Deterioration of mechanical properties of high strength structural steel S460N under transient state fire condition

International Nuclear Information System (INIS)

Qiang, Xuhong; Bijlaard, Frans S.K.; Kolstein, Henk

2012-01-01

Highlights: ► Mechanical properties of S460N under transient state fire condition are obtained. ► Elevated-temperature mechanical properties of steels are dependent on steel grades. ► No design standard is applicable to HSS S460N under transient state fire condition. ► Specific statements on various HSS in fire should be proposed in design standards. ► Research results offer accurate material property for structural design engineers. -- Abstract: 911 World Trade Centre Tragedy put fire safety of constructional steel structures into question. Since then, more and more research attention has been paid to the elevated-temperature mechanical properties of structural steels, which is a critical basis of evaluating the fire performance of steel structures. In the literature the available mechanical properties of structural steels under fire conditions were mainly obtained from steady state test method, as steady state test method is easier to perform than transient state test method and offers stress–strain curves directly. However, the transient state fire condition is considered to be more realistic to represent the real condition when constructions are exposed to fire. In order to reveal the deterioration of mechanical properties of the commonly used high strength structural steel S460N under transient state fire condition, tensile tests were conducted under various constant stress levels up to 800 MPa. The reduction factors of elastic modulus, yield and ultimate strengths of S460N under transient state fire condition were obtained and compared with current leading design standards and available literature. The application of such accurate elevated-temperature mechanical properties reduction factors of S460N can ensure a safe fire-resistance design and evaluation of steel structures with high strength steel S460N under transient state fire condition. This experimental study also supports other relative research on fire performance of steel structures with

Constant-resistance deep-level transient spectroscopy in Si and Ge JFET's

International Nuclear Information System (INIS)

Kolev, P.V.; Deen, J.

1999-01-01

The recently introduced constant-resistance deep-level transient spectroscopy (CR-DLTS) was successfully applied to study virgin and radiation-damaged junction field-effect transistors (JFET's). The authors have studied three groups of devices: commercially available-discrete silicon JFET's; virgin and exposed to high-level neutron radiation silicon JFET's, custom-made by using a monolithic technology; and commercially available discrete germanium p-channel JFET's. CR-DLTS is similar to both the conductance DLTs and to the constant-capacitance variation (CC-DLTS). Unlike the conductance and current DLTS, it is independent of the transistor size and does not require simultaneous measurement of the transconductance or the free-carrier mobility for calculation of the trap concentration. Compared to the CC-DLTS, it measures only the traps inside the gate-controlled part of the space charge region. Comparisons have also been made with the CC-DLTS and standard capacitance DLTS. In addition, possibilities for defect profiling in the channel have been demonstrated. CR-DLTS was found to be a simple, very sensitive, and device area-independent technique which is well suited for measurement of a wide range of deep level concentrations in transistors

Kinetics of non-equilibrium carries in high-resistance materials

International Nuclear Information System (INIS)

Arkhipov, V.I.; Rudenko, A.I.

1979-01-01

The kinetics of equilibrium carriers of high-resistance material samples is analytically studied to investigate and control the parameters and properties of these materials. Nonequilibrium carriers were generated by electron beam in these samples near by one of the contacts. The carrier drift causes the transient current. The study of it permits to make a conclusion about carrier mobility, their capture and release times and also about zone structure of material. Both the model taking into account energy-level transitions and the model taking into account the conduction zone interaction with local energy- level are shown to have features of anomalous behaviour

Effects of multiple resistive shells and transient electromagnetic torque on the dynamics of mode locking in reversed field pinch plasmas

International Nuclear Information System (INIS)

Guo, S.C.; Chu, M.S.

2002-01-01

The effects of multiple resistive shells and transient electromagnetic torque on the dynamics of mode locking in the reversed field pinch (RFP) plasmas are studied. Most RFP machines are equipped with one or more metal shells outside of the vacuum vessel. These shells have finite resistivities. The eddy currents induced in each of the shells contribute to the braking electromagnetic (EM) torque which slows down the plasma rotation. In this work we study the electromagnetic torque acting on the plasma (tearing) modes produced by a system of resistive shells. These shells may consist of several nested thin shells or several thin shells enclosed within a thick shell. The dynamics of the plasma mode is investigated by balancing the EM torque from the resistive shells with the plasma viscous torque. Both the steady state theory and the time-dependent theory are developed. The steady state theory is shown to provide an accurate account of the resultant EM torque if (dω/dt)ω -2 <<1 and the time scale of interest is much longer than the response (L/R) time of the shell. Otherwise, the transient theory should be adopted. As applications, the steady state theory is used to evaluate the changes of the EM torque response from the resistive shells in two variants of two RFP machines: (1) modification from Reversed Field Experiment (RFX) [Gnesotto et al., Fusion Eng. Des. 25, 335 (1995)] to the modified RFX: both of them are equipped with one thin shell plus one thick shell; (2) modification from Extrap T2 to Extrap T2R [Brunsell et al., Plasma Phys. Controlled Fusion 43, 1457 (2001)]: both of them are equipped with two thin shells. The transient theory has been applied numerically to study the time evolution of the EM torque during the unlocking of a locked tearing mode in the modified RFX

Discussion on Design Transients of Pebble-bed High Temperature Gas-cooled Reactor

International Nuclear Information System (INIS)

Wang Yan; Li Fu; Zheng Yanhua

2014-01-01

In order to assure high quality for the components and their supports in the reactor coolant system, etc., some thermal-hydraulic transient conditions will be selected and researched for equipment design evaluation to satisfy the requirements ASME code, which are based on the conservative estimates of the magnitude and frequency of the temperature and pressure transients resulting from various operating conditions in the plant. In the mature design on pressurized water reactor, five conditions are considered. For the developing advanced pebble-bed high temperature gas-cooled reactor(HTGR), its design and operation has much difference with other reactors, so the transients of the pebble-bed high temperature gas-cooled reactor have distinctive characteristics. In this paper, the possible design transients of the pebble-bed HTGR will be discussed, and the frequency of design transients for equipment fatigue analysis and stress analysis due to cyclic stresses is also studied. The results will provide support for the design and construct of the pebble-bed HTGR. (author)

High energy transients: The millisecond domain

Science.gov (United States)

Rao, A. R.

2018-02-01

The search for high energy transients in the millisecond domain has come to the focus in recent times due to the detection of gravitational wave events and the identification of fast radio bursts as cosmological sources. Here we highlight the sensitivity limitations in the currently operating hard X-ray telescopes and give some details of the search for millisecond events in the AstroSat CZT Imager data.

ELOCA: fuel element behaviour during high temperature transients

International Nuclear Information System (INIS)

Sills, H.E.

1979-03-01

The ELOCA computer code was developed to simulate the uniform thermal-mechanical behaviour of a fuel element during high-temperature transients such as a loss-of-coolant accident (LOCA). Primary emphasis is on the diametral expansion of the fuel sheath. The model assumed is a single UO2/zircaloy-clad element with axisymmetric properties. Physical effects considered by the code are fuel expansion, cracking and melting; variation, during the transient, of internal gas pressure; changing fuel/sheath heat transfer; thermal, elastic and plastic sheath deformation (anisotropic); Zr/H 2 O chemical reaction effects; and beryllium-assisted crack penetration of the sheath. (author)

A study on heat resistance of high temperature resistant coating

Energy Technology Data Exchange (ETDEWEB)

Zhang, Liping; Wang, Xueying; Zhang, Qibin; Qin, Yanlong; Lin, Zhu [Research Institute of Engineering Technology of CNPC, Tianjin (China)

2005-04-15

A high temperature resistant coating has been developed, which is mainly for heavy oil production pipes deserved the serious corrosion. The coating has excellent physical and mechanical performance and corrosion resistance at room and high temperature. In order to simulate the underground working condition of heavy oil pipes,the heat resistance of the high temperature resistant coating has been studied. The development and a study on the heat resistance of the DHT high temperature resistance coating have been introduced in this paper

A study on heat resistance of high temperature resistant coating

International Nuclear Information System (INIS)

Zhang, Liping; Wang, Xueying; Zhang, Qibin; Qin, Yanlong; Lin, Zhu

2005-01-01

A high temperature resistant coating has been developed, which is mainly for heavy oil production pipes deserved the serious corrosion. The coating has excellent physical and mechanical performance and corrosion resistance at room and high temperature. In order to simulate the underground working condition of heavy oil pipes,the heat resistance of the high temperature resistant coating has been studied. The development and a study on the heat resistance of the DHT high temperature resistance coating have been introduced in this paper

Recrystallization and grain growth induced by ELMs-like transient heat loads in deformed tungsten samples

Science.gov (United States)

Suslova, A.; El-Atwani, O.; Sagapuram, D.; Harilal, S. S.; Hassanein, A.

2014-11-01

Tungsten has been chosen as the main candidate for plasma facing components (PFCs) due to its superior properties under extreme operating conditions in future nuclear fusion reactors such as ITER. One of the serious issues for PFCs is the high heat load during transient events such as ELMs and disruption in the reactor. Recrystallization and grain size growth in PFC materials caused by transients are undesirable changes in the material, since the isotropic microstructure developed after recrystallization exhibits a higher ductile-to-brittle transition temperature which increases with the grain size, a lower thermal shock fatigue resistance, a lower mechanical strength, and an increased surface roughening. The current work was focused on careful determination of the threshold parameters for surface recrystallization, grain growth rate, and thermal shock fatigue resistance under ELM-like transient heat events. Transient heat loads were simulated using long pulse laser beams for two different grades of ultrafine-grained tungsten. It was observed that cold rolled tungsten demonstrated better power handling capabilities and higher thermal stress fatigue resistance compared to severely deformed tungsten. Higher recrystallization threshold, slower grain growth, and lower degree of surface roughening were observed in the cold rolled tungsten.

Investigation of the oxygen-vacancy (A-center) defect complex profile in neutron irradiated high resistivity silicon junction particle detectors

International Nuclear Information System (INIS)

Li, Zheng; Kraner, H.W.; Verbitskaya, E.; Eremin, V.; Ivanov, A.; Rubinelli, F.A.; Fonash, S.J.

1992-02-01

Distributions of the A-center (oxygen-vacancy) in neutron silicon detectors have been studied using Deep Level Transient Spectroscopy. A-centers have been found to be nearly uniformly distributed in the silicon water depth for medium resistivity (0.1 - 0.2 kΩ-cm) silicon detectors. A positive filling pulse was needed to detect the A-centers in high resistivity (>4 kΩ-cm) silicon detectors, and this effect was found to be dependent on the oxidation temperature. A discussion of this effect is presented. 16 refs

RF control at transient beamloading for high-duty-factor linacs

Energy Technology Data Exchange (ETDEWEB)

Chernogubovsky, M.A.; Sugimoto, Masayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-08-01

An effective RF control with the transient beamloading is the major issue in the operation of the high-duty-factor linacs to suppress the undesirable beam loss. The RF control method is considered to obtain the control principle and the state equation, under the analysis of electrodynamical properties of the excitation in the resonator of the linac due to the transient beamloading. The concept of the directional selective coupling is applied for the RF system to define the main characteristics and to optimize the RF control parameters. (author)

Modeling of transient ionizing radiation effects in bipolar devices at high dose-rates

International Nuclear Information System (INIS)

FJELDLY, T.A.; DENG, Y.; SHUR, M.S.; HJALMARSON, HAROLD P.; MUYSHONDT, ARNOLDO

2000-01-01

To optimally design circuits for operation at high intensities of ionizing radiation, and to accurately predict their a behavior under radiation, precise device models are needed that include both stationary and dynamic effects of such radiation. Depending on the type and intensity of the ionizing radiation, different degradation mechanisms, such as photoelectric effect, total dose effect, or single even upset might be dominant. In this paper, the authors consider the photoelectric effect associated with the generation of electron-hole pairs in the semiconductor. The effects of low radiation intensity on p-II diodes and bipolar junction transistors (BJTs) were described by low-injection theory in the classical paper by Wirth and Rogers. However, in BJTs compatible with modem integrated circuit technology, high-resistivity regions are often used to enhance device performance, either as a substrate or as an epitaxial layer such as the low-doped n-type collector region of the device. Using low-injection theory, the transient response of epitaxial BJTs was discussed by Florian et al., who mainly concentrated on the effects of the Hi-Lo (high doping - low doping) epilayer/substrate junction of the collector, and on geometrical effects of realistic devices. For devices with highly resistive regions, the assumption of low-level injection is often inappropriate, even at moderate radiation intensities, and a more complete theory for high-injection levels was needed. In the dynamic photocurrent model by Enlow and Alexander. p-n junctions exposed to high-intensity radiation were considered. In their work, the variation of the minority carrier lifetime with excess carrier density, and the effects of the ohmic electric field in the quasi-neutral (q-n) regions were included in a simplified manner. Later, Wunsch and Axness presented a more comprehensive model for the transient radiation response of p-n and p-i-n diode geometries. A stationary model for high-level injection in p

Asteroids in the High Cadence Transient Survey

Science.gov (United States)

Peña, J.; Fuentes, C.; Förster, F.; Maureira, J. C.; San Martín, J.; Littín, J.; Huijse, P.; Cabrera-Vives, G.; Estévez, P. A.; Galbany, L.; González-Gaitán, S.; Martínez, J.; de Jaeger, Th.; Hamuy, M.

2018-03-01

We report on the serendipitous observations of solar system objects imaged during the High cadence Transient Survey 2014 observation campaign. Data from this high-cadence wide-field survey was originally analyzed for finding variable static sources using machine learning to select the most-likely candidates. In this work, we search for moving transients consistent with solar system objects and derive their orbital parameters. We use a simple, custom motion detection algorithm to link trajectories and assume Keplerian motion to derive the asteroid’s orbital parameters. We use known asteroids from the Minor Planet Center database to assess the detection efficiency of the survey and our search algorithm. Trajectories have an average of nine detections spread over two days, and our fit yields typical errors of {σ }a∼ 0.07 {au}, σ e ∼ 0.07 and σ i ∼ 0.°5 in semimajor axis, eccentricity, and inclination, respectively, for known asteroids in our sample. We extract 7700 orbits from our trajectories, identifying 19 near-Earth objects, 6687 asteroids, 14 Centaurs, and 15 trans-Neptunian objects. This highlights the complementarity of supernova wide-field surveys for solar system research and the significance of machine learning to clean data of false detections. It is a good example of the data-driven science that Large Synoptic Survey Telescope will deliver.

EBR-II high-ramp transients under computer control

International Nuclear Information System (INIS)

Forrester, R.J.; Larson, H.A.; Christensen, L.J.; Booty, W.F.; Dean, E.M.

1983-01-01

During reactor run 122, EBR-II was subjected to 13 computer-controlled overpower transients at ramps of 4 MWt/s to qualify the facility and fuel for transient testing of LMFBR oxide fuels as part of the EBR-II operational-reliability-testing (ORT) program. A computer-controlled automatic control-rod drive system (ACRDS), designed by EBR-II personnel, permitted automatic control on demand power during the transients

A strategy to unveil transient sources of ultra-high-energy cosmic rays

Directory of Open Access Journals (Sweden)

Takami Hajime

2013-06-01

Full Text Available Transient generation of ultra-high-energy cosmic rays (UHECRs has been motivated from promising candidates of UHECR sources such as gamma-ray bursts, flares of active galactic nuclei, and newly born neutron stars and magnetars. Here we propose a strategy to unveil transient sources of UHECRs from UHECR experiments. We demonstrate that the rate of UHECR bursts and/or flares is related to the apparent number density of UHECR sources, which is the number density estimated on the assumption of steady sources, and the time-profile spread of the bursts produced by cosmic magnetic fields. The apparent number density strongly depends on UHECR energies under a given rate of the bursts, which becomes observational evidence of transient sources. It is saturated at the number density of host galaxies of UHECR sources. We also derive constraints on the UHECR burst rate and/or energy budget of UHECRs per source as a function of the apparent source number density by using models of cosmic magnetic fields. In order to obtain a precise constraint of the UHECR burst rate, high event statistics above ∼ 1020 eV for evaluating the apparent source number density at the highest energies and better knowledge on cosmic magnetic fields by future observations and/or simulations to better estimate the time-profile spread of UHECR bursts are required. The estimated rate allows us to constrain transient UHECR sources by being compared with the occurrence rates of known energetic transient phenomena.

Thermonuclear model for high energy transients

International Nuclear Information System (INIS)

Woosley, S.E.

1982-01-01

The thermonuclear model for x- and γ-ray bursts is discussed. Different regimes of nuclear burning are reviewed, each appropriate to a given range of (steady state) accretion rate. Accretion rates in the range 10 -14 to 10 -8 Msub solar y -1 all appear capable of producing x-ray transients of various durations and intervals. Modifications introduced by radiatively driven mass loss, the thermal inertia of the envelope, different burning mechanisms, and two-dimensional considerations are discussed as are difficulties encountered when the thermonuclear model is confronted with observations of rapidly recurrent bursts (less than or equal to 10 min), and super-Eddington luminosities and temperatures. Results from a numerical simulation of a combined hydrogen-helium runaway initiated at pycnonuclear density are presented for the first time. The thermonuclear model for γ-ray bursts is also reviewed and updated, particularly with regard to the breakdown of the steady state hypothesis employed in previous work. Solely on the basis of nuclear instability, γ-ray bursts of various types appear possible for a very broad variety of accretion rates (approx. 10 -17 to approx. 10 -11 Msub solar y -1 ) although other considerations may restrict this range. The thermonuclear model appears capable of yielding a great diversity of high energy transient phenomena for various accretion rates, magnetic field configurations, and neutron star envelope histories

Absence of transient elevated uv resistance during germination of Bacillus subtilis spores lacking small, acid-soluble spore proteins α and β

International Nuclear Information System (INIS)

Setlow, B.; Setlow, P.

1988-01-01

Dormant spores of various Bacillus species are much more resistant to UV irradiation than are the corresponding vegetative cells. This elevated spore UV resistance appears to have two causes. First, UV irradiation of spores does not produce the pyrimidine dimers formed in vegetative-cell DNA, but rather produces several other photoproducts, the most predominant of which is termed the spore photoproduct, a 5-thyminyl-5,6-dihydrothymine adduct (1, 10). Second, spores have at least two mechanisms which efficiently repair this spore photoproduct during spore germination, including one which monomerizes the adduct back to two thymines. This study shows that germinating spores of bacillus subtilis mutants which lack small, acid-soluble spore proteins α and β did not exhibit the transient elevated UV resistance seen during germination of wild-type spores

Transient analysis for alternating over-current characteristics of HTSC power transmission cable

Science.gov (United States)

Lim, S. H.; Hwang, S. D.

2006-10-01

In this paper, the transient analysis for the alternating over-current distribution in case that the over-current was applied for a high-TC superconducting (HTSC) power transmission cable was performed. The transient analysis for the alternating over-current characteristics of HTSC power transmission cable with multi-layer is required to estimate the redistribution of the over-current between its conducting layers and to protect the cable system from the over-current in case that the quench in one or two layers of the HTSC power cable happens. For its transient analysis, the resistance generation of the conducting layers for the alternating over-current was reflected on its equivalent circuit, based on the resistance equation obtained by applying discrete Fourier transform (DFT) for the voltage and the current waveforms of the HTSC tape, which comprises each layer of the HTSC power transmission cable. It was confirmed through the numerical analysis on its equivalent circuit that after the current redistribution from the outermost layer into the inner layers first happened, the fast current redistribution between the inner layers developed as the amplitude of the alternating over-current increased.

Chronic Iron Limitation Confers Transient Resistance to Oxidative Stress in Marine Diatoms.

Science.gov (United States)

Graff van Creveld, Shiri; Rosenwasser, Shilo; Levin, Yishai; Vardi, Assaf

2016-10-01

Diatoms are single-celled, photosynthetic, bloom-forming algae that are responsible for at least 20% of global primary production. Nevertheless, more than 30% of the oceans are considered "ocean deserts" due to iron limitation. We used the diatom Phaeodactylum tricornutum as a model system to explore diatom's response to iron limitation and its interplay with susceptibility to oxidative stress. By analyzing physiological parameters and proteome profiling, we defined two distinct phases: short-term (chronic (>5 d, phase II) iron limitation. While at phase I no significant changes in physiological parameters were observed, molecular markers for iron starvation, such as Iron Starvation Induced Protein and flavodoxin, were highly up-regulated. At phase II, down-regulation of numerous iron-containing proteins was detected in parallel to reduction in growth rate, chlorophyll content, photosynthetic activity, respiration rate, and antioxidant capacity. Intriguingly, while application of oxidative stress to phase I and II iron-limited cells similarly oxidized the reduced glutathione (GSH) pool, phase II iron limitation exhibited transient resistance to oxidative stress, despite the down regulation of many antioxidant proteins. By comparing proteomic profiles of P. tricornutum under iron limitation and metatranscriptomic data of an iron enrichment experiment conducted in the Pacific Ocean, we propose that iron-limited cells in the natural environment resemble the phase II metabolic state. These results provide insights into the trade-off between optimal growth rate and susceptibility to oxidative stress in the response of diatoms to iron quota in the marine environment. © 2016 American Society of Plant Biologists. All Rights Reserved.

Investigations of anticipated transients without scram (ATWS) for the high temperature reactor

International Nuclear Information System (INIS)

Heckhoff, H.D.

1981-10-01

In this study anticipated transients without scram (ATWS) are investigated for the high temperature reactor, especially for the thorium high temperature reactor (THTR) 300 MWe as an example. It is shown that the two ATWS 'feedwater flow reduction from full power' and 'positive reactivity insertion of 1 mNile/s from 40 per cent power' are the most important transients for the THTR. The additional load caused by the ATWS can be reduced sufficiently by some small modifications of the afterheat removal system. Supplementary precautions are not necessary. In the last part of this study some possibilities to improve the behaviour of the power plant are shown with regard to high temperature reactors of the future, the partial scram as well as some modifications of heating and cooling of the steam generator. (orig.) [de

Performance of high burned PWR fuel during transient

International Nuclear Information System (INIS)

Yanagisawa, Kazuaki; Fujishiro, Toshio

1992-01-01

In a majority of Japanese light water type commercial powder reactors (LWRs), UO 2 pellet sheathed by zircaloy cladding is used. Licensed discharged burn-up of the PWR fuel rod is going to be increased from 39 MWd/kgU to 48 MWd/kgU. This requests the increased reliability of cladding material as a strong barrier against fission product (FP). A long time usage in the neutron field and in the high temperature coolant will cause the zircaloy hardening and embrittlement. The cladding material is also degraded by waterside corrosion. These degradations are enhanced much by increased burn-up. A increased magnitude of the pellet-cladding mechanical interaction (PCMI) is of importance for increasing the stress of cladding material. In addition, aggressive FPs released from the fuel tends to attack the cladding material to cause stress corrosion cracking (SCC). At the Nuclear Safety Research Reactor (NSRR) in JAERI, 14 x 14 PWR type fuel rods preirradiation up to 42 MWd/kgU was prepared for the transient pulse irradiation under the simulated reactivity initiated accident (RIA) conditions. This will cause a prompt increase of the fuel temperature and stress on the highly burned cladding material. In the present paper, steady-state and transient behavior observed from the tested PWR fuel rod and calculational results obtained from the computer code FPRETAIN will be described. (author)

Transient analyzer

International Nuclear Information System (INIS)

Muir, M.D.

1975-01-01

The design and design philosophy of a high performance, extremely versatile transient analyzer is described. This sub-system was designed to be controlled through the data acquisition computer system which allows hands off operation. Thus it may be placed on the experiment side of the high voltage safety break between the experimental device and the control room. This analyzer provides control features which are extremely useful for data acquisition from PPPL diagnostics. These include dynamic sample rate changing, which may be intermixed with multiple post trigger operations with variable length blocks using normal, peak to peak or integrate modes. Included in the discussion are general remarks on the advantages of adding intelligence to transient analyzers, a detailed description of the characteristics of the PPPL transient analyzer, a description of the hardware, firmware, control language and operation of the PPPL transient analyzer, and general remarks on future trends in this type of instrumentation both at PPPL and in general

Chronic Iron Limitation Confers Transient Resistance to Oxidative Stress in Marine Diatoms1

Science.gov (United States)

Graff van Creveld, Shiri; Rosenwasser, Shilo; Vardi, Assaf

2016-01-01

Diatoms are single-celled, photosynthetic, bloom-forming algae that are responsible for at least 20% of global primary production. Nevertheless, more than 30% of the oceans are considered “ocean deserts” due to iron limitation. We used the diatom Phaeodactylum tricornutum as a model system to explore diatom’s response to iron limitation and its interplay with susceptibility to oxidative stress. By analyzing physiological parameters and proteome profiling, we defined two distinct phases: short-term (5 d, phase II) iron limitation. While at phase I no significant changes in physiological parameters were observed, molecular markers for iron starvation, such as Iron Starvation Induced Protein and flavodoxin, were highly up-regulated. At phase II, down-regulation of numerous iron-containing proteins was detected in parallel to reduction in growth rate, chlorophyll content, photosynthetic activity, respiration rate, and antioxidant capacity. Intriguingly, while application of oxidative stress to phase I and II iron-limited cells similarly oxidized the reduced glutathione (GSH) pool, phase II iron limitation exhibited transient resistance to oxidative stress, despite the down regulation of many antioxidant proteins. By comparing proteomic profiles of P. tricornutum under iron limitation and metatranscriptomic data of an iron enrichment experiment conducted in the Pacific Ocean, we propose that iron-limited cells in the natural environment resemble the phase II metabolic state. These results provide insights into the trade-off between optimal growth rate and susceptibility to oxidative stress in the response of diatoms to iron quota in the marine environment. PMID:27503604

Modelling of phenomena associated with high burnup fuel behaviour during overpower transients

International Nuclear Information System (INIS)

Sills, H.E.; Langman, V.J.; Iglesias, F.C.

1995-01-01

Phenomena of importance to the behaviour of high burnup fuel subjected to conditions of rapid overpower (i.e., LWR RIAs) include the change in cladding material properties due to irradiation, pellet-clad interaction (PCI) and 'rim' effects associated with the periphery of high burnup fuel. 'Rim' effects are postulated to be caused by changes in fuel morphology at high burnup. Typical discharge burnups for CANDU fuel are low compared to LWRs. Maximum linear ratings for CANDU fuel are higher than those for LWRs. However, under normal operating conditions, the Zircaloy-4 clad of the CANDU fuel is collapsed onto the fuel stack. Thus, the CANDU fuel performance codes model the transient behaviour of the fuel-to-clad interface and are capable of assessing the potential for pellet-clad mechanical interaction (PCMI) failures for a wide range of overpower conditions. This report provides a discussion of the modelling of the phenomena of importance to high burnup fuel behaviour during rapid overpower transients. (author)

Electrical capacity and resistance determination of emitting electric transducer

International Nuclear Information System (INIS)

Alba Fernandez, J.; Ramis Soriano, J.

2000-01-01

In this work we calculate the electrical resistance and capacity of emitting electric transducer, which is mainly formed, in direct relationship with its properties, by a ceramic capacitor. Our aim is to motivate the students with an attractive element in order to carry out traditional measurements of the charge and discharge transients of a capacitor, implementing high resistance setups. (Author) 5 refs

Modeling and Mitigation for High Frequency Switching Transients Due to Energization in Offshore Wind Farms

Directory of Open Access Journals (Sweden)

Yanli Xin

2016-12-01

Full Text Available This paper presents a comprehensive investigation on high frequency (HF switching transients due to energization of vacuum circuit breakers (VCBs in offshore wind farms (OWFs. This research not only concerns the modeling of main components in collector grids of an OWF for transient analysis (including VCBs, wind turbine transformers (WTTs, submarine cables, but also compares the effectiveness between several mainstream switching overvoltage (SOV protection methods and a new mitigation method called smart choke. In order to accurately reproduce such HF switching transients considering the current chopping, dielectric strength (DS recovery capability and HF quenching capability of VCBs, three models are developed, i.e., a user–defined VCB model, a HF transformer terminal model and a three-core (TC frequency dependent model of submarine cables, which are validated through simulations and compared with measurements. Based on the above models and a real OWF configuration, a simulation model is built and several typical switching transient cases are investigated to analyze the switching transient process and phenomena. Subsequently, according to the characteristics of overvoltages, appropriate parameters of SOV mitigation methods are determined to improve their effectiveness. Simulation results indicate that the user–defined VCB model can satisfactorily simulate prestrikes and the proposed component models display HF characteristics, which are consistent with onsite measurement behaviors. Moreover, the employed protection methods can suppress induced SOVs, which have a steep front, a high oscillation frequency and a high amplitude, among which the smart choke presents a preferable HF damping effect.

Resistive wall mode feedback control in EXTRAP T2R with improved steady-state error and transient response

Science.gov (United States)

Brunsell, P. R.; Olofsson, K. E. J.; Frassinetti, L.; Drake, J. R.

2007-10-01

Experiments in the EXTRAP T2R reversed field pinch [P. R. Brunsell, H. Bergsåker, M. Cecconello et al., Plasma Phys. Control. Fusion 43, 1457 (2001)] on feedback control of m =1 resistive wall modes (RWMs) are compared with simulations using the cylindrical linear magnetohydrodynamic model, including the dynamics of the active coils and power amplifiers. Stabilization of the main RWMs (n=-11,-10,-9,-8,+5,+6) is shown using modest loop gains of the order G ˜1. However, other marginally unstable RWMs (n=-2,-1,+1,+2) driven by external field errors are only partially canceled at these gains. The experimental system stability limit is confirmed by simulations showing that the latency of the digital controller ˜50μs is degrading the system gain margin. The transient response is improved with a proportional-plus-derivative controller, and steady-state error is improved with a proportional-plus-integral controller. Suppression of all modes is obtained at high gain G ˜10 using a proportional-plus-integral-plus-derivative controller.

VO2 OFF TRANSIENT KINETICS IN EXTREME INTENSITY SWIMMING

Directory of Open Access Journals (Sweden)

Ana Sousa

2011-09-01

Full Text Available Inconsistencies about dynamic asymmetry between the on- and off- transient responses in oxygen uptake are found in the literature. Therefore, the purpose of this study was to characterize the oxygen uptake off-transient kinetics during a maximal 200-m front crawl effort, as examining the degree to which the on/off regularity of the oxygen uptake kinetics response was preserved. Eight high level male swimmers performed a 200-m front crawl at maximal speed during which oxygen uptake was directly measured through breath-by-breath oxymetry (averaged every 5 s. This apparatus was connected to the swimmer by a low hydrodynamic resistance respiratory snorkel and valve system. Results: The on- and off-transient phases were symmetrical in shape (mirror image once they were adequately fitted by a single-exponential regression models, and no slow component for the oxygen uptake response was developed. Mean (± SD peak oxygen uptake was 69.0 (± 6.3 mL·kg-1·min-1, significantly correlated with time constant of the off- transient period (r = 0.76, p < 0.05 but not with any of the other oxygen off-transient kinetic parameters studied. A direct relationship between time constant of the off-transient period and mean swimming speed of the 200-m (r = 0.77, p < 0.05, and with the amplitude of the fast component of the effort period (r = 0.72, p < 0.05 were observed. The mean amplitude and time constant of the off-transient period values were significantly greater than the respective on- transient. In conclusion, although an asymmetry between the on- and off kinetic parameters was verified, both the 200-m effort and the respectively recovery period were better characterized by a single exponential regression model

Modeling of Transient Response of the Wickless Heat Pipes

International Nuclear Information System (INIS)

Hussien, A.K.A.

2013-01-01

Thermosyphons transient response for startup from ambient temperature to steady state until shutdown conditions, is considered a stringent necessity for applications such as electronic, solar, geothermal and even nuclear reactors safety systems. This typically returns to the need to keep the temperature within certain limits before reaching critical conditions. A simple network model is derived for describing the transient response of closed two-phase thermosyphon (CTPT) at startup and shutdown states. In addition, for predicting the effect of operational characteristics of water/copper closed two-phase thermosyphon such as thermal load, filling ratio, evaporator length, and thermosyphon tube diameter. The thermosyphons operation was considered a thermal network of various components with different thermal resistances and dynamic responses. The network model consists of six sub-models. These models are pure conduction in walls of evaporator, adiabatic and condenser, and convection in evaporator pool, evaporator film, and condenser film. So, an energy balance for each sub-model was done to estimate temperatures, heat transfer coefficients, thermal resistances, time constant, and other thermal characteristics that describe the required transient response of the closed two-phase thermosyphon. Governing equations of the transient thermosyphon behavior can be simplified into a set of first-order linear ordinary differential equations. The Runge-Kutta method can be used to obtain transient thermosyphon temperatures from these equations.

On RELAP5-simulated High Flux Isotope Reactor reactivity transients: Code change and application

International Nuclear Information System (INIS)

Freels, J.D.

1993-01-01

This paper presents a new and innovative application for the RELAP5 code (hereafter referred to as ''the code''). The code has been used to simulate several transients associated with the (presently) draft version of the High-Flux Isotope Reactor (HFIR) updated safety analysis report (SAR). This paper investigates those thermal-hydraulic transients induced by nuclear reactivity changes. A major goal of the work was to use an existing RELAP5 HFIR model for consistency with other thermal-hydraulic transient analyses of the SAR. To achieve this goal, it was necessary to incorporate a new self-contained point kinetics solver into the code because of a deficiency in the point-kinetics reactivity model of the Mod 2.5 version of the code. The model was benchmarked against previously analyzed (known) transients. Given this new code, four event categories defined by the HFIR probabilistic risk assessment (PRA) were analyzed: (in ascending order of severity) a cold-loop pump start; run-away shim-regulating control cylinder and safety plate withdrawal; control cylinder ejection; and generation of an optimum void in the target region. All transients are discussed. Results of the bounding incredible event transient, the target region optimum void, are shown. Future plans for RELAP5 HFIR applications and recommendations for code improvements are also discussed

High temperature resistant cermet and ceramic compositions

Science.gov (United States)

Phillips, W. M. (Inventor)

1978-01-01

Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.

Tests of the SNR fuel pin behaviour in case of operational transients in the HFR Petten

International Nuclear Information System (INIS)

Plitz, H.

1989-05-01

The loadings on fast reactor fuel pins under operational transients (power and temperature increases in the design area) have been studied in the High-Flux-Reactor HFR in Petten with sodium cooled irradiation capsules. The results of the first campaign of transient experiments are described in the report. No cladding defects have been observed, and the fuel pins of the Mark-I and Mark-II type resisted to linear power levels of more than 800 W/cm, thus demonstrating the required design margins. The plans for further experiments are outlined

The wheat homolog of putative nucleotide-binding site-leucine-rich repeat resistance gene TaRGA contributes to resistance against powdery mildew.

Science.gov (United States)

Wang, Defu; Wang, Xiaobing; Mei, Yu; Dong, Hansong

2016-03-01

Powdery mildew, one of the most destructive wheat diseases worldwide, is caused by Blumeria graminis f. sp. tritici (Bgt), a fungal species with a consistently high mutation rate that makes individual resistance (R) genes ineffective. Therefore, effective resistance-related gene cloning is vital for breeding and studying the resistance mechanisms of the disease. In this study, a putative nucleotide-binding site-leucine-rich repeat (NBS-LRR) R gene (TaRGA) was cloned using a homology-based cloning strategy and analyzed for its effect on powdery mildew disease and wheat defense responses. Real-time reverse transcription-PCR (RT-PCR) analyses revealed that a Bgt isolate 15 and salicylic acid stimulation significantly induced TaRGA in the resistant variety. Furthermore, the silencing of TaRGA in powdery mildew-resistant plants increased susceptibility to Bgt15 and prompted conidia propagation at the infection site. However, the expression of TaRGA in leaf segments after single-cell transient expression assay highly increased the defense responses to Bgt15 by enhancing callose deposition and phenolic autofluorogen accumulation at the pathogen invading sites. Meanwhile, the expression of pathogenesis-related genes decreased in the TaRGA-silenced plants and increased in the TaRGA-transient-overexpressing leaf segments. These results implied that the TaRGA gene positively regulates the defense response to powdery mildew disease in wheat.

Development of high-performance concrete having high resistance to chloride penetration

International Nuclear Information System (INIS)

Oh, Byung Hwan; Cha, Soo Won; Jang, Bong Seok; Jang, Seung Yup

2002-01-01

The resistance to chloride penetration is one of the simplest measures to determine the durability of concrete, e.g. resistance to freezing and thawing, corrosion of steel in concrete and other chemical attacks. Thus, high-performance concrete may be defined as the concrete having high resistance to chloride penetration as well as high strength. The purpose of this paper is to investigate the resistance to chloride penetration of different types of concrete and to develop high-performance concrete that has very high resistance to chloride penetration, and thus, can guarantee high durability. A large number of concrete specimens have been tested by the rapid chloride permeability test method as designated in AASHTO T 277 and ASTM C 1202. The major test variables include water-to-binder ratios, type of cement, type and amount of mineral admixtures (silica fume, fly ash and blast-furnace slag), maximum size of aggregates and air-entrainment. Test results show that concrete containing optimal amount of silica fume shows very high resistance to chloride penetration, and high-performance concrete developed in this study can be efficiently employed to enhance the durability of concrete structures in severe environments such as nuclear power plants, water-retaining structures and other offshore structures

Evaluation of thermal resistance constitution for packaged AlGaN/GaN high electron mobility transistors by structure function method

International Nuclear Information System (INIS)

Zhang Guang-Chen; Feng Shi-Wei; Zhou Zhou; Li Jing-Wan; Guo Chun-Sheng

2011-01-01

The evaluation of thermal resistance constitution for packaged AlGaN/GaN high electron mobility transistor (HEMT) by structure function method is proposed in this paper. The evaluation is based on the transient heating measurement of the AlGaN/GaN HEMT by pulsed electrical temperature sensitive parameter method. The extracted chip-level and package-level thermal resistances of the packaged multi-finger AlGaN/GaN HEMT with 400-μm SiC substrate are 22.5 K/W and 7.2 K/W respectively, which provides a non-invasive method to evaluate the chip-level thermal resistance of packaged AlGaN/GaN HEMTs. It is also experimentally proved that the extraction of the chip-level thermal resistance by this proposed method is not influenced by package form of the tested device and temperature boundary condition of measurement stage. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Investigation of electrically-active deep levels in single-crystalline diamond by particle-induced charge transient spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kada, W., E-mail: kada.wataru@gunma-u.ac.jp [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Kambayashi, Y.; Ando, Y. [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Onoda, S. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Umezawa, H.; Mokuno, Y. [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Shikata, S. [Kwansei Gakuin Univ., 2-1, Gakuen, Mita, Hyogo 669-1337 (Japan); Makino, T.; Koka, M. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Hanaizumi, O. [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Kamiya, T.; Ohshima, T. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan)

2016-04-01

To investigate electrically-active deep levels in high-resistivity single-crystalline diamond, particle-induced charge transient spectroscopy (QTS) techniques were performed using 5.5 MeV alpha particles and 9 MeV carbon focused microprobes. For unintentionally-doped (UID) chemical vapor deposition (CVD) diamond, deep levels with activation energies of 0.35 eV and 0.43 eV were detected which correspond to the activation energy of boron acceptors in diamond. The results suggested that alpha particle and heavy ion induced QTS techniques are the promising candidate for in-situ investigation of deep levels in high-resistivity semiconductors.

The High Time Resolution Universe surveys for pulsars and fast transients

Science.gov (United States)

Keith, Michael J.

2013-03-01

The High Time Resolution Universe survey for pulsars and transients is the first truly all-sky pulsar survey, taking place at the Parkes Radio Telescope in Australia and the Effelsberg Radio Telescope in Germany. Utilising multibeam receivers with custom built all-digital recorders the survey targets the fastest millisecond pulsars and radio transients on timescales of 64 μs to a few seconds. The new multibeam digital filter-bank system at has a factor of eight improvement in frequency resolution over previous Parkes multibeam surveys, allowing us to probe further into the Galactic plane for short duration signals. The survey is split into low, mid and high Galactic latitude regions. The mid-latitude portion of the southern hemisphere survey is now completed, discovering 107 previously unknown pulsars, including 26 millisecond pulsars. To date, the total number of discoveries in the combined survey is 135 and 29 MSPs These discoveries include the first magnetar to be discovered by it's radio emission, unusual low-mass binaries, gamma-ray pulsars and pulsars suitable for pulsar timing array experiments.

Goaf water detection using the grounded electrical source airborne transient electromagnetic system

Science.gov (United States)

Li, D.; Ji, Y.; Guan, S.; Wu, Y.; Wang, A.

2017-12-01

To detect the geoelectric characteristic of goaf water, the grounded electrical source airborne transient electromagnetic (GREATEM) system (developed by Jilin University, China) is applied to the goaf water detection since its advantages of considerable prospecting depth, lateral resolution and detection efficiency. For the test of GREATEM system in goaf water detection, an experimental survey was conducted at Qinshui coal mine (Shanxi province, China). After data acquisition, noise reduction and inversion, the resistivity profiles of survey area is presented. The results highly agree the investigation information provided by Shanxi Coal Geology Geophysical Surveying Exploration Institute (China), conforming that the GREATEM system is an effective technique for resistivity detection of goaf water.

Compiling a national resistivity atlas of Denmark based on airborne and ground-based transient electromagnetic data

DEFF Research Database (Denmark)

Barfod, Adrian; Møller, Ingelise; Christiansen, Anders Vest

2016-01-01

in the large-scale resistivity-lithology relations, reflecting geological details such as available source material for tills. The resistivity maps also reveal a clear ambiguity in the resistivity values for different lithologies. The Resistivity Atlas is highly useful when geophysical data are to be used...

Adaptive sampling of AEM transients

Science.gov (United States)

Di Massa, Domenico; Florio, Giovanni; Viezzoli, Andrea

2016-02-01

This paper focuses on the sampling of the electromagnetic transient as acquired by airborne time-domain electromagnetic (TDEM) systems. Typically, the sampling of the electromagnetic transient is done using a fixed number of gates whose width grows logarithmically (log-gating). The log-gating has two main benefits: improving the signal to noise (S/N) ratio at late times, when the electromagnetic signal has amplitudes equal or lower than the natural background noise, and ensuring a good resolution at the early times. However, as a result of fixed time gates, the conventional log-gating does not consider any geological variations in the surveyed area, nor the possibly varying characteristics of the measured signal. We show, using synthetic models, how a different, flexible sampling scheme can increase the resolution of resistivity models. We propose a new sampling method, which adapts the gating on the base of the slope variations in the electromagnetic (EM) transient. The use of such an alternative sampling scheme aims to get more accurate inverse models by extracting the geoelectrical information from the measured data in an optimal way.

Highly Stable Operation of Lithium Metal Batteries Enabled by the Formation of a Transient High Concentration Electrolyte Layer

Energy Technology Data Exchange (ETDEWEB)

Zheng, Jianming; Yan, Pengfei; Mei, Donghai; Engelhard, Mark H.; Cartmell, Samuel S.; Polzin, Bryant; Wang, Chong M.; Zhang, Jiguang; Xu, Wu

2016-02-08

Lithium (Li) metal has been extensively investigated as an anode for rechargeable battery applications due to its ultrahigh specific capacity and the lowest redox potential. However, significant challenges including dendrite growth and low Coulombic efficiency are still hindering the practical applications of rechargeable Li metal batteries. Here, we demonstrate that long-term cycling of Li metal batteries can be realized by the formation of a transient high concentration electrolyte layer near the surface of Li metal anode during high rate discharge process. The highly concentrated Li+ ions in this transient layer will immediately solvate with the available solvent molecules and facilitate the formation of a stable and flexible SEI layer composed of a poly(ethylene carbonate) framework integrated with other organic/inorganic lithium salts. This SEI layer largely suppresses the corrosion of Li metal anode by free organic solvents and enables the long-term operation of Li metal batteries. The fundamental findings in this work provide a new direction for the development and operation of Li metal batteries that could be operated at high current densities for a wide range of applications.

High temperature resistant cermet and ceramic compositions. [for thermal resistant insulators and refractory coatings

Science.gov (United States)

Phillips, W. M. (Inventor)

1978-01-01

High temperature oxidation resistance, high hardness and high abrasion and wear resistance are properties of cermet compositions particularly to provide high temperature resistant refractory coatings on metal substrates, for use as electrical insulation seals for thermionic converters. The compositions comprise a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride are also described.

Compressive Transient Imaging

KAUST Repository

Sun, Qilin

2017-04-01

High resolution transient/3D imaging technology is of high interest in both scientific research and commercial application. Nowadays, all of the transient imaging methods suffer from low resolution or time consuming mechanical scanning. We proposed a new method based on TCSPC and Compressive Sensing to achieve a high resolution transient imaging with a several seconds capturing process. Picosecond laser sends a serious of equal interval pulse while synchronized SPAD camera\\'s detecting gate window has a precise phase delay at each cycle. After capturing enough points, we are able to make up a whole signal. By inserting a DMD device into the system, we are able to modulate all the frames of data using binary random patterns to reconstruct a super resolution transient/3D image later. Because the low fill factor of SPAD sensor will make a compressive sensing scenario ill-conditioned, We designed and fabricated a diffractive microlens array. We proposed a new CS reconstruction algorithm which is able to denoise at the same time for the measurements suffering from Poisson noise. Instead of a single SPAD senor, we chose a SPAD array because it can drastically reduce the requirement for the number of measurements and its reconstruction time. Further more, it not easy to reconstruct a high resolution image with only one single sensor while for an array, it just needs to reconstruct small patches and a few measurements. In this thesis, we evaluated the reconstruction methods using both clean measurements and the version corrupted by Poisson noise. The results show how the integration over the layers influence the image quality and our algorithm works well while the measurements suffer from non-trival Poisson noise. It\\'s a breakthrough in the areas of both transient imaging and compressive sensing.

Segregated copper ratio experiment on transient stability (SeCRETS). Final Report

International Nuclear Information System (INIS)

Bruzzone, P.

2001-01-01

Two Nb 3 Sn, steel jacketed, cable-in-conduit conductors have been manufactured with identical non-Cu cross sections and the stabilizer either included in the Nb 3 Sn composite or partly segregated as copper wires. The two conductors are series connected and wound as a bifilar , single layer solenoid, assembled in the high field bore (11 T) of the SULTAN test facility. The operating current is up to 12 kA (400 A/mm 2 ). A transverse pulsed field is applied with ΔB up to 2.7 T, field rate up to 180 T/s and field integral up to 530 T 2 /s. In the dc test, a good agreement is found between the I c and the T cs results, both correctly scaling according to the parameters derived from the strand tests. The n-value from the V-I curve is in the range of 15. The current sharing at the high field section is correlated with a local current re-distribution, observed by arrays of miniature Hall sensors, detecting the self-field around the conductor. The ac losses results in the range of 2 to 9 Hz by gas flow calorimetry indicate coupling currents constant, nτ, in the range of 1.5 ms at high field, increasing by a factor of 2 with 12 kA transport current. Loss extrapolation to 0 frequency suggests that the loss curve may be not linear outside the test range, with higher nτ at lower field rate. The calorimetric loss estimation at the fast field transient (f=15 Hz) indicates nτ ≅ 2 ms. The ITER plasma disruption transients have been reproduced by the pulsed coils. Due to the very low ac losses, no quench could be generated in either conductor even reducing the temperature margin below 0.2-0.3 K. Very large field transients, with integral above 100 T 2 /s, are required to quench the conductors. In that range, the conductor without segregated copper has superior performance. Due to the large interstrand resistance (very low ac losses), the segregated copper has marginal contribution to the stability. No evidence of current redistribution is observed during the field transients

Concretes with high mechanical resistance

International Nuclear Information System (INIS)

Mauny, Pierre.

1973-01-01

Description is given of a method for manufacturing concretes with high mechanical resistance in compression, obtained by mixing gravels highly resistant to compression, sand and cement in an aqueous medium. Use is made of sands of porous ceramics, such as terra-cotta, of a grain size from 0,1 to 5mm, the pore diameter of which is from 0.5 to 15 microns, chosen so as to be slighty bigger than the crystals of the cement used. This can be applied to the pre-stressed structures used in the nuclear field [fr

Determination of charge transfer resistance and capacitance of microbial fuel cell through a transient response analysis of cell voltage.

Science.gov (United States)

Ha, Phuc Thi; Moon, Hyunsoo; Kim, Byung Hong; Ng, How Yong; Chang, In Seop

2010-03-15

An alternative method for determining the charge transfer resistance and double-layer capacitance of microbial fuel cells (MFCs), easily implemented without a potentiostat, was developed. A dynamic model with two parameters, the charge transfer resistance and double-layer capacitance of electrodes, was derived from a linear differential equation to depict the current generation with respect to activation overvoltage. This model was then used to fit the transient cell voltage response to the current step change during the continuous operation of a flat-plate type MFC fed with acetate. Variations of the charge transfer resistance and the capacitance value with respect to the MFC design conditions (biocatalyst existence and electrode area) and operating parameters (acetate concentration and buffer strength in the catholyte) were then determined to elucidate the validity of the proposed method. This model was able to describe the dynamic behavior of the MFC during current change in the activation loss region; having an R(2) value of over 0.99 in most tests. Variations of the charge transfer resistance value (thousands of Omega) according to the change of the design factors and operational factors were well-correlated with the corresponding MFC performances. However, though the capacitance values (approximately 0.02 F) reflected the expected trend according to the electrode area change and catalyst property, they did not show significant variation with changes in either the acetate concentration or buffer strength. (c) 2009 Elsevier B.V. All rights reserved.

Extreme Transients in the High Energy Universe

Science.gov (United States)

Kouveliotou, Chryssa

2013-01-01

The High Energy Universe is rich in diverse populations of objects spanning the entire cosmological (time)scale, from our own present-day Milky Way to the re-ionization epoch. Several of these are associated with extreme conditions irreproducible in laboratories on Earth. Their study thus sheds light on the behavior of matter under extreme conditions, such as super-strong magnetic fields (in excess of 10^14 G), high gravitational potentials (e.g., Super Massive Black Holes), very energetic collimated explosions resulting in relativistic jet flows (e.g., Gamma Ray Bursts, exceeding 10^53 ergs). In the last thirty years, my work has been mostly focused on two apparently different but potentially linked populations of such transients: magnetars (highly magnetized neutron stars) and Gamma Ray Bursts (strongly beamed emission from relativistic jets), two populations that constitute unique astrophysical laboratories, while also giving us the tools to probe matter conditions in the Universe to redshifts beyond z=10, when the first stars and galaxies were assembled. I did not make this journey alone I have either led or participated in several international collaborations studying these phenomena in multi-wavelength observations; solitary perfection is not sufficient anymore in the world of High Energy Astrophysics. I will describe this journey, present crucial observational breakthroughs, discuss key results and muse on the future of this field.

High temperature resistant nanofiber by bubbfil-spinning

Directory of Open Access Journals (Sweden)

Li Ya

2015-01-01

Full Text Available Heat-resisting nanofibers have many potential applications in various industries, and the bubbfil spinning is the best candidate for mass-production of such materials. Polyether sulfone/zirconia solution with a bi-solvent system is used in the experiment. Experimental result reveals that polyether sulfone/zirconia nanofibers have higher resistance to high temperature than pure polyether sulfone fibers, and can be used as high-temperature-resistant filtration materials.

Transient period analysis of a distillation column using a control approach with distributed heating; Analise do periodo transiente de uma coluna de destilacao usando abordagem de controle com aquecimento distribuido

Energy Technology Data Exchange (ETDEWEB)

Werle, Leandro O.; Steinmacher, Fernanda R.; Marangoni, Cintia; Araujo, Pedro H.H de; Machado, Ricardo A.F.; Sayer, Claudia [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

2008-07-01

The distillation process is widely used in oil refineries. The non-linear behavior, the coupling between variables and the high time constants, associated to the response delay, result in long transient periods operating out of the desired conditions, obtaining out of specification products. Even with several researches in more and more complex control approaches, few works approached the aspect of transient minimization. Moreover, the control of distillation columns is carried out centralized at the bottom and the top. In the present work the effect of the distributed control is evaluated, through the electric resistance located on an intermediate tray of the column. The objective of the work is reducing the operation transients when a disturbance is applied. For the current study, experiments have been carried out in a pilot distillation unit composed of 13 trays and instrumented in fieldbus, processing an ethanol-water mixture. Step disturbances of 50% in the feeding flow rate of have been carried out. The comparison of the results showed that the introduction of the distributed heating throughout the column allows faster dynamics, revealing itself as a valid option for the transient reduction. (author)

Transient analysis for resolving safety issues

International Nuclear Information System (INIS)

Chao, J.; Layman, W.

1987-01-01

The Nuclear Safety Analysis Center (NSAC) has a Generic Safety Analysis Program to help resolve high priority generic safety issues. This paper describes several high priority safety issues considered at NSAC and how they were resolved by transient analysis using thermal hydraulics and neutronics codes. These issues are pressurized thermal shock (PTS), anticipated transients without scram (ATWS), steam generator tube rupture (SGTR), and reactivity transients in light of the Chernobyl accident

The effect of high-flux H plasma exposure with simultaneous transient heat loads on tungsten surface damage and power handling

NARCIS (Netherlands)

van Eden, G. G.; Morgan, T. W.; van der Meiden, H. J.; J Matejicek,; T Chraska,; Wirtz, M.; De Temmerman, G.

2014-01-01

The performance of the full-W ITER divertor may be significantly affected by the interplay between steady-state plasma exposure and transient events. To address this issue, the effect of a high-flux H plasma on the thermal shock response of W to ELM-like transients has been investigated. Transient

High counting rate resistive-plate chamber

International Nuclear Information System (INIS)

Peskov, V.; Anderson, D.F.; Kwan, S.

1993-05-01

Parallel-plate avalanche chambers (PPAC) are widely used in physics experiments because they are fast ( 5 counts/mm 2 . A resistive-plate chamber (RPC) is similar to the PPAC in construction except that one or both of the electrodes are made from high resistivity (≥10 10 Ω·cm) materials. In practice RPCs are usually used in the spark mode. Resistive electrodes are charged by sparks, locally reducing the actual electric field in the gap. The size of the charged surface is about 10 mm 2 , leaving the rest of the detector unaffected. Therefore, the rate capability of such detectors in the spark mode is considerably higher than conventional spark counters. Among the different glasses tested the best results were obtained with electron type conductive glasses, which obey Ohm's law. Most of the work with such glasses was done with high pressure parallel-plate chambers (10 atm) for time-of-flight measurements. Resistive glasses have been expensive and produced only in small quantities. Now resistive glasses are commercially available, although they are still expensive in small scale production. From the positive experience of different groups working with the resistive glasses, it was decided to review the old idea to use this glass for the RPC. This work has investigated the possibility of using the RPC at 1 atm and in the avalanche mode. This has several advantages: simplicity of construction, high rate capability, low voltage operation, and the ability to work with non-flammable gases

Transient Resistive Wall Wake for Very Short Bunches

International Nuclear Information System (INIS)

Stupakov, G.; SLAC

2005-01-01

The catch up distance for the resistive wall wake in a round pipe is approximately equal to the square of the pipe radius divided by the bunch length. The standard formulae for this wake are applicable at distances much larger than the catch up distance. In this paper, we calculate the resistive wall wake at distances compared with the catch up distance assuming a constant wall conductivity

An analytical and experimental investigation of natural circulation transients in a model pressurized water reactor

International Nuclear Information System (INIS)

Massoud, M.

