Wireless Sensor Network(WSN)is a cornerstone of Internet of Things(IoT)and has rich application scenarios.In this work,we consider a heterogeneous WSN whose sensor nodes have a diversity in their Residual Energy(RE).I...Wireless Sensor Network(WSN)is a cornerstone of Internet of Things(IoT)and has rich application scenarios.In this work,we consider a heterogeneous WSN whose sensor nodes have a diversity in their Residual Energy(RE).In this work,to protect the sensor nodes with low RE,we investigate dynamic working modes for sensor nodes which are determined by their RE and an introduced energy threshold.Besides,we employ an Unmanned Aerial Vehicle(UAV)to collect the stored data from the heterogeneous WSN.We aim to jointly optimize the cluster head selection,energy threshold and sensor nodes’working mode to minimize the weighted sum of energy con-sumption from the WSN and UAV,subject to the data collection rate constraint.To this end,we propose an efficient search method to search for an optimal energy threshold,and develop a penalty-based successive convex approximation algorithm to select the cluster heads.Then we present a low-complexity iterative approach to solve the joint optimization problem and discuss the implementation procedure.Numerical results justify that our proposed approach is able to reduce the energy consumption of the sensor nodes with low RE significantly and also saves energy for the whole WSN.展开更多
Context: Working conditions in the car repair sector are difficult in general. This leads to health risk factors for inexperienced staff. In the bodywork painting workshop, the staff seemed less interested in the risk...Context: Working conditions in the car repair sector are difficult in general. This leads to health risk factors for inexperienced staff. In the bodywork painting workshop, the staff seemed less interested in the risks probably due to negligence or by lack of knowledge. This work aimed to describe the working conditions and their impact on the workers’ health in a workshop of bodywork painting in Conakry. Material and Methods: This was a cross-sectional study over 06 months (from July 01, 2021, to December 31, 2021). Were included the bodybuilders-painters, the painters and the bodybuilders. The data was collected during an interview. We analysed the personal data of the workers, the physical environment factors (lighting, noise, etc.) and, the clinical manifestations felt by the workers. Results: The average age was 37 years extenting from 18 to 54 years and, they were all men. Over 80% of workers were exposed to more than 1000 lux and, 78.2% of workers were exposed to the vibratory intensity level of the cordless drill > 2.5 m/s2. The most frequent symptoms were back pain, headache, itchy eyes, and numbness of fingers and hands. The analysis of working conditions and clinical manifestations showed a significant relationship between the level of illumination and the tingling eyes (p = 0.0007), the vibratory intensity of the drill and the numbness of fingers and hands (p = 0.01). This study revealed that some of the complaints cited are related to the working conditions. Conclusion: Working conditions in a bodywork paint workshop are occupational risk factors that become dangerous if they are unknown. A longitudinal study on the assessment of working conditions could better enlighten us on this phenomenon.展开更多
基金supported in part by the National Nature Science Foundation of China under Grant 62001168in part by the Foundation and Application Research Grant of Guangzhou under Grant 202102020515.
文摘Wireless Sensor Network(WSN)is a cornerstone of Internet of Things(IoT)and has rich application scenarios.In this work,we consider a heterogeneous WSN whose sensor nodes have a diversity in their Residual Energy(RE).In this work,to protect the sensor nodes with low RE,we investigate dynamic working modes for sensor nodes which are determined by their RE and an introduced energy threshold.Besides,we employ an Unmanned Aerial Vehicle(UAV)to collect the stored data from the heterogeneous WSN.We aim to jointly optimize the cluster head selection,energy threshold and sensor nodes’working mode to minimize the weighted sum of energy con-sumption from the WSN and UAV,subject to the data collection rate constraint.To this end,we propose an efficient search method to search for an optimal energy threshold,and develop a penalty-based successive convex approximation algorithm to select the cluster heads.Then we present a low-complexity iterative approach to solve the joint optimization problem and discuss the implementation procedure.Numerical results justify that our proposed approach is able to reduce the energy consumption of the sensor nodes with low RE significantly and also saves energy for the whole WSN.
文摘Context: Working conditions in the car repair sector are difficult in general. This leads to health risk factors for inexperienced staff. In the bodywork painting workshop, the staff seemed less interested in the risks probably due to negligence or by lack of knowledge. This work aimed to describe the working conditions and their impact on the workers’ health in a workshop of bodywork painting in Conakry. Material and Methods: This was a cross-sectional study over 06 months (from July 01, 2021, to December 31, 2021). Were included the bodybuilders-painters, the painters and the bodybuilders. The data was collected during an interview. We analysed the personal data of the workers, the physical environment factors (lighting, noise, etc.) and, the clinical manifestations felt by the workers. Results: The average age was 37 years extenting from 18 to 54 years and, they were all men. Over 80% of workers were exposed to more than 1000 lux and, 78.2% of workers were exposed to the vibratory intensity level of the cordless drill > 2.5 m/s2. The most frequent symptoms were back pain, headache, itchy eyes, and numbness of fingers and hands. The analysis of working conditions and clinical manifestations showed a significant relationship between the level of illumination and the tingling eyes (p = 0.0007), the vibratory intensity of the drill and the numbness of fingers and hands (p = 0.01). This study revealed that some of the complaints cited are related to the working conditions. Conclusion: Working conditions in a bodywork paint workshop are occupational risk factors that become dangerous if they are unknown. A longitudinal study on the assessment of working conditions could better enlighten us on this phenomenon.
