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Status of uncertainty assessment in k ₀-NAA measurement: anything still missing?

JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY 2014年第2期300卷 567-572页

作者： Smodis, Borut Bucar, Tinkara Jozef Stefan Inst Ljubljana 1000 Slovenia

Several approaches to quantifying measurement uncertainty in k (0)-based neutron activation analysis (k (0)-NAA) are reviewed, comprising the original approach, the spreadsheet approach, the dedicated computer program involving analytical calculations and the two k (0)-NAA programs available on the market. Two imperfectness in the dedicated programs are identified, their impact assessed and possible improvements presented for a concrete experimental situation. The status of uncertainty assessment in k (0)-NAA is discussed and steps for improvement are recommended. It is concluded that the present magnitude of measurement uncertainty should further be improved by making additional efforts in reducing uncertainties of the relevant nuclear constants used.

关键词： k(0)-NAA Measurement result Uncertainty Uncertainty propagation factor computer program

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A new method to evaluate roadheader operational stability

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TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY 2006年第2期21卷 172-179页

作者： Acaroglu, O Ergin, H Istanbul Tech Univ Fac Min Dept Min Engn TR-34469 Istanbul Turkey

Roadheader, one of the mechanized excavation equipments, has an exceptional place among the other excavation methods. Determination of the stability states of the roadheader is an important matter for the efficiency of excavation. For this reason, a new method has been developed to obtain numerical values that indicate stability states of such machines. The method has been developed for both longitudinal and transverse cutting head type machines by establishing stability equations for states of turning around the vertical axis, turning to the side direction, turning to the back direction and sliding in all cutting modes. A computer program based on these equations has been written in C++ programming language. The stability analysis can be made either for one point on the excavation face or whole face. Obtained values can be used to compare the stability states of various roadheaders in the same cutting condition as well as using to compare the stability states of a roadheader. A stability index that has also been established can only be used to compare a stability state of a roadheader in different cutting conditions. The developed methodology was tested in a transverse cutting head type roadheader for arcing, lowering and lifting modes. It has been obtained that the stability state of turning around the vertical axis of the roadheader is the most critical state especially in arcing mode. The effects of the machine design parameters, cutting head and tunnel parameters on the stability of the roadheaders can also be investigated by this method. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： roadheader stability analysis computer program

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computer ESTIMATION OF THE ATMOSPHERIC GAS-PHASE REACTION-RATE OF ORGANIC-COMPOUNDS WITH HYDROXYL RADICALS AND OZONE

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CHEMOSPHERE 1993年第12期26卷 2293-2299页

作者： MEYLAN, WM HOWARD, PH Syracuse Research Corporation Merrill Lane Syracuse NY 13210 USA

The Atmospheric Oxidation program (AOP) is a computer program constant for the atmospheric, gas-phase reaction between photochemically produced hydroxyl radicals (OH) and organic chemicals. It also estimates the rate constant for the gas-phase reaction between ozone and olefinic/acetylenic compounds. AOP, which uses estimation methods developed by Atkinson and co-workers, estimates more accurate rate constants than the PCFAP (Fate of Atmospheric Pollutants) program that was part of the U.S. EPA's Graphical Exposure Modeling System (GEMS). Due to its superior predictive ability, the EPA is currently using AOP to evaluate the atmospheric fate of compounds defined under Sections 4, 5 and 6 of the Toxic Substances Control Act (TSCA).

关键词： Air pollution research computer program Hydroxyl radical Organic compound Reaction rate, gas-phase, atmospheric

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Numerical simulation method for the slip power recovery system

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IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS 1999年第1期146卷 17-24页

作者： Marques, GD Univ Tecn Lisboa Seccao Maquinas Elect & Elect Potencia Inst Super Tecn P-1096 Lisbon Portugal

A numerical simulation method for the slip power recovery system is presented. The rig induction-machine model. using flux linkages as state variables is used. This leads to a simple and efficient computer program. The diode bridge rectifier is modelled using three switching functions that are determined by the sign of the corresponding AC currents. The model obtained is very simple, and accurately represents the three-phase diode bridge rectifier including the current commutation process. To merge the models of the induction machine and the diode-bridge rectifier, no difficulties arise when a direct-voltage intermediate circuit is present. When a direct-current circuit is used in the intermediate circuit a model of the whole 'induction machine and diode-bridge rectifier' must be used. Park's variables can be used in this case, also. The operations performed to model the system are equivalent to assuming that the diode bridge rectifier and the DC circuits are transformed into a nonlinear circuit connected to the rotor terminals. MATLAB/simulink is used to integrate the equations. Experimental and simulated results are presented and compared showing good accuracy.

