gastrointestinal tract in cases where leakage outside the GIT can be suspected. Leakage outside the gastro-intestinal tract lumen can occur in many ways eg.,

PLASMA LEAKAGE PROFILES OF DENGUE HEMORRHAGIC FEVER PATIENTS IN RSUD DR. SOETOMO, SURABAYA, EAST JAVA, INDONESIA JANUARY – JUNE 2014

Directory of Open Access Journals (Sweden)

Ferdian Rizaliansyah

2017-04-01

Full Text Available Plasma leakage is one crucial point of dengue hemorrhagic fever (DHF that differentiates it from dengue fever (DF. DHF has to meet 4 criteria which are 2 – 7 days of acute fever, hemorrhagic manifestation, thrombocytopenia (≤100.000 cells/mm3 and evidence of plasma leakage. Plasma leakage consists of increasing hematocrit ≥20%, hypoalbuminemia or evidence of pleural effusion or ascites. Often doctors only base their DHF diagnosis on the presence of thrombocytopenia. This study analyzed the presence of plasma leakage between adult and pediatric patients with a DHF diagnosis in RSUD Dr. Soetomo in order to make the diagnosis and healthcare services better in the future. This was a retrospective study which used medical records of DHF patients admitted from January to June 2014. 78 cases were included, 24 adult patients (31% and 54 pediatric patients (69%. 29/78 (37% patients had no evidence of plasma leakage. No adult patients had ascites whereas 11/54 (20% pediatric patients presented with ascites. No adult patients had pleural effusion whereas 25/54 (53% pediatric patients did. Most adult patients that had serum albumin checked had normal albumin levels (12/14 [86%] while only 14/28 (52% pediatric patients had normal albumin level. 5/22 (23% adult patients versus 32/53 (60% pediatric patients showed hematocrit increments ≥20%. Patients admitted with dengue virus infection may currently be often misclassified as DHF because there are no plasma leakage manifestation in some patients.. There are significant differences in plasma leakage manifestations between adult and pediatric patients which poses a theory that pediatric patients are more susceptible to have plasma leakage manifestations than adult patients.

Transanal stent in anterior resection does not prevent anastomotic leakage

DEFF Research Database (Denmark)

Bülow, Steffen; Bulut, O; Christensen, Ib Jarle

2006-01-01

OBJECTIVE: A defunctioning transanal stent may theoretically reduce the leakage rate after anterior rectal resection. We present a randomized open study with the aim of comparing the leakage rate after anterior resection with a loop ileostomy, a transanal stent, both or neither. PATIENTS AND METH....... On this basis it was decided to discontinue the study prematurely for ethical reasons. CONCLUSION: Decompression of the anastomosis with a transanal stent does not reduce the risk of anastomotic leakage after anterior resection.......OBJECTIVE: A defunctioning transanal stent may theoretically reduce the leakage rate after anterior rectal resection. We present a randomized open study with the aim of comparing the leakage rate after anterior resection with a loop ileostomy, a transanal stent, both or neither. PATIENTS...... AND METHODS: Randomized open trial of 194 patients operated in 11 hospitals during September 2000 to September 2003 with anterior resection for a mobile rectal tumour, 115 men and 79 women, median age 68 years (range 37-90 years). The surgeon decided upon the use of a protective ileostomy, and after...

New Method for Leakage Detection by Using Artificial Neural Networks

Directory of Open Access Journals (Sweden)

Mohammad Attari

2018-03-01

Full Text Available Nowadays water loss has been turned into a global concern and on the other hand the demand for water is increasing. This problem has made the demand management and consumption pattern reform necessary. One of the most important methods for managing water consumption is to decrease the water loss. In this study by using neural networks, a new method is presented to specify the location and quantity of leakages in water distribution networks.  In this method, by producing the training data and applying it to neural network, the network is able to determine approximate location and quantity of nodal leakage with receiving the nodal pressure. Production of training data is carried out by applying assumed leakage to specific nodes in the network and calculating the new nodal pressures. The results show that by minimum use of hydraulic data taken from pressures, not only this method can determine the location of nodal leakages, but also it can specify the amount of leakage on each node with reasonable accuracy.

Modelling of heterogenous neutron leakages in a nuclear reactor

International Nuclear Information System (INIS)

Wohleber, X.

1997-01-01

The TIBERE Model is a neutron leakage method based on B 1 heterogeneous transport equation resolution. In this work, we have studied the influence of the reflection mode at the boundary of the assembly. In particular the White boundary condition has been implemented in the APOLLO2 neutron transport code. We have compared the two TIBERE kinds of boundary conditions (specular and white) with the classical B 1 homogeneous leakage method in the modelling of some reactors. We have remarked the better capability of the TIBERE Model to compute voided assemblies. The white boundary condition is also able to compute a completely voided assembly and, besides, wins a factor 10 in CPU time in comparison with the specular boundary condition. These two heterogenous leakage formalisms have been tested on a partially voided experiment and have shown that the TIBERE Model can compute this kind of situation with a greater precision than the classical B 1 homogeneous leakage method, and with a shorter computational time. (author)

Intensity and Compactness Enabled Saliency Estimation for Leakage Detection in Diabetic and Malarial Retinopathy.

Science.gov (United States)

Zhao, Yitian; Zheng, Yalin; Liu, Yonghuai; Yang, Jian; Zhao, Yifan; Chen, Duanduan; Wang, Yongtian

2017-01-01

Leakage in retinal angiography currently is a key feature for confirming the activities of lesions in the management of a wide range of retinal diseases, such as diabetic maculopathy and paediatric malarial retinopathy. This paper proposes a new saliency-based method for the detection of leakage in fluorescein angiography. A superpixel approach is firstly employed to divide the image into meaningful patches (or superpixels) at different levels. Two saliency cues, intensity and compactness, are then proposed for the estimation of the saliency map of each individual superpixel at each level. The saliency maps at different levels over the same cues are fused using an averaging operator. The two saliency maps over different cues are fused using a pixel-wise multiplication operator. Leaking regions are finally detected by thresholding the saliency map followed by a graph-cut segmentation. The proposed method has been validated using the only two publicly available datasets: one for malarial retinopathy and the other for diabetic retinopathy. The experimental results show that it outperforms one of the latest competitors and performs as well as a human expert for leakage detection and outperforms several state-of-the-art methods for saliency detection.

Evaluation of the White Test for the Intraoperative Detection of Bile Leakage

OpenAIRE

Leelawat, Kawin; Chaiyabutr, Kittipong; Subwongcharoen, Somboon; Treepongkaruna, Sa-ad

2012-01-01

We assess whether the White test is better than the conventional bile leakage test for the intraoperative detection of bile leakage in hepatectomized patients. This study included 30 patients who received elective liver resection. Both the conventional bile leakage test (injecting an isotonic sodium chloride solution through the cystic duct) and the White test (injecting a fat emulsion solution through the cystic duct) were carried out in the same patients. The detection of bile leakage was c...

On camera-based smoke and gas leakage detection

Energy Technology Data Exchange (ETDEWEB)

Nyboe, Hans Olav

1999-07-01

Gas detectors are found in almost every part of industry and in many homes as well. An offshore oil or gas platform may host several hundred gas detectors. The ability of the common point and open path gas detectors to detect leakages depends on their location relative to the location of a gas cloud. This thesis describes the development of a passive volume gas detector, that is, one than will detect a leakage anywhere in the area monitored. After the consideration of several detection techniques it was decided to use an ordinary monochrome camera as sensor. Because a gas leakage may perturb the index of refraction, parts of the background appear to be displaced from their true positions, and it is necessary to develop algorithms that can deal with small differences between images. The thesis develops two such algorithms. Many image regions can be defined and several feature values can be computed for each region. The value of the features depends on the pattern in the image regions. The classes studied in this work are: reference, gas, smoke and human activity. Test show that observation belonging to these classes can be classified fairly high accuracy. The features in the feature set were chosen and developed for this particular application. Basically, the features measure the magnitude of pixel differences, size of detected phenomena and image distortion. Interesting results from many experiments are presented. Most important, the experiments show that apparent motion caused by a gas leakage or heat convection can be detected by means of a monochrome camera. Small leakages of methane can be detected at a range of about four metres. Other gases, such as butane, where the densities differ more from the density of air than the density of methane does, can be detected further from the camera. Gas leakages large enough to cause condensation have been detected at a camera distance of 20 metres. 59 refs., 42 figs., 13 tabs.

Theory and Practice of a Leakage Resilient Masking Scheme

DEFF Research Database (Denmark)

Balasch, Josep; Faust, Sebastian; Gierlichs, Benedikt

2012-01-01

A recent trend in cryptography is to formally prove the leakage resilience of cryptographic implementations – that is, one formally shows that a scheme remains provably secure even in the presence of side channel leakage. Although many of the proposed schemes are secure in a surprisingly strong m...

IMPACT OF DUCT LEAKAGE PRESSURES ON THE SHAPE OF THE DELTA Q CURVE

International Nuclear Information System (INIS)

Andrews, J.W.

2002-01-01

The question of whether and to what extent information on the pressures driving duct leaks can be extracted from the data taken during the Delta Q test for duct leakage is investigated. Curves of Delta Q vs. house pressure are generated for sets of cases where the supply and return leakage rates to/from outside are held constant while the leakage pressures are varied. It is found that the Delta Q curve takes on two qualitatively different shapes, one for leakage pressures within the range of house pressures used in the Delta Q test (i.e., -25 Pa to +25 Pa) and the other for leakage pressures well outside this range. These effects are seen in experimental data taken with leakage at known pressures. However, extracting the signal of the leakage pressure from the surrounding noise caused by random measurement variation is likely to be a difficult problem in many cases

Automated detection of leakage in fluorescein angiography images with application to malarial retinopathy.

Science.gov (United States)

Zhao, Yitian; MacCormick, Ian J C; Parry, David G; Leach, Sophie; Beare, Nicholas A V; Harding, Simon P; Zheng, Yalin

2015-06-01

The detection and assessment of leakage in retinal fluorescein angiogram images is important for the management of a wide range of retinal diseases. We have developed a framework that can automatically detect three types of leakage (large focal, punctate focal, and vessel segment leakage) and validated it on images from patients with malarial retinopathy. This framework comprises three steps: vessel segmentation, saliency feature generation and leakage detection. We tested the effectiveness of this framework by applying it to images from 20 patients with large focal leak, 10 patients with punctate focal leak, and 5,846 vessel segments from 10 patients with vessel leakage. The sensitivity in detecting large focal, punctate focal and vessel segment leakage are 95%, 82% and 81%, respectively, when compared to manual annotation by expert human observers. Our framework has the potential to become a powerful new tool for studying malarial retinopathy, and other conditions involving retinal leakage.

Application Of The Climafor Baseline To Determine Leakage: TheCase Of Scolel Te.

Energy Technology Data Exchange (ETDEWEB)

De Jong, B.H.J.; Bazan, E. Esquivel; Quechulpa Montalvo, S.

2007-06-01

The acceptance of forestry-based project activities tomitigate greenhouse gases emissions has been subjected to a number ofmethodological questions to be answered, of which the most challengingare baseline establishment and identification of and measuring leakage.Here we pose hypotheses for and quantify leakage of the Scolel Te projectin Chiapas, Mexico. In this project small-scale farmers are implementingforestry, agroforestry, and forest conservation activities, with carbonsequestration as one of the goals. The main leakage monitoring domain isdefined as the area owned by the participating farmers or communitiesoutside the area where the specific project activities take place. Thenull-hypothesis (no leakage) is that non-project land owned by the farmeror community will experience the same carbon stock changes as predictedby the regional baseline, specifically developed for the project. Firstwe assessed the most likely causes and sources of leakage that may occurin the project. From this analysis, one type of leakage seems to beimportant, i.e., activity shifting. Second we estimated the leakage of asample of participating farmers and communities. Actual land use was thencompared with expected land use derived from the baseline. The Plan Vivoof each participant, complemented with readily available tools toidentify the main sources and drivers of leakage are used to developsimple leakage assessment procedures, as demonstrated in this paper.Negative leakage was estimated to be negligible in this study.Incorporating these procedures already in the project planning stage willreduce the uncertainties related to the actual carbon mitigationpotential of any forestry project.

Magnetic leakage shield of septum magnet for SPring-8 synchrotron

International Nuclear Information System (INIS)

Abe, Hiroshi; Aoki, Tsuyoshi; Fukami, Kenji

1997-01-01

This paper describes magnetic field measurements of the prototype septum magnet and countermeasure for reducing the leakage magnetic fields in the incidence and the extraction parts of the SPring-8 synchrotron. We studied and developed 'leakage magnetic shield' on the basis of the tests data got in these measurements. Consequentially, it succeeded in reducing effects of the leakage field to about 50% by installing the shield board in the magnet main body. Then, it was possible to manufacture the magnet which sufficiently held the effect of the leakage field for the electron and positron beam. In this examination, we confirmed the reproduction with the magnetic field distribution of the magnet measured in the manufacturer. We developed and produced of the septum magnets which were carried out determination of the shapes of the magnetic shielding. (author)

Clear corneal incision leakage after phacoemulsification--detection using povidone iodine 5%.

Science.gov (United States)

Chee, Soon-Phaik

2005-01-01

The purpose of this work was to study the incidence of clear corneal wound leakage at the conclusion of standard co-axial phacoemulsification in a prospective observational series of 100 consecutive cataract cases in a single surgeon's institutional practice. At the conclusion of standard co-axial phacoemulsification using a 2.75 mm temporal single plane clear corneal incision with a 1 mm clear corneal side-port incision, the wounds were hydrated and checked for water-tightness. Povidone iodine 5% (P-I) was then evenly dripped over the cornea and the wounds were inspected visually. Any leakage of aqueous observed was recorded. The amount of leakage was graded as small or large from each wound. Leaky wounds were further hydrated and retested with P-I until sealed. Wound integrity was reassessed on the first postoperative day by use of fluorescein. Of the 100 cases, wound leakage was observed for 31 eyes (31%)-ten main incisions, nineteen side-port incisions, and both incisions in two cases. Wound leakage was easily detected as a ribbon of clear fluid streaming from the incision amid a pool of brown solution. Povidone iodine was not observed within the tract in any incision. All wound leakage was small except for one from the main incision and two from the side-port incision. None of the eyes developed wound leakage the day after surgery and none developed endophthalmitis. In conclusion, leakage from clear corneal incisions at the conclusion of phacoemulsification occurs in almost a third of cases, predominantly from the side incision. It is easily detected by use of the P-I test.

Theory and Application of Magnetic Flux Leakage Pipeline Detection.

Science.gov (United States)

Shi, Yan; Zhang, Chao; Li, Rui; Cai, Maolin; Jia, Guanwei

2015-12-10

Magnetic flux leakage (MFL) detection is one of the most popular methods of pipeline inspection. It is a nondestructive testing technique which uses magnetic sensitive sensors to detect the magnetic leakage field of defects on both the internal and external surfaces of pipelines. This paper introduces the main principles, measurement and processing of MFL data. As the key point of a quantitative analysis of MFL detection, the identification of the leakage magnetic signal is also discussed. In addition, the advantages and disadvantages of different identification methods are analyzed. Then the paper briefly introduces the expert systems used. At the end of this paper, future developments in pipeline MFL detection are predicted.

Effects of cavity on leakage loss in straight-through labyrinth seals

International Nuclear Information System (INIS)

Zhao, W; Nielsen, T K; Billdal, J T

2010-01-01

Labyrinth seals are widely used in rotating fluid machinery, due to its low-cost, simplicity and reliability. A straight-through labyrinth seal consists of a clearance between the stator and rotor, and sometimes cavities which are included on the stator or the rotator side. In this type of seals, making cavities are an effective way to convert turbulence kinetic energy into thermal energy by forming turbulence vortices, thereby reducing pressure difference and leakage flow. In this paper, the effect of cavities on leakage loss in straight-through labyrinth seals are studied by changing cavity dimensions such as depth and length, cavity number and cavity location. The influences of unilateral cavities and bilateral cavities on the leakage loss in straight-through labyrinth seals are also compared. The fluid flow characteristics through straight-through labyrinth seals were obtained by using viscous flow analysis along with a standard k-ωturbulence model. The cavity dimensions and cavity numbers have significant effects on the leakage as well as on the flow pattern in the seal. The bilateral cavity has better leakage performance than the unilateral cavity when cavity dimensions are identical. However, the cavity location shows no significant influences on the leakage flow.

Geologic Carbon Sequestration Leakage Detection: A Physics-Guided Machine Learning Approach

Science.gov (United States)

Lin, Y.; Harp, D. R.; Chen, B.; Pawar, R.

2017-12-01

One of the risks of large-scale geologic carbon sequestration is the potential migration of fluids out of the storage formations. Accurate and fast detection of this fluids migration is not only important but also challenging, due to the large subsurface uncertainty and complex governing physics. Traditional leakage detection and monitoring techniques rely on geophysical observations including pressure. However, the resulting accuracy of these methods is limited because of indirect information they provide requiring expert interpretation, therefore yielding in-accurate estimates of leakage rates and locations. In this work, we develop a novel machine-learning technique based on support vector regression to effectively and efficiently predict the leakage locations and leakage rates based on limited number of pressure observations. Compared to the conventional data-driven approaches, which can be usually seem as a "black box" procedure, we develop a physics-guided machine learning method to incorporate the governing physics into the learning procedure. To validate the performance of our proposed leakage detection method, we employ our method to both 2D and 3D synthetic subsurface models. Our novel CO2 leakage detection method has shown high detection accuracy in the example problems.

Blower-door techniques for measuring interzonal leakage

Energy Technology Data Exchange (ETDEWEB)

Hult, Erin L.; Sherman, Max H.; Walker, Iain

2013-01-01

Abstract The standard blower door test methods, such as ASTM E779, describe how to use a single blower door to determine the total leakage of a single-zone structure such as a detached single-family home. There are no standard test methods for measuring interzonal leakage in a two-zone or multi-zone building envelope such as might be encountered in with an attached garage or in a multifamily building. Some practitioners have been using techniques that involve making multiple measurements with a single blower door as well as combined measurements using multiple blower doors. Even for just two zones there are dozens of combinations of one-door and two-door test protocols that could conceivably be used to determine the interzonal air tightness. We examined many of these two-zone configurations using both simulation and measured data to estimate the accuracy and precision of each technique for realistic measurement scenarios. We also considered the impact of taking measurements at a single pressure versus over multiple pressures. We compared the various techniques and evaluated them for specific uses. Some techniques work better in one leakage regime; some are more sensitive to wind and other noise; some are more suited to determining only a subset of the leakage values. This paper makes recommendations on which techniques to use or not use for various cases and provides data that could be used to develop future test methods.

An Empirical Assessment of the Risk of Carbon Leakage in Poland - Working Paper No. 08/13,

International Nuclear Information System (INIS)

Sartor, Oliver; Spencer, Thomas

2013-01-01

Poland is a particularly carbon intensive economy. This has created concern that it may be particularly exposed to carbon leakage. However, there is an absence of robust and transparent empirical research on carbon leakage risks in Poland. This study aims at filling this gap by assessing the impact of EU climate policy, in particular the EU Emissions Trading Scheme, on Polish industry. With no mitigating measures, a small number of Polish industrial sectors would face significant carbon costs. However, with free allocation, banked surplus allowances and a carbon price of euros 30/ton, only one sector would face direct carbon costs in excess of 5% of operating profits. Three sectors face direct carbon costs in the order of 1-3% of operating profits; three face no direct carbon costs. With direct compensation for indirect carbon costs (electricity price increases), the two most affected sectors would face indirect costs of 3.5 to 5.5% of gross value added with a carbon price of euros 30/ ton. The vast majority of Poland's trade in energy intensive sectors occurs within the EU. It is important to maintain a harmonized climate policy to avoid internal market distortions. There is thus a negligible risk of carbon leakage in Poland under current policy. The mitigating measures in the EU Directive remove the vast majority of direct and indirect carbon costs for Polish industry. EU climate policy can be made more stringent without inducing risks of significant carbon leakage. The current benchmarking system appears to be reasonably effective at not structurally disadvantaging less carbon efficient Member States like Poland. And it is vital to maintaining a harmonized climate policy. Finding a harmonized way to address indirect carbon costs may unlock Polish support for future policy. (authors)

Effect of Reverse Bias Stress on Leakage Currents and Breakdown Voltages of Solid Tantalum Capacitors

Science.gov (United States)

Teverovsky, Alexander A.

