Transient thermal performance analysis of micro heat pipes
International Nuclear Information System (INIS)
Liu, Xiangdong; Chen, Yongping
2013-01-01
A theoretical analysis of transient fluid flow and heat transfer in a triangular micro heat pipes (MHP) has been conducted to study the thermal response characteristics. By introducing the system identification theory, the quantitative evaluation of the MHP's transient thermal performance is realized. The results indicate that the evaporation and condensation processes are both extended into the adiabatic section. During the start-up process, the capillary radius along axial direction of MHP decreases drastically while the liquid velocity increases quickly at the early transient stage and an approximately linear decrease in wall temperature arises along the axial direction. The MHP behaves as a first-order LTI control system with the constant input power as the 'step input' and the evaporator wall temperature as the 'output'. Two corresponding evaluation criteria derived from the control theory, time constant and temperature constant, are able to quantitatively evaluate the thermal response speed and temperature level of MHP under start-up, which show that a larger triangular groove's hydraulic diameter within 0.18–0.42 mm is able to accelerate the start-up and decrease the start-up temperature level of MHP. Additionally, the MHP starts up fastest using the fluid of ethanol and most slowly using the working fluid of methanol, and the start-up temperature reaches maximum level for acetone and minimum level for the methanol. -- Highlights: • Transient thermal response of micro heat pipe is simulated by an improved model. • Control theory is introduced to quantify the thermal response of micro heat pipe. • Evaluation criteria are proposed to represent thermal response of micro heat pipe. • Effects of groove dimensions and working fluids on start-up of micro heat pipe are evaluated
The development of the fuel rod transient performance analysis code FTPAC
International Nuclear Information System (INIS)
Han Zhijie; Ji Songtao
2014-01-01
Fuel rod behavior, especially the integrity of cladding, played an important role in fuel safety research during reactor transient and hypothetical accidents conditions. In order to study fuel rod performance under transient accidents, FTPAC (Fuel Transient Performance Analysis Code) has been developed for simulating light water reactor fuel rod transient behavior when power or coolant boundary conditions are rapidly changing. It is composed of temperature, mechanical deformation, cladding oxidation and gas pressure model. The assessment was performed by comparing FTPAC code analysis result to experiments data and FRAPTRAN code calculations. Comparison shows that, the FTPAC gives reasonable agreement in temperature, deformation and gas pressure prediction. And the application of slip coefficient is more suitable for simulating the sliding between pellet and cladding when the gap is closed. (authors)
Fluid dynamic transient analysis
International Nuclear Information System (INIS)
Vilhena Reigosa, R. de
1992-01-01
This paper describes the methodology adopted at NUCLEN for the fluid dynamic analyses for ANGRA 2. The fluid dynamic analysis allows, through computer codes to simulate and quantify the loads resulting from fluid dynamic transients caused by postulated ruptures or operational transients, in the piping of the safety systems and of the important operational systems. (author)
DEFF Research Database (Denmark)
Li, H.; Zhao, B.; Han, L.
2010-01-01
In order to analyze correctly the effect of different models for induction generators on the transient performances of large wind power generation, Wind turbine driven squirrel cage induction generator (SCIG) models taking into account both main and leakage flux saturation and skin effect were...
DEFF Research Database (Denmark)
Li, H.; Ye, R.; Han, L.
2010-01-01
In order to entirely analyze the transient performances of a grid-connected doubly fed induction generator (DFIG) wind turbine under the different operational states, based on the transient models of DFIG, a two-mass wind turbine electrical equivalent model considering the torsional flexibility o...
Ravikumar, S.; Subash Chandra, Parisaboina; Harish, Remella; Sivaji, Tallapaneni
2017-05-01
The advancement of the digital computer and its utilization day by day is rapidly increasing. But the reliability of electronic components is critically affected by the temperature at which the junction operates. The designers are forced to shorten the overall system dimensions, in extracting the heat and controlling the temperature which focus the studies of electronic cooling. In this project Thermal analysis is carried out with a commercial package provided by ANSYS. The geometric variables and design of heat sink for improving the thermal performance is experimented. This project utilizes thermal analysis to identify a cooling solution for a desktop computer, which uses a 5 W CPU. The design is able to cool the chassis with heat sink joined to the CPU is adequate to cool the whole system. This work considers the circular cylindrical pin fins and rectangular plate heat sink fins design with aluminium base plate and the control of CPU heat sink processes.
Transient analysis of space reactors
International Nuclear Information System (INIS)
Giap, H.Q.; Best, F.
1985-01-01
Nuclear reactors are being considered as the primary energy source for an increasing number of space missions including the National Aeronautics and Space Administration's space station and the Strategic Defense Initiative's SP-100. Conceptual reactor designs include fast and thermal spectrum reactors with liquid-metal or gas cooling delivering thermal energy to Brayton, Stirling, thermoelectric, thermoionic, or Rankine cycle power conversion systems. Almost all designs utilize a thermal radiator for waste heat rejection, although the radiator may assume such exotic forms as fans of liquid-metal droplets or metal filaments floating in free space. The reactor, power conversion, and heat rejection systems must operate in zero gravity, be uniformly small and lightweight, and utilize exotic materials compared with terrestrial technology. Therefore, the problems of system design and analysis are unique to space applications, and new analysis tools must be developed. With this motivation, the Transient Analysis of Space Reactors (TASR) computer code has been developed to predict system performance under steady-state and transient conditions. The SP-100 space reactor system, being designed by General Electric (GE) Company, was used as the test system for the TASR code. At full power, the SP-100 produces 110 kW(e) from 2.21 MW(t) via a thermoelectric conversion system
Reactor operational transient analysis
International Nuclear Information System (INIS)
Shin, W.K.; Chae, S.K.; Han, K.I.; Yang, K.S.; Chung, H. D.; Kim, H.G.; Moon, H.J.; Ryu, Y.H.
1983-01-01
To build up efficient capability of safety review and inspection for the nuclear power plants, four area of studies have performed as follows: 1) In order to search the most optimized operating method during load follow operating schemes, automatic control and normal control, are compared each other under the CAOC condition. The analysis performed by DDID code has shown that the reactor has to be controlled by the operator manually during load follow operation. 2) Through the sensitivity analysis by COBRA code, the operating parameters, such as coolant pressure, flow rate, inlet temperature, and power distribution are shown to be important to the determination of DNBR. Expecially, inlet temperature of primary coolant system is appeared as the most senstive parameter on DNBR. 3) FRAPCON code is adapted to study the sensitivity of several operational parameters on the mechanical properties of reactor fuel rod. 4) The calculations procedure which is required to be obtained the neutron fluence at the reactor vessel and the spectrum at the surveillance capsule is established. The results of computation are conpared with those of FSAR and SWRI report and proved its applicability to reactor surveillance program. (Author)
Analysis of UO{sub 2}-BeO fuel under transient using fuel performance code
Energy Technology Data Exchange (ETDEWEB)
Gomes, Daniel S.; Abe, Alfredo Y.; Muniz, Rafael O.R.; Giovedi, Claudia, E-mail: dsgomes@ipen.br, E-mail: alfredo@ctmsp.mar.mil.br, E-mail: rafael.orm@gmail.com, E-mail: claudia.giovedi@ctmsp.mar.mil.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Universidade de São Paulo (USP), São Paulo, SP (Brazil). Departamento de Engenharia Naval e Oceânica
2017-11-01
Recent research has appointed the need to replace the classic fuel concept, used in light water reactors. Uranium dioxide has a weak point due to the low thermal conductivity, that produce high temperatures on the fuel. The ceramic composite fuel formed of uranium dioxide (UO{sub 2}), with the addition of beryllium oxide (BeO), presents high thermal conductivity compared with UO{sub 2}. The oxidation of zirconium generates hydrogen gas that can create a detonation condition. One of the preferred options are the ferritic alloys formed of iron-chromium and aluminum (FeCrAl), that should avoid the hydrogen release due to oxidation. In general, the FeCrAl alloys containing 10 - 20Cr, 3 - 5Al, and 0 - 0.12Y in weight percent. The FeCrAl alloys should exhibit a slow oxidation kinetics due to chemical composition. Resistance to oxidation in the presence of steam is improved as a function of the content of chromium and aluminum. In this way, the thermal and mechanical properties of the UO{sub 2}-BeO-10%vol, composite fuel were coupled with FeCrAl alloys and added to the fuel codes. In this work, we examine the fuel rod behavior of UO{sub 2}-10%vol-BeO/FeCrAl, including a simulated transient of reactivity. The fuels behavior shown reduced temperature with UO{sub 2}-BeO/Zr, UO{sub 2}-BeO/FeCrAl also were compared with UO{sub 2}/Zr system. The case reactivity initiated accident analyzed, reproducing the fuel rod called VA-1 using UO{sub 2}/Zr alloys and compared with UO{sub 2}-BeO/FeCrAl. (author)
Transient analysis of multicavity klystrons
International Nuclear Information System (INIS)
Lavine, T.L.; Miller, R.H.; Morton, P.L.; Ruth, R.D.
1988-09-01
We describe a model for analytic analysis of transients in multicavity klystron output power and phase. Cavities are modeled as resonant circuits, while bunching of the beam is modeled using linear space-charge wave theory. Our analysis has been implemented in a computer program which we use in designing multicavity klystrons with stable output power and phase. We present as examples transient analysis of a relativistic klystron using a magnetic pulse compression modulator, and of a conventional klystron designed to use phase shifting techniques for RF pulse compression. 4 refs., 4 figs
Fault Transient Analysis and Protection Performance Evaluation within a Large-scale PV Power Plant
Directory of Open Access Journals (Sweden)
Wen Jinghua
2016-01-01
Full Text Available In this paper, a short-circuit test within a large-scale PV power plant with a total capacity of 850MWp is discussed. The fault currents supplied by the PV generation units are presented and analysed. According to the fault behaviour, the existing protection coordination principles with the plant are considered and their performances are evaluated. Moreover, these protections are examined in simulation platform under different operating situations. A simple measure with communication system is proposed to deal with the foreseeable problem about the current protection scheme in the PV power plant.
Directory of Open Access Journals (Sweden)
Young Eun Chon
Full Text Available Transient elastography (TE, a non-invasive tool that measures liver stiffness, has been evaluated in meta-analyses for effectiveness in assessing liver fibrosis in European populations with chronic hepatitis C (CHC. However, these data cannot be extrapolated to populations in Asian countries, where chronic hepatitis B (CHB is more prevalent. In this study, we performed a meta-analysis to assess the overall performance of TE for assessing liver fibrosis in patients with CHB.Studies from the literature and international conference abstracts which enrolled only patients with CHB or performed a subgroup analysis of such patients were enrolled. Combined effects were calculated using area under the receiver operating characteristic curves (AUROC and diagnostic accuracy values of each study.A total of 18 studies comprising 2,772 patients were analyzed. The mean AUROCs for the diagnosis of significant fibrosis (F2, severe fibrosis (F3, and cirrhosis (F4 were 0.859 (95% confidence interval [CI], 0.857-0.860, 0.887 (95% CI, 0.886-0.887, and 0.929 (95% CI, 0.928-0.929, respectively. The estimated cutoff for F2 was 7.9 (range, 6.1-11.8 kPa, with a sensitivity of 74.3% and specificity of 78.3%. For F3, the cutoff value was determined to be 8.8 (range, 8.1-9.7 kPa, with a sensitivity of 74.0% and specificity of 63.8%. The cutoff value for F4 was 11.7 (range, 7.3-17.5 kPa, with a sensitivity of 84.6% and specificity of 81.5%.TE can be performed with good diagnostic accuracy for quantifying liver fibrosis in patients with CHB.
Nwosu, Cajethan M.; Oti, Stephen E.; Ogbuka, Cosmas U.
2017-01-01
This paper presents transient and steady state performance analysis of power flow control in a 5.0 kW Doubly-Fed Induction Generator (DFIG) Variable Speed Wind Turbine (VSWT) under sub synchronous speed, super synchronous speed and synchronous speed modes of operation. Stator flux orientation is used for the control of the rotor-side converter (RSC) and DFIG whereas the grid (or stator) voltage orientation is the preferred choice for the control of the grid-side converter (GSC). In each of the three speeds modes, power is always supplied to the grid through the stator of the DFIG. The magnitude of net power (stator power plus rotor power) is less than stator power during the sub synchronous speed mode; it is greater than stator power during the super synchronous speed mode while it is equal to the stator power during the synchronous speed mode. In synchronous speed mode, the rotor power is zero indicating that power is neither supplied to the grid from the rotor nor supplied to the rotor from the grid; here the magnitude of net power is equal to stator power. The simulation results thus obtained in a MATLAB/SIMULINK environment laid credence to the controllability of power flow reversal in a DFIG-VSWT through back-to-back power electronic converter.
International Nuclear Information System (INIS)
Han, Ji Woong; Eoh, Jae Hyuk; Kim, Seong O
2010-01-01
The effect of increasing the elevation of an IHX (intermediate heat exchanger) on the transient performance of the KALIMER-600 reactor pool during the early phase of a loss of normal heat sink accident was investigated. Three reactors equipped with IHXs that were elevated to different heights were designed, and the thermal-hydraulic analyses were carried out for the steady and transient state by using the COMMIX-1AR/P code. In order to analyze the effects of the elevation of an IHX between reactors, various thermal-hydraulic properties such as mass flow rate, core peak temperature, RmfQ (ratio of mass flow over Q) and initiation time of decay heat removal via DHX (decay heat exchanger) were evaluated. It was found that with an increase in the IHX elevation, the circulation flow rate increases and a steep rise in the core peak temperature under the same coastdown flow condition is prevented without a delay in the initiation of the second stage of cooling. The available coastdown flow range in the reactor could be increased by increasing the elevation of the IHX
International Nuclear Information System (INIS)
Mori, Michitsugu; Mizuno, Minoru; Itoh, Mitsuyoshi; Urabe, Shigemi
1985-01-01
The intermediate heat exchanger (IHX) is designed as the high temperature heat exchanger for HTGR (High Temperature Gas-cooled Reactor), which transmits the primary coolant helium's heat raised up to about 950 0 C in the reactor core to the secondary helium or the nuclear heat utilization. Having to meet, in addition, the requirement of the primary coolant pressure boundary as the Class-1 component, it must be secured integrity throughout the service life. This paper will show (1) the design of the thermal performance; (2) the results of the dynamic analyses of the 1.5 MWt-IHX with its comparison to the experimental data; (3) the analytical predictions of the dynamic thermal behaviors under start-up and of the transient thermal behaviors during the accident on the 25 MWt-IHX. (author)
Transient analysis capabilities at ABB-CE
International Nuclear Information System (INIS)
Kling, C.L.
1992-01-01
The transient capabilities at ABB-Combustion Engineering (ABB-CE) Nuclear Power are a function of the computer hardware and related network used, the computer software that has evolved over the years, and the commercial technical exchange agreements with other related organizations and customers. ABB-CEA is changing from a mainframe/personal computer network to a distributed workstation/personal computer local area network. The paper discusses computer hardware, mainframe computing, personal computers, mainframe/personal computer networks, workstations, transient analysis computer software, design/operation transient analysis codes, safety (licensed) analysis codes, cooperation with ABB-Atom, and customer support
Intermediate size inducer pump - structural analysis and transient deformation studies
Energy Technology Data Exchange (ETDEWEB)
Cheng, T.K.; Nishizaka, J.N.
1979-05-01
This report summarizes the structural and thermal transient deformation analysis of the Intermediate Size Inducer Pump. The analyses were performed in accordance to the requirements of N266ST310001, the specification for the ISIP. Results of stress analysis indicate that the thermal transient stress and strain are within the stress strain limits of RDT standard F9-4 which was used as a guide.
Alternatives Analysis for the Resumption of Transient Testing Program
Energy Technology Data Exchange (ETDEWEB)
Lee Nelson
2013-11-01
An alternatives analysis was performed for resumption of transient testing. The analysis considered eleven alternatives – including both US international facilities. A screening process was used to identify two viable alternatives from the original eleven. In addition, the alternatives analysis includes a no action alternative as required by the National Environmental Policy Act (NEPA). The alternatives considered in this analysis included: 1. Restart the Transient Reactor Test Facility (TREAT) 2. Modify the Annular Core Research Reactor (ACRR) which includes construction of a new hot cell and installation of a new hodoscope. 3. No Action
Mendes, L C; Ferreira, P A; Miotto, N; Zanaga, L; Gonçales, E S L; Pedro, M N; Lazarini, M S; Júnior, F L G; Stucchi, R S B; Vigani, A G
2018-04-01
Vibration-controlled transient elastography (VCTE) is widely used for noninvasive fibrosis staging in chronic hepatitis C. However, internal validation is based solely on variability and success rate and lacks reproducible quality indicators. We analysed the graphic representation of shear wave propagation in comparison with morphometric results of liver biopsy, eliminating observer variability bias. Individual elastograms were classified according to two morphologic criteria: extension of wave propagation (length of the graphic representation) and shear wave dispersal (level of parallelism displayed in the elastogram). Then, a score based on these criteria stratified the elastogram in classes I through III (highest to lowest technical quality). Liver stiffness results of each measurement were compared with collagen contents in liver biopsy by morphometric analysis. A total of 3243 elastograms were studied (316 patients). Digital morphometry in liver biopsy showed significant fibrosis in 66% of samples and advanced fibrosis in 31%. Elastogram quality analysis resulted in 1438 class I measurements (44%), 1070 class II (34%) and 735 class III. Area under the receiver operating curve (AUROC) for severe fibrosis according to class (I, II and III) was 0.941, 0.887 and 0.766, respectively. For advanced fibrosis, AUROCs were 0.977, 0.883 and 0.781, respectively. Spearman's correlation testing for all classes and levels of fibrosis demonstrated significant independent association (r 2 = -.95, P digital morphometric imaging analysis. We concluded that VCTE performance is significantly influenced by quality assessment of individual measurements. Considering these criteria in clinical practice may improve accuracy. © 2017 John Wiley & Sons Ltd.
Thermophysical Analysis of Rocks by Transient Methods
Kubicar, Ludovit; Vretenar, Viliam; Bohac, Vlastimil; Stofanik, Vladimir; Dieska, Peter
2010-05-01
Rocks belong to porous materials where content of pore significantly influence its thermophysical properties. Porous structure plays an important role in heat and fluid transport. A set of effects can be found in such structures like freezing, thawing, evaporation, etc. Highly innovative testing technique based on transient methods has been used for thermophysical analysis in which the specific heat, thermal diffusivity and thermal conductivity is determined, anomalies of the thermophysical parameters connected with freezing and thawing of water in pores are measured, propagation of freezing and thawing fronts are detected and diffusion of moisture in pore structure is monitored on sandstone and Gioia marble. Pulse transient method is based on generation of a heat disturbance by plane heat source fixed in the sample. Specific heat, thermal diffusivity and thermal conductivity are determined from the parameters of the temperature response to this heat disturbance. A heat source in the step-wise heating regime was applied to the frozen sample to study basic characteristics of the propagation of thawing front. In both experiments a sample is used that consists of three parts of size 50x50x10 mm assembled in a rectangle 50x50x30 mm where in first contact of the specimen parts a plane of heat source and in the second one a thermometer is fixed. The sample has to be conditioned prior the measurement to obtain the required thermodynamic state, i.e. the initial temperature and moisture stage. An appropriate heating and cooling regime allows measuring the anomalies of specific heat, thermal conductivity and thermal diffusivity connected with freezing and thawing. The hot ball transient method for measuring thermal conductivity is used for monitoring the moisture diffusion. Principle of the hot ball method is based on generation of the heat in a step-wise regime by a sensor in a form of small ball in diameter of 2 mm that, in addition, it monitors its temperature. A
Analytic models for fuel pin transient performance
International Nuclear Information System (INIS)
Bard, F.E.; Fox, G.L.; Washburn, D.F.; Hanson, J.E.
1976-09-01
HEDL's ability to analyze various mechanisms that operate within a fuel pin has progressed substantially through development of codes such as PECTCLAD, which solves cladding response, and DSTRESS, which solves fuel response. The PECTCLAD results show good correlation with a variety of mechanical tests on cladding material and also demonstrate the significance of cladding strength when applying the life fraction rule. The DSTRESS results have shown that fuel deforms sufficiently during overpower transient tests that available volumes are filled, whether in the form of a central cavity or start-up cracks
International Nuclear Information System (INIS)
2008-05-01
This book introduces energy and resource technology development business with performance analysis, which has business division and definition, analysis of current situation of support, substance of basic plan of national energy, resource technique development, selection of analysis index, result of performance analysis by index, performance result of investigation, analysis and appraisal of energy and resource technology development business in 2007.
Castellini, Paolo; Di Giuseppe, Andrea
2008-06-01
This paper describes the development of a system for measuring surface coordinates (commonly known as "shape measurements") which is able to give the temporal evolution of the position of the tire sidewall in transient conditions (such as during braking, when there are potholes or when the road surface is uneven) which may or may not be reproducible. The system is based on the well-known technique of projecting and observing structured light using a digital camera with an optical axis which is slanted with respect to the axis of the projector. The transient nature of the phenomenon has led to the development of specific innovative solutions as regards image processing algorithms. This paper briefly describes the components which make up the measuring system and presents the results of the measurements carried out on the drum bench. It then analyses the performance of the measuring system and the sources of uncertainty which led to the development of the system for a specific dynamic application: impact with an obstacle (cleat test). The measuring system guaranteed a measurement uncertainty of 0.28mm along the Z axis (the axial direction of the tire) with a measurement range of 250(X)×80(Y)×25(Z)mm3, with the tire rolling at a speed of up to 30km/h.
International Nuclear Information System (INIS)
Porter, W.H.L.
1982-11-01
To check containment performance of the CVTR, steam was injected above the operating floor through a 10 foot pipe cap containing the 1 inch diameter holes, at a steady rate of 102.8 lb/sec for a period of 166 seconds. This steam had an enthalpy of 1195 Btu/lb and was therefore not entirely typical of the much wetter material which would be rejected for the greater part of a true breached circuit accident. Pressure transients measured experimentally within the containment were compared with results calculated by the American code CONTEMPT and these results in turn have allowed the Winfrith code CLAPTRAP to be tested for consistency and to establish that the use of this code would have led to similar conclusions about the heat transfer coefficients at the heat absorbent surfaces. (U.K.)
Control Design of VSIs to Enhance Transient Performance in Microgrids
DEFF Research Database (Denmark)
Federico, de Bosio; Antonio DeSouza Ribeiro, Luiz; Savaghebi, Mehdi
2016-01-01
This paper discusses the control design for an islanded microgrid in order to ensure acceptable performance in terms of voltage quality and load sharing by focusing on transient conditions. To this aim, state feedback decoupling approach has been applied. Experimental tests have been performed...
Performance of neutron kinetics models for ADS transient analyses
International Nuclear Information System (INIS)
Rineiski, A.; Maschek, W.; Rimpault, G.
2002-01-01
Within the framework of the SIMMER code development, neutron kinetics models for simulating transients and hypothetical accidents in advanced reactor systems, in particular in Accelerator Driven Systems (ADSs), have been developed at FZK/IKET in cooperation with CE Cadarache. SIMMER is a fluid-dynamics/thermal-hydraulics code, coupled with a structure model and a space-, time- and energy-dependent neutronics module for analyzing transients and accidents. The advanced kinetics models have also been implemented into KIN3D, a module of the VARIANT/TGV code (stand-alone neutron kinetics) for broadening application and for testing and benchmarking. In the paper, a short review of the SIMMER and KIN3D neutron kinetics models is given. Some typical transients related to ADS perturbations are analyzed. The general models of SIMMER and KIN3D are compared with more simple techniques developed in the context of this work to get a better understanding of the specifics of transients in subcritical systems and to estimate the performance of different kinetics options. These comparisons may also help in elaborating new kinetics models and extending existing computation tools for ADS transient analyses. The traditional point-kinetics model may give rather inaccurate transient reaction rate distributions in an ADS even if the material configuration does not change significantly. This inaccuracy is not related to the problem of choosing a 'right' weighting function: the point-kinetics model with any weighting function cannot take into account pronounced flux shape variations related to possible significant changes in the criticality level or to fast beam trips. To improve the accuracy of the point-kinetics option for slow transients, we have introduced a correction factor technique. The related analyses give a better understanding of 'long-timescale' kinetics phenomena in the subcritical domain and help to evaluate the performance of the quasi-static scheme in a particular case. One
TauG-guidance of transients in expressive musical performance
Schogler, Benjaman; Pepping, Gert-Jan; Lee, David N.
The sounds in expressive musical performance, and the movements that produce them, offer insight into temporal patterns in the brain that generate expression. To gain understanding of these brain patterns, we analyzed two types of transient sounds, and the movements that produced them, during a
Analysis of short-term reactor cavity transient
International Nuclear Information System (INIS)
Cheng, T.C.; Fischer, S.R.
1981-01-01
Following the transient of a hypothetical loss-of-coolant accident (LOCA) in a nuclear reactor, peak pressures are reached within the first 0.03 s at different locations inside the reactor cavity. Due to the complicated multidimensional nature of the reactor cavity, the short-term analysis of the LOCA transient cannot be performed by using traditional containment codes, such as CONTEMPT. The advanced containment code, BEACON/MOD3, developed at the Idaho National Engineering Laboratory (INEL), can be adapted for such analysis. This code provides Eulerian, one and two-dimensional, nonhomogeneous, nonequilibrium flow modeling as well as lumped parameter, homogeneous, equilibrium flow modeling for the solution of two-component, two-phase flow problems. The purpose of this paper is to demonstrate the capability of the BEACON code to analyze complex containment geometry such as a reactor cavity
Baquerizo, Guillermo; Maestre, Juan P; Machado, Vinicius C; Gamisans, Xavier; Gabriel, David
2009-05-01
A comprehensive study of long-term ammonia removal in a biofilter packed with coconut fiber is presented under both steady-state and transient conditions. Low and high ammonia loads were applied to the reactor by varying the inlet ammonia concentration from 90 to 260 ppm(v) and gas contact times ranging from 20 to 36 s. Gas samples and leachate measurements were periodically analyzed and used for characterizing biofilter performance in terms of removal efficiency (RE) and elimination capacity (EC). Also, N fractions in the leachate were quantified to both identify the experimental rates of nitritation and nitratation and to determine the N leachate distribution. Results showed stratification in the biofilter activity and, thus, most of the NH(3) removal was performed in the lower part of the reactor. An average EC of 0.5 kg N-NH(3)m(-3)d(-1) was obtained for the whole reactor with a maximum local average EC of 1.7 kg N-NH(3)m(-3)d(-1). Leachate analyses showed that a ratio of 1:1 of ammonium and nitrate ions in the leachate was obtained throughout steady-state operation at low ammonia loads with similar values for nitritation and nitratation rates. Low nitratation rates during high ammonia load periods occurred because large amounts of ammonium and nitrite accumulated in the packed bed, thus causing inhibition episodes on nitrite-oxidizing bacteria due to free ammonia accumulation. Mass balances showed that 50% of the ammonia fed to the reactor was oxidized to either nitrite or nitrate and the rest was recovered as ammonium indicating that sorption processes play a fundamental role in the treatment of ammonia by biofiltration.
International Nuclear Information System (INIS)
Kinoshita, Hidetaka; Kaminaga, Masanori; Hino, Ryutaro
2000-02-01
In order to promote the Neutron Science Project of JAERI, the design of a 5MW-spallation target system is in progress with the purpose of producing a practical neutron application while at the same time adhering to the highest levels of safety. To establish the safety of the target system, it is important to understand the transient behaviors during anticipated operational events of the system, and to design the safety protection systems for the safe termination of the transients. This report presents the analytical results of transient behaviors in the mercury experimental loop using mercury properties. At first, the analytical pressure distributions were compared with experimental data measured with the mercury experimental loop. The modeling data were modified to reproduce the actual pressure distributions of the mercury experimental loop. Then a loss of forced convection and a loss of coolant accident were analyzed. In the case of the pump trip, the transient analysis was conducted using two types of mercury pumps, the mechanical type pump with moment of inertia, and the electrical-magnetic type pump without moment of inertia. The results show there was no clear difference in the two analyses, since the mercury had a large inertia, which was 13.5 times that of the water. Moreover, in the case of a pipe rupture at the pump exit, a moderate pressure decrease was confirmed when a small breakage area existed in which the coolant flowed out gradually. Based on these results, it was appeared that the transient fluctuation of pressure in the mercury loop would not become large and accidents would have to be detected by small fluctuations in pressure. Based on these analyses, we plan to conduct a simulation test to verify the RELAP5 code, and then the analysis of a full-scale mercury system will be performed. (author)
Transient Vestibulopathy in Wallenberg’s Syndrome: Pathologic Analysis
Directory of Open Access Journals (Sweden)
Jorge C. Kattah
2017-05-01
Full Text Available ObjectiveTo report an unusual lateral medullary stroke (LMS associated with transient unidirectional horizontal, nystagmus, and decreased horizontal vestibulo–ocular reflex (h-VOR gain that mimicked a peripheral vestibulopathy. MRI suggested involvement of caudal medial vestibular nucleus (MVN; however, the rapid resolution of the nystagmus and improved h-VOR gain favored transient ischemia without infarction. Decreased h-VOR gain is expected with peripheral vestibular lesions within the labyrinth or superior vestibular nerve; less frequently lateral pontine strokes involving the vestibular root entry, the vestibular fascicle, or neurons within the MVN may be responsible. The h-VOR is typically normal in LMS.MethodsClinicopathologic examination of a 61-year-old man with an acute vestibular syndrome (AVS and left LMS who died 3 weeks after the stroke. Postmortem brainstem analysis was performed.ResultsThe stroke involved the lateral medulla and pontomedullary junction, near the MVN, sparing the cerebellum and pons. To explain transient vestibular findings there are two possible hypotheses; the first would be that the MVN survived the ischemic process and would be histologically intact, and the second that vestibular afferents in the horizontal semicircular canal were ischemic and recovered after the ischemic process. Neuropathological examination showed a left LMS whose extent matched that seen by imaging. Non-ocular motor signs correlated well with structures affected by the infarction. Neurons and glia within nearby MVN were spared, as predicted by the rapid normalization of the ocular motor signs. Although unlikely, the possibility of transient intralabyrinthine arteriolar ischemia cannot be excluded. Additionally, truncal lateropulsion was due to combined lateral vestibulospinal tract and lateral reticular nucleus infarction.ConclusionLMS may rarely be associated with an AVS that either represents or mimics a peripheral vestibulopathy. To
One gigasample per second transient recorder: a performance demonstration
International Nuclear Information System (INIS)
Linnenbrink, T.E.; Gradl, D.A.; Ritt, D.M.; DeWitte, G.J.; Hutton, J.D.
1982-01-01
The performance demonstrated by a one gigasample per second (1 Gs/s) transient recorder currently in advanced development portends an important new instrument for recording single transient data. A Charge-Coupled Device (CCD) is used to sample a continuous analog signal. Samples acquired at the full sampling rate (1 Gs/s) are temporarily stored in the CCD, then read out at a slow rate (e.g., 250 Ks/s) into a conventional analog-to-digital converter prior to storage in nonvolatile, digital memory. Enhanced circuitry and techniques developed over the past three years have yielded higher performance than originally anticipated. Accordingly, the target specification has been revised to reflect higher expectations
One gigasample per second transient recorder: a performance demonstration
Energy Technology Data Exchange (ETDEWEB)
Linnenbrink, T. E.; Gradl, D. A.; Ritt, D. M.; DeWitte, G. J.; Hutton, J. D.
1982-01-01
The performance demonstrated by a one gigasample per second (1 Gs/s) transient recorder currently in advanced development portends an important new instrument for recording single transient data. A Charge-Coupled Device (CCD) is used to sample a continuous analog signal. Samples acquired at the full sampling rate (1 Gs/s) are temporarily stored in the CCD, then read out at a slow rate (e.g., 250 Ks/s) into a conventional analog-to-digital converter prior to storage in nonvolatile, digital memory. Enhanced circuitry and techniques developed over the past three years have yielded higher performance than originally anticipated. Accordingly, the target specification has been revised to reflect higher expectations.
Atucha I nuclear power plant transients analysis
International Nuclear Information System (INIS)
Castano, J.; Schivo, M.
1987-01-01
A program for the transients simulation thermohydraulic calculation without loss of coolant (KWU-ENACE development) to evaluate Atucha I nuclear power plant behaviour is used. The program includes systems simulation and nuclear power plants control bonds with real parameters. The calculation results show a good agreement with the output 'protocol' of various transients of the nuclear power plant, keeping the error, in general, lesser than ± 10% from the variation of the nuclear power plant's state variables. (Author)
Power System Transient Stability Analysis through a Homotopy Analysis Method
Energy Technology Data Exchange (ETDEWEB)
Wang, Shaobu; Du, Pengwei; Zhou, Ning
2014-04-01
As an important function of energy management systems (EMSs), online contingency analysis plays an important role in providing power system security warnings of instability. At present, N-1 contingency analysis still relies on time-consuming numerical integration. To save computational cost, the paper proposes a quasi-analytical method to evaluate transient stability through time domain periodic solutions’ frequency sensitivities against initial values. First, dynamic systems described in classical models are modified into damping free systems whose solutions are either periodic or expanded (non-convergent). Second, because the sensitivities experience sharp changes when periodic solutions vanish and turn into expanded solutions, transient stability is assessed using the sensitivity. Third, homotopy analysis is introduced to extract frequency information and evaluate the sensitivities only from initial values so that time consuming numerical integration is avoided. Finally, a simple case is presented to demonstrate application of the proposed method, and simulation results show that the proposed method is promising.
Failure analysis of carbide fuels under transient overpower (TOP) conditions
International Nuclear Information System (INIS)
Nguyen, D.H.
1980-06-01
The failure of carbide fuels in the Fast Test Reactor (FTR) under Transient Overpower (TOP) conditions has been examined. The Beginning-of-Cycle Four (BOC-4) all-oxide base case, at $.50/sec ramp rate was selected as the reference case. A coupling between the advanced fuel performance code UNCLE-T and HCDA Code MELT-IIIA was necessary for the analysis. UNCLE-T was used to determine cladding failure and fuel preconditioning which served as initial conditions for MELT-III calculations. MELT-IIIA determined the time of molten fuel ejection from fuel pin
Bancă, Gheorghe; Ivan, Florian; Iozsa, Daniel; Nisulescu, Valentin
2017-10-01
Currently, the tendency of the car manufacturers is to continue the expansion of the global production of SUVs (Sport Utility Vehicle), while observing the requirements imposed by the new pollution standards by developing new technologies like DHEP (Diesel Hybrid Electric Powertrain). Experience has shown that the transient regimes are the most difficult to control from an economic and ecological perspective. As a result, this paper will highlight the behaviour of such engines that are provided in a middle class SUV (Sport Utility Vehicle), which operates in such states. We selected the transient regimes characteristic to the NMVEG (New Motor Vehicle Emissions Group) cycle. The investigations using the modelling platform AMESim allowed for rigorous interpretations for the 16 acceleration and 18 deceleration states. The results obtained from the simulation will be validated by experiments.
Steady State and Transient Analysis of Induction Motor Driving a ...
African Journals Online (AJOL)
The importance of using a digital computer in studying the performance of Induction machine under steady and transient states is presented with computer results which show the transient behaviour of 3-phase machine during balanced and unbalanced conditions. The computer simulation for these operating conditions is ...
Pressure Transient Analysis of Dual Fractal Reservoir
Directory of Open Access Journals (Sweden)
Xiao-Hua Tan
2013-01-01
Full Text Available A dual fractal reservoir transient flow model was created by embedding a fracture system simulated by a tree-shaped fractal network into a matrix system simulated by fractal porous media. The dimensionless bottom hole pressure model was created using the Laplace transform and Stehfest numerical inversion methods. According to the model's solution, the bilogarithmic type curves of the dual fractal reservoirs are illustrated, and the influence of different fractal factors on pressure transient responses is discussed. This semianalytical model provides a practical and reliable method for empirical applications.
Vincent, Charles C.J.; Kok, Jacobus B.W.
1992-01-01
The two-phase closed loop thermosyphon is investigated with emphasis on the overall performance in transient operation. The control volume approach is the base of a global analysis describing the motion of vapor and liquid phases of the thermosyphon system in one-dimensional equations. Interfacial
DEFF Research Database (Denmark)
Federico, de Bosio; Pastorelli, Michele; Antonio DeSouza Ribeiro, Luiz
2016-01-01
State feedback coupling between the capacitor voltage and inductor current deteriorates notably the performance during transients of voltage and current regulators in stand-alone systems based on voltage source inverters. A decoupling technique is proposed, considering the limitations introduced...... by system delays. Laboratory experiments were executed in compliance with the normative for Uninterruptible Power Supply systems to prove the developed analysis....
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)
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)
Thermal-hydraulic analysis of PWR cores in transient condition
International Nuclear Information System (INIS)
Silva Galetti, M.R. da.
1984-01-01
A calculational methodology for thermal - hydraulic analysis of PWR cores under steady-state and transient condition was selected and made available to users. An evaluation of the COBRA-IIIP/MIT code, used for subchannel analysis, was done through comparison of the code results with experimental data on steady state and transient conditions. As a result, a comparison study allowing spatial and temporal localization of critical heat flux was obtained. A sensitivity study of the simulation model to variations in some empirically determined parameter is also presented. Two transient cases from Angra I FSAR were analysed, showing the evolution of minimum DNBR with time. (Author) [pt
Adaptive Nodal Transport Methods for Reactor Transient Analysis
Energy Technology Data Exchange (ETDEWEB)
Thomas Downar; E. Lewis
2005-08-31
Develop methods for adaptively treating the angular, spatial, and time dependence of the neutron flux in reactor transient analysis. These methods were demonstrated in the DOE transport nodal code VARIANT and the US NRC spatial kinetics code, PARCS.
Transient thermal analysis of a space reactor power system
International Nuclear Information System (INIS)
Gaeta, M.J.; Best, F.R.
1993-01-01
Space nuclear power systems utilize materials and processes that are completely different from terrestrial reactor systems. Therefore, the tools used to analyze ground-based systems are inappropriate for space reactor design and analysis. The purpose of this study was to develop a space reactor transient analysis tool and to apply this tool to scenarios of interest. The scope of the simulation includes the thermal and neutronic behavior of a liquid-metal-cooled fast reactor, the electrical and thermal performance of the thermoelectric generators, the thermal dynamics of heat pipe radiators, and the thermal behavior of the coolant piping between major components. The thermal model of the system is explicitly coupled to a momentum model of the primary and secondary coolant loops. A one-dimensional conduction model is employed in all solid component models. The reactor model includes an expression for energy generation due to fission and decay heat. The thermoelectric heat exchanger model accounts for thermal energy conversion to useful electrical output. The two-node radiator heat pipe model includes normal operation as well as limited heat pipe operation under sonic limit conditions. The reactor, thermoelectric heat exchanger, and heat pipe models are coupled explicitly by the coolant piping thermal model. The computer program is used to simulate a variety of transients including reactor power changer, degradation of the radiator, and a temporary open circuit condition on the thermoelectrics
International Nuclear Information System (INIS)
Lindley, Benjamin A.; Ahmad, Ali; Zainuddin, N. Zara; Franceschini, Fausto; Parks, Geoffrey T.
2014-01-01
Highlights: • We present a core analysis for a thorium-transuranic fuelled reduced-moderation PWR. • There is the possibility of positive reactivity in severe large break LOCAs. • Mechanical shim is used to control reactivity within power peaking constraints. • Adequate shutdown margin can be achieved with B 4 C control rods are required. • The response to a rod ejection accident is within likely licensing limits. - Abstract: It is difficult to perform multiple recycle of transuranic (TRU) isotopes in PWRs as the moderator temperature coefficient (MTC) tends to become positive after a few recycles and the core may have positive reactivity when fully voided. Due to the favourable impact on the MTC fostered by use of thorium (Th), the possibility of performing Th–TRU multiple-recycle in reduced-moderation PWRs (RMPWRs) is under consideration. Heterogeneous fuel design with spatial separation of Th–U and Th–TRU is necessary to improve neutronic performance. This can take the form of a heterogeneous fuel assembly (TPUC), or whole assembly heterogeneity (WATU). Satisfactory discharge burn-up can be maintained while ensuring negative MTC, with the pin diameter of a standard PWR increased from 9.5 to 11 mm. However, the reactivity becomes positive when the coolant density in the core becomes extremely low. This could lead to positive reactivity in some loss of coolant accident (LOCA) scenarios, for example a surge line break, if the reactor does not trip. To protect against this beyond design basis accident, a second redundant set of shutdown rods is added to the reactor, so that either the usual or secondary rods can trip the reactor when there is zero coolant in the core. Even so, this condition is likely to be concerning from a regulatory standpoint. Reactivity control is a key challenge due to the reduced worth of neutron absorbers and their detrimental effect on the void coefficients, especially when diluted, as is the case for soluble boron
Transient safety performance of the PRISM innovative liquid metal reactor
International Nuclear Information System (INIS)
Magee, P.M.; Dubberley, A.E.; Rhow, S.K.; Wu, T.
1988-01-01
The PRISM sodium-cooled reactor concept utilizes passive safety characteristics and modularity to increase performance margins, improve licensability, reduce owner's risk and reduce costs. The relatively small size of each reactor module (471 MWt) facilitates the use of passive self-shutdown and shutdown heat removal features, which permit design simplification and reduction of safety-related systems. Key to the transient performance is the inherent negative reactivity feedback characteristics of the core design resulting from the use of metal (U-Pu-Zr) swing, and very low control rod runout worth. Selected beyond design basis events relying only on these core design features are analyzed and the design margins summarized to demonstrate the advancement in reactor safety achieved with the PRISM design concept
Lightning transient analysis in wind turbine blades
DEFF Research Database (Denmark)
Candela Garolera, Anna; Holbøll, Joachim; Madsen, Søren Find
2013-01-01
The transient behavior of lightning surges in the lightning protection system of wind turbine blades has been investigated in this paper. The study is based on PSCAD models consisting of electric equivalent circuits with lumped and distributed parameters involving different lightning current...... waveforms. The aim of the PSCAD simulations is to study the voltages induced by the lightning current in the blade that may cause internal arcing. With this purpose, the phenomenon of current reflections in the lightning down conductor of the blade and the electromagnetic coupling between the down conductor...... and other internal conductive elements of the blade is studied. Finally, several methods to prevent internal arcing are discussed in order to improve the lightning protection of the blade....
Transient analysis for a system with a tilted disc check valve
International Nuclear Information System (INIS)
Jeung, Jaesik; Lee, Kyukwang; Cho, Daegwan
2014-01-01
Check valves are used to prevent reverse flow conditions in a variety of systems in nuclear power plants. When a check valve is closed by a reverse flow, the transient load can jeopardize the structural integrity on the piping system and its supports. It may also damage intended function of the in-line components even though the severity of the load differs and depends strongly on types of the check valves. To incorporate the transient load in the piping system, it is very important to properly predict the system response to transients such as a check valve closure accompanied by pump trip and to evaluate the system transient. The one-dimensional transient simulation codes such as the RELAP5/MOD3.3 and TRACE were used. There has not been a single model that integrates the two codes to handle the behavior of a tilted disc check valve, which is designed to mitigate check valve slams by shorting the travel of the disc. In this paper a model is presented to predict the dynamic motion of a tilted disc check valve in the transient simulation using the RELAP5/MOD3.3 code and the model is incorporated in a system transient analysis using control variables of the code. In addition, transient analysis for Essential Service Water (ESW) system is performed using the proposed model and the associated load is evaluated for the system. (author)
Computer Models for IRIS Control System Transient Analysis
International Nuclear Information System (INIS)
Gary D Storrick; Bojan Petrovic; Luca Oriani
2007-01-01
This report presents results of the Westinghouse work performed under Task 3 of this Financial Assistance Award and it satisfies a Level 2 Milestone for the project. Task 3 of the collaborative effort between ORNL, Brazil and Westinghouse for the International Nuclear Energy Research Initiative entitled 'Development of Advanced Instrumentation and Control for an Integrated Primary System Reactor' focuses on developing computer models for transient analysis. This report summarizes the work performed under Task 3 on developing control system models. The present state of the IRIS plant design--such as the lack of a detailed secondary system or I and C system designs--makes finalizing models impossible at this time. However, this did not prevent making considerable progress. Westinghouse has several working models in use to further the IRIS design. We expect to continue modifying the models to incorporate the latest design information until the final IRIS unit becomes operational. Section 1.2 outlines the scope of this report. Section 2 describes the approaches we are using for non-safety transient models. It describes the need for non-safety transient analysis and the model characteristics needed to support those analyses. Section 3 presents the RELAP5 model. This is the highest-fidelity model used for benchmark evaluations. However, it is prohibitively slow for routine evaluations and additional lower-fidelity models have been developed. Section 4 discusses the current Matlab/Simulink model. This is a low-fidelity, high-speed model used to quickly evaluate and compare competing control and protection concepts. Section 5 describes the Modelica models developed by POLIMI and Westinghouse. The object-oriented Modelica language provides convenient mechanisms for developing models at several levels of detail. We have used this to develop a high-fidelity model for detailed analyses and a faster-running simplified model to help speed the I and C development process. Section
An approximate analysis for general film condensation transients
International Nuclear Information System (INIS)
Flik, M.I.; Tien, C.L.
1989-01-01
This work presents a simple, powerful technique for analyzing a broad class of film condensation transients. The analysis shows that general film condensation transients are governed by the propagation of a kinematic wave along the film. Scaling arguments establish conditions for the use of quasi-steady profiles in the integral conservation equations. An elementary method permits simple solutions of the governing hyperbolic equation for time-step changes with arbitrary initial conditions. The application of this method yields closed-form solutions for step changes of body force, vapor shear, and wall temperature for a laminar film and for step changes of body force and wall temperature for a film within a porous medium. These approximate results agree excellently with numerical solutions of the complete boundary-layer equations. This technique has applications to a wide class of film condensation transients and to film boiling and convective vaporization transients
TREAT Transient Analysis Benchmarking for the HEU Core
Energy Technology Data Exchange (ETDEWEB)
Kontogeorgakos, D. C. [Argonne National Lab. (ANL), Argonne, IL (United States); Connaway, H. M. [Argonne National Lab. (ANL), Argonne, IL (United States); Wright, A. E. [Argonne National Lab. (ANL), Argonne, IL (United States)
2014-05-01
This work was performed to support the feasibility study on the potential conversion of the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory from the use of high enriched uranium (HEU) fuel to the use of low enriched uranium (LEU) fuel. The analyses were performed by the GTRI Reactor Conversion staff at the Argonne National Laboratory (ANL). The objective of this study was to benchmark the transient calculations against temperature-limited transients performed in the final operating HEU TREAT core configuration. The MCNP code was used to evaluate steady-state neutronics behavior, and the point kinetics code TREKIN was used to determine core power and energy during transients. The first part of the benchmarking process was to calculate with MCNP all the neutronic parameters required by TREKIN to simulate the transients: the transient rod-bank worth, the prompt neutron generation lifetime, the temperature reactivity feedback as a function of total core energy, and the core-average temperature and peak temperature as a functions of total core energy. The results of these calculations were compared against measurements or against reported values as documented in the available TREAT reports. The heating of the fuel was simulated as an adiabatic process. The reported values were extracted from ANL reports, intra-laboratory memos and experiment logsheets and in some cases it was not clear if the values were based on measurements, on calculations or a combination of both. Therefore, it was decided to use the term “reported” values when referring to such data. The methods and results from the HEU core transient analyses will be used for the potential LEU core configurations to predict the converted (LEU) core’s performance.
Transient Reliability Analysis Capability Developed for CARES/Life
Nemeth, Noel N.
2001-01-01
The CARES/Life software developed at the NASA Glenn Research Center provides a general-purpose design tool that predicts the probability of the failure of a ceramic component as a function of its time in service. This award-winning software has been widely used by U.S. industry to establish the reliability and life of a brittle material (e.g., ceramic, intermetallic, and graphite) structures in a wide variety of 21st century applications.Present capabilities of the NASA CARES/Life code include probabilistic life prediction of ceramic components subjected to fast fracture, slow crack growth (stress corrosion), and cyclic fatigue failure modes. Currently, this code can compute the time-dependent reliability of ceramic structures subjected to simple time-dependent loading. For example, in slow crack growth failure conditions CARES/Life can handle sustained and linearly increasing time-dependent loads, whereas in cyclic fatigue applications various types of repetitive constant-amplitude loads can be accounted for. However, in real applications applied loads are rarely that simple but vary with time in more complex ways such as engine startup, shutdown, and dynamic and vibrational loads. In addition, when a given component is subjected to transient environmental and or thermal conditions, the material properties also vary with time. A methodology has now been developed to allow the CARES/Life computer code to perform reliability analysis of ceramic components undergoing transient thermal and mechanical loading. This means that CARES/Life will be able to analyze finite element models of ceramic components that simulate dynamic engine operating conditions. The methodology developed is generalized to account for material property variation (on strength distribution and fatigue) as a function of temperature. This allows CARES/Life to analyze components undergoing rapid temperature change in other words, components undergoing thermal shock. In addition, the capability has
An analysis of power transients observed in SPERT I reactors
International Nuclear Information System (INIS)
Clancy, B.E.; Connolly, J.W.; Harrington, B.V.
1976-04-01
The analytical method described in Part I of this series has been applied to the calculation of spert I transients performed with higher initial moderator temperatures and also to those performed in a highly undermoderated core. Reasonable agreement has been obtained between calculated and experimental burst data. (author)
Modeling the Transient Effects of High Energy Subsystems on High-Performance Aerospace Systems
Gvozdich, Grant Gregory
2011-01-01
As directed energy technology continues to evolve and become a viable weapon alternative, a need exists to investigate the impacts of these applications without a â plug-and-checkâ method, but rather with an analysis governed by fundamental principles. This thesis examines the transient thermal loads that a high-energy weapon system introduces into a high performance aircraft using fundamental thermodynamic and heat transfer analyses. The high-energy weapon system employed in this resea...
A fast reactor transient analysis methodology for personal computers
International Nuclear Information System (INIS)
Ott, K.O.
1993-01-01
A simplified model for a liquid-metal-cooled reactor (LMR) transient analysis, in which point kinetics as well as lumped descriptions of the heat transfer equations in all components are applied, is converted from a differential into an integral formulation. All 30 differential balance equations are implicitly solved in terms of convolution integrals. The prompt jump approximation is applied as the strong negative feedback effectively keeps the net reactivity well below prompt critical. After implicit finite differencing of the convolution integrals, the kinetics equation assumes a new form, i.e., the quadratic dynamics equation. In this integral formulation, the initial value problem of typical LMR transients can be solved with large item steps (initially 1 s, later up to 256 s). This then makes transient problems amenable to a treatment on personal computer. The resulting mathematical model forms the basis for the GW-BASIC program LMR transient calculation (LTC) program. The LTC program has also been converted to QuickBASIC. The running time for a 10-h transient overpower transient is then ∼40 to 10 s, depending on the hardware version (286, 386, or 486 with math coprocessors)
Transient electromagnetic analysis in tokamaks using TYPHOON code
International Nuclear Information System (INIS)
Belov, A.V.; Duke, A.E.; Korolkov, M.D.; Kotov, V.L.; Kukhtin, V.P.; Lamzin, E.A.; Sytchevsky, S.E.
1996-01-01
The transient electromagnetic analysis of conducting structures in tokamaks is presented. This analysis is based on a three-dimensional thin conducting shell model. The finite element method has been used to solve the corresponding integrodifferential equation. The code TYPHOON has been developed to calculate transient processes in tokamaks. Calculation tests and the code verification have been carried out. The calculation results of eddy current and force distibution and a.c. losses for different construction elements for both ITER and TEXTOR tokamaks magnetic systems are presented. (orig.)
ANALYSIS OF THE TRANSIENT STABILITY LIMIT OF NIGERIA'S ...
African Journals Online (AJOL)
user
network engineers have to devise methodologies based on the dynamic stability analysis. This motivates the development of power system transient stability model presented herein. The developed model is thus applied to a specimen of the Nigeria's transmission power system, i.e. the Ikeja-West Sub-network. This choice ...
ANALYSIS OF THE TRANSIENT STABILITY LIMIT OF NIGERIA'S ...
African Journals Online (AJOL)
This choice is influenced by the fact that the Ikeja-West sub-network is the hub of power transmission arteries in Nigeria. Thus the Electrical Transient and Analysis Program (ETAP) software is deployed to operate on the ensuing model. This then leads to generating a series of results that demonstrates the different scenarios ...
Transient stability analysis of a distribution network with distributed generators
Xyngi, I.; Ishchenko, A.; Popov, M.; Van der Sluis, L.
2009-01-01
This letter describes the transient stability analysis of a 10-kV distribution network with wind generators, microturbines, and CHP plants. The network being modeled in Matlab/Simulink takes into account detailed dynamic models of the generators. Fault simulations at various locations are
Perturbation analysis of transient population dynamics using matrix projection models
DEFF Research Database (Denmark)
Stott, Iain
2016-01-01
to different applications: choosing a method to use may be challenging. Here, I review existing methods for prospective transient perturbation analysis, and identify a number of key considerations for ecologists when choosing a method. These include the approach taken in calculating the perturbation, the type...
Transient Safety Analysis of Fast Spectrum TRU Burning LWRs with Internal Blankets
Energy Technology Data Exchange (ETDEWEB)
Downar, Thomas [Univ. of Michigan, Ann Arbor, MI (United States); Zazimi, Mujid [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Hill, Bob [Argonne National Lab. (ANL), Argonne, IL (United States)
2015-01-31
The objective of this proposal was to perform a detailed transient safety analysis of the Resource-Renewable BWR (RBWR) core designs using the U.S. NRC TRACE/PARCS code system. This project involved the same joint team that has performed the RBWR design evaluation for EPRI and therefore be able to leverage that previous work. And because of their extensive experience with fast spectrum reactors and parfait core designs, ANL was also part the project team. The principal outcome of this project was the development of a state-of-the-art transient analysis capability for GEN-IV reactors based on Monte Carlo generated cross sections and the US NRC coupled code system TRACE/PARCS, and a state-of-the-art coupled code assessment of the transient safety performance of the RBWR.
Verification and validation of COBRA-SFS transient analysis capability
International Nuclear Information System (INIS)
Rector, D.R.; Michener, T.E.; Cuta, J.M.
1998-05-01
This report provides documentation of the verification and validation testing of the transient capability in the COBRA-SFS code, and is organized into three main sections. The primary documentation of the code was published in September 1995, with the release of COBRA-SFS, Cycle 2. The validation and verification supporting the release and licensing of COBRA-SFS was based solely on steady-state applications, even though the appropriate transient terms have been included in the conservation equations from the first cycle. Section 2.0, COBRA-SFS Code Description, presents a capsule description of the code, and a summary of the conservation equations solved to obtain the flow and temperature fields within a cask or assembly model. This section repeats in abbreviated form the code description presented in the primary documentation (Michener et al. 1995), and is meant to serve as a quick reference, rather than independent documentation of all code features and capabilities. Section 3.0, Transient Capability Verification, presents a set of comparisons between code calculations and analytical solutions for selected heat transfer and fluid flow problems. Section 4.0, Transient Capability Validation, presents comparisons between code calculations and experimental data obtained in spent fuel storage cask tests. Based on the comparisons presented in Sections 2.0 and 3.0, conclusions and recommendations for application of COBRA-SFS to transient analysis are presented in Section 5.0
Analysis of operator's behaviour under accidental transients
International Nuclear Information System (INIS)
Llory, M.; Lemaitre, D.; Griffon-Fouco, C.; Meslin, B.
1992-01-01
Since 1979, EDF has been conducting intensive test campaigns on full-scale PWR simulators in order to study and improve the operators behaviour under incident as well as accident conditions. This paper presents some results obtained during tests carried out in 1986 on the P4 (1300 MWe power plant series) simulators of the Paluel Training Center. These results essentially concern the observed deviations, the diagnosis and the safety engineer's role. They are compared with the results of previous tests on 900 MWe unit simulators. The test organization and methodology, the result analysis methods and the biases introduced by this kind of test are also discussed. (author). 7 refs, 1 fig., 6 figs
An Effective Distributed Model for Power System Transient Stability Analysis
Directory of Open Access Journals (Sweden)
MUTHU, B. M.
2011-08-01
Full Text Available The modern power systems consist of many interconnected synchronous generators having different inertia constants, connected with large transmission network and ever increasing demand for power exchange. The size of the power system grows exponentially due to increase in power demand. The data required for various power system applications have been stored in different formats in a heterogeneous environment. The power system applications themselves have been developed and deployed in different platforms and language paradigms. Interoperability between power system applications becomes a major issue because of the heterogeneous nature. The main aim of the paper is to develop a generalized distributed model for carrying out power system stability analysis. The more flexible and loosely coupled JAX-RPC model has been developed for representing transient stability analysis in large interconnected power systems. The proposed model includes Pre-Fault, During-Fault, Post-Fault and Swing Curve services which are accessible to the remote power system clients when the system is subjected to large disturbances. A generalized XML based model for data representation has also been proposed for exchanging data in order to enhance the interoperability between legacy power system applications. The performance measure, Round Trip Time (RTT is estimated for different power systems using the proposed JAX-RPC model and compared with the results obtained using traditional client-server and Java RMI models.
Mixed time integration methods for transient thermal analysis of structures, appendix 5
Liu, W. K.
1982-01-01
Mixed time integration methods for transient thermal analysis of structures are studied. An efficient solution procedure for predicting the thermal behavior of aerospace vehicle structures was developed. A 2D finite element computer program incorporating these methodologies is being implemented. The performance of these mixed time finite element algorithms can then be evaluated employing the proposed example problem.
Transient Performance Improvement Circuit (TPIC)s for DC-DC converter applications
Lim, Sungkeun
designed to improve the performance of an LDO regulator during output current transients. A TPIC for a LDO regulator is proposed to reduce the over voltage spike settling time. During a load current step down transient, the only current discharging path is a light load current. However, it takes a long time to discharge the current charged in the output capacitors with the light load current. The proposed TPIC will make an additional current discharging path to reduce the long settling time. By reducing the settling time, the load current transient frequency of the LDO regulator can be increased. A Ripple Cancellation Circuit (RCC) is proposed to reduce the output voltage ripple. The RCC has a very similar concept with the TPIC which is sinking or injecting additional current to the power stage to compensate the inductor ripple current. The proposed TPICs and RCC have been implemented with a 0.6m CMOS process. A single-phase VR, a 4SBB converter, and a LDO regulator have been utilized with the proposed TPIC to evaluate its performance. The theoretical analysis will be confirmed by Cadence simulation results and experimental results.
Transient Analysis of STELLA-2 using MARS-LMR
Energy Technology Data Exchange (ETDEWEB)
Lee, Jewhan; Kim, Hyungmo; Lee, Yong-Bum; Yoon, Jung; Eoh, Jaehyuk; Jeong, Ji-Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-10-15
The Sodium Integral Effect Test Loop for Safety Simulation and Assessment (STELLA) program is one of the key activities and the basic design of STELLA-2 facility has been completed in 2015. The STELLA-2 is a scaled facility including all the major components of PGSFR and is able to simulate the transient behavior. For STELLA-2 design evaluation, the representative design basis event (DBE) analysis was conducted by MARS-LMR with the same assumption and same approach used in PGSFR analysis. In this paper, the method and result of MARS-LMR transient analysis are described and also the comparison result with the PGSFR is illustrated. As a part of STELLA-2 design evaluation, MARS-LMR input was prepared to analyze the steady-state and transient behavior. The LOF condition with LOOP assumption was selected for the representative DBE and the result was compared with PGSFR analysis. Some of the values were inconsistent with PGSFR and the reason of difference was also discussed.
RELAP5/MOD2: for PWR transient analysis
International Nuclear Information System (INIS)
Ransom, V.H.
1983-01-01
RELAP5 is a light water reactor system transient simulation code for use in nuclear plant safety analysis. Development of a new version, RELAP5/MOD2, has been completed and will be released to the United States Nuclear Regulatory Commission during September of 1983. The new and improved modeling capability of RELAP5/MOD2 is described and some developmental assessment results are presented. The future plans for extension to severe accident modeling are briefly discussed
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
TRAWA, a transient analysis code for water reactions
International Nuclear Information System (INIS)
Rajamaeki, M.
