FIELD SURVEY ON LIGHTING ENVIRONMENT FOR WORK FROM HOME IN JAPAN

The working situation has been dramatically changed in 2020 due to COVID-19. The purpose of this study is to identify the lighting environment which can be adapted to various styles of work from home. In this study, questionnaire survey and field measurement were conducted to identify the actual working situation and the lighting environment of the working location at home. This paper reports the results of questionnaire survey and the measurement data comparing the working location in office and at home.

A load spectra design method for multi-stress accelerated testing

Accelerated testing (AT) is an effective testing method for evaluating the reliability of highly reliable products. In many applications, such products are often subject to multiple stresses in actual working environments. Then, how to design the load spectra for multi-stress AT becomes a critical issue. In this paper, a new load spectra design method is proposed to overcome this challenge. Considering the properties of multiple stresses, a novel multi-stress loading matrix (MSLM) is modified to fully describe the load spectra in actual working environments and to generate the corresponding load spectra for AT. For illustration purposes, an inverse Gaussian (IG) process incorporating life-stress relationships is adopted to model product degradation under multiple stresses. A case study on a type of hydraulic piston pump is provided to demonstrate the use of the proposed method in guiding the load spectra design for multi-stress AT.

An Attention-based Text Detection and Recognition Method for Terminals of Current Transformer’s Secondary Circuit

Recognizing irregular text in real industrial scenes is a challenging task due to the background clutter, low resolutions or distortions. In this work, an attention-based text detection and recognition method for terminals of current transformer’s secondary circuit is proposed. It consists of three major components: pre-processing, text detection and text recognition. In text recognition module, a novel spatial temporal embedding is designed to better utilize the positional information. During training, the proposed framework only requires sequence-level annotations, instead of extra fine-grained character-level boxes or segmentation masks as in previous work. Despite its simplicity, the proposed method achieves good performance on the dataset collected in actual working scene.

Travel Dynamics Analysis and Intelligent Path Rectification Planning of a Roadheader on a Roadway

The tunneling work belongs to the group operation of semi-closed space, and the work is difficult with a high risk coefficient. It is an urgent requirement of coal mining to achieve unmanned and intelligent tunneling work. The path rectification planning of roadheaders is a necessary step before roadway cutting. In the traditional dynamic modeling analysis of roadhead tracks, problems such as compaction resistance, bulldozing resistance, steering resistance, tunnel dip angle, ditching, and obstacle-crossing capacity are not considered. In order to approximate the kinematic and dynamic parameters of a roadheader’s deviation correction under actual working conditions, this paper establishes kinematic and dynamic models of a roadheader’s path rectification at low speeds and under complex working conditions, and calculates the obstacle-crossing ability of roadheaders in the course of path rectification by modes based on roadway conditions, crawler resistance, and driving performance of the roadheader. Field experiments were carried out to verify the effectiveness of the dynamic model. The dynamic roadheader model was used in combination with actual working conditions of roadways in order to establish a roadway grid model. The grid model was simplified using rectifying influence degree and distance cost. The roadheader dynamic model and grid model were then used to propose a path rectification planning and tracking algorithm based on particle swarm optimization of the actual roadway conditions and roadheader driving performance. Finally, the effectiveness and superiority of the algorithm were verified using MATLAB simulation. The algorithm can provide strong technical guarantee for the intelligence of roadheader and unmanned mining. The results presented here can provide theoretical and technical support for the structural optimization and intelligent travel control of roadheaders.

Assessment of the working conditions of medical personnel in military medical organizations during the pandemic of new coronavirus infection

Relevance. During the pandemic of new coronavirus infection, healthcare professionals have increased occupational risks of exposure to the pathogen SARS-CoV-2, as well as physical and psychological stress, especially when treating Covid patients in “red zones”. Such a change in working conditions wasn’t reflected in the results of a special assessment, which requires the development of an individual scientifically based approach to its organization in conditions equated to emergency situations. Intention. Evaluate the results of a special assessment of working conditions and their compliance with actual working conditions, taking into account the health risks for healthcare professionals taking care of Covid patients.Methodology. We retrospectively conducted a comparative analysis of 295 cards for a special assessment of the working conditions of medical personnel of military medical organizations of therapeutic and infectious profile over 2015–2019, and 266 cards from the same organizations for 2020.Results and Discussion. Study of cards for special assessment of working conditions of medical personnel of military medical organizations for 2015–2020 showed the leading role of biological factors for all categories of medical personnel. Working in the “Red zone” should be assessed as 3.3 (Degree III harmful) based on biological hazard or 4 (dangerous) due to risks of acute occupational diseases and death. This should be reflected in the results of special assessment of working conditions and compensated via reduction of working hours. However, in the context of the pandemic, actual working hours of healthcare professionals exceeded the established 39 hours per week (Article 350 of the Labor Code of the Russian Federation), and the medical personnel were allowed to work with the pathogen of Group II pathogenicity without preliminary medical examinations.Conclusion. Analysis of the results of special assessment of the working conditions of medical personnel showed that they do not reflect the actual harmful (dangerous) working conditions of employees involved in providing care to patients with new coronavirus infection in these medical and preventive institutions.

Numerical Simulation and Experimental Research of Oil-Free Scroll Air Compressor Based on CFD

Background: Compared with other types of compressors, although the scroll compressor has a simple structure and low noise, due to the limitation of the structure, it has defects such as excessively high discharge temperature, and has extremely high requirements on the machining accuracy of parts. The oil-free scroll compressor is a new type of scroll machine, which does not contain oil during the working process; it can be applied to cases with low displacement requirements and a high-pressure ratio. Objective: Taking a scroll compressor with a rated displacement of 0.6 as the research object, the analysis and research of the working performance parameters of the scroll compressor in actual work provide a certain theoretical basis for the improvement and optimization of the test prototype. Methods: The thermodynamic model of the scroll compressor in the actual working process is established by the variable-mass system thermodynamics and the control volume method. Based on the CFD method, a three-dimensional unsteady-state numerical simulation of the flow characteristics of the working fluid in the scroll compressor's working chamber is carried out in order to verify the thermodynamic model. Considering the accuracy of numerical simulation, a test platform with air as the working fluid is set up. Results: Through the thermodynamic model and numerical simulation, the changes of temperature, pressure and velocity in the working chamber of the scroll compressor with the orbiting angle of the main shaft as well as the gas force and torque acting on the orbiting scroll tooth are obtained. Through experiments, the law of volume flow and shaft power of the scroll compressor with the speed of change, and the law of the change of discharge temperature with pressure at different speeds are obtained. Conclusion: At the same time, the thermodynamic model established by considering heat transfer and leakage is more in line with the actual working process of the compressor; the mass exchange between adjacent working chambers of the scroll compressor has a greater impact on the temperature and pressure in the working chamber. Due to internal leakage and irreversible loss, such as heat transmission, there is a deviation between the theoretical volume flow and the actual volume flow.