1987-01-01

Natural Circulation phenomena in a simulated PWR was investigated experimentally and analytically. The experimental investigation included determination of system characteristics as well as system response to the imposed transient under symmetric and asymmetric operations. System characteristics were used to obtain correlation for heat transfer coefficient in heat exchangers, system flow resistance, and system buoyancy heat. Asymmetric transients were imposed to study flow oscillation and possible instability. The analytical investigation encompassed development of mathematical model for single-phase, steady-state and transient natural circulation as well as modification of existing model for two-phase flow analysis of phenomena such as small break LOCA, high pressure coolant injection and pump coast down. The developed mathematical model for single-phase analysis was computer coded to simulate the imposed transients. The computer program, entitled ''Symmetric and Asymmetric Analysis of Single-Phase Flow (SAS),'' were employed to simulate the imposed transients. It closely emulated the system behavior throughout the transient and subsequent steady-state. Modifications for two-phase flow analysis included addition of models for once-through steam generator and electric heater rods. Both programs are faster than real time. Off-line, they can be used for prediction and training applications while on-line they serve for simulation and signal validation. The programs can also be used to determine the sensitivity of natural circulation behavior to variation of inputs such as secondary distribution and power transients

Transient Overexpression of HvSERK2 Improves Barley Resistance to Powdery Mildew.

Science.gov (United States)

Li, Yingbo; Li, Qingwei; Guo, Guimei; He, Ting; Gao, Runhong; Faheem, Muhammad; Huang, Jianhua; Lu, Ruiju; Liu, Chenghong

2018-04-18

Somatic embryogenesis receptor-like kinases (SERKs) play an essential role in plant response to pathogen infection. Here we identified three SERK genes ( HvSERK1/2/3 ) from barley, and aimed to determine their implication in defense responses to barley powdery mildew ( Bgh ). Although HvSERK1/2/3 share the characteristic domains of the SERK family, only HvSERK2 was significantly induced in barley leaves during Bgh infection. The expression of HvSERK2 was rapidly induced by hydrogen peroxide (H₂O₂) treatment, but not by treatment with salicylic acid (SA), methyl jasmonate (MeJA), ethephon (ETH), or abscisic acid (ABA). Bioinformatics analysis of the cloned HvSERK2 promoter revealed that it contains several elements responsible for defense responses against pathogens. Promoter functional analysis showed that the HvSERK2 promoter was induced by Bgh and H₂O₂. Subcellular localization analysis of HvSERK2 indicated that it is mainly located on the plasma membrane. Transient overexpression of HvSERK2 in epidermal cells of the susceptible barley cultivar Hua 30 reduced the Bgh haustorium index from 58.6% to 43.2%. This study suggests that the HvSERK2 gene plays a positive role in the improvement of barley resistance to powdery mildew, and provides new insight into the function of SERK genes in the biotic stress response of plants.

Enhanced Severe Transient Analysis for Prevention Technical Program Plan

Energy Technology Data Exchange (ETDEWEB)

Gougar, Hans [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2014-09-01

This document outlines the development of a high fidelity, best estimate nuclear power plant severe transient simulation capability that will complement or enhance the integral system codes historically used for licensing and analysis of severe accidents. As with other tools in the Risk Informed Safety Margin Characterization (RISMC) Toolkit, the ultimate user of Enhanced Severe Transient Analysis and Prevention (ESTAP) capability is the plant decision-maker; the deliverable to that customer is a modern, simulation-based safety analysis capability, applicable to a much broader class of safety issues than is traditional Light Water Reactor (LWR) licensing analysis. Currently, the RISMC pathway’s major emphasis is placed on developing RELAP-7, a next-generation safety analysis code, and on showing how to use RELAP-7 to analyze margin from a modern point of view: that is, by characterizing margin in terms of the probabilistic spectra of the “loads” applied to systems, structures, and components (SSCs), and the “capacity” of those SSCs to resist those loads without failing. The first objective of the ESTAP task, and the focus of one task of this effort, is to augment RELAP-7 analyses with user-selected multi-dimensional, multi-phase models of specific plant components to simulate complex phenomena that may lead to, or exacerbate, severe transients and core damage. Such phenomena include: coolant crossflow between PWR assemblies during a severe reactivity transient, stratified single or two-phase coolant flow in primary coolant piping, inhomogeneous mixing of emergency coolant water or boric acid with hot primary coolant, and water hammer. These are well-documented phenomena associated with plant transients but that are generally not captured in system codes. They are, however, generally limited to specific components, structures, and operating conditions. The second ESTAP task is to similarly augment a severe (post-core damage) accident integral analyses code

Measuring voltage transients with an ultrafast scanning tunneling microscope

DEFF Research Database (Denmark)

Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

1997-01-01

circuit, where the tunneling tip is directly connected to the current amplifier of the scanning tunneling microscope, this dependence is eliminated. Ail results can be explained with coupling through the geometrical capacitance of the tip-electrode junction. By illuminating the current......We use an ultrafast scanning tunneling microscope to resolve propagating voltage transients in space and time. We demonstrate that the previously observed dependence of the transient signal amplitude on the tunneling resistance was only caused by the electrical sampling circuit. With a modified...

Improved lumped models for transient combined convective and radiative cooling of multi-layer composite slabs

International Nuclear Information System (INIS)

An Chen; Su Jian

2011-01-01

Improved lumped parameter models were developed for the transient heat conduction in multi-layer composite slabs subjected to combined convective and radiative cooling. The improved lumped models were obtained through two-point Hermite approximations for integrals. Transient combined convective and radiative cooling of three-layer composite slabs was analyzed to illustrate the applicability of the proposed lumped models, with respect to different values of the Biot numbers, the radiation-conduction parameter, the dimensionless thermal contact resistances, the dimensionless thickness, and the dimensionless thermal conductivity. It was shown by comparison with numerical solution of the original distributed parameter model that the higher order lumped model (H 1,1 /H 0,0 approximation) yielded significant improvement of average temperature prediction over the classical lumped model. In addition, the higher order (H 1,1 /H 0,0 ) model was applied to analyze the transient heat conduction problem of steel-concrete-steel sandwich plates. - Highlights: → Improved lumped models for convective-radiative cooling of multi-layer slabs were developed. → Two-point Hermite approximations for integrals were employed. → Significant improvement over classical lumped model was achieved. → The model can be applied to high Biot number and high radiation-conduction parameter. → Transient heat conduction in steel-concrete-steel sandwich pipes was analyzed as an example.

Corrosion-Resistant High-Entropy Alloys: A Review

Directory of Open Access Journals (Sweden)

Yunzhu Shi

2017-02-01

Full Text Available Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

Mechanism of high-temperature resistant water-base mud

Energy Technology Data Exchange (ETDEWEB)

Luo, P

1981-01-01

Based on experiments, the causes and laws governing the changes in the performance of water-base mud under high temperature are analyzed, and the requisites and mechanism of treating agents resisting high temperature are discussed. Ways and means are sought for inhibiting, delaying and making use of the effect of high temperature on the performance of mud, while new ideas and systematic views have been expressed on the preparation of treating agents and set-up of a high temperature resistant water-base mud system. High temperature dispersion and high temperature surface inactivation of clay in the mud, as well as their effect and method of utilization are reviewed. Subjects also touched upon include degradation and cross-linking of the high-temperature resistant treating agents, their use and effect. Based on the above, the preparation of a water-base and system capable of resisting 180 to 250/sup 0/C is recommended.

Preliminary analysis of typical transients in fusion driven subcritical system (FDS-I)

International Nuclear Information System (INIS)

Bai Yunqing; Ke Yan; Wu Yican

2007-01-01

The potential safety characteristic is expected as one of the advantages of fusion-driven subcritical system (FDS-I) for the transmutation and incineration of nuclear waste compared with the critical reactor. Transients of the FDS-I may occur due to the perturbation of external neutron source, the failure of functional device, and the occurrence of the uncontrolled event. As typical transient scenarios, the following cases were analyzed: unprotected plasma overpower (UPOP), unprotected loss of flow (ULOF), unprotected transient overpower (UTOP). The transient analyses for the FDS-I were performed with a coupled two-dimensional thermal-hydraulics and neutronics transient analysis code NTC2D. The negative feedback of reactivity is the interesting safety feature of FDS-I as temperature increase, due to the fuel form of the circulating particle. The present simulation results showed that the current FDS-I design has a resistance against severe transient scenarios. (author)

Microstructural Evolution of Ni-Sn Transient Liquid Phase Sintering Bond during High-Temperature Aging

Science.gov (United States)

Feng, Hongliang; Huang, Jihua; Peng, Xianwen; Lv, Zhiwei; Wang, Yue; Yang, Jian; Chen, Shuhai; Zhao, Xingke

2018-05-01

For high-temperature-resistant packaging of new generation power chip, a chip packaging simulation structure of Ni/Ni-Sn/Ni was bonded by a transient liquid-phase sintering process. High-temperature aging experiments were carried out to investigate joint heat stability. The microstructural evolution and mechanism during aging, and mechanical properties after aging were analyzed. The results show that the 30Ni-70Sn bonding layer as-bonded at 340°C for 240 min is mainly composed of Ni3Sn4 and residual Ni particles. When aged at 350°C, because of the difficulty of nucleation for Ni3Sn and quite slow growth of Ni3Sn2, the bonding layer is stable and the strength of that doesn't change obviously with aging time. When aging temperature increased to 500°C, however, the residual Ni particles were gradually dissolved and the bonding layer formed a stable structure with dominated Ni3Sn2 after 36 h. Meanwhile, due to the volume shrinkage (4.43%) from Ni3Sn2 formation, a number of voids were formed. The shear strength shows an increase, resulting from Ni3Sn2 formation, but then it decreases slightly caused by voids. After aging at 500°C for 100 h, shear strength is still maintained at 29.6 MPa. In addition, the mechanism of void formation was analyzed and microstructural evolution model was also established.

High corrosion-resistant fuel spacers

International Nuclear Information System (INIS)

Yoshida, Toshimi; Takase, Iwao; Ikeda, Shinzo; Masaoka, Isao; Nakajima, Junjiro.

1986-01-01

Purpose: To enable manufacturing BWR fuel spacers by prior-art production process, using a zirconium-base alloy having very excellent corrosion resistance. Method: A highly improved nodular-resistant, corrosion-resistant zirconium alloy is devised by adding a slight amount of niobium, titanium and vanadium to zircaloy, of which fuel spacers are produced. That is, there can be obtained an alloy having much more excellent nodular resistance than conventional zircaloy, and free from a large change in plasticity, workability, and weldability, by adding to zirconium about 1.5 % of tin, about 0.15 % of iron, about 0.05 % of chromium, about 0.05 % of nickel, and 0.05 to 0.5 % of at least one or two kinds of niobium, titanium and vanadium. Using this zirconium-base alloy can manufacture fuel spacers by the same manufacturing process, thus improving economy and reliability. (Kamimura, M.)

Physiological and genetics studies of highly radiation-resistant bacteria

International Nuclear Information System (INIS)

Keller, L.C.

1981-01-01

The phenomenon of radiation resistance was studied using micrococci and Moraxella-Acinetobacter capable of surviving very high doses of gamma radiation which were isolated from foods. Physiological age, or growth phase, was found to be an important factor in making comparisons of radiation-resistance among different bacteria and their mutants. Radiation-resistant bacteria were highly resistant to the lethal effect of nitrosoguanidine used for mutagenesis. Studies of relative resistance of radiation-resistant bacteria, radiation-sensitive mutants, and nonradiation-resistant bacteria to killing by different chemical mutagens did not reveal a correlation between the traits of radiation resistance and mutagen resistance among different strains. Comparisons of plasmid profiles of radiation-resistant bacteria and selected radiation-sensitive mutants suggested the possibility that plasmids may carry genes involved in radiation resistance

High temperature oxidation resistant cermet compositions

Science.gov (United States)

Phillips, W. M. (Inventor)

1976-01-01

Cermet compositions are designed to provide high temperature resistant refractory coatings on stainless steel or molybdenum substrates. A ceramic mixture of chromium oxide and aluminum oxide form a coating of chromium oxide as an oxidation barrier around the metal particles, to provide oxidation resistance for the metal particles.

The role of transient receptor potential channels in metabolic syndrome

DEFF Research Database (Denmark)

Liu, Daoyan; Zhu, Zhiming; Tepel, Martin

2008-01-01

Metabolic syndrome is correlated with increased cardiovascular risk and characterized by several factors, including visceral obesity, hypertension, insulin resistance, and dyslipidemia. Several members of a large family of nonselective cation entry channels, e.g., transient receptor potential (TRP...

An analytical and experimental investigation of natural circulation transients in a model pressurized water reactor

Energy Technology Data Exchange (ETDEWEB)

Massoud, M

1987-01-01

Natural Circulation phenomena in a simulated PWR was investigated experimentally and analytically. The experimental investigation included determination of system characteristics as well as system response to the imposed transient under symmetric and asymmetric operations. System characteristics were used to obtain correlation for heat transfer coefficient in heat exchangers, system flow resistance, and system buoyancy heat. Asymmetric transients were imposed to study flow oscillation and possible instability. The analytical investigation encompassed development of mathematical model for single-phase, steady-state and transient natural circulation as well as modification of existing model for two-phase flow analysis of phenomena such as small break LOCA, high pressure coolant injection and pump coast down. The developed mathematical model for single-phase analysis was computer coded to simulate the imposed transients. The computer program, entitled ''Symmetric and Asymmetric Analysis of Single-Phase Flow (SAS),'' were employed to simulate the imposed transients. It closely emulated the system behavior throughout the transient and subsequent steady-state. Modifications for two-phase flow analysis included addition of models for once-through steam generator and electric heater rods. Both programs are faster than real time. Off-line, they can be used for prediction and training applications while on-line they serve for simulation and signal validation. The programs can also be used to determine the sensitivity of natural circulation behavior to variation of inputs such as secondary distribution and power transients.

Transient deformational properties of high temperature alloys used in solid oxide fuel cell stacks

DEFF Research Database (Denmark)

Tadesse Molla, Tesfaye; Kwok, Kawai; Frandsen, Henrik Lund

2017-01-01

Stresses and probability of failure during operation of solid oxide fuel cells (SOFCs) is affected by the deformational properties of the different components of the SOFC stack. Though the overall stress relaxes with time during steady state operation, large stresses would normally appear through...... to describe the high temperature inelastic deformational behaviors of Crofer 22 APU used for metallic interconnects in SOFC stacks.......Stresses and probability of failure during operation of solid oxide fuel cells (SOFCs) is affected by the deformational properties of the different components of the SOFC stack. Though the overall stress relaxes with time during steady state operation, large stresses would normally appear through...... transients in operation including temporary shut downs. These stresses are highly affected by the transient creep behavior of metallic components in the SOFC stack. This study investigates whether a variation of the so-called Chaboche's unified power law together with isotropic hardening can represent...

Analysis of a high pressure ATWS [anticipated transient without scram] with very low make-up flow

International Nuclear Information System (INIS)

Wagner, K.C.

1988-10-01

A series of calculations were performed to analyze the response of General Electric Company's (GE) advanced boiling water reactor (ABWR) during an anticipated transient without scram (ATWS). This work investigated the early plant response with an assumed failure or manual inhibit of the high pressure core flooder (HPCF). Consequently, the reactor core isolation cooling (RCIC) and control rod drive (CRD) systems are the only sources of high pressure injection available to maintain core cooling. Steam leaving the reactor pressure vessel was diverted to the pressure suppression pool (PSP) via the steam line and the safety relief valves. The combination of an unscrammed core and the CRD and RCIC injection sources make this a particularly challenging transient. System energy balance calculations were performed to predict the core power and PSP heat-up rate. The amount of vessel vapor superheat and the PSP temperature were found to significantly affect the resultant core power. Consequently, detailed thermal-hydraulic calculations were performed to simulate the system response during the postulated transient. 15 refs., 15 figs., 4 tabs

HTGR-GT primary coolant transient resulting from postulated turbine deblading

International Nuclear Information System (INIS)

Cadwallader, G.J.; Deremer, R.K.

1980-11-01

The turbomachine is located within the primary coolant system of a nuclear closed cycle gas turbine plant (HTGR-GT). The deblading of the turbine can cause a rapid pressure equilibration transient that generates significant loads on other components in the system. Prediction of and design for this transient are important aspects of assuring the safety of the HTGR-GT. This paper describes the adaptation and use of the RATSAM program to analyze the rapid fluid transient throughout the primary coolant system during a spectrum of turbine deblading events. Included are discussions of (1) specific modifications and improvements to the basic RATSAM program, which is also briefly described; (2) typical results showing the expansion wave moving upstream from the debladed turbine through the primary coolant system; and (3) the effect on the transient results of different plenum volumes, flow resistances, times to deblade, and geometries that can choke the flow

HEDL experimental transient overpower program

International Nuclear Information System (INIS)

Hikido, T.; Culley, G.E.

1976-01-01

HEDL is conducting a series of experiments to evaluate the performance of Fast Flux Test Facility (FFTF) prototypic fuel pins up to the point of cladding breach. A primary objective of the program is to demonstrate the adequacy of fuel pin and Plant Protective System (PPS) designs for terminated transients. Transient tests of prototypic FFTF fuel pins previously irradiated in the Experimental Breeder Reactor-II (EBR-II) have demonstrated the adequacy of the PPS and fuel pin designs and indicate that a very substantial margin exists between PPS-terminated transients and that required to produce fuel pin cladding failure. Additional experiments are planned to extend the data base to high burnup, high fluence fuel pin specimens

Corrosion resistance of high-performance materials titanium, tantalum, zirconium

CERN Document Server

2012-01-01

Corrosion resistance is the property of a material to resist corrosion attack in a particular aggressive environment. Although titanium, tantalum and zirconium are not noble metals, they are the best choice whenever high corrosion resistance is required. The exceptionally good corrosion resistance of these high–performance metals and their alloys results from the formation of a very stable, dense, highly adherent, and self–healing protective oxide film on the metal surface. This naturally occurring oxide layer prevents chemical attack of the underlying metal surface. This behavior also means, however, that high corrosion resistance can be expected only under neutral or oxidizing conditions. Under reducing conditions, a lower resistance must be reckoned with. Only very few inorganic and organic substances are able to attack titanium, tantalum or zirconium at ambient temperature. As the extraordinary corrosion resistance is coupled with an excellent formability and weldability these materials are very valua...

Management of high current transients in the CWDD Injector 200 kV power system

International Nuclear Information System (INIS)

Carwardine, J.A.; Pile, G.; Zinneman, T.E.

1993-01-01

The injector for the Continuous Wave Deuterium Demonstrator is designed to deliver a high current CW negative deuterium ion beam at an energy of 200 keV to a Radio Frequency Quadrupole. The injector comprises a volume ion source, triode accelerator, high-power electron traps and low-energy beam transport with a single focusing solenoid. Some 75 Joules of energy are stored in stray capacitance around the high voltage system and discharged in a few microseconds following an injector breakdown. In order to limit damage to the accelerator grids, a magnetic snubber is incorporated to absorb most of the energy. Nevertheless, large current transients flow around the system as a result of an injector breakdown; these have frequently damaged power components and caused spurious behavior in many of the supporting systems. The analytical and practical approaches taken to minimize the effects of these transients are described. Injector breakdowns were simulated using an air spark gap and measurements made using standard EMC test techniques. The power circuit was modeled using an electrical simulation code; good agreement was reached between the model and measured results

Oxidation resistant high creep strength austenitic stainless steel

Science.gov (United States)

Brady, Michael P.; Pint, Bruce A.; Liu, Chain-Tsuan; Maziasz, Philip J.; Yamamoto, Yukinori; Lu, Zhao P.

2010-06-29

An austenitic stainless steel displaying high temperature oxidation and creep resistance has a composition that includes in weight percent 15 to 21 Ni, 10 to 15 Cr, 2 to 3.5 Al, 0.1 to 1 Nb, and 0.05 to 0.15 C, and that is free of or has very low levels of N, Ti and V. The alloy forms an external continuous alumina protective scale to provide a high oxidation resistance at temperatures of 700 to 800.degree. C. and forms NbC nanocarbides and a stable essentially single phase fcc austenitic matrix microstructure to give high strength and high creep resistance at these temperatures.

Study on transient hydrodynamic performance and cavitation characteristic of high-speed mixed-flow pump

International Nuclear Information System (INIS)

Chen, T; Liu, Y L; Sun, Y B; Wang, L Q; Wu, D Z

2013-01-01

In order to analyse the hydrodynamic performance and cavitation characteristic of a high-speed mixed-flow pump during transient operations, experimental studies were carried out. The transient hydrodynamic performance and cavitation characteristics of the mixed-flow pump with guide vane during start-up operation processes were tested on the pump performance test-bed. Performance tests of the pump were carried out under various inlet pressures and speed-changing operations. The real-time instantaneous external characteristics such as rotational speed, hydraulic head, flow rate, suction pressure and discharge pressure of the pump were measured. Based on the experimental results, the effect of fluid acceleration on the hydrodynamic performances and cavitation characteristics of the mixed-flow pump were analysed and evaluated

Electromagnetic transients in power cables

CERN Document Server

da Silva, Filipe Faria

2013-01-01

From the more basic concepts to the most advanced ones where long and laborious simulation models are required, Electromagnetic Transients in Power Cables provides a thorough insight into the study of electromagnetic transients and underground power cables. Explanations and demonstrations of different electromagnetic transient phenomena are provided, from simple lumped-parameter circuits to complex cable-based high voltage networks, as well as instructions on how to model the cables.Supported throughout by illustrations, circuit diagrams and simulation results, each chapter contains exercises,

Construction of a High Temporal-spectral Resolution Spectrometer for Detection of Fast Transients from Observations of the Sun at 1.4 GHz.

Science.gov (United States)

Casillas-Perez, G. A.; Jeyakumar, S.; Perez-Enriquez, R.

2014-12-01

Transients explosive events with time durations from nanoseconds to several hours, are observed in the Sun at high energy bands such as gamma ray and xray. In the radio band, several types of radio bursts are commonly detected from the ground. A few observations of the Sun in the past have also detected a new class of fast transients which are known to have short-live electromagnetic emissions with durations less than 100 ms. The mechanisms that produce such fast transiets remain unclear. Observations of such fast transients over a wide bandwidth is necessary to uderstand the underlying physical process that produce such fast transients. Due to their very large flux densities, fast radio transients can be observed at high time resolution using small antennas in combination with digital signal processing techniques. In this work we report the progress of an spectrometer that is currently in construction at the Observatorio de la Luz of the Universidad de Guanajuato. The instrument which will have the purpose of detecting solar fast radio transients, involves the use of digital devices such as FPGA and ADC cards, in addition with a receiver with high temporal-spectral resolution centered at 1.4 GHz and a pair of 2.3 m satellite dish.

Thermal shock behavior of W-ZrC/Sc2O3 composites under two different transient events by electron and laser irradiation

Science.gov (United States)

Chen, Hong-Yu; Luo, Lai-Ma; Zan, Xiang; Xu, Qiu; Tokunaga, Kazutoshi; Liu, Jia-Qin; Zhu, Xiao-Yong; Cheng, Ji-Gui; Wu, Yu-Cheng

2018-02-01

The transient thermal shock behaviors of W-ZrC/Sc2O3 composites with different ZrC contents were evaluated using transient thermal shock test by electron and laser beams. The effects of different ZrC doping contents on the surface morphology and thermal shock resistance of W-ZrC/Sc2O3 composites were then investigated. Similarity and difference between effects of electron and laser beam transient heat loading were also discussed in this study. Repeated heat loading resulted in thermal fatigue of the irradiated W-ZrC/Sc2O3 samples by thermal stress, leading to the rough surface morphologies with cracks. After different transient thermal tests, significant surface roughening, cracks, surface melting, and droplet ejection occurred. W-2vol.%Sc2O3 sample has superior thermal properties and greater resistance to surface modifications under transient thermal shock, and with the increasing ZrC content in W alloys, thermal shock resistance of W-Zr/Sc2O3 sample tends to be unsatisfied.

Modelling and transient simulation of water flow in pipelines using WANDA Transient software

Directory of Open Access Journals (Sweden)

P.U. Akpan

2017-09-01

Full Text Available Pressure transients in conduits such as pipelines are unsteady flow conditions caused by a sudden change in the flow velocity. These conditions might cause damage to the pipelines and its fittings if the extreme pressure (high or low is experienced within the pipeline. In order to avoid this occurrence, engineers usually carry out pressure transient analysis in the hydraulic design phase of pipeline network systems. Modelling and simulation of transients in pipelines is an acceptable and cost effective method of assessing this problem and finding technical solutions. This research predicts the pressure surge for different flow conditions in two different pipeline systems using WANDA Transient simulation software. Computer models were set-up in WANDA Transient for two different systems namely; the Graze experiment (miniature system and a simple main water riser system based on some initial laboratory data and system parameters. The initial laboratory data and system parameters were used for all the simulations. Results obtained from the computer model simulations compared favourably with the experimental results at Polytropic index of 1.2.

Segregated copper ratio experiment on transient stability (SeCRETS). Final Report

Energy Technology Data Exchange (ETDEWEB)

Bruzzone, P. [ed.] [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

2001-01-01

Two Nb{sub 3}Sn, steel jacketed, cable-in-conduit conductors have been manufactured with identical non-Cu cross sections and the stabilizer either included in the Nb{sub 3}Sn composite or partly segregated as copper wires. The two conductors are series connected and wound as a bifilar , single layer solenoid, assembled in the high field bore (11 T) of the SULTAN test facility. The operating current is up to 12 kA (400 A/mm{sup 2}). A transverse pulsed field is applied with {delta}B up to 2.7 T, field rate up to 180 T/s and field integral up to 530 T{sup 2}/s. In the dc test, a good agreement is found between the I{sub c} and the T{sub cs} results, both correctly scaling according to the parameters derived from the strand tests. The n-value from the V-I curve is in the range of 15. The current sharing at the high field section is correlated with a local current re-distribution, observed by arrays of miniature Hall sensors, detecting the self-field around the conductor. The ac losses results in the range of 2 to 9 Hz by gas flow calorimetry indicate coupling currents constant, n{tau}, in the range of 1.5 ms at high field, increasing by a factor of 2 with 12 kA transport current. Loss extrapolation to 0 frequency suggests that the loss curve may be not linear outside the test range, with higher n{tau} at lower field rate. The calorimetric loss estimation at the fast field transient (f=15 Hz) indicates n{tau} {approx_equal} 2 ms. The ITER plasma disruption transients have been reproduced by the pulsed coils. Due to the very low ac losses, no quench could be generated in either conductor even reducing the temperature margin below 0.2-0.3 K. Very large field transients, with integral above 100 T{sup 2}/s, are required to quench the conductors. In that range, the conductor without segregated copper has superior performance. Due to the large interstrand resistance (very low ac losses), the segregated copper has marginal contribution to the stability. No evidence of current

Production of low-affinity penicillin-binding protein by low- and high-resistance groups of methicillin-resistant Staphylococcus aureus.

Science.gov (United States)

Murakami, K; Nomura, K; Doi, M; Yoshida, T

1987-01-01

Methicillin- and cephem-resistant Staphylococcus aureus (137 strains) for which the cefazolin MICs are at least 25 micrograms/ml could be classified into low-resistance (83% of strains) and high-resistance (the remaining 17%) groups by the MIC of flomoxef (6315-S), a 1-oxacephalosporin. The MICs were less than 6.3 micrograms/ml and more than 12.5 micrograms/ml in the low- and high-resistance groups, respectively. All strains produced penicillin-binding protein 2' (PBP 2'), which has been associated with methicillin resistance and which has very low affinity for beta-lactam antibiotics. Production of PBP 2' was regulated differently in low- and high-resistance strains. With penicillinase-producing strains of the low-resistance group, cefazolin, cefamandole, and cefmetazole induced PBP 2' production about 5-fold, while flomoxef induced production 2.4-fold or less. In contrast, penicillinase-negative variants of low-resistance strains produced PBP 2' constitutively in large amounts and induction did not occur. With high-resistance strains, flomoxef induced PBP 2' to an extent similar to that of cefazolin in both penicillinase-producing and -negative strains, except for one strain in which the induction did not occur. The amount of PBP 2' induced by beta-lactam antibiotics in penicillinase-producing strains of the low-resistance group correlated well with resistance to each antibiotic. Large amounts of PBP 2' in penicillinase-negative variants of the low-resistance group did not raise the MICs of beta-lactam compounds, although these strains were more resistant when challenged with flomoxef for 2 h. Different regulation of PBP 2' production was demonstrated in the high- and low-resistance groups, and factor(s) other than PBP 2' were suggested to be involved in the methicillin resistance of high-resistance strains. Images PMID:3499861

NOx, Soot, and Fuel Consumption Predictions under Transient Operating Cycle for Common Rail High Power Density Diesel Engines

Directory of Open Access Journals (Sweden)

N. H. Walke

2016-01-01

Full Text Available Diesel engine is presently facing the challenge of controlling NOx and soot emissions on transient cycles, to meet stricter emission norms and to control emissions during field operations. Development of a simulation tool for NOx and soot emissions prediction on transient operating cycles has become the most important objective, which can significantly reduce the experimentation time and cost required for tuning these emissions. Hence, in this work, a 0D comprehensive predictive model has been formulated with selection and coupling of appropriate combustion and emissions models to engine cycle models. Selected combustion and emissions models are further modified to improve their prediction accuracy in the full operating zone. Responses of the combustion and emissions models have been validated for load and “start of injection” changes. Model predicted transient fuel consumption, air handling system parameters, and NOx and soot emissions are in good agreement with measured data on a turbocharged high power density common rail engine for the “nonroad transient cycle” (NRTC. It can be concluded that 0D models can be used for prediction of transient emissions on modern engines. How the formulated approach can also be extended to transient emissions prediction for other applications and fuels is also discussed.

Transient pool boiling heat transfer due to increasing heat inputs in subcooled water at high pressures

International Nuclear Information System (INIS)

Fukuda, K.; Shiotsu, M.; Sakurai, A.

1995-01-01

Understanding of transient boiling phenomenon caused by increasing heat inputs in subcooled water at high pressures is necessary to predict correctly a severe accident due to a power burst in a water-cooled nuclear reactor. Transient maximum heat fluxes, q max , on a 1.2 mm diameter horizontal cylinder in a pool of saturated and subcooled water for exponential heat inputs, q o e t/T , with periods, τ, ranging from about 2 ms to 20 s at pressures from atmospheric up to 2063 kPa for water subcoolings from 0 to about 80 K were measured to obtain the extended data base to investigate the effect of high subcoolings on steady-state and transient maximum heat fluxes, q max . Two main mechanisms of q max exist depending on the exponential periods at low subcoolings. One is due to the time lag of the hydrodynamic instability which starts at steady-state maximum heat flux on fully developed nucleate boiling (FDNB), and the other is due to the heterogenous spontaneous nucleations (HSN) in flooded cavities which coexist with vapor bubbles growing up from active cavities. The shortest period corresponding to the maximum q max for long period range belonging to the former mechanism becomes longer and the q max mechanism for long period range shifts to that due the HSN on FDNB with the increase of subcooling and pressure. The longest period corresponding to the minimum q max for the short period range belonging to the latter mechanism becomes shorter with the increase in saturated pressure. On the contrary, the longest period becomes longer with the increase in subcooling at high pressures. Correlations for steady-state and transient maximum heat fluxes were presented for a wide range of pressure and subcooling

Transient pool boiling heat transfer due to increasing heat inputs in subcooled water at high pressures

Energy Technology Data Exchange (ETDEWEB)

Fukuda, K. [Kobe Univ. of Mercantile Marine (Japan); Shiotsu, M.; Sakurai, A. [Kyoto Univ. (Japan)

1995-09-01

Understanding of transient boiling phenomenon caused by increasing heat inputs in subcooled water at high pressures is necessary to predict correctly a severe accident due to a power burst in a water-cooled nuclear reactor. Transient maximum heat fluxes, q{sub max}, on a 1.2 mm diameter horizontal cylinder in a pool of saturated and subcooled water for exponential heat inputs, q{sub o}e{sup t/T}, with periods, {tau}, ranging from about 2 ms to 20 s at pressures from atmospheric up to 2063 kPa for water subcoolings from 0 to about 80 K were measured to obtain the extended data base to investigate the effect of high subcoolings on steady-state and transient maximum heat fluxes, q{sub max}. Two main mechanisms of q{sub max} exist depending on the exponential periods at low subcoolings. One is due to the time lag of the hydrodynamic instability which starts at steady-state maximum heat flux on fully developed nucleate boiling (FDNB), and the other is due to the heterogenous spontaneous nucleations (HSN) in flooded cavities which coexist with vapor bubbles growing up from active cavities. The shortest period corresponding to the maximum q{sub max} for long period range belonging to the former mechanism becomes longer and the q{sub max}mechanism for long period range shifts to that due the HSN on FDNB with the increase of subcooling and pressure. The longest period corresponding to the minimum q{sub max} for the short period range belonging to the latter mechanism becomes shorter with the increase in saturated pressure. On the contrary, the longest period becomes longer with the increase in subcooling at high pressures. Correlations for steady-state and transient maximum heat fluxes were presented for a wide range of pressure and subcooling.

Development of a 1 GS/s high-resolution transient recorder

CERN Document Server

Bartknecht, S; Herrmann, F; Königsmann, K; Lauser, L; Schill, C; Schopferer, S; Wollny, H

2009-01-01

With present-day detectors in high energy physics one is often faced with short analog pulses of a few nanoseconds length which may cover large dynamic ranges. In many experiments both amplitude and timing information have to be measured with high accuracy. Additionally, the data rate per readout channel can reach several MHz, which makes high demands on the separation of pile-up pulses. For such applications we have built the GANDALF transient recorder with a resolution of 12bit@1GS/s and an analog bandwidth of 500 MHz. Signals are digitized and processed by fast algorithms to extract pulse arrival times and amplitudes in real-time and to generate experiment trigger signals. With up to 16 analog channels, deep memories and a high data rate interface, this 6U-VME64x/VXS module is not only a dead-time free digitization unit but also has huge numerical capabilities provided by the implementation of a Virtex5-SXT FPGA. Fast algorithms implemented in the FPGA may be used to disentangle possible pile-up pulses and...

Resistance Exercise Attenuates High-Fructose, High-Fat-Induced Postprandial Lipemia

Directory of Open Access Journals (Sweden)

Jessie R. Wilburn

2015-01-01

Full Text Available Introduction Meals rich in both fructose and fat are commonly consumed by many Americans, especially young men, which can produce a significant postprandial lipemic response. Increasing evidence suggests that aerobic exercise can attenuate the postprandial increase in plasma triacylglycerols (TAGs in response to a high-fat or a high-fructose meal. However, it is unknown if resistance exercise can dampen the postprandial lipemic response to a meal rich in both fructose and fat. Methods Eight apparently healthy men (Mean ± SEM; age = 27 ± 2 years participated in a crossover study to examine the effects of acute resistance exercise on next-day postprandial lipemia resulting from a high-fructose, high-fat meal. Participants completed three separate two-day conditions in a random order: (1 EX-COMP: a full-body weightlifting workout with the provision of additional kilocalories to compensate for the estimated net energy cost of exercise on day 1, followed by the consumption of a high-fructose, high-fat liquid test meal the next morning (day 2 (~600 kcal and the determination of the plasma glucose, lactate, insulin, and TAG responses during a six-hour postprandial period; (2 EX-DEF: same condition as EX-COMP but without exercise energy compensation on day 1; and (3 CON: no exercise control. Results The six-hour postprandial plasma insulin and lactate responses did not differ between conditions. However, the postprandial plasma TAG concentrations were 16.5% and 24.4% lower for EX-COMP (551.0 ± 80.5 mg/dL x 360 minutes and EX-DEF (499.4 ± 73.5 mg/dL x 360 minutes, respectively, compared to CON (660.2 ± 95.0 mg/dL x 360 minutes ( P < 0.05. Conclusions A single resistance exercise bout, performed ~15 hours prior to a high-fructose, high-fat meal, attenuated the postprandial TAG response, as compared to a no-exercise control condition, in healthy, resistance-trained men.

Resistance Exercise Attenuates High-Fructose, High-Fat-Induced Postprandial Lipemia.

Science.gov (United States)

Wilburn, Jessie R; Bourquin, Jeffrey; Wysong, Andrea; Melby, Christopher L

2015-01-01

Meals rich in both fructose and fat are commonly consumed by many Americans, especially young men, which can produce a significant postprandial lipemic response. Increasing evidence suggests that aerobic exercise can attenuate the postprandial increase in plasma triacylglycerols (TAGs) in response to a high-fat or a high-fructose meal. However, it is unknown if resistance exercise can dampen the postprandial lipemic response to a meal rich in both fructose and fat. Eight apparently healthy men (Mean ± SEM; age = 27 ± 2 years) participated in a crossover study to examine the effects of acute resistance exercise on next-day postprandial lipemia resulting from a high-fructose, high-fat meal. Participants completed three separate two-day conditions in a random order: (1) EX-COMP: a full-body weightlifting workout with the provision of additional kilocalories to compensate for the estimated net energy cost of exercise on day 1, followed by the consumption of a high-fructose, high-fat liquid test meal the next morning (day 2) (~600 kcal) and the determination of the plasma glucose, lactate, insulin, and TAG responses during a six-hour postprandial period; (2) EX-DEF: same condition as EX-COMP but without exercise energy compensation on day 1; and (3) CON: no exercise control. The six-hour postprandial plasma insulin and lactate responses did not differ between conditions. However, the postprandial plasma TAG concentrations were 16.5% and 24.4% lower for EX-COMP (551.0 ± 80.5 mg/dL × 360 minutes) and EX-DEF (499.4 ± 73.5 mg/dL × 360 minutes), respectively, compared to CON (660.2 ± 95.0 mg/dL × 360 minutes) (P < 0.05). A single resistance exercise bout, performed ~15 hours prior to a high-fructose, high-fat meal, attenuated the postprandial TAG response, as compared to a no-exercise control condition, in healthy, resistance-trained men.

Calculation of Lightning Transient Responses on Wind Turbine Towers

Directory of Open Access Journals (Sweden)

Xiaoqing Zhang

2013-01-01

Full Text Available An efficient method is proposed in this paper for calculating lightning transient responses on wind turbine towers. In the proposed method, the actual tower body is simplified as a multiconductor grid in the shape of cylinder. A set of formulas are given for evaluating the circuit parameters of the branches in the multiconductor grid. On the basis of the circuit parameters, the multiconductor grid is further converted into an equivalent circuit. The circuit equation is built in frequency-domain to take into account the effect of the frequency-dependent characteristic of the resistances and inductances on lightning transients. The lightning transient responses can be obtained by using the discrete Fourier transform with exponential sampling to take the inverse transform of the frequency-domain solution of the circuit equation. A numerical example has been given for examining the applicability of the proposed method.

Drought resistance in early and late secondary successional species from a tropical dry forest: the interplay between xylem resistance to embolism, sapwood water storage and leaf shedding.

Science.gov (United States)

Pineda-García, Fernando; Paz, Horacio; Meinzer, Frederick C

2013-02-01

The mechanisms of drought resistance that allow plants to successfully establish at different stages of secondary succession in tropical dry forests are not well understood. We characterized mechanisms of drought resistance in early and late-successional species and tested whether risk of drought differs across sites at different successional stages, and whether early and late-successional species differ in resistance to experimentally imposed soil drought. The microenvironment in early successional sites was warmer and drier than in mature forest. Nevertheless, successional groups did not differ in resistance to soil drought. Late-successional species resisted drought through two independent mechanisms: high resistance of xylem to embolism, or reliance on high stem water storage capacity. High sapwood water reserves delayed the effects of soil drying by transiently decoupling plant and soil water status. Resistance to soil drought resulted from the interplay between variations in xylem vulnerability to embolism, reliance on sapwood water reserves and leaf area reduction, leading to a tradeoff of avoidance against tolerance of soil drought, along which successional groups were not differentiated. Overall, our data suggest that ranking species' performance under soil drought based solely on xylem resistance to embolism may be misleading, especially for species with high sapwood water storage capacity. © 2012 Blackwell Publishing Ltd.

Creep resistant high temperature martensitic steel

Energy Technology Data Exchange (ETDEWEB)

Hawk, Jeffrey A.; Jablonski, Paul D.; Cowen, Christopher J.

2017-01-31

The disclosure provides a creep resistant alloy having an overall composition comprised of iron, chromium, molybdenum, carbon, manganese, silicon, nickel, vanadium, niobium, nitrogen, tungsten, cobalt, tantalum, boron, copper, and potentially additional elements. In an embodiment, the creep resistant alloy has a molybdenum equivalent Mo(eq) from 1.475 to 1.700 wt. % and a quantity (C+N) from 0.145 to 0.205. The overall composition ameliorates sources of microstructural instability such as coarsening of M.sub.23C.sub.6carbides and MX precipitates, and mitigates or eliminates Laves and Z-phase formation. A creep resistant martensitic steel may be fabricated by preparing a melt comprised of the overall composition followed by at least austenizing and tempering. The creep resistant alloy exhibits improved high-temperature creep strength in the temperature environment of around 650.degree. C.

Creep resistant high temperature martensitic steel

Science.gov (United States)

Hawk, Jeffrey A.; Jablonski, Paul D.; Cowen, Christopher J.

2015-11-13

The disclosure provides a creep resistant alloy having an overall composition comprised of iron, chromium, molybdenum, carbon, manganese, silicon, nickel, vanadium, niobium, nitrogen, tungsten, cobalt, tantalum, boron, and potentially additional elements. In an embodiment, the creep resistant alloy has a molybdenum equivalent Mo(eq) from 1.475 to 1.700 wt. % and a quantity (C+N) from 0.145 to 0.205. The overall composition ameliorates sources of microstructural instability such as coarsening of M.sub.23C.sub.6 carbides and MX precipitates, and mitigates or eliminates Laves and Z-phase formation. A creep resistant martensitic steel may be fabricated by preparing a melt comprised of the overall composition followed by at least austenizing and tempering. The creep resistant alloy exhibits improved high-temperature creep strength in the temperature environment of around 650.degree. C.

Optimizing transient processes with AVL-GCA for a highly flexible gasoline engine; Optimierung transienter Vorgaenge mit AVL-GCA an einem Otto-Motor hoher Flexibilitaet

Energy Technology Data Exchange (ETDEWEB)

Leifert, Thomas; Moreno Nevado, Fernando; Fairbrother, Robert; Prevedel, Kurt [AVL List GmbH, Graz (Austria)

2011-07-01

Optimizing the dynamic operation of a gasoline engine with high flexibility by means of AVL-GCA. Downsizing and Downspeeding are considered being the most promising approaches to significantly reduce CO{sub 2} emission. Because of synergy effects between its technologies, downsized Turbocharged Gasoline Direct Injection (TGDI) engines have the highest potential for fuel economy. The key for high market penetration of such concepts requires customer acceptance and this is closely linked to driver satisfaction. For the drivability rating of vehicles fitted with turbocharged engines, tip-in behavior is of paramount importance. A combined combustion analysis and gas-exchange analysis was performed with AVL GCA (Gas exchange and Combustion Analysis) on a ''beyond-state-of-the-art'' TGDI engine, namely a variable compression ratio engine featuring MCE-5 VCRi technology. With variable compression ratio and 2-stage boosting this engine features an unusually high level of flexibility. Therefore the analysis is used to examine the thermodynamic processes taking place in the cylinders not only in steady state operation but also under highly transient boundary conditions and on a ''cycle-by-cycle'' basis in order to examine hints for optimizing transient response. An established numerical approach for analysis was applied to measurement data acquired on an engine dynamometer thanks to a dedicated measurement chain that will be described in detail. (orig.)

High chlorpyrifos resistance in Culex pipiens mosquitoes: strong synergy between resistance genes

Science.gov (United States)

Alout, H; Labbé, P; Berthomieu, A; Makoundou, P; Fort, P; Pasteur, N; Weill, M

2016-01-01

We investigated the genetic determinism of high chlorpyrifos resistance (HCR), a phenotype first described in 1999 in Culex pipiens mosquitoes surviving chlorpyrifos doses ⩾1 mg l−1 and more recently found in field samples from Tunisia, Israel or Indian Ocean islands. Through chlorpyrifos selection, we selected several HCR strains that displayed over 10 000-fold resistance. All strains were homozygous for resistant alleles at two main loci: the ace-1 gene, with the resistant ace-1R allele expressing the insensitive G119S acetylcholinesterase, and a resistant allele of an unknown gene (named T) linked to the sex and ace-2 genes. We constructed a strain carrying only the T-resistant allele and studied its resistance characteristics. By crossing this strain with strains harboring different alleles at the ace-1 locus, we showed that the resistant ace-1R and the T alleles act in strong synergy, as they elicited a resistance 100 times higher than expected from a simple multiplicative effect. This effect was specific to chlorpyrifos and parathion and was not affected by synergists. We also examined how HCR was expressed in strains carrying other ace-1-resistant alleles, such as ace-1V or the duplicated ace-1D allele, currently spreading worldwide. We identified two major parameters that influenced the level of resistance: the number and the nature of the ace-1-resistant alleles and the number of T alleles. Our data fit a model that predicts that the T allele acts by decreasing chlorpyrifos concentration in the compartment targeted in insects. PMID:26463842

A Rapid, Highly Efficient and Economical Method of Agrobacterium-Mediated In planta Transient Transformation in Living Onion Epidermis

Science.gov (United States)

Xu, Kedong; Huang, Xiaohui; Wu, Manman; Wang, Yan; Chang, Yunxia; Liu, Kun; Zhang, Ju; Zhang, Yi; Zhang, Fuli; Yi, Liming; Li, Tingting; Wang, Ruiyue; Tan, Guangxuan; Li, Chengwei

2014-01-01

Transient transformation is simpler, more efficient and economical in analyzing protein subcellular localization than stable transformation. Fluorescent fusion proteins were often used in transient transformation to follow the in vivo behavior of proteins. Onion epidermis, which has large, living and transparent cells in a monolayer, is suitable to visualize fluorescent fusion proteins. The often used transient transformation methods included particle bombardment, protoplast transfection and Agrobacterium-mediated transformation. Particle bombardment in onion epidermis was successfully established, however, it was expensive, biolistic equipment dependent and with low transformation efficiency. We developed a highly efficient in planta transient transformation method in onion epidermis by using a special agroinfiltration method, which could be fulfilled within 5 days from the pretreatment of onion bulb to the best time-point for analyzing gene expression. The transformation conditions were optimized to achieve 43.87% transformation efficiency in living onion epidermis. The developed method has advantages in cost, time-consuming, equipment dependency and transformation efficiency in contrast with those methods of particle bombardment in onion epidermal cells, protoplast transfection and Agrobacterium-mediated transient transformation in leaf epidermal cells of other plants. It will facilitate the analysis of protein subcellular localization on a large scale. PMID:24416168

Cardiac Outcomes After Ischemic Stroke or Transient Ischemic Attack: Effects of Pioglitazone in Patients With Insulin Resistance Without Diabetes Mellitus.

Science.gov (United States)

Young, Lawrence H; Viscoli, Catherine M; Curtis, Jeptha P; Inzucchi, Silvio E; Schwartz, Gregory G; Lovejoy, Anne M; Furie, Karen L; Gorman, Mark J; Conwit, Robin; Abbott, J Dawn; Jacoby, Daniel L; Kolansky, Daniel M; Pfau, Steven E; Ling, Frederick S; Kernan, Walter N

2017-05-16

Insulin resistance is highly prevalent among patients with atherosclerosis and is associated with an increased risk for myocardial infarction (MI) and stroke. The IRIS trial (Insulin Resistance Intervention after Stroke) demonstrated that pioglitazone decreased the composite risk for fatal or nonfatal stroke and MI in patients with insulin resistance without diabetes mellitus, after a recent ischemic stroke or transient ischemic attack. The type and severity of cardiac events in this population and the impact of pioglitazone on these events have not been described. We performed a secondary analysis of the effects of pioglitazone, in comparison with placebo, on acute coronary syndromes (MI and unstable angina) among IRIS participants. All potential acute coronary syndrome episodes were adjudicated in a blinded fashion by an independent clinical events committee. The study cohort was composed of 3876 IRIS participants, mean age 63 years, 65% male, 89% white race, and 12% with a history of coronary artery disease. Over a median follow-up of 4.8 years, there were 225 acute coronary syndrome events, including 141 MIs and 84 episodes of unstable angina. The MIs included 28 (19%) with ST-segment elevation. The majority of MIs were type 1 (94, 65%), followed by type 2 (45, 32%). Serum troponin was 10× to 100× upper limit of normal in 49 (35%) and >100× upper limit of normal in 39 (28%). Pioglitazone reduced the risk of acute coronary syndrome (hazard ratio, 0.71; 95% confidence interval, 0.54-0.94; P =0.02). Pioglitazone also reduced the risk of type 1 MI (hazard ratio, 0.62; 95% confidence interval, 0.40-0.96; log-rank P =0.03), but not type 2 MI (hazard ratio, 1.05; 95% confidence interval, 0.58-1.91; P =0.87). Similarly, pioglitazone reduced the risk of large MIs with serum troponin >100× upper limit of normal (hazard ratio, 0.44; 95% confidence interval, 0.22-0.87; P =0.02), but not smaller MIs. Among patients with insulin resistance without diabetes mellitus

Vivitron 1995, transient voltage simulation, high voltage insulator tests, electric field calculation

International Nuclear Information System (INIS)

Frick, G.; Osswald, F.; Heusch, B.

1996-01-01

Preliminary investigations showed clearly that, because of the discrete electrode structure of the Vivitron, important overvoltage leading to insulator damage can appear in case of a spark. The first high voltage tests showed damage connected with such events. This fact leads to a severe voltage limitation. This work describes, at first, studies made to understand the effects of transients and the associated over-voltage appearing in the Vivitron. Then we present the high voltage tests made with full size Vivitron components using the CN 6 MV machine as a pilot machine. Extensive field calculations were made. These involve simulations of static stresses and transient overvoltages, on insulating boards and electrodes. This work gave us the solutions for arrangements and modifications in the machine. After application, the Vivitron runs now without any sparks and damage at 20 MV. In the same manner, we tested column insulators of a new design and so we will find out how to get to higher voltages. Electric field calculation around the tie bars connecting the discrete electrodes together showed field enhancements when the voltages applied on the discrete electrodes are not equally distributed. This fact is one of the sources of discharges and voltage limitations. A scenario of a spark event is described and indications are given how to proceed towards higher voltages, in the 30 MV range. (orig.)

Radiation of transient high-current arcs: energy measurements in the optical range

International Nuclear Information System (INIS)

Bauchire, J M; Hong, D; Rabat, H; Riquel, G

2012-01-01

When no protection is used, the radiation emitted by a high-power electric arc can be dangerous for the eyes and the skin of a person. To ensure effective protection, it is first necessary to know the energy emitted by such arcs. The aim of our work was to experimentally determine the energy emitted by high-current (from 4 to 40 kA) transient arcs, for two different (10 cm and 2 m) lengths and for electrodes in copper or steel. These experiments enabled the radiative energy of the arcs to be quantified and also showed the influence of metal vapors in the spectral distribution of the radiation.

Conventional P-ω/Q-V Droop Control in Highly Resistive Line of Low-Voltage Converter-Based AC Microgrid

Directory of Open Access Journals (Sweden)

Xiaochao Hou

2016-11-01

Full Text Available In low-voltage converter-based alternating current (AC microgrids with resistive distribution lines, the P-V droop with Q-f boost (VPD/FQB is the most common method for load sharing. However, it cannot achieve the active power sharing proportionally. To overcome this drawback, the conventional P-ω/Q-V droop control is adopted in the low-voltage AC microgrid. As a result, the active power sharing among the distributed generators (DGs is easily obtained without communication. More importantly, this study clears up the previous misunderstanding that conventional P-ω/Q-V droop control is only applicable to microgrids with highly inductive lines, and lays a foundation for the application of conventional droop control under different line impedances. Moreover, in order to guarantee the accurate reactive power sharing, a guide for designing Q-V droop gains is given, and virtual resistance is adopted to shape the desired output impedance. Finally, the effects of power sharing and transient response are verified through simulations and experiments in converter-based AC Microgrid.

Method of separate determination of high-ohmic sample resistance and contact resistance

Directory of Open Access Journals (Sweden)

Vadim A. Golubiatnikov

2015-09-01

Full Text Available A method of separate determination of two-pole sample volume resistance and contact resistance is suggested. The method is applicable to high-ohmic semiconductor samples: semi-insulating gallium arsenide, detector cadmium-zinc telluride (CZT, etc. The method is based on near-contact region illumination by monochromatic radiation of variable intensity from light emitting diodes with quantum energies exceeding the band gap of the material. It is necessary to obtain sample photo-current dependence upon light emitting diode current and to find the linear portion of this dependence. Extrapolation of this linear portion to the Y-axis gives the cut-off current. As the bias voltage is known, it is easy to calculate sample volume resistance. Then, using dark current value, one can determine the total contact resistance. The method was tested for n-type semi-insulating GaAs. The contact resistance value was shown to be approximately equal to the sample volume resistance. Thus, the influence of contacts must be taken into account when electrophysical data are analyzed.