2011-01-01

The majority of solid tantalum capacitors are produced by high-temperature sintering of a fine tantalum powder around a tantalum wire followed by electrolytic anodization that forms a thin amorphous Ta2O5 dielectric layer and pyrolysis of manganese nitrite on the oxide to create a conductive manganese dioxide electrode. A contact to tantalum wire is used as anode terminal and to the manganese layer as a cathode terminal of the device. This process results in formation of an asymmetric Ta -- Ta2O5 -- MnO2 capacitor that has different characteristics at forward (positive bias applied to tantalum) and reverse (positive bias applied to manganese cathode) voltages. Reverse bias currents might be several orders of magnitude larger than forward leakage currents so I-V characteristics of tantalum capacitors resemble characteristics of semiconductor rectifiers. Asymmetric I-V characteristics of Ta -- anodic Ta2O5 systems have been observed at different top electrode materials including metals, electrolytes, conductive polymers, and manganese oxide thus indicating that this phenomenon is likely related to the specifics of the Ta -- Ta2O5 interface. There have been multiple attempts to explain rectifying characteristics of capacitors employing anodic tantalum pentoxide dielectrics. A brief review of works related to reverse bias (RB) behavior of tantalum capacitors shows that the mechanism of conduction in Ta -- Ta2O5 systems is still not clear and more testing and analysis is necessary to understand the processes involved. If tantalum capacitors behave just as rectifiers, then the assessment of the safe reverse bias operating conditions would be a relatively simple task. Unfortunately, these parts can degrade with time under reverse bias significantly, and this further complicates analysis of the I-V characteristics and establishing safe operating areas of the parts. On other hand, time dependence of reverse currents might provide additional information for investigation of

Experimental evaluation of clinical colon anastomotic leakage

DEFF Research Database (Denmark)

Pommergaard, Hans-Christian

2014-01-01

, whereas the eight-suture control anastomoses had a 0% leakage rate. Furthermore, the use of absorbable suture together with voluntarily ingested Temgesic in chocolate spread as analgesic regimen were feasible. This model may be used to test the leakage reducing potential of coating materials. STUDY 3...... experimental, in which designs were not comparable and many results were contradictory. In a clinical study, a non-significant benefit of fibrin sealant was found. Based on the available clinical and experimental data it was concluded that the fibrin-based sealants, such as Tisseel and Tachosil...

Partially polymerized liposomes: stable against leakage yet capable of instantaneous release for remote controlled drug delivery

Energy Technology Data Exchange (ETDEWEB)

Qin Guoting; Li Zheng; Xia Rongmin; Li Feng; O' Neill, Brian E; Li, King C [Department of Radiology, The Methodist Hospital Research Institute, Houston, TX 77030 (United States); Goodwin, Jessica T; Khant, Htet A; Chiu, Wah, E-mail: zli@tmhs.org, E-mail: kli@tmhs.org [National Center for Macromolecular Imaging, Baylor College of Medicine, Houston, TX 77030 (United States)

2011-04-15

A critical issue for current liposomal carriers in clinical applications is their leakage of the encapsulated drugs that are cytotoxic to non-target tissues. We have developed partially polymerized liposomes composed of polydiacetylene lipids and saturated lipids. Cross-linking of the diacetylene lipids prevents the drug leakage even at 40 deg. C for days. These inactivated drug carriers are non-cytotoxic. Significantly, more than 70% of the encapsulated drug can be instantaneously released by a laser that matches the plasmon resonance of the tethered gold nanoparticles on the liposomes, and the therapeutic effect was observed in cancer cells. The remote activation feature of this novel drug delivery system allows for precise temporal and spatial control of drug release.

Multiple leakage localization and leak size estimation in water networks

NARCIS (Netherlands)

Abbasi, N.; Habibi, H.; Hurkens, C.A.J.; Klabbers, M.D.; Tijsseling, A.S.; Eijndhoven, van S.J.L.

2012-01-01

Water distribution networks experience considerable losses due to leakage, often at multiple locations simultaneously. Leakage detection and localization based on sensor placement and online pressure monitoring could be fast and economical. Using the difference between estimated and measured

Competitiveness and carbon leakages in industry under asymmetric climate policy

International Nuclear Information System (INIS)

Demailly, D.

2008-02-01

This research aims at studying how to predict competitiveness loss for an industry submitted to an asymmetric carbon constraint, and carbon leakages, whether high losses and important leakages might be feared, and which policies can be used to mitigate these losses and escapes. The author analyses and comments the content of four articles dealing with: the impact on competitiveness, revenue distribution and economic efficiency of a change in the allocation rules for EU greenhouse gas allowances; the relationship between allocation of CO 2 allowances and competitiveness in the case of the European iron and steel industry; CO 2 abatement, competitiveness and leakage in the European cement industry under EU ETS; and leakage from climate policies and border tax adjustment (lessons from a geographic model of the cement industry). Then, the author combines several approaches to study the cement and steel industries

Current practice and developmental efforts for leak detection in US reactor primary systems

International Nuclear Information System (INIS)

Kupperman, D.S.; Claytor, T.N.

1985-07-01

Current leak detection practices in 74 operating nuclear reactors have been reviewed. Existing leak detection systems are adequate to ensure a leak-before-break scenario in most situations, but no currently available, single method combines optimal leakage detection sensitivity, leak-locating ability, and leakage measurement accuracy. Simply tightening current leakage limits may produce an unacceptably large number of unnecessary shutdowns. The use of commercially available acoustic monitoring systems or moisture-sensitive tape may improve leak detection capability at specific sites. However, neither of these methods currently provides source discrimination (e.g., to distinguish between leaks from pipe cracks and valves) or leak-rate information (a small leak may saturate the system). A field-implementable acoustic leak detection system is being developed to address these limitations. 5 refs., 3 figs

Current practice and developmental efforts for leak detection in U.S. reactor primary systems

International Nuclear Information System (INIS)

Kupperman, D.S.; Claytor, T.N.

1986-01-01

Current leak detection practices in 74 operating nuclear reactors have been reviewed. Existing leak detection systems are adequate to ensure a leak-before-break scenario in most situations, but no currently available, single method combines optimal leakage detection sensitivity, leak-locating ability, and leakage measurement accuracy. Simply tightening current leakage limits may produce an unacceptably large number of unnecessary shutdowns. The use of commercially available acoustic monitoring systems or moisture-sensitive tape may improve leak detection capability at specific sites. However, neither of these methods currently provides source discrimination (e.g., to distinguish between leaks from pipe cracks and valves) or leak-rate information (a small leak may saturate the system). A field-implementable acoustic leak detection system is being developed to address these limitations. 5 refs.

Factors related to ostomy leakage in the community setting.

Science.gov (United States)

Ratliff, Catherine R

2014-01-01

The purpose of this study was to describe demographic and clinical variables related to ostomy pouch leakage from those discharged from a major medical center during a 2-year period. A convenience sample of 198 persons with an ostomy was obtained using the ICD-9 (International Classification of Diseases, Ninth Revision) codes for colostomy, ileostomy, and ileal conduit for patients who were discharged from the medical center within the time frame of July 2009 to July 2011. One hundred seven participants (55%) returned a completed survey. Respondents included 57 men (53%) and 50 women (47%). The mean age was 60 years with age range from 23 to 91 years. Fecal ostomies made up the majority of the stomas representing 71 patients (66%). A descriptive, cross-sectional research design was used to describe clinical variables related to ostomy pouch leakage for those discharged from a major academic medical center over a 2-year period of time. Participants were mailed an introductory letter from the principal investigator, a self-administered questionnaire, and a prepaid return envelope. Ninety-three patients (87%) reported leakage; however, 48 patients (45%) stated that they did not leak often. A logistic regression was estimated to determine which variables were significant predictors of the dependent variable of leaking status (no/seldom leaking vs more frequent leaking). Two variables were individually significant predictors, sex (P = .021) and 2-piece pouch (P = .015). Women were 4 times more likely to be in the more frequent leaking group than were men. Those who were wearing 2-piece pouches were 78% less likely to be in the more frequent leaking group. Participants with ileostomies or urostomies were more likely to be in the more frequent leaking group and those with peristomal skin irritation were more likely to be in the more frequent leaking group. Findings from this study reveal that women were more likely to experience leakage than men and that wearing a 2-piece

Heat exchanger leakage problem location

Directory of Open Access Journals (Sweden)

Jícha Miroslav

2012-04-01

Full Text Available Recent compact heat exchangers are very often assembled from numerous parts joined together to separate heat transfer fluids and to form the required heat exchanger arrangement. Therefore, the leak tightness is very important property of the compact heat exchangers. Although, the compact heat exchangers have been produced for many years, there are still technological problems associated with manufacturing of the ideal connection between the individual parts, mainly encountered with special purpose heat exchangers, e.g. gas turbine recuperators. This paper describes a procedure used to identify the leakage location inside the prime surface gas turbine recuperator. For this purpose, an analytical model of the leaky gas turbine recuperator was created to assess its performance. The results obtained are compared with the experimental data which were acquired during the recuperator thermal performance analysis. The differences between these two data sets are used to indicate possible leakage areas.

A study on the measurement of effective energy of leakage X-rays

International Nuclear Information System (INIS)

Fijimoto, Nobuhisa; Oogama, Noboru; Nishitani, Motohiro; Yamada, Katsuhiko

1997-01-01

It is important to correct for the energy response of the X-ray detector in measuring X-ray leakage from the protective barrier of the examination room. However, measurement of effective energy of leakage X-rays is very difficult in the clinical setting. In this paper, we discuss a method for estimating the effective energy of both primary and scattered X-rays. This method is based on the measurement of leakage X-ray spectra using a semiconductor-fitted X-ray detector and analyzing the relationship between X-ray tube voltage and effective energy. In this study. we found that the effective energy of leakage X-rays was not dependent on the thickness of shielding materials like concrete and lead. With the concrete barrier, it was possible to express the relation-ship between X-ray tube voltage and the effective energy of leakage X-rays with a simple approximate equation. With the lead-lined barrier, the absorption of the K-edge of lead needs to be considered in estimating the effective energy of leakage X-rays at relatively high tube voltages. (author)

Leakage current conduction mechanisms and electrical properties of atomic-layer-deposited HfO2/Ga2O3 MOS capacitors

Science.gov (United States)

Zhang, Hongpeng; Jia, Renxu; Lei, Yuan; Tang, Xiaoyan; Zhang, Yimen; Zhang, Yuming

2018-02-01

In this paper, current conduction mechanisms in HfO2/β-Ga2O3 metal-oxide-semiconductor (MOS) capacitors under positive and negative biases are investigated using the current-voltage (I-V) measurements conducted at temperatures from 298 K to 378 K. The Schottky emission is dominant under positively biased electric fields of 0.37-2.19 MV cm-1, and the extracted Schottky barrier height ranged from 0.88 eV to 0.91 eV at various temperatures. The Poole-Frenkel emission dominates under negatively biased fields of 1.92-4.83 MV cm-1, and the trap energy levels are from 0.71 eV to 0.77 eV at various temperatures. The conduction band offset (ΔE c) of HfO2/β-Ga2O3 is extracted to be 1.31  ±  0.05 eV via x-ray photoelectron spectroscopy, while a large negative sheet charge density of 1.04  ×  1013 cm-2 is induced at the oxide layer and/or HfO2/β-Ga2O3 interface. A low C-V hysteresis of 0.76 V, low interface state density (D it) close to 1  ×  1012 eV-1 cm-2, and low leakage current density of 2.38  ×  10-5 A cm-2 at a gate voltage of 7 V has been obtained, suggesting the great electrical properties of HfO2/β-Ga2O3 MOSCAP. According to the above analysis, ALD-HfO2 is an attractive candidate for high voltage β-Ga2O3 power devices.

Transanal stent in anterior resection does not prevent anastomotic leakage

DEFF Research Database (Denmark)

Bülow, Steffen; Bulut, O; Christensen, Ib Jarle

2006-01-01

OBJECTIVE: A defunctioning transanal stent may theoretically reduce the leakage rate after anterior rectal resection. We present a randomized open study with the aim of comparing the leakage rate after anterior resection with a loop ileostomy, a transanal stent, both or neither. PATIENTS...... completion of the operation the patients were randomized in two groups with and without a transanal stent. RESULTS: A clinically significant leakage was diagnosed in 25 patients (13%). No significant difference was found 17 of 98 patients with a stent and 8 of 96 without (P = 0.09), or in 9 of 44 ileostomy...... patients with a stent and in 3 of 45 without (P = 0.07). Several leaks over a short time led to an interim analysis after inclusion of 194 of 448 planned patients. The analysis showed no significant protective effect of the stent, and more leakages in the stent group, although not statistically significant...

Air Leakage Rates in Typical Air Barrier Assemblies

Energy Technology Data Exchange (ETDEWEB)

Hun, Diana E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Atchley, Jerald Allen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Childs, Phillip W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-11-01

Estimates for 2010 indicate that infiltration in residential buildings was responsible for 2.85 quads of energy (DOE 2014), which is about 3% of the total energy consumed in the US. One of the mechanisms being implemented to reduce this energy penalty is the use of air barriers as part of the building envelope. These technologies decrease airflow through major leakage sites such as oriented strand board (OSB) joints, and gaps around penetrations (e.g., windows, doors, pipes, electrical outlets) as indicated by Hun et al. (2014). However, most air barrier materials do not properly address leakage spots such as wall-to-roof joints and wall-to-foundation joints because these are difficult to seal, and because air barrier manufacturers usually do not provide adequate instructions for these locations. The present study focuses on characterizing typical air leakage sites in wall assemblies with air barrier materials.

Investigation of defect-induced abnormal body current in fin field-effect-transistors

International Nuclear Information System (INIS)

Liu, Kuan-Ju; Tsai, Jyun-Yu; Lu, Ying-Hsin; Liu, Xi-Wen; Chang, Ting-Chang; Chen, Ching-En; Yang, Ren-Ya; Cheng, Osbert; Huang, Cheng-Tung

2015-01-01

This letter investigates the mechanism of abnormal body current at the linear region in n-channel high-k/metal gate stack fin field effect transistors. Unlike body current, which is generated by impact ionization at high drain voltages, abnormal body current was found to increase with decreasing drain voltages. Notably, the unusual body leakage only occurs in three-dimensional structure devices. Based on measurements under different operation conditions, the abnormal body current can be attributed to fin surface defect-induced leakage current, and the mechanism is electron tunneling to the fin via the defects, resulting in holes left at the body terminal

Leakage Inductance Calculation for Planar Transformers with a Magnetic Shunt

DEFF Research Database (Denmark)

Jun, Zhang; Ouyang, Ziwei; Duffy, M. C.

2013-01-01

The magnetic shunt is generally inserted in a planar transformer to increase the leakage inductance which can be utilized as the series inductor in resonant circuits such as the LLC resonant converter. This paper presents a calculation methodology for the leakage inductance of the transformer...

Current leakage for low altitude satellites: modeling applications

International Nuclear Information System (INIS)

Konradi, A.; Mccoy, J.E.; Garriott, O.K.

1979-01-01

To simulate the behavior of a high voltage solar cell array in the ionospheric plasma environment, the large (90 ft x 55 ft diameter) vacuum chamber was used to measure the high-voltage plasma interactions of a 3 ft x 30 ft conductive panel. The chamber was filled with nitrogen and argon plasma at electron densities of up to 1,000,000 per cu cm. Measurements of current flow to the plasma were made in three configurations: (a) with one end of the panel grounded, (b) with the whole panel floating while a high bias was applied between the ends of the panel, and (c) with the whole panel at high negative voltage with respect to the chamber walls. The results indicate that a simple model with a constant panel conductivity and plasma resistance can adequately describe the voltage distribution along the panel and the plasma current flow. As expected, when a high potential difference is applied to the panel ends more than 95% of the panel floats negative with respect to the plasma

A new approach for simple radioisotope cisternography examination in cerebrospinal fluid leakage detection.

Science.gov (United States)

Hoshino, Hiromitsu; Higuchi, Tetsuya; Achmad, Arifudin; Taketomi-Takahashi, Ayako; Fujimaki, Hiroya; Tsushima, Yoshito

2016-01-01

We developed a new quantitative interpretation technique of radioisotope cisternography (RIC) for the diagnosis of spontaneous cerebrospinal fluid hypovolemia (SCH). RIC studies performed for suspected SCH were evaluated. (111)In-DTPA RIC images were taken at 0, 1, 3, 6, and 24-h after radioisotope injection following the current protocol. Regions of interest (ROI) were selected on 3-h images to include brain, spine, bladder or the whole body. The accumulative radioactivity counts were calculated for quantitative analysis. Final diagnoses of SCH were established based on the diagnostic criteria recently proposed by Schievink and colleagues. Thirty-five patients were focused on. Twenty-one (60.0%) patients were diagnosed as having SCH according to the Schievink criteria. On the 3-h images, direct cerebrospinal fluid leakage sign was detected in nine of 21 SCH patients (42.9%), as well as three patients with suspected iatrogenic leakage. Compared to non-SCH patients, SCH patients showed higher bladder accumulation at 3-h images (P = 0.0002), and higher brain clearance between the 6- and 24-h images (P leakage was not observed. 1- and 6-h images did not provide any additional information in any patients. A new simple ROI setting method, in which only the 3-h whole body and 24-h brain images were necessary, was sufficient to diagnose SCH.

Signal-based Gas Leakage Detection for Fluid Power Accumulators in Wind Turbines

DEFF Research Database (Denmark)

Liniger, Jesper; Sepehri, Nariman; N. Soltani, Mohsen

2017-01-01

This paper describes the development and application of a signal-based fault detection method for identifying gas leakage in hydraulic accumulators used in wind turbines. The method uses Multiresolution Signal Decomposition (MSD) based on wavelets for feature extraction from a~single fluid pressure...... measurement located close to the accumulator. Gas leakage is shown to create increased variations in this pressure signal. The Root Mean Square (RMS) of the detail coefficient Level 9 from the MSD is found as the most sensitive and robust fault indicator of gas leakage. The method is verified...... on an experimental setup allowing for the replication of the conditions for accumulators in wind turbines. Robustness is tested in a multi-fault environment where gas and external fluid leakage occurs simultaneously. In total, 24 experiments are performed, which show that the method is sensitive to gas leakage...

Feasibility of Locating Leakages in Sewage Pressure Pipes Using the Distributed Temperature Sensing Technology.

Science.gov (United States)

Apperl, Benjamin; Pressl, Alexander; Schulz, Karsten

2017-01-01

The cost effective maintenance of underwater pressure pipes for sewage disposal in Austria requires the detection and localization of leakages. Extrusion of wastewater in lakes can heavily influence the water and bathing quality of surrounding waters. The Distributed Temperature Sensing (DTS) technology is a widely used technique for oil and gas pipeline leakage detection. While in pipeline leakage detection, fiber optic cables are installed permanently at the outside or within the protective sheathing of the pipe; this paper aims at testing the feasibility of detecting leakages with temporary introduced fiber optic cable inside the pipe. The detection and localization were tested in a laboratory experiment. The intrusion of water from leakages into the pipe, producing a local temperature drop, served as indicator for leakages. Measurements were taken under varying measurement conditions, including the number of leakages as well as the positioning of the fiber optic cable. Experiments showed that leakages could be detected accurately with the proposed methodology, when measuring resolution, temperature gradient and measurement time were properly selected. Despite the successful application of DTS for leakage detection in this lab environment, challenges in real system applications may arise from temperature gradients within the pipe system over longer distances and the placement of the cable into the real pipe system.

