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基于NB-IoT的家居环境监控系统设计 被引量:8
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作者 王建新 王颖聪 《电子设计工程》 2020年第8期141-144,149,共5页
为解决传统家居环境监控系统存在功耗较高、配置网络复杂和安全可靠性低的问题,设计了一种基于NB-IoT(窄带物联网)技术的家居环境监控系统。系统采用STM32L431作为微处理器,以BC35-G为通信模块,利用CoAP协议将采集的数据信息周期性上报... 为解决传统家居环境监控系统存在功耗较高、配置网络复杂和安全可靠性低的问题,设计了一种基于NB-IoT(窄带物联网)技术的家居环境监控系统。系统采用STM32L431作为微处理器,以BC35-G为通信模块,利用CoAP协议将采集的数据信息周期性上报给云端服务器,云端服务器将数据信息推送至微信小程序,同时微信小程序也可以远程控制环境监测设备。经过测试和验证,该系统具有功耗低、自动联网和安全可靠性高的特点,实现了对家庭环境参数的实时监测与控制,能够较好地满足应用需求。 展开更多
关键词 NB-IoT STM32 CoAP TEA算法 环境监控系统 微信小程序
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Risk Factors of Low Back Pain among the Chinese Occupational Population:A Case-control Study 被引量:7
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作者 LI Jing Yun wang Sheng +6 位作者 HE Li Hua WU Shan Shan YANG Lei YU Shan Fa LI Li Ping wang jian xin HUANG Yan Di 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2012年第4期421-429,共9页
Objective To explore the risk factors of low back pain among the Chinese occupational population in several major industries. Methods A total of 7200 subjects (3600 cases and 3600 controls) were randomly sampled fro... Objective To explore the risk factors of low back pain among the Chinese occupational population in several major industries. Methods A total of 7200 subjects (3600 cases and 3600 controls) were randomly sampled from a cross-sectional study, and they were investigated for individual and occupational factors of low back pain. The potential risk factors were first selected by using chi-square tests. Secondly, collinearity diagnosis proceeded by using the Kendall's rank correlation. Finally, binary logistic regression model was used for multi-factor analysis. Results Collinearity diagnosis showed that there was a severe collinearity problem among the potential risk factors of low back pain. Logistic regression model included 20 variables with statistical significance. Bending neck forward or holding neck in a forward posturefor long periods (0R=1.408) was the most important risk factor inducing low back pain in this study, followed by bending heavily with the trunk (0R=1.402), carrying out identical work almost for the whole day (0R=1.340). Additionally, suHicient normal break was a protective factor of low back pain. Conclusion Low back pain among the Chinese occupational population was associated with body height, occupation, work organization, physical work, working posture, and others. All these risk factors could be regarded as the indicators of low back pain, and some relevant preventive measures should be taken to reduce low back pain risk. 展开更多
关键词 Case-control studies Low back pain Occupational health Risk factors
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