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951.
For the restricted construction site of a Beijing metro station surrounded by many important buildings and characterized by complex staggered underground pipelines, many construction difficulties and a high level of re-quired management, settlement monitoring is necessary for the sake of construction safety. A 3D model of the metro,a model of the specially shaped structure and models of many details of the metro were established using the BIM technique, allowing for: creation of a 3D presentation, extraction of construction quantities, construction conse-quence optimization, guidance of construction endeavors, simulation of the construction process, 4D dynamic con-struction management and 4D dynamic settlement monitoring. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
952.
953.
The wide adoption of location-enabled devices, together with the acceptance of services that leverage (personal) data as payment, allows scientists to push through some of the previous barriers imposed by data insufficiency, ethics and privacy skepticism. The research problems whose study require hard-to-obtain data (e.g. transportation mode detection, service contextualisation, etc.) have now become more accessible to scientists because of the availability of data collecting outlets. One such problem is the detection of a user's transportation mode. Different fields have approached the problem of transportation mode detection with different aims: Location-Based Services (LBS) is a field that focuses on understanding the transportation mode in real-time, Transportation Science is a field that focuses on measuring the daily travel patterns of individuals or groups of individuals, and Human Geography is a field that focuses on enriching a trajectory by adding domain-specific semantics. While different fields providing solutions to the same problem could be viewed as a positive outcome, it is difficult to compare these solutions because the reported performance indicators depend on the type of approach and its aim (e.g. the real-time availability of LBS requires the performance to be computed on each classified location). The contributions of this paper are three fold. First, the paper reviews the critical aspects desired by each research field when providing solutions to the transportation mode detection problem. Second, it proposes three dimensions that separate three branches of science based on their main interest. Finally, it identifies important gaps in research and future directions, that is, proposing: widely accepted error measures meaningful for all disciplines, methods robust to new data sets and a benchmark data set for performance validation. 相似文献
954.
Mohamed B. Trabia Mohamed S. Kaseko Murali Ande 《Transportation Research Part C: Emerging Technologies》1999,7(6):353-367
This paper presents the design and evaluation of a fuzzy logic traffic signal controller for an isolated intersection. The controller is designed to be responsive to real-time traffic demands. The fuzzy controller uses vehicle loop detectors, placed upstream of the intersection on each approach, to measure approach flows and estimate queues. These data are used to decide, at regular time intervals, whether to extend or terminate the current signal phase. These decisions are made using a two-stage fuzzy logic procedure. In the first stage, observed approach traffic flows are used to estimate relative traffic intensities in the competing approaches. These traffic intensities are then used in the second stage to determine whether the current signal phase should be extended or terminated. The performance of this controller is compared to that of a traffic-actuated controller for different traffic conditions on a simulated four-approach intersection. 相似文献
955.
Interannual variation of the Polar Front in the Japan/East Sea from summertime hydrography and sea level data 总被引:1,自引:0,他引:1
The Polar Front in the Japan/East Sea separates the southern warm water region from the northern cold water region. A merged TOPEX/POSEIDON and ERS-1/2 altimeter dataset and upper water temperature data were used to determine the frontal location and to examine the structure of its interannual variability from 1993 to 2001. The identified frontal location, where sea surface height gradient has a maximum about 10–20 cm over the horizontal distance of 100 km, corresponds well to the maximum subsurface horizontal temperature gradient. The front migrates more widely (36°N–41°N) in the western part of the sea than in the eastern part. The interannual migration induces large variability in upper water temperatures and sea surface height in the western region. Responsible physical mechanisms were studied using a reduced-gravity model. Differences between inflow and outflow change the total volume of warm water, and total warm water volume change in the warm water region uniformly pushes the front in the meridional direction across its mean position in the model simulation. Interannual variation of wind stress causes relatively wide migration of the modeled front in the western part. 相似文献
956.
The problem of wave scattering by undulating bed topography in a two-layer ocean is investigated on the basis of linear theory.
