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The shaft of the electric isolation valve at the outlet of the seawater tank pump in a nuclear power plant fractured due to bolt failure, resulting in detachment and loss of electrical switching function. Upon disassembly, it was discovered that all connecting bolts on the frame were fractured. Macroscopic examination, chemical composition analysis, hardness testing, metallographic examination, scanning electron microscope (SEM) observation, and energy spectrum analysis were performed on the fractured bolts. Results revealed significant deviation from design specifications for stainless steel austenite in terms of their chemical composition; instead they consisted of low-alloy steel (40Cr). High-strength bolts exposed to marine environments are susceptible to corrosion-induced stress cracking or hydrogen embrittlement leading to fracture. Replacement is recommended as a preventive measure against corrosion-induced bolt failure.

According to the requirements of military education policy in the new era, military equipment instructors must constantly strengthen the construction of teaching ability in order to provide professional equipment technical personnel for the new information war in the future. In view of how to comprehensively improve the teaching ability of military equipment instructors, this paper first analyses the main problems existing in the current teaching ability construction of equipment instructors in our Institute, and then puts forward some specific measures to strengthen the teaching ability construction of equipment instructors, which has certain guidance and reference for rapidly and efficiently improving the actual combat teaching ability of equipment instructors.

To solve the problem of mechanized blending and low-level cooperation in Blended Cooperative Learning, this paper proposes a Blended Cooperative Learning Model aiming to Deep Learning, which including the definition, key features and its framework. Through the application in the course of Radar Maintenance Engineering and Performance Parameters Measurement, our teaching practice shows that the students’ practical skills and scientific teamwork ability are significantly improved.

During the normal operation of the third-generation nuclear power plant, according to the requirements of the technical specification (TS), the CMT should be sampled every seven days, which should be controlled between 3400ppm and 4500ppm. However, due to various reasons, the boron concentration of CMT will drop abnormally. In order to meet the requirements of the technical specification, it is necessary to supplement boron to CMT frequently, which will cause a series of serious problems. Therefore, it is necessary and urgent to solve the problem of abnormal reduction of boron concentration in CMT.

Through the modification of a nuclear power plant, the extraction steam on the exhaust pipe of the high-pressure cylinder of the steam turbine is used to heat the circulating water of the heat network, and the pressurized anf heated circulating water of the heat network is supplied to the secondary thermal power station, and then supplied to various users after heat exchange, realizing the first large-scale nuclear heating in China. This paper introduces the function and process of nuclear heating system, and focuses on the analysis of the problems in the commissioning process, which provides a reference for the commissioning of other domestic nuclear power plants after nuclear heating modification.

The new energy represented by strong random wind power connecting to the power system may make the problem of inter-area low-frequency oscillation more serious. In this paper, a DFIG-PSS controller based on virtual impedance is constructed to solve the low-frequency oscillation problem in the wind power system. The step response of PSS-VI was carried out to test the effect of the controller to verify the advantages of PSS-VI than traditional PSS. The input signal of PSS-VI which is a controller based on PSS installed virtual impedance is the active power of DFIG. The output signal of PSS-VI is added to the reactive power control loop of rotor side controller of DFIG. DFIG-PSS-VI was built in Digsilent/Powerfactory software, and the simulation was carried out on the system of 4 machines and 2 regions. It is verified that PSS-VI can improve the low-frequency oscillation of wind power system.

As one of the most versatile and universal second messengers, calcium plays an essential role in cell life. Here we briefly reviewed the research progress of how different calcium channels are located at the cell plasma membrane, including voltage-gated calcium channels (VGCCs), receptor-operated channels (ROC), and store-operated channels (ROC). These channels can regulate different cancer progression. Afterward, the patch clamp technique's development and operating principle, an important quantitative method used for ion channel investigation, are introduced in this paper.

It is necessary to monitor the pressure in the networks in real time, when we face the problem of pipe burst and leakage in urban water supply network. Therefore, it is particularly important to arrange pressure monitoring points in appropriate places in the pipeline networks. The pressure monitoring point layout is often based on similar degree of the node pressure data in the current stage. A method of optimal pressure monitoring point location in the urban water distribution networks was proposed in this paper. Since the above method did not consider spatial properties of network node. The original feature matrix data is constructed by acquiring the spatial attributes of the pressure monitoring nodes and calculating the non-spatial attributes of the nodes. The original feature matrix data will be normalized. Then the Optics clustering algorithm is used to cluster the normalized node feature matrix data to determine the location and number of pressure monitoring points in monitoring area of urban water distribution networks. Experimental results show that the method effectively ensures that the pressure monitoring points can grasp the pressure information of the whole water supply network more comprehensively and rationally, improves the economy of the pressure monitoring points layout, and provides good guidance for the actual layout of pressure monitoring points in municipal water distribution networks.

