公路特大型泥石流研究及防治新理念

作为我国一种严重的公路水毁类型，公路特大型泥石流灾害至今尚未解决，本文建构了该类泥石流研究及防治新理念，对于公路建筑物的安全与稳定、确保公路交通有序进行具有重要意义。研究认为，公路泥石流研究及防治的主要对象是具有大冲大淤性能、毁损作用强烈的特大型泥石流；必须遵循以泥石流发育机理研究为基础、防治技术研究为手段、防治工程研究为目的的研究原则；详细分析了公路泥石流水毁模式，概化分析了冲淤变动型沟谷泥石流的发育特性；开发了防治效果极佳的速流结构，运用运动状态函数法建构了速流结构设计理念，运用动力学建构了泥石流最大抛程计算理论。     

A practical capacity model of a single track line

The paper presents a model for determining the practical capacity of a single track line, i.e. the maximum number of trains which can be run along it in a time unit under the condition that each train enters its bottleneck segment with a definite delay.

The input data used in the model are: geometrical characteristics of the bottleneck segment of the line under study, the intensity and structure of demand expressed by a number of trains which are run over the line in a given time unit, the scenario of traffic running over the line under study and the operational tactics of individual train categories processing on the bottleneck segment.

(Two tactics can be applied in the train processing on the line under study; first, the trains of individual categories are given different priorities in the processing, and second, all the trains have the same priority).

The output results of the model are average delays of trains of each category occurring within the train processing performed on the bottleneck segment of the line under study in a given time unit.     

Cycle-simulation turbulence modelling of IC engines

Numerical simulations of IC engines are of high interest for automotive engineers worldwide. The simulation models should be as fast as possible, low-computational effort and predictive tool. The correct prediction of turbulence level inside the combustion chamber of spark ignition engines is the most important factor influencing to the engine working cycle. This paper presents a development of the k-ε turbulence model applied to the commercial cycle-simulation software with the high emphasis on the intake part. The validation was performed on two engine geometries with the variation of engine speed and load comparing the cycle-simulation results of the turbulent kinetic energy and in-cylinder temperature with 3-D CFD results. In order to apply the cycle-simulation turbulence model for the simulation of entire engine map, the parameterization model of turbulence constants was proposed. The parameterized turbulence model was optimized using NLPQL optimization algorithm where the single set of turbulence model parameters for each engine was found. A good agreement of the turbulent kinetic energy during the expansion was achieved when the turbulence affects the flame front propagation and combustion rate as well.     

出行者特征要素对公交服务模式的影响分析

公共交通是面向大众的服务,公共交通服务模式的制定与完善需要重点考虑出行者的出行需求,才能从根本上提高公共交通的竞争力。借鉴服务经济学的理论将公共交通服务模式分为公交服务标准、出行者界面、公交服务环境和技术4个维度。基于攀枝花市居民出行调查与公交专项调查数据,应用SPSS定量分析出行者特征要素与公交服务选择的相关性,以考察研究出行者对于公交服务的需求,并提出改善策略。通过研究表明,出行目的、出行时间、职业和年龄与公交服务模式的相关性较大。     

Quantitative evaluation of passenger terminal orientation

When passenger terminal layout is being decided, one of the important aspects to consider is how the passenger orients himself during his visit to the terminal and his movements through it, i.e. terminal orientation. Among other things, this terminal characteristic results from visibility, or the visual connectivity between elements and spaces. The paper proposes an amendment and modification to the known method for the quantitative evaluation of terminal orientation which uses an oriented network to describe the connectivity of elements (terminal orientation). The amendment and modification of the method consists of proposing that during evaluation only visual connections that have functional meaning should be considered, rather than all visual connections. A further modification is the introduction of different weights for different connections. The example presented in the paper considers an airport terminal building.     

Automobile aerodynamics influenced by airfoil-shaped rear wing

Computational model is developed to analyze aerodynamic loads and flow characteristics for an automobile, when the rear wing is placed above the trunk of the vehicle. The focus is on effects of the rear wing height that is investigated in four different positions. The relative wind incidence angle of the rear wing is equal in all configurations. Hence, the discrepancies in the results are only due to an influence of the rear wing position. Computations are performed by using the Reynolds-averaged Navier-Stokes equations along with the standard k-ε turbulence model and standard wall functions assuming the steady viscous fluid flow. While the lift force is positive (upforce) for the automobile without the rear wing, negative lift force (downforce) is obtained for all configurations with the rear wing in place. At the same time, the rear wing increases the automobile drag that is not favorable with respect to the automobile fuel consumption. However, this drawback is not that significant, as the rear wing considerably benefits the automobile traction and stability. An optimal automobile downforce-to-drag ratio is obtained for the rear wing placed at 39 % of the height between the upper surface of the automobile trunk and the automobile roof. Two characteristic large vortices develop in the automobile wake in configuration without the rear wing. They vanish with the rear wing placed close to the trunk, while they gradually restore with an increase in the wing mounting height.     

Experimental study on piston- and sloshing- mode moonpool resonances

An experimental study was performed on the piston- and sloshing-mode moonpool resonances of offshore structures. Two different geometries were considered to investigate the flow characteristics in a plain moonpool and a moonpool with a cofferdam. To examine the efficiency of a cofferdam for reducing the flow in a moonpool, three cofferdam geometries were tested. The plain moonpool presented violent flows as a result of the piston- and sloshing-mode resonances. However, the moonpool with the cofferdam introduced violent sloshing waves instead of the ascent and descent of the water column in the piston-mode moonpool resonance. Among three different cofferdam geometries, the model with a right triangle facing to the left on the top of the cofferdam was most effective in reducing the flow in the moonpool when compared with the other models.     

论研究与开发费用的会计处理

本文对企业研究与开发费用的现行会计处理方法,即全部费用化和部分资本化作了分析,并指出了这两种处理方法存在的缺点。提出了在知识经济时代,随着企业研究开发费用投入的不断增加,对研究开发费用的会计处理应采用全部资本化处理方法的观点。     

Light Rail Rapid Transit systems for more sustainable ground accessibility of airports

This paper investigates the potential of Light Rail Rapid Transit (LRRT) to mitigate the environmental and social burden of ground access systems of an airport. This implies, on the one hand, LRRT's capability in mitigating externalities in terms of noise, air pollution/climate change, traffic incidents/accidents and congestion of airport ground access systems and, on the other, the provision of sufficient capacity to accommodate generally increasing volumes of both air passenger and airport employee demand by connecting the airport to its core catchment area. A methodology for assessing the capability of LRRT operating as an airport ground access system is developed. This methodology consists of models to analyze and predict demand and capacity for an LRRT system and models to quantify the externalities of particular airport ground access systems as well as assessing their prospective savings thanks to the introduction of an LRRT system. The methodology is applied to a large European airport – Amsterdam Schiphol (the Netherlands) – using a ‘what-if?’ scenario approach.