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771.
Estimates of the numbers of trips likely to be made by individuals and of the modes of transport that will be available to them for those trips are provided by the trip production model. The objective of the work described in this paper was to investigate the geographical stability of the trip production model by comparing the numbers of trips estimated by the model when using national rather than local data. The 1972/3 National Travel Survey was used as the national data. Household interview survey data from the transportation studies of Lincoln, Sheffield/Rotherham, South East Dorset and Bristol were the local data sources. Three home based trip purposes are modelled; 24 hour work, 24 hour shop, 24 hour other.The models calibrated from national and local data perform similarly provided both operate with local trip rates. The car ownership sub-model with national parameters produces similar forecasts to the models with local parameters. There are probably real differences in household trip rates for some trip purposes between urban areas. 相似文献
772.
C. W. Ronosulistyo P. F. Sweatman P. N. Joubert 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1976,5(4):239-264
The significance of the effects of steering compliance and aerodynamic life on high speed automobile's steering response was investigated on two vehicles, a Ford Falcon XW (1969) station-wagon and a GM-Holden Kingswood HQ (1974) sedan. An aerofoil was mounted above the front bumper bar of the Ford Falcon to enable the simulation of vehicles with very degraded aerodynamic characteristics. Mathematical analysis showed the importance of the inclusion of steering compliance effects in determining stability factor, and hence the vehicle's high speed yaw rate sensitivity. Both experiments and theory showed that the actual high speed yaw rate response is not significantly less than that predicted from a low speed skid pad test, however, slight errors were found which are likely to be due to steering system nonlinearity and the effects of aerodynamic lift. 相似文献
773.
Building on earlier work to incorporate real option methodologies into network modeling, two models are proposed. The first is the network option design problem, which maximizes the expanded net present value of a network investment as a function of network design variables with the option to defer the committed design investment. The problem is shown to be a generalized version of the network design problem and the multi-period network design problem. A heuristic based on radial basis functions is used to solve the problem for continuous link expansion with congestion effects. The second model is a link investment deferral option set, which decomposes the network investment deferral option into individual, interacting link or project investments. This model is a project selection problem under uncertainty, where each link or project can be deferred such that the expanded net present value is maximized. The option is defined in such a way that a lower bound can be solved using an exact method based on multi-option least squares Monte Carlo simulation. Numerical tests are conducted with the classical Sioux Falls network and compared to earlier published results. 相似文献
774.
Camille N. Kamga Kyriacos C. Mouskos Robert E. Paaswell 《Transportation Research Part C: Emerging Technologies》2011,19(6):1215-1224
This paper presents results from a research case study that examined the distribution of travel time of origin–destination (OD) pairs on a transportation network under incident conditions. Using a transportation simulation dynamic traffic assignment (DTA) model, incident on a transportation network is executed under normal conditions, incident conditions without traveler information availability, and incident conditions assuming that users had perfect knowledge of the incident conditions and could select paths to avoid the incident location. The results suggest that incidents have a different impact on different OD pairs. The results confirm that an effective traveler information system has the potential to ease the impacts of incident conditions network wide. Yet it is also important to note that the use of information may detriment some OD pairs while benefiting other OD pairs. The methodology demonstrated in this paper provides insights into the usefulness of embedding a fully calibrated DTA model into the analysis tools of a traffic management and information center. 相似文献
775.
776.
目的研究制备地高辛(DIG)标记的Tex13(testis expressed gene 13)基因非放射性原位杂交探针,用于检测小鼠性腺Tex13基因的表达。方法采用RT-PCR方法扩增Tex13靶序列,将其插入带SP6和T7 RNA聚合酶启动子的pGEM-T Easy质粒,转入大肠杆菌DH10B,经蓝白斑筛选获得重组质粒,用T7和SP6引物对重组质粒进行PCR扩增,以此PCR产物为模板,以DIG RNA Labeling Mix为底物,经SP6 RNA聚合酶和T7 RNA聚合酶体外转录,分别制备DIG标记的反义链和正义链RNA探针。结果应用正常小鼠睾丸组织非放射性原位杂交实验,证实制备的探针具有较高的特异性和敏感性。结论 DIG标记Tex13基因杂交探针的成功制备,为进一步研究Tex13基因在小鼠性腺中的表达定位和发育规律以及它在减数分裂过程中的作用提供了实验基础。 相似文献
777.