Frictional resistance of adiabatic two-phase flow in narrow rectangular duct under rolling conditions

International Nuclear Information System (INIS)

Xing, Dianchuan; Yan, Changqi; Sun, Licheng; Jin, Guangyuan; Tan, Sichao

2013-01-01

Highlights: ► Two-phase flow frictional resistance in narrow duct in rolling is studied. ► Frictional resistance behaviors in rolling are divided into three regions. ► Transient frictional pressure drop fluctuates synchronously with rolling motion. ► Conventional correlations are evaluated against experimental data in rolling motion. ► New correlation for transient frictional resistance in rolling motion is developed. - Abstract: Frictional resistance of air-water two-phase flow in a narrow rectangular duct subjected to rolling motion was investigated experimentally. Time-averaged and transient frictional pressure drop under rolling condition were compared with conventional correlation in laminar flow region (Re l l ⩽ 1400) and turbulent flow region (Re l > 1400) respectively. The result shows that, despite no influence on time-averaged frictional resistance, rolling motion does induce periodical fluctuation of the pressure drop in laminar and transition flow regions. Transient frictional pressure drop fluctuates synchronously with the rolling motion both in laminar and in transition flow region, while it is nearly invariable in turbulent flow region. The fluctuation amplitude of the Relative frictional pressure gradient decreases with the increasing of the superficial velocities. Lee and Lee (2002) correlation and Chisholm (1967) correlation could satisfactorily predict time-averaged frictional pressure drop under rolling conditions, whereas poorly predict the transient frictional pressure drop when it fluctuates periodically. A new correlation with better accuracy for predicting the transient frictional pressure drop in rolling motion is achieved by modifying the Chisholm (1967) correlation on the basis of analyzing the present experimental results with a great number of data points

Transient plant transformation mediated by Agrobacterium tumefaciens: Principles, methods and applications.

Science.gov (United States)

Krenek, Pavel; Samajova, Olga; Luptovciak, Ivan; Doskocilova, Anna; Komis, George; Samaj, Jozef

2015-11-01

Agrobacterium tumefaciens is widely used as a versatile tool for development of stably transformed model plants and crops. However, the development of Agrobacterium based transient plant transformation methods attracted substantial attention in recent years. Transient transformation methods offer several applications advancing stable transformations such as rapid and scalable recombinant protein production and in planta functional genomics studies. Herein, we highlight Agrobacterium and plant genetics factors affecting transfer of T-DNA from Agrobacterium into the plant cell nucleus and subsequent transient transgene expression. We also review recent methods concerning Agrobacterium mediated transient transformation of model plants and crops and outline key physical, physiological and genetic factors leading to their successful establishment. Of interest are especially Agrobacterium based reverse genetics studies in economically important crops relying on use of RNA interference (RNAi) or virus-induced gene silencing (VIGS) technology. The applications of Agrobacterium based transient plant transformation technology in biotech industry are presented in thorough detail. These involve production of recombinant proteins (plantibodies, vaccines and therapeutics) and effectoromics-assisted breeding of late blight resistance in potato. In addition, we also discuss biotechnological potential of recombinant GFP technology and present own examples of successful Agrobacterium mediated transient plant transformations. Copyright © 2015 Elsevier Inc. All rights reserved.

Stability of High Temperature Standard Platinum Resistance Thermometers at High Temperatures

OpenAIRE

Y. A. ABDELAZIZ; F. M. MEGAHED

2010-01-01

An investigation of the stability of high temperature standard platinum resistance thermometers HTSPRTs has been carried out for two different designs thermometers (with nominal resistance 0.25 Ω and 2.5 Ω) from two different suppliers. The thermometers were heated for more than 160 hours at temperatures above 960 0C using a vertical furnace with a ceramic block. A study was made of the influence of the heat treatment on the stability of the resistance at the triple point of water, and on the...

Transient voltage sharing in series-coupled high voltage switches

Directory of Open Access Journals (Sweden)

Editorial Office

1992-07-01

Full Text Available For switching voltages in excess of the maximum blocking voltage of a switching element (for example, thyristor, MOSFET or bipolar transistor such elements are often coupled in series - and additional circuitry has to be provided to ensure equal voltage sharing. Between each such series element and system ground there is a certain parasitic capacitance that may draw a significant current during high-speed voltage transients. The "open" switch is modelled as a ladder network. Analy­sis reveals an exponential progression in the distribution of the applied voltage across the elements. Overstressing thus oc­curs in some of the elements at levels of the total voltage that are significantly below the design value. This difficulty is overcome by grading the voltage sharing circuitry, coupled in parallel with each element, in a prescribed manner, as set out here.

Genetic Determinants of High-Level Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus.

Science.gov (United States)

Pardos de la Gandara, Maria; Borges, Vitor; Chung, Marilyn; Milheiriço, Catarina; Gomes, João Paulo; de Lencastre, Herminia; Tomasz, Alexander

2018-06-01

Methicillin-resistant Staphylococcus aureus (MRSA) strains carry either a mecA - or a mecC -mediated mechanism of resistance to beta-lactam antibiotics, and the phenotypic expression of resistance shows extensive strain-to-strain variation. In recent communications, we identified the genetic determinants associated with the stringent stress response that play a major role in the antibiotic resistant phenotype of the historically earliest "archaic" clone of MRSA and in the mecC -carrying MRSA strain LGA251. Here, we sought to test whether or not the same genetic determinants also contribute to the resistant phenotype of highly and homogeneously resistant (H*R) derivatives of a major contemporary MRSA clone, USA300. We found that the resistance phenotype was linked to six genes ( fruB , gmk , hpt , purB , prsA , and relA ), which were most frequently targeted among the analyzed 20 H*R strains (one mutation per clone in 19 of the 20 H*R strains). Besides the strong parallels with our previous findings (five of the six genes matched), all but one of the repeatedly targeted genes were found to be linked to guanine metabolism, pointing to the key role that this pathway plays in defining the level of antibiotic resistance independent of the clonal type of MRSA. Copyright © 2018 American Society for Microbiology.

Effects of a parallel resistor on electrical characteristics of a piezoelectric transformer in open-circuit transient state.

Science.gov (United States)

Chang, Kuo-Tsai

2007-01-01

This paper investigates electrical transient characteristics of a Rosen-type piezoelectric transformer (PT), including maximum voltages, time constants, energy losses and average powers, and their improvements immediately after turning OFF. A parallel resistor connected to both input terminals of the PT is needed to improve the transient characteristics. An equivalent circuit for the PT is first given. Then, an open-circuit voltage, involving a direct current (DC) component and an alternating current (AC) component, and its related energy losses are derived from the equivalent circuit with initial conditions. Moreover, an AC power control system, including a DC-to-AC resonant inverter, a control switch and electronic instruments, is constructed to determine the electrical characteristics of the OFF transient state. Furthermore, the effects of the parallel resistor on the transient characteristics at different parallel resistances are measured. The advantages of adding the parallel resistor also are discussed. From the measured results, the DC time constant is greatly decreased from 9 to 0.04 ms by a 10 k(omega) parallel resistance under open output.

Development of radiation-resisting high molecular-weight materials

International Nuclear Information System (INIS)

Nakagawa, Tsutomu

1976-01-01

The excellent radiation-resisting polyvinyl chloride developed at the opportunity of the research on the relationships between the protection of living body and the polymer-technological protection from radiation is reviewed. The report is divided into four main parts, namely 1) the change in the molecular arrangement of market-available, high molecular-weight materials by gamma-ray irradiation, 2) the protection of high molecular-weight materials from radiation, 3) the relationships between the biological radiation-protective substances and the change to radiation-resisting property of synthesized high molecular-weight substances, and 4) the development of the radiation-resisting high molecular-weight materials as metal-collecting agents. Attention is paid to the polyvinyl chloride having N-methyl-dithio-carbamate radical (PMD), synthesized by the author et. al., that has excellent radiation-resisting property. PMD has some possibility to form thiol- and amino-radicals necessary to protect living things from radiation. It is believed that the protection effects of N-methyl-dithio-carbamate radical are caused by the relatively stable S radical produced by the energy transfer. PMD film is suitable for the irradiation of foods, because it hardly changes the permeability of oxygen and carbon dioxide. PMD produces mercaptide or chelate. A new metal-collecting agent (PSDC) having reactivity with the metallic ions with radiation-resisting property was developed, which is derived from polyvinyl chloride and sodium N-methyl-N-carboxy-methyl-dithio-carbamate. (Iwakiri, K.)

ORTAP: a nuclear steam supply system simulation for the dynamic analysis of high temperature gas cooled reactor transients

International Nuclear Information System (INIS)

Cleveland, J.C.; Hedrick, R.A.; Ball, S.J.; Delene, J.G.

1977-01-01

ORTAP was developed to predict the dynamic behavior of the high temperature gas cooled reactor (HTGR) Nuclear Steam Supply System for normal operational transients and postulated accident conditions. It was developed for the Nuclear Regulatory Commission (NRC) as an independent means of obtaining conservative predictions of the transient response of HTGRs over a wide range of conditions. The approach has been to build sufficient detail into the component models so that the coupling between the primary and secondary systems can be accurately represented and so that transients which cover a wide range of conditions can be simulated. System components which are modeled in ORTAP include the reactor core, a typical reheater and steam generator module, a typical helium circulator and circulator turbine and the turbine generator plant. The major plant control systems are also modeled. Normal operational transients which can be analyzed with ORTAP include reactor start-up and shutdown, normal and rapid load changes. Upset transients which can be analyzed with ORTAP include reactor trip, turbine trip and sudden reduction in feedwater flow. ORTAP has also been used to predict plant response to emergency or faulted conditions such as primary system depressurization, loss of primary coolant flow and uncontrolled removal of control poison from the reactor core

Charge deep-level transient spectroscopy study of high-energy-electron-beam-irradiated hydrogenated amorphous silicon

NARCIS (Netherlands)

Klaver, A.; Nádaždy, V.; Zeman, M.; Swaaiij, R.A.C.M.M.

2006-01-01

We present a study of changes in the defect density of states in hydrogenated amorphous silicon (a-Si:H) due to high-energy electron irradiation using charged deep-level transient spectroscopy. It was found that defect states near the conduction band were removed, while in other band gap regions the

Single-event transients (SET) in analog circuits

International Nuclear Information System (INIS)

Chen Panxun; Zhou Kaiming

2006-01-01

A new phenomenon of single- event upset is introduced. The transient signal is produced in the output of analog circuits after a heavy ion strikes. The transient upset can influence the circuit connected with the output of analog circuits. For example, the output of operational amplifier can be connected with the input of a digital counter, and the pulse of sufficiently high transient output induced by an ion can increase counts of the counter. On the other hand, the transient voltage signal at the output of analog circuits can change the stage of other circuits. (authors)

500 MHz transient digitizers based on GaAs CCDs

International Nuclear Information System (INIS)

Bryman, D.A.; Constable, M.; Cresswell, J.V.; Daviel, A.; LeNoble, M.; Mildenberger, J.; Poutissou, R.

1996-11-01

A system of 500 MHz transient digitizers based on gallium arsenide resistive gate charged coupled devices has been developed for an experiment studying rare K decays. CCDs with dynamic range of 8-bits and 128 or 320 pixels are used as analog pipelines. The CCD's are driven by a single phase transport system. Data readout and manipulation occurs at 15.6 MHz. (authors)

Mapping localised freshwater anomalies in the brackish paleo-lake sediments of the Machile–Zambezi Basin with transient electromagnetic sounding, geoelectrical imaging and induced polarisation

DEFF Research Database (Denmark)

Chongo, Mkhuzo; Christiansen, Anders Vest; Fiandaca, Gianluca

2015-01-01

A recent airborne TEM survey in the Machile–Zambezi Basin of south western Zambia revealed high electrical resistivity anomalies (around 100 Ωm) in a low electrical resistivity (below 13 Ωm) background. The near surface (0–40 m depth range) electrical resistivity distribution of these anomalies...... appeared to be coincident with superficial features related to surface water such as alluvial fans and flood plains. This paper describes the application of transient electromagnetic soundings (TEM) and continuous vertical electrical sounding (CVES) using geo-electrics and time domain induced polarisation...... thins out and deteriorates in water quality further inland. It is postulated that the freshwater lens originated as a result of interaction between the Zambezi River and the salty aquifer in a setting in which evapotranspiration is the net climatic stress. Similar high electrical resistivity bodies were...

Transient analysis of the output short-circuit fault of high power and high voltage DC power supply

International Nuclear Information System (INIS)

Yang Zhigang; Zhang Jian; Huang Yiyun; Hao Xu; Sun Haozhang; Guo Fei

2014-01-01

The transient conditions of output short-circuit fault of high voltage DC power supply was introduced, and the energy of power supply injecting into klystron during the protection process of three-electrode gas switch were analyzed and calculated in detail when klystron load happening electrode arc faults. The results of calculation and simulation are consistent with the results of the experiment. When the output short-circuit fault of high voltage power supply occurs, switch can be shut off in the microsecond, and the short circuit current can be controlled in 200 A. It has verified the rapidity and reliability of the three-electrode gas switch protection, and it has engineering application value. (authors)

Transient impedance changes in venous endothelial monolayers as a biological radiation dosimetry response

Directory of Open Access Journals (Sweden)

Erik Fossum Young

2012-10-01

Full Text Available In March of 2011, a magnitude 9.0 earthquake and subsequent 14 m-high tsunami caused major damage to the Fukushima Daiichi nuclear power plant in Japan.  While cancer incidence in the radiation-exposed population is a logical concern, the complex effects of radiation on the heart and cardiovascular system are also of interest.  Immediate and early vascular radiation effects could be exploited as a dosimetry modality.  To test whether non-coronary vasculature exhibited transient perturbation in barrier function, video microscopy studies and Electric Cell Substrate Impedance Sensing technology were used to probe very subtle changes in primary human vascular endothelium.  Human umbilical vein endothelial cell (HUVEC monolayers exhibit a transient, statistically significant decrease (P = 0.017 in monolayer resistance 3 h after irradiation with 5.0 Gy of g rays.  Radiation induced perturbations in HUVEC monolayer permeability are similar in magnitude and kinetics to those observed in coronary arterial endothelium.  Therefore, at least two types of vasculature respond to radiation on ECIS arrays with an early transient disruption in permeability.  The finding supports the use of early passage HUVECs for use in bioelectric dosimetry studies of vasculature and suggests that permeability of vessels could potentially serve as a biological dosimetry tool.

Transient simulation of an endothermic chemical process facility coupled to a high temperature reactor: Model development and validation

International Nuclear Information System (INIS)

Brown, Nicholas R.; Seker, Volkan; Revankar, Shripad T.; Downar, Thomas J.

2012-01-01

Highlights: ► Models for PBMR and thermochemical sulfur cycle based hydrogen plant are developed. ► Models are validated against available data in literature. ► Transient in coupled reactor and hydrogen plant system is studied. ► For loss-of-heat sink accident, temperature feedback within the reactor core enables shut down of the reactor. - Abstract: A high temperature reactor (HTR) is a candidate to drive high temperature water-splitting using process heat. While both high temperature nuclear reactors and hydrogen generation plants have high individual degrees of development, study of the coupled plant is lacking. Particularly absent are considerations of the transient behavior of the coupled plant, as well as studies of the safety of the overall plant. The aim of this document is to contribute knowledge to the effort of nuclear hydrogen generation. In particular, this study regards identification of safety issues in the coupled plant and the transient modeling of some leading candidates for implementation in the Nuclear Hydrogen Initiative (NHI). The Sulfur Iodine (SI) and Hybrid Sulfur (HyS) cycles are considered as candidate hydrogen generation schemes. Three thermodynamically derived chemical reaction chamber models are coupled to a well-known reference design of a high temperature nuclear reactor. These chemical reaction chamber models have several dimensions of validation, including detailed steady state flowsheets, integrated loop test data, and bench scale chemical kinetics. The models and coupling scheme are presented here, as well as a transient test case initiated within the chemical plant. The 50% feed flow failure within the chemical plant results in a slow loss-of-heat sink (LOHS) accident in the nuclear reactor. Due to the temperature feedback within the reactor core the nuclear reactor partially shuts down over 1500 s. Two distinct regions are identified within the coupled plant response: (1) immediate LOHS due to the loss of the sulfuric

Do Magnetic Fields drive high-energy explosive transients?

OpenAIRE

Mundell, Carole

2017-01-01

I will review the current state-of-the-art in real-time, rapid response optical imaging and polarimetric followup of transient sources such as Gamma Ray Bursts. I will interpret current results within the context of the external shock model and present predictions for future mm- and cm-wave radio observatories. Recent observational results from new radio pilot studies will also be presented.

Do Magnetic Fields Drive High-Energy Explosive Transients?

Science.gov (United States)

Mundell, Carole

2017-10-01

I will review the current state-of-the-art in real-time, rapid response optical imaging and polarimetric followup of transient sources such as Gamma Ray Bursts. I will interpret current results within the context of the external shock model and present predictions for future mm- and cm-wave radio observatories. Recent observational results from new radio pilot studies will also be presented.

Investigation on transient flow of a centrifugal charging pump in the process of high pressure safety injection

Energy Technology Data Exchange (ETDEWEB)

Zhang, Fan, E-mail: zhangfan4060@gmail.com; Yuan, Shouqi; Fu, Qiang; Tao, Yi

2015-11-15

Highlights: • The transient flow characteristics of the charging pump with the first stage impeller in the HPSI process have been investigated numerically by CFD. • The hydraulic performance of the charging pump during the HPSI are discussed, andthe absolute errors between the simulated and measured results are analyzed in the paper. • Pressure fluctuation in the impeller and flow pattern in the impeller were studied in the HPSI process. It is influenced little at the beginning of the HPSI process while fluctuates strongly in the end of the HPSI process. - Abstract: In order to investigate the transient flow characteristics of the centrifugal charging pump during the transient transition process of high pressure safety injection (HPSI) from Q = 148 m{sup 3}/h to Q = 160 m{sup 3}/h, numerical simulation and experiment are implemented in this study. The transient flow rate, which is the most important factor, is obtained from the experiment and works as the boundary condition to accurately accomplish the numerical simulation in the transient process. Internal characteristics under the variable operating conditions are analyzed through the transient simulation. The results shows that the absolute error between the simulated and measured heads is less than 2.26% and the absolute error between the simulated and measured efficiency is less than 2.04%. Pressure fluctuation in the impeller is less influenced by variable flow rate in the HPSI process, while flow pattern in the impeller is getting better and better with the flow rate increasing. As flow rate increases, fluid blocks on the tongue of the volute and it strikes in this area at large flow rate. Correspondingly, the pressure fluctuation is intense and vortex occurs gradually during this period, which obviously lowers the efficiency of the pump. The contents of the current work can provide references for the design optimization and fluid control of the pump used in the transient process of variable operating

Investigation on transient flow of a centrifugal charging pump in the process of high pressure safety injection

International Nuclear Information System (INIS)

Zhang, Fan; Yuan, Shouqi; Fu, Qiang; Tao, Yi

2015-01-01

Highlights: • The transient flow characteristics of the charging pump with the first stage impeller in the HPSI process have been investigated numerically by CFD. • The hydraulic performance of the charging pump during the HPSI are discussed, andthe absolute errors between the simulated and measured results are analyzed in the paper. • Pressure fluctuation in the impeller and flow pattern in the impeller were studied in the HPSI process. It is influenced little at the beginning of the HPSI process while fluctuates strongly in the end of the HPSI process. - Abstract: In order to investigate the transient flow characteristics of the centrifugal charging pump during the transient transition process of high pressure safety injection (HPSI) from Q = 148 m"3/h to Q = 160 m"3/h, numerical simulation and experiment are implemented in this study. The transient flow rate, which is the most important factor, is obtained from the experiment and works as the boundary condition to accurately accomplish the numerical simulation in the transient process. Internal characteristics under the variable operating conditions are analyzed through the transient simulation. The results shows that the absolute error between the simulated and measured heads is less than 2.26% and the absolute error between the simulated and measured efficiency is less than 2.04%. Pressure fluctuation in the impeller is less influenced by variable flow rate in the HPSI process, while flow pattern in the impeller is getting better and better with the flow rate increasing. As flow rate increases, fluid blocks on the tongue of the volute and it strikes in this area at large flow rate. Correspondingly, the pressure fluctuation is intense and vortex occurs gradually during this period, which obviously lowers the efficiency of the pump. The contents of the current work can provide references for the design optimization and fluid control of the pump used in the transient process of variable operating conditions.

Image reconstruction with an adaptive threshold technique in electrical resistance tomography

International Nuclear Information System (INIS)

Kim, Bong Seok; Khambampati, Anil Kumar; Kim, Sin; Kim, Kyung Youn

2011-01-01

In electrical resistance tomography, electrical currents are injected through the electrodes placed on the surface of a domain and the corresponding voltages are measured. Based on these currents and voltage data, the cross-sectional resistivity distribution is reconstructed. Electrical resistance tomography shows high temporal resolution for monitoring fast transient processes, but it still remains a challenging problem to improve the spatial resolution of the reconstructed images. In this paper, a novel image reconstruction technique is proposed to improve the spatial resolution by employing an adaptive threshold method to the iterative Gauss–Newton method. Numerical simulations and phantom experiments have been performed to illustrate the superior performance of the proposed scheme in the sense of spatial resolution

Taipower's transient analysis methodology for pressurized water reactors

International Nuclear Information System (INIS)

Huang, Pinghue

1998-01-01

The methodology presented in this paper is a part of the 'Taipower's Reload Design and Transient Analysis Methodologies for Light Water Reactors' developed by the Taiwan Power Company (TPC) and the Institute of Nuclear Energy Research. This methodology utilizes four computer codes developed or sponsored by Electric Power Research institute: system transient analysis code RETRAN-02, core thermal-hydraulic analysis code COBRAIIIC, three-dimensional spatial kinetics code ARROTTA, and fuel rod evaluation code FREY. Each of the computer codes was extensively validated. Analysis methods and modeling techniques were conservatively established for each application using a systematic evaluation with the assistance of sensitivity studies. The qualification results and analysis methods were documented in detail in TPC topical reports. The topical reports for COBRAIIIC, ARROTTA. and FREY have been reviewed and approved by the Atomic Energy Council (ABC). TPC 's in-house transient methodology have been successfully applied to provide valuable support for many operational issues and plant improvements for TPC's Maanshan Units I and 2. Major applications include the removal of the resistance temperature detector bypass system, the relaxation of the hot-full-power moderator temperature coefficient design criteria imposed by the ROCAEC due to a concern on Anticipated Transient Without Scram, the reduction of boron injection tank concentration and the elimination of the heat tracing, and the reduction of' reactor coolant system flow. (author)

Effect of stationary high heat flux and transient ELMs-like heat loads on the divertor PFCs

Energy Technology Data Exchange (ETDEWEB)

Riccardi, B., E-mail: bruno.riccardi@f4e.europa.eu [Fusion for Energy, ITER Department, Josep Pla, 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Gavila, P. [Fusion for Energy, ITER Department, Josep Pla, 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Giniatulin, R. [Efremov Institute, 196641 St. Petersburg (Russian Federation); Kuznetsov, V. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, 142190 Troitsk, Moscow Region (Russian Federation); Rulev, R. [Efremov Institute, 196641 St. Petersburg (Russian Federation); Klimov, N.; Kovalenko, D.; Barsuk, V. [SRC RF TRINITI, ul. Pushkovykh, vladenie 12, 142190 Troitsk, Moscow Region (Russian Federation); Koidan, V.; Korshunov, S. [NRC “Kurchatov Institute”, Moscow (Russian Federation)

2013-10-15

The experimental evaluation of the divertor plasma facing components (PFCs) lifetime under transient events, such as edge localized modes (ELMs) and high heat flux (HHF) thermal fatigue expected during ITER normal operations and slow transient events is here presented. The experiments have been performed in the frame of an EU/RF collaboration. For carbon fiber composite material the erosion is caused by PAN fiber damage whilst the erosion of tungsten is determined by the melt layer movement and crack formation. The conclusion of this study is that, in addition to the structural change produced in the armor materials by ELMs-like loads, some mock ups showed also a degradation of the thermal fatigue performances.

Transient flow characteristics of a high speed rotary valve

Science.gov (United States)

Browning, Patrick H.

were experimentally mapped as a function of valve speed, inter-cylinder pressure ratios and volume ratios and the results were compared to compressible flow theoretical models. Specifically, the transient behavior suggested a short-lived loss-mode initiation closely resembled by shock tube theory followed by a quasi-steady flow regime resembling choked flow behavior. An empirical model was then employed to determine the useful range of the CCV design as applied to a four-stroke CIBAI engine cycle modeled using a 1-D quasi-steady numerical method, with particular emphasis on the cyclic timing of the CCV opening. Finally, a brief discussion of a high-temperature version of the CCV design is presented.

Transient and intermittent magnetic reconnections in TS-3/UTST merging startup experiments

International Nuclear Information System (INIS)

Ono, Y.; Imazawa, R.; Imanaka, H.; Hayamizu, T.; Inomoto, M.; Sato, M.; Kawamori, E.; Ejiri, A.; Takase, Y.; Asai, T.; Takahashi, T.

2007-01-01

The high-power reconnection heating has been developed in the TS-3 merging experiments, leading us to a new pulsed high-beta spherical tokamak (ST) formation. Two ST plasmas were produced inductively by two or four PF coils without using any central solenoid (CS) coil and were merged together for MW-GW reconnection heating. The magnetic reconnection transformed the magnetic energy of reconnecting magnetic field through the outflow kinetic energy finally to the ion thermal energy, increasing the plasma beta of ST up to 0.5. A new finding is that ejection of current sheet (or plasmoid) causes high-speed merging/ reconnection as well as high-power heating. In the high-q ST merging, the sheet resistivity was almost classical due to the sheet thickness much longer than ion gyroradius. Large inflow flux and low current-sheet dissipation resulted in flux pileup followed by rapid growth of the current sheet. When the flux pileup exceeded a critical limit, the sheet was ejected mechanically from the squeezed X-point area. The reconnection (outflow) speed was slow during the flux pileup and was fast during the ejection, indicating that intermittent reconnection similar to the solar flare increased the averaged reconnection speed. These transient effects enable us to have the fast reconnection as well as the high-power reconnection heating, even if the merging high-q tokamaks have low current-sheet resistivity. (author)

Pressure transients across HEPA filters

International Nuclear Information System (INIS)

Gregory, W.; Reynolds, G.; Ricketts, C.; Smith, P.R.

1977-01-01

Nuclear fuel cycle facilities require ventilation for health and safety reasons. High efficiency particulate air (HEPA) filters are located within ventilation systems to trap radioactive dust released in reprocessing and fabrication operations. Pressure transients within the air cleaning systems may be such that the effectiveness of the filtration system is questioned under certain accident conditions. These pressure transients can result from both natural and man-caused phenomena: atmospheric pressure drop caused by a tornado or explosions and nuclear excursions initiate pressure pulses that could create undesirable conditions across HEPA filters. Tornado depressurization is a relatively slow transient as compared to pressure pulses that result from combustible hydrogen-air mixtures. Experimental investigation of these pressure transients across air cleaning equipment has been undertaken by Los Alamos Scientific Laboratory and New Mexico State University. An experimental apparatus has been constructed to impose pressure pulses across HEPA filters. The experimental equipment is described as well as preliminary results using variable pressurization rates. Two modes of filtration of an aerosol injected upstream of the filter is examined. A laser instrumentation for measuring the aerosol release, during the transient, is described

Towards a utilisation of transient processing in the technology of high efficiency silicon solar cells

International Nuclear Information System (INIS)

Eichhammer, W.

1989-01-01

The utilization of transient processing in the technology of high efficient silicon solar cells is investigated. An ultraviolet laser (an ArF pulsed excimer laser working at 193 nm) is applied. Laser processing induces only a short superficial melting of the material and does not modify the transport properties in the base of the material. This mode of processing associated to ion implantation to form the junction as well as an oxide layer in an atmosphere of oxygen. The volume was left entirely cold in this process. The results of the investigation show: that an entirely cold process of solar cell fabrication needs a thermal treatment at a temperature around 600 C; that the oxides obtained are not satisfying as passivating layers; and that the Rapid Thermal Processing (RTP) induced recombination centers are not directly related to the quenching step but a consequence of the presence of metal impurities. The utilisation of transient processing in the adiabatic regime (laser) and in the rapid isothermal regime (RTP) are possible as two complementary techniques for the realization of high efficiency solar cells

Advanced Instrumentation for Transient Reactor Testing

Energy Technology Data Exchange (ETDEWEB)

Corradini, Michael L.; Anderson, Mark; Imel, George; Blue, Tom; Roberts, Jeremy; Davis, Kurt

2018-01-31

Transient testing involves placing fuel or material into the core of specialized materials test reactors that are capable of simulating a range of design basis accidents, including reactivity insertion accidents, that require the reactor produce short bursts of intense highpower neutron flux and gamma radiation. Testing fuel behavior in a prototypic neutron environment under high-power, accident-simulation conditions is a key step in licensing nuclear fuels for use in existing and future nuclear power plants. Transient testing of nuclear fuels is needed to develop and prove the safety basis for advanced reactors and fuels. In addition, modern fuel development and design increasingly relies on modeling and simulation efforts that must be informed and validated using specially designed material performance separate effects studies. These studies will require experimental facilities that are able to support variable scale, highly instrumented tests providing data that have appropriate spatial and temporal resolution. Finally, there are efforts now underway to develop advanced light water reactor (LWR) fuels with enhanced performance and accident tolerance. These advanced reactor designs will also require new fuel types. These new fuels need to be tested in a controlled environment in order to learn how they respond to accident conditions. For these applications, transient reactor testing is needed to help design fuels with improved performance. In order to maximize the value of transient testing, there is a need for in-situ transient realtime imaging technology (e.g., the neutron detection and imaging system like the hodoscope) to see fuel motion during rapid transient excursions with a higher degree of spatial and temporal resolution and accuracy. There also exists a need for new small, compact local sensors and instrumentation that are capable of collecting data during transients (e.g., local displacements, temperatures, thermal conductivity, neutron flux, etc.).

Transient virulence of emerging pathogens.

Science.gov (United States)

Bolker, Benjamin M; Nanda, Arjun; Shah, Dharmini

2010-05-06

Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution.

Ultrahigh hardness and high electrical resistivity in nano-twinned, nanocrystalline high-entropy alloy films

Science.gov (United States)

Huo, Wenyi; Liu, Xiaodong; Tan, Shuyong; Fang, Feng; Xie, Zonghan; Shang, Jianku; Jiang, Jianqing

2018-05-01

Nano-twinned, nanocrystalline CoCrFeNi high-entropy alloy films were produced by magnetron sputtering. The films exhibit a high hardness of 8.5 GPa, the elastic modulus of 161.9 GPa and the resistivity as high as 135.1 μΩ·cm. The outstanding mechanical properties were found to result from the resistance of deformation created by nanocrystalline grains and nano-twins, while the electrical resistivity was attributed to the strong blockage effect induced by grain boundaries and lattice distortions. The results lay a solid foundation for the development of advanced films with structural and functional properties combined in micro-/nano-electronic devices.

Optimization of High-Resolution Continuous Flow Analysis for Transient Climate Signals in Ice Cores

DEFF Research Database (Denmark)

Bigler, Matthias; Svensson, Anders; Kettner, Ernesto

2011-01-01

Over the past two decades, continuous flow analysis (CFA) systems have been refined and widely used to measure aerosol constituents in polar and alpine ice cores in very high-depth resolution. Here we present a newly designed system consisting of sodium, ammonium, dust particles, and electrolytic...... meltwater conductivity detection modules. The system is optimized for high- resolution determination of transient signals in thin layers of deep polar ice cores. Based on standard measurements and by comparing sections of early Holocene and glacial ice from Greenland, we find that the new system features...

A graphene integrated highly transparent resistive switching memory device

Science.gov (United States)

Dugu, Sita; Pavunny, Shojan P.; Limbu, Tej B.; Weiner, Brad R.; Morell, Gerardo; Katiyar, Ram S.

2018-05-01

We demonstrate the hybrid fabrication process of a graphene integrated highly transparent resistive random-access memory (TRRAM) device. The indium tin oxide (ITO)/Al2O3/graphene nonvolatile memory device possesses a high transmittance of >82% in the visible region (370-700 nm) and exhibits stable and non-symmetrical bipolar switching characteristics with considerably low set and reset voltages (ITO/Al2O3/Pt device and studied its switching characteristics for comparison and a better understanding of the ITO/Al2O3/graphene device characteristics. The conduction mechanisms in high and low resistance states were analyzed, and the observed polarity dependent resistive switching is explained based on electro-migration of oxygen ions.

Extraction of diagnostic parameters from the transient response of a porous electro ceramic gas sensor

International Nuclear Information System (INIS)

Hossein-Babaei, F.; Orvatinia, M.

2004-01-01

A novel concept for the diagnosis of a pure target gas in air is presented. The method employs a resistive gas sensor with a mm-thick highly porous electro ceramic gas sensitive body. The diagnosis is based on the fact that the diffusion time of the target gas through the porous body would depend on its molecular properties. The transient response of the device was analyzed based on a diffusion reaction equation. The solutions of the equation were shown to be of diagnostic merits. Such a device was fabricated by partial sintering of a Zn O body formed by low pressure pressing. The transient responses of the device to methanol, ethanol, poropanol and butanol were recorded. The analytical data, and the diagnostic parameters were resulted as the fitting parameters. Comparison of the parameters obtained with those available from the calibration experiments afforded target gas identification

Transient analysis of house load operation for LNPP

International Nuclear Information System (INIS)

Shi Junying; Zheng Bin

2000-01-01

The author analysis the transient of house load operation for Ling'ao Nuclear Power Plant by using the methods of dynamic simulation and closed loops of primary and secondary system. The transient of house load operation from 100% FP is the most severe that can occur on the unit in normal operation because it causes immediately shedding of 95% of turbine load and requires the unit to operate steadily at reduced power. The results show that the transient can be successful both at beginning of core life and manual house load operation. However, more attentions must be paid to automatic house load operation caused by grid fault at toward end of core life because the success of the transient could be threatened by the actuation of the protection of high flux and high flux rate

Aerial Transient Electromagnetic Surveys of Alluvial Aquifers in Rural Watersheds of Arizona

Science.gov (United States)

Pool, D. R.; Callegary, J. B.; Groom, R. W.

2006-12-01

Development in rural areas of Arizona has led the State of Arizona (Arizona Department of Water Resources), in cooperation with the Arizona Water Science Center of the U.S. Geological Survey, to sponsor investigations of the hydrogeologic framework of several alluvial-basin aquifers. An efficient method for mapping the aquifer extent and lithology was needed due to sparse subsurface information. Aerial Transient Electro-Magnetic (ATEM) methods were selected because they can be used to quickly survey large areas and with a great depth of investigation. Both helicopter and fixed-wing ATEM methods are available. A fixed-wing method (GEOTEM) was selected because of the potential for a depth of investigation of 300 m or more and because previous surveys indicated the method is useful in alluvial basins in southeastern Arizona. About 2,900 km of data along flight lines were surveyed across five alluvial basins, including the Middle San Pedro and Willcox Basins in southeastern Arizona, and Detrital, Hualapai, and Sacramento Basins in northwestern Arizona. Data initially were analyzed by the contractor (FUGRO Airborne Surveys) to produce conductivity-depth-transforms, which approximate the general subsurface electrical-property distribution along profiles. Physically based two-dimensional physical models of the profile data were then developed by PetRos- Eikon by using EMIGMA software. Hydrologically important lithologies can have different electrical properties. Several types of crystalline and sedimentary rocks generally are poor aquifers that have low porosity and high electrical resistivity. Good alluvial aquifers of sand and gravel generally have an intermediate electrical resistivity. Poor aquifer materials, such as silt and clay, and areas of poor quality water have low electrical resistivity values. Several types of control data were available to constrain the models including drill logs, electrical logs, water levels , and water quality information from wells; and

The OECD/NEA/NSC PBMR 400 MW coupled neutronics thermal hydraulics transient benchmark: transient results - 290

International Nuclear Information System (INIS)

Strydom, G.; Reitsma, F.; Ngeleka, P.T.; Ivanov, K.N.

2010-01-01

The PBMR is a High-Temperature Gas-cooled Reactor (HTGR) concept developed to be built in South Africa. The analysis tools used for core neutronic design and core safety analysis need to be verified and validated, and code-to-code comparisons are an essential part of the V and V plans. As part of this plan the PBMR 400 MWth design and a representative set of transient exercises are defined as an OECD benchmark. The scope of the benchmark is to establish a series of well defined multi-dimensional computational benchmark problems with a common given set of cross sections, to compare methods and tools in coupled neutronics and thermal hydraulics analysis with a specific focus on transient events. This paper describes the current status of the benchmark project and shows the results for the six transient exercises, consisting of three Loss of Cooling Accidents, two Control Rod Withdrawal transients, a power load-follow transient, and a Helium over-cooling Accident. The participants' results are compared using a statistical method and possible areas of future code improvement are identified. (authors)

Deep level transient spectroscopic investigation of phosphorus-doped silicon by self-assembled molecular monolayers.

Science.gov (United States)

Gao, Xuejiao; Guan, Bin; Mesli, Abdelmadjid; Chen, Kaixiang; Dan, Yaping

2018-01-09

It is known that self-assembled molecular monolayer doping technique has the advantages of forming ultra-shallow junctions and introducing minimal defects in semiconductors. In this paper, we report however the formation of carbon-related defects in the molecular monolayer-doped silicon as detected by deep-level transient spectroscopy and low-temperature Hall measurements. The molecular monolayer doping process is performed by modifying silicon substrate with phosphorus-containing molecules and annealing at high temperature. The subsequent rapid thermal annealing drives phosphorus dopants along with carbon contaminants into the silicon substrate, resulting in a dramatic decrease of sheet resistance for the intrinsic silicon substrate. Low-temperature Hall measurements and secondary ion mass spectrometry indicate that phosphorus is the only electrically active dopant after the molecular monolayer doping. However, during this process, at least 20% of the phosphorus dopants are electrically deactivated. The deep-level transient spectroscopy shows that carbon-related defects are responsible for such deactivation.

Iron-niobium-aluminum alloy having high-temperature corrosion resistance

Science.gov (United States)

Hsu, Huey S.

1988-04-14

An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

A simple heat transfer model for a heat flux plate under transient conditions

International Nuclear Information System (INIS)

Ryan, L.; Dale, J.D.

1985-01-01

Heat flux plates are used for measuring rates of heat transfer through surfaces under steady state and transient conditions. Their usual construction is to have a resistive layer bounded by thermopiles and an exterior layer for protection. If properly designed and constructed a linear relationship between the thermopile generated voltage and heat flux results and calibration under steady state conditions is straight forward. Under transient conditions however the voltage output from a heat flux plate cannot instantaneously follow the heat flux because of the thermal capacitance of the plate and the resulting time lag. In order to properly interpret the output of a heat flux plate used under transient conditions a simple heat transfer model was constructed and tested. (author)

Overall Low Extended-Spectrum Cephalosporin Resistance but high Azithromycin Resistance in Neisseria gonorrhoeae in 24 European Countries, 2015.

Science.gov (United States)

Cole, Michelle J; Spiteri, Gianfranco; Jacobsson, Susanne; Woodford, Neil; Tripodo, Francesco; Amato-Gauci, Andrew J; Unemo, Magnus

2017-09-11

Surveillance of Neisseria gonorrhoeae antimicrobial susceptibility in Europe is performed through the European Gonococcal Antimicrobial Surveillance Programme (Euro-GASP), which additionally provides data to inform the European gonorrhoea treatment guideline; currently recommending ceftriaxone 500 mg plus azithromycin 2 g as first-line therapy. We present antimicrobial susceptibility data from 24 European countries in 2015, linked to epidemiological data of patients, and compare the results to Euro-GASP data from previous years. Antimicrobial susceptibility testing by MIC gradient strips or agar dilution methodology was performed on 2134 N. gonorrhoeae isolates and interpreted using EUCAST breakpoints. Patient variables associated with resistance were established using logistic regression to estimate odds ratios (ORs). In 2015, 1.7% of isolates were cefixime resistant compared to 2.0% in 2014. Ceftriaxone resistance was detected in only one (0.05%) isolate in 2015, compared with five (0.2%) in 2014. Azithromycin resistance was detected in 7.1% of isolates in 2015 (7.9% in 2014), and five (0.2%) isolates displayed high-level azithromycin resistance (MIC ≥ 256 mg/L) compared with one (0.05%) in 2014. Ciprofloxacin resistance remained high (49.4%, vs. 50.7% in 2014). Cefixime resistance significantly increased among heterosexual males (4.1% vs. 1.7% in 2014), which was mainly attributable to data from two countries with high cefixime resistance (~11%), however rates among men-who-have-sex-with-men (MSM) and females continued to decline to 0.5% and 1%, respectively. Azithromycin resistance in MSM and heterosexual males was higher (both 8.1%) than in females (4.9% vs. 2.2% in 2014). The association between azithromycin resistance and previous gonorrhoea infection, observed in 2014, continued in 2015 (OR 2.1, CI 1.2-3.5, p resistance and low overall resistance to ceftriaxone and cefixime. The low cephalosporin resistance may be attributable to the effectiveness

Three dimensional transient electromagnetic model study for fracture prediction from tunnel face; Sanjigen model keisan ni yoru TEM ho no tunnel zenpo tansa eno tekiyosei no kento

Energy Technology Data Exchange (ETDEWEB)

Wada, K; Tsutsui, T; Saito, A [Mitsui Mineral Development Engineering Co. Ltd., Tokyo (Japan); Hara, T [Toda Corp., Tokyo, (Japan); Zhdanov, M [University of Utah, UT (United States)

1996-10-01

In order to apply TEM model to fracture prediction at tunnel face, 3-D TEM model computation by FEM was conducted by installing a transmission loop on a tunnel face. MT field responses diffusing into the 3-D model were computed by time-domain difference calculus, and analytical precision was improved by introducing a staggered grid method. In the case where a low resistive zone exists before a tunnel face, time variance in diffused eddy current and induction current in the low resistive zone could be obtained. The difference in tunnel-axial transient curve (transient phenomenon curve in magnetic field) between uniform medium and low resistive zone models was based on the absorption process of diffused eddy current into the low resistive zone, and the expanding process of it toward the outside. Change in background condition could be predicted from the background and the ratio of transient curves every measurement. The detection limit of the low resistive zone was dependent on resistivity contrast, distance and geometry. Fluctuation in measurement due to noises and S/N ratio were also essential. 3 refs., 10 figs.

Current voltage characteristics of composite superconductors with high contact resistance

International Nuclear Information System (INIS)

Akhmetov, A.A.; Baev, V.P.

1984-01-01

An experimental study has been made of current-voltage characteristics of composite superconductors with contact resistance between superconducting filaments and normal metal with high electrical conductivity. It is shown that stable resistive states exist in such conductors over a wide range of currents. The presence of resistive states is interpreted in terms of the resistive domain concept. The minimum and maximum currents of resistive states are found to be dependent on the electrical resistance of normal metal and magnetic field. (author)

Studies on transient characteristics of unipolar resistive switching processes in TiO2 thin film grown by atomic layer deposition

Science.gov (United States)

Sahu, Vikas Kumar; Das, Amit K.; Ajimsha, R. S.; Misra, P.

2018-05-01

The transient characteristics of resistive switching processes have been investigated in TiO2 thin films grown by atomic layer deposition (ALD) to study the temporal evolution of the switching processes and measure the switching times. The reset and set switching times of unipolar Au/TiO2/Pt devices were found to be ~250 µs and 180 ns, respectively in the voltage windows of 0.5–0.9 V for reset and 1.9–4.8 V for set switching processes, obtained from quasi-static measurements. The reset switching time decreased exponentially with increasing amplitude of applied reset voltage pulse, while the set switching time remained insensitive to the amplitude of the set voltage pulse. A fast reset process with a switching time of ~400 ns was achieved by applying a reset voltage of ~1.8 V, higher than that of the quasi-static reset voltage window but below the set voltage window. The sluggish reset process in TiO2 thin film and the dependence of the reset switching time on the amplitude of the applied voltage pulse was understood on the basis of a self-accelerated thermal dissolution model of conducting filaments (CFs), where a higher temperature of the CFs owing to enhanced Joule heating at a higher applied voltage imposes faster diffusion of oxygen vacancies, resulting in a shorter reset switching time. Our results clearly indicate that fast resistive switching with switching times in hundreds of nanoseconds can be achieved in ALD-grown TiO2 thin films. This may find applications in fast non-volatile unipolar resistive switching memories.

Does High-Dose Antimicrobial Chemotherapy Prevent the Evolution of Resistance?

Science.gov (United States)

Day, Troy; Read, Andrew F.

2016-01-01

High-dose chemotherapy has long been advocated as a means of controlling drug resistance in infectious diseases but recent empirical studies have begun to challenge this view. We develop a very general framework for modeling and understanding resistance emergence based on principles from evolutionary biology. We use this framework to show how high-dose chemotherapy engenders opposing evolutionary processes involving the mutational input of resistant strains and their release from ecological competition. Whether such therapy provides the best approach for controlling resistance therefore depends on the relative strengths of these processes. These opposing processes typically lead to a unimodal relationship between drug pressure and resistance emergence. As a result, the optimal drug dose lies at either end of the therapeutic window of clinically acceptable concentrations. We illustrate our findings with a simple model that shows how a seemingly minor change in parameter values can alter the outcome from one where high-dose chemotherapy is optimal to one where using the smallest clinically effective dose is best. A review of the available empirical evidence provides broad support for these general conclusions. Our analysis opens up treatment options not currently considered as resistance management strategies, and it also simplifies the experiments required to determine the drug doses which best retard resistance emergence in patients. PMID:26820986

Transient formation of forbidden lines

International Nuclear Information System (INIS)

Rosmej, F.B.; Rosmej, O.N.

1996-01-01

An explanation of anomalously long time scales in the transient formation of forbidden lines is proposed. The concept is based on a collisionally induced density dependence of the relaxation times of metastable level populations in transient plasma. Generalization leads to an incorporation of diffusion phenomena. We demonstrate this new concept for the simplest atomic system: the He-like isoelectronic sequence. A new interpretation of the observed long duration and anomalously high intensity of spin-forbidden emission in hot plasmas is given. (author)

Transient formation of forbidden lines

Energy Technology Data Exchange (ETDEWEB)

Rosmej, F.B. [Bochum Univ., Ruhr (Germany). Inst. fuer Experimentalphysik V; Rosmej, O.N. [VNIIFTRI, Moscow Region (Russian Federation). MISDC

1996-05-14

An explanation of anomalously long time scales in the transient formation of forbidden lines is proposed. The concept is based on a collisionally induced density dependence of the relaxation times of metastable level populations in transient plasma. Generalization leads to an incorporation of diffusion phenomena. We demonstrate this new concept for the simplest atomic system: the He-like isoelectronic sequence. A new interpretation of the observed long duration and anomalously high intensity of spin-forbidden emission in hot plasmas is given. (author).

Stability of High Temperature Standard Platinum Resistance Thermometers at High Temperatures

Directory of Open Access Journals (Sweden)

Y. A. ABDELAZIZ

2010-05-01

Full Text Available An investigation of the stability of high temperature standard platinum resistance thermometers HTSPRTs has been carried out for two different designs thermometers (with nominal resistance 0.25 Ω and 2.5 Ω from two different suppliers. The thermometers were heated for more than 160 hours at temperatures above 960 0C using a vertical furnace with a ceramic block. A study was made of the influence of the heat treatment on the stability of the resistance at the triple point of water, and on the relative resistance W(Ga at the melting point of gallium. The thermometers showed a correlation between the drift note and the values of W(Ga. It was found also that the HTSPRT which has a sensor with strip shaped support and low nominal resistance is more stable than the HTSPRT which has a sensor in the form of a coil wound on silica cross. The 0.25 Ω thermometer has better stability @ 7x10-6 0C (at TPW after 40 hour. Factors affecting the stability and accuracy of HTSPRT also will be discussed.

High prevalence of multi-drug resistant Klebsiella pneumoniae in a ...

African Journals Online (AJOL)

The lowest resistance rates were documented for Carbapenems (23.2%). For specific antibiotics, there was high resistance to commonly used antibiotics (over 80% for Ceftriaxone, Cefipime, Gentamycin and Ceftazidime). The antibiotics with least resistance were Amikacin and Meropenem (21% and 7 % respectively).

Wide Field Radio Transient Surveys

Science.gov (United States)

Bower, Geoffrey

2011-04-01

The time domain of the radio wavelength sky has been only sparsely explored. Nevertheless, serendipitous discovery and results from limited surveys indicate that there is much to be found on timescales from nanoseconds to years and at wavelengths from meters to millimeters. These observations have revealed unexpected phenomena such as rotating radio transients and coherent pulses from brown dwarfs. Additionally, archival studies have revealed an unknown class of radio transients without radio, optical, or high-energy hosts. The new generation of centimeter-wave radio telescopes such as the Allen Telescope Array (ATA) will exploit wide fields of view and flexible digital signal processing to systematically explore radio transient parameter space, as well as lay the scientific and technical foundation for the Square Kilometer Array. Known unknowns that will be the target of future transient surveys include orphan gamma-ray burst afterglows, radio supernovae, tidally-disrupted stars, flare stars, and magnetars. While probing the variable sky, these surveys will also provide unprecedented information on the static radio sky. I will present results from three large ATA surveys (the Fly's Eye survey, the ATA Twenty CM Survey (ATATS), and the Pi GHz Survey (PiGSS)) and several small ATA transient searches. Finally, I will discuss the landscape and opportunities for future instruments at centimeter wavelengths.

Impact of Low and High Doses of Marbofloxacin on the Selection of Resistant Enterobacteriaceae in the Commensal Gut Flora of Young Cattle: Discussion of Data from 2 Study Populations.

Science.gov (United States)

Lhermie, Guillaume; Dupouy, Véronique; El Garch, Farid; Ravinet, Nadine; Toutain, Pierre-Louis; Bousquet-Mélou, Alain; Seegers, Henri; Assié, Sébastien

2017-03-01

In the context of requested decrease of antimicrobial use in veterinary medicine, our objective was to assess the impact of two doses of marbofloxacin administered on young bulls (YBs) and veal calves (VCs) treated for bovine respiratory disease, on the total population of Enterobacteriaceae in gut flora and on the emergence of resistant Enterobacteriaceae. In two independent experiments, 48 YBs from 6 commercial farms and 33 VCs previously colostrum deprived and exposed to cefquinome were randomly assigned to one of the three groups LOW, HIGH, and Control. In LOW and HIGH groups, animals received a single injection of, respectively, 2 and 10 mg/kg marbofloxacin. Feces were sampled before treatment, and at several times after treatment. Total and resistant Enterobacteriaceae enumerating were performed by plating dilutions of fecal samples on MacConkey agar plates that were supplemented or not with quinolone. In YBs, marbofloxacin treatment was associated with a transient decrease in total Enterobacteriaceae count between day (D)1 and D3 after treatment. Total Enterobacteriaceae count returned to baseline between D5 and D7 in all groups. None of the 48 YBs harbored marbofloxacin-resistant Enterobacteriaceae before treatment. After treatment, 1 out of 20 YBs from the Control group and 1 out of 14 YBs from the HIGH group exhibited marbofloxacin-resistant Enterobacteriaceae. In VCs, the rate of fluoroquinolone-resistant Enterobacteriaceae significantly increased after low and high doses of marbofloxacin treatment. However, the effect was similar for the two doses, which was probably related to the high level of resistant Enterobacteriaceae exhibited before treatment. Our results suggest that a single treatment with 2 or 10 mg/kg marbofloxacin exerts a moderate selective pressure on commensal Enterobacteriaceae in YBs and in VCs. A fivefold decrease of marbofloxacin regimen did not affect the selection of resistances among commensal bacteria.

500 MHz transient digitizers based on GaAs CCDs

Energy Technology Data Exchange (ETDEWEB)

Bryman, D A; Constable, M; Cresswell, J V; Daviel, A; LeNoble, M; Mildenberger, J; Poutissou, R

1996-11-01

A system of 500 MHz transient digitizers based on gallium arsenide resistive gate charged coupled devices has been developed for an experiment studying rare K decays. CCDs with dynamic range of 8-bits and 128 or 320 pixels are used as analog pipelines. The CCD`s are driven by a single phase transport system. Data readout and manipulation occurs at 15.6 MHz. (authors). 12 refs., 15 figs.

High resistance ratio of bipolar resistive switching in a multiferroic/high-K Bi(Fe0.95Cr0.05)O3/ZrO2/Pt heterostructure

Science.gov (United States)

Dong, B. W.; Miao, Jun; Han, J. Z.; Shao, F.; Yuan, J.; Meng, K. K.; Wu, Y.; Xu, X. G.; Jiang, Y.

2018-03-01

An novel heterostructure composed of multiferroic Bi(Fe0.95Cr0.05)O3 (BFCO) and high-K ZrO2 (ZO) layers is investigated. Ferroelectric and electrical properties of the BFZO/ZO heterostructure have been investigated. A pronounced bipolar ferroelectric resistive switching characteristic was achieved in the heterostructure at room temperature. Interestingly, the BFCO/ZO structures exhibit a reproducible resistive switching with a high On/Off resistance ratio ∼2×103 and long retention time. The relationship between polarization and band structure at the interface of BFCO/ZO bilayer under the positive and negative sweepings has been discussed. As a result, the BFCO/ZO multiferroic/high-K heterostructure with high On/Off resistance ratio and long retention characterizes, exhibits a potential in future nonvolatile memory application.

Transient pseudohypoaldosteronism

Directory of Open Access Journals (Sweden)

Stajić Nataša

2011-01-01

Full Text Available Introduction. Infants with urinary tract malformations (UTM presenting with urinary tract infection (UTI are prone to develop transient type 1 pseudohypoaldosteronism (THPA1. Objective. Report on patient series with characteristics of THPA1, UTM and/or UTI and suggestions for the diagnosis and therapy. Methods. Patients underwent blood and urine electrolyte and acid-base analysis, serum aldosterosterone levels and plasma rennin activity measuring; urinalysis, urinoculture and renal ultrasound were done and medical and/or surgical therapy was instituted. Results. Hyponatraemia (120.9±5.8 mmol/L, hyperkalaemia (6.9±0.9 mmol/L, metabolic acidosis (plasma bicarbonate, 11±1.4 mmol/L, and a rise in serum creatinine levels (145±101 μmol/L were associated with inappropriately high urinary sodium (51.3±17.5 mmol/L and low potassium (14.1±5.9 mmol/L excretion. Elevated plasma aldosterone concentrations (170.4±100.5 ng/dL and the very high levels of the plasma aldosterone to potassium ratio (25.2±15.6 together with diminished urinary K/Na values (0.31±0.19 indicated tubular resistance to aldosterone. After institution of appropriate medical and/or surgical therapy, serum electrolytes, creatinine, and acid-base balance were normalized. Imaging studies showed ureteropyelic or ureterovesical junction obstruction in 3 and 2 patients, respectively, posterior urethral valves in 3, and normal UT in 1 patient. According to our knowledge, this is the first report on THPA1 in the Serbian literature. Conclusion. Male infants with hyponatraemia, hyperkalaemia and metabolic acidosis have to have their urine examined and the renal ultrasound has to be done in order to avoid both, the underdiagnosis of THPA1 and the inappropriate medication.

