基于缓冲区分析的北京城市用地扩展研究

遥感和地理信息系统技术的结合,对于了解城市空间格局现状．研究城市扩展趋势具有显而易见的好处。本文以多时相遥感影像及其分类结果为原始数据．应用GIS提供的空间分析功能,以北京城市规划中十个边缘集团和部分卫星城以及六条放射形交通线为基础做缓冲区分析,对北京城市土地利用扩展做了定量的描述与分析,从而得到一些北京市城市土地扩展的结论;北京城市原有的分散集团式规划效用不大,城市中心区的集聚能力依然较突出,沿交通线的扩展非常明显。整体来说北部地区的城市扩展强度指数远大于过南部,但是未来南部地区需要成为北京城市用地扩展的重要方向。     

快速路合流影响区交通安全影响研究

为解决合流影响区对道路交通安全的影响,本研究以分析合流区的交通流特性和通行能力为出发点,通过HCM2000的理论计算和微观仿真的方法,与采集的观测数据结果进行对比,验证仿真结果的可行性,探讨匝道分流流量、减速段长度与分流影响区密度的关系,以4车道和6车道为例进行分析匝道分流流量、减速段长度与分流影响区密度的关系。结果表明,车道合流区密度随着合流与上游流量比例的增大而增大,在同样的分流合流与上游流量比下,4车道合流区的密度要比6车道小,并且两者都呈指数形式的增长;车道合流影响区密度随着加速段长度的增大而减小,当加速段长度为170m时6车道合流区的密度比加速道长度为150m情况下要大。当加速段长度大于240m时,车流密度下降趋势逐渐趋缓,且4车道与6车道的车流密度比较接近。     

Prevention strategies for field traffic-induced subsoil compaction: a review: Part 2. Equipment and field practices

The loads imposed by modern farm machinery have considerable potential to increase subsoil stress. Within the context of economically viable and environmentally sustainable systems, the practices associated with subsoil damage and methods for avoidance are identified. The greatest potential for damage is on fragile, wet or loosened subsoils combined with high wheel or track loads and contact pressures that create noticeable ruts in the topsoil. In-furrow ploughing increases this potential considerably by placing loads on the subsoil. Measures to avoid this potential involve a whole farm approach and an understanding of the many interactions between cropping systems and machinery. Alternatives to in-furrow ploughing that involve working from the surface and building a protective topsoil are discussed. Key measures to reduce the risk to subsoils involve a clear understanding of tyre load and inflation data and simple on-farm methods of achieving this are suggested. Although avoidance has the potential to reduce the risk, confinement of damage to specific strips in the field is seen as a realistic alternative. Controlled traffic operations, together with precision guidance, offer an economic means by which compaction on the cropped area can be avoided. The most effective route to improvement in soil care across the European Union (EU) is an appropriate management structure coupled with a best practice framework.     

Wheel traffic and tillage effects on runoff and crop yield

Traffic and tillage effects on runoff, soil water and crop production under rainfall were investigated over a period of 6 years on a heavy clay vertosols (vertisols) in Queensland, Australia. A split plot design was used to isolate traffic effects, while the cropping program and treatments were broadly representative of extensive grain production practice in the northern grain region of Australia. Treatments subject to zero tillage and stubble mulch tillage each comprised pairs of 90 m² plots, from which runoff was recorded. A 3 m wide controlled traffic system allowed one of each pair to be maintained as a non-wheeled plot, while the complete surface area of the other received a single annual wheeling treatment from a working 100 kW tractor.

Mean annual runoff from controlled traffic plots was 81 mm (36.3%) smaller than that from wheeled plots, while runoff from zero tillage was reduced by 31 mm (15.7%). Traffic and tillage effects appeared to be cumulative, so the mean annual runoff from controlled traffic and zero tillage plots, representing best practice, was 112 mm (47.2%) less than that from wheeled stubble mulch plots, representing conventional cropping practice. Rainfall infiltration into controlled traffic zero tillage soil was thus 12.0% greater than into wheeled stubble mulched soil. Rainfall/runoff hydrographs show that wheeling produced a large and consistent increase in runoff, whereas tillage produced a smaller increase. Treatment effects were greater on dry soil, but were still present in large and intense rainfall events on wet soil.

Plant available water capacity (PAWC) in the 0–500 mm zone increased by 10 mm (11.5%) and mean grain yields increased by 337 kg/ha (9.4%) in controlled traffic plots, compared with wheeled plots. Mean grain yield of zero tillage was 2–8% greater than that of stubble mulch plots for all crops except for winter wheat in 1994 and 1998. Increased infiltration and plant available water were probably responsible for increased mean grain yields of 497 kg/ha (14.5%) in controlled traffic zero tillage, compared with wheeled stubble mulch treatments. Dissipation of tractive and tillage energy in the soil is the apparent mechanism of deleterious effects on the soils ability to support productive cropping in this environment. Controlled traffic and conservation tillage farming systems appear to be a practicable solution.     

