High Speed Stability for Rail Vehicles Considering Varying Conicity and Creep Coefficients

The critical or hunting speed of solid axle rail vehicles is known to be a strong function of primary suspension stiffness, wheel/rail profile geometry (conicity and gravitational stiffness), wheel/rail friction forces (creep coefficients), bogie/carbody inertia properties, and secondary suspension design. This paper deals with the problem of maximizing the critical speed through design of the primary and secondary suspension but with control only over the range of wheel/rail geometry and friction characteristics. For example, the conicity may varie from .05 to .3 and the linear creep coefficients from 25% to 100% of the predicted Kalker values.

It is shown that the maximum critical speed is greatly limited by the wheel/rail geometry and friction variations. It is also shown that, when lateral curving and ride quality are considered, the best design approach is to select an intermediate primary longitudinal stiffness, to limit the lowest value of conicity (e.g. to .1 or .2) by wheel profile redesign, increasing the secondary yaw damping value (yaw relaxation) and optimizing the primary and secondary lateral stiffness.     

DISCREPANCY OF COCAINE EFFECT ON CONDUCTION AND REPOLARIZATION

ＤＩＳＣＲＥＰＡＮＣＹＯＦＣＯＣＡＩＮＥＥＦＦＥＣＴＯＮＣＯＮＤＵＣＴＩＯＮＡＮＤＲＥＰＯＬＡＲＩＺＡＴＩＯＮＬｉｕＤｏｎｇ；ＲｏｂｅｒｔＪ．Ｈａｒｉｍａｎ，ＨｅｎｒｙＳ．Ｌｏｅｂ，ＰａｔｒｉｃｋＪ．Ｓｃａｎｌｏｎ，ＪｅｒｒｙＬ．Ｂａｕｍａｎ，Ｈｉｎ...     

DYNAMIC CHANGES IN Giα2 LEVELS IN THE RAT HEART ASSOCIATED WITH IMPAIRED CARDIAC FUNCTION FOLLOWING ACUTE MYOCARDIAL INFA RCT

ＤＹＮＡＭＩＣＣＨＡＮＧＥＳＩＮＧｉα２ＬＥＶＥＬＳＩＮＴＨＥＲＡＴＨＥＡＲＴＡＳＳＯＣＩＡＴＥＤＷＩＴＨＩＭＰＡＩＲＥＤＣＡＲＤＩＡＣＦＵＮＣＴＩＯＮＦＯＬＬＯＷＩＮＧＡＣＵＴＥＭＹＯＣＡＲＤＩＡＬＩＮＦＡＲＣＴＩＯＮＳｋｉＢｉｎｇ；Ｊ．Ｅ．Ｈｅａ...     

Automated transit vehicle size considerations

Synthesis of cost-effective transit alternatives using automated vehicles requires consideration of a wide range of factors that are moot in determination of the optimum size of manually driven vehicles where the need to amortize driver wages dominates the economics. Discussions of many of these factors have appeared in previous papers. This article brings them together into consideration of one specific system characteristic: the optimum automated-transit-vehicle size.     

铌磷半钢在中磷铸铁闸瓦中应用的研究

本文通过对用铌磷半钢配制的中磷闸瓦的金相组织、力学性能、物理性能和摩擦-磨损特性的研究及其实际运行,证明:其质量指标和使用性能完全满足 TB1159-76标准,并超过普通中磷闸瓦的技术水平;可使中磷铸铁闸瓦的原材料成本降低10%左右.     

Dynamic transit scheduling under efficiency constraints

The problem of dynamic transit scheduling is addressed, and a method for transient and steady-state solutions is developed. The dynamic demand-supply formulation employed is based on previously calibrated disaggregate demand specifications. The existence and feasibility of solutions are examined, and stability conditions are derived. Numerical examples for both urban and rural conditions are given. The new methodology does not require time-series endogenous data but only initial conditions to provide long- or short-term scheduling plans. Futhermore, it takes into account passenger demand fluctuations and explicitly deals with management responsiveness and time lags in implementing scheduling decisions. Owing to its dynamic nature the methodology can be used as a design tool in transit scheduling and for assessing the effects of time-varying exogenous events such as gasoline price fluctuations, transport budget restrictions and other contingencies.     

The process of capital investment at US public portst

It is virtually impossible for a US public port authority to be totally proactive in its behaviour since there are too many major factors that affect its future that cannot be controlled or even anticipated by the port staff. Conversely, it is also virtually impossible for a public port authority to be totally reactive since the time window between decision and implementation often exceeds the time window of opportunity. For a public port authority to maintain long-term viability, it must constantly review the facilities it owns, the services it offers, and the source of the revenues it generates. This on-going review should determine how well the Port is adhering to its mission and accomplishing its goals and objectives as set out in the Port's strategic plan. Today, a major management challenge for any viable Port is prioritizing goals and maintaining a policy that ensures clear focus on the highest priority goals. Determining priorities amongst capital projects should be high on the list of any public port authority. This paper provides an overview of the decision-making processes used by American public port authorities in evaluating new capital projects and, we hope, an insight into processes for determining the desirability of expanding, contracting, or terminating present facilities and services.     

Jetfoils on the Ostend—Dover route: a technical and commercial appraisal

A high-speed jetfoil service was introduced in 1981 on the Ostend—Dover route. As a 1982-1988 review of operations shows, an average of one flight out of seven is being cancelled. Technical factors are acting in a random manner and, not surprisingly, the reliability of the service is worst in winter-time. It has been but a partial commercial success and its future is threatened by the forthcoming cross-Channel fixed link.     

An investigation into the suitability of an enclosed seaport for cruise ships the case of Leith

This paper considers port infrastructure, in terms of the physical limitations placed on vessel size, at the major cruise ship ports in northern Europe. Physical design characteristics and vessel size restrictions common to these ports are identified. The same physical design charactersitics and vessels limitations are considered in the context of a port with cruise ship ambitions, viz. Leith. The subsequent analysis suggests that infrastructure design weaknesses at a given port, in this case the presence of an entrance lock and tidal delay, may act as a deterrent to cruise ships. Primary data gathered from cruise lines and from observation of cruise ship activity at Leith supports this hypothesis. These findings have implications for both seaports and cruise lines.