Hyperpolarization-activated inward leakage currents caused by deletion or mutation of carboxy-terminal tyrosines of the Na+/K+-ATPase {alpha} subunit.

Science.gov (United States)

Meier, Susan; Tavraz, Neslihan N; Dürr, Katharina L; Friedrich, Thomas

2010-02-01

The Na(+)/K(+)-ATPase mediates electrogenic transport by exporting three Na(+) ions in exchange for two K(+) ions across the cell membrane per adenosine triphosphate molecule. The location of two Rb(+) ions in the crystal structures of the Na(+)/K(+)-ATPase has defined two "common" cation binding sites, I and II, which accommodate Na(+) or K(+) ions during transport. The configuration of site III is still unknown, but the crystal structure has suggested a critical role of the carboxy-terminal KETYY motif for the formation of this "unique" Na(+) binding site. Our two-electrode voltage clamp experiments on Xenopus oocytes show that deletion of two tyrosines at the carboxy terminus of the human Na(+)/K(+)-ATPase alpha(2) subunit decreases the affinity for extracellular and intracellular Na(+), in agreement with previous biochemical studies. Apparently, the DeltaYY deletion changes Na(+) affinity at site III but leaves the common sites unaffected, whereas the more extensive DeltaKETYY deletion affects the unique site and the common sites as well. In the absence of extracellular K(+), the DeltaYY construct mediated ouabain-sensitive, hyperpolarization-activated inward currents, which were Na(+) dependent and increased with acidification. Furthermore, the voltage dependence of rate constants from transient currents under Na(+)/Na(+) exchange conditions was reversed, and the amounts of charge transported upon voltage pulses from a certain holding potential to hyperpolarizing potentials and back were unequal. These findings are incompatible with a reversible and exclusively extracellular Na(+) release/binding mechanism. In analogy to the mechanism proposed for the H(+) leak currents of the wild-type Na(+)/K(+)-ATPase, we suggest that the DeltaYY deletion lowers the energy barrier for the intracellular Na(+) occlusion reaction, thus destabilizing the Na(+)-occluded state and enabling inward leak currents. The leakage currents are prevented by aromatic amino acids at the

A severity-based quantification of data leakages in database systems

NARCIS (Netherlands)

Vavilis, S.; Petkovic, M.; Zannone, N.

2016-01-01

The detection and handling of data leakages is becoming a critical issue for organizations. To this end, data leakage solutions are usually employed by organizations to monitor network traffic and the use of portable storage devices. However, these solutions often produce a large number of alerts,

Cement Leakage in Percutaneous Vertebral Augmentation for Osteoporotic Vertebral Compression Fractures: Analysis of Risk Factors.

Science.gov (United States)

Xie, Weixing; Jin, Daxiang; Ma, Hui; Ding, Jinyong; Xu, Jixi; Zhang, Shuncong; Liang, De

2016-05-01

The risk factors for cement leakage were retrospectively reviewed in 192 patients who underwent percutaneous vertebral augmentation (PVA). To discuss the factors related to the cement leakage in PVA procedure for the treatment of osteoporotic vertebral compression fractures. PVA is widely applied for the treatment of osteoporotic vertebral fractures. Cement leakage is a major complication of this procedure. The risk factors for cement leakage were controversial. A retrospective review of 192 patients who underwent PVA was conducted. The following data were recorded: age, sex, bone density, number of fractured vertebrae before surgery, number of treated vertebrae, severity of the treated vertebrae, operative approach, volume of injected bone cement, preoperative vertebral compression ratio, preoperative local kyphosis angle, intraosseous clefts, preoperative vertebral cortical bone defect, and ratio and type of cement leakage. To study the correlation between each factor and cement leakage ratio, bivariate regression analysis was employed to perform univariate analysis, whereas multivariate linear regression analysis was employed to perform multivariate analysis. The study included 192 patients (282 treated vertebrae), and cement leakage occurred in 100 vertebrae (35.46%). The vertebrae with preoperative cortical bone defects generally exhibited higher cement leakage ratio, and the leakage is typically type C. Vertebrae with intact cortical bones before the procedure tend to experience type S leakage. Univariate analysis showed that patient age, bone density, number of fractured vertebrae before surgery, and vertebral cortical bone were associated with cement leakage ratio (Pcement leakage are bone density and vertebral cortical bone defect, with standardized partial regression coefficients of -0.085 and 0.144, respectively. High bone density and vertebral cortical bone defect are independent risk factors associated with bone cement leakage.

A non-uniform three-gap buncher cavity with suppression of transverse-electromagnetic mode leakage in the triaxial klystron amplifier

Energy Technology Data Exchange (ETDEWEB)

Qi, Zumin; Zhang, Jun, E-mail: zhangjun-nudt@126.com; Zhong, Huihuang; Zhu, Danni; Qiu, Yongfeng [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China)

2014-01-15

The triaxial klystron amplifier is an efficient high power relativistic klystron amplifier operating at high frequencies due to its coaxial structure with large radius. However, the coaxial structures result in coupling problems among the cavities as the TEM mode is not cut-off in the coaxial tube. Therefore, the suppression of the TEM mode leakage, especially the leakage from the buncher cavity to the input cavity, is crucial in the design of a triaxial klystron amplifier. In this paper, a non-uniform three-gap buncher cavity is proposed to suppress the TEM mode leakage. The cold cavity analysis shows that the non-uniform three-gap buncher cavity can significantly suppress the TEM mode generation compared to a uniform three-gap buncher cavity. Particle-in-cell simulation shows that the power leakage to the input cavity is less than 1.5‰ of the negative power in the buncher cavity and the buncher cavity can efficiently modulate an intense relativistic electron beam free of self-oscillations. A fundamental current modulation depth of 117% is achieved by employing the proposed non-uniform buncher cavity into an X-band triaxial amplifier, which results in the high efficiency generation of high power microwave.

Leakage detection in underground gas mains with radioaktive argon

International Nuclear Information System (INIS)

Schmitz, J.

1975-01-01

In the field of gas supply, radionuclide techniques are suitable for the routine monitoring of transport mains by means of highly active tracer clouds and a measuring scraper as well as for exact leakage detection in local gas distribution systems. Very good results are obtained in the case of mains lying lower than 1.5 m if the length and alignment of the pipe section allow a towing probe to be pulled through. This was investigated systematically on a model stretch under practical conditions. The attempts to detect leakages were made with the aid of the radioactive isotope 41 Ar. Under conditions close to practice concerning pipe bedding, branching, pre-pressure, and leakage diameter, a leak with leakage rates as small as approx. 1 l/min could be measured with the aid of a towing probe with a precision of +-0.5 m. This accuracy is another advantage of this method. Branching and fittings with a big dead volume do not interfere with the evaluation. The investment for this method can be compared to other physical/technical investigations on mains, e.g. weld seam tests. (orig./LN) [de

Design of modified annulus air sampling system for the detection of leakage in waste transfer line

International Nuclear Information System (INIS)

Deokar, U.V; Khot, A.R.; Mathew, P.; Ganesh, G.; Tripathi, R.M.; Srivastava, Srishti

2018-01-01

Various liquid waste streams are generated during the operation of reprocessing plant. The High Level (HL), Intermediate Level (IL) and Low Level (LL) liquid wastes generated, are transferred from reprocessing plant to Waste Management Facility. These respective waste streams are transferred through pipe-in-pipe lines along the shielded concrete trench. For detection of radioactive leakage from primary waste transfer line into secondary line, sampling of the annulus air between the two pipes is carried out. The currently installed pressurized annulus air sampling system did not have online leakage detection provision. Hence, there are chances of personal exposure and airborne activity in the working area. To overcome these design flaws, free air flow modified online annulus air sampling system with more safety features is designed

Impact of leakage delay on bifurcation in high-order fractional BAM neural networks.

Science.gov (United States)

Huang, Chengdai; Cao, Jinde

2018-02-01

The effects of leakage delay on the dynamics of neural networks with integer-order have lately been received considerable attention. It has been confirmed that fractional neural networks more appropriately uncover the dynamical properties of neural networks, but the results of fractional neural networks with leakage delay are relatively few. This paper primarily concentrates on the issue of bifurcation for high-order fractional bidirectional associative memory(BAM) neural networks involving leakage delay. The first attempt is made to tackle the stability and bifurcation of high-order fractional BAM neural networks with time delay in leakage terms in this paper. The conditions for the appearance of bifurcation for the proposed systems with leakage delay are firstly established by adopting time delay as a bifurcation parameter. Then, the bifurcation criteria of such system without leakage delay are successfully acquired. Comparative analysis wondrously detects that the stability performance of the proposed high-order fractional neural networks is critically weakened by leakage delay, they cannot be overlooked. Numerical examples are ultimately exhibited to attest the efficiency of the theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

Understanding and Mitigating Tip Leakage and Endwall Losses in High Pressure Ratio Cores

Science.gov (United States)

Christophel, Jesse

2015-01-01

Reducing endwall and tip secondary flow losses will be a key enabler for the next generation of commercial and military air transport and will be an improvement on the state-of-the-art in turbine loss reduction strategies. The objective of this research is three-fold: 1) To improve understanding of endwall secondary flow and tip clearance losses 2) To develop novel technologies to mitigate these losses and test them in low-speed cascade and rig environments 3) To validate predictive tools To accomplish these objectives, Pratt & Whitney (P&W) has teamed with Pennsylvania State University (PSU) to experimentally test new features designed by P&W. P&W will create new rim-cavity features to reduce secondary flow loss and improve purge flow cooling effectiveness and new blade tip features to manage leakage flows and reduce tip leakage secondary flow loss. P&W is currently developing technologies in these two areas that expect to be assimilated in the N+2/N+3 generation of commercial engines.

Advanced Detection Technology of Trace-level Borate for SG Leakage Monitoring

Energy Technology Data Exchange (ETDEWEB)

Lee, Seban; Kang, Dukwon; Kim, Seungil; Kim, Hyunki; Heo, Jun; Sung, Jinhyun [Radiation Eng. Center, Shihung (Korea, Republic of); Lee, Dongbum [Academic Support Dept., Seoul (Korea, Republic of)

2013-05-15

Many studies have been reported for monitoring technology of steam generator, however, all of these methods have their own limitations. The leakage monitoring technology of steam generator of PWR has also got a limit due to the adoption of specific radionuclides (N-16, Ar-41, H-3, Xe, etc.) generated by nuclear fission, which are available only when reactor output is 20% or more. Most of domestic NPPs apply the N-16 technique for monitoring tube leakage but it has some problem that it is difficult to calculate the leakage rate because neutron flux are not completely formed during low power operation. For example, tube leakage of steam generator occurred in the Uljin nuclear power plant in 2002 during coast down operation for periodic plant maintenance. This plant could not prevent a rupture accident in advance because N-16 method is not possible the leak monitoring less than 20% reactor power. The development of excellent alternative monitoring technology that can monitor the real-time leakage is required under a variety of operating conditions like start-up and abnormal conditions of NPPs. This study was performed to lay a foundation in monitoring the leakage of steam generator coping with the lower output and low power operational condition using trace level of boron which is non-radioactive nuclide to inject control neutron injection. In this study, non-radioactive nuclide boron ion, which existed in the secondary system water, as leakage monitoring indicator was investigated for the separation of complex cation and anion phase. Borate was detected by using borate concentrator column coupled with the ion-exclusion column analytical column, revealing the problem of overlapped peak between fluoride and boron ions. Meanwhile, ion-exchange column could confirm the possibility as a leakage monitoring indicator of steam generator, despite the peak of glycolic acid salts was slightly overlapped. It will be needed for further research regarding the selectivity of the

Advanced Detection Technology of Trace-level Borate for SG Leakage Monitoring

International Nuclear Information System (INIS)

Lee, Seban; Kang, Dukwon; Kim, Seungil; Kim, Hyunki; Heo, Jun; Sung, Jinhyun; Lee, Dongbum

2013-01-01

Many studies have been reported for monitoring technology of steam generator, however, all of these methods have their own limitations. The leakage monitoring technology of steam generator of PWR has also got a limit due to the adoption of specific radionuclides (N-16, Ar-41, H-3, Xe, etc.) generated by nuclear fission, which are available only when reactor output is 20% or more. Most of domestic NPPs apply the N-16 technique for monitoring tube leakage but it has some problem that it is difficult to calculate the leakage rate because neutron flux are not completely formed during low power operation. For example, tube leakage of steam generator occurred in the Uljin nuclear power plant in 2002 during coast down operation for periodic plant maintenance. This plant could not prevent a rupture accident in advance because N-16 method is not possible the leak monitoring less than 20% reactor power. The development of excellent alternative monitoring technology that can monitor the real-time leakage is required under a variety of operating conditions like start-up and abnormal conditions of NPPs. This study was performed to lay a foundation in monitoring the leakage of steam generator coping with the lower output and low power operational condition using trace level of boron which is non-radioactive nuclide to inject control neutron injection. In this study, non-radioactive nuclide boron ion, which existed in the secondary system water, as leakage monitoring indicator was investigated for the separation of complex cation and anion phase. Borate was detected by using borate concentrator column coupled with the ion-exclusion column analytical column, revealing the problem of overlapped peak between fluoride and boron ions. Meanwhile, ion-exchange column could confirm the possibility as a leakage monitoring indicator of steam generator, despite the peak of glycolic acid salts was slightly overlapped. It will be needed for further research regarding the selectivity of the

The Impact of Gas Turbine Component Leakage Fault on GPA Performance Diagnostics

Directory of Open Access Journals (Sweden)

E. L. Ntantis

2016-01-01

Full Text Available The leakage analysis is a key factor in determining energy loss from a gas turbine. Once the components assembly fails, air leakage through the opening increases resulting in a performance loss. Therefore, the performance efficiency of the engine cannot be reliably determined, without good estimates and analysis of leakage faults. Consequently, the implementation of a leakage fault within a gas turbine engine model is necessary for any performance diagnostic technique that can expand its diagnostics capabilities for more accurate predictions. This paper explores the impact of gas turbine component leakage fault on GPA (Gas Path Analysis Performance Diagnostics. The analysis is demonstrated with a test case where gas turbine performance simulation and diagnostics code TURBOMATCH is used to build a performance model of a model engine similar to Rolls-Royce Trent 500 turbofan engine, and carry out the diagnostic analysis with the presence of different component fault cases. Conclusively, to improve the reliability of the diagnostic results, a leakage fault analysis of the implemented faults is made. The diagnostic tool used to deal with the analysis of the gas turbine component implemented faults is a model-based method utilizing a non-linear GPA.

Injection Technique and Pen Needle Design Affect Leakage From Skin After Subcutaneous Injections

DEFF Research Database (Denmark)

Præstmark, Kezia Ann; Stallknecht, Bente; Jensen, Morten Lind

2016-01-01

BACKGROUND: After a subcutaneous injection fluid might leak out of the skin, commonly referred to as leakage or backflow. The objective was to examine the influence of needle design and injection technique on leakage after injections in the subcutaneous tissue of humans and pigs. METHOD: Leakage ...

Modeling the leakage of LCD displays with local backlight for quality assessment

DEFF Research Database (Denmark)

Mantel, Claire; Korhonen, Jari; Pedersen, Jesper M.

2014-01-01

The recent technique of local backlight dimming has a significant impact on the quality of images displayed with a LCD screen with LED local dimming. Therefore it represents a necessary step in the quality assessment chain, independently from the other processes applied to images. This paper...... investigates the modeling of one of the major spatial artifacts produced by local dimming: leakage. Leakage appears in dark areas when the backlight level is too high for LC cells to block sufficiently and the final displayed brightness is higher than it should. A subjective quality experiment was run...... on videos displayed on LCD TV with local backlight dimming viewed from a 0° and 15° angles. The subjective results are then compared objective data using different leakage models: constant over the whole display or horizontally varying and three leakage factor (no leakage, measured at 0° and 15...

On the scaling of gas leakage from static seals

International Nuclear Information System (INIS)

Chivers, T.C.; Hunt, R.P.

1977-01-01

The interaction between gas leakage from static seals and eight potential variables is discussed. From a consideration of the interaction of these various parameters and the mechanical design of the seal system the importance of correctly interpreting leakage data is demonstrated. Given a situation where model experiments are necessary, this document forms a basis for the definition and interpretation of a test programme. (author)

The Effect of Internal Leakages on Thermal Performance in NPPs

International Nuclear Information System (INIS)

Heo, Gyun Young; Kim, Doo Won; Jang, Seok Bo

2007-01-01

Since the Balance Of Plant (BOP, limited to a turbine cycle in this study) does not contain radioactive material, regulatory authorities did not need to have concerns on it. As the interests on safety and performance is getting more serious and extensive, controlling the level of safety and performance of a BOP have just begun or is about to begin. The performance standards or ageing management programs of the major equipment in a BOP is being developed. The regulatory requirements for tests and/or maintenance are being actively built up. There is also a probabilistic approach quantifying performance of a BOP. The study on quantifying the rate of unanticipated shutdowns caused by careless maintenance and/or tests conducted in a BOP is going on. In this study, the modeling of the entire BOP and the methodologies of thermal performance analysis should be one of the must-have items as well. This study was achieved to ensure fundamental skills related to 1) the detailed steady-state modeling of a BOP and 2) thermal performance analysis under various conditions. Particularly, the paper will focus on the effect of internal leakages inside the valves and FeedWater Heaters (FWHs). The internal leakage is regarded as the flow movement through the isolated path but remaining inside the system boundary of a BOP. For instance, the leakage from one side of a valve seat to the other side, or the leakage through the cracked tubes or tube-sheets in a heat exchanger correspond to internal leakages. We made a BOP model of OPR1000 and investigated thermal performance under the internal leakage in Turbine Bypass Condenser Dump Valves (TBCDV) and FWHs

The Leakage determination on corrosion fretting machine

International Nuclear Information System (INIS)

Sriyono; Satmoko, Ari; Hafid, Abdul; Febrianto; Prasetio, Joko; Abtokhi; Sumarno, Edy; Handoyo, Ismu; Hidayati, Nur Rahmah; Histori

1998-01-01

Fretting machine is an experimental loop to learn fretting corrosion phenomena wich is caused by loading and vibration. On the steam generator, one of the corrosion process that's occurred, it can be caused by vibration between tubes and bending material. Because of high flow rate inside the tube, the high frequency vibration will appeared so it can make the corrosion on bending material more faster. This process can be simulate by fretting machine. This machine has already damage because of leakage. So it will be repaired by dismantling, radiography testing and redrawing. from the result of radiography, the leakage is caused by cracking on bellows seals of the dynamic main support

ERROR REDUCTION IN DUCT LEAKAGE TESTING THROUGH DATA CROSS-CHECKS

Energy Technology Data Exchange (ETDEWEB)

ANDREWS, J.W.

1998-12-31

One way to reduce uncertainty in scientific measurement is to devise a protocol in which more quantities are measured than are absolutely required, so that the result is over constrained. This report develops a method for so combining data from two different tests for air leakage in residential duct systems. An algorithm, which depends on the uncertainty estimates for the measured quantities, optimizes the use of the excess data. In many cases it can significantly reduce the error bar on at least one of the two measured duct leakage rates (supply or return), and it provides a rational method of reconciling any conflicting results from the two leakage tests.