Determinants of the degradation of soil structure in vineyards with a view to conversion to organic farming

In perennial crops such as grapevine, there is a considerable risk of soil degradation caused by mechanization. Organic farming may increase traffic and result in more intensive soil structure degradation, especially on wet soil. Soil structure was observed in 69 soil profiles from 12 vineyards (Languedoc‐Roussillon, Bordeaux, Provence, Burgundy, Rhône Valley) to study the relationships between permanent soil characteristics (texture, stoniness, waterlogging), cultivation practices (technical operations, traffic, farm equipment) and soil structure. Compaction zones were identified in soil profiles viewed perpendicularly to the grapevine rows. The percentage of compacted area and a score for compaction intensity were assessed in the top 0.5 m of the soil profile in three soil compartments defined by the distance from the grapevine row: (1) 0 to 0.2 m (2) 0.2 m to 0.5 m and (3) 0.5 m to the middle of the inter‐row. Most soil profiles exhibited considerable compaction: 75% of the soil profiles were compacted in compartments 2 or 3. Intensity correlated with depth of compaction in compartment 2 – the deeper the compaction, the greater the compaction intensity. Four types of soil profiles could be identified, depending on the location of compacted zones and of their intensity of compaction. The factors that determined the types of soil profiles were as follows: soil vulnerability to compaction, use of moderating practices (practices that limit the risk of compaction) and traffic geometry. A statistical analysis resulted in a decision tree that provides a useful basis to choose cultivation practices that limit damage to or improve soil structure.     

河南省城市交通公众智慧出行问题研究——以郑州市为例

以郑州市为例对当前河南省城市交通公众智慧出行系统建设需求和存在的问题进行了分析,提出政府部门应加强认识、加大投入,将智慧出行系统纳入城市交通规划中,积极建立交通信息服务系统,满足公众智慧出行。     

略论道路交通事故认定的可诉性

采用实证分析法、比较分析法、逻辑分析法和语义分析法,在总结相关规范性法律文件的规定及其变化、司法审判实践情况以及理论界有关该问题的争议的基础上,分析了交通事故责任认定的特征及其与鉴定行为的区别,得出交通事故责任认定应是公安机关行使行政管理职权的具体行政行为,应该纳入行政诉讼范围的结论。从立法、司法、理论方面全面研究该问题,意在充实相关问题的理论研究,并希望通过本文论述推动有关立法,实现行政实务和法律规定的衔接,制约公安交警部门的行政权力,促使交通事故当事人权益得到充分维护,实现真正的依法行政。     

加强农机监管确保农村道路交通安全

随着农村经济的发展,广大农民踊跃购买农业机械从事农业生产,极大地推动了农业机械的发展和农机化水平的提高,农业机械在粮、棉、油等生产和发展农村经济中发挥了巨大作用。但农业机械数量的骤增也给保证农机安全生产带来了困难,尽管各级农机部门及其监理机构做了很大的努力,农机安全事故仍时有发生,给人民群众的生命财产带来了巨大损失。笔者以近年来浙江地区发生的农机安全事故为研究对象,对事故产生的原因进行分析,并提出了降低农机事故、保障农村路面交通安全的措施。     

饱和交叉口信号配时研究

随着城市交通量的日益增加,越来越多的平面信号交叉口交通量趋于饱和。信号交叉口的配时合理与否,对交叉口运行效率有很大的影响。对于非饱和交叉口配时,可以运用Webster模型,对饱和交叉口的信号配时研究,还没有成熟的模型,本文将尝试建立一个适于饱和交叉口的指导配时的模型。     

Microscopic Traffic Simulation Mathematic Model Based on Cellular Automata

This paper presents a model for freeway traffic flow simulation and prediction. The model uses cellular automation theory to model complex traffic behavior. The advantage of the cellular automata approach is that the roadway to be modeled is quantized into simple homogeneous cells, time is quanitzed into discrete steps, and physical quantities take on a finite set of values. Also, the state of the cells is updated at each discrete timestep by using a vehicle update algorithm that combines a few vehicle motion models, governed by a relatively small set of parameters. Then vehicles just move one or several cells at each discrete timestep according to the self-defined rule. This approach makes the computer operation feasible. At last, the paper puts forward a suppose that if the simulation system is equiped with the self-study system of NN (neural network) module according to the statistical data from the transducer fixed on the freeway, it can predict the traffic status ahead of 10 minutes.