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Chinese Journal of Oceanology and Limnology 2003年第2期21卷 46-63页

作者：杨东方张经高振会陈豫孙培艳 College of Fishery Science Shanghai Fisheries University State Key Laboratory of Estuarine and Coastal Research Beihai Monitoring Center of State Oceanic Administration College of Computer Science Shanghai Fisheries University

Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994 revealed the spatiotemporal variations of the ambient Si(OH) 4∶NO 3 (Si∶N) concentration ratios and the seasonal variations of (Si∶N) ratios in Jiaozhou Bay and showed that the Si∶N ratios were values of primary production is divided into three parts: the basic value of Si limited primary production, the extent of Si limited primary production and the critical value of Si limited primary production, which can be calculated for Jiaozhou Bay by Equations (1), (2) and (3), showing that the time of the critical value of Si limitation of phytoplankton growth in Jiaozhou Bay is around November 3 to November 13 in autumn; and that the time of the critical value of Si satisfaction of phytoplankton growth in Jiaozhou Bay is around May 22 to June 7 in spring. Moreover, the calculated critical value of Si satisfactory for phytoplankton growth is 2.15-0.76 μmol/L and the critical value of Si limitation of phytoplankton growth is 1.42-0.36 μmol/L; so that the time period of Si limitation of phytoplankton growth is around November 13 to May 22 in the next year; the time period of Si satisfactory for phytoplankton growth is around June 7 to November 3. This result also expl

关键词： phytoplankton limitation and satisfaction critical value Jiaozhou Bay

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Determination of indices and critical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine

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International Journal of Mining Science and Technology 2012年第1期22卷 89-93页

作者： Ou Jianchun Liu Mingju Zhang Chunru Liu Yanwei Wei Jianping School of Safety Engineering Chino University of Mining&TechnologyXuzhou 221008China Science and Engineering Henan Polytechnic UniversityJiaozuo 454003China Xieqiao Mine of Huainan Mining Industry Group Huainan 232001Chino

Based on the important role in mine safety played by parameters of the first gas outburst, we propose a method of combining historic data, theoretical analysis and experimental research for the purpose of crit- ical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine. According to a characteristic analysis and a summary of the rules of coal and gas outbursts in the No.8 coal seam of a Hua- inan mine, we have investigated their effect on coal and gas outbursts in terms such as ground stress, gas, and coal structure. We have selected gas parameters and determined the critical values of each of the fol- lowing indices： gas content as 7.7 m^3/t, tectonic coal as 0.8 m thick, the absolute gas emission as 2 m3/min, the rate of change as 0.7 m3/min, the gas desorption index of a drilling chip KI as 0.26 mL/（g min^1/2） and the values of desorption indexes Ah2 as 200 Pa. From a verification of the production, the results indicate that application of each index and their critical values significantly improve the level of safety in the pro- duction process, relieve the burden upon the mine, save much labor and bring clear economic benefits.

关键词： Parameters of first gas outburst Gas content Thickness of tectonic coal critical value Coal and gas outbursts

Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection

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Chinese Physics B 2022年第1期31卷 395-402页

作者： Ming-Wei Fang Jian-Chao He Zhan-Chao Hu Yun Bao School of Aeronautics and Astronautics Sun Yat-sen UniversityGuangzhou 510275China

We study the characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh–Benard convection in´a square cavity by direct numerical *** Rayleigh number range is 1×10^(8)≤Ra≤1×10^(13),and the Prandtl number is selected as Pr=0.7 and Pr=*** is found that the temperature fluctuation profiles with respect to Ra exhibit two different distribution *** the thermal boundary layer,the normalized fluctuationθrms/θrms,max is independent of Ra and a power law relation is identified,i.e.,θrms/θrms,max∼(z/δ)0.99±0.01,where z/δis a dimensionless distance to the boundary(δis the thickness of thermal boundary layer).Out of the boundary layer,when Ra≤5×10^(9),the profiles ofθrms/θrms,max descend,then ascend,and finally drop dramatically as z/δ*** for Ra≥1×10^(10),the profiles continuously decrease and finally overlap with each *** two different characteristics of temperature fluctuations are closely related to the formation of stable large-scale circulations and corner ***,there is a critical value of Ra indicating the transition,beyond which the fluctuation hθrmsiV has a power law dependence on Ra,given by hθrmsiV∼Ra−0.14±0.01.