Pulse sequences for suppressing leakage in single-qubit gate operations

Science.gov (United States)

Ghosh, Joydip; Coppersmith, S. N.; Friesen, Mark

2017-06-01

Many realizations of solid-state qubits involve couplings to leakage states lying outside the computational subspace, posing a threat to high-fidelity quantum gate operations. Mitigating leakage errors is especially challenging when the coupling strength is unknown, e.g., when it is caused by noise. Here we show that simple pulse sequences can be used to strongly suppress leakage errors for a qubit embedded in a three-level system. As an example, we apply our scheme to the recently proposed charge quadrupole (CQ) qubit for quantum dots. These results provide a solution to a key challenge for fault-tolerant quantum computing with solid-state elements.

A Novel Leakage-tolerant Domino Logic Circuit With Feedback From Footer Transistor In Ultra Deep Submicron CMOS

DEFF Research Database (Denmark)

Moradi, Farshad; Peiravi, Ali; Mahmoodi, Hamid

As the CMOS manufacturing process scales down into the ultra deep sub-micron regime, the leakage current becomes an increasingly more important consideration in VLSI circuit design. In this paper, a high speed and noise immune domino logic circuit is presented which uses the property of the footer...

A white-box anomaly-based framework for database leakage detection

NARCIS (Netherlands)

Costante, E.; den Hartog, J.; Petkovic, M.; Etalle, S.; Pechenizkiy, M.

2017-01-01

Data leakage is at the heart most of the privacy breaches worldwide. In this paper we present a white-box approach to detect potential data leakage by spotting anomalies in database transactions. We refer to our solution as white-box because it builds self explanatory profiles that are easy to

A retrospective analysis of endoscopic treatment outcomes in patients with postoperative bile leakage.

Science.gov (United States)

Sayar, Suleyman; Olmez, Sehmus; Avcioglu, Ufuk; Tenlik, Ilyas; Saritas, Bunyamin; Ozdil, Kamil; Altiparmak, Emin; Ozaslan, Ersan

2016-01-01

Bile leakage, while rare, can be a complication seen after cholecystectomy. It may also occur after hepatic or biliary surgical procedures. Etiology may be underlying pathology or surgical complication. Endoscopic retrograde cholangiopancreatography (ERCP) can play major role in diagnosis and treatment of bile leakage. Present study was a retrospective analysis of outcomes of ERCP procedure in patients with bile leakage. Patients who underwent ERCP for bile leakage after surgery between 2008 and 2012 were included in the study. Etiology, clinical and radiological characteristics, and endoscopic treatment outcomes were recorded and analyzed. Total of 31 patients (10 male, 21 female) were included in the study. ERCP was performed for bile leakage after cholecystectomy in 20 patients, after hydatid cyst operation in 10 patients, and after hepatic resection in 1 patient. Clinical signs and symptoms of bile leakage included abdominal pain, bile drainage from percutaneous drain, peritonitis, jaundice, and bilioma. Twelve (60%) patients were treated with endoscopic sphincterotomy (ES) and nasobiliary drainage (NBD) catheter, 7 patients (35%) were treated with ES and biliary stent (BS), and 1 patient (5%) was treated with ES alone. Treatment efficiency was 100% in bile leakage cases after cholecystectomy. Ten (32%) cases of hydatid cyst surgery had subsequent cystobiliary fistula. Of these patients, 7 were treated with ES and NBD, 2 were treated with ES and BS, and 1 patient (8%) with ES alone. Treatment was successful in 90% of these cases. ERCP is an effective method to diagnose and treat bile leakage. Endoscopic treatment of postoperative bile leakage should be individualized based on etiological and other factors, such as accompanying fistula.

Measurement strategy of the water leakage into a low pressure sodium boundary for a liquid metal reactor

International Nuclear Information System (INIS)

Hur, S.; Kim, D.H.; Seong, S.H.; Kim, S.O.

2004-01-01

This paper deals with the measurement strategy of a water leakage into sodium boundary for a liquid metal reactor. There are several methods including the chemical sensing method, pressure sensing methods, and non-destructive method including the acoustic monitoring technique to measure the leakage. As for the results of the analysis with respect to the event propagation characteristics, it has been recommended that the acoustic method has a capability to detect small and intermediate leaks within required response time of 10 seconds. A leak of one gram/sec could be currently detected within the required response time of 10 seconds with a high reliability. In the case of less than a one gram/sec leakage, the response time could not meet our requirements due to a complicated signal processing logic. Thus, the system configuration for a fast processing of a leak detection has been recommended. It is expected that this configuration of the leak detection system could reduce the response time due to the distributed and parallel processing scheme. (orig.)

Leakage monitoring and maintenance for main heat-exchanger of project 871

International Nuclear Information System (INIS)

Li Yanshui; Cao Zhibin

1995-01-01

Main heat-exchanger is one of the most important equipment. To prevent the occurrence of leakage accident, desalting and water treatment for secondary cooling water is conducted chemical except controlling the water quality of coolant. There is a small loop for leakage monitoring to find out the leakage immediately. In order to ensure the safety of operation, the treatment of eliminating water dirt and inspection for outside and inside must be done periodically, and the relevant means must be adopted if any abnormal phenomenon is found

Suppression and control of leakage field in electromagnetic helical microwiggler

Energy Technology Data Exchange (ETDEWEB)

Ohigashi, N. [Kansai Univ., Osaka (Japan); Tsunawaki, Y. [Osaka Sangyo Univ. (Japan); Imasaki, K. [Institute for Laser Technology, Osaka (Japan)] [and others

1995-12-31

Shortening the period of electromagnetic wiggler introduces both the radical increase of the leakage field and the decrease of the field in the gap region. The leakage field is severer problem in planar electromagnetic wiggler than in helical wiggler. Hence, in order to develop a short period electromagnetic wiggler, we have adopted {open_quotes}three poles per period{close_quotes} type electromagnetic helical microwiggler. In this work, we inserted the permanent magnet (PM) blocks with specific magnetized directions in the space between magnetic poles, for suppressing the leakage field flowing out from a pole face to the neighboring pole face. These PM-blocks must have higher intrinsic coersive force than saturation field of pole material. The gap field due to each pole is adjustable by controlling the leakage fields, that is, controlling the position of each iron screw set in each retainer fixing the PM-blocks. At present time, a test wiggler with period 7.8mm, periodical number 10 and gap length 4.6mm has been manufactured. Because the ratio of PM-block aperture to gap length is important parameter to suppress the leakage field, the parameter has been surveyed experimentally for PM-blocks with several dimensions of aperture. The field strength of 3-5kG (K=0.2-0.4) would be expected in the wiggler.

Report on the water leakage from instrumentation pipe in JMTR

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-03-01

On December 10, 2002, the leakage was found at the pressure instrumentation pipe attached to the exit pipe of No.1 charging pump of the purification system of a primary cooling system at JMTR in the Oarai Research establishment, JAERI. The Investigation Committee for Water Leakage from Instrumentation Pipe in JMTR was established and organized by specialists from inside and outside JAERI on December 16 and its meeting was held in public 3 times by 6th January, 2003. They found out the cause and countermeasures of cracks, and also investigated enhancement of safety management. As the result, it was considered that the leakage started around the 6th of December 2002 and the cause of the cracks was due to fatigue by vibration of the charging pump during operation. The committee discovered following incorrect actions in the safety management. First, operation of JMTR was continued without keeping careful watch in spite of occurrence of leakage detector alarm. Second, every time when the alarm range for the reasons other than the leakage, appropriate investigation and countermeasure were not taken. Third, the manager in charge didn't have a fair understanding of the situation and didn't give an appropriate direction. This is the report on the cause and countermeasures of cracks and enhancement of safety management. (author)

Percutaneous Management of Postoperative Duodenal Stump Leakage with Foley Catheter

International Nuclear Information System (INIS)

Oh, Jung Suk; Lee, Hae Giu; Chun, Ho Jong; Choi, Byung Gil; Lee, Sang Hoon; Hahn, Seong Tai; Ohm, Joon Young

2013-01-01

Purpose: This study was designed to evaluate retrospectively the safety and efficacy of the percutaneous management of duodenal stump leakage with a Foley catheter after subtotal gastrectomy. Methods: Ten consecutive patients (M:F = 9:1, median age: 64 years) were included in this retrospective study. The duodenal stump leakages were diagnosed in all the patients within a median of 10 days (range, 6–20). At first, the patients underwent percutaneous drainage on the day of or the day after confirmation of the presence of duodenal stump leakage, and then the Foley catheters were replaced at a median of 9 days (range, 6–38) after the percutaneous drainage. Results: Foley catheters were placed successfully in the duodenal lumen of all the patients under a fluoroscopic guide. No complication was observed during and after the procedures in all the patients. All of the patients started a regular diet 1 day after the Foley catheter placement. The patients were discharged at a median of 7 days (range, 5–14) after the Foley catheter placement. The catheters were removed in an outpatient clinic 10–58 days (median, 28) after the Foley catheter placement. Conclusions: Fluoroscopy-guided percutaneous Foley catheter placement may be a safe and effective treatment option for postoperative duodenal stump leakage and may allow for shorter hospital stays, earlier oral intake, and more effective control of leakage sites

AN ADVANCED LEAKAGE SCHEME FOR NEUTRINO TREATMENT IN ASTROPHYSICAL SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Perego, A. [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 2, D-64289 Darmstadt (Germany); Cabezón, R. M. [Physics Department, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Käppeli, R., E-mail: albino.perego@physik.tu-darmstadt.de [Seminar for Applied Mathematics, ETH Zürich, Rämistrasse 101, 8092 Zürich (Switzerland)

2016-04-15

We present an Advanced Spectral Leakage (ASL) scheme to model neutrinos in the context of core-collapse supernovae (CCSNe) and compact binary mergers. Based on previous gray leakage schemes, the ASL scheme computes the neutrino cooling rates by interpolating local production and diffusion rates (relevant in optically thin and thick regimes, respectively) separately for discretized values of the neutrino energy. Neutrino trapped components are also modeled, based on equilibrium and timescale arguments. The better accuracy achieved by the spectral treatment allows a more reliable computation of neutrino heating rates in optically thin conditions. The scheme has been calibrated and tested against Boltzmann transport in the context of Newtonian spherically symmetric models of CCSNe. ASL shows a very good qualitative and a partial quantitative agreement for key quantities from collapse to a few hundreds of milliseconds after core bounce. We have proved the adaptability and flexibility of our ASL scheme, coupling it to an axisymmetric Eulerian and to a three-dimensional smoothed particle hydrodynamics code to simulate core collapse. Therefore, the neutrino treatment presented here is ideal for large parameter-space explorations, parametric studies, high-resolution tests, code developments, and long-term modeling of asymmetric configurations, where more detailed neutrino treatments are not available or are currently computationally too expensive.

Microvascular dysfunction with increased vascular leakage response in mice systemically exposed to arsenic.

Science.gov (United States)

Chen, Shih-Chieh; Huang, Shin-Yin; Lu, Chi-Yu; Hsu, Ya-Hung; Wang, Dean-Chuan

2014-09-01

The mechanisms underlying cardiovascular disease induced by arsenic exposure are not completely understood. The objectives of this study were to investigate whether arsenic-fed mice have an increased vascular leakage response to vasoactive agents and whether enhanced type-2 protein phosphatase (PP2A) activity is involved in mustard oil-induced leakage. ICR mice were fed water or sodium arsenite (20 mg/kg) for 4 or 8 weeks. The leakage response to vasoactive agents was quantified using the Evans blue (EB) technique or vascular labeling with carbon particles. Increased EB leakage and high density of carbon-labeled microvessels were detected in arsenic-fed mice treated with mustard oil. Histamine induced significantly higher vascular leakage in arsenic-fed mice than in water-fed mice. Pretreatment with the PP2A inhibitor okadaic acid or the neurokinin 1 receptor (NK1R) blocker RP67580 significantly reduced mustard oil-induced vascular leakage in arsenic-fed mice. The protein levels of PP2Ac and NK1R were similar in both groups. PP2A activity was significantly higher in the arsenic-fed mice compared with the control group. These findings indicate that microvessels generally respond to vasoactive agents, and that the increased PP2A activity is involved in mustard oil-induced vascular leakage in arsenic-fed mice. Arsenic may initiate endothelial dysfunction, resulting in vascular leakage in response to vasoactive agents.

Short-term effects of CO2 leakage on the soil bacterial community in a simulated gas leakage scenario

Directory of Open Access Journals (Sweden)

Jing Ma

2017-11-01

Full Text Available The technology of carbon dioxide (CO2 capture and storage (CCS has provided a new option for mitigating global anthropogenic emissions with unique advantages. However, the potential risk of gas leakage from CO2 sequestration and utilization processes has attracted considerable attention. Moreover, leakage might threaten soil ecosystems and thus cannot be ignored. In this study, a simulation experiment of leakage from CO2 geological storage was designed to investigate the short-term effects of different CO2 leakage concentration (from 400 g m−2 day−1 to 2,000 g m−2 day−1 on soil bacterial communities. A shunt device and adjustable flow meter were used to control the amount of CO2 injected into the soil. Comparisons were made between soil physicochemical properties, soil enzyme activities, and microbial community diversity before and after injecting different CO2 concentrations. Increasing CO2 concentration decreased the soil pH, and the largest variation ranged from 8.15 to 7.29 (p < 0.05. Nitrate nitrogen content varied from 1.01 to 4.03 mg/Kg, while Olsen-phosphorus and total phosphorus demonstrated less regular downtrends. The fluorescein diacetate (FDA hydrolytic enzyme activity was inhibited by the increasing CO2 flux, with the average content varying from 22.69 to 11.25 mg/(Kg h (p < 0.05. However, the increasing activity amplitude of the polyphenol oxidase enzyme approached 230%, while the urease activity presented a similar rising trend. Alpha diversity results showed that the Shannon index decreased from 7.66 ± 0.13 to 5.23 ± 0.35 as the soil CO2 concentration increased. The dominant phylum in the soil samples was Proteobacteria, whose proportion rose rapidly from 28.85% to 67.93%. In addition, the proportion of Acidobacteria decreased from 19.64% to 9.29% (p < 0.01. Moreover, the abundances of genera Methylophilus, Methylobacillus, and Methylovorus increased, while GP4, GP6 and GP7 decreased. Canonical correlation analysis

Leakage test evaluation used for qualification of iodine-125 seeds sealing

International Nuclear Information System (INIS)

Feher, Anselmo; Rostelato, Maria E.C.M.; Zeituni, Carlos A.; Calvo, Wilson A.P.; Somessari, Samir L.; Moura, Joao A.; Moura, Eduardo S.; Souza, Carla D.; Rela, Paulo R.

2009-01-01

The prostate cancer is a problem of public health in Brazil, and the second cause of cancer deaths in men, exceeded only by lung cancer. Among the possible treatments available for prostate cancer is brachytherapy, in which small seeds containing Iodine-125 radioisotope are implanted in the prostate. The seed consists of a sealed titanium tube measuring 0.8 mm external diameter and 4.5 mm in length, containing a central silver wire with adsorbed Iodine-125. The tube sealing is made with titanium at the ends, using electric arc welding or laser process. This sealing must be leakage-resistant and free of cracks, therefore avoiding the Iodine-125 to deposit in the silver wire to escape and spread into the human body. To ensure this problem does not occur, rigorous leakage tests, in accordance with the standard Radiation protection - Sealed Radioactive Sources - leakage Test Methods - ISO 9978, should be applied. The aim of this study is to determine, implement and evaluate the leakage test to be used in the Iodine-125 seeds production, in order to qualify the sealing procedure. The standard ISO 9978 presents a list of tests to be carried out according to the type of source. The preferential methods for brachytherapy sources are soaking and helium. To assess the seeds leakage, the method of immersion test at room temperature was applied. The seeds are considered leakage-free if the detected activity does not exceed the 185 Bq (5 nCi). An Iodine standard was prepared and its value determined in a sodium iodide detector. A liquid scintillation counter was calibrated with the standard for seeds leakage tests. Forty-eight seeds were welded for these tests. (author)

Anastomotic leakage after esophageal resection: new treatment options by endoluminal vacuum therapy.

Science.gov (United States)

Weidenhagen, Rolf; Hartl, Wolfgang H; Gruetzner, Klaus U; Eichhorn, Martin E; Spelsberg, Fritz; Jauch, Karl W

2010-11-01

Anastomotic leakage after esophagectomy is an important determinant of early and late morbidity and mortality. Control of the septic focus is essential when treating patients with anastomotic leakages. Surgical and endoscopic treatment options are limited. Between 2005 and 2009, we treated 6 patients who experienced an intrathoracic anastomotic leakage after esophageal resection. After all established therapeutic measures had failed, we explored the feasibility of an endoscopically assisted mediastinal vacuum therapy. We were able to heal intrathoracic esophageal leakages in all 6 patients without any local complications and without the need for reoperation. One patient died because of a progressive pneumonia. Endoscopic vacuum-assisted closure of anastomotic leakages may help to overcome the limitations that are associated with intermittent endoscopic treatment and conventional drainage therapy. Our preliminary results suggest that this new concept may be suitable for those patients. Copyright © 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Leakage Detection and Estimation Algorithm for Loss Reduction in Water Piping Networks

Directory of Open Access Journals (Sweden)

Kazeem B. Adedeji

2017-10-01

Full Text Available Water loss through leaking pipes constitutes a major challenge to the operational service of water utilities. In recent years, increasing concern about the financial loss and environmental pollution caused by leaking pipes has been driving the development of efficient algorithms for detecting leakage in water piping networks. Water distribution networks (WDNs are disperse in nature with numerous number of nodes and branches. Consequently, identifying the segment(s of the network and the exact leaking pipelines connected to this segment(s where higher background leakage outflow occurs is a challenging task. Background leakage concerns the outflow from small cracks or deteriorated joints. In addition, because they are diffuse flow, they are not characterised by quick pressure drop and are not detectable by measuring instruments. Consequently, they go unreported for a long period of time posing a threat to water loss volume. Most of the existing research focuses on the detection and localisation of burst type leakages which are characterised by a sudden pressure drop. In this work, an algorithm for detecting and estimating background leakage in water distribution networks is presented. The algorithm integrates a leakage model into a classical WDN hydraulic model for solving the network leakage flows. The applicability of the developed algorithm is demonstrated on two different water networks. The results of the tested networks are discussed and the solutions obtained show the benefits of the proposed algorithm. A noteworthy evidence is that the algorithm permits the detection of critical segments or pipes of the network experiencing higher leakage outflow and indicates the probable pipes of the network where pressure control can be performed. However, the possible position of pressure control elements along such critical pipes will be addressed in future work.

Leakage Account for Radial Face Contact Seal in Aircraft Engine Support

Science.gov (United States)

Vinogradov, A. S.; Sergeeva, T. V.

2018-01-01

The article is dedicated to the development of a methodology for the radial face contact seal design taking into consideration the supporting elements deformations in different aircraft engine operating modes. Radial face contact seals are popular in the aircraft engines bearing support. However, there are no published leakage calculation methodologies of these seals. Radial face contact seal leakage is determined by the gap clearance in the carbon seal ring split. In turn, the size gap clearance depends on the deformation of the seal assembly parts and from the engine operation. The article shows the leakage detection sequence in the intershaft radial face contact seal of the compressor support for take-off and cruising modes. Evaluated calculated leakage values (2.4 g/s at takeoff and 0.75 g/s at cruising) go with experience in designing seals.

Effect of condenser water in-leakage on steam generator water chemistry

International Nuclear Information System (INIS)

Balakrishnan, P.V.

