汽车行驶速度对运输安全的影响

改革开放以来,我国加大了对能源、铁路、公路建设的投入,高速公路、立体交通发展迅速,特别是在南方地区。现就国内、国外汽车行驶速度对安全运输的影响做一分析: 七十年代国外(日、美、英)立体交通、封闭式高速公路之大量出现,从原理上来讲,汽车都是专线行驶应减少交通事故,经调查却不是这样,事故不但没减少反而有增     

基于运行速度的山区新建高速公路限速方案调整研究

指出了目前我国山区新建高速公路统一采用设计速度进行限速,导致高速公路部分路段限速偏低,限制速度与驾驶员行车期望速度不一致,甚至导致多数驾驶员依据道路状况超速行车,限速值失去了说服力,同时影响了道路的运输效率,使得高速公路功能无法得到有效发挥。通过对西部某省山区新建高速公路现场调研和运行速度观测,分析了现有限速方案的合理性,结合运行速度特征、道路交通量与交通组成、道路环境、历史事故等研究限速方案调整的可行性,考虑山区高速公路特殊构筑物位置进行限速区合理划分,根据限速调整方案对道路条件进行了检查并提出了特殊路段相应安全保障措施。     

汽车运材系统管理初探

为适应木材运输需要,提出以系统工程原理为基础,以驾驶员、汽车列车、道路和外部环境四要素组成的汽车运材系统。通过对该系统的研究,可全面系统地改进和解决汽车运材管理中的主要问题,提高管理水平。     

道路运输经营状态的预报

目前,根据道路状态的检查与评价结果来确定和规化道路维修实施方法,其缺点在于规定的那些道路工作状态与标准要求不符,出现了不允许的变形和破坏,以及现行道路的参数、指标与复杂的交通密度和组成不符.这样一来要提高道路的运输一经营,就必须预报在复杂交通密度和组成下道路的变形,破坏的形成及发展过程.通常在第一阶段,路面、路基和其它道路部份的变形发展是很慢的,而以后开始急剧增加,出现个别或大量的破坏.要消除变形和破坏包括预防的办法采用越晚则所要的经费就越多.这是由于降低车速,道路运输损失增大;交通事故油脂燃料消耗、轮胎磨损加大;以及维修费用增多等原因造成的.     

林区汽车维修业的现状分析

随着我国汽车保有量的增加，汽车维修业作为道路运输的五个子行业之一也正在迅速发展。在林区的汽车保有车辆总数中，企业保有数量的比例正在逐渐减少，汽车维修的社会化越来越明显。而且随着汽车技术的不断进步，汽车维修过程中智能化和信息化的程度也在不断提高。因此，林区汽车维修企业，如何面对市场经济的发展，已成为业内人士普遍关注的问题。１　林区汽车维修业发展概况 我国汽车维修业的发展，按企业所有制的性质可划分为三个时期，即私有小型化时期，国有标准化时期和市场多元化时期。这三个时期的划分，基本上是与我国经济体制和…     

运材汽车在低温和山区道路上的使用技术

总结了运材汽车在低温和山区冰雪复杂路面上的使用技术及驾驶经验,给出了不同道路、不同车速情况下安全制动距离的参考值,这对减少和避免运材汽车发生事故具有非常重要的意义,特别是对运材汽车年轻驾驶员具有重要的指导作用。     

城市道路破冰除雪机使用要求及性能参数论证

清除道路冰雪,保持交通畅通,是我国北方地区城市、林区、农村道路冬季养护的常规作业。由于机械化程度低,不能及时清除路面冰雪,往往形成冰雪公害,阻塞交通,交通事故频生,车速降低,运输效率降低,油耗增高,城市道路尤为突出。仅以哈尔滨市为例,由于冬季路面冰雪公害,车速降低,车辆周转慢,使乘客留站时间延长,在早晚上下班高峰期,平均延长20分钟左右,按每日上下班60万人次计算,整个冬季约损失工时600万个;路面冰雪公害,也使公共电汽车公司运营减少,电车公司相当于每日少出67台车;路面冰雪公害,也影响货运,据市交通局统计,1985年就少运货物90万吨;由于路面     

正确换档是汽车驾驶的关键

汽车驾驶时,由于道路、地形、交通等情况的变化以及车速的需要,换档相当频繁.能否及时、正确的换档,对于维护车辆机件、保持车辆行驶平稳,充分利用发动机动力和节约燃料、机件,以及延长车辆寿命等都有很大关系.这也是考核驾驶员技术水平的一项主要内容.     

浅析汽车安全新技术与道路交通安全

指出了随着汽车保有量的剧增,道路交通事故发生率在不断上升,因道路交通事故而产生的伤害和死亡率一直居高不下,分析了道路交通安全的影响因素,从汽车安全新技术方面分析和阐述了车辆及行人在提高道路交通安全方面的重要作用,并提出了相应的建议和设想。     

道路安全评价实施构想

交通安全问题严重危害了社会经济及人们的社会生活及家庭幸福.如何减少交通事故、降低交通事故的严重程度,提高道路安全性,国内外专家学者都进行了大量研究.英国、澳大利亚等发达国家实践证明实施道路安全评价是一种行之有效的方法,我国在道路规划、设计、运营中强制实施道路安全评价是必须的,建立道路安全信息系统数据库也是必须的.     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.