Photoluminescence transient study of surface defects in ZnO nanorods grown by chemical bath deposition

Science.gov (United States)

Barbagiovanni, E. G.; Strano, V.; Franzò, G.; Crupi, I.; Mirabella, S.

2015-03-01

Two deep level defects (2.25 and 2.03 eV) associated with oxygen vacancies (Vo) were identified in ZnO nanorods (NRs) grown by low cost chemical bath deposition. A transient behaviour in the photoluminescence (PL) intensity of the two Vo states was found to be sensitive to the ambient environment and to NR post-growth treatment. The largest transient was found in samples dried on a hot plate with a PL intensity decay time, in air only, of 23 and 80 s for the 2.25 and 2.03 eV peaks, respectively. Resistance measurements under UV exposure exhibited a transient behaviour in full agreement with the PL transient, indicating a clear role of atmospheric O2 on the surface defect states. A model for surface defect transient behaviour due to band bending with respect to the Fermi level is proposed. The results have implications for a variety of sensing and photovoltaic applications of ZnO NRs.

Optimization of resistively hardened latches

International Nuclear Information System (INIS)

Gagne, G.; Savaria, Y.

1990-01-01

The design of digital circuits tolerant to single-event upsets is considered. The results of a study are presented on which an analytical model was used to predict the behavior of a standard resistively hardened latch. It is shown that a worst case analysis for all possible single-event upset situations (on the latch or in the logic) can be derived from studying the effects of a transient disturbed write cycle. The existence of an intrinsic minimum write period to tolerate a transient of a given duration is also demonstrated

Development and Performance Verification of the GANDALF High-Resolution Transient Recorder System

CERN Document Server

Bartknecht, Stefan; Herrmann, Florian; Königsmann, Kay; Lauser, Louis; Schill, Christian; Schopferer, Sebastian; Wollny, Heiner

2011-01-01

With present-day detectors in high energy physics one often faces fast analog pulses of a few nanoseconds length which cover large dynamic ranges. In many experiments both amplitude and timing information have to be measured with high accuracy. Additionally, the data rate per readout channel can reach several MHz, which leads to high demands on the separation of pile-up pulses. For an upgrade of the COMPASS experiment at CERN we have designed the GANDALF transient recorder with a resolution of 12bit@1GS/s and an analog bandwidth of 500\\:MHz. Signals are digitized with high precision and processed by fast algorithms to extract pulse arrival times and amplitudes in real-time and to generate trigger signals for the experiment. With up to 16 analog channels, deep memories and a high data rate interface, this 6U-VME64x/VXS module is not only a dead-time free digitization unit but also has huge numerical capabilities provided by the implementation of a Virtex5-SXT FPGA. Fast algorithms implemented in the FPGA may b...

Transient behaviour of small HTR for cogeneration

International Nuclear Information System (INIS)

Verkerk, E.C.; Van Heek, A.I.

2000-01-01

The Dutch market for combined generation of heat and power identifies a unit size of 40 MW thermal for the conceptual design of a nuclear cogeneration plant. The ACACIA system provides 14 MWe electricity combined with 17 t/h of high temperature steam (220 deg C, 10 bar) with a pebble-bed high temperature reactor directly coupled with a helium compressor and a helium turbine. The design of this small CHP unit that is used for industrial applications is mainly based on a pre-feasibility study in 1996, performed by a joint working group of five Dutch organisations, in which technical feasibility was shown. Thermal hydraulic and reactor physics analyses show favourable control characteristics during normal operation and a benign response to loss of helium coolant and loss of flow conditions. Throughout the response on these highly infrequent conditions, ample margin exists between the highest fuel temperatures and the temperature above which fuel degradation will occur. To come to quantitative statements about the ACACIA transient behaviour, a calculational coupling between the high temperature reactor core analysis code package PANTHER/DIREKT and the thermal hydraulic code RELAP5 for the energy conversion system has been made. This coupling offers a more realistic simulation of the entire system, since it removes the necessity of forcing boundary conditions on the simulation models at the data transfer points. In this paper, the models used for the dynamic components of the energy conversion system are described, and the results of the calculation for two operational transients in order to demonstrate the effects of the interaction between reactor core and its energy conversion system are shown. Several transient cases that are representative as operational transients for an HTR will be discussed, including one representing a load rejection case that shows the functioning of the control system, in particular the bypass valve. Another transient is a load following

Transient hypothyroidism after 131I treatment of Graves disease

International Nuclear Information System (INIS)

Liu Jianfeng; Fang Yi; Zhang Xiuli; Ye Genyao; Xing Jialiu; Zhang Youren

2003-01-01

Objective: To evaluate the results of the transient hypothyroidism after 131 I treatment of Graves disease. Methods: A total of 32 transient hypothyroidism patients treated with 131 I for Graves disease were studied and followed up. Results: Transient hypothyroidism occurred within 2-6 months after 131 I treatment and 19 patients were symptomatic. At diagnosis of transient hypothyroidism, T 3 and T 4 levels were decreased had normal, TSH levels were increased, normal or low. Follow-up examination found that 20 patients were normal and 12 patients had relapse of hyperthyroidism. Conclusions: Therapy of Graves disease with low doses of 131 I causes a high incidence of transient hypothyroidism. After recovery of transient hypothyroidism, some patients have relapse of hyperthyroidism

Transient osteoporosis: Not just the hip to worry about

Directory of Open Access Journals (Sweden)

Nicola Berman, MD

2016-12-01

Full Text Available Transient osteoporosis (TO is a clinical syndrome characterized by joint pain and the presence of bone marrow edema on magnetic resonance imaging (MRI, both of which spontaneously resolve over time. Transient osteoporosis most commonly affects the hip, but also may involve other lower extremity sites. TO likely represents a disorder that may be monoarticular or “migratory” with involvement of two or more lower extremity sites sequentially affected over a number of months. We report on two cases of transient osteoporosis, one involving the knee and one involving the hip, demonstrating the utility of serial bone mineral density measurements at both sites. Additionally, we are able to report on the microarchitectural changes seen at the distal femur on ultra-high resolution (7 T MRI. Case #1 describes a recurrence of transient osteoporosis of the hip three years after a similar presentation at the contralateral hip and highlights the findings of rapidly changing bone mineral density in this clinical syndrome. In contrast to the spine, hip and forearm, peripheral bone density measurements at the knee are rarely reported and to our knowledge Case #2 represents the first report of transient osteoporosis of the knee demonstrating bone density findings similar to that seen in the hip. We postulate that transient osteoporosis of the knee is part of a clinical spectrum most commonly seen in the hip and one that is marked by lower extremity joint pain, bone marrow edema on MRI and transient decreases in bone mineral density all of which spontaneously resolve without sequelae. Keywords: Transient osteoporosis, Transient osteoporosis of the hip, Transient osteoporosis of the knee, Bone marrow edema, High resolution 7 T MRI

Transient hardened power FETs

International Nuclear Information System (INIS)

Dawes, W.R. Jr.; Fischer, T.A.; Huang, C.C.C.; Meyer, W.J.; Smith, C.S.; Blanchard, R.A.; Fortier, T.J.

1986-01-01

N-channel power FETs offer significant advantages in power conditioning circuits. Similiarily to all MOS technologies, power FET devices are vulnerable to ionizing radiation, and are particularily susceptible to burn-out in high dose rate irradiations (>1E10 rads(Si)/sec.), which precludes their use in many military environments. This paper will summarize the physical mechanisms responsible for burn-out, and discuss various fabrication techniques designed to improve the transient hardness of power FETs. Power FET devices were fabricated with several of these techniques, and data will be presented which demonstrates that transient hardness levels in excess of 1E12 rads(Si)/sec. are easily achievable

Transient Go: A Mobile App for Transient Astronomy Outreach

Science.gov (United States)

Crichton, D.; Mahabal, A.; Djorgovski, S. G.; Drake, A.; Early, J.; Ivezic, Z.; Jacoby, S.; Kanbur, S.

2016-12-01

Augmented Reality (AR) is set to revolutionize human interaction with the real world as demonstrated by the phenomenal success of `Pokemon Go'. That very technology can be used to rekindle the interest in science at the school level. We are in the process of developing a prototype app based on sky maps that will use AR to introduce different classes of astronomical transients to students as they are discovered i.e. in real-time. This will involve transient streams from surveys such as the Catalina Real-time Transient Survey (CRTS) today and the Large Synoptic Survey Telescope (LSST) in the near future. The transient streams will be combined with archival and latest image cut-outs and other auxiliary data as well as historical and statistical perspectives on each of the transient types being served. Such an app could easily be adapted to work with various NASA missions and NSF projects to enrich the student experience.

High-energy transients with Fermi/GBM

International Nuclear Information System (INIS)

Gruber, David

2012-01-01

For most of mankind's history, astronomy was performed on-ground in the optical energy range. It was only when space-based missions, built more than 50 years ago, detected photons with mind-boggling energies that the exploration of the violent Universe really began. These γ-ray photons still provide us with an unprecedented wealth of information for the most energetic processes taking place in the cosmos. Faithful to the olympic slogan ''higher, faster, further'', an increasing armada of γ-ray satellites was built and launched over the last couple of decades with Fermi being the youngest of its kind. In this thesis, I use data from the Gamma-Ray Burst Monitor (GBM) onboard the Fermi satellite. The focus of this work lies on three very different classes of high-energy astrophysical transients: Gamma-Ray Bursts (GRBs), solar flares and Soft Gamma Repeaters (SGRs). In Chapter 2, I present GRB 091024A, a burst of very long duration in γ-rays where optical data could be acquired well during its active phase. The optical light curve shows very intriguing features which I subsequently interpret as the so called ''optical flash'', a fundamental property of the ''fireball'' model. Although predicted by the latter model, only a handful of GRBs show such a behavior, making them interesting transients to study. Furthermore, I present the fundamental temporal and spectral properties of 47 GBM-detected GRBs with known redshifts. As GRBs explode at cosmological distances it is of uttermost importance to study them in their restframe to get a better understanding of their emission mechanisms. I confirm several correlations already found in the past together with an intriguing connection between redshift and the peak energy (E peak ) of GRBs. Although this correlation is heavily influenced by instrumental effects, it is not unexpected from other experimental results, giving it more credibility. Finally, I present the results of the search for untriggered GRBs in GBM data. This

High-energy transients with Fermi/GBM

Energy Technology Data Exchange (ETDEWEB)

Gruber, David

2012-10-09

For most of mankind's history, astronomy was performed on-ground in the optical energy range. It was only when space-based missions, built more than 50 years ago, detected photons with mind-boggling energies that the exploration of the violent Universe really began. These {gamma}-ray photons still provide us with an unprecedented wealth of information for the most energetic processes taking place in the cosmos. Faithful to the olympic slogan ''higher, faster, further'', an increasing armada of {gamma}-ray satellites was built and launched over the last couple of decades with Fermi being the youngest of its kind. In this thesis, I use data from the Gamma-Ray Burst Monitor (GBM) onboard the Fermi satellite. The focus of this work lies on three very different classes of high-energy astrophysical transients: Gamma-Ray Bursts (GRBs), solar flares and Soft Gamma Repeaters (SGRs). In Chapter 2, I present GRB 091024A, a burst of very long duration in {gamma}-rays where optical data could be acquired well during its active phase. The optical light curve shows very intriguing features which I subsequently interpret as the so called ''optical flash'', a fundamental property of the ''fireball'' model. Although predicted by the latter model, only a handful of GRBs show such a behavior, making them interesting transients to study. Furthermore, I present the fundamental temporal and spectral properties of 47 GBM-detected GRBs with known redshifts. As GRBs explode at cosmological distances it is of uttermost importance to study them in their restframe to get a better understanding of their emission mechanisms. I confirm several correlations already found in the past together with an intriguing connection between redshift and the peak energy (E{sub peak}) of GRBs. Although this correlation is heavily influenced by instrumental effects, it is not unexpected from other experimental results, giving it more credibility

Development of THYDE-HTGR: computer code for transient thermal-hydraulics of high-temperature gas-cooled reactor

International Nuclear Information System (INIS)

Hirano, Masashi; Hada, Kazuhiko

1990-04-01

The THYDE-HTGR code has been developed for transient thermal-hydraulic analyses of high-temperature gas-cooled reactors, based on the THYDE-W code. THYDE-W is a code developed at JAERI for the simulation of Light Water Reactor plant dynamics during various types of transients including loss-of-coolant accidents. THYDE-HTGR solves the conservation equations of mass, momentum and energy for compressible gas, or single-phase or two-phase flow. The major code modification from THYDE-W is to treat helium loops as well as water loops. In parallel to this, modification has been made for the neutron kinetics to be applicable to helium-cooled graphite-moderated reactors, for the heat transfer models to be applicable to various types of heat exchangers, and so forth. In order to assess the validity of the modifications, analyses of some of the experiments conducted at the High Temperature Test Loop of ERANS have been performed. In this report, the models applied in THYDE-HTGR are described focusing on the present modifications and the results from the assessment calculations are presented. (author)

Turbofan compressor dynamics during afterburner transients

Science.gov (United States)

Kurkov, A. P.

1976-01-01

The effects of afterburner light-off and shut-down transients on the compressor stability are investigated. The reported experimental results are based on detailed high response pressure and temperature measurements on the TF30-P-3 turbofan engine. The tests were performed in an altitude test chamber simulating high altitude engine operation. It is shown that during both types of transients, flow breaks down in the forward part of the fan bypass duct. At a sufficiently low engine inlet pressure this resulted in a compressor stall. Complete flow breakdown within the compressor was preceded by a rotating stall. At some locations in the compressor, rotating stall cells initially extended only through part of the blade span. For the shutdown transient the time between first and last detected occurrence of rotating stall is related to the flow Reynolds number. An attempt was made to deduce the number and speed of propagation of rotating stall cells.

Temperature shock, injury and transient sensitivity to nisin in Gram negatives.

Science.gov (United States)

Boziaris, I S; Adams, M R

2001-10-01

The effect of thermal stresses on survival, injury and nisin sensitivity was investigated in Salmonella Enteritidis PT4, PT7 and Pseudomonas aeruginosa. Heating at 55 degrees C, rapid chilling to 0.5 degrees C or freezing at -20 degrees C produced transient sensitivity to nisin. Cells were only sensitive if nisin was present during stress. Resistance recovered rapidly afterwards, though some cells displayed residual injury. Injury was assessed by SDS sensitivity, hydrophobicity changes, lipopolysaccharide release and NPN uptake. LPS release and hydrophobicity were not always associated with transient nisin sensitivity. Uptake of NPN correlated better but persisted longer after treatment. Thermal shocks produce transient injury to the outer membrane, allowing nisin access. After treatment, the permeability barrier is rapidly restored by a process apparently involving reorganization rather than biosynthetic repair. Inclusion of nisin during food treatments that impose sub-lethal stress on Gram negatives could increase process lethality, enhancing microbiological safety and stability.

Analysis on blow-down transient in water ingress accident of high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Wang, Yan; Zheng, Yanhua; Li, Fu; Shi, Lei

2014-01-01

Water ingress into the primary circuit is generally recognized as one of the severe accidents with potential hazard to the modular high temperature gas-cooled reactor, which will cause a positive reactivity introduction with the increase of steam density in reactor core to enhance neutron slowing-down, also the chemical corrosion of graphite fuel elements and the damage of reflector structure material. The increase of the primary pressure may result in the opening of the safety valves, consequently leading the release of radioactive isotopes and flammable water gas. The research on water ingress transient is significant for the verification of inherent safety characteristics of high temperature gas-cooled reactor. The 200 MWe high temperature gas-cooled reactor (HTR-PM), designed by the Institute of Nuclear and New Energy Technology of Tsinghua University, is exampled to be analyzed in this paper. The design basis accident (DBA) scenarios of double-ended guillotine break of single heat-exchange tube (steam generator heat-exchange tube rupture) are simulated by the thermal-hydraulic analysis code, and some key concerns which are relative to the amount of water into the reactor core during the blow-down transient are analyzed in detail. The results show that both of water mass and steam ratio of the fluid spouting from the broken heat-exchange tube are affected by break location, which will increase obviously with the broken location closing to the outlet of the heat-exchange tube. The double-ended guillotine rupture at the outlet of the heat-exchange will result more steam penetrates into the reactor core in the design basis accident of water ingress. The mass of water ingress will also be affected by the draining system. It is concluded that, with reasonable optimization on design to balance safety and economy, the total mass of water ingress into the primary circuit of reactor could be limited effectively to meet the safety requirements, and the pollution of

Development of Creep-Resistant and Oxidation-Resistant Austenitic Stainless Steels for High Temperature Applications

Science.gov (United States)

Maziasz, Philip J.

2018-01-01

Austenitic stainless steels are cost-effective materials for high-temperature applications if they have the oxidation and creep resistance to withstand prolonged exposure at such conditions. Since 1990, Oak Ridge National Laboratory (ORNL) has developed advanced austenitic stainless steels with creep resistance comparable to Ni-based superalloy 617 at 800-900°C based on specially designed "engineered microstructures" utilizing a microstructure/composition database derived from about 20 years of radiation effect data on steels. The wrought high temperature-ultrafine precipitate strengthened (HT-UPS) steels with outstanding creep resistance at 700-800°C were developed for supercritical boiler and superheater tubing for fossil power plants in the early 1990s, the cast CF8C-Plus steels were developed in 1999-2001 for land-based gas turbine casing and diesel engine exhaust manifold and turbocharger applications at 700-900°C, and, in 2015-2017, new Al-modified cast stainless steels with oxidation and creep resistance capabilities up to 950-1000°C were developed for automotive exhaust manifold and turbocharger applications. This article reviews and summarizes their development and their properties and applications.

High efficiency algorithm for 3D transient thermo-elasto-plastic contact problem in reactor pressure vessel sealing system

International Nuclear Information System (INIS)

Xu Mingyu; Lin Tengjiao; Li Runfang; Du Xuesong; Li Shuian; Yang Yu

2005-01-01

There are some complex operating cases such as high temperature and high pressure during the operating process of nuclear reactor pressure vessel. It is necessary to carry out mechanical analysis and experimental investigation for its sealing ability. On the basis of the self-developed program for 3-D transient sealing analysis for nuclear reactor pressure vessel, some specific measures are presented to enhance the calculation efficiency in several aspects such as the non-linear solution of elasto-plastic problem, the mixed solution algorithm for contact problem as well as contract heat transfer problem and linear equation set solver. The 3-D transient sealing analysis program is amended and complemented, with which the sealing analysis result of the pressure vessel model can be obtained. The calculation results have good regularity and the calculation efficiency is twice more than before. (authors)

Oat beta-glucan ameliorates insulin resistance in mice fed on high-fat and high-fructose diet

Directory of Open Access Journals (Sweden)

Jie Zheng

2013-12-01

Full Text Available Methods: This study sought to evaluate the impact of oat beta-glucan on insulin resistance in mice fed on high-fat and high-fructose diet with fructose (10%, w/v added in drinking water for 10 weeks. Results: The results showed that supplementation with oat beta-glucan could significantly reduce the insulin resistance both in low-dose (200 mg/kg−1 body weight and high-dose (500 mg/kg−1 body weight groups, but the high-dose group showed a more significant improvement in insulin resistance (P<0.01 compared with model control (MC group along with significant improvement in hepatic glycogen level, oral glucose, and insulin tolerance. Moreover, hepatic glucokinase activity was markedly enhanced both in low-dose and high-dose groups compared with that of MC group (P<0.05. Conclusion: These results suggested that supplementation of oat beta-glucan alleviated insulin resistance and the effect was dose dependent.

Transient and steady-state analyses of an electrically heated Topaz-II Thermionic Fuel Element

International Nuclear Information System (INIS)

El-Genk, M.S.; Xue, H.

1992-01-01

Transient and steady-state analyses of electrically heated, Thermionic Fuel Elements (TFEs) for Topaz-II space power system are performed. The calculated emitter and collector temperatures, load electric power and conversion efficiency are in good agreement with reported data. In this paper the effects or Cs pressure, thermal power input, and load resistance on the steady-state performance of the TFE are also investigated. In addition, the thermal response of the ZrH moderator during a startup transient and following a change in the thermal power input is examined

Advanced hybrid transient stability and EMT simulation for VSC-HVDC systems

NARCIS (Netherlands)

Van Der Meer, A.A.; Gibescu, M.; Van Der Meijden, M.A.M.M.; Kling, W.L.; Ferreira, J.A.

2015-01-01

This paper deals with advanced hybrid transient stability and electromagnetic-transient (EMT) simulation of combined ac/dc power systems containing large amounts of renewable energy sources interfaced through voltage-source converter-high-voltage direct current (VSC-HVDC). The concerning transient

Transient performance estimation of charge plasma based negative capacitance junctionless tunnel FET

International Nuclear Information System (INIS)

Singh, Sangeeta; Kondekar, P. N.; Pal, Pawan

2016-01-01

We investigate the transient behavior of an n-type double gate negative capacitance junctionless tunnel field effect transistor (NC-JLTFET). The structure is realized by using the work-function engineering of metal electrodes over a heavily doped n + silicon channel and a ferroelectric gate stack to get negative capacitance behavior. The positive feedback in the electric dipoles of ferroelectric materials results in applied gate bias boosting. Various device transient parameters viz. transconductance, output resistance, output conductance, intrinsic gain, intrinsic gate delay, transconductance generation factor and unity gain frequency are analyzed using ac analysis of the device. To study the impact of the work-function variation of control and source gate on device performance, sensitivity analysis of the device has been carried out by varying these parameters. Simulation study reveals that it preserves inherent advantages of charge-plasma junctionless structure and exhibits improved transient behavior as well. (paper)

Effect of physiological age on radiation resistance of some bacteria that are highly radiation resistant

International Nuclear Information System (INIS)

Keller, L.C.; Maxcy, R.B.

1984-01-01

Physiological age-dependent variation in radiation resistance was studied for three bacteria that are highly radiation resistant: Micrococcus radiodurans, Micrococcus sp. isolate C-3, and Moraxella sp. isolate 4. Stationary-phase cultures of M. radiodurans and isolate C-3 were much more resistant to gamma radiation than were log-phase cultures. This pattern of relative resistance was reversed for isolate 4. Resistance of isolate 4 to UV light was also greater during log phase, although heat resistance and NaCl tolerance after heat stresses were greater during stationary phase. Radiation-induced injury of isolate 4 compared with injury of Escherichia coli B suggested that the injury process, as well as the lethal process, was affected by growth phase. The hypothesis that growth rate affects radiation resistance was tested, and results were interpreted in light of the probable confounding effect of methods used to alter growth rates of bacteria. These results indicate that dose-response experiments should be designed to measure survival during the most resistant growth phase of the organism under study. The timing is particularly important when extrapolations of survival results might be made to potential irradiation processes for foods. 17 references

Cementitious artificial aggregate particles for high-skid resistance pavements

OpenAIRE

DE LARRARD, François; MARTINEZ CASTILLO, Rafael; SEDRAN, Thierry; HAUZA, Philippe; POIRIER, Jean Eric

2012-01-01

For some critical road sections, a high skid resistance of wearing course is required to minimise the risk of traffic accidents. Nowadays this skid resistance is mainly brought by the use of special aggregates as calcined bauxite, a scarce and expensive material. The paper presents a patented technology, where a special high-performance mortar is produced and crushed at early age. These cementitious artificial aggregates (CAA) can display aggregate properties close to those of calcined bauxit...

Shape memory alloy resistance behaviour at high altitude for feedback control

Science.gov (United States)

Ng, W. T.; Sedan, M. F.; Abdullah, E. J.; Azrad, S.; Harithuddin, A. S. M.

2017-12-01

Many recent aerospace technologies are using smart actuators to reduce the system's complexity and increase its reliability. One such actuator is shape memory alloy (SMA) actuator, which is lightweight, produces high force and large deflection. However, some disadvantages in using SMA actuators have been identified and they include nonlinear response of the strain to input current, hysteresis characteristic that results in inaccurate control and less than optimum system performance, high operating temperatures, slow response and also high requirement of electrical power to obtain the desired actuation forces. It is still unknown if the SMA actuators can perform effectively at high altitude with low surrounding temperature. The work presented here covers the preliminary process of verifying the feasibility of using resistance as feedback control at high altitude for aerospace applications. Temperature and resistance of SMA actuator at high altitude is investigated by conducting an experiment onboard a high altitude balloon. The results from the high altitude experiment indicate that the resistance or voltage drop of the SMA wire is not significantly affected by the low surrounding temperature at high altitude as compared to the temperature of SMA. Resistance feedback control for SMA actuators may be suitable for aerospace applications.

Polycistronic artificial miRNA-mediated resistance to Wheat dwarf virus in barley is highly efficient at low temperature.

Science.gov (United States)

Kis, András; Tholt, Gergely; Ivanics, Milán; Várallyay, Éva; Jenes, Barnabás; Havelda, Zoltán

2016-04-01

Infection of Wheat dwarf virus (WDV) strains on barley results in dwarf disease, imposing severe economic losses on crop production. As the natural resistance resources against this virus are limited, it is imperative to elaborate a biotechnological approach that will provide effective and safe immunity to a wide range of WDV strains. Because vector insect-mediated WDV infection occurs during cool periods in nature, it is important to identify a technology which is effective at lower temperature. In this study, we designed artificial microRNAs (amiRNAs) using a barley miRNA precursor backbone, which target different conservative sequence elements of the WDV strains. Potential amiRNA sequences were selected to minimize the off-target effects and were tested in a transient sensor system in order to select the most effective constructs at low temperature. On the basis of the data obtained, a polycistronic amiRNA precursor construct (VirusBuster171) was built expressing three amiRNAs simultaneously. The construct was transformed into barley under the control of a constitutive promoter. The transgenic lines were kept at 12-15 °C to mimic autumn and spring conditions in which major WDV infection and accumulation take place. We were able to establish a stable barley transgenic line displaying resistance to insect-mediated WDV infection. Our study demonstrates that amiRNA technology can be an efficient tool for the introduction of highly efficient resistance in barley against a DNA virus belonging to the Geminiviridae family, and this resistance is effective at low temperature where the natural insect vector mediates the infection process. © 2015 BSPP and John Wiley & Sons Ltd.

High temperature creep strength of Advanced Radiation Resistant Oxide Dispersion Strengthened Steels

Energy Technology Data Exchange (ETDEWEB)

Noh, Sanghoon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Austenitic stainless steel may be one of the candidates because of good strength and corrosion resistance at the high temperatures, however irradiation swelling well occurred to 120dpa at high temperatures and this leads the decrease of the mechanical properties and dimensional stability. Compared to this, ferritic/martensitic steel is a good solution because of excellent thermal conductivity and good swelling resistance. Unfortunately, the available temperature range of ferritic/martensitic steel is limited up to 650 .deg. C. ODS steel is the most promising structural material because of excellent creep and irradiation resistance by uniformly distributed nano-oxide particles with a high density which is extremely stable at the high temperature in ferritic/martensitic matrix. In this study, high temperature strength of advanced radiation resistance ODS steel was investigated for the core structural material of next generation nuclear systems. ODS martensitic steel was designed to have high homogeneity, productivity and reproducibility. Mechanical alloying, hot isostactic pressing and hot rolling processes were employed to fabricate the ODS steels, and creep rupture test as well as tensile test were examined to investigate the behavior at high temperatures. ODS steels were fabricated by a mechanical alloying and hot consolidation processes. Mechanical properties at high temperatures were investigated. The creep resistance of advanced radiation resistant ODS steels was more superior than those of ferritic/ martensitic steel, austenitic stainless steel and even a conventional ODS steel.

Improved lumped models for transient combined convective and radiative cooling of a two-layer spherical fuel element

International Nuclear Information System (INIS)

Silva, Alice Cunha da; Su, Jian

2013-01-01

The High Temperature Gas cooled Reactor (HTGR) is a fourth generation thermal nuclear reactor, graphite-moderated and helium cooled. The HTGRs have important characteristics making essential the study of these reactors, as well as its fuel element. Examples of these are: high thermal efficiency,low operating costs and construction, passive safety attributes that allow implication of the respective plants. The Pebble Bed Modular Reactor (PBMR) is a HTGR with spherical fuel elements that named the reactor. This fuel element is composed by a particulate region with spherical inclusions, the fuel UO2 particles, dispersed in a graphite matrix and a convective heat transfer by Helium happens on the outer surface of the fuel element. In this work, the transient heat conduction in a spherical fuel element of a pebble-bed high temperature reactor was studied in a transient situation of combined convective and radiative cooling. Improved lumped parameter model was developed for the transient heat conduction in the two-layer composite sphere subjected to combined convective and radiative cooling. The improved lumped model was obtained through two-point Hermite approximations for integrals. Transient combined convective and radiative cooling of the two-layer spherical fuel element was analyzed to illustrate the applicability of the proposed lumped model, with respect to die rent values of the Biot number, the radiation-conduction parameter, the dimensionless thermal contact resistance, the dimensionless inner diameter and coating thickness, and the dimensionless thermal conductivity. It was shown by comparison with numerical solution of the original distributed parameter model that the improved lumped model, with H2,1/H1,1/H0,0 approximation yielded significant improvement of average temperature prediction over the classical lumped model. (author)

CMOS pixel sensors on high resistive substrate for high-rate, high-radiation environments

Energy Technology Data Exchange (ETDEWEB)

Hirono, Toko, E-mail: thirono@uni-bonn.de [Physikalisches Institute der Universität Bonn, Bonn (Germany); Barbero, Marlon; Breugnon, Patrick; Godiot, Stephanie [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Gonella, Laura; Hemperek, Tomasz; Hügging, Fabian; Krüger, Hans [Physikalisches Institute der Universität Bonn, Bonn (Germany); Liu, Jian; Pangaud, Patrick [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Peric, Ivan [IPE, Karlsruher Institut für Technologie, Karlsruhe (Germany); Pohl, David-Leon [Physikalisches Institute der Universität Bonn, Bonn (Germany); Rozanov, Alexandre [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Rymaszewski, Piotr [Physikalisches Institute der Universität Bonn, Bonn (Germany); Wang, Anqing [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Wermes, Norbert [Physikalisches Institute der Universität Bonn, Bonn (Germany)

2016-09-21

A depleted CMOS active pixel sensor (DMAPS) has been developed on a substrate with high resistivity in a high voltage process. High radiation tolerance and high time resolution can be expected because of the charge collection by drift. A prototype of DMAPS was fabricated in a 150 nm process by LFoundry. Two variants of the pixel layout were tested, and the measured depletion depths of the variants are 166 μm and 80 μm. We report the results obtained with the prototype fabricated in this technology.

Analysis of the FFTF primary pipe rupture transients

International Nuclear Information System (INIS)

Perkins, K.R.; Bari, R.A.; Chen, L.C.; Albright, D.C.

1979-01-01

The response of the Fast Flux Test Facility (FFTF) to hypothetical ruptures of the high pressure primary piping has been analyzed using two LMFBR plant systems codes, namely IANUS and DEMO. Comparisons of the average channel temperatures predicted by the two codes show good agreement for identical transients. However, the hot channel temperatures predicted by DEMO are about 60K higher than the corresponding IANUS predictions for severe transients. This difference is attributed to the dynamic hot channel factors employed in DEMO which discount the thermal inertia of the duct walls for rapid transients. DEMO also predicts more severe transients for hot-leg ruptures in FFTF than previously reported analyses for the CRBR

Investigation of natural circulation instability and transients in passively safe novel modular reactor

Science.gov (United States)

Shi, Shanbin

The Purdue Novel Modular Reactor (NMR) is a new type small modular reactor (SMR) that belongs to the design of boiling water reactor (BWR). Specifically, the NMR is one third the height and area of a conventional BWR reactor pressure vessel (RPV) with an electric output of 50 MWe. The fuel cycle length of the NMR-50 is extended up to 10 years due to optimized neutronics design. The NMR-50 is designed with double passive engineering safety system. However, natural circulation BWRs (NCBWR) could experience certain operational difficulties due to flow instabilities that occur at low pressure and low power conditions. Static instabilities (i.e. flow excursion (Ledinegg) instability and flow pattern transition instability) and dynamic instabilities (i.e. density wave instability and flashing/condensation instability) pose a significant challenge in two-phase natural circulation systems. In order to experimentally study the natural circulation flow instability, a proper scaling methodology is needed to build a reduced-size test facility. The scaling analysis of the NMR uses a three-level scaling method, which was developed and applied for the design of the Purdue Multi-dimensional Integral Test Assembly (PUMA). Scaling criteria is derived from dimensionless field equations and constitutive equations. The scaling process is validated by the RELAP5 analysis for both steady state and startup transients. A new well-scaled natural circulation test facility is designed and constructed based on the scaling analysis of the NMR-50. The experimental facility is installed with different equipment to measure various thermal-hydraulic parameters such as pressure, temperature, mass flow rate and void fraction. Characterization tests are performed before the startup transient tests and quasi-steady tests to determine the loop flow resistance. The controlling system and data acquisition system are programmed with LabVIEW to realize the real-time control and data storage. The thermal

Borides - a new generation of highly resistant materials?

International Nuclear Information System (INIS)

Telle, R.

1988-01-01

High-duty ceramics are on advance in all sectors where materials with extremely good resistance to high temperatures and wear are required. The group of oxides, nitrides and carbides in use for quite a time now recently has been increased by the metal borides which offer among others economic advantages in certain applications. The drawbacks of these materials still to be reduced are their brittleness and susceptibility to oxidation and corrosion. Current research work on the thermodynamics of such systems, on the interaction between structure and properties, and on means to improve strength and resistance to wear are expected to soon open up new applications. (orig.) [de

Transient voltage oscillations in coils

International Nuclear Information System (INIS)

Chowdhuri, P.

1985-01-01

Magnet coils may be excited into internal voltage oscillations by transient voltages. Such oscillations may electrically stress the magnet's dielectric components to many times its normal stress. This may precipitate a dielectric failure, and the attendant prolonged loss of service and costly repair work. Therefore, it is important to know the natural frequencies of oscillations of a magnet during the design stage, and to determine whether the expected switching transient voltages can excite the magnet into high-voltage internal oscillations. The series capacitance of a winding significantly affects its natural frequencies. However, the series capacitance is difficult to calculate, because it may comprise complex capacitance network, consisting of intra- and inter-coil turn-to-turn capacitances of the coil sections. A method of calculating the series capacitance of a winding is proposed. This method is rigorous but simple to execute. The time-varying transient voltages along the winding are also calculated

Resistance Exercise Attenuates High-Fructose, High-Fat-Induced Postprandial Lipemia

OpenAIRE

Jessie R. Wilburn; Jeffrey Bourquin; Andrea Wysong; Christopher L. Melby

2015-01-01

Introduction Meals rich in both fructose and fat are commonly consumed by many Americans, especially young men, which can produce a significant postprandial lipemic response. Increasing evidence suggests that aerobic exercise can attenuate the postprandial increase in plasma triacylglycerols (TAGs) in response to a high-fat or a high-fructose meal. However, it is unknown if resistance exercise can dampen the postprandial lipemic response to a meal rich in both fructose and fat. Methods Eight ...

Current interruption transients calculation

CERN Document Server

Peelo, David F

2014-01-01

Provides an original, detailed and practical description of current interruption transients, origins, and the circuits involved, and how they can be calculated Current Interruption Transients Calculationis a comprehensive resource for the understanding, calculation and analysis of the transient recovery voltages (TRVs) and related re-ignition or re-striking transients associated with fault current interruption and the switching of inductive and capacitive load currents in circuits. This book provides an original, detailed and practical description of current interruption transients, origins,

Multi-Electrode Resistivity Probe for Investigation of Local Temperature Inside Metal Shell Battery Cells via Resistivity: Experiments and Evaluation of Electrical Resistance Tomography

Directory of Open Access Journals (Sweden)

Xiaobin Hong

2015-01-01

Full Text Available Direct Current (DC electrical resistivity is a material property that is sensitive to temperature changes. In this paper, the relationship between resistivity and local temperature inside steel shell battery cells (two commercial 10 Ah and 4.5 Ah lithium-ion cells is innovatively studied by Electrical Resistance Tomography (ERT. The Schlumberger configuration in ERT is applied to divide the cell body into several blocks distributed in different levels, where the apparent resistivities are measured by multi-electrode surface probes. The investigated temperature ranges from −20 to 80 °C. Experimental results have shown that the resistivities mainly depend on temperature changes in each block of the two cells used and the function of the resistivity and temperature can be fitted to the ERT-measurement results in the logistical-plot. Subsequently, the dependence of resistivity on the state of charge (SOC is investigated, and the SOC range of 70%–100% has a remarkable impact on the resistivity at low temperatures. The proposed approach under a thermal cool down regime is demonstrated to monitor the local transient temperature.

New approach of a transient ICP-MS measurement method for samples with high salinity.

Science.gov (United States)

Hein, Christina; Sander, Jonas Michael; Kautenburger, Ralf

2017-03-01

In the near future it is necessary to establish a disposal for high level nuclear waste (HLW) in deep and stable geological formations. In Germany typical host rocks are salt or claystone. Suitable clay formations exist in the south and in the north of Germany. The geochemical conditions of these clay formations show a strong difference. In the northern ionic strengths of the pore water up to 5M are observed. The determination of parameters like K d values during sorption experiments of metal ions like uranium or europium as homologues for trivalent actinides onto clay stones are very important for long term safety analysis. The measurement of the low concentrated, not sorbed analytes commonly takes place by inductively coupled plasma mass spectrometry (ICP-MS). A direct measurement of high saline samples like seawater with more than 1% total dissolved salt content is not possible. Alternatives like sample clean up, preconcentration or strong dilution have more disadvantages than advantages for example more preparation steps or additional and expensive components. With a small modification of the ICP-MS sample introduction system and a home-made reprogramming of the autosampler a transient analysing method was developed which is suitable for measuring metal ions like europium and uranium in high saline sample matrices up to 5M (NaCl). Comparisons at low ionic strength between the default and the transient measurement show the latter performs similarly well to the default measurement. Additionally no time consuming sample clean-up or expensive online dilution or matrix removal systems are necessary and the analysation shows a high sensitivity due to the data processing based on the peak area. Copyright © 2016 Elsevier B.V. All rights reserved.

Study of current instabilities in high resistivity gallium arsenide

International Nuclear Information System (INIS)

Barraud, A.

1968-01-01

We have shown the existence and made a study of the current oscillations produced in high-resistivity gallium arsenide by a strong electric field. The oscillations are associated with the slow travelling of a region of high electrical field across the whole sample. An experimental study of the properties of these instabilities has made it possible for us to distinguish this phenomenon from the Gunn effect, from acoustic-electric effects and from contact effects. In order to account for this type of instability, a differential trapping mechanism involving repulsive impurities is proposed; this mechanism can reduce the concentration of charge carriers in the conduction band at strong electrical fields and can lead to the production of a high-field domain. By developing this model qualitatively we have been able to account for all the properties of high-resistance gallium arsenide crystals subjected to a strong electrical field: increase of the Hall constant, existence of a voltage threshold for these oscillations, production of domains of high field, low rate of propagation of these domains, and finally the possibility of inverting the direction of the propagation of the domain without destroying the latter. A quantitative development of the model makes it possible to calculate the various characteristic parameters of these instabilities. Comparison with experiment shows that there is a good agreement, the small deviations coming especially from the lack of knowledge concerning transport properties in gallium arsenide subjected to high fields. From a study of this model, it appears that the instability phenomenon can occur over a wide range of repulsive centre concentrations, and also for a large range of resistivities. This is the reason why it appears systematically in gallium arsenide of medium and high resistivity. (authors) [fr

Electrical resistivity of UBe13 in high magnetic fields

International Nuclear Information System (INIS)

Schmiedeshoff, G.M.; Lacerda, A.; Fisk, Z.; Smith, J.L.

1996-01-01

We have measured the temperature dependent electrical resistivity of single and polycrystal samples of UBe 13 in high magnetic fields. Two maxima in the resistivity are observed at T M1 and T M2 . T M1 , the temperature of the colder maximum, increases quadratically with magnetic field H, a field dependence previously observed under hydrostatic pressure. The high temperature maximum at T M2 emerges in fields above about 4 T and increases linearly with H, a behavior which may be due to a sharpening of the crystal field levels associated with a depression of the Kondo effect by high magnetic fields. copyright 1996 The American Physical Society

Development of a high strength, hydrogen-resistant austenitic alloy

International Nuclear Information System (INIS)

Chang, K.M.; Klahn, D.H.; Morris, J.W. Jr.

1980-08-01

Research toward high-strength, high toughness nonmagnetic steels for use in the retaining rings of large electrical generators led to the development of a Ta-modified iron-based superalloy (Fe-36 Ni-3 Ti-3 Ta-0.5 Al-1.3 Mo-0.3 V-0.01 B) which combines high strength with good toughness after suitable aging. The alloy did, however, show some degradation in fatigue resistance in gaseous hydrogen. This sensitivity was associated with a deformation-induced martensitic transformation near the fracture surface. The addition of a small amount of chromium to the alloy suppressed the martensite transformation and led to a marked improvement in hydrogen resistance

Demonstration of a transient high gain nickel-like xenon ion x-ray laser

International Nuclear Information System (INIS)

Lu, Peixiang; Kawachi, Tetsuya; Kishimoto, Maki

2003-01-01

We demonstrate a high gain nickel-like xenon ion x-ray laser using a picosecond-laser-irradiated gas puff target. The elongated x-ray laser plasma column was produced by irradiating the gas puff target with line-focused double picosecond laser pulses with a total energy of 18 J in a travelling-wave excitation scheme. Strong lasing at 9.98 nm was observed, and a high gain coefficient of 17.4 cm -1 was measured on the transient collisionally excited 4d-4p, J=0-1 transition for nickel-like xenon ion with target lengths up to 0.45 cm. A weak nickel-like lasing line at a shorter wavelength of 9.64 nm was also observed with a gain coefficient of 5.9 cm -1 . (author)

Study on the transient properties of amorphous solar cells

Science.gov (United States)

Smrity, Manu; Dhariwal, S. R.

2016-05-01

The transient response for the solar cell when switched off from steady-state can provide useful information about the quality of the material used for fabrication of the device. In this paper we shall discuss the photovoltaic transients of amorphous silicon solar cells when switched off from open circuit configuration and illuminated by electrical pulse. The open-circuit voltage (Voc) decay can be performed by two methods, by optical excitation and by electrical pulse. When one of carriers has a concentration much higher than the other the photoconductivity is dominated by majority carriers; in that case the Voc decay which depends on the np product can be used as complementary method for obtaining information about the minority carriers. Also the series resistance drop in an electrical Voc decay method can be used to obtain a IJ't product as an additional information regarding the material of the device.

Semi-transparent gold film as simultaneous surface heater and resistance thermometer for nucleate boiling studies

International Nuclear Information System (INIS)

Oker, E.; Merte, H. Jr.

1981-01-01

A large (22 x 25 mm) semi-transparent thin film of gold, approximately 400 A in thickness, is deposited on a glass substrate for simultaneous use as a heat source and resistance thermometer. Construction techniques and calibration procedures are described, and a sample application to a transient boiling process is included with simultaneous high speed photographs taken through the thin film from beneath

Transient ischemic attack presenting in an elderly patient with transient ophthalmic manifestations

Directory of Open Access Journals (Sweden)

Sparshi Jain

2016-01-01

Full Text Available Transient ischemic attack (TIA is a transient neurological deficit of cerebrovascular origin without infarction which may last only for a short period and can have varying presentations. We report a case of 58-year-old male with presenting features of sudden onset transient vertical diplopia and transient rotatory nystagmus which self-resolved within 12 h. Patient had no history of any systemic illness. On investigating, hematological investigations and neuroimaging could not explain these sudden and transient findings. A TIA could possibly explain these sudden and transient ocular findings in our patient. This case report aims to highlight the importance of TIA for ophthalmologists. We must not ignore these findings as these could be warning signs of an impending stroke which may or may not be detected on neuroimaging. Thus, early recognition, primary prevention strategies, and timely intervention are needed.

High resolution deep level transient spectroscopy and process-induced defects in silicon

International Nuclear Information System (INIS)

Evans-Freeman, J.H.; Emiroglu, D.; Vernon-Parry, K.D.

2004-01-01

High resolution, or Laplace, deep level transient spectroscopy (LDLTS) enables the identification of very closely spaced energetic levels in a semiconductor bandgap. DLTS may resolve peaks with a separation of tens of electron volts, but LDLTS can resolve defect energy separations as low as a few MeV. In this paper, we present results from LDLTS applied to ion implantation-induced defects in silicon, with particular emphasis on characterisation of end-of-range interstitial type defects. Silicon was implanted with a variety of ions from mass 28 to 166. A combination of LDLTS and direct capture cross-section measurements was employed to show that electrically active small extended defects were present in the as-implanted samples. Larger dislocations were then generated in Si by oxygenation to act as a control sample. These stacking faults had typical lengths of microns, and their electrical activity was subsequently characterised by LDLTS. This was to establish the sensitivity of LDLTS to defects whose carrier capture is characterised by a non-exponential filling process and an evolving band structure as carrier capture proceeds. The LDLTS spectra show several components in capacitance transients originating from both the end-of-range defects, and the stacking faults, and also clearly show that the carrier emission rates reduce as these extended defects fill with carriers. The end-of-range defects and the stacking faults are shown to have the same electrical behaviour

Interpreting signals from astrophysical transient experiments.

Science.gov (United States)

O'Brien, Paul T; Smartt, Stephen J

2013-06-13

Time-domain astronomy has come of age with astronomers now able to monitor the sky at high cadence, both across the electromagnetic spectrum and using neutrinos and gravitational waves. The advent of new observing facilities permits new science, but the ever-increasing throughput of facilities demands efficient communication of coincident detections and better subsequent coordination among the scientific community so as to turn detections into scientific discoveries. To discuss the revolution occurring in our ability to monitor the Universe and the challenges it brings, on 25-26 April 2012, a group of scientists from observational and theoretical teams studying transients met with representatives of the major international transient observing facilities at the Kavli Royal Society International Centre, UK. This immediately followed the Royal Society Discussion Meeting 'New windows on transients across the Universe' held in London. Here, we present a summary of the Kavli meeting at which the participants discussed the science goals common to the transient astronomy community and analysed how to better meet the challenges ahead as ever more powerful observational facilities come on stream.

An MOT-TDIE solver for analyzing transient fields on graphene-based devices

KAUST Repository

Shi, Yifei

2016-11-02

A marching on-in-time (MOT) scheme for analyzing transient electromagnetic wave interactions on devices consisting of graphene sheets and dielectric substrates is proposed. The MOT scheme discretizes time domain resistive boundary condition (TD-RBC) and Poggio-Miller-Chang-Harrington-Wu-Tsai (TD-PMCHWT) integral equation, which are enforced on the surfaces of the graphene and dielectric substrate, respectively. The expressions of the time domain resistivity and conductivity of the graphene sheet are obtained analytically from the intra-band contribution formulated in frequency domain. Numerical results, which demonstrate the applicability of the proposed scheme, are presented.

ELECTROMECHANICAL TRANSIENT PROCESSES DURING SUPPLY VOLTAGE CHANGING IN THE SYSTEM OF POLYMER INSULATION COVERING OF THE CURRENT-CARRYING CORE OF ULTRA HIGH VOLTAGE CABLES

Directory of Open Access Journals (Sweden)

V. M. Zolotaryov

2018-04-01

Full Text Available Aim. The article is devoted to the analysis of the electromechanical transient processes in a system of three frequency-controlled electric drives based on asynchronous motors that control current-carrying core motion, as well as to the study of the effect of such processes on the modes applying three-layer polymer insulation to the current-carrying core. Technique. The study was conducted based on the concepts of electromechanics, electromagnetic field theory, mathematical physics, mathematical modeling. Results. A mathematical model has been developed to analyze transients in an electromechanical system consisting of three frequency-controlled electric drives providing current-carrying core motion of ultra-high voltage cables in an inclined extrusion line. The coordination of the electromechanical parameters of the system drives has been carried out and the permissible changes in the supply voltage at the limiting mass while moving current-carrying core of ultra-high voltage cables with applied polymer insulation have been estimated. Scientific novelty. For the first time it is determined that with the limiting mass of the current-carrying core, the electromechanical system allows to stabilize the current-carrying core speed with the required accuracy at short-term decreases in the supply voltage by no more than 27 % of its amplitude value. It is also shown that this system is resistant to short-term increases in voltage by 32 % for 0.2 s. Practical significance. Using the developed model, it is possible to calculate the change in the configuration and speed of the slack current-carrying core when applying polymer insulation, depending on the specific mass of the current-carrying core per unit length, its tension at the bottom, the torque of the traction motor and the supply voltage to achieve stable operation of the system and accurate working of the set parameters.

Polystyrene negative resist for high-resolution electron beam lithography

Directory of Open Access Journals (Sweden)

Ma Siqi

2011-01-01

Full Text Available Abstract We studied the exposure behavior of low molecular weight polystyrene as a negative tone electron beam lithography (EBL resist, with the goal of finding the ultimate achievable resolution. It demonstrated fairly well-defined patterning of a 20-nm period line array and a 15-nm period dot array, which are the densest patterns ever achieved using organic EBL resists. Such dense patterns can be achieved both at 20 and 5 keV beam energies using different developers. In addition to its ultra-high resolution capability, polystyrene is a simple and low-cost resist with easy process control and practically unlimited shelf life. It is also considerably more resistant to dry etching than PMMA. With a low sensitivity, it would find applications where negative resist is desired and throughput is not a major concern.

Predicting dermal absorption of gas-phase chemicals: transient model development, evaluation, and application

DEFF Research Database (Denmark)

Gong, M.; Zhang, Y.; Weschler, Charles J.

2014-01-01

A transient model is developed to predict dermal absorption of gas-phase chemicals via direct air-to-skin-to-blood transport under non-steady-state conditions. It differs from published models in that it considers convective mass-transfer resistance in the boundary layer of air adjacent to the skin....... Results calculated with this transient model are in good agreement with the limited experimental results that are available for comparison. The sensitivity of the modeled estimates to key parameters is examined. The model is then used to estimate air-to-skin-to-blood absorption of six phthalate esters...... and less absorbed into blood than would a steady-state model. In the 7-day scenario, results calculated by the transient and steady-state models converge over a time period that varies between 3 and 4days for all but the largest phthalate (DEHP). Dermal intake is comparable to or larger than inhalation...

Fission gas behavior during fast thermal transients

International Nuclear Information System (INIS)

Esteves, R.G.

1976-01-01

The behavior of non-equilibrium fission in fuel elements undergoing fast thermal transients is analyzed. To facilitate the analysis, a new variable, the equilibrium variable (EV) is defined. This variable, together with bubble radius, completely specifies a bubble with respect to its size and equilibrium condition. The analysis is coded using a two-variable (radius and EV) multigroup numerical approximation that accepts as input the time-temperature history, the time-fission rate history, and the time-thermal gradient history of the fuel element. Studies were performed to test the code for convergence with respect to the time interval and the number of groups chosen. For a series of transient simulation studies, the measurements obtained at HEDL (microscopic examination of intragranular porosity in oxide fuel transient-tested in TREAT) are used. Two different transient histories were selected; the first, a high-temperature transient (HTT) with a peak at 2477 0 K and the second, a low-temperature transient (LTT) with a peak-temperature at 2000 0 K. The LTT was simulated for three different conditions: Bubbles were allowed to move via (a) only biased migration, (b) via random migration, and (c) via both mechanisms. The HTT was also run for both mechanisms. The agreement with HEDL microscopic observations was fair for bubbles smaller than 964 A in diameter, and poor for larger bubbles. Bubbles that grew during the heat-up part of the transient were frozen at a larger size during the cool down

The Virtual Resistance Control Strategy for HVRT of Doubly Fed Induction Wind Generators Based on Particle Swarm Optimization

Directory of Open Access Journals (Sweden)

Zhen Xie

2014-01-01

Full Text Available Grid voltage swell will cause transient DC flux component in the doubly fed induction generator (DFIG stator windings, creating serious stator and rotor current and torque oscillation, which is more serious than influence of the voltage dip. It is found that virtual resistance manages effectively to suppress rotor current and torque oscillation, avoid the operation of crowbar circuit, and enhance its high voltage ride through technology capability. In order to acquire the best virtual resistance value, the excellent particle library (EPL of dynamic particle swarm optimization (PSO algorithm is proposed. It takes the rotor voltage and rotor current as two objectives, which has a fast convergence performance and high accuracy. Simulation and experimental results verify the effectiveness of the virtual resistance control strategy.

Development of high electrical resistance persistent current switch for high speed energization system

International Nuclear Information System (INIS)

Jizo, Y.; Furuta, Y.; Nakashima, H.

1986-01-01

Japanese National Railways is now developing a superconducting magnetically-levitated train system. A persistent current switch is incorporated in the super-conducting magnet used in the magnetically-levitated train. In recent years, the switch has been required to have higher electrical resistance during its off-state in order to realize the high speed energization/de-energization system of the superconducting magnets. The system aims to decrease evaporation volume of liquid helium during the energization/de-energization of the magnet, by means of energizing the superconducting magnet with high current increasing/decreasing rate. Consequently, it would be possible to decrease the dependence of the on-board magnet system upon the ground cooling system. Through the development of a stable superconductive wire material and a coil structure for the persistent current switch using many small model switches which were produced in order to improve their current carrying capacities, the authors have succeeded in manufacturing the high electrical resistance persistent current switch whose electrical resistance was 5 ohms. The switch, of cylindrical shape, has a diameter of about 100mm, a length of about 100mm. These 5 ohm PCSs are now functioning in stable conditions being incorporated in the superconducting magnets of No.2 vehicle of MLU001 at the JNR's Miyazaki test track. Further, the authors are now developing the PCS of still higher resistance values, such as 50 ohms, through studies for stabilization in structural aspects of the winding and obtaining results therefrom

Considerations in designing and using superconductors with high resistivity matrices

International Nuclear Information System (INIS)

Bartlett, R.J.; Carlson, R.V.; Laquer, H.L.; Migliori, A.

1976-01-01

Superconductors are often designed with matrices of much higher residual resistivities than copper for reasons of manufacturing (multifilamentary Nb 3 Sn in CuSn bronze) or loss reduction (mixed matrix NbTi with Cu and CuNi). The high resistivity matrix may complicate or degrade contact resistances at the joints, generate excess heat, reduce the stability of the conductor, and interfere with the observation of flux flow resistivities in the 10 -12 Ω-cm region. The minimization of these effects is discussed, presenting both simple and more refined models for the current transfer length, and it is shown how variations in transfer length (with current), particularly under significant self field conditions, can mimic flux flow resistivity

High resistivity in InP by helium bombardment

International Nuclear Information System (INIS)

Focht, M.W.; Macrander, A.T.; Schwartz, B.; Feldman, L.C.