1978-01-01

Corrosive environments may be generated within steam genrators from condenser cooling water in-leakage. Theoretical as well as experimental evaluation of the aggressiveness of such environments is being carried out for the condenser-cooling waters used at CANDU-PHW nuclear power stations. Calculations have shown that highly concentrated chloride solutions - acidic in the case of sea-water in-leakage, and alkaline in the rest of the cases considered - would be produced within the steam generator. Experiments in a model boiler showed that sea-water in-leakage caused rapid corrosion of carbon steel components when only AVT (all volatile treatment) was used for water chemistry control. Use of a non-volatile reagent, as in the congruent phosphate treatment, avoided the rapid corrosion of carbon steel. On the basis of our studies, congruent phosphate treatment during sea water in-leakage appears desirable. (author)

CT evaluation of local leakage of bone cement after percutaneous kyphoplasty and vertebroplasty

International Nuclear Information System (INIS)

Lee, In Jae; Choi, A. Lam; Yie, Mi-Yeon; Yoon, Ji Young; Jeon, Eui Yong; Koh, Sung Hye; Yoon, Dae Young; Lim, Kyung Ja; Im, Hyoung June

2010-01-01

Background: Percutaneous injection of bone cement (acrylic cement) during percutaneous kyphoplasty and vertebroplasty can cause symptomatic or asymptomatic complications due to leakage, extravasation or vascular migration of cement. Purpose: To investigate and to compare the incidence and site of local leakage or complications of bone cement after percutaneous kyphoplasty and vertebroplasty using bone cement. Material and Methods: We retrospectively reviewed 473 cases of percutaneous kyphoplasty or vertebroplasty performed under fluoroscopic guidance. Of the 473 cases, follow-up CT scans that covered the treated bones were available for 83 cases (59 kyphoplasty and 24 vertebroplasty). Results: The rate of local leakage of bone cement was 87.5% (21/24) for percutaneous vertebroplasty and 49.2% (29/59) for kyphoplasty. The most common site of local leakage was perivertebral soft tissue (n=8, 38.1%) for vertebroplasty. The most common site of local leakage was a perivertebral vein (n=7, 24.1%) for kyphoplasty. Two cases of pulmonary cement embolism developed: one case after kyphoplasty and one case after vertebroplasty. Conclusion: Local leakage of bone cement was more common for percutaneous vertebroplasty compared with kyphoplasty (P<0.005). The most common sites of local leakage were perivertebral soft tissue and perivertebral vein.

Cumulative Impacts of Energy and Climate Change Policies on Carbon Leakage

Energy Technology Data Exchange (ETDEWEB)

Varma, A.; Milnes, R.; Miller, K.; Williams, E. [AEA Technology plc, London (United Kingdom); De Bruyn, S.; Brinke, L. [CE Delft, Delft (Netherlands)

2012-02-15

Carbon leakage occurs when climate change policy aimed at reducing carbon dioxide emissions in one country leads to an increase in carbon dioxide emissions in a country that is not bound by these policies. Given that climate change is a global issue, carbon leakage impacts upon the effectiveness of climate change policies. This independent study examines the cumulative impact of climate change policies on carbon leakage. The report brings together findings and analysis from a wide range of primary literature in this area and where possible, conclusions relevant to the UK are drawn.

Leakage tests of wall segments of reactor containments

International Nuclear Information System (INIS)

Rizkalla, S.H.; Simmonds, S.H.; MacGregor, J.G.

1979-10-01

Two prestressed concrete wall segments simulating portions of containment walls were loaded by axial tensile forces to cause cracking of the concrete. At each load increment air pressure was applied in steps up to 21 psi to one side of the segment and the rate of leakage of air through the cracked concrete section was measured. A theoretical equation for the flow of air through concrete cracks is developed and the results from one leakage test are used to determine the dimensionless constant required for this equation. (author)

Method for detecting resin leakage in LWR coolant

International Nuclear Information System (INIS)

Girard, J.E.

1988-05-01

Resin leakage from condensate polishing units can result in steam generator corrosion. This report describes the development of a resin leakage detection method based in analyzing the organic breakdown products released from resin on heating. The breakdown products are analyzed using high performance liquid chromatography (HPLC) with fluorescence detection. Some of the organic products formed have been identified. A design for a resin monitoring unit, suitable for incorporation into the IONTRAC system, is presented. Theoretically, detection of ppB levels of resin by processing about one liter of water, is possible

Non-fistulous urinary leakage among women attending a Nigerian family planning clinic

Directory of Open Access Journals (Sweden)

Ijaiya MA

2011-12-01

Full Text Available Munir'deen A Ijaiya1, Hadijat O Raji1, Abiodun P Aboyeji1, Kike T Adesina1, Idowu O Adebara2, Grace G Ezeoke11Department of Obstetrics and Gynaecology, University of Ilorin Teaching Hospital, Ilorin, Nigeria; 2Department of Obstetrics and Gynaecology, Federal Medical Centre, Ido-Ekiti, NigeriaAbstract: Urinary leakage is an important gynecological challenge, which has a substantial impact on quality of life. The aim of this study was to determine the prevalence and types of non-fistulous urinary leakage among women attending the family planning clinic of the University of Ilorin teaching hospital, Ilorin, Nigeria. The study was a cross-sectional study carried out between January 3 and April 25 2009. One hundred and two women experienced urinary leakage out of 333 women interviewed, giving a prevalence rate of 30.6%. Stress incontinence was the most common urinary leakage (prevalence rate 12.0%. This is followed by urge incontinence (10.8%, urinary incontinence (4.8%, and overflow incontinence (3.0%. None of the women afflicted sought medical help. Conclusively, this study has demonstrated that non-fistulous urinary leakage is a common problem among women of reproductive age in this environment.Keywords: non-fistulous urinary leakage, family planning, women, prevalence, types

HTS current lead units prepared by the TFA-MOD processed YBCO coated conductors

International Nuclear Information System (INIS)

Shiohara, K.; Sakai, S.; Ishii, Y.; Yamada, Y.; Tachikawa, K.; Koizumi, T.; Aoki, Y.; Hasegawa, T.; Tamura, H.; Mito, T.

2010-01-01

Two superconducting current lead units have been prepared using ten coated conductors of the Tri-Fluoro-Acetate - Metal Organic Deposition (TFA-MOD) processed Y 1 Ba 2 Cu 3 O 7-δ (YBCO) coated conductors with critical current (I c ) of about 170 A at 77 K in self-field. The coated conductors are 5 mm in width, 190 mm in length and about 120 μm in overall thickness. The 1.5 μm thick superconducting YBCO layer was synthesized through the TFA-MOD process on Hastelloy TM C-276 substrate tape with two buffer oxide layers of Gd 2 Zr 2 O 7 and CeO 2 . The five YBCO coated conductors are attached on a 1 mm thick Glass Fiber Reinforced Plastics (GFRP) board and soldered to Cu caps at the both ends. We prepared two 500 A-class current lead units. The DC transport current of 800 A was stably applied at 77 K without any voltage generation in all coated conductors. The voltage between both Cu caps linearly increased with increasing the applied current, and was about 350 μV at 500 A in both current lead units. According to the estimated values of the heat leakage from 77 K to 4.2 K, the heat leakage for the current lead unit was 46.5 mW. We successfully attained reduction of the heat leakage because of improvement of the transport current performance (I c ), a thinner Ag layer of YBCO coated conductor and usage of the GFRP board for reinforcement instead of a stainless steel board used in the previous study. The DC transport current of 1400 A was stably applied when the two current lead units were joined in parallel. The sum of the heat leakages from 77 K to 4.2 K for the combined the current lead units was 93 mW. In comparison with the conventional Cu current leads by gas-cooling, it could be noted that the heat leakage of the current lead is about one order of magnitude smaller than that of the Cu current lead.

Satellite assisted aerosol correlation in a sequestered CO2 leakage controlled site

Science.gov (United States)

Landulfo, Eduardo; da Silva Lopes, Fábio J.; Nakaema, Walter M.; de Medeiros, José A. G.; Moreira, Andrea

2014-10-01

Currently one of the main challenges in CO2 storage research is to grant the development, testing and validation of accurate and efficient Measuring, Monitoring and Verification (MMV) techniques to be deployed at the final storage site, targeting maximum storage efficiency at the minimal leakage risk levels. For such task a mimetic sequestration site has been deployed in Florianopolis, Brazil, in order to verify the performance of monitoring plataforms to detect and quantify leakages of ground injected CO2, namely a Cavity Ring Down System (CRDS) - Los Gatos Research - an Eddy Covariance System (Campbell Scientific and Irgason) and meteorological tower for wind, humidity, precipitation and temperature monitoring onsite. The measurement strategy for detecting CO2 leakages can be very challenging since environmental and phytogenic influence can be very severe and play a role on determining if the values measured are unambiguous or not. One external factor to be considered is the amount of incoming solar radiation which will be the driving force for the whole experimental setup and following this reasoning the amount of aerosols in the atmospheric column can be a determinant factor influencing the experimental results. Thus the investigation of measured fluxes CO2 and its concentration with the aforementioned experimental instruments and their correlation with the aerosol data should be taken into account by means of satellite borne systems dedicated to measure aerosol vertical distribution and its optical properties, in this study we have selected CALIPSO and MODIS instrumentation to help on deriving the aerosol properties and CO2 measurements.

Prevention through policy: Urban macroplastic leakages to the marine environment during extreme rainfall events

OpenAIRE

Axelsson, Charles; van Sebille, Erik

2017-01-01

The leakage of large plastic litter (macroplastics) into the ocean is a major environmental problem. A significant fraction of this leakage originates from coastal cities, particularly during extreme rainfall events. As coastal cities continue to grow, finding ways to reduce this macroplastic leakage is extremely pertinent. Here, we explore why and how coastal cities can reduce macroplastic leakages during extreme rainfall events. Using nine global cities as a basis, we establish that while c...

Evaluation of isolation valve leakage in alternate charging piping

International Nuclear Information System (INIS)

Strauch, P.L.; Roarty, D.H.; Brice-Nash, R.L.

1995-01-01

The chemical and volume control system (CVCS) alternate charging flow path at an operating pressurized water reactor (PWR) plant was determined to be susceptible to adverse stresses from isolation valve leakage. Isolation valve leakage had resulted in pipe cracks at several nuclear units worldwide, as described in United States Nuclear Regulatory Commission Bulletin 88-08 and its supplements. To provide for continuing assurance that cracks would not initiate over the plant life, the operators considered performing fatigue evaluation to demonstrate structural integrity of the system. This evaluation included heat transfer, stress and fatigue analysis, using methods described in Electric Power Research Institute Report ''Thermal Stratification, Cycling, and Striping (TASCS),'' March 1994. The evaluation concluded that the fatigue usage would be less than 1.0 under worst case isolation valve leakage conditions, and therefore a significant investment in permanent temperature monitoring was avoided

Leakage of pressurized gases through unlined concrete containment structures

International Nuclear Information System (INIS)

Rizkalla, S.H.; Simmonds, S.H.

1983-01-01

Eight reinforced concrete specimens were fabricated and subjected to tensile membrane forces and air pressure to study the air leakage characteristics in cracked reinforced concrete members. A mathematical expression for the rate of pressurized air flowing through an idealized crack is presented. The mathematical expression is refined by using the experimental data to describe the air flow rate through any given crack pattern. Graphical charts are also presented for the calculation of the air leakage rate through concrete cracks. The concept of equivalent crack width for a given crack pattern is introduced. The mathematical expression and graphical charts are modified to include this equivalent crack width concept. The proposed technique is applicable for the prediction of the leakage from concrete containment structures or any similar structures due to high internal pressure sufficient to initiate cracking. (orig.)

Research on leakage detection of nuclear power station primary loop

International Nuclear Information System (INIS)

Cao Shengquan; Yang Jicai; Li Jianjun; Dong Zhijuan; Ren Juyan; Zhang Pinyuan

1993-01-01

The sensor of leak-detection system is a special humidity-sensitive element. In this system, the collection and treatment of detected data, and the leakage alarm are controlled by a simple board computer. The three parameters A, B and C are set up in this system, and the alarm will give out when signal surpasses values of B and C at the same time. The effects of environment humidity and temperature on collection of detected data are considered, and the leakage alarm is reliable. When the leakage rate of water at 320 degree C and 12.2 MPa is 0.3 g/min, the alarm signal will sent out within 5 s

Leakage Characteristics of Dual-Cannula Fenestrated Tracheostomy Tubes during Positive Pressure Ventilation: A Bench Study

Directory of Open Access Journals (Sweden)

Thomas Berlet

2016-01-01

Full Text Available This study compared the leakage characteristics of different types of dual-cannula fenestrated tracheostomy tubes during positive pressure ventilation. Fenestrated Portex® Blue Line Ultra®, TRACOE® twist, or Rüsch® Traceofix® tracheostomy tubes equipped with nonfenestrated inner cannulas were tested in a tracheostomy-lung simulator. Transfenestration pressures and transfenestration leakage rates were measured during positive pressure ventilation. The impact of different ventilation modes, airway pressures, temperatures, and simulated static lung compliance settings on leakage characteristics was assessed. We observed substantial differences in transfenestration pressures and transfenestration leakage rates. The leakage rates of the best performing tubes were <3.5% of the delivered minute volume. At body temperature, the leakage rates of these tracheostomy tubes were <1%. The tracheal tube design was the main factor that determined the leakage characteristics. Careful tracheostomy tube selection permits the use of fenestrated tracheostomy tubes in patients receiving positive pressure ventilation immediately after stoma formation and minimises the risk of complications caused by transfenestration gas leakage, for example, subcutaneous emphysema.

MODELING OF TECHNICAL CHANNELS OF INFORMATION LEAKAGE AT DISTRIBUTED CONTROL OBJECTS

Directory of Open Access Journals (Sweden)

Aleksander Vladimirovich Karpov

2018-05-01

Full Text Available The significant increase in requirements for distributed control objects’ functioning can’t be realized only at the expense of the widening and strengthening of security control measures. The first step in ensuring the information security at such objects is the analysis of the conditions of their functioning and modeling of technical channels of information leakage. The development of models of such channels is essentially the only method of complete study of their opportunities and it is pointed toward receiving quantitative assessments of the safe operation of compound objects. The evaluation data are necessary to make a decision on the degree of the information security from a leak according to the current criterion. The existing models are developed for the standard concentrated objects and allow to evaluate the level of information security from a leak on each of channels separately, what involves the significant increase in the required protective resource and time of assessment of information security on an object in general. The article deals with a logical-and-probabilistic method of a security assessment of structurally-compound objects. The model of a security leak on the distributed control objects is cited as an example. It is recommended to use a software package of an automated structurally-logistical modeling of compound systems, which allows to evaluate risk of information leakage in the loudspeaker. A possibility of information leakage by technical channels is evaluated and such differential characteristics of the safe operation of the distributed control objects as positive and negative contributions of the initiating events and conditions, which cause a leak are calculated. Purpose. The aim is a quantitative assessment of data risk, which is necessary for justifying the rational composition of organizational and technical protection measures, as well as a variant of the structure of the information security system from a

Prevalence of extravertebral cement leakage after vertebroplasty: procedural documentation versus CT detection.

Science.gov (United States)

Martin, Douglas J; Rad, Arash Ehteshami; Kallmes, David F

2012-06-01

Reported incidence of extravertebral cement leakage after vertebroplasty varies widely across studies. To retrospectively compare the relative detection rates of extravertebral leakage noted under intra-procedural fluoroscopic surveillance, postprocedure plain radiographs, and postprocedure computed tomography (CT) in a cohort of patients undergoing vertebroplasty. With IRB approval, we retrospectively identified 181 patients with 277 levels treated with percutaneous vertebroplasty among a total of 1255 patients undergoing vertebroplasty between 1999 and 2010 who had subsequently undergone a CT examination that included the treated level(s). Categories of leakage were paravertebral, end plate, epidural, and prevertebral venous leakage. CT-detected leak rates were then compared to those noted on the vertebroplasty procedure reports and the archived fluoroscopic images for this same cohort using Pearson's χ(2) test. One hundred and forty-nine (82%, 95% CI 76-87%) of 181 patients demonstrated evidence of some type of leakage on CT at one or more treated levels. Sixty-two (34%, 95% CI 28-42%) and seventy-seven (50%, 95% CI 43-57%) of 149 CT-detected leaks were reported in the procedural dictation or detected on plain radiography (P = 0.01 and 0.006, respectively). The most common type of leakage noted on CT was end plate (n = 81, 45%, 95% CI 38-52%), followed by paravertebral (n = 64, 35%, 95% CI 29-43%), epidural (n = 36, 20%, 95% CI 15-26%), and prevertebral venous (n = 32, 18%, 95% CI 13-24%). Cement leakage after vertebroplasty is common and is often not reported by operators in procedural dictations. CT detects substantially more leaks than plain radiography.

Simulating CO₂ leakages from CCS to determine Zn toxicity using the marine microalgae Pleurochrysis roscoffensis.

Science.gov (United States)

Bautista-Chamizo, Esther; De Orte, Manoela Romanó; DelValls, Tomás Ángel; Riba, Inmaculada

2016-02-01

Due to the current climate change and ocean acidification, a new technology for CO2 mitigation has been proposed, the Carbon dioxide Capture and Storage (CCS). However, there is an ecological risk associated with potential CO2 leakages from the sub-seabed storages sites. To evaluate the effects related to CO2 leakages, laboratory-scales experiments were performed using the marine microalgae Pleurochrysis roscoffensis. Five Zn concentrations were tested at different pHs to study Zn toxicity under acidified conditions. Seawater was collected and submitted to acidification by means of CO2 injection and by HCl addition. Results showed differences between both acidification techniques: while microalgae growth was enhanced by CO2 supply, reaching the optimal growth at pH 6.5 and full inhibition at pH 5.5, HCl acidification growth was inhibited at pH 6.5. Although small concentrations of Zn were positive for P. roscoffensis growth, Zn toxicity increased at lower pHs, and more severely on samples acidified with HCl. The conclusions obtained in this work are useful to address the potential effects on the marine ecosystem related to changes in metal bioavailability during CO2 leakages scenarios. Copyright © 2015 Elsevier Ltd. All rights reserved.

Embolization for Thoracic Duct Collateral Leakage in High-Output Chylothorax After Thoracic Surgery

International Nuclear Information System (INIS)

Kariya, Shuji; Nakatani, Miyuki; Yoshida, Rie; Ueno, Yutaka; Komemushi, Atsushi; Tanigawa, Noboru

2017-01-01

PurposeThis study was designed to investigate thoracic duct collateral leakage and the supply route of lymphatic fluid by lymphangiography and transcatheter thoracic ductography and to evaluate the results of embolization for thoracic duct collateral leakage performed to cut off this supply route.MethodsData were retrospectively collected from five patients who underwent embolization for thoracic duct collateral leakage in persistent high-output chylothorax after thoracic surgery. Extravasation of lipiodol at the ruptured thoracic duct collaterals was confirmed in all patients on lymphangiography. Transcatheter thoracic ductography was used to identify extravasation of iodinated contrast agent and to identify communication between the thoracic duct and leakage site. Thoracic duct embolization (TDE) was performed using the percutaneous transabdominal approach to cut off the supply route using N-butyl cyanoacrylate (NBCA) mixed with lipiodol (1:5–1:20).ResultsClinical success (drainage volume ≤10 mL/kg/day within 7 days after TDE) was achieved in all patients. The collateral routes developed as consequence of surgical thoracic duct ligation. In three patients, NBCA-Lipiodol reached the leakage site through direct communication between the thoracic duct and the ruptured lymphatic duct. In the other two patients, direct communication and extravasation was not detected on thoracic ductography, and NBCA-Lipiodol did not reach the leakage site. However, NBCA-Lipiodol did reach the cisterna chyli, lumbar trunks, and some collateral routes via the cisterna chyli or lumbar lymphatics. As a result, leakage was stopped.ConclusionsTDE was effective for the management of leakage of the collaterals in high-output chylothorax after thoracic surgery.

