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Technical Problems and Approval Standards for the Regional Trials of Soybean Varieties in Liaoning Province
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作者 唐红丽 《Agricultural Science & Technology》 CAS 2014年第11期1847-1848,1882,共3页
The technical problems and approval standards for the regional test of soybean varieties in Liaoning Province were discussed. The technical key points for the soybean regional trials were the selection of trial fields... The technical problems and approval standards for the regional test of soybean varieties in Liaoning Province were discussed. The technical key points for the soybean regional trials were the selection of trial fields, preparations in lab be-fore sowing, preparations in regional trial field before sowing, sowing in suitable time and strict with sowing process, field management and survey record, harvest and sampling as wel as lab test and summary. In addition, the approval standards for common varieties and quality varieties for the soybean regional trials in Liaoning were introduced, with the aim to provide accurate and scientific theoretical basis for the approval of soybean varieties. 展开更多
关键词 Liaoning soybean Regional Test Technical problems Approval stan-dards
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Sequential fault diagnosis strategy with imperfect tests considering life cycle cost 被引量:2
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作者 张士刚 胡政 温熙森 《Journal of Central South University》 SCIE EI CAS 2013年第12期3513-3521,共9页
The problem of sequential fault diagnosis is to construct a diagnosis tree that can isolate the failure sources with minimal test cost. Pervious sequential fault diagnosis strategy generating algorithms only consider ... The problem of sequential fault diagnosis is to construct a diagnosis tree that can isolate the failure sources with minimal test cost. Pervious sequential fault diagnosis strategy generating algorithms only consider the execution cost at application stage, which may result in a solution with poor quality from the view of life cycle cost. Furthermore, due to the fact that uncertain information exists extensively in the real-world systems, the tests are always imperfect. In order to reduce the cost of fault diagnosis in the realistic systems, the sequential fault diagnosis problem with imperfect tests considering life cycle cost is presented and formulated in this work, which is an intractable NP-hard AND/OR decision tree construction problem. An algorithm based on AND/OR graph search is proposed to solve this problem. Heuristic search based on information theory is applied to generate the sub-tree in the algorithm. Some practical issues such as the method to improve the computational efficiency and the diagnosis strategy with multi-outcome tests are discussed. The algorithm is tested and compared with previous algorithms on the simulated systems with different scales and uncertainty. Application on a wheel momentum system of a spacecraft is studied in detail. Both the simulation and application results suggest that the cost of the diagnosis strategy can be reduced significantly by using the proposed algorithm, especially when the placement cost of the tests constitutes a large part of the total cost. 展开更多
关键词 test sequencing problem sequential fault diagnosis imperfect test life cycle cost AND/OR graph
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On the Solution Accuracy Downstream of Shocks When Using Godunov-Type Schemes.I.Sources of Errors in One-Dimensional Problems
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作者 Alexander V.Rodionov 《Communications in Computational Physics》 SCIE 2023年第8期749-786,共38页
The article opens a series of publications devoted to a systematic study of numerical errors behind the shock wave when using high-order Godunov-type schemes,including in combination with the artificial viscosity appr... The article opens a series of publications devoted to a systematic study of numerical errors behind the shock wave when using high-order Godunov-type schemes,including in combination with the artificial viscosity approach.The proposed paper describes the numerical methods used in the study,and identifies the main factors affecting the accuracy of the solution for the case of one-dimensional gas dynamic problems.The physical interpretation of the identified factors is given and their influence on the grid convergence is analyzed. 展开更多
关键词 Shock-capturing methods Riemann problem WENO reconstruction Runge-Kutta method Hancock-Rodionov method artificial viscosity approach Shu-Osher test problem
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Key problems and solutions in supercritical CO2 fracturing technology 被引量:3
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作者 Haizhu WANG Gensheng LI +4 位作者 Bin ZHU Kamy SEPEHRNOORI Lujie SHI Yong ZHENG Xiaomei SHI 《Frontiers in Energy》 SCIE CSCD 2019年第4期667-672,共6页
Supercritical CO2 fracturing is considered to be a new method for efficient exploitation of unconventional reservoirs,such as shale gas,coal bed methane,and tight sand stone gas.Supercritical CO2 has many special prop... Supercritical CO2 fracturing is considered to be a new method for efficient exploitation of unconventional reservoirs,such as shale gas,coal bed methane,and tight sand stone gas.Supercritical CO2 has many special properties including low viscosity,high diffusion coefficient,and lack of surface tension,which brings about great advantages for fracturing.However,these properties also cause several problems,such as difficulty in proppant transportation,high friction loss,and high pump displacement.In this paper,the above problems were analyzed by combining field test with laboratory study and specific solutions to these problems are given.The high frictionloss in the pipeline could be reduced by developing a new drag reducing agent and selecting large-size casing.Besides,for the problem of poor capacity in proppant carrying and sand plug,the methods of adding tackifier into supercritical CO2,increasing pump displacement and selecting ultralow density proppants are proposed.Moreover,for the problem of fast leak-off and high requirement for pump displacement,the displacement can be increased or the pad fluid can be injected into the reservoir.After solving the above three problems,the field test of supercritical CO2 fracturing can be conducted.The research results can promote the industrialization process of supercritical CO2 fracturing. 展开更多