1984-01-01

Helium implants over a fluence range from 10 11 to 10 16 ions/cm 2 , reproducibly form high resistivity regions in both p- and n-type InP. Average resistivities of greater than 10 9 Ω cm for p-type InP and of 10 3 Ω cm for n-type InP are reported. Results are presented of a Monte Carlo simulation of helium bombardment into the compound target InP that yields the mean projected range and the range straggling

Transient drainage summary report

International Nuclear Information System (INIS)

1996-09-01

This report summarizes the history of transient drainage issues on the Uranium Mill Tailings Remedial Action (UMTRA) Project. It defines and describes the UMTRA Project disposal cell transient drainage process and chronicles UMTRA Project treatment of the transient drainage phenomenon. Section 4.0 includes a conceptual cross section of each UMTRA Project disposal site and summarizes design and construction information, the ground water protection strategy, and the potential for transient drainage

TRANSIENT ELECTRONICS CATEGORIZATION

Science.gov (United States)

2017-08-24

AFRL-RY-WP-TR-2017-0169 TRANSIENT ELECTRONICS CATEGORIZATION Dr. Burhan Bayraktaroglu Devices for Sensing Branch Aerospace Components & Subsystems...SUBTITLE TRANSIENT ELECTRONICS CATEGORIZATION 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S) Dr. Burhan...88ABW-2017-3747, Clearance Date 31 July 2017. Paper contains color. 14. ABSTRACT Transient electronics is an emerging technology area that lacks proper

Development of drug resistance mutations in patients on highly active antiretroviral therapy: does competitive advantage drive evolution.

Science.gov (United States)

Kolber, Michael A

2007-01-01

Most physicians that treat individuals with HIV-1 disease are able to successfully suppress viral replication with the pharmacologic armamentarium available today. For the majority of patients this results in immune reconstitution and improved quality of life. However, a large fraction of these patients have transient elevations in their viral burden and even persistence of low-level viremia. In fact, many individuals whose viral load is suppressed to < 50 c/ml have evidence of low-level viral replication. The impact of low-level viremia and persistent viral replication is an area of significant study and interest owing to the potential for the development of drug resistance mutations. Here the fundamental question is whether and perhaps what factors provide a venue for the development of resistant virus. The concern is clearly the eventual progression of disease with the exhaustion of treatment options. The purpose of this review is to evaluate the current literature regarding the effect of low-level viremia on the development of drug resistance mutations. Herein, we discuss the impact of different levels of viral suppression on the development of mutations. In addition, we look at the role that resistance and fitness play in determining the survival of a breakthrough mutation within the background of drug.

Applications of transient annealing to solar cell processing

Energy Technology Data Exchange (ETDEWEB)

Bentini, G.G. (C.N.R. Istituto LAMEL, Bologna (Italy))

1983-01-01

The economical reasons supporting the introduction of transient annealing in solar cell manufacturing are briefly discussed. Such techniques may play an important role, as they are compatible with the request of high throughput, automated processing together with the high quality of the p-n junction which are necessary for large scale economical production of photovoltaic energy. A survey of the applications of the different transient annealing techniques to solar cell processing has been developed by comparing in detail the results obtained up to now the case of solid and liquid phase transient annealing, associated with dry techniques such as Ion Implantation or dopant deposition on the wafer surface. The possibility of using laser pulses for the formation of the p-n junction by incorporation of dopant atoms from a suitable gaseous environment, has also been examined.

Abrasion Resistance of as-Cast High-Chromium Cast Iron

Directory of Open Access Journals (Sweden)

Pokusová Marcela

2014-12-01

Full Text Available High chromium cast irons are widely used as abrasion resistant materials. Their properties and wear resistance depend on carbides and on the nature of the matrix supporting these carbides. The paper presents test results of irons which contain (in wt.% 18-22 Cr and 2-5 C, and is alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve the toughness. Tests showed as-cast irons with mostly austenitic matrix achieved hardness 36-53 HRC but their relative abrasion-resistance was higher than the tool steel STN 19436 heat treated on hardness 60 HRC.

Kapitza thermal resistance studied by high-frequency photothermal radiometry

International Nuclear Information System (INIS)

Horny, Nicolas; Chirtoc, Mihai; Hamaoui, Georges; Fleming, Austin; Ban, Heng

2016-01-01

Kapitza thermal resistance is determined using high-frequency photothermal radiometry (PTR) extended for modulation up to 10 MHz. Interfaces between 50 nm thick titanium coatings and silicon or stainless steel substrates are studied. In the used configuration, the PTR signal is not sensitive to the thermal conductivity of the film nor to its optical absorption coefficient, thus the Kapitza resistance is directly determined from single thermal parameter fits. Results of thermal resistances show the significant influence of the nature of the substrate, as well as of the presence of free electrons at the interface.

Hydrological controls on transient aquifer storage in a karst watershed

Science.gov (United States)

Spellman, P.; Martin, J.; Gulley, J. D.

2017-12-01

While surface storage of floodwaters is well-known to attenuate flood peaks, transient storage of floodwaters in aquifers is a less recognized mechanism of flood peak attenuation. The hydraulic gradient from aquifer to river controls the magnitude of transient aquifer storage and is ultimately a function of aquifer hydraulic conductivity, and effective porosity. Because bedrock and granular aquifers tend to have lower hydraulic conductivities and porosities, their ability to attenuate flood peaks is generally small. In karst aquifers, however, extensive cave systems create high hydraulic conductivities and porosities that create low antecedent hydraulic gradients between aquifers and rivers. Cave springs can reverse flow during high discharges in rivers, temporarily storing floodwaters in the aquifer thus reducing the magnitude of flood discharge downstream. To date however, very few studies have quantified the magnitude or controls of transient aquifer storage in karst watersheds. We therefore investigate controls on transient aquifer storage by using 10 years of river and groundwater data from the Suwannee River Basin, which flows over the karstic upper Floridan aquifer in north-central Florida. We use multiple linear regression to compare the effects of three hydrological controls on the magnitude of transient aquifer storage: antecedent stage, recharge and slope of hydrograph rise. We show the dominant control on transient aquifer storage is antecedent stage, whereby lower stages result in greater magnitudes of transient aquifer storage. Our results suggest that measures of groundwater levels prior to an event can be useful in determining whether transient aquifer storage will occur and may provide a useful metric for improving predictions of flood magnitudes.

Viral Transmission Dynamics at Single-Cell Resolution Reveal Transiently Immune Subpopulations Caused by a Carrier State Association.

Directory of Open Access Journals (Sweden)

William Cenens

2015-12-01

Full Text Available Monitoring the complex transmission dynamics of a bacterial virus (temperate phage P22 throughout a population of its host (Salmonella Typhimurium at single cell resolution revealed the unexpected existence of a transiently immune subpopulation of host cells that emerged from peculiarities preceding the process of lysogenization. More specifically, an infection event ultimately leading to a lysogen first yielded a phage carrier cell harboring a polarly tethered P22 episome. Upon subsequent division, the daughter cell inheriting this episome became lysogenized by an integration event yielding a prophage, while the other daughter cell became P22-free. However, since the phage carrier cell was shown to overproduce immunity factors that are cytoplasmically inherited by the P22-free daughter cell and further passed down to its siblings, a transiently resistant subpopulation was generated that upon dilution of these immunity factors again became susceptible to P22 infection. The iterative emergence and infection of transiently resistant subpopulations suggests a new bet-hedging strategy by which viruses could manage to sustain both vertical and horizontal transmission routes throughout an infected population without compromising a stable co-existence with their host.

Stability and control of resistive wall modes in high beta, low rotation DIII-D plasmas

International Nuclear Information System (INIS)

Garofalo, A.M.; Jackson, G.L.; Haye, R.J. La; Okabayashi, M.; Reimerdes, H.; Strait, E.J.; Ferron, J.R.; Groebner, R.J.; In, Y.; Lanctot, M.J.; Matsunaga, G.; Navratil, G.A.; Solomon, W.M.; Takahashi, H.; Takechi, M.; Turnbull, A.D.

2007-01-01

Recent high-β DIII-D (Luxon J.L. 2002 Nucl. Fusion 42 64) experiments with the new capability of balanced neutral beam injection show that the resistive wall mode (RWM) remains stable when the plasma rotation is lowered to a fraction of a per cent of the Alfven frequency by reducing the injection of angular momentum in discharges with minimized magnetic field errors. Previous DIII-D experiments yielded a high plasma rotation threshold (of order a few per cent of the Alfven frequency) for RWM stabilization when resonant magnetic braking was applied to lower the plasma rotation. We propose that the previously observed rotation threshold can be explained as the entrance into a forbidden band of rotation that results from torque balance including the resonant field amplification by the stable RWM. Resonant braking can also occur naturally in a plasma subject to magnetic instabilities with a zero frequency component, such as edge localized modes. In DIII-D, robust RWM stabilization can be achieved using simultaneous feedback control of the two sets of non-axisymmetric coils. Slow feedback control of the external coils is used for dynamic error field correction; fast feedback control of the internal non-axisymmetric coils provides RWM stabilization during transient periods of low rotation. This method of active control of the n = 1 RWM has opened access to new regimes of high performance in DIII-D. Very high plasma pressure combined with elevated q min for high bootstrap current fraction, and internal transport barriers for high energy confinement, are sustained for almost 2 s, or 10 energy confinement times, suggesting a possible path to high fusion performance, steady-state tokamak scenarios

Solidification structure and abrasion resistance of high chromium white irons

Science.gov (United States)

Doğan, Ö. N.; Hawk, J. A.; Laird, G.

1997-06-01

Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.

Probability based high temperature engineering creep and structural fire resistance

CERN Document Server

Razdolsky, Leo

2017-01-01

This volume on structural fire resistance is for aerospace, structural, and fire prevention engineers; architects, and educators. It bridges the gap between prescriptive- and performance-based methods and simplifies very complex and comprehensive computer analyses to the point that the structural fire resistance and high temperature creep deformations will have a simple, approximate analytical expression that can be used in structural analysis and design. The book emphasizes methods of the theory of engineering creep (stress-strain diagrams) and mathematical operations quite distinct from those of solid mechanics absent high-temperature creep deformations, in particular the classical theory of elasticity and structural engineering. Dr. Razdolsky’s previous books focused on methods of computing the ultimate structural design load to the different fire scenarios. The current work is devoted to the computing of the estimated ultimate resistance of the structure taking into account the effect of high temperatur...

High Velocity Oxidation and Hot Corrosion Resistance of Some ODS Alloys

Science.gov (United States)

Lowell, C. E.; Deadmore, D. L.

1977-01-01

Several oxide dispersion strengthened (ODS) alloys were tested for cyclic, high velocity, oxidation, and hot corrosion resistance. These results were compared to the resistance of an advanced, NiCrAl coated superalloy. An ODS FeCrAl were identified as having sufficient oxidation and hot corrosion resistance to allow potential use in an aircraft gas turbine without coating.

Characteristics of spring wheat genotypes exhibiting high resistance to FHB in terms of their resistance to other fungal diseases

Directory of Open Access Journals (Sweden)

Danuta Kurasiak-Popowska

2016-09-01

Full Text Available The field experiment was carried out in 2010–2012 at the Dłoń Agricultural Research Station, the Poznań University of Life Sciences, Poland. The study was designed to evaluate the degree of infection by powdery mildew, brown rust, and septoria leaf blotch in 61 spring wheat genotypes differing in their resistance to Fusarium ssp. The vast majority of spring wheat genotypes in the collection of gene resources in the USA defined as resistant to Fusarium ssp. confirmed their resistance under Polish climatic conditions. The B .graminis infection rate of genotypes that are considered to be resistant to Fusarium head blight was high. The resistance ranged from 7 for Sumai 3 (PL2 up to 8.8 for Ning 8331 (in a 9-point scale. Most of the genotypes (56.5% were infected by Puccinia recondita at a level of 1–3 (in a 9-point scale. The genotypes of Sumai 3 exhibited high resistance to septoria leaf blotch, amounting to 1–2 in a 9-point scale; the resistance of Frontana ranged from 1 to 3.5, while the genotypes of Ning were infected by Mycosphaerella graminicola at 5–6.

Mechanisms of Evolution in High-Consequence Drug Resistance Plasmids

Directory of Open Access Journals (Sweden)

Susu He

2016-12-01

Full Text Available The dissemination of resistance among bacteria has been facilitated by the fact that resistance genes are usually located on a diverse and evolving set of transmissible plasmids. However, the mechanisms generating diversity and enabling adaptation within highly successful resistance plasmids have remained obscure, despite their profound clinical significance. To understand these mechanisms, we have performed a detailed analysis of the mobilome (the entire mobile genetic element content of a set of previously sequenced carbapenemase-producing Enterobacteriaceae (CPE from the National Institutes of Health Clinical Center. This analysis revealed that plasmid reorganizations occurring in the natural context of colonization of human hosts were overwhelmingly driven by genetic rearrangements carried out by replicative transposons working in concert with the process of homologous recombination. A more complete understanding of the molecular mechanisms and evolutionary forces driving rearrangements in resistance plasmids may lead to fundamentally new strategies to address the problem of antibiotic resistance.

PSH Transient Simulation Modeling

Energy Technology Data Exchange (ETDEWEB)

Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-12-21

PSH Transient Simulation Modeling presentation from the WPTO FY14 - FY16 Peer Review. Transient effects are an important consideration when designing a PSH system, yet numerical techniques for hydraulic transient analysis still need improvements for adjustable-speed (AS) reversible pump-turbine applications.

One-step patterning of double tone high contrast and high refractive index inorganic spin-on resist

Energy Technology Data Exchange (ETDEWEB)

Zanchetta, E.; Della Giustina, G.; Brusatin, G. [Industrial Engineering Department and INSTM, Via Marzolo 9, 35131 Padova (Italy)

2014-09-14

A direct one-step and low temperature micro-fabrication process, enabling to realize large area totally inorganic TiO₂ micro-patterns from a spin-on resist, is presented. High refractive index structures (up to 2 at 632 nm) without the need for transfer processes have been obtained by mask assisted UV lithography, exploiting photocatalytic titania properties. A distinctive feature not shared by any of the known available resists and boosting the material versatility, is that the system behaves either as a positive or as negative tone resist, depending on the process parameters and on the development chemistry. In order to explain the resist double tone behavior, deep comprehension of the lithographic process parameters optimization and of the resist chemistry and structure evolution during the lithographic process, generally uncommon in literature, is reported. Another striking property of the presented resist is that the negative tone shows a high contrast up to 19, allowing to obtain structures resolution down to 2 μm wide. The presented process and material permit to directly fabricate different titania geometries of great importance for solar cells, photo-catalysis, and photonic crystals applications.

RACLETTE: a model for evaluating the thermal response of plasma facing components to slow high power plasma transients. Part I: Theory and description of model capabilities

Science.gov (United States)

Raffray, A. René; Federici, Gianfranco

1997-04-01

RACLETTE (Rate Analysis Code for pLasma Energy Transfer Transient Evaluation), a comprehensive but relatively simple and versatile model, was developed to help in the design analysis of plasma facing components (PFCs) under 'slow' high power transients, such as those associated with plasma vertical displacement events. The model includes all the key surface heat transfer processes such as evaporation, melting, and radiation, and their interaction with the PFC block thermal response and the coolant behaviour. This paper represents part I of two sister and complementary papers. It covers the model description, calibration and validation, and presents a number of parametric analyses shedding light on and identifying trends in the PFC armour block response to high plasma energy deposition transients. Parameters investigated include the plasma energy density and deposition time, the armour thickness and the presence of vapour shielding effects. Part II of the paper focuses on specific design analyses of ITER plasma facing components (divertor, limiter, primary first wall and baffle), including improvements in the thermal-hydraulic modeling required for better understanding the consequences of high energy deposition transients in particular for the ITER limiter case.

RACLETTE: a model for evaluating the thermal response of plasma facing components to slow high power plasma transients. Pt. I. Theory and description of model capabilities

International Nuclear Information System (INIS)

Raffray, A.R.; Federici, G.

1997-01-01

For pt.II see ibid., p.101-30, 1997. RACLETTE (Rate Analysis Code for pLasma Energy Transfer Transient Evaluation), a comprehensive but relatively simple and versatile model, was developed to help in the design analysis of plasma facing components (PFCs) under 'slow' high power transients, such as those associated with plasma vertical displacement events. The model includes all the key surface heat transfer processes such as evaporation, melting, and radiation, and their interaction with the PFC block thermal response and the coolant behaviour. This paper represents part I of two sister and complementary papers. It covers the model description, calibration and validation, and presents a number of parametric analyses shedding light on and identifying trends in the PFC armour block response to high plasma energy deposition transients. Parameters investigated include the plasma energy density and deposition time, the armour thickness and the presence of vapour shielding effects. Part II of the paper focuses on specific design analyses of ITER plasma facing components (divertor, limiter, primary first wall and baffle), including improvements in the thermal-hydraulic modeling required for better understanding the consequences of high energy deposition transients in particular for the ITER limiter case. (orig.)

Diagnostic Evasion of Highly-Resistant Microorganisms: A Critical Factor in Nosocomial Outbreaks.

Science.gov (United States)

Zhou, Xuewei; Friedrich, Alexander W; Bathoorn, Erik

2017-01-01

Highly resistant microorganisms (HRMOs) may evade screening strategies used in routine diagnostics. Bacteria that have evolved to evade diagnostic tests may have a selective advantage in the nosocomial environment. Evasion of resistance detection can result from the following mechanisms: low-level expression of resistance genes not resulting in detectable resistance, slow growing variants, mimicry of wild-type-resistance, and resistance mechanisms that are only detected if induced by antibiotic pressure. We reviewed reports on hospital outbreaks in the Netherlands over the past 5 years. Remarkably, many outbreaks including major nation-wide outbreaks were caused by microorganisms able to evade resistance detection by diagnostic screening tests. We describe various examples of diagnostic evasion by several HRMOs and discuss this in a broad and international perspective. The epidemiology of hospital-associated bacteria may strongly be affected by diagnostic screening strategies. This may result in an increasing reservoir of resistance genes in hospital populations that is unnoticed. The resistance elements may horizontally transfer to hosts with systems for high-level expression, resulting in a clinically significant resistance problem. We advise to communicate the identification of HRMOs that evade diagnostics within national and regional networks. Such signaling networks may prevent inter-hospital outbreaks, and allow collaborative development of adapted diagnostic tests.

Response of steam-water mixtures to pressure transients

International Nuclear Information System (INIS)

Hull, L.M.

1985-01-01

During the transition phase of a hypothetical core-disruptive accident in a liquid-metal fast breeder reactor, melting fuel-steel mixtures may begin to boil, resulting in a two-phase mixture of molten reactor fuel and steel vapor. Dispersal of this mixture by pressure transients may prevent recriticality of the fuel material. This paper describes the results of a series of experiments that investigated the response of two-phase mixtures to pressure transients. Simulant fluids (steam/water) were used in a transparent 10.2-cm-dia, 63.5-cm-long acrylic tube. The pressure transient was provided by releasing pressurized nitrogen from a supply tank. The data obtained are in the form of pressure-time records and high-speed movies. The varied parameters are initial void fraction (10% and 40%) and transient pressure magnitude (3.45 and 310 kPa)

Investigations on heavy ion induced Single-Event Transients (SETs) in highly-scaled FinFETs

Energy Technology Data Exchange (ETDEWEB)

Gaillardin, M., E-mail: marc.gaillardin@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Raine, M.; Paillet, P. [CEA, DAM, DIF, F-91297 Arpajon (France); Adell, P.C. [Jet Propulsion Laboratory, Pasadena, CA 91101 (United States); Girard, S. [Université de Saint-Etienne, Laboratoire H. Curien, UMR-5516, 42000 Saint-Etienne (France); Duhamel, O. [CEA, DAM, DIF, F-91297 Arpajon (France); Andrieu, F.; Barraud, S.; Faynot, O. [CEA, LETI-Minatec, 17 avenue des Martyrs, 38000 Grenoble (France)

2015-12-15

We investigate Single-Event Transients (SET) in different designs of multiple-gate devices made of FinFETs with various geometries. Heavy ion experimental results are explained by using a thorough charge collection analysis of fast transients measured on dedicated test structures. Multi-level simulations are performed to get new insights into the charge collection mechanisms in multiple-gate devices. Implications for multiple-gate device design hardening are finally discussed.

The Transient High Energy Sky and Early Universe Surveyor (THESEUS)

Science.gov (United States)

Amati, Lorenzo; O'Brien, Paul T.; Götz, Diego

2016-07-01

The Transient High Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept under development by a large international collaboration aimed at exploiting gamma-ray bursts for investigating the early Universe. The main scientific objectives of THESEUS include: investigating the star formation rate and metallicity evolution of the ISM and IGM up to redshift 9-10, detecting the first generation (pop III) of stars, studying the sources and physics of re-ionization, detecting the faint end of galaxies luminosity function. These goals will be achieved through a unique combination of instruments allowing GRB detection and arcmin localization over a broad FOV (more than 1sr) and an energy band extending from several MeVs down to 0.3 keV with unprecedented sensitivity, as well as on-board prompt (few minutes) follow-up with a 0.6m class IR telescope with both imaging and spectroscopic capabilities. Such instrumentation will also allow THESEUS to unveil and study the population of soft and sub-energetic GRBs, and, more in general, to perform monitoring and survey of the X-ray sky with unprecedented sensitivity.

High temperature resistive phase transition in A15 high temperature superconductors

International Nuclear Information System (INIS)

Chu, C.W.; Huang, C.Y.; Schmidt, P.H.; Sugawara, K.

1976-01-01

Resistive measurements were made on A15 high temperature superconductors. Anomalies indicative of a phase transition were observed at 433 0 K in a single crystal Nb 3 Sn and at 485 0 K in an unbacked Nb 3 Ge sputtered thin film. Results are compared with the high temperature transmission electron diffraction studies of Nb 3 Ge films by Schmidt et al. A possible instability in the electron energy spectrum is discussed

The annealing of interstitial carbon atoms in high-resistivity n-type silicon after proton irradiation

CERN Document Server

Kuhnke, M; Lindström, G

2002-01-01

The annealing of interstitial carbon C sub i after 7-10 MeV and 23 GeV proton irradiations at room temperature in high-resistivity n-type silicon is investigated. Deep level transient spectroscopy is used to determine the defect parameters. The annealing characteristics of the impurity defects C sub i , C sub i C sub s , C sub i O sub i and VO sub i suggest that the mobile C sub i atoms are also captured at divacancy VV sites at the cluster peripheries and not only at C sub s and O sub i sites in the silicon bulk. The deviation of the electrical filling characteristic of C sub i from the characteristic of a homogeneously distributed defect can be explained by an aggregation of C sub i atoms in the environment of the clusters. The capture rate of electrons into defects located in the cluster environment is reduced due to a positive space charge region surrounding the negatively charged cluster core. The optical filling characteristic of C sub i suggests that the change of the triangle-shaped electric field dis...

High resolution resistivity measurements at the Down Ampney research site

International Nuclear Information System (INIS)

Hallam, J.R.; Jackson, P.D.; Rainsbury, M.; Raines, M.

1991-01-01

A new high resolution resistivity surveying method is described for fault detection and characterisation. The resolution is shown to be significantly higher than conventional apparent resistivity profiling when applied to geological discontinuities such as faults. Nominal fault locations have been determined to an accuracy of 0.5 m, as proven by drilling. Two dimensional profiling and image enhancement of the resulting 2-D data set indicated the possibility of subsidiary fractures and/or lateral changes within the clay to clay' fault zone. The increased resolution allows greater confidence to be placed on both the fault detection and lateral perturbations derived from processed resistance and resistivity images. (Author)

Parallel Evolution of High-Level Aminoglycoside Resistance in Escherichia coli Under Low and High Mutation Supply Rates

Directory of Open Access Journals (Sweden)

Claudia Ibacache-Quiroga

2018-03-01

Full Text Available Antibiotic resistance is a major concern in public health worldwide, thus there is much interest in characterizing the mutational pathways through which susceptible bacteria evolve resistance. Here we use experimental evolution to explore the mutational pathways toward aminoglycoside resistance, using gentamicin as a model, under low and high mutation supply rates. Our results show that both normo and hypermutable strains of Escherichia coli are able to develop resistance to drug dosages > 1,000-fold higher than the minimal inhibitory concentration for their ancestors. Interestingly, such level of resistance was often associated with changes in susceptibility to other antibiotics, most prominently with increased resistance to fosfomycin. Whole-genome sequencing revealed that all resistant derivatives presented diverse mutations in five common genetic elements: fhuA, fusA and the atpIBEFHAGDC, cyoABCDE, and potABCD operons. Despite the large number of mutations acquired, hypermutable strains did not pay, apparently, fitness cost. In contrast to recent studies, we found that the mutation supply rate mainly affected the speed (tempo but not the pattern (mode of evolution: both backgrounds acquired the mutations in the same order, although the hypermutator strain did it faster. This observation is compatible with the adaptive landscape for high-level gentamicin resistance being relatively smooth, with few local maxima; which might be a common feature among antibiotics for which resistance involves multiple loci.

Low- and High-Resistance Exercise: Long-Term Adherence and Motivation among Older Adults.

Science.gov (United States)

Van Roie, Evelien; Bautmans, Ivan; Coudyzer, Walter; Boen, Filip; Delecluse, Christophe

2015-01-01

In terms of motivation and long-term adherence, low-resistance exercise might be more suitable for older adults than high-resistance exercise. However, more data are needed to support this claim. The objective was to investigate the effect of low- and high-resistance exercise protocols on long-term adherence and motivation. This study was designed as an exploratory 24-week follow-up of a randomized 12-week resistance training intervention in older adults. Participants were free to decide whether or not they continued resistance training at their own expense following the intervention. Fifty-six older adults were randomly assigned to HIGH [2 × 10-15 repetitions at 80% of one repetition maximum (1RM)], LOW (1 × 80-100 repetitions at 20% of 1RM), or LOW+ (1 × 60 repetitions at 20% of 1RM + 1 × 10-20 repetitions at 40% 1RM). Motivation, self-efficacy and the perceived barriers for continuing resistance exercise were measured after cessation of each supervised intervention and at follow-up, while long-term adherence was probed retrospectively at follow-up. Participants reported high levels of self-determined motivation before, during, and after the supervised intervention, with no differences between groups (p > 0.05). Nevertheless, only few participants continued strength training after the intervention: 17% in HIGH, 21% in LOW+, and 11% in LOW (p > 0.05). The most commonly reported barriers for continuing resistance exercise were perceived lack of time (46%), being more interested in other physical activities (40%), seasonal reasons (40%), and financial cost (28%). The results suggest no difference in long-term adherence after the end of a supervised exercise intervention at high or low external resistances. Long-term adherence was limited despite high levels of self-determined motivation during the interventions. These findings highlight the importance of further research on developing strategies to overcome barriers of older adults to adhere to resistance

Transient analysis on the SMART-P anticipated transients without scram

International Nuclear Information System (INIS)

Yang, S. H.; Bae, K. H.; Kim, H. C.; Zee, S. Q.

2005-01-01

Anticipated transients without scram (ATWS) are anticipated operational occurrences accompanied by a failure of an automatic reactor trip when required. Although the occurrence probability of the ATWS events is considerably low, these events can result in unacceptable consequences, i.e. the pressurization of the reactor coolant system (RCS) up to an unacceptable range and a core-melting situation. Therefore, the regulatory body requests the installation of a protection system against the ATWS events. According to the request, a diverse protection system (DPS) is installed in the SMART-P (System-integrated Modular Advanced ReacTor-Pilot). This paper presents the results of the transient analysis performed to identify the performance of the SMART-P against the ATWS. In the analysis, the TASS/SMR (Transients And Setpoint Simulation/Small and Medium Reactor) code is applied to identify the thermal hydraulic response of the RCS during the transients

Multidrug efflux pumps at the crossroad between antibiotic resistance and bacterial virulence

Directory of Open Access Journals (Sweden)

Manuel Alcalde-Rico

2016-09-01

Full Text Available Multidrug efflux pumps can be involved in bacterial resistance to antibiotics at different levels. Some efflux pumps are constitutively expressed at low levels and contribute to intrinsic resistance. In addition, their overexpression may allow higher levels of resistance. This overexpression can be transient, in the presence of an effector (phenotypic resistance, or constitutive when mutants in the regulatory elements of the expression of efflux pumps are selected (acquired resistance. Efflux pumps are present in all cells, from human to bacteria and are highly conserved, which indicates that they are ancient elements in the evolution of different organisms. Consequently, it has been suggested that, besides antibiotic resistance, bacterial multidrug efflux pumps would likely contribute to other relevant process of the microbial physiology. In the current article, we discuss some specific examples of the role that efflux pumps may have in the bacterial virulence of animals' and plants' pathogens, including the processes of intercellular communication. Based in these evidences, we propose that efflux pumps are at the crossroad between resistance and virulence of bacterial pathogens. Consequently, the comprehensive study of multidrug efflux pumps requires addressing these functions, which are of relevance for the bacterial-host interactions during infection.

Multidrug Efflux Pumps at the Crossroad between Antibiotic Resistance and Bacterial Virulence.

Science.gov (United States)

Alcalde-Rico, Manuel; Hernando-Amado, Sara; Blanco, Paula; Martínez, José L

2016-01-01

Multidrug efflux pumps can be involved in bacterial resistance to antibiotics at different levels. Some efflux pumps are constitutively expressed at low levels and contribute to intrinsic resistance. In addition, their overexpression may allow higher levels of resistance. This overexpression can be transient, in the presence of an effector (phenotypic resistance), or constitutive when mutants in the regulatory elements of the expression of efflux pumps are selected (acquired resistance). Efflux pumps are present in all cells, from human to bacteria and are highly conserved, which indicates that they are ancient elements in the evolution of different organisms. Consequently, it has been suggested that, besides antibiotic resistance, bacterial multidrug efflux pumps would likely contribute to other relevant processes of the microbial physiology. In the current article, we discuss some specific examples of the role that efflux pumps may have in the bacterial virulence of animals' and plants' pathogens, including the processes of intercellular communication. Based in these evidences, we propose that efflux pumps are at the crossroad between resistance and virulence of bacterial pathogens. Consequently, the comprehensive study of multidrug efflux pumps requires addressing these functions, which are of relevance for the bacterial-host interactions during infection.

Rod-bundle transient-film boiling of high-pressure water in the liquid-deficient regime

International Nuclear Information System (INIS)

Morris, D.G.; Mullins, C.B.; Yoder, G.L.

1982-01-01

Results are reported from a recent experiment investigating dispersed flow film boiling of high pressure water in upflow through a rod bundle. The data, obtained under mildly transient conditions, are used to assess correlations currently used to predict heat transfer in these circumstances. In light of the scarcity of similar data, the data should prove useful in the development and assessment of new heat transfer models. The experiment was conducted at the Oak Ridge National Laboratory in the Thermal-Hydraulic Test Facility, a highly instrumented, non-nuclear, pressurized-water loop containing 64, 3.66-m (12-ft) long rods (of which 60 are electrically heated). The rods are arranged in a square array typical of 17 x 17 fuel rod assemblies in late generation PWRs. Data were collected over typical reactor blowdown parameter ranges

Development of MCP transient operation strategy for the SMART-P

International Nuclear Information System (INIS)

Yoo, S. E.; Choi, B. S.; Kang, H. O.; Yoon, J. H.; Ji, S. K.

2003-01-01

SMART-P MCP(Main Coolant Pump) transient operation strategies are developed. A Modular Modeling System (MMS) computer code is used for the evaluation of the developed operation strategies. In the SMART-P, normal operating modes are classified into MCP high speed(3600 rpm) mode and MCP low speed mode. Also, natural circulation mode is defined as a performance test case. MCP operation transients occur when changing modes from one to another, and system parameters(core power, system pressure, temperature) are having transients. These transients affect on system performance and, in some cases, limit system operation. In this study, MCP operation strategies are developed and obtained acceptable results

Evaluation of prevalence of low and high level mupirocin resistance in methicillin resistant staphylococcus aureus isolates at a tertiary care hospital

International Nuclear Information System (INIS)

Nizamuddin, S.; Irfan, S.; Zafar, A.

2011-01-01

To evaluate the trend of mupirocin resistance in MRSA, isolated at the Clinical Microbiology Laboratory of a tertiary care hospital. Methods: A total of 200 MRSA strains recovered over a 2 year period from various body sites were tested using the 5 and 200 mu g discs of mupirocin to detect its resistance. Results: High level and low level mupirocin resistance were detected in zero and 1 % of MRSA strains, respectively. Resistance to other non beta lactam antibiotics was also high. No MRSA strains were found to be resistant to vancomycin and tegicycline. Conclusion: Mupirocin resistance was found to be very low among local clinical isolates of MRSA. Its judicious use to decolonize nasal carriers should be promoted among hospitalized patients to avoid further transmission and infections due to prevalent endemic MRSA strains in any health care setting. Concomitantly, regular surveillance and effective infection control initiatives are desirable to reduce the incidence of health care associated infections due to MRSA and also of mupirocin resistance. (author)

Near-surface effects of transient oxidation and reduction on Nb-doped SrTiO3 epitaxial thin films

Science.gov (United States)

Chang, C. F.; Chen, Q. Y.; Wadekar, P. V.; Lozano, O.; Wong, M. S.; Hsieh, W. C.; Lin, W. Y.; Ko, H. H.; Lin, Q. J.; Huang, H. C.; Ho, N. J.; Tu, L. W.; Liao, H. H.; Chinta, P. V.; Chu, W. K.; Seo, H. W.

2014-03-01

We studied the effects of transient oxidation and reduction of Nb-doped epitaxial thin films through variations of PAr and PO2. The samples were prepared by co-sputtering of Nb and SrTiO3 on LaAlO3 substrates. The Nb-content were varied from 0-33.7%, as determined by PIXE. Contact resistance, sheet resistance, and optical properties are used to discriminate the effects.

Numerical solution of one-dimensional transient, two-phase flows with temporal fully implicit high order schemes: Subcooled boiling in pipes

Energy Technology Data Exchange (ETDEWEB)

López, R., E-mail: ralope1@ing.uc3m.es; Lecuona, A., E-mail: lecuona@ing.uc3m.es; Nogueira, J., E-mail: goriba@ing.uc3m.es; Vereda, C., E-mail: cvereda@ing.uc3m.es

2017-03-15

Highlights: • A two-phase flows numerical algorithm with high order temporal schemes is proposed. • Transient solutions route depends on the temporal high order scheme employed. • ESDIRK scheme for two-phase flows events exhibits high computational performance. • Computational implementation of the ESDIRK scheme can be done in a very easy manner. - Abstract: An extension for 1-D transient two-phase flows of the SIMPLE-ESDIRK method, initially developed for incompressible viscous flows by Ijaz is presented. This extension is motivated by the high temporal order of accuracy demanded to cope with fast phase change events. This methodology is suitable for boiling heat exchangers, solar thermal receivers, etc. The methodology of the solution consist in a finite volume staggered grid discretization of the governing equations in which the transient terms are treated with the explicit first stage singly diagonally implicit Runge-Kutta (ESDIRK) method. It is suitable for stiff differential equations, present in instant boiling or condensation processes. It is combined with the semi-implicit pressure linked equations algorithm (SIMPLE) for the calculation of the pressure field. The case of study consists of the numerical reproduction of the Bartolomei upward boiling pipe flow experiment. The steady-state validation of the numerical algorithm is made against these experimental results and well known numerical results for that experiment. In addition, a detailed study reveals the benefits over the first order Euler Backward method when applying 3rd and 4th order schemes, making emphasis in the behaviour when the system is subjected to periodic square wave wall heat function disturbances, concluding that the use of the ESDIRK method in two-phase calculations presents remarkable accuracy and computational advantages.

A transient single particle model under FCI conditions

Institute of Scientific and Technical Information of China (English)

LI Xiao-Yan; SHANG Zhi; XU Ji-Jun

2005-01-01

The paper is focused on the coupling effect between film boiling heat transfer and evaporation drag around a hot-particle in cold liquid. Based on the continuity, momentum and energy equations of the vapor film, a transient two-dimensional single particle model has been established. This paper contains a detailed description of HPMC (High-temperature Particle Moving in Coolant) model for studying some aspects of the premixing stage of fuel-coolant interactions (FCIs). The transient process of high-temperature particles moving in coolant can be simulated. Comparisons between the experiment results and the calculations using HPMC model demonstrate that HPMC model achieves a good agreement in predicting the time-varying characteristic of high-temperature spheres moving in coolant.

Tokamaks with high-performance resistive magnets: advanced test reactors and prospects for commercial applications

International Nuclear Information System (INIS)

Bromberg, L.; Cohn, D.R.; Williams, J.E.C.; Becker, H.; Leclaire, R.; Yang, T.

1981-10-01

Scoping studies have been made of tokamak reactors with high performance resistive magnets which maximize advantages gained from high field operation and reduced shielding requirements, and minimize resistive power requirements. High field operation can provide very high values of fusion power density and n tau/sub e/ while the resistive power losses can be kept relatively small. Relatively high values of Q' = Fusion Power/Magnet Resistive Power can be obtained. The use of high field also facilitates operation in the DD-DT advanced fuel mode. The general engineering and operational features of machines with high performance magnets are discussed. Illustrative parameters are given for advanced test reactors and for possible commercial reactors. Commercial applications that are discussed are the production of fissile fuel, electricity generation with and without fissioning blankets and synthetic fuel production

High levels of macrolide-resistant Mycoplasma genitalium in Queensland, Australia.

Science.gov (United States)

Trembizki, Ella; Buckley, Cameron; Bletchly, Cheryl; Nimmo, Graeme R; Whiley, David M

2017-10-01

The macrolide azithromycin is recommended for treatment of Mycoplasma genitalium infection; however, M. genitalium strains possessing macrolide resistance-mediating mutations (MRMMs) are increasingly being reported. Here, we used the SpeeDx ResistancePlus MG kit, which provides simultaneous detection of M. genitalium and MRMMs, to assess MRMM carriage among M. genitalium infections in Queensland, Australia. Performance characteristics of the ResistancePlus MG kit for M. genitalium detection were compared to in-house PCR. Available M. genitalium PCR-positive (n=67) and negative (n=281) samples from the years 2011 to 2017 were tested using the SpeeDx ResistancePlus MG kit. In total, 63.6 % M. genitalium-positive samples were indicated to harbour MRMMs. The ResistancePlus MG method provided sensitivity and specificity of 97 and 99.6 % respectively compared to in-house PCR for M. genitalium detection. Such high levels of macrolide-resistant M. genitalium raise further concerns over future use of azithromycin for treatment of M. genitalium infection.

Development of transgenic finger millet (Eleusine coracana (L.) Gaertn.) resistant to leaf blast disease.

Science.gov (United States)

Ignacimuthu, S; Ceasar, S Antony

2012-03-01

Finger millet plants conferring resistance to leaf blast disease have been developed by inserting a rice chitinase (chi11) gene through Agrobacterium-mediated transformation. Plasmid pHyg-Chi.11 harbouring the rice chitinase gene under the control of maize ubiquitin promoter was introduced into finger millet using Agrobacterium strain LBA4404 (pSB1). Transformed plants were selected and regenerated on hygromycin-supplemented medium. Transient expression of transgene was confirmed by GUS histochemical staining. The incorporation of rice chitinase gene in R0 and R1 progenies was confirmed by PCR and Southern blot analyses. Expression of chitinase gene in finger millet was confirmed by Western blot analysis with a barley chitinase antibody. A leaf blast assay was also performed by challenging the transgenic plants with spores of Pyricularia grisea. The frequency of transient expression was 16.3% to 19.3%. Stable frequency was 3.5% to 3.9%. Southern blot analysis confirmed the integration of 3.1 kb chitinase gene. Western blot analysis detected the presence of 35 kDa chitinase enzyme. Chitinase activity ranged from 19.4 to 24.8. In segregation analysis, the transgenic R1 lines produced three resistant and one sensitive for hygromycin, confirming the normal Mendelian pattern of transgene segregation. Transgenic plants showed high level of resistance to leaf blast disease compared to control plants. This is the first study reporting the introduction of rice chitinase gene into finger millet for leaf blast resistance.

Radiation-induced frequency transients in AT, BT, and SC cut quartz resonators

International Nuclear Information System (INIS)

Koehler, D.R.

1979-01-01

Earlier studies of transient frequency changes in high-purity swept AT quartz resonators led to the conclusion that impurity-induced effects were small, while the observed changes were qualitatively and quantitatively well characterized in terms of the time changing temperature of the vibrating quartz and its effect on frequency. 5 MHz, AT cut fifth overtone, and BT and SC cut third overtone resonators were prepared from a single stone of Sawyer swept Premium-Q quartz. The resonators were operated in precision ovenized oscillators at or near their turnover temperatures. Pulsed irradiation, at dose levels of the order of 10 4 rads (Si) per pulse, was accomplished at Sandia. The experimental data display negative frequency transients for the AT cut resonators, positive frequency transients for the BT cut resonators, and very small transient effects for the SC cut resonators. From these experimental results, it is concluded that no measurable impurity-induced frequency changes are observed in this high-purity swept-quartz and that the frequency transients are accurately modelled in terms of transient temperature effects stemming from the thermal characteristics of the resonator structure

Directly patternable high refractive index ferroelectric sol–gel resist

Energy Technology Data Exchange (ETDEWEB)

Garoli, D., E-mail: denis.garoli@iit.it [Istituto Italiano di Tecnologia, Via Morego 16, 16136 Genova (Italy); Della Giustina, G. [Industrial Engineering Department, University of Padova and INSTM, Via Marzolo 9, 35131 Padova (Italy)

2015-08-15

The development of a ferroelectric negative tone sol–gel resist for Ultraviolet (UV) and Electron Beam (EB) lithography is presented. A new system based on Lead Zirconate Titanate (PZT, with formula PbZr{sub 0.52}Ti{sub 0.48}O{sub 3}) was synthesized by sol–gel method. The lithographic performances were investigated and several structures spanning from the micron range down to less than 50 nm have been achieved by UV and EB lithography. The system interaction with UV light and Electron beam was thoroughly characterized by FT-IT spectroscopy. The exposed PZT was annealed at high temperatures in order to study the crystalline phase evolution, the optical constants values and stability of patterned structures. After exposure and annealing, the refractive index of the material can vary from 1.68 up to 2.33 (@400 nm), while the ferroelectric behaviour seems to be maintained after high temperature annealing. These results suggest a possible application of PZT resist not only as ferroelectric but also as nanopatternable high refractive index material. Moreover, direct nanopatterning by means of Focused Ion Beam (FIB) lithography was verified and the potentiality for the preparation of high aspect ratio hollow nanostructures will be presented. - Highlights: • A new formula directly patternable PZT high refractive index resist is presented. • The gel is sensitive to both UV and electron beam exposure. • The refractive index can vary from 1.68 up to 2.33 (@400 nm). • Direct nanopatterning by means of Focused Ion Beam (FIB) lithography was verified. • High aspect ratio hollow nanostructures will be presented.

Transient flow combustion

Science.gov (United States)

Tacina, R. R.

1984-01-01

Non-steady combustion problems can result from engine sources such as accelerations, decelerations, nozzle adjustments, augmentor ignition, and air perturbations into and out of the compressor. Also non-steady combustion can be generated internally from combustion instability or self-induced oscillations. A premixed-prevaporized combustor would be particularly sensitive to flow transients because of its susceptability to flashback-autoignition and blowout. An experimental program, the Transient Flow Combustion Study is in progress to study the effects of air and fuel flow transients on a premixed-prevaporized combustor. Preliminary tests performed at an inlet air temperature of 600 K, a reference velocity of 30 m/s, and a pressure of 700 kPa. The airflow was reduced to 1/3 of its original value in a 40 ms ramp before flashback occurred. Ramping the airflow up has shown that blowout is more sensitive than flashback to flow transients. Blowout occurred with a 25 percent increase in airflow (at a constant fuel-air ratio) in a 20 ms ramp. Combustion resonance was found at some conditions and may be important in determining the effects of flow transients.

FIRST RESULTS FROM THE CATALINA REAL-TIME TRANSIENT SURVEY

International Nuclear Information System (INIS)

Drake, A. J.; Djorgovski, S. G.; Mahabal, A.; Graham, M. J.; Williams, R.; Beshore, E.; Larson, S.; Boattini, A.; Gibbs, A.; Hill, R.; Kowalski, R.; Christensen, E.; Catelan, M.

2009-01-01

We report on the results from the first six months of the Catalina Real-Time Transient Survey (CRTS). In order to search for optical transients (OTs) with timescales of minutes to years, the CRTS analyses data from the Catalina Sky Survey which repeatedly covers 26,000 of square degrees on the sky. The CRTS provides a public stream of transients that are bright enough to be followed up using small telescopes. Since the beginning of the survey, all CRTS transients have been made available to astronomers around the world in real time using HTML tables,RSS feeds, and VOEvents. As part of our public outreach program, the detections are now also available in Keyhole Markup Language through Google Sky. The initial discoveries include over 350 unique OTs rising more than 2 mag from past measurements. Sixty two of these are classified as supernovae (SNe), based on light curves, prior deep imaging and spectroscopic data. Seventy seven are due to cataclysmic variables (CVs; only 13 previously known), while an additional 100 transients were too infrequently sampled to distinguish between faint CVs and SNe. The remaining OTs include active galactic nucleus, blazars, high-proper-motions stars, highly variable stars (such as UV Ceti stars), and transients of an unknown nature. Our results suggest that there is a large population of SNe missed by many current SN surveys because of selection biases. These objects appear to be associated with faint host galaxies. We also discuss the unexpected discovery of white dwarf binary systems through dramatic eclipses.

Exploring transient X-ray sky with Einstein Probe

Science.gov (United States)

Yuan, W.; Zhang, C.; Ling, Z.; Zhao, D.; Chen, Y.; Lu, F.; Zhang, S.

2017-10-01

The Einstein Probe is a small satellite in time-domain astronomy to monitor the soft X-ray sky. It is a small mission in the space science programme of the Chinese Academy of Sciences. It will carry out systematic survey and characterisation of high-energy transients at unprecedented sensitivity, spatial resolution, Grasp and monitoring cadence. Its wide-field imaging capability is achieved by using established technology of micro-pore lobster-eye X-ray focusing optics. Complementary to this is X-ray follow-up capability enabled by a narrow-field X-ray telescope. It is capable of on-board triggering and real time downlink of transient alerts, in order to trigger fast follow-up observations at multi-wavelengths. Its scientific goals are concerned with discovering and characterising diverse types of X-ray transients, including tidal disruption events, supernova shock breakouts, high-redshift GRBs, and of particular interest, X-ray counterparts of gravitational wave events.

Limited recovery of soil microbial activity after transient exposure to gasoline vapors

DEFF Research Database (Denmark)

Modrzyński, Jakub J.; Christensen, Jan H.; Mayer, Philipp

2016-01-01

During gasoline spills complex mixtures of toxic volatile organic compounds (VOCs) are released to terrestrial environments. Gasoline VOCs exert baseline toxicity (narcosis) and may thus broadly affect soil biota. We assessed the functional resilience (i.e. resistance and recovery of microbial...... functions) in soil microbial communities transiently exposed to gasoline vapors by passive dosing via headspace for 40 days followed by a recovery phase of 84 days. Chemical exposure was characterized with GC-MS, whereas microbial activity was monitored as soil respiration (CO2 release) and soil bacterial...... microbial activity indicating residual soil toxicity, which could not be attributed to BTEX, but rather to mixture toxicity of more persistent gasoline constituents or degradation products. Our results indicate a limited potential for functional recovery of soil microbial communities after transient...

Effects of spinach nitrate on insulin resistance, endothelial dysfunction markers and inflammation in mice with high-fat and high-fructose consumption

Directory of Open Access Journals (Sweden)

Ting Li

2016-09-01

Full Text Available Background: Insulin resistance, which is associated with an increased risk of cardiovascular morbidity and mortality, has become a leading nutrition problem. Inorganic nitrate enriched in spinach has been demonstrated to reverse the pathological features of insulin resistance and endothelial dysfunction. However, the effects of a direct intake of nitrate-enriched spinach on insulin resistance and endothelial dysfunction have not been studied. Objective: To investigate the effects of spinach nitrate on insulin resistance, lipid metabolism, endothelial function, and inflammation in mice fed with a high-fat and high-fructose diet. Design: A diet intervention of spinach with or without nitrate was performed in mice. A high-fat and high-fructose diet was used to cause insulin resistance, endothelial dysfunction, and inflammation in mice. The impacts of spinach nitrate on lipid profile, insulin resistance, markers of endothelial function, and inflammation were determined in mice. Results: Spinach nitrate improved the vascular endothelial function of the mice with high-fat and high-fructose consumption, as evidenced by the elevated plasma nitrite level, increased serum nitric oxide (NO level and decreased serum ET-1 level after spinach nitrate intervention. Spinach nitrate also reduced serum triglycerides, total cholesterol, and low-density lipoprotein-cholesterol levels and elevated serum high-density lipoprotein-cholesterol levels in the mice fed with a high-fat and high-fructose diet. Mice receiving spinach with 60 mg/kg of nitrate (1.02±0.34 showed a significantly low homeostasis model assessment-insulin resistance index as compared with the model mice (2.05±0.58, which is indicating that spinach nitrate could effectively improve the insulin resistance. In addition, spinach nitrate remarkably decreased the elevated serum C-reactive protein, tumor necrosis factor α, and interleukin-6 levels induced by a high-fat and high-fructose diet

The effect of high-pressure devitrification and densification on ballistic-penetration resistance of fused silica

Science.gov (United States)

Avuthu, Vasudeva Reddy

perhaps alpha-quartz) within fused silica during ballistic impact. To rationalize the findings obtained, the all-atom molecular-level computational analysis is complemented by a series of quantum-mechanics density functional theory (DFT) computations. The latter computations enable determination of the relative potential energies of the fused silica, alpha-quartz and stishovite under ambient pressure (i.e. under their natural densities) as well as under imposed (as high as 50 GPa) pressures (i.e. under higher densities) and shear strains. In addition, the transition states associated with various fused-silica devitrification processes were identified. In the second part of the present work, the molecular-level computational results obtained in the first portion of the work are used to enrich a continuum-type constitutive model (that is, the so-called Johnson-Holmquist-2, JH2, model) for fused silica. Since the aforementioned devitrification and permanent-densification processes modify the response of fused silica to the pressure as well as to the deviatoric part of the stress, changes had to be made in both the JH2 equation of state and the strength model. To assess the potential improvements with respect to the ballistic-penetration resistance of this material brought about by the fused-silica devitrification and permanent-densification processes, a series of transient non-linear dynamics finite element analyses of the transverse impact of a fused-silica test plate with a solid right-circular cylindrical steel projectile was conducted. The results obtained revealed that, provided the projectile incident velocity and, hence, the attendant pressure, is sufficiently high, fused silica can undergo impact-induced energy-consuming devitrification, which improves its ballistic-penetration resistance.

Consumption of a liquid high-fat meal increases triglycerides but decreases high-density lipoprotein cholesterol in abdominally obese subjects with high postprandial insulin resistance.

Science.gov (United States)

Wang, Feng; Lu, Huixia; Liu, Fukang; Cai, Huizhen; Xia, Hui; Guo, Fei; Xie, Yulan; Huang, Guiling; Miao, Miao; Shu, Guofang; Sun, Guiju

2017-07-01

Abdominal obesity is associated with an increased risk of insulin resistance, which may be a potential contributor to dyslipidemia. However, the relationship between postprandial insulin resistance and lipid metabolism in abdominally obese subjects remains unknown. We hypothesized that postprandial dyslipidemia would be exaggerated in abdominally obese subjects with high postprandial insulin resistance. To test this hypothesis, serum glucose, insulin, triglycerides, total cholesterol, high-density lipoprotein cholesterol, and apolipoprotein B were measured at baseline and postprandial state at 0.5, 1, 2, 4, 6, and 8 hours after a liquid high-fat meal in non-abdominally obese controls (n=44) and abdominally obese subjects with low (AO-LPIR, n=40), middle (n=40), and high postprandial insulin resistance (AO-HPIR, n=40) based on the tertiles ratio of the insulin to glucose areas under the curve (AUC). Their serum adipokines were tested at baseline only. Fasting serum leptin was higher (Pinsulin resistance and controls. The present study indicated that the higher degree of postprandial insulin resistance, the more adverse lipid profiles in abdominally obese subjects, which provides insight into opportunity for screening in health. Copyright © 2017 Elsevier Inc. All rights reserved.

The Internal Resistance of Supercapacitors

Science.gov (United States)

Costa, G. G. G.; Pietronero, R. C.; Catunda, T.

2012-01-01

In this paper we study the transient behaviour of RC circuits with supercapacitors, varying R between 1 and 100 [omega]. We demonstrate that supercapacitors behave as ideal capacitors in series with an internal resistance (r [similar to] 8 [omega] for C = 0.2 F, 5.5 V). This result is important to optimize the demonstration of RC circuits using a…

Pius, self-protective thermohydraulics transient without safety system intervention

International Nuclear Information System (INIS)

Fredell, J.; Bredolt, V.

1989-01-01

In this paper, the self-protective thermohydraulic feedback of the PIUS reactor system is illustrated by an in-depth discussion of one typical transient. The selected transient is an undetected total loss of feedwater in the complete absence of conventional safety system intervention. The reactor shuts itself down to residual power in two steps. First, the power decreases due to the strongly negative moderator temperature reactivity coefficient, and then a complete shutdown occurs by ingress of cold, highly borated water from the reactor pool. The transient is terminated without any harm to the fuel or paint systems

Effect of some structural parameters on high-temperature crack resistance of tungsten

International Nuclear Information System (INIS)

Babak, A.V.; Uskov, E.I.