1976-06-01
TRAWA is a transient analysis code for water reactors. It solves the two-group neutron diffusion equations simultaneously with the heat conduction equations and the two-phase hydraulic equations for one or more channels. At most one-dimensional submodels are used. Neither thermal nor hydraulic mixing appear between channels. Doppler, coolant density, coolant temperature, and soluble poison density feedbacks due to the thermohydraulics of the channels are described by using polynomial expansions for the group constants. The hydraulic circuit outside the reactor core consists of by-pass channel and risers with two-phase flow and of pump lines with incompressible flow. Nontrivial implicit methods are employed in the discretization of the equations to allow for sparse spatial mesh and flexible choice of time steps. Various transients can be calculated by applying external disturbances. The code is extensively supplied by input and output capabilities. TRAWA is written in FORTRAN V for UNIVAC 1108 computer. (author)
Sellers, J. F.
1973-01-01
The transient performance of two concepts for control of vertical takeoff aircraft remote lift fans is analyzed and discussed. Both concepts employ flow transfer between pairs of lift fans located in separate parts of the aircraft in order to obtain attitude control moments for hover and low-speed flight. The results presented are from a digital computer, dynamic analysis of the YJ97/LF460 remote drive turbofan. The transient responses of the two systems are presented for step demands in lift and moment.
Transient performance of flow in PWR reactor circuits
International Nuclear Information System (INIS)
Hirdes, V.R.T.R.; Carajilescov, P.
1988-12-01
Generally, PWR's are designed with several primary loops, each one provided with a pump to circulate the coolant through the core. If one or more of these pumps fail, there would be a decrease in reactor flow rate which cause coolant phase change in the core and components overheating. The present work establishes a simulation model for pump failure in PWR's and the SARDAN-FLOW computes code was developed, considering any combination of such failures. Based on the data of Angra I, several accident and operational transient conditions were simulated. (author) [pt
Transient performance of flow in circuits of PWR type reactors
International Nuclear Information System (INIS)
Hirdes, V.R.; Carajilescov, P.
1988-09-01
Generally, PWR's are designed with several primary loops, each one provided with a pump to circulate the coolant through the core. If one or more of these pumps fail, there would be a decrease in reactor flow rate which could cause coolant phase change in the core and components overheating. The present work establishes a simulation model for pump failure in PWR's and the SARDAN-FLOW computes code was developed, considering any combination of such failures. Based on the data of Angra I, several accident and operational transient conditions were simulated. (author) [pt
Nastran nonlinear dynamic transient accident analysis for FFTF reactor component
International Nuclear Information System (INIS)
Lujan, R.A.; Chenault, D.M.; Go, J.C.
1976-01-01
A nonlinear dynamic transient analysis merging hand calculations and the NASTRAN structural analysis computer code was conducted for a Fast Flux Test Facility in-reactor test assembly during an extremely unlikely design basis accidental event which is considered a Hypothetical Core Disruptive Accident (HCDA). The finite element modeling of the problem took advantage of NASTRAN's versatility to create loads and nonlinear elements not previously found in NASTRAN's library. The structural criteria for the test assembly to withstand an HCDA stipulates that the test assembly and its spoolpiece shall remain integral with the reactor head such that missiles are not generated
TRAB, a transient analysis program for BWR. Part 1
International Nuclear Information System (INIS)
Rajamaeki, Markku.
1980-03-01
TRAB is a transient analysis program for BWR. The present report describes its principles. The program has been developed from TRAWA-program. It models the interior of the pressure vessel and related subsystems of BWR viz. reactor core, recirculation loop including the upper part of the vessel, recirculation pumps, incoming and outgoing flow systems, and control and protection systems. Concerning core phenomena and all flow channel hydraulics the submodels are one-dimensional of main features. The geometry is very flexible. The program has been made particularly to simulate various reactivity transients, but it is applicable more generally to reactor incidents and accidents in which no flow reversal or no emptying of the circuit must occur below the water level. The program is extensively supplied by input and output capabilities. The user can act upon the simulation of a transient by defining external disturbances, scheduled timevariations for any system variable, by modeling new subsystems, which are representable with ordinary linear differential equations, and by defining relations of functional form between system variables. The run of the program can be saved and restarted. (author)
Analysis of forced convective transient boiling by homogeneous model of two-phase flow
International Nuclear Information System (INIS)
Kataoka, Isao
1985-01-01
Transient forced convective boiling is of practical importance in relation to the accident analysis of nuclear reactor etc. For large length-to-diameter ratio, the transient boiling characteristics are predicted by transient two-phase flow calculations. Based on homogeneous model of two-phase flow, the transient forced convective boiling for power and flow transients are analysed. Analytical expressions of various parameters of transient two-phase flow have been obtained for several simple cases of power and flow transients. Based on these results, heat flux, velocity and time at transient CHF condition are predicted analytically for step and exponential power increases, and step, exponential and linear velocity decreases. The effects of various parameters on heat flux, velocity and time at transient CHF condition have been clarified. Numerical approach combined with analytical method is proposed for more complicated cases. Solution method for pressure transient are also described. (author)
Analysis and computer simulation for transient flow in complex system of liquid piping
International Nuclear Information System (INIS)
Mitry, A.M.
1985-01-01
This paper is concerned with unsteady state analysis and development of a digital computer program, FLUTRAN, that performs a simulation of transient flow behavior in a complex system of liquid piping. The program calculates pressure and flow transients in the liquid filled piping system. The analytical model is based on the method of characteristics solution to the fluid hammer continuity and momentum equations. The equations are subject to wide variety of boundary conditions to take into account the effect of hydraulic devices. Water column separation is treated as a boundary condition with known head. Experimental tests are presented that exhibit transients induced by pump failure and valve closure in the McGuire Nuclear Station Low Level Intake Cooling Water System. Numerical simulation is conducted to compare theory with test data. Analytical and test data are shown to be in good agreement and provide validation of the model
Dynamic remedial action scheme using online transient stability analysis
Shrestha, Arun
Economic pressure and environmental factors have forced the modern power systems to operate closer to their stability limits. However, maintaining transient stability is a fundamental requirement for the operation of interconnected power systems. In North America, power systems are planned and operated to withstand the loss of any single or multiple elements without violating North American Electric Reliability Corporation (NERC) system performance criteria. For a contingency resulting in the loss of multiple elements (Category C), emergency transient stability controls may be necessary to stabilize the power system. Emergency control is designed to sense abnormal conditions and subsequently take pre-determined remedial actions to prevent instability. Commonly known as either Remedial Action Schemes (RAS) or as Special/System Protection Schemes (SPS), these emergency control approaches have been extensively adopted by utilities. RAS are designed to address specific problems, e.g. to increase power transfer, to provide reactive support, to address generator instability, to limit thermal overloads, etc. Possible remedial actions include generator tripping, load shedding, capacitor and reactor switching, static VAR control, etc. Among various RAS types, generation shedding is the most effective and widely used emergency control means for maintaining system stability. In this dissertation, an optimal power flow (OPF)-based generation-shedding RAS is proposed. This scheme uses online transient stability calculation and generator cost function to determine appropriate remedial actions. For transient stability calculation, SIngle Machine Equivalent (SIME) technique is used, which reduces the multimachine power system model to a One-Machine Infinite Bus (OMIB) equivalent and identifies critical machines. Unlike conventional RAS, which are designed using offline simulations, online stability calculations make the proposed RAS dynamic and adapting to any power system
International Nuclear Information System (INIS)
Powell, Jade; Heng, Ik Siong; Torres-Forné, Alejandro; Font, José A; Lynch, Ryan; Trifirò, Daniele; Cuoco, Elena; Cavaglià, Marco
2017-01-01
The data taken by the advanced LIGO and Virgo gravitational-wave detectors contains short duration noise transients that limit the significance of astrophysical detections and reduce the duty cycle of the instruments. As the advanced detectors are reaching sensitivity levels that allow for multiple detections of astrophysical gravitational-wave sources it is crucial to achieve a fast and accurate characterization of non-astrophysical transient noise shortly after it occurs in the detectors. Previously we presented three methods for the classification of transient noise sources. They are Principal Component Analysis for Transients (PCAT), Principal Component LALInference Burst (PC-LIB) and Wavelet Detection Filter with Machine Learning (WDF-ML). In this study we carry out the first performance tests of these algorithms on gravitational-wave data from the Advanced LIGO detectors. We use the data taken between the 3rd of June 2015 and the 14th of June 2015 during the 7th engineering run (ER7), and outline the improvements made to increase the performance and lower the latency of the algorithms on real data. This work provides an important test for understanding the performance of these methods on real, non stationary data in preparation for the second advanced gravitational-wave detector observation run, planned for later this year. We show that all methods can classify transients in non stationary data with a high level of accuracy and show the benefits of using multiple classifiers. (paper)
Analytical transient analysis of Peltier device for laser thermal tuning
Sheikhnejad, Yahya; Vujicic, Zoran; Almeida, Álvaro J.; Bastos, Ricardo; Shahpari, Ali; Teixeira, António L.
2017-08-01
Recently, industrial trends strongly favor the concepts of high density, low power consumption and low cost applications of Datacom and Telecom pluggable transceiver modules. Hence, thermal management plays an important role, especially in the design of high-performance compact optical transceivers. Extensive care should be taken on wavelength drift for thermal tuning lasers using thermoelectric cooler and indeed, accurate expression is needed to describe transient characteristics of the Peltier device to achieve maximum controllability. In this study, the exact solution of governing equation is presented, considering Joule heating, heat conduction, heat flux of laser diode and thermoelectric effect in one dimension.
Momentum integral network method for thermal-hydraulic transient analysis
International Nuclear Information System (INIS)
Van Tuyle, G.J.
1983-01-01
A new momentum integral network method has been developed, and tested in the MINET computer code. The method was developed in order to facilitate the transient analysis of complex fluid flow and heat transfer networks, such as those found in the balance of plant of power generating facilities. The method employed in the MINET code is a major extension of a momentum integral method reported by Meyer. Meyer integrated the momentum equation over several linked nodes, called a segment, and used a segment average pressure, evaluated from the pressures at both ends. Nodal mass and energy conservation determined nodal flows and enthalpies, accounting for fluid compression and thermal expansion
Mixed time integration methods for transient thermal analysis of structures
Liu, W. K.
1983-01-01
The computational methods used to predict and optimize the thermal-structural behavior of aerospace vehicle structures are reviewed. In general, two classes of algorithms, implicit and explicit, are used in transient thermal analysis of structures. Each of these two methods has its own merits. Due to the different time scales of the mechanical and thermal responses, the selection of a time integration method can be a difficult yet critical factor in the efficient solution of such problems. Therefore mixed time integration methods for transient thermal analysis of structures are being developed. The computer implementation aspects and numerical evaluation of these mixed time implicit-explicit algorithms in thermal analysis of structures are presented. A computationally-useful method of estimating the critical time step for linear quadrilateral element is also given. Numerical tests confirm the stability criterion and accuracy characteristics of the methods. The superiority of these mixed time methods to the fully implicit method or the fully explicit method is also demonstrated.
Fuel element thermo-mechanical analysis during transient events using the FMS and FETMA codes
International Nuclear Information System (INIS)
Hernandez Lopez Hector; Hernandez Martinez Jose Luis; Ortiz Villafuerte Javier
2005-01-01
In the Instituto Nacional de Investigaciones Nucleares of Mexico, the Fuel Management System (FMS) software package has been used for long time to simulate the operation of a BWR nuclear power plant in steady state, as well as in transient events. To evaluate the fuel element thermo-mechanical performance during transient events, an interface between the FMS codes and our own Fuel Element Thermo Mechanical Analysis (FETMA) code is currently being developed and implemented. In this work, the results of the thermo-mechanical behavior of fuel rods in the hot channel during the simulation of transient events of a BWR nuclear power plant are shown. The transient events considered for this work are a load rejection and a feedwater control failure, which among the most important events that can occur in a BWR. The results showed that conditions leading to fuel rod failure at no time appeared for both events. Also, it is shown that a transient due load rejection is more demanding on terms of safety that the failure of a controller of the feedwater. (authors)
Steady State and Transient Fuel Rod Performance Analyses by Pad and Transuranus Codes
International Nuclear Information System (INIS)
Slyeptsov, O.; Slyeptsov, S.; Kulish, G.; Ostapov, A.; Chernov, I.
2013-01-01
The report performed under IAEA research contract No.15370/L2 describes the analysis results of WWER and PWR fuel rod performance at steady state operation and transients by means of PAD and TRANSURANUS codes. The code TRANSURANUS v1m1j09 developed by Institute for of Transuranium Elements (ITU) was used based on the Licensing Agreement N31302. The code PAD 4.0 developed by Westinghouse Electric Company was utilized in the frame of the Ukraine Nuclear Fuel Qualification Project for safety substantiation for the use of Westinghouse fuel assemblies in the mixed core of WWER-1000 reactor. The experimental data for the Russian fuel rod behavior obtained during the steady-state operation in the WWER-440 core of reactor Kola-3 and during the power transients in the core of MIR research reactor were taken from the IFPE database of the OECD/NEA and utilized for assessing the codes themselves during simulation of such properties as fuel burnup, fuel centerline temperature (FCT), fuel swelling, cladding strain, fission gas release (FGR) and rod internal pressure (RIP) in the rod burnup range of (41 - 60) GWD/MTU. The experimental data of fuel behavior at steady-state operation during seven reactor cycles presented by AREVA for the standard PWR fuel rod design were used to examine the code FGR model in the fuel burnup range of (37 - 81) GWD/MTU. (author)
Noda, Taku
Nowadays, there is quite high demand for electromagnetic transient (EMT) analysis programs and real-time simulators for power systems. In addition to the conventional demand such as overvoltage, over-current and oscillation simulations, the new demand that includes simulations of power-electronics circuits and power quality is increasing. With this background, development groups of EMT programs and real-time simulators have made progress in terms of computational performance and user experience. In Japan, Central Research Institute of Electric Power Industry has newly developed an EMT analysis program called XTAP (eXpandable Transient Analysis Program). This article overviews these international and domestic development trends of EMT analysis programs and real-time simulators.
Directory of Open Access Journals (Sweden)
Samaneh Jenab
2014-01-01
Full Text Available Application of fractional order proportional integral (FOPI controller to improve transient performance of wind turbine (WT with Doubly fed induction generator (DFIG is presented and studied in this paper. By small signal analysis, it is found that the dynamic behavior of the DFIG based WT, during the variation of operating conditions, is strongly affected by the stator dynamics. Since the DFIG electrical dynamics are nonlinear, the linear control (PI scheme cannot work properly under change in wind speed and stator modes are not damped appropriately. The proposed fractional order controller generalizes the conventional integer order PI controller whose integral order are fractional number rather than integer. This expansion can provide more flexibility in achieving control objectives. By time domain simulations, a comparative analysis is made with respect to the standard PI controller to demonstrate effectiveness of the fractional order PI controller during wind speed perturbation.
Analysis of transient fission gas behaviour in oxide fuel using BISON and TRANSURANUS
Barani, T.; Bruschi, E.; Pizzocri, D.; Pastore, G.; Van Uffelen, P.; Williamson, R. L.; Luzzi, L.
2017-04-01
The modelling of fission gas behaviour is a crucial aspect of nuclear fuel performance analysis in view of the related effects on the thermo-mechanical performance of the fuel rod, which can be particularly significant during transients. In particular, experimental observations indicate that substantial fission gas release (FGR) can occur on a small time scale during transients (burst release). To accurately reproduce the rapid kinetics of the burst release process in fuel performance calculations, a model that accounts for non-diffusional mechanisms such as fuel micro-cracking is needed. In this work, we present and assess a model for transient fission gas behaviour in oxide fuel, which is applied as an extension of conventional diffusion-based models to introduce the burst release effect. The concept and governing equations of the model are presented, and the sensitivity of results to the newly introduced parameters is evaluated through an analytic sensitivity analysis. The model is assessed for application to integral fuel rod analysis by implementation in two structurally different fuel performance codes: BISON (multi-dimensional finite element code) and TRANSURANUS (1.5D code). Model assessment is based on the analysis of 19 light water reactor fuel rod irradiation experiments from the OECD/NEA IFPE (International Fuel Performance Experiments) database, all of which are simulated with both codes. The results point out an improvement in both the quantitative predictions of integral fuel rod FGR and the qualitative representation of the FGR kinetics with the transient model relative to the canonical, purely diffusion-based models of the codes. The overall quantitative improvement of the integral FGR predictions in the two codes is comparable. Moreover, calculated radial profiles of xenon concentration after irradiation are investigated and compared to experimental data, illustrating the underlying representation of the physical mechanisms of burst release.
Transient thermal analysis of semiconductor diode lasers under pulsed operation
Veerabathran, G. K.; Sprengel, S.; Karl, S.; Andrejew, A.; Schmeiduch, H.; Amann, M.-C.
2017-02-01
Self-heating in semiconductor lasers is often assumed negligible during pulsed operation, provided the pulses are `short'. However, there is no consensus on the upper limit of pulse width for a given device to avoid-self heating. In this paper, we present an experimental and theoretical analysis of the effect of pulse width on laser characteristics. First, a measurement method is introduced to study thermal transients of edge-emitting lasers during pulsed operation. This method can also be applied to lasers that do not operate in continuous-wave mode. Secondly, an analytical thermal model is presented which is used to fit the experimental data to extract important parameters for thermal analysis. Although commercial numerical tools are available for such transient analyses, this model is more suitable for parameter extraction due to its analytical nature. Thirdly, to validate this approach, it was used to study a GaSb-based inter-band laser and an InP-based quantum cascade laser (QCL). The maximum pulse-width for less than 5% error in the measured threshold currents was determined to be 200 and 25 ns for the GaSb-based laser and QCL, respectively.
Directory of Open Access Journals (Sweden)
Sang Hwan Lee
Full Text Available BACKGROUND: Early discrimination between transient and persistent par-solid ground-glass nodules (PSNs at CT is essential for patient management. The objective of our study was to retrospectively investigate the value of texture analysis in differentiating pulmonary transient and persistent PSNs in addition to clinical and CT features. METHODS: This retrospective study was performed with IRB approval and a waiver of the requirement for patients' informed consent. From January 2007 to October 2009, we identified 77 individuals (39 men and 38 women; mean age, 55 years with 86 PSNs on thin-section chest CT. Thirty-nine PSNs in 31 individuals were transient and 47 PSNs in 46 patients were persistent. The clinical, CT, and texture features of PSNs were evaluated. To investigate the additional value of texture analysis in differentiating transient from persistent PSNs, logistic regression analysis and C-statistics were performed. RESULTS: Between transient and persistent PSNs, there were significant differences in age, gender, smoking history, and eosinophil count among the clinical features. As for thin-section CT features, there were significant differences in lesion size, solid portion size, and lesion multiplicity. In terms of texture features, there were significant differences in mean attenuation, skewness of whole PSN, attenuation ratio of whole PSN to inner solid portion, and 5-, 10-, 25-, 50-percentile CT numbers of whole PSN. Multivariate analysis revealed eosinophilia, lesion size, lesion multiplicity, mean attenuation of whole PSN, skewness of whole PSN, and 5-percentile CT number were significant independent predictors of transient PSNs. (P<0.05 C-statistics revealed that texture analysis incorporating clinical and CT features (AUC, 92.9% showed significantly higher differentiating performance of transient from persistent PSNs compared with the clinical and CT features alone (AUC, 79.0%. (P = 0.004. CONCLUSION: Texture analysis of
Investigation of transient models and performances for a doubly fed wind turbine under a grid fault
DEFF Research Database (Denmark)
Wang, M.; Zhao, B.; Li, H.
2011-01-01
of the grid-side converter and the rotor-side converter of DFIG. Secondly, the transient performances of the presented doubly fed wind turbine under a grid fault were compared and evaluated with different equivalent models, parameters and initial operational conditions. And thirdly, the effects of the active......In order to investigate the impacts of the integration of wind farms into utilities network, it is necessary to analyze the transient performances of wind turbine generation systems (WTGS) with the appropriate transient models. According to the grid code requirements for a wind turbine with doubly...... trip time. Firstly, the different mathematical models of the doubly fed wind turbine were presented, including the electromagnetic transient models of DFIG, a one-mass lumped model, a two-mass shaft flexible model of the wind turbine drive train system, and the power decoupling control strategies...
Qualitative diagnosis for transients analysis on nuclear reactors
International Nuclear Information System (INIS)
Lorre, J.P.; Dorlet, E.; Evrard, J.M.
1995-01-01
One of the major aims of an intelligent monitoring system, is the supervision task which assist the operator in understanding what occurs on a process. Failures hypotheses must be located and the inferring process must be explained. This paper demonstrate a second generation expert system (SEXTANT) decided to the transients analysis on PWR nuclear reactors. This system detects failures by simulating the process with a numerical model. A diagnosis module uses an even graph built from a causal graph model of the plant to generate hypotheses, and a numerical model to validate these hypotheses. Hypotheses are stored into scenarios which are concurrent possible interpretations of the process evolution. The approach is illustrated by an application for the analysis of the house load operation on a pressurized water reactor. (authors). 9 refs., 10 figs
THYDE-P, PWR LOCA Thermohydraulic Transient Analysis
International Nuclear Information System (INIS)
Asahi, Yoshiro
2001-01-01
1 - Description of problem or function: THYDE-P1 analyzes the behaviour of LWR plants in response to various disturbances, including the thermal hydraulic transient following a break of the primary coolant pipe system, generally referred to as a loss-of-coolant-accident (LOCA). LOCA can be considered as the most critical condition for testing the methods and models for plant dynamics, since thermal hydraulic conditions in the system change drastically during the transient. THYDE-P is capable of a complete LOCA calculation from start to complete reflooding of the core by subcooled water. The program performs steady-state adjustment, which is complete in the sense that the steady state obtained is a set of exact solutions of all the transient equations without time derivatives, not only for plant hydraulics but also for all the other phenomena in the simulation of a PWR plant. THYDE-P2 contains among others the following improvements over THYDE-P1: (1) not only the mass and momentum equations but also the energy equation are included in the non-linear implicit scheme; (2) the valve model is implemented; (3) the relaxation equation for void fraction is theoretically derived; (4) vectorized programming is implemented; (5) both EM (evaluation mode) and BE (best estimate) calculations are possible. THYDE-W is an improved version of THYDE-P2 and contains the following additional features: (a) analysis of multiple number of disjoint loops is possible; (b) a control system simulation model is included; (c) the trip model has been improved; (d) heavy water is allowed as coolant; (e) the effect of drift flux is accounted for in the steady state calculation; (f) boron transport is included; (g) to obtain steady state loop heat balance, the option of adjusting the enthalpy distribution is prepared included in addition to that of adjusting heat exchanger areas; (h) to obtain steady state pressure distribution, three other options are prepared in addition to the original ones
Directory of Open Access Journals (Sweden)
Ruizhong Jiang
2014-01-01
Full Text Available A mathematical model of multistage fractured horizontal well (MsFHW considering stimulated reservoir volume (SRV was presented for tight oil reservoirs. Both inner and outer regions were assumed as single porosity media but had different formation parameters. Laplace transformation method, point source function integration method, superposition principle, Stehfest numerical algorithm, and Duhamel’s theorem were used comprehensively to obtain the semianalytical solution. Different flow regimes were divided based on pressure transient analysis (PTA curves. According to rate transient analysis (RTA, the effects of related parameters such as SRV radius, storativity ratio, mobility ratio, fracture number, fracture half-length, and fracture spacing were analyzed. The presented model and obtained results in this paper enrich the performance analysis models of MsFHW considering SRV.
Current status of the transient integral fuel element performance code URANUS
International Nuclear Information System (INIS)
Preusser, T.; Lassmann, K.
1983-01-01
To investigate the behavior of fuel pins during normal and off-normal operation, the integral fuel rod code URANUS has been extended to include a transient version. The paper describes the current status of the program system including a presentation of newly developed models for hypothetical accident investigation. The main objective of current development work is to improve the modelling of fuel and clad material behavior during fast transients. URANUS allows detailed analysis of experiments until the onset of strong material transport phenomena. Transient fission gas analysis is carried out due to the coupling with a special version of the LANGZEIT-KURZZEIT-code (KfK). Fuel restructuring and grain growth kinetics models have been improved recently to better characterize pre-experimental steady-state operation; transient models are under development. Extensive verification of the new version has been carried out by comparison with analytical solutions, experimental evidence, and code-to-code evaluation studies. URANUS, with all these improvements, has been successfully applied to difficult fast breeder fuel rod analysis including TOP, LOF, TUCOP, local coolant blockage and specific carbide fuel experiments. Objective of further studies is the description of transient PCMI. It is expected that the results of these developments will contribute significantly to the understanding of fuel element structural behavior during severe transients. (orig.)
Evaluating transient performance of servo mechanisms by analysing stator current of PMSM
Zhang, Qing; Tan, Luyao; Xu, Guanghua
2018-02-01
Smooth running and rapid response are the desired performance goals for the transient motions of servo mechanisms. Because of the uncertain and unobservable transient behaviour of servo mechanisms, it is difficult to evaluate their transient performance. Under the effects of electromechanical coupling, the stator current signals of a permanent-magnet synchronous motor (PMSM) potentially contain the performance information regarding servo mechanisms in use. In this paper, a novel method based on analysing the stator current of the PMSM is proposed for quantifying the transient performance. First, a vector control model is constructed to simulate the stator current behaviour in the transient processes of consecutive speed changes, consecutive load changes, and intermittent start-stops. It is discovered that the amplitude and frequency of the stator current are modulated by the transient load torque and motor speed, respectively. The stator currents under different performance conditions are also simulated and compared. Then, the stator current is processed using a local means decomposition (LMD) algorithm to extract the instantaneous amplitude and instantaneous frequency. The sample entropy of the instantaneous amplitude, which reflects the complexity of the load torque variation, is calculated as a performance indicator of smooth running. The peak-to-peak value of the instantaneous frequency, which defines the range of the motor speed variation, is set as a performance indicator of rapid response. The proposed method is applied to both simulated data in an intermittent start-stops process and experimental data measured for a batch of servo turrets for turning lathes. The results show that the performance evaluations agree with the actual performance.
TRAB - A transient analysis program for BWR. Part 2
International Nuclear Information System (INIS)
Raety, H.; Rajamaeki, M.
1991-05-01
TRAB is a transient analysis code for BWRs developed at the Technical Research Centre of Finland. It models the phenomena in the interior of the BWR pressure vessel and in related subsystems. The core model of TRAB can be used separately for LWR modelling. For PWR modelling the core model of TRAB is connected to circuit model SMABRE to form the SMATRA code. This report is a user's manual and documents the structure, contents and preparation of input for TRAB. The structure of TRAB input is very flexible, featuring input groups and subgroups identified with keywords and given in any order as well as data items in free format, freely mixed with explanatory texts. Users interface of the code can be used for modelling within input: through normal input it is possible to create new submodels. These may be functional or tabulated dependencies of the code variables, different types of delays, or ordinary linear differential equations
Quantum-corrected transient analysis of plasmonic nanostructures
Uysal, Ismail Enes
2017-03-08
A time domain surface integral equation (TD-SIE) solver is developed for quantum-corrected analysis of transient electromagnetic field interactions on plasmonic nanostructures with sub-nanometer gaps. “Quantum correction” introduces an auxiliary tunnel to support the current path that is generated by electrons tunneled between the nanostructures. The permittivity of the auxiliary tunnel and the nanostructures is obtained from density functional theory (DFT) computations. Electromagnetic field interactions on the combined structure (nanostructures plus auxiliary tunnel connecting them) are computed using a TD-SIE solver. Time domain samples of the permittivity and the Green function required by this solver are obtained from their frequency domain samples (generated from DFT computations) using a semi-analytical method. Accuracy and applicability of the resulting quantum-corrected solver scheme are demonstrated via numerical examples.
FAST: An advanced code system for fast reactor transient analysis
International Nuclear Information System (INIS)
Mikityuk, Konstantin; Pelloni, Sandro; Coddington, Paul; Bubelis, Evaldas; Chawla, Rakesh
2005-01-01
One of the main goals of the FAST project at PSI is to establish a unique analytical code capability for the core and safety analysis of advanced critical (and sub-critical) fast-spectrum systems for a wide range of different coolants. Both static and transient core physics, as well as the behaviour and safety of the power plant as a whole, are studied. The paper discusses the structure of the code system, including the organisation of the interfaces and data exchange. Examples of validation and application of the individual programs, as well as of the complete code system, are provided using studies carried out within the context of designs for experimental accelerator-driven, fast-spectrum systems
An Efficient Topology-Based Algorithm for Transient Analysis of Power Grid
Yang, Lan
2015-08-10
In the design flow of integrated circuits, chip-level verification is an important step that sanity checks the performance is as expected. Power grid verification is one of the most expensive and time-consuming steps of chip-level verification, due to its extremely large size. Efficient power grid analysis technology is highly demanded as it saves computing resources and enables faster iteration. In this paper, a topology-base power grid transient analysis algorithm is proposed. Nodal analysis is adopted to analyze the topology which is mathematically equivalent to iteratively solving a positive semi-definite linear equation. The convergence of the method is proved.
Greensmith, David J
2014-01-01
Here I present an Excel based program for the analysis of intracellular Ca transients recorded using fluorescent indicators. The program can perform all the necessary steps which convert recorded raw voltage changes into meaningful physiological information. The program performs two fundamental processes. (1) It can prepare the raw signal by several methods. (2) It can then be used to analyze the prepared data to provide information such as absolute intracellular Ca levels. Also, the rates of change of Ca can be measured using multiple, simultaneous regression analysis. I demonstrate that this program performs equally well as commercially available software, but has numerous advantages, namely creating a simplified, self-contained analysis workflow. Copyright © 2013 The Author. Published by Elsevier Ireland Ltd.. All rights reserved.
An offshore wind farm with dc grid connection and its performance under power system transients
DEFF Research Database (Denmark)
Deng, Fujin; Chen, Zhe
2011-01-01
The continuous increase in wind power penetration level brings new requirements for wind turbine integration into the network. The grid code requires that after clearance of an external short-circuit fault, grid-connected wind turbines should restore their normal operation without power loss caused...... by disconnections. This paper presents a transient performance study of an offshore wind farm with HVDC transmission for grid connection, where the wind turbines in the offshore wind farm are also connected with dc collection network. A power-reduction control strategy (PRCS) for transient performance improvement...... is proposed for the offshore wind farm that allows it to withstand severe voltage dips. A simulation model of a 400 MW offshore wind farm developed in PSCAD/EMTDC is presented. The transient performance of the offshore wind farm is studied, and the results show the effectiveness of the proposed control...
Energy Technology Data Exchange (ETDEWEB)
Navarro-Valenti, S.; Kim, S.H.; Georgevich, V. [Oak Ridge National Lab., TN (United States)] [and others
1995-09-01
The purpose of this paper is to describe the analysis performed to predict the thermal behavior of fuel miniplates under rapid transient heatup conditions. The possibility of explosive boiling was considered, and it was concluded that the heating rates are not large enough for explosive boiling to occur. However, transient boiling effects were pronounced. Because of the complexity of transient pool boiling and the unavailability of experimental data for the situations studied, an approximation was made that predicted the data very well within the uncertainties present. If pool boiling from the miniplates had been assumed to be steady during the heating pulse, the experimental data would have been greatly overestimated. This fact demonstrates the importance of considering the transient nature of heat transfer in the analysis of reactivity excursion accidents. An additional contribution of the present work is that it provided data on highly subcooled steady nulceate boiling from the cooling portion of the thermocouple traces.
Transient analysis for alternating over-current characteristics of HTSC power transmission cable
International Nuclear Information System (INIS)
Lim, S.H.; Hwang, S.D.
2006-01-01
In this paper, the transient analysis for the alternating over-current distribution in case that the over-current was applied for a high-T C 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
Improved Flow Modeling in Transient Reactor Safety Analysis Computer Codes
International Nuclear Information System (INIS)
Holowach, M.J.; Hochreiter, L.E.; Cheung, F.B.
2002-01-01
A method of accounting for fluid-to-fluid shear in between calculational cells over a wide range of flow conditions envisioned in reactor safety studies has been developed such that it may be easily implemented into a computer code such as COBRA-TF for more detailed subchannel analysis. At a given nodal height in the calculational model, equivalent hydraulic diameters are determined for each specific calculational cell using either laminar or turbulent velocity profiles. The velocity profile may be determined from a separate CFD (Computational Fluid Dynamics) analysis, experimental data, or existing semi-empirical relationships. The equivalent hydraulic diameter is then applied to the wall drag force calculation so as to determine the appropriate equivalent fluid-to-fluid shear caused by the wall for each cell based on the input velocity profile. This means of assigning the shear to a specific cell is independent of the actual wetted perimeter and flow area for the calculational cell. The use of this equivalent hydraulic diameter for each cell within a calculational subchannel results in a representative velocity profile which can further increase the accuracy and detail of heat transfer and fluid flow modeling within the subchannel when utilizing a thermal hydraulics systems analysis computer code such as COBRA-TF. Utilizing COBRA-TF with the flow modeling enhancement results in increased accuracy for a coarse-mesh model without the significantly greater computational and time requirements of a full-scale 3D (three-dimensional) transient CFD calculation. (authors)
Energy Technology Data Exchange (ETDEWEB)
Penha, Rosani Maria Libardi da
1999-07-01
transient impulses and discontinuities presents in the signals. As STFT did not detect discontinuities or short transients, the wavelet transform revealed superior performance in this kind of analysis. (author)
Analysis of transient fuel failure mechanisms: selected ANL programs
International Nuclear Information System (INIS)
Deitrich, L.W.
1975-01-01
Analytical programs at Argonne National Laboratory related to fuel pin failure mechanisms in fast-reactor accident transients are described. The studies include transient fuel pin mechanics, mechanics of unclad fuel, and mechanical effects concerning potential fuel failure propagation. (U.S.).
Directory of Open Access Journals (Sweden)
Tao Li
Full Text Available Background and purpose: Transient elastography (TE has been shown to be a valuable tool for the prediction of large esophageal varices. However, the conclusions have not been always consistent throughout the different studies. Therefore, we performed a further meta-analysis in order to evaluate the diagnostic accuracy of transient elastography for the prediction of large esophageal varices. Methods: We performed a systematic literature search in PubMed, EMBASE, Web of Science, and CENTRAL in The Cochrane Library without time restriction. The strategy we used was "(fibroscan OR transient elastography OR stiffness AND esophageal varices". Accuracy measures such as pooled sensitivity, specificity, among others, were calculated using Meta-DiSc statistical software. Results: Twenty studies (2,994 patients were included in our meta-analysis. The values of pooled sensitivity, specificity, positive and negative likelihood ratios and diagnostic odds ratio were as follows: 0.81 (95% CI, 0.79-0.84, 0.71 (95% CI, 0.69-0.73, 2.63 (95% CI, 2.15-3.23, 0.27 (95% CI, 0.22-0.34 and 10.30 (95% CI, 7.33-14.47. The area under the receiver operating characteristics curve was 0.83. The Spearman correlation coefficient was 0.246 with a p-value of 0.296, indicating the absence of any significant threshold effects. In our subgroup analysis, the heterogeneity could be partially explained by the geographical origin of the study or etiology; or it could be partially explained blindingly, through the appropriate interval and cut-off value of the liver stiffness (LS. Conclusions: Transient elastography could be used as a valuable non-invasive screening tool for the prediction of large esophageal varices. However, since LS cut-off values vary throughout the different studies and significant heterogeneity also exists among them, we need more reasonable approaches or flow diagram in order to improve the operability of this technology.
Steady-state and transient analysis of a squeeze film damper bearing for rotor stability
Barrett, L. E.; Gunter, E. J.
1975-01-01
A study of the steady-state and transient response of the squeeze film damper bearing is presented. Both the steady-state and transient equations for the hydrodynamic bearing forces are derived. The bearing equivalent stiffness and damping coefficients are determined by steady-state equations. These coefficients are used to find the bearing configuration which will provide the optimum support characteristics based on a stability analysis of the rotor-bearing system. The transient analysis of rotor-bearing systems is performed by coupling the bearing and journal equations and integrating forward in time. The effects of unbalance, cavitation, and retainer springs are included in the analysis. Methods of determining the stability of a rotor-bearing system under the influence of aerodynamic forces and internal shaft friction are discussed with emphasis on solving the system characteristic frequency equation and on producing stability maps. It is shown that for optimum stability and low force transmissability the squeeze bearing should operate at an eccentricity ratio epsilon 0.4.
Transient Analysis Needs for Generation IV Reactor Concepts
International Nuclear Information System (INIS)
Siefken, L.J.; Harvego, E.A.; Coryell, E.W.; Davis, C.B.
2002-01-01
The importance of nuclear energy as a vital and strategic resource in the U. S. and world's energy supply mix has led to an initiative, termed Generation IV by the U.S. Department of Energy (DOE), to develop and demonstrate new and improved reactor technologies. These new Generation IV reactor concepts are expected to be substantially improved over the current generation of reactors with respect to economics, safety, proliferation resistance and waste characteristics. Although a number of light water reactor concepts have been proposed as Generation IV candidates, the majority of proposed designs have fundamentally different characteristics than the current generation of commercial LWRs operating in the U.S. and other countries. This paper presents the results of a review of these new reactor technologies and defines the transient analyses required to support the evaluation and future development of the Generation IV concepts. The ultimate objective of this work is to identify and develop new capabilities needed by INEEL to support DOE's Generation IV initiative. In particular, the focus of this study is on needed extensions or enhancements to SCDAP/RELAP5/3D code. This code and the RELAP5-3D code from which it evolved are the primary analysis tools used by the INEEL and others for the analysis of design-basis and beyond-design-basis accidents in current generation light water reactors. (authors)
Data Analysis of Transient Energy Releases in the LHC Superconducting Dipole Magnets
Calvi, M; Bottura, L; Di Castro, M; Masi, A; Siemko, A
2007-01-01
Premature training quenches are caused by transient energy released within the LHC dipole magnet coils while it is energized. Voltage signals recorded across the magnet coils and on the so-called quench antenna carry information about these disturbances. The transitory events correlated to transient energy released are extracted making use of continuous wavelet transform. Several analyses are performed to understand their relevance to the so called training phenomenon. The statistical distribution of the signals amplitude, the number of events occurring at a given current level, the average frequency content of the events are the main parameters on which the analysis have been focalized. Comparisons among different regions of the magnet, among different quenches in the same magnet and among magnets made by different builders are reported. Conclusions about the efficiency of the raw data treatment and the relevance of the parameters developed with respect to the magnet global behavior are finally given.
Hirai, Takao; Miyazaki, Teru; Okabe, Shigemitsu; Aiba, Kiyoshi; Yoshinaga, Jun
Lightning performance of grounding electrode is one of the most important lightning-protection features of power distribution lines. It is well known that ground resistance has current-dependent characteristic due to soil ionization. Moreover, it also has time-dependent characteristic. But especially transient behavior has not been represented by EMTP models well because its mechanism is not cleared. In order to clarify the transient behaviors of the grounding electrode, experiments were conducted with full-scale grounding systems. In this study, the paper describes a grounding electrode model that can be easily used in the EMTP analysis. The proposed model considers both current-dependent and time-dependent characteristics. It is verified by comparing calculated results with the experimental results.
Analysis for transient temperature distribution two phase flow using test section QUEEN-02
International Nuclear Information System (INIS)
Ainur Rosidi; Joko Prasetio; Edy Sumarno; Kiswanta; Heru Bambang
2013-01-01
Experiments on the transient temperature distribution using a two-phase flow test facility QUEEN-02 and BETA test loop was conducted. Purpose of the experiment is to study temperature distribution during the transient cooling process. Experiments performed with the variation of the initial temperature of hot rod test section QUEEN-02 of 350 °C and 500 °C as well as the flow of cooling water temperature is 90 °C with the direction of flow from the bottom up from the BETA test loop. The analysis shows that temperature have the same downward trend in its every point thermocouple for the same initial temperature during cooling. Initial temperature of 350 °C hot rods produced when temperatures drop to 90 °C (the same as the temperature of the cooling water) for 78 seconds while the initial temperature of 500 °C produces hot rod drop time 190 seconds. (author)
International Nuclear Information System (INIS)
Hamed, Mouna; Fellah, Ali; Ben Brahim, Ammar
2014-01-01
Highlights: • Parametric studies of a flat plate solar collector is developed. • The model predicts the temperature profile of all the components of the collector and of the working fluid. • A simulation program was constructed to study the effect parameters. • The optimal performance and design of solar collector system was carried out. - Abstract: In this paper, a numerical investigation of flat plate solar collectors is developed to determine the optimal performance and design parameters of these solar to thermal energy conversion systems. The collector is used to supply hot water. It consists of three main components, namely a transparent cover, an absorber and a transfer fluid. A transient simulation method has been developed to characterize the dynamic behavior. The model was established regarding the energy balance analysis. A set of equations representing the model was simultaneously solved. The results are used to investigate the effect of various parameters on the performance of the collector such as outlet water temperature and overall heat loss coefficient. The overall methodology has been developed on environmental data which are characteristic of the city of Gabes in Tunisia
Steady-state and transient performance of HVDC link based 3-level ...
African Journals Online (AJOL)
Administrateur
testés par des simulations à l'aide de Matlab Simulink et SimPowerSystems toolbox. Mots clé : CCHT- convertisseur à base de source de tension- MLI - technique de contrôle - charge passive. Abstract. This paper investigates the steady-state and transient performance of high-voltage DC (HVDC) transmission systems ...
Transient performance simulation of aircraft engine integrated with fuel and control systems
International Nuclear Information System (INIS)
Wang, C.; Li, Y.G.; Yang, B.Y.
2017-01-01
Highlights: • A new performance simulation method for engine hydraulic fuel systems is introduced. • Time delay of engine performance due to fuel system model is noticeable but small. • The method provides details of fuel system behavior in engine transient processes. • The method could be used to support engine and fuel system designs. - Abstract: A new method for the simulation of gas turbine fuel systems based on an inter-component volume method has been developed. It is able to simulate the performance of each of the hydraulic components of a fuel system using physics-based models, which potentially offers more accurate results compared with those using transfer functions. A transient performance simulation system has been set up for gas turbine engines based on an inter-component volume (ICV) method. A proportional-integral (PI) control strategy is used for the simulation of engine controller. An integrated engine and its control and hydraulic fuel systems has been set up to investigate their coupling effect during engine transient processes. The developed simulation system has been applied to a model aero engine. The results show that the delay of the engine transient response due to the inclusion of the fuel system model is noticeable although relatively small. The developed method is generic and can be applied to any other gas turbines and their control and fuel systems.
Transient Performance Improvement of Static Series Compensator by Double Vector Control
DEFF Research Database (Denmark)
Awad, Hilmy; Blaabjerg, Frede
2004-01-01
This paper presents the principle and verification of the double vector control (DVC) algorithm, which improves the transient performance of the Static Series Compensator (SSC). Both current and voltage controllers are incorporated by the DVC, with an inner current control loop and outer voltage ...
The THU-NAOC transient survey: the performance and results from the first year
International Nuclear Information System (INIS)
Zhang Tian-Meng; Zhou Xu; Nie Jun-Dan; Jiang Zhao-Ji; Ma Jun; Wang Ling-Zhi; Zhou Zhi-Min; Zou Hu; Wang Xiao-Feng; Chen Jun-Cheng; Zhou Li; Li Wen-Xiong; Liu Qing; Mo Jun; Zhang Kai-Cheng; Yao Xin-Yu; Zhao Xu-Lin; Huang Fang; Zhang Ju-Jia; Wu Chao
2015-01-01
The Tsinghua University-National Astronomical Observatories, Chinese Academy of Sciences (NAOC) Transient Survey is an automatic survey that conducts a systematic exploration of optical transients. This project utilizes a 60/90 cm Schmidt telescope at the Xinglong Station of NAOC. This survey repeatedly covers ∼ 1000 square degrees of the northern sky with a cadence of 3–4 d. With an exposure of 60 s, the survey reaches a limiting unfiltered magnitude of about 19.5 mag, which enables us to discover supernovae in their relatively young stages. We describe the overall performance of our survey during the first year and present some preliminary results. (research papers)
The Dynamic Monte Carlo Method for Transient Analysis of Nuclear Reactors
Sjenitzer, B.L.
2013-01-01
In this thesis a new method for the analysis of power transients in a nuclear reactor is developed, which is more accurate than the present state-of-the-art methods. Transient analysis is important tool when designing nuclear reactors, since they predict the behaviour of a reactor during changing
Shaking of reinforced concrete structures subjected to transient dynamic analysis
International Nuclear Information System (INIS)
Rouzaud, Christophe
2015-01-01
In the design of nuclear engineering structures security and safety present a crucial aspect. Civil engineering design and the qualification of materials to dynamic loads must consider the accelerations which they undergo. These accelerations could integrate seismic activity and shaking movements consecutive to aircraft impact with higher cut-off frequency. Current methodologies for assessing this shock are based on transient analyses using classical finite element method associated with explicit numerical schemes or projection on modal basis, often linear. In both cases, to represent in meaningful way a medium-frequency content, it should implement a mesh refinement which is hardly compatible with the size of models of the civil engineering structures. In order to extend industrial methodologies used and to allow a better representation of the behavior of the structure in medium-frequency, an approach coupling a temporal and non-linear analysis for shock area with a frequency approach to treatment of shaking with VTCR (Variational Theory of Complex Rays) has been used. The aim is to use the computational efficiency of the implemented strategy, including medium frequency to describe the nuclear structures to aircraft impact. (author)
Analysis of three-dimensional transient seepage into ditch drains ...
Indian Academy of Sciences (India)
Ratan Sarmah
dimensional solutions to the problem are actually valid not for a field of finite size but for an infinite one only. Keywords. Analytical models; three-dimensional ponded ditch drainage; transient seepage; variable ponding; hydraulic conductivity ...
Asymptotic and transient analysis of stochastic core ecosystem models
Directory of Open Access Journals (Sweden)
Thomas C. Gard
2000-07-01
Full Text Available General results on ultimate boundedness and exit probability estimates for stochastic differential equations are applied to investigate asymptotic and transient properties of models of plankton-fish dynamics in uncertain environments
Significance of Dynamic and Transient Analysis in the Design and Operation of Hybrid Energy Systems
International Nuclear Information System (INIS)
Panwar, Mayank; Mohanpurkar, Manish; Hovsapian, Rob; Osorio, Julian D.
2015-01-01
Energy systems were historically designed and operated with a specific energy conversion objective, while managing loads and resources. In the recent years, the increased utilization of non-dispatchable renewable sources such as wind and solar has played a role in power quality and the reliability of power systems. In order to mitigate the risk associated with the non-dispatchable resources an integrated approach, such as Hybrid Energy Systems (HES), has to be taken, integrating the loads and resource management between the traditional thermal power plants and the non-dispatchable resources. As our electric energy becomes more diverse in its generation resources, the HES with its operational control system, its real-time view and its dynamic decisions making will become an essential part of the integrated energy systems and improve the overall grid reliability. The operational constraints of the energy sources on both the thermal power plants and the non-dispatchable resources in HES, plays a vital role in the planning and design stage. It is an established fact that the choice of energy source depends on the available natural resources and possible infrastructure. A critical component of decision-making depends on the complementary nature and controllability of the energy sources to supply the load demands with high reliability. Controllability of complex HES to achieve desired performance and flexibility is implemented via coordinated control systems while simultaneously generating electricity and other useful products such as useful heat or hydrogen. These systems are based on instrumentation, signal processing, control theory, and engineering system design. The entire HES along with the control systems are characterized by widely varying time constants. Hence, for a well-coordinated control and operation, we propose physics based modeling of the subsystems to assist in a dynamic and transient analysis. Dynamic and transient analysis in real and non-real time
The Palomar Transient Factory Survey Camera: first year performance and results
Law, N. M.; Dekany, R. G.; Rahmer, G.; Hale, D.; Smith, R.; Quimby, R.; Ofek, E. O.; Kasliwal, M.; Zolkower, J.; Velur, V.; Henning, J.; Bui, K.; McKenna, D.; Nugent, P.; Jacobsen, J.; Walters, R.; Bloom, J.; Surace, J.; Grillmair, C.; Laher, R.; Mattingly, S.; Kulkarni, S.
2010-07-01
The Palomar Transient Factory (PTF) is a new fully-automated, wide-field survey conducting a systematic exploration of the optical transient sky. The transient survey is performed using a new 8.1 square degree, 101 megapixel camera installed on the 48-inch Samuel Oschin Telescope at Palomar Observatory. The PTF Camera achieved first light at the end of 2008, completed commissioning in July 2009, and is now in routine science operations. The camera is based on the CFH12K camera, and was extensively modified for use on the 48-inch telescope. A field-flattening curved window was installed, the cooling system was re-engineered and upgraded to closed-cycle, custom shutter and filter exchanger mechanisms were added, new custom control software was written, and many other modifications were made. We here describe the performance of these new systems during the first year of Palomar Transient Factory operations, including a detailed and long term on-sky performance characterization. We also describe lessons learned during the construction and commissioning of the upgraded camera, the photometric and astrometric precision currently achieved with the PTF camera, and briefly summarize the first supernova results from the PTF survey.
DEFF Research Database (Denmark)
Wang, Yun; Wu, Qiuwei
2014-01-01
This paper analysis the electromagnetic transient response characteristics of DFIG under symmetrical and asymmetrical cascading grid fault conditions considering phaseangel jump of grid. On deriving the dynamic equations of the DFIG with considering multiple constraints on balanced and unbalanced...... conditions, phase angel jumps, interval of cascading fault, electromagnetic transient characteristics, the principle of the DFIG response under cascading voltage fault can be extract. The influence of grid angel jump on the transient characteristic of DFIG is analyzed and electromagnetic response...
International Nuclear Information System (INIS)
Hartmann, C.; Sanchez, V.; Tietsch, W.; Stieglitz, R.
2012-01-01
The KIT is involved in the development and qualification of best estimate methodologies for BWR transient analysis in cooperation with industrial partners. The goal is to establish the most advanced thermal hydraulic system codes coupled with 3D reactor dynamic codes to be able to perform a more realistic evaluation of the BWR behavior under accidental conditions. For this purpose a computational chain based on the lattice code (SCALE6/GenPMAXS), the coupled neutronic/thermal hydraulic code (TRACE/PARCS) as well as a Monte Carlo based uncertainty and sensitivity package (SUSA) has been established and applied to different kind of transients of a Boiling Water Reactor (BWR). This paper will describe the multidimensional models of the plant elaborated for TRACE and PARCS to perform the investigations mentioned before. For the uncertainty quantification of the coupled code TRACE/PARCS and specifically to take into account the influence of the kinetics parameters in such studies, the PARCS code has been extended to facilitate the change of model parameters in such a way that the SUSA package can be used in connection with TRACE/PARCS for the U and S studies. This approach will be presented in detail. The results obtained for a rod drop transient with TRACE/PARCS using the SUSA-methodology showed clearly the importance of some kinetic parameters on the transient progression demonstrating that the coupling of a best-estimate coupled codes with uncertainty and sensitivity tools is very promising and of great importance for the safety assessment of nuclear reactors. (authors)
Recent developments in transient magneto-structural integrated analysis for fusion applications
International Nuclear Information System (INIS)
Crutzen, Y.; Papadopoulos, S.; Richard, N.; Siakavellas, N.; Wu, J.
1992-01-01
In this paper three different numerical approaches modelling the mutual field-structure interactions during transient electromagnetic events are presented. The application of these approaches to simple plate models, simulating flexible conducting components of fusion devices, show that a magnetic damping is encountered when coupling effects between eddy currents and plate motion are taken into account. This damping increases with the applied magnetic field, modifying the mechanical behavior. An Integrated Design/Analysis System is also proposed, in order to combine different computer codes, obtaining performing computational schemes, in the field of 3D electromagneto-mechanical analyses
A model for transient analysis of a multiple-medium confinement filter system
International Nuclear Information System (INIS)
Hyder, M.L.; Ellison, P.G.; Leonard, M.T.; Louie, D.L.Y.; Donbroski, E.L.; Wagner, K.C.
1990-01-01
A computational model is described that calculates the transient behavior of aerosol and vapor (adsorption) filter compartments such as those used in the Savannah River Site (SRS) production reactor confinement system. The principal application of the model is in the analysis of confinement response to hypothetical severe (core melt) accidents. Under these conditions, aerosol and radio-iodine deposition on filter compartments may be substantial. Attendant filter degradation mechanisms are modeled. Sample calculations are included to illustrate model performance. 6 refs., 14 figs., 1 tab
A fast reactor transient analysis methodology for PCs
International Nuclear Information System (INIS)
Ott, K.O.
1991-10-01
This Manual describes a PC program for LMR Transient Calculations, LTC, written in GW-BASIC. It calculates the power and temperature trajectories for unscrammed TOP and LOHS transients. The LOF transient treatment is not operational in the GW-BASIC program because of storage limitations. The corresponding mathematical model, which allows a rapid treatment of the kinetics and the various feedback effects, is described in Ref. 1. It is briefly reviewed in Sec. 1. The program structure is outlined in Sec. 2, followed by a more detailed description in Sec. 3. Computational details are presented in Appendix A. A complete listing of the GW-BASIC program is given in Appendix B. Appendix C shows input-echo and output for a TOP sample problem, and Appendix D is a Glossary of all quantities used in the LTC program. The limitations of the GW-BASIC storage (to about 60K) are removed if it is run within Quick-BASIC. This then allows the extension of this program to treat LOF transients. Running LTC in Quick-BASIC permits also larger ''Dimensions'' for TOP and LOHS transients
DEFF Research Database (Denmark)
Li, H.; Zhao, B.; Yang, C.
2011-01-01
of a grid-connected wind turbine with squirrel cage induction generator (SCIG). Firstly, by using an equivalent lump mass method, a three-mass wind turbine equivalent model is proposed considering both the blades and the shaft flexibility of the wind turbine drive train system. Combined with the detailed......Increasing levels of wind energy in modern electrical power system is initiating a need for accurate analysis and estimation of transient stability of wind turbine generation systems. This paper investigates the transient behaviors and possible direct methods for transient stability evaluation...... electromagnetic transient models of a SCIG, the transient behaviors of the wind turbine generation system during a three-phase fault are simulated and compared with the traditional models. Secondly, in order to quickly estimate the transient stability limit of the wind turbine generation system, a direct method...
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
Cernavoda unit2 recirculated cooling water system transient analysis
International Nuclear Information System (INIS)
Nita, I. P.; Pancef, R.
2015-01-01
The paper is an approach to calculate the response of Cernavoda NPP Unit 2 RCW System to transient regimes during normal and abnormal regimes. Then one started to analyse the system response to reactor trip on class III and IV of power, LOCA on class IV of power, LOCA on class III power, LOIA on class IV of power, and LOIA on class III power. Moreover, one analysed the system transient due to requirement of changeover of a RCW operating pump, planned and unplanned changeover. This is the first transient approach to this system that took in consideration all building of the system, obtaining a very large system model, with over 900 pipe, 4 pumps, 50 consumers, 21 control valves. The changeover procedure was required to be analysed in order to change the nominal operating mode for Unit 2, from current 2 pumps in operation to 3 pump operations during summer operating mode. (authors)
Summary of transient management
International Nuclear Information System (INIS)
Sheron, B.W.
1984-01-01
This chapter reviews the papers on evaluating and managing transients, as given at the American Nuclear Society Topical Meeting on Anticipated and Abnormal Plant Transients in Light Water Reactors. Transient management involves both diverse and related areas such as analysis, systems performance, human performance, procedures, and training. State-of-the-art simulators are being improved to solve the constitutive equations for two-phase fluid flow by the development of a new generation of analysis codes which are simpler and faster than earlier codes. Both the US NRC and the nuclear industry are criticized for solving problems by adding additional requirements for the reactor operator rather than by recognizing design deficiencies
Directory of Open Access Journals (Sweden)
Huan-Feng Duan
2017-10-01
Full Text Available This paper investigates the impacts of non-uniformities of pipe diameter (i.e., an inhomogeneous cross-sectional area along pipelines on transient wave behavior and propagation in water supply pipelines. The multi-scale wave perturbation method is firstly used to derive analytical solutions for the amplitude evolution of transient pressure wave propagation in pipelines, considering regular and random variations of cross-sectional area, respectively. The analytical analysis is based on the one-dimensional (1D transient wave equation for pipe flow. Both derived results show that transient waves can be attenuated and scattered significantly along the longitudinal direction of the pipeline due to the regular and random non-uniformities of pipe diameter. The obtained analytical results are then validated by extensive 1D numerical simulations under different incident wave and non-uniform pipe conditions. The comparative results indicate that the derived analytical solutions are applicable and useful to describe the wave scattering effect in complex pipeline systems. Finally, the practical implications and influence of wave scattering effects on transient flow analysis and transient-based leak detection in urban water supply systems are discussed in the paper.
Transient Analysis of Station Blackout While Shutdown for OPR1000 Nuclear Power Plant
Energy Technology Data Exchange (ETDEWEB)
Hwang, Su Hyun; Kim, Min Hwa [FNC Technology Co., Yongin (Korea, Republic of); Yoon, Duk Joo; Lee, Seung Chan [KHNP, Daejeon (Korea, Republic of)
2016-10-15
Some studies have been performed to support and provide useful insights for operator guidelines to maintain critical safety functions during a Station Blackout (SBO) or ELAP event for shutdown modes. Shutdown SBO Guideline has been issued to provide instructions for responding to a SBO, including an ELAP, while shutdown with SIAS (Safety Injection Actuation Signal) blocked and fuel in the reactor vessel. The thermal-hydraulic transient analysis using RELAP5/Mod3.3 code was performed to provide insights for shutdown SBO for OPR1000 NPP. It will be helpful for developing a strategy to cope with shutdown SBO for OPR1000 NPP. The thermal-hydraulic transient analysis was performed to provide insights for shutdown SBO. For Shutdown State A, if SG ADV is opened by operator manual action within 4,000 sec, then 6 hour is available to avoid core uncovery and damage. 6 hour is sufficient time for operator to prepare the secondary external injection. For Shutdown State C, if RWST gravity feed is provided by operator manual action within 4,000 sec, then 24 hour is available to avoid core uncovery and damage. 24 hour is sufficient time for operator to prepare the primary external injection or refill RWST. This calculation results can be directly applied to the development of Plant Specific Technical Guide (PSTG) for OPR1000 NPP.
Energy Technology Data Exchange (ETDEWEB)
Ortensi, J.; Brian Boer; Abderrafi M. Ougouag
2010-10-01
A rapid increase of the temperature and the mechanical stress is expected in TRISO coated particle fuel that experiences a fast Total Control Rod Ejection (CRE) transient event. During this event the reactor power in the pebble bed core increases significantly for a short time interval. The power is deposited instantly and locally in the fuel kernel. This could result in a rapid increase of the pressure in the buffer layer of the coated fuel particle and, consequently, in an increase of the coating stresses. These stresses determine the mechanical failure probability of the coatings, which serve as the containment of radioactive fission products in the Pebble Bed Reactor (PBR). A new calculation procedure has been implemented at the Idaho National Laboratory (INL), which analyzes the transient fuel performance behavior of TRISO fuel particles in PBRs. This early capability can easily be extended to prismatic designs, given the availability of neutronic and thermal-fluid solvers. The full-core coupled neutronic and thermal-fluid analysis has been modeled with CYNOD-THERMIX. The temperature fields for the fuel kernel and the particle coatings, as well as the gas pressures in the buffer layer, are calculated with the THETRIS module explicitly during the transient calculation. Results from this module are part of the feedback loop within the neutronic-thermal fluid iterations performed for each time step. The temperature and internal pressure values for each pebble type in each region of the core are then input to the PArticle STress Analysis (PASTA) code, which determines the particle coating stresses and the fraction of failed particles. This paper presents an investigation of a Total Control Rod Ejection (TCRE) incident in the 400 MWth Pebble Bed Modular reactor design using the above described calculation procedure. The transient corresponds to a reactivity insertion of $3 (~2000 pcm) reaching 35 times the nominal power in 0.5 seconds. For each position in the core
Numerical analysis of power system transients and dynamics
Ametani, Akihiro
2015-01-01
This book describes the three major power system transient and dynamics simulation tools based on a circuit-theory based approach which are most widely used all over the world (EMTP-ATP, EMTP-RV and EMTDC/PSCAD), together with other powerful simulation tools such as XTAP.
