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971.
为了从服务学的视角准确考量公交系统运行服务的质量,本文基于交通调查和系统采集数据,通过统计分析解析了公交系统运行服务的过程和出行者出行的内在特性;基于对出行策略的定义,分析了出行者出行对时间、成本与体能消耗三方面的预算对其出行决策的影响;探讨了公交运行服务质量评价的系统边界,以价值、能耗与信息为基本维度,提出了评价公交运行服务质量的三维体系架构;最后分析提出三大预算对于从公交出行生理因素和心理过程两个基础层面揭示出行行为机理,是从乘客对服务感知视角对公交运行服务质量进行评价的更为客观有效的手段. 相似文献
972.
We developed a new structural lightweight concrete by totally or partially replacing coarse and fine aggregates in high performance concrete by expanded polystyrene (EPS) beads. In this work,the sizes of EPS bead were 1.0,2.5 and 6.3 mm. Lightweight EPS concretes with a wide range of concrete densities and compressive strengths were successfully developed. Compressive strength,splitting tensile strength,shrinkage,and water absorption were examined. Additionally,fine silica fume (SF) and polypropylene (PP) f... 相似文献
973.
Mesh motion strategy is one of the key points in many fluid-structure interaction problems. One popular technique used to solve this problem is known as the spring analogy method. In this paper a new mesh update approach based on the spring analogy method is presented for the effective treatment of mesh moving boundary problems. The proposed mesh update technique is developed to avoid the generation of squashed invalid elements and maintain mesh quality by considering each element shape and grid scale to th... 相似文献
974.
Many sensor network applications require location awareness,but it is often too expensive to equip a global positioning system(GPS) receiver for each network node.Hence,localization schemes for sensor networks typically use a small number of seed nodes that know their locations and protocols whereby other nodes estimate their locations from the messages they receive.For the inherent shortcomings of general particle filter(the sequential Monte Carlo method) this paper introduces particle swarm optimization a... 相似文献
975.
冯正平 《上海交通大学学报(英文版)》2010,15(2):194-198
The design approach of H∞ autopilot for autonomous underwater vehicles (AUVs) is proposed. Comprised by the three sub-controllers,i.e. speed,heading and depth controllers,the designed autopilot has advantage over existing H∞ control of AUVs. The overshoot in speed,heading and depth control systems under step commands is restricted by refining the weighting function for robust stability. The dynamic performance of heading and depth control systems is improved by feeding back yaw rate and pitch angle,respecti... 相似文献
976.
Method for workspace calculation of 6R serial manipulator based on surface enveloping and overlaying
Aiming at the workspace calculation problem of multi-joint serial manipulators, a surface enveloping and overlaying (SEO)
method is presented to identify and visualize the manipulator workspace. The SEO method is composed of two stages: the first
stage is to choose reference points of the manipulator and calculate their boundary surfaces using the nth enveloping method; the second stage is to overlay these boundary surfaces to identify the final workspace. The SEO method
is basically a combination of the analytic method and the numerical method. By delineating the graphic representation of the
workspace step by step, the SEO method is easy to analyze the existence and the shape of voids and holes. The basic theory
of the SEO method and formulas for workspace calculation are presented based on a 6R serial manipulator. By showing the workspace
calculation results, the SEO method is proved working correctly. 相似文献
977.
To quantify mechanical effects of plantar fascia and ligaments on the arch structure, a 3D finite element model of the foot
was created to simulate the balanced standing posture. Four cases after individual releases of plantar fascia, spring ligament,
long and short plantar ligaments were simulated respectively to compare their consequences to the predictions of the intact
structure. It was founded that the foot arch didn’t collapse obviously after any individual release of these structures. As
plantar fascia was released, tensions of plantar ligaments were largely increased. Long and short plantar ligaments performed
mutual compensation functions. 相似文献
978.
A fuzzy optimization model of storage space allocation is proposed, and a rolling-planning method is derived. The model takes
the uncertainty of departure time of import containers and arrival time of export containers into account. For each planning
horizon, the problem is decomposed into two levels: the first level minimizes the unbalanced workloads among blocks using
hybrid intelligence algorithm; based on block workloads allocated in the above level, the second level minimizes the number
of blocks to which the same group of import containers are split. Numerical results show that the model reduces workload imbalance,
and speeds up the vessel loading and discharging process. 相似文献
979.
Initial conditions of impact dynamics 总被引:1,自引:0,他引:1
The effects of the initial conditions of impact dynamics equations are investigated numerically and experimentally. The inadequacies
of previous studies on initial conditions are pointed out. Then a coefficient of velocity jump at the moment of impact is
introduced, and the experiments for the mental rods are implemented to validate the appending constraints modeling methods
for impact process. The comparisons between the experimental and simulated results at different coefficients are used to study
the effects of the velocity jump conditions to the numerical simulation. The results indicate that the physical velocity response
of bodies during impact is smooth; the different values of velocity jump only have small effects on numerical oscillation
of velocity response, and they have no effects on the time history of impact force. 相似文献
980.
Dynamic investigation on composite flexible multi-body system considering thermal effect 总被引:1,自引:0,他引:1
The dynamic performance of composite flexible multi-body system under the simultaneous action of thermal fields and driving
constraint is analyzed. Based on strain-displacement relation of the Mindlin plate theory which includes transverse shear
deformation, and considering thermal effect, variation equations of laminated plate are derived by the principle of virtual
work. The finite element method is used for discretization. According to kinematics constraint relation, dynamic equations
for spatial slider-crank system are established. Simulation results show that spatial deformation (torsion deformation) appears
in the multi-layered composite slider-crank mechanism which is simulated with planar motions. Furthermore, the influence of
coupling between thermal expansion and flexible deformations of non-symmetrical composite plates on the large overall motion
under the uniform temperature field is investigated. Finally, significant change in constraint force due to the spatial deformation
is shown. 相似文献