1984-01-01

The paper presents results of physicomechanical studied in high-temperature crack resistance of tungsten produced by powder metallurgy methods. It is shown that at high temperatures (>2000 deg C) a structure is formed in the material and fails at stresses independent of temperature. It is found that high-temperature tungsten crack resistance is affected neighter by changes in the effictive grain size, nor by appearance of grain-boundary microcraks in the material under high-temperature action

Improving UV Resistance of High Performance Fibers

Science.gov (United States)

Hassanin, Ahmed

High performance fibers are characterized by their superior properties compared to the traditional textile fibers. High strength fibers have high modules, high strength to weight ratio, high chemical resistance, and usually high temperature resistance. It is used in application where superior properties are needed such as bulletproof vests, ropes and cables, cut resistant products, load tendons for giant scientific balloons, fishing rods, tennis racket strings, parachute cords, adhesives and sealants, protective apparel and tire cords. Unfortunately, Ultraviolet (UV) radiation causes serious degradation to the most of high performance fibers. UV lights, either natural or artificial, cause organic compounds to decompose and degrade, because the energy of the photons of UV light is high enough to break chemical bonds causing chain scission. This work is aiming at achieving maximum protection of high performance fibers using sheathing approaches. The sheaths proposed are of lightweight to maintain the advantage of the high performance fiber that is the high strength to weight ratio. This study involves developing three different types of sheathing. The product of interest that need be protected from UV is braid from PBO. First approach is extruding a sheath from Low Density Polyethylene (LDPE) loaded with different rutile TiO2 % nanoparticles around the braid from the PBO. The results of this approach showed that LDPE sheath loaded with 10% TiO2 by weight achieved the highest protection compare to 0% and 5% TiO2. The protection here is judged by strength loss of PBO. This trend noticed in different weathering environments, where the sheathed samples were exposed to UV-VIS radiations in different weatheromter equipments as well as exposure to high altitude environment using NASA BRDL balloon. The second approach is focusing in developing a protective porous membrane from polyurethane loaded with rutile TiO2 nanoparticles. Membrane from polyurethane loaded with 4

Transient Tolerant Automated Control System for the LEDA 75kV Injector

International Nuclear Information System (INIS)

Thuot, M.E.; Dalesio, L.R.; Harrington, M.; Hodgkins, D.; Kerstiens, D.M.; Stettler, M.W.; Warren, D.S.; Zaugg, T.; Arvin, A.; Bolt, S.; Richards, M.

1999-01-01

The Low-Energy Demonstration Accelerator (LEDA) injector is designed to inject 75-keV, 110-mA, proton beams into the LEDA RFQ. The injector operation has been automated to provide long term, high availability operation using the Experimental Physics and Industrial Control System (EPICS). Automated recovery from spark-downs demands reliable spark detection and sequence execution by the injector controller. Reliable computer control in the high-energy transient environment required transient suppression and isolation of hundreds of analog and binary data lines connecting the EPICS computer controller to the injector and it's power supplies and diagnostics. A transient suppression design based on measured and modeled spark transient parameters provides robust injector operation. This paper describes the control system hardware and software design, implementation and operational performance

Pressure transients analysis of a high-temperature gas-cooled reactor with direct helium turbine cycle

Energy Technology Data Exchange (ETDEWEB)

Dang, M.; Dupont, J. F.; Jacquemoud, P.; Mylonas, R. [Eidgenoessisches Inst. fuer Reaktorforschung, Wuerenlingen (Switzerland)

1981-01-15

The direct coupling of a gas cooled reactor with a closed gas turbine cycle leads to a specific dynamic plant behaviour, which may be summarized as follows: a) any operational transient involving a variation of the core mass flow rate causes a variation of the pressure ratio of the turbomachines and leads unavoidably to pressure and temperature transients in the gas turbine cycle; and b) very severe pressure equalization transients initiated by unlikely events such as the deblading of one or more turbomachines must be taken into account. This behaviour is described and illustrated through results gained from computer analyses performed at the Swiss Federal Institute for Reactor Research (EIR) in Wurenlingen within the scope of the Swiss-German HHT project.

Study on the high temperature crack resistance of tungsten

International Nuclear Information System (INIS)

Uskov, E.I.; Babak, A.V.

1983-01-01

The possibility of a multiple use of tungsten specimens in crack resistance tests in the temperature range of 600-2000 deg C is studied. It is established experimentally that the minimum length of growth of a main crack is 1x10 -4 m for the most effective repeated use of specimens. A flow diagram of mechanical tests is suggested for investigating high temperature tungsten crack resistance and estimating the degree of weakening the grain-boundary bond

Reduced-order modellin for high-pressure transient flow of hydrogen-natural gas mixture

Science.gov (United States)

Agaie, Baba G.; Khan, Ilyas; Alshomrani, Ali Saleh; Alqahtani, Aisha M.

2017-05-01

In this paper the transient flow of hydrogen compressed-natural gas (HCNG) mixture which is also referred to as hydrogen-natural gas mixture in a pipeline is numerically computed using the reduced-order modelling technique. The study on transient conditions is important because the pipeline flows are normally in the unsteady state due to the sudden opening and closure of control valves, but most of the existing studies only analyse the flow in the steady-state conditions. The mathematical model consists in a set of non-linear conservation forms of partial differential equations. The objective of this paper is to improve the accuracy in the prediction of the HCNG transient flow parameters using the Reduced-Order Modelling (ROM). The ROM technique has been successfully used in single-gas and aerodynamic flow problems, the gas mixture has not been done using the ROM. The study is based on the velocity change created by the operation of the valves upstream and downstream the pipeline. Results on the flow characteristics, namely the pressure, density, celerity and mass flux are based on variations of the mixing ratio and valve reaction and actuation time; the ROM computational time cost advantage are also presented.

Plant analyzer development for high-speed interactive simulation of BWR plant transients

International Nuclear Information System (INIS)

Wulff, W.; Cheng, H.S.; Mallen, A.N.

1986-01-01

Advanced modeling techniques have been combined with modern, special-purpose peripheral minicomputer technology to develop a plant analyzer which provides realistic and accurate predictions of plant transients and severe off-normal events in nuclear power plants through on-line simulations at speeds of approximately 10 times faster than actual process speeds. The new simulation technology serves not only for carrying out routinely and efficiently safety analyses, optimizations of emergency procedures and design changes, parametric studies for obtaining safety margins and for generic training but also for assisting plant operations. Five modeling principles are presented which serve to achieve high-speed simulation of neutron kinetics, thermal conduction, nonhomogeneous and nonequilibrium two-phase flow coolant dynamics, steam line acoustical effects, and the dynamics of the balance of plant and containment systems, control systems and plant protection systems. 21 refs

Method for making low-resistivity contacts to high T/sub c/ superconductors

International Nuclear Information System (INIS)

Ekin, J.W.; Panson, A.J.; Blankenship, B.A.

1988-01-01

A method for making low-resistivity contacts to high T/sub c/ superconductors has been developed, which has achieved contact surface resistivities less than 10 μΩ cm 2 at 76 K and does not require sample heating above ∼150 0 C. This is an upper limit for the contact resistivity obtained at high current densities up to 10 2 --10 3 A/cm 2 across the contact interface. At lower measuring current densities the contact resistivities were lower and the voltage-current curve was nonlinear, having a superconducting transition character. On cooling from 295 to 76 K, the contact resistivity decreased several times, in contrast to indium solder contacts where the resistivity increased on cooling. The contacts showed consistently low resistivity and little degradation when exposed to dry air over a four-month period and when repeatedly cycled between room temperature and 76 K. The contacts are formed by sputter depositing a layer of a noble metal-silver and gold were used-on a clean superconductor surface to protect the surface and serve as a contact pad. External connections to the contact pads have been made using both solder and wire-bonding techniques

Analysis of the transient compressible vapor flow in heat pipes

Science.gov (United States)

Jang, J. H.; Faghri, A.; Chang, W. S.

1989-01-01

The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual vapor flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted. The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures.

Analysis of the transient compressible vapor flow in heat pipe

International Nuclear Information System (INIS)

Jang, J.H.; Faghri, A.; Chang, W.S.

1989-07-01

The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual vapor flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted. The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures

Analysis of the transient compressible vapor flow in heat pipe

Science.gov (United States)

Jang, Jong Hoon; Faghri, Amir; Chang, Won Soon

1989-01-01

The transient compressible one-dimensional vapor flow dynamics in a heat pipe is modeled. The numerical results are obtained by using the implicit non-iterative Beam-Warming finite difference method. The model is tested for simulated heat pipe vapor flow and actual flow in cylindrical heat pipes. A good comparison of the present transient results for the simulated heat pipe vapor flow with the previous results of a two-dimensional numerical model is achieved and the steady state results are in agreement with the existing experimental data. The transient behavior of the vapor flow under subsonic, sonic, and supersonic speeds and high mass flow rates are successfully predicted. The one-dimensional model also describes the vapor flow dynamics in cylindrical heat pipes at high temperatures.

Transient Diagnosis and Prognosis for Secondary System in Nuclear Power Plants

Directory of Open Access Journals (Sweden)

Sangjun Park

2016-10-01

Full Text Available This paper introduces the development of a transient monitoring system to detect the early stage of a transient, to identify the type of the transient scenario, and to inform an operator with the remaining time to turbine trip when there is no operator's relevant control. This study focused on the transients originating from a secondary system in nuclear power plants (NPPs, because the secondary system was recognized to be a more dominant factor to make unplanned turbine-generator trips which can ultimately result in reactor trips. In order to make the proposed methodology practical forward, all the transient scenarios registered in a simulator of a 1,000 MWe pressurized water reactor were archived in the transient pattern database. The transient patterns show plant behavior until turbine-generator trip when there is no operator's intervention. Meanwhile, the operating data periodically captured from a plant computer is compared with an individual transient pattern in the database and a highly matched section among the transient patterns enables isolation of the type of transient and prediction of the expected remaining time to trip. The transient pattern database consists of hundreds of variables, so it is difficult to speedily compare patterns and to draw a conclusion in a timely manner. The transient pattern database and the operating data are, therefore, converted into a smaller dimension using the principal component analysis (PCA. This paper describes the process of constructing the transient pattern database, dealing with principal components, and optimizing similarity measures.

Static converters power supply: transient regimes; Alimentation par convertisseurs statiques: regimes transitoires

Energy Technology Data Exchange (ETDEWEB)

Pasqualini, G. [Ecole Superieure d`Electricite (France)

1997-08-01

Direct current motors, asynchronous and variable speed synchronous motors are generally supplied with static converters. Speed variation is obtained by voltage variation in DC motors and by frequency variation in AC motors. In these conditions, these motors are running continuously in transient regimes: the DC motors current is not direct and the AC motors current is not sinusoidal. This situation leads to pulsing couples in the shaft line and to an increase of Joule effect losses. The aim of this paper is to present the methods of study of the electric motors functioning using the shape of the power voltages given by converters and mathematical models of these machines. The synchronous machines are rapidly described while the asynchronous machines are studied using Ku`s transformation instead of Park`s transformation for simplification. For each type of machine, calculation methods allow to determine their current, additional losses and couple characteristics. The transient regimes considered are those remaining when the motor is running at a constant speed and defined regime (supply voltages are periodical functions of time). These transient regimes are identically reproducing with a frequency which is a multiple of the converters supply frequency. Transient regimes due to functioning changes of the motor, such as resisting couple or power supply frequency variations, are not considered in this study. (J.S.) 9 refs.

Incidence of high-level evernimicin resistance in Enterococcus faecium among food animals and humans

DEFF Research Database (Denmark)

Aarestrup, Frank Møller; McNicholas, P. M.

2002-01-01

Six high-level evernimicin-resistant Enterococcus faecium isolates were identified among 304 avilarnycin-resistant E. faecium isolates from animals and 404 stool samples from humans with diarrhea. All four animal isolates, and one of the human isolates, were able to transfer resistance...... to a susceptible E. faecium strain. The resulting transconjugants all tested positive for the presence of emtA, a gene encoding a methyltransferase previously linked with high-level evernimicin resistance. The four transconjugants derived from animal isolates all carried the same plasmid, while a differently sized...... plasmid was found in the isolate from humans. This study demonstrated a low incidence of high-level evernimicin resistance mediated by the emtA gene in different E. faecium isolates of animal and human origin....

Transient particle emission measurement with optical techniques

Science.gov (United States)

Bermúdez, Vicente; Luján, José M.; Serrano, José R.; Pla, Benjamín

2008-06-01

Particulate matter is responsible for some respiratory and cardiovascular diseases. In addition, it is one of the most important pollutants of high-speed direct injection (HSDI) passenger car engines. Current legislation requires particulate dilution tunnels for particulate matter measuring. However for development work, dilution tunnels are expensive and sometimes not useful since they are not able to quantify real-time particulate emissions during transient operation. In this study, the use of a continuous measurement opacimeter and a fast response HFID is proven to be a good alternative to obtain instantaneous particle mass emissions during transient operation (due to particulate matter consisting mainly of soot and SOF). Some methods and correlations available from literature, but developed for steady conditions, are evaluated during transient operation by comparing with mini-tunnel measurements during the entire MVEG-A transient cycle. A new correlation was also derived from this evaluation. Results for soot and SOF (obtained from the new correlation proposed) are compared with soot and SOF captured with particulate filters, which have been separated by means of an SOF extraction method. Finally, as an example of ECU design strategies using these sort of correlations, the EGR valve opening is optimized during transient operation. The optimization is performed while simultaneously taking into account instantaneous fuel consumption, particulate emissions (calculated with the proposed correlation) and other regulated engine pollutants.

Resistive internal kink modes in a tokamak with high-pressure plasma

International Nuclear Information System (INIS)

Kuvshinov, B.N.; Mikhajlovskij, A.B.; Tatarinov, E.G.

1988-01-01

Theory of resistive internal kink modes in a tokamak with high-pressure plasma is developed. Equation for Fourie-image of disturbed displacment in a resistive layer ie derived with regard to effects of the fourth order by plasma pressure within the framework of single-liquid approach. In its structure this equation coincides with a similar equation for resistive balloon modes and has an exact solution expressed by degenerated hypergeometric function. A general dispersion equation for resistive kink modes is derived with regard to the effects indicated. It is shown that plasma pressure finiteness leads to the reduction of reconnection and tyring-mode increments

Predictive Studies Suggest that the Risk for the Selection of Antibiotic Resistance by Biocides Is Likely Low in Stenotrophomonas maltophilia.

Directory of Open Access Journals (Sweden)

María Blanca Sánchez

Full Text Available Biocides are used without restriction for several purposes. As a consequence, large amounts of biocides are released without any control in the environment, a situation that can challenge the microbial population dynamics, including selection of antibiotic resistant bacteria. Previous work has shown that triclosan selects Stenotrophomonas maltophilia antibiotic resistant mutants overexpressing the efflux pump SmeDEF and induces expression of this pump triggering transient low-level resistance. In the present work we analyze if two other common biocides, benzalkonium chloride and hexachlorophene, trigger antibiotic resistance in S. maltophilia. Bioinformatic and biochemical methods showed that benzalkonium chloride and hexachlorophene bind the repressor of smeDEF, SmeT. Only benzalkonium chloride triggers expression of smeD and its effect in transient antibiotic resistance is minor. None of the hexachlorophene-selected mutants was antibiotic resistant. Two benzalkonium chloride resistant mutants presented reduced susceptibility to antibiotics and were impaired in growth. Metabolic profiling showed they were more proficient than their parental strain in the use of some dipeptides. We can then conclude that although bioinformatic predictions and biochemical studies suggest that both hexachlorophene and benzalkonium chloride should induce smeDEF expression leading to transient S. maltophilia resistance to antibiotics, phenotypic assays showed this not to be true. The facts that hexachlorophene resistant mutants are not antibiotic resistant and that the benzalkonium chloride resistant mutants presenting altered susceptibility to antibiotics were impaired in growth suggests that the risk for the selection (and fixation of S. maltophilia antibiotic resistant mutants by these biocides is likely low, at least in the absence of constant selection pressure.

Rugged Low-Resistance Contacts To High-Tc Superconductors

Science.gov (United States)

Caton, Randall; Selim, Raouf; Byvik, Charles E.; Buoncristiani, A. Martin

1992-01-01

Newly developed technique involving use of gold makes possible to fabricate low-resistance contacts with rugged connections to high-Tc superconductors. Gold diffused into specimen of superconducting material by melting gold beads onto surface of specimen, making strong mechanical contacts. Shear strength of gold bead contacts greater than epoxy or silver paste. Practical use in high-current-carrying applications of new high-Tc materials, including superconducting magnets, long-wavelength sensors, electrical ground planes at low temperatures, and efficient transmission of power.

Design, Construction, and Validation of Artificial MicroRNA Vectors Using Agrobacterium-Mediated Transient Expression System.

Science.gov (United States)

Bhagwat, Basdeo; Chi, Ming; Han, Dianwei; Tang, Haifeng; Tang, Guiliang; Xiang, Yu

2016-01-01

Artificial microRNA (amiRNA) technology utilizes microRNA (miRNA) biogenesis pathway to produce artificially selected small RNAs using miRNA gene backbone. It provides a feasible strategy for inducing loss of gene function, and has been applied in functional genomics study, improvement of crop quality and plant virus disease resistance. A big challenge in amiRNA applications is the unpredictability of silencing efficacy of the designed amiRNAs and not all constructed amiRNA candidates would be expressed effectively in plant cells. We and others found that high efficiency and specificity in RNA silencing can be achieved by designing amiRNAs with perfect or almost perfect sequence complementarity to their targets. In addition, we recently demonstrated that Agrobacterium-mediated transient expression system can be used to validate amiRNA constructs, which provides a simple, rapid and effective method to select highly expressible amiRNA candidates for stable genetic transformation. Here, we describe the methods for design of amiRNA candidates with perfect or almost perfect base-pairing to the target gene or gene groups, incorporation of amiRNA candidates in miR168a gene backbone by one step inverse PCR amplification, construction of plant amiRNA expression vectors, and assay of transient expression of amiRNAs in Nicotiana benthamiana through agro-infiltration, small RNA extraction, and amiRNA Northern blot.

Effects of pellet-to-cladding gap design parameters on the reliability of high burnup PWR fuel rods under steady state and transient conditions

International Nuclear Information System (INIS)

Tas, Fatma Burcu; Ergun, Sule

2013-01-01

Highlights: • Fuel performance of a typical Pressurized Water Reactor rod is analyzed. • Steady state fuel rod behavior is examined to see the effects of pellet to cladding gap thickness and gap gas pressure. • Transient fuel rod behavior is examined to see the effects of pellet to cladding gap thickness and gap gas pressure. • The optimum pellet to cladding gap thickness and gap gas pressure values of the simulated fuel are determined. • The effects of pellet to cladding gap design parameters on nuclear fuel reliability are examined. - Abstract: As an important improvement in the light water nuclear reactor operations, the nuclear fuel burnup rate is increased in recent decades and this increase causes heavier duty for the nuclear fuel. Since the high burnup fuel is exposed to very high thermal and mechanical stresses and since it operates in an environment with high radiation for about 18 month cycles, it carries the risk of losing its integrity. In this study; it is aimed to determine the effects of pellet–cladding gap thickness and gap pressure on reliability of high burnup nuclear fuel in Pressurized Water Reactors (PWRs) under steady state operation conditions and suggest optimum values for the examined parameters only and validate these suggestions for a transient condition. In the presented study, fuel performance was analyzed by examining the effects of pellet–cladding gap thickness and gap pressure on the integrity of high burnup fuels. This work is carried out for a typical Westinghouse type PWR fuel. The steady state conditions were modeled and simulated with FRAPCON-3.4a steady state fuel performance code and the FRAPTRAN-1.4 fuel transient code was used to calculate transient fuel behavior. The analysis included the changes in the important nuclear fuel design limitations such as the centerline temperature, cladding stress, strain and oxidation with the change in pellet–cladding gap thickness and initial pellet–cladding gap gas

Understanding Epileptiform After-Discharges as Rhythmic Oscillatory Transients.

Science.gov (United States)

Baier, Gerold; Taylor, Peter N; Wang, Yujiang

2017-01-01

Electro-cortical activity in patients with epilepsy may show abnormal rhythmic transients in response to stimulation. Even when using the same stimulation parameters in the same patient, wide variability in the duration of transient response has been reported. These transients have long been considered important for the mapping of the excitability levels in the epileptic brain but their dynamic mechanism is still not well understood. To investigate the occurrence of abnormal transients dynamically, we use a thalamo-cortical neural population model of epileptic spike-wave activity and study the interaction between slow and fast subsystems. In a reduced version of the thalamo-cortical model, slow wave oscillations arise from a fold of cycles (FoC) bifurcation. This marks the onset of a region of bistability between a high amplitude oscillatory rhythm and the background state. In vicinity of the bistability in parameter space, the model has excitable dynamics, showing prolonged rhythmic transients in response to suprathreshold pulse stimulation. We analyse the state space geometry of the bistable and excitable states, and find that the rhythmic transient arises when the impending FoC bifurcation deforms the state space and creates an area of locally reduced attraction to the fixed point. This area essentially allows trajectories to dwell there before escaping to the stable steady state, thus creating rhythmic transients. In the full thalamo-cortical model, we find a similar FoC bifurcation structure. Based on the analysis, we propose an explanation of why stimulation induced epileptiform activity may vary between trials, and predict how the variability could be related to ongoing oscillatory background activity. We compare our dynamic mechanism with other mechanisms (such as a slow parameter change) to generate excitable transients, and we discuss the proposed excitability mechanism in the context of stimulation responses in the epileptic cortex.

No seasonal accumulation of resistant P. falciparum when high-dose chloroquine is used

DEFF Research Database (Denmark)

Ursing, Johan; Kofoed, Poul-Erik; Rodrigues, Amabelia

2009-01-01

increase of pfcrt 76T if the high doses of CQ commonly used are effective. METHODS AND FINDINGS: P. falciparum parasite density, age, sex, the proportion of chloroquine resistance associated haplotypes pfcrt 76T and P. falciparum multidrug resistance gene 1 86Y were assessed in 988 samples collected from...... to become the dominant P.falciparum type in Guinea-Bissau. This is most likely due to the efficacy of high-dose chloroquine as used in Guinea-Bissau, combined with a loss of fitness associated with pfcrt 76T.......BACKGROUND: Potentially chloroquine resistant P. falciparum, identified by the 76T haplotype in the chloroquine resistance transporter (pfcrt 76T), are highly prevalent throughout Africa. In Guinea-Bissau, normal and double dose chloroquine have respective efficacies of 34% and 78% against P...

Transient MutS-Based Hypermutation System for Adaptive Evolution of Lactobacillus casei to Low pH.

Science.gov (United States)

Overbeck, Tom J; Welker, Dennis L; Hughes, Joanne E; Steele, James L; Broadbent, Jeff R

2017-10-15

This study explored transient inactivation of the gene encoding the DNA mismatch repair enzyme MutS as a tool for adaptive evolution of Lactobacillus casei MutS deletion derivatives of L. casei 12A and ATCC 334 were constructed and subjected to a 100-day adaptive evolution process to increase lactic acid resistance at low pH. Wild-type parental strains were also subjected to this treatment. At the end of the process, the Δ mutS lesion was repaired in representative L. casei 12A and ATCC 334 Δ mutS mutant isolates. Growth studies in broth at pH 4.0 (titrated with lactic acid) showed that all four adapted strains grew more rapidly, to higher cell densities, and produced significantly more lactic acid than untreated wild-type cells. However, the adapted Δ mutS derivative mutants showed the greatest increases in growth and lactic acid production. Further characterization of the L. casei 12A-adapted Δ mutS derivative revealed that it had a significantly smaller cell volume, a rougher cell surface, and significantly better survival at pH 2.5 than parental L. casei 12A. Genome sequence analysis confirmed that transient mutS inactivation decreased DNA replication fidelity in both L. casei strains, and it identified genetic changes that might contribute to the lactic acid-resistant phenotypes of adapted cells. Targeted inactivation of three genes that had acquired nonsense mutations in the adapted L. casei 12A Δ mutS mutant derivative showed that NADH dehydrogenase ( ndh ), phosphate transport ATP-binding protein PstB ( pstB ), and two-component signal transduction system (TCS) quorum-sensing histidine protein kinase ( hpk ) genes act in combination to increase lactic acid resistance in L. casei 12A. IMPORTANCE Adaptive evolution has been applied to microorganisms to increase industrially desirable phenotypes, including acid resistance. We developed a method to increase the adaptability of Lactobacillus casei 12A and ATCC 334 through transient inactivation of the DNA

Voltage transients in thin-film InSb Hall sensor

Science.gov (United States)

Bardin, Alexey; Ignatjev, Vyacheslav; Orlov, Andrey; Perchenko, Sergey

The work is reached to study temperature transients in thin-film Hall sensors. We experimentally study InSb thin-film Hall sensor. We find transients of voltage with amplitude about 10 μ V on the sensor ports after current switching. We demonstrate by direct measurements that the transients is caused by thermo-e.m.f., and both non-stationarity and heterogeneity of temperature in the film. We find significant asymmetry of temperature field for different direction of the current, which is probably related to Peltier effect. The result can be useful for wide range of scientist who works with switching of high density currents in any thin semiconductor films.

A numerical method for a transient two-fluid model

International Nuclear Information System (INIS)

Le Coq, G.; Libmann, M.

1978-01-01

The transient boiling two-phase flow is studied. In nuclear reactors, the driving conditions for the transient boiling are a pump power decay or/and an increase in heating power. The physical model adopted for the two-phase flow is the two fluid model with the assumption that the vapor remains at saturation. The numerical method for solving the thermohydraulics problems is a shooting method, this method is highly implicit. A particular problem exists at the boiling and condensation front. A computer code using this numerical method allow the calculation of a transient boiling initiated by a steady state for a PWR or for a LMFBR

Short-time, high temperature mechanical testing of electrically conductive materials

International Nuclear Information System (INIS)

Marion, R.H.; Karnes, C.H.

1975-10-01

Design and performance details are given for a facility which was developed to obtain the mechanical properties of materials under high heating rate or transient temperature conditions and medium strain rates. The system is shown to be applicable to materials possessing electrical resistivities ranging from that of aluminum to that of graphite without taxing the heating capability. Heating rates as high as 2000 0 K/s in graphite are attained under controlled conditions. Methods of measuring temperature and the effects of expected temperature distributions are discussed. A method for measuring strain valid for transient temperature conditions to 3000 0 K is described. Results are presented for the stress-strain behavior of 316 stainless steel and ATJ(S) graphite obtained for heating times of a few seconds. (auth)

High-Rate Glass Resistive Plate Chambers For LHC Muon Detectors Upgrade

CERN Document Server

Laktineh, I; Cauwenbergh, S; Combret, C; Crotty, I; Haddad, Y; Grenier, G; Guida, R; Kieffer, R; Lumb, N; Mirabito, L; Schirra, F; Seguin, N; Tytgat, M; Van der Donckt, M; Wang, Y; Zaganidis, N

2012-01-01

The limitation of the detection rate of standard bakelite resistive plate chambers (RPC) used as muon detector in LHC experiments is behind the absence of such detectors in the high TJ regions in both CMS and ATLAS detectors. RPCs made with low resistivity glass plates (10ID O.cm) could be an adequate solution to equip the high TJ regions extending thus both the trigger efficiency and the physics performance. Different beam tests with single and multi-gap configurations using the new glass have shown that such detectors can operate at few thousands Hzlcm2 with high efficiency( > 90%).

Superresolution microscopy with transient binding.

Science.gov (United States)

Molle, Julia; Raab, Mario; Holzmeister, Susanne; Schmitt-Monreal, Daniel; Grohmann, Dina; He, Zhike; Tinnefeld, Philip

2016-06-01

For single-molecule localization based superresolution, the concentration of fluorescent labels has to be thinned out. This is commonly achieved by photophysically or photochemically deactivating subsets of molecules. Alternatively, apparent switching of molecules can be achieved by transient binding of fluorescent labels. Here, a diffusing dye yields bright fluorescent spots when binding to the structure of interest. As the binding interaction is weak, the labeling is reversible and the dye ligand construct diffuses back into solution. This approach of achieving superresolution by transient binding (STB) is reviewed in this manuscript. Different realizations of STB are discussed and compared to other localization-based superresolution modalities. We propose the development of labeling strategies that will make STB a highly versatile tool for superresolution microscopy at highest resolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transients: The regulator's view

International Nuclear Information System (INIS)

Sheron, B.W.; Speis, T.P.

1984-01-01

This chapter attempts to clarify the basis for the regulator's concerns for transient events. Transients are defined as both anticipated operational occurrences and postulated accidents. Recent operational experience, supplemented by improved probabilistic risk analysis methods, has demonstrated that non-LOCA transient events can be significant contributors to overall risk. Topics considered include lessons learned from events and issues, the regulations governing plant transients, multiple failures, different failure frequencies, operator errors, and public pressure. It is concluded that the formation of Owners Groups and Regulatory Response Groups within the owners groups are positive signs of the industry's concern for safety and responsible dealing with the issues affecting both the US NRC and the industry

Rapid transient production in plants by replicating and non-replicating vectors yields high quality functional anti-HIV antibody.

Directory of Open Access Journals (Sweden)

Frank Sainsbury

2010-11-01

Full Text Available The capacity of plants and plant cells to produce large amounts of recombinant protein has been well established. Due to advantages in terms of speed and yield, attention has recently turned towards the use of transient expression systems, including viral vectors, to produce proteins of pharmaceutical interest in plants. However, the effects of such high level expression from viral vectors and concomitant effects on host cells may affect the quality of the recombinant product.To assess the quality of antibodies transiently expressed to high levels in plants, we have expressed and characterised the human anti-HIV monoclonal antibody, 2G12, using both replicating and non-replicating systems based on deleted versions of Cowpea mosaic virus (CPMV RNA-2. The highest yield (approximately 100 mg/kg wet weight leaf tissue of affinity purified 2G12 was obtained when the non-replicating CPMV-HT system was used and the antibody was retained in the endoplasmic reticulum (ER. Glycan analysis by mass-spectrometry showed that the glycosylation pattern was determined exclusively by whether the antibody was retained in the ER and did not depend on whether a replicating or non-replicating system was used. Characterisation of the binding and neutralisation properties of all the purified 2G12 variants from plants showed that these were generally similar to those of the Chinese hamster ovary (CHO cell-produced 2G12.Overall, the results demonstrate that replicating and non-replicating CPMV-based vectors are able to direct the production of a recombinant IgG similar in activity to the CHO-produced control. Thus, a complex recombinant protein was produced with no apparent effect on its biochemical properties using either high-level expression or viral replication. The speed with which a recombinant pharmaceutical with excellent biochemical characteristics can be produced transiently in plants makes CPMV-based expression vectors an attractive option for

High Rate of Resistance to Quinupristin-Dalfopristin in Enterococcus faecium Clinical Isolates from Korea

Science.gov (United States)

Oh, Won Sup; Ko, Kwan Soo; Song, Jae-Hoon; Lee, Mi Young; Park, Sulhee; Peck, Kyong Ran; Lee, Nam Yong; Kim, Choon-Kwan; Lee, Hyuck; Kim, Shin-Woo; Chang, Hyun-Ha; Kim, Yeon-Sook; Jung, Sook-In; Son, Jun Seong; Yeom, Joon-Sup; Ki, Hyun Kyun; Woo, Gun-Jo

2005-01-01

We tested the in vitro susceptibilities of 603 enterococcal isolates from eight tertiary-care hospitals in Korea. The quinupristin-dalfopristin resistance rate in Enterococcus faecium was very high (25 isolates, 10.0%). It was suggested that both clonal spread and the sporadic emergence of quinupristin-dalfopristin-resistant isolates may explain the high prevalence of quinupristin-dalfopristin resistance in Korea. PMID:16304198

Deep-HiTS: Rotation Invariant Convolutional Neural Network for Transient Detection

Science.gov (United States)

Cabrera-Vives, Guillermo; Reyes, Ignacio; Förster, Francisco; Estévez, Pablo A.; Maureira, Juan-Carlos

2017-02-01

We introduce Deep-HiTS, a rotation-invariant convolutional neural network (CNN) model for classifying images of transient candidates into artifacts or real sources for the High cadence Transient Survey (HiTS). CNNs have the advantage of learning the features automatically from the data while achieving high performance. We compare our CNN model against a feature engineering approach using random forests (RFs). We show that our CNN significantly outperforms the RF model, reducing the error by almost half. Furthermore, for a fixed number of approximately 2000 allowed false transient candidates per night, we are able to reduce the misclassified real transients by approximately one-fifth. To the best of our knowledge, this is the first time CNNs have been used to detect astronomical transient events. Our approach will be very useful when processing images from next generation instruments such as the Large Synoptic Survey Telescope. We have made all our code and data available to the community for the sake of allowing further developments and comparisons at https://github.com/guille-c/Deep-HiTS. Deep-HiTS is licensed under the terms of the GNU General Public License v3.0.

Transient electromagnetic mapping of clay units in the San Luis Valley, Colorado

Science.gov (United States)

Fitterman, David V.; Grauch, V.J.S.

2010-01-01

Transient electromagnetic soundings were used to obtain information needed to refine hydrologic models of the San Luis Valley, Colorado. The soundings were able to map an aquitard called the blue clay that separates an unconfined surface aquifer from a deeper confined aquifer. The blue clay forms a conductor with an average resistivity of 6.9 ohm‐m. Above the conductor are found a mixture of gray clay and sand. The gray clay has an average resistivity of 21 ohm‐m, while the sand has a resistivity of greater than 100 ohm‐m. The large difference in resistivity of these units makes mapping them with a surface geophysical method relatively easy. The blue clay was deposited at the bottom of Lake Alamosa which filled most of the San Luis Valley during the Pleistocene. The geometry of the blue clay is influenced by a graben on the eastern side of the valley. The depth to the blue clay is greater over the graben. Along the eastern edge of valley the blue clay appears to be truncated by faults.

Positron beam studies of transients in semiconductors

International Nuclear Information System (INIS)

Beling, C.D.; Ling, C.C.; Cheung, C.K.; Naik, P.S.; Zhang, J.D.; Fung, S.

2006-01-01

Vacancy-sensing positron deep level transient spectroscopy (PDLTS) is a positron beam-based technique that seeks to provide information on the electronic ionization levels of vacancy defects probed by the positron through the monitoring of thermal transients. The experimental discoveries leading to the concept of vacancy-sensing PDLTS are first reviewed. The major problem associated with this technique is discussed, namely the strong electric fields establish in the near surface region of the sample during the thermal transient which tend to sweep positrons into the contact with negligible defect trapping. New simulations are presented which suggest that under certain conditions a sufficient fraction of positrons may be trapped into ionizing defects rendering PDLTS technique workable. Some suggestions are made for techniques that might avoid the problematic electric field problem, such as optical-PDLTS where deep levels are populated using light and the use of high forward bias currents for trap filling

Transient Behaviour of Superconducting Magnet Systems of Fusion Reactor ITER during Safety Discharge

Directory of Open Access Journals (Sweden)

A. M. Miri

2008-01-01

Full Text Available To investigate the transient behaviour of the toroidal and poloidal field coils magnet systems of the International Thermonuclear Experimental Reactor during safety discharge, network models with lumped elements are established. Frequency-dependant values of the network elements, that is, inductances and resistances are calculated with the finite element method. That way, overvoltages can be determined. According to these overvoltages, the insulation coordination of coils has to be selected.

Transient-field strength measurements for 52Cr traversing Fe hosts at high velocity and polarization transfer mechanisms

International Nuclear Information System (INIS)

Stuchbery, A.E.; Doran, C.E.; Byrne, A.P.; Bolotin, H.H.; Dracoulis, G.D.

1986-12-01

Transient-field strengths were measured for 52 Cr ions traversing polarized Fe hosts at velocities up to 12v>=o (v>=o = c/137 = Bohr velocity). The results are compared with predictions of various transient field parametrizations and discussed in terms of possible mechanisms by which polarization might be transferred from the Fe host to inner vacancies of the moving Cr ions. The g-factor of the first 2 + state of 52 Cr was also measured by the transient field technique and found to be in accord with shell-model calculations

Lifetime improvement of sheathed thermocouples for use in high-temperature and thermal transient operations

International Nuclear Information System (INIS)

McCulloch, R.W.; Clift, J.H.

1982-01-01

Premature failure of small-diameter, magnesium-oxide-insulated sheathed thermocouples occurred when they were placed within nuclear fuel rod simulators (FRSs) to measure high temperatures and to follow severe thermal transients encountered during simulation of nuclear reactor accidents in Oak Ridge National Laboratory (ORNL) thermal-hydraulic test facilities. Investigation of thermally cycled thermocouples yielded three criteria for improvement of thermocouple lifetime: (1) reduction of oxygen impurities prior to and during their fabrication, (2) refinement of thermoelement grain size during their fabrication, and (3) elimination of prestrain prior to use above their recrystallization temperature. The first and third criteria were satisfied by improved techniques of thermocouple assembly and by a recovery anneal prior to thermocouple use

A Highly Stable Marching-on-in-Time Volume Integral Equation Solver for Analyzing Transient Wave Interactions on High-Contrast Scatterers

KAUST Repository

Bagci, Hakan

2014-01-06

). Numerical results demonstrate that this new MOT-VIE solver maintains its stability and accuracy even when used in analyzing transient wave interactions on high-contrast scatterers.

Title: High-level cefotaxime-resistant Proteus mirabilis strain isolated ...

African Journals Online (AJOL)

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High-level cefotaxime-resistant Proteus mirabilis strain isolated from a Tunisian .... UV- visible) at 37°C. Specific activity is calculated on depending of. Ross and ..... Performance standards for antimicrobial susceptibility testing;. Seventeenth ...

Boiling and burnout phenomena under transient heat input, 1

International Nuclear Information System (INIS)

Aoki, Shigebumi; Kozawa, Yoshiyuki; Iwasaki, Hideaki.

1976-01-01

In order to simulate the thermo-hydrodynamic conditions at reactor power excursions, a test piece was placed in a forced convective channel and heated with exponential power inputs. The boiling heat transfer and the burnout heat flux under the transient heat input were measured, and pressure and water temperature changes in the test section were recorded at the same time. Following experimental results were obtained; (1) Transient boiling heat transfer characteristics at high heat flux stayed on the stationary nucleate boiling curve of each flow condition, or extrapolated line of the curves. (2) Transient burnout heat flux increased remarkably with decreasing heating-time-constant, when the flow rate was lower and the subcooling was higher. (3) Transient burnout phenomena were expressed with the relation of (q sub(max) - q sub(sBO)) tau = constant at several flow conditions. This relation was derived from the stationary burnout mechanism of pool boiling. (auth.)

Assessment of the potential for high-pressure melt ejection resulting from a Surry station blackout transient

International Nuclear Information System (INIS)

Knudson, D.L.; Dobbe, C.A.

1993-11-01

Containment integrity could be challenged by direct heating associated with a high pressure melt ejection (HPME) of core materials following reactor vessel breach during certain severe accidents. Intentional reactor coolant system (RCS) depressurization, where operators latch pressurizer relief valves open, has been proposed as an accident management strategy to reduce risks by mitigating the severity of HPME. However, decay heat levels, valve capacities, and other plant-specific characteristics determine whether the required operator action will be effective. Without operator action, natural circulation flows could heat ex-vessel RCS pressure boundaries (surge line and hot leg piping, steam generator tubes, etc.) to the point of failure before vessel breach, providing an alternate mechanism for RCS depressurization and HPME mitigation. This report contains an assessment of the potential for HPME during a Surry station blackout transient without operator action and without recovery. The assessment included a detailed transient analysis using the SCDAP/RELAP5/MOD3 computer code to calculate the plant response with and without hot leg countercurrent natural circulation, with and without reactor coolant pump seal leakage, and with variations on selected core damage progression parameters. RCS depressurization-related probabilities were also evaluated, primarily based on the code results

Analyses on Silicide Coating for LOCA Resistant Cladding

Energy Technology Data Exchange (ETDEWEB)

Sweidan, Faris B.; Lee, You Ho; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)

2015-10-15

A particular focus of accident-tolerant fuel has been cladding due to the rapid high-temperature oxidation of zirconium-based cladding with the evolution of H2 when steam is a reactant. Some key features of the coated cladding include high-temperature resistance to oxidation, lower processing temperatures, and a high melting point of the coating. Zirconium alloys exhibit a reasonably high melting temperature, so a coating for the cladding is appealing if the coating increases the high-temperature resistance to oxidation. In this case, the cladding is protected from complete oxidation. The cladding coating involves the application of zirconium silicide onto Zr-based cladding. Zirconium silicide coating is expected to produce a glassy layer that becomes more protective at elevated temperature. For this reason, silicide coatings on cladding offer the potential for improved reliability at normal operating temperatures and at the higher transient temperatures encountered during accidents. Although ceramic coatings are brittle and may have weak points to be used as coating materials, several ceramic coatings were successful and showed adherent behavior and high resistance to oxidation. In this study, the oxidation behavior of zirconium silicide and its oxidation kinetics are analyzed. Zirconium silicide is a new suggested material to be used as coatings on existing Zr-based cladding alloys, the aim of this study is to evaluate if zirconium silicide is applicable to be used, so they can be more rapidly developed using existing cladding technology with some modifications. These silicide coatings are an attractive alternative to the use of coatings on zirconium claddings or to the lengthy development of monolithic ceramic or ceramic composite claddings and coatings.

Analyses on Silicide Coating for LOCA Resistant Cladding

International Nuclear Information System (INIS)

Sweidan, Faris B.; Lee, You Ho; Ryu, Ho Jin

2015-01-01

A particular focus of accident-tolerant fuel has been cladding due to the rapid high-temperature oxidation of zirconium-based cladding with the evolution of H2 when steam is a reactant. Some key features of the coated cladding include high-temperature resistance to oxidation, lower processing temperatures, and a high melting point of the coating. Zirconium alloys exhibit a reasonably high melting temperature, so a coating for the cladding is appealing if the coating increases the high-temperature resistance to oxidation. In this case, the cladding is protected from complete oxidation. The cladding coating involves the application of zirconium silicide onto Zr-based cladding. Zirconium silicide coating is expected to produce a glassy layer that becomes more protective at elevated temperature. For this reason, silicide coatings on cladding offer the potential for improved reliability at normal operating temperatures and at the higher transient temperatures encountered during accidents. Although ceramic coatings are brittle and may have weak points to be used as coating materials, several ceramic coatings were successful and showed adherent behavior and high resistance to oxidation. In this study, the oxidation behavior of zirconium silicide and its oxidation kinetics are analyzed. Zirconium silicide is a new suggested material to be used as coatings on existing Zr-based cladding alloys, the aim of this study is to evaluate if zirconium silicide is applicable to be used, so they can be more rapidly developed using existing cladding technology with some modifications. These silicide coatings are an attractive alternative to the use of coatings on zirconium claddings or to the lengthy development of monolithic ceramic or ceramic composite claddings and coatings

Transient behavior of high-interaction MHD generator following external loading faults

International Nuclear Information System (INIS)

Ishikawa, Motoo

1983-01-01

Transient behavior consequent to external loading faults is studied numerically on four configurations of high-interaction MHD generators-subsonic Faraday, supersonic Faraday, subsonic diagonal and supersonic diagonal, to provide a variable data base to serve in selecting the type of large-scale MHD generator. Time-dependent one-dimensional Navier-Stokes equations are solved with the 1969 MacCormack method, in combination with the Maxwell equations and the generalized Ohm's law. An artificial viscosity term is added to the Navier-Stokes equations to maintain numerical stability. It is shown that, with both supersonic and subsonic flows, the Faraday generator is liable to sustain more harmful effect from short than from open faults of the external loading circuit. For large-scale diagonal types, on the other hand, open faults are more dangerous. With subsonic flow, a shock wave propagating upstream is induced by short fault in the Faraday, and by open fault in the diagonal-type generator. In the case of supersonic flow, propagation upstream of the disturbance is completely obstructed. Larger electrical stress is foreseen for Faraday than for diagonal configuration. (author)

Resistance against Schistosoma mansoni induced by highly irradiated infections: studies on species specificity of immunization and attempts to transfer resistance

International Nuclear Information System (INIS)

Bickle, Q.D.; Andrews, B.J.; Doenhoff, M.J.; Ford, M.J.; Taylor, M.G.

1985-01-01

Significant levels of resistance against Schistosoma mansoni challenge were developed by mice exposed to highly irradiated (20 krad.) cercariae of the homologous species (53-67%), whereas vaccination with S. bovis, S. haematobium or S. japonicum failed to confer significant levels of resistance (-5-12%), thus confirming the specificity of the immunizing procedure. Attempts to transfer resistance to naive recipients by injection of serum and of spleen or lymph node cells from donor mice vaccinated with highly irradiated cercariae were largely unsuccessful. However, significant levels of resistance could be transferred to mice by injection of serum from rabbits exposed to irradiated cercariae. Comparable levels of resistance were conferred by injection of serum at the time of challenge (34-69%) or 5-6 days later (31-56%). In contrast, sera from rabbits injected with soluble egg antigen or homogenized cercariae failed to confer protection upon recipient mice. Sera from vaccinated mice, vaccinated rabbits and antigen-injected rabbits all caused cell adherence to skin-transformed schistosomula but neither the level of adherence nor the serum titre correlated with the ability to confer protection to mice. (author)

The use of high-throughput sequencing to investigate an outbreak of glycopeptide-resistant Enterococcus faecium with a novel quinupristin-dalfopristin resistance mechanism.

Science.gov (United States)

Shaw, Timothy D; Fairley, D J; Schneiders, T; Pathiraja, M; Hill, R L R; Werner, G; Elborn, J S; McMullan, R

2018-02-24

High-throughput sequencing (HTS) has successfully identified novel resistance genes in enterococci and determined clonal relatedness in outbreak analysis. We report the use of HTS to investigate two concurrent outbreaks of glycopeptide-resistant Enterococcus faecium (GRE) with an uncharacterised resistance mechanism to quinupristin-dalfopristin (QD). Seven QD-resistant and five QD-susceptible GRE isolates from a two-centre outbreak were studied. HTS was performed to identify genes or predicted proteins that were associated with the QD-resistant phenotype. MLST and SNP typing on HTS data was used to determine clonal relatedness. Comparative genomic analysis confirmed this GRE outbreak involved two distinct clones (ST80 and ST192). HTS confirmed the absence of known QD resistance genes, suggesting a novel mechanism was conferring resistance. Genomic analysis identified two significant genetic determinants with explanatory power for the high level of QD resistance in the ST80 QD-resistant clone: an additional 56aa leader sequence at the N-terminus of the lsaE gene and a transposon containing seven genes encoding proteins with possible drug or drug-target modification activities. However, HTS was unable to conclusively determine the QD resistance mechanism and did not reveal any genetic basis for QD resistance in the ST192 clone. This study highlights the usefulness of HTS in deciphering the degree of relatedness in two concurrent GRE outbreaks. Although HTS was able to reveal some genetic candidates for uncharacterised QD resistance, this study demonstrates the limitations of HTS as a tool for identifying putative determinants of resistance to QD.

High dietary zinc feeding promotes persistence of multi-resistant E. coli in the swine gut.

Science.gov (United States)

Ciesinski, Lisa; Guenther, Sebastian; Pieper, Robert; Kalisch, Martin; Bednorz, Carmen; Wieler, Lothar H

2018-01-01

High levels of zinc oxide are used frequently as feed additive in pigs to improve gut health and growth performance and are still suggested as an alternative to antimicrobial growth promoters. However, we have recently described an increase of multi-resistant E. coli in association to zinc feeding in piglets. This previous study focused on clonal diversity of E. coli, observing the effect on multi-resistant strains by chance. To shed further light into this highly important topic and falsify our previous findings, we performed a zinc pig feeding trial where we specifically focused on in-depth analysis of antimicrobial resistant E. coli. Under controlled experimental conditions, piglets were randomly allocated to a high dietary zinc (zinc group) and a background zinc feeding group (control group). At different ages samples were taken from feces, digesta, and mucosa and absolute E. coli numbers were determined. A total of 2665 E. coli isolates were than phenotypically tested for antimicrobial resistance and results were confirmed by minimum inhibitory concentration testing for random samples. In piglets fed with high dietary zinc, we detected a substantial increase of multi-resistant E. coli in all gut habitats tested, ranging from 28.9-30.2% multi-resistant E. coli compared to 5.8-14.0% in the control group. This increase was independent of the total number of E. coli. Interestingly, the total amount of the E. coli population decreased over time. Thus, the increase of the multi-resistant E. coli populations seems to be linked with persistence of the resistant population, caused by the influence of high dietary zinc feeding. In conclusion, these findings corroborate our previous report linking high dietary zinc feeding of piglets with the occurrence of antimicrobial resistant E. coli and therefore question the feeding of high dietary zinc oxide as alternative to antimicrobial growth promoters.

Screen for soil fungi highly resistant to dichloroaniline uncovers mostly Fusarium species.

Science.gov (United States)

Chan Ho Tong, Laetitia; Dairou, Julien; Bui, Linh-Chi; Bouillon, Julien; Rodrigues-Lima, Fernando; Dupret, Jean-Marie; Silar, Philippe

2015-08-01

Arylamines are frequent pollutants in soils. Fungi have proven to be efficient in detoxifying these chemicals by acetylating them using arylamine N-acetyl transferase enzymes. Here, we selected from natural soils fungi highly resistant to 3,4-dichloroaniline (DCA). Fusarium species were the most frequently isolated species, especially Fusarium solani. The sequenced strain of F. solani contains five NAT genes, as did all the DCA-resistant isolates. RT-PCR analysis showed that the five genes were expressed in F. solani. Expression of the F. solani genes in Podospora anserina and analysis of acetylation directly in F. solani showed that only the NhNAT2B gene conferred significant resistance to DCA and that F. solani likely uses pathways different from acetylation to resist high doses of DCA, as observed previously for Trichoderma. Copyright © 2015 Elsevier Inc. All rights reserved.

Development of leak detection system using high temperature-resistant microphones

International Nuclear Information System (INIS)

Morishita, Yoshitsugu; Mochizuki, Hiroyasu; Watanabe, Kenshiu; Nakamura, Takahisa; Nakazima, Yoshiaki; Yamauchi, Tatsuya

1995-01-01

This report describes the development and testing of a coolant leak detection system for an inlet feeder pipe of an advanced thermal reactor (ATR) using high temperature-resistant microphones. Such microphones must be resistant to both high temperatures and high radiation doses. Leakage sound characteristics, attenuation of the sound level in a heat insulating box for the inlet feeder pipes, and background noise were investigated using the experimental facility and the prototype ATR 'FUGEN'. The optimum frequency ranges for the microphone were then determined based on the observed leakage sound and background noise. The ability of the microphone to discriminate between leaks and other burst-type noises was also investigated by statistical analyses. Finally, it was confirmed that the present method could detect a leak within a couple of seconds. (author)

Searching for MHz Transients with the VLA Low-band Ionosphere and Transient Experiment (VLITE)

Science.gov (United States)

Polisensky, Emil; Peters, Wendy; Giacintucci, Simona; Clarke, Tracy; Kassim, Namir E.; hyman, Scott D.; van der Horst, Alexander; Linford, Justin; Waldron, Zach; Frail, Dale

2018-01-01

NRL and NRAO have expanded the low frequency capabilities of the VLA through the VLA Low-band Ionosphere and Transient Experiment (VLITE, http://vlite.nrao.edu/ ), effectively making the instrument two telescopes in one. VLITE is a commensal observing system that harvests data from the prime focus in parallel with normal Cassegrain focus observing on a subset of VLA antennas. VLITE provides over 6000 observing hours per year in a > 5 square degree field-of-view using 64 MHz bandwidth centered on 352 MHz. By operating in parallel, VLITE offers invaluable low frequency data to targeted observations of transient sources detected at higher frequencies. With arcsec resolution and mJy sensitivity, VLITE additionally offers great potential for blind searches of rarer radio-selected transients. We use catalog matching software on the imaging products from the daily astrophysics pipeline and the LOFAR Transients Pipeline (TraP) on repeated observations of the same fields to search for coherent and incoherent astronomical transients on timescales of a few seconds to years. We present the current status of the VLITE transient science program from its initial deployment on 10 antennas in November 2014 through its expansion to 16 antennas in the summer of 2017. Transient limits from VLITE’s first year of operation (Polisensky et al. 2016) are updated per the most recent analysis.

Increased radiation resistance in lithium-counterdoped silicon solar cells

Science.gov (United States)

Weinberg, I.; Swartz, C. K.; Mehta, S.

1984-01-01

Lithium-counterdoped n(+)p silicon solar cells are found to exhibit significantly increased radiation resistance to 1-MeV electron irradiation when compared to boron-doped n(+)p silicon solar cells. In addition to improved radiation resistance, considerable damage recovery by annealing is observed in the counterdoped cells at T less than or equal to 100 C. Deep level transient spectroscopy measurements are used to identify the defect whose removal results in the low-temperature aneal. It is suggested that the increased radiation resistance of the counterdoped cells is primarily due to interaction of the lithium with interstitial oxygen.

A High-Speed Spectroscopy System for Observing Lightning and Transient Luminous Events

Science.gov (United States)

Boggs, L.; Liu, N.; Austin, M.; Aguirre, F.; Tilles, J.; Nag, A.; Lazarus, S. M.; Rassoul, H.

2017-12-01

Here we present a high-speed spectroscopy system that can be used to record atmospheric electrical discharges, including lightning and transient luminous events. The system consists of a Phantom V1210 high-speed camera, a Volume Phase Holographic (VPH) grism, an optional optical slit, and lenses. The spectrograph has the capability to record videos at speeds of 200,000 frames per second and has an effective wavelength band of 550-775 nm for the first order spectra. When the slit is used, the system has a spectral resolution of about 0.25 nm per pixel. We have constructed a durable enclosure made of heavy duty aluminum to house the high-speed spectrograph. It has two fans for continuous air flow and a removable tray to mount the spectrograph components. In addition, a Watec video camera (30 frames per second) is attached to the top of the enclosure to provide a scene view. A heavy duty Pelco pan/tilt motor is used to position the enclosure and can be controlled remotely through a Rasperry Pi computer. An observation campaign has been conducted during the summer and fall of 2017 at the Florida Institute of Technology. Several close cloud-to-ground discharges were recorded at 57,000 frames per second. The spectrum of a downward stepped negative leader and a positive cloud-to-ground return stroke will be reported on.

Mechanisms of Evolution in High-Consequence Drug Resistance Plasmids.