Embolization for Thoracic Duct Collateral Leakage in High-Output Chylothorax After Thoracic Surgery

Energy Technology Data Exchange (ETDEWEB)

Kariya, Shuji, E-mail: kariyas@hirakata.kmu.ac.jp; Nakatani, Miyuki, E-mail: nakatanm@hirakata.kmu.ac.jp; Yoshida, Rie, E-mail: yagir@hirakata.kmu.ac.jp; Ueno, Yutaka, E-mail: uenoyut@hirakata.kmu.ac.jp; Komemushi, Atsushi, E-mail: komemush@takii.kmu.ac.jp; Tanigawa, Noboru, E-mail: tanigano@hirakata.kmu.ac.jp [Kansai Medical University, Department of Radiology (Japan)

2017-01-15

PurposeThis study was designed to investigate thoracic duct collateral leakage and the supply route of lymphatic fluid by lymphangiography and transcatheter thoracic ductography and to evaluate the results of embolization for thoracic duct collateral leakage performed to cut off this supply route.MethodsData were retrospectively collected from five patients who underwent embolization for thoracic duct collateral leakage in persistent high-output chylothorax after thoracic surgery. Extravasation of lipiodol at the ruptured thoracic duct collaterals was confirmed in all patients on lymphangiography. Transcatheter thoracic ductography was used to identify extravasation of iodinated contrast agent and to identify communication between the thoracic duct and leakage site. Thoracic duct embolization (TDE) was performed using the percutaneous transabdominal approach to cut off the supply route using N-butyl cyanoacrylate (NBCA) mixed with lipiodol (1:5–1:20).ResultsClinical success (drainage volume ≤10 mL/kg/day within 7 days after TDE) was achieved in all patients. The collateral routes developed as consequence of surgical thoracic duct ligation. In three patients, NBCA-Lipiodol reached the leakage site through direct communication between the thoracic duct and the ruptured lymphatic duct. In the other two patients, direct communication and extravasation was not detected on thoracic ductography, and NBCA-Lipiodol did not reach the leakage site. However, NBCA-Lipiodol did reach the cisterna chyli, lumbar trunks, and some collateral routes via the cisterna chyli or lumbar lymphatics. As a result, leakage was stopped.ConclusionsTDE was effective for the management of leakage of the collaterals in high-output chylothorax after thoracic surgery.

Leakage Risk Assessment for a Potential CO2 Storage Project in Saskatchewan, Canada

Energy Technology Data Exchange (ETDEWEB)

Houseworth, J.E.; Oldenburg, C.M.; Mazzoldi, A.; Gupta, A.K.; Nicot, J.-P.; Bryant, S.L.

2011-05-01

A CO{sub 2} sequestration project is being considered to (1) capture CO{sub 2} emissions from the Consumers Cooperative Refineries Limited at Regina, Saskatchewan and (2) geologically sequester the captured CO{sub 2} locally in a deep saline aquifer. This project is a collaboration of several industrial and governmental organizations, including the Petroleum Technology Research Centre (PTRC), Sustainable Development Technology Canada (SDTC), SaskEnvironment Go Green Fund, SaskPower, CCRL, Schlumberger Carbon Services, and Enbridge. The project objective is to sequester 600 tonnes CO{sub 2}/day. Injection is planned to start in 2012 or 2013 for a period of 25 years for a total storage of approximately 5.5 million tonnes CO{sub 2}. This report presents an assessment of the leakage risk of the proposed project using a methodology known as the Certification Framework (CF). The CF is used for evaluating CO{sub 2} leakage risk associated with geologic carbon sequestration (GCS), as well as brine leakage risk owing to displacement and pressurization of brine by the injected CO{sub 2}. We follow the CF methodology by defining the entities (so-called Compartments) that could be impacted by CO{sub 2} leakage, the CO{sub 2} storage region, the potential for leakage along well and fault pathways, and the consequences of such leakage. An understanding of the likelihood and consequences of leakage forms the basis for understanding CO{sub 2} leakage risk, and forms the basis for recommendations of additional data collection and analysis to increase confidence in the risk assessment.

Preoperative risk factors for anastomotic leakage after resection for colorectal cancer

DEFF Research Database (Denmark)

Pommergaard, Hans-Christian; Gessler, B; Burcharth, Jakob

2014-01-01

AIM: Colorectal anastomotic leakage is a serious complication. Despite extensive research, no consensus on the most important preoperative risk factors exists. The aim of this systematic review and meta-analysis was to evaluate risk factors for anastomotic leakage in patients operated with colore...

SU-F-J-144: Scatter and Leakage Survey of An Integrated MR-Linac System

Energy Technology Data Exchange (ETDEWEB)

Wang, J; Bosco, G; Darenbourg, B; Ibbott, G [UT MD Anderson Cancer Center, Houston, TX (United States)

2016-06-15

Purpose: To assess the scatter and leakage radiation of an integrated 1.5T MRI-Linac system. Methods: A 150cc chamber (model 96020C, Inovision) was used in all the scatter and leakage measurements, after being recalibrated for MV energy by the Accredited Dosimetry Calibration Laboratory at MD Anderson. The scatter radiation was measured by placing a 25 cm stack of solid-water materials at iso-center on the patient couch to simulate patient scatter. Gantry angles were positioned at 0 degree (beam pointing downward) and 270 (beam pointing laterally). Scatter radiation was measured at selective locations inside the RF room. Beam stopper leakage was measured at the exterior panel of the gantry. The head leakage was measured at 1 meter away from the Linac head in the direction which was determined to be the area of maximum leakage by wrapped films test. All measurements were repeated with the 1.5T magnetic field turned off to study the effect of magnetic field. Results: When the magnet was on (B=1.5T), the maximum head leakage at 1 meter was 191.6mR/1000MU. The scatter radiation at 1 meter from the iso-center was 1.091R/1000MU when the radiation beam was pointing downward, 1.296R/1000MU when the beam pointed laterally. The beam stopper leakage was measured as 299.4 mR/1000MU at the exterior panel of the gantry. When magnet was off (B=0), the head leakage was measured as 198.6mR/1000MU. The scatter radiation at 1 meter was 1.153R/1000MU when beam pointed downward, 1.287R/1000MU when beam pointed laterally. The beam stopper leakage was measured as 309.4 mR/1000MU at the exterior panel of the gantry. Conclusion: The measurements indicate that the scatter and leakage radiation from the integrated MR-Linac system are in-line with the expected values. The beam stopper leakage is approximately 300 mR/1000MU. The leakage and scatter difference with the magnetic field ON and OFF was within 5%. The authors received a corporate sponsored grant from Elekta which is the vendor of

A coupled approach for the three-dimensional simulation of pipe leakage in variably saturated soil

Science.gov (United States)

Peche, Aaron; Graf, Thomas; Fuchs, Lothar; Neuweiler, Insa

2017-12-01

In urban water pipe networks, pipe leakage may lead to subsurface contamination or to reduced waste water treatment efficiency. The quantification of pipe leakage is challenging due to inaccessibility and unknown hydraulic properties of the soil. A novel physically-based model for three-dimensional numerical simulation of pipe leakage in variably saturated soil is presented. We describe the newly implemented coupling between the pipe flow simulator HYSTEM-EXTRAN and the groundwater flow simulator OpenGeoSys and its validation. We further describe a novel upscaling of leakage using transfer functions derived from numerical simulations. This upscaling enables the simulation of numerous pipe defects with the benefit of reduced computation times. Finally, we investigate the response of leakage to different time-dependent pipe flow events and conclude that larger pipe flow volume and duration lead to larger leakage while the peak position in time has a small effect on leakage.

Method of detecting leakage from geologic formations used to sequester CO.sub.2

Science.gov (United States)

White, Curt [Pittsburgh, PA; Wells, Arthur [Bridgeville, PA; Diehl, J Rodney [Pittsburgh, PA; Strazisar, Brian [Venetia, PA

2010-04-27

The invention provides methods for the measurement of carbon dioxide leakage from sequestration reservoirs. Tracer moieties are injected along with carbon dioxide into geological formations. Leakage is monitored by gas chromatographic analyses of absorbents. The invention also provides a process for the early leak detection of possible carbon dioxide leakage from sequestration reservoirs by measuring methane (CH.sub.4), ethane (C.sub.2H.sub.6), propane (C.sub.3H.sub.8), and/or radon (Rn) leakage rates from the reservoirs. The invention further provides a method for branding sequestered carbon dioxide using perfluorcarbon tracers (PFTs) to show ownership.

Low field leakage current on ultra-thin gate oxides after ion or electron beam irradiations; Courant de fuite aux champs faibles d'oxydes ultra-minces apres irradiations avec des faisceaux d'ions et d'electrons

Energy Technology Data Exchange (ETDEWEB)

Ceschia, M.; Paccagnella, A.; Sandrin, S. [Universita di Padova, Dipt. di Elettronica e Informatica, Padova (Italy); Paccagnella, A. [Istituto Nazionale per la Fisica della Materia, INFM, Unita di Padova (Italy); Ghidini, G. [ST-Microelectronics, Agrate Brianza (Italy); Wyss, J. [Universita di Padova, Dipt. di Fisica, Padova (Italy)

1999-07-01

In contemporary CMOS 0.25-{mu}m technologies, the MOS gate oxide (thickness {approx_equal} 5 nm) shows a low-field leakage current after radiation stresses, i.e. the radiation induced leakage current (RILC). RILC is generally attributed to a trap assisted tunneling (TAT) of electrons through neutral oxide traps generated by radiation stress. RILC has been investigated on ultra-thin oxides irradiated with 158 MeV {sup 28}Si ions or 8 MeV electrons. 3 main results are worth being quoted: 1) ion or electron beam irradiation can produce RILC with similar characteristics. Even the dose dependence of RILC is similar in the 2 cases, despite the large LET difference (about a factor of 10{sup +4}), 2) RILC is not a constant as a function of time, it tends to decrease when an oxide field (few MV/cm) is applied for (tens of) thousands seconds. On the other hand, RILC stays constant in devices kept at low bias, and 3) if a pulsed gate voltage is applied during irradiation, RILC is reduced with respect to the zero-field case. (A.C.)

Application of thermometric methods for detection and characterization of leakages in embankment dams

Energy Technology Data Exchange (ETDEWEB)

Beck, Y.L.; Cunat, P.; Fry, J.J. [EDF, Grenoble (France); Faure, Y.H. [LTHE, Saint Martin d' Heres (France)

2010-07-01

The earliest possible detection of leakages in dikes is essential. Distributed temperature measurements using fibre optics allow the monitoring of large sections of the dike with a high spatial and temperature resolution. This paper presented the application of thermometric methods for detection and characterization of leakage in embankment dams. After a brief description of the system used, its application on a controlled experimental site and an EDF industrial site instrumented with fibre optics was presented. The instrumentation is complemented by installation of local temperature and pressure sensors in the piezometers for complete characterization of the detected leakages. The analysis of the results data clearly allowed detecting the leakages. The vertical location, intensity and location of the detected leakages were also identified. It was found that thermometry is potentially very powerful for detecting leaks and as a diagnostic tool.

Time reversal technique for gas leakage detection.

Science.gov (United States)

Maksimov, A O; Polovinka, Yu A

2015-04-01

The acoustic remote sensing of subsea gas leakage traditionally uses sonars as active acoustic sensors and hydrophones picking up the sound generated by a leak as passive sensors. When gas leaks occur underwater, bubbles are produced and emit sound at frequencies intimately related to their sizes. The experimental implementation of an acoustic time-reversal mirror (TRM) is now well established in underwater acoustics. In the basic TRM experiment, a probe source emits a pulse that is received on an array of sensors, time reversed, and re-emitted. After time reversal, the resulting field focuses back at the probe position. In this study, a method for enhancing operation of the passive receiving system has been proposed by using it in the regime of TRM. Two factors, the local character of the acoustic emission signal caused by the leakage and a resonant nature of the bubble radiation at their birth, make particularly effective scattering with the conjugate wave (CW). Analytical calculations are performed for the scattering of CW wave on a single bubble when CW is formed by bubble birthing wail received on an array, time reversed, and re-emitted. The quality of leakage detection depends on the spatio-temporal distribution of ambient noise.

Increased risk of anastomotic leakage with diclofenac treatment after laparoscopic colorectal surgery

DEFF Research Database (Denmark)

Klein, Mads; Andersen, Lars Peter Holst; Harvald, Thomas

2009-01-01

BACKGROUND: Over a period our department experienced an unexpected high frequency of anastomotic leakages. After diclofenac was removed from the postoperative analgesic regimen, the frequency dropped. This study aimed to evaluate the influence of diclofenac on the risk of developing anastomotic...... leakage after laparoscopic colorectal surgery. METHODS: This was a retrospective case-control study based on 75 consecutive patients undergoing laparoscopic colorectal resection with primary anastomosis. In period 1, patients received diclofenac 150 mg/day. In period 2, diclofenac was withdrawn...... and the patients received an opioid analgesic instead. The primary outcome parameter was clinically significant anastomotical leakage verified at reoperation. RESULTS: 1/42 patients in the no-diclofenac group compared with 7/33 in the diclofenac group had an anastomotic leakage after operation (p = 0...

Integral leakage rate tests of containments

International Nuclear Information System (INIS)

Engel, M.; Siefart, E.; Walter, R.

1978-01-01

A method is presented for the integral leakage rate tests of containments. This method, used in conjunction with statistical methods, provides reliable information on the tightness of the containment. This method forms the basis of DIN 25436/KTA 3405. (orig.) [de

Detection of marginal leakage of Class V restorations in vitro by micro-computed tomography.

Science.gov (United States)

Zhao, X Y; Li, S B; Gu, L J; Li, Y

2014-01-01

This in vitro study evaluated the efficacy of micro-computed tomography (CT) in marginal leakage detection of Class V restorations. Standardized Class V preparations with cervical margins in dentin and occlusal margins in enamel were made in 20 extracted human molars and restored with dental bonding agents and resin composite. All teeth were then immersed in 50% ammoniacal silver nitrate solution for 12 hours, followed by a developing solution for eight hours. Each restoration was scanned by micro-CT, the depth of marginal silver leakage in the central scanning section was measured, and the three-dimensional images of the silver leakage around each restoration were reconstructed. Afterward, all restorations were cut through the center and examined for leakage depth using a microscope. The silver leakage depth of each restoration obtained by the micro-CT and the microscope were compared for equivalency. The silver leakage depth in cervical walls observed by micro-CT and microscope showed no significant difference; however, in certain cases the judgment of leakage depth in the occlusal wall in micro-CT image was affected by adjacent enamel structure, providing less leakage depth than was observed with the microscope (pleakage around the Class V restorations with clear borders only in the dentin region. It can be concluded that micro-CT can detect nondestructively the leakage around a resin composite restoration in two and three dimensions, with accuracy comparable to that of the conventional microscope method in the dentin region but with inferior accuracy in the enamel region.

Correlation between stress-induced leakage current and dielectric degradation in ultra-porous SiOCH low-k materials

Energy Technology Data Exchange (ETDEWEB)

Wu, C., E-mail: Chen.Wu@imec.be; De Wolf, I. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Department of Materials Engineering, KU Leuven, 3000 Leuven (Belgium); Li, Y.; Leśniewska, A.; Varela Pedreira, O.; Marneffe, J.-F. de; Ciofi, I.; Verdonck, P.; Baklanov, M. R.; Bömmels, J.; Tőkei, Zs.; Croes, K. [imec, Kapeldreef 75, 3001 Leuven (Belgium)

2015-10-28

Stress-Induced Leakage Current (SILC) behavior during the dielectric degradation of ultra-porous SiOCH low-k materials was investigated. Under high voltage stress, SILC increases to a critical value before final hard breakdown. This SILC increase rate is mainly driven by the injected charges and is negligibly influenced by temperature and voltage. SILC is found to be transient and shows a t{sup −1} relaxation behavior, where t is the storage time at low voltages. This t{sup −1} transient behavior, described by the tunneling front model, is caused by both electron charging of neutral defects in the dielectric close to the cathode interface and discharging of donor defects close to the anode interface. These defects have a uniform density distribution within the probed depth range, which is confirmed by the observed flat band voltage shift results collected during the low voltage storage. By applying an additional discharging step after the low voltage storage, the trap energies and spatial distributions are derived. In a highly degraded low-k dielectric, the majority of defects have a trap depth between 3.4 eV and 3.6 eV and a density level of 1 × 10{sup 18 }eV{sup −1 }cm{sup −3}. The relation between the defect density N and the total amount of the injected charges Q is measured to be sub-linear, N ∼ Q{sup 0.45±0.07}. The physical nature of these stress-induced defects is suggested to be caused by the degradation of the Si-O based skeleton in the low-k dielectric.

Current Travertines Precipitation from CO2-rich Groundwaters as an alert of CO2 Leakages from a Natural CO2 Storage at Ganuelas-Mazarron Tertiary Basin (Murcia, Spain)

International Nuclear Information System (INIS)

Rodrigo-Naharro, J.; Delgado, A.; Herrero, M. J.; Granados, A.; Perez del Villar, L.

2013-01-01

Carbon capture and storage technologies represent the most suitable solutions related to the high anthropogenic CO 2 emissions to the atmosphere. As a consequence, monitoring of the possible CO 2 leakages from an artificial deep geological CO 2 storage is indispensable to guarantee its safety. Fast surficial travertine precipitation related to these CO 2 leakages can be used as an alert for these escapes. Since few studies exist focusing on the long-term behaviour of an artificial CO 2 DGS, natural CO 2 storage affected by natural or artificial escapes must be studied as natural analogues for predicting the long-term behaviour of an artificial CO 2 storage. In this context, a natural CO 2 reservoir affected by artificial CO 2 escapes has been studied in this work. This study has mainly focused on the current travertines precipitation associated with the upwelling CO 2 -rich waters from several hydrogeological wells drilled in the Ganuelas-Mazarron Tertiary basin (SE Spain), and consists of a comprehensive characterisation of parent-waters and their associated carbonates, including elemental and isotopic geochemistry, mineralogy and petrography. Geochemical characterisation of groundwaters has led to recognise 4 hydrofacies from 3 different aquifers. These groundwaters have very high salinity and electrical conductivity; are slightly acid; present high dissolved inorganic carbon (DIC) and free CO 2 ; are oversaturated in both aragonite and calcite; and dissolve, mobilize and transport low quantities of heavy and/or toxic elements. Isotopic values indicate that: i) the origin of parent-waters is related to rainfalls from clouds originated in the Mediterranean Sea or continental areas; ii) the origin of C is mainly inorganic; and iii) sulphate anions come mainly from the dissolution of the Messinian gypsum from the Tertiary Basin sediments. Current travertines precipitation seems to be controlled by a combination of several factors, such as: i) a fast decrease of the

Effects of Chemistry Parameters of Primary Water affecting Leakage of Steam Generator Tube Cracks

Energy Technology Data Exchange (ETDEWEB)

Shin, D. M.; Cho, N. C.; Kang, Y. S.; Lee, K. H. [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

Degradation of steam generator (SG) tubes can affect pressure boundary tightness. As a defense-in-depth measure, primary to secondary leak monitoring program for steam generators is implemented, and operation is allowed under leakage limits in nuclear power plants. Chemistry parameters that affect steam generator tube leakage due to primary water stress corrosion cracking (PWSCC) are investigated in this study. Tube sleeves were installed to inhibit leakage and improve tube integrity as a part of maintenance methods. Steam generators occurred small leak during operation have been replaced with new steam generators according to plant maintenance strategies. The correlations between steam generator leakage and chemistry parameters are presented. Effects of primary water chemistry parameters on leakage from tube cracks were investigated for the steam generators experiencing small leak. Unit A experienced small leakage from steam generator tubes in the end of operation cycle. It was concluded that increased solubility of oxides due to high pHT could make leakage paths, and low boron concentration lead to less blockage in cracks. Increased dissolved hydrogen may retard crack propagations, but it did not reduce leak rate of the leaking steam generator. In order to inhibit and reduce leakage, pH{sub T} was controlled by servicing cation bed operation. The test results of decreasing pHT indicate low pHT can reduce leak rate of PWSCC cracks in the end of cycle.

