Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is e...Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB, Probabilistic Seismic Hazard Analysis （PSHA） is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seis- mic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al. （1997） model with broadband approach and Shahi and Baker （2011） model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites.展开更多
随着食品安全问题日益受到重视,危害分析与关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系作为保障食品安全的重要手段,其有效实施与监控显得尤为重要。基于此,本文阐述了HACCP体系的内涵,分析了HACCP体系有效实施...随着食品安全问题日益受到重视,危害分析与关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系作为保障食品安全的重要手段,其有效实施与监控显得尤为重要。基于此,本文阐述了HACCP体系的内涵,分析了HACCP体系有效实施的路径,包括建立前提条件、确定关键控制点、设立监控程序等。同时,分析了HACCP体系在实施监控中存在的问题,如企业重视程度不足、监控手段落后等,并针对这些问题提出了相应的改进建议,旨在为食品企业和监管部门提供一些参考和借鉴,促进食品安全管理水平的提升。展开更多
通过田间试验,研究二甲戊灵等7种除草剂及混剂对大葱田不同时期杂草的防除效果及对大葱的安全性,以期为大葱田筛选高效、安全的禾本科杂草及阔叶杂草除草剂。结果表明,大葱移栽期、杂草苗前进行土壤封闭处理,二甲戊灵单剂对禾本科杂草...通过田间试验,研究二甲戊灵等7种除草剂及混剂对大葱田不同时期杂草的防除效果及对大葱的安全性,以期为大葱田筛选高效、安全的禾本科杂草及阔叶杂草除草剂。结果表明,大葱移栽期、杂草苗前进行土壤封闭处理,二甲戊灵单剂对禾本科杂草有较好防效,最高达到100%,但对阔叶杂草防效差;乙草胺单剂和精异丙甲草胺单剂对总草的防效均较低,介于36.39%~40.75%;二甲戊灵与乙氧氟草醚、辛酰溴苯腈混配均可以有效地防除杂草,其中二甲戊灵与乙氧氟草醚低剂量混配效果最佳,对总草的防效为68.28%,大葱的生长促进率为9.59%、增产率为11.81%。大葱生长期、杂草3~5叶期喷雾,精喹禾灵和乙氧氟草醚低剂量混配、精喹禾灵+辛酰溴苯腈+乙氧氟草醚三元复配对禾本科杂草和阔叶杂草防除效果最好,对总草的防效分别为74.74%、76.52%,前期虽对大葱有轻微药害,但不影响后期产量,大葱的生长促进率分别为1.29%、7.92%,大葱的增产率分别为88.96%、70.42%;精喹禾灵单剂、精喹禾灵和辛酰溴苯腈混配防除阔叶杂草效果较差,精喹禾灵和灭草松混配对除马泡瓜外的禾本科杂草和阔叶杂草都有一定的防效,这几种处理对总草的防效均低于40%。杂草苗前,推荐使用330 g/L二甲戊灵EC 2 250 m L/hm2+24%乙氧氟草醚EC 300 m L/hm2混配;杂草3~5叶期,推荐使用10%精喹禾灵EC 675 m L/hm2+24%乙氧氟草醚EC 900 m L/hm2、10%精喹禾灵EC 675 m L/hm2+30%辛酰溴苯腈EC 1 200 m L/hm2+24%乙氧氟草醚EC 750 m L/hm2混配,可以安全、有效地防除大葱田禾本科杂草及阔叶杂草。展开更多
目的:研究医用加速器机房辐射防护屏蔽设计方法,评价职业危害控制效果。方法:根据国际辐射防护和测量委员会(National Committee on Radiological and Protection,NCRP)发布的报告和国家卫计委发布的职业卫生标准计算机房屏蔽防护厚度,...目的:研究医用加速器机房辐射防护屏蔽设计方法,评价职业危害控制效果。方法:根据国际辐射防护和测量委员会(National Committee on Radiological and Protection,NCRP)发布的报告和国家卫计委发布的职业卫生标准计算机房屏蔽防护厚度,检测屏蔽效果;按照建设项目职业病危害放射防护评价规范,从机房防护、放射工作场所分区、异常照射控制、放射防护管理4个方面对项目可能产生的放射性职业危害进行评价。结果:屏蔽检测结果达到设定的管理限值要求,职业危害评价结果符合国家法律法规要求。结论:该防护改造方法可有效控制放射性职业危害,确保职业人员、患者或公众的健康与安全。展开更多
文摘Many destructive earthquakes happened in Tehran, Iran in the last centuries. The existence of active faults like the North Tehran is the main cause of seismicity in this city. According to past investigations, it is estimated that in the scenario of activation of the North Tehran fault, many structures in Tehran will collapse. Therefore, it is necessary to incorporate the near field rupture directivity effects of this fault into the seismic hazard assessment of important sites in Tehran. In this study, using calculations coded in MATLAB, Probabilistic Seismic Hazard Analysis （PSHA） is conducted for an important site in Tehran. Following that, deaggregation technique is performed on PSHA and the contribution of seis- mic scenarios to hazard is obtained in the range of distance and magnitude. After identifying the North Tehran fault as the most hazardous source affecting the site in 10000-year return period, rupture directivity effects of this fault is incorporated into the seismic hazard assessment using Somerville et al. （1997） model with broadband approach and Shahi and Baker （2011） model with narrowband approach. The results show that the narrowband approach caused a 27% increase in the peak of response spectrum in 10000-year return period compared with the conventional PSHA. Therefore, it is necessary to incorporate the near fault rupture directivity effects into the higher levels of seismic hazard assessment attributed to important sites.