Development of the containment transient analysis code for the passive reactor
Energy Technology Data Exchange (ETDEWEB)
Hwang, Young Dong; Kim, Young In; Bae, Yoon Young; Chang, Moon Hi [Korea Atomic Energy Research Institute, Taejon (Korea)
1998-05-01
This study was performed to develop the analysis tools for the passively cooled steel containment and to construct the integrated code system which can analyze a thermal hydraulic behavior of the containment and reactor system during a loss of coolant accident. The computer code CONTEMPT4/MOD5/PCCS was developed by incorporating the passive containment cooling models to the containment pressure and temperature transient analysis computer code CONTEMPT4/MOD5. The integrated reactor thermal hydraulic analysis code system for passive reactor was constructed by coupling the best estimate thermal hydraulic system analysis code RELAP5/MOD3 and CONTEMPT4/MOD5/PCCS through the process control method. In addition, to evaluate the applicability of the code the CONTEMPT4/MOD5/PCCS was applied to the SMART(System-Integrated Modular Advanced Reactor). The pressure and temperature transient following the small break LOCA of SMART was analysed by modeling the safeguard vessel using both the newly added passive containment cooling model and existing pool model. (author). 16 refs., 22 figs., 7 tabs.
Energy Technology Data Exchange (ETDEWEB)
Schafer, Annette L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sondrup, A. Jeffrey [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2013-11-01
This is a companion document to the analyses performed in support of the environmental assessment for the Resumption of Transient Fuels and Materials Testing. It is provided to allow transparency of the supporting calculations. It provides computer code input and output. The basis for the calculations is documented separately in INL (2013) and is referenced, as appropriate. Spreadsheets used to manipulate the code output are not provided.
Transient Stability Analysis of Induction Generator Using Time Domain Torque Characteristic
Senjyu, Tomonobu; Sueyoshi, Norihide; Uezato, Katsumi; Fujita, Hideki; Funabashi, Toshihisa
Transient stability assessment of the wind power generator is one of main issue in power system security and operation. The transient stability of the wind power generator is determine by its corresponding Critical Clearing Time(CCT). In this paper, we present the formulae to the transient behavior analysis and the transient stability analysis technique of induction generator used in wind power generating system at the three-phase fault condition. In the proposed method, the transient stability of the induction generator is analyzed using well known torque-slip and generator speed-time characteristics. The validity of the developed technique is confirmed with the results obtained from trials and error method using MATLAB/SIMULINK.
INITIAL ANALYSIS OF TRANSIENT POWER TIME LAG DUE TO HETEROGENEITY WITHIN THE TREAT FUEL MATRIX.
Energy Technology Data Exchange (ETDEWEB)
D.M. Wachs; A.X. Zabriskie, W.R. Marcum
2014-06-01
The topic Nuclear Safety encompasses a broad spectrum of focal areas within the nuclear industry; one specific aspect centers on the performance and integrity of nuclear fuel during a reactivity insertion accident (RIA). This specific accident has proven to be fundamentally difficult to theoretically characterize due to the numerous empirically driven characteristics that quantify the fuel and reactor performance. The Transient Reactor Test (TREAT) facility was designed and operated to better understand fuel behavior under extreme (i.e. accident) conditions; it was shutdown in 1994. Recently, efforts have been underway to commission the TREAT facility to continue testing of advanced accident tolerant fuels (i.e. recently developed fuel concepts). To aid in the restart effort, new simulation tools are being used to investigate the behavior of nuclear fuels during facility’s transient events. This study focuses specifically on the characterizing modeled effects of fuel particles within the fuel matrix of the TREAT. The objective of this study was to (1) identify the impact of modeled heterogeneity within the fuel matrix during a transient event, and (2) demonstrate acceptable modeling processes for the purpose of TREAT safety analyses, specific to fuel matrix and particle size. Hypothetically, a fuel that is dominantly heterogeneous will demonstrate a clearly different temporal heating response to that of a modeled homogeneous fuel. This time difference is a result of the uniqueness of the thermal diffusivity within the fuel particle and fuel matrix. Using MOOSE/BISON to simulate the temperature time-lag effect of fuel particle diameter during a transient event, a comparison of the average graphite moderator temperature surrounding a spherical particle of fuel was made for both types of fuel simulations. This comparison showed that at a given time and with a specific fuel particle diameter, the fuel particle (heterogeneous) simulation and the homogeneous simulation
Greensmith, David J.
2014-01-01
Here I present an Excel based program for the analysis of intracellular Ca transients recorded using fluorescent indicators. The program can perform all the necessary steps which convert recorded raw voltage changes into meaningful physiological information. The program performs two fundamental processes. (1) It can prepare the raw signal by several methods. (2) It can then be used to analyze the prepared data to provide information such as absolute intracellular Ca levels. Also, the rates of change of Ca can be measured using multiple, simultaneous regression analysis. I demonstrate that this program performs equally well as commercially available software, but has numerous advantages, namely creating a simplified, self-contained analysis workflow. PMID:24125908
Research on Model-Based Fault Diagnosis for a Gas Turbine Based on Transient Performance
Directory of Open Access Journals (Sweden)
Detang Zeng
2018-01-01
Full Text Available It is essential to monitor and to diagnose faults in rotating machinery with a high thrust–weight ratio and complex structure for a variety of industrial applications, for which reliable signal measurements are required. However, the measured values consist of the true values of the parameters, the inertia of measurements, random errors and systematic errors. Such signals cannot reflect the true performance state and the health state of rotating machinery accurately. High-quality, steady-state measurements are necessary for most current diagnostic methods. Unfortunately, it is hard to obtain these kinds of measurements for most rotating machinery. Diagnosis based on transient performance is a useful tool that can potentially solve this problem. A model-based fault diagnosis method for gas turbines based on transient performance is proposed in this paper. The fault diagnosis consists of a dynamic simulation model, a diagnostic scheme, and an optimization algorithm. A high-accuracy, nonlinear, dynamic gas turbine model using a modular modeling method is presented that involves thermophysical properties, a component characteristic chart, and system inertial. The startup process is simulated using this model. The consistency between the simulation results and the field operation data shows the validity of the model and the advantages of transient accumulated deviation. In addition, a diagnostic scheme is designed to fulfill this process. Finally, cuckoo search is selected to solve the optimization problem in fault diagnosis. Comparative diagnostic results for a gas turbine before and after washing indicate the improved effectiveness and accuracy of the proposed method of using data from transient processes, compared with traditional methods using data from the steady state.
Mrvić Jovan; Jasika Ranko; Vukelja Petar; Lepović Goran; Simić Ninoslav
2016-01-01
The goal of this paper is to introduce a procedure for risk assessment of insulation failure due to storm surges. The simulations were carried out in ATP / EMTP software, which allowed the use of the Monte Carlo method for the statistical analysis of insulation coordination. The paper gives a detailed account of modelling of all the elements relevant to the analysis. At the same time, the capabilities of the programming language MODELS (allows the creation and implementation of new complex co...
Nuclear fuel management and transients analysis in Laguna Verde nuclear power plant
International Nuclear Information System (INIS)
De Loera De Haro, M.A.; Alvarez Gasca, J.
1991-01-01
Nuclear fuel management transient analysis are the set of activities which determine the load and reload of nuclear fuel inside the reactor, with the aim of getting the maximum performance in fuel burn up and heat remotion, without have an effect in the station safety. Nuclear fuel management and transient analysis has its basis on high precision quantitative analysis methodologies by means of simulation of nuclear and physical phenomena occurring both in normal and abnormal operation of nuclear power plants. On account of complexity of simulations and the required precision, those are carry out using codes type 'best estimate'. For the use of this tools it is necessary a deep knowledge of simulated nuclear and physical phenomena, as well as the used mathematical models and the numerical methods used. If different, the simulation results will be notably different actual processes owing to the use of models out of validity range, or incorrect calculations in the input parameters. On account of complexity of simulations and the required precision, those are carry out using codes type 'best estimate'. For the use of this tools it is necessary a deep knowledge of simulated nuclear and physical phenomena, as well as the used mathematical models and the numerical methods used. If different, the simulation results will be notably different actual processes owing to the use of models out of validity range, or incorrect calculations in the input parameters
[Risk factors' analysis of transient and permanent hypoparathyroidism after thyroidectomy].
Cocchiara, G; Cajozzo, M; Fazzotta, S; Palumbo, V D; Geraci, G; Maione, C; Buscemi, S; Romano, G; Fatica, F; Spinelli, G; Ficarella, S; Maffongelli, A; Caternicchia, F; Lo Monte, A I
2017-01-01
This review evaluates those main risk factors that can affect patients undergoing thyroidectomy, to reach a better pre- and post-operative management of transient and permanent hypoparathyroidism. The transient hypoparathyroidism is a potentially severe complication of thyroidectomy, including a wide range of signs and symptoms that persists for a few weeks. The definitive hypoparathyroidism occurs when a medical treatment is necessary over 12 months. Risk factors that may influence the onset of this condition after thyroidectomy include: pre- and post-operative biochemical factors, such as serum calcium levels, vitamin D blood concentrations and intact PTH. Other involved factors could be summarized as follow: female sex, Graves' or thyroid neoplastic diseases, surgeon's dexterity and surgical technique. The medical treatment includes the administration of calcium, vitamin D and magnesium sometimes. Although biological and biochemical factors could be related to iatrogenic hypoparathyroidism, the surgeon's experience and the used surgical technique still maintain a crucial role in the aetiology of this important complication.
Transient Analysis of Monopile Foundations Partially Embedded in Liquefied Soil
DEFF Research Database (Denmark)
Barari, Amin; Bayat, Mehdi; Meysam, Saadati
2015-01-01
In this study, the authors present a coupled fluid-structures-seabed interaction analysis of a monopile type of wind turbine foundations in liquefiable soils. A two dimensional analysis is performed with a nonlinear stiffness degradation model incorporated in the finite difference program Fast...... Lagrangian Analysis of Continua (FLAC), which captured the fundamental mechanisms of the monopiles in saturated granular soil. The effects of inertia and the kinematic flow of soil are investigated separately, to highlight the importance of considering the combined effect of these phenomena on the seismic...... design of offshore monopiles. Different seismic loads, such as those experienced in the Kobe, Santa Cruz, Loma Prieta, Kocaeli, and Morgan Hill earthquakes, are analyzed. The pore water pressure development, relative displacements, soil skeleton deformation and monopile bending moment are obtained...
Guidelines for Transient Analysis in Water Transmission and Distribution Systems
Pothof, Ivo; Karney, Bryan
2012-01-01
All water systems leak, and many supply systems do so considerably, with water losses typically of approximately 20% of the water production. The IWA Water Loss Task Force aims for a significant reduction of annual water losses by drafting documents to assist practitioners and others to prevent, monitor and mitigate water losses in water transmission and distribution systems. One of the causes of water losses are transient phenomena, caused by normal and accidental pump and valve operations. ...
Transient Response Analysis of Metropolis Learning in Games
Jaleel, Hassan
2017-10-19
The objective of this work is to provide a qualitative description of the transient properties of stochastic learning dynamics like adaptive play, log-linear learning, and Metropolis learning. The solution concept used in these learning dynamics for potential games is that of stochastic stability, which is based on the stationary distribution of the reversible Markov chain representing the learning process. However, time to converge to a stochastically stable state is exponential in the inverse of noise, which limits the use of stochastic stability as an effective solution concept for these dynamics. We propose a complete solution concept that qualitatively describes the state of the system at all times. The proposed concept is prevalent in control systems literature where a solution to a linear or a non-linear system has two parts, transient response and steady state response. Stochastic stability provides the steady state response of stochastic learning rules. In this work, we study its transient properties. Starting from an initial condition, we identify the subsets of the state space called cycles that have small hitting times and long exit times. Over the long time scales, we provide a description of how the distributions over joint action profiles transition from one cycle to another till it reaches the globally optimal state.
Analysis of an Earthquake-Initiated-Transient in a PBR
Energy Technology Data Exchange (ETDEWEB)
A. M. Ougouag; J. Ortensi; H. Hiruta
2009-05-01
One of the Design Basis Accidents (DBA) for a Pebble Bed Reactor has been identified as the “Safe shutdown earthquake with core conduction cooling to passive mode of Reactor Cavity Cooling System.” A new methodology to analyze this particular DBA has been developed at the Idaho National Laboratory (INL). During the seismic event the reactor core experiences the densification of the pebbles, which produce small reactivity insertions due to the effective fuel densification. In addition, a decrease in the active core height results in the relative withdrawal of the control rods, which are assumed to remain stationary during the transient. The methodology relies on the dynamic re-meshing of the core during the transient to capture the local packing fraction changes and their corresponding effects on temperature and reactivity. The core re-meshing methodology is based on the velocity profiles of the pebbles in the core, which were obtained with the INL’s pebble mechanics code PEBBLES. The methodology has been added to the coupled code system CYNOD-THERMIX-KONVEK. The reactor power calculation is further improved with the use of the new advanced TRISO fuel model to better approximate the temperatures in the fuel kernels. During the transient the core is brought back to a safe condition by the strong Doppler feedback from local temperature increases.
Peptidomics Analysis of Transient Regeneration in the Neonatal Mouse Heart.
Fan, Yi; Zhang, Qijun; Li, Hua; Cheng, Zijie; Li, Xing; Chen, Yumei; Shen, Yahui; Wang, Liansheng; Song, Guixian; Qian, Lingmei
2017-09-01
Neonatal mouse hearts have completely regenerative capability after birth, but the ability to regenerate rapidly lost after 7 days, the mechanism has not been clarified. Previous studies have shown that mRNA profile of adult mouse changed greatly compared to neonatal mouse. So far, there is no research of peptidomics related to heart regeneration. In order to explore the changes of proteins, enzymes, and peptides related to the transient regeneration, we used comparative petidomics technique to compare the endogenous peptides in the mouse heart of postnatal 1 and 7 days. In final, we identified 236 differentially expressed peptides, 169 of which were upregulated and 67 were downregulated in the postnatal 1 day heart, and also predicted 36 functional peptides associated with transient regeneration. The predicted 36 candidate peptides are located in the important domains of precursor proteins and/or contain the post-transcriptional modification (PTM) sites, which are involved in the biological processes of cardiac development, cardiac muscle disease, cell proliferation, necrosis, and apoptosis. In conclusion, for the first time, we compared the peptidomics profiles of neonatal heart between postnatal 1 day and postnatal 7 day. This study provides a new direction and an important basis for the mechanism research of transient regeneration in neonatal heart. J. Cell. Biochem. 118: 2828-2840, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
Transient analysis of LMFBR reinforced/prestressed concrete containment
International Nuclear Information System (INIS)
Marchertas, A.H.; Belytschko, T.B.; Bazant, Z.P.
1979-01-01
The use of prestressed concrete reactor vessels (PCRVs) for LMFBR containment creates a need for analytical methods for treating the transient response of such structures, for LMFBR containments must be capable of sustaining the dynamic effects which arise in a hypothetical core disruptive accident (HCDA). These analyses require several unique features: a model of concrete which includes tensile cracking, a methodology for representing the prestressing tendons and for simulating the prestressing operation, and an efficient computational tool for treating the transient response. Furthermore, for the sake of convenience, all of these features should be available in a single computer code. For the purpose of treating the transient response, a finite element program with explicit time integration was chosen. The use of explicit time integration has the advantage that it can easily treat the complicated constitutive model which arises from the considerations of concrete cracking and it can handle the slip between reinforcing tendons and the concrete through the use of the well known sliding interface options. However, explicit time integration programs are usually not well suited to the simulation of static processes such as prestressing. Nevertheless, explicit time integration programs can handle static processes through the introduction of damping by what is known as a dynamic relaxation procedure. For this reason, the dynamic relaxation procedure was refined through the introduction of lumped mass, viscous damping. This provision made the prestressing operation of the concrete structures by means of the explicit formulation rather convenient. (orig.)
Directory of Open Access Journals (Sweden)
Mrvić Jovan
2016-01-01
Full Text Available The goal of this paper is to introduce a procedure for risk assessment of insulation failure due to storm surges. The simulations were carried out in ATP / EMTP software, which allowed the use of the Monte Carlo method for the statistical analysis of insulation coordination. The paper gives a detailed account of modelling of all the elements relevant to the analysis. At the same time, the capabilities of the programming language MODELS (allows the creation and implementation of new complex components within the ATP software are discussed.
Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori
2009-01-01
The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump.
Comparison and analysis on transient characteristics of integral pressurized water reactors
International Nuclear Information System (INIS)
Zhang, Guoxu; Xie, Heng
2017-01-01
Highlights: • Two IPWR Relap5 models with different PSS design were developed. • Postulated SBO and SBLOCA were analyzed. • PRHRS in primary PSS design showed stable performance under different scenarios. • Secondary PRHRS design faced flow instability. - Abstract: In the present work, the similarities and differences of representative IPWRs (integral pressurized water reactor) are studied, and two typical reactor design schemes are summarized. To get a comprehensive understanding of their transient characteristics, SBO (station blackout) and SBLOCA (small break LOCA) are simulated and analyzed respectively by using Relap5/Mod3.2. The calculation results show that, both designs are effective in keeping reactor safe. However, the transient features of the two designs show significant differences. In the primary side passive safety system (PSS) connection design, PRHRS (passive residual heat removal system) shows a roughly congruent performance in removing residual heat under various accidents. While in secondary side PSS connection design, the capability of PRHRS is closely related to primary coolant circulation condition. In SBLOCA analysis, different design approach shows different primary coolant water inventory change trend. And primary PSS connection design could potentially keep reactor core well covered for a longer time.
Transient analysis of printed lines using finite-difference time-domain method
Energy Technology Data Exchange (ETDEWEB)
Ahmed, Shahid [Thomas Jefferson National Accelerator Facility, 12050 Jefferson Avenue, Suite 704, Newport News, VA, 23606, USA
2012-03-29
Comprehensive studies of ultra-wideband pulses and electromagnetic coupling on printed coupled lines have been performed using full-wave 3D finite-difference time-domain analysis. Effects of unequal phase velocities of coupled modes, coupling between line traces, and the frequency dispersion on the waveform fidelity and crosstalk have been investigated in detail. To discriminate the contributions of different mechanisms into pulse evolution, single and coupled microstrip lines without (ϵ_{r} = 1) and with (ϵ_{r} > 1) dielectric substrates have been examined. To consistently compare the performance of the coupled lines with substrates of different permittivities and transients of different characteristic times, a generic metric similar to the electrical wavelength has been introduced. The features of pulse propagation on coupled lines with layered and pedestal substrates and on the irregular traces have been explored. Finally, physical interpretations of the simulation results are discussed in the paper.
International Nuclear Information System (INIS)
Nalezny, C.L.; Chapman, R.L.; Martinell, J.S.; Riordon, R.P.; Solbrig, C.W.
1979-01-01
Mass flow is an important measured variable in the Loss-of-Fluid Test (LOFT) Program. Large uncertainties in mass flow measurements in the LOFT piping during LOFT coolant experiments requires instrument testing in a transient two-phase flow loop that simulates the geometry of the LOFT piping. To satisfy this need, a transient two-phase flow loop has been designed and built. The load cell weighing system, which provides reference mass flow measurements, has been analyzed to assess its capability to provide the measurements. The analysis consisted of first performing a thermal-hydraulic analysis using RELAP4 to compute mass inventory and pressure fluctuations in the system and mass flow rate at the instrument location. RELAP4 output was used as input to a structural analysis code SAPIV which is used to determine load cell response. The computed load cell response was then smoothed and differentiated to compute mass flow rate from the system. Comparison between computed mass flow rate at the instrument location and mass flow rate from the system computed from the load cell output was used to evaluate mass flow measurement capability of the load cell weighing system. Results of the analysis indicate that the load cell weighing system will provide reference mass flows more accurately than the instruments now in LOFT
Power system transient stability analysis based on branch potential characteristics
Han, Huan; Wang, Zengping
2017-09-01
Branch potential function is proposed based on the power system network preserving model. The concept of thermodynamics-entropy, is introduced to describe spatial distribution characteristics of the branch potential energy. Branch potential energy was analysed in time and space domain., with transient stability index proposed accordingly. The larger disturbance energy line fault injected to grid is, the larger branch energy entropy will be, and the more energy accumulated on key branches is, the more prone to lose stability the system will be. Simulation results on IEEE system proved its feasibility.
RETRAN operational transient analysis of the Big Rock Point plant boiling water reactor
International Nuclear Information System (INIS)
Sawtelle, G.R.; Atchison, J.D.; Farman, R.F.; VandeWalle, D.J.; Bazydlo, H.G.
1983-01-01
Energy Incorporated used the RETRAN computer code to model and calculate nine Consumers Power Company Big Rock Point Nuclear Power Plant transients. RETRAN, a best-estimate, one-dimensional, homogeneous-flow thermal-equilibrium code, is applicable to FSAR Chapter 15 transients for Conditions 1 through IV. The BWR analyses were performed in accordance with USNRC Standard Review Plan criteria and in response to the USNRC Systematic Evaluation Program. The RETRAN Big Rock Point model was verified by comparison to plant startup test data. This paper discusses the unique modeling techniques used in RETRAN to model this steam-drum-type BWR. Transient analyses results are also presented
Rapid All-Sky Transient Discovery and Analysis with Evryscope
Corbett, Henry T.; Law, Nicholas; Fors, Octavi; Ratzloff, Jeff; Goeke, Erin; Howard, Ward S.
2018-01-01
The Evryscope is an array of 24 small telescopes on a common mount, capable of observing the entire visible sky down to g' ~ 16 with a two-minute cadence. Each exposure covers 8000 square degrees over 691 MPix and requires minimal readout time, providing 97% continuous coverage of the night sky. The system's large field of view and rapid cadence enable exploration of a previously inaccessible parameter space of bright and fast transients, including nearby microlensing events, supernovae, and kilonovae GW counterparts. The first instrument, located at CTIO in Chile, was deployed in mid-2015 and is currently in production creating multi-year light curves with percent-level precision. A second identical system is on track for deployment at Mount Laguna Observatory in California in early 2018. Once operational, the two sites will provide simultaneous two-color photometry over a 4000 square degree overlapping region accessible to both instruments, operating as a combined discovery and follow-up network for transient phenomena on all nearby stars and many nearby galaxies. I will present recent science results from the Evryscope and an overview of our data reduction pipeline.
Transient analysis of blowdown thrust force under PWR LOCA
International Nuclear Information System (INIS)
Yano, Toshikazu; Miyazaki, Noriyuki; Isozaki, Toshikuni
1982-10-01
The analytical results of blowdown characteristics and thrust forces were compared with the experiments, which were performed as pipe whip and jet discharge tests under the PWR LOCA conditions. The blowdown thrust forces obtained by Navier-Stokes momentum equation about a single-phase, homogeneous and separated two-phase flow, assuming critical pressure at the exit if a critical flow condition was satisfied. The following results are obtained. (1) The node-junction method is useful for both the analyses of the blowdown thrust force and of the water hammer phenomena. (2) The Henry-Fauske model for subcooled critical flow is effective for the analysis of the maximum thrust force under the PWR LOCA conditions. The jet thrust parameter of the analysis and experiment is equal to 1.08. (3) The thrust parameter of saturated blowdown has the same one with the value under pressurized condition when the stagnant pressure is chosen as the saturated one. (4) The dominant terms of the blowdown thrust force in the momentum equation are the pressure and momentum terms except that the acceleration term has large contribution only just after the break. (5) The blowdown thrust force in the analysis greatly depends on the selection of the exit pressure. (author)
Analysis of cofrentes abnormal plant transients with RETRAN-02 and RETRAN-03
International Nuclear Information System (INIS)
Mata, P.; Sedano, P.G.; Serra, J.
1992-01-01
In this paper the applicability and usefulness of a complete and well-qualified plant transient code and model to support in-depth evaluation of anomalous plant transients are described. The qualified best-estimate RETRAN-02 model for the Cofrentes nuclear power plant (a boiling water reactor with an uprated power of 2952 MW) has been updated for RETRAN-03 using algebraic slip and one-dimensional kinetics. This model has been used in the analysis of recent abnormal plant transients at Cofrentes, including a partial control rod insertion at 92% power, a turbine trip at 67% power with reactor vessel overfill, and reactor instabilities during startup
International Nuclear Information System (INIS)
Gomes, Daniel S.; Teixeira, Antonio S.
2017-01-01
Although regulatory agencies have shown a special interest in incorporating best estimate approaches in the fuel licensing process, fuel codes are currently licensed based on only the deterministic limits such as those seen in 10CRF50, and therefore, may yield unrealistic safety margins. The concept of uncertainty analysis is employed to more realistically manage this risk. In this study, uncertainties were classified into two categories: probabilistic and epistemic (owing to a lack of pre-existing knowledge in this area). Fuel rods have three sources of uncertainty: manufacturing tolerance, boundary conditions, and physical models. The first step in successfully analyzing the uncertainties involves performing a statistical analysis on the input parameters used throughout the fuel code. The response obtained from this analysis must show proportional index correlations because the uncertainties are globally propagated. The Dakota toolkit was used to analyze the FRAPTRAN transient fuel code. The subsequent sensitivity analyses helped in identifying the key parameters with the highest correlation indices including the peak cladding temperature and the time required for cladding failures. The uncertainty analysis was performed using an IFA-650-5 fuel rod, which was in line with the tests performed in the Halden Project in Norway. The main objectives of the Halden project included studying the ballooning and rupture processes. The results of this experiment demonstrate the accuracy and applicability of the physical models in evaluating the thermal conductivity, mechanical model, and fuel swelling formulations. (author)
Chatterjee, A.; Ghoshal, S. P.; Mukherjee, V.
In this paper, a conventional thermal power system equipped with automatic voltage regulator, IEEE type dual input power system stabilizer (PSS) PSS3B and integral controlled automatic generation control loop is considered. A distributed generation (DG) system consisting of aqua electrolyzer, photovoltaic cells, diesel engine generator, and some other energy storage devices like flywheel energy storage system and battery energy storage system is modeled. This hybrid distributed system is connected to the grid. While integrating this DG with the onventional thermal power system, improved transient performance is noticed. Further improvement in the transient performance of this grid connected DG is observed with the usage of superconducting magnetic energy storage device. The different tunable parameters of the proposed hybrid power system model are optimized by artificial bee colony (ABC) algorithm. The optimal solutions offered by the ABC algorithm are compared with those offered by genetic algorithm (GA). It is also revealed that the optimizing performance of the ABC is better than the GA for this specific application.
Development of a computer code for Dalat research reactor transient analysis
International Nuclear Information System (INIS)
Le Vinh Vinh; Nguyen Thai Sinh; Huynh Ton Nghiem; Luong Ba Vien; Pham Van Lam; Nguyen Kien Cuong
2003-01-01
DRSIM (Dalat Reactor SIMulation) computer code has been developed for Dalat reactor transient analysis. It is basically a coupled neutronics-hydrodynamics-heat transfer code employing point kinetics, one dimensional hydrodynamics and one dimensional heat transfer. The work was financed by VAEC and DNRI in the framework of institutional R and D programme. Some transient problems related to reactivity and loss of coolant flow was carried out by DRSIM using temperature and void coefficients calculated by WIMS and HEXNOD2D codes. (author)
Analysis of tracer and thermal transients during reinjection
Energy Technology Data Exchange (ETDEWEB)
Kocabas, I.
1989-10-01
This work studied tracer and thermal transients during reinjection in geothermal reserviors and developed a new technique which combines the results from interwell tracer tests and thermal injection-backflow tests to estimate the thermal breakthrough times. Tracer tests are essential to determine the degree of connectivity between the injection wells and the producing wells. To analyze the tracer return profiles quantitatively, we employed three mathematical models namely, the convection-dispersion (CD) model, matrix diffusion (MD) model, and the Avodnin (AD) model, which were developed to study tracer and heat transport in a single vertical fracture. We considered three types of tracer tests namely, interwell tracer tests without recirculation, interwell tracer tests with recirculation, and injection-backflow tracer tests. To estimate the model parameters, we used a nonlinear regression program to match tracer return profiles to the solutions.
Implicit analysis of the transient water flow with dissolved air
Directory of Open Access Journals (Sweden)
J. Twyman
2018-01-01
Full Text Available The implicit finite-difference method (IFDM for solving a system that transports water with dissolved air using a fixed (or variable rectangular space-time mesh defined by the specified time step method is applied. The air content in the fluid modifies both the wave speed and the Courant number, which makes it inconvenient to apply the traditional Method of Characteristics (MOC and other explicit schemes due to their impossibility to simulate the changes in magnitude, shape and frequency of the pressures train. The conclusion is that the IFDM delivers an accurate and stable solution, with a good adjustment level with respect to a classical case reported in the literature, being a valid alternative for the transient solution in systems that transport water with dissolved air.
ANO-2 turbine trip transient test analysis using MMS
International Nuclear Information System (INIS)
Jain, P.K.; Divakaruni, S.M.
1984-01-01
The data from the turbine trip transient tests conducted at the Arkansas Nuclear One-Unit 2 was used as one of the benchmark cases for validating the Modular Modeling System (MMS) Code, developed by the Electric Power Research Institute (EPRI). The data was used first to validate the modules in stand-alone simulation tests and then in a Nuclear Steam Supply system integral tests. This paper presents the results from the MMS simulation effort and compares the code generated results with the plant data as well as RETRAN results. In general, MMS simulation results compare very well with the plant data. The code calculations for the hot and cold leg temperatures, primary system pressure and the pressurizer level are very good compared to RETRAN; however, MMS results for steam generator level compare reasonably well only with RETRAN calculations
Computer analysis of transient heat transfer from coated surfaces
International Nuclear Information System (INIS)
Menard, A.; Holmes, D.
1983-01-01
The transient thermal response of internally heated, coated surfaces in contact with liquid helium was investigated with a previously developed computer model. The coatings were found to affect the time required to initiate film boiling or to quench a superconductor in the substrate. The energy which can be absorbed without an unacceptably large temperature rise depends most strongly upon the coating thermal property group (kpC /SUB p/ ) /SUP 1/2/ and on the peak nucleate boiling heat flux. Dielectric materials for electrical insulation usually have low thermal property group values, but a new class of ceramic materials shows great promise for application with superconducting devices as electrical insulations with good thermal properties. Coating materials with thermal property group values greater than that of OFHC copper at liquid helium temperatures provide the same thermal stability as a bare copper surface exposed to the helium bath. Possible applications of the new materials to potted windings are also discussed
Energy Technology Data Exchange (ETDEWEB)
Matuck, Vinicius; Ramos, Mario C.; Faria, Rochkhudson B.; Reis, Patricia A.L.; Costa, Antonella L.; Pereira, Claubia, E-mail: rochkdefaria@yahoo.com.br, E-mail: matuck747@gmail.com, E-mail: patricialire@yahoo.com.br, E-mail: marc5663@gmail.com, E-mail: antonella@nuclear.ufmg.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenharia Nuclear
2017-11-01
A detailed thermal-hydraulic reactor model using as reference data from the Angra 2 Final Safety Analysis Report (FSAR) has been developed and SiC reinforced with Hi-Nicalon type S fibers (SiC HNS) was used as fuel cladding. The goal is to compare its behavior from the thermal viewpoint with the Zircaloy, at the steady- state and transient conditions. The RELAP-3D was used to perform the thermal-hydraulic analysis and a blockage transient has been investigated at full power operation. The transient considered is related to total obstruction of a core cooling channel of one fuel assembly. The calculations were performed using a point kinetic model. The reactor behavior after this transient was analyzed and the time evolution of cladding and coolant temperatures mass flow and void fraction are presented. (author)
CORTES, Steady-State and Transient Heat Flow and Stress Analysis in Pipe Joints
International Nuclear Information System (INIS)
Gantayat, A. N.; Powell, G. H.; Textor, R. E.; Bass, B. R.; Bryson, J. W.; Moore, S. E.
1996-01-01
1 - Description of problem or function: CORTES is a package consisting of five finite element programs developed for the stress analysis of ANSI Bl6.9 tee joints. The five programs are: SA, the stress analysis program which analyzes pipe joints for the effects of internal pressure and arbitrary combinations of bending moment, torsional moment, axial force, and sheer force on the ends of the branch and run pipes. A limited temperature stress analysis capability is provided. EP, the elasto-plastic stress analysis program which analyzes pipe joints for the effects of internal pressure and arbitrary combinations of forces (including moments) and displacements including rotations imposed on the ends of the run and branch pipes. THFA, the transient heat flow analysis program which determines the time history of temperature variations in the pipe joints. The joint is assumed initially to be at a uniform temperature. Temperature changes are then specified at the inner surface, and a heat flow analysis is performed assuming a perfectly insulated outer surface. SHFA, the steady-state heat flow analysis program which determines the steady-state temperature distribution in pipe joints. Temperatures are specified on given cross-sections of the branch and run portions of the tee joint, and the temperature distribution throughout the remainder of the joint is calculated assuming the inner and outer surfaces are perfectly insulated. TSA, accepts as input, the output data from THFA or SHFA and performs the thermal stress analysis on the pipe joints. 2 - Method of solution: The joint is idealized as a system of 8-node hexahedral finite elements. A modified Zienkiewicz-Irons iso-parametric element which has superior bending properties compared with the unmodified iso-parametric element is used. The transient heat flow (THFA) problem is solved by a step-by-step integration procedure assuming linear variation of temperature with time within a step. 3 - Restrictions on the complexity of
SPM analysis and cognitive dysfunctions in patients with transient global amnesia
Energy Technology Data Exchange (ETDEWEB)
Jeong, Young Jin; Kang, Do Young; Yun, Go Un; Park, Kyung Won; Kim, Jae Woo [School of Medicine, Donga University, Busan (Korea, Republic of)
2004-07-01
Transient global amnesia (TGA) is known as a disease of benign nature characterized with clinically transient global antegrade amnesia and a variable degree of global retrograde memory impairment, but it usually resolved within 24 hours. The aims of this study are to assess the alterations in regional cerebral blood flow (rCBF) by Tc-99m HMPAO SPECT imaging with statistical parametric mapping (SPM) analysis and to verify the cognitive deficits by neuropsychological test in TGA patients. Twelve patients with TGA and age-matched normal control subjects participated in this study. Tc-99m HMPAO SPECT was performed within 1 to 19 days (mean duration: 7.3:{+-}5.2 days) after the events to measure the rCBF. SPECT images were analyzed using SPM (SPM99) with Matlab 5.3. Seoul Neuropsychological Screening Battery test was also done within 2 to 8 days (mean duration 3.8{+-}2.2 days) for cognitive functions in 8 of 12 patients with TGA. The SPM analysis of SPECT images showed significantly decreased rCBF in the left inferior frontal gyrus (Brodmann area 9), the left supramarginal gyrus (Brodmann area 40), the left postcentral gyrus (Brodmann area 40) and the left precentral gyrus (Brodmann area 4) in patients with TGA (uncorrected p<0.01). Neuropsychological test findings represented that several cognitive functions. such as, verbal memory, visual memory, phonemic fluency and confrontational naming, were impaired in patients with TGA compared with normal control. Additionally, on SPM analysis, we found lesions of hyperperfusion in contralateral cerebral hemisphere. Our study shows perfusion deficits in the left cerebral hemisphere in patients with TGA and several cognitive dysfunctions. And we found after clinical symptoms were completely resolved, the lesions of hypoperfusion were still remained. We found that functional quantitative neuroimaging study and neuropsychological test are useful to understand underlying pathomachanism of TGA.
SPM analysis and cognitive dysfunctions in patients with transient global amnesia
International Nuclear Information System (INIS)
Jeong, Young Jin; Kang, Do Young; Yun, Go Un; Park, Kyung Won; Kim, Jae Woo
2004-01-01
Transient global amnesia (TGA) is known as a disease of benign nature characterized with clinically transient global antegrade amnesia and a variable degree of global retrograde memory impairment, but it usually resolved within 24 hours. The aims of this study are to assess the alterations in regional cerebral blood flow (rCBF) by Tc-99m HMPAO SPECT imaging with statistical parametric mapping (SPM) analysis and to verify the cognitive deficits by neuropsychological test in TGA patients. Twelve patients with TGA and age-matched normal control subjects participated in this study. Tc-99m HMPAO SPECT was performed within 1 to 19 days (mean duration: 7.3:±5.2 days) after the events to measure the rCBF. SPECT images were analyzed using SPM (SPM99) with Matlab 5.3. Seoul Neuropsychological Screening Battery test was also done within 2 to 8 days (mean duration 3.8±2.2 days) for cognitive functions in 8 of 12 patients with TGA. The SPM analysis of SPECT images showed significantly decreased rCBF in the left inferior frontal gyrus (Brodmann area 9), the left supramarginal gyrus (Brodmann area 40), the left postcentral gyrus (Brodmann area 40) and the left precentral gyrus (Brodmann area 4) in patients with TGA (uncorrected p<0.01). Neuropsychological test findings represented that several cognitive functions. such as, verbal memory, visual memory, phonemic fluency and confrontational naming, were impaired in patients with TGA compared with normal control. Additionally, on SPM analysis, we found lesions of hyperperfusion in contralateral cerebral hemisphere. Our study shows perfusion deficits in the left cerebral hemisphere in patients with TGA and several cognitive dysfunctions. And we found after clinical symptoms were completely resolved, the lesions of hypoperfusion were still remained. We found that functional quantitative neuroimaging study and neuropsychological test are useful to understand underlying pathomachanism of TGA
Rampidis, I.; Nikolopoulos, A.; Koukouzas, N.; Grammelis, P.; Kakaras, E.
2007-09-01
This work aims to present a pure 3-D CFD model, accurate and efficient, for the simulation of a pilot scale CFB hydrodynamics. The accuracy of the model was investigated as a function of the numerical parameters, in order to derive an optimum model setup with respect to computational cost. The necessity of the in depth examination of hydrodynamics emerges by the trend to scale up CFBCs. This scale up brings forward numerous design problems and uncertainties, which can be successfully elucidated by CFD techniques. Deriving guidelines for setting a computational efficient model is important as the scale of the CFBs grows fast, while computational power is limited. However, the optimum efficiency matter has not been investigated thoroughly in the literature as authors were more concerned for their models accuracy and validity. The objective of this work is to investigate the parameters that influence the efficiency and accuracy of CFB computational fluid dynamics models, find the optimum set of these parameters and thus establish this technique as a competitive method for the simulation and design of industrial, large scale beds, where the computational cost is otherwise prohibitive. During the tests that were performed in this work, the influence of turbulence modeling approach, time and space density and discretization schemes were investigated on a 1.2 MWth CFB test rig. Using Fourier analysis dominant frequencies were extracted in order to estimate the adequate time period for the averaging of all instantaneous values. The compliance with the experimental measurements was very good. The basic differences between the predictions that arose from the various model setups were pointed out and analyzed. The results showed that a model with high order space discretization schemes when applied on a coarse grid and averaging of the instantaneous scalar values for a 20 sec period, adequately described the transient hydrodynamic behaviour of a pilot CFB while the
Preliminary analysis of the transient overpower accident for CRBRP. Final report
International Nuclear Information System (INIS)
Kastenberg, W.E.; Frank, M.V.
1975-07-01
A preliminary analysis of the transient overpower accident for the Clinch River Breeder Reactor Plant (CRBRP) is presented. Several uncertainties in the analysis and the estimation of ramp rates during the transition to disassembly are discussed. The major conclusions are summarized
Transient thermal analysis as measurement method for IC package structural integrity
Hanß, Alexander; Schmid, Maximilian; Liu, E.; Elger, Gordon
2015-06-01
Practices of IC package reliability testing are reviewed briefly, and the application of transient thermal analysis is examined in great depth. For the design of light sources based on light emitting diode (LED) efficient and accurate reliability testing is required to realize the potential lifetimes of 105 h. Transient thermal analysis is a standard method to determine the transient thermal impedance of semiconductor devices, e.g. power electronics and LEDs. The temperature of the semiconductor junctions is assessed by time-resolved measurement of their forward voltage (Vf). The thermal path in the IC package is resolved by the transient technique in the time domain. This enables analyzing the structural integrity of the semiconductor package. However, to evaluate thermal resistance, one must also measure the dissipated energy of the device (i.e., the thermal load) and the k-factor. This is time consuming, and measurement errors reduce the accuracy. To overcome these limitations, an innovative approach, the relative thermal resistance method, was developed to reduce the measurement effort, increase accuracy and enable automatic data evaluation. This new way of evaluating data simplifies the thermal transient analysis by eliminating measurement of the k-factor and thermal load, i.e. measurement of the lumen flux for LEDs, by normalizing the transient Vf data. This is especially advantageous for reliability testing where changes in the thermal path, like cracks and delaminations, can be determined without measuring the k-factor and thermal load. Different failure modes can be separated in the time domain. The sensitivity of the method is demonstrated by its application to high-power white InGaN LEDs. For detailed analysis and identification of the failure mode of the LED packages, the transient signals are simulated by time-resolved finite element (FE) simulations. Using the new approach, the transient thermal analysis is enhanced to a powerful tool for reliability
Stamper, David A.; Lund, David J.; Molchany, Jerome W.; Stuck, Bruce E.
1997-05-01
The proliferation of lasers for medical care, laser displays, industrial applications and audio- visual presentations has increased the potential for accidental intrabeam exposure to visible laser radiation. The output of these laser devices may be limited to below permissible exposure limits, but they are perceived as bright and can affect performance. The disruption experienced while viewing a laser is related to factors that include the retinal irradiance level, wavelength, ambient light level and mode (continuous wave (CW) and repetitively pulsed (RP)). This report describes studies where these factors were varied to assess the effects of laser light on tracking performance in a laboratory simulator and in a field study. Disruption was determined by measuring maximum error and total time off target. Performance disruption increased as irradiance levels increased and ambient light levels decreased.Under dawn/dusk conditions, relatively low-level laser energy produced performance disruption. Green laser light at the peak of the photopic sensitivity curve was more disruptive than red laser light. Increased error scores during CW and RP trials were attributed to average rather than peak power effects. More than 1500 laser exposures at levels up to MPE/2 have been given to volunteers. Despite transient performance disruption comparison of the pre- and post- laser visual performance tests and fundus evaluations wee unremarkable.
And yet it moves! Involving transient flow conditions is the logical next step for WHPA analysis
Rodriguez-Pretelin, A.; Nowak, W.
2017-12-01
As the first line of defense among different safety measures, Wellhead Protection Areas (WHPAs) have been broadly used to protect drinking water wells against sources of pollution. In most cases, their implementation relies on simplifications, such as assuming homogeneous or zonated aquifer conditions or considering steady-state flow scenarios. Obviously, both assumptions inevitably invoke errors. However, while uncertainty due to aquifer heterogeneity has been extensively studied in the literature, the impact of transient flow conditions have received yet very little attention. For instance, WHPA maps in the offices of water supply companies are fixed maps derived from steady-state models although the actual catchment out there are transient. To mitigate high computational costs, we approximate transiency by means of a dynamic superposition of steady-state flow solutions. Then, we analyze four transient drivers that often appear on the seasonal scale: (I) regional groundwater flow direction, (II) strength of the regional hydraulic gradient, (III) natural recharge to the groundwater and (IV) pumping rate. The integration of transiency in WHPA analysis leads to time-frequency maps. They express for each location the temporal frequency of catchment membership. Furthermore, we account for the uncertainty due to incomplete knowledge on geological and transiency conditions, solved through Monte Carlo simulations. The main contribution of this study, is to show the need of enhancing groundwater well protection by considering transient flow considerations during WHPA analysis. To support and complement our statement, we demonstrate that 1) each transient driver imprints an individual spatial pattern in the required WHPA, ranking their influence through a global sensitivity analysis. 2) We compare the influence of transient conditions compared to geological uncertainty in terms of areal WHPA demand. 3) We show that considering geological uncertainty alone is insufficient
Transient analysis of the new Cold Source at the FRM-II
International Nuclear Information System (INIS)
Gutsmiedl, E.; Posselt, H.; Scheuer, A.
2003-01-01
The new Cold Source (CNS) at the FRM-II research reactor is completely installed. This paper reports on the results of the transient analysis in the design status for this facility for producing cold neutrons for neutron experiments, the implementation of the results in the design of the mechanical components, the measurements at the cold tests and the comparison with the data of the transient analysis. The important load cases are fixed in the system description and the design data sheet of the CNS. A transient analysis was done with the computer program ESATAN, the nodal configuration was identical with the planned system of the CNS and the boundary conditions were chosen so, that conservative results can be expected. The following transients of the load cases in the piping system behind the inpile part 1) normal storage of D 2 at the hydride storage vessel 2) breakdown of cooling system of the CNS and transfer of D 2 to the buffer tank 3) rapid charge of D 2 to the buffer tank with break of the insulation vacuum and flooding of Neon 4) reloading of the D 2 from the buffer tank to the D 2 hydride storage vessel were calculated. Additionally the temperature distribution for these transients in the connecting flanges of the systems to the inpile part were analysed. The temperature distributions in the flange region were take into account for the strength calculation of the flange construction. The chosen construction shows allowable values and a leak tight flange connection for the load cases. The piping system was designed to the lowest expected temperatures. The load cases in the moderator tank were take into account in the stress analysis and the fatigue analysis of the vacuum vessel and the moderator vessel. The results shows allowable stresses. The results shows that a transient analysis is necessary and helpful for good design of the CNS. (author)
Ward, Michael J; Froehle, Craig M; Hart, Kimberly W; Collins, Sean P; Lindsell, Christopher J
2014-03-01
Little is known about the transient and sustained operational effects of electronic health records on emergency department (ED) performance. We quantify how the implementation of a comprehensive electronic health record was associated with metrics of operational performance, test ordering, and medication administration at a single-center ED. We performed a longitudinal analysis of electronic data from a single, suburban, academic ED during 28 weeks between May 2011 and November 2011. We assessed length of stay, use of diagnostic testing, medication administration, radiologic imaging, and patient satisfaction during a 4-week baseline measurement period and then tracked changes in these variables during the 24 weeks after implementation of the electronic health record. Median length of stay increased and patient satisfaction was reduced transiently, returning to baseline after 4 to 8 weeks. Rates of laboratory testing, medication administration, overall radiologic imaging, radiographs, computed tomography scans, and ECG ordering all showed sustained increases throughout the 24 weeks after electronic health record implementation. Electronic health record implementation in this single-center study was associated with both transient and sustained changes in metrics of ED performance, as well as laboratory and medication ordering. Understanding ways in which an ED can be affected by electronic health record implementation is critical to providing insight about ways to mitigate transient disruption and to maximize potential benefits of the technology. Copyright © 2013 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.
Transient analysis of a typical MTR fuel type research reactor by RELAP5/MOD 3.3
International Nuclear Information System (INIS)
Montazeri, A.; Bousbia Salah, A.; D'Auria, F.
2004-01-01
In this work the Transient Analysis for two different scenarios in a typical research reactor are considered. The first case is T he Spurious opening of the safety flapper valve, following reactor trip . The second case is the same as the first one, but the corresponding trip signal is not initiated, i.e. an anticipated transient without scram. The safety flapper valve is employed for natural convection in a typical swimming pool type research reactor. In both cases it is considered that the core is in steady state operation at full power. The reactor under consideration is a pool-type MTR core with maximum thermal capacity of 1 MW. Light water moderates the neutrons and a downward forced circulation of light water cools off the core as well. The analysis is performed using advanced computational tools, i.e. RELAP5/MOD 3.3
International Nuclear Information System (INIS)
Gregory, W.S.; Smith, P.R.; Bolstad, J.W.; Duerre, K.H.
1979-08-01
This report describes an initial study of explosive pressure transients and their propagation through ventilation systems. The objective of this study is to organize the required calculations into a computer code that is highly user-oriented and will predict explosive-induced gas dynamics within a ventilation system. The explosive process is subdivided into three regimes - deflagration, detonation, and transition from deflagration to detonation. Equations describing each process and suggested procedures for solving these equations are presented. The proposed organization of the explosion code capitalizes on the desirable aspects of the previously developed TVENT code, which predicts tornado-induced pressure transients within ventilation systems. The explosion code will include both near- and far-field analyses. The near-field analysis will use detailed models to describe the combustion process near the explosive event, and provide parametric driving potentials for flow in the regions that are removed from the explosive event (far-field). The far-field analysis will include the combustion wave as it propagates through the rest of the system
The importance of transient analysis in the light water reactor licensing procedure
International Nuclear Information System (INIS)
Izouierdo, J.M.; Villadoniga, J.I.
1979-01-01
The basic principles of the Nuclear Regulation are developed in the first part of this report. The achievement of the safety objective by establishing protections -that prevent or reduce the barriers failure- is analyzed. An iterative method for the definition of the systems and components safety design bases is proposed, analyzing the role of Technical Specifications in this process. The second part shows how this methodology can be used in the case of the first barrier: the fuel cladding. The safety criteria, transient clasification problems, transient analysis and its relation with surveillance and protection systems, and the role of such analysis in fuel protection design verification are discused. (author)
Bonald, Thomas
2013-01-01
The book presents some key mathematical tools for the performance analysis of communication networks and computer systems.Communication networks and computer systems have become extremely complex. The statistical resource sharing induced by the random behavior of users and the underlying protocols and algorithms may affect Quality of Service.This book introduces the main results of queuing theory that are useful for analyzing the performance of these systems. These mathematical tools are key to the development of robust dimensioning rules and engineering methods. A number of examples i
Chin, Jeffrey C.; Csank, Jeffrey T.
2016-01-01
The Tool for Turbine Engine Closed-Loop Transient Analysis (TTECTrA ver2) is a control design tool thatenables preliminary estimation of transient performance for models without requiring a full nonlinear controller to bedesigned. The program is compatible with subsonic engine models implemented in the MATLAB/Simulink (TheMathworks, Inc.) environment and Numerical Propulsion System Simulation (NPSS) framework. At a specified flightcondition, TTECTrA will design a closed-loop controller meeting user-defined requirements in a semi or fully automatedfashion. Multiple specifications may be provided, in which case TTECTrA will design one controller for each, producing acollection of controllers in a single run. Each resulting controller contains a setpoint map, a schedule of setpointcontroller gains, and limiters; all contributing to transient characteristics. The goal of the program is to providesteady-state engine designers with more immediate feedback on the transient engine performance earlier in the design cycle.
Energy Technology Data Exchange (ETDEWEB)
Hazen, Damian [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Hick, Jason [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
2012-06-12
We provide analysis of Oracle StorageTek T10000 Generation B (T10KB) Media Information Record (MIR) Performance Data gathered over the course of a year from our production High Performance Storage System (HPSS). The analysis shows information in the MIR may be used to improve tape subsystem operations. Most notably, we found the MIR information to be helpful in determining whether the drive or tape was most suspect given a read or write error, and for helping identify which tapes should not be reused given their history of read or write errors. We also explored using the MIR Assisted Search to order file retrieval requests. We found that MIR Assisted Search may be used to reduce the time needed to retrieve collections of files from a tape volume.
TRANSPA: a code for transient thermal analysis of a single fuel pin
International Nuclear Information System (INIS)
Prenger, F.C.
1985-02-01
An analytical model (TRANSPA) for the transient thermal analysis of a single uranium carbide fuel pin was developed. This model uses thermal boundary conditions obtained from COBRA-WC output and calculates the transient thermal response of a single fuel pin to changes in internal power generation, coolant flowrate, or fuel pin physical configuration. The model uses the MITAS finite difference thermal analyzer. MITAS provides the means to input separate conductance models through the use of a user subroutine input capability. The model is a lumped-mass representation of the fuel pin using 26 nodes and 42 conductors. Run time for each transient analysis is approximately one minute of central processor time on the NOS operating system
Neural-network-based adaptive UPFC for improving transient stability performance of power system.
Mishra, Sukumar
2006-03-01
This paper uses the recently proposed H(infinity)-learning method, for updating the parameter of the radial basis function neural network (RBFNN) used as a control scheme for the unified power flow controller (UPFC) to improve the transient stability performance of a multimachine power system. The RBFNN uses a single neuron architecture whose input is proportional to the difference in error and the updating of its parameters is carried via a proportional value of the error. Also, the coefficients of the difference of error, error, and auxiliary signal used for improving damping performance are depicted by a genetic algorithm. The performance of the newly designed controller is evaluated in a four-machine power system subjected to different types of disturbances. The newly designed single-neuron RBFNN-based UPFC exhibits better damping performance compared to the conventional PID as well as the extended Kalman filter (EKF) updating-based RBFNN scheme, making the unstable cases stable. Its simple architecture reduces the computational burden, thereby making it attractive for real-time implementation. Also, all the machines are being equipped with the conventional power system stabilizer (PSS) to study the coordinated effect of UPFC and PSS in the system.
International Nuclear Information System (INIS)
Chen, Lei; Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui; Zhu, Lin; Guo, Fang
2015-01-01
Highlights: • A modified flux-coupling type SFCL is suggested to enhance the transient performance of a micro-grid. • The SFCL’s main contribution is to improve the micro-grid’s fault ride-through capability. • The SFCL also can make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. • The simulations show that the SFCL can availably strengthen the micro-grid’s voltage and frequency stability. - Abstract: Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid’s operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid’s fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL’s contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.
Energy Technology Data Exchange (ETDEWEB)
Roberto, Thiago D., E-mail: thiagodbtr@gmail.com [Instituto de Engenharia Nuclear (IEN/CNEN—RJ), Rua Hélio de Almeida, 75 21941-972, Rio de Janeiro Caixa-Postal: 68550, RJ (Brazil); Silva, Mário A. B. da, E-mail: mabs500@gmail.com [Departamento de Energia Nuclear (CTG/UFPE), Av. Professor Luiz Freire, 1000, Recife 50740-540, PE (Brazil); Lapa, Celso M.F., E-mail: lapa@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN—RJ), Rua Hélio de Almeida, 75 21941-972, Rio de Janeiro Caixa-Postal: 68550, RJ (Brazil)
2016-01-15
The feasibility of performing experiments using water under supercritical conditions is limited by technical and financial difficulties. These difficulties can be overcome by using model fluids that are characterized by feasible supercritical conditions, that is, lower critical pressure and critical temperature. Experimental investigations are normally used to determine the conditions under which model fluids reliably represent supercritical fluids under steady-state conditions. A fluid-to-fluid scaling approach has been proposed to determine the model fluids that represent supercritical fluids in a transient state. Recently, a similar technique known as fractional scaling analysis was developed to establish the conditions under which experiments can be performed using models that represent transients in prototypes. This paper presents a fractional scaling analysis application to determine parameters for a test facility in which transient conditions in supercritical water-cooled reactors are simulated by using carbon dioxide as a model fluid, whose critical point conditions are more feasible than those of water. Similarity is obtained between water (prototype) and carbon dioxide (model) by depressurization in a simple vessel. The main parameters required for the construction of a future test facility are obtained using the proposed method.
Performance and stability analysis of a photovoltaic power system
Merrill, W. C.; Blaha, R. J.; Pickrell, R. L.
1978-01-01
The performance and stability characteristics of a 10 kVA photovoltaic power system are studied using linear Bode analysis and a nonlinear analog simulation. Power conversion efficiencies, system stability, and system transient performance results are given for system operation at various levels of solar insolation. Additionally, system operation and the modeling of system components for the purpose of computer simulation are described.
Stress analysis in pipelines submitted to internal pressure - and temperature transients
International Nuclear Information System (INIS)
Mansur, T.R.
1981-08-01
Experimental determination of the structural behaviour of a thermal-hydraulic loop, when submitted to simultaneous fast change of pressure and temperature, was performed. For this, electrical strain-gages were positioned at some critical points in order to measure the deformation conditions of the structure. The study of the kinetics of the deformation revealed the presence of important transient stresses, mainly from thermal origin. After this transient behaviour, the structure is submitted to a thermal stress, which is shown to be strongly dependent on the degree of restraint of the structure. (Author) [pt
International Nuclear Information System (INIS)
Guerreiro, J.N.C.; Loula, A.F.D.
1988-12-01
The mixed Petrov-Galerkin finite element formulation is applied to transiente and steady state creep problems. Numerical analysis has shown additional stability of this method compared to classical Galerkin formulations. The accuracy of the new formulation is confirmed in some representative examples of two dimensional and axisymmetric problems. (author) [pt
Modal analysis of spatial effects on transients in nuclear power reactor
International Nuclear Information System (INIS)
Agueda, O.
1976-01-01
The solution of the linearized space dependant reactor kinetics equations with fuel and moderator temperature coefficient feed backs are obtained by modal analysis. The heat transfer from fuel to moderator is explicitly considered through the heat balance equations. The delayed neutrons are lumped into one group. The space dependant transients due to localized perturbation such as insertion of fuel rod or withdrawal of control rod and uniform perturbation such as fractional loss of the coolant flow in a PWR are determined and compared with the solutions of space independent solutions. Transients resulting from a simultaneous introduction of localized and uniform perturbation are also examined. (author)
Inverse Transient Analysis for Classification of Wall Thickness Variations in Pipelines
Directory of Open Access Journals (Sweden)
Jeffrey Tuck
2013-12-01
Full Text Available Analysis of transient fluid pressure signals has been investigated as an alternative method of fault detection in pipeline systems and has shown promise in both laboratory and field trials. The advantage of the method is that it can potentially provide a fast and cost effective means of locating faults such as leaks, blockages and pipeline wall degradation within a pipeline while the system remains fully operational. The only requirement is that high speed pressure sensors are placed in contact with the fluid. Further development of the method requires detailed numerical models and enhanced understanding of transient flow within a pipeline where variations in pipeline condition and geometry occur. One such variation commonly encountered is the degradation or thinning of pipe walls, which can increase the susceptible of a pipeline to leak development. This paper aims to improve transient-based fault detection methods by investigating how changes in pipe wall thickness will affect the transient behaviour of a system; this is done through the analysis of laboratory experiments. The laboratory experiments are carried out on a stainless steel pipeline of constant outside diameter, into which a pipe section of variable wall thickness is inserted. In order to detect the location and severity of these changes in wall conditions within the laboratory system an inverse transient analysis procedure is employed which considers independent variations in wavespeed and diameter. Inverse transient analyses are carried out using a genetic algorithm optimisation routine to match the response from a one-dimensional method of characteristics transient model to the experimental time domain pressure responses. The accuracy of the detection technique is evaluated and benefits associated with various simplifying assumptions and simulation run times are investigated. It is found that for the case investigated, changes in the wavespeed and nominal diameter of the
Analysis of transient heat conduction in a PWR fuel rod by an improved lumped parameter approach
Energy Technology Data Exchange (ETDEWEB)
Dourado, Eneida Regina G. [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil); Cotta, Renato M. [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Mecanica; Jian, Su, E-mail: eneidadourado@gmail.com, E-mail: sujian@nuclear.ufrj.br, E-mail: cotta@mecanica.ufrj.br [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear
2017-07-01
This paper aims to analyze transient heat conduction in a nuclear fuel rod by an improved lumped parameter approach. One-dimensional transient heat conduction is considered, with the circumferential symmetry assumed and the axial conduction neglected. The thermal conductivity and specific heat in the fuel pellet are considered temperature dependent, while the thermophysical properties of the cladding are considered constant. Hermite approximation for integration is used to obtain the average temperature and heat flux in the radial direction. Significant improvement over the classical lumped parameter formulation has been achieved. The proposed model can be also used in dynamic analysis of PWR and nuclear power plant simulators. (author)
Directory of Open Access Journals (Sweden)
Masaru Ishizuka
2011-01-01
Full Text Available In recent years, there is a growing demand to have smaller and lighter electronic circuits which have greater complexity, multifunctionality, and reliability. High-density multichip packaging technology has been used in order to meet these requirements. The higher the density scale is, the larger the power dissipation per unit area becomes. Therefore, in the designing process, it has become very important to carry out the thermal analysis. However, the heat transport model in multichip modules is very complex, and its treatment is tedious and time consuming. This paper describes an application of the thermal network method to the transient thermal analysis of multichip modules and proposes a simple model for the thermal analysis of multichip modules as a preliminary thermal design tool. On the basis of the result of transient thermal analysis, the validity of the thermal network method and the simple thermal analysis model is confirmed.