Effects of Chemistry Parameters of Primary Water affecting Leakage of Steam Generator Tube Cracks

International Nuclear Information System (INIS)

Shin, D. M.; Cho, N. C.; Kang, Y. S.; Lee, K. H.

2016-01-01

Degradation of steam generator (SG) tubes can affect pressure boundary tightness. As a defense-in-depth measure, primary to secondary leak monitoring program for steam generators is implemented, and operation is allowed under leakage limits in nuclear power plants. Chemistry parameters that affect steam generator tube leakage due to primary water stress corrosion cracking (PWSCC) are investigated in this study. Tube sleeves were installed to inhibit leakage and improve tube integrity as a part of maintenance methods. Steam generators occurred small leak during operation have been replaced with new steam generators according to plant maintenance strategies. The correlations between steam generator leakage and chemistry parameters are presented. Effects of primary water chemistry parameters on leakage from tube cracks were investigated for the steam generators experiencing small leak. Unit A experienced small leakage from steam generator tubes in the end of operation cycle. It was concluded that increased solubility of oxides due to high pHT could make leakage paths, and low boron concentration lead to less blockage in cracks. Increased dissolved hydrogen may retard crack propagations, but it did not reduce leak rate of the leaking steam generator. In order to inhibit and reduce leakage, pH_T was controlled by servicing cation bed operation. The test results of decreasing pHT indicate low pHT can reduce leak rate of PWSCC cracks in the end of cycle

Oil leakage detection for electric power equipment based on ultraviolet fluorescence effect

Science.gov (United States)

Zhang, Jing; Wang, Jian-hui; Xu, Bin; Huang, Zhi-dong; Huang, Lan-tao

2018-03-01

This paper presents a method to detect the oil leakage of high voltage power equipment based on ultraviolet fluorescence effect. The method exploits the principle that the insulating oil has the fluorescent effect under the irradiation of specific ultraviolet light. The emission spectrum of insulating oil under excitation light with different wavelengths is measured and analyzed first. On this basis, a portable oil leakage detective device for high voltage power equipment is designed and developed with a selected 365 nm ultraviolet as the excitation light and the low light level camera as the fluorescence image collector. Then, the feasibility of the proposed method and device in different conditions is experimentally verified in the laboratory environment. Finally, the developed oil leakage detective device is applied to 500 kV Xiamen substation and Quanzhou substation. And the results show that the device can detect the oil leakage of high voltage electrical equipment quickly and conveniently even under the condition of a slight oil leakage especially in the low light environment.

An alternative treatment for anastomotic leakage after oesophageal resection

DEFF Research Database (Denmark)

Damm, P; Hoffmann, J.

1988-01-01

An alternative non-operative method for treatment for anastomotic leakage after oesophageal resection is presented. A mediastinal abscess cavity was drained by an ordinary nasogastric tube introduced via the nose through the anastomotic defect and into the cavity.......An alternative non-operative method for treatment for anastomotic leakage after oesophageal resection is presented. A mediastinal abscess cavity was drained by an ordinary nasogastric tube introduced via the nose through the anastomotic defect and into the cavity....

A precision analogue integrator system for heavy current measurement in MFDC resistance spot welding

International Nuclear Information System (INIS)

Xia, Yu-Jun; Zhang, Zhong-Dian; Xia, Zhen-Xin; Zhu, Shi-Liang; Zhang, Rui

2016-01-01

In order to control and monitor the quality of middle frequency direct current (MFDC) resistance spot welding (RSW), precision measurement of the welding current up to 100 kA is required, for which Rogowski coils are the only viable current transducers at present. Thus, a highly accurate analogue integrator is the key to restoring the converted signals collected from the Rogowski coils. Previous studies emphasised that the integration drift is a major factor that influences the performance of analogue integrators, but capacitive leakage error also has a significant impact on the result, especially in long-time pulse integration. In this article, new methods of measuring and compensating capacitive leakage error are proposed to fabricate a precision analogue integrator system for MFDC RSW. A voltage holding test is carried out to measure the integration error caused by capacitive leakage, and an original integrator with a feedback adder is designed to compensate capacitive leakage error in real time. The experimental results and statistical analysis show that the new analogue integrator system could constrain both drift and capacitive leakage error, of which the effect is robust to different voltage levels of output signals. The total integration error is limited within  ±0.09 mV s −1 0.005% s −1 or full scale at a 95% confidence level, which makes it possible to achieve the precision measurement of the welding current of MFDC RSW with Rogowski coils of 0.1% accuracy class. (paper)

Functions and requirements for single-shell tank leakage mitigation

International Nuclear Information System (INIS)

Cruse, J.M.

1994-01-01

This document provides the initial functions and requirements for the leakage mitigation mission applicable to past and potential future leakage from the Hanford Site's 149 single-shell high-level waste tanks. This mission is a part of the overall mission of the Westinghouse Hanford Company Tank Waste Remediation System division to remediate the tank waste in a safe and acceptable manner. Systems engineering principles are being applied to this effort. A Mission Analysis has been completed, this document reflects the next step in the systems engineering approach to decompose the mission into primary functions and requirements. The functions and requirements in this document apply to mitigative actions to be taken regarding below ground leaks from SST containment boundaries and the resulting soil contamination. Leakage mitigation is invoked in the TWRS Program in three fourth level functions: (1) Store Waste, (2) Retrieve Waste, and (3) Disposition Excess Facilities

On the Connection between Leakage Tolerance and Adaptive Security

DEFF Research Database (Denmark)

Nielsen, Jesper Buus; Venturi, Daniele; Zottarel, Angela

2013-01-01

We revisit the context of leakage-tolerant interactive protocols as defined by Bitanski, Canetti and Halevi (TCC 2012). Our contributions can be summarized as follows: For the purpose of secure message transmission, any encryption protocol with message space M and secret key space SK tolerating...... at the end of the protocol execution, if and only if the protocol has passive adaptive security against an adaptive corruption of one party at the end of the protocol execution. This shows that as soon as a little leakage is tolerated, one needs full adaptive security. In case more than one party can...... be corrupted, we get that leakage tolerance is equivalent to a weaker form of adaptivity, which we call semi-adaptivity. Roughly, a protocol has semi-adaptive security if there exist a simulator which can simulate the internal state of corrupted parties, however, such a state is not required...

Prevalence of extravertebral cement leakage after vertebroplasty: procedural documentation versus CT detection

International Nuclear Information System (INIS)

Martin, Douglas J.; Rad, Arash Ehteshami; Kallmes, David F.

2012-01-01

Background: Reported incidence of extravertebral cement leakage after vertebroplasty varies widely across studies. Purpose: To retrospectively compare the relative detection rates of extravertebral leakage noted under intra-procedural fluoroscopic surveillance, post procedure plain radiographs, and post procedure computed tomography (CT) in a cohort of patients undergoing vertebroplasty. Material and Methods: With IRB approval, we retrospectively identified 181 patients with 277 levels treated with percutaneous vertebroplasty among a total of 1255 patients undergoing vertebroplasty between 1999 and 2010 who had subsequently undergone a CT examination that included the treated level(s). Categories of leakage were paravertebral, end plate, epidural, and pre vertebral venous leakage. CT-detected leak rates were then compared to those noted on the vertebroplasty procedure reports and the archived fluoroscopic images for this same cohort using Pearson's χ 2 test. Results: One hundred and forty-nine (82%, 95% CI 76-87%) of 181 patients demonstrated evidence of some type of leakage on CT at one or more treated levels. Sixty-two (34 %, 95 % CI 28-42 %) and seventy-seven (50%, 95% CI 43-57%) of 149 CT-detected leaks were reported in the procedural dictation or detected on plain radiography (P 0.01 and 0.006, respectively). The most common type of leakage noted on CT was end plate (n = 81, 45%, 95% CI 38-52%), followed by paravertebral (n 64, 35%, 95% CI 29-43%), epidural (n = 36, 20%, 95% CI 15-26%), and pre vertebral venous (n = 32, 18%, 95% CI 13-24%). Conclusion: Cement leakage after vertebroplasty is common and is often not reported by operators in procedural dictations. CT detects substantially more leaks than plain radiography

Root cause evaluation of pressurizer relief valve leakage

International Nuclear Information System (INIS)

Olson, D.E.; Voll, B.J.

1996-01-01

Pressurizer relief valves at two pressurized water reactor units experienced unacceptable leakage during plant heatup. The leakage was suspected to be caused by excessive pipe loads on the valves. This paper describes how monitoring via hard-wired transducers and a digital data acquisition system was used to quantify the pipe loads on the valves, and assist in determining the root cause of the pipe loads and appropriate corrective actions. The selection of the parameters monitored, how the monitoring was accomplished and interpretation of the results is discussed. The corrective actions implemented based on the monitoring results are also discussed

Regulatory concerns for leakage testing of packagings with three O-ring closure seals

International Nuclear Information System (INIS)

Oras, J.J.; Towell, R.H.; Wangler, M.E.

1997-01-01

The American National Standard for Radioactive Materials--Leakage Tests on Packages for Shipment (ANSI N14.5) provides guidance for leakage rate testing to show that a particular packaging complies with regulatory requirements and also provides guidance in determining appropriate acceptance criteria. Recent radioactive packagings designs have incorporated three O-ring closure seals, the middle O-ring being the containment seal. These designs have the potential for false positive results of leakage rate tests. The volume between the containment O-ring and the inner O-ring is used for the helium gas required for the leakage rate tests to reduce both the amount of helium used and the time required to conduct the tests. A leak detector samples the evacuated volume between the outer O-ring and the containment O-ring. False positive results can be caused in two ways, a large leakage in the containment seal or leakage in the inner seal. This paper will describe the problem together with possible solutions/areas that need to be addressed in a Safety Analysis Report for Packagings before a particular packaging design can be certified for transport

The extent of on-site leakage in selected suburbs of Johannesburg ...

African Journals Online (AJOL)

This study investigated on-site leakage on 182 properties with relatively new municipal water meters in well-established suburbs of Johannesburg. A methodology was developed to estimate the on-site leakage rate from readings taken from these municipal water meters, which was then adjusted to account for metering ...

Method of detecting leakage in nuclear reactor containment vessel

International Nuclear Information System (INIS)

Koba, Akitoshi; Goto, Seiichiro.

1974-01-01

Object: To permit accurate and prompt detection of leakage of a radioactive substance. Structure: The rate of change of such factors as radiation dose, temperature and pressure in the containment vessel, and each detected rate of change is compared with a reference value. The running cycle of the condensed drain exhausting pump in a drain collecting tank within a predetermined period is detected, and it is also compared with a reference value. These comparisons determine the absence or presence of leakage. (Kamimura, M.)

A conservation planning approach to mitigate the impacts of leakage from protected area networks.

Science.gov (United States)

Bode, Michael; Tulloch, Ayesha I T; Mills, Morena; Venter, Oscar; Ando, Amy W

2015-06-01

Protected area networks are designed to restrict anthropogenic pressures in areas of high biodiversity. Resource users respond by seeking to replace some or all of the lost resources from locations elsewhere in the landscape. Protected area networks thereby perturb the pattern of human pressures by displacing extractive effort from within protected areas into the broader landscape, a process known as leakage. The negative effects of leakage on conservation outcomes have been empirically documented and modeled using homogeneous descriptions of conservation landscapes. Human resource use and biodiversity vary greatly in space, however, and a theory of leakage must describe how this heterogeneity affects the magnitude, pattern, and biodiversity impacts of leakage. We combined models of household utility, adaptive human foraging, and biodiversity conservation to provide a bioeconomic model of leakage that accounts for spatial heterogeneity. Leakage had strong and divergent impacts on the performance of protected area networks, undermining biodiversity benefits but mitigating the negative impacts on local resource users. When leakage was present, our model showed that poorly designed protected area networks resulted in a substantial net loss of biodiversity. However, the effects of leakage can be mitigated if they are incorporated ex-ante into the conservation planning process. If protected areas are coupled with nonreserve policy instruments such as market subsidies, our model shows that the trade-offs between biodiversity and human well-being can be further and more directly reduced. © 2014 Society for Conservation Biology.

Early detection of anastomotic leakage after elective low anterior resection.

Science.gov (United States)

Fouda, Elyamani; El Nakeeb, Ayman; Magdy, Alaa; Hammad, Enas A; Othman, Gamal; Farid, Mohamed

2011-01-01

Colorectal anastomotic leakage is a serious complication leading to major postoperative morbidity and mortality. In the present study, we investigated the early detection of anastomotic leakage before its clinical presentation. Fifty-six patients with rectal cancer were included prospectively in this study. All patients underwent elective low anterior resection. Peritoneal samples were collected from the abdominal drains at the first, third, and fifth days postoperatively for bacteriological study (quantitative cultures for both aerobes and anaerobes) and cytokines (IL-6, IL-10, TNF) measurement. Patients were divided into two groups: those without symptomatic or clinical evidence of anastomotic leakage (AL; group 1) and those with clinical evidence of AL (group 2). Study variables included hospital stay, wound infection, operative time, blood loss, height of anastomosis, intraperitoneal cytokines, and microbiological study of peritoneal fluid. Clinically evident AL occurred in eight patients (14.3%) and diagnosed postoperatively on median day 6. Intraperitoneal bacterial colonization and cytokine levels were significantly higher in patients with clinical evidence of AL. Wound infection was significantly higher in anastomotic leakage group. The hospital stay for the patients with anastomotic leakage was significantly longer than those without AL (14 ± 1.41 vs. 5.43 ± 0.89 days). A significant difference among two groups was observed regarding operative time, blood loss, blood transfusion, and height of the anastomosis. The peritoneal cytokines levels and intraperitoneal bacterial colonization might be an additional diagnostic tool that can support the decision making of surgeons for early detection of anastomotic leak in colorectal surgery.

Acoustic emission monitoring of leakage through seal-plug in PHWR systems

Energy Technology Data Exchange (ETDEWEB)

Jha, S K; Badgujar, B P; Goswami, G L [Bhabha Atomic Research Centre, Bombay (India). Atomic Fuels Div.; Patel, R J; Bhattacharya, S; Agrawal, R G [Bhabha Atomic Research Centre, Mumbai (India). Refuelling Technology Division

1994-12-31

Acoustic Emission (AE) technique is being developed as an in-service inspection tool for monitoring the leakage through seal-plugs in Pressurised Heavy Water Reactors (PHWRs). Time as well as frequency domain analysis have been utilised during the experiment carried out at Bhabha Atomic Research Centre (BARC) using test set up simulating the pressure and temperature conditions. The work involved were to determine the temperature profile on end-fitting, effect of pressure and temperature on leakage etc. This paper discusses various relationships like signal-level vs. pressure, frequency spectrum of signal, signal-level vs. leakage based on the above experimental work. (author). 4 refs., 6 figs.

Polarization leakage in epoch of reionization windows - II. Primary beam model and direction-dependent calibration

Science.gov (United States)

Asad, K. M. B.; Koopmans, L. V. E.; Jelić, V.; Ghosh, A.; Abdalla, F. B.; Brentjens, M. A.; de Bruyn, A. G.; Ciardi, B.; Gehlot, B. K.; Iliev, I. T.; Mevius, M.; Pandey, V. N.; Yatawatta, S.; Zaroubi, S.

2016-11-01

Leakage of diffuse polarized emission into Stokes I caused by the polarized primary beam of the instrument might mimic the spectral structure of the 21-cm signal coming from the epoch of reionization (EoR) making their separation difficult. Therefore, understanding polarimetric performance of the antenna is crucial for a successful detection of the EoR signal. Here, we have calculated the accuracy of the nominal model beam of Low Frequency ARray (LOFAR) in predicting the leakage from Stokes I to Q, U by comparing them with the corresponding leakage of compact sources actually observed in the 3C 295 field. We have found that the model beam has errors of ≤10 per cent on the predicted levels of leakage of ˜1 per cent within the field of view, I.e. if the leakage is taken out perfectly using this model the leakage will reduce to 10-3 of the Stokes I flux. If similar levels of accuracy can be obtained in removing leakage from Stokes Q, U to I, we can say, based on the results of our previous paper, that the removal of this leakage using this beam model would ensure that the leakage is well below the expected EoR signal in almost the whole instrumental k-space of the cylindrical power spectrum. We have also shown here that direction-dependent calibration can remove instrumentally polarized compact sources, given an unpolarized sky model, very close to the local noise level.

Investigations of leakage mechanisms and its influences on a micro swing engine considering rarefaction effects

International Nuclear Information System (INIS)

Zhou, Xiong; Zhang, Zhenyu; Kong, Wenjun; Du, Ning

2016-01-01

Highlights: • Mechanisms of the leakage flow in different flow regimes have been studied. • The leakage flow regime and patterns in the micro swing engine are presented. • Slip on the walls has a larger effect on leakage flow with decreasing the gap. • Rarefaction effects on the engine performance have been investigated. - Abstract: Considering rarefaction effects, this paper investigated mechanisms of the clearance leakage and its influences on a micro swing engine for the micro power generation by employing three different flow models named as discrete velocity direction (DVD) model, Navier-Stokes equations with slip boundary conditions (NS-slip) and no-slip boundary conditions (NS-no slip). Using the DVD model, this paper firstly studied leakage mechanisms of a micro Couette-Poisueille flow. Factors which control the leakage in different regimes were obtained. Furthermore, the system-level predictions of the clearance leakage in the micro swing engine have been conducted by solving the Navier-Stokes equations. The leakage flow regime, patterns and characteristics were presented. Results by NS-slip and NS-no slip were compared to study the rarefaction effects. Finally, investigations of the engine size and the gap height on the engine performance have been conducted. The significance of the leakage in different engine size regimes was presented, and the results show that rarefaction effects affect the indicated thermal efficiency greatly with the decrease of the engine size scale.