关键词： Rayleigh-Benard temperature fluctuation distribution patterns critical value

Site-Specific Nitrogen Management in Dry Direct-Seeded Rice Using Chlorophyll Meter and Leaf Colour Chart

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Pedosphere 2015年第1期25卷 72-81页

作者： Ali Mohamed ALI Harmit Singh THIND Sandeep SHARMA YADVINDER-SINGH Department of Soil Science Punjab Agricultural University Department of Soil Fertility and Microbiology Desert Research Centre

The need to maintain high rice yields and improve fertilizer nitrogen(N)-use efficiency has fueled the use of tools such as leaf colour chart(LCC) and chlorophyll meter(SPAD meter) in managing fertilizer N based on colour of the leaf. Field experiments were conducted during 2011 to 2013 at Ludhiana, India to assess the need for basal N application and to establish critical threshold values of leaf greenness as measured by LCC and SPAD meter for formulating strategies for in-season management of fertilizer N in dry direct-seeded rice(DDSR). Avoiding application of N at sowing did not adversely affect rice grain yield, indicating that basal N application in DDSR was not necessary and might lead to reduced N-use efficiency. Monitoring N uptake rate during the growing season of DDSR suggested that N uptake rate peaked at the two growth stages: maximum tillering(42 to 56 days after sowing(DAS))and panicle initiation stages(70 to 84 DAS). Using the Cate-Nelson procedure, critical LCC and SPAD meter values for fertilizer N application worked out to be 4 and 37, respectively. Real-time fertilizer N management strategy based on applying 30 kg N ha-1whenever SPAD meter or LCC readings fell below the critical values maintained optimum rice yields along with higher N-use efficiency than that observed by following blanket recommendation for fertilizer N in the region. The fixed-time variable-dose strategy consisted of applying prescriptive doses of 20 kg N ha-1at 14 DAS and 30 kg N ha-1at 28 DAS and corrective doses of 30, 40 or 50 kg N ha-1at 49 and 70 DAS depending upon LCC shade to be ≥ 4, 4–3.5, or < 3.5 and SPAD meter readings to be ≥ 40, 40–35, or< 35, respectively. This strategy also resulted in optimal rice yield along with higher N-use efficiency as compared to the blanket recommendation. This study revealed that in DDSR, fertilizer N could be managed more efficiently using the tools of LCC and SPAD meter than the current blanket recommendation.

关键词： basal N application critical value grain yield leaf greenness N-use efficiency

State Key Laboratory of Power Grid Safety and Energy Conservation,China Electric Power Research Institute,Beijing,China

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CSEE Journal of Power and Energy Systems 2022年第3期8卷 710-720页

作者： Lin Yu Huadong Sun Shiyun Xu Bing Zhao Jian Zhang State Key Laboratory of Power Grid Safety and Energy Conservation China Electric Power Research InstituteBeijing100192China

The power system is experiencing a higher penetration of renewable energy generations(REGs).The short circuit ratio(SCR)and the grid impedance ratio(GIR)are two indices to quantify the system strength of the power system with *** this paper,the critical short circuit ratio(CSCR)is defined as the corresponding SCR when the system voltage is in the critical stable *** static voltage stability analysis,the mathematical expression of the CSCR considering the impact of GIR is *** maximum value of CSCR is adopted as the critical value to distinguish the weak power *** on the static equivalent circuit analysis,it is proved that the CSCR is still effective to evaluate critical system strength considering the interactive impact among ***,we find that the GIR can be neglected and the SCR can be used individually to evaluate the system strength when SCR>2 or GIR>*** correctness and rationality of the CSCR and its critical value are validated on ADPSS.

关键词： critical short circuit ratio critical value grid impedance ratio maximum power transfer theorem static equivalent circuit analysis

Fractal analysis on the spatial distribution of acoustic emission in the failure process of rock specimens

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International Journal of Minerals,Metallurgy and Materials 2009年第1期16卷 19-24页

作者： Rui-fu Yuan Yuan-hui Li Energy Science and Engineering School Henan Polytechnic University Jiaozuo 454000 China College of Resource and Civil Engineering Northeastern University Shenyang 110004 China

The spatial distribution of acoustic emission （AE） events in the failure process of several rock specimens was acquired using an advanced AE acquiring and analyzing system. The box counting method （BCM） was employed to calculate the fractal dimension （FD） of AE spatial distribution. There is a similar correlation between the fractal dimension and the load strength for different rock specimens. The fractal dimension presents a decreasing trend with the increase of load strength. For the same kind of specimens, their FD values will decrease to the level below a relatively same value when they reach failure. This value can be regarded as the critical value, which implies that the specimen will reach failure soon. The results reflect that it is possible to correlate the damage of rock with a macroscopic parameter, the FD value of AE signals. Furthermore, the FD value can be also used to forecast the final failure of rock. This conclusion allows identifying or predicting the damage in rock with a great advantage over the classic theory and is very crucial for forecasting rockburst or other dynamic disasters in mines.

