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481.
北京市铁路噪声特性实例分析研究 总被引:6,自引:0,他引:6
通过实际测量及数据分析,认为测量现场昼夜等效声级达到 777 d B( A),超过了国家标准;快速列车噪声频谱分布复杂,难以治理;列车鸣笛对铁路噪声超标贡献最大,验证了铁路噪声与列车车速的关系,最后提出控制铁路噪声的建议。 相似文献
482.
D. A. Crolla A. K. Dale 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1980,9(5):261-279
Tractor ride vibration levels have been measured when operating with and without a two wheel (2W) unbalanced and a four wheel (4W) balanced trailer. Measurements were made in the vertical, pitch, longitudinal and roll directions with the trailers unladen and laden over four typical farm surfaces
The results showed that tractor ride vibration levels were usually increased in all directions-particularly the longitudinal direction- when operating with the laden trailers. But for the unladen trailers, they were increased only in the longitudinal direction. Predominant tractor frequencies tended to be lower with the trailers attached, and coupling between the tractor longitudinal, vertical, roll and pitch co-ordinates was generally increased
Comparisons of the results with the trends predicted by a simplified theoretical model of a tractor and 2W trailer, suggested that the model should be extended to include, (a) the roll direction, (b) more realistic ground inputs, and (c) a 4W trailer 相似文献
The results showed that tractor ride vibration levels were usually increased in all directions-particularly the longitudinal direction- when operating with the laden trailers. But for the unladen trailers, they were increased only in the longitudinal direction. Predominant tractor frequencies tended to be lower with the trailers attached, and coupling between the tractor longitudinal, vertical, roll and pitch co-ordinates was generally increased
Comparisons of the results with the trends predicted by a simplified theoretical model of a tractor and 2W trailer, suggested that the model should be extended to include, (a) the roll direction, (b) more realistic ground inputs, and (c) a 4W trailer 相似文献
483.
John A. Hall Christopher P. Weaver Jayantha Obeysekera Mark Crowell Radley M. Horton Robert E. Kopp 《Coastal management》2019,47(2):127-150
Sea-level rise (SLR) is not just a future trend; it is occurring now in most coastal regions across the globe. It thus impacts not only long-range planning in coastal environments, but also emergency preparedness. Its inevitability and irreversibility on long time scales, in addition to its spatial non-uniformity, uncertain magnitude and timing, and capacity to drive non-stationarity in coastal flooding on planning and engineering timescales, create unique challenges for coastal risk-management decision processes. This review assesses past United States federal efforts to synthesize evolving SLR science in support of coastal risk management. In particular, it outlines the: (1) evolution in global SLR scenarios to those using a risk-based perspective that also considers low-probability but high-consequence outcomes, (2) regionalization of the global scenarios, and (3) use of probabilistic approaches. It also describes efforts to further contextualize regional scenarios by combining local mean sea-level changes with extreme water level projections. Finally, it offers perspectives on key issues relevant to the future uptake, interpretation, and application of sea-level change scenarios in decision-making. These perspectives have utility for efforts to craft standards and guidance for preparedness and resilience measures to reduce the risk of coastal flooding and other impacts related to SLR. 相似文献
484.
Thomas A. Hamade 《上海交通大学学报(英文版)》2018,23(1):112-121
A novel high-voltage electrostatics corona ions pre-charger apparatus and methods were invented earlier by Hamade related to treat various types of receptors such as but not limited to electret polymer, air filters, particulates, catalytic converters, bioaerosols, fluids, pollutants, virus, and bacteria. It is shown in this article that his work led to the construction of various prototype chargers, customized differently for each type of a receptor. In particular his recent development of biological matter corona charger (BMCC) prototype related to expose, treat, sanitize, and disinfect bioaerosols, virus, bacteria, and contaminated fluids and blood such as human immunodeficiency virus (HIV) - acquired immune deficiency syndrome (AIDS). It is shown in this paper that each previous investigated research contemplated ionized corona charger attendant to a charging process and the corona, imparts and provides enough treatment charges to receptors including the aforementioned receptors. Researchers often relied on adopting prior corona charger methods that do not necessarily and effectively solve the problems associated with them or utilize them for optimum treatment effect. The inventor exhaustively studied the characteristics of corona discharge, and has found that the greatest difficulty in corona discharge has to do with the maintenance of the corona, particularly when the receptor is being charged. This is due to variations in either the dielectric value between the corona electrode and a grounded base or flaws in the design as the receptor passes there between suppressing or hindering corona and its effectiveness. What is needed in-the-art is an apparatus and method to achieve maximum possible charge on a receptor, a charge order of magnitude greater than that used by other investigators. This often requires customizing each apparatus and method and does not just merely use one type of a charger to satisfy all applications. To satisfy this need, we build a low cost prototype BMCC that generates self-sustaining charge corona, eliminates many previous design flaws such as spark over, and make it ready for testing remotely or with apparatus. 相似文献
485.
