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611.
A rectangular system of roads is examined in a simple circular city where homes and workplaces are uniformly and independently distributed. Expressions for the number of vehicles crossing a given line segment are derived. 相似文献
612.
W. R. Pasterkamp H. B. Pacejka 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1997,27(5):409-422
Continuously updated knowledge of the friction potential and the friction demand can help to improve manoeuvrability and thereby safety of vehicles under slippery road conditions. An on line friction estimation method is presented using a simple brush type tyre model. First the method is verified by outdoor experiments using a tyre test trailer. Then the setup of a low-cost measurement system in a vehicle is discussed and results from both simulations and outdoor experiments are presented. Neural networks have been used both for modelling and identification of friction potential and friction demand. 相似文献
613.
Two hydrobiological transects across the East Greenland Shelf and the open waters of Fram Strait in summer were chosen to illustrate the distribution and production of phyto- and zooplankton in relation to water masses and ice cover. The parameters used were temperature and salinity, inorganic nutrients, chlorophyll a, primary production, phytoplankton species composition, abundance of the dominant herbivorous copepods Calanus finmarchicus, C. glacialis, C. hyperboreus, Metridia longa and egg production of C. finmarchicus and C. glacialis. Grazing impact of copepodites and adults of these four species was modelled for each station by using egg production rates as an index of growth. Seasonal development of plankton communities was closely associated with the extent of the ice cover, hydrographic conditions and the water masses typical of the different hydrographic domains. Four regions were identified from their biological activities and physical environment: The Northeast Water polynya on the East Greenland Shelf, with a springbloom of diatoms and active reproduction of herbivorous copepods. The pack ice region, dominated by small flagellates and negligible grazing activities. The marginal ice zone, with high variability and strong gradients of autotroph production related to eddies and ice tongues, an active microbial loop and low egg production. The open water, with high station-to-station variability of most of the parameters, probably related to hydrographic mesoscale activities. Here, Phaeocystis pouchetii was a prominent species in the phytoplankton communities. Its presence may at least partly be responsible for the generally low egg production in the open waters. Grazing impact on primary production was always small, due to low zooplankton biomass in the polynya and due to low ingestion in the remaining regions. 相似文献
614.
R. G. Rice 《先进运输杂志》1988,21(3):239-253
Expo 86, the World Exposition held last year in Vancouver, Canada, was the largest, special-category world's fair ever staged, with 54 international participants. Given the designated theme of transportation and communications, it is interesting to interpret the statements made by the participants in regard to particular sub-theme areas such as urban transit. This paper reviews the presentations (exhibits, demonstrations, conferences, and seminars) developed by all participants in Expo 86 in regard to urban transit technology, and assesses the significance and direction of technological developments in the areas of vehicle and terminal design, network and system operation and control, and planning and management systems. 相似文献
615.
Preview Estimation and Control for (Semi-) Active Suspensions 总被引:3,自引:0,他引:3
R.G.M. Huisman F.E. Veldpaus J.G.A.M. Van Heck J.J. Kok 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1993,22(5):335-346
An active suspension with preview is tested for rounded pulses and a stochastic road surface, and is compared to a passive suspension. The spectacular performance improvement obtained for a step function as road surface is not achieved but the improvement is still significant. The frequency response of the active suspension is determined for comparison with some suspension systems found in literature
An observer to reconstruct the preview information is presented. No model of the road surface is needed. From simulations, it appears that the observer reconstructs both deterministic and stochastic road surfaces satisfactory. However, the influence of measurement noise is not reduced sufficiently. 相似文献
An observer to reconstruct the preview information is presented. No model of the road surface is needed. From simulations, it appears that the observer reconstructs both deterministic and stochastic road surfaces satisfactory. However, the influence of measurement noise is not reduced sufficiently. 相似文献
616.
Impact of Liquid Load Shift on the Braking Characteristics of Partially Filled Tank Vehicles 总被引:1,自引:0,他引:1
R. Ranganathan Y. S. Yang 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1996,26(3):223-240
Braking characteristics of a tractor-tank-semitrailer vehicle is investigated by incorporating the influence of liquid load shift occurring within the partially filled tank. The tank vehicle model is developed by integrating a steady state model of a partially filled tank and a pitch plane model of the vehicle. The liquid load shift occurring in the pitch plane of the vehicle during a braking maneuver is characterized using the change in the gradient of the free surface of liquid and the corresponding shift in the center of gravity of the fluid bulk. The change in normal load on the various axles of the vehicle during the maneuver is then computed to analyze the braking behavior of the partially filled tank vehicle. The braking characteristics of the tank vehicle are then compared to those of an equivalent rigid cargo vehicle in order to study the impact of liquid load shift. Influence of various vehicle and tank design parameters on the braking behavior and wheel lock-up condition is also investigated for typical braking maneuvers. 相似文献
617.
618.
619.
Doubting that its infant shipping industry would be able to overcome, unaided, the bottleneck it was becoming for the country's export expansion policy, the government of the Republic of China has implemented in the last 25 years a set of shipping policies to address the problem. This paper examines the details of these policies, assesses the extent to which they have succeeded, and comments on the conflicts their implementation has created within the shipping and shipbuilding sectors. 相似文献
620.
A. G. Thompson B. R. Davis 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1988,17(4):179-192
In optimally controlled active suspensions with either full or incomplete state feedback there is tradeoff between system performance and overall stiffness. It is sought to remove this limitation by incorporating integral action which results in a system with infinite stiffness towards static loading, but which is soft with respect to road inputs. The system is also able to eliminate the steady state deflections due to step and (potentially) ramp type inputs at the wheel. Optimality is retained at the cost only of a derivative constraint and the system can be physically realised using output feedback control. 相似文献