关键词： rockburst acoustic emission spatial distribution fractal dimension critical value damage

Drag Force of Non—newtonian Fluid on a Continuous Moving Surface with Strong Suction／Blowing

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Chinese Physics Letters 2003年第6期20卷 858-861页

作者： ZHENGLian-Cun ZHANGXin-Xin HEJi-Cheng DepartmentofMathematicsandMechanics UniversityofScienceandTechnologyBeijingBeijing100083 MechanicalEngineeringSchool UniversityofScienceandTechnologyBeijingBeijing100083 ThernalEngineeringDepartment NortheasternUniversityShenyang110006

A theoretical analysis for the laminar boundary layer flow of a non-Newtonian fluid on a continuous moving flat plate with surface strong suction/blowing is made. The types of potential flows necessary for similar solutions to the boundary layer are determined and both analytical and numerical solutions are presented. It is shown that the solution of the boundary layer problem depends not only on the ratio of the velocity of the plate to the velocity of the free stream, but also on the suction/blowing parameter. The skin friction decreases with increasing the parameters of power law and blowing. In the case of existing suction, the shear force decreases with the increases of tangential velocity, the largest shear force occurs at wall and the smallest shear force occurs at the edge of the boundary layer. However, in the case of existing surface blowing, the shear force initially increases with tangential velocity and the biggest shear force occurs at the interior of the boundary layer, the skin friction approaches to zero as the blowing rate approaches the critical value.

关键词： Drag forces Moving boundary layer flow Shear Force critical value blowing tangential velocity boundary layer Power law Skin friction speed

Epidemic dynamics on complex networks

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Progress in Natural Science:Materials International 2006年第5期16卷 452-457页

作者： ZHOU Tao , FU Zhongqian, and WANG Binghong (Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230026, China Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China) [a]Department of Electronic Science and Technology University of Science and Technology of China Hefei China

Recently, motivated by the pioneer work in revealing the small-world effect and scale-free property of various real-life networks, many scientists devote themselves to studying complex networks. One of the ultimate goals is to understand how the topological structures affect the dynamics upon networks. In this paper, we give a brief review on the studies of epidemic dynamics on complex networks, including the description of classical epidemic models, the epidemic spread on small-world and scale-free networks, and network immunization. Finally, perspectives and some interesting problems are proposed.

关键词： epidemic dynamics complex networks critical value immunization small-world effect scale-free property.

EXISTENCE AND UNIQUENESS OF THE POSITIVE STEADY STATE SOLUTION FOR A LOTKA-VOLTERRA PREDATOR-PREY MODEL WITH A CROWDING TERM

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Acta Mathematica Scientia 2020年第6期40卷 1961-1980页

作者： Xianzhong ZENG Lingyu LIU Weiyuan XIE School of Mathematics and Computing Science Hunan University of Science and TechnologyXiangtan 411201China

This paper deals with a Lotka-Volterra predator-prey model with a crowding term in the predator *** obtain a critical value λ1^D(Ω0),and demonstrate that the existence of the predator inΩ0 only depends on the relationship of the growth rateμof the predator and λ1^D(Ω0),not on the ***,whenμ<λ1^D(Ω0),we obtain the existence and uniqueness of its positive steady state solution,while whenμ≥λ1^D(Ω0),the predator and the prey cannot coexist inΩ*** results show that the coexistence of the prey and the predator is sensitive to the size of the crowding regionΩ0,which is different from that of the classical Lotka-Volterra predator-prey model.

关键词： Lotka-Volterra predator-prey model crowding term critical value coexistence

A Rank-Sum Testing Method for Multi-Trait Comprehensive Ranking and Its Application

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Agricultural Sciences in China 2010年第8期9卷 1117-1126页

作者： LUO Ru-jiu HU Zhi-qiu KONG Wen-qian SONG Wen XU Chen-wu Jiangsu Provincial Key Laboratory of Crop Genetics and Physiology/Key Laboratory of Plant Functional Genomics Ministry of Education/ Yangzhou University Yangzhou 225009 P.R. China Lianyungang Technical College Lianyungang 222006 P.R.China

The rank-sum test is a nonparametric method used in variety evaluation. However, the hypothesis testing of the method hasn＇t been established for multi-trait comprehensive ranking. In this paper, under null hypothesis H0： the variety＇s ranking on each trait is random, the theoretical distribution of sum of ranks （SR） was firstly derived and further used to obtain the critical values for multi-trait comprehensive evaluation in rank-sum testing. A new C＋＋ class and its basic arithmetic were defined to deal with the miscount caused by the precision limitation of built-in data type in common statistical software under large number of varieties and traits. Finally, an application of the theoretical results was demonstrated using five starch viscosity traits of 12 glutinous maize varieties. The proposed method is so simple and convenient that it can be easily used to rank different varieties by multiple traits.

关键词： comprehensive evaluation sum of ranks theoretical distribution critical value