为揭示交叉口车道的布设、交通流量、车辆所在时空位置等要素对直行车辆出口车道选择行为的影响,保障直行车流运行安全,运用专家知识和相关性分析确定了由最内侧直行车道中线偏移角、进口车道位置等10个影响因素组成的贝叶斯网络(Bayesi...为揭示交叉口车道的布设、交通流量、车辆所在时空位置等要素对直行车辆出口车道选择行为的影响,保障直行车流运行安全,运用专家知识和相关性分析确定了由最内侧直行车道中线偏移角、进口车道位置等10个影响因素组成的贝叶斯网络(Bayesian Network,BN)结构,采用数据驱动法进行了参数学习,建立了直行出口车道选择BN模型。经验证,模型的平均绝对偏差(Mean Absolute Error,MAE)、均方根误差(Root Mean Square Deviation,RMSE)分别为4.37%、4.96%,具有良好的精度。应用正向推理得到:影响直行出口车道选择的主要因素是进口车道位置、进出口车道数量匹配性、进出口车道选择不匹配比例、最内侧车道中线偏移角;引入情景分析法可有效预测进口车道平均流量等不同影响因素组合波动时出口车道利用率的变化,如直行车辆由最内侧进口车道驶入直行最内侧车道中线左偏移角为2°~4°的交叉口,在直行车流为>600~900辆/(h·道)、绿色信号倒数(Green Signal Countdown Display,GSCD)显示到达的条件下,选择最内侧出口道的概率为44.6%。研究结果为交通管理部门提供了直行出口车道选择的预测工具,为交叉口直行车流安全理论研究提供支持与参考。展开更多
Although either absolute speed or speed difference can be considered as a measure for speed consistency, few researches consider both in practice. The factor analysis method was introduced to extract an optimal number...Although either absolute speed or speed difference can be considered as a measure for speed consistency, few researches consider both in practice. The factor analysis method was introduced to extract an optimal number of factors from numerous original measures. The freeway diverging zone was divided into four elements, namely the upstream, the diverge area, the downstream and the exit ramp. Operating speeds together with individual vehicle speeds were collected at each element with radar guns. Following the factor analysis procedure, two factors, which explain 96.722% of the variance in the original data, were retained from the initial seven speed measures. According to the loadings after Varimax rotation, the two factors are clearly classified into two categories. The first category is named "speed scale" reflecting the absolute speed, and the other one is named "speed dispersion" interpreting speed discreteness. Then, the weighted score of speed consistency for each diverge area is given in terms of linear combination of the two retained factors. To facilitate the level classification of speed consistency, the weighted scores are normalized in the range of (0, 1.0). The criterion for speed consistency classification is given as 0≤F N <0.30, good consistency; 0.30≤F N <0.60, fair consistency; 0.60≤ F N ≤1.00, poor consistency. The validation by comparing with previously developed measures shows that the proposed measure is acceptable in evaluating speed consistency.展开更多
China has built three policy banks since 1994, which are China Development Bank, China Export-import Bank and China Agricultural Development Bank. Policy banks, as an important financial instrument, have made great co...China has built three policy banks since 1994, which are China Development Bank, China Export-import Bank and China Agricultural Development Bank. Policy banks, as an important financial instrument, have made great contributions to the development of China＇ s economy. But there isn＇ t an official law fbr policy banks for a long time. They just operate based on some relevant documents and regulations of their own. However these documents and regulations are always indistinct in law, which is not good for the further development of policy banks and the accomplishment of our country＇ s financial system. As a result, in order to standardize the operation of China＇ s policy banks, it＇ s essential to position policy banks in law accurately, which is also the only way to legalize policy banks. Aiming at finding out the problems existing in policy banks of China in present, this paper analyzes the general theory of policy banks, some relevant international experience and the current situation of law position of china＇ s policy banks. In addition, through the analyses of possible solutions, this paper wishes to reconstruct the legal location of China ＇ s policy banks.展开更多
Romania has the potential of resources, labor and real capacity to adapt to the gait of a global economic competition. But it required a long term policy and environment which could support this potential value. If no...Romania has the potential of resources, labor and real capacity to adapt to the gait of a global economic competition. But it required a long term policy and environment which could support this potential value. If not, we will risk turning into a consumer economy, consumption will not be funded on internal production and become supplier of labor services for peripheral. In the context of economic crisis, Romanian furniture retains its significant competitive advantages, including the price in export markets. The most important markets for exporters of furniture from Romania are Ukraine and Russia, markets with great potential, but affected by problems such as devaluing local currencies, and recently, imposing new duties.展开更多
In the first half of 2005. the import of erude oil increased 4% up of the same period, but the net import of petroleum products including crude oil, oil products, liquefied petroleum gas （LPG） and others declined 7%...In the first half of 2005. the import of erude oil increased 4% up of the same period, but the net import of petroleum products including crude oil, oil products, liquefied petroleum gas （LPG） and others declined 7% of the same period last year. As the oil price in international market continuously climbs up and creates new records,展开更多
Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixt...Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixteen signalized intersections in the Nanjing area in China. The risk-taking behaviors of the drivers of taxis and private cars were compared. The results suggest that 19.9% of taxi drivers have committed at least one of the identified risky behaviors, which is 2.37 times as high as that of the drivers of private cars(8.4%). The traffic conflicts technique was used to estimate the safety effects of taxis and private cars. The overall conflict rate for taxis is 21.4% higher than that for private cars, implying that taxis are more likely to be involved in conflicts. Almost all of the identified traffic conflicts can be attributed to certain levels of risk-taking behaviors committed by either taxi drivers or the drivers of private cars, and taxi drivers are more likely to be at fault in a conflict. Failure to yield to right-of-way and improper lane change is the leading causes of the conflicts in which taxis are at-fault. The research team further studied the effects of taxis on the queue discharge characteristics at signalized intersections. The results show that the presence of taxis significantly reduces both start-up lost time and saturation headways. The effects of taxis on saturation flow rates are dependent on the proportion of taxis in the discharge flow, and the saturation flow rates increase with the increase in the proportion of taxis. The adjustment factors for various proportions of taxis for different turning movements are then calculated to quantitatively evaluate the effects of taxis on the capacity of signalized intersections.展开更多
This paper sets up a simplified dynamic discrete selection model to analyze two-stage decision of corporate export behavior and influence of exchange rate under the framework of profit maximization. Then we adopt Heck...This paper sets up a simplified dynamic discrete selection model to analyze two-stage decision of corporate export behavior and influence of exchange rate under the framework of profit maximization. Then we adopt Heckman selection model to estimate general effects and structural effects of RMB appreciation on export based on the sample data of China Industrial Enterprises from 2005 to 2009. Findings reveal that RMB appreciation has exerted a significant negative impact to corporate export through extensive margins and intensive margins. Meanwhile, due to different corporate strategies of heterogeneous enterprises, RMB appreciation cannot achieve the expected effect of ＂survival of the fittest＂ and is instead unfavorable to the optimization of export structure. RMB appreciatiou drives industry structure of export to evolve towards advanced levels to a certain extent. However, such a positive effect mainly derives from the contribution of foreign-funded enterprises while restricting development space of indigenous firms in the sector of advanced manufacturing.展开更多
文摘为揭示交叉口车道的布设、交通流量、车辆所在时空位置等要素对直行车辆出口车道选择行为的影响,保障直行车流运行安全,运用专家知识和相关性分析确定了由最内侧直行车道中线偏移角、进口车道位置等10个影响因素组成的贝叶斯网络(Bayesian Network,BN)结构,采用数据驱动法进行了参数学习,建立了直行出口车道选择BN模型。经验证,模型的平均绝对偏差(Mean Absolute Error,MAE)、均方根误差(Root Mean Square Deviation,RMSE)分别为4.37%、4.96%,具有良好的精度。应用正向推理得到:影响直行出口车道选择的主要因素是进口车道位置、进出口车道数量匹配性、进出口车道选择不匹配比例、最内侧车道中线偏移角;引入情景分析法可有效预测进口车道平均流量等不同影响因素组合波动时出口车道利用率的变化,如直行车辆由最内侧进口车道驶入直行最内侧车道中线左偏移角为2°~4°的交叉口,在直行车流为>600~900辆/(h·道)、绿色信号倒数(Green Signal Countdown Display,GSCD)显示到达的条件下,选择最内侧出口道的概率为44.6%。研究结果为交通管理部门提供了直行出口车道选择的预测工具,为交叉口直行车流安全理论研究提供支持与参考。
基金Project(2012CB725400) supported by the National Key Basic Research Program of ChinaProject(2012AA112304) supported by the National High Technology Research and Development Program of ChinaProject(2009BAG13A07-5) supported by National Science and Technology Plan of Action of China for Traffic Safety
文摘Although either absolute speed or speed difference can be considered as a measure for speed consistency, few researches consider both in practice. The factor analysis method was introduced to extract an optimal number of factors from numerous original measures. The freeway diverging zone was divided into four elements, namely the upstream, the diverge area, the downstream and the exit ramp. Operating speeds together with individual vehicle speeds were collected at each element with radar guns. Following the factor analysis procedure, two factors, which explain 96.722% of the variance in the original data, were retained from the initial seven speed measures. According to the loadings after Varimax rotation, the two factors are clearly classified into two categories. The first category is named "speed scale" reflecting the absolute speed, and the other one is named "speed dispersion" interpreting speed discreteness. Then, the weighted score of speed consistency for each diverge area is given in terms of linear combination of the two retained factors. To facilitate the level classification of speed consistency, the weighted scores are normalized in the range of (0, 1.0). The criterion for speed consistency classification is given as 0≤F N <0.30, good consistency; 0.30≤F N <0.60, fair consistency; 0.60≤ F N ≤1.00, poor consistency. The validation by comparing with previously developed measures shows that the proposed measure is acceptable in evaluating speed consistency.
