Optimal Culture Capacity of White Shrimp (Litopenaeus vannamei) and Razor Clam (Sinonovacula constricta) in a New Series-Connection Culture Model

To construct an effective circular mix-culture model and investigate its culture capacity,we established one small and one large systems,with white shrimp(Litopenaeus vannamei)and razor clam(Sinonovacula constricta)cultured in separate ponds.The culture water from the L.vannamei was pumped to the S.constricta,and the culture water from the S.constricta overflowed back into the L.vannamei via gravity.In trial I,we tested four culture densities(groups 1–4),and monitored water quality,growth indices,and digestive and immune enzyme activities.From the results,the nitrogen and phosphorus levels generally increased then declined after 56 days,and were lower in groups 1 and 2.The specific growth rate of group 2 was the highest.After 56 days,activities of four digestive enzymes were increased in group 2,and lysozyme activity was significantly decreased in S.constricta in groups 1–4;Alkaline phosphatase activity of L.vannamei was increased in group 3,but decreased in S.constricta in groups 2–4;Acid phosphatase activity was significantly higher in groups 1–3(P<0.05),while SOD and CAT activities were significantly elevated in group 2(P<0.05).Thus,we applied group 2 density for trial II.In trial II,nitrogen and phosphorus concentrations declined significantly during the latter stages,and growth indices were higher than the control(P<0.05).The yields of L.vannamei and S.constricta were significantly higher than the control(P<0.05).The results revealed a good circular mix-culture system with the optimal culture capacity for L.vannamei(40 ind m^(−2))and S.constricta(300 ind m^(−2)),which provided a reference for the future culture of them.

Reliability model of organization management chain of South-to-North Water Diversion Project during construction period

In order to analyze the indispensability of the organization management chain of the South-to-North Water Diversion Project （SNWDP）, two basic forms （series connection state and mixed state of both series connection and parallel connection） of the organization management chain can be abstracted. The indispensability of each form has been studied and is described in this paper. Through analysis of the reliability of the two basic forms, reliability models of the organization management chain in the series connection state and the mixed state of both series connection and parallel connection have been set up.

SiC JFETs Modular Cascaded Method with Active Clamp Control Strategy for DC Solid-state Circuit Breaker

Power semiconductor devices cascaded topology is one of the most common solutions for solid-state circuit breakers(SSCBs)working in medium-voltage DC systems.However,when the number of cascaded devices is large,current series technologies of power semiconductor devices will be difficult to be applied since with uneven voltage sharing problems.Thus,this paper proposes a novel cascade method of multi-SiC JFETs based on modules cascaded.This method consists of two parts:one is a single-gate driver cascaded SiC JFETs topology which is used to form the module,the other one is an active clamp control strategy which ensures that each module is protected from overvoltage when modules are cascaded.The proposed cascade method can effectively suppress voltage overshoot of cascading power devices in the switching process.Based on the proposed cascade method,a 5kV/63A SSCB prototype is designed.Finally,an experiment is conducted based on the designed SSCB.Experimental results validate the effectiveness of the proposed cascaded method for SSCB.

An Analysis of Reliability and Competitiveness of a Corporation in China

This paper, by using the theory of reliability, studies operating of a corporation in China. Firstly, the paper clarifies new characteristics of a corporation in China. Secondly, the paper analyses three kinds of systems that include series connection model, parellel connection model and mixed connection model. In the end, the paper studies four kinds of corporations and makes a forecast that are market-oriented corporation, innovation-oriented market, scale-oriented market and power-oriented market in China.