文摘随着食品安全问题日益受到重视,危害分析与关键控制点(Hazard Analysis and Critical Control Point,HACCP)体系作为保障食品安全的重要手段,其有效实施与监控显得尤为重要。基于此,本文阐述了HACCP体系的内涵,分析了HACCP体系有效实施的路径,包括建立前提条件、确定关键控制点、设立监控程序等。同时,分析了HACCP体系在实施监控中存在的问题,如企业重视程度不足、监控手段落后等,并针对这些问题提出了相应的改进建议,旨在为食品企业和监管部门提供一些参考和借鉴,促进食品安全管理水平的提升。
文摘通过田间试验,研究二甲戊灵等7种除草剂及混剂对大葱田不同时期杂草的防除效果及对大葱的安全性,以期为大葱田筛选高效、安全的禾本科杂草及阔叶杂草除草剂。结果表明,大葱移栽期、杂草苗前进行土壤封闭处理,二甲戊灵单剂对禾本科杂草有较好防效,最高达到100%,但对阔叶杂草防效差;乙草胺单剂和精异丙甲草胺单剂对总草的防效均较低,介于36.39%~40.75%;二甲戊灵与乙氧氟草醚、辛酰溴苯腈混配均可以有效地防除杂草,其中二甲戊灵与乙氧氟草醚低剂量混配效果最佳,对总草的防效为68.28%,大葱的生长促进率为9.59%、增产率为11.81%。大葱生长期、杂草3~5叶期喷雾,精喹禾灵和乙氧氟草醚低剂量混配、精喹禾灵+辛酰溴苯腈+乙氧氟草醚三元复配对禾本科杂草和阔叶杂草防除效果最好,对总草的防效分别为74.74%、76.52%,前期虽对大葱有轻微药害,但不影响后期产量,大葱的生长促进率分别为1.29%、7.92%,大葱的增产率分别为88.96%、70.42%;精喹禾灵单剂、精喹禾灵和辛酰溴苯腈混配防除阔叶杂草效果较差,精喹禾灵和灭草松混配对除马泡瓜外的禾本科杂草和阔叶杂草都有一定的防效,这几种处理对总草的防效均低于40%。杂草苗前,推荐使用330 g/L二甲戊灵EC 2 250 m L/hm2+24%乙氧氟草醚EC 300 m L/hm2混配;杂草3~5叶期,推荐使用10%精喹禾灵EC 675 m L/hm2+24%乙氧氟草醚EC 900 m L/hm2、10%精喹禾灵EC 675 m L/hm2+30%辛酰溴苯腈EC 1 200 m L/hm2+24%乙氧氟草醚EC 750 m L/hm2混配,可以安全、有效地防除大葱田禾本科杂草及阔叶杂草。
文摘目的:研究医用加速器机房辐射防护屏蔽设计方法,评价职业危害控制效果。方法:根据国际辐射防护和测量委员会(National Committee on Radiological and Protection,NCRP)发布的报告和国家卫计委发布的职业卫生标准计算机房屏蔽防护厚度,检测屏蔽效果;按照建设项目职业病危害放射防护评价规范,从机房防护、放射工作场所分区、异常照射控制、放射防护管理4个方面对项目可能产生的放射性职业危害进行评价。结果:屏蔽检测结果达到设定的管理限值要求,职业危害评价结果符合国家法律法规要求。结论:该防护改造方法可有效控制放射性职业危害,确保职业人员、患者或公众的健康与安全。