文摘China has built three policy banks since 1994, which are China Development Bank, China Export-import Bank and China Agricultural Development Bank. Policy banks, as an important financial instrument, have made great contributions to the development of China＇ s economy. But there isn＇ t an official law fbr policy banks for a long time. They just operate based on some relevant documents and regulations of their own. However these documents and regulations are always indistinct in law, which is not good for the further development of policy banks and the accomplishment of our country＇ s financial system. As a result, in order to standardize the operation of China＇ s policy banks, it＇ s essential to position policy banks in law accurately, which is also the only way to legalize policy banks. Aiming at finding out the problems existing in policy banks of China in present, this paper analyzes the general theory of policy banks, some relevant international experience and the current situation of law position of china＇ s policy banks. In addition, through the analyses of possible solutions, this paper wishes to reconstruct the legal location of China ＇ s policy banks.
文摘Romania has the potential of resources, labor and real capacity to adapt to the gait of a global economic competition. But it required a long term policy and environment which could support this potential value. If not, we will risk turning into a consumer economy, consumption will not be funded on internal production and become supplier of labor services for peripheral. In the context of economic crisis, Romanian furniture retains its significant competitive advantages, including the price in export markets. The most important markets for exporters of furniture from Romania are Ukraine and Russia, markets with great potential, but affected by problems such as devaluing local currencies, and recently, imposing new duties.
文摘In the first half of 2005. the import of erude oil increased 4% up of the same period, but the net import of petroleum products including crude oil, oil products, liquefied petroleum gas （LPG） and others declined 7% of the same period last year. As the oil price in international market continuously climbs up and creates new records,
基金Projects(51322810,50908050)supported by the National Natural Science Foundation of China
文摘Comparative analyses were conducted to compare the effects of the behavioral characteristics of the drivers of taxis and private cars on the capacity and safety of signalized intersections. Data were collected at sixteen signalized intersections in the Nanjing area in China. The risk-taking behaviors of the drivers of taxis and private cars were compared. The results suggest that 19.9% of taxi drivers have committed at least one of the identified risky behaviors, which is 2.37 times as high as that of the drivers of private cars(8.4%). The traffic conflicts technique was used to estimate the safety effects of taxis and private cars. The overall conflict rate for taxis is 21.4% higher than that for private cars, implying that taxis are more likely to be involved in conflicts. Almost all of the identified traffic conflicts can be attributed to certain levels of risk-taking behaviors committed by either taxi drivers or the drivers of private cars, and taxi drivers are more likely to be at fault in a conflict. Failure to yield to right-of-way and improper lane change is the leading causes of the conflicts in which taxis are at-fault. The research team further studied the effects of taxis on the queue discharge characteristics at signalized intersections. The results show that the presence of taxis significantly reduces both start-up lost time and saturation headways. The effects of taxis on saturation flow rates are dependent on the proportion of taxis in the discharge flow, and the saturation flow rates increase with the increase in the proportion of taxis. The adjustment factors for various proportions of taxis for different turning movements are then calculated to quantitatively evaluate the effects of taxis on the capacity of signalized intersections.
文摘This paper sets up a simplified dynamic discrete selection model to analyze two-stage decision of corporate export behavior and influence of exchange rate under the framework of profit maximization. Then we adopt Heckman selection model to estimate general effects and structural effects of RMB appreciation on export based on the sample data of China Industrial Enterprises from 2005 to 2009. Findings reveal that RMB appreciation has exerted a significant negative impact to corporate export through extensive margins and intensive margins. Meanwhile, due to different corporate strategies of heterogeneous enterprises, RMB appreciation cannot achieve the expected effect of ＂survival of the fittest＂ and is instead unfavorable to the optimization of export structure. RMB appreciatiou drives industry structure of export to evolve towards advanced levels to a certain extent. However, such a positive effect mainly derives from the contribution of foreign-funded enterprises while restricting development space of indigenous firms in the sector of advanced manufacturing.