On uncertainty and local sensitivity analysis for transient conjugate heat transfer problems
International Nuclear Information System (INIS)
Rauch, Christian
2012-01-01
The need for simulating real-world behavior of automobiles has led to more and more sophisticated models being added of various physical phenomena for being coupled together. This increases the number of parameters to be set and, consequently, the required knowledge of their relative importance for the solution and the theory behind them. Sensitivity and uncertainty analysis provides the knowledge of parameter importance. In this paper a thermal radiation solver is considered that performs conduction calculations and receives heat transfer coefficient and fluid temperate at a thermal node. The equations of local, discrete, and transient sensitivities for the conjugate heat transfer model solved by the finite difference method are being derived for some parameters. In the past, formulations for the finite element method have been published. This paper builds on the steady-state formulation published previously by the author. A numerical analysis on the stability of the solution matrix is being conducted. From those normalized sensitivity coefficients are calculated dimensionless uncertainty factors. On a simplified example the relative importance of the heat transfer modes at various locations is then investigated by those uncertainty factors and their changes over time
Iacomini, Christie; Powers, Aaron; Speight, Garland; Padilla, Sebastian; Paul, Heather L.
2009-01-01
A Metabolic heat-regenerated Temperature Swing Adsorption (MTSA) system is being developed for carbon dioxide, water and thermal control in a lunar and martian portable life support system (PLSS). A previous system analysis was performed to evaluate the impact of MTSA on PLSS design. That effort was Mars specific and assumed liquid carbon dioxide (LCO2) coolant made from martian resources. Transient effects were not considered but rather average conditions were used throughout the analysis. This effort takes into further consideration the transient effects inherent in the cycling MTSA system as well as assesses the use of water as coolant. Standard heat transfer, thermodynamic, and heat exchanger methods are presented to conduct the analysis. Assumptions and model verification are discussed. The tool was used to perform various system studies. Coolant selection was explored and takes into account different operational scenarios as the minimum bed temperature is driven by the sublimation temperature of the coolant (water being significantly higher than LCO2). From this, coolant mass is sized coupled with sorbent bed mass because MTSA adsorption performance decreases with increasing sublimation temperature. Reduction in heat exchanger performance and even removal of certain heat exchangers, like a recuperative one between the two sorbent beds, is also investigated. Finally, the coolant flow rate is varied over the cycle to determine if there is a more optimal means of cooling the bed from a mass perspective. Results of these studies and subsequent recommendations for system design are presented.
Zhu, L.; Zhang, H. P.; Zhang, J. G.; Meng, X. C.; Lu, L.
2012-11-01
In this paper, a bulb turbine, with unit specific speed of nq=223.1 min-1 suitable for low prototype head was studied from aspect of its performance. Hydraulic model of the turbine was developed firstly, and then model turbine was designed and manufactured. Performance tests were carried out on high-accuracy hydraulic machinery model universal test rig located at IWHR, including energy, cavitation and pressure fluctuation tests, etc. In order to investigate internal flow field, three-dimensional transient turbulence numerical simulation was conducted on the tested turbine, adopting Reynolds-averaged Navier-Stocks control equations and RNG k-ɛ turbulence model. Test and simulation results show that: (1) hydraulic efficiency of model turbine ηM is up to 91.7%, at the optimum operating point of n11o=165.54 r/min versus Q11o=1.93 m3/s; (2) numerical results agree well with experimental resultsby comparing pressure fluctuation, which shows that pressure amplitude is very low at the optimum operating point; (3) hydraulic loss in Outflow domain accounts for more than 50% total hydraulic loss due to flow separation and secondary flow.
Thermal hydraulic transient analysis of the HTR-10
International Nuclear Information System (INIS)
Gao Zuying; Shi Lei
2002-01-01
The HTR-10 is the first high temperature gas-cooled test module reactor built in China. In the accident analysis, typical design basis accident and beyond design basis accident (BDBA), including the reactivity accident, the loss of external power ATWS, the air ingress accident and water ingress accident into the primary system are selected and detailed analyzed. The results show that the HTR-10 has inherent safety properties. The maximum fuel element temperature will not exceed the limit value 1230 deg. C. The total amount of graphite corrosion maintains no more than 320 kg, the exposure ratio of first coated particles is less than 2.4% in the BDBA. The released radioactivity is limited at a low level and the ability of fuel particles to retain fission products is not corrupted. Even the consequence of the severest hypothetical accident has no safety danger to the reactor. The reactor can shut itself down via its negative temperature coefficient of reactivity in heat-up conditions
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
Energy Technology Data Exchange (ETDEWEB)
Chien, T.H.; Domanus, H.M.; Sha, W.T.
1993-02-01
The COMMIX-PPC computer pregrain is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex Industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional equations of conservation of mass, momentum, and energy on the tube stile and the proper accounting for the thermal interaction between shell and tube side through the porous-medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient. Three-dimensional analysis of fluid flow with heat transfer tn a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification, it can be used to analyze processes in any heat exchanger or other single-phase engineering applications. Volume I (Equations and Numerics) of this report describes in detail the basic equations, formulation, solution procedures, and models for a phenomena. Volume II (User's Guide and Manual) contains the input instruction, flow charts, sample problems, and descriptions of available options and boundary conditions.
Energy Technology Data Exchange (ETDEWEB)
Chien, T.H.; Domanus, H.M.; Sha, W.T.
1993-02-01
The COMMIX-PPC computer program is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional conservation of mass. momentum, and energy equations on the tube side, and the proper accounting for the thermal interaction between shell and tube side through the porous medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient three-dimensional analysis of fluid flow with heat transfer in a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification. it can be used to analyze processes in any heat exchanger or other single-phase engineering applications.
Analysis of core uncovery time in Kuosheng station blackout transient with MELCOR
International Nuclear Information System (INIS)
Wang, S.J.; Chien, C.S.
1996-01-01
The MELCOR code, developed by the Sandia National Laboratories, is capable of simulating severe accident phenomena of nuclear power plants. Core uncovery time is an important parameter in the probabilistic risk assessment. However, many MELCOR users do not generate the initial conditions in a station blackout (SBO) transient analysis. Thus, achieving reliable core uncovery time is difficult. The core uncovery time for the Kuosheng nuclear power plant during an SBO transient is analyzed. First, full-power steady-state conditions are generated with the application of a developed self-initialization algorithm. Then the response of the SBO transient up to core uncovery is simulated. The effects of key parameters including the initialization process and the reactor feed pump (RFP) coastdown time on the core uncovery time are analyzed. The initialization process is the most important parameter that affects the core uncovery time. Because SBO transient analysis, the correct initial conditions must be generated to achieve a reliable core uncovery time. The core uncovery time is also sensitive to the RFP coastdown time. A correct time constant is required
Building America House Performance Analysis Procedures
Energy Technology Data Exchange (ETDEWEB)
Hendron, R.; Farrar-Nagy, S.; Anderson, R.; Judkoff, R.
2001-10-29
As the Building America Program has grown to include a large and diverse cross section of the home building industry, accurate and consistent analysis techniques have become more important to help all program partners as they perform design tradeoffs and calculate energy savings for prototype houses built as part of the program. This document illustrates some of the analysis concepts proven effective and reliable for analyzing the transient energy usage of advanced energy systems as well as entire houses. The analysis procedure described here provides a starting point for calculating energy savings of a prototype house relative to two base cases: builder standard practice and regional standard practice. Also provides building simulation analysis to calculate annual energy savings based on side-by-side short-term field testing of a prototype house.
International Nuclear Information System (INIS)
Kim, Soon Young; Suk, Ho Chun
2002-01-01
The performance of adjuster rod system in four operational transients of CANDU-6 RUFIC (Recovered Uranium Fuel In CANDU) core was preliminarily assessed, where the operational transients include startup after a short shutdown, startup after a poison-out shutdown, shim mode operation, and a stepback to 60% full power. The results of the preliminary assessment indicated that the adjuster rod system as currently designed and installed in the CANDU-6 NU (Natural Uranium) core will adequately meet the functional requirements in the RUFIC core. Comparing to the performance of adjuster rod system in the NU core, the total worth of the adjuster system in the RUFIC core is reduced, leading to less xenon override capability and shimming capability. In spite of the reduction of total worth, however, the overall performance of adjuster rod system in the operation transient of the RUFIC core is expected to still be satisfied. An alternative adjuster-banking scheme is also included in the assessment. The alternative adjuster-banking scheme involves rods in Bank 1 and Bank 7 being re-distributed within the two banks. The overall results from the transients studied indicated that the alternative banking scheme does show some better performance characteristics and merits
Present status of numerical analysis on transient two-phase flow
International Nuclear Information System (INIS)
Akimoto, Masayuki; Hirano, Masashi; Nariai, Hideki.
1987-01-01
The Special Committee for Numerical Analysis of Thermal Flow has recently been established under the Japan Atomic Energy Association. Here, some methods currently used for numerical analysis of transient two-phase flow are described citing some information given in the first report of the above-mentioned committee. Many analytical models for transient two-phase flow have been proposed, each of which is designed to describe a flow by using differential equations associated with conservation of mass, momentum and energy in a continuous two-phase flow system together with constructive equations that represent transportation of mass, momentum and energy though a gas-liquid interface or between a liquid flow and the channel wall. The author has developed an analysis code, called MINCS, that serves for systematic examination of conservation equation and constructive equations for two-phase flow models. A one-dimensional, non-equilibrium two-liquid flow model that is used as the basic model for the code is described. Actual procedures for numerical analysis is shown and some problems concerning transient two-phase analysis are described. (Nogami, K.)
Adaptive explicit and implicit finite element methods for transient thermal analysis
Probert, E. J.; Hassan, O.; Morgan, K.; Peraire, J.
1992-01-01
The application of adaptive finite element methods to the solution of transient heat conduction problems in two dimensions is investigated. The computational domain is represented by an unstructured assembly of linear triangular elements and the mesh adaptation is achieved by local regeneration of the grid, using an error estimation procedure coupled to an automatic triangular mesh generator. Two alternative solution procedures are considered. In the first procedure, the solution is advanced by explicit timestepping, with domain decomposition being used to improve the computational efficiency of the method. In the second procedure, an algorithm for constructing continuous lines which pass only once through each node of the mesh is employed. The lines are used as the basis of a fully implicit method, in which the equation system is solved by line relaxation using a block tridiagonal equation solver. The numerical performance of the two procedures is compared for the analysis of a problem involving a moving heat source applied to a convectively cooled cylindrical leading edge.
Brain SPECT analysis using statistical parametric mapping in patients with transient global amnesia
Energy Technology Data Exchange (ETDEWEB)
Kim, E. N.; Sohn, H. S.; Kim, S. H; Chung, S. K.; Yang, D. W. [College of Medicine, The Catholic Univ. of Korea, Seoul (Korea, Republic of)
2001-07-01
This study investigated alterations in regional cerebral blood flow (rCBF) in patients with transient global amnesia (TGA) using statistical parametric mapping 99 (SPM99). Noninvasive rCBF measurements using 99mTc-ethyl cysteinate dimer (ECD) SPECT were performed on 8 patients with TGA and 17 age matched controls. The relative rCBF maps in patients with TGA and controls were compared. In patients with TGA, significantly decreased rCBF was found along the left superior temporal extending to left parietal region of the brain and left thalamus. There were areas of increased rCBF in the right temporal, right frontal region and right thalamus. We could demonstrate decreased perfusion in left cerebral hemisphere and increased perfusion in right cerebral hemisphere in patients with TGA using SPM99. The reciprocal change of rCBF between right and left cerebral hemisphere in patients with TGA might suggest that imbalanced neuronal activity between the bilateral hemispheres may be important role in the pathogenesis of the TGA. For quantitative SPECT analysis in TGA patients, we recommend SPM99 rather than the ROI method because of its definitive advantages.
Brain SPECT analysis using statistical parametric mapping in patients with transient global amnesia
International Nuclear Information System (INIS)
Kim, E. N.; Sohn, H. S.; Kim, S. H; Chung, S. K.; Yang, D. W.
2001-01-01
This study investigated alterations in regional cerebral blood flow (rCBF) in patients with transient global amnesia (TGA) using statistical parametric mapping 99 (SPM99). Noninvasive rCBF measurements using 99mTc-ethyl cysteinate dimer (ECD) SPECT were performed on 8 patients with TGA and 17 age matched controls. The relative rCBF maps in patients with TGA and controls were compared. In patients with TGA, significantly decreased rCBF was found along the left superior temporal extending to left parietal region of the brain and left thalamus. There were areas of increased rCBF in the right temporal, right frontal region and right thalamus. We could demonstrate decreased perfusion in left cerebral hemisphere and increased perfusion in right cerebral hemisphere in patients with TGA using SPM99. The reciprocal change of rCBF between right and left cerebral hemisphere in patients with TGA might suggest that imbalanced neuronal activity between the bilateral hemispheres may be important role in the pathogenesis of the TGA. For quantitative SPECT analysis in TGA patients, we recommend SPM99 rather than the ROI method because of its definitive advantages
Cerebral blood flow SPET in transient global amnesia with automated ROI analysis by 3DSRT
Energy Technology Data Exchange (ETDEWEB)
Takeuchi, Ryo [Division of Nuclear Medicine, Nishi-Kobe Medical Center, Kohjidai 5-7-1, 651-2273, Nishi-ku, Kobe-City, Hyogo (Japan); Matsuda, Hiroshi [Department of Radiology, National Center Hospital for Mental, Nervous and Muscular Disorders, National Center of Neurology and Psychiatry, Tokyo (Japan); Yoshioka, Katsunori [Daiichi Radioisotope Laboratories, Ltd., Tokyo (Japan); Yonekura, Yoshiharu [Biomedical Imaging Research Center, University of Fukui, Fukui (Japan)
2004-04-01
The aim of this study was to determine the areas involved in episodes of transient global amnesia (TGA) by calculation of cerebral blood flow (CBF) using 3DSRT, fully automated ROI analysis software which we recently developed. Technetium-99m l,l-ethyl cysteinate dimer single-photon emission tomography ({sup 99m}Tc-ECD SPET) was performed during and after TGA attacks on eight patients (four men and four women; mean study interval, 34 days). The SPET images were anatomically standardized using SPM99 followed by quantification of 318 constant ROIs, grouped into 12 segments (callosomarginal, precentral, central, parietal, angular, temporal, posterior cerebral, pericallosal, lenticular nucleus, thalamus, hippocampus and cerebellum), in each hemisphere to calculate segmental CBF (sCBF) as the area-weighted mean value for each of the respective 12 segments based on the regional CBF in each ROI. Correlation of the intra- and post-episodic sCBF of each of the 12 segments of the eight patients was estimated by scatter-plot graphical analysis and Pearson's correlation test with Fisher's Z-transformation. For the control, {sup 99m}Tc-ECD SPET was performed on eight subjects (three men and five women) and repeated within 1 month; the correlation between the first and second sCBF values of each of the 12 segments was evaluated in the same way as for patients with TGA. Excellent reproducibility between the two sCBF values was found in all 12 segments of the control subjects. However, a significant correlation between intra- and post-episodic sCBF was not shown in the thalamus or angular segments of TGA patients. The present study was preliminary, but at least suggested that thalamus and angular regions are closely involved in the symptoms of TGA. (orig.)
Cerebral blood flow SPET in transient global amnesia with automated ROI analysis by 3DSRT
International Nuclear Information System (INIS)
Takeuchi, Ryo; Matsuda, Hiroshi; Yoshioka, Katsunori; Yonekura, Yoshiharu
2004-01-01
The aim of this study was to determine the areas involved in episodes of transient global amnesia (TGA) by calculation of cerebral blood flow (CBF) using 3DSRT, fully automated ROI analysis software which we recently developed. Technetium-99m l,l-ethyl cysteinate dimer single-photon emission tomography ( 99m Tc-ECD SPET) was performed during and after TGA attacks on eight patients (four men and four women; mean study interval, 34 days). The SPET images were anatomically standardized using SPM99 followed by quantification of 318 constant ROIs, grouped into 12 segments (callosomarginal, precentral, central, parietal, angular, temporal, posterior cerebral, pericallosal, lenticular nucleus, thalamus, hippocampus and cerebellum), in each hemisphere to calculate segmental CBF (sCBF) as the area-weighted mean value for each of the respective 12 segments based on the regional CBF in each ROI. Correlation of the intra- and post-episodic sCBF of each of the 12 segments of the eight patients was estimated by scatter-plot graphical analysis and Pearson's correlation test with Fisher's Z-transformation. For the control, 99m Tc-ECD SPET was performed on eight subjects (three men and five women) and repeated within 1 month; the correlation between the first and second sCBF values of each of the 12 segments was evaluated in the same way as for patients with TGA. Excellent reproducibility between the two sCBF values was found in all 12 segments of the control subjects. However, a significant correlation between intra- and post-episodic sCBF was not shown in the thalamus or angular segments of TGA patients. The present study was preliminary, but at least suggested that thalamus and angular regions are closely involved in the symptoms of TGA. (orig.)
Performance of transient elastography in diagnosis of nonalcoholic fatty liver disease
Directory of Open Access Journals (Sweden)
ZHUANG Xiaofang
2017-12-01
Full Text Available ObjectiveTo investigate the value of transient elastography (TE in the diagnosis of nonalcoholic fatty liver disease (NAFLD. MethodsA total of 21 patients without fatty liver disease and 92 patients with NAFLD, who visited Traditional Chinese Medicine Hospital of Xinjiang Uygur Autonomous Region from June to December, 2016, were enrolled. Their general information was collected and body mass index (BMI was calculated. Routine blood test, liver function evaluation, and measurement of blood lipid, serum insulin, and alpha-fetoprotein were performed, and liver CT and FibroTouch were performed. The receiver operating characteristic (ROC curve was plotted with liver/spleen CT ratio as diagnostic criteria, and the ROC curve was used to evaluate the ability of controlled attenuation parameter (CAP to diagnose NAFLD. The area under the ROC curve (AUC was calculated, the Z test was used to evaluate diagnostic effectiveness, and Youden index was used to determine the optimal cut-off value. The t-test was used for comparison of normally distributed continuous data between two groups; a one-way analysis of variance was used for comparison between multiple groups, and the least significant difference t-test was used for further comparison between any two groups. The Mann-Whitney U test was used for comparison of non-normally distributed continuous data between two groups, and the Kruskal-Wallis H test was used for comparison between multiple groups. The chi-square test was used for comparison of categorical data between groups. ResultsThere were significant differences in age, alanine aminotransferase (ALT, aspartate aminotransferase (AST, serum insulin, fat attenuation, and liver stiffness measurement (LSM between the patients without fatty liver disease and those with varying degrees of NAFLD (all P＜0.05. The severe NAFLD group had a significantly lower mean age than the non-fatty liver disease group (P＜0.001. There was a significant difference in CAP
Review of HEDL fuel pin transient analyses analytical programs
International Nuclear Information System (INIS)
Scott, J.H.; Baars, R.E.
1975-05-01
Methods for analysis of transient fuel pin performance are described, as represented by the steady-state SIEX code and the PECT series of codes used for steady-state and transient mechanical analyses. The empirical fuel failure correlation currently in use for analysis of transient overpower accidents is described. (U.S.)
TRANSIENT ANALYSIS OF WIND DIESEL POWER SYSTEM WITH FLYWHEEL ENERGY STORAGE
Directory of Open Access Journals (Sweden)
S. SUJITH
2017-10-01
Full Text Available Wind-Diesel Hybrid power generation is a viable alternative for generating continuous power to isolated power system areas which have inconsistent but potential wind power. The unpredictable nature of variable power from Wind generator to the system is compensated by Diesel generator, which supplies the deficit in generated power from wind to meet the instantaneous system load. However, one of the major challenges for such a system is the higher probability of transients in the form of wind and load fluctuations. This paper analyses the application of Flywheel Energy storage system (FESS to meet the transients during wind-speed and load fluctuations around high wind operation. The power system architecture, the distributed control mechanism governing the flow of power transfer and the modelling of major system components has been discussed and the system performances have been validated using MATLAB /Simulink software. Two cases of transient stages around the high wind system operation are discussed. The simulation results highlight the effective usage of FESS in reducing the peak overshoot of active power transients, smoothes the active power curves and helps in reducing the diesel consumption during the flywheel discharge period, without affecting the continuous power supply for meeting the instantaneous load demand.
ERP-IV-A program for transient thermal-hydraulic analysis of PWR plant
International Nuclear Information System (INIS)
Dai Anguo; Tang Jiahuan; Qian Huifu; Gao Zhikang
1987-12-01
The author deal with the descriptions of physical model of transient process in PWR plant and the function of ERP-IV (ERR-IV Transient Thermo-Hydraulic Analysis Code). The code has been developed for safety analysis and design transient. The code is characterized by the multi-loop long-term, short term, wide-range plant simulation with the capability to analyze natural circulation condition. The description of ERP-IV includes following parts: reactor, primary coolant loops, pressurizer, steam generators, main steam system, turbine, feedwater system, steam dump, relive valves, and safety valves in secondary side, etc.. The code can use for accident analysis, such as loss of all A.C. power to power plant auxiliaries (a station blackout), loss of normal feedwater, loss of load, loss of condenser vacuum and other events causing a turbine trip, complete loss of forced reactor coolant flow, uncontrolled rod cluster control assembly bank withdrawal. It can also be used for accident analysis of the emergency and limiting conditions, such as feedwater line break and main steam line rupture. It can also be utilized as a tool for system design studies, component design, setpoint studies and design transition studies, etc
Transient thermal-hydraulic characteristics analysis software for PWR nuclear power systems
International Nuclear Information System (INIS)
Wu Yingwei; Zhuang Chengjun; Su Guanghui; Qiu Suizheng
2010-01-01
A point reactor neutron kinetics model, a two-phase drift-flow U-tube steam generator model, an advanced non-equilibrium three regions pressurizer model, and a passive emergency core decay heat-removed system model are adopted in the paper to develop the computerized analysis code for PWR transient thermal-hydraulic characteristics, by Compaq Visual Fortran 6.0 language. Visual input, real-time processing and dynamic visualization output are achieved by Microsoft Visual Studio. NET language. The reliability verification of the soft has been conducted by RELAP 5, and the verification results show that the software is with high calculation precision, high calculation speed, modern interface, luxuriant functions and strong operability. The software was applied to calculate the transient accident conditions for QSNP, and the analysis results are significant to the practical engineering applications. (authors)
Transient Three-Dimensional Side Load Analysis of a Film Cooled Nozzle
Wang, Ten-See; Guidos, Mike
2008-01-01
Transient three-dimensional numerical investigations on the side load physics for an engine encompassing a film cooled nozzle extension and a regeneratively cooled thrust chamber, were performed. The objectives of this study are to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet history based on an engine system simulation. Ultimately, the computational results will be provided to the nozzle designers for estimating of effect of the peak side load on the nozzle structure. Computations simulating engine startup at ambient pressures corresponding to sea level and three high altitudes were performed. In addition, computations for both engine startup and shutdown transients were also performed for a stub nozzle, operating at sea level. For engine with the full nozzle extension, computational result shows starting up at sea level, the peak side load occurs when the lambda shock steps into the turbine exhaust flow, while the side load caused by the transition from free-shock separation to restricted-shock separation comes at second; and the side loads decreasing rapidly and progressively as the ambient pressure decreases. For the stub nozzle operating at sea level, the computed side loads during both startup and shutdown becomes very small due to the much reduced flow area.
Development of a system code for transient analysis in a HTGR
International Nuclear Information System (INIS)
Lee, Tae Beom
2004-02-01
A GAMMA (GAs Multi-component Multi-dimensional Analysis) code is developed for transient analysis and air ingress analysis in High Temperature Gas-cooled Reactors (HTGR). The PBMR of ESKOM is selected as a reference plant for the High Temperature Gas-cooled Reactor here, which uses a direct helium cycle and pebble fuel. Physical models included in GAMMA are the pebble conduction model, radiation heat transfer model, point kinetics model, decay heat model, and component models for break flow, valve, pump, cooler, power conversion unit model. The temperature distribution and the flow distribution of the PBMR are calculated for initial and accident core in the present study. In the accident analysis, typical design basis accident (DBA), including the load transient accident and depressurization accident into the system are selected and analyzed in detail. The predictions by GAMMA for PBMR at 100% power are compared with those by VSOP and PBR S IM. It turns out that the temperature in the upper region in the third channel predicted by GAMMA is about 62 .deg. C at maximum higher than that by VSOP, but is pretty close to that by PBR S IM. The center temperature of the fuel shows that that predicted by considering swelling effect is higher than that without swelling effect by about 10 .deg. C. The net efficiency of direct system is higher than that of indirect system due to an effect of the circulator power. The transient capability of GAMMA is validated through analytical solution and PBR S IM analyzing the depressurization (Loss Of Coolant Accident, LOCA) and load transient accident. After the LOCA the system pressure decreases dramatically from 8MPa to 0.4MPa within 2 sec. After the PI (Proportional-plus-Integral) controller senses that the power shaft is over the set-point of 3,600 rpm, the bypass valve makes shaft speed back to the set-point
International Nuclear Information System (INIS)
Buckner, M.R.; Hostetler, D.E.; Anderson, M.M.; Dodds, H.L.
1977-01-01
GRASS is a three-dimensional, coupled neutronic and engineering code for analysis of the radioisotope production reactors at the Savannah River Plant. The capabilities of GRASS are reviewed with emphasis on recent additions to model accident conditions involving the transport of molten fuel material and to accurately characterize neutronic and engineering feedback. The general application of GRASS to the Savannah River reactors is discussed, and results are presented for the analyses of severla reactor transient calculations
Current interruption transients calculation
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,
Nisa Khan, M
2017-09-20
We present measurement and analysis of color stability over time for two categories of white LED lamps based on their thermal management scheme, which also affects their transient lumen depreciation. We previously reported that lumen depreciation in LED lamps can be minimized by properly designing the heat sink configuration that allows lamps to reach a thermal equilibrium condition quickly. Although it is well known that lumen depreciation degrades color stability of white light since color coordinates vary with total lumen power by definition, quantification and characterization of color shifts based on thermal transient behavior have not been previously reported in literature for LED lamps. Here we provide experimental data and analysis of transient color shifts for two categories of household LED lamps (from a total of six lamps in two categories) and demonstrate that reaching thermal equilibrium more quickly provides better stability for color rendering, color temperature, and less deviation of color coordinates from the Planckian blackbody locus line, which are all very important characterization parameters of color for white light. We report for the first time that a lamp's color degradation from the turn-on time primarily depends on thermal transient behavior of the semiconductor LED chip, which experiences a wavelength shift as well as a decrease in its dominant wavelength peak value with time, which in turn degrades the phosphor conversion. For the first time, we also provide a comprehensive quantitative analysis that differentiates color degradation due to the heat rise in GaN/GaInN LED chips and subsequently the boards these chips are mounted on-from that caused by phosphor heating in a white LED module. Finally, we briefly discuss why there are some inevitable trade-offs between omnidirectionality and color and luminous output stability in current household LED lamps and what will help eliminate these trade-offs in future lamp designs.
Transient overexpression of the 5-HT1A receptor impairs water-maze but not hole-board performance.
Bert, B; Dere, E; Wilhelmi, N; Kusserow, H; Theuring, F; Huston, J P; Fink, H
2005-07-01
Previously, we showed that mice that overexpress the 5-HT(1A) receptor transiently from embryonic to perinatal stages show reduced anxiety and changes in brain serotonin turnover as adults. Here, we investigated the long-term effects of the temporary overexpression of the 5-HT(1A) receptor during early embryonic and perinatal development on the performance in two memory tasks. In the hole-board test mice that were homozygous for the transgene showed similar behavioral habituation but increased locomotion compared to heterozygous mice. In contrast water-maze performance of homozygous mice was impaired compared to heterozygous mice. These results suggest that a transient overexpression of 5-HT(1A) receptor during embryonic and perinatal development has detrimental effects on water-maze performance at adult stages.
Energy Technology Data Exchange (ETDEWEB)
Kot, C A; Youngdahl, C K
1978-09-01
PTAC was developed to predict pressure transients in nuclear-power-plant piping systems in which the possibility of cavitation must be considered. The program performs linear or nonlinear fluid-hammer calculations, using a fixed-grid method-of-characteristics solution procedure. In addition to pipe friction and elasticity, the program can treat a variety of flow components, pipe junctions, and boundary conditions, including arbitrary pressure sources and a sodium/water reaction. Essential features of transient cavitation are modeled by a modified column-separation technique. Comparisons of calculated results with available experimental data, for a simple piping arrangement, show good agreement and provide validation of the computational cavitation model. Calculations for a variety of piping networks, containing either liquid sodium or water, demonstrate the versatility of PTAC and clearly show that neglecting cavitation leads to erroneous predictions of pressure-time histories.
Directory of Open Access Journals (Sweden)
Jikai Chen
2016-12-01
Full Text Available In a power system, the analysis of transient signals is the theoretical basis of fault diagnosis and transient protection theory. Shannon wavelet entropy (SWE and Shannon wavelet packet entropy (SWPE are powerful mathematics tools for transient signal analysis. Combined with the recent achievements regarding SWE and SWPE, their applications are summarized in feature extraction of transient signals and transient fault recognition. For wavelet aliasing at adjacent scale of wavelet decomposition, the impact of wavelet aliasing is analyzed for feature extraction accuracy of SWE and SWPE, and their differences are compared. Meanwhile, the analyses mentioned are verified by partial discharge (PD feature extraction of power cable. Finally, some new ideas and further researches are proposed in the wavelet entropy mechanism, operation speed and how to overcome wavelet aliasing.
Sextant: an expert system for transient analysis of nuclear reactors and integral test facilities
International Nuclear Information System (INIS)
Barbet, N.; Dumas, M.; Mihelich, G.
1987-01-01
Expert systems provide a new way of dealing with the computer-aided management of nuclear plants by combining several knowledge bases and reasoning modes together with a set of numerical models for real-time analysis of transients. New development tools are required together with metaknowledge bases handling temporal hypothetical reasoning and planning. They have to be efficient and robust because during a transient, neither measurements nor models, nor scenarios are hold as absolute references. SEXTANT is a general purpose physical analyzer intended to provide a pattern and avoid duplication of general tools and knowledge bases for similar applications. It combines several knowledge bases concerning measurements, models and qualitative behavior of PWR with a mechanism of conjecture-refutation and a set of simplified models matching the current physical state. A prototype is under assessment by dealing with integral test facility transients. For its development, SEXTANT requires a powerful shell. SPIRAL is such a toolkit, oriented towards online analysis of complex processes and already used in several applications
Safety analysis on the operational transients and some accidents of MUTSU reactor
International Nuclear Information System (INIS)
Fujiki, Kazuo; Asaka, Hideaki
1981-03-01
The safety analyses on the operational transients and accidents of the MUTSU reactor have been described. The purposes of the analysis are: 1) to show the safety of the MUTSU reactor and 2) to provide the information of the methods of general transient analysis of LWR using RETRAN and other computer programs. This report gives analytical results on the following items of transients and accidents: (1) Partial loss of primary coolant flow (2) Loss of feedwater to steam generator (3) Excessive feedwater to steam generator (4) Blackout (5) Loss of primary coolant flow accident (6) Main coolant pump stick accident (7) Feedline pipe rupture accident (8) Steam generator U-tube rupture accident. The results shows the maximum pressure of primary system is 139.4 kg/cm 2 G (1997 psia) and minimum DNBR is 2.01, and the MUTSU-reactor has enough margin with respect to the safety limits. The useful informations on the modeling technique and analytical method are also obtained. (author)
Measurement and Analysis of Multiple Output Transient Propagation in BJT Analog Circuits
Roche, Nicolas J.-H.; Khachatrian, A.; Warner, J. H.; Buchner, S. P.; McMorrow, D.; Clymer, D. A.
2016-08-01
The propagation of Analog Single Event Transients (ASETs) to multiple outputs of Bipolar Junction Transistor (BJTs) Integrated Circuits (ICs) is reported for the first time. The results demonstrate that ASETs can appear at several outputs of a BJT amplifier or comparator as a result of a single ion or single laser pulse strike at a single physical location on the chip of a large-scale integrated BJT analog circuit. This is independent of interconnect cross-talk or charge-sharing effects. Laser experiments, together with SPICE simulations and analysis of the ASET's propagation in the s-domain are used to explain how multiple-output transients (MOTs) are generated and propagate in the device. This study demonstrates that both the charge collection associated with an ASET and the ASET's shape, commonly used to characterize the propagation of SETs in devices and systems, are unable to explain quantitatively how MOTs propagate through an integrated analog circuit. The analysis methodology adopted here involves combining the Fourier transform of the propagating signal and the current-source transfer function in the s-domain. This approach reveals the mechanisms involved in the transient signal propagation from its point of generation to one or more outputs without the signal following a continuous interconnect path.
Analysis of Transient Phenomena Due to a Direct Lightning Strike on a Wind Energy System
Directory of Open Access Journals (Sweden)
João P. S. Catalão
2012-07-01
Full Text Available This paper is concerned with the protection of wind energy systems against the direct effects of lightning. As wind power generation undergoes rapid growth, lightning damages involving wind turbines have come to be regarded as a serious problem. Nevertheless, very few studies exist yet in Portugal regarding lightning protection of wind energy systems using numerical codes. A new case study is presented in this paper, based on a wind turbine with an interconnecting transformer, for the analysis of transient phenomena due to a direct lightning strike to the blade. Comprehensive simulation results are provided by using models of the Restructured Version of the Electro-Magnetic Transients Program (EMTP, and conclusions are duly drawn.
MARVEL: a digital computer code for transient analysis of a multiloop PWR system
International Nuclear Information System (INIS)
Krise, R.C.; Miranda, S.
1977-11-01
The MARVEL (Multi-Loop Analysis of Pressurized Water Reactor System Transient) digital computer code was developed to calculate multiloop detailed transient behavior of pressurized water reactor systems. The program simulates two reactor coolant loops including two steam generators and associated systems. It also simulates reactor kinetics, reactor control and protection system, safeguards system, and other subsystems. The code can also be used for three- or four-loop plants by assuming that the other loops are operated in the same way as either of the two loops. The program can be utilized as a tool for various types of accident analyses and control studies, including startup of an inactive reactor coolant loop, loss of reactor coolant flow, reactivity insertion incidents, steam line break accident, steam generator tube rupture accident, and others
Fast reactor fuel failures and steam generator leaks: Transient and accident analysis approaches
International Nuclear Information System (INIS)
1996-10-01
This report consists of a survey of activities on transient and accident analysis for the LMFR. It is focused on the following subjects: Fuel transient tests and analyses in hypothetical incident/accident situations; sodium-water interaction in steam generators, and sodium fires: test and analyses. There are also sections dealing with the experimental and analytical studies of: fuel subassembly failures; sodium boiling, molten fuel-coolant interaction; molten material movement and relocation in fuel bundles; heat removal after an accident or incident; sodium-water reaction in steam generator; steam generator protection systems; sodium-water contact in steam generator building; fire-fighting methods and systems to deal with sodium fires. Refs, figs, tabs
RAP-2A Computer code for transients analysis in fast reactors
International Nuclear Information System (INIS)
Iftode, I.; Popescu, C.; Turcu, I.; Biro, L.
1975-10-01
The RAP-2A computer code is designed for analyzing thermohydraulic transients and/or steady state problems for large LMFBR cores. Physical and mathematical models, main input-output data, the flow chart of the code and a sample problem are given. RAP-2A calculates the power and the thermoydraulic transients initiated by a flow or reactivity changes, from a normal operating state of the reactor up to core disassembly. In this analysis a representative fuel pin is considered: a one-group space-independent (point) kinetics model to describe the neutron kinetics and a one-dimensional model describing the heat transfer (radial in the fuel and axial in the coolant) are used. Mechanical deformations due to temperature gradient, pressure losses, fuel melting, etc., are also calculated. The code is written in FORTRAN-4 language and is running on a IBM-370/135 computer
D'Isanto, A.; Cavuoti, S.; Brescia, M.; Donalek, C.; Longo, G.; Riccio, G.; Djorgovski, S. G.
2016-04-01
The exploitation of present and future synoptic (multiband and multi-epoch) surveys requires an extensive use of automatic methods for data processing and data interpretation. In this work, using data extracted from the Catalina Real Time Transient Survey (CRTS), we investigate the classification performance of some well tested methods: Random Forest, MultiLayer Perceptron with Quasi Newton Algorithm and K-Nearest Neighbours, paying special attention to the feature selection phase. In order to do so, several classification experiments were performed. Namely: identification of cataclysmic variables, separation between galactic and extragalactic objects and identification of supernovae.
Energy Technology Data Exchange (ETDEWEB)
Faydide, B. [Commissariat a l`Energie Atomique, Grenoble (France)
1997-07-01
This paper presents the current and planned numerical development for improving computing performance in case of Cathare applications needing real time, like simulator applications. Cathare is a thermalhydraulic code developed by CEA (DRN), IPSN, EDF and FRAMATOME for PWR safety analysis. First, the general characteristics of the code are presented, dealing with physical models, numerical topics, and validation strategy. Then, the current and planned applications of Cathare in the field of simulators are discussed. Some of these applications were made in the past, using a simplified and fast-running version of Cathare (Cathare-Simu); the status of the numerical improvements obtained with Cathare-Simu is presented. The planned developments concern mainly the Simulator Cathare Release (SCAR) project which deals with the use of the most recent version of Cathare inside simulators. In this frame, the numerical developments are related with the speed up of the calculation process, using parallel processing and improvement of code reliability on a large set of NPP transients.
International Nuclear Information System (INIS)
Bates, G.; Bodine, S.; Carroll, T.; Keller, M.
1984-02-01
This report begins with an overview of the Data Acquisition System (DAS), which supports several of PPPL's experimental devices. Performance measurements which were taken on DAS and the tools used to make them are then described
Baygi, Mahdi Oloumi; Ghazi, Reza; Monfared, Mohammad
2014-07-01
Applying the min-projection strategy (MPS) to a three-phase grid-connected inverter to improve its transient performance is the main objective of this paper. For this purpose, the inverter is first modeled as a switched linear system. Then, the feasibility of the MPS technique is investigated and the stability criterion is derived. Hereafter, the fundamental equations of the MPS for the control of the inverter are obtained. The proposed scheme is simulated in PSCAD/EMTDC environment. The validity of the MPS approach is confirmed by comparing the obtained results with those of VOC method. The results demonstrate that the proposed method despite its simplicity provides an excellent transient performance, fully decoupled control of active and reactive powers, acceptable THD level and a reasonable switching frequency. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
A High-Performance Portable Transient Electro-Magnetic Sensor for Unexploded Ordnance Detection.
Wang, Haofeng; Chen, Shudong; Zhang, Shuang; Yuan, Zhiwen; Zhang, Haiyang; Fang, Dong; Zhu, Jun
2017-11-17
Portable transient electromagnetic (TEM) systems can be well adapted to various terrains, including mountainous, woodland, and other complex terrains. They are widely used for the detection of unexploded ordnance (UXO). As the core component of the portable TEM system, the sensor is constructed with a transmitting coil and a receiving coil. Based on the primary field of the transmitting coil and internal noise of the receiving coil, the design and testing of such a sensor is described in detail. Results indicate that the primary field of the transmitting coil depends on the diameter, mass, and power of the coil. A higher mass-power product and a larger diameter causes a stronger primary field. Reducing the number of turns and increasing the clamp voltage reduces the switch-off time of the transmitting current effectively. Increasing the cross-section of the wire reduces the power consumption, but greatly increases the coil's weight. The study of the receiving coil shows that the internal noise of the sensor is dominated by the thermal noise of the damping resistor. Reducing the bandwidth of the system and increasing the size of the coil reduces the internal noise effectively. The cross-sectional area and the distance between the sections of the coil have little effect on the internal noise. A less damped state can effectively reduce signal distortion. Finally, a portable TEM sensor with both a transmitting coil (constructed with a diameter, number of turns, and transmitting current of 0.5 m, 30, and 5 A, respectively) and a receiving coil (constructed with a length and resonant frequency of 5.6 cm and 50 kHz, respectively) was built. The agreement between experimental and calculated results confirms the theory used in the sensor design. The responses of an 82 mm mortar shell at different distances were measured and inverted by the differential evolution (DE) algorithm to verify system performance. Results show that the sensor designed in this study can not only
A High-Performance Portable Transient Electro-Magnetic Sensor for Unexploded Ordnance Detection
Directory of Open Access Journals (Sweden)
Haofeng Wang
2017-11-01
Full Text Available Portable transient electromagnetic (TEM systems can be well adapted to various terrains, including mountainous, woodland, and other complex terrains. They are widely used for the detection of unexploded ordnance (UXO. As the core component of the portable TEM system, the sensor is constructed with a transmitting coil and a receiving coil. Based on the primary field of the transmitting coil and internal noise of the receiving coil, the design and testing of such a sensor is described in detail. Results indicate that the primary field of the transmitting coil depends on the diameter, mass, and power of the coil. A higher mass–power product and a larger diameter causes a stronger primary field. Reducing the number of turns and increasing the clamp voltage reduces the switch-off time of the transmitting current effectively. Increasing the cross-section of the wire reduces the power consumption, but greatly increases the coil’s weight. The study of the receiving coil shows that the internal noise of the sensor is dominated by the thermal noise of the damping resistor. Reducing the bandwidth of the system and increasing the size of the coil reduces the internal noise effectively. The cross-sectional area and the distance between the sections of the coil have little effect on the internal noise. A less damped state can effectively reduce signal distortion. Finally, a portable TEM sensor with both a transmitting coil (constructed with a diameter, number of turns, and transmitting current of 0.5 m, 30, and 5 A, respectively and a receiving coil (constructed with a length and resonant frequency of 5.6 cm and 50 kHz, respectively was built. The agreement between experimental and calculated results confirms the theory used in the sensor design. The responses of an 82 mm mortar shell at different distances were measured and inverted by the differential evolution (DE algorithm to verify system performance. Results show that the sensor designed in this
A High-Performance Portable Transient Electro-Magnetic Sensor for Unexploded Ordnance Detection
Wang, Haofeng; Chen, Shudong; Zhang, Shuang; Yuan, Zhiwen; Zhang, Haiyang; Fang, Dong; Zhu, Jun
2017-01-01
Portable transient electromagnetic (TEM) systems can be well adapted to various terrains, including mountainous, woodland, and other complex terrains. They are widely used for the detection of unexploded ordnance (UXO). As the core component of the portable TEM system, the sensor is constructed with a transmitting coil and a receiving coil. Based on the primary field of the transmitting coil and internal noise of the receiving coil, the design and testing of such a sensor is described in detail. Results indicate that the primary field of the transmitting coil depends on the diameter, mass, and power of the coil. A higher mass–power product and a larger diameter causes a stronger primary field. Reducing the number of turns and increasing the clamp voltage reduces the switch-off time of the transmitting current effectively. Increasing the cross-section of the wire reduces the power consumption, but greatly increases the coil’s weight. The study of the receiving coil shows that the internal noise of the sensor is dominated by the thermal noise of the damping resistor. Reducing the bandwidth of the system and increasing the size of the coil reduces the internal noise effectively. The cross-sectional area and the distance between the sections of the coil have little effect on the internal noise. A less damped state can effectively reduce signal distortion. Finally, a portable TEM sensor with both a transmitting coil (constructed with a diameter, number of turns, and transmitting current of 0.5 m, 30, and 5 A, respectively) and a receiving coil (constructed with a length and resonant frequency of 5.6 cm and 50 kHz, respectively) was built. The agreement between experimental and calculated results confirms the theory used in the sensor design. The responses of an 82 mm mortar shell at different distances were measured and inverted by the differential evolution (DE) algorithm to verify system performance. Results show that the sensor designed in this study can not only
Real-time Transient Monitoring With the HAWC Detector: Design and Performance
Wisher, Ian Gabriel
Blazars are some of the most energetic environments in the Universe with exceptionally strong non-thermal emission. Since the detection of VHE variability in the blazar Markarian 421, observations of blazars and their VHE variability have been an active field of research. Through long campaigns of observations, blazars have shown variability over timescales that vary from minutes to days across the electromagnetic spectrum from radio to TeV gamma rays. Though rare, the variability can also have extreme outburst events where the flux peaks at several orders of magnitude higher than the quiescent state of the source. These outbursts are interesting not only for constraining the models of acceleration and variability but also as tools to study other physics topics such as the extragalactic background light, intergalactic magnetic field, and Lorentz invariance. Though powerful, the rarity of these events makes studies challenging and motivates additional searches and detections. The High Altitude Water Cherenkov (HAWC) detector is an extensive air shower instrument with a high duty cycle, large field of view, and extraordinary sensitivity to TeV gamma rays. This allows HAWC to perform unbiased monitoring of a large number of different sources for flaring states and catch rare events such as the aforementioned blazar flares. This work presents a search for short timescale flares from known blazars and TeV sources for the first year of HAWC data with the capability to generate alerts in real time. In the course of this work, a variety of new hardware, software, and detection techniques were developed in conjunction with the construction of the HAWC detector. These include hardware development on the design of the main data acquisition system, electronics integrations and testing, design/testing of the online reconstruction system, and design of the electronics for the outrigger extension. Algorithms and methods to detect transients in HAWC time series data were developed
Transient thermal hydraulic modeling and analysis of ITER divertor plate system
International Nuclear Information System (INIS)
El-Morshedy, Salah El-Din; Hassanein, Ahmed
2009-01-01
A mathematical model has been developed/updated to simulate the steady state and transient thermal-hydraulics of the International Thermonuclear Experimental Reactor (ITER) divertor module. The model predicts the thermal response of the armour coating, divertor plate structural materials and coolant channels. The selected heat transfer correlations cover all operating conditions of ITER under both normal and off-normal situations. The model also accounts for the melting, vaporization, and solidification of the armour material. The developed model is to provide a quick benchmark of the HEIGHTS multidimensional comprehensive simulation package. The present model divides the coolant channels into a specified axial regions and the divertor plate into a specified radial zones, then a two-dimensional heat conduction calculation is created to predict the temperature distribution for both steady and transient states. The model is benchmarked against experimental data performed at Sandia National Laboratory for both bare and swirl tape coolant channel mockups. The results show very good agreements with the data for steady and transient states. The model is then used to predict the thermal behavior of the ITER plasma facing and structural materials due to plasma instability event where 60 MJ/m 2 plasma energy is deposited over 500 ms. The results for ITER divertor response is analyzed and compared with HEIGHTS results.
Transient thermal hydraulic modeling and analysis of ITER divertor plate system
Energy Technology Data Exchange (ETDEWEB)
El-Morshedy, Salah El-Din [Argonne National Laboratory, Argonne, IL (United States); Atomic Energy Authority, Cairo (Egypt)], E-mail: selmorshedy@etrr2-aea.org.eg; Hassanein, Ahmed [Purdue University, West Lafayette, IN (United States)], E-mail: hassanein@purdue.edu
2009-12-15
A mathematical model has been developed/updated to simulate the steady state and transient thermal-hydraulics of the International Thermonuclear Experimental Reactor (ITER) divertor module. The model predicts the thermal response of the armour coating, divertor plate structural materials and coolant channels. The selected heat transfer correlations cover all operating conditions of ITER under both normal and off-normal situations. The model also accounts for the melting, vaporization, and solidification of the armour material. The developed model is to provide a quick benchmark of the HEIGHTS multidimensional comprehensive simulation package. The present model divides the coolant channels into a specified axial regions and the divertor plate into a specified radial zones, then a two-dimensional heat conduction calculation is created to predict the temperature distribution for both steady and transient states. The model is benchmarked against experimental data performed at Sandia National Laboratory for both bare and swirl tape coolant channel mockups. The results show very good agreements with the data for steady and transient states. The model is then used to predict the thermal behavior of the ITER plasma facing and structural materials due to plasma instability event where 60 MJ/m{sup 2} plasma energy is deposited over 500 ms. The results for ITER divertor response is analyzed and compared with HEIGHTS results.
CEDNBR: a computer code for transient thermal margin analysis of a reactor core
International Nuclear Information System (INIS)
Shesler, A.T.; Lehmann, C.R.
1976-09-01
The report describes the CEDNBR computer code. This code was developed for the transient thermal analysis of a pressurized water reactor core or a critical heat flux test. Included are the code structure, conservation equations, and correlations utilized by CEDNBR. The methods of modelling a reactor core and hot channel and a CHF test are presented. Comparisons of CEDNBR calculations are made with both empirical pressure loss data and simulated loss of flow test data. The code solves the one-dimensional conservation of mass, energy, and momentum equations and the equation of state for the fluid for either steady-state or transient conditions. Tabular time dependent functions of inlet temperatures, pressure, mass velocity, axial heat flux distributions, normalized heat flux, radial peaking factors, and incremental mixing factors are required input to the code. Transient effects are included in the calculation of enthalpy rise and fluid properties. The Departure from Nucleate Boiling Ratio (DNBR) is calculated by applying a Critical Heat Flux (CHF) correlation to the computed local fluid properties. A code user's guide is provided for preparing input to the code. In addition, descriptions of the sub-routines used by CEDNBR are given
An efficient transient expression system for gene function analysis in rose.
Lu, Jun; Bai, Mengjuan; Ren, Haoran; Liu, Jinyi; Wang, Changquan
2017-01-01
Roses are widely used as garden ornamental plants and cut flowers. Rosa chinensis cv 'Old Blush' has been used as a model genotype in rose studies due to its contribution to recurrent flowering and tea scent traits of modern roses. The deficiency of efficient genetic transformation systems is a handicap limiting functional genetics studies of roses. Agrobacterium -mediated transient transformation offers a powerful tool for the characterization of gene function in plants. A convenient and highly efficient Agrobacterium mediated genetic transformation protocol using R. chinensis cv 'Old Blush' seedlings in vitro as an expression system is described in this paper. The most important factor affecting transformation efficiency in this system is seedling age; 3/4-week-old rose shoots with or without roots from sub-culturing are optimal for transformation, requiring no complicated inoculation media, supplements, or carefully tuned plant growth conditions. This transient expression system was successfully applied to analysis of the gene promoter activities, DNA binding capacity of transcription factors, protein-protein interaction in physiological contexts using luciferase as a reporter gene. This transient transformation system was validated as a robust and efficient platform, thus providing a new option for gene function and signaling pathway investigation in roses and further extending the utility of R. chinensis cv 'Old Blush' as a model plant to study diverse gene function and signaling pathways in Rosaceae.
WWER fuel rod analysis of KOLA3-MIR transient experiment using PAD and TRANSURANUS codes
International Nuclear Information System (INIS)
Slyeptsov, O.; Slyeptsov, S.; Sung, Y.
2013-01-01
The capability prediction of PAD (version 10.5.2) and TRANSURANUS (TU - v1m1j09) fuel rod models to simulate Russian WWER fuel rod behavior under the power transient conditions was estimated using the benchmark from the IFPE database for WWER refabricated fuel rods (RFRs) examined in different power ramp tests of reactor MIR, which are referred to as “FGR-1”, “FGR-2” and “RAMP”. The pre-transient calculations carried out for nine RFRs operated under conditions simulating the base irradiation in WWER-440 reactor demonstrated that the rod performances at burnups (BU) of ∼50 and 60 GWD/MTU predicted by both codes are in good agreement with the experimental data. The PAD and TU calculations of RFR dimensional changes (cladding outer diameter, pellet-to-cladding gap) after the ramp tests showed reasonable agreement with the measured ones. For RFRs irradiated in the “FGR-2” test, the behavior of fuel centerline temperatures (FCT) calculated by both codes are close to each other and the predicted FCTs correlate well with the measured ones for the rod BU of ∼50 GWD/MTU. The over- and underestimation of fission gas release (FGR) after the power transients calculated by PAD code are observed for RFRs from “FGR-2” and “FGR-1”/”RAMP” tests, respectively. For the current TU code version the FGR model parameters underestimate the FGR under the power transient conditions for the examined WWER RFRs. (authors)
Analysis of metal fuel transient overpower experiments with the SAS4A accident analysis code
International Nuclear Information System (INIS)
Tentner, A.M.; Kalimullah; Miles, K.J.
1990-01-01
The results of the SAS4A analysis of the M7 TREAT Metal fuel experiment are presented. New models incorporated in the metal fuel version of SAS4A are described. The computational results are compared with the experimental observations and this comparison is used in the interpretation of physical phenomena. This analysis was performed using the integrated metal fuel SAS4A version and covers a wide range of events, providing an increased degree of confidence in the SAS4A metal fuel accident analysis capabilities
LOFT transient thermal analysis for 10 inch primary coolant blowdown piping weld
International Nuclear Information System (INIS)
Howell, S.K.
1978-01-01
A flaw in a weld in the 10 inch primary coolant blowdown piping was discovered by LOFT personnel. As a result of this, a thermal analysis and fracture mechanics analysis was requested by LOFT personnel. The weld and pipe section were analyzed for a complete thermal cycle, heatup and Loss of Coolant Experiment (LOCE), using COUPLE/MOD2, a two-dimensional finite element heat conduction code. The finite element representation used in this analysis was generated by the Applied Mechanics Branch. The record of nodal temperatures for the entire transient was written on tape VSN=T9N054, and has been forwarded to the Applied Mechanics Branch for use in their mechanical analysis. Specific details and assumptions used in this analysis are found in appropriate sections of this report
DEFF Research Database (Denmark)
Ravn, Ole; Andersen, Nils Axel; Andersen, Thomas Timm
While working with the UR-10 robot arm, it has become apparent that some commands have undesired behaviour when operating the robot arm through a socket connection, sending one command at a time. This report is a collection of the results optained when testing the performance of the different...... commands available in URScript to control the robot. It will also describe the different time delays discovered when using the UR-10 robot arm...
Performance of fast reactor mixed-oxide fuels pins during extended overpower transients
International Nuclear Information System (INIS)
Tsai, H.; Neimark, L.A.; Asaga, T.; Shikakura, S.
1991-02-01
The Operational Reliability Testing (ORT) program, a collaborative effort between the US Department of Energy and the Power Reactor and Nuclear Fuel Development Corp. (PNC) of Japan, was initiated in 1982 to investigate the behavior of mixed-oxide fuel pin under various slow-ramp transient and duty-cycle conditions. In the first phase of the program, a series of four extended overpower transient tests, with severity sufficient to challenge the pin cladding integrity, was conducted. The objectives of the designated TOPI-1A through -1D tests were to establish the cladding breaching threshold and mechanisms, and investigate the thermal and mechanical effects of the transient on pin behavior. The tests were conducted in EBR-2, a normally steady-state reactor. The modes of transient operation in EBR-2 were described in a previous paper. Two ramp rates, 0.1%/s and 10%/s, were selected to provide a comparison of ramp-rate effects on fuel behavior. The test pins chosen for the series covered a range of design and pre-test irradiation parameters. In the first test (1A), all pins maintained their cladding integrity during the 0.1%/s ramp to 60% peak overpower. Fuel pins with aggressive designs, i.e., high fuel- smear density and/or thin cladding, were, therefore, included in the follow-up 1B and 1C tests to enhance the likelihood of achieving cladding breaching. In the meantime, a higher pin overpower capability, to greater than 100%, was established by increasing the reactor power limit from 62.5 to 75 MWt. In this paper, the significant results of the 1B and 1C tests are presented. 4 refs., 5 figs., 1 tab
DEFF Research Database (Denmark)
Wang, Haojie; Han, Minxiao; Guerrero, Josep M.
2017-01-01
The external droop control loop of I-V droop control is designed as a voltage loop with embedded virtual impedance, so the internal current loop plays a major role in the system bandwidth. Thus, in this paper, the influence of internal current loop on transient response performance of I-V droop...... controlled paralleled dc-dc converters is analyzed, which is guided and significant for its industry application. The model which is used for dynamic analysis is built, and the root locus method is used based on the model to analyze the dynamic response of the system by shifting different control parameters...
Two-dimensional transient thermal analysis of a fuel rod by finite volume method
Energy Technology Data Exchange (ETDEWEB)
Costa, Rhayanne Yalle Negreiros; Silva, Mário Augusto Bezerra da; Lira, Carlos Alberto de Oliveira, E-mail: ryncosta@gmail.com, E-mail: mabs500@gmail.com, E-mail: cabol@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamento de Energia Nuclear
2017-07-01
One of the greatest concerns when studying a nuclear reactor is the warranty of safe temperature limits all over the system at all time. The preservation of core structure along with the constraint of radioactive material into a controlled system are the main focus during the operation of a reactor. The purpose of this paper is to present the temperature distribution for a nominal channel of the AP1000 reactor developed by Westinghouse Co. during steady-state and transient operations. In the analysis, the system was subjected to normal operation conditions and then to blockages of the coolant flow. The time necessary to achieve a new safe stationary stage (when it was possible) was presented. The methodology applied in this analysis was based on a two-dimensional survey accomplished by the application of Finite Volume Method (FVM). A steady solution is obtained and compared with an analytical analysis that disregard axial heat transport to determine its relevance. The results show the importance of axial heat transport consideration in this type of study. A transient analysis shows the behavior of the system when submitted to coolant blockage at channel's entrance. Three blockages were simulated (10%, 20% and 30%) and the results show that, for a nominal channel, the system can still be considerate safe (there's no bubble formation until that point). (author)
SAFE: A computer code for the steady-state and transient thermal analysis of LMR fuel elements
International Nuclear Information System (INIS)
Hayes, S.L.
1993-12-01
SAFE is a computer code developed for both the steady-state and transient thermal analysis of single LMR fuel elements. The code employs a two-dimensional control-volume based finite difference methodology with fully implicit time marching to calculate the temperatures throughout a fuel element and its associated coolant channel for both the steady-state and transient events. The code makes no structural calculations or predictions whatsoever. It does, however, accept as input structural parameters within the fuel such as the distributions of porosity and fuel composition, as well as heat generation, to allow a thermal analysis to be performed on a user-specified fuel structure. The code was developed with ease of use in mind. An interactive input file generator and material property correlations internal to the code are available to expedite analyses using SAFE. This report serves as a complete design description of the code as well as a user's manual. A sample calculation made with SAFE is included to highlight some of the code's features. Complete input and output files for the sample problem are provided
Choi, M H; Park, C H; Kim, S W; Hahn, S H; Seong, D J; Kim, J C
1999-01-01
The thermal diffusivity in a direction perpendicular to an epoxy resin film sandwiched between two identical metal layers was measured not only by using a pulsed transient analysis but also by using AC calorimetry. The pulsed transient analysis utilized the surface-temperature decay of the heating pulse from a Q-switched, 2nd harmonic generated Nd:YAG laser. The temperature decay was measured with a HgCdTe infrared detector. After data collection, a nonlinear least-squares regression was performed to estimate the optimal values of several separate thermal parameters by fitting the data to the solutions. Additionally, the thermal diffusivity of the samples was obtained by using the AC calorimetric method which measured the frequency-dependent phase changes of the samples. The thermal diffusivities obtained by the two methods were in the range of 0.07 approx 0.09 x 10 sup - sup 2 cm sup 2 /s, agreed within 8 %, but were lower than the literature values. To improve the results, the contact heat resistance from t...
International Nuclear Information System (INIS)
Gilli, L.; Lathouwers, D.; Kloosterman, J.L.; Van der Hagen, T.H.J.J.
2011-01-01
In this paper a method to perform sensitivity analysis for a simplified multi-physics problem is presented. The method is based on the Adjoint Sensitivity Analysis Procedure which is used to apply first order perturbation theory to linear and nonlinear problems using adjoint techniques. The multi-physics problem considered includes a neutronic, a thermo-kinetics, and a thermal-hydraulics part and it is used to model the time dependent behavior of a sodium cooled fast reactor. The adjoint procedure is applied to calculate the sensitivity coefficients with respect to the kinetic parameters of the problem for two reference transients using two different model responses, the results obtained are then compared with the values given by a direct sampling of the forward nonlinear problem. Our first results show that, thanks to modern numerical techniques, the procedure is relatively easy to implement and provides good estimation for most perturbations, making the method appealing for more detailed problems. (author)
Fracture mechanical analysis of relevant transients in the pressure vessel of Atucha I reactor
International Nuclear Information System (INIS)
Saavedra, Fernando M.