关键词 supercritical CO2 FRACTURING friction loss proppant carrying flied test problem
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Test sequencing problem arising at the design stage for reducing life cycle cost 被引量:3
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作者 Zhang Shigang Hu Zheng Wen Xisen 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2013年第4期1000-1007,共8页
Previous test sequencing algorithms only consider the execution cost of a test at the application stage. Due to the fact that the placement cost of some tests at the design stage is considerably high compared with the... Previous test sequencing algorithms only consider the execution cost of a test at the application stage. Due to the fact that the placement cost of some tests at the design stage is considerably high compared with the execution cost, the sequential diagnosis strategy obtained by previous methods is actually not optimal from the view of life cycle. In this paper, the test sequencing problem based on life cycle cost is presented. It is formulated as an optimization problem, which is non-deterministic polynomial-time hard (NP-hard). An algorithm and a strategy to improve its computational efficiency are proposed. The formulation and algorithms are tested on various simulated systems and comparisons are made with the extant test sequencing methods. Application on a pump rotational speed control (PRSC) system of a spacecraft is studied in detail. Both the simulation results and the real-world case application results suggest that the solution proposed in this paper can significantly reduce the life cycle cost of a sequential fault diagnosis strategy. 展开更多
关键词 AND/OR graph Heuristic search Life cycle cost Sequential fault diagnosis Test sequencing problem
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Projection-based High-dimensional Sign Test
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作者 Hui CHEN Chang Liang ZOU Run Ze LI 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2022年第4期683-708,共26页
This article is concerned with the high-dimensional location testing problem.For highdimensional settings,traditional multivariate-sign-based tests perform poorly or become infeasible since their Type I error rates ar... This article is concerned with the high-dimensional location testing problem.For highdimensional settings,traditional multivariate-sign-based tests perform poorly or become infeasible since their Type I error rates are far away from nominal levels.Several modifications have been proposed to address this challenging issue and shown to perform well.However,most of modified sign-based tests abandon all the correlation information,and this results in power loss in certain cases.We propose a projection weighted sign test to utilize the correlation information.Under mild conditions,we derive the optimal direction and weights with which the proposed projection test possesses asymptotically and locally best power under alternatives.Benefiting from using the sample-splitting idea for estimating the optimal direction,the proposed test is able to retain type-I error rates pretty well with asymptotic distributions,while it can be also highly competitive in terms of robustness.Its advantage relative to existing methods is demonstrated in numerical simulations and a real data example. 展开更多
关键词 High dimensional location test problem locally optimal test nonparametric test sample-splitting spatial sign test
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A GENERATOR AND A SIMPLEX SOLVER FOR NETWORK PIECEWISE LINEAR PROGRAMS
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作者 孙捷 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 1994年第2期177-185,共9页
This is a brief report on our recent work in network piecewise linear programming (NPLP),and it consists of two parts. In the first park, we describe a generator for NPLP problems which is derived from the classical n... This is a brief report on our recent work in network piecewise linear programming (NPLP),and it consists of two parts. In the first park, we describe a generator for NPLP problems which is derived from the classical network linear program generator NETGEN. The generator creates networks of the same topological structures as NETGEN, but each arc is associated with a convex piecewise linear cost. The purpose of this program is to provide a set of standard test problems which can be used to compare the performance of various algorithms for NPLP. In the second part,we introduce a network simplex method that directly solves a network piecewise linear program without reformulating it as a network linear program of higher dimension. Forty benchmark NPLP problems are solved by this method and a reformulation method. The computational results are in favor of the direct method and show that solving an NPLP problem is not much harder than solving a network linear program of the same dimension. 展开更多
关键词 Computational experiments generator of test problems network programming piecewise linear programming simplex method.
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