检索结果-南通市图书馆

Automated Sequence Selection and Cost Calculation for Maintenance and Rehabilitation in Highway Life-Cycle Cost Analysis(LCCA)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of transportation Science and Technology 2015年第1期4卷 61-75页

作者： Changmo Kim Eul-Bum Lee John T.Harvey Amy Fong Ray Lott Project Scientist University of CaliforniaDavis Associate Professor Pohang University of Science and Technology Professor University of CaliforniaDavis Senior transportation engineer California Department of Transportation transportation engineer California Department of Transportation

Life-Cycle Cost Analysis(LCCA)for highway projects is an analytical technique that uses economic principles to evaluate long-term alternative investment options,especially for comparing the values of alternative pavement design structures and construction *** approaches and software have been adopted to undertake LCCA by many transportation agencies in the United States over the last *** 2007,the California Department of transportation(Caltrans)adopted RealCost,the LCCA software,developed by the *** Highway Administration(FHWA).The California implementation incorporates major user interface enhancements and *** paper introduces the Caltrans LCCA procedure and describes the functions and improvements of the enhanced California version of RealCost software(RealCost 2.5CA).Automated functions were developed to select efficient and adequate sequences for future maintenance and rehabilitation(M&R)for comparing *** graphical user interface integrates service life,maintenance frequency,and agency cost of each maintenance activity with given project constraints,such as climate region,final pavement surface,and design *** automated cost calculation modules estimate future M&R costs based on each construction scope and pavement *** main focus of the California LCCA enhancement is to improve the efficiency of LCCA procedures with automatic data selection and *** RealCost 2.5CA program has been adopted as an official LCCA tool to comply with regulatory requirements for California state highway *** of this Californiacustomized LCCA software helps Caltrans to achieve substantial economic benefits(agency cost and road user cost savings)for highway projects.

关键词： California maintenance custom

Methods for determining unimpeded aircraft taxiing time and evaluating airport taxiing performance

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2017年第2期30卷 523-537页

作者： Yu Zhang Qing Wang Civil and Environmental engineering University of South Florida College of Air Traffic Management Civil Aviation University of China College of transportation engineer Tongji University

The objective of this study is to improve the methods of determining unimpeded（nominal） taxiing time,which is the reference time used for estimating taxiing delay,a widely accepted performance indicator of airport surface *** reviewing existing methods used widely by different air navigation service providers（ANSP）,new methods relying on computer software and statistical tools,and econometrics regression models are *** models are highly recommended because they require less detailed data and can serve the needs of general performance analysis of airport surface *** proposed econometrics model outperforms existing ones by introducing more explanatory variables,especially taking aircraft passing and over-passing into the considering of queue length calculation and including runway configuration,ground delay program,and weather *** length of the aircraft queue in the taxiway system and the interaction between queues are major contributors to long taxi-out *** proposed method provides a consistent and more accurate method of calculating taxiing delay and it can be used for ATM-related performance analysis and international comparison.

关键词： Aircraft taxiing Airport performance Econometric regression modeling Queue length Simulation analysis Taxiway system

Modeling and control of a novel electro-hydrostatic actuator with adaptive pump displacement

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第1期33卷 365-371页

作者： Yan WANG Shengrong GUO Hongkang DONG School of transportation Science and engineering Beihang UniversityBeijing 100083China Nanjing engineer Institute of Aircraft System Jincheng AVICNanjing 211100China

The