Science.gov (United States)

He, Susu; Chandler, Michael; Varani, Alessandro M; Hickman, Alison B; Dekker, John P; Dyda, Fred

2016-12-06

The dissemination of resistance among bacteria has been facilitated by the fact that resistance genes are usually located on a diverse and evolving set of transmissible plasmids. However, the mechanisms generating diversity and enabling adaptation within highly successful resistance plasmids have remained obscure, despite their profound clinical significance. To understand these mechanisms, we have performed a detailed analysis of the mobilome (the entire mobile genetic element content) of a set of previously sequenced carbapenemase-producing Enterobacteriaceae (CPE) from the National Institutes of Health Clinical Center. This analysis revealed that plasmid reorganizations occurring in the natural context of colonization of human hosts were overwhelmingly driven by genetic rearrangements carried out by replicative transposons working in concert with the process of homologous recombination. A more complete understanding of the molecular mechanisms and evolutionary forces driving rearrangements in resistance plasmids may lead to fundamentally new strategies to address the problem of antibiotic resistance. The spread of antibiotic resistance among Gram-negative bacteria is a serious public health threat, as it can critically limit the types of drugs that can be used to treat infected patients. In particular, carbapenem-resistant members of the Enterobacteriaceae family are responsible for a significant and growing burden of morbidity and mortality. Here, we report on the mechanisms underlying the evolution of several plasmids carried by previously sequenced clinical Enterobacteriaceae isolates from the National Institutes of Health Clinical Center (NIH CC). Our ability to track genetic rearrangements that occurred within resistance plasmids was dependent on accurate annotation of the mobile genetic elements within the plasmids, which was greatly aided by access to long-read DNA sequencing data and knowledge of their mechanisms. Mobile genetic elements such as

High hardness and superlative oxidation resistance in a pseudo-icosahehdral Cr-Al binary

Science.gov (United States)

Simonson, J. W.; Rosa, R.; Antonacci, A. K.; He, H.; Bender, A. D.; Pabla, J.; Adrip, W.; McNally, D. E.; Zebro, A.; Kamenov, P.; Geschwind, G.; Ghose, S.; Dooryhee, E.; Ibrahim, A.; Aronson, M. C.

Improving the efficiency of fossil fuel plants is a practical option for decreasing carbon dioxide emissions from electrical power generation. Present limits on the operating temperatures of exposed steel components, however, restrict steam temperatures and therefore energy efficiency. Even as a new generation of creep-resistant, high strength steels retain long term structural stability to temperatures as high as ~ 973 K, the low Cr-content of these alloys hinders their oxidation resistance, necessitating the development of new corrosion resistant coatings. We report here the nearly ideal properties of potential coating material Cr55Al229, which exhibits high hardness at room temperature as well as low thermal conductivity and superlative oxidation resistance at 973 K, with an oxidation rate at least three times smaller than those of benchmark materials. These properties originate from a pseudo-icosahedral crystal structure, suggesting new criteria for future research.

[From the discovery of antibiotics to emerging highly drug-resistant bacteria].

Science.gov (United States)

Meunier, Olivier

2015-01-01

The discovery of antibiotics has enabled serious infections to be treated. However, bacteria resistant to several families of antibiotics and the emergence of new highly drug-resistant bacteria constitute a public health issue in France and across the world. Actions to prevent their transmission are being put in place. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Characterization of transient gain x-ray lasers

International Nuclear Information System (INIS)

Dunn, J.; Osterheld, A.; Shlyaptsev, V.

1999-01-01

We have performed numerical simulations of the transient collisional excitation Ni-like Pd 4d → 4p J = 0 → 1 147 angstrom laser transition recently observed at Lawrence Livermore National Laboratory (LLNL). The high gain ∼35 cm results from the experiment are compared with detailed modeling simulations from the 1-D RADEX code in order to better understand the main physics issues affecting the measured gain and x-ray laser propagation along the plasma column. Simulations indicate that the transient gain lifetime associated with the short pulse pumping and refraction of the x-ray laser beam out of the gain region are the main detrimental effects. Gain lifetimes of ∼7 ps(1/e decay) are inferred from the smoothly changing gain experimental observations and are in good agreement with the simulations. Furthermore, the modeling results indicate the presence of a longer-lived but lower gain later in time associated with the transition from transient to quasi-steady state excitation

RFI flagging implications for short-duration transients

Science.gov (United States)

Cendes, Y.; Prasad, P.; Rowlinson, A.; Wijers, R. A. M. J.; Swinbank, J. D.; Law, C. J.; van der Horst, A. J.; Carbone, D.; Broderick, J. W.; Staley, T. D.; Stewart, A. J.; Huizinga, F.; Molenaar, G.; Alexov, A.; Bell, M. E.; Coenen, T.; Corbel, S.; Eislöffel, J.; Fender, R.; Grießmeier, J.-M.; Jonker, P.; Kramer, M.; Kuniyoshi, M.; Pietka, M.; Stappers, B.; Wise, M.; Zarka, P.

2018-04-01

With their wide fields of view and often relatively long coverage of any position in the sky in imaging survey mode, modern radio telescopes provide a data stream that is naturally suited to searching for rare transients. However, Radio Frequency Interference (RFI) can show up in the data stream in similar ways to such transients, and thus the normal pre-treatment of filtering RFI (flagging) may also remove astrophysical transients from the data stream before imaging. In this paper we investigate how standard flagging affects the detectability of such transients by examining the case of transient detection in an observing mode used for Low Frequency Array (LOFAR; van Haarlem et al., 2013) surveys. We quantify the fluence range of transients that would be detected, and the reduction of their SNR due to partial flagging. We find that transients with a duration close to the integration sampling time, as well as bright transients with durations on the order of tens of seconds, are completely flagged. For longer transients on the order of several tens of seconds to minutes, the flagging effects are not as severe, although part of the signal is lost. For these transients, we present a modified flagging strategy which mitigates the effect of flagging on transient signals. We also present a script which uses the differences between the two strategies, and known differences between transient RFI and astrophysical transients, to notify the observer when a potential transient is in the data stream.

Body size mediated starvation resistance in an insect predator.

NARCIS (Netherlands)

Gergs, A.; Jager, T.

2014-01-01

Summary: Individual organisms have to endure transient periods of low-food supply with consequences for growth, reproduction and survival. To resist starvation, animals usually store resources in their bodies: the larger the animals are, the more resources they can carry, but the more energy they

A population of highly energetic transient events in the centres of active galaxies

Science.gov (United States)

Kankare, E.; Kotak, R.; Mattila, S.; Lundqvist, P.; Ward, M. J.; Fraser, M.; Lawrence, A.; Smartt, S. J.; Meikle, W. P. S.; Bruce, A.; Harmanen, J.; Hutton, S. J.; Inserra, C.; Kangas, T.; Pastorello, A.; Reynolds, T.; Romero-Cañizales, C.; Smith, K. W.; Valenti, S.; Chambers, K. C.; Hodapp, K. W.; Huber, M. E.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

2017-12-01

Recent all-sky surveys have led to the discovery of new types of transients. These include stars disrupted by the central supermassive black hole, and supernovae that are 10-100 times more energetic than typical ones. However, the nature of even more energetic transients that apparently occur in the innermost regions of their host galaxies is hotly debated1-3. Here we report the discovery of the most energetic of these to date: PS1-10adi, with a total radiated energy of 2.3 × 1052 erg. The slow evolution of its light curve and persistently narrow spectral lines over ˜ 3 yr are inconsistent with known types of recurring black hole variability. The observed properties imply powering by shock interaction between expanding material and large quantities of surrounding dense matter. Plausible sources of this expanding material are a star that has been tidally disrupted by the central black hole, or a supernova. Both could satisfy the energy budget. For the former, we would be forced to invoke a new and hitherto unseen variant of a tidally disrupted star, while a supernova origin relies principally on environmental effects resulting from its nuclear location. Remarkably, we also discover that PS1-10adi is not an isolated case. We therefore surmise that this new population of transients has previously been overlooked due to incorrect association with underlying central black hole activity.

Expression of the Bs2 pepper gene confers resistance to bacterial spot disease in tomato.

Science.gov (United States)

Tai, T H; Dahlbeck, D; Clark, E T; Gajiwala, P; Pasion, R; Whalen, M C; Stall, R E; Staskawicz, B J

1999-11-23

The Bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of Xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrBs2. The involvement of avrBs2 in pathogen fitness and its prevalence in many X. campestris pathovars suggests that the Bs2 gene may be durable in the field and provide resistance when introduced into other plant species. Employing a positional cloning strategy, the Bs2 locus was isolated and the gene was identified by coexpression with avrBs2 in an Agrobacterium-mediated transient assay. A single candidate gene, predicted to encode motifs characteristic of the nucleotide binding site-leucine-rich repeat class of resistance genes, was identified. This gene specifically controlled the hypersensitive response when transiently expressed in susceptible pepper and tomato lines and in a nonhost species, Nicotiana benthamiana, and was designated as Bs2. Functional expression of Bs2 in stable transgenic tomatoes supports its use as a source of resistance in other Solanaceous plant species.

Differential Effects of High-Carbohydrate and High-Fat Diet Composition on Metabolic Control and Insulin Resistance in Normal Rats

Science.gov (United States)

Ble-Castillo, Jorge L.; Aparicio-Trapala, María A.; Juárez-Rojop, Isela E.; Torres-Lopez, Jorge E.; Mendez, Jose D.; Aguilar-Mariscal, Hidemi; Olvera-Hernández, Viridiana; Palma-Cordova, Leydi C.; Diaz-Zagoya, Juan C.

2012-01-01

The macronutrient component of diets is critical for metabolic control and insulin action. The aim of this study was to compare the effects of high fat diets (HFDs) vs. high carbohydrate diets (HCDs) on metabolic control and insulin resistance in Wistar rats. Thirty animals divided into five groups (n = 6) were fed: (1) Control diet (CD); (2) High-saturated fat diet (HSFD); (3) High-unsaturated fat diet (HUFD); (4) High-digestible starch diet, (HDSD); and (5) High-resistant starch diet (HRSD) during eight weeks. HFDs and HCDs reduced weight gain in comparison with CD, however no statistical significance was reached. Calorie intake was similar in both HFDs and CD, but rats receiving HCDs showed higher calorie consumption than other groups, (p < 0.01). HRSD showed the lowest levels of serum and hepatic lipids. The HUFD induced the lowest fasting glycemia levels and HOMA-IR values. The HDSD group exhibited the highest insulin resistance and hepatic cholesterol content. In conclusion, HUFD exhibited the most beneficial effects on glycemic control meanwhile HRSD induced the highest reduction on lipid content and did not modify insulin sensitivity. In both groups, HFDs and HCDs, the diet constituents were more important factors than caloric intake for metabolic disturbance and insulin resistance. PMID:22754464

Transient elevation of glycolysis confers radio-resistance by facilitating DNA repair in cells

International Nuclear Information System (INIS)

Bhatt, Anant Narayan; Chauhan, Ankit; Khanna, Suchit; Rai, Yogesh; Singh, Saurabh; Soni, Ravi; Kalra, Namita; Dwarakanath, Bilikere S

2015-01-01

Cancer cells exhibit increased glycolysis for ATP production (the Warburg effect) and macromolecular biosynthesis; it is also linked with therapeutic resistance that is generally associated with compromised respiratory metabolism. Molecular mechanisms underlying radio-resistance linked to elevated glycolysis remain incompletely understood. We stimulated glycolysis using mitochondrial respiratory modifiers (MRMs viz. di-nitro phenol, DNP; Photosan-3, PS3; Methylene blue, MB) in established human cell lines (HEK293, BMG-1 and OCT-1). Glucose utilization and lactate production, levels of glucose transporters and glycolytic enzymes were investigated as indices of glycolysis. Clonogenic survival, DNA repair and cytogenetic damage were studied as parameters of radiation response. MRMs induced the glycolysis by enhancing the levels of two important regulators of glucose metabolism GLUT-1 and HK-II and resulted in 2 fold increase in glucose consumption and lactate production. This increase in glycolysis resulted in resistance against radiation-induced cell death (clonogenic survival) in different cell lines at an absorbed dose of 5 Gy. Inhibition of glucose uptake and glycolysis (using fasentin, 2-deoxy-D-glucose and 3-bromopyruvate) in DNP treated cells failed to increase the clonogenic survival of irradiated cells, suggesting that radio-resistance linked to inhibition of mitochondrial respiration is glycolysis dependent. Elevated glycolysis also facilitated rejoining of radiation-induced DNA strand breaks by activating both non-homologous end joining (NHEJ) and homologous recombination (HR) pathways of DNA double strand break repair leading to a reduction in radiation-induced cytogenetic damage (micronuclei formation) in these cells. These findings suggest that enhanced glycolysis generally observed in cancer cells may be responsible for the radio-resistance, partly by enhancing the repair of DNA damage

Trapping induced Neff and electrical field transformation at different temperatures in neutron irradiated high resistivity silicon detectors

International Nuclear Information System (INIS)

Eremin, V.; Li, Z.; Iljashenko, I.

1994-02-01

The trapping of both non-equilibrium electrons and holes by neutron induced deep levels in high resistivity silicon planar detectors have been observed. In the experiments Transient Current and Charge Techniques, with short laser light pulse excitation have been applied at temperature ranges of 77--300 k. Light pulse illumination of the front (p + ) and back (n + ) contacts of the detectors showed effective trapping and detrapping, especially for electrons. At temperatures lower than 150 k, the detrapping becomes non-efficient, and the additional negative charge of trapped electrons in the space charge region (SCR) of the detectors leads to dramatic transformations of the electric field due to the distortion of the effective space charge concentration N eff . The current and charge pulses transformation data can be explained in terms of extraction of electric field to the central part of the detector from the regions near both contacts. The initial field distribution may be recovered immediately by dropping reverse bias, which injects both electrons and holes into the space charge region. In the paper, the degree of the N eff distortions among various detectors irradiated by different neutron fluences are compared

The Transient High-Energy Sky and Early Universe Surveyor (THESEUS)

Science.gov (United States)

Amati, L.; O'Brien, P.; Goetz, D.; Tenzer, C.; Bozzo, E.

2017-10-01

The Transient High Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept developed by a large international collaboration aimed at exploiting Gamma-Ray Bursts for investigating the early Universe. The main scientic objectives of THESEUS, currently under evaluation by ESA within the selection process for next M5 mission, include: investigating the star formation rate and metallicity evolution of the ISM and IGM up to redshift 10, detecting the first generation (pop III) of stars, studying the sources and physics of re-ionization, detecting the faint end of galaxies luminosity function. These goals will be achieved through a unique combination of instruments allowing GRB detection and arcmin localization over a broad FOV (more than 1sr) and an energy band extending from several MeVs down to 0.3 keV with unprecedented sensitivity, as well as on-board prompt (few minutes) follow-up with a 0.7m class IR telescope with both imaging and spectroscopic capabilities. Such instrumentation will also allow THESEUS to perform a monitoring of the X-ray sky with unprecedented sensitivity, which will provide a perfect service and sinergy to next generation multi-wavalength (e.g., E-ELT, SKA, CTA, ATHENA) and multi-messenger (aLIGO, aVIRGO, eLISA, ET, neutrino detectors, ...) facilities.

High-pressure resistivity technique for quasi-hydrostatic compression experiments.

Science.gov (United States)

Rotundu, C R; Ćuk, T; Greene, R L; Shen, Z-X; Hemley, Russell J; Struzhkin, V V

2013-06-01

Diamond anvil cell techniques are now well established and powerful methods for measuring materials properties to very high pressure. However, high pressure resistivity measurements are challenging because the electrical contacts attached to the sample have to survive to extreme stress conditions. Until recently, experiments in a diamond anvil cell were mostly limited to non-hydrostatic or quasi-hydrostatic pressure media other than inert gases. We present here a solution to the problem by using focused ion beam ultrathin lithography for a diamond anvil cell loaded with inert gas (Ne) and show typical resistivity data. These ultrathin leads are deposited on the culet of the diamond and are attaching the sample to the anvil mechanically, therefore allowing for measurements in hydrostatic or nearly hydrostatic conditions of pressure using noble gases like Ne or He as pressure transmitting media.

Transient characteristics of current lead losses for the large scale high-temperature superconducting rotating machine

International Nuclear Information System (INIS)

Le, T. D.; Kim, J. H.; Park, S. I.; Kim, D. J.; Kim, H. M.; Lee, H. G.; Yoon, Y. S.; Jo, Y. S.; Yoon, K. Y.

2014-01-01

To minimize most heat loss of current lead for high-temperature superconducting (HTS) rotating machine, the choice of conductor properties and lead geometry - such as length, cross section, and cooling surface area - are one of the various significant factors must be selected. Therefore, an optimal lead for large scale of HTS rotating machine has presented before. Not let up with these trends, this paper continues to improve of diminishing heat loss for HTS part according to different model. It also determines the simplification conditions for an evaluation of the main flux flow loss and eddy current loss transient characteristics during charging and discharging period.

Primary drug resistance in a region with high burden of tuberculosis. A critical problem.

Science.gov (United States)

Villa-Rosas, Cecilia; Laniado-Laborín, Rafael; Oceguera-Palao, Lorena

2015-01-01

To determine rates of drug resistance in new cases of pulmonary tuberculosis in a region with a high burden of the disease. New case suspects were referred for drug susceptibility testing. 28.9% of new cases were resistant to at least one first line drug; 3.9% had a multidrug-resistant strain, 15.6% a monoresistant strain and 9.4% a polyresistant strain. Our rate of drug resistant tuberculosis in new cases is very high; this has important clinical implications, since even monoresistance can have a negative impact on the outcome of new cases treated empirically with a six month regimen.

LLL transient-electromagnetics-measurement facility

International Nuclear Information System (INIS)

Deadrick, F.J.; Miller, E.K.; Hudson, H.G.

1975-01-01

The operation and hardware of the Lawrence Livermore Laboratory's transient-electromagnetics (EM)-measurement facility are described. The transient-EM range is useful for determining the time-domain transient responses of structures to incident EM pulses. To illustrate the accuracy and utility of the EM-measurement facility, actual experimental measurements are compared to numerically computed values

Damage behavior of REE-doped W-based material exposed to high-flux transient heat loads

International Nuclear Information System (INIS)

Shi, Jing; Luo, Lai–Ma; Lin, Jin–shan; Zan, Xiang; Zhu, Xiao–yong; Xu, Qiu; Wu, Yu–Cheng

2016-01-01

Pure W and W-Lu alloys were prepared by mechanical alloying (MA) and spark plasma sintering (SPS) technology. The performance and relevant damage mechanism of W-(0%, 2%, 5%, 10%) Lu alloys under transient heat loads were investigated using a laser beam heat load test to simulate the transient events in future nuclear fusion reactors. Scanning electron microscopy was used to observe the morphologies of the damaged surfaces and energy dispersive X-ray spectroscopy was used to conduct composition analysis. Damages to the surface such as cracks, pits, melting layers, Lu-rich droplets, and thermal ablation were observed. A mass of dense fuzz-like nanoparticles formed on the outer region of the laser-exposed area. Recrystallization, grain growth, increased surface roughness, and material erosion were also observed. W-Lu samples with low Lu content demonstrated better thermal performance than pure W, and the degree of damage significantly deteriorated under repetitive transient heat loads.

Characterization of transient groundwater flow through a high arch dam foundation during reservoir impounding

Directory of Open Access Journals (Sweden)

Yifeng Chen

2016-08-01

Full Text Available Even though a large number of large-scale arch dams with height larger than 200 m have been built in the world, the transient groundwater flow behaviors and the seepage control effects in the dam foundations under difficult geological conditions are rarely reported. This paper presents a case study on the transient groundwater flow behaviors in the rock foundation of Jinping I double-curvature arch dam, the world's highest dam of this type to date that has been completed. Taking into account the geological settings at the site, an inverse modeling technique utilizing the time series measurements of both hydraulic head and discharge was adopted to back-calculate the permeability of the foundation rocks, which effectively improves the uniqueness and reliability of the inverse modeling results. The transient seepage flow in the dam foundation during the reservoir impounding was then modeled with a parabolic variational inequality (PVI method. The distribution of pore water pressure, the amount of leakage, and the performance of the seepage control system in the dam foundation during the entire impounding process were finally illustrated with the numerical results.

Effect of transmitter turn-off time on transient soundings

Science.gov (United States)

Fitterman, D.V.; Anderson, W.L.

1987-01-01

A general procedure for computing the effect of non-zero turn-off time on the transient electromagnetic response is presented which can be applied to forward and inverse calculation methods for any transmitter-receiver configuration. We consider in detail the case of a large transmitter loop which has a receiver coil located at the center of the loop (central induction or in-loop array). For a linear turn-off ramp of width t0, the voltage response is shown to be the voltage due to an ideal step turn-off averaged over windows of width t0. Thus the effect is similar to that obtained by using averaging windows in the receiver. In general when time zero is taken to be the end of the ramp, the apparent resistivity increases for a homogeneous half-space over a limited time range. For time zero taken to be the start of the ramp the apparent resistivity is affected in the opposite direction. The effect of the ramp increases with increasing t0 and first-layer resistivity, is largest during the intermediate stage, and decreases with increasing time. It is shown that for a ramp turn-off, there is no effect in the early and late stages. For two-layered models with a resistive first layer (??1>??2), the apparent resistivity is increased in the intermediate stage. When the first layer is more conductive than the second layer (??1interpretation as shown by field examples; the influence is the greatest on near-surface layer parameters. ?? 1987.

Transient coupled calculations of the Molten Salt Fast Reactor using the Transient Fission Matrix approach

Energy Technology Data Exchange (ETDEWEB)

Laureau, A., E-mail: laureau.axel@gmail.com; Heuer, D.; Merle-Lucotte, E.; Rubiolo, P.R.; Allibert, M.; Aufiero, M.

2017-05-15

Highlights: • Neutronic ‘Transient Fission Matrix’ approach coupled to the CFD OpenFOAM code. • Fission Matrix interpolation model for fast spectrum homogeneous reactors. • Application for coupled calculations of the Molten Salt Fast Reactor. • Load following, over-cooling and reactivity insertion transient studies. • Validation of the reactor intrinsic stability for normal and accidental transients. - Abstract: In this paper we present transient studies of the Molten Salt Fast Reactor (MSFR). This generation IV reactor is characterized by a liquid fuel circulating in the core cavity, requiring specific simulation tools. An innovative neutronic approach called “Transient Fission Matrix” is used to perform spatial kinetic calculations with a reduced computational cost through a pre-calculation of the Monte Carlo spatial and temporal response of the system. Coupled to this neutronic approach, the Computational Fluid Dynamics code OpenFOAM is used to model the complex flow pattern in the core. An accurate interpolation model developed to take into account the thermal hydraulics feedback on the neutronics including reactivity and neutron flux variation is presented. Finally different transient studies of the reactor in normal and accidental operating conditions are detailed such as reactivity insertion and load following capacities. The results of these studies illustrate the excellent behavior of the MSFR during such transients.

Transient coupled calculations of the Molten Salt Fast Reactor using the Transient Fission Matrix approach

International Nuclear Information System (INIS)

Laureau, A.; Heuer, D.; Merle-Lucotte, E.; Rubiolo, P.R.; Allibert, M.; Aufiero, M.

2017-01-01

Highlights: • Neutronic ‘Transient Fission Matrix’ approach coupled to the CFD OpenFOAM code. • Fission Matrix interpolation model for fast spectrum homogeneous reactors. • Application for coupled calculations of the Molten Salt Fast Reactor. • Load following, over-cooling and reactivity insertion transient studies. • Validation of the reactor intrinsic stability for normal and accidental transients. - Abstract: In this paper we present transient studies of the Molten Salt Fast Reactor (MSFR). This generation IV reactor is characterized by a liquid fuel circulating in the core cavity, requiring specific simulation tools. An innovative neutronic approach called “Transient Fission Matrix” is used to perform spatial kinetic calculations with a reduced computational cost through a pre-calculation of the Monte Carlo spatial and temporal response of the system. Coupled to this neutronic approach, the Computational Fluid Dynamics code OpenFOAM is used to model the complex flow pattern in the core. An accurate interpolation model developed to take into account the thermal hydraulics feedback on the neutronics including reactivity and neutron flux variation is presented. Finally different transient studies of the reactor in normal and accidental operating conditions are detailed such as reactivity insertion and load following capacities. The results of these studies illustrate the excellent behavior of the MSFR during such transients.

Characterization of active CMOS pixel sensors on high resistive substrate

Energy Technology Data Exchange (ETDEWEB)

Hirono, Toko; Hemperek, Tomasz; Huegging, Fabian; Krueger, Hans; Rymaszewski, Piotr; Wermes, Norbert [Physikalisches Institut, Universitaet Bonn, Bonn (Germany)

2016-07-01

Active CMOS pixel sensors are very attractive as radiation imaging pixel detector because they do not need cost-intensive fine pitch bump bonding. High radiation tolerance and time resolution are required to apply those sensors to upcoming particle physics experiments. To achieve these requirements, the active CMOS pixel sensors were developed on high resistive substrates. Signal charges are collected faster by drift in high resistive substrates than in standard low resistive substrates yielding also a higher radiation tolerance. A prototype of the active CMOS pixel sensor has been fabricated in the LFoundry 150 nm CMOS process on 2 kΩcm substrate. This prototype chip was thinned down to 300 μm and the backside has been processed and can contacted by an aluminum contact. The breakdown voltage is around -115 V, and the depletion width has been measured to be as large as 180 μm at a bias voltage of -110 V. Gain and noise of the readout circuitry agree with the designed values. Performance tests in the lab and test beam have been done before and after irradiation with X-rays and neutrons. In this presentation, the measurement results of the active CMOS prototype sensors are shown.

30 CFR 75.803 - Fail safe ground check circuits on high-voltage resistance grounded systems.

Science.gov (United States)

2010-07-01

... High-Voltage Distribution § 75.803 Fail safe ground check circuits on high-voltage resistance grounded systems. [Statutory Provisions] On and after September 30, 1970, high-voltage, resistance grounded systems... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fail safe ground check circuits on high-voltage...

Tailoring Cytotoxicity of Antimicrobial Peptidomimetics with High Activity against Multidrug-Resistant Escherichia coli

DEFF Research Database (Denmark)

Jahnsen, Rasmus D; Sandberg-Schaal, Anne; Vissing, Karina Juul

2014-01-01

Infections with multidrug-resistant pathogens are an increasing concern for public health. Recently, subtypes of peptide-peptoid hybrids were demonstrated to display potent activity against multidrug-resistant Gram-negative bacteria. Here, structural variation of these antibacterial peptidomimetics...... cells. Thus, lead compounds with a high selectivity toward killing of clinically important multidrug-resistant E. coli were identified....

Experimental verification of transient nonlinear acoustical holography.

Science.gov (United States)

Jing, Yun; Cannata, Jonathan; Wang, Tianren

2013-05-01

This paper presents an experimental study on nonlinear transient acoustical holography. The validity and effectiveness of a recently proposed nonlinear transient acoustical holography algorithm is evaluated in the presence of noise. The acoustic field measured on a post-focal plane of a high-intensity focused transducer is backward projected to reconstruct the pressure distributions on the focal and a pre-focal plane, which are shown to be in good agreement with the measurement. In contrast, the conventional linear holography produces erroneous results in this case where the nonlinearity involved is strong. Forward acoustic field projection was also carried out to further verify the algorithm.

Development of High Temperature/High Sensitivity Novel Chemical Resistive Sensor

Energy Technology Data Exchange (ETDEWEB)

Ma, Chunrui [Univ. of Texas, San Antonio, TX (United States); Enriquez, Erik [Univ. of Texas, San Antonio, TX (United States); Wang, Haibing [Univ. of Texas, San Antonio, TX (United States); Xu, Xing [Univ. of Texas, San Antonio, TX (United States); Bao, Shangyong [Univ. of Texas, San Antonio, TX (United States); Collins, Gregory [Univ. of Texas, San Antonio, TX (United States)

2013-08-13

The research has been focused to design, fabricate, and develop high temperature/high sensitivity novel multifunctional chemical sensors for the selective detection of fossil energy gases used in power and fuel systems. By systematically studying the physical properties of the LnBaCo₂O_5+d (LBCO) [Ln=Pr or La] thin-films, a new concept chemical sensor based high temperature chemical resistant change has been developed for the application for the next generation highly efficient and near zero emission power generation technologies. We also discovered that the superfast chemical dynamic behavior and an ultrafast surface exchange kinetics in the highly epitaxial LBCO thin films. Furthermore, our research indicates that hydrogen can superfast diffuse in the ordered oxygen vacancy structures in the highly epitaxial LBCO thin films, which suggest that the LBCO thin film not only can be an excellent candidate for the fabrication of high temperature ultra sensitive chemical sensors and control systems for power and fuel monitoring systems, but also can be an excellent candidate for the low temperature solid oxide fuel cell anode and cathode materials.

Psilocybin with psychological support for treatment-resistant depression: an open-label feasibility study.

Science.gov (United States)

Carhart-Harris, Robin L; Bolstridge, Mark; Rucker, James; Day, Camilla M J; Erritzoe, David; Kaelen, Mendel; Bloomfield, Michael; Rickard, James A; Forbes, Ben; Feilding, Amanda; Taylor, David; Pilling, Steve; Curran, Valerie H; Nutt, David J

2016-07-01

Psilocybin is a serotonin receptor agonist that occurs naturally in some mushroom species. Recent studies have assessed the therapeutic potential of psilocybin for various conditions, including end-of-life anxiety, obsessive-compulsive disorder, and smoking and alcohol dependence, with promising preliminary results. Here, we aimed to investigate the feasibility, safety, and efficacy of psilocybin in patients with unipolar treatment-resistant depression. In this open-label feasibility trial, 12 patients (six men, six women) with moderate-to-severe, unipolar, treatment-resistant major depression received two oral doses of psilocybin (10 mg and 25 mg, 7 days apart) in a supportive setting. There was no control group. Psychological support was provided before, during, and after each session. The primary outcome measure for feasibility was patient-reported intensity of psilocybin's effects. Patients were monitored for adverse reactions during the dosing sessions and subsequent clinic and remote follow-up. Depressive symptoms were assessed with standard assessments from 1 week to 3 months after treatment, with the 16-item Quick Inventory of Depressive Symptoms (QIDS) serving as the primary efficacy outcome. This trial is registered with ISRCTN, number ISRCTN14426797. Psilocybin's acute psychedelic effects typically became detectable 30-60 min after dosing, peaked 2-3 h after dosing, and subsided to negligible levels at least 6 h after dosing. Mean self-rated intensity (on a 0-1 scale) was 0·51 (SD 0·36) for the low-dose session and 0·75 (SD 0·27) for the high-dose session. Psilocybin was well tolerated by all of the patients, and no serious or unexpected adverse events occurred. The adverse reactions we noted were transient anxiety during drug onset (all patients), transient confusion or thought disorder (nine patients), mild and transient nausea (four patients), and transient headache (four patients). Relative to baseline, depressive symptoms were markedly reduced 1

Application of transient analysis methodology to heat exchanger performance monitoring

International Nuclear Information System (INIS)

Rampall, I.; Soler, A.I.; Singh, K.P.; Scott, B.H.

1994-01-01

A transient testing technique is developed to evaluate the thermal performance of industrial scale heat exchangers. A Galerkin-based numerical method with a choice of spectral basis elements to account for spatial temperature variations in heat exchangers is developed to solve the transient heat exchanger model equations. Testing a heat exchanger in the transient state may be the only viable alternative where conventional steady state testing procedures are impossible or infeasible. For example, this methodology is particularly suited to the determination of fouling levels in component cooling water system heat exchangers in nuclear power plants. The heat load on these so-called component coolers under steady state conditions is too small to permit meaningful testing. An adequate heat load develops immediately after a reactor shutdown when the exchanger inlet temperatures are highly time-dependent. The application of the analysis methodology is illustrated herein with reference to an in-situ transient testing carried out at a nuclear power plant. The method, however, is applicable to any transient testing application

Cerebrospinal fluid (CSF) transient responses induced by hypercapnia

International Nuclear Information System (INIS)

Fisher, M.J.

1984-01-01

CSF transient responses to CO 2 inhalation were measured before and after facilitated perfusate flow through subarachnoid spaces of anesthetized cats during ventriculocisternal perfusion with artificial CSF containing 14 C-dextran. Convective mixing of perfusate in subarachnoid spaces was augmented while infusion constant, either by impeding cisternal efflux of perfusate by raising the cisternal outflow cannula (high CSF pressure), or by preventing CSF outflow by clamping the cisternal outflow cannula (stopflow; S-F). CSF transients were also measured before and after systemic administration of phenoxybenzamine (PBZ) in order to evaluate the contribution of sympatho-adrenergic activity to craniospinal CSF redistribution and mixing. Results from high CSF pressure and S-F experiments indicate that unequilibrated CSF contributes significantly to the reduced tracer concentration in CSF volume (Vd) since SCF effluent tracer concentration (Cd) was decreased after subarachnoid facilitated flow. Further, results from S-F studies indicate that at least 50% of Cd is due to craniospinal fluid redistribution, a process which, along with CSF outflow transients, was unaffected by PBZ. Conversely, PBZ administration decreased steady state SCF formation and absorption through alpha-mediated cerebrovascular responses and/or through beta-adrenoceptor inhibition of metabolism of CSF secretory epithelium

Halogen effect for improving high temperature oxidation resistance of Ti-50Al by anodization

Science.gov (United States)

Mo, Min-Hua; Wu, Lian-Kui; Cao, Hua-Zhen; Lin, Jun-Pin; Zheng, Guo-Qu

2017-06-01

The high temperature oxidation resistance of Ti-50Al was significantly improved via halogen effect which was achieved by anodizing in an ethylene glycol solution containing with fluorine ion. The anodized Ti-50Al with holes and micro-cracks could be self-repaired during oxidation at 1000 °C. The thickness of the oxide scale increases with the prolonging of oxidation time. On the basis of halogen effect for improving the high temperature oxidation resistance of Ti-50Al by anodization, only fluorine addition into the electrolyte can effectively improve the high temperature oxidation resistance of Ti-50Al.

Monitoring of high temperature zone by resistivity tomography during in-situ heater test in sedimentary soft rocks

International Nuclear Information System (INIS)

Kubota, Kenji; Suzuki, Koichi; Ikenoya, Takafumi; Takakura, Nozomu; Tani, Kazuo

2008-01-01

In-situ heater test has been conducted to evaluate the influence of high temperature in an underground facility at a depth of 50 m. Resistivity monitoring is thought to be effective to map the extent of the high temperature zone. So we have conducted resistivity tomography during the heater test. As a result, low resistivity zone was appeared near the heated area as starting the heating, and the zone was expanded. Resistivity of rock is proportional to resistivity of pore water. It is known that pore water resistivity decreases as the temperature rise. This suggests that high temperature zone is detected and spatial distribution of temperature can be mapped by resistivity tomography. (author)

Effects of high-intensity interval cycling performed after resistance training on muscle strength and hypertrophy.

Science.gov (United States)

Tsitkanou, S; Spengos, K; Stasinaki, A-N; Zaras, N; Bogdanis, G; Papadimas, G; Terzis, G

2017-11-01

Aim of the study was to investigate whether high-intensity interval cycling performed immediately after resistance training would inhibit muscle strength increase and hypertrophy expected from resistance training per se. Twenty-two young men were assigned into either resistance training (RE; N = 11) or resistance training plus high-intensity interval cycling (REC; N = 11). Lower body muscle strength and rate of force development (RFD), quadriceps cross-sectional area (CSA) and vastus lateralis muscle architecture, muscle fiber type composition and capillarization, and estimated aerobic capacity were evaluated before and after 8 weeks of training (2 times per week). Muscle strength and quadriceps CSA were significantly and similarly increased after both interventions. Fiber CSA increased significantly and similarly after both RE (type I: 13.6 ± 3.7%, type IIA: 17.6 ± 4.4%, type IIX: 23.2 ± 5.7%, P high-intensity interval cycling performed after heavy-resistance exercise may not inhibit resistance exercise-induced muscle strength/hypertrophy after 2 months of training, while it prompts aerobic capacity and muscle capillarization. The addition of high-intensity cycling after heavy-resistance exercise may decrease RFD partly due to muscle architectural changes. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Breeding of new variety Yangfumai 4 with high resistance to wheat yellow mosaic disease

International Nuclear Information System (INIS)

He Zhentian; Chen Xiulan; Zhang Rong; Wang Jianhua; Wang Jinrong; Liu Jian

2011-01-01

To control the infection of wheat yellow mosaic disease,new wheat variety with high-yield, disease-resistant was selected. Ningmai 9, which carries yellow mosaic disease resistant genes, was used as original material. Combination of conventional breeding technique and radiation methods, a new wheat variety Yangfumai 4 was developed during 1996-2007, and registered in 2008. The new wheat variety with high yield and resistance to yellow mosaic disease is suitable to plant in the Yangtze River region. (authors)

Investigation of Thermal Interface Materials Using Phase-Sensitive Transient Thermoreflectance Technique: Preprint

Energy Technology Data Exchange (ETDEWEB)

Feng, X.; King, C.; DeVoto, D.; Mihalic, M.; Narumanchi, S.

2014-08-01

With increasing power density in electronics packages/modules, thermal resistances at multiple interfaces are a bottleneck to efficient heat removal from the package. In this work, the performance of thermal interface materials such as grease, thermoplastic adhesives and diffusion-bonded interfaces are characterized using the phase-sensitive transient thermoreflectance technique. A multi-layer heat conduction model was constructed and theoretical solutions were derived to obtain the relation between phase lag and the thermal/physical properties. This technique enables simultaneous extraction of the contact resistance and bulk thermal conductivity of the TIMs. With the measurements, the bulk thermal conductivity of Dow TC-5022 thermal grease (70 to 75 um bondline thickness) was 3 to 5 W/(m-K) and the contact resistance was 5 to 10 mm2-K/W. For the Btech thermoplastic material (45 to 80 μm bondline thickness), the bulk thermal conductivity was 20 to 50 W/(m-K) and the contact resistance was 2 to 5 mm2-K/W. Measurements were also conducted to quantify the thermal performance of diffusion-bonded interface for power electronics applications. Results with the diffusion-bonded sample showed that the interfacial thermal resistance is more than one order of magnitude lower than those of traditional TIMs, suggesting potential pathways to efficient thermal management.

Experimental study on transient boiling heat transfer

International Nuclear Information System (INIS)

Visentini, R.

2012-01-01

Boiling phenomena can be found in the everyday life, thus a lot of studies are devoted to them, especially in steady state conditions. Transient boiling is less known but still interesting as it is involved in the nuclear safety prevention. In this context, the present work was supported by the French Institute of Nuclear Safety (IRSN). In fact, the IRSN wanted to clarify what happens during a Reactivity-initiated Accident (RIA). This accident occurs when the bars that control the nuclear reactions break down and a high power peak is passed from the nuclear fuel bar to the surrounding fluid. The temperature of the nuclear fuel bar wall increases and the fluid vaporises instantaneously. Previous studies on a fuel bar or on a metal tube heated by Joule effect were done in the past in order to understand the rapid boiling phenomena during a RIA. However, the measurements were not really accurate because the measurement techniques were not able to follow rapid phenomena. The main goal of this work was to create an experimental facility able to simulate the RIA boiling conditions but at small scale in order to better understand the boiling characteristics when the heated-wall temperature increases rapidly. Moreover, the experimental set-up was meant to be able to produce less-rapid transients as well, in order to give information on transient boiling in general. The facility was built at the Fluid-Mechanics Institute of Toulouse. The core consists of a metal half-cylinder heated by Joule effect, placed in a half-annulus section. The inner half cylinder is made of a 50 microns thick stainless steel foil. Its diameter is 8 mm, and its length 200 mm. The outer part is a 34 mm internal diameter glass half cylinder. The semi-annular section is filled with a coolant, named HFE7000. The configuration allows to work in similarity conditions. The heated part can be place inside a loop in order to study the flow effect. The fluid temperature influence is taken into account as

MHD aspects of coronal transients

International Nuclear Information System (INIS)

Anzer, U.

1979-10-01

If one defines coronal transients as events which occur in the solar corona on rapid time scales (< approx. several hours) then one would have to include a large variety of solar phenomena: flares, sprays, erupting prominences, X-ray transients, white light transients, etc. Here we shall focus our attention on the latter two phenomena. (orig.) 891 WL/orig. 892 RDG

The high temperature resistivity of Ba2YCu3O7-chi

International Nuclear Information System (INIS)

Xingkui, Z.; Shining, Z.; Hao, W.; Shiyuan, Z.; Ningshen, Z.; Ziran, X.

1988-01-01

The high temperature resistivity (rho), thermogravimetry (TG) and derivative thermogravimetric (DTG) have been used to characterize superconductor Ba 2 YCu 3 O 7-chi (BYCO) in O 2 , air and N 2 . The resistivity is linear from room temperature at 350 0 C and then deviate from linearity with oxygen evolution, the derivative of resistivity drho/dT increases abruptly near orthorhombic to tetragonal phase transition. These phenomena can give good explanations for a two-band Drude model

The High Temperature Resistivity of Ba2YCu3O7-x

Science.gov (United States)

Xingkui, Zhang; Shining, Zhu; Hao, Wang; Shiyuan, Zhang; Su, Ye; Ningshen, Zhou; Ziran, Xu

The high temperature resistivity (ρ), thermogravimetry (TG) and derivative thermogravimetry (DTG) have been used to characterize superconductor Ba2YCu3O7-x (BYCO) in O2, air and N2. The resistivity is linear from room temperature to 350°C and then deviate from linearity with oxygen evolution, the derivative of resistivity dρ/dT increases abruptly near orthorhombic to tetragonal phase transition. These phenomena can give good explanations for a two-band Drude model.

A discussion of the eccentric binary hypothesis for transient X-ray sources

International Nuclear Information System (INIS)

Avni, Y.; Goldman, I.

1979-01-01

The eccentric binary hypothesis for transient x-ray sources in the framework of the gradual acceleration stellar wind model proposed by Barlow and Cohen is examined. It is found that a consideration of the ratio of maximum to minimum luminosities and of the ratio of the durations of the high and low states, for a typical transient x-ray source, yields a rather high eccentricity, despite the gradual acceleration of the wind. When typical physical parameters for the binary members are taken into account, we find that a consistent description is possible only for very eccentric orbits (e>=0.9), thus the model is inadequate as a general explanation of the x-ray transient phenomenon. The recurrent transient x-ray source 4U 1630-47, which was considered in ihe past to be a realization of the eccentric binary model is studied and it is demonstrated that it cannot be described consistently within the framework of the model, unless the optical primary is very peculiar. (author)

Behavior of mixed-oxide fuel elements during the TOPI-1E transient overpower test

International Nuclear Information System (INIS)

Tsai, H.; Neimark, L.A.; Yamamoto, K.; Hirai, K.; Shikakura, S.

1993-12-01

A slow-ramp, extended overpower transient test was conducted on a group of nineteen preirradiated mixed-oxide fuel elements in EBR-II. During the transient two of the test elements with high-density fuel and tempered martensitic cladding (PNC-FMS) breached at an overpower of ∼75%. Fuel elements with austenitic claddings (D9, PNC316, and PNC150), many with aggressive design features and high burnups, survived the overpower transient and incurred little or no cladding strain. Fuel elements with annual fuel or heterogeneous fuel columns also behaved well

Primary drug resistance in a region with high burden of tuberculosis. A critical problem

Directory of Open Access Journals (Sweden)

Cecilia Villa-Rosas

2015-03-01

Full Text Available Objective. To determine rates of drug resistance in new cases of pulmonary tuberculosis in a region with a high burden of the disease. Materials and methods. New case suspects were referred for drug susceptibility testing. Results. 28.9% of new cases were resistant to at least one first line drug; 3.9% had a multidrug-resistant strain, 15.6% a monoresistant strain and 9.4% a polyresistant strain. Conclusion. Our rate of drug resistant tuberculosis in new cases is very high; this has important clinical implications, since even monoresistance can have a negative impact on the outcome of new cases treated empirically with a six month regimen.

Minimum depth of investigation for grounded-wire TEM due to self-transients

Science.gov (United States)

Zhou, Nannan; Xue, Guoqiang

2018-05-01

The grounded-wire transient electromagnetic method (TEM) has been widely used for near-surface metalliferous prospecting, oil and gas exploration, and hydrogeological surveying in the subsurface. However, it is commonly observed that such TEM signal is contaminated by the self-transient process occurred at the early stage of data acquisition. Correspondingly, there exists a minimum depth of investigation, above which the observed signal is not applicable for reliable data processing and interpretation. Therefore, for achieving a more comprehensive understanding of the TEM method, it is necessary to perform research on the self-transient process and moreover develop an approach for quantifying the minimum detection depth. In this paper, we first analyze the temporal procedure of the equivalent circuit of the TEM method and present a theoretical equation for estimating the self-induction voltage based on the inductor of the transmitting wire. Then, numerical modeling is applied for building the relationship between the minimum depth of investigation and various properties, including resistivity of the earth, offset, and source length. It is guide for the design of survey parameters when the grounded-wire TEM is applied to the shallow detection. Finally, it is verified through applications to a coal field in China.

Validation of criteria for the definition of transient lower esophageal sphincter relaxations using high-resolution manometry.

Science.gov (United States)

Roman, S; Holloway, R; Keller, J; Herbella, F; Zerbib, F; Xiao, Y; Bernard, L; Bredenoord, A J; Bruley des Varannes, S; Chen, M; Fox, M; Kahrilas, P J; Mittal, R K; Penagini, R; Savarino, E; Sifrim, D; Wu, J; Decullier, E; Pandolfino, J E; Mion, F

2017-02-01

Criteria for transient lower esophageal sphincter relaxations (TLESRs) are well-defined for Dentsleeve manometry. As high-resolution manometry (HRM) is now the gold standard to assess esophageal motility, our aim was to propose a consensus definition of TLESRs using HRM. Postprandial esophageal HRM combined with impedance was performed in 10 patients with gastroesophageal reflux disease. Transient lower esophageal sphincter relaxations identification was performed by 17 experts using a Delphi process. Four investigators then characterized TLESR candidates that achieved 100% agreement (TLESR events) and those that achieved less than 25% agreement (non-events) after the third round. Logistic regression and decision tree analysis were used to define optimal diagnostic criteria. All diagnostic criteria were more frequently encountered in the 57 TLESR events than in the 52 non-events. Crural diaphragm (CD) inhibition and LES relaxation duration >10 seconds had the highest predictive value to identify TLESR. Based on decision tree analysis, reflux on impedance, esophageal shortening, common cavity, upper esophageal sphincter relaxation without swallow and secondary peristalsis were alternate diagnostic criteria. Using HRM, TLESR might be defined as LES relaxation occurring in absence of swallowing, lasting more than 10 seconds and associated with CD inhibition. © 2016 John Wiley & Sons Ltd.

Transient Mass and Thermal Transport during Methane Adsorption into the Metal-Organic Framework HKUST-1.

Science.gov (United States)

Babaei, Hasan; McGaughey, Alan J H; Wilmer, Christopher E

2018-01-24

Methane adsorption into the metal-organic framework (MOF) HKUST-1 and the resulting heat generation and dissipation are investigated using molecular dynamics simulations. Transient simulations reveal that thermal transport in the MOF occurs two orders of magnitude faster than gas diffusion. A large thermal resistance at the MOF-gas interface (equivalent to 127 nm of bulk HKUST-1), however, prevents fast release of the generated heat. The mass transport resistance at the MOF-gas interface is equivalent to 1 nm of bulk HKUST-1 and does not present a bottleneck in the adsorption process. These results provide important insights into the application of MOFs for gas storage applications.

Thyroid Stimulating Hormone Resistance Syndrome – A Case Report

Directory of Open Access Journals (Sweden)

SM Ashrafuzzaman

2014-01-01

Full Text Available Resistance to thyrotropin or thyroid stimulating hormone (RTSH can be defined as decreased responsiveness to thyroid stimulating hormone (TSH characterized by high TSH with normal but occasionally low T4 and T3 usually in absence of goiter or ectopic thyroid. It can be diagnosed when TSH is >30 mIU/L but free T4 (FT4 is within normal limit. Patient usually presents in euthyroid state with abnormally high TSH but may also present with mild to overt hypothyroidism. The precise prevalence is not known, but 20-30% infants may show transient mild RTSH. In adults it is rare. Here we report a case of RTSH in which a 19 years old young girl presented in euthyroid state with mild goiter. Ibrahim Med. Coll. J. 2014; 8(1: 32-33

Nonuniformities of electrical resistivity in undoped 6H-SiC wafers

International Nuclear Information System (INIS)

Li, Q.; Polyakov, A.Y.; Skowronski, M.; Sanchez, E.K.; Loboda, M.J.; Fanton, M.A.; Bogart, T.; Gamble, R.D.

2005-01-01

Chemical elemental analysis, temperature-dependent Hall measurements, deep-level transient spectroscopy, and contactless resistivity mapping were performed on undoped semi-insulating (SI) and lightly nitrogen-doped conducting 6H-SiC crystals grown by physical vapor transport (PVT). Resistivity maps of commercial semi-insulating SiC wafers revealed resistivity variations across the wafers between one and two orders of magnitude. Two major types of variations were identified. First is the U-shape distribution with low resistivity in the center and high in the periphery of the wafer. The second type had an inverted U-shape distribution. Secondary-ion-mass spectrometry measurements of the distribution of nitrogen concentration along the growth axis and across the wafers sliced from different locations of lightly nitrogen-doped 6H-SiC boules were conducted. The measured nitrogen concentration gradually decreased along the growth direction and from the center to the periphery of the wafers. This change gives rise to the U-like distribution of resistivity in wafers of undoped SI-SiC. The concentrations of deep electron traps exhibited similar dependence. Compensation of nitrogen donors by these traps can result in the inverted U-like distribution of resistivity. Possible reasons for the observed nonuniformities include formation of a (0001) facet in PVT growth coupled with orientation-dependent nitrogen incorporation, systematic changes of the gas phase composition, and increase of the deposition temperature during boule growth

The effects of varying resistance-training loads on intermediate- and high-velocity-specific adaptations.

Science.gov (United States)

Jones, K; Bishop, P; Hunter, G; Fleisig, G

2001-08-01

The purpose of this study was to compare changes in velocity-specific adaptations in moderately resistance-trained athletes who trained with either low or high resistances. The study used tests of sport-specific skills across an intermediate- to high-velocity spectrum. Thirty NCAA Division I baseball players were randomly assigned to either a low-resistance (40-60% 1 repetition maximum [1RM]) training group or a high-resistance (70-90% 1RM) training group. Both of the training groups intended to maximallv accelerate each repetition during the concentric phase (IMCA). The 10 weeks of training consisted of 4 training sessions a week using basic core exercises. Peak force, velocity, and power were evaluated during set angle and depth jumps as well as weighted jumps using 30 and 50% 1RM. Squat 1RMs were also tested. Although no interactions for any of the jump tests were found, trends supported the hypothesis of velocity-specific training. Percentage gains suggest that the combined use of heavier training loads (70-90% 1RM) and IMCA tend to increase peak force in the lower-body leg and hip extensors. Trends also show that the combined use of lighter training loads (40-60% 1RM) and IMCA tend to increase peak power and peak velocity in the lower-body leg and hip extensors. The high-resistance group improved squats more than the low-resistance group (p training loads and IMCA to increase 1RM strength in the lower bodies of resistance-trained athletes.

A new capacitive/resistive probe method for studying magnetic surfaces

International Nuclear Information System (INIS)

Kitajima, Sumio; Takayama, Masakazu; Zama, Tatsuya; Takaya, Kazuhiro; Takeuchi, Nobunao; Watanabe, Hiroshige

1991-01-01

A new capacitive/resistive probe method for mapping the magnetic surfaces from resistance or capacitance between a magnetic surface and a vacuum vessel was developed and tested. Those resistances and capacitances can be regarded as components of a simple electrical bridge circuit. This method exploits electrical transient response of the bridge circuit for a square pulse. From equiresistance or equicapacitance points, the magnetic surface structure can be deduced. Measurements on the Tohoku University Heliac, which is a small-size standard heliac, show good agreement with numerical calculations. This method is particularly useful for pulse-operated machines. (author)

Silent Aortic Dissection Presenting as Transient Locked-In Syndrome

Science.gov (United States)

Nadour, Wadih; Goldwasser, Brian; Biederman, Robert W.; Taffe, Kevin

2008-01-01

Acute aortic dissection is a medical emergency. Without prompt recognition and treatment, the mortality rate is high. An atypical presentation makes timely diagnosis difficult, especially if the patient is experiencing no characteristic pain. Many patients with aortic dissection are reported to have presented with various neurologic manifestations, but none with only a presentation of transient locked-in syndrome. Herein, we report a case of completely painless aortic dissection in a woman who presented with a transient episode of anarthria, quadriplegia, and preserved consciousness. On physical examination, she had a 40-point difference in blood pressure between her left and right arms, and a loud diastolic murmur. The diagnosis of acute aortic dissection was reached via a combination of radiography, computed tomography, echocardiography, and a high index of clinical suspicion. The patient underwent emergency surgery and ultimately experienced a successful outcome. To our knowledge, this is the 1st report of aortic dissection that presented solely as locked-in syndrome. We suggest that silent aortic dissection be added to the differential diagnosis for transient locked-in syndrome. PMID:18941610

Transient insomnia versus chronic insomnia: a comparison study of sleep-related psychological/behavioral characteristics.

Science.gov (United States)

Yang, Chien-Ming; Lin, Shih-Chun; Cheng, Chung-Ping

2013-10-01

Vulnerability to transient insomnia is regarded as a predisposing factor for chronic insomnia. However, most individuals with transient insomnia do not develop chronic insomnia. The current study investigated the differential contributing factors for these two conditions to further the understanding of this phenomenon. Chronic insomnia patients and normal sleepers with high and low vulnerability to transient insomnia completed measures of pre-sleep arousal, dysfunctional sleep beliefs, and sleep-related safety behaviors. Both cognitive and somatic pre-sleep arousals were identified as significant predictors for transient insomnia. Dysfunctional beliefs regarding worry about insomnia and cognitive arousal were predictors for chronic insomnia. Sleep-related safety behavior, although correlated with insomnia severity, was not a significant predictor for both conditions. Dysfunctional beliefs associated with worry and losing control over sleep are the most critical factors in differentiating chronic insomnia from transient insomnia. These factors should be addressed to help prevent individuals with high sleep vulnerability from developing chronic sleep disturbance. © 2013 Wiley Periodicals, Inc.

Separation of transient and oscillatory cerebral activities using over-complete rational dilation wavelet transforms

International Nuclear Information System (INIS)

Chaibi, S.; Lajnef, T.; Samet, M.; Kachouri, A.

2011-01-01

Many natural signals EEG are comprised frequency overlapping of oscillatory and transient components. In our study the intracranial EEG signals of epilepsy are composed of the superposition of oscillatory signals (HFOs: High Frequency oscillations) and a transient signals (spikes and sharp waves, etc.). The oscillatory components (HFOs) exist in the frequency band 80-500Hz. The transient components comes from nonrhythmic brain activities (spikes, sharp waves and vertex waves of varying amplitude, shape and duration) and cover a continuous wide bandwidth from low to high frequencies and resemble an HFOs events when filtered using a band pass classical filter. The classical filtering methods based on FIR filters, Wavelet transforms and the Matching Pursuit cannot separate the oscillatory from transient activities. This paper describes an approach for decomposing an iEEG signals of epilepsy into the sum of oscillatory components and a transient components based on overcomplete rational dilation wavelet transforms (overcomplete RADWT) in conjunction with morphological component analysis (MCA).