2001-01-01
The evolution of the applied stress intensity factor K I for 10 relevant transients of the nuclear power station Atucha I obtained from thermohydraulic data is analyzed according to the methodology proposed in Section XI of ASME Boiler and Pressure Vessel Code. Vast knowledge was thus obtained about basic concepts of fracture mechanics and its application to remanent life of nuclear components. Basic knowledge which commands the performance of nuclear power stations was also obtained, especially that related to the Atucha I utility [es
Transient Thermal Testing and Analysis of a Thermally Insulating Structural Sandwich Panel
Blosser, Max L.; Daryabeigi, Kamran; Bird, Richard K.; Knutson, Jeffrey R.
2015-01-01
A core configuration was devised for a thermally insulating structural sandwich panel. Two titanium prototype panels were constructed to illustrate the proposed sandwich panel geometry. The core of one of the titanium panels was filled with Saffil(trademark) alumina fibrous insulation and the panel was tested in a series of transient thermal tests. Finite element analysis was used to predict the thermal response of the panel using one- and two-dimensional models. Excellent agreement was obtained between predicted and measured temperature histories.
Application of transient ignition model to multi-canister (MCO) accident analysis
International Nuclear Information System (INIS)
Kummerer, M.
1996-01-01
The potential for ignition of spent nuclear fuel in a Multi-Canister Overpack (MCO) is examined. A transient model is applied to calculate the highest ambient gas temperature outside an MCO wall tube or shipping cask for which a stable temperature condition exists. This integral analysis couples reaction kinetics with a description of the MCO configuration, heat and mass transfer, and fission product phenomena. It thereby allows ignition theory to be applied to various complex scenarios, including MCO water loss accidents and dry MCO air ingression
Development and Transient Analysis of a Helical-coil Steam Generator for High Temperature Reactors
International Nuclear Information System (INIS)
Hoffer, Nathan V.; Anderson, Nolan A.; Sabharwall, Piyush
2011-01-01
A high temperature gas-cooled reactor (HTGR) is under development by the Next Generation Nuclear Plant (NGNP) Project at the Idaho National Laboratory (INL). Its design emphasizes electrical power production which may potentially be coupled with process heat for hydrogen production and other industrial applications. NGNP is considering a helical-coil steam generator for the primary heat transport loop heat exchanger based on its increased heat transfer and compactness when compared to other steam generators. The safety and reliability of the helical-coil steam generator is currently under evaluation as part of the development of NGNP. Transients, such as loss of coolant accidents (LOCA), are of interest in evaluating the safety of steam generators. In this study, a complete steam generator inlet pipe break (double ended pipe break) LOCA was simulated by an exponential loss of primary side pressure. For this analysis, a model of the helical-coil steam generator was developed using RELAP5-3D, an INL inhouse systems analysis code. The steam generator model behaved normally during the transient simulating the complete steam generator inlet pipe break LOCA. Further analysis is required to comprehensively evaluate the safety and reliability of the helical-coil steam generator design in the NGNP setting.
International Nuclear Information System (INIS)
Di Maio, Francesco; Vagnoli, Matteo; Zio, Enrico
2016-01-01
Highlights: • We develop an Integrated Deterministic and Probabilistic Safety Analysis (IDPSA). • We present a transient identification approach for retrieving IDPSA scenarios information. • We post-process the IDPSA scenarios for clustering Prime Implicants and Near Misses. • The approach is useful for an on-line cluster assignment of an unknown developing scenario. • We apply the approach to the accidental scenarios of a dynamic Steam Generator of a NPP. - Abstract: In this work, we present a transient identification approach that utilizes clustering for retrieving scenarios information from an Integrated Deterministic and Probabilistic Safety Analysis (IDPSA). The approach requires: (i) creation of a database of scenarios by IDPSA; (ii) scenario post-processing for clustering Prime Implicants (PIs), i.e., minimum combinations of failure events that are capable of leading the system into a fault state, and Near Misses, i.e., combinations of failure events that lead the system to a quasi-fault state; (iii) on-line cluster assignment of an unknown developing scenario. In the step (ii), we adopt a visual interactive method and risk-based clustering to identify PIs and Near Misses, respectively; in the on-line step (iii), to assign a scenario to a cluster we consider the sequence of events in the scenario and evaluate the Hamming similarity to the sequences of the previously clustered scenarios. The feasibility of the analysis is shown with respect to the accidental scenarios of a dynamic Steam Generator (SG) of a NPP.
Agius, Fernanda; Amaya, Iraida; Botella, Miguel A; Valpuesta, Victoriano
2005-01-01
The isolation and characterization of fruit-specific promoters are critical for the manipulation of the nutritional value and quality of fruits by genetic engineering. The analysis of regulatory sequences of many ripening-related genes has remained elusive for many species due to their low transformation efficiency and/or lengthy regeneration of a small number of transgenic plants. Strawberry is an important crop and represents one of the most widely studied non-climacteric model systems. However, until recently, its difficult regeneration has limited the functional study of promoters by stable transformation. A protocol based on biolistic transient transformation has been developed in order to study the function of promoters in a fast and efficient manner in strawberry fruits. The protocol has been applied to the study of the GalUR promoter, a gene involved in the biosynthesis of vitamin C in this fruit. The activity of the GalUR promoter is restricted to the fruit, being strictly dependent on light. The analysis of deletion series revealed the presence of a minimum activation region 397 bp upstream of the gene with a putative G-box motif, and a negative regulatory region between -397 and -518 bp, where an I-box was identified. The transient assay has been used to study the activity of the tomato polygalacturonase and the pepper fibrillin promoters in strawberry fruits. Whereas slight activity was observed with the fibrillin promoter, no significant activity was found with the polygalacturonase promoter. The GalUR promoter in transiently transformed ripe tomato fruits showed no activity, indicating the presence of regulatory sequences specific for its function in strawberry fruit.
International Nuclear Information System (INIS)
Krätschmer, D.; Roos, E.; Schuler, X.; Herter, K.-H.
2012-01-01
For the construction, design and operation of nuclear components and systems the appropriate technical codes and standards provide detailed analysis procedures which guarantee a reliable behaviour of the structural components throughout the specified lifetime. Especially for cyclic stress evaluation the different codes and standards provide different fatigue analyses procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. To consider effects of light water reactor coolant environments, new design curves included in report NUREG/CR-6909 for austenitic stainless steels and for low alloy steels have been presented. For the usage of these new design curves an environmental fatigue correction factor for incorporating environmental effects has to be calculated and used. The application of this environmental correction factor to a fatigue analysis of a nozzle with transient stratification loads, derived by in-service monitoring, has been performed. The results are used to compare with calculated usage factors, based on design curves without taking environmental effects particularly into account. - Highlights: ► We model an nozzle for fatigue analysis und mechanical and thermal loading conditions. ► A simplified as well as a general elastic–plastic fatigue analysis considering environmental effects is performed. ► The influence of different factors calculating the environmental factor F en are shown. ► The presented numerical evaluation methodology allows the consideration of all relevant parameters to assess lifetime.
MPQC: Performance Analysis and Optimization
Energy Technology Data Exchange (ETDEWEB)
Sarje, Abhinav [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Williams, Samuel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bailey, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2013-01-24
MPQC (Massively Parallel Quantum Chemistry) is a widely used computational quantum chemistry code. It is capable of performing a number of computations commonly occurring in quantum chemistry. In order to achieve better performance of MPQC, in this report we present a detailed performance analysis of this code. We then perform loop and memory access optimizations, and measure performance improvements by comparing the performance of the optimized code with that of the original MPQC code. We observe that the optimized MPQC code achieves a significant improvement in the performance through a better utilization of vector processing and memory hierarchies.
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.
International Nuclear Information System (INIS)
Magalhaes, Mardson Alencar de Sa; Lira, Carlos Alberto Brayner de Oliveira; Silva, Mario Augusto Bezerra da
2011-01-01
The IRIS project has significantly advanced in the last few years in response to a demand for a new generation reactor, that could fulfill the essential requirements for a future nuclear power plant: better economics, safety-by-design, low proliferation risk and environmental sustainability. IRIS reactor is a integral type PWR in which all primary components are arranged inside the pressure vessel. This configuration involves important changes in relation to a conventional PWR. These changes require several studies to comply with the safe operational limits for the reactor. In this paper, a study has been conducted to develop a dynamic model (named MODIRIS) for transient analysis, implemented in the MATLAB'S software SIMULINK, allowing the analysis of IRIS behavior by considering the neutron point kinetics for power production. The methodology is based on generating a set of differential equations of neutronic and thermal-hydraulic balances which describes the dynamics of the primary circuit, as well as a set of differential equations describing the dynamics of secondary circuit. The equations and initialization parameters at full power were into the SIMULINK and the code was validated by the confrontation with RELAP simulations for a transient of feedwater reduction in the steam generators. (author)
International Nuclear Information System (INIS)
Annor-Nyarko, M.; Ayensu Gyeabour, I.; Akaho, E. H. K.
2013-01-01
Lumped thermal capacitance analysis has been undertaken to investigate the transient temperature variations, associated induced thermal stress distributions, and the structural integrity of Ghana Research Reactor-I (GHAR R-I) vessel after 15 years of operation. The beltline configuration of the cylindrical vessel of the Miniature Neutron Source Reactor (MNSR) was based on thin-shell and axi-symmetric assumptions with small temperature gradient and low Biot number. The thermal energy transferred by unsteady flow of the coolant to the vessel was determined as internal energy change. Numerical algorithms for Matlab Code were implemented to generate data for transient analysis and simulation. The simulations indicated that the temperature variations and the thermal stresses were below the limits imposed by the vessel material (Aluminium alloy LT 21) specifications of 933 K melting point and allowable yield stress of 480 MPa. The low level of induced thermal stresses indicated that the structural integrity of the reactor vessel has been maintained to forestall any incidence of crack propagation and fatigue failure over the operation period. (au)
Ivanović, Vladimir; Deur, Joško; Kostelac, Milan; Pentek, Tibor; Hrovat, Davor
2011-10-01
The paper shows that, during abrupt wheel torque transients for ice surface and low vehicle speeds, the tyre can develop significantly larger longitudinal force than the peak value of the tyre static curve. This so-called dynamic tyre friction potential (DTFP) effect has many influencing factors such as the rate of change of the wheel torque, the vehicle speed, and the tyre dwell time. The paper presents a detailed analysis of the DTFP behaviour based on the experimental data collected by using an in-wheel motor-based tyre test vehicle. The analysis results and an insight into the brush structure of a tyre model lead to the hypothesis that the different influencing factors may be predominantly explained by the bristle dwell time (BDT) effect. Following this hypothesis, the LuGre model of the tyre friction dynamics is extended with a physical BDT sub-model. The experimental validation results show that the proposed model can accurately capture the low-speed tyre-ice friction behaviour during abrupt wheel torque transients.
PASP Plus Transient Pulse Monitor (TPM) - Data Analysis and Interpretation Report
National Research Council Canada - National Science Library
Adamo, Richard
1996-01-01
The Transient Pulse Monitor (TPM), part of the PASP Plus experiment aboard the APEX spacecraft, is designed to detect and characterize electromagnetic transient signals produced by electrostatic discharges on the solar array test modules...
Directory of Open Access Journals (Sweden)
Youwei He
2018-02-01
Full Text Available Although technical advances in hydraulically fracturing and drilling enable commercial production from tight reservoirs, oil/gas recovery remains at a low level. Due to the technical and economic limitations of well-testing operations in tight reservoirs, rate-transient analysis (RTA has become a more attractive option. However, current RTA models hardly consider the effect of the non-uniform production on rate decline behaviors. In fact, PLT results demonstrate that production profile is non-uniform. To fill this gap, this paper presents an improved RTA model of multi-fractured horizontal wells (MFHWs to investigate the effects of non-uniform properties of hydraulic fractures (production of fractures, fracture half-length, number of fractures, fracture conductivity, and vertical permeability on rate transient behaviors through the diagnostic type curves. Results indicate obvious differences on the rate decline curves among the type curves of uniform properties of fractures (UPF and non-uniform properties of fractures (NPF. The use of dimensionless production integral derivative curve magnifies the differences so that we can diagnose the phenomenon of non-uniform production. Therefore, it’s significant to incorporate the effects of NPF into the RDA models of MFHWs, and the model proposed in this paper enables us to better evaluate well performance based on long-term production data.
Transient Three-Dimensional Side Load Analysis of Out-of-Round Film Cooled Nozzles
Wang, Ten-See; Lin, Jeff; Ruf, Joe; Guidos, Mike
2010-01-01
The objective of this study is to investigate the effect of nozzle out-of-roundness on the transient startup side loads at a high altitude, with an anchored computational methodology. The out-of-roundness could be the result of asymmetric loads induced by hardware attached to the nozzle, asymmetric internal stresses induced by previous tests, and deformation, such as creep, from previous tests. The rocket engine studied encompasses a regeneratively cooled thrust chamber and a film cooled nozzle extension with film coolant distributed from a turbine exhaust manifold. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet history based on an engine system simulation. Transient startup computations were performed with the out-of-roundness achieved by four different degrees of ovalization: one perfectly round, one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation-line-jump is the peak side load physics for the round, slightly our-of-round, and more out-of-round cases, and the peak side load increases as the degree of out-of-roundness increases. For the significantly out-of-round nozzle, however, the peak side load reduces to comparable to that of the round nozzle and the separation line jump is not the peak side load physics. The counter-intuitive result of the significantly out-of-round case is found to be related to a side force reduction mechanism that splits the effect of the separation-line-jump into two parts, not only in the circumferential direction and most importantly in time.
Transient Side Load Analysis of Out-of-Round Film-Cooled Nozzle Extensions
Wang, Ten-See; Lin, Jeff; Ruf, Joe; Guidos, Mike
2012-01-01
There was interest in understanding the impact of out-of-round nozzle extension on the nozzle side load during transient startup operations. The out-of-round nozzle extension could be the result of asymmetric internal stresses, deformation induced by previous tests, and asymmetric loads induced by hardware attached to the nozzle. The objective of this study was therefore to computationally investigate the effect of out-of-round nozzle extension on the nozzle side loads during an engine startup transient. The rocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film cooled nozzle extension. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and transient inlet boundary flow properties derived from an engine system simulation. Six three-dimensional cases were performed with the out-of-roundness achieved by three different degrees of ovalization, elongated on lateral y and z axes: one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation line jump was the primary source of the peak side loads. Comparing to the peak side load of the perfectly round nozzle, the peak side loads increased for the slightly and more ovalized nozzle extensions, and either increased or decreased for the two significantly ovalized nozzle extensions. A theory based on the counteraction of the flow destabilizing effect of an exacerbated asymmetrical flow caused by a lower degree of ovalization, and the flow stabilizing effect of a more symmetrical flow, created also by ovalization, is presented to explain the observations obtained in this effort.
Directory of Open Access Journals (Sweden)
Mohammed Hussein
2007-01-01
Full Text Available The transient response of erodable surface thermocouples has been numerically assessed by using a two dimensional finite element analysis. Four types of base metal erodable surface thermocouples have been examined in this study, included type-K (alumel-chromel, type-E (chromel-constantan, type-T (copper-constantan, and type-J (iron-constantan with 50 mm thick- ness for each. The practical importance of these types of thermocouples is to be used in internal combustion engine studies and aerodynamics experiments. The step heat flux was applied at the surface of the thermocouple model. The heat flux from the measurements of the surface temperature can be commonly identified by assuming that the heat transfer within these devices is one-dimensional. The surface temperature histories at different positions along the thermocouple are presented. The normalized surface temperature histories at the center of the thermocouple for different types at different response time are also depicted. The thermocouple response to different heat flux variations were considered by using a square heat flux with 2 ms width, a sinusoidal surface heat flux variation width 10 ms period and repeated heat flux variation with 2 ms width. The present results demonstrate that the two dimensional transient heat conduction effects have a significant influence on the surface temperature history measurements made with these devices. It was observed that the surface temperature history and the transient response for thermocouple type-E are higher than that for other types due to the thermal properties of this thermocouple. It was concluded that the thermal properties of the surrounding material do have an impact, but the properties of the thermocouple and the insulation materials also make an important contribution to the net response.
International Nuclear Information System (INIS)
Wareing, T.A.
1988-02-01
Two potential undercooling transients are of concern in the design of TIBER-II (Tokamak Ignition/Burn Experimental Reactor), namely loss of coolant and loss of flow accidents. The major area of concern for TIBER-II is the inboard shield, where, due to tungsten material, the decay heat is extremely high. The purpose of this study was to analyze these transients using the thermal-hydraulic code ATHENA (Advanced Thermal-Hydraulic Energy Network Analyzer). The most comprehensive portion of this project involved creating a simple, yet complete, ATHENA model representative of TIBER-II. The completed model represents the case when the plasma is off and contains the inboard shield, the outboard shield, the divertor shields, and the primary loop. The primary loop contains the piping, pump, pressurizer, and heat exchanger. The heat exchanger is at the same elevation as the reactor, the least favorable to establishing natural circulation. The only transient analyzed so far, however, is a loss of flow accident. Results from the loss of flow analysis show that there is sufficient natural circulation in the inboard, outboard, and lower divertor shield to remove the decay heat, assuming that the secondary side flow is at full capacity. Although the upper divertor shield does not have sufficient natural circulation, cooling is provided due to vaporization and re-flood oscillations. However, one must recognize that there may be some local hot sport where the flow geometry inhibits cooling in a LOFA; the ATHENA model would not detect any localized problem. 9 refs., 18 figs., 4 tabs
TRAC analysis of steam-generator overfill transients for TMI-1
International Nuclear Information System (INIS)
Bassett, B.
1983-01-01
A reactor safety issue concerning the overfilling of once-through steam generators leading to combined primary/secondary blowdown has been raised recently. A series of six calculations, performed with the LWR best-estimate code, TRAC-PD2, on a Babcock and Wilcox Plant (TMI-1), was performed to investigate this safety issue. The base calculation assumed runaway main feedwater to one steam generator causing it to overfill and to break the main steam line. Four additional calculations build onto the base case with combinations of a pump-seal failure, a steam-generator tube rupture, and the pilot-operated relief valve not reseating. A sixth calculation involved only the rupture of a single steam-generator tube. The results of these analyses indicate that for the transients investigated, the emergency cooling system provided an adequate make-up coolant flow to mitigate the accidents
International Nuclear Information System (INIS)
Lim, Hong Sik; No, Hee Cheon
2003-01-01
The transient multicomponent mixture analysis tool has been developed to analyze molecular diffusion, natural convection and chemical reactions related to air ingress phenomena during the primary-pipe rupture accident of a High Temperature Gas Cooled Reactor. The present tool solves the one-dimensional basic equations for continuity, momentum, energy of the gas mixture, and mass of each species. In order to get stable and fast computation, the Implicit Continuous Eulerian scheme is adopted to solve the governing equations in a strongly coupled manner. Two kinds of benchmark calculations with Japanese inverse U-tube experiments have been performed. The present method based on the ICE technique runs faster by about 36 times for the simulation of the two experiments than the FLUENT5 does. The calculation results agree well within 10% deviations with the experimental data regarding the concentrations of gas species and the onset time of the natural circulation
Transient Analysis of Grid-Connected Wind Turbines with DFIG After an External Short-Circuit Fault
DEFF Research Database (Denmark)
Sun, Tao; Chen, Zhe; Blaabjerg, Frede
2004-01-01
The fast development of wind power generation brings new requirements for wind turbine integration to the network. After the clearance of an external short-circuit fault, the grid-connected wind turbine should restore its normal operation with minimized power losses. This paper concentrates...... on transient analysis of variable speed wind turbines with doubly fed induction generator (DFIG) after an external short-circuit fault. A simulation model of a MW-level variable speed wind turbine with DFIG developed in PSCAD/EMTDC is presented, and the control and protection schemes are described in detail....... After the clearance of an external short-circuit fault the control schemes manage to restore the wind turbine?s normal operation, and their performances are demonstrated by simulation results both during the fault and after the clearance of the fault....
Vasung, Lana; Lepage, Claude; Radoš, Milan; Pletikos, Mihovil; Goldman, Jennifer S.; Richiardi, Jonas; Raguž, Marina; Fischi-Gómez, Elda; Karama, Sherif; Huppi, Petra S.; Evans, Alan C.; Kostovic, Ivica
2016-01-01
The cerebral wall of the human fetal brain is composed of transient cellular compartments, which show characteristic spatiotemporal relationships with intensity of major neurogenic events (cell proliferation, migration, axonal growth, dendritic differentiation, synaptogenesis, cell death, and myelination). The aim of the present study was to obtain new quantitative data describing volume, surface area, and thickness of transient compartments in the human fetal cerebrum. Forty-four postmortem fetal brains aged 13–40 postconceptional weeks (PCW) were included in this study. High-resolution T1 weighted MR images were acquired on 19 fetal brain hemispheres. MR images were processed using in-house software (MNI-ACE toolbox). Delineation of fetal compartments was performed semi-automatically by co-registration of MRI with histological sections of the same brains, or with the age-matched brains from Zagreb Neuroembryological Collection. Growth trajectories of transient fetal compartments were reconstructed. The composition of telencephalic wall was quantitatively assessed. Between 13 and 25 PCW, when the intensity of neuronal proliferation decreases drastically, the relative volume of proliferative (ventricular and subventricular) compartments showed pronounced decline. In contrast, synapse- and extracellular matrix-rich subplate compartment continued to grow during the first two trimesters, occupying up to 45% of telencephalon and reaching its maximum volume and thickness around 30 PCW. This developmental maximum coincides with a period of intensive growth of long cortico-cortical fibers, which enter and wait in subplate before approaching the cortical plate. Although we did not find significant age related changes in mean thickness of the cortical plate, the volume, gyrification index, and surface area of the cortical plate continued to exponentially grow during the last phases of prenatal development. This cortical expansion coincides developmentally with the
Nhu Y, Do
2018-03-01
Vietnam has many advantages of wind power resources. Time by time there are more and more capacity as well as number of wind power project in Vietnam. Corresponding to the increase of wind power emitted into national grid, It is necessary to research and analyze in order to ensure the safety and reliability of win power connection. In national distribution grid, voltage sag occurs regularly, it can strongly influence on the operation of wind power. The most serious consequence is the disconnection. The paper presents the analysis of distribution grid's transient process when voltage is sagged. Base on the analysis, the solutions will be recommended to improve the reliability and effective operation of wind power resources.
Directory of Open Access Journals (Sweden)
Oramus Piotr
2015-09-01
Full Text Available Electric arc is a complex phenomenon occurring during the current interruption process in the power system. Therefore performing digital simulations is often necessary to analyse transient conditions in power system during switching operations. This paper deals with the electric arc modelling and its implementation in simulation software for transient analyses during switching conditions in power system. Cassie, Cassie-Mayr as well as Schwarz-Avdonin equations describing the behaviour of the electric arc during the current interruption process have been implemented in EMTP-ATP simulation software and presented in this paper. The models developed have been used for transient simulations to analyse impact of the particular model and its parameters on Transient Recovery Voltage in different switching scenarios: during shunt reactor switching-off as well as during capacitor bank current switching-off. The selected simulation cases represent typical practical scenarios for inductive and capacitive currents breaking, respectively.
Energy Technology Data Exchange (ETDEWEB)
Fraley, D.W.; Chockie, A.D.; Levy, M.; Kofoed, R.J.
1979-06-01
This document presents an analysis of alternatives under consideration by the US Nuclear Regulatory Commission for the protection of transient shipments of Strategic Special Nuclear Material (SSNM). (A transient shipment is a shipment of SSNM from one foreign country to another which makes a stopover in US territory). The objective of this study was to assess the values and impacts of NRC designated alternatives. Criteria were developed for the evaluation which are based on the NRC's objective of providing physical protection for transient shipments at a level equivalent to that afforded domestic shipments of SSNM. The results of the assessment are intended to provide support to the NRC in their selection of a preferred approach for the protection of transient shipments.
An analysis of transient thermal properties for high power GaN-based laser diodes
Energy Technology Data Exchange (ETDEWEB)
Kim, Jae Min; Kim, Seungtaek; Kang, Sung Bok; Kim, Young Jin; Jeong, Hoon; Lee, Kyeongkyun; Kim, Jongseok [Korea Institute of Industrial Technology, 35-3 Hongcheon-Ri, Ipjang-Myeon, Cheonan, Chungnam 331-825 (Korea); Lee, Sangdon; Suh, Dongsik [QSI Co., Ltd., 315-9 Cheonheung-Ri, Sungger-Eup, Cheonan, Chungnam 330-836 (Korea); Yi, Jeong Hoon; Choi, Yoonho; Jung, Seok Gu; Noh, Minsoo [LG Electronics Advanced Research Institute, 16 Woomyeon-Dong, Seocho-Gu, Seoul 137-724 (Korea)
2010-07-15
Thermal properties of 405 nm GaN-based laser diodes were investigated by employing a transient heating response method based on the temperature dependence of diode forward voltage. Thermal resistances of materials consisting of packaged laser diodes were differentiated in transient thermal response curves at a current below threshold current. With a current above threshold current, no significant change in thermal resistances and difference between junction-up and junction-down laser diodes was observed at pulses shorter than 3 sec. From an analysis with long current injections, thermal resistance of a packaged laser diode with a junction-up bonding was {proportional_to}45 C/W which was higher than that of a junction-down bonded laser diode by {proportional_to}10 C/W. Further analyses based on parameters obtained from voltage recovery curves indicated that the time constant for cooling is directly related to the thermal resistance and thermal capacitance of a laser diode package. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Design base transient analysis using the real-time nuclear reactor simulator model
International Nuclear Information System (INIS)
Tien, K.K.; Yakura, S.J.; Morin, J.P.; Gregory, M.V.
1987-01-01
A real-time simulation model has been developed to describe the dynamic response of all major systems in a nuclear process reactor. The model consists of a detailed representation of all hydraulic components in the external coolant circulating loops consisting of piping, valves, pumps and heat exchangers. The reactor core is described by a three-dimensional neutron kinetics model with detailed representation of assembly coolant and moderator thermal hydraulics. The models have been developed to support a real-time training simulator, therefore, they reproduce system parameters characteristic of steady state normal operation with high precision. The system responses for postulated severe transients such as large pipe breaks, loss of pumping power, piping leaks, malfunctions in control rod insertion, and emergency injection of neutron absorber are calculated to be in good agreement with reference safety analyses. Restrictions were imposed by the requirement that the resulting code be able to run in real-time with sufficient spare time to allow interfacing with secondary systems and simulator hardware. Due to hardware set-up and real plant instrumentation, simplifications due to symmetry were not allowed. The resulting code represents a coarse-node engineering model in which the level of detail has been tailored to the available computing power of a present generation super-minicomputer. Results for several significant transients, as calculated by the real-time model, are compared both to actual plant data and to results generated by fine-mesh analysis codes
Lin, Jieqiong; Guan, Liang; Lu, Mingming; Han, Jinguo; Kan, Yudi
2017-12-01
In traditional diamond cutting, the cutting force is usually large and it will affect tool life and machining quality. Elliptical vibration cutting (EVC) as one of the ultra-precision machining technologies has a lot of advantages, such as reduces cutting force, extend tool life and so on. It's difficult to predict the transient cutting force of EVC due to its unique elliptical motion trajectory. Study on chip formation will helpfully to predict cutting force. The geometric feature of chip has important effects on cutting force, however, few scholars have studied the chip formation. In order to investigate the time-varying cutting force of EVC, the geometric feature model of chip is established based on analysis of chip formation, and the effects of cutting parameters on the geometric feature of chip are analyzed. To predict transient force quickly and effectively, the geometric feature of chip is introduced into the cutting force model. The calculated results show that the error between the predicted cutting force in this paper and that in the literature is less than 2%, which proves its feasibility.
Directory of Open Access Journals (Sweden)
Jieqiong Lin
2017-12-01
Full Text Available In traditional diamond cutting, the cutting force is usually large and it will affect tool life and machining quality. Elliptical vibration cutting (EVC as one of the ultra-precision machining technologies has a lot of advantages, such as reduces cutting force, extend tool life and so on. It’s difficult to predict the transient cutting force of EVC due to its unique elliptical motion trajectory. Study on chip formation will helpfully to predict cutting force. The geometric feature of chip has important effects on cutting force, however, few scholars have studied the chip formation. In order to investigate the time-varying cutting force of EVC, the geometric feature model of chip is established based on analysis of chip formation, and the effects of cutting parameters on the geometric feature of chip are analyzed. To predict transient force quickly and effectively, the geometric feature of chip is introduced into the cutting force model. The calculated results show that the error between the predicted cutting force in this paper and that in the literature is less than 2%, which proves its feasibility.
Wavelet-based analysis of transient electromagnetic wave propagation in photonic crystals.
Shifman, Yair; Leviatan, Yehuda
2004-03-01
Photonic crystals and optical bandgap structures, which facilitate high-precision control of electromagnetic-field propagation, are gaining ever-increasing attention in both scientific and commercial applications. One common photonic device is the distributed Bragg reflector (DBR), which exhibits high reflectivity at certain frequencies. Analysis of the transient interaction of an electromagnetic pulse with such a device can be formulated in terms of the time-domain volume integral equation and, in turn, solved numerically with the method of moments. Owing to the frequency-dependent reflectivity of such devices, the extent of field penetration into deep layers of the device will be different depending on the frequency content of the impinging pulse. We show how this phenomenon can be exploited to reduce the number of basis functions needed for the solution. To this end, we use spatiotemporal wavelet basis functions, which possess the multiresolution property in both spatial and temporal domains. To select the dominant functions in the solution, we use an iterative impedance matrix compression (IMC) procedure, which gradually constructs and solves a compressed version of the matrix equation until the desired degree of accuracy has been achieved. Results show that when the electromagnetic pulse is reflected, the transient IMC omits basis functions defined over the last layers of the DBR, as anticipated.
Directory of Open Access Journals (Sweden)
Andrzej Rusek
2008-01-01
Full Text Available The mathematical model of cylindrical linear induction motor (C-LIM fed via frequency converter is presented in the paper. The model was developed in order to analyze numerically the transient states. Problems concerning dynamics of ac-machines especially linear induction motor are presented in [1 – 7]. Development of C-LIM mathematical model is based on circuit method and analogy to rotary induction motor. The analogy between both: (a stator and rotor windings of rotary induction motor and (b winding of primary part of C-LIM (inductor and closed current circuits in external secondary part of C-LIM (race is taken into consideration. The equations of C-LIM mathematical model are presented as matrix together with equations expressing each vector separately. A computational analysis of selected transient states of C-LIM fed via frequency converter is presented in the paper. Two typical examples of C-LIM operation are considered for the analysis: (a starting the motor at various static loads and various synchronous velocities and (b reverse of the motor at the same operation conditions. Results of simulation are presented as transient responses including transient electromagnetic force, transient linear velocity and transient phase current.
Boom or bust? A comparative analysis of transient population dynamics in plants
DEFF Research Database (Denmark)
Stott, Iain; Franco, Miguel; Carslake, David
2010-01-01
a population must become before reaching its maximum possible transient amplification following a disturbance) and the extension of this and other transient indices to simultaneously describe both amplified and attenuated transient dynamics. We apply the Kreiss bound and other transient indices to a data base......Population dynamics often defy predictions based on empirical models, and explanations for noisy dynamics have ranged from deterministic chaos to environmental stochasticity. Transient (short-term) dynamics following disturbance or perturbation have recently gained empirical attention from...... succession have the highest potential for transient amplification and attenuation, whereas species with intermediate life history complexity have the lowest potential. We find ecological relationships between transients and asymptotic dynamics: faster-growing populations tend to have greater potential...
Federici, Gianfranco; Raffray, A. René
1997-04-01
The transient thermal model RACLETTE (acronym of Rate Analysis Code for pLasma Energy Transfer Transient Evaluation) described in part I of this paper is applied here to analyse the heat transfer and erosion effects of various slow (100 ms-10 s) high power energy transients on the actively cooled plasma facing components (PFCs) of the International Thermonuclear Experimental Reactor (ITER). These have a strong bearing on the PFC design and need careful analysis. The relevant parameters affecting the heat transfer during the plasma excursions are established. The temperature variation with time and space is evaluated together with the extent of vaporisation and melting (the latter only for metals) for the different candidate armour materials considered for the design (i.e., Be for the primary first wall, Be and CFCs for the limiter, Be, W, and CFCs for the divertor plates) and including for certain cases low-density vapour shielding effects. The critical heat flux, the change of the coolant parameters and the possible severe degradation of the coolant heat removal capability that could result under certain conditions during these transients, for example for the limiter, are also evaluated. Based on the results, the design implications on the heat removal performance and erosion damage of the variuos ITER PFCs are critically discussed and some recommendations are made for the selection of the most adequate protection materials and optimum armour thickness.
International Nuclear Information System (INIS)
Federici, G.; Raffray, A.R.
1997-01-01
For pt.I see ibid., p.85-100, 1997. The transient thermal model RACLETTE (acronym of Rate Analysis Code for pLasma Energy Transfer Transient Evaluation) described in part I of this paper is applied here to analyse the heat transfer and erosion effects of various slow (100 ms-10 s) high power energy transients on the actively cooled plasma facing components (PFCs) of the International Thermonuclear Experimental Reactor (ITER). These have a strong bearing on the PFC design and need careful analysis. The relevant parameters affecting the heat transfer during the plasma excursions are established. The temperature variation with time and space is evaluated together with the extent of vaporisation and melting (the latter only for metals) for the different candidate armour materials considered for the design (i.e., Be for the primary first wall, Be and CFCs for the limiter, Be, W, and CFCs for the divertor plates) and including for certain cases low-density vapour shielding effects. The critical heat flux, the change of the coolant parameters and the possible severe degradation of the coolant heat removal capability that could result under certain conditions during these transients, for example for the limiter, are also evaluated. Based on the results, the design implications on the heat removal performance and erosion damage of the various ITER PFCs are critically discussed and some recommendations are made for the selection of the most adequate protection materials and optimum armour thickness. (orig.)
Pre-test analysis of protected loss of primary pump transients in CIRCE-HERO facility
Narcisi, V.; Giannetti, F.; Del Nevo, A.; Tarantino, M.; Caruso, G.
2017-11-01
In the frame of LEADER project (Lead-cooled European Advanced Demonstration Reactor), a new configuration of the steam generator for ALFRED (Advanced Lead Fast Reactor European Demonstrator) was proposed. The new concept is a super-heated steam generator, double wall bayonet tube type with leakage monitoring [1]. In order to support the new steam generator concept, in the framework of Horizon 2020 SESAME project (thermal hydraulics Simulations and Experiments for the Safety Assessment of MEtal cooled reactors), the ENEA CIRCE pool facility will be refurbished to host the HERO (Heavy liquid mEtal pRessurized water cOoled tubes) test section to investigate a bundle of seven full scale bayonet tubes in ALFRED-like thermal hydraulics conditions. The aim of this work is to verify thermo-fluid dynamic performance of HERO during the transition from nominal to natural circulation condition. The simulations have been performed with RELAP5-3D© by using the validated geometrical model of the previous CIRCE-ICE test section [2], in which the preceding heat exchanger has been replaced by the new bayonet bundle model. Several calculations have been carried out to identify thermal hydraulics performance in different steady state conditions. The previous calculations represent the starting points of transient tests aimed at investigating the operation in natural circulation. The transient tests consist of the protected loss of primary pump, obtained by reducing feed-water mass flow to simulate the activation of DHR (Decay Heat Removal) system, and of the loss of DHR function in hot conditions, where feed-water mass flow rate is absent. According to simulations, in nominal conditions, HERO bayonet bundle offers excellent thermal hydraulic behavior and, moreover, it allows the operation in natural circulation.
International Nuclear Information System (INIS)
Barbet, N.; Dumas, M.; Mihelich, G.; Souchet, Y.; Thomas, J.B.
1987-04-01
Two developments of expert systems intended to work on line to the analysis of nuclear reactor transients are reported. During an hypothetical crisis occurring in a nuclear facility, a staff of the Institute for Protection and Nuclear Safety (IPSN) has to assess the risk to local population. The expert system is intended to work as an assistant to the staff. At the present time, it deals with the availability of the safety systems of the plant (e.g. ECCS), depending on the functional state of the support systems. A next step is to take into account the physical transient of the reactor (mass and energy balance, pressure, flows). In order to reach this goal as in the development of other similar expert systems, a physical analyser is required. This is the aim of SEXTANT, which combines several knowledge bases concerning measurements, models and qualitative behaviour of the plant with a mechanism of conjecture-refutation and a set of simplified models matching the current physical state. A prototype is under assessment by dealing with integral test facility transients. Both expert systems require powerful shells for their development. SPIRAL is such a toolkit for the development of expert systems devoted to the computer aided management of complex processes
Notes on human performance analysis
International Nuclear Information System (INIS)
Hollnagel, E.; Pedersen, O.M.; Rasmussen, J.
1981-06-01
This paper contains a framework for the integration of observation and analysis of human performance in nuclear environments - real or simulated. It identifies four main sources of data, and describes the characteristic data types and methods of analysis for each source in relation to a common conceptual background. The general conclusion is that it is highly useful to combine the knowledge and experience from different contexts into coherent picture of how nuclear operators perform under varying circumstances. (author)
Energy Technology Data Exchange (ETDEWEB)
Onur, M.; Serpen, U.; Gok, I.M. [Istanbul Technical Univ. (Turkey). Faculty of Mines; Zeybek, A.D. [Al-Mutlaq Compound, Al-Khobar (Saudi Arabia)
2003-04-01
The analyses of two build-up tests and one interference test in the Kizildere geothermal field, Turkey, are presented. Modern well test analysis methods based on pressure-derivative (logarithmic time rate of pressure) and non-linear regression, as well as conventional log-log and semi-log straight-line methods, have been used in the interpretation of these field pressure tests. Pressure transient models based on both homogeneous reservoirs and fractal reservoirs without matrix participation are considered in the analysis. It is shown that the use of conventional analysis methods alone can lead to an inaccurate interpretation of these field tests, and the use of modern analysis techniques in conjunction with conventional analysis techniques provides a more reliable and accurate interpretation of the well test data in the Kizildere geothermal field. The information obtained (e.g., estimates of permeability thickness and fractal dimensions) from analyses of these tests should prove useful for reservoir characterization studies in the Kizildere field, where reinjection is scheduled to begin soon. Finally, the modern interpretation methods described in this paper are recommended for analysis of well test pressure data from geothermal reservoirs. (Author)
Directory of Open Access Journals (Sweden)
Asan Mohideen Khansadurai
2014-01-01
Full Text Available The main objective of the paper is to design a model reference adaptive controller (MRAC with improved transient performance. A modification to the standard direct MRAC called fuzzy modified MRAC (FMRAC is used in the paper. The FMRAC uses a proportional control based Mamdani-type fuzzy logic controller (MFLC to improve the transient performance of a direct MRAC. The paper proposes the application of real-coded genetic algorithm (RGA to tune the membership function parameters of the proposed FMRAC offline so that the transient performance of the FMRAC is improved further. In this study, a GA based modified MRAC (GAMMRAC, an FMRAC, and a GA based FMRAC (GAFMRAC are designed for a coupled tank setup in a hybrid tank process and their transient performances are compared. The results show that the proposed GAFMRAC gives a better transient performance than the GAMMRAC or the FMRAC. It is concluded that the proposed controller can be used to obtain very good transient performance for the control of nonlinear processes.
International Nuclear Information System (INIS)
Johnson, H.G.
1982-01-01
The Fast Flux Test Facility (FFTF) is arranged for natural circulation emergency core cooling in the event of loss of all plant electrical power. This design feature was conclusively demonstrated in a series of four natural circulation transient tests during the plant startup testing program in 1980 and 1981. Predictions, of core performance during these tests were made using the Westinghouse Hanford Company CORA computer program. The predictions, which compared well with measured plant data, were used in the extrapolation process to demonstrate the validity of the FFTF plant safety models and codes. This paper provides a brief description of the CORA code and includes typical comparisons of predictions to measured plant test data
Finite element analysis of transient viscous flow with free surface using filling pattern technique
International Nuclear Information System (INIS)
Kim, Ki Don; Yang, Dong Yol; Jeong, Jun Ho
2001-01-01
The filling pattern technique based on the finite element method and Eulerian mesh advancement approach has been developed to analyze incompressible transient viscous flow with free surfaces. The governing equation for flow analysis is Navier-Stokes equation including inertia and gravity effects. The penalty and predictor-corrector methods are used effectively for finite element formulation. The flow front surface and the volume inflow rate are calculated using the filling pattern technique to select an adequate pattern among four filling patterns at each triangular control volume. Using the proposed numerical technique, the collapse of a dam has been analyzed to predict flow phenomenon of fluid and the predicted front positions versus time have been compared with the reported experimental result
Evaluation of time integration methods for transient response analysis of nonlinear structures
International Nuclear Information System (INIS)
Park, K.C.
1975-01-01
Recent developments in the evaluation of direct time integration methods for the transient response analysis of nonlinear structures are presented. These developments, which are based on local stability considerations of an integrator, show that the interaction between temporal step size and nonlinearities of structural systems has a pronounced effect on both accuracy and stability of a given time integration method. The resulting evaluation technique is applied to a model nonlinear problem, in order to: 1) demonstrate that it eliminates the present costly process of evaluating time integrator for nonlinear structural systems via extensive numerical experiments; 2) identify the desirable characteristics of time integration methods for nonlinear structural problems; 3) develop improved stiffly-stable methods for application to nonlinear structures. Extension of the methodology for examination of the interaction between a time integrator and the approximate treatment of nonlinearities (such as due to pseudo-force or incremental solution procedures) is also discussed. (Auth.)
International Nuclear Information System (INIS)
Zeuch, W.R.; Wang, C.Y.
1985-01-01
This paper presents some of the current capabilities of the three-dimensional piping code SHAPS and demonstrates their usefulness in handling analyses encountered in typical LMFBR studies. Several examples demonstrate the utility of the SHAPS code for problems involving fluid-structure interactions and seismic-related events occurring in three-dimensional piping networks. Results of two studies of pressure wave propagation demonstrate the dynamic coupling of pipes and elbows producing global motion and rigorous treatment of physical quantities such as changes in density, pressure, and strain energy. Results of the seismic analysis demonstrate the capability of SHAPS to handle dynamic structural response within a piping network over an extended transient period of several seconds. Variation in dominant stress frequencies and global translational frequencies were easily handled with the code. 4 refs., 10 figs
Arman, Yusuf; Zor, Mehmet; Güngör, M Ali; Akan, Ender; Aksoy, Sami
2009-09-18
Transient and residual stresses occurring in partially fixed dental prostheses after the firing process can be calculated with elastic or elastic-plastic finite element analyses (FEA). In this study, firstly, the mechanical and thermal properties at various temperatures of the materials used in a porcelain fused metal (PFM) system were obtained by experimental and literature studies. The effects of viscoelastic and viscoplastic behaviours of the dental porcelain at the elevated temperatures were reflected onto its elastic properties. The equivalent heat transfer coefficients were determined experimentally by measuring temperatures and the results were supplied as input to the 3D finite elements analysis. It has been observed that the maximum stresses occur within a short time period after cooling begins and that stresses decrease during the cooling process and remain at a constant value at the end of cooling; these are the thermal residual stresses.
Tamma, Kumar K.; D'Costa, Joseph F.
1991-01-01
This paper describes the evaluation of mixed implicit-explicit finite element formulations for hyperbolic heat conduction problems involving non-Fourier effects. In particular, mixed implicit-explicit formulations employing the alpha method proposed by Hughes et al. (1987, 1990) are described for the numerical simulation of hyperbolic heat conduction models, which involves time-dependent relaxation effects. Existing analytical approaches for modeling/analysis of such models involve complex mathematical formulations for obtaining closed-form solutions, while in certain numerical formulations the difficulties include severe oscillatory solution behavior (which often disguises the true response) in the vicinity of the thermal disturbances, which propagate with finite velocities. In view of these factors, the alpha method is evaluated to assess the control of the amount of numerical dissipation for predicting the transient propagating thermal disturbances. Numerical test models are presented, and pertinent conclusions are drawn for the mixed-time integration simulation of hyperbolic heat conduction models involving non-Fourier effects.
Thermal Power Plant Performance Analysis
2012-01-01
The analysis of the reliability and availability of power plants is frequently based on simple indexes that do not take into account the criticality of some failures used for availability analysis. This criticality should be evaluated based on concepts of reliability which consider the effect of a component failure on the performance of the entire plant. System reliability analysis tools provide a root-cause analysis leading to the improvement of the plant maintenance plan. Taking in view that the power plant performance can be evaluated not only based on thermodynamic related indexes, such as heat-rate, Thermal Power Plant Performance Analysis focuses on the presentation of reliability-based tools used to define performance of complex systems and introduces the basic concepts of reliability, maintainability and risk analysis aiming at their application as tools for power plant performance improvement, including: · selection of critical equipment and components, · defini...
Energy Technology Data Exchange (ETDEWEB)
Vinai, P
2007-10-15
For the development, design and licensing of a nuclear power plant (NPP), a sound safety analysis is necessary to study the diverse physical phenomena involved in the system behaviour under operational and transient conditions. Such studies are based on detailed computer simulations. With the progresses achieved in computer technology and the greater availability of experimental and plant data, the use of best estimate codes for safety evaluations has gained increasing acceptance. The application of best estimate safety analysis has raised new problems that need to be addressed: it has become more crucial to assess as to how reliable code predictions are, especially when they need to be compared against safety limits that must not be crossed. It becomes necessary to identify and quantify the various possible sources of uncertainty that affect the reliability of the results. Currently, such uncertainty evaluations are generally based on experts' opinion. In the present research, a novel methodology based on a non-parametric statistical approach has been developed for objective quantification of best-estimate code uncertainties related to the physical models used in the code. The basis is an evaluation of the accuracy of a given physical model achieved by comparing its predictions with experimental data from an appropriate set of separate-effect tests. The differences between measurements and predictions can be considered stochastically distributed, and thus a statistical approach can be employed. The first step was the development of a procedure for investigating the dependence of a given physical model's accuracy on the experimental conditions. Each separate-effect test effectively provides a random sample of discrepancies between measurements and predictions, corresponding to a location in the state space defined by a certain number of independent system variables. As a consequence, the samples of 'errors', achieved from analysis of the entire
Directory of Open Access Journals (Sweden)
Saeed Soleymani
2016-01-01
Full Text Available This paper Analytically investigates the effects of system and controller parameters and operating conditions on the dynamic and transient behavior of wind turbines (WTs with doubly-fed induction generators (DFIGs under voltage dips and wind speed fluctuations. Also, it deals with the design considerations regarding rotor and speed controllers. The poorly damped electrical and mechanical modes of the system are identified, and the effects of system parameters, and speed/rotor controllers on these modes are investigated by modal and sensitivity analyses. The results of theoretical studies are verified by time domain simulations. It is found that the dynamic behavior of the DFIG-based WT under voltage dips is strongly affected by the stator dynamics. Further, it is shown that the closed loop bandwidth of the rotor current control, rotor current damping, DFIG power factor and the rotor back-emf voltages have high impact on the stator modes and consequently on the DFIG dynamic behavior. Moreover, it is shown that the dynamic behavior of DFIG-based WT under wind speed fluctuation is significantly dependent on the bandwidth and damping of speed control loop.
Dalgleish, Simon; Reissig, Louisa; Hu, Laigui; Matsushita, Michio M; Sudo, Yuki; Awaga, Kunio
2015-05-12
A novel planar architecture has been developed for the study of photodetectors utilizing the transient photocurrent response induced by a metal/insulator/semiconductor/metal (MISM) structured device, where the insulator is an ionic liquid (IL-MISM). Using vanadyl 2,3-naphthalocyanine, which absorbs in the communications-relevant near-infrared wavelength region (λ(max,film) ≈ 850 nm), in conjunction with C60 as a bulk heterojunction, the high capacitance of the formed electric double layers at the ionic liquid interfaces yields high charge separation efficiency within the semiconductor layer, and the minimal potential drop in the bulk ionic liquid allows the electrodes to be offset by distances of over 7 mm. Furthermore, the decrease in operational speed with increased electrode separation is beneficial for a clear modeling of the waveform of the photocurrent signal, free from the influence of measurement circuitry. Despite the use of a molecular semiconductor as the active layer in conjunction with a liquid insulating layer, devices with a stability of several days could be achieved, and the operational stability of such devices was shown to be dependent solely on the solubility of the active layer in the ionic liquid, even under atmospheric conditions. Furthermore, the greatly simplified device construction process, which does not rely on transparent electrode materials or direct electrode deposition, provides a highly reproducible platform for the study of the electronic processes within IL-MISM detectors that is largely free from architectural constraints.
Benchmarking of Modern Data Analysis Tools for a 2nd generation Transient Data Analysis Framework
Goncalves, Nuno
2016-01-01
During the past year of operating the Large Hadron Collider (LHC), the amount of transient accelerator data to be persisted and analysed has been steadily growing. Since the startup of the LHC in 2006, the amount of weekly data storage requirements exceeded what the systems was initially designed to accommodate in a full year of operation. Moreover, it is predicted that the data acquisition rates will continue to increase in the future, due to foreseen improvements in the infrastructure within the scope of the High Luminosity LHC project. Despite the efforts for improving and optimizing the current data storage infrastructures (CERN Accelerator Logging Service and Post Mortem database), some limitations still persist and require a different approach to scale up efficiently to provide efficient services for future machine upgrades. This project aims to explore one of the possibilities among novel solutions proposed to solve the problem of working with large datasets. The configuration is composed of Spark for ...
DEFF Research Database (Denmark)
Dorrell, David G.; Hermann, Alexander Niels August; Jensen, Bogi Bech
2013-01-01
eccentricity. The operating conditions are varied so that transient, motoring and doubly-fed induction generator modes are studied. This allows greater understanding of the radial forces involved. Wound rotor induction machines exhibit higher unbalanced magnetic pull than cage induction machines so......There has been much literature on unbalanced magnetic pull in various types of electrical machine. This can lead to bearing wear and additional vibrations in the machine. In this paper a wound rotor induction is studied. Finite element analysis studies are conducted when the rotor has 10 % rotor...
TRAC-PF1 analysis of LOFT steam-generator feedwater transient test L9-1
International Nuclear Information System (INIS)
Meier, J.K.
1983-01-01
The Transient Reactor Analysis Code (TRAC-PF1) calculations were compared to test data from Loss-of-Fluid Test (LOFT) L9-1, which was a loss-of-feedwater transient. This paper includes descriptions of the test and the TRAC input and compares the TRAC-calculated results with the test data. We conclude that the code predicted the experiment well, given the uncertainties in the boundary conditions. The analysis indicates the need to model all the flow paths and heat structures, and to improve the TRAC wall condensation heat-transfer model
Development of Input/Output System for the Reactor Transient Analysis System (RETAS)
Energy Technology Data Exchange (ETDEWEB)
Suh, Jae Seung; Kang, Doo Hyuk; Cho, Yeon Sik [ENESYS, Daejeon (Korea, Republic of); Ahn, Seung Hoon; Cho, Yong Jin [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2009-05-15
A Korea Institute of Nuclear Safety Reactor Transient Analysis System (KINS-RETAS) aims at providing a realistic prediction of core and RCS response to the potential or actual event scenarios in Korean nuclear power plants (NPPs). A thermal hydraulic system code MARS is a pivot code of the RETAS, and used to predict thermal hydraulic (TH) behaviors in the core and associated systems. MARS alone can be applied to many types of transients, but is sometimes coupled with the other codes developed for different objectives. Many tools have been developed to aid users in preparing input and displaying the transient information and output data. Output file and Graphical User Interfaces (GUI) that help prepare input decks, as seen in SNAP (Gitnick, 1998), VISA (K.D. Kim, 2007) and display aids include the eFAST (KINS, 2007). The tools listed above are graphical interfaces. The input deck builders allow the user to create a functional diagram of the plant, pictorially on the screen. The functional diagram, when annotated with control volume and junction numbers, is a nodalization diagram. Data required for an input deck is entered for volumes and junctions through a mouse-driven menu and pop-up dialog; after the information is complete, an input deck is generated. Display GUIs show data from MARS calculations, either during or after the transient. The RETAS requires the user to first generate a set of 'input', two dimensional pictures of the plant on which some of the data is displayed either numerically or with a color map. The RETAS can generate XY-plots of the data. Time histories of plant conditions can be seen via the plots or through the RETAS's replay mode. The user input was combined with design input from MARS developers and experts from both the GUI and ergonomics fields. A partial list of capabilities follows. - 3D display for neutronics. - Easier method (less user time and effort) to generate 'input' for the 3D displays. - Detailed view
TACO: fuel pin performance analysis
International Nuclear Information System (INIS)
Stoudt, R.H.; Buchanan, D.T.; Buescher, B.J.; Losh, L.L.; Wilson, H.W.; Henningson, P.J.
1977-08-01
The thermal performance of fuel in an LWR during its operational lifetime must be described for LOCA analysis as well as for other safety analyses. The determination of stored energy in the LOCA analysis, for example, requires a conservative fuel pin thermal performance model that is capable of calculating fuel and cladding behavior, including the gap conductance between the fuel and cladding, as a function of burnup. The determination of parameters that affect the fuel and cladding performance, such as fuel densification, fission gas release, cladding dimensional changes, fuel relocation, and thermal expansion, should be accounted for in the model. Babcock and Wilcox (B and W) has submitted a topical report, BAW-10087P, December 1975, which describes their thermal performance model TACO. A summary of the elements that comprise the TACO model and an evaluation are presented
Experimental analysis on the dynamic wake of an actuator disc undergoing transient loads
Yu, W.; Hong, V. W.; Ferreira, C.; van Kuik, G. A. M.
2017-10-01
The Blade Element Momentum model, which is based on the actuator disc theory, is still the model most used for the design of open rotors. Although derived from steady cases with a fully developed wake, this approach is also applied to unsteady cases, with additional engineering corrections. This work aims to study the impact of an unsteady loading on the wake of an actuator disc. The load and flow of an actuator disc are measured in the Open Jet Facility wind tunnel of Delft University of Technology, for steady and unsteady cases. The velocity and turbulence profiles are characterized in three regions: the inner wake region, the shear layer region and the region outside the wake. For unsteady load cases, the measured velocity field shows a hysteresis effect in relation to the loading, showing differences between the cases when loading is increased and loading is decreased. The flow field also shows a transient response to the step change in loading, with either an overshoot or undershoot of the velocity in relation to the steady-state velocity. In general, a smaller reduced ramp time results in a faster velocity transient, and in turn a larger amplitude of overshoot or undershoot. Time constants analysis shows that the flow reaches the new steady-state slower for load increase than for load decrease; the time constants outside the wake are generally larger than at other radial locations for a given downstream plane; the time constants of measured velocity in the wake show radial dependence.The data are relevant for the validation of numerical models for unsteady actuator discs and wind turbines, and are made available in an open source database (see Appendix).
Transient analysis of a molten salt central receiver (MSCR) in a solar power plant
Joshi, A.; Wang, C.; Akinjiola, O.; Lou, X.; Neuschaefer, C.; Quinn, J.
2016-05-01
Alstom is developing solar power tower plants utilizing molten salt as the working fluid. In solar power tower, the molten salt central receiver (MSCR) atop of the tower is constructed of banks of tubes arranged in panels creating a heat transfer surface exposed to the solar irradiation from the heliostat field. The molten salt heat transfer fluid (HTF), in this case 60/40%wt NaNO3-KNO3, flows in serpentine flow through the surface collecting sensible heat thus raising the HTF temperature from 290°C to 565°C. The hot molten salt is stored and dispatched to produce superheated steam in a steam generator, which in turn produces electricity in the steam turbine generator. The MSCR based power plant with a thermal energy storage system (TESS) is a fully dispatchable renewable power plant with a number of opportunities for operational and economic optimization. This paper presents operation and controls challenges to the MSCR and the overall power plant, and the use of dynamic model computer simulation based transient analyses applied to molten salt based solar thermal power plant. This study presents the evaluation of the current MSCR design, using a dynamic model, with emphasis on severe events affecting critical process response, such as MS temperature deviations, and recommend MSCR control design improvements based on the results. Cloud events are the scope of the transient analysis presented in this paper. The paper presents results from a comparative study to examine impacts or effects on key process variables related to controls and operation of the MSCR plant.
Wu, Guangxi; Yu, Xiong
2015-06-01
Thermoelectric power generator has potential for small-scale and distributed power generation because of its high durability and scalability. It is very important to realize that the transient behavior of thermoelectric modules (TEM) affects a thermoelectric generator's response to dynamic working environments. Traditionally, researchers have used simplified models to describe the behavior of thermoelectric modules. In this paper we propose a comprehensive mathematical model that considers the effect of variations of chemical potential and carrier density, which are ignored by traditional models. Finite element models based on this new model are used to simulate the transient behavior of a thermoelectric module subjected to rapid changes in boundary temperature or working load. Simulation results show that transition times of thermoelectric modules affected by temperature change are much longer than those of modules affected by changes in electrical load resistance. Sudden changes in working temperature cause voltage overshoot of the TEM output, which, however, is not observed in responses to sudden changes of load resistance. Comparisons also show there are significant differences between the behavior of TEM predicted by use of this new comprehensive model and that predicted by use of traditional models, particularly for the high-temperature intrinsic ionization region and the low-temperature weak ionization region. This implies that chemical potential and carrier density variations, which are taken into account by this new model but ignored by traditional models, have major effects on the performance of TEM.
Identification of a cis-regulatory element by transient analysis of co-ordinately regulated genes
Directory of Open Access Journals (Sweden)
Allan Andrew C
2008-07-01
Full Text Available Abstract Background Transcription factors (TFs co-ordinately regulate target genes that are dispersed throughout the genome. This co-ordinate regulation is achieved, in part, through the interaction of transcription factors with conserved cis-regulatory motifs that are in close proximity to the target genes. While much is known about the families of transcription factors that regulate gene expression in plants, there are few well characterised cis-regulatory motifs. In Arabidopsis, over-expression of the MYB transcription factor PAP1 (PRODUCTION OF ANTHOCYANIN PIGMENT 1 leads to transgenic plants with elevated anthocyanin levels due to the co-ordinated up-regulation of genes in the anthocyanin biosynthetic pathway. In addition to the anthocyanin biosynthetic genes, there are a number of un-associated genes that also change in expression level. This may be a direct or indirect consequence of the over-expression of PAP1. Results Oligo array analysis of PAP1 over-expression Arabidopsis plants identified genes co-ordinately up-regulated in response to the elevated expression of this transcription factor. Transient assays on the promoter regions of 33 of these up-regulated genes identified eight promoter fragments that were transactivated by PAP1. Bioinformatic analysis on these promoters revealed a common cis-regulatory motif that we showed is required for PAP1 dependent transactivation. Conclusion Co-ordinated gene regulation by individual transcription factors is a complex collection of both direct and indirect effects. Transient transactivation assays provide a rapid method to identify direct target genes from indirect target genes. Bioinformatic analysis of the promoters of these direct target genes is able to locate motifs that are common to this sub-set of promoters, which is impossible to identify with the larger set of direct and indirect target genes. While this type of analysis does not prove a direct interaction between protein and DNA
AITRAC: Augmented Interactive Transient Radiation Analysis by Computer. User's information manual
Energy Technology Data Exchange (ETDEWEB)
1977-10-01
AITRAC is a program designed for on-line, interactive, DC, and transient analysis of electronic circuits. The program solves linear and nonlinear simultaneous equations which characterize the mathematical models used to predict circuit response. The program features 100 external node--200 branch capability; conversional, free-format input language; built-in junction, FET, MOS, and switch models; sparse matrix algorithm with extended-precision H matrix and T vector calculations, for fast and accurate execution; linear transconductances: beta, GM, MU, ZM; accurate and fast radiation effects analysis; special interface for user-defined equations; selective control of multiple outputs; graphical outputs in wide and narrow formats; and on-line parameter modification capability. The user describes the problem by entering the circuit topology and part parameters. The program then automatically generates and solves the circuit equations, providing the user with printed or plotted output. The circuit topology and/or part values may then be changed by the user, and a new analysis, requested. Circuit descriptions may be saved on disk files for storage and later use. The program contains built-in standard models for resistors, voltage and current sources, capacitors, inductors including mutual couplings, switches, junction diodes and transistors, FETS, and MOS devices. Nonstandard models may be constructed from standard models or by using the special equations interface. Time functions may be described by straight-line segments or by sine, damped sine, and exponential functions. 42 figures, 1 table. (RWR)
AITRAC: Augmented Interactive Transient Radiation Analysis by Computer. User's information manual
International Nuclear Information System (INIS)
1977-10-01
AITRAC is a program designed for on-line, interactive, DC, and transient analysis of electronic circuits. The program solves linear and nonlinear simultaneous equations which characterize the mathematical models used to predict circuit response. The program features 100 external node--200 branch capability; conversional, free-format input language; built-in junction, FET, MOS, and switch models; sparse matrix algorithm with extended-precision H matrix and T vector calculations, for fast and accurate execution; linear transconductances: beta, GM, MU, ZM; accurate and fast radiation effects analysis; special interface for user-defined equations; selective control of multiple outputs; graphical outputs in wide and narrow formats; and on-line parameter modification capability. The user describes the problem by entering the circuit topology and part parameters. The program then automatically generates and solves the circuit equations, providing the user with printed or plotted output. The circuit topology and/or part values may then be changed by the user, and a new analysis, requested. Circuit descriptions may be saved on disk files for storage and later use. The program contains built-in standard models for resistors, voltage and current sources, capacitors, inductors including mutual couplings, switches, junction diodes and transistors, FETS, and MOS devices. Nonstandard models may be constructed from standard models or by using the special equations interface. Time functions may be described by straight-line segments or by sine, damped sine, and exponential functions. 42 figures, 1 table
Xue, H.; Popov, M.