A method to investigate inter-aquifer leakage using hydraulics and multiple environmental tracers

Science.gov (United States)

Priestley, Stacey; Love, Andrew; Wohling, Daniel; Post, Vincent; Shand, Paul; Kipfer, Rolf; Tyroller, Lina

2016-04-01

Informed aquifer management decisions regarding sustainable yields or potential exploitation require an understanding of the groundwater system (Alley et al. 2002, Cherry and Parker 2004). Recently, the increase in coal seam gas (CSG) or shale gas production has highlighted the need for a better understanding of inter-aquifer leakage and contaminant migration. In most groundwater systems, the quantity or location of inter-aquifer leakage is unknown. Not taking into account leakage rates in the analysis of large scale flow systems can also lead to significant errors in the estimates of groundwater flow rates in aquifers (Love et al. 1993, Toth 2009). There is an urgent need for robust methods to investigate inter-aquifer leakage at a regional scale. This study builds on previous groundwater flow and inter-aquifer leakage studies to provide a methodology to investigate inter-aquifer leakage in a regional sedimentary basin using hydraulics and a multi-tracer approach. The methodology incorporates geological, hydrogeological and hydrochemical information in the basin to determine the likelihood and location of inter-aquifer leakage. Of particular benefit is the analysis of hydraulic heads and environmental tracers at nested piezometers, or where these are unavailable bore couplets comprising bores above and below the aquitard of interest within a localised geographical area. The proposed methodology has been successful in investigating inter-aquifer leakage in the Arckaringa Basin, South Australia. The suite of environmental tracers and isotopes used to analyse inter-aquifer leakage included the stable isotopes of water, radiocarbon, chloride-36, 87Sr/86Sr and helium isotopes. There is evidence for inter-aquifer leakage in the centre of the basin ~40 km along the regional flow path. This inter-aquifer leakage has been identified by a slight draw-down in the upper aquifer during pumping in the lower aquifer, overlap in Sr isotopes, δ2H, δ18O and chloride

Risk of acute anastomotic leakage after preoperative radiotherapy in rectal cancer

Directory of Open Access Journals (Sweden)

Devid Belalla

2016-11-01

Full Text Available Objective: To evaluate the preoperative radiotherapy and its role in anastomotic leakage. Methods: A total of 327 patients who had an anterior resection (AR in elective surgery for a rectal carcinoma were selected and operated in our clinic of surgery during the period from 2003 to 2015. Among them, 135 patients had a low anterior resection (LAR and the other 192 had an AR. This is a retrospective study. Chi-squared test was used to evaluate statistical differences and the P < 0.05 was considered statistically significant. Results: A total of 126 patients had radiotherapy before surgery, and 50 of them had a LAR. In the other 201 patients, surgery was the first treatment modality, and 83 of them had a LAR. We had an overall anastomotic leakage of 7.95% or 26% patients. Anastomotic leakage was found in 14 patients with LAR, 9 of which had radiotherapy before surgery. From the 12 patients with AR who had an anastomotic leakage, 6 of them had radiotherapy before surgery. Conclusions: Radiotherapy may affect anastomotic healing and increase the risk of leakage. This risk is higher in low anterior anastomoses where a protective stoma may be considered. A better evaluation and support for patients with preoperative radiotherapy is needed in order to diminish the concomitant risk factors as much as possible.

Control room habitability assessment and in-leakage test for Korean NPP - 15510

International Nuclear Information System (INIS)

Song, D.S.; Lee, J.B.; Ha, S.J.; Seong, J.J.

2015-01-01

The assessment of control room habitability for Wolsung unit 1 was performed based on GL 2003-01 and Reg. Guide 1.197. The control room habitability program including Control Room Envelope (CRE) in-leakage test procedures, self assessment guidance, CRE boundary control program, CRE maintenance/sealing program was developed for Wolsung unit 1. The integrated CRE test was performed utilizing ASTM E741. There are two operating modes of pressurization and isolation for CRE ventilation test, and four tests were performed using each of the control room HVAC sub-trains. The control room HVAC system lineup of pressurization mode test was based upon a lineup that encompassed the design basis radiological analyses. The other control room HVAC system lineup of isolation mode test was based on an operation mode that considers toxic gas. The in-leakage testing was performed in accordance with CRE in-leakage test procedures. In the pressurization mode, measured unfiltered in-leakage rates for train A and train B were 0 CFM and 405 CFM respectively. In the isolation mode, measured unfiltered in-leakage rates for train A and train B were 1,739 CFM and 1,502 CFM, respectively. Maximum concentration of ammonia at the control room HVAC intake is calculated to be 0.027 g/m 3 (39 ppm), and satisfied the toxicity limit of 300 ppm. The test result shows that the measured unfiltered in-leakage is bounded by the regulatory criteria assumed in the design basis radiological analyses. (authors)

Low leakage Ru-strontium titanate-Ru metal-insulator-metal capacitors for sub-20 nm technology node in dynamic random access memory

Energy Technology Data Exchange (ETDEWEB)

Popovici, M., E-mail: Mihaela.Ioana.Popovici@imec.be; Swerts, J.; Redolfi, A.; Kaczer, B.; Aoulaiche, M.; Radu, I.; Clima, S.; Everaert, J.-L.; Van Elshocht, S.; Jurczak, M. [Imec, Leuven 3001 (Belgium)

2014-02-24

Improved metal-insulator-metal capacitor (MIMCAP) stacks with strontium titanate (STO) as dielectric sandwiched between Ru as top and bottom electrode are shown. The Ru/STO/Ru stack demonstrates clearly its potential to reach sub-20 nm technology nodes for dynamic random access memory. Downscaling of the equivalent oxide thickness, leakage current density (J{sub g}) of the MIMCAPs, and physical thickness of the STO have been realized by control of the Sr/Ti ratio and grain size using a heterogeneous TiO{sub 2}/STO based nanolaminate stack deposition and a two-step crystallization anneal. Replacement of TiN with Ru as both top and bottom electrodes reduces the amount of electrically active defects and is essential to achieve a low leakage current in the MIM capacitor.

Monitoring device for radioactive leakage from steam system in nuclear power plant

International Nuclear Information System (INIS)

Ogawa, Tateo; Sato, Kohei

1988-01-01

Purpose: To improve the reliability for the monitor of radio-active leakage by accumulating small quantity of radioactivities each lower than the detectable level and increasing their dose rate. Constitution: Even if the steam system radiation monitor in the nuclear power plant is disposed for the detection of in-leak radioactivity, radioactive leakage can be monitored at high reliability by increasing the small quantity of radioactivities in the drains to a detectable sensitivity range of the monitor upon detection. In view of the above, in the present invention, radioactive material catching medium is incorporated to a radio-activity monitor spool piece for accumulating small quantity of radioactivities. Specifically as the catching medium, an ion exchange resin is used for the leakage of ionic radioactive material, while an ion exchange resin increased with the mixing ratio of a cationic resin or hollow thread membrane filter is used for crud-like radioactive material leakage. These catching media are incorporated into the spool piece, thereby enabling to catch even small quantity of radioactive leakage lower than the detectable sensitivity of the radiation monitor, if should occur, in the spool piece and enabling radioactive detection for the accumulated dose rate. (Horiuchi, T.)

Binding and leakage of barium in alginate microbeads.

Science.gov (United States)

Mørch, Yrr A; Qi, Meirigeng; Gundersen, Per Ole M; Formo, Kjetil; Lacik, Igor; Skjåk-Braek, Gudmund; Oberholzer, Jose; Strand, Berit L

2012-11-01

Microbeads of alginate crosslinked with Ca(2+) and/or Ba(2+) are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared with high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. To reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation. Copyright © 2012 Wiley Periodicals, Inc.

Leakage of CO2 from geologic storage: Role of secondaryaccumulation at shallow depth

Energy Technology Data Exchange (ETDEWEB)

Pruess, K.

2007-05-31

Geologic storage of CO2 can be a viable technology forreducing atmospheric emissions of greenhouse gases only if it can bedemonstrated that leakage from proposed storage reservoirs and associatedhazards are small or can be mitigated. Risk assessment must evaluatepotential leakage scenarios and develop a rational, mechanisticunderstanding of CO2 behavior during leakage. Flow of CO2 may be subjectto positive feedbacks that could amplify leakage risks and hazards,placing a premium on identifying and avoiding adverse conditions andmechanisms. A scenario that is unfavorable in terms of leakage behavioris formation of a secondary CO2 accumulation at shallow depth. This paperdevelops a detailed numerical simulation model to investigate CO2discharge from a secondary accumulation, and evaluates the role ofdifferent thermodynamic and hydrogeologic conditions. Our simulationsdemonstrate self-enhancing as well as self-limiting feedbacks.Condensation of gaseous CO2, 3-phase flow of aqueous phase -- liquid CO2-- gaseous CO2, and cooling from Joule-Thomson expansion and boiling ofliquid CO2 are found to play important roles in the behavior of a CO2leakage system. We find no evidence that a subsurface accumulation of CO2at ambient temperatures could give rise to a high-energy discharge, aso-called "pneumatic eruption."

Methane leakage in natural gas operations

International Nuclear Information System (INIS)

Jennervik, A.

1992-01-01

The world gas industry is efficient in conservation of natural gas within its systems. As the influence of methane as an infra-red absorbent gas has been more widely recognized, the considerations of methane's greenhouse effect has become vitally important to gas companies around the world. The industry is universally environmentally conscious. natural gas transmission and distribution companies want to maintain their image as suppliers of clean fuel. Further reductions in methane leakage --- particularly in older distribution systems --- can, should and will be pursued. Unfortunately, there has been little exchange of views on methane leakages between commentators on environmental matters and gas companies and organizations. There is absolutely no need for the industry to avoid the issue of greenhouse gases. Without industry involvement, the environmental debate concerning fossil fuels could lead to selective interpretation of scientific views and available evidence. Companies and authorities would be presented with confusing, contradictory evidence on which to base policy approaches and regulations

Leakage radiation spectroscopy of organic/dielectric/metal systems

DEFF Research Database (Denmark)

Fiutowski, Jacek; Kawalec, Tomasz; Kostiučenko, Oksana

2014-01-01

side of a hemisphere fused silica prism with an index matching liquid was illuminated under normal incidence by a He-Cd 325 nm laser. Two orthogonal linear polarizations were used both parallel and perpendicular to the detection plane. Spectrally resolved leakage radiation was observed on the opposite......Leakage radiation spectroscopy of organic para-Hexaphenylene (p-6P) molecules has been performed in the spectral range 420-675 nm which overlaps with the p-6P photoluminescence band. The p-6P was deposited on 40 nm silver (Ag) films on BK7 glass, covered with SiO2 layers. The SiO2 layer thickness...

A study on two phase flows of linear compressors for the prediction of refrigerant leakage

International Nuclear Information System (INIS)

Hwang, Il Sun; Lee, Young Lim; Oh, Won Sik; Park, Kyeong Bae

2015-01-01

Usage of linear compressors is on the rise due to their high efficiency. In this paper, leakage of a linear compressor has been studied through numerical analysis and experiments. First, nitrogen leakage for a stagnant piston with fixed cylinder pressure as well as for a moving piston with fixed cylinder pressure was analyzed to verify the validity of the two-phase flow analysis model. Next, refrigerant leakage of a linear compressor in operation was finally predicted through 3-dimensional unsteady, two phase flow CFD (Computational fluid dynamics). According to the research results, the numerical analyses for the fixed cylinder pressure models were in good agreement with the experimental results. The refrigerant leakage of the linear compressor in operation mainly occurred through the oil exit and the leakage became negligible after about 0.4s following operation where the leakage became lower than 2.0x10 -4 kg/s.

Investigation of pool thermal hydraulics and temperature distribution in inner vessel under mechanical seal leakage

International Nuclear Information System (INIS)

Abraham, Juby; Velusamy, K.; Selvaraj, P.

2015-01-01

The primary heat sink of prototype fast breeder reactor is a sodium pool which is partitioned into cold pool and hot pool. The inner vessel which separates the cold and hot pools is having penetrations for intermediate heat exchangers. The hot sodium from hot pool leaks into the cold pool through these penetrations and to reduce the leakage, mechanical seals are provided. Leakage of hot sodium into cold pool can lead to thermal stratification in the cold pool and also will affect the temperature distribution in inner vessel. 3-D CFD studies were performed focusing these features as a function of sodium leakage. The analyses indicate that the maximum temperature difference across the IV thickness is 65°C without any leakage of sodium. The temperature difference is found to decrease with increase in leakage through the seals. It is seen that a leakage of 2.5% is acceptable. (author)

Detection and quantification of methane leakage from landfills

Energy Technology Data Exchange (ETDEWEB)

Ljungberg, Sven-Aake; Maartensson, Stig-Goeran (Univ. of Gaevle, Gaevle (Sweden)); Meijer, Jan-Erik; Rosqvist, Haakan (NSR AB, Helsingborg (Sweden))

2009-03-15

The purpose of this project was to detect gas leakage and to measure and quantify methane emission from landfills using modern remote sensing techniques. In this project, a handheld laser instrument and an IR camera were used. The overall objective was to develop cost-effective methods for detecting and quantifying methane emissions from landfills. There are many methods available for measuring the methane concentration in air, both from close-up and from long distances. Combined with the use of a tracer gas, the methane emission from entire landfills can be measured relatively accurately. A number of methods are used to detect leakage from parts of landfill surfaces, but there are few methods for quantifying leakage from sub-zones. Field measurements with the laser instrument and the IR camera were carried out at seven Swedish landfills and two landfills in France. The investigated surfaces at the Swedish landfills were divided into different zones, such as top surface, slope, crest and toe of slope. The field measurements in France were taken over entire landfills. The methane emission varied between the different landfills in the project, and also between the different landfill zones. The results from repeated field measurements indicated that a landfill with a final cap and a successful gas recovery system produces barely measurable emissions. The weak points at a landfill are generally slopes, including crests and toes of slopes. Where the covering of the waste is inadequate, leakage often occurs at lift joints and in areas where waste protrudes through the cover. Other weak points are deficiencies in the gas recovery system. Leachate systems can lead landfill gas and thereby cause methane leakage. Along with wind velocity and variations in atmospheric pressure, moisture content in the ground is an important factor that affects methane emissions from landfill surfaces. Results from field measurements of the same feature/surface at different points in time and

Evidence for paternal leakage in hybrid periodical cicadas (Hemiptera: Magicicada spp..

Directory of Open Access Journals (Sweden)

Kathryn M Fontaine

2007-09-01

Full Text Available Mitochondrial inheritance is generally assumed to be maternal. However, there is increasing evidence of exceptions to this rule, especially in hybrid crosses. In these cases, mitochondria are also inherited paternally, so "paternal leakage" of mitochondria occurs. It is important to understand these exceptions better, since they potentially complicate or invalidate studies that make use of mitochondrial markers. We surveyed F1 offspring of experimental hybrid crosses of the 17-year periodical cicadas Magicicada septendecim, M. septendecula, and M. cassini for the presence of paternal mitochondrial markers at various times during development (1-day eggs; 3-, 6-, 9-week eggs; 16-month old 1st and 2nd instar nymphs. We found evidence of paternal leakage in both reciprocal hybrid crosses in all of these samples. The relative difficulty of detecting paternal mtDNA in the youngest eggs and ease of detecting leakage in older eggs and in nymphs suggests that paternal mitochondria proliferate as the eggs develop. Our data support recent theoretical predictions that paternal leakage may be more common than previously estimated.

Evidence for paternal leakage in hybrid periodical cicadas (Hemiptera: Magicicada spp.).

Science.gov (United States)

Fontaine, Kathryn M; Cooley, John R; Simon, Chris

2007-09-12

Mitochondrial inheritance is generally assumed to be maternal. However, there is increasing evidence of exceptions to this rule, especially in hybrid crosses. In these cases, mitochondria are also inherited paternally, so "paternal leakage" of mitochondria occurs. It is important to understand these exceptions better, since they potentially complicate or invalidate studies that make use of mitochondrial markers. We surveyed F1 offspring of experimental hybrid crosses of the 17-year periodical cicadas Magicicada septendecim, M. septendecula, and M. cassini for the presence of paternal mitochondrial markers at various times during development (1-day eggs; 3-, 6-, 9-week eggs; 16-month old 1st and 2nd instar nymphs). We found evidence of paternal leakage in both reciprocal hybrid crosses in all of these samples. The relative difficulty of detecting paternal mtDNA in the youngest eggs and ease of detecting leakage in older eggs and in nymphs suggests that paternal mitochondria proliferate as the eggs develop. Our data support recent theoretical predictions that paternal leakage may be more common than previously estimated.

Integrating Flexible Sensor and Virtual Self-Organizing DC Grid Model With Cloud Computing for Blood Leakage Detection During Hemodialysis.

Science.gov (United States)

Huang, Ping-Tzan; Jong, Tai-Lang; Li, Chien-Ming; Chen, Wei-Ling; Lin, Chia-Hung

2017-08-01

Blood leakage and blood loss are serious complications during hemodialysis. From the hemodialysis survey reports, these life-threatening events occur to attract nephrology nurses and patients themselves. When the venous needle and blood line are disconnected, it takes only a few minutes for an adult patient to lose over 40% of his / her blood, which is a sufficient amount of blood loss to cause the patient to die. Therefore, we propose integrating a flexible sensor and self-organizing algorithm to design a cloud computing-based warning device for blood leakage detection. The flexible sensor is fabricated via a screen-printing technique using metallic materials on a soft substrate in an array configuration. The self-organizing algorithm constructs a virtual direct current grid-based alarm unit in an embedded system. This warning device is employed to identify blood leakage levels via a wireless network and cloud computing. It has been validated experimentally, and the experimental results suggest specifications for its commercial designs. The proposed model can also be implemented in an embedded system.

Pipeline leakage recognition based on the projection singular value features and support vector machine

Energy Technology Data Exchange (ETDEWEB)

Liang, Wei; Zhang, Laibin; Mingda, Wang; Jinqiu, Hu [College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing, (China)

2010-07-01

The negative wave pressure method is one of the processes used to detect leaks on oil pipelines. The development of new leakage recognition processes is difficult because it is practically impossible to collect leakage pressure samples. The method of leakage feature extraction and the selection of the recognition model are also important in pipeline leakage detection. This study investigated a new feature extraction approach Singular Value Projection (SVP). It projects the singular value to a standard basis. A new pipeline recognition model based on the multi-class Support Vector Machines was also developed. It was found that SVP is a clear and concise recognition feature of the negative pressure wave. Field experiments proved that the model provided a high recognition accuracy rate. This approach to pipeline leakage detection based on the SVP and SVM has a high application value.

Development of Wireless System for Containment Integrated Leakage Rate Test

International Nuclear Information System (INIS)

Lee, Kwang-Dae; Oh, Eung-Se; Yang, Seung-Ok

2006-01-01

The containment system leakage rate should be estimated periodically with reliable test equipment. In light-water reactor nuclear power plants, ANSI/ANS- 56.8 is a basis for determining leakage rates. Two types of data acquisition system, centralized type and networked type, has been used. In centralized type, all sensors are connected directly from sensors in the containment to the measuring equipment outside the building. The other hand, the networked type has several branch chains which connect one group of the network-sensors together. To test leakage rate, more than 20 temperature sensors and 6 humidity sensors, which are different for each plant, should be installed on a specific level in the containment. A wireless technology gives the benefits such as reducing installation efforts, making pretest easy, so it is widely used more and more in the plant monitoring. As the containment system has many kinds of complex barriers to the radio frequency, the radio power and frequency band for better transmission rate as well as the interference by the radio frequency should be considered. The overview of the wireless sensor system for the containment leakage rate test is described here and the test results on Yonggwang unit 4 PWR plant is presented

Risk factors for leakage following intestinal anastomosis in dogs and cats: 115 cases (1991-2000).

Science.gov (United States)

Ralphs, S Christopher; Jessen, Carl R; Lipowitz, Alan J

2003-07-01

To identify factors associated with leakage following intestinal anastomosis in dogs and cats. Retrospective study. 90 dogs and 25 cats. Medical records of all dogs and cats that underwent intestinal resection and anastomosis between 1991 and 2000 were reviewed, and information on 27 factors was recorded. Anastomotic leakage was identified in 13 of the 90 dogs but in none of the 25 cats. Preoperative factors significantly associated with development of anastomotic leakage in dogs included preoperative peritonitis, serum albumin concentration, a left shift, and indication for surgery (dogs with intestinal foreign bodies were more likely to have leakage than dogs that underwent surgery for any other cause). Postoperative and case management factors significantly associated with development of leakage included duration of hospitalization, supplemental alimentation, whether the dog ate the day after surgery, blood product administration, and outcome (died vs survived). Discriminant analysis was performed, and dogs with 2 or more of the following factors were predicted to develop anastomotic leakage: preoperative peritonitis, intestinal foreign body, and serum albumin concentration dogs. Results suggest that a variety of factors may be associated with development of intestinal anastomotic leakage in dogs. In particular, dogs with 2 or more of the following risk factors are predicted to be at high risk for developing anastomotic leakage: preoperative peritonitis, intestinal foreign body, and serum albumin concentration < or = 2.5 g/dL.