Detection of Suspended SARS-CoV-2 in Indoor Air Using an Electrostatic Sampler

A prototype virus sampler using electrostatic precipitation has been developed to investigate aerosol infection by SARS-CoV-2. The sampler consists of a discharge electrode placed inside a vial, and a thin layer of viral lysis buffer at the bottom, working as a collection electrode. The sampler was operated with the sampling air flow rate of 40 L/min. Collection efficiency of the sampler is about 80% for 25nm to 5.0µm diameter particles. We sampled the air of a food court of a commercial facility, a connecting corridor of a clouded train station, and two office rooms (A and B) in September 2021, just after the 5th peak of COVID-19 in Japan. The analysis using a RT-qPCR detected the virus RNA in the air of the office A, B and the food court. Estimated concentration of the virus in the air determined by calibration curve was 2.0 x 102, 7.8 x 102, and 0.6 - 2.4 x 102 copies/m3, in the office A, B, and the food court, respectively. These results indicate that the sampler using electrostatic precipitation can detect SARS-CoV-2 in indoor air. It could be developed as a risk assessment method for aerosol infection.

GIS-based research on climate suitable region of Loquat in Lishui, Zhejiang province of China

To develop a climatic suitability index and conduct the cultivation division of loquat in Lishui, Zhejiang province of China, we introduced the multi-indicator comprehensive risk assessment method to combine with the hazard factor model, necessary climatic elements during the growing season of loquat and geographic information elements. Results show that the annual active accumulated temperature (rainfall ) over most Lishui is more than 4500°C (1600mm). The two climatic factors above can well meet the needs of loquat growth. The frozen injury days over most Lishui during the young fruit period of loquat are more than 10.0 days, which are higher than those during the flowering period. The annual mean number of continuous overcast rain occurrences is less than 4.5. The climatic mean annual occurrence of persistent abnormal high temperature weather is less than 1. Overall, the most suitable area for the cultivation of loquat mainly located over the relatively flat areas such as river valleys and basins, especially the banks of the Oujiang River in Qingtian and Xiaoxi River valley in Jingning. The excellent combinations of light, heat and water with relatively few meteorological disasters just like frozen injury, continuous rain and high temperature provide a good climatic conditions of the high-quality of loquat planting.

A Comprehensive Failure Risk Assessment Method of Machining Center Component Based on Topology Analysis

The risk assessment of the failure mode of the traditional machining center component rarely considers the topological characteristics of the system and the influence of propagation risks, which makes the failure risk assessment results biased. Therefore, this paper proposes a comprehensive failure risk assessment method of a machining center component based on topology analysis. On the basis of failure mode and cause analysis, considering the correlation of failure modes, Analytic Network Process (ANP) is used to calculate the influence degree of failure modes, and it is combined with component failure mode frequency ratio and failure rate function to calculate independent failure risk. The ANP model of the machining center is transformed into a topological model, and the centrality measurement of network theory is used to analyze the topology of the machining center. The weight of the topological structure index is measured by subjective and objective weighting methods, and then the importance degree of the machining center component is calculated. In this paper, the coupling degree function is introduced to calculate the importance of the connection edge, which is combined with the failure probability to calculate the failure propagation influence degree, and the component propagation failure risk is calculated based on this. Finally, the independent failure risk and the propagation failure risk of the component are integrated to realize the failure risk assessment of the component. Taking a certain type of machining center as an example to illustrate the application, compared with the traditional assessment method, the effectiveness and advancement of the method proposed in this paper have been verified.

Winning the War on Terror

From the perspective of counter-terrorism strategies, terrorist risk assessment has become an important approach for counter-terrorism early warning research. Combining with the characteristics of known terrorists, a quantitative analysis method of active risk assessment method with terrorists as the research object is proposed. This assessment method introduces deep learning algorithms into social computing problems on the basis of information coding technology. We design a special "Top-k" algorithm to screen the terrorism related features, and optimize the evaluation model through convolution neural network, so as to determine the risk level of terrorist suspects. This study provides important research ideas for counter-terrorism assessment, and verifies the feasibility and accuracy of the proposed scheme through a number of experiments, which greatly improves the efficiency of counter-terrorism early warning.