关键词： bridge circuits Asynchronous machines three-phase diode bridge rectifier electric machine analysis computing state variables slip (asynchronous machines) MATLAB Park's variables Power engineering computing direct-current circuit Power convertors and power supplies to apparatus machine theory switching circuits numerical simulation method direct-voltage intermediate circuit computer program rotor terminals dq induction-machine model induction motors slip power recovery system rotors switching functions Simulink current commutation process nonlinear circuit flux linkages rectifying circuits commutation

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CHIMERA: A software tool for reaction rate calculations and kinetics and thermodynamics analysis

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JOURNAL OF COMPUTATIONAL CHEMISTRY 2002年第14期23卷 1375-1389页

作者： Novoselov, KP Shirabaikin, DB Umanskii, SY Vladimirov, AS Minushev, AK Korkin, AA Motorola Inc Semicond Prod Sector Mesa AZ 85202 USA JSC Soft Tec Moscow 117218 Russia Russian Acad Sci NN Semenov Chem Phys Inst Moscow 117977 Russia

This article presents and overviews the CHIMERA program package, which provides a user-friendly graphical interface between quantum chemistry and chemical kinetics programs. CHIMERA facilitates calculations of rate constants for gas-phase reactions using transition state and Rice-Ramsperger-Kassel-Marcus theories. The program includes computational modules for simulation of gas-phase kinetics using simplified reactor models and for computation of chemical equilibria. The review includes a description of the theory implemented in the code, the program description, the general strategy of calculations using CHIMERA, and illustrative examples of the program application. (C) 2002 Wiley Periodicals, Inc.

关键词： computer program chemical kinetics rate constants reactor modeling

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A computational approach for analysis and optimal design of FRP beams

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computerS & STRUCTURES 1999年第2期70卷 169-183页

作者： Davalos, JF Qiao, PZ W Virginia Univ Dept Civil & Environm Engn Morgantown WV 26506 USA

Fiber-reinforced plastic (FRP) beams are thin-walled or moderately thick-walled open or closed sections consisting of assemblies of flat panels. We present a computational approach with the computer program FRPBEAM (1994) for the response evaluation of pultruded FRP beams in bending. This program combines micro/macro-mechanics analyses with the Mechanics of Laminated composite Beams (MLB) model and an explicit stability solution to analyze, design, and optimize FRP shapes. In FRPBEAM, the ply stiffnesses are predicted by micromechanics formulas, based on the fiber volume fraction of each lamina, and the panel laminate properties are computed from the ply stiffnesses and macromechanics. The MLB model is used to analyze the overall response of FRP beams in bending, and the Tsai-Hill failure criterion is adopted to predict first-ply-failure loads. An example of a laminated box beam is used to demonstrate the accuracy of the computer program for predicting beam displacements and ply stresses in relation to finite element analyses. A stability Rayleigh-Ritz method is included in the program and used to evaluate the critical buckling loads for pultruded I-beams. Through parametric studies with FRPBEAM and a multiobjective optimization scheme, the fiber architecture of an existing I-beam is optimized, and based on a recommended practical design, the I-beam section is produced by pultrusion and subsequently tested in bending. The predicted response with FRPBEAM correlates well with the experimental results. As illustrated by design analysis and optimization examples presented in this study, the experimentally and numerically verified computer program can be used to analyze existing FRP shapes and develop new optimized shapes for the civil structural market. (C) 1998 Elsevier Science Ltd. All rights reserved.

关键词： fiber-reinforced plastics beams computer program micro/macromechanics bending buckling material failure optimization

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Characterization and modeling of illite crystal particles and growth mechanisms in a zoned hydrothermal deposit, Lake City, Colorado

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AMERICAN MINERALOGIST 2002年第11-12期87卷 1546-1556页

作者： Bove, DJ Eberl, DD McCarthy, DK Meeker, GP US Geol Survey Denver CO 80225 USA US Geol Survey Boulder CO 80303 USA Texaco EPTD Houston TX 77042 USA

Mean thickness measurements and crystal-thickness distributions (CTDs) of illite particles vary systematically with changes in hydrothermal alteration type, fracture density, and attendant mineralization in a large acid-sulfate/Mo-porphyry hydrothermal system at Red Mountain, near Lake City, Colorado. The hydrothermal illites characterize an extensive zone of quartz-sericite-pyrite alteration beneath two deeply rooted bodies of magmatic-related, quartz-alunite altered rock. Nineteen illites from a 3000 ft vertical drill hole were analyzed by XRD using the PVP-10 intercalation method and the computer program MudMaster (Bertaut-Warren-Averbach technique). Mean crystallite thicknesses, as determined from 001 reflections, range from 5-7 nanometers (nm) at depths from 0-1700 ft, then sharply increase to 10-16 nm at depths between 1800-2100 ft, and decrease again to 4-5 nm below this level. The interval of largest particle thickness correlates strongly with the zone of most intense quartz-sericite-pyrite alteration (QSP) and attendant high-density stockwork fracturing, and with the highest concentrations of Mo within the drill core. CTD shapes for the illite particles fall into two main categories: asymptotic and lognormal. The shapes of the CTDs are dependent on conditions of illite formation. The asymptotic CTDs correspond to a nucleation and growth mechanism, whereas surface-controlled growth was the dominant mechanism for the lognormal CTDs. Lognormal CTDs coincide with major through-going fractures or stockwork zones, whereas asymptotic CTDs are present in wallrock distal to these intense fracture zones. The increase in illite particle size and the associated zone of intense QSP alteration and stockwork veining was related by proximity to the dacitic magma(s), which supplied both reactants and heat to the hydrothermal system. However, no changes in illite polytype, which in other studies reflect temperature transitions, were observed within this interval.

