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1.
Benchmark models of the critical experiments which measured reactivity effects of main fission product elements (Rh, Cs, Nd, Sm, Eu, and Gd) and of an important burnable poison element, erbium, were presented. These elements were dissolved in a vessel which was inserted into the central region of a fuel rod array of TCA (Tank-Type Critical Assembly). The atomic number densities of aqueous solutions in the vessel were calculated. Using these number densities, criticality calculations with MCNP 4A, TWOTRAN code, and JENDL-3.2 cross section library were performed for these experiments.  相似文献   
2.
Abstract

A series of benchmark tests was made to check the neutron nuclear data of main fissile nuclides (239Pu, 235U and 233U) of JENDL-3 for fast reactors. A total of nine critical assemblies were analyzed. They are assemblies of single material, high enrichment and simple geometry with small volume and therefore suitable for nuclear data testing. Criticality calculation was made by ANISN with S16P5 using the VITAMIN-J 175-energy-group. Discussions are made on keft, spectral indices at core center and leakage spectra.

From the study, a problem was pointed out relating to the interpolation of secondary-neutron energy distributions for threshold reactions near the threshold energy point adopted in the original JENDL-3 and its remedy was proposed. By the benchmark tests of thus JENDL-3 (JENDL-3.1), it was shown that integral experiments for 239Pu and 235U cores were reproduced quite satisfactorily. On the contrary, it was revealed that large deviations for 233U cores from the experiment were due to uncertainties of the fission spectrum and the inelastic scattering cross sections. In the present work, sensitivity of “a” parameter (level density parameter) of Madland-Nix's fission spectrum formula to the integral data was extensively studied. Some recommendations are made to improve JENDL-3.1.  相似文献   
3.
Sensitivity analysis of model output is relevant to a number of practices, including verification of models and computer code quality assurance. It deals with the identification of influential model parameters, especially in complex models implemented in computer programs with many uncertain input variables. In a recent article a new method for sensitivity analysis, named HIM* based on a rank transformation of the uncertainty importance measure suggested by Hora and Iman was proved very powerful for performing automated sensitivity analysis of model output, even in presence of model non-monotonicity. The same was not true of other widely used non-parametric techniques such as standardized rank regression coefficients. A drawback of the HIM* method was the large dimension of the stochastic sample needed for its estimation, which made HIM* impracticable for systems with large number of uncertain parameters. In the present note a more effective sampling algorithm, based on Sobol's quasirandom generator is coupled with HIM*, thereby greatly reducing the sample size needed for an effective identification of influential variables. The performances of the new technique are investigated for two different benchmarks.  相似文献   
4.
Due to the advent of sensor technology and its applications, mobile wireless sensor networks (MWSNs) have gained a significant amount of research interest. In a typical MWSN, sensors can move within the network. We develop a set of probabilistic and deterministic cellular automaton (CA)-based algorithms for motion planning problems in MWSNs. First, we consider a scenario where a group of sensors are deployed and they need to disperse in order to maximise the area covered by the network. In this variant of the problem we do not explicitly consider that the sensors should maintain the connectivity of the network while they move. Second, we consider a scenario where the sensors are initially randomly distributed and they need to disperse autonomously to both maximise the coverage of the network and maintain its connectivity. We carry out extensive simulations of both deterministic and randomised variants of the algorithms. For the first variant of the problem we compare our algorithms with one previous algorithm and find that our algorithm yields better network coverage than the earlier algorithm. We also find that probabilistic algorithms have better overall performance for the second variant. CA algorithms rely only on local information about the network and, hence, they can be used in practice for MWSN problems. On the other hand, locality of the algorithm implies that maintaining connectivity becomes a non-trivial problem.  相似文献   
5.
工件在机床上或者夹具中时,用作确定位置的基准称为定位基准,定位基准分粗基准和精基准.定位基准的合理选择直接影响着机械加工的质量与稳定性.  相似文献   
6.
本优解方法解决了轴端定位孔中心位置(转角)的测量数据不稳定,重复性不好的问题,即把轴端定位孔看作是凸轮轴上的一个凸轮。这个凸轮的"最高点"与旋转中心连线所确定的角度,就是轴端定位孔中心的转角。则可以按"敏感点法"非常容易地求解出轴端定位孔中心转角。  相似文献   
7.
