电梯轿厢上行超速保护装置现状分析与检验要求

曳引驱动电梯上应装设符合要求的轿厢上行超速保护装置,使轿厢制停或使轿厢速度降低至对重缓冲器能够承受的设计范围内,防止“冲顶”事故。本文阐述了上行超速保护装置的设置历程,概述了上行超速保护装置的构成及现状,分析失效原因,提出检验方法。在此基础上指出检验过程中面临的问题,认为缺乏统一定性定量的试验方法及判别标准是目前亟待解决的问题关键,提出了相应的改善建议。     

铁路货车制造企业焊接烟尘治理探讨

为改善焊接作业环境、保护职工健康,基于某铁路货车企业的生产工艺和焊接烟尘治理难点,从完善焊接烟尘治理技术方案、优化焊接方法和焊接结构、改造厂房加强换气通风等方面总结治理措施,提出了焊接烟尘综合治理的新方向,即融入绿色设计思维、提高工艺制造水平、结合智能制造和采取综合治理方案。     

Value of time: Speeding behavior and gasoline prices

‘Value of Time’ (VOT) is a key parameter in economics and policy. This paper presents an alternative method to estimate VOT by analyzing an hourly dataset on drivers speeding behavior as a function of the gasoline price. Our identification strategy is novel as it is based on the intensive margin. In comparison, previous studies reveal VOT on the extensive margin, but choice alternatives have multiple attributes thereby potentially confounding estimates. Consistent with the range of the prior literature, we find a VOT of about 50% of the wage rate and analyze sources of bias from accidents and traffic tickets. These bias functions suggest that previous stated preference VOT estimates are likely downward whereas previous revealed preference estimates are likely upward biased.     

基于改进型AES算法汽车门禁系统的研究

汽车门禁系统已成为汽车智能与安全领域的重要一部分.车主手持智能钥匙靠近汽车,通过车载基站与钥匙的双频通信,实现车门的开与关,还可实现发动机的一键启动.同时,对信号加密采用了改进的AES算法,加入了循环扩展密钥,加大了密码的破解难度.并对整个系统进行了建模仿真,分析了信号传输的误码率.图6,表1,参5.     

The impact of gasoline emission on plants – a review

This review presents the status of knowledge about gasoline exhaust pollution and its impact biochemical and physiological characteristics of plants. Parameters on such as leaf conductance, membrane permeability, ascorbic acid, chlorophyll and relative water content have been used as indicators to assess the impact of gasoline exhaust pollution on plant health. Tolerant plants such as Mangifera indica Linn. are reported showing an insignificant decrease in the percentage of chlorophyll content (3.6%) and a significant increase in the percentage of ascorbic acid (84.6%) and sensitive plants such as Cassia fistula are reported showing a significant decrease in the percentage of chlorophyll (66.4%) as well as ascorbic acid (32.9%). In the case of ornamental plants, Dracaena deremensis has been reported to show an insignificant decrease in the chlorophyll content but a significant increase in the ascorbic acid, pH and relative water content, which were found to be in tolerant category, while Dianthus caryophyllus showed sensitive characteristics. Such plants can be used as sinks and bioindicators for gasoline exhaust pollution. Though several studies reported biochemical impacts of individual or combined exhaust gases on plant species, the cumulative effect of gasoline exhaust on plant species has not been studied extensively, especially in the developing countries.     

考虑设备跌落的天然气计量站失效后果计算方法

天然气计量站阀门多且检定流程中频繁使用桁车，常规天然气站场的失效后果计算方法难以评估由此带来的影响及后果。为此，在API 581标准基础上，考虑阀门截断作用对机械损伤事故的影响，选取管段组储气量为最大天然气泄漏量，并以动量定理为依据，研究了桁车失效所引发的设备跌落事故，建立了潜在影响面积计算模型；将影响面积内损伤的管段及设备、泄漏的天然气、伤亡的人员等折算为经济损失，形成了考虑设备跌落的天然气计量站失效后果计算方法；将该方法应用于某天然气计量站。研究结果表明:设备跌落事故损失金额为机械损伤事故的3倍；当考虑设备跌落事故时，管段风险等级由低级上升为中低级。研究结果可为天然气计量站失效后果评价提供理论支撑。     

A Technique for Estimating the Age of Regular/Mid-grade Gasolines Released to the Subsurface Since the Early 1970's

Investigators, regulators, and litigants having interest in gasoline hydrocarbon releases are almost always concerned with knowing when a release occurred. Gasoline releases to the subsurface have, historically, been the most difficult to age date because of their volatile nature and highly aromatic composition. Age dating of gasolines in the past has depended on the degree of weathering of the lower boiling hydrocarbons in gasoline, the use and disuse of lead, lead isotopes, the use of other additives such as methyl-tertiary-butyl ether, and major refining and formulation changes. However, these approaches are limited and many times difficult to demonstrate and apply. This paper describes a new age dating technique using gas chromatographic data. It is based on the progressive enhancement of the aromatics and the reduction of the normal alkanes (paraffins) in the manufacture of regular and mid-grade gasolines since the 1970s. The changing composition of gasoline was necessary to maintain octane ratings during the removal of lead from the gasoline and while meeting increasingly stringent air quality regulations over the past 30 years. This paper proposes the use of an index that reflects these changes in gasoline composition over time and can be correlated to when the gasoline was manufactured. The resulting curve can be used to estimate the age of release (manufacture) of gasolines. This forensic application can be successfully applied to liquid gasoline samples where the evaporation of the gasoline is less than 50%. Case histories and examples are presented to demonstrate application of the technique.     

The welfare effects of fuel conservation policies in a dual-fuel car market: Evidence from India

We estimate a model of vehicle choice and kilometers driven to analyze the long-run impacts of fuel conservation policies in the Indian car market. We simulate the effects of petrol and diesel fuel taxes and a diesel car tax, taking into account their interactions with the pre-existing petrol fuel tax and car sales taxes. At levels sufficient to reduce total fuel consumption by 7%, the increased diesel and petrol fuel taxes both yield deadweight losses (net of externalities) of about 4 (2010) Rs./L. However, at levels sufficient to reduce total fuel consumption by 2%, the increased petrol fuel tax results in a deadweight loss per liter of fuel conserved that is greater than that caused by the diesel fuel tax. This reflects both the high pre-existing tax on petrol fuel and the high own-price elasticities of fuel demand in India. A tax on diesel cars that results in the same diesel market share as the large diesel fuel tax actually has a negative deadweight loss per liter of fuel conserved. The welfare effects of all three policy instruments are positive, once the external benefits of reducing fuel consumption are added to the excess burden of taxation.     

小曲率轿车覆盖件拉深模设计

在分析小曲率轿车覆盖件成形特点的基础上,指出采用阶梯拉深是提高材料塑性变形、减少回弹的有效措施,以一个典型零件前盖外板为例,设计了其拉深工艺补充面,并给出了有限元模拟结果以验证有效性。     

甲基叔丁基醚和三羰基甲基戊基锰的毒理学比较

在汽油无铅化的进程中，甲基叔丁基醚和三羰基甲基戊基锰是两种主要的汽油添加剂。它们可有效地增加汽油的辛烷值，提高汽油的燃烧效率；同时，作为氧化剂，还可减少ＣＯ和其它有在物质的排放。但是，这两种物质会否给人体健康带来潜在的危害或影响，也日益引起广泛的关注。