Mechanical modelling of transient- to- failure SFR fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Feria, F.; Herranz, L. E.

2014-07-01

The response of Sodium Fast Reactor (SFR) fuel rods to transient accident conditions is an important safety concern. During transients the cladding strain caused by the stress due to pellet cladding mechanical interaction (PCMI) can lead to failure. Due to the fact that SFR fuel rods are commonly clad with strengthened material made of stainless steel (SS), cladding is usually treated as an elastic-perfectly-plastic material. However, viscoplastic behaviour can contribute to mechanical strain at high temperature (> 1000 K). (Author)

Transient-Switch-Signal Suppressor

Science.gov (United States)

Bozeman, Richard J., Jr.

1995-01-01

Circuit delays transmission of switch-opening or switch-closing signal until after preset suppression time. Used to prevent transmission of undesired momentary switch signal. Basic mode of operation simple. Beginning of switch signal initiates timing sequence. If switch signal persists after preset suppression time, circuit transmits switch signal to external circuitry. If switch signal no longer present after suppression time, switch signal deemed transient, and circuit does not pass signal on to external circuitry, as though no transient switch signal. Suppression time preset at value large enough to allow for damping of underlying pressure wave or other mechanical transient.

Summary of transient analysis

International Nuclear Information System (INIS)

Saha, P.

1984-01-01

This chapter reviews the papers on the pressurized water reactor (PWR) and boiling water reactor (BWR) transient analyses given at the American Nuclear Society Topical Meeting on Anticipated and Abnormal Plant Transients in Light Water Reactors. Most of the papers were based on the systems calculations performed using the TRAC-PWR, RELAP5 and RETRAN codes. The status of the nuclear industry in the code applications area is discussed. It is concluded that even though comprehensive computer codes are available for plant transient analysis, there is still a need to exercise engineering judgment, simpler tools and even hand calculations to supplement these codes

Localized corrosion of high alloyed austenitic stainless steels

International Nuclear Information System (INIS)

Morach, R.; Schmuki, P.; Boehni, H.

1992-01-01

The susceptibility of several high alloyed stainless steels against localized corrosion was investigated by traditional potentiostatic and -kinetic methods and the current transient technique. Different test cells, proposed in literature, were evaluated for use in testing of plate materials. The AVESTA-cell showed to be not useful for potentiokinetic current density potential curves, but useable for pitting experiments. After pickling and prepassivation epoxy embedded materials proved to be resistant to crevice corrosion at the metal-resin interface. The electrode in form of a wire was the most reliable crevice free cell design. The grinding of the samples in the pretreatment procedure was found to have a large effect on the pitting corrosion behaviour. Using different paper types with varying grit, a drop in pitting potential for rougher surfaces and an increase in metastable pitting activity was found. Increasing surface roughness led also to changes in the electronic structure of the passive film reflected by a lower bandgap energy. High alloyed stainless steels showed no breakdown potential within the examined potential range. Compared to 18/8 type stainless steels significantly less transients were found. The number of transients decreases with increasing molybdenum and chromium content

Experience with transients in German NPPs

International Nuclear Information System (INIS)

Lindauer, E.

1984-01-01

This chapter examines reactor accidents in the Federal Republic of Germany based on the formal reporting system for licensee event reports (LERs) and a special investigation on all unplanned power variations in 3 PWRs. The significant transients experienced by BWR type reactors are analyzed. The main goal is to find weak points which caused the transient or influenced its course in an unfavorable way in order to improve the affected plant and others. The complete survey of all transients, with normally little or no safety relevance, allows statistical evaluations and the analysis of trends. It is concluded that significant transients were mainly experienced at older plants, whereas plants of an advanced design produced very few significant transients. The most frequent human errors which lead to transients are failure search in electronic systems and errors during design and commissioning

Breeding of a new potato variety 'Nagasaki Kogane' with high eating quality, high carotenoid content, and resistance to diseases and pests.

Science.gov (United States)

Sakamoto, Yu; Mori, Kazuyuki; Matsuo, Yuuki; Mukojima, Nobuhiro; Watanabe, Wataru; Sobaru, Norio; Tamiya, Seiji; Nakao, Takashi; Hayashi, Kazuya; Watanuki, Hitomi; Nara, Kazuhiro; Yamazaki, Kaoru; Chaya, Masataka

2017-06-01

'Nagasaki Kogane' is a new potato variety bred from a cross between 'Saikai 35' as a female parent and 'Saikai 33' as a male. 'Saikai 35' is resistant to bacterial wilt, contains the H1 and Ry chc genes for resistance to the potato cyst nematode (PCN) and potato virus Y (PVY), respectively, and has high carotenoid content, while 'Saikai 33' has large and high-yielding tubers and is resistant to both bacterial wilt and PCN. The carotenoid content of 'Nagasaki Kogane' is higher than that of 'Dejima', a common double cropping variety. The taste quality of steamed 'Nagasaki Kogane' is comparable to that of 'Inca-no-mezame' tubers, which has high levels of carotenoid, and superior to 'Nishiyutaka', another popular double cropping variety. 'Nagasaki Kogane' is suitable for French fries, because its tuber has high starch content. The marketable yield of 'Nagasaki Kogane' was higher than that of 'Inca-no-mezame' in spring cropping, although it was lower than that of 'Nishiyutaka' in double cropping regions. 'Nagasaki Kogane' tubers are larger on average than 'Inca-no-mezame' tubers in spring cropping. Moreover, the 'Nagasaki Kogane' variety is resistant to PCN and PVY, and exhibits a high level of resistance to bacterial wilt.

Direct observation and measurements of neutron induced deep levels responsible for N{sub eff} changes in high resistivity silicon detectors using TCT

Energy Technology Data Exchange (ETDEWEB)

Li, Z.; Li, C.J. [Brookhaven National Lab., Upton, NY (United States); Eremin, V.; Verbitskaya, E. [AN SSSR, Leningrad (Russian Federation). Fiziko-Tekhnicheskij Inst.

1996-03-01

Neutron induced deep levels responsible for changes of space charge concentration {ital N{sub eff}} in high resistivity silicon detectors have been observed directly using the transient current technique (TCT). It has been observed by TCT that the absolute value and sign of {ital N{sub eff}} experience changes due to the trapping of non- equilibrium free carriers generated near the surface (about 5 micrometers depth into the silicon) by short wavelength laser pulses in fully depleted detectors. Electron trapping causes {ital N{sub eff}} to change toward negative direction (or more acceptor-like space charges) and hole trapping causes {ital N{sub eff}} to change toward positive direction (or more donor-like space charges). The specific temperature associated with these {ital N{sub eff}} changes are those of the frozen-up temperatures for carrier emission of the corresponding deep levels. The carrier capture cross sections of various deep levels have been measured directly using different free carrier injection schemes. 10 refs., 12 figs., 3 tabs.

Experimental study and modelling of transient boiling

International Nuclear Information System (INIS)

Baudin, Nicolas

2015-01-01

A failure in the control system of the power of a nuclear reactor can lead to a Reactivity Initiated Accident in a nuclear power plant. Then, a power peak occurs in some fuel rods, high enough to lead to the coolant film boiling. It leads to an important increase of the temperature of the rod. The possible risk of the clad failure is a matter of interest for the Institut de Radioprotection et de Securite Nucleaire. The transient boiling heat transfer is not yet understood and modelled. An experimental set-up has been built at the Institut de Mecanique des Fluides de Toulouse (IMFT). Subcooled HFE-7000 flows vertically upward in a semi annulus test section. The inner half cylinder simulates the clad and is made of a stainless steel foil, heated by Joule effect. Its temperature is measured by an infrared camera, coupled with a high speed camera for the visualization of the flow topology. The whole boiling curve is studied in steady state and transient regimes: convection, onset of boiling, nucleate boiling, critical heat flux, film boiling and rewetting. The steady state heat transfers are well modelled by literature correlations. Models are suggested for the transient heat flux: the convection and nucleate boiling evolutions are self-similar during a power step. This observation allows to model more complex evolutions, as temperature ramps. The transient Hsu model well represents the onset of nucleate boiling. When the intensity of the power step increases, the film boiling begins at the same temperature but with an increasing heat flux. For power ramps, the critical heat flux decreases while the corresponding temperature increases with the heating rate. When the wall is heated, the film boiling heat transfer is higher than in steady state but it is not understood. A two-fluid model well simulates the cooling film boiling and the rewetting. (author)

Transient fuel rod behavior prediction with RODEX-3/SIERRA

Energy Technology Data Exchange (ETDEWEB)

Billaux, M R; Shann, S H; Swam, L.F. Van [Siemens Power Corp., Richland, WA (United States)

1997-08-01

This paper discusses some aspects of the fuel performance code SIERRA (SIEmens Rod Response Analysis). SIERRA, the latest version of the code RODEX-3, has been developed to improve the fuel performance prediction capabilities of the code, both at high burnup and during transient reactor conditions. The paper emphasizes the importance of the mechanical models of the cracked pellet and of the cladding, in the prediction of the transient response of the fuel rod to power changes. These models are discussed in detail. Other aspects of the modelling of high burnup effects are also presented, in particular the modelling of the rim effect and the way it affects the fuel temperature. (author). 12 refs, 5 figs.

Transient fuel rod behavior prediction with RODEX-3/SIERRA

International Nuclear Information System (INIS)

Billaux, M.R.; Shann, S.H.; Swam, L.F. Van

1997-01-01

This paper discusses some aspects of the fuel performance code SIERRA (SIEmens Rod Response Analysis). SIERRA, the latest version of the code RODEX-3, has been developed to improve the fuel performance prediction capabilities of the code, both at high burnup and during transient reactor conditions. The paper emphasizes the importance of the mechanical models of the cracked pellet and of the cladding, in the prediction of the transient response of the fuel rod to power changes. These models are discussed in detail. Other aspects of the modelling of high burnup effects are also presented, in particular the modelling of the rim effect and the way it affects the fuel temperature. (author). 12 refs, 5 figs

Nuclear power plant transients: where are we

International Nuclear Information System (INIS)

Majumdar, D.

1984-05-01

This document is in part a postconference review and summary of the American Nuclear Society sponsored Anticipated and Abnormal Plant Transients in Light Water Reactors Conference held in Jackson, Wyoming, September 26-29, 1983, and in part a reflection upon the issues of plant transients and their impact on the viability of nuclear power. This document discusses state-of-the-art knowledge, deficiencies, and future directions in the plant transients area as seen through this conference. It describes briefly what was reported in this conference, emphasizes areas where it is felt there is confidence in the nuclear industry, and also discusses where the experts did not have a consensus. Areas covered in the document include major issues in operational transients, transient management, transient events experience base, the status of the analytical tools and their capabilities, probabilistic risk assessment applications in operational transients, and human factors impact on plant transients management

High-level transient expression of recombinant protein in lettuce.

Science.gov (United States)

Joh, Lawrence D; Wroblewski, Tadeusz; Ewing, Nicholas N; VanderGheynst, Jean S

2005-09-30

Transient expression following agroinfiltration of plant tissue was investigated as a system for producing recombinant protein. As a model system, Agrobacterium tumefaciens containing the beta-glucuronidase (GUS) gene was vacuum infiltrated into lettuce leaf disks. Infiltration with a suspension of 10(9) colony forming units/mL followed by incubation for 72 h at 22 degrees C in continuous darkness produced a maximum of 0.16% GUS protein based on dry tissue or 1.1% GUS protein based on total soluble protein. This compares favorably to expression levels for commercially manufactured GUS protein from transgenic corn seeds. A. tumefaciens culture medium pH between 5.6 and 7.0 and surfactant concentrations lettuce to produce GUS protein more rapidly, but final levels did not exceed the GUS production in leaves incubated in continuous darkness after 72 h at 22 degrees C. The kinetics of GUS expression during incubation in continuous light and dark were represented well using a logistic model, with rate constants of 0.30 and 0.29/h, respectively. To semi-quantitatively measure the GUS expression in large numbers of leaf disks, a photometric enhancement of the standard histochemical staining method was developed. A linear relationship with an R2 value of 0.90 was determined between log10 (% leaf darkness) versus log10 (GUS activity). Although variability in expression level was observed, agroinfiltration appears to be a promising technology that could potentially be scaled up to produce high-value recombinant proteins in planta. Copyright 2005 Wiley Periodicals, Inc

Fission product transport and behavior during two postulated loss of flow transients in the air

International Nuclear Information System (INIS)

Adams, J.P.; Carboneau, M.L.

1991-01-01

This document discusses fission product behavior during two postulated loss-of-flow accidents (leading to high- and low-pressure core degradation, respectively) in the Advanced Test Reactor (ATR). These transients are designated ATR Transient LCPI5 (high-pressure) and LPP9 (low-pressure). Normally, transients of this nature would be easily mitigated using existing safety systems and procedures. In these analyses, failure of these safety systems was assumed so that core degradation and fission product release could be analyzed. A probabilistic risk assessment indicated that the probability of occurrence for these two transients is of the order of 10 -5 and 10 -7 per reactor year for LCP15 and LPP9, respectively

PWR systems transient analysis

International Nuclear Information System (INIS)

Kennedy, M.F.; Peeler, G.B.; Abramson, P.B.

1985-01-01

Analysis of transients in pressurized water reactor (PWR) systems involves the assessment of the response of the total plant, including primary and secondary coolant systems, steam piping and turbine (possibly including the complete feedwater train), and various control and safety systems. Transient analysis is performed as part of the plant safety analysis to insure the adequacy of the reactor design and operating procedures and to verify the applicable plant emergency guidelines. Event sequences which must be examined are developed by considering possible failures or maloperations of plant components. These vary in severity (and calculational difficulty) from a series of normal operational transients, such as minor load changes, reactor trips, valve and pump malfunctions, up to the double-ended guillotine rupture of a primary reactor coolant system pipe known as a Large Break Loss of Coolant Accident (LBLOCA). The focus of this paper is the analysis of all those transients and accidents except loss of coolant accidents

Transient osteoporosis of the hip

International Nuclear Information System (INIS)

McWalter, Patricia; Hassan Ahmed

2007-01-01

Transient osteoporosis of the hip is an uncommon cause of hip pain, mostly affecting healthy middle-aged men and also women in the third trimester of pregnancy. We present a case of transient osteoporosis of the hip in a 33-year-old non-pregnant female patient. This case highlights the importance of considering a diagnosis of transient osteoporosis of the hip in patients who present with hip pain. (author)

Diffusion barrier coatings for high temperature corrosion resistance of advanced carbon/carbon composites

International Nuclear Information System (INIS)

Singh Raman, K.S.

2000-01-01

Carbon possesses an excellent combination of mechanical and thermal properties, viz., excellent creep resistance at temperatures up to 2400 deg C in non-oxidizing environment and a low thermal expansion coefficient. These properties make carbon a potential material for very high temperature applications. However, the use of carbon materials at high temperatures is considerably restricted due to their extremely poor oxidation resistance at temperatures above 400 deg C. The obvious choice for improving high temperature oxidation resistance of such materials is a suitable diffusion barrier coating. This paper presents an overview of recent developments in advanced diffusion- and thermal-barrier coatings for ceramic composites, with particular reference to C/C composites. The paper discusses the development of multiphase and multi-component ceramic coatings, and recent investigations on the oxidation resistance of the coated C/C composites. The paper also discusses the cases of innovative engineering solutions for traditional problems with the ceramic coatings, and the scope of intelligent processing in developing coatings for the C/C composites. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

30 CFR 77.803 - Fail safe ground check circuits on high-voltage resistance grounded systems.

Science.gov (United States)

2010-07-01

... circuits on high-voltage resistance grounded systems. On and after September 30, 1971, all high-voltage... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fail safe ground check circuits on high-voltage resistance grounded systems. 77.803 Section 77.803 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...

RNAi validation of resistance genes and their interactions in the highly DDT-resistant 91-R strain of Drosophila melanogaster.

Science.gov (United States)

Gellatly, Kyle J; Yoon, Kyong Sup; Doherty, Jeffery J; Sun, Weilin; Pittendrigh, Barry R; Clark, J Marshall

2015-06-01

4,4'-dichlorodiphenyltrichloroethane (DDT) has been re-recommended by the World Health Organization for malaria mosquito control. Previous DDT use has resulted in resistance, and with continued use resistance will increase in terms of level and extent. Drosophila melanogaster is a model dipteran that has many available genetic tools, numerous studies done on insecticide resistance mechanisms, and is related to malaria mosquitoes allowing for extrapolation. The 91-R strain of D. melanogaster is highly resistant to DDT (>1500-fold), however, there is no mechanistic scheme that accounts for this level of resistance. Recently, reduced penetration, increased detoxification, and direct excretion have been identified as resistance mechanisms in the 91-R strain. Their interactions, however, remain unclear. Use of UAS-RNAi transgenic lines of D. melanogaster allowed for the targeted knockdown of genes putatively involved in DDT resistance and has validated the role of several cuticular proteins (Cyp4g1 and Lcp1), cytochrome P450 monooxygenases (Cyp6g1 and Cyp12d1), and ATP binding cassette transporters (Mdr50, Mdr65, and Mrp1) involved in DDT resistance. Further, increased sensitivity to DDT in the 91-R strain after intra-abdominal dsRNA injection for Mdr50, Mdr65, and Mrp1 was determined by a DDT contact bioassay, directly implicating these genes in DDT efflux and resistance. Copyright © 2015 Elsevier Inc. All rights reserved.

A COMETHE version with transient capability

International Nuclear Information System (INIS)

Vliet, J. van; Lebon, G.; Mathieu, P.

1980-01-01

A version of the COMETHE code is under development to simulate transient situations. This paper focuses on some aspects of the transient heat transfer models. Initially the coupling between transient heat transfer and other thermomechanical models is discussed. An estimation of the thermal characteristic times shows that the cladding temperatures are often in quasi-steady state. In order to reduce the computing time, calculations are therefore switched from a transient to a quasi-static numerical procedure as soon as such a quasi-equilibrium is detected. The temperature calculation is performed by use of the Lebon-Lambermont restricted variational principle, with piecewise polynoms as trial functions. The method has been checked by comparison with some exact results and yields good agreement for transient as well as for quasi-static situations. This method therefore provides a valuable tool for the simulation of the transient behaviour of nuclear reactor fuel rods. (orig.)

Measurement of resistance switching dynamics in copper sulfide memristor structures

Science.gov (United States)

McCreery, Kaitlin; Olson, Matthew; Teitsworth, Stephen

Resistance switching materials are the subject of current research in large part for their potential to enable novel computing devices and architectures such as resistance random access memories and neuromorphic chips. A common feature of memristive structures is the hysteretic switching between high and low resistance states which is induced by the application of a sufficiently large electric field. Here, we describe a relatively simple wet chemistry process to fabricate Cu2 S / Cu memristive structures with Cu2 S film thickness ranging up to 150 micron. In this case, resistance switching is believed to be mediated by electromigration of Cu ions from the Cu substrate into the Cu2 S film. Hysteretic current-voltage curves are measured and reveal switching voltages of about 0.8 Volts with a relatively large variance and independent of film thickness. In order to gain insight into the dynamics and variability of the switching process, we have measured the time-dependent current response to voltage pulses of varying height and duration with a time resolution of 1 ns. The transient response consists of a deterministic RC component as well as stochastically varying abrupt current steps that occur within a few microseconds of the pulse application.

Adaptation to high current using low external resistances eliminates power overshoot in microbial fuel cells

KAUST Repository

Hong, Yiying; Call, Douglas F.; Werner, Craig M.; Logan, Bruce E.

2011-01-01

. Acclimation of the high external resistance reactors for a few cycles to low external resistance (5. Ω), and therefore higher current densities, eliminated power overshoot. MFCs initially acclimated to low external resistances exhibited both higher current

The effect of retarding torque during a flow transient for Tehran Research Reactor

Energy Technology Data Exchange (ETDEWEB)

Farhadi, Kazem, E-mail: kfarhadi@aeoi.org.ir [Engineering Science Research Group, Nuclear Science Research School, Nuclear Science and Technology Research Institute, AEOI, P.O. Box 11365-3486, Tehran (Iran, Islamic Republic of)

2011-02-15

The primary cooling system of the Tehran Research Reactor (TRR) has been analysed for a possible flow transient phenomenon caused by power cut-off. All the components of the TRR primary cooling loop that offer resistance to the coolant flow are physically modelled. Differential equations of motion for the coolant in the primary piping of the TRR and for the rotating parts of the centrifugal pump are then derived. The equation of flow motion is solved simultaneously with momentum conservation equation of the rotating parts of the pump which predicts the TRR pump speed during the flow transient. Electrical and mechanical losses are measured for the TRR three-phase induction motor in order to calculate the motor retarding torque during the event. The results of the present study are compared with the other similar primary loop results. The present model shows good agreement with the existing experimental and theoretical studies.

The Pan-STARRS Survey for Transients (PSST)

Science.gov (United States)

Huber, Mark; Carter Chambers, Kenneth; Flewelling, Heather; Smartt, Stephen J.; Smith, Ken; Wright, Darryl

2015-08-01

The Pan-STARRS1 (PS1) Science Consortium finished the 3Pi survey of the whole sky north of -30 degrees between 2010-2014 in grizy (PS1 specific filters) and the PS1 telescope has been running a wide-field survey for near earth objects, funded by NASA through the NEO Observation Program. This survey takes data in a w-band (wide-band filter spanning g,r,i) in dark time, and combinations of r, i, z and y during bright time. We are now processing these data through the Pan-STARRS IPP difference imaging pipeline and recovering stationary transients. Effectively the 3Pi survey for transients that started during the PS1 Science Consortium is being continued under the new NEO optimized operations mode. The observing procedure in this case is to take a quad of exposures, typically 30-45 seconds separated by 10-20 minutes each, typically revealing high confidence transients (greater than 5-sigma) to depths of i~ 20.7, y~18.3 (AB mags). This cadence may be repeated on subsequent nights in a return pointing.Continuing the public release of the first 880 transients from the PS1 3Pi survey during the search period September 2013 - January 2014, beginning February 2015, the transient events using the data from the the Pan-STARRS NEO Science Consortium are now regularly added. These are mostly supernova candidates, but the list also contains some variable stars, AGN, and nuclear transients. The light curves are too sparsely sampled to be of standalone use, but they may be of use to the community in combining with existing data (e.g. Fraser et al. 2013, ApJ, 779, L8), constraining explosion and rise times (e.g. Nicholl et al. 2013, Nature, 502, 346) as well as many being new discoveries.For additional details visit http://star.pst.qub.ac.uk/ps1threepi/

Transients in reactors for power systems compensation

Science.gov (United States)

Abdul Hamid, Haziah

This thesis describes new models and investigations into switching transient phenomena related to the shunt reactors and the Mechanically Switched Capacitor with Damping Network (MSCDN) operations used for reactive power control in the transmission system. Shunt reactors and MSCDN are similar in that they have reactors. A shunt reactor is connected parallel to the compensated lines to absorb the leading current, whereas the MSCDN is a version of a capacitor bank designed as a C-type filter for use in the harmonic-rich environment. In this work, models have been developed and transient overvoltages due to shunt reactor deenergisation were estimated analytically using MathCad, a mathematical program. Computer simulations used the ATP/EMTP program to reproduce both single-phase and three-phase shunt reactor switching at 275 kV operational substations. The effect of the reactor switching on the circuit breaker grading capacitor was also examined by considering various switching conditions.. The main original achievement of this thesis is the clarification of failure mechanisms occurring in the air-core filter reactor due to MSCDN switching operations. The simulation of the MSCDN energisation was conducted using the ATP/EMTP program in the presence of surge arresters. The outcome of this simulation shows that extremely fast transients were established across the air-core filter reactor. This identified transient event has led to the development of a detailed air-core reactor model, which accounts for the inter-turn RLC parameters as well as the stray capacitances-to-ground. These parameters are incorporated into the transient simulation circuit, from which the current and voltage distribution across the winding were derived using electric field and equivalent circuit modelling. Analysis of the results has revealed that there are substantial dielectric stresses imposed on the winding insulation that can be attributed to a combination of three factors. (i) First, the

Thermal characterizations analysis of high-power ThinGaN cool-white light-emitting diodes

Science.gov (United States)

Raypah, Muna E.; Devarajan, Mutharasu; Ahmed, Anas A.; Sulaiman, Fauziah

2018-03-01

Analysis of thermal properties plays an important role in the thermal management of high-power (HP) lighting-emitting diodes (LEDs). Thermal resistance, thermal capacitance, and thermal time constant are essential parameters for the optimal design of the LED device and system, particularly for dynamic performance study. In this paper, thermal characterization and thermal time constant of ThinGaN HP LEDs are investigated. Three HP cool-white ThinGaN LEDs from different manufacturers are used in this study. A forward-voltage method using thermal transient tester (T3Ster) system is employed to determine the LEDs' thermal parameters at various operating conditions. The junction temperature transient response is described by a multi-exponential function model to extract thermal time constants. The transient response curve is divided into three layers and expressed by three exponential functions. Each layer is associated with a particular thermal time constant, thermal resistance, and thermal capacitance. It is found that the thermal time constant of LED package is on the order of 22 to 100 ms. Comparison between the experimental results is carried out to show the design effects on thermal performance of the LED package.

Effects of transient conditions on exhaust emissions from two non-road diesel engines

International Nuclear Information System (INIS)

Lindgren, M.; Hansson, P.-A.

2004-01-01

Growing interest in quantifying and reducing the amount of engine emissions of carbon monoxide, hydrocarbons, and nitrogen oxides loading the environment has led to increasingly tighter environmental regulations. However, current non-road emission standards are performed according to a steady-state test cycle, which does not include transient effects and thus underestimates the amount of emissions produced in real use of the engine. This study quantifies the effects of transients in engine speed and torque on the fuel consumption and emissions from two diesel engines intended for non-road mobile machinery. Fuel consumption and emissions from the engines were measured in an engine dynamometer during various transient load conditions. The results showed that during fast transients, the measured fuel consumption was up to twice as high as the corresponding steady-state load conditions. The effects of transients on emissions of nitrogen oxides were even greater, as were the effects of transient load increase with increasing transient conditions i. e. rate of change. The results showed that the effect of transients on fuel consumption and emissions were also dependent on the type of diesel injection pump and the engine equipment used. Furthermore, the results indicated that the air/fuel ratio was an important contributor to the emission formation process during transient loads. (Author)

GRB 070610: a curious galactic transient

OpenAIRE

Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Cameron, P. B.; Nakar, E.; Ofek, E. O.; Rau, A.; Soderberg, A. M.; Campana, S.; Bloom, J. S.; Perley, D. A.; Pollack, L. K.; Barthelmy, S.; Cummings, J.; Gehrels, N.

2008-01-01

GRB 070610 is a typical high-energy event with a duration of 5 s. Yet within the burst localization we detect a highly unusual X-ray and optical transient, Swift J195509.6+261406. We see high-amplitude X-ray and optical variability on very short timescales even at late times. Using near-infrared imaging assisted by a laser guide star and adaptive optics, we identified the counterpart of Swift J195509.6+261406. Late-time optical and near-infrared imaging constrain the spectral type of the coun...

Transient nuclide release through the bentonite barrier -SKB 91

International Nuclear Information System (INIS)

Bengtsson, A.; Widen, H.

1991-05-01

A study of near-field radionuclide migration is presented. The study has been performed in the context of the SKB91 study which is a comprehensive performance assessment of disposal of spent fuel. The objective of the present study has been to enable the assessment of which nuclides can be screened out because they decay to insignificant levels already in the near-field of the repository. A numerical model has been used which describes the transient transport of radionuclides through a small hole in a HLW canister imbedded in bentonite clay into a fracture in the rock outside the bentonite. Calculations for more than twenty nuclides, nuclides with both high and low solubility have been made. The effect of sorption in the bentonite backfill is included. The size of the penetration hole was assumed to be constant up to time when the calculations were terminated, 500000 year after the deposition. The mass transport rate is controlled by diffusion. The model is three dimensional. The report describes the geometry of the modelled system, the assumptions concerning the transport resistances at the boundary conditions, the handling of the source term and obtained release curves. (au)

Status of insecticide resistance in high-risk malaria provinces in Afghanistan.

Science.gov (United States)

Ahmad, Mushtaq; Buhler, Cyril; Pignatelli, Patricia; Ranson, Hilary; Nahzat, Sami Mohammad; Naseem, Mohammad; Sabawoon, Muhammad Farooq; Siddiqi, Abdul Majeed; Vink, Martijn

2016-02-18

Insecticide resistance seriously threatens the efficacy of vector control interventions in malaria endemic countries. In Afghanistan, the status of insecticide resistance is largely unknown while distribution of long-lasting insecticidal nets has intensified in recent years. The main objective of this study was thus to measure the level of resistance to four classes of insecticides in provinces with medium to high risk of malaria transmission. Adult female mosquitoes were reared from larvae successively collected in the provinces of Nangarhar, Kunar, Badakhshan, Ghazni and Laghman from August to October 2014. WHO insecticide susceptibility tests were performed with DDT (4 %), malathion (5 %), bendiocarb (0.1 %), permethrin (0.75 %) and deltamethrin (0.05 %). In addition, the presence of kdr mutations was investigated in deltamethrin resistant and susceptible Anopheles stephensi mosquitoes collected in the eastern provinces of Nangarhar and Kunar. Analyses of mortality rates revealed emerging resistance against all four classes of insecticides in the provinces located east and south of the Hindu Kush mountain range. Resistance is observed in both An. stephensi and Anopheles culicifacies, the two dominant malaria vectors in these provinces. Anopheles superpictus in the northern province of Badakhshan shows a different pattern of susceptibility with suspected resistance observed only for deltamethrin and bendiocarb. Genotype analysis of knock down resistance (kdr) mutations at the voltage-gated channel gene from An. stephensi mosquitoes shows the presence of the known resistant alleles L1014S and L1014F. However, a significant fraction of deltamethrin-resistant mosquitoes were homozygous for the 1014L wild type allele indicating that other mechanisms must be considered to account for the observed pyrethroid resistance. This study confirms the importance of monitoring insecticide resistance for the development of an integrated vector management in Afghanistan. The

Research of the transient management in TQNPC

International Nuclear Information System (INIS)

Guo Longzhang; Lin Chuanqing

2008-01-01

Transient management is the basic technical subject in nuclear power plant. Since the Third Qinshan nuclear power company (TQNPC) successful completes the commissioning in 2003, the transient management work start at the transient management item selection and the flow definition. Now TQNPC have a complete transient management system and the management flow. In the last two years, TNQPC have finished the historic transient data collection for two units, and confirmed that the plant's key systems and equipments are at safe state. The development of the transient management subject would build a reliable foundation for the plant safe operation, plant lifetime management and periodic safety review. (author)

High Radiation Resistance IMM Solar Cell

Science.gov (United States)

Pan, Noren

2015-01-01

Due to high launch costs, weight reduction is a key driver for the development of new solar cell technologies suitable for space applications. This project is developing a unique triple-junction inverted metamorphic multijunction (IMM) technology that enables the manufacture of very lightweight, low-cost InGaAsP-based multijunction solar cells. This IMM technology consists of indium (In) and phosphorous (P) solar cell active materials, which are designed to improve the radiation-resistant properties of the triple-junction solar cell while maintaining high efficiency. The intrinsic radiation hardness of InP materials makes them of great interest for building solar cells suitable for deployment in harsh radiation environments, such as medium Earth orbit and missions to the outer planets. NASA Glenn's recently developed epitaxial lift-off (ELO) process also will be applied to this new structure, which will enable the fabrication of the IMM structure without the substrate.

Transient Performance Improvement Circuit (TPIC)s for DC-DC converter applications

Science.gov (United States)

Lim, Sungkeun

Gordon Moore famously predicted the exponential increase in transistor integration and computing power that has been witnessed in recent decades [1]. In the near future, it is expected that more than one billion transistors will be integrated per chip, and advanced microprocessors will require clock speeds in excess of several GHz. The increasing number of transistors and high clock speeds will necessitate the consumption of more power. By 2014, it is expected that the maximum power consumption of the microprocessor will reach approximately 150W, and the maximum load current will be around 150A. Today's trend in power and thermal management is to reduce supply voltage as low as possible to reduce delivered power. It is anticipated that the Intel cores will operate on 0.8V of supply voltage by 2014 [2]. A significant challenge in Voltage Regulator Module (VRM) development for next generation microprocessors is to regulate the supply voltage within a certain tolerance band during high slew rate load transitions, since the required supply voltage tolerance band will be much narrower than the current requirement. If VR output impedance is maintained at a constant value from DC to high frequency, large output voltage spikes can be avoided during load cur- rent transients. Based on this, the Adaptive Voltage Position (AVP) concept was developed to achieve constant VR output impedance to improve transient response performance [3]. However, the VR output impedance can not be made constant over the entire frequency range with AVP design, because the AVP design makes the VR output impedance constant only at low frequencies. To make the output impedance constant at high frequencies, many bulk capacitors and ceramic capacitors are required. The tight supply voltage tolerance for the next generation of microprocessors during high slew rate load transitions requires fast transient response power supplies. A VRM can not follow the high slew rate load current transients, because

Development of a leak detection system using high temperature-resistant microphones

International Nuclear Information System (INIS)

Morishita, Yoshitsugu; Mochizuki, Hiroyasu; Watanabe, Kenshiu; Nakamura, Takahisa; Nakajima, Yoshiaki; Yamauchi, Tatsuya

1991-01-01

This report describes the development of a detection system of coolant leak from an inlet feeder pipe of an Advanced Thermal Reactor (ATR) with high temperature-resistant microphones. A microphone having resistance to both high temperature and high radiation dose has been developed at first. The characteristics with regard to leakage sound, attenuation of sound level in a heat insulating box for the inlet feeder pipes and background noise were clarified by laboratory experiments and measurements in the prototype ATR 'Fugen'. On the basis of these experimental findings, appropriate frequency ranges were surveyed to detect the leakage sound with a high S/N ratio under the background noise. Reliability of the system to a malfunction caused by burst-type noises observed in the plant was also investigated by statistical analyses. Finally, it was confirmed that the present method could detect a leak within a couple of seconds. (author)

IncA/C plasmids conferring high azithromycin resistance in vibrio cholerae.

Science.gov (United States)

Wang, Ruibai; Liu, Haican; Zhao, Xiuqin; Li, Jie; Wan, Kanglin

2018-01-01

Azithromycin (AZM) is a clinically important antibiotic against Vibrio cholerae, especially for inhibiting V. cholerae colonisation of the intestine and for the treatment of severe cholera in children and pregnant women. An IncA/C plasmid was isolated from two high minimum inhibitory concentration (MIC) AZM-resistant V. cholerae strains of the two mainly pathogenic serogroups (O1 and O139) isolated in China. In the 172 predicted open reading frames (ORFs), 16 genes were related to antibiotic resistance, of which 5 were well-defined genes associated with macrolide resistance. The five macrolide resistance genes distributed in two clusters, mphR-mrx-mph(K) and mel-mph2, flanked by insertion sequence elements and involving two kinds of resistance mechanism. Deletion of the complete region of the two clusters deceased the AZM MIC from ≥64 µg/mL to ≤0.5 µg/mL. This IncA/C plasmid shows great ability to accumulate antibiotic resistance genes. In addition to 11 resistance genes to other antibiotics, 5 macrolide resistance genes with different function were gathered repeatedly through transposition on one plasmid. This genotype could not be simply explained by antibiotic stress applied on the host from the environment or treatment. These phosphorylases and transmembrane transporters might be involved in the transport and metabolism of other non-antibiotic substances, enabling this kind of plasmid to propagate better in the host. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

The High-Temperature Resistance Properties of Polysiloxane/Al Coatings with Low Infrared Emissivity

Directory of Open Access Journals (Sweden)

Jun Zhao

2018-03-01

Full Text Available High-temperature-resistant coatings with low infrared emissivity were prepared using polysiloxane resin and flake aluminum as the adhesive and pigment, respectively. The heat resistance mechanisms of the polysiloxane/Al coating were systematically investigated. The composition, surface morphology, infrared reflectance spectra, and thermal expansion dimension (ΔL of the coatings were characterized by X-ray photoelectron spectroscopy (XPS, field emission scanning electron microscopy (FE-SEM, Fourier transform infrared spectroscopy, and thermal mechanical analysis (TMA, respectively. The results show that thermal decomposition of the resin and mismatch of ΔL between the coating and the substrate facilitate the high temperature failure of the coating. A suitable amount of flake aluminum pigments could restrain the thermal decomposition of the resin and could increase the match degree of ΔL between the coating and substrate, leading to an enhanced thermal resistance of the coating. Our results find that a coating with a pigment to binder ratio (P/B ratio of 1.0 could maintain integrity until 600 °C, and the infrared emissivity was as low as 0.27. Hence, a coating with high-temperature resistance and low emissivity was obtained. Such coatings can be used for infrared stealth technology or energy savings in high-temperature equipment.

Effect of high-flux H/He plasma exposure on tungsten damage due to transient heat loads

Energy Technology Data Exchange (ETDEWEB)

De Temmerman, G., E-mail: gregory.detemmerman@iter.org [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregion Cluster, Postbus 1207, 3430BE Nieuwegein (Netherlands); ITER Organization, Route de Vinon sur Verdon, CS 90 096, 13067 Saint Paul-lez-Durance (France); Morgan, T.W.; Eden, G.G. van; Kruif, T. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Trilateral Euregion Cluster, Postbus 1207, 3430BE Nieuwegein (Netherlands); Wirtz, M. [Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research – Microstructure and Properties of Materials (IEK-2), EURATOM Association, 52425 Jülich (Germany); Matejicek, J.; Chraska, T. [Institute of Plasma Physics, Association EURATOM-IPP, CR Prague (Czech Republic); Pitts, R.A. [ITER Organization, Route de Vinon sur Verdon, CS 90 096, 13067 Saint Paul-lez-Durance (France); Wright, G.M. [MIT Plasma Science and Fusion Center, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)

2015-08-15

The thermal shock behaviour of tungsten exposed to high-flux plasma is studied using a high-power laser. The cases of laser-only, sequential laser and hydrogen (H) plasma and simultaneous laser plus H plasma exposure are studied. H plasma exposure leads to an embrittlement of the material and the appearance of a crack network originating from the centre of the laser spot. Under simultaneous loading, significant surface melting is observed. In general, H plasma exposure lowers the heat flux parameter (F{sub HF}) for the onset of surface melting by ∼25%. In the case of He-modified (fuzzy) surfaces, strong surface deformations are observed already after 1000 laser pulses at moderate F{sub HF} = 19 MJ m{sup −2} s{sup −1/2}, and a dense network of fine cracks is observed. These results indicate that high-fluence ITER-like plasma exposure influences the thermal shock properties of tungsten, lowering the permissible transient energy density beyond which macroscopic surface modifications begin to occur.

On transient events in the upper atmosphere generated away of thunderstorm regions

Science.gov (United States)

Morozenko, V.; Garipov, G.; Khrenov, B.; Klimov, P.; Panasyuk, M.; Sharakin, S.; Zotov, M.

2011-12-01

Experimental data on transient events in UV and Red-IR ranges obtained in the MSU missions "Unversitetsky-Tatiana" (wavelengths 300-400 nm) and "Unversitetsky-Tatiana-2" (wavelengths 300-400 nm and 600-800 nm), published by Garipov et al, in 2010 at COSPAR session http://www.cospar2010.org, at TEPA conference http://www.aragats.am/Conferences/tepa2010 and in 2011 by Sadovnichy et al, Solar System Research, 45, #1, 3-29 (2011); Vedenkin et al, JETP, v. 140, issue 3(9), 1-11 (2011) demonstrated existence of transients at large distances (up to thousands km) away of cloud thunderstorm regions. Those "remote" transients are short (1-5 msec) and are less luminous than the transients above thunderstorm regions. The ratio of Red-IR to UV photon numbers in those transients indicates high altitude of their origin (~70 km). Important observation facts are also: 1. a change of the exponent in transient distribution on luminosity Q ("-1" for photon numbers Q=1020 -1023 to "-2" for Q>1023), 2. a change of global distribution of transient with their luminosity (transients with Q>1023 are concentrated in equatorial range above continents, while transients with low luminosity are distributed more uniformly), 3. a phenomenon of transient sequences in one satellite orbit which is close to geomagnetic meridian. In the present paper phenomenological features of transients are explained in assumption that the observed transients have to be divided in two classes: 1. transients related to local, lower in the atmosphere, lightning at distance not more than hundreds km from satellite detector field of view in the atmosphere and 2. transients generated by far away lightning. Local transients are luminous and presumably are events called "transient luminous events" (TLE). In distribution on luminosity those events have some threshold Q~1023 and their differential luminosity distribution is approximated by power law exponent "-2". Remote transients have to be considered separately. Their

A transient absorption study of allophycocyanin

Indian Academy of Sciences (India)

Transient dynamics of allophycocyanin trimers and monomers are observed by using the pump-probe, transient absorption technique. The origin of spectral components of the transient absorption spectra is discussed in terms of both kinetics and spectroscopy. We find that the energy gap between the ground and excited ...

Summer freezing resistance: a critical filter for plant community assemblies in Mediterranean high mountains

Directory of Open Access Journals (Sweden)

David Sánchez Pescador

2016-02-01

Full Text Available Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain by measuring their ice nucleation temperature, freezing point (FP, and low-temperature damage (LT50, as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance. The community response to freezing was estimated for each plot as community weighted means (CWMs and functional diversity, and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content, and seed mass. There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the functional diversity of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only the leaf dry matter content correlated negatively with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower functional diversity of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to

UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

International Nuclear Information System (INIS)

Sanders, N. E.; Soderberg, A. M.; Betancourt, M.

2015-01-01

Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST

UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

Energy Technology Data Exchange (ETDEWEB)

Sanders, N. E.; Soderberg, A. M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Betancourt, M., E-mail: nsanders@cfa.harvard.edu [Department of Statistics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2015-02-10

Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST.

Investigation of Natural Circulation Instability and Transients in Passively Safe Small Modular Reactors

Energy Technology Data Exchange (ETDEWEB)

Ishii, Mamoru [Purdue Univ., West Lafayette, IN (United State

2016-11-30

The NEUP funded project, NEUP-3496, aims to experimentally investigate two-phase natural circulation flow instability that could occur in Small Modular Reactors (SMRs), especially for natural circulation SMRs. The objective has been achieved by systematically performing tests to study the general natural circulation instability characteristics and the natural circulation behavior under start-up or design basis accident conditions. Experimental data sets highlighting the effect of void reactivity feedback as well as the effect of power ramp-up rate and system pressure have been used to develop a comprehensive stability map. The safety analysis code, RELAP5, has been used to evaluate experimental results and models. Improvements to the constitutive relations for flashing have been made in order to develop a reliable analysis tool. This research has been focusing on two generic SMR designs, i.e. a small modular Simplified Boiling Water Reactor (SBWR) like design and a small integral Pressurized Water Reactor (PWR) like design. A BWR-type natural circulation test facility was firstly built based on the three-level scaling analysis of the Purdue Novel Modular Reactor (NMR) with an electric output of 50 MWe, namely NMR-50, which represents a BWR-type SMR with a significantly reduced reactor pressure vessel (RPV) height. The experimental facility was installed with various equipment to measure thermalhydraulic parameters such as pressure, temperature, mass flow rate and void fraction. Characterization tests were performed before the startup transient tests and quasi-steady tests to determine the loop flow resistance. The control system and data acquisition system were programmed with LabVIEW to realize the realtime control and data storage. The thermal-hydraulic and nuclear coupled startup transients were performed to investigate the flow instabilities at low pressure and low power conditions for NMR-50. Two different power ramps were chosen to study the effect of startup

The joy of transient chaos

Energy Technology Data Exchange (ETDEWEB)

Tél, Tamás [Institute for Theoretical Physics, Eötvös University, and MTA-ELTE Theoretical Physics Research Group, Pázmány P. s. 1/A, Budapest H-1117 (Hungary)

2015-09-15

We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

The joy of transient chaos.

Science.gov (United States)

Tél, Tamás

2015-09-01

We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

The ZTF Bright Transient Survey

Science.gov (United States)

Fremling, C.; Sharma, Y.; Kulkarni, S. R.; Miller, A. A.; Taggart, K.; Perley, D. A.; Gooba, A.

2018-06-01

As a supplement to the Zwicky Transient Facility (ZTF; ATel #11266) public alerts (ATel #11685) we plan to report (following ATel #11615) bright probable supernovae identified in the raw alert stream from the ZTF Northern Sky Survey ("Celestial Cinematography"; see Bellm & Kulkarni, 2017, Nature Astronomy 1, 71) to the Transient Name Server (https://wis-tns.weizmann.ac.il) on a daily basis; the ZTF Bright Transient Survey (BTS; see Kulkarni et al., 2018; arXiv:1710.04223).

Development of a Long-Life-Cycle, Highly Water-Resistant Solar Reflective Retrofit Roof Coating

Energy Technology Data Exchange (ETDEWEB)

Polyzos, Georgios [ORNL; Hunter, Scott Robert [ORNL; Sharma, Jaswinder K [ORNL; Cheng, Mengdawn [ORNL; Chen, Sharon S [Lawrence Berkeley National Laboratory (LBNL); Demarest, Victoria [Dow Chemical Company; Fabiny, William [Dow Chemical Company; Destaillats, Hugo [Lawrence Berkeley National Laboratory (LBNL); Levinson, Ronnen [Lawrence Berkeley National Laboratory (LBNL)

2016-03-04

Highly water-resistant and solar-reflective coatings for low-slope roofs are potentially among the most economical retrofit approaches to thermal management of the building envelope. Therefore, they represent a key building technology research program within the Department of Energy. Research efforts in industry and the Department of Energy are currently under way to increase long-term solar reflectance on a number of fronts. These include new polymer coatings technologies to provide longer-lasting solar reflectivity and improved test methodologies to predict long-term soiling and microbial performance. The focus on long-term improvements in soiling and microbial resistance for maximum reflectance does not address the single most important factor impacting the long-term sustainability of low-slope roof coatings: excellent water resistance. The hydrophobic character of asphaltic roof products makes them uniquely suitable for water resistance, but their low albedo and poor exterior durability are disadvantages. A reflective coating that maintains very high water resistance with increased long-term resistance to soiling and microbial activity would provide additional energy savings and extend roof service life.

Beam induced rf cavity transient voltage

International Nuclear Information System (INIS)

Kramer, S.L.; Wang, J.M.

1998-10-01

The authors calculate the transient voltage induced in a radio frequency cavity by the injection of a relativistic bunched beam into a circular accelerator. A simplified model of the beam induced voltage, using a single tone current signal, is generated and compared with the voltage induced by a more realistic model of a point-like bunched beam. The high Q limit of the bunched beam model is shown to be related simply to the simplified model. Both models are shown to induce voltages at the resonant frequency ω r of the cavity and at an integer multiple of the bunch revolution frequency (i.e. the accelerating frequency for powered cavity operation) hω ο . The presence of two nearby frequencies in the cavity leads to a modulation of the carrier wave exp(hω ο t). A special emphasis is placed in this paper on studying the modulation function. These models prove useful for computing the transient voltage induced in superconducting rf cavities, which was the motivation behind this research. The modulation of the transient cavity voltage discussed in this paper is the physical basis of the recently observed and explained new kinds of longitudinal rigid dipole mode which differs from the conventional Robinson mode

Transient Stability Improvement for Combined Heat and Power System Using Load Shedding

Directory of Open Access Journals (Sweden)

Hung-Cheng Chen

2014-01-01

Full Text Available The purpose of the paper is to analyze and improve the transient stability of an industrial combined heat and power (CHP system in a high-tech science park in Taiwan. The CHP system installed two 161 kV/161 kV high-impendence transformers to connect with Taipower System (TPS for both decreasing the short-circuit fault current and increasing the fault critical clearing time. The transient stabilities of three types of operation modes in CHP units, 3G1S, 2G1S, and 1G1S, are analyzed. Under the 3G1S operation mode, the system frequency is immediately restored to 60 Hz after tie line tripping with the TPS. Under the 1G1S and 2G1S operation modes, the system frequencies will continuously decrease and eventually become unstable. A novel transient stability improvement approach using load shedding technique based on the change in frequency is proposed to improve the transient stability.

Rme1 is necessary for Mi-1-mediated resistance and acts early in the resistance pathway.

Science.gov (United States)

Martinez de Ilarduya, Oscar; Nombela, Gloria; Hwang, Chin-Feng; Williamson, Valerie M; Muñiz, Mariano; Kaloshian, Isgouhi

2004-01-01

The tomato gene Mi-1 confers resistance to root-knot nematodes (Meloidogyne spp.), potato aphid, and whitefly. Using genetic screens, we have isolated a mutant, rme1 (resistance to Meloidogyne spp.), compromised in resistance to M. javanica and potato aphid. Here, we show that the rme1 mutant is also compromised in resistance to M. incognita, M. arenaria, and whitefly. In addition, using an Agrobacterium-mediated transient assay in leaves to express constitutive gain-of-function mutant Pto(L205D), we demonstrated that the rme1 mutation is not compromised in Pto-mediated hypersensitive response. Moreover, the mutation in rme1 does not result in increased virulence of pathogenic Pseudomonas syringae or Mi-1-virulent M. incognita. Using a chimeric Mi-1 construct, Mi-DS4, which confers constitutive cell death phenotype and A. rhizogenes root transformation, we showed that the Mi-1-mediated cell death pathway is intact in this mutant. Our results indicate that Rme1 is required for Mi-1-mediated resistance and acts either at the same step in the signal transduction pathway as Mi-1 or upstream of Mi-1.

Investigating the impact of in-vehicle transients on diesel soot emissions

Directory of Open Access Journals (Sweden)

Filipi Zoran

2008-01-01

Full Text Available This paper describes development of a test cell setup for concurrent running of a real engine and a simulation of the vehicle system, and its use for investigating highly-dynamic engine-in-vehicle operation and its effect on diesel engine emissions. Running an engine in the test cell under conditions experienced in the vehicle enables acquiring detailed insight into dynamic interactions between power train sub-systems, and the impact of it on fuel consumption and transient emissions. This type of data may otherwise be difficult and extremely costly to obtain from a vehicle prototype test. In particular, engine system response during critical transients and the effect of transient excursions on emissions are investigated using advanced, fast-response test instrumentation and emissions analyzers. Main enablers of the work include the highly dynamic AC electric dynamometer with the accompanying computerized control system and the computationally efficient simulation of the driveline/vehicle system. The latter is developed through systematic energy-based proper modeling that tailors the virtual model to capture critical powertrain transients while running in real time. Coupling the real engine with the virtual driveline/vehicle offers a chance to easily modify vehicle parameters, and even study different power train configurations. In particular, the paper describes the engine-in-the-loop study of a V-8, 6l engine coupled to a virtual 4´4 off road vehicle. This engine is considered as a high-performance option for this truck and the real prototype of the complete vehicle does not exist yet. The results shed light on critical transients in a conventional powertrain and their effect on NOx and soot emissions. Measurements demonstrate very large spikes of particulate concentration at the initiation of vehicle acceleration events. Characterization of transients and their effect on particulate emission provides a basis for devising engine-level or

Exceptionally high cavitation erosion and corrosion resistance of a high entropy alloy.

Science.gov (United States)

Nair, R B; Arora, H S; Mukherjee, Sundeep; Singh, S; Singh, H; Grewal, H S

2018-03-01

Cavitation erosion and corrosion of structural materials are serious concerns for marine and offshore industries. Durability and performance of marine components are severely impaired due to degradation from erosion and corrosion. Utilization of advanced structural materials can play a vital role in limiting such degradation. High entropy alloys (HEAs) are a relatively new class of advanced structural materials with exceptional properties. In the present work, we report on the cavitation erosion behavior of Al 0.1 CoCrFeNi HEA in two different media: distilled water with and without 3.5wt% NaCl. For comparison, conventionally used stainless steel SS316L was also evaluated in identical test conditions. Despite lower hardness and yield strength, the HEA showed significantly longer incubation period and lower erosion-corrosion rate (nearly 1/4th) compared to SS316L steel. Enhanced erosion resistance of HEA was attributed to its high work-hardening behavior and stable passivation film on the surface. The Al 0.1 CoCrFeNi HEA showed lower corrosion current density, high pitting resistance and protection potential compared to SS316L steel. Further, HEA showed no evidence of intergranular corrosion likely due to the absence of secondary precipitates. Although, the degradation mechanisms (formation of pits and fatigue cracks) were similar for both the materials, the damage severity was found to be much higher for SS316L steel compared to HEA. Copyright © 2017 Elsevier B.V. All rights reserved.

An experimental investigation of transient heat transfer in surrounding rock mass of high geothermal roadway

Directory of Open Access Journals (Sweden)

Zhang Yuan

2016-01-01

Full Text Available A self-designed experimental installation for transient heat transfer in the modelling surrounding rock mass of high geothermal roadways was elaborated in this paper. By utilizing the new installation, the temperature variation rules in surrounding rock mass of the high geothermal roadway during mechanical ventilation were studied. The results show that the roadway wall temperature decreases dramatically at the early stage of ventilation, and the temperature at every position of the surrounding rock mass is decreasing constantly with time passing by. From roadway wall to deep area, the temperature gradually increases until reaching original rock temperature. The relationship between dimensionless temperature and dimensionless radius demonstrates approximately exponential function. Meanwhile, the temperature disturbance range in the simulated surrounding rock mass extends gradually from the roadway wall to deep area in the surrounding rock mass. Besides, as the air velocity increases, heat loss in the surrounding rock mass rises and the ratio of temperature reduction becomes larger, the speed of disturbance range expansion also gets faster.

Transient and steady-state flows in shock tunnels

Energy Technology Data Exchange (ETDEWEB)

Hannemann, K. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Goettingen (Germany); Jacobs, P.A. [Queensland Univ., Brisbane (Australia). Dept. of Mechanical Engineering; Thomas, A.; McIntyre, T.J. [Queensland Univ., Brisbane, QLD. (Australia). Dept. of Physics

1999-12-01

Due to the difficulty of measuring all necessary flow quantities in the nozzle reservoir and the test section of high enthalpy shock tunnels, indirect computational methods are necessary to estimate the required flow parameters. In addition to steady state flow computations of the nozzle flow and the flow past wind tunnel models it is necessary to investigate the transient flow in the facility in order to achieve a better understanding of its performance. These transient effects include the nozzle starting flow, the interaction of the shock tube boundary layers and the reflected shock, thermal losses in the shock reflection region and the developing boundary layers in the expanding section of the nozzle. Additionally, the nonequilibrium chemical and thermal relaxation models which are used to compute high enthalpy flows have to be validated with appropriate experimental data. (orig.)

Transient and steady-state flows in shock tunnels