2013-01-01
Large transient overvoltages are normally caused by vacuum circuit breaker (VCB) switching operation during disconnection of induction motors. In this paper VCBs, cables, generators, busbars, induction motors and surge arresters are modeled by making use of ATP-EMTP. Switching transient overvoltages
EXPERIMENTAL PERFORMANCE ANALYSIS OF WIRELESS ...
African Journals Online (AJOL)
ABSTRACT. Wireless networking is currently being deployed for various applications. However, the application of wireless networking in healthcare remains a challenge mainly because of security and reliability concerns. This paper presents experimental results of performance analysis of a wireless network for healthcare ...
design analysis and performance evaluation
African Journals Online (AJOL)
The design analysis and performance evaluation of an active solar crop dryer was undertaken by drying marched cassava. The drying rate, system drying, collector and pick-up efficiencies were 1.6kg/day (14%/day), 9%, 46% and 29% respectively. Comparatively, the drying rate for sun drying was 0.9kg/day. The collector ...
Fuel performance analysis code 'FAIR'
International Nuclear Information System (INIS)
Swami Prasad, P.; Dutta, B.K.; Kushwaha, H.S.; Mahajan, S.C.; Kakodkar, A.
1994-01-01
For modelling nuclear reactor fuel rod behaviour of water cooled reactors under severe power maneuvering and high burnups, a mechanistic fuel performance analysis code FAIR has been developed. The code incorporates finite element based thermomechanical module, physically based fission gas release module and relevant models for modelling fuel related phenomena, such as, pellet cracking, densification and swelling, radial flux redistribution across the pellet due to the build up of plutonium near the pellet surface, pellet clad mechanical interaction/stress corrosion cracking (PCMI/SSC) failure of sheath etc. The code follows the established principles of fuel rod analysis programmes, such as coupling of thermal and mechanical solutions along with the fission gas release calculations, analysing different axial segments of fuel rod simultaneously, providing means for performing local analysis such as clad ridging analysis etc. The modular nature of the code offers flexibility in affecting modifications easily to the code for modelling MOX fuels and thorium based fuels. For performing analysis of fuel rods subjected to very long power histories within a reasonable amount of time, the code has been parallelised and is commissioned on the ANUPAM parallel processing system developed at Bhabha Atomic Research Centre (BARC). (author). 37 refs
International Nuclear Information System (INIS)
Kwon, Young Min; Lee, Yong Bum; Chang, Won Pyo; Hahn, Do Hee
2002-06-01
The purpose of this study is to validate the analysis of the Unprotected Transient Overpower (UTOP) event in the KALIMER design using the SSC-K code against the SAS4A/SASSYS-1 computer code. At the same time, the predictive performance of the SSC-K code is evaluated by doing the code-to-code comparison analyses. The SAS4A/SASSYS-1 computer code is a general purpose one-dimensional thermal-hydraulic Liquid Metal Reactor (LMR) system analysis code. SAS4A/SASSYS-1 is especially suited for evaluating off-normal reactor transients, such as protected and unprotected transients. SAS4A/SASSYS-1 has been used in support of the IFR concept and of innovative LMR designs, such as PRISM and SAFR, and test facilities, such as EBR-II and FFTF, and there exists a strong validation base for the code. The adequacy of the SSC-K calculations for the UTOP event in the KALIMER design was confirmed by independent analyses using the SAS4A/SASSYS-1 code. The code-to-code comparison analyses show that the SSC-K calculation is generally acceptable and the feedback of reactivity in the SSC-K analysis is reasonably accurate. The comparison results also indicate that the thermal-hydraulic behaviors calculated by two codes during the UTOP event show good agreements
Transient analysis of rod drop accident for third fuel cycle for Angra-1 reactor using SACI2/MOD0
International Nuclear Information System (INIS)
Atayde, P.A. de.
1989-01-01
The rod drop accident for 3 0 fuel cycle of Angra-1 reactor is analysed, evaluating de position effect of detectors on the measurement of reactor power. The transient calculation was done using SAC12/MOD0 code for thermo-hydraulic analysis of reactor core, aiming to evaluate safe conditions during the accident. (M.C.K.)
DEFF Research Database (Denmark)
Hassager, Ole; Westborg, H
1987-01-01
An analysis of the transient rotating cylinder apparatus for the measurement of liquid-liquid interface viscosity is given. An analytical expression that allows the determination of the interfacial viscosity from observations of the interface movement is given. The expression is presented...... in tabular form for selected values of the physical parameters of the two phases, and suggestions for apparatus design are given....
Analysis methods of stochastic transient electro–magnetic processes in electric traction system
Directory of Open Access Journals (Sweden)
T. M. Mishchenko
2013-04-01
Full Text Available Purpose. The essence and basic characteristics of calculation methods of transient electromagnetic processes in the elements and devices of non–linear dynamic electric traction systems taking into account the stochastic changes of voltages and currents in traction networks of power supply subsystem and power circuits of electric rolling stock are developed. Methodology. Classical methods and the methods of non–linear electric engineering, as well as probability theory method, especially the methods of stationary ergodic and non–stationary stochastic processes application are used in the research. Findings. Using the above-mentioned methods an equivalent circuit and the system of nonlinear integra–differential equations for electromagnetic condition of the double–track inter-substation zone of alternating current electric traction system are drawn up. Calculations allow obtaining electric traction current distribution in the areas of feeder zones. Originality. First of all the paper is interesting and important from scientific point of view due to the methods, which allow taking into account probabilistic character of change for traction voltages and electric traction system currents. On the second hand the researches develop the most efficient methods of nonlinear circuits’ analysis. Practical value. The practical value of the research is presented in application of the methods to the analysis of electromagnetic and electric energy processes in the traction power supply system in the case of high-speed train traffic.
Transient Analysis of Thermal Protection System for X-33 Aircraft using MSC/NASTRAN
Miura, Hirokazu; Chargin, M. K.; Bowles, J.; Tam, T.; Chu, D.; Chainyk, M.; Green, Michael J. (Technical Monitor)
1997-01-01
X-33 is an advanced technology demonstrator vehicle for the Reusable Launch Vehicle (RLV) program. The thermal protection system (TPS) for the X-33 is composed of complex layers of materials to protect internal components, while withstanding severe external temperatures induced by aerodynamic heating during high speed flight. It also serves as the vehicle aeroshell in some regions using a stand-off design. MSC/NASTRAN thermal analysis capability was used to predict transient temperature distribution (within the TPS) throughout a mission, from launch through the cool-off period after landing. In this paper, a typical analysis model, representing a point on the vehicle where the liquid oxygen tank is closest to the outer mold line, is described. The maximum temperature difference between the outer mold line and the internal surface of the liquid oxygen tank can exceed 1500 F. One dimensional thermal models are used to select the materials and determine the thickness of each layer for minimum weight while insuring that all materials remain within the allowable temperature range. The purpose of working with three dimensional (3D) comprehensive models using MSC/NASTRAN is to assess the 3D radiation effects and the thermal conduction heat shorts of the support fixtures.
Transient analysis mode participation for modal survey target mode selection using MSC/NASTRAN DMAP
Barnett, Alan R.; Ibrahim, Omar M.; Sullivan, Timothy L.; Goodnight, Thomas W.
1994-01-01
Many methods have been developed to aid analysts in identifying component modes which contribute significantly to component responses. These modes, typically targeted for dynamic model correlation via a modal survey, are known as target modes. Most methods used to identify target modes are based on component global dynamic behavior. It is sometimes unclear if these methods identify all modes contributing to responses important to the analyst. These responses are usually those in areas of hardware design concerns. One method used to check the completeness of target mode sets and identify modes contributing significantly to important component responses is mode participation. With this method, the participation of component modes in dynamic responses is quantified. Those modes which have high participation are likely modal survey target modes. Mode participation is most beneficial when it is used with responses from analyses simulating actual flight events. For spacecraft, these responses are generated via a structural dynamic coupled loads analysis. Using MSC/NASTRAN DMAP, a method has been developed for calculating mode participation based on transient coupled loads analysis results. The algorithm has been implemented to be compatible with an existing coupled loads methodology and has been used successfully to develop a set of modal survey target modes.
Transient analysis mode participation for modal survey target mode selection using MSC/NASTRAN DMAP
Barnett, Alan R.; Ibrahim, Omar M.; Sullivan, Timothy L.; Goodnight, Thomas W.
1994-03-01
Many methods have been developed to aid analysts in identifying component modes which contribute significantly to component responses. These modes, typically targeted for dynamic model correlation via a modal survey, are known as target modes. Most methods used to identify target modes are based on component global dynamic behavior. It is sometimes unclear if these methods identify all modes contributing to responses important to the analyst. These responses are usually those in areas of hardware design concerns. One method used to check the completeness of target mode sets and identify modes contributing significantly to important component responses is mode participation. With this method, the participation of component modes in dynamic responses is quantified. Those modes which have high participation are likely modal survey target modes. Mode participation is most beneficial when it is used with responses from analyses simulating actual flight events. For spacecraft, these responses are generated via a structural dynamic coupled loads analysis. Using MSC/NASTRAN DMAP, a method has been developed for calculating mode participation based on transient coupled loads analysis results. The algorithm has been implemented to be compatible with an existing coupled loads methodology and has been used successfully to develop a set of modal survey target modes.
International Nuclear Information System (INIS)
Berta, V.T.
1977-05-01
Fourteen experiments on the Loss-of-Fluid Test (LOFT) facility pressure suppression system (PSS) are analyzed in relation to the vertical load generated on the suppression tank in the first 0.5 sec of the transient. Variations in principle parameters affecting the generation of vertical loads were included in the experiments. The internal and external vent submergences are identified from the analysis as being parameters which are first order in influencing the magnitude of the vertical load. These parameters are geometric in nature and depend only on PSS design. Physical parameters of total energy input and rate of energy input to the dry well, which influence the dry well pressurization, also are identified as being first order in influencing the magnitude of the vertical loads. The vertical load magnitude is a direct function of these geometric and physical parameters. The analysis indicates that a small value in any one of the parameters will cause the vertical load to be small and to have little dependence on the magnitude of the other parameters. In addition, the phenomena of nonuniform nonsynchronized vent inlet pressures, which have origins that are either geometric, physical, or a combination of both, act as a significant vertical load reduction mechanism
Directory of Open Access Journals (Sweden)
Yan Wang
2017-01-01
Full Text Available After a postulated design basis accident leads high temperature gas cooled reactor to emergency shutdown, steam generator still remains with high temperature level and needs to be cooled down by a precooling before reactor restarts with clearing of fault. For the large difference of coolant temperature between inlet and outlet of steam generator in normal operation, the temperature distribution on the components of steam generator is very complicated. Therefore, the temperature descending rate of the components in steam generator needs to be limited to avoid the potential damage during the precooling stage. In this paper, a pebble-bed high temperature gas cooled reactor is modeled by thermal-hydraulic system analysis code and several postulated precooling injection transients are simulated and compared to evaluate their effects, which will provide support for the precooling design. The analysis results show that enough precooling injection is necessary to satisfy the precooling requirements, and larger mass flow rate of precooling water injection will accelerate the precooling process. The temperature decrease of steam generator is related to the precooling injection scenarios, and the maximal mass flow rate of the precooling injection should be limited to avoid the excessively quick temperature change of the structures in steam generator.
International Nuclear Information System (INIS)
Lazaro, A.; Ammirabile, L.; Martorell, S.
2014-01-01
The article describes the changes implemented in the TRACE code to include thermodynamic tables of liquid lead drawn from experimental results. He then explains the process for developing a thermohydraulic model for the prototype ALFRED and analysis of a selection of representative transient conducted within the framework of international research projects. The study demonstrates the applicability of TRACE code to simulate designs of cooled lead fast reactors and exposes the high safety margins are there in this technology to accommodate the most severe transients identified in their security study. (Author)
Transient Analysis of Axially Moving Materials Interacting with External Dynamic Components
Zhu, Weidong
A new transient analysis, that overcomes the limitations of the spatially discretized models, is developed in the present study for the response of axially moving materials interacting with external dynamic components. First, the complex response of a time-varying, cable transport system, such as a tramway or cable car, is predicted from the model of an axially moving string transporting a damped, linear oscillator under arbitrary initial conditions, external forces and boundary excitations. A delay-integral equation describing the force of interaction between the cable and the payload is derived using the Green's function for the traveling string. Repeated scattering of transverse waves in the string at the payload is represented by the delay terms. The solution technique within the framework of the theory of distributions is developed for the delay -integral equation with discontinuous kernel and dependent variable. The forcing integrals are evaluated by both distribution and series expansion methods. Limitations of the series expansion approach are explored. Exact in the spatial domain, a temporal finite difference algorithm is presented for the solution of a resulting delay-integro -differential equation with discontinuous dependent variable. Special condition for the initial conditions of the system leading to vanishing slopes of the propagating wavefronts and consequently absence of the discontinuities in the interaction force is obtained. Second, the transient response of a translating string in contact with rigid and flexible constraints is determined for arbitrary initial conditions, external forces and boundary disturbances. The model represents the translating magnetic tape-head systems in computer data storage devices. The contact force between the string and a one-sided constraint is composed of a static preload component existing at the equilibrium and a dynamic component. The exact expression describing the dynamic contact force component is derived
Directory of Open Access Journals (Sweden)
Jeong Soon Park
2016-04-01
Full Text Available The failure probabilities of the reactor pressure vessel (RPV for low temperature over-pressurization (LTOP and cool-down transients are calculated in this study. For the cool-down transient, a pressure–temperature limit curve is generated in accordance with Section XI, Appendix G of the American Society of Mechanical Engineers (ASME code, from which safety margin factors are deliberately removed for the probabilistic fracture mechanics analysis. Then, sensitivity analyses are conducted to understand the effects of some input parameters. For the LTOP transient, the failure of the RPV mostly occurs during the period of the abrupt pressure rise. For the cool-down transient, the decrease of the fracture toughness with temperature and time plays a main role in RPV failure at the end of the cool-down process. As expected, the failure probability increases with increasing fluence, Cu and Ni contents, and initial reference temperature-nil ductility transition (RTNDT. The effect of warm prestressing on the vessel failure probability for LTOP is not significant because most of the failures happen before the stress intensity factor reaches the peak value while its effect reduces the failure probability by more than one order of magnitude for the cool-down transient.
International Nuclear Information System (INIS)
Ayazuddin, S.K.; Qureshi, A.A.; Hayat, T.
1997-11-01
The Primary Water Inlet Pipeline (PW-IPL) is of stainless steel conveying demineralized water from hold-up tank to the reactor pool of Pakistan Research Reactor-1 (PARR-1). The section of the pipeline from heat exchangers to the valve pit is hanger supported in the pump room and the rest of the section from valve pit to the reactor pool is embedded. The PW-IPL is subjected to steady state and transient vibrations. The reactor pumps, which drive the coolant through various circuits mainly contribute the steady state vibrations, while transient vibrations arise due to instant closure of the check valve (water hammer). The ASME Boiler and Pressure Vessel code provides data about the acceptable limits of stresses related to the primary static stress due to steady state vibrations. However, due to complexity in the pipe structure, stresses related to the transient vibrations are neglected in the code. In this report attempt has been made to analyzed both steady state and transient vibrations of PW-IPL of PARR-1. Since, both the steady state and transient vibrations affect the hanger-supported section of the PW-IPL, therefore, it was selected for vibration test measurements. In the analysis vibration data was compared with the allowable limits and estimations of maximum pressure build-up, eflection, natural frequency, tensile and shear load on hanger support, and the ratio of maximum combine stress to the allowable load were made. (author)
Grillmair, C. J.; Laher, R.; Surace, J.; Mattingly, S.; Hacopians, E.; Jackson, E.; van Eyken, J.; McCollum, B.; Groom, S.; Mi, W.; Teplitz, H.
2010-12-01
The Palomar Transient Factory is conducting a wide-field, variable-cadence optical survey of the northern sky to detect transient, variable, and moving objects. As a member of the PTF collaboration, the Infrared Processing and Analysis Center has developed an image archive, a high-quality photometry pipeline, and a searchable database of detected astronomical sources. The system is capable of processing and storing 300 Gbytes of data per night over the course of the 5-year survey. With an expected total of ˜ 20 billion rows, the table containing sources extracted from PTF images will be among the largest astronomical databases ever created. The survey is efficiently discovering transient sources from asteroids to supernovae, and will inform the development of future sky surveys like that of the Large Synoptic Survey Telescope.
Validation of coupled Relap5-3D code in the analysis of RBMK-1500 specific transients
International Nuclear Information System (INIS)
Evaldas, Bubelis; Algirdas, Kaliatka; Eugenijus, Uspuras
2003-01-01
This paper deals with the modelling of RBMK-1500 specific transients taking place at Ignalina NPP. These transients include: measurements of void and fast power reactivity coefficients, change of graphite cooling conditions and reactor power reduction transients. The simulation of these transients was performed using RELAP5-3D code model of RBMK-1500 reactor. At the Ignalina NPP void and fast power reactivity coefficients are measured on a regular basis and, based on the total reactor power, reactivity, control and protection system control rods positions and the main circulation circuit parameter changes during the experiments, the actual values of these reactivity coefficients are determined. Graphite temperature reactivity coefficient at the plant is determined by changing graphite cooling conditions in the reactor cavity. This type of transient is very unique and important from the gap between fuel channel and the graphite bricks model validation point of view. The measurement results, obtained during this transient, allowed to determine the thermal conductivity coefficient for this gap and to validate the graphite temperature reactivity feedback model. Reactor power reduction is a regular operation procedure during the entire lifetime of the reactor. In all cases it starts by either a scram or a power reduction signal activation by the reactor control and protection system or by an operator. The obtained calculation results demonstrate reasonable agreement with Ignalina NPP measured data. Behaviours of the separate MCC thermal-hydraulic parameters as well as physical processes are predicted reasonably well to the real processes, occurring in the primary circuit of RBMK-1500 reactor. Reasonable agreement of the measured and the calculated total reactor power change in time demonstrates the correct modelling of the neutronic processes taking place in RBMK- 1500 reactor core. And finally, the performed validation of RELAP5-3D model of Ignalina NPP RBMK-1500
NUMERICAL MULTIGROUP TRANSIENT ANALYSIS OF SLAB NUCLEAR REACTOR WITH THERMAL FEEDBACK
Directory of Open Access Journals (Sweden)
Filip Osuský
2016-12-01
Full Text Available The paper describes a new numerical code for multigroup transient analyses with thermal feedback. The code is developed at Institute of Nuclear and Physical Engineering. It is necessary to carefully investigate transient states of fast neutron reactors, due to recriticality issues after accident scenarios. The code solves numerical diffusion equation for 1D problem with possible neutron source incorporation. Crank-Nicholson numerical method is used for the transient states. The investigated cases are describing behavior of PWR fuel assembly inside of spent fuel pool and with the incorporated neutron source for better illustration of thermal feedback.
Techniques for Automated Performance Analysis
Energy Technology Data Exchange (ETDEWEB)
Marcus, Ryan C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-09-02
The performance of a particular HPC code depends on a multitude of variables, including compiler selection, optimization flags, OpenMP pool size, file system load, memory usage, MPI configuration, etc. As a result of this complexity, current predictive models have limited applicability, especially at scale. We present a formulation of scientific codes, nodes, and clusters that reduces complex performance analysis to well-known mathematical techniques. Building accurate predictive models and enhancing our understanding of scientific codes at scale is an important step towards exascale computing.
International Nuclear Information System (INIS)
Federici, G.; Raffray, A.R.; Chiocchio, S.; Esser, B.; Dietz, J.; Igitkhanov, Y.; Janeschitz, G.
1995-01-01
This paper presents the results of an analysis carried out to investigate the thermal response of ITER divertor plasma facing components (PFC's) clad with Be, W, and CFC, to high-recycling, high-power thermal transients (i.e. 10--30 MW/m 2 ) which are anticipated to last up to a few seconds. The armour erosion and surface melting are estimated for the different plasma facing materials (PFM's) together with the maximum heat flux to the coolant, and armour/heat-sink interface temperature. The analysis assumes that intense target evaporation will lead to high radiative power losses in the plasma in front of the target which self-protects the target. The cases analyzed clarify the influence of several key parameters such as the plasma heat flux to the target, the loss of the melt layer, the duration of the event, the thickness of the armour, and comparison is made with cases without vapor shielding. Finally, some implications for the performance and lifetime of divertor PFC's clad with different PFM's are discussed
Directory of Open Access Journals (Sweden)
Sivakumar Dakshinamurthy
2010-07-01
Full Text Available A non-identifier-based adaptive PI controller is designed using a gradient approach to improve the performance of a control system when device aging and environmental factors degrade the efficiency of the process. The design approach is based on the model reference adaptive control technique. The controller drives the difference (error between the process response and desired model output to zero asymptotically at a rate constrained by the desired characteristics of the model. The tuning rules are designed and justified for a non-linear process with dominant dynamics of second order. The advantage of this method for tracking and regulation compared to adaptive MIT control was validated in real time by conducting experiments on a laboratory air flow control system using the dSPACE interface in the SIMULINK software. The experimental results show that the process with adaptive PI controller has better dynamic performance and robustness than that with traditional adaptive MIT controller.
Sivakumar Dakshinamurthy
2010-01-01
A non-identifier-based adaptive PI controller is designed using a gradient approach to improve the performance of a control system when device aging and environmental factors degrade the efficiency of the process. The design approach is based on the model reference adaptive control technique. The controller drives the difference (error) between the process response and desired model output to zero asymptotically at a rate constrained by the desired characteristics of the model. The tuning r...
Steady-state and transient performance of HVDC link based 3-level ...
African Journals Online (AJOL)
Les systèmes de contrôle pour le redresseur et l'onduleur sont examinés. Les réseaux de transport sont équipés par des convertisseurs à trois niveaux à base de source de tension. Cette étude comprend l'analyse, le transit de puissance active ainsi que les performances dynamiques suite aux défauts AC externes. Enfin ...
Urquiza, Eugenio
This work presents a comprehensive thermal hydraulic analysis of a compact heat exchanger using offset strip fins. The thermal hydraulics analysis in this work is followed by a finite element analysis (FEA) to predict the mechanical stresses experienced by an intermediate heat exchanger (IHX) during steady-state operation and selected flow transients. In particular, the scenario analyzed involves a gas-to-liquid IHX operating between high pressure helium and liquid or molten salt. In order to estimate the stresses in compact heat exchangers a comprehensive thermal and hydraulic analysis is needed. Compact heat exchangers require very small flow channels and fins to achieve high heat transfer rates and thermal effectiveness. However, studying such small features computationally contributes little to the understanding of component level phenomena and requires prohibitive computational effort using computational fluid dynamics (CFD). To address this issue, the analysis developed here uses an effective porous media (EPM) approach; this greatly reduces the computation time and produces results with the appropriate resolution [1]. This EPM fluid dynamics and heat transfer computational code has been named the Compact Heat Exchanger Explicit Thermal and Hydraulics (CHEETAH) code. CHEETAH solves for the two-dimensional steady-state and transient temperature and flow distributions in the IHX including the complicating effects of temperature-dependent fluid thermo-physical properties. Temperature- and pressure-dependent fluid properties are evaluated by CHEETAH and the thermal effectiveness of the IHX is also calculated. Furthermore, the temperature distribution can then be imported into a finite element analysis (FEA) code for mechanical stress analysis using the EPM methods developed earlier by the University of California, Berkeley, for global and local stress analysis [2]. These simulation tools will also allow the heat exchanger design to be improved through an
PRONTO3D users` instructions: A transient dynamic code for nonlinear structural analysis
Energy Technology Data Exchange (ETDEWEB)
Attaway, S.W.; Mello, F.J.; Heinstein, M.W.; Swegle, J.W.; Ratner, J.A. [Sandia National Labs., Albuquerque, NM (United States); Zadoks, R.I. [Univ. of Texas, El Paso, TX (United States)
1998-06-01
This report provides an updated set of users` instructions for PRONTO3D. PRONTO3D is a three-dimensional, transient, solid dynamics code for analyzing large deformations of highly nonlinear materials subjected to extremely high strain rates. This Lagrangian finite element program uses an explicit time integration operator to integrate the equations of motion. Eight-node, uniform strain, hexahedral elements and four-node, quadrilateral, uniform strain shells are used in the finite element formulation. An adaptive time step control algorithm is used to improve stability and performance in plasticity problems. Hourglass distortions can be eliminated without disturbing the finite element solution using either the Flanagan-Belytschko hourglass control scheme or an assumed strain hourglass control scheme. All constitutive models in PRONTO3D are cast in an unrotated configuration defined using the rotation determined from the polar decomposition of the deformation gradient. A robust contact algorithm allows for the impact and interaction of deforming contact surfaces of quite general geometry. The Smooth Particle Hydrodynamics method has been embedded into PRONTO3D using the contact algorithm to couple it with the finite element method.
Transient analysis for lead-bismuth-cooled accelerator-driven system proposed by JAEA
International Nuclear Information System (INIS)
Sugawara, T.; Nishihara, K.; Tsujimoto, K.
2015-01-01
It is supposed that an Accelerator-driven System (ADS) is safer than conventional critical reactors since an ADS is driven by the external neutron source in the subcritical state. In this study, the transient analyses for the lead-bismuth cooled ADS proposed by JAEA were performed using the SIMMER-III and RELAP5/mod3.2 codes to investigate the possibility of core damage. In this research, 3 accidents: the protected loss of heat sink, the protected overcooling and the unprotected blockage accident were considered as typical ADS accidents. Through these calculations, it was confirmed that all calculation results, except for the protected loss of heat sink, fulfilled the no-damage criteria. In the protected loss of heat sink, the cladding tube temperature reached its melting temperature after 18-21 hours, although the calculation condition was very conservative. These results have led to requirements to design a safety system of the ADS to decrease the frequencies of accidents. (authors)
Transient Two-Dimensional Analysis of Side Load in Liquid Rocket Engine Nozzles
Wang, Ten-See
2004-01-01
Two-dimensional planar and axisymmetric numerical investigations on the nozzle start-up side load physics were performed. The objective of this study is to develop a computational methodology to identify nozzle side load physics using simplified two-dimensional geometries, in order to come up with a computational strategy to eventually predict the three-dimensional side loads. The computational methodology is based on a multidimensional, finite-volume, viscous, chemically reacting, unstructured-grid, and pressure-based computational fluid dynamics formulation, and a transient inlet condition based on an engine system modeling. The side load physics captured in the low aspect-ratio, two-dimensional planar nozzle include the Coanda effect, afterburning wave, and the associated lip free-shock oscillation. Results of parametric studies indicate that equivalence ratio, combustion and ramp rate affect the side load physics. The side load physics inferred in the high aspect-ratio, axisymmetric nozzle study include the afterburning wave; transition from free-shock to restricted-shock separation, reverting back to free-shock separation, and transforming to restricted-shock separation again; and lip restricted-shock oscillation. The Mach disk loci and wall pressure history studies reconfirm that combustion and the associated thermodynamic properties affect the formation and duration of the asymmetric flow.
Transient Three-Dimensional Analysis of Side Load in Liquid Rocket Engine Nozzles
Wang, Ten-See
2004-01-01
Three-dimensional numerical investigations on the nozzle start-up side load physics were performed. The objective of this study is to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, and pressure-based computational fluid dynamics formulation, and a simulated inlet condition based on a system calculation. Finite-rate chemistry was used throughout the study so that combustion effect is always included, and the effect of wall cooling on side load physics is studied. The side load physics captured include the afterburning wave, transition from free- shock to restricted-shock separation, and lip Lambda shock oscillation. With the adiabatic nozzle, free-shock separation reappears after the transition from free-shock separation to restricted-shock separation, and the subsequent flow pattern of the simultaneous free-shock and restricted-shock separations creates a very asymmetric Mach disk flow. With the cooled nozzle, the more symmetric restricted-shock separation persisted throughout the start-up transient after the transition, leading to an overall lower side load than that of the adiabatic nozzle. The tepee structures corresponding to the maximum side load were addressed.
International Nuclear Information System (INIS)
Mahaffy, J.; Boyack, B.E.; Steinke, R.G.
1998-05-01
The objective of this document is to ease the task of adding new system components to the Transient Reactor Analysis Code (TRAC) or altering old ones. Sufficient information is provided to permit replacement or modification of physical models and correlations. Within TRAC, information is passed at two levels. At the upper level, information is passed by system-wide and component-specific data modules at and above the level of component subroutines. At the lower level, information is passed through a combination of module-based data structures and argument lists. This document describes the basic mechanics involved in the flow of information within the code. The discussion of interfaces in the body of this document has been kept to a general level to highlight key considerations. The appendices cover instructions for obtaining a detailed list of variables used to communicate in each subprogram, definitions and locations of key variables, and proposed improvements to intercomponent interfaces that are not available in the first level of code modernization
Analysis of transient flow boiling: application of the method of characteristics
Energy Technology Data Exchange (ETDEWEB)
Hancox, W.T. (Atomic Energy of Canada, Ltd., Manitoba); Mathers, W.G.; Kawa, D.
1978-01-01
An analysis, based on the method of characteristics, was deveoped for transient flow boiling; particular emphasis was placed on blowdown from subcooled liquid conditions. The governing equations are quasilinear partial differential equations of the hyperbolic type which are derived from the conservation laws assuming one-dimensional homogeneous thermal equilibrium flow. Using a wave tracing procedure, the solution is advanced at grid points in the spacetime plane which are the intersections of the characteristic curves. The contribution of the present paper is in the application of this technique, used extensively in gas dynamics, to flow boiling dynamics. Special procedures were developed to handle discontinuities and complex wave interactions which arise owing to phase changes. Wave diagrams obtained using the wave tracing technique are discussed and compared with experimental data. The more complex forms of the one-dimensional homogeneous conservation laws and required constitutive equations, which incorporate departures from thermal equilibrium are also presented. The extension of the method of characteristics to these systems of equations is discussed.
Bhagat, Shaum; Bass, Johnnie; Qaddoumi, Ibrahim; Brennan, Rachel; Wilson, Matthew; Wu, Jianrong; Galindo, Carlos-Rodriguez; Paglialonga, Alessia; Tognola, Gabriella
2013-01-01
The aims of this study were to characterize and quantify time-frequency changes in transient-evoked otoacoustic emissions (TEOAEs) recorded in children diagnosed with retinoblastoma who were receiving carboplatin chemotherapy. A signal processing technique, the wavelet transform (WT), was used to analyze TEOAE waveforms in narrow-band frequency components. Ten children (aged 3-72 months) diagnosed with unilateral or bilateral retinoblastoma were enrolled in the study. TEOAEs were acquired from the children with linear sequences of 70 dB peak equivalent SPL clicks. After WT analysis, TEOAE energy, latency and normalized energy in the narrow-band frequency components were compared before and during carboplatin chemotherapy treatment (average dose 1693 mg/m2). On a group basis, no significant differences (p>0.05) in the TEOAE energy, latency or normalized energy before and after carboplatin treatment were observed. There were decreases in normalized energy on an individual basis in 10 out of 18 ears in the sample. Exposure to carboplatin chemotherapy did not cause significant changes in TEOAE energy, latency and normalized energy during treatment. However, long-term monitoring of hearing with measurements of TEOAEs is warranted, given the risks of delayed hearing loss in some children receiving carboplatin chemotherapy. Copyright © 2012 S. Karger AG, Basel.
Transient Thermal Analysis of 3-D Integrated Circuits Packages by the DGTD Method
Li, Ping
2017-03-11
Since accurate thermal analysis plays a critical role in the thermal design and management of the 3-D system-level integration, in this paper, a discontinuous Galerkin time-domain (DGTD) algorithm is proposed to achieve this purpose. Such as the parabolic partial differential equation (PDE), the transient thermal equation cannot be directly solved by the DGTD method. To address this issue, the heat flux, as an auxiliary variable, is introduced to reduce the Laplace operator to a divergence operator. The resulting PDE is hyperbolic, which can be further written into a conservative form. By properly choosing the definition of the numerical flux used for the information exchange between neighboring elements, the hyperbolic thermal PDE can be solved by the DGTD together with the auxiliary differential equation. The proposed algorithm is a kind of element-level domain decomposition method, which is suitable to deal with multiscale geometries in 3-D integrated systems. To verify the accuracy and robustness of the developed DGTD algorithm, several representative examples are benchmarked.
DEFF Research Database (Denmark)
Dalla Costa, Giuseppe; Madruga, Daniel González; De Chiffre, Leonardo
2016-01-01
the cooling phase, from 27 °C to 20 °C approximately. The length variation was measured by means of an inductive probe and the temperature with an RTD surface sensor. The frame of the system was composed by elements in Zerodur and Invar to minimize the thermal deformations of the structure. Uniform...... temperature in the part was assumed. The reference length at 20 °C (L20) was calculated with an a posteriori regression of the data from the complete cooling curve. A prediction of L20 was then performed exploiting partial segments of the curve. Several segments with different time spans and starting points...
Correlation analysis of transient heat transfer characteristics for air precooling aggregate
Guo, Chaohong; Zeng, Miao; Lu, Fei; Tang, Dawei; Guan, Wei; Li, Li; Fu, Tingwu
2017-04-01
In dam works, air precooling of aggregate is a common and effective method to avoid temperature cracks in concrete structure. In order to offer a reliable design theory for the air precooling process to avoid unreasonable energy consumption, the transient heat transfer characteristics of the aggregate are intensively analyzed. The combined structure of the aggregate and the interstitial space in the hopper is treated as a porous structure, and the space-average method is used to simulate the transient heat transfer process. Simulation results show that size of the hopper and the average air velocity in the cross section have great influence on the transient heat transfer process of the aggregate, while the porosity in the range of 0.4‒0.5 has little influence. Nomograms are abstracted from simulation results, and then correlations of the compared excess temperature are precisely fitted to predict the air precooling transient heat transfer process of the aggregate.
Analysis of start-up transient for a powertrain system with a nonlinear clutch damper
Li, Laihang; Singh, Rajendra
2015-10-01
The transient vibration phenomenon in a vehicle powertrain system during the start-up (or shut-down) process is studied with a focus on the nonlinear characteristics of a multi-staged clutch damper. First, a four-degree-of-freedom torsional model with multiple discontinuous nonlinearities under flywheel motion input is developed, and the powertrain transient event is validated with a vehicle start-up experiment. Second, the role of the nonlinear torsional path on the transient event is investigated in the time and time-frequency domains; interactions between the clutch damper and the transmission transients are estimated by using two metrics. Third, the harmonic balance method is applied to examine the nonlinear characteristics of clutch damper during a slowly varying non-stationary process in a simplified and validated single-degree-of-freedom powertrain system model. Finally, analytical formulas are successfully developed and verified to approximate the nonlinear amplification level for a rapidly varying process.
Analysis of reactivity transients and heat conduction in cylindrical fuel rod
International Nuclear Information System (INIS)
Botelho, D.A.
1984-01-01
The derivation of an algorithm for calculating the transient temperature distribution in a cylindrical fuel rod from the Paret computer code is presented. The finite diference method and the Crank-Nicholson method are used. (E.G.) [pt
Wavelet transform analysis of transient signals: the seismogram and the electrocardiogram
Energy Technology Data Exchange (ETDEWEB)
Anant, K.S.
1997-06-01
In this dissertation I quantitatively demonstrate how the wavelet transform can be an effective mathematical tool for the analysis of transient signals. The two key signal processing applications of the wavelet transform, namely feature identification and representation (i.e., compression), are shown by solving important problems involving the seismogram and the electrocardiogram. The seismic feature identification problem involved locating in time the P and S phase arrivals. Locating these arrivals accurately (particularly the S phase) has been a constant issue in seismic signal processing. In Chapter 3, I show that the wavelet transform can be used to locate both the P as well as the S phase using only information from single station three-component seismograms. This is accomplished by using the basis function (wave-let) of the wavelet transform as a matching filter and by processing information across scales of the wavelet domain decomposition. The `pick` time results are quite promising as compared to analyst picks. The representation application involved the compression of the electrocardiogram which is a recording of the electrical activity of the heart. Compression of the electrocardiogram is an important problem in biomedical signal processing due to transmission and storage limitations. In Chapter 4, I develop an electrocardiogram compression method that applies vector quantization to the wavelet transform coefficients. The best compression results were obtained by using orthogonal wavelets, due to their ability to represent a signal efficiently. Throughout this thesis the importance of choosing wavelets based on the problem at hand is stressed. In Chapter 5, I introduce a wavelet design method that uses linear prediction in order to design wavelets that are geared to the signal or feature being analyzed. The use of these designed wavelets in a test feature identification application led to positive results. The methods developed in this thesis; the
International Nuclear Information System (INIS)
Rhee, B.W.; Park, J.H.
2006-01-01
To form a licensing bases for the new methodology of fuel channel safety analysis code system for CANDU-6, a CATHENA model for the post-blowdown fuel channel analysis has been developed, and tested for a high temperature thermal-chemical experiment CS28-1. Pursuant to the objective of this study the current study has focused on understanding the involved phenomena, their interrelations, and how to maintain good accuracy in the temperature and H 2 generation rate prediction without losing the important physics of the involved phenomena. The transient simulation results for the FESs of three fuel rings and the pressure tube were quite good as proven in the Figs. 3∼6. However this raises a question how the transient FES and pressure tube temperature can be predicted so well in spite of the insufficient justification of using the 'non-participating medium assumption' for the CO 2 gas gap. Through this study, it was found that the radiation heat transfer model of CATHENA among FES of three rings and the pressure tube as well as the exothermic metal-water reaction model based on the Urbanic-Heidrick correlation are quite accurate and sound. Also it was found that an accurate prediction of the initial condition of the experiment is very important for the accurate prediction of the whole transient as it serves as the starting point of the transient. (author)
International Nuclear Information System (INIS)
Scheuerer, Martina; Weis, Johannes
2012-01-01
Highlights: ► Pressurized thermal shocks are important phenomena for plant life extension and aging. ► The thermal-hydraulics of PTS have been studied experimentally and numerically. ► In the Large Scale Test Facility a loss of coolant accident was investigated. ► CFD software is validated to simulate the buoyancy driven flow after ECC injection. - Abstract: Within the framework of the European Nuclear Reactor Integrated Simulation Project (NURISP), computational fluid dynamics (CFD) software is validated for the simulation of the thermo-hydraulics of pressurized thermal shocks. A proposed validation experiment is the test series performed within the OECD ROSA V project in the Large Scale Test Facility (LSTF). The LSTF is a 1:48 volume-scaled model of a four-loop Westinghouse pressurized water reactor (PWR). ROSA V Test 1-1 investigates temperature stratification under natural circulation conditions. This paper describes calculations which were performed with the ANSYS CFD software for emergency core cooling injection into one loop at single-phase flow conditions. Following the OECD/NEA CFD Best Practice Guidelines (Mahaffy, 2007) the influence of grid resolution, discretisation schemes, and turbulence models (shear stress transport and Reynolds stress model) on the mixing in the cold leg were investigated. A half-model was used for these simulations. The transient calculations were started from a steady-state solution at natural circulation conditions. The final calculations were obtained in a complete model of the downcomer. The results are in good agreement with data.
International Nuclear Information System (INIS)
Knudsen, P.
1979-11-01
Reports from the meetings at Petten (Nov. - Dec. 1978), Portland (April-May 1979) and Arles (May 1979) have been reviewed together with various reports related to the Three-Mile Island accident. The reports were selected to cover transients in normal operation (power ramps, load-following) as well as off-normal transients. (author)
Scalable Performance Measurement and Analysis
Energy Technology Data Exchange (ETDEWEB)
Gamblin, Todd [Univ. of North Carolina, Chapel Hill, NC (United States)
2009-01-01
Concurrency levels in large-scale, distributed-memory supercomputers are rising exponentially. Modern machines may contain 100,000 or more microprocessor cores, and the largest of these, IBM's Blue Gene/L, contains over 200,000 cores. Future systems are expected to support millions of concurrent tasks. In this dissertation, we focus on efficient techniques for measuring and analyzing the performance of applications running on very large parallel machines. Tuning the performance of large-scale applications can be a subtle and time-consuming task because application developers must measure and interpret data from many independent processes. While the volume of the raw data scales linearly with the number of tasks in the running system, the number of tasks is growing exponentially, and data for even small systems quickly becomes unmanageable. Transporting performance data from so many processes over a network can perturb application performance and make measurements inaccurate, and storing such data would require a prohibitive amount of space. Moreover, even if it were stored, analyzing the data would be extremely time-consuming. In this dissertation, we present novel methods for reducing performance data volume. The first draws on multi-scale wavelet techniques from signal processing to compress systemwide, time-varying load-balance data. The second uses statistical sampling to select a small subset of running processes to generate low-volume traces. A third approach combines sampling and wavelet compression to stratify performance data adaptively at run-time and to reduce further the cost of sampled tracing. We have integrated these approaches into Libra, a toolset for scalable load-balance analysis. We present Libra and show how it can be used to analyze data from large scientific applications scalably.
Directory of Open Access Journals (Sweden)
Fifteen Aprila Fajrin
2018-02-01
Full Text Available Ginger had been reported to ameliorate painful diabetic neuropathy (PDN in an animal model. Gingerol and shogaol were active compounds of ginger that potentially act on transient receptor potential cation channel subfamily V member 1 (TRPV1, a key receptor in PDN. This study aims to predict the binding of gingerol and shogaol to TRPV1 using an in silico model. The ligands of the docking study were 3 chemical compounds of each gingerol and shogaol, i.e. 6-shogaol, 8-shogaol, 10-shogaol, 6-gingerol, 8 gingerol and 10-gingerol. Capsaicin, a TRPV1 agonist, was used as a native ligand. The TRPV1 structure was taken from Protein Data Bank (ID 3J9J. The docking analysis was performed using Autodock Vina. The result showed that among the ginger active compounds, 6-shogaol had the strongest binding energy (-7.10 kcal/mol to TRPV1. The 6-shogaol lacked the potential hydrogen bond to Ile265 of TRPV1 protein, which capsacin had. However, it's binding energy towards TRPV1 was not significantly different compared to capsaicin. Therefore, 6-shogaol had potential to be developed as a treatment for PDN.
International Nuclear Information System (INIS)
Maheshwari, B.K.; Truman, K.Z.; El Naggar, M.H.; Gould, P.L.
2004-01-01
The effects of material nonlinearity of soil and separation at the soil-pile interface on the dynamic behaviour of a single pile and pile groups are investigated. An advanced plasticity-based soil model, hierarchical single surface (HiSS), is incorporated in the finite element formulation. To simulate radiation effects, proper boundary conditions are used. The model and algorithm are verified with analytical results that are available for elastic and elastoplastic soil models. Analyses are performed for seismic excitation and for the load applied on the pile cap. For seismic analysis, both harmonic and transient excitations are considered. For loading on the pile cap, dynamic stiffness of the soil-pile system is derived and the effect of nonlinearity is investigated. The effects of spacing between piles are investigated, and it was found that the effect of soil nonlinearity on the seismic response is very much dependent on the frequency of excitation. For the loading on a pile cap, the nonlinearity increases the response for most of the frequencies of excitation while decreasing the dynamic stiffness of the soil-pile system. (author)
DEFF Research Database (Denmark)
Callahan, Alfred; Amarenco, Pierre; Goldstein, Larry B
2011-01-01
To perform a secondary analysis of the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL) trial, which tested the effect of treatment with atorvastatin in reducing stroke in subjects with a recent stroke or transient ischemic attack, to explore the effects of treatment...
Safety analysis of loss of flow transients in a typical research reactor by RELAP5/MOD3.3
International Nuclear Information System (INIS)
Di Maro, B.; Pierro, F.; Adorni, M.; Bousbia Salah, A.; D'Auria, F.
2003-01-01
The main aim of the following study is to assess the RELAP5/MOD3.3 code capability in simulating transient dynamic behaviour in nuclear research reactors. For this purpose typical loss of flow transient in a representative MTR (Metal Test Reactor) fuel type Research Reactor is considered. The transient herein considered is a sudden pump trip followed by the opening of a safety valve in order to allow passive decay heat removal by natural convection. During such transient the coolant flow decay, originally downward, leads to a flow reversal and the cooling process of the core passes from forced, mixed and finally to natural circulation. This fact makes it suitable for evaluating the new features of RELAP5 to simulate such specific operating conditions. The instantaneous reactor power is derived through the point kinetic calculation, both protected and unprotected cases are considered (with and without Scram). The results obtained from this analysis were also compared with previous results obtained by old version RELAP5/MOD2 code. (author)
Energy Technology Data Exchange (ETDEWEB)
Chien, T.H.; Domanus, H.M.; Sha, W.T.
1993-02-01
The COMMIX-PPC computer pregrain is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex Industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional equations of conservation of mass, momentum, and energy on the tube stile and the proper accounting for the thermal interaction between shell and tube side through the porous-medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient. Three-dimensional analysis of fluid flow with heat transfer tn a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification, it can be used to analyze processes in any heat exchanger or other single-phase engineering applications. Volume I (Equations and Numerics) of this report describes in detail the basic equations, formulation, solution procedures, and models for a phenomena. Volume II (User`s Guide and Manual) contains the input instruction, flow charts, sample problems, and descriptions of available options and boundary conditions.
Energy Technology Data Exchange (ETDEWEB)
Chien, T.H.; Domanus, H.M.; Sha, W.T.
1993-02-01
The COMMIX-PPC computer program is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional conservation of mass. momentum, and energy equations on the tube side, and the proper accounting for the thermal interaction between shell and tube side through the porous medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient three-dimensional analysis of fluid flow with heat transfer in a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification. it can be used to analyze processes in any heat exchanger or other single-phase engineering applications.
Anticipated Transient Without SCRAM(ATWS) analysis using the RETRAN code
International Nuclear Information System (INIS)
Youn, Bum soo; Lee, Jong beom; Song, Dong soo; Ha, Sang jun
2014-01-01
The purpose of this study is to evaluate the Anticipated Transient Without Scram(ATWS) Loss of Load(LOL) and Loss of Normal Feedwater(LOFW) events for the OPR1000 reactor. The analysis calculates the peak RCS and secondary system pressure for the LOL and LOFW ATWS events. The main product of this study is the ATWS evaluation of the OPR1000 reactor LOL and LOFW events. The results include a sequence of events and plots of key output parameters.. This study includes results of Loss of Load and Loss of Feedwater ATWS. The LOL case results in a faster reactor trip than the LOFW since the LOFW does not have the turbine trip at time zero. In addition the LOFW event has the SBCS available and as secondary pressure increase, the steam releases from the SBCS valves provide extra cooling to the secondary system, which also cools the primary system. This additional cooling also delays the DSS trip. For the LOFW event, both the turbine and SBCS are providing additional cooling, hence the primary and secondary system heatups are slower and lower. Thus the RCS and steam generator pressure are higher for the LOL event than the LOFW event. The LOL also has a slower decrease in SG water level than the LOFW event. This is due to loss of condenser vacuum that trips and isolates the turbine and renders the SBCS unavailable for the LOL event. Hence the secondary cooling for the LOL event is due to the steam releases from the MSSVs; whereas the LOFW turbine remains online until a DTT occurs on the DSS. Also the SBCS is available because the condenser is available
Pressure transient analysis in single and two-phase water by finite difference methods
International Nuclear Information System (INIS)
Berry, G.F.; Daley, J.G.
1977-01-01
An important consideration in the design of LMFBR steam generators is the possibility of leakage from a steam generator water tube. The ensuing sodium/water reaction will be largely controlled by the amount of water available at the leak site, thus analysis methods treating this event must have the capability of accurately modeling pressure transients through all states of water occurring in a steam generator, whether single or two-phase. The equation systems of the present model consist of the conservation equations together with an equation of state for one-dimensional homogeneous flow. These equations are then solved using finite difference techniques with phase considerations and non-equilibrium effects being treated through the equation of state. The basis for water property computation is Keenan's 'fundamental equation of state' which is applicable to single-phase water at pressures less than 1000 bars and temperatures less than 1300 0 C. This provides formulations allowing computation of any water property to any desired precision. Two-phase properties are constructed from values on the saturation line. The use of formulations permits the direct calculation of any thermodynamic property (or property derivative) to great precision while requiring very little computer storage, but does involve considerable computation time. For this reason an optional calculation scheme based on the method of 'transfinite interpolation' is included to give rapid computation in selected regions with decreased precision. The conservation equations were solved using the second order Lax-Wendroff scheme which includes wall friction, allows the formation of shocks and locally supersonic flow. Computational boundary conditions were found from a method-of-characteristics solution at the reservoir and receiver ends. The local characteristics were used to interpolate data from inside the pipe to the boundary
Anticipated Transient Without SCRAM(ATWS) analysis using the RETRAN code
Energy Technology Data Exchange (ETDEWEB)
Youn, Bum soo; Lee, Jong beom; Song, Dong soo; Ha, Sang jun [KHNP-CRI, Daejeon (Korea, Republic of)
2014-10-15
The purpose of this study is to evaluate the Anticipated Transient Without Scram(ATWS) Loss of Load(LOL) and Loss of Normal Feedwater(LOFW) events for the OPR1000 reactor. The analysis calculates the peak RCS and secondary system pressure for the LOL and LOFW ATWS events. The main product of this study is the ATWS evaluation of the OPR1000 reactor LOL and LOFW events. The results include a sequence of events and plots of key output parameters.. This study includes results of Loss of Load and Loss of Feedwater ATWS. The LOL case results in a faster reactor trip than the LOFW since the LOFW does not have the turbine trip at time zero. In addition the LOFW event has the SBCS available and as secondary pressure increase, the steam releases from the SBCS valves provide extra cooling to the secondary system, which also cools the primary system. This additional cooling also delays the DSS trip. For the LOFW event, both the turbine and SBCS are providing additional cooling, hence the primary and secondary system heatups are slower and lower. Thus the RCS and steam generator pressure are higher for the LOL event than the LOFW event. The LOL also has a slower decrease in SG water level than the LOFW event. This is due to loss of condenser vacuum that trips and isolates the turbine and renders the SBCS unavailable for the LOL event. Hence the secondary cooling for the LOL event is due to the steam releases from the MSSVs; whereas the LOFW turbine remains online until a DTT occurs on the DSS. Also the SBCS is available because the condenser is available.
International Nuclear Information System (INIS)
Leavell, W.H.; Mullens, J.A.
1981-01-01
A computational algorithm has been developed to measure transient, phase-interface velocity in two-phase, steam-water systems. The algorithm will be used to measure the transient velocity of steam-water mixture during simulated PWR reflood experiments. By utilizing signals produced by two, spatially separated impedance probes immersed in a two-phase mixture, the algorithm computes the average transit time of mixture fluctuations moving between the two probes. This transit time is computed by first, measuring the phase shift between the two probe signals after transformation to the frequency domain and then computing the phase shift slope by a weighted least-squares fitting technique. Our algorithm, which has been tested with both simulated and real data, is able to accurately track velocity transients as fast as 4 m/s/s
Powell, W. B.
1973-01-01
A methodology is described for the analysis of a transient temperature measurement made in a flat or curved plate subjected to convective heat transfer, such that the surface heat flux, the hot-gas temperture, and the gas heat transfer coefficient can be determined. It is shown that if the transient temperature measurement is made at a particular point located nearly midway in the thickness of the plate there is an important simplification in the data analysis process, in that the factor relating the surface heat flux to the measured rate of rise of temperature becomes invariant for a Fourier Number above 0.60 and for all values of the Biot Number. Parameters are derived, tabulated, and plotted which enable straightforward determination of the surface heat flux, the hot-gas temperature, of the plate, the rate of rise of temperature, the plate thickness and curvature, and the mean thermal properties of the plate material at the test temperature.
International Nuclear Information System (INIS)
Reddy, B.S.; Sharan, A.M.
1985-01-01
The heat transfer process in some of the metallurgical processes is quite involved; for example, during the cooling of castings or heating of ingots before forging. These castings or ingots can be very complicated shapes. Therefore, the solution of heat transfer problems by exact methods is not possible. In such situations, the heat transfer process is studied either by finite difference or finite element method. The heat transfer process in this problem involves all the three modes of heat transfer which are: the conduction, convection and radiation. In this paper, the equations for the heat transfer process of a solid subjected to nonlinear boundary conditions using the finite element analysis have been derived. Then, these equations are solved using the Gauss-Seidel iteration technique. (author)
Comparison of simulators for variable-speed wind turbine transient analysis
DEFF Research Database (Denmark)
Seman, S.; Iov, Florin; Niiranen, J.
2006-01-01
This paper presents a comparison of three variable-speed wind turbine simulators used for a 2 MW wind turbine short-term transient behaviour study during a symmetrical network disturbance. The simulator with doubly fed induction generator (DFIG) analytical model, the simulator with a finite element...... method (FEM) DFIG model and the wind turbine simulator with an analytical model of DFIG are compared. The comparison of the simulation results shows the influence of the different modelling approaches on the short-term transient simulation accuracy...
Fishman, Keera N; Ashbaugh, Andrea R; Lanctôt, Krista L; Cayley, Megan L; Herrmann, Nathan; Murray, Brian J; Sicard, Michelle; Lien, Karen; Sahlas, Demetrios J; Swartz, Richard H
2017-09-15
This study examined the relationship between apathy and cognition in patients with cerebrovascular disease. Apathy may result from damage to frontal subcortical circuits causing dysexecutive syndromes, but apathy is also related to depression. We assessed the ability of apathy to predict phonemic fluency and semantic fluency performance after controlling for depressive symptoms in 282 individuals with stroke and/or transient ischemic attack. Participants (N = 282) completed the Phonemic Fluency Test, Semantic Fluency Test, Center for Epidemiologic Studies Depression Scale, and Apathy Evaluation Scale. A cross-sectional correlational design was utilized. Using hierarchical linear regressions, apathy scores significantly predicted semantic fluency performance (β = -.159, p = .020), but not phonemic fluency performance (β = -.112, p = .129) after scaling scores by age and years of education and controlling for depressive symptoms. Depressive symptoms entered into the first step of both hierarchical linear regressions did not predict semantic fluency (β = -.035, p = .554) or phonemic fluency (β = -.081, p = .173). Apathy and depressive symptoms were moderately correlated, r(280) = .58, p < .001. The results of this study are consistent with research supporting a differentiation between phonemic and semantic fluency tasks, whereby phonemic fluency tasks primarily involve frontal regions, and semantic fluency tasks involve recruitment of more extended networks. The results also highlight a distinction between apathy and depressive symptoms and suggest that apathy may be a more reliable predictor of cognitive deficits than measures of mood in individuals with cerebrovascular disease. Apathy may also be more related to cognition due to overlapping motivational and cognitive frontal subcortical circuitry. Future research should explore whether treatments for apathy could be a novel target for improving cognitive outcomes after stroke.
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
Cynod: A Neutronics Code for Pebble Bed Modular Reactor Coupled Transient Analysis
Energy Technology Data Exchange (ETDEWEB)
Hikaru Hiruta; Abderrafi M. Ougouag; Hans D. Gougar; Javier Ortensi
2008-09-01
Green’s function method. The performance of the new code is demonstrated by applying it to a delayed supercritical problem and a to the OECD PBMR400 rod ejection benchmark problem. The latter makes use of the coupled CYNOD-THERMIX/KONVEK codes. A final improvement to the code is the subject of a companion paper: a heterogeneous TRISO fuel particle model was devised and incorporated into the code and used to provide an enhanced Doppler treatment. The new code is currently being coupled to the RELAP5-3D code for thermal-hydraulics. The full length paper will include extensive summaries of the equations and algorithm, descriptions of the sample and benchmark problems and details of the results. It is shown, in inter-code comparisons, that the new code correctly predicts the transient behaviors of the test problems.
A development of containment performance analysis methodology using GOTHIC code
International Nuclear Information System (INIS)
Lee, B. C.; Yoon, J. I.; Byun, C. S.; Lee, J. Y.; Lee, J. Y.
2003-01-01
In a circumstance that well-established containment pressure/temperature analysis code, CONTEMPT-LT treats the reactor containment as a single volume, this study introduces, as an alternative, the GOTHIC code for an usage on multi-compartmental containment performance analysis. With a developed GOTHIC methodology, its applicability is verified for containment performance analysis for Korean Nuclear Unit 1. The GOTHIC model for this plant is simply composed of 3 compartments including the reactor containment and RWST. In addition, the containment spray system and containment recirculation system are simulated. As a result of GOTHIC calculation, under the same assumptions and conditions as those in CONTEMPT-LT, the GOTHIC prediction shows a very good result; pressure and temperature transients including their peaks are nearly the same. It can be concluded that the GOTHIC could provide reasonable containment pressure and temperature responses if considering the inherent conservatism in CONTEMPT-LT code
A development of containment performance analysis methodology using GOTHIC code
Energy Technology Data Exchange (ETDEWEB)
Lee, B. C.; Yoon, J. I. [Future and Challenge Company, Seoul (Korea, Republic of); Byun, C. S.; Lee, J. Y. [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Lee, J. Y. [Seoul National University, Seoul (Korea, Republic of)
2003-10-01
In a circumstance that well-established containment pressure/temperature analysis code, CONTEMPT-LT treats the reactor containment as a single volume, this study introduces, as an alternative, the GOTHIC code for an usage on multi-compartmental containment performance analysis. With a developed GOTHIC methodology, its applicability is verified for containment performance analysis for Korean Nuclear Unit 1. The GOTHIC model for this plant is simply composed of 3 compartments including the reactor containment and RWST. In addition, the containment spray system and containment recirculation system are simulated. As a result of GOTHIC calculation, under the same assumptions and conditions as those in CONTEMPT-LT, the GOTHIC prediction shows a very good result; pressure and temperature transients including their peaks are nearly the same. It can be concluded that the GOTHIC could provide reasonable containment pressure and temperature responses if considering the inherent conservatism in CONTEMPT-LT code.