A numerical benchmark exercise has been under way for comparing the results of different calculational methods/data sets used for the analysis of light water reactor (LWR) configurations employing Pu inert matrix fuels (IMFs). The first phase of the exercise was devoted to infinite arrays of identical IMF cells. The main feature investigated in the second phase has been the influence of the neutron spectra in UO2 and MOX cores on individual IMF cells. Phase 3 is concerned with the more realistic situation of an IMF assembly surrounded by UO2 assemblies. Significant discrepancies have been observed for power peaking effects and delayed neutron parameters in Phase 2. In Phase 3, neutron balance differences for the IMF, particularly at EOL, are found to be significantly larger than were observed in Phase 1.  相似文献   
8.
The usefulness of an automatic workpiece classification system depends primarily on the extent to which its classification results are consistent with users' judgments. Thus, to evaluate the effectiveness of an automatic classification system it is necessary to establish classification benchmarks based on users' judgments. Such benchmarks are typically established by having subjects perform pair comparisons of all workpieces in a set of sample workpieces. The result of such comparisons is called a full-data classification. However, when the number of sample workpieces is very large, such exhaustive comparisons become impractical. This paper proposes a more efficient method, called lean classification, in which data on comparisons between the samples and a small number of typical workpieces are used to infer the complete classification results. The proposed method has been verified by using a small set of 36 sample workpieces and by computer simulation with medium to large sets of 100 to 800 sample workpieces. The results reveal that the method could produce a classification that was 71% consistent with the full-data classification while using only 10% of the total data.  相似文献   
9.
Identified as one of the key issues in sustainable building designs, freshwater consumption is of primary importance to the design of water systems in buildings. Various benchmarks of water consumption have been developed for the indication and promotion of building sustainability; however, a simple normalization might require precise regional and timing adaptation while a complicated benchmarking model could impose extra adaptation difficulties. In this study, a simple epistemic benchmarking model for residential buildings was formed from existing domestic water consumption patterns and the latest regional survey results. In particular, with various prior estimates from reported water consumption worldwide, a water consumption survey of 60 apartments in Hong Kong was used to formulate a likelihood function for assessing the model validity. The posterior average consumption was compared with the Hong Kong global freshwater consumption patterns to derive the water consumption benchmarks for residential buildings in the region. This epistemic approach would be useful for evaluating the benchmarks of water consumption that is under continuous monitoring. The study also presented a template for formulating epistemic water consumption benchmarks for residential premises elsewhere.  相似文献   
10.
In the framework of joint effort between the Nuclear Energy Agency (NEA) of OECD, the United States Department of Energy (US DOE), and the Commissariat a l'Energie Atomique (CEA), France a coupled three-dimensional (3D) thermal-hydraulics/neutron kinetics benchmark for VVER-1000 was defined. The benchmark consists of calculation of a pump start-up experiment labelled V1000CT-1 (Phase 1), as well as a vessel mixing experiment and main steam line break (MSLB) transient labelled V1000CT-2 (Phase 2), respectively. The reference nuclear plant is Kozloduy-6 in Bulgaria. The overall objective is to assess computer codes used in the analysis of VVER-1000 reactivity transients. A specific objective is to assess the vessel mixing models used in system codes. Plant data are available for code validation consisting of one experiment of pump start-up (V1000CT-1) and one experiment of steam generator isolation (V1000CT-2). The validated codes can be used to calculate asymmetric MSLB transients involving similar mixing patterns. This paper summarizes a comparison of CATHARE and TRAC-PF1 system code results for V1000CT-1, Exercise 1, which is a full plant point kinetics simulation of a reactor coolant system (RCS) pump start-up experiment. The reference plant data include integral and sector average parameters. The comparison is made from the point of view of vessel mixing and full system simulation. CATHARE used a six-sector multiple 1D vessel thermal-hydraulic model with cross flows and TRAC used a six-sector, 18-channel coarse-mesh 3D vessel model. Good agreement in terms of integral parameters and inter-loop mixing is observed.  相似文献   
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