The French-German research project Bahn.Ville, dealing with Rail oriented development and intermodality in German and French urban regions, has consisted in identifying the principles and factors of success of an urban development oriented towards rail, and in testing them in the agglomeration of Saint-Étienne. One of the research-actions focussed on identifying and anticipating the potential impacts in terms of urban development of a new transport system, of the tram-train type, on an existing railway line. The effect of the insertion of new stops on the global journey time is one of the criterion of the evaluation of new stops. A simulation method of the journey times is presented in this paper. The interest and the limits of this approach, regarding the rolling stock choice and the insertion of new stops, are emphasized. 相似文献
778.
Y. -G. Kim S. -W. Kim C. -K. Park T. -W. Park Y. -M. Kim 《International Journal of Automotive Technology》2011,12(1):51-58
It is necessary to guarantee the proper brake force to stop a train safely in a limited distance and o adjust its speed. Currently,
most trains are run by electrical power and have a combined electrical and mechanical (friction) braking system. The mechanical
brake force is determined by many parameters, such as the friction coefficient of the brake disc and pad, the pressure in
the brake cylinder, the brake cylinder’s cross sectional area and the brake linkage ratio. In general, the friction coefficient
data of the brake disc and pad have been taken through a dynamo-test in a laboratory, but these data might not be well matched
with real data under operating conditions because of the difference in data acquisition conditions. The present study examined
two methodologies that can measure the friction coefficient of the brake pad and disc based on a train’s real operating conditions.
The first method was the direct method, which measured the brake force and clamping force applied on the mechanical brake
by using strain gauges installed on the brake to calculate the friction coefficient. The second was an indirect method that
obtained the friction coefficient by using the weight of the train and the equivalent brake force. Those variables were calculated
from the longitudinal dynamic characteristics, such as resistance to motion, gradient resistance and curved resistance. These
two methodologies were used to obtain the disc-pad friction coefficient for the mechanical brakes of a Korean high-speed train
(HSR350x). 相似文献
779.
D. M. Chun J. C. Lee J. C. Yeo S. H. Ahn S. S. Hong J. D. Jang 《International Journal of Automotive Technology》2011,12(2):273-280
In new slim torque converters, lock-up clutches are used to provide high fuel efficiency at low speed. However, the slimness
of the converters causes difficulty in heat dissipation, which may damage the friction material and shorten its life span.
A cooling hole in the lock-up piston reduces the heat but also reduces the torque because oil flows through the hole due to
the pressure difference between the two faces of the piston. In the early stages of the development of this type of torque
converter, designers must consider the minimum flow rate required to cool the friction material and the minimum torque capacity
required to transmit the engine torque. This research explored two methods of estimating these parameters. In the first method,
an estimation equation was derived by combining the response surface method with physical properties such as the centrifugal
force, a sudden expansion, a sudden contraction, and the steady flow energy equation. The second method involved the use of
an artificial neural network. The feasibility of the estimates based on statistics and on the artificial neural network were
confirmed in the design stage by comparing experimental and estimated data. An estimation program was created using the C#.Net
language and has been used for actual torque converter designs by the Korea Powertrain Company. 相似文献
780.
M. S. Kim S. B. Yu S. Y. Lee M. C. Lee 《International Journal of Automotive Technology》2011,12(5):755-762
For developing telematics devices, traditional development methods include the unit function test, compatibility test and
T-Car, which have some limitations. Telematics devices have various functions that require accounting for the interactions
among three major elements of automotive electronics: the vehicle, the device unit and driver. The KAAS (KATECH Advanced Automotive
Simulator) system is a virtual-reality-based test environment designed to test and analyze the three elements in one place.
One of the difficult functions when constructing such VR (Virtual Reality)-based telematics test environment is to develop
a test method for the LBS (Location-Based Service) function such as a car navigation demanding the GPS (Global Positioning
System) satellite signals because KAAS is in a fixed laboratory. To overcome these problems, a real-time GPS simulation system,
which can be integrated with KAAS, is needed because the location of the vehicle in virtual space is determined purely by
the driver’s personal intention while driving virtually. This paper presents new concepts needed to construct a VR-based telematics
test environment to generate a GPS RF signal, which reflects the continuously changing vehicle location during virtual driving
in real-time. To construct this system, the coordinate transform must be conducted from a rectangular coordinate system that
is compatible with a virtual 3D DB that is used to construct a 3D image for KAAS using a WGS84 and a longitude-latitude coordinate
system compatible with a GPS simulator. Moreover, the real-time HILS (Hardware In Loop Simulation) systems and the CDMA (Code
Division Multiple Access) simulation system are developed to evaluate telematics devices. Finally, we show its applications
and results. 相似文献