In a two-layer fluid with the upper layer having a free surface, there exist two modes of waves propagating at both the free
surface of the upper layer and the interface between the two layers. Due to a wave train of a particular mode incident on
an obstacle which is bottom-standing on the lower layer, reflected and transmitted waves of both modes are created by the
obstacle. For small undulations on the bottom of the lower layer, a perturbation method is employed to obtain first-order
reflection and transmission coefficients of both modes for incident wave trains of again both modes in terms of integrals
involving the bed-shape function. For sinusoidal undulations, numerical results are presented graphically to illustrate the
energy transfer between the waves of different modes by the undulating bed.
U. BASU was born in 1949. She is a professor in the Department Applied Mathematics, Calcutta University, India. Her current research
interests include water wave problems, continuum mechanics, etc. 相似文献
957.
H. Yang B. Kim Y. Park W. Lim S. Cha 《International Journal of Automotive Technology》2009,10(3):381-390
In recent studies, various types of multi-mode electric variable transmissions for hybrid electric vehicles have been proposed.
A multi-mode electric variable transmission consists of two or more different types of a planetary gear hybrid powertrain
system (PGHP), which can change power flow type using clutches to improve transmission efficiency. Input split systems are
generally used for the single-mode powertrain because of their overall superiority, but other power split systems such as
output split and compound split systems can be used in the dual-mode powertrain. In this study, we analyze the power transmission
characteristics of output split systems, and evaluate their fuel economies in the FTP72 cycle, acceleration performance, and
constant vehicle speeds. These results enable the selection of appropriate systems for a dual-mode powertrain. 相似文献
958.
S. Kim J. M. Nouri Y. Yan C. Arcoumanis 《International Journal of Automotive Technology》2009,10(3):277-284
The spray characteristics of a 6-hole injector were examined in a single cylinder optical direct injection spark ignition
engine. The effects of injection timing, in-cylinder charge motion, fuel injection pressure, and coolant temperature were
investigated using the 2-dimensional Mie scattering technique. It was confirmed that the in-cylinder charge motion played
a major role in the fuel spray distribution during the induction stroke while injection timing had to be carefully considered
at high injection pressures during the compression stroke to prevent spray impingement on the piston. 相似文献
959.
J. Galindo H. Climent C. Guardiola J. Doménech 《International Journal of Automotive Technology》2009,10(2):141-149
Parallel sequential turbocharging systems are able to operate in different modes, which are defined according to the turbochargers
that simultaneously boost the engine, and are controlled by means of specific valves. In order to cover the full engine operating
range, a smooth transition between turbocharging operating modes must be ensured. However, important disturbances affect both
boost and exhaust pressure when shifting the operation mode, thus causing non-negligible torque oscillations. This paper presents
different methods for smoothing such undesirable effects during mode transition. Strategies covering optimal synchronization
of the control valves, control of the valves’ position, and correction of the injected fuel during the transition are analysed.
A fully instrumented passenger car engine is used for illustrating the different torque smoothing methods, and experimental
results for transitions during both steady operation and engine accelerations are shown. 相似文献
960.
B. -L. Choi D. -H. Choi J. Min K. Jeon J. Park S. Choi J. -M. Ko 《International Journal of Automotive Technology》2009,10(1):49-54
This research proposes an automatic torsion beam axle optimization process with a multidisciplinary approach and generates
the optimal torsion design parameters, such as thickness and shape. In order to construct an automatic analysis process, multidisciplinary
analysis models, such as modal analysis, roll mode dynamic analysis, and fatigue analysis, were applied in batch mode. To
understand the design space, a parametric study using the torsion beam thickness and shape was performed. Considering roll
durability and K&C characteristics, the torsion beam axle could be optimized. For the automated design process, a PIDO tool
called PIAnO was used. In conclusion, a reduction in the computer-aided simulation time was achieved, and the durability and
K&C characteristics of the torsion beam were enhanced by optimizing the thickness and shape. 相似文献