Effect of local operational constraints on runway capacity - A case study

The estimation of runway capacity is important in airport planning and operational analysis. Standard procedures for capacity determination typically assume that there is no constraint on aircraft operations and do not provide good estimates when constraints exist. This paper presents a study of runway capacity at Singapore Changi Airport in which local operational constraints are taken into account. In addition, the impacts on capacity due to marine vessel crossings in a shipping channel near the airport, and the timing for implementation of simultaneous, independent instrument approach procedures are also investigated. The levels of annual aviation demand that could be served without excessive delays to aircraft under various operating scenarios are estimated.     

The role of subsidy policies in modernizing the structure of the bus transit industry

Full reliance on conventional forms of bus transit for peak hour needs reduces industry productivity and creates major new subsidy requirements. Restructuring of transit is needed to enable paratransit integration and other innovations than can improve efficiency. This paper discusses the industry's long-term neglect of efficiency and describes subsidy policies that would promote necessary changes.     

Talgo XXI客运豪华摆式列车

Talgo XXI是速度至220 km/h的现代化高速低地板摆式列车,其编组可按当时的客运量加以改变和调整.按用户愿望Talgo公司可为用户承担整个列车的维修,采用这种方式保证列车有很高的使用率和可靠性,考虑了用户的最大要求.     

A Method to Analyse the Dynamic Behavior of a Motorcycle Front Suspension Equipped with Sequential Dampers

This work analyses the dynamic behavior of a motorcycle front suspension equipped with passive sequential hydraulic dampers, in some operative situations. The dampers, with non-linear and asymmetric characteristics, may be regulated in six different ways. Using experimental elasticity and damping data as reference parameters, and a simplified two-degrees-of-freedom model, some dynamic simulations were carried out in order to define damping parameters for optimal comfort and safety.     

Do motor-vehicle users in the US pay their way?

Governments in the US spend over a hundred billion dollars per year to build and maintain roads and provide a variety of services for motor-vehicle users. To pay for these infrastructure and services governments collect revenue from a variety of taxes and fees. The basic objective of this paper is to compare these government expenditures with the corresponding user tax and fee payments in the US. At the outset I argue that the such comparisons tell us something about the equity but not necessarily the economic efficiency of highway financing. I then present four different ways one might tally up government expenditures and user payments, depending on the extent to which one wishes to count “indirect” expenditures (e.g., on prosecuting car thieves) and non-targeted general-tax payments (e.g., severance taxes on oil). I make a comprehensive analysis of all possible expenditures and payments, and then compare them according to three of the four ways of counting expenditures and payments. The analysis indicates that in the US current tax and fee payments to the government by motor-vehicle users fall short of government expenditures related to motor-vehicle use by approximately 20–70 cents per gallon of all motor fuel. (Note that in this accounting we include only government expenditures; we do not include any “external” costs of motor-vehicle use.) The extent to which one counts indirect government expenditures related to motor-vehicle use is a key factor in the comparison.     

Semi-Active Control of Wheel Hop in Ground Vehicles

A two degree-of-freedom vehicle model is developed which incorporates passive, active, and semi-active secondary suspensions. The model is used to demonstrate the trade-offs which are inherent in attempting to provide desirable sprung weight isolation while at the same time controlling unsprung weight motions.

A linear model is used first in order to compare passive and active suspensions in an analytically understandable configuration. The semi-active suspension is inherently nonlinear and is compared to the others through computer simulation. The passive suspension is, of course, the most restrictive in providing simultaneous isolation of sprung and unsprung weight; however, the active suspension is also compromised in providing both functions. The semi-active suspension does an excellent job of tracking its active counterpart.