Energy Technology Data Exchange (ETDEWEB)
Gorham, P. W. [Univ. of Hawaii, Manoa, HI (United States); Allison, P. [Univ. of Hawaii, Manoa, HI (United States); Barwick, S. W. [Univ. of California, Irvine, CA (United States); Beatty, J. J. [The Ohio State Univ., Columbus, OH (United States); Besson, D. Z. [Univ. of Kansas, Lawrence, KS (United States); Binns, W. R. [Washington Univ., St. Louis, MO (United States); Chen, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Chen, P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); NASA Goddard Space Flight Center, Greenbelt, MD (United States); Clem, J. M. [Univ. of Delaware, Newark, DE (United States); Connolly, A. [Univ. College London, London (United Kingdom); Dowkontt, P. F. [Washington Univ., St. Louis, MO (United States); DuVernois, M. A. [Univ. of Minnesota, Minneapolis, MN (United States); Field, R. C. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Goldstein, D. [Univ. of California, Irvine, CA (United States); Goodhue, A. [Univ. of California, Los Angeles, CA (United States); Hast, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hebert, C. L. [Univ. of Hawaii, Manoa, HI (United States); Hoover, S. [Univ. of California, Los Angeles, CA (United States); Israel, M. H. [Washington Univ., St. Louis, MO (United States); Learned, J. G. [Univ. of Hawaii, Manoa, HI (United States). et al.
2009-05-23
In this article, we present a comprehensive report on the experimental details of the Antarctic Impulsive Transient Antenna (ANITA) long-duration balloon payload, including the design philosophy and realization, physics simulations, performance of the instrument during its first Antarctic flight completed in January of 2007, and expectations for the limiting neutrino detection sensitivity.
Transient isotachophoresis in carrier ampholyte-based capillary electrophoresis for protein analysis
Czech Academy of Sciences Publication Activity Database
Busnel, J. M.; Descroix, S.; Godfrin, D.; Hennion, M. C.; Kašička, Václav; Peltre, G.
2006-01-01
Roč. 27, č. 18 (2006), s. 3591-3598 ISSN 0173-0835 Institutional research plan: CEZ:AV0Z40550506 Keywords : carrier ampholyte-based capillary electrophoresis * transient isotachophoresis * proteins Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.101, year: 2006
Stochastic resonance of ensemble neurons for transient spike trains: Wavelet analysis
International Nuclear Information System (INIS)
Hasegawa, Hideo
2002-01-01
By using the wavelet transformation (WT), I have analyzed the response of an ensemble of N (=1, 10, 100, and 500) Hodgkin-Huxley neurons to transient M-pulse spike trains (M=1 to 3) with independent Gaussian noises. The cross correlation between the input and output signals is expressed in terms of the WT expansion coefficients. The signal-to-noise ratio (SNR) is evaluated by using the denoising method within the WT, by which the noise contribution is extracted from the output signals. Although the response of a single (N=1) neuron to subthreshold transient signals with noises is quite unreliable, the transmission fidelity assessed by the cross correlation and SNR is shown to be much improved by increasing the value of N: a population of neurons plays an indispensable role in the stochastic resonance (SR) for transient spike inputs. It is also shown that in a large-scale ensemble, the transmission fidelity for suprathreshold transient spikes is not significantly degraded by a weak noise which is responsible to SR for subthreshold inputs
Escherichia coli is a leading cause of bacterial mastitis in dairy cattle. Typically this infection is transient in nature, causing an infection that lasts 2-3 days. However, in a minority of cases, E. coli has been shown to cause a persistent intramammary infection. The mechanisms that allow for...
Transient and steady state photoelectronic analysis in TlInSe{sub 2} crystals
Energy Technology Data Exchange (ETDEWEB)
Qasrawi, A.F., E-mail: aqasrawi@atilim.edu.tr [Group of Physics, Faculty of Engineering, Atilim University, 06836 Ankara (Turkey); Department of Physics, Arab-American University, Jenin, West Bank, Palestine (Country Unknown); Gasanly, N.M. [Department of Physics, Middle East Technical University, 06531 Ankara (Turkey)
2011-08-15
Highlights: {yields} The steady state and time dependent photoconductivity kinetics of the TlInSe{sub 2} crystals are investigated in the temperature region of 100-350 K. {yields} The photocurrent of the sample exhibited linear, sublinear, and supralinear recombination mechanisms, at, above and below 160 K, respectively. {yields} Steady state photoconductivity revealed two recombination centres located at 234 and 94 meV. {yields} The transient photoconductivity is limited by a trapping center located at 173 meV. {yields} The capture coefficient of the trap for holes was determined as 3.11 x 10{sup -22} cm{sup -2}. -- Abstract: The temperature and illumination effects on the transient and steady state photoconductivities of TlInSe{sub 2} crystals have been studied. Namely, two recombination centres located at 234 and at 94 meV and one trap center located at 173 meV were determined from the temperature-dependent steady state and transient photoconductivities, respectively. The illumination dependence of photoconductivity indicated the domination of sublinear and supralinear recombination mechanisms above and below 160 K, respectively. The change in the recombination mechanism is attributed to the exchange of roles between the linear recombination at the surface and trapping centres in the crystal, which become dominant as temperature decreases. The transient photoconductivity measurement allowed the determination of the capture coefficient of traps for holes as 3.11 x 10{sup -22} cm{sup -2}.
Simulation and analysis of transient over voltages due to capacitor banks switching
International Nuclear Information System (INIS)
Jadid, Sh.; Yazdanpanah, D.
2002-01-01
The switching of any capacitor bank produces over voltages. Transient overvoltage will always occur in the switching device, the switching of shunt capacitor bank has become the most common source of transient voltage on power systems. Transient over voltages due to switching the capacitor bands hurt not only to the capacitor banks, but also to other equipment, such as circuit breakers and transformers. Several methods are available for reducing energising transients. These devices include pre-insertion resistors, pre-insertion inductors,synchronous closing, and MOV arresters. However, not all are practical or economical. The other important problem is existence of capacitor banks in presence of harmonics.Capacitors do not produce harmonics;however,the addition of capacitors to the electrical system will change the frequency response characteristics of the system will change the frequency response characteristics of the system, and in some cases can result in magnification of the voltage and current distortion in the system. In other word in presence of harmonic-producing loads,the capacitors used for power factor correction,may cause parallel resonance with the system inductance, so they increase the total harmonic distortion of voltage and current waveforms
Analysis of electromagnetic and electromechanical power system transients with dynamic phasors
Henschel, Sebastian
1999-11-01
Over the last 50 years, digital simulation of electric power systems has become an integral part for planning, design and operation in the power industry. The number of possibilities with respect to the purpose of a study, investigated frequency ranges, etc. with, in the past, limited computer resources has resulted in a spectrum of simulation tools, designed to handle very specific tasks. Simplifying assumptions were often needed to facilitate such a simulation. Recent system failures and power outages, partly due to increasingly sensitive operating conditions, have created a demand for more comprehensive studies and more general simulation tools that overcome former limitations. With regards to time-domain simulation, this demand has led to combining the areas of transient, mid-term and long-term stability. Confronted with concerns about black start and system restoration due to a global trend to a deregulated power market, several power utilities suggested to also include the area of electromagnetic transients. However, previously made assumptions as well as technical limitations complicate the implementation of this idea: Stability programs are based on the assumption that power transfer takes place at system frequency and are therefore unable to represent rapid electromagnetic transients. Electromagnetic transients programs, on the other hand, are very accurate but use too small simulation step sizes for an efficient simulation of electromechanical transients. A new method for simulating both types of transient phenomena with complex signals and dynamic phasors is presented in this thesis. Whereas in previous work three-phase transformations had been used to accomplish this task, this new method is applied directly in the phase-domain and not restricted to balanced three-phase systems. Several numerical aspects such as an appropriate variable representation, integration method and a control mechanism for variable simulation step sizes have been addressed
Bravo-Imaz, Inaki; Davari Ardakani, Hossein; Liu, Zongchang; García-Arribas, Alfredo; Arnaiz, Aitor; Lee, Jay
2017-09-01
This paper focuses on analyzing motor current signature for fault diagnosis of gearboxes operating under transient speed regimes. Two different strategies are evaluated, extensively tested and compared to analyze the motor current signature in order to implement a condition monitoring system for gearboxes in industrial machinery. A specially designed test bench is used, thoroughly monitored to fully characterize the experiments, in which gears in different health status are tested. The measured signals are analyzed using discrete wavelet decomposition, in different decomposition levels using a range of mother wavelets. Moreover, a dual-level time synchronous averaging analysis is performed on the same signal to compare the performance of the two methods. From both analyses, the relevant features of the signals are extracted and cataloged using a self-organizing map, which allows for an easy detection and classification of the diverse health states of the gears. The results demonstrate the effectiveness of both methods for diagnosing gearbox faults. A slightly better performance was observed for dual-level time synchronous averaging method. Based on the obtained results, the proposed methods can used as effective and reliable condition monitoring procedures for gearbox condition monitoring using only motor current signature.
Rodriguez Pretelin (1), Abelardo; Nowak (1), Wolfgang
2017-04-01
Well head protection areas (WHPAs) are frequently used as safety measures for drinking water wells, preventing them from being polluted by restricting land use activities in their proximities. Two sources of uncertainty are involved during delineation: 1) uncertainty in aquifer parameters and 2) time-varying groundwater flow scenarios and their own inherent uncertainties. The former has been studied by Enzenhoefer et al (2012 [1] and 2014 [2]) as probabilistic risk version of WHPA delineation. The latter is frequently neglected and replaced by steady-state assumptions; thereby ignoring time-variant flow conditions triggered either by anthropogenic causes or climatic conditions. In this study we analyze the influence of transient flow considerations in WHPA delineation, following annual seasonality behavior; with transiency represented by four transient conditions: (I) regional groundwater flow direction, (II) strength of the regional hydraulic gradient, (III) natural recharge to the groundwater and (IV) pumping rate. Addressing WHPA delineation in transient flow scenarios is computationally expensive. Thus, we develop an efficient method using a dynamic superposition of steady-state flow solutions coupled with a reversed formulation of advective-dispersive transport based on a Lagrangian particle tracking with continuous injection. This analysis results in a time-frequency map of pixel-wise membership to the well catchment. Additional to transient flow conditions, we recognize two sources of uncertainty, inexact knowledge of transient drivers and parameters. The uncertainties are accommodated through Monte Carlo simulation. With the help of a global sensitivity analysis, we investigate the impact of transiency in WHPA solutions. In particular, we evaluate: (1) Among all considered transients, which ones are the most influential. (2) How influential in WHPA delineation is the transience-related uncertainty compared to aquifer parameter uncertainty. Literature [1] R
DEFF Research Database (Denmark)
Rolle, Massimo; Kitanidis, Peter
, a transient flux-related dilution index that allows quantifying the evolution of solute dilution at a given position along the main flow direction. For the different solute transport scenarios we obtained dilution breakthrough curves that complement and add important information to traditional solute......Compound-specific diffusivities significantly impact solute transport and mixing at different scales. Although diffusive processes occur at the small pore scale, their effects propagate and remain important at larger macroscopic scales [1]. In this pore-scale modeling study in saturated porous...... media we show that compound-specific effects are important not only at steady-state and for the lateral displacement of solutes with different diffusivities but also for transient transport and solute breakthrough [2]. We performed flow and transport simulations in two-dimensional pore-scale domains...
International Nuclear Information System (INIS)
Miles, K.J.; Hill, D.J.
1986-01-01
The DEFORM-4 module is the segment of the SAS4A Accident Analysis Code System that calculates the fuel pin characterization in response to a steady state irradiation history, thereby providing the initial conditions for the transient calculation. The various phenomena considered include fuel porosity migration, fission gas bubble induced swelling, fuel cracking and healing, fission gas release, cladding swelling, and the thermal-mechanical state of the fuel and cladding. In the transient state, the module continues the thermal-mechanical response calculation, including fuel melting and central cavity pressurization, until cladding failure is predicted and one of the failed fuel modules is initiated. Comparisons with experimental data have demonstrated the validity of the modeling approach
International Nuclear Information System (INIS)
Peng Muzhang; Zhang Quan; Wang Guoli; Zhang Yuman
1988-01-01
TISKTH-3 is a coupled neutronics/thermal-hydraulics code for the transient analysis. A 3-dimensional neutron kinetics equation solved by the Nodal Green's Function Method is used for the neutronics model of the code. A homogeneous equilibrium model with a complete boiling curve and two numerical solutions of the implicit and explicit scheme is used for the thermal-hydraulics model of the code. A 2-dimensional heat conduction equation with variable conductivity solved by the method of weighted residuals is used for the fuel rod heat transfer model of the code. TISKTH-3 is able to analyze the fast transient process and complicate accident situations in the core. The initative applications have shown that the stability and convergency in the calculations with the code are satisfactory
Analysis of a Station Black-Out transient in SMR by using the TRACE and RELAP5 code
De Rosa, F.; Lombardo, C.; Mascari, F.; Polidori, M.; Chiovaro, P.; D'Amico, S.; Moscato, I.; Vella, G.
2014-11-01
The present paper deals with the investigation of the evolution and consequences of a Station Black-Out (SBO) initiating event transient in the SPES3 facility [1]. This facility is an integral simulator of a small modular reactor being built at the SIET laboratories, in the framework of the R&D program on nuclear fission funded by the Italian Ministry of Economic Development and led by ENEA. The SBO transient will be simulated by using the RELAP5 and TRACE nodalizations of the SPES3 facility. Moreover, the analysis will contribute to study the differences on the code predictions considering the different modelling approach with one and/or three-dimensional components and to compare the capability of these codes to describe the SPES3 facility behaviour.
Energy Technology Data Exchange (ETDEWEB)
Luna, N. [Secretaria de Energia, Direccion de Operacion Petrolera, Mexico DF (Mexico); Mendez, F. [UNAM, Facultad de Ingenieria, Mexico DF (Mexico); Bautista, O. [ITESM, Division de Ingenieria y Arquitectura, Mexico DF (Mexico)
2005-05-01
We treat numerically in this paper, the transient analysis of a conjugated heat transfer process in the thermal entrance region of a circular tube with a fully developed laminar power-law fluid flow. We apply the quasi-steady approximation for the power-law fluid, identifying the suitable time scales of the process. Thus, the energy equation in the fluids is solved analytically using the well-known integral boundary layer technique. This solution is coupled to the transient energy equation for the solid where the transverse and longitudinal heat conduction effects are taken into account. The numerical results for the temporal evolution of the average temperature of the tube wall, {theta}{sub av,} is plotted for different nondimensional parameters such as conduction parameter, {alpha}, the aspect ratios of the tube, {epsilon} and {epsilon}{sub 0} and the index of power-law fluid, n. (orig.)
International Nuclear Information System (INIS)
Sommer, J.
1993-12-01
Accidents and transient processes were analyzed in order to assess the feasibility of eliminating the 2nd level accident protection (HO-2). All analyses were performed in 3 alternatives, viz. for the normal performance of HO-2, for the HO-2 signals being transferred to the 1st level accident protection (HO-1), and for a complete elimination of HO-2. Transfer of HO-2 signals to HO-1 definitely brings about an improvement of the nuclear power plant operation safety. There is no evidence indicating that the safety would decrease intolerably if HO-2 were eliminated altogether. Elimination of the ''moderate leak'' safety system does not require any thermohydraulic analysis to be performed. 18 refs
Freight performance measures : approach analysis.
2010-05-01
This report reviews the existing state of the art and also the state of the practice of freight performance measurement. Most performance measures at the state level have aimed at evaluating highway or transit infrastructure performance with an empha...
International Nuclear Information System (INIS)
Tziourtzioumis, Dimitrios; Stamatelos, Anastassios
2012-01-01
Highlights: ► We demonstrate how the fuel injection system responds to different fuel properties. ► Improvements to the ECU maps of the engine are suggested. ► These allow operation at high biodiesel blends without loss in engine performance. ► Continued operation with high biodiesel fuel blend, resulted in fuel pump failure. - Abstract: The results of steady state and transient engine bench tests of a 2.0l common-rail passenger car diesel engine fuelled by B70 biodiesel blend are compared with the corresponding results of baseline tests with standard EN 590 diesel fuel. The macroscopic steady-state performance and emissions of the same engine has already been presented elsewhere. The current study demonstrates how the engine management system responds to different fuel properties, with focus to the fuel system dynamics and the engine’s transient response. A set of characteristic transient operation points was selected for the tests. Data acquisition of engine ECU variables was made by means of INCA software/ETAS Mac2 interface. Additional data acquisition regarding engine performance was based on external sensors. The results indicate significant differences in fuel system dynamics and transient engine operation with the B70 blend at high fuel flow rates. Certain modifications to engine ECU maps and control parameters are proposed, aimed at improvement of transient performance of modern engines run on high percentage biodiesel blends. However, a high pressure pump failure that was observed after prolonged operation with the B70 blend, hints to the use of more conservative biodiesel blending in fuel.
Fast thermal transients on valve
International Nuclear Information System (INIS)
Ferjancic, M.; Stok, B.; Halilovic, M.; Koc, P.; Mole, N.; Otrin, Z.; Kotar, A.
2007-01-01
One of the regulatory body methods to supervise nuclear safety of a nuclear power plant is a review of plant modifications and evaluation of their impact on plant operating experience. The Slovenian Nuclear Safety Administration (SNSA) licensed in April 2003 the use of leak-before-break (LBB) methodology in the Krsko NPP for the primary loop including surge line and connecting pipelines with minimal diameter of 6 inch. The SNSA decision based also on fracture mechanics analyses that include direct pipe failure mechanisms such as water hammer, creep damage, erosion and corrosion, fatigue and environmental conditions over the entire life of the plant. The evaluation of the operating transients pointed out, that presumed loadings, used for the LBB analysis, did not incorporate all the fast thermal transients data. For that purpose the SNSA requested Faculty of Mechanical Engineering (FS) in Ljubljana to perform additional analyses. The results of the analysis shall confirm the validity of the LBB analysis. (author)
Software Performs Complex Design Analysis
2008-01-01
Designers use computational fluid dynamics (CFD) to gain greater understanding of the fluid flow phenomena involved in components being designed. They also use finite element analysis (FEA) as a tool to help gain greater understanding of the structural response of components to loads, stresses and strains, and the prediction of failure modes. Automated CFD and FEA engineering design has centered on shape optimization, which has been hindered by two major problems: 1) inadequate shape parameterization algorithms, and 2) inadequate algorithms for CFD and FEA grid modification. Working with software engineers at Stennis Space Center, a NASA commercial partner, Optimal Solutions Software LLC, was able to utilize its revolutionary, one-of-a-kind arbitrary shape deformation (ASD) capability-a major advancement in solving these two aforementioned problems-to optimize the shapes of complex pipe components that transport highly sensitive fluids. The ASD technology solves the problem of inadequate shape parameterization algorithms by allowing the CFD designers to freely create their own shape parameters, therefore eliminating the restriction of only being able to use the computer-aided design (CAD) parameters. The problem of inadequate algorithms for CFD grid modification is solved by the fact that the new software performs a smooth volumetric deformation. This eliminates the extremely costly process of having to remesh the grid for every shape change desired. The program can perform a design change in a markedly reduced amount of time, a process that would traditionally involve the designer returning to the CAD model to reshape and then remesh the shapes, something that has been known to take hours, days-even weeks or months-depending upon the size of the model.
Directory of Open Access Journals (Sweden)
Silvestar Šesnić
2016-01-01
Full Text Available The paper deals with the stochastic collocation analysis of a time domain response of a straight thin wire scatterer buried in a lossy half-space. The wire is excited either by a plane wave transmitted through the air-ground interface or by an equivalent current source representing direct lightning strike pulse. Transient current induced at the center of the wire, governed by corresponding Pocklington integrodifferential equation, is determined analytically. This antenna configuration suffers from uncertainties in various parameters, such as ground properties, wire dimensions, and position. The statistical processing of the results yields additional information, thus enabling more accurate and efficient analysis of buried wire configurations.
International Nuclear Information System (INIS)
Fan, Li-Wu; Wu, Yu-Yue; Xiao, Yu-Qi; Zeng, Yi; Zhang, Yi-Ling; Yu, Zi-Tao
2016-01-01
Highlights: • A liquid metal is adopted as the PCM in a thermal energy storage-based heat sink. • Transient performance of the heat sink is tested in comparison to an organic PCM. • The liquid metal has a similar volumetric latent heat of fusion to the organic PCM. • Outperformance of the liquid metal is found due to its higher thermal conductivity. • Liquid metals are preferred when the system weight is less important than volume. - Abstract: In this Technical Note, the use of a liquid metal, i.e., a low melting point Pb–Sn–In–Bi alloy, as the phase change material (PCM) in thermal energy storage-based heat sinks is tested in comparison to an organic PCM (1-octadecanol) having a similar melting point of ∼60 °C. The thermophysical properties of the two types of PCM are characterized, revealing that the liquid metal is much more conductive while both have nearly identical volumetric latent heat of fusion (∼215 MJ/m 3 ). By using at the same volume of 80 mL, i.e., the same energy storage capacity, the liquid metal is shown to outperform significantly over the organic PCM under the various heating powers up to 105.3 W/cm 2 . During the heating period, the use of the liquid metal leads to a remarkable extension of the effective protection time to nearly twice longer as well as a reduction of the highest overheating temperature by up to 50 °C. The cool-down period can also be shortened significantly by taking advantage of the much higher thermal conductivity of the liquid metal. These findings suggest that liquid metals could serve as a promising PCM candidate for particular applications where the volume limit is very rigorous and the penalty in weight increment is acceptable.
DYNREL - the reference calculation (coupled code utilization on analysis of RIA-transient)
International Nuclear Information System (INIS)
Strmensky, C.; Darilek, P.
2003-01-01
DYNREL is coupled code, comprising DYN3D and RELAP5 programs. The coupled code has been developed during four years. Now DYNREL is tested on selected RIA and thermo-hydraulic transient calculations. This material describes some results from selected RIA transient calculation (initiated by control rod movement). DYNREL modelled the whole nuclear reactors. The core is modeled as 313 or 349 independent thermo-hydraulic channels with 10 or 20 axial layers. Thermo-hydraulic part contains about 700 components that covered the six loops' model of nuclear power plant in detail. The calculated results are compared with DYN3D/M3, DYN3D/H1.1 results (Authors)
Analysis of Switching Transients during Energization in Large Offshore Wind Farms
Directory of Open Access Journals (Sweden)
Gang Liu
2018-02-01
Full Text Available In order to study switching transients in an offshore wind farm (OWF collector system, we employ modeling methods of the main components in OWFs, including vacuum circuit breakers (VCBs, submarine cables, and wind turbine transformers (WTTs. In particular, a high frequency (HF VCB model that reflects the prestrike characteristics of VCBs was developed. Moreover, a simplified experimental system of an OWF electric collection system was set up to verify the developed models, and a typical OWF medium voltage (MV cable collection system was built in PSCAD/EMTDC based on the developed models. Finally, we investigated the influences of both the initial closing phase angle of VCBs and typical system operation scenarios on the amplitude and steepness of transient overvoltages (TOVs at the high-voltage side of WTTs.
Analysis on accident transient of complete loss of forced reactor coolant flow in AP1000
International Nuclear Information System (INIS)
Jing Jianping; Zhang Chunming; Sun Wei; An Jieru; Jia Bin
2014-01-01
AP1OOO reactor is a typical third generation nuclear power plant at present in the world. The primary system of AP10OO nuclear power plant was modeled by using RELAP5/MOD 3.3 code, and the transient thermal hydraulic characteristics were analyzed under the accident sequence of complete loss of forced reactor coolant flow. The calculation results by RELAP5 code were compared with those of the COAST and LOFTRAN codes. The distributions by RELAP5 code were consistent with those of the COAST and LOFTRAN codes. The study results show that the RELAP5 model can accurately simulate the transient thermal hydraulic characteristics of AP1OOO under the accident of complete loss of forced reactor coolant flow. (authors)
Analysis of single particle diffusion with transient binding using particle filtering.
Bernstein, Jason; Fricks, John
2016-07-21
Diffusion with transient binding occurs in a variety of biophysical processes, including movement of transmembrane proteins, T cell adhesion, and caging in colloidal fluids. We model diffusion with transient binding as a Brownian particle undergoing Markovian switching between free diffusion when unbound and diffusion in a quadratic potential centered around a binding site when bound. Assuming the binding site is the last position of the particle in the unbound state and Gaussian observational error obscures the true position of the particle, we use particle filtering to predict when the particle is bound and to locate the binding sites. Maximum likelihood estimators of diffusion coefficients, state transition probabilities, and the spring constant in the bound state are computed with a stochastic Expectation-Maximization (EM) algorithm. Copyright © 2016 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
David, J.; Procaccia, H.; Billon, F.
1983-08-01
The operating efficiency of steam generators (S.G.s) and their structural integrity depend on the design configurations of the feedwater spray within the S.G., and on the operating procedure. To check the merit of some design modifications, and to verify the fluid-structure interaction with a view to preserve the S.G.s integrity during severe operating transients, a special instrumentation that admits the determination of the instantaneous thermal hydraulic characteristics of the flow in the secondary water and the corresponding metal temperature, in particular in the S.G. downcomer and near the S.G. tube sheet, has been installed by EDF on one steam generator of Tricastin unit 1 power plant. In parallel, FRAMATOME has developped a computer code, TEMPTRON, that allows the calculation of the thermal loads and the consequent stresses in the most sollicited zones of the steam generator during transient operation of the plant
DEFF Research Database (Denmark)
Wagner, Manfred H.; Rolon-Garrido, Victor H.; Nielsen, Jens Kromann
2008-01-01
The transient and steady-state elongational viscosity data of three bidisperse polystyrene blends were investigated recently by Nielsen et al. [J. Rheol. 50, 453-476 (2006)]. The blends contain a monodisperse high molar mass component (M-L= 390 kg/ mol) in a matrix of a monodisperse small molar...... stretching potential of the long-chain component and an increasing steady-state elongational viscosity with increasing strain rate. In addition, in the dilution regime, a transition from affine chain stretch to nonaffine tube squeeze with decreasing strain rate is identified. The dilution regime ends......, and allowing (albeit by use of empirical linear-viscoelastic shift factors to correct the linear-viscoelastic predictions) for a quantitative description of the transient and steady-state elongational viscosities of the bidisperse polystyrene blends....
Development of the computer code for transient analysis in experimental fast reactor
International Nuclear Information System (INIS)
Moreira, M.L.; Sato, E.F.
1989-01-01
A calculational model of heat transfer and fluid coolant dynamics, for thermal-hydraulic simulation of the primary system components of a pool type experimental fast breeder reactor, has developed. Programmed in FORTRAN, the SORES code was used to simulate transients as loss of pumping and loss of secondary sodium flow in the EBRII. The SORES results compared with measured data and NATDEMO code results was found to be good. (author) [pt
Energy Technology Data Exchange (ETDEWEB)
Hanson, J.M.
1984-12-01
The report evaluates previous investigations of the gas permeability of the rock surrounding emplacement holes at the Nevada Test Site. The discussion sets the framework from which the present uncertainty in gas permeability can be overcome. The usefulness of the barometric pressure testing method has been established. Flow models were used to evaluate barometric pressure transients taken at NTS holes U2fe, U19ac and U20ai. 31 refs., 103 figs., 18 tabs. (ACR)
International Nuclear Information System (INIS)
Hanson, J.M.
1984-12-01
The report evaluates previous investigations of the gas permeability of the rock surrounding emplacement holes at the Nevada Test Site. The discussion sets the framework from which the present uncertainty in gas permeability can be overcome. The usefulness of the barometric pressure testing method has been established. Flow models were used to evaluate barometric pressure transients taken at NTS holes U2fe, U19ac and U20ai. 31 refs., 103 figs., 18 tabs
FRAPTRAN Fuel Rod Code and its Coupled Transient Analysis with the GENFLO Thermal-Hydraulic Code
International Nuclear Information System (INIS)
Valtonen, Keijo; Hamalainen, Anitta; Cunningham, Mitchel E.
2002-01-01
The FRAPTRAN computer code has been developed for the U.S. Nuclear Regulatory Commission (NRC) to calculate fuel behavior during power and/or cooling transients at burnup levels up to 65 MWd/kgM. FRAPTRAN has now been assessed and peer reviewed. STUK/VTT have coupled GENFLO to FRAPTRAN for calculations with improved coolant boundary conditions and prepared example calculations to show the effect of improving the coolant boundary conditions.
FRAPTRAN Fuel Rod Code and its Coupled Transient Analysis with the GENFLO Thermal-Hydraulic Code
Energy Technology Data Exchange (ETDEWEB)
Valtonen, Keijo (Radiation and Nuclear Safety Authority, Finland); Hamalainen, Anitta (VTT Energy, Finland); Cunningham, Mitchel E.(BATTELLE (PACIFIC NW LAB))
2002-05-01
The FRAPTRAN computer code has been developed for the U.S. Nuclear Regulatory Commission (NRC) to calculate fuel behavior during power and/or cooling transients at burnup levels up to 65 MWd/kgM. FRAPTRAN has now been assessed and peer reviewed. STUK/VTT have coupled GENFLO to FRAPTRAN for calculations with improved coolant boundary conditions and prepared example calculations to show the effect of improving the coolant boundary conditions.
International Nuclear Information System (INIS)
Yamakawa, T.
1979-01-01
The base mats for several types of reactor containment structures which rest directly on the surface of a uniform rock foundation are nearly square. They are, however, idealized as beams or circular plates on Winkler model of foundation in engineering design and anlysis. In this paper, the square base mats on elastic foundation are analytically replaced by circular plates, which are equal in area, on Winkler foundation. These basic equations, boundary conditions and general solutions defined exactly in series of the Bessel functions of the first and the second kinds are to be shown at the beginning. The bending problems considering transverse shear effect and membrane problems under axisymmetric and non-axisymmetric loads are studied. Particularly, static and dynamic linear behaviours of circular plates on elastic foundation subjected to seismic loads can be analyzed. Secondly, this theory is applied to the investigation of static and dynamic behaviours of the base mat of the reactor containment structure on elastic foundation subjected to axisymmetric transient pressure loadings which are periodic or impact loads, including the soil-structure interaction effect. These transient loads due to safety relief valve (SRV) discharges or losses of coolant accidents (LOCA) were newly recognized transient phenomena for the boiling water reactor (BWR). Analytical results by the pure bending theory and the bending theory considering shear effect are presented to exhibit the dynamic response behaviour of the base mat in comparison with the static behaviour as the transient loading frequencies and the foundation damping values vary. The specific purpose of investigation is to determine the dynamic load factors on the base mat design. (orig.)
Temporal frequency probing for 5D transient analysis of global light transport
O'Toole, Matthew
2014-07-27
We analyze light propagation in an unknown scene using projectors and cameras that operate at transient timescales. In this new photography regime, the projector emits a spatio-temporal 3D signal and the camera receives a transformed version of it, determined by the set of all light transport paths through the scene and the time delays they induce. The underlying 3D-to-3D transformation encodes scene geometry and global transport in great detail, but individual transport components (e.g., direct reflections, inter-reflections, caustics, etc.) are coupled nontrivially in both space and time. To overcome this complexity, we observe that transient light transport is always separable in the temporal frequency domain. This makes it possible to analyze transient transport one temporal frequency at a time by trivially adapting techniques from conventional projector-to-camera transport. We use this idea in a prototype that offers three never-seen-before abilities: (1) acquiring time-of-flight depth images that are robust to general indirect transport, such as interreflections and caustics; (2) distinguishing between direct views of objects and their mirror reflection; and (3) using a photonic mixer device to capture sharp, evolving wavefronts of "light-in-flight".
Directory of Open Access Journals (Sweden)
Qinglei Jiang
2011-01-01
Full Text Available The current paper studies the influence of annular seal flow on the transient response of centrifugal pump rotors during the start-up period. A single rotor system and three states of annular seal flow were modeled. These models were solved using numerical integration and finite difference methods. A fluid-structure interaction method was developed. In each time step one of the three annular seal models was chosen to simulate the annular seal flow according to the state of rotor systems. The objective was to obtain a transient response of rotor systems under the influence of fluid-induced forces generated by annular seal flow. This method overcomes some shortcomings of the traditional FSI method by improving the data transfer process between two domains. Calculated results were in good agreement with the experimental results. The annular seal was shown to have a supportive effect on rotor systems. Furthermore, decreasing the seal clearance would enhance this supportive effect. In the transient process, vibration amplitude and critical speed largely changed when the acceleration of the rotor system increased.
Performance Analysis of Waste Heat Driven Pressurized Adsorption Chiller
LOH, Wai Soong
2010-01-01
This article presents the transient modeling and performance of waste heat driven pressurized adsorption chillers for refrigeration at subzero applications. This innovative adsorption chiller employs pitch-based activated carbon of type Maxsorb III (adsorbent) with refrigerant R134a as the adsorbent-adsorbate pair. It consists of an evaporator, a condenser and two adsorber/desorber beds, and it utilizes a low-grade heat source to power the batch-operated cycle. The ranges of heat source temperatures are between 55 to 90°C whilst the cooling water temperature needed to reject heat is at 30°C. A parametric analysis is presented in the study where the effects of inlet temperature, adsorption/desorption cycle time and switching time on the system performance are reported in terms of cooling capacity and coefficient of performance. © 2010 by JSME.
Directory of Open Access Journals (Sweden)
Miroslav M Živković
2010-01-01
Full Text Available This paper deals with transient nonlinear heat conduction through the insulation wall of the tank for transportation of liquid aluminum. Tanks designed for this purpose must satisfy certain requirements regarding temperature of loading and unloading, during transport. Basic theoretical equations are presented, which describe the problem of heat conduction finite element (FE analysis, starting from the differential equation of energy balance, taking into account the initial and boundary conditions of the problem. General 3D problem for heat conduction is considered, from which solutions for two- and one-dimensional heat conduction can be obtained, as special cases. Forming of the finite element matrices using Galerkin method is briefly described. The procedure for solving equations of energy balance is discussed, by methods of resolving iterative processes of nonlinear transient heat conduction. Solution of this problem illustrates possibilities of PAK-T software package, such as materials properties, given as tabular data, or analytical functions. Software also offers the possibility to solve nonlinear and transient problems with incremental methods. Obtained results for different thicknesses of the tank wall insulation materials enable its comparison in regards to given conditions
TAPINS: A THERMAL-HYDRAULIC SYSTEM CODE FOR TRANSIENT ANALYSIS OF A FULLY-PASSIVE INTEGRAL PWR
Directory of Open Access Journals (Sweden)
YEON-GUN LEE
2013-08-01
Full Text Available REX-10 is a fully-passive small modular reactor in which the coolant flow is driven by natural circulation, the RCS is pressurized by a steam-gas pressurizer, and the decay heat is removed by the PRHRS. To confirm design decisions and analyze the transient responses of an integral PWR such as REX-10, a thermal-hydraulic system code named TAPINS (Thermal-hydraulic Analysis Program for INtegral reactor System is developed in this study. Based on a one-dimensional four-equation drift-flux model, TAPINS incorporates mathematical models for the core, the helical-coil steam generator, and the steam-gas pressurizer. The system of difference equations derived from the semi-implicit finite-difference scheme is numerically solved by the Newton Block Gauss Seidel (NBGS method. TAPINS is characterized by applicability to transients with non-equilibrium effects, better prediction of the transient behavior of a pressurizer containing non-condensable gas, and code assessment by using the experimental data from the autonomous integral effect tests in the RTF (REX-10 Test Facility. Details on the hydrodynamic models as well as a part of validation results that reveal the features of TAPINS are presented in this paper.
Analysis and simulation of electromagnetic transients in HVAC cable transmission grids
Energy Technology Data Exchange (ETDEWEB)
DA Silva, F.M.F.
2011-07-15
Denmark is the first country in the world undergrounding most of its transmission network. As a result, several technical barriers and challenges associated to the use of an undergrounded transmission grid must first be dealt with. For that purpose, several research and development projects were initiated by the Danish TSO, among them this PhD thesis. The main objective of this PhD is to study electromagnetic transient phenomena. Thereto, the thesis is divided into two main parts: 1) Description of the different electromagnetic phenomena likely to occur in transmission grids with a large amount of HVAC cables and respective countermeasures; 2) Guidelines for the proper simulation of those phenomena when using EMTP software, more specifically PSCAD/EMTDC, and methods to optimize the simulations; A simulation network based on the Transmission Grid of West Denmark as planned for 2030 has been used as simulation base case to identify the dimensioning transient phenomena and find the right countermeasures for an undergrounded transmission network. In order to ensure that the transient studies are made on a proper model basis, the frequency dependent phasor model in PSCAD/EMTDC has been verified by measurements on a 100 km, 58 km of land cable plus 42 km of submarine cable, 165 kV cable, which is connecting an offshore wind farm to the Danish transmission network. The 2030 West Denmark Grid has two voltage levels, 165 kV and 400 kV. The 165 kV level will be all cables, whereas the 400 kV level will mostly be cables. This network provides the necessary complexity for the electromagnetic studies. The accuracy of cable simulation models has been addressed by several authors prior to this thesis. However, the validations were normally made for short cables, whereas in this thesis are analysed cables with dozens of km length. The thesis shows the measurement's results and demonstrates that the land cable model is accurate, yet the same is not true for the used submarine
Directory of Open Access Journals (Sweden)
Paulo Antonio Delgado-Arredondo
2015-01-01
Full Text Available Induction motors are critical components for most industries and the condition monitoring has become necessary to detect faults. There are several techniques for fault diagnosis of induction motors and analyzing the startup transient vibration signals is not as widely used as other techniques like motor current signature analysis. Vibration analysis gives a fault diagnosis focused on the location of spectral components associated with faults. Therefore, this paper presents a comparative study of different time-frequency analysis methodologies that can be used for detecting faults in induction motors analyzing vibration signals during the startup transient. The studied methodologies are the time-frequency distribution of Gabor (TFDG, the time-frequency Morlet scalogram (TFMS, multiple signal classification (MUSIC, and fast Fourier transform (FFT. The analyzed vibration signals are one broken rotor bar, two broken bars, unbalance, and bearing defects. The obtained results have shown the feasibility of detecting faults in induction motors using the time-frequency spectral analysis applied to vibration signals, and the proposed methodology is applicable when it does not have current signals and only has vibration signals. Also, the methodology has applications in motors that are not fed directly to the supply line, in such cases the analysis of current signals is not recommended due to poor current signal quality.
Bock, Y.; Crowell, B. W.; Dong, D.; Fang, P.; Kedar, S.; Liu, Z.; Moore, A. W.; Owen, S. E.; Prawirodirdjo, L. M.; Squibb, M. B.; Webb, F.
2011-12-01
As part of a NASA MEaSUREs project and its contribution to EarthScope, we are producing a combined 24-hour position time series for more than 1000 stations in Western North America based on independent analyses of continuous GPS data at JPL (using GIPSY software) and at SIO (using GAMIT software), using the SOPAC archive as a common source of metadata. Included are all EarthScope/PBO stations as well as stations from other networks still active (SCIGN, BARD and PANGA), and pre-PBO era data some already two decades old. The time series are appended weekly and the entire data set is filtered once a week using a modified principle component analysis (PCA) algorithm using the st_filter software. Both the unfiltered and filtered data undergo a time series analysis with the analyze_tseri software. All relevant time series are available through NASA's GPS Explorer data portal and its interactive Java-based time series utility. After a comprehensive process of re-analysis and quality control, we have evaluated the time series for transient deformation, that is, time series that deviate from linear behavior due to coseismic and postseismic deformation, slow slip events, volcanic events, and strain anomalies. In addition, we have observed non-tectonic effects from hydrologic, magmatic and anthropogenic sources which are manifested primarily in the vertical but sometimes bleed over into the horizontal and make tectonic interpretation and transient detection difficult. Other sources of anomalous deformation are due to dam deformation such as Diamond Valley Lake an important water reservoir in Southern California, and structural deformation including the Harvest oil platform used by NASA for altimeter calibrations. We present a compendium of transient deformation discovered in our time series analysis, including duration, geographical extent and magnitudes.
Diagnosing SWOT through Importance-performance Analysis
Alagirisamy Kamatchi Subbiah Sukumaran; Shanmugasundaram Chandrasekaran Sivasundaram
2015-01-01
The aim of the study is to evaluate the performance of the firms surveyed against the importance of the opportunities, threats, strengths and weaknesses applicable to those firms using Importance-Performance analysis. Firms optimize their Strengths, Weaknesses, Opportunities and Threats with the help of SWOT analysis. Martilla and James (1977) popularized the Importance-Performance analysis through their study titled with the same name. Importance-Performance analysis can be used to evaluate ...
Directory of Open Access Journals (Sweden)
A. V. Stepanov
2014-01-01
Full Text Available A development of the direct Lyapunov method for the analysis of transient stability of a system of synchronous generators based on the determination of non- stable equilibria on a multidimensional sphere.We consider the problem of transient stability analysis for a system of synchronous generators under the action of strong perturbations. The aim of our work is to develop methods to analyze a transient stability of the system of synchronous generators, which allow getting trustworthy results on reserve transient stability under different perturbations. For the analysis of transient stability, we use the direct Lyapunov method.One of the problems for this method application is to find the Lypunov function that well reflects the properties of a parallel system of synchronous generators. The most reliable results were obtained when the analysis of transient stability was performed with a Lyapunov function of energy type. Another problem for application of the direct Lyapunov method is to determine the critical value of the Lyapunov function, which requires finding the non-stable equilibria of the system. Determination of the non-stable equilibria requires studying the Lyapunov function in a multidimensional space in a neighborhood of a stable equilibrium for the post-breakdown system; this is a complicated non-linear problem.In the paper, we propose a method for determination of the non-stable equilibria on a multidimensional sphere. The method is based on a search of a minimum of the Lyapunov function on a multidimensional sphere the center of which is a stable equilibrium. Our method allows, comparing with the other, e.g., gradient methods, reliable finding a non-stable equilibrium and calculating the critical value. The reliability of our method is proved by numerical experiments. The developed methods and a program realized in a MATLAB package can be recommended for design of a post-breakdown control system of synchronous generators or as a
International Nuclear Information System (INIS)
Lazaro, A.; Ammirabile, L.; Martorell, S.
2015-01-01
Lead-Cooled Fast Reactor (LFR) has been identified as one of promising future reactor concepts in the technology road map of the Generation IVC International Forum (GIF)as well as in the Deployment Strategy of the European Sustainable Nuclear Industrial Initiative (ESNII), both aiming at improved sustainability, enhanced safety, economic competitiveness, and proliferation resistance. This new nuclear reactor concept requires the development of computational tools to be applied in design and safety assessments to confirm improved inherent and passive safety features of this design. One approach to this issue is to modify the current computational codes developed for the simulation of Light Water Reactors towards their applicability for the new designs. This paper reports on the performed modifications of the TRACE system code to make it applicable to LFR safety assessments. The capabilities of the modified code are demonstrated on series of benchmark exercises performed versus other safety analysis codes. (Author)
International Nuclear Information System (INIS)
Nie, Ren-Shi; Guo, Jian-Chun; Jia, Yong-Lu; Zhu, Shui-Qiao; Rao, Zheng; Zhang, Chun-Guang
2011-01-01
The no-type curve with negative skin of a horizontal well has been found in the current research. Negative skin is very significant to transient well test and rate decline analysis. This paper first presents the negative skin problem where the type curves with negative skin of a horizontal well are oscillatory. In order to solve the problem, we propose a new model of transient well test and rate decline analysis for a horizontal well in a multiple-zone composite reservoir. A new dimensionless definition of r D is introduced in the dimensionless mathematical modelling under different boundaries. The model is solved using the Laplace transform and separation of variables techniques. In Laplace space, the solutions for both constant rate production and constant wellbore pressure production are expressed in a unified formula. We provide graphs and thorough analysis of the new standard type curves for both well test and rate decline analysis; the characteristics of type curves are the reflections of horizontal well production in a multiple-zone reservoir. An important contribution of our paper is that our model removed the oscillation in type curves and thus solved the negative skin problem. We also show that the characteristics of type curves depend heavily on the properties of different zones, skin factor, well length, formation thickness, etc. Our research can be applied to a real case study
Liu, Fang; Shen, Changqing; He, Qingbo; Zhang, Ao; Liu, Yongbin; Kong, Fanrang
2014-01-01
A fault diagnosis strategy based on the wayside acoustic monitoring technique is investigated for locomotive bearing fault diagnosis. Inspired by the transient modeling analysis method based on correlation filtering analysis, a so-called Parametric-Mother-Doppler-Wavelet (PMDW) is constructed with six parameters, including a center characteristic frequency and five kinematic model parameters. A Doppler effect eliminator containing a PMDW generator, a correlation filtering analysis module, and a signal resampler is invented to eliminate the Doppler effect embedded in the acoustic signal of the recorded bearing. Through the Doppler effect eliminator, the five kinematic model parameters can be identified based on the signal itself. Then, the signal resampler is applied to eliminate the Doppler effect using the identified parameters. With the ability to detect early bearing faults, the transient model analysis method is employed to detect localized bearing faults after the embedded Doppler effect is eliminated. The effectiveness of the proposed fault diagnosis strategy is verified via simulation studies and applications to diagnose locomotive roller bearing defects. PMID:24803197
Liu, Yang
2018-02-26
A wavelet-enhanced plane-wave time-domain (PWTD) algorithm for efficiently and accurately solving time-domain surface integral equations (TD-SIEs) on electrically large conducting objects is presented. The proposed scheme reduces the memory requirement and computational cost of the PWTD algorithm by representing the PWTD ray data using local cosine wavelet bases (LCBs) and performing PWTD operations in the wavelet domain. The memory requirement and computational cost of the LCB-enhanced PWTD-accelerated TD-SIE solver, when applied to the analysis of transient scattering from smooth quasi-planar objects with near-normal incident pulses, scale nearly as O(Ns log Ns) and O(Ns 1.5 ), respectively. Here, Ns denotes the number of spatial unknowns. The efficiency and accuracy of the proposed scheme are demonstrated through its applications to the analysis of transient scattering from a 185 wave-length-long NASA almond and a 123-wavelength long Air-bus-A320 model.
International Nuclear Information System (INIS)
Ren Zhihao; Kong Xiangyin; Tsai Chiungwen; Ruan Jialei; Li Jinggang; Ma Zhongying; Yan Jianxing; Ma Yinxiang
2015-01-01
A system transient thermal-hydraulic analysis code for PWRs named GINKGO is being developed as part of the indigenous effort of China General Nuclear Power Corp. (CGN) to develop a full-spectrum software package for reactor design and safety analysis. Implemented using the Object-Oriented programming technology, GINKGO is designed to be used for simulating all PWR transients except LBLOCA. The primary physical models and key algorithms applied in GINKGO and also the preliminary validation with the phenomena cases are introduced in the paper. To account for reactor coolant transients, the separated phase model under thermal equilibrium is used in the code. The three governing mixture balance equations augmented with Chexal-Lellouche drift-flux model to determine phase velocities are solved at each time step. Thermal equilibrium between the vapor and liquid phases is assumed with the exception of the upper head volume and pressurizer. And two-region non-equilibrium model and multi-region non-equilibrium model are available for the pressurizer simulation. The reactor point kinetics model with six groups of delayed neutrons, the partial derivative approximation of the DNBR model and decay heat model are combined to give a full description for the reactor core. The additional component model, engineered safety system model and models for other auxiliary systems in GINKGO demonstrate a complete capability for PWR safety analysis and thermal-hydraulic design. A fully implicit solution algorithm involving pressure search is applied in GINKGO to improve the stability of the solution method, especially when two-phase conditions with unequal phase velocities exist. Different phenomena cases are set up to demonstrate the capability of GINKGO used in different boundary conditions, steady state achievement, reverse and branch flow, etc. The GINKGO code uses the C/C++ programming language to take advantage of the language's inherent Object Oriented characteristic and to
International Nuclear Information System (INIS)
Cintra Filho, J. de S.; Cintra, W.H.
1983-01-01
The applicability of the optimal control theory to thermal transients is studied in the case of bringing, the temperature distribution in a flat plate, up to a desired profile, in a fixed time interval, by varying, within certain limits, the temperature outside the plate. The problem is analysed by the method of ligenfunction expansions and the maximum principle with control variable inequality constraints. A numerical application then supports the developed procedure, and emphasizes the role, in the optimization process, of the heat conduction within the plate. (Author) [pt
Transient Thermal Model and Analysis of the Lunar Surface and Regolith for Cryogenic Fluid Storage
Christie, Robert J.; Plachta, David W.; Yasan, Mohammad M.
2008-01-01
A transient thermal model of the lunar surface and regolith was developed along with analytical techniques which will be used to evaluate the storage of cryogenic fluids at equatorial and polar landing sites. The model can provide lunar surface and subsurface temperatures as a function of latitude and time throughout the lunar cycle and season. It also accounts for the presence of or lack of the undisturbed fluff layer on the lunar surface. The model was validated with Apollo 15 and Clementine data and shows good agreement with other analytical models.
Sayed, Sadeed Bin
2016-11-02
An explicit marching on-in-time scheme for analyzing transient electromagnetic wave interactions on ferromagnetic scatterers is described. The proposed method solves a coupled system of time domain magnetic field volume integral and Landau-Lifshitz-Gilbert (LLG) equations. The unknown fluxes and fields are discretized using full and half Schaubert-Wilton-Glisson functions in space and bandlimited temporal interpolation functions in time. The coupled system is cast in the form of an ordinary differential equation and integrated in time using a PE(CE)m type linear multistep method to obtain the unknown expansion coefficients. Numerical results demonstrating the stability and accuracy of the proposed scheme are presented.
Directory of Open Access Journals (Sweden)
Orie Sakamoto
2016-01-01
Full Text Available In remote site power systems with small diesel generators, weak distribution feeders with diesel generators may suffer from voltage and power fluctuations due to misfiring of the engine cylinder. An electromagnetic transient (EMT program named XTAP is considered to be useful to analyze these phenomena. In this study, a new diesel generator model with example fluctuating engine torque has been developed using XTAP for analyses of small power systems with those diesel engines. The configuration and verification results of the developed model are presented in the paper.
Directory of Open Access Journals (Sweden)
Isabelle Guénot-Delahaie
2018-03-01
Full Text Available The ALCYONE multidimensional fuel performance code codeveloped by the CEA, EDF, and AREVA NP within the PLEIADES software environment models the behavior of fuel rods during irradiation in commercial pressurized water reactors (PWRs, power ramps in experimental reactors, or accidental conditions such as loss of coolant accidents or reactivity-initiated accidents (RIAs. As regards the latter case of transient in particular, ALCYONE is intended to predictively simulate the response of a fuel rod by taking account of mechanisms in a way that models the physics as closely as possible, encompassing all possible stages of the transient as well as various fuel/cladding material types and irradiation conditions of interest. On the way to complying with these objectives, ALCYONE development and validation shall include tests on PWR-UO2 fuel rods with advanced claddings such as M5® under “low pressure–low temperature” or “high pressure–high temperature” water coolant conditions.This article first presents ALCYONE V1.4 RIA-related features and modeling. It especially focuses on recent developments dedicated on the one hand to nonsteady water heat and mass transport and on the other hand to the modeling of grain boundary cracking-induced fission gas release and swelling. This article then compares some simulations of RIA transients performed on UO2-M5® fuel rods in flowing sodium or stagnant water coolant conditions to the relevant experimental results gained from tests performed in either the French CABRI or the Japanese NSRR nuclear transient reactor facilities. It shows in particular to what extent ALCYONE—starting from base irradiation conditions it itself computes—is currently able to handle both the first stage of the transient, namely the pellet-cladding mechanical interaction phase, and the second stage of the transient, should a boiling crisis occur.Areas of improvement are finally discussed with a view to simulating and
Performance Analysis in Elite Sports
Talsma, Bertus Gatze
2013-01-01
The central theme of this dissertation concerns the development of techniques for analyzing and comparing performances of elite sportsmen. When performances are delivered under varying circumstances, or are influenced by other factors than the athletes' abilities, a fair comparison, for instance
Enhancing importance-performance analysis
DEFF Research Database (Denmark)
Eskildsen, Jacob Kjær; Kristensen, Kai
2006-01-01
Purpose: The interpretation of the importance/performance map is based on an assumption of independence between importance and performance but many studies question the validity of this assumption. The aim of this research is to develop a new typology for job satisfaction attributes as well...... as a new importance/performance map that can be an aid for organizations when they prioritize their improvement actions based on a job satisfaction study. Design/methodology/approach: A typology for possible relationships between importance and performance in job satisfaction studies is developed based...... on theoretical considerations. This typology is then applied and validated on approximately 10,000 responses from the European Employee Index 2002. Ultimately a new importance/performance map for priority setting in job satisfaction studies is developed based on the new typology for possible relationships...
Energy Technology Data Exchange (ETDEWEB)
Kim, Seyun; Kim, Minhee [KHNP CRI, Daejeon (Korea, Republic of)
2016-10-15
The total loss of feed water (TLOFW) scenario is a beyond design basis accident (DBA) for nuclear steam supply system (NSSS) but is considered in the safety analysis report (SAR) for the stress analysis of structures of KEPIC class 1 and the hydrogen generation analysis. The postulated single feed line break (FLB) scenario is DBA and is described in chapter 15.2 of SAR. To evaluate the safety impact, the integrity of plant and the coping measures, a transient of total loss of feed water due to the postulated breaks of both feed line is analyzed for OPR1000 with RELAP5 code. To evaluate the safety impact, the integrity of plant and the coping measures, a transient of total loss of feed water due to the postulated breaks of both feed line is analyzed for OPR1000 with RELAP5 code. The calculations show that the operation of safety depressurization system at 1800 seconds is an effective measure to mitigate the core damage due to the uncovery of the core according to the pressurization of primary loop. Through the sensitivity studies, it is presented that the peak cladding temperature is proportional to the break size.
FRAP-T1: a computer code for the transient analysis of oxide fuel rods
International Nuclear Information System (INIS)
Dearien, J.A.; Miller, R.L.; Hobbins, R.R.; Siefken, L.J.; Baston, V.F.; Coleman, D.R.
1977-02-01
FRAP-T is a FORTRAN IV computer code which can be used to solve for the transient response of a light water reactor (LWR) fuel rod during accident transients such as loss-of-coolant accident (LOCA) or a power-cooling-mismatch (PCM). The coupled effects of mechanical, thermal, internal gas, and material property response on the behavior of the fuel rod are considered. FRAP-T is a modular code with each major computational model isolated within the code and coupled to the main code by subroutine calls and data transfer through argument lists. FRAP-T is coupled to a materials properties subcode (MATPRO) which is used to provide gas, fuel, and cladding properties to the FRAP-T computational subcodes. No material properties need be supplied by the code user. The needed water properties are stored in tables built into the code. Critical heat flux (CHF) and heat transfer correlations for a wide range of coolant conditions are contained in modular subroutines. FRAP-T has been evaluated by making extensive comparisons between predictions of the code and experimental data. Comparison of predicted and experimental results are presented for a range of FRAP-T calculated parameters. The code is presently programmed and running on an IBM-360/75 and a CDC 7600 computer
Transient analysis of leaky Lamb waves with a semi-analytical finite element method.
Inoue, Daisuke; Hayashi, Takahiro
2015-09-01
We previously formulated a semi-analytical finite element technique for Lamb waves in a plate surrounded by fluids and investigated the dispersion curves and wave structures for leaky Lamb waves. Herein, this technique is extended to the calculation of transient responses both in a plate and in fluids for dynamic loading on the plate surface. To gain fundamental insights into guided wave inspection for a water-filled pipe or tank, guided waves generated upon transient loading of a flat plate water-loaded on one side were analyzed. The results show that a quasi-Scholte mode propagating at the plate-water interface is useful for the long-range inspection of a water-loaded plate because of its non-attenuation and minimal dispersion; moreover, this mode has superior generation efficiency in the low-frequency range, while it is localized near the plate-water interface at higher frequencies. Copyright © 2015 Elsevier B.V. All rights reserved.
Transient current analysis of a GaN radiation detector by TCAD
International Nuclear Information System (INIS)
Wang, Jinghui; Mulligan, Padhraic L.; Cao, Lei R.
2014-01-01
A gallium nitride (GaN) Schottky diode radiation detector has been fabricated with a successfully demonstrated radiation response to alpha particles and neutrons when using Li as a convertor. In order to understand the charge collection process for further device modification, the Sentaurus TCAD software package is employed to quantitatively study the transient current produced by energetic charge particles. By comparing the simulation and experimental results, especially the capacitance–voltage relationship and charge collection efficiency, the device parameters and physics models used for the simulation are validated. The time behavior of the transient current is studied, and the carrier generation/loss by impact ionization, recombination, and trapping are discussed. The total collected charge contributed by various components, such as drift, funneling, and diffusion are also analyzed. - Highlights: • A TCAD model is established for a GaN Schottky diode radiation detector. • Schottky side mainly collects holes, while ohmic side solely collects electrons. • The funneling region evolution is visualized by carrier current densities. • Carrier generation/loss by impact ionization/trapping is insignificant. • The collected charges are primarily drift carriers in the depletion region
High-resolution spectral analysis of transient pulsars in the Small Magellanic Cloud
La Palombara, N.; Sidoli, L.; Esposito, P.; Pintore, F.; Tiengo, A.; Mereghetti, S.
2017-10-01
At low energies the spectra of several X-ray binary pulsars show a significant excess over the main power-law component. Although various physical processes (both thermal and non-thermal) have been invoked to produce this excess, its origin is still unclear. The best sources to study this type of feature are the transient pulsars in the Small Magellanic Cloud, which can reach high luminosities (L_{X} > 10^{38} erg s^{-1}) and, thanks to the low absorption in the SMC direction, can provide high statistics spectra at low energies. In the last three years we observed with XMM-Newton the large outburst of three of these transient pulsars (RX J0059.2-7138, SMC X-2, and IGR J01572-7259). Thanks to the high throughput and spectral resolution of XMM, these observations allowed us to investigate at an unprecedented level of detail their spectral and timing properties at soft X-ray energies. We found that these sources show a pulsed emission also at low energies, and that they are characterized by a significant thermal component of low temperature (kT ˜ 0.2 keV); moreover, we discovered several emission and absorption features, which are very likely produced by photoionization of plasma located above the inner regions of the accretion disc.
Transient current analysis of a GaN radiation detector by TCAD
Energy Technology Data Exchange (ETDEWEB)
Wang, Jinghui; Mulligan, Padhraic L.; Cao, Lei R., E-mail: cao.152@osu.edu
2014-10-11
A gallium nitride (GaN) Schottky diode radiation detector has been fabricated with a successfully demonstrated radiation response to alpha particles and neutrons when using Li as a convertor. In order to understand the charge collection process for further device modification, the Sentaurus TCAD software package is employed to quantitatively study the transient current produced by energetic charge particles. By comparing the simulation and experimental results, especially the capacitance–voltage relationship and charge collection efficiency, the device parameters and physics models used for the simulation are validated. The time behavior of the transient current is studied, and the carrier generation/loss by impact ionization, recombination, and trapping are discussed. The total collected charge contributed by various components, such as drift, funneling, and diffusion are also analyzed. - Highlights: • A TCAD model is established for a GaN Schottky diode radiation detector. • Schottky side mainly collects holes, while ohmic side solely collects electrons. • The funneling region evolution is visualized by carrier current densities. • Carrier generation/loss by impact ionization/trapping is insignificant. • The collected charges are primarily drift carriers in the depletion region.
International Nuclear Information System (INIS)
Pailharey, Eric
2000-01-01
The behavior of laser diodes under transient environment is presented in this work. The first section describes the basic phenomena of radiation interaction with matter. The radiative environments, the main characteristics of laser diodes and the research undertaken on the subject are presented and discussed. The tests on 1300 nm edge emitting laser diode are presented in the second section. The response to a transient ionizing excitation is explored using a 532 nm laser beam. The time of return to steady state after the perturbation is decomposed into several steps: decrease of the optical power during excitation, turn-on delay, relaxation oscillations and optical power offset. Their origins are analyzed using the device structure. To include all the phenomena in a numerical simulation of the device, an individual study of low conductivity materials used for the lateral confinement of the current density is undertaken. The effects of a single particle traversing the optical cavity and an analysis of permanent damages induced by neutrons are also determined. In the last section, 850 nm vertical cavity surface emitting laser diodes (VCSEL) are studied. The behavior of these devices which performances are in constant evolution, is investigated as a function of both temperature and polarization. Then VCSEL are submitted to transient ionizing irradiation and their responses are compared to those of edge emitting diodes. When proton implantation is used in the process, we observe the same behavior for both technologies. VCSEL were submitted to neutron fluence and we have studied the influence of the damages on threshold current, emission patterns and maximum of optical power. (author) [fr
Importance-performance analysis based SWOT analysis
Phadermrod, Boonyarat; Crowder, Richard M.; Wills, Gary B.
