Measuring foregone output under industry emission reduction target in the transportation sector

Numerous countries have implemented or are considering a range of policies to lower emissions from transportation. An analysis of the impacts of environmental regulation is a crucial issue, which has not been properly highlighted in the transportation literature, particularly in terms of the foregone output by such regulation. This study develops a novel DEA model that measures the foregone output when the industry emissions target is imposed. This model reflects the real regulatory process more appropriately than other models in that the authority in charge sets the emission reduction target first, and the transport operators respond to it. In addition, the model can test the industrywide impacts over a wide range of emission target values, which can help policy makers determine the optimal emission target. Finally, the proposed model was applied to the port industry in Korea. The results suggest that Korean ports can reduce their emissions by a maximum of 239,850 tons of CO₂, which accounts for 13% of the total emissions in 2010. The 13% reduction in emission, however, would result in $ 91,109,000 of foregone cargo traffic to the Korean economy. In addition, the foregone cargo traffic increases at much faster rate than the emission reduction rate. For example, the shadow price of emission differs by 2.25 times between the most moderate and strictest emission targets. This suggests that the government needs to impose moderate emission targets at the initial stages if it decides to minimize the regulatory impacts on the industry.     

基于CADDS5-PIPING的舰船管系三维模型到二维出图技术的开发应用

文章概述了进行舰船管系三维模型到二维出图技术开发的目的、意义。针对CADDS5-P IP ING的特点和二维出图的需求,提出了解决问题的方法,达到了研发的目的。     

我国交通运输业全要素生产率测算方法

为全面掌握我国交通运输业当前的运营状况和生产率水平,更准确地分析交通运输业的经济增长点和更好地促进行业高质量发展,利用Malmquist生产率指数模型,通过对全行业及分领域的投入产出要素的测算,分析了全行业的全要素生产率水平,并对比了行业各领域的全要素生产率发展情况。结果显示：2003—2018年,全行业全要素生产率在平稳波动中有所增长,各分领域的生产率也在波动中不断变化;公路、水路、民航的全要素生产率增长较快,年均增长率在3.6%左右,主要得益于资源配置效率和技术进步率的共同提高;铁路运输业全要素生产率年均增长率较低,低于行业平均水平。根据测算结果分析,应继续推进体制改革,加快行业转型升级步伐,推动资源配置效率的最大化,以提高行业全要素生产率。     

Correlations between industrial demands (direct and total) for communications and transportation in the U.S. economy 1947–1997

Using input–output (I–O) accounts provided by the U.S. Department of Commerce, this study investigates the aggregate relationships between the transportation and communications inputs demanded (directly and in total) by all industries in the U.S., and compares the results across time. We analyzed five pairs of Spearman correlations of transportation and communications demands (utilities, manufacturing, and overall) using the direct and total coefficient tables from the ten benchmark input–output years spanning 1947 to 1997. To correctly represent the overall economy-wide relationship, each industry (direct table) or commodity (total table) in the correlation was weighted proportionately to the monetary value of its contribution to the U.S. economy. In the analysis using direct I–O coefficients, we found a pattern of predominant complementarity between transportation and communications manufacturing, and substitution between transportation and communications utilities. There are intriguing indications, however, of a shift from substitution to complementarity in the latter case, beginning around 1987. In the analysis using total I–O coefficients, we found a pattern of complementarity for all years between transportation and communications manufacturing, and a pattern changing from substitution to complementarity for the remaining four pairs (transportation manufacturing and communications utilities; transportation utilities and communications manufacturing; the utilities pair; and the overall pair). Thus, from the industrial perspective (which constitutes a sizable proportion of the total demand for communications and transportation), it is not realistic in modern times to expect telecommunications to substitute for travel. Nevertheless, further research is needed into the specific causes of the observed shift from substitution to complementarity, and current trends should continue to be monitored for any changes.

LC滤波器在三相并联有源滤波器中的一种实用设计方法

本文对三相并联电力滤波器的输出LC滤波器进行了研究,考虑有源滤波器的输出电流的频宽和EMI标准对LC滤波器的参数进行设计,并给出了设计实例,仿真结果验证了设计方法的可行性.     

电流输出型快速响应电压传感器

分析了高导磁环形镍铁合金铁心线圈构成的电流输出型快速响应电压传感器的响应时间、工作原理及其改进设计后的工作电源电路;介绍了该种电压传感器的主要特点及由此所开发的系列产品的主要技术参数。     

某船主减速齿轮箱输出轴非正常磨损的原因分析及修理工艺

某"抓斗"挖泥船主减速齿轮箱输出轴出现非正常磨损,根据拆检结果,用公差配合原则和安装工艺要求进行了分析,认为轴颈非正常磨损是由轴与轴承内圈配合间隙过大和安装方法不当造成的,并采取具体措施进行了修复。     

Capacity and QoS based codebook construction for MIMO precoded spatial multiplexing systems with limited feedback

This paper deals with the design and performance analysis of transmit precoder optimization for multiple input multiple output (MIMO) systems with limited feedback of channel state information. A capacity criterion based optimal codebook construction algorithm for MIMO precoded spatial multiplexing systems is pre-sented. The optimal precoder structure combining precoding and power allocation is employed. Simulation results show that the capacity criteria based codebook can achieve higher capacity than that of equally power allocation based codebook of previous research.     

A review of input–output models on multisectoral modelling of transportation–economic linkages

Understanding the role of transportation in urban and regional economy is a persistent analytical topic within the transportation research community. Multi-sectoral input–output (IO) modelling, as a standard economic analysis tool, has great advantages in reflecting industrial interdependencies in an economy. The simplicity of IO and the well-known concept of multiplier effect also make it broadly used in both academia and practice. This paper provides an introduction of IO models and reviews the past IO studies from 2000 onward on modelling transportation–economic linkages. The following types of models are included: single-region, multi-region and random utility-based multi-region IO models, with central methodological features described. An evaluation of modelling issues brought to light by reviewing the literature is then presented. For future research, more critical attention should be directed towards IO’s modelling assumptions, spatial linkages and the static representation of the economy. In addition, there are needs for more attention in the following areas: sectoral aggregation, specification of household sector and the integration with transportation forecasting models. The paper concludes with brief recommendations on future IO applications.     

死区时间对正弦输出电压的影响研究

深入研究了死区时间对正弦输出电压的影响.死区时间是逆变电源正常工作的保证,随着死区时间的增长,逆变电源工作越安全,但同时逆变电源正弦输出电压波形质量变差,正弦输出电压有效值改变,将对负载造成影响.试验结果与理论分析的相一致.