Objective:To explore the reduction effect for the indoor ^(222)Rn(Rn)by Fresh Air Ventilation(FAV)system,a novel commercial ventilation device in China.Methods:The indoor concentrations of Rn and its decay products(Rn...Objective:To explore the reduction effect for the indoor ^(222)Rn(Rn)by Fresh Air Ventilation(FAV)system,a novel commercial ventilation device in China.Methods:The indoor concentrations of Rn and its decay products(RnD)in three residential rooms,two in Beijing and one in Hefei city,Anhui province,before and after FAVS functioned were measured using an active continuous method.The air exchange rate was monitored by measuring CO_(2) concentration using the tracer gas method.Results:In the three rooms,the FAVS reduced the Rn concentrations from(162±80)Bq/m^(3) to(63±22)Bq/m^(3) and decreased the RnD concentrations from(64±35)Bq/m^(3) to(13±6)Bq/m^(3) on average,a decrease of(59±25)% in the Rn concentrations and a drop of(77±18)%in the RnD concentrations.Considering dose conversion factors of Rn and RnD,FAVS decreased the exposure dose by(76±20)%.Besides,FAVS increased the air exchange rates from 0.17 h^(-1) to 0.56 h^(-1) on average.Conclusions:FAVS can effectively reduce indoor Rn and RnD concentrations by improving the air exchange,serving as a valuable supplement to existing radon mitigation methods,especially in extreme climates.展开更多
表面组装技术(Surface Mount Technology,SMT)产品是当前板级电子电路产品的主要形式。以SMT产品为对象,以面向分析的设计(DFA)思想为驱动,提出了基于STEP标准的SMT产品信息模型与数据交换。基于多信息模型的建模思想,建立了融合几何信...表面组装技术(Surface Mount Technology,SMT)产品是当前板级电子电路产品的主要形式。以SMT产品为对象,以面向分析的设计(DFA)思想为驱动,提出了基于STEP标准的SMT产品信息模型与数据交换。基于多信息模型的建模思想,建立了融合几何信息、物理信息、性能信息与功能信息的SMT产品器件级和产品级两级信息模型,并进行了多信息模型的DFA可应用性分析,以SMT产品电子设计信息到制造信息的数据交换为目标,从源数据、前处理器、后处理器3个角度阐述了基于STEP标准的数据交换方法。展开更多
This paper examines global value chains at the level of the heterogeneous firm. The context is a world of horizontal intra-industry trade, characterized by imperfect competition and product differentiation at the firm...This paper examines global value chains at the level of the heterogeneous firm. The context is a world of horizontal intra-industry trade, characterized by imperfect competition and product differentiation at the firm level. Standard microeconomic tools are employed to assess the effects of inter-firm dissimilarities in both demand and supply on firms＇ responses to changes in trade policy. In this set-up, dissimilarities in firm characteristics play roles similar to factor endowments and technology differences in traditional trade models. When cross-border production sharing （＂fragmentation＂） is introduced into this framework, those differences in firm characteristics determine the degree to which individual firms will enter into production networks. In this context, horizontal and vertical intra-industry tradel elements interact in their effects on firm decisions. Traditional comparative advantage considerations still govern the choice of off-shored activities, while direct competition between imports and exports expands the range of possible outcomes. Finally, it is shown that cross-border production sharing reduces the sensitivity of firms to variations in exchange rates, matching a phenomenon that has been observed in traditional country-level models.展开更多
文摘Objective:To explore the reduction effect for the indoor ^(222)Rn(Rn)by Fresh Air Ventilation(FAV)system,a novel commercial ventilation device in China.Methods:The indoor concentrations of Rn and its decay products(RnD)in three residential rooms,two in Beijing and one in Hefei city,Anhui province,before and after FAVS functioned were measured using an active continuous method.The air exchange rate was monitored by measuring CO_(2) concentration using the tracer gas method.Results:In the three rooms,the FAVS reduced the Rn concentrations from(162±80)Bq/m^(3) to(63±22)Bq/m^(3) and decreased the RnD concentrations from(64±35)Bq/m^(3) to(13±6)Bq/m^(3) on average,a decrease of(59±25)% in the Rn concentrations and a drop of(77±18)%in the RnD concentrations.Considering dose conversion factors of Rn and RnD,FAVS decreased the exposure dose by(76±20)%.Besides,FAVS increased the air exchange rates from 0.17 h^(-1) to 0.56 h^(-1) on average.Conclusions:FAVS can effectively reduce indoor Rn and RnD concentrations by improving the air exchange,serving as a valuable supplement to existing radon mitigation methods,especially in extreme climates.
文摘表面组装技术(Surface Mount Technology,SMT)产品是当前板级电子电路产品的主要形式。以SMT产品为对象,以面向分析的设计(DFA)思想为驱动,提出了基于STEP标准的SMT产品信息模型与数据交换。基于多信息模型的建模思想,建立了融合几何信息、物理信息、性能信息与功能信息的SMT产品器件级和产品级两级信息模型,并进行了多信息模型的DFA可应用性分析,以SMT产品电子设计信息到制造信息的数据交换为目标,从源数据、前处理器、后处理器3个角度阐述了基于STEP标准的数据交换方法。
文摘This paper examines global value chains at the level of the heterogeneous firm. The context is a world of horizontal intra-industry trade, characterized by imperfect competition and product differentiation at the firm level. Standard microeconomic tools are employed to assess the effects of inter-firm dissimilarities in both demand and supply on firms＇ responses to changes in trade policy. In this set-up, dissimilarities in firm characteristics play roles similar to factor endowments and technology differences in traditional trade models. When cross-border production sharing （＂fragmentation＂） is introduced into this framework, those differences in firm characteristics determine the degree to which individual firms will enter into production networks. In this context, horizontal and vertical intra-industry tradel elements interact in their effects on firm decisions. Traditional comparative advantage considerations still govern the choice of off-shored activities, while direct competition between imports and exports expands the range of possible outcomes. Finally, it is shown that cross-border production sharing reduces the sensitivity of firms to variations in exchange rates, matching a phenomenon that has been observed in traditional country-level models.
