Ergonomics research strives to make workers’ labor more efficient, safer, and more comfortable. Therefore, six digital humans and welding torch model were built and evaluated based on the Jack software in order to improve the ergonomics of welders’ standing postures. Three sets of standing welding actions were designed: walking, raising arm, and contracting arm. Through the Lower Back Analysis, Ovako Working Posture Analysis, Comfort Assessment, and Rapid Upper Limb Assessment, this paper evaluated the optimum range of the weight of the welding torch, the upper limb posture, and the neck posture of the welder. Firstly, the results show that Chinese welders should not use a welding torch with a weight of more than 6 kg when standing up. Secondly, for adult males in the 5th, 50th, 95th percentile of body size, the best operating distance is 321 mm, 371 mm, and 421 mm, respectively, and the best operating height is 1050 mm, 1100 mm, and 1150 mm, respectively; for females in the same percentiles, the optimal operating distance is 271 mm, 321 mm, and 371 mm, respectively, and the optimal operating height is 1000 mm, 1050 mm, and 1100 mm, respectively. Moreover, the horizontal and vertical rotation angle of the welder’s neck should not exceed 15° and 8.7°. The adjustment strategy not only has a positive effect on improving welders’ operational posture and preventing fatigue and injury to the welder, but it also develops research ideas for promoting safety from the perspective of ergonomics.

A uniform push–pull ventilation device can effectively improve indoor air quality (IAQ). The 90° rectangular elbow is an important part of the push–pull ventilation device. This paper analyzes the flow field characteristics of the 90° rectangular elbows under different working conditions. This was done by using computational fluid dynamics (CFD) simulation (Fluent). The flow lines, velocity and pressure distribution patterns of the elbow flow field are revealed in detail. The wind velocity non-uniformity and wind pressure non-uniformity of the 90° rectangular elbows with different coefficients of radius curvature R and rectangular section height h are also compared. The results show that when R ≥ 2.5 h, the wind flow traces inside the elbow are basically parallel lines. At the same time, the average wind velocity and the average wind pressure are stable. Also, the wind velocity non-uniformity and wind pressure non-uniformity decrease with the increase of R. Therefore, considering the space and material loss caused by an increase in radius of curvature, the elbow with R = 2.5 h can be used as the best design structure for the 90° rectangular elbow, which is of great significance for improving the control effect of dust and toxic pollutants in a uniform push–pull ventilation device.

The desktop slot exhaust hood has been widely used, but it is calculated by empirical formula. Axial velocity change rule of desktop slot exhaust hood can effectively provide the basis of the wind speed needed in order to control the poison. According to gas motion mathematical model, the geometry model and boundary conditions of desktop slot exhaust hood was established, and the influence of the hood sizes to axial velocity were analyzed by Fluent simulation. The changes of relationship between the axial velocity (V) and the distance from the hood mouth (L), the short edge of the hood mouth (a), the long edge of the hood mouth (b), the equivalent diameter of the hood mouth (d) and the square root of the hood mouth area (√A) were comparative analyzed by dimensionless processing. The result is the V/V0 with L/d have better change rule. The axial velocity change rule of different axial velocity were also analyzed using V/V0 with L/d change rule, and the change rule of V/V0 with L/d of desktop slot exhaust hood was obtained, which was verified by experiment.

A parallel-flow exhaust hood is an effective ventilation device to control dust and toxic pollutants and protect the occupational health of workers, whether it is used alone or combined with a uniform air supply hood in a push–pull ventilation system. Some scholars have studied the outside air flow characteristics of the conventional exhaust hood with non-uniform air speed at the hood face, but the law of velocity variation outside the parallel-flow exhaust hood is not clear at present. Therefore, this paper uses the dimensionless method to study the center-line velocity change regime in a parallel-flow square exhaust hood based on simulation and experimental data. The results show that the dimensionless center-line velocity has a good change law with the characteristic length of exhaust hood in a parallel-flow square exhaust hood, which can eliminate the influence of hood face velocity and the hood size on the velocity change regime; and the experimental data is basically consistent with the calculated data, which shows that the regression equation method is reliable.

The method of flow ratio k is often used for designing parallel push-pull ventilation. The k value is mostly selected empirically and is difficult to determine accurately, resulting in an imprecise design of the push-pull ventilation system. Therefore, parallel push-pull ventilation was taken as the research object in this paper. The push-pull ventilation studied consists of a square uniform supply hood and a square uniform exhaust hood, and the side length of pull hood and pull hood was same. A workbench was set between the push hood and pull hood, and the source of toluene pollutions was set in the center of the worktable surface. The optimal k values for different distances between push hood and pull hood were studied by numerical simulation using Ansys Fluent, which were obtained base on the distribution of wind speed and toluene concentration. The results showed that parallel push-pull ventilation is not suitable for applications when L/a ≥ 6. The changing patterns of k value with L/a is proposed in the range of 1.5 ≤ L/a ≤ 5 for the parallel square push-pull ventilation, which can be used to estimate k value relatively accurately under the condition that L/a is known, so as to guide the determination of the exhaust air volume of the parallel push-pull ventilation system.

As an important indicator to measure the adaptability and development potential of individuals in an organization, political skill is rarely considered as an antecedent variable in the field of safety voice. This study is based on impression management theory and social cognitive theory. From the perspective of employee self-service-oriented safety voice motivation, we took political skill as a predictor of safety voice behavior and introduced voice efficacy as an intermediary variable to construct a theoretical model of the relationship between political skill, voice efficacy, and safety voice behavior. We used the method of questionnaire to collect data from employees in high-risk industries. SPSS and AMOS software were used as analysis tools to examine the relationship between political skill, voice efficacy, and safety voice behavior. The study results show that: (1) political skill has a significant positive impact on safety voice behavior; and (2) voice efficacy plays a mediating role in the relationship between political skill and safety voice behavior. In this study, a new predictor of safety voice behavior and its mediation mechanism were obtained. Political skill can not only reflect the psychological cognitive ability of individuals in dangerous work environments, but it is also an important manifestation of the social exchanges between employees and organizations. In the special organizational context where China generally values “guanxi”, political skill has a stronger ability to predict and explain safety voice behavior. This research can help organizations obtain safety-related suggestions from employees in a timely manner and realize the sustainable development of safety management.