In this lab-scale simulation, the performance of aerated immobilized microbe (IM) in in-situ pond sedimentation remediation, and the microbial community was studied. It is known for the results that total organic matter (TOM), total nitrogen (TN) and total phosphorus (TP) in the sediment can be effectively reduced by aerated immobilized microbe technology. The polluted raw water, classified as inferior Class-Ⅴ according to the surface water environment quality standard (GB3838-2002), upgraded to Class-III in 30-days remediation with TOM, TN and TP removal rates of 33.35%, 43.35% and 23.20%, respectively. In contract, the control group without the assistant of aerated immobilized microbe still remains at Class-IV. High-throughput sequencing analysis reveals that immobilized microbe technology could improve the species diversity and abundance of the flora, and enhance the similarity between the sediment and the overlying water in the system. The dominant bacteria of the overlying water were Perlucidibaca, Limnohabitans, Bacillus, Hydrogenophaga, Mycobacterium etc. And the dominant bacteria of the sediment were Methanolinea, Methanoregula, Candidatus Competibacter, Methanosaeta etc. Total phosphorous, certified by the redundancy analysis, is the key environmental factor of microbial community structure in both overlying water and sediment.

Since the light control module and communication module connected by the CAN bus, the traditional and centralized lighting control system has a high cost of maintenance. Meanwhile, the connecting way relied on the CAN bus is hard to achieve energy saving. It’s entirely possible to improve the efficiency by using the design of distributed non-central platform, we proposed a new lighting control simulation system based on the natural illumination model and the personnel movement model. Considering that all influencing factors of the real light environment, this paper calculated the illumination of light source on the working surface and the natural illumination in the room by the method of azimuth coefficient and boundary integral. Furthermore, in order to decrease energy consumption, we introduced the Markov transfer matrix to describe the position changes of staff to control the light intensity of the office. Though the simulation results, the proposed lighting control system in this paper is demonstrated that can save more lighting energy consumption in comparison with traditional and centralized lighting control system.

Gas Insulated Switchgear (GIS) is related to the stable operation of power equipment. The traditional partial discharge pattern recognition method relies on expert experience to carry out feature engineering design artificial features, which has strong subjectivity and large blindness. To address the problem, we introduce an encoding-decoding network to reconstruct the input data and then treat the encoded network output as a partial discharge signal feature. The adaptive feature mining ability of the Auto-Encoder Network is effectively utilized, and the traditional classifier is connected to realize the effective combination of the deep learning method and the traditional machine learning method. The results show that the features extracted based on this method have better recognition than artificial features, which can effectively improve the recognition accuracy of partial discharge.

Based on the stress characteristics and the composition of lateral deformation about retaining wall structure, a kind of lateral displacement repairing construction technique of reinforced concrete retaining wall is proposed. Meanwhile, the process principle, construction process and quality control points of the technique are systematically analyzed in this paper. From the application effect of site engineering, the construction proposed in the paper has good engineering benefit and promotion value.

Abstract Background Feral sheep are considered to be a source of genetic variation that has been lost from their domestic counterparts through selection. Methods This study investigates variation in the genes KRTAP1-1, KRT33, ADRB3 and DQA2 in Merino-like feral sheep populations from New Zealand and its offshore islands. These genes have previously been shown to influence wool, lamb survival and animal health. Results All the genes were polymorphic, but no new allele was identified in the feral populations. In some of these populations, allele frequencies differed from those observed in commercial Merino sheep and other breeds found in New Zealand. Heterozygosity levels were comparable to those observed in other studies on feral sheep. Our results suggest that some of the feral populations may have been either inbred or outbred over the duration of their apparent isolation. Conclusion The variation described here allows us to draw some conclusions about the likely genetic origin of the populations and selective pressures that may have acted upon them, but they do not appear to be a source of new genetic material, at least for these four genes.