关键词： .crystallite PVP shapes computer program thicknesses MEAN THICKNESS illites hydrothermal alteration Lake City Qsp hydrothermal system Growth mechanisms CTDs illite particles Red Mountain quartz-sericite-pyrite quartz-alunite MudMaster nm at depths particle thickness drill core

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Predicting the fire resistance behaviour of high strength concrete columns

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CEMENT & CONCRETE COMPOSITES 2004年第2期26卷 141-153页

作者： Kodur, VKR Wang, TC Cheng, FP Natl Res Council Canada Inst Res Construct Ottawa ON K1A 0R6 Canada Natl Chiao Tung Univ Dept Civil Engn Hsinchu Taiwan

A numerical model, in the form of a computer program, for tracing the behaviour of high performance concrete (HPC) columns exposed to fire is presented. The three stages, associated with the thermal and structural analysis, for the calculation of fire resistance of columns are explained. A simplified approach is proposed to account for spalling under fire conditions. The use of the computer program for tracing the response of an HPC column from the initial pre-loading stage to collapse, due to fire, is demonstrated. The validity of the numerical model used in the program is established by comparing the predictions from the computer program with results from full-scale fire resistance tests. Details of fire resistance experiments carried out on HPC columns, together with results, are presented. The computer program can be used to predict the fire resistance of HPC columns for any value of the significant parameters, such as load, section dimensions, fiber reinforcement, column length, concrete strength, aggregate type, and fiber reinforcement. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： fire resistance computer program high temperature high performance concrete columns spalling numerical model

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A feedforward IMC structure for controlling the charging temperature of a TES system of a solar cooker

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ENERGY CONVERSION AND MANAGEMENT 2008年第11期49卷 3143-3154页

作者： Mawire, A. McPherson, M. North West Univ Dept Phys & Elect ZA-2735 Mmabatho South Africa

A feedforward internal model control (IMC) structure for controlling and maintaining the outlet charging temperature of a thermal energy storage (TES) system of a solar cooker is presented. The TES system consists of a packed pebble bed in thermal contact with a heat transfer oil contained in a storage tank. An electrical hot plate simulates the collector/concentrator which heats up the oil circulating in a hollow copper spiral coil thus charging the storage. A model for the collector/concentrator system is developed to enable simulation of the feedforward IMC structure. Using a Simulink block model, the simulation results reveal that a feedforward IMC structure performs better than a feedforward structure. The feedforward IMC structure is tested experimentally and the performance of the control structure is acceptable within a few degrees of the set temperatures. Experimental results are also compared with the simulation results. The simulated responses are found to relate closely to the experimental ones and any discrepancies between the two are discussed. Furthermore, the feedforward IMC structure is also compared experimentally with a combined feedforward and PID feedback structure. Results of the comparison indicate that the feedforward IMC structure performs better than the combined feedforward and PID feedback structure. The thermal profile of the storage during the charging experiment with the feedforward IMC structure is also presented and the results obtained from the storage profile indicate that the storage tank is thermally stratified. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： Thermal energy storage Feedforward IMC Modelling Simulation Temperature control computer program

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SEISMIC RESPONSE OF HIGH-TEMPERATURE GAS-COOLED REACTOR CORE WITH BLOCK-TYPED FUEL, (V) - ANALYTICAL METHOD OF SEISMIC RESPONSE FOR TWO-DIMENSIONAL HORIZONTAL SLICE CORE MODEL

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JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 1989年第10期26卷 913-930页

作者： IKUSHIMA, T HONMA, T MITSUBISHI HEAVY IND CO LTD ARAI MACHI TAKASAGO 676 JAPAN

An analytical method for the seismic response of the two-dimensional horizontal slice core model of a high temperature gas-cooled reactor core with block-type fuel has been developed. In the analytical method, blocks are modeled as rigid bodies and a spring dashpot model is used for the collision process between blocks. Analytical results are compared with experimental ones and both are found to be in good agreement. The analytical method can be used to predict the behavior of the high temperature gas-cooled reactor core under seismic excitation.

关键词： seismic response seismic analysis impact response seismic design HTGR type reactors reactor core computer program numerical analysis

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