K. Knothe A. Gross-Thebing 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1986,15(3):133-153
Kalker's creep coefficients for linear rolling contact problems are only valid in the steady state case. A method for the extension of linear contact mechanics into the high frequency range is presented. Frequency dependent creep coefficients are obtained, which can be interpreted as harmonic responses of the creep forces for harmonically varying creepages. For linear investigations of contact phenomena in the high frequency range simple laws governing the Kalker coefficients C11and C22 are given. 相似文献
486.
R.S. Sharp D.A. Wilson 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1990,19(6):353-363
Input correlations involving time delays are common in active vehicle suspension system problems. One approach to control law derivation fur such systems is to restrict attention to slate feedback laws in the interests of practicality and it is then of interest to determine the law which is, in some sense, the best. Under assumptions which are common in this area. relating to input, system and cost Function forms, a new derivation of the expression for the cost, accounting for time delays, is given. The use of the expression in numerical procedures for determining effective control gains is discussed and an example for a half car planar vehicle model is described. By comparing results with existing ones which are truly optimal, an estimate is made of the loss of performance which results from the restriction of the control law form in this case. Some generalisation of the results is attempted and they are placed in a contemporary context at the conclusion. 相似文献
487.
Optimal liner fleet routeing strategies 总被引:1,自引:0,他引:1
488.
针对铁路运输的货物在途中被盗现象,提出了货车、集装箱防盗系统的设计原理,给出了系统硬件结构示意图和软件设计框图并对其在 T M I S中的使用前景进行了展望。 相似文献
489.
A. Gentile A. Messina A. Trentadue 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1996,25(2):89-112
The actual trajectory covered by a mobile robot in motion differs from the trajectory planned on the basis of the kinematic characteristics of its directional control system. This difference is essentially related to the behaviour of wheel-road contact, the influence of dynamic loads and the presence of caster wheels.
This paper presents a mathematical model (“ DDPP) which simulates the motion of a generic mobile robot vehicle with a propulsion and directional control system based on two independent driving wheels and two caster wheels.
The differential equations of motion have been obtained by applying modified equations of Lagrange.
The role played by the dynamic loads, the wheel-road contact features and the caster wheels is discussed hereof. 相似文献
This paper presents a mathematical model (“ DDPP) which simulates the motion of a generic mobile robot vehicle with a propulsion and directional control system based on two independent driving wheels and two caster wheels.
The differential equations of motion have been obtained by applying modified equations of Lagrange.
The role played by the dynamic loads, the wheel-road contact features and the caster wheels is discussed hereof. 相似文献
490.
A survey of the supply side of the Automated People Mover (APM) market over the past ten to fifteen years shows some significant trends. In the nineteen eighties, suppliers concentrated on designing, developing, and marketing unique technologies. Thus, each supplier tended to specialize in a single technology, with some variations in size and capacity. With the present growth of the APM market, several APM suppliers have developed, either through mergers or acquisitions, a more diversified range of technologies to meet a variety of system requirements in terms of capacity, service and budget considerations. As a result of this trend, the transit industry now has a full range of technologies that are well proven and capable of meeting the different needs, special operational requirements, and budgets of its potential clients. 相似文献