Wave generation of a compartmented surface-effect ship

A series of carefully controlled experiments on the wave-generation characteristics of a model of a compartmented surface-effect ship has been conducted in a towing tank. Configurations of the model included cases encompassing one subcushion and two subcushions, as well as differing values of the pressures in the subcushions. It was shown that a reduced wave generation in the appropriate Froude number range could be achieved in this manner. Furthermore, a previously developed theory for the wave generation of marine vessels was verified for the model for a Froude number greater than 0.40.     

The evaluation of large cycling infrastructure investments in Glasgow using crowdsourced cycle data

Transportation - The benefits of cycling have been well established for several decades. It can improve public health and make cities more active and environmentally friendly. Due to the...     

A system for determining economic loss associated with estuary degradation

Abstract

This article suggests a method of estimating economic losses for estuary‐dependent faunal species under conditions whereby the impact of a given degrading development on a particular estuary has a significant degree of uncertainty associated with it. The approach draws on standard theories from a variety of disciplines to provide an operational procedure capable of joint application by biologists, economists, and other related disciplines with working responsibility in the subject area. Consideration is given to probability estimation of possible impacts, sensitivity to underlying assumptions, and decisional safety under conditions of uncertainty. Applied results are demonstrated in a simulation of a negative developmental impact on the estuary‐dependent salmon resources of the Fraser River in British Columbia.     

A co-integration approach to forecasting freight rates in the dry bulk shipping sector

In this paper, a vector autoregressive model is developed for a sample of ocean dry bulk freight rates. Although the series of freight rates are themselves found to be non-stationary, thus precluding the use of many modelling methodologies, evidence provided by cointegration tests points to the existence of stable long-term relationships between the series. An assessment of the forecasts derived from the model suggests that the specification of these long-term relationships does not improve the accuracy of short- or long-term forecasts. These results are interpreted as a corroboration of the efficient market hypothesis.     

Nitroglycerin reduces augmentation index and central blood pressure independent of effects on cardiac preload

Objective To determine whether reduction In central pressure augmentation and central systolic blood pressure by nitroglycerine (NTG) results from effects on pre-lead or is due to arterial dilation. Methods We compared effects of NTG with these of lower body negative pressure (LBNP). Hemodyunmic measurements were made at rest, during LBNP (10, 20 and 30 mmHg, each for 15 min) and after NTG (10, 30 and 100μg/min, each dose for 15 min) in ten healthy volunteers. Cardiac pre-lead, stroke volume and cardiac output were assessed by echacardiography. Central pressure an mnentation and central systolic pressure were obtained by radial tonometry using a transfer function. Results LBNP (20 mmHg) and NTG (30μg/min) reduced pre-lead (as measured by the peak velocity of the S wave in the superior vena eava) to a similar degree [by (26. 8 ± 3.8) % and (23.9 ± 3. 4) %, respectively]. Compared to LBNP, NTG reduced systemic vascular resistance [by (32. 9 ± 7.5) %, p< 0. 01], decreased peripheral and central pressure augmentation [by (20. 8 ± 3. 4)% units and (12. 9±2. 9)% units, respectively, each P< 0. 01]. Conclusion These results suggest that a reduction in pre-load does not explain reduction in pressure augmentation and central systolic blood pressure by NTG and that these effects are mediated through arterial dilation.     

Consumers as participants in transportation planning

Legal requirements for public participation in transportation planning increase the opportunity for transportation consumers to influence the design of systems they will use. However, the implementation of these requirements may also increase the possibility that system design will be dominated by the opinions of outspoken groups. This study postulates that public participation is biased, and seeks to test this proposition using data from an Oregon survey consisting of approximately 2,400 respondents. Using Automatic Interaction Detector and cross tabulation analyses, different participation rates were uncovered for groups identified by demographic, attitudinal and behavioral variables.The authors thank the Oregon Department of Transportation for making the original data for the study available.