2016-01-01
SWOT analysis, a commonly used tool for strategic planning, is traditionally a form of brainstorming. Hence, it has been criticised that it is likely to hold subjective views of the individuals who participate in a brainstorming session and that SWOT factors are not prioritized by their significance thus it may result in an improper strategic action. While most studies of SWOT analysis have only focused on solving these shortcomings separately, this study offers an approach to diminish both s...
DEFF Research Database (Denmark)
Rømer, Daniel; Johansen, Per; Pedersen, Henrik C.
2013-01-01
A fast rotating 1500 rpm radial piston digital displacement motor connected to a 350 bar high pressure manifold is simulated by means of transient 3D CFD analysis of a single pressure chamber. The analysis includes dynamic piston and valve movement, influencing the boundaries of the fluid domain....... Movement of the low and high pressure valves is coupled to fluid forces and valve actuation is included to control the valve movement according to the pressure cycle of the digital displacement motor. The fluid domain is meshed using a structured/unstructured non-conformal mesh, which is updated throughout...... the simulation using layering zones as required by the moving fluid boundaries. The effect of cavitation at low pressures is included by implementing a pressure dependent density, based on an effective bulk modulus model. In addition, pressure dependent oil viscosity is included in the analysis. As a result...
Transient states analysis of CI engine injectors with the use of optical methods
Skowron, M.; Pielecha, I.; Wisłocki, K.
2016-09-01
The main aim of research was to define real injection time delay against the time of electrical control signal for piezoelectric and electromagnetic diesel fuel injectors. The second objective of this work was the evaluation of influence of typical injection parameters on this delay. The analysis was focused on the occurrence of appropriate control signals recorded with the use of fast-varying data acquisition system and compared with the data recorded by high speed camera. The tests were conducted in constant volume chamber for different injector types used in combustion engines with direct injection of diesel fuel. The tests were performed under variable conditions: different fuel pressure, air back-pressure and injection duration time.
Transient Torsional Analysis of a Belt Conveyor Drive with Pneumatic Flexible Shaft Coupling
Directory of Open Access Journals (Sweden)
Kaššay Peter
2017-03-01
Full Text Available Development and application of pneumatic flexible shaft couplings have been in the center of our department research activities for a long time. These couplings are able to change torsional stiffness by changing pressure in their flexible elements – air bellows. Until now we have dealt with the use of pneumatic flexible shaft couplings for tuning mechanical systems working with periodically alternating load torque at steady state. Some mechanical systems, however, operate with a static load torque at constant speed (e.g. hoists, elevators, etc., where it is necessary to consider the suitability of shaft coupling in terms of load torque at transient conditions (run-up and braking. Therefore we decided to analyze the use of pneumatic flexible shaft couplings also in this type of mechanical systems on an example of conveyor belt drive.
Vectorization of LWR transient analysis code RELAP5/MOD1 and its effect
International Nuclear Information System (INIS)
Ishiguro, Misako; Harada, Hiroo; Shinozawa, Naohisa; Naraoka, Ken-itsu
1985-03-01
The RELAP5/MOD1 is a large thermal-hydraulic code to analyze LWR LOCA and non-LOCA transients. The code originally was designed for use on a CDC Cyber-176. This report documents vectorization of the RELAP5/MOD1 code conducted for the purpose of efficient use of VP-100 (peak speed 250 MFLOPS, clock period 7.5 ns) at the JAERI. The code was vectorized using the junction and volume level parallelisms in the hydrodynamic calculations, and the heat-structure and heat-mesh level in the heat conduction calculations. The vectorized version runs as much as 2.4 to 2.8 times faster than the original scalar version, while the speedup ratio is dependent on the number of spactial cells included in the problem. (author)
Busy period analysis, rare events and transient behavior in fluid flow models
Directory of Open Access Journals (Sweden)
Søren Asmussen
1994-01-01
Full Text Available We consider a process {(Jt,Vt}t≥0 on E×[0,∞, such that {Jt} is a Markov process with finite state space E, and {Vt} has a linear drift ri on intervals where Jt=i and reflection at 0. Such a process arises as a fluid flow model of current interest in telecommunications engineering for the purpose of modeling ATM technology. We compute the mean of the busy period and related first passage times, show that the probability of buffer overflow within a busy cycle is approximately exponential, and give conditioned limit theorems for the busy cycle with implications for quick simulation. Further, various inequalities and approximations for transient behavior are given. Also explicit expressions for the Laplace transform of the busy period are found. Mathematically, the key tool is first passage probabilities and exponential change of measure for Markov additive processes.
Transient analysis of nuclear graphite oxidation for high temperature gas cooled reactor
International Nuclear Information System (INIS)
Xu Wei; Shi Lei; Zheng Yanhua
2014-01-01
Graphite is widely used in the high temperature gas-cooled reactor pebble-bed modular (HTR-PM). There are about 420,000 spherical fuel elements in the reactor core. The amount of graphite matrix in the reactor is dozens of tons. In normal operating conditions or water/air ingress accident, the matrix graphite of spherical fuel element may be oxidized by air or steam. This paper developed a new graphite oxidation model, considering the graphite porosity variation with the fractional burn-off. This model also considered the effects of microstructure development during oxidation and the resulting changing of diffusivity as well as the oxidation rate. Based on this theoretical model, this paper analyzed penetration depth and the graphite transient oxidation by oxygen. In addition, this paper obtained the weight loss ratio and oxidation rate trend over time and space. (author)
Transient line starting analysis of the ultra-high speed PMSM
Directory of Open Access Journals (Sweden)
Wenjie Cheng
2017-05-01
Full Text Available Aiming at the ultra high speed permanent magnet synchronous motor (PMSM supported by gas foil bearings (GFBs, this paper calculates the transient line starting of the motor. Firstly, the start effect of the rotor composed of cylindrical PM and stainless steel sleeve is studied. Then, in order to enhance the start torque, copper ring, nickel ring and copper squirrel-cage are introduced in the rotor and their start effect are analysed, respectively. It can be found that the rotor including nickel ring can be accelerated to set speed, but all the other rotors are failed due to the higher PM and braking torques. It can be concluded that some material owning slight large relative permeability can be applied in the rotor to reduce the PM field and contribute to start by using the line-start method.
International Nuclear Information System (INIS)
Itoh, Hiroyasu; Tomioka, Satoshi; Enoto, Takeaki
1994-01-01
Wave information about micro-pulses of electron beams is required in order to control an electron beam precisely, and it may be possible to obtain such information by analyzing the spectrum of the electromagnetic field created by a linac electron beam. In order to derive the spectrum, we measured the spatial distribution generated by a standing wave. Furthermore we calculated the transient electromagnetic field excited by a bunched electron beam, using the finite-difference time-domain (FD-TD) method, and compared two spectra in the frequency domain, into which the calculated value in time variation and the measured values in spatial variation are transformed by using the fast Fourier transform (FFT) respectively. (author)
Gao, B. C.; Meng, X. K.; Shen, M. X.; Peng, X. D.
2016-05-01
A transient thermal-mechanical coupling model for a contacting mechanical seal during start-up has been developed. It takes into consideration the coupling relationship among thermal-mechanical deformation, film thickness, temperature and heat generation. The finite element method and multi-iteration technology are applied to solve the temperature distribution and thermal-mechanical deformation as well as their evolution behavior. Results show that the seal gap transforms from negative coning to positive coning and the contact area of the mechanical seal gradually decreases during start-up. The location of the maximum temperature and maximum contact pressure move from the outer diameter to inside diameter. The heat generation and the friction torque increase sharply at first and then decrease. Meanwhile, the contact force decreases and the fluid film force and leakage rate increase.
Analysis of a Microgrid under Transient Conditions Using Voltage and Frequency Controller
Directory of Open Access Journals (Sweden)
Monika Jain
2012-01-01
Full Text Available This paper presents an investigation of voltage-and-frequency-(VF- based battery energy storage system (BESS controller used in micro grid for analyzing the optimum capability of plant. Microgrid is formed by using three hydropower plants feeding three-phase four-wire load. The proposed controller is used for load balancing, harmonic elimination, load leveling, and neutral current compensation. The proposed BESS controller permits the selection of an optimum voltage level of battery and allows independent current control of each phase. The main emphasis is given on maintaining constant voltage and frequency within the micro grid during transient conditions. Micro grid with power plant and its controller is modeled in MATLAB/Simulink using Power System Blockset (PSB toolboxes.
Directory of Open Access Journals (Sweden)
Younsi Ramdane
2015-01-01
Full Text Available In the present paper, three-dimensional equations for coupled heat and mass conservation equations for wood are solved to study the transient heat and mass transfer during high thermal treatment of wood. The model is based on Luikov’s approach, including pressure. The model equations are solved numerically by the commercial package FEMLfor the temperature and moisture content histories under different treatment conditions. The simulation of the proposed conjugate problem allows the assessment of the effect of the heat and mass transfer within wood. A parametric study was also carried out to determine the effects of several parameters such as initial moisture content and the sample thickness on the temperature, pressure and moisture content distributions within the samples during heat treatment.
Transient analysis of a thermal storage unit involving a phase change material
Griggs, E. I.; Pitts, D. R.; Humphries, W. R.
1974-01-01
The transient response of a single cell of a typical phase change material type thermal capacitor has been modeled using numerical conductive heat transfer techniques. The cell consists of a base plate, an insulated top, and two vertical walls (fins) forming a two-dimensional cavity filled with a phase change material. Both explicit and implicit numerical formulations are outlined. A mixed explicit-implicit scheme which treats the fin implicity while treating the phase change material explicitly is discussed. A band algorithmic scheme is used to reduce computer storage requirements for the implicit approach while retaining a relatively fine grid. All formulations are presented in dimensionless form thereby enabling application to geometrically similar problems. Typical parametric results are graphically presented for the case of melting with constant heat input to the base of the cell.
Development and Application of a Plant Code to the Analysis of Transients in Integrated Reactors
International Nuclear Information System (INIS)
Rabiti, A.; Gimenez, M.; Delmastro, D.; Zanocco, P.
2003-01-01
In this work, a secondary system model for a CAREM-25 type nuclear power plant was developed.A two-phase flow homogenous model was used and found adequate for the scope of the present work.A finite difference scheme was used for the numerical implementation of the model.This model was coupled to the HUARPE code, a primary circuit code, in order to obtain a plant code.This plant code was used to analyze the inherent response of the system, without control feedback loops, for a transient of steam generator feed-water mass flow reduction.The results obtained are satisfactory, but a validation against other plant codes is still necessary
Detection and analysis of a transient energy burst with beamforming of multiple teleseismic phases
Retailleau, Lise; Landès, Matthieu; Gualtieri, Lucia; Shapiro, Nikolai M.; Campillo, Michel; Roux, Philippe; Guilbert, Jocelyn
2018-01-01
Seismological detection methods are traditionally based on picking techniques. These methods cannot be used to analyse emergent signals where the arrivals cannot be picked. Here, we detect and locate seismic events by applying a beamforming method that combines multiple body-wave phases to USArray data. This method explores the consistency and characteristic behaviour of teleseismic body waves that are recorded by a large-scale, still dense, seismic network. We perform time-slowness analysis of the signals and correlate this with the time-slowness equivalent of the different body-wave phases predicted by a global traveltime calculator, to determine the occurrence of an event with no a priori information about it. We apply this method continuously to one year of data to analyse the different events that generate signals reaching the USArray network. In particular, we analyse in detail a low-frequency secondary microseismic event that occurred on 2010 February 1. This event, that lasted 1 d, has a narrow frequency band around 0.1 Hz, and it occurred at a distance of 150° to the USArray network, South of Australia. We show that the most energetic phase observed is the PKPab phase. Direct amplitude analysis of regional seismograms confirms the occurrence of this event. We compare the seismic observations with models of the spectral density of the pressure field generated by the interferences between oceanic waves. We attribute the observed signals to a storm-generated microseismic event that occurred along the South East Indian Ridge.
Transient pressure analysis of a volume fracturing well in fractured tight oil reservoirs
Lu, Cheng; Wang, Jiahang; Zhang, Cong; Cheng, Minhua; Wang, Xiaodong; Dong, Wenxiu; Zhou, Yingfang
2017-12-01
This paper presents a semi-analytical model to simulate transient pressure curves for a vertical well with a reconstructed fracture network in fractured tight oil reservoirs. In the proposed model, the reservoir is a composite system and contains two regions. The inner region is described as a formation with a finite conductivity hydraulic fracture network and the flow in the fracture is assumed to be linear, while the outer region is modeled using the classical Warren–Root model where radial flow is applied. The transient pressure curves of a vertical well in the proposed reservoir model are calculated semi-analytically using the Laplace transform and Stehfest numerical inversion. As shown in the type curves, the flow is divided into several regimes: (a) linear flow in artificial main fractures; (b) coupled boundary flow; (c) early linear flow in a fractured formation; (d) mid radial flow in the semi-fractures of the formation; (e) mid radial flow or pseudo steady flow; (f) mid cross-flow; (g) closed boundary flow. Based on our newly proposed model, the effects of some sensitive parameters, such as elastic storativity ratio, cross-flow coefficient, fracture conductivity and skin factor, on the type curves were also analyzed extensively. The simulated type curves show that for a vertical fractured well in a tight reservoir, the elastic storativity ratios and crossflow coefficients affect the time and the degree of crossflow respectively. The pressure loss increases with an increase in the fracture conductivity. To a certain extent, the effect of the fracture conductivity is more obvious than that of the half length of the fracture on improving the production effect. With an increase in the wellbore storage coefficient, the fluid compressibility is so large that it might cover the early stage fracturing characteristics. Linear or bilinear flow may not be recognized, and the pressure and pressure derivative gradually shift to the right. With an increase in the skin
Directory of Open Access Journals (Sweden)
Sungchul Hwang
2016-12-01
Full Text Available Many of the recent projects for new transmission line have considered the high-voltage direct current (HVDC system, owing to the many advantages of the direct current (DC system. The most noteworthy advantage is that a cable can serve as a substitute for the overhead transmission line in residential areas; therefore, the HVDC system application is increasing, and as the number of DC systems in the power system increases, the interaction assessment regarding the HVDC system gains importance. An index named multi-infeed interaction factor (MIIF is commonly used to estimate the interaction between power converters; however, the HVDC system is composed of two converters and a transmission line. The MIIF represents the interaction between the rectifiers and inverters, but not for the whole system. In this work, a method to assess the interaction of the whole system was therefore studied. To decide on the location of the new HVDC transmission system at the planning stage, in consideration of the interaction of the existing DC system, the line flow change distribution factor, according to the HVDC-transmission capacity change, was examined. Also, a power system transient -stability analysis was performed with different HVDC system locations, depending on the distribution factor. The simulation results indicate that when the factor is higher, two HVDC systems have a stronger interaction and are less stable in the transient state.
Energy Technology Data Exchange (ETDEWEB)
Pradhan, Santosh K., E-mail: santosh@aerb.gov.in [Nuclear Safety Analysis Division, Atomic Energy Regulatory Board, Mumbai 400094 (India); Obaidurrahman, K. [Nuclear Safety Analysis Division, Atomic Energy Regulatory Board, Mumbai 400094 (India); Iyer, Kannan N. [Department of Mechanical Engineering, IIT Bombay, Mumbai 400076 (India); Gaikwad, Avinash J. [Nuclear Safety Analysis Division, Atomic Energy Regulatory Board, Mumbai 400094 (India)
2016-04-15
Highlights: • A multi-point kinetics model is developed for RELAP5 system thermal hydraulics code. • Model is validated against extensive 3D kinetics code. • RELAP5 multi-point kinetics formulation is used to investigate critical break for LOCA in PHWR. - Abstract: Point kinetics approach in system code RELAP5 limits its use for many of the reactivity induced transients, which involve asymmetric core behaviour. Development of fully coupled 3D core kinetics code with system thermal-hydraulics is the ultimate requirement in this regard; however coupling and validation of 3D kinetics module with system code is cumbersome and it also requires access to source code. An intermediate approach with multi-point kinetics is appropriate and relatively easy to implement for analysis of several asymmetric transients for large cores. Multi-point kinetics formulation is based on dividing the entire core into several regions and solving ODEs describing kinetics in each region. These regions are interconnected by spatial coupling coefficients which are estimated from diffusion theory approximation. This model offers an advantage that associated ordinary differential equations (ODEs) governing multi-point kinetics formulation can be solved using numerical methods to the desired level of accuracy and thus allows formulation based on user defined control variables, i.e., without disturbing the source code and hence also avoiding associated coupling issues. Euler's method has been used in the present formulation to solve several coupled ODEs internally at each time step. The results have been verified against inbuilt point-kinetics models of RELAP5 and validated against 3D kinetics code TRIKIN. The model was used to identify the critical break in RIH of a typical large PHWR core. The neutronic asymmetry produced in the core due to the system induced transient was effectively handled by the multi-point kinetics model overcoming the limitation of in-built point kinetics model
MONJU fuel pin performance analysis
International Nuclear Information System (INIS)
Kitagawa, H.; Yamanaka, T.; Hayashi, H.
1979-01-01
Monju fuel pin has almost the same properties as other LMFBR fuel pins, i.e. Phenix, PFR, CRBR, but would be irradiated under severe conditions: maximum linear heat rate of 381 watt/cm, hot spot cladding temperature of 675 deg C, peak burnup of 131,000 MWd/t, peak fluence (E greater than 0.1 MeV) of 2.3 10 23 n/cm 2 . In order to understand in-core performance of Monju fuel pin, its thermal and mechanical behaviour was predicted using the fast running performance code SIMPLE. The code takes into account pellet-cladding interaction due to thermal expansion and swelling, gap conductance, structural changes of fuel pellets, fission product gas release with burnup and temperature increase, swelling and creep of fuel pellets, corrosion of cladding due to sodium flow and chemical attack by fission products, and cumulative damage of the cladding due to thermal creep
International Nuclear Information System (INIS)
Droppo, James G.
2004-01-01
An analysis is conducted of the 1996-1998 Hanford tank ventilation studies of average ventilation rates to help define characteristics of shorter term releases. This effort is being conducted as part of the design of tests of Industrial Hygiene's (IH) instrumentation ability to detect transient airborne plumes from tanks using current deployment strategies for tank operations. This analysis has improved our understanding of the variability of hourly average tank ventilation processes. However, the analysis was unable to discern the relative importance of emissions due to continuous releases and short-duration bursts of material. The key findings are as follows: (1) The ventilation of relatively well-sealed, passively ventilated tanks appears to be driven by a combination of pressure, buoyancy, and wind influences. The results of a best-fit analysis conducted with a single data set provide information on the hourly emission variability that IH instrumentation will need to detect. (2) Tank ventilation rates and tank emission rates are not the same. The studies found that the measured infiltration rates for a single tank are often a complex function of air exchanges between tanks and air exchanges with outdoor air. This situation greatly limits the usefulness of the ventilation data in defining vapor emission rates. (3) There is no evidence in the data to discern if the routine tank vapor releases occur over a short time (i.e., a puff) or over an extended time (i.e., continuous releases). Based on this analysis of the tank ventilation studies, it is also noted that (1) the hourly averaged emission peaks from the relatively well-sealed passively-vented tanks (such as U-103) are not a simple function of one meteorological parameter--but the peaks often are the result of the coincidence of temporal maximums in pressure, temperature, and wind influences and (2) a mechanistic combination modeling approach and/or field studies may be necessary to understand the short
Analysis of fast reactor steam generator performance
International Nuclear Information System (INIS)
Hulme, G.; Curzon, A.F.
1992-01-01
A computer model for the prediction of flow and temperature fields within a fast reactor steam generator unit is described. The model combines a commercially available computational fluid dynamics (CFD) solver (PHOENICS) with a steam-tube calculation and provides solutions for the fully coupled flow and temperature fields on both the shell side and the tube side. The model includes the inlet and outlet headers and the bottom end stagnant zone. It also accounts for the effects of support grids and edge-gaps. Two and three dimensional and transient calculations have been performed for both straight tube and J-tube units. Examples of the application of the model are presented. (7 figures) (Author)
Model Performance Evaluation and Scenario Analysis (MPESA)
Model Performance Evaluation and Scenario Analysis (MPESA) assesses the performance with which models predict time series data. The tool was developed Hydrological Simulation Program-Fortran (HSPF) and the Stormwater Management Model (SWMM)
Time-step selection considerations in the analysis of reactor transients with DIF3D-K
International Nuclear Information System (INIS)
Taiwo, T.A.; Khalil, H.S.; Cahalan, J.E.; Morris, E.E.
1993-01-01
The DIF3D-K code solves the three-dimensional, time-dependent multigroup neutron diffusion equations by using a nodal approach for spatial discretization and either the theta method or one of three space-time factorization approaches for temporal integration of the nodal equations. The three space-time factorization options (namely, improved quasistatic, adiabatic, and conventional point kinetics) were implemented because of their potential efficiency advantage for the analysis of transients in which the flux shape changes more slowly than its amplitude. In this paper, we describe the implementation of DIF3D-K as the neutronics module within the SAS-HWR accident analysis code. We also describe the neuronic-related time-step selection algorithms and their influence on the accuracy and efficiency of the various solution options
Time-step selection considerations in the analysis of reactor transients with DIF3D-K
International Nuclear Information System (INIS)
Taiwo, T.A.; Khalil, H.S.; Cahalan, J.E.; Morris, E.E.
1993-01-01
The DIF3D-K code solves the three-dimensional, time-dependent multigroup neutron diffusion equations by using a nodal approach for spatial discretization and either the theta method or one of three space-time factorization approaches for temporal integration of the nodal equations. The three space-time factorization options (namely, improved quasistatic, adiabatic and conventional point kinetics) were implemented because of their potential efficiency advantage for the analysis of transients in which the flux shape changes more slowly than its amplitude. Here we describe the implementation of DIF3D-K as the neutronics module within the SAS-HWR accident analysis code. We also describe the neutronics-related time step selection algorithms and their influence on the accuracy and efficiency of the various solution options
Nisulescu, Valentin; Ivan, Florian; Iozsa, Daniel; Banca, Gheorghe
2017-10-01
It is known that current vehicles must meet stringent demands on pollution limits but also must meet and the dynamical and economical performances. In this context the transient regimes are those affecting this performances, in this paper are presenting the results of the simulations for these regimes using a vehicle powered with two energy sources gasoline and LPG. Have been selected the transient regimes characteristic for NMVEG cycle (New Motor Vehicle Emissions Group). The simulation is performed using AMESim platform and the results have allowed meticulous interpretations for the 16 regimes of acceleration. The results obtained from the simulation will be validated experimentally.
Transient Heat Transfer Analysis For Ion-Exchange Waste Removal Process
International Nuclear Information System (INIS)
Lee, S.
2010-01-01
The small column ion exchange (SCIX) process treats low curie salt (LCS) waste before feeding it to the saltstone facility to be made into grout. Through this process, radioactive cesium from the salt solution is absorbed into the CST bed. A CST column loaded with radioactive cesium will generate significant heat from radiolytic decay. If engineering designs of the CST sorption column can not handle this thermal load, hot spots may develop locally within the column and degrade the performance of the ion-exchange process. The CST starts to degrade at about 80 to 85 C, and the CST completely changes to another material above 120 C. In addition, the process solution will boil around 130 C. If the column boiled dry, the sorbent could plug the column and require replacement of the column module. The objective of the present work is to compute temperature distributions across the column as a function of transit time after the initiation of accidents when there is loss of the salt solution flow in the CST column under abnormal conditions of the process operations. In this situation, the customer requested that the calculations should be conservative in that the model results would show the maximum centerline temperatures achievable by the CST design configurations. The thermal analysis results will be used to evaluate the fluid temperature distributions and the process component temperatures within the ion exchange system. This information will also assist in the system design and maintenance.
Transient Analysis of Lumped Circuit Networks Loaded Thin Wires By DGTD Method
Li, Ping
2016-03-31
With the purpose of avoiding very fine mesh cells in the proximity of a thin wire, the modified telegrapher’s equations (MTEs) are employed to describe the thin wire voltage and current distributions, which consequently results in reduced number of unknowns and augmented Courant-Friedrichs-Lewy (CFL) number. As hyperbolic systems, both the MTEs and the Maxwell’s equations are solved by the discontinuous Galerkin time-domain (DGTD) method. In realistic situations, the thin wires could be either driven or loaded by circuit networks. The thin wire-circuit interface performs as a boundary condition for the thin wire solver, where the thin wire voltage and current used for the incoming flux evaluation involved in the DGTD analyzed MTEs are not available. To obtain this voltage and current, an auxiliary current flowing through the thin wire-circuit interface is introduced at each interface. Corresponding auxiliary equations derived from the invariable property of characteristic variable for hyperbolic systems are developed and solved together with the circuit equations established by the modified nodal analysis (MNA) modality. Furthermore, in order to characterize the field and thin wire interactions, a weighted electric field and a volume current density are added into the MTEs and Maxwell-Ampere’s law equation, respectively. To validate the proposed algorithm, three representative examples are presented.
Bronuzzi, J.; Mapelli, A.; Sallese, J. M.
2016-12-01
A silicon wafer bonding technique has been recently proposed for the fabrication of monolithic silicon radiation detectors. This new process would enable direct bonding of a read-out electronic chip wafer on a highly resistive silicon substrate wafer. Therefore, monolithic silicon detectors could be fabricated in this way which would allow the free choice of electronic chips and high resistive silicon bulk, even from different providers. Moreover, a monolithic detector with a high resistive bulk would also be available. Electrical properties of the bonded interface are then critical for this application. Indeed, mobile charges generated by radiation inside the bonded bulk are expected to transit through the interface to be collected by the read-out electronics. In order to characterize this interface, the concept of Transient Current Technique (TCT) has been explored by means of numerical simulations combined with a physics based analytical model. In this work, the analytical model giving insight into the physics behind the TCT dependence upon interface traps is validated using both TCAD simulations and experimental measurements.
A thermal-hydraulic code for transient analysis in a channel with a rod bundle
Energy Technology Data Exchange (ETDEWEB)
Khodjaev, I.D. [Research & Engineering Centre of Nuclear Plants Safety, Electrogorsk (Russian Federation)
1995-09-01
The paper contains the model of transient vapor-liquid flow in a channel with a rod bundle of core of a nuclear power plant. The computer code has been developed to predict dryout and post-dryout heat transfer in rod bundles of nuclear reactor core under loss-of-coolant accidents. Economizer, bubble, dispersed-annular and dispersed regimes are taken into account. The computer code provides a three-field representation of two-phase flow in the dispersed-annular regime. Continuous vapor, continuous liquid film and entrained liquid drops are three fields. For the description of dispersed flow regime two-temperatures and single-velocity model is used. Relative droplet motion is taken into account for the droplet-to-vapor heat transfer. The conservation equations for each of regimes are solved using an effective numerical technique. This technique makes it possible to determine distribution of the parameters of flows along the perimeter of fuel elements. Comparison of the calculated results with the experimental data shows that the computer code adequately describes complex processes in a channel with a rod bundle during accident.
Uysal, Ismail Enes
2016-08-09
Transient electromagnetic interactions on plasmonic nanostructures are analyzed by solving the Poggio-Miller-Chan-Harrington-Wu-Tsai (PMCHWT) surface integral equation (SIE). Equivalent (unknown) electric and magnetic current densities, which are introduced on the surfaces of the nanostructures, are expanded using Rao-Wilton-Glisson and polynomial basis functions in space and time, respectively. Inserting this expansion into the PMCHWT-SIE and Galerkin testing the resulting equation at discrete times yield a system of equations that is solved for the current expansion coefficients by a marching on-in-time (MOT) scheme. The resulting MOT-PMCHWT-SIE solver calls for computation of additional convolutions between the temporal basis function and the plasmonic medium\\'s permittivity and Green function. This computation is carried out with almost no additional cost and without changing the computational complexity of the solver. Time-domain samples of the permittivity and the Green function required by these convolutions are obtained from their frequency-domain samples using a fast relaxed vector fitting algorithm. Numerical results demonstrate the accuracy and applicability of the proposed MOT-PMCHWT solver. © 2016 Optical Society of America.
Transient Mass-loss Analysis of Solar Observations Using Stellar Methods
International Nuclear Information System (INIS)
Crosley, M. K.; Norman, C.; Osten, R. A.
2017-01-01
Low-frequency dynamic spectra of radio bursts from nearby stars offer the best chance to directly detect the stellar signature of transient mass loss on low-mass stars. Crosley et al. (2016) proposes a multi-wavelength methodology to determine coronal mass ejection (CME) parameters, such as speed, mass, and kinetic energy. We test the validity and accuracy of the results derived from the methodology by using Geostationary Operational Environmental Satellite X-ray observations and Bruny Island Radio Spectrometer radio observations. These are analogous observations to those that would be found in the stellar studies. Derived results from these observations are compared to direct white light measurements of the Large Angle and Spectrometric Coronagraph. We find that, when a pre-event temperature can be determined, the accuracy of CME speeds are within a few hundred km s −1 , and are reliable when specific criteria has been met. CME mass and kinetic energies are only useful in determining the approximate order of magnitude measurements when considering the large errors associated to them. These results will be directly applicable to the interpretation of any detected stellar events and the derivation of stellar CME properties.
Transient Mass-loss Analysis of Solar Observations Using Stellar Methods
Crosley, M. K.; Osten, R. A.; Norman, C.
2017-08-01
Low-frequency dynamic spectra of radio bursts from nearby stars offer the best chance to directly detect the stellar signature of transient mass loss on low-mass stars. Crosley et al. (2016) proposes a multi-wavelength methodology to determine coronal mass ejection (CME) parameters, such as speed, mass, and kinetic energy. We test the validity and accuracy of the results derived from the methodology by using Geostationary Operational Environmental Satellite X-ray observations and Bruny Island Radio Spectrometer radio observations. These are analogous observations to those that would be found in the stellar studies. Derived results from these observations are compared to direct white light measurements of the Large Angle and Spectrometric Coronagraph. We find that, when a pre-event temperature can be determined, the accuracy of CME speeds are within a few hundred km s-1, and are reliable when specific criteria has been met. CME mass and kinetic energies are only useful in determining the approximate order of magnitude measurements when considering the large errors associated to them. These results will be directly applicable to the interpretation of any detected stellar events and the derivation of stellar CME properties.
Numerical Analysis of the Effect of T-tubule Location on Calcium Transient in Ventricular Myocytes
George, Uduak Z.; Wang, Jun; Yu, Zeyun
2013-01-01
Intracellular calcium (Ca2+) signaling in cardiac myocytes is vital for proper functioning of the heart. Understanding the intracellular Ca2+ dynamics would give an insight into the functions of normal and diseased hearts. In the current study, spatiotemporal Ca2+ dynamics is investigated in ventricular myocytes by considering Ca2+ release and re-uptake via sarcolemma and transverse tubules (T-tubules), Ca2+ diffusion and buffering in the cytosol, and the blockade of Ca2+ activities associated with the sarcoplasmic reticulum. This study is carried out using a three dimensional (3D) geometric model of a branch of T-tubule extracted from the electron microscopy (EM) images of a partial ventricular myocyte. Mathematical modeling is done by using a system of partial differential equations involving Ca2+ , buffers, and membrane channels. Numerical simulation results suggest that a lack of T-tubule structure at the vicinity of the cell surface could increase the peak time of Ca2+ concentration in myocytes. The results also show that T-tubules and mobile buffers play an important role in the regulation of Ca2+ transient in ventricular myocytes. PMID:24212025
Non-modal stability analysis and transient growth in a magnetized Vlasov plasma
Ratushnaya, V.
2014-12-01
Collisionless plasmas, such as those encountered in tokamaks, exhibit a rich variety of instabilities. The physical origin, triggering mechanisms and fundamental understanding of many plasma instabilities, however, are still open problems. We investigate the stability properties of a 3-dimensional collisionless Vlasov plasma in a stationary homogeneous magnetic field. We narrow the scope of our investigation to the case of Maxwellian plasma and examine its evolution with an electrostatic approximation. For the first time using a fully kinetic approach we show the emergence of the local instability, a transient growth, followed by classical Landau damping in a stable magnetized plasma. We show that the linearized Vlasov operator is non-normal leading to the algebraic growth of the perturbations using non-modal stability theory. The typical time scales of the obtained instabilities are of the order of several plasma periods. The first-order distribution function and the corresponding electric field are calculated and the dependence on the magnetic field and perturbation parameters is studied. Our results offer a new scenario of the emergence and development of plasma instabilities on the kinetic scale.
Transient Mass-loss Analysis of Solar Observations Using Stellar Methods
Energy Technology Data Exchange (ETDEWEB)
Crosley, M. K.; Norman, C. [Johns Hopkins University, Department of Physics and Astronomy, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Osten, R. A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
2017-08-10
Low-frequency dynamic spectra of radio bursts from nearby stars offer the best chance to directly detect the stellar signature of transient mass loss on low-mass stars. Crosley et al. (2016) proposes a multi-wavelength methodology to determine coronal mass ejection (CME) parameters, such as speed, mass, and kinetic energy. We test the validity and accuracy of the results derived from the methodology by using Geostationary Operational Environmental Satellite X-ray observations and Bruny Island Radio Spectrometer radio observations. These are analogous observations to those that would be found in the stellar studies. Derived results from these observations are compared to direct white light measurements of the Large Angle and Spectrometric Coronagraph. We find that, when a pre-event temperature can be determined, the accuracy of CME speeds are within a few hundred km s{sup −1}, and are reliable when specific criteria has been met. CME mass and kinetic energies are only useful in determining the approximate order of magnitude measurements when considering the large errors associated to them. These results will be directly applicable to the interpretation of any detected stellar events and the derivation of stellar CME properties.
McNally, Richard J Q; Rankin, Judith; Shirley, Mark D F; Rushton, Stephen P; Pless-Mulloli, Tanja
2008-10-01
Whilst maternal age is an established risk factor for Patau syndrome (trisomy 13), Edwards syndrome (trisomy 18) and Down syndrome (trisomy 21), the aetiology and contribution of genetic and environmental factors remains unclear. We analysed for space-time clustering using high quality fully population-based data from a geographically defined region. The study included all cases of Patau, Edwards and Down syndrome, delivered during 1985-2003 and resident in the former Northern Region of England, including terminations of pregnancy for fetal anomaly. We applied the K-function test for space-time clustering with fixed thresholds of close in space and time using residential addresses at time of delivery. The Knox test was used to indicate the range over which the clustering effect occurred. Tests were repeated using nearest neighbour (NN) thresholds to adjust for variable population density. The study analysed 116 cases of Patau syndrome, 240 cases of Edwards syndrome and 1084 cases of Down syndrome. There was evidence of space-time clustering for Down syndrome (fixed threshold of close in space: P = 0.01, NN threshold: P = 0.02), but little or no clustering for Patau (P = 0.57, P = 0.19) or Edwards (P = 0.37, P = 0.06) syndromes. Clustering of Down syndrome was associated with cases from more densely populated areas and evidence of clustering persisted when cases were restricted to maternal age syndrome suggests an aetiological role for transient environmental factors, such as infections.
Techno-economic analysis of a transient plant-based platform for monoclonal antibody production
Nandi, Somen; Kwong, Aaron T.; Holtz, Barry R.; Erwin, Robert L.; Marcel, Sylvain; McDonald, Karen A.
2016-01-01
ABSTRACT Plant-based biomanufacturing of therapeutic proteins is a relatively new platform with a small number of commercial-scale facilities, but offers advantages of linear scalability, reduced upstream complexity, reduced time to market, and potentially lower capital and operating costs. In this study we present a detailed process simulation model for a large-scale new “greenfield” biomanufacturing facility that uses transient agroinfiltration of Nicotiana benthamiana plants grown hydroponically indoors under light-emitting diode lighting for the production of a monoclonal antibody. The model was used to evaluate the total capital investment, annual operating cost, and cost of goods sold as a function of mAb expression level in the plant (g mAb/kg fresh weight of the plant) and production capacity (kg mAb/year). For the Base Case design scenario (300 kg mAb/year, 1 g mAb/kg fresh weight, and 65% recovery in downstream processing), the model predicts a total capital investment of $122 million dollars and cost of goods sold of $121/g including depreciation. Compared with traditional biomanufacturing platforms that use mammalian cells grown in bioreactors, the model predicts significant reductions in capital investment and >50% reduction in cost of goods compared with published values at similar production scales. The simulation model can be modified or adapted by others to assess the profitability of alternative designs, implement different process assumptions, and help guide process development and optimization. PMID:27559626
International Nuclear Information System (INIS)
Moinereau, D.; Dahl, A.; Wadier, Y.
2005-01-01
The Reactor Pressure Vessel (RPV) is an essential component liable to limit the lifetime duration of PWR plants. The assessment of defects in RPV subjected to PTS transients made at an European level do not always account the beneficial effect of load history (warm pre-stress WPS). A 3-year Research and Development program-SMILE-has been started in January 2002 as part of the 5th Framework Program of the European Atomic Energy Community (EURATOM). The SMILE project-Structural Margin Improvements in aged embrittled RPV with Load history Effect-is one of a cluster of 5th framework projects in the area of Plant Life Management. It aims to give sufficient elements to demonstrate, to model and to validate the beneficial WPS effect in a RPV integrity assessment. Within the framework of the project, an important experimental work has been conducted including WPS type experiments on CT specimens and a PTS type transient experiment on a large component. The WPS type experiment on the cylinder has been successfully conducted by MPA Stuttgart with a final brittle failure during the reloading. The present paper describes shortly the experiment and presents the corresponding analyses based on engineering methods, finite element elastic-plastic computations, and local approach to fracture. The results are in good agreement with the experimental observations. Very significant margins are underlined, with an effective important increase of the material resistance regarding the risk of brittle failure. (authors)
A Novel Method for Performance Analysis of Compartmentalized Reservoirs
Directory of Open Access Journals (Sweden)
Shahamat Mohammad Sadeq
2016-05-01
Full Text Available This paper presents a simple analytical model for performance analysis of compartmentalized reservoirs producing under Constant Terminal Rate (CTR and Constant Terminal Pressure (CTP. The model is based on the well-known material balance and boundary dominated flow equations and is written in terms of capacitance and resistance of a production and a support compartment. These capacitance and resistance terms account for a combination of reservoir parameters which enable the developed model to be used for characterizing such systems. In addition to considering the properties contrast between the two reservoir compartments, the model takes into account existence of transmissibility barriers with the use of resistance terms. The model is used to analyze production performance of unconventional reservoirs, where the multistage fracturing of horizontal wells effectively creates a Stimulated Reservoir Volume (SRV with an enhanced permeability surrounded by a non-stimulated region. It can also be used for analysis of compartmentalized conventional reservoirs. The analytical solutions provide type curves through which the controlling reservoirs parameters of a compartmentalized system can be estimated. The contribution of the supporting compartment is modeled based on a boundary dominated flow assumption. The transient behaviour of the support compartment is captured by application of “distance of investigation” concept. The model shows that depletion of the production and support compartments exhibit two unit slopes on a log-log plot of pressure versus time for CTR. For CTP, however, the depletions display two exponential declines. The depletion signatures are separated by transition periods, which depend on the contribution of the support compartment (i.e. transient or boundary dominated flow. The developed equations can be implemented easily in a spreadsheet application, and are corroborated with the use of a numerical simulation. The study
Clinical analysis of 65 cases of hyperemesis gravidarum with gestational transient thyrotoxicosis.
Sun, Shuiya; Qiu, Xia; Zhou, Jiaqiang
2014-06-01
We investigated thyroid function and the impact of gestational transient thyrotoxicosis (GTT) on pregnancy outcome in patients with hyperemesis gravidarum (HG; n = 143) who were hospitalized for rehydration. Serum thyroid-stimulating hormone (TSH), free T3 (FT3), free T4 (FT4), thyroid globulin antibody (TgAb), thyroid peroxidase antibody (TPOAb) and hCG were measured after admission. The total prevalence of thyrotoxicosis in HG was 48.3%; GTT was the main form (45.5%). The total incidence of GTT increased significantly if serum hCG was more than 80,000 IU/L, subclinical GTT if serum hCG was 80,000-140,000 IU/L and clinical GTT if serum hCG was more than 180,000 IU/L. GTT did not require antithyroid therapy. The course of TSH, FT3 and FT4 were followed in 34 cases of GTT; thyroid function normalized by the second trimester. Of 65 patients with GTT, two underwent abortions due to unplanned pregnancies, two delivered prematurely and two infants had macrosomia. There were no other complications. All newborns (n = 63) of mothers with GTT had normal TSH levels. GTT is common in HG. The severity of GTT is related to serum hCG levels. In patients with HG and GTT, thyroid function normalized by the second trimester without antithyroid treatment. GTT did not affect pregnancy outcomes. © 2014 The Authors. Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology.
Turner, Grace M; Calvert, Melanie; Feltham, Max G; Ryan, Ronan; Finnikin, Samuel; Marshall, Tom
2018-03-01
Primary prevention of stroke and transient ischemic attack (TIA) is important to reduce the burden of these conditions; however, prescribing of prevention drugs is suboptimal. We aimed to identify individual clinical and demographic characteristics associated with potential missed opportunities for prevention therapy with lipid-lowering, anticoagulant, or antihypertensive drugs before stroke/TIA. We analyzed anonymized electronic primary care records from a UK primary care database that covers 561 family practices. Patients with first-ever stroke/TIA, ≥18 years, with diagnosis between January 1, 2009, and December 31, 2013, were included. Missed opportunities for prevention were defined as people with clinical indications for lipid-lowering, anticoagulant, or antihypertensive drugs but not prescribed these drugs before their stroke/TIA. Mixed-effect logistic regression models evaluated the relationship between missed opportunities and individual clinical/demographic characteristics. The inclusion criteria were met by 29 043 people with stroke/TIA. Patients with coronary heart disease, chronic kidney disease, peripheral arterial disease, or diabetes mellitus were at less risk of a missed opportunity for prescription of lipid-lowering and antihypertensive drugs. However, patients with a 10-year cardiovascular disease risk ≥20% but without these diagnoses had increased risk of having a missed opportunity for prescription of lipid-lowering drugs or antihypertensive drugs. Women were less likely to be prescribed anticoagulants but more likely to be prescribed antihypertensive drugs. The elderly (≥85 years of age) were less likely to be prescribed all 3 prevention drugs, compared with people aged 75 to 79 years. Knowing the patient characteristics predictive of missed opportunities for stroke prevention may help primary care identify and appropriately manage these patients. Improving the management of these groups may reduce their risk and potentially prevent
Directory of Open Access Journals (Sweden)
Nadeem Shaukat
2017-08-01
Full Text Available With ever-advancing computer technology, the Monte Carlo (MC neutron transport calculation is expanding its application area to nuclear reactor transient analysis. Dynamic MC (DMC neutron tracking for transient analysis requires efficient algorithms for delayed neutron generation, neutron population control, and initial condition modeling. In this paper, a new MC steady-state simulation method based on time-dependent MC neutron tracking is proposed for steady-state initial condition modeling; during this process, prompt neutron sources and delayed neutron precursors for the DMC transient simulation can easily be sampled. The DMC method, including the proposed time-dependent DMC steady-state simulation method, has been implemented in McCARD and applied for two-dimensional core kinetics problems in the time-dependent neutron transport benchmark C5G7-TD. The McCARD DMC calculation results show good agreement with results of a deterministic transport analysis code, nTRACER.
Power and performance software analysis and optimization
Kukunas, Jim
2015-01-01
Power and Performance: Software Analysis and Optimization is a guide to solving performance problems in modern Linux systems. Power-efficient chips are no help if the software those chips run on is inefficient. Starting with the necessary architectural background as a foundation, the book demonstrates the proper usage of performance analysis tools in order to pinpoint the cause of performance problems, and includes best practices for handling common performance issues those tools identify. Provides expert perspective from a key member of Intel's optimization team on how processors and memory
International Nuclear Information System (INIS)
Bekstein, A; De Urquijo, J; Rodríguez-Luna, J C; Juárez, A M; Ducasse, O
2012-01-01
We present in this paper the interpretation and analysis of transient pulses from a pulsed Townsend experiment by solving the continuity equations of the charged carriers (electrons and ions) involved in the avalanche. The set of second order partial differential equations is solved by SIMAV, a simulator designed specifically for the pulsed Townsend avalanche. Complex situations involving processes such as electron detachment, ion-molecule reactions, Penning ionization and secondary electron emission from ion impact at the cathode, virtually impossible to solve analytically, are discussed here to illustrate the capability of the simulator to help explain the various reaction processes involved in the avalanche, and also to derive some of the transport and reaction coefficients.
Directory of Open Access Journals (Sweden)
Sohel Rana
2014-01-01
Full Text Available Non-Fourier heat conduction model with dual phase lag wave-diffusion model was analyzed by using well-conditioned asymptotic wave evaluation (WCAWE and finite element method (FEM. The non-Fourier heat conduction has been investigated where the maximum likelihood (ML and Tikhonov regularization technique were used successfully to predict the accurate and stable temperature responses without the loss of initial nonlinear/high frequency response. To reduce the increased computational time by Tikhonov WCAWE using ML (TWCAWE-ML, another well-conditioned scheme, called mass effect (ME T-WCAWE, is introduced. TWCAWE with ME (TWCAWE-ME showed more stable and accurate temperature spectrum in comparison to asymptotic wave evaluation (AWE and also partial Pade AWE without sacrificing the computational time. However, the TWCAWE-ML remains as the most stable and hence accurate model to analyze the fast transient thermal analysis of non-Fourier heat conduction model.
The model of double-cage induction motor for the analysis of thermal fields in transient operations
Directory of Open Access Journals (Sweden)
Mróz Jan
2017-06-01
Full Text Available Emergency motor switch-on happens occasionally while operating a doublesquirrel- cage motor at full supply voltage with the rotor blocked (e.g., in coal mills. After releasing the blockage, the by now heated motor is started up again. However, the mechanical stress caused by the increased temperature poses considerable hazards to the squirrel-cage winding. This paper presents a double-cage induction motor model for analysis of thermal fields in transient operation. The thermal field for the rotor of a doublesquirrel- cage motor of soldered or cast structure, operating in the conditions described, has been calculated in the present paper using a thermal network method. Measurement results have been presented for the double-squirrel-cage winding temperature for a soldered cage construction in the blocked rotor state.
Foster, Winfred A., Jr.; Crowder, Winston; Steadman, Todd E.
2014-01-01
This paper presents the results of statistical analyses performed to predict the thrust imbalance between two solid rocket motor boosters to be used on the Space Launch System (SLS) vehicle. Two legacy internal ballistics codes developed for the Space Shuttle program were coupled with a Monte Carlo analysis code to determine a thrust imbalance envelope for the SLS vehicle based on the performance of 1000 motor pairs. Thirty three variables which could impact the performance of the motors during the ignition transient and thirty eight variables which could impact the performance of the motors during steady state operation of the motor were identified and treated as statistical variables for the analyses. The effects of motor to motor variation as well as variations between motors of a single pair were included in the analyses. The statistical variations of the variables were defined based on data provided by NASA's Marshall Space Flight Center for the upgraded five segment booster and from the Space Shuttle booster when appropriate. The results obtained for the statistical envelope are compared with the design specification thrust imbalance limits for the SLS launch vehicle
Analysis of the VVER-1000 coolant transient benchmark phase 1 with the code system RELAP5/PARCS
International Nuclear Information System (INIS)
Victor Hugo Sanchez Espinoza
2005-01-01
Full text of publication follows: As part of the reactor dynamics activities of FZK/IRS, the qualification of best-estimate coupled code systems for reactor safety evaluations is a key step toward improving their prediction capability and acceptability. The VVER-1000 Coolant Transient Benchmark Phase 1 represents an excellent opportunity to validate the simulation capability of the coupled code system RELAP5/PACRS regarding both the thermal hydraulic plant response (RELAP5) using measured data obtained during commissioning tests at the Kozloduy nuclear power plant unit 6 and the neutron kinetics models of PARCS for hexagonal geometries. The Phase 1 is devoted to the analysis of the switching on of one main coolant pump while the other three pumps are in operation. It includes the following exercises: (a) investigation of the integral plant response using a best-estimate thermal hydraulic system code with a point kinetics model (b) analysis of the core response for given initial and transient thermal hydraulic boundary conditions using a coupled code system with 3D-neutron kinetics model and (c) investigation of the integral plant response using a best-estimate coupled code system with 3D-neutron kinetics. Already before the test, complex flow conditions exist within the RPV e.g. coolant mixing in the upper plenum caused by the reverse flow through the loop-3 with the stopped pump. The test is initiated by switching on the main coolant pump of loop-3 that leads to a reversal of the flow through the respective piping. After about 13 s the mass flow rate through this loop reaches values comparable with the one of the other loops. During this time period, the increased primary coolant flow causes a reduction of the core averaged coolant temperature and thus an increase of the core power. Later on, the power stabilizes at a level higher than the initial power. In this analysis, special attention is paid on the prediction of the spatial asymmetrical core cooling during
DEFF Research Database (Denmark)
Johansen, Torben; Krabbe, Christina; Schmidt, Sissel Ida
2017-01-01
Spontaneous cytosolic calcium transients and oscillations have been reported in various tissues of nonhuman and human origin but not in human midbrain-derived stem cells. Using confocal microfluorimetry, we studied spontaneous calcium transients and calcium-regulating mechanisms in a human ventra...... cells that provides evidence for the mechanisms that are likely to be involved. We propose that the observed spontaneous calcium transients may contribute to mechanisms involved in cell proliferation, phenotypic differentiation, and general cell maturation....
Performance analysis of GYRO: a tool evaluation
International Nuclear Information System (INIS)
Worley, P; Candy, J; Carrington, L; Huck, K; Kaiser, T; Mahinthakumar, G; Malony, A; Moore, S; Reed, D; Roth, P; Shan, H; Shende, S; Snavely, A; Sreepathi, S; Wolf, F; Zhang, Y
2005-01-01
The performance of the Eulerian gyrokinetic-Maxwell solver code GYRO is analyzed on five high performance computing systems. First, a manual approach is taken, using custom scripts to analyze the output of embedded wallclock timers, floating point operation counts collected using hardware performance counters, and traces of user and communication events collected using the profiling interface to Message Passing Interface (MPI) libraries. Parts of the analysis are then repeated or extended using a number of sophisticated performance analysis tools: IPM, KOJAK, SvPablo, TAU, and the PMaC modeling tool suite. The paper briefly discusses what has been discovered via this manual analysis process, what performance analyses are inconvenient or infeasible to attempt manually, and to what extent the tools show promise in accelerating or significantly extending the manual performance analyses
Performance optimisations for distributed analysis in ALICE
Betev, L; Gheata, M; Grigoras, C; Hristov, P
2014-01-01
Performance is a critical issue in a production system accommodating hundreds of analysis users. Compared to a local session, distributed analysis is exposed to services and network latencies, remote data access and heterogeneous computing infrastructure, creating a more complex performance and efficiency optimization matrix. During the last 2 years, ALICE analysis shifted from a fast development phase to the more mature and stable code. At the same time, the framewo rks and tools for deployment, monitoring and management of large productions have evolved considerably too. The ALICE Grid production system is currently used by a fair share of organized and individual user analysis, consuming up to 30% or the available r esources and ranging from fully I/O - bound analysis code to CPU intensive correlations or resonances studies. While the intrinsic analysis performance is unlikely to improve by a large factor during the LHC long shutdown (LS1), the overall efficiency of the system has still to be improved by a...
Fox, Kim; Bousser, Marie-Germaine; Amarenco, Pierre; Chamorro, Angel; Fisher, Marc; Ford, Ian; Hennerici, Michael G; Mattle, Heinrich P; Rothwell, Peter M
2013-10-09
Elevated resting heart rate is known to be detrimental to morbidity and mortality in cardiovascular disease, though its effect in patients with ischemic stroke is unclear. We analyzed the effect of baseline resting heart rate on myocardial infarction (MI) in patients with a recent noncardioembolic cerebral ischemic event participating in PERFORM. We compared fatal or nonfatal MI using adjusted Cox proportional hazards models for PERFORM patients with baseline heart rate heart rate was analyzed as a continuous variable. Other cerebrovascular and cardiovascular outcomes were also explored. Heart rate ≥70 bpm was associated with increased relative risk for fatal or nonfatal MI (HR 1.32, 95% CI 1.03-1.69, P=0.029). For every 5-bpm increase in heart rate, there was an increase in relative risk for fatal and nonfatal MI (11.3%, P=0.0002). Heart rate ≥70 bpm was also associated with increased relative risk for a composite of fatal or nonfatal ischemic stroke, fatal or nonfatal MI, or other vascular death (excluding hemorrhagic death) (Pheart rate, there were increases in relative risk for fatal or nonfatal ischemic stroke, fatal or nonfatal MI, or other vascular death (4.7%, Pheart rate ≥70 bpm places patients with a noncardioembolic cerebral ischemic event at increased risk for MI. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
Theoretical and experimental analysis of fast reactor fuel performance
International Nuclear Information System (INIS)
Kummerer, K.R.; Freund, D.; Steiner, H.
1982-09-01
In order to predict behavior, performance, and capability of prototypic fuel pins a standard operational scheme for the SNR-300 fast breeder reactor is established considering besides normal operation unscheduled power changes and shutdowns. The behavior during the whole lifetime is calculated using the updated SATURN codes and - for special conditions as power transients and skewed fuel rod power - the new TRANSIENT and TEXDIF codes. The results of these calculations are compared to experimental findings. It is demonstrated that the level of modeling and the knowledge of material properties under irradiation are sufficient for a quantitative description of the fuel pin performance under the above mentioned conditions. (orig.) [de
DEFF Research Database (Denmark)
Rode, Carsten
1998-01-01
Analytical theory of transient heat conduction.Fourier's law. General heat conducation equation. Thermal diffusivity. Biot and Fourier numbers. Lumped analysis and time constant. Semi-infinite body: fixed surface temperature, convective heat transfer at the surface, or constant surface heat flux...
Lifetime Reliability Prediction of Ceramic Structures Under Transient Thermomechanical Loads
Nemeth, Noel N.; Jadaan, Osama J.; Gyekenyesi, John P.
2005-01-01
An analytical methodology is developed to predict the probability of survival (reliability) of ceramic components subjected to harsh thermomechanical loads that can vary with time (transient reliability analysis). This capability enables more accurate prediction of ceramic component integrity against fracture in situations such as turbine startup and shutdown, operational vibrations, atmospheric reentry, or other rapid heating or cooling situations (thermal shock). The transient reliability analysis methodology developed herein incorporates the following features: fast-fracture transient analysis (reliability analysis without slow crack growth, SCG); transient analysis with SCG (reliability analysis with time-dependent damage due to SCG); a computationally efficient algorithm to compute the reliability for components subjected to repeated transient loading (block loading); cyclic fatigue modeling using a combined SCG and Walker fatigue law; proof testing for transient loads; and Weibull and fatigue parameters that are allowed to vary with temperature or time. Component-to-component variation in strength (stochastic strength response) is accounted for with the Weibull distribution, and either the principle of independent action or the Batdorf theory is used to predict the effect of multiaxial stresses on reliability. The reliability analysis can be performed either as a function of the component surface (for surface-distributed flaws) or component volume (for volume-distributed flaws). The transient reliability analysis capability has been added to the NASA CARES/ Life (Ceramic Analysis and Reliability Evaluation of Structures/Life) code. CARES/Life was also updated to interface with commercially available finite element analysis software, such as ANSYS, when used to model the effects of transient load histories. Examples are provided to demonstrate the features of the methodology as implemented in the CARES/Life program.
Nonspecific competition underlies transient attention
Wilschut, A.M.; Theeuwes, J.; Olivers, C.N.L.
2015-01-01
Cueing a target by abrupt visual stimuli enhances its perception in a rapid but short-lived fashion, an effect known as transient attention. Our recent study showed that when targets are cued at a constant, central location, the emergence of the transient performance pattern was dependent on the
Dutilleul, Christelle; Driscoll, Simon; Cornic, Gabriel; De Paepe, Rosine; Foyer, Christine H.; Noctor, Graham
2003-01-01
The importance of the mitochondrial electron transport chain in photosynthesis was studied using the tobacco (Nicotiana sylvestris) mutant CMSII, which lacks functional complex I. Rubisco activities and oxygen evolution at saturating CO2 showed that photosynthetic capacity in the mutant was at least as high as in wild-type (WT) leaves. Despite this, steady-state photosynthesis in the mutant was reduced by 20% to 30% at atmospheric CO2 levels. The inhibition of photosynthesis was alleviated by high CO2 or low O2. The mutant showed a prolonged induction of photosynthesis, which was exacerbated in conditions favoring photorespiration and which was accompanied by increased extractable NADP-malate dehydrogenase activity. Feeding experiments with leaf discs demonstrated that CMSII had a lower capacity than the WT for glycine (Gly) oxidation in the dark. Analysis of the postillumination burst in CO2 evolution showed that this was not because of insufficient Gly decarboxylase capacity. Despite the lower rate of Gly metabolism in CMSII leaves in the dark, the Gly to Ser ratio in the light displayed a similar dependence on photosynthesis to the WT. It is concluded that: (a) Mitochondrial complex I is required for optimal photosynthetic performance, despite the operation of alternative dehydrogenases in CMSII; and (b) complex I is necessary to avoid redox disruption of photosynthesis in conditions where leaf mitochondria must oxidize both respiratory and photorespiratory substrates simultaneously. PMID:12529534
Li, Guanchen; von Spakovsky, Michael R.; Shen, Fengyu; Lu, Kathy
2018-01-01
Oxygen reduction in a solid oxide fuel cell cathode involves a nonequilibrium process of coupled mass and heat diffusion and electrochemical and chemical reactions. These phenomena occur at multiple temporal and spatial scales, making the modeling, especially in the transient regime, very difficult. Nonetheless, multiscale models are needed to improve the understanding of oxygen reduction and guide cathode design. Of particular importance for long-term operation are microstructure degradation and chromium oxide poisoning both of which degrade cathode performance. Existing methods are phenomenological or empirical in nature and their application limited to the continuum realm with quantum effects not captured. In contrast, steepest-entropy-ascent quantum thermodynamics can be used to model nonequilibrium processes (even those far-from equilibrium) at all scales. The nonequilibrium relaxation is characterized by entropy generation, which can unify coupled phenomena into one framework to model transient and steady behavior. The results reveal the effects on performance of the different timescales of the varied phenomena involved and their coupling. Results are included here for the effects of chromium oxide concentrations on cathode output as is a parametric study of the effects of interconnect-three-phase-boundary length, oxygen mean free path, and adsorption site effectiveness. A qualitative comparison with experimental results is made.
Building America Performance Analysis Procedures: Revision 1
Energy Technology Data Exchange (ETDEWEB)
None
2004-06-01
To measure progress toward multi-year research goals, cost and performance trade-offs are evaluated through a series of controlled field and laboratory experiments supported by energy analysis techniques using test data to calibrate simulation models.
Verification and Performance Analysis for Embedded Systems
DEFF Research Database (Denmark)
Larsen, Kim Guldstrand
2009-01-01
This talk provides a thorough tutorial of the UPPAAL tool suite for, modeling, simulation, verification, optimal scheduling, synthesis, testing and performance analysis of embedded and real-time systems....
Transients by substructuring with DMAP
Butler, T. G.
1978-01-01
Automated substructuring in level 16 of NASTRAN was employed as a preface to the solution of a direct transient analysis. The DMAP ALTER statements written to adapt the substructuring for transient purposes are explained. Data recovery was accomplished with transfer functions. Proof of the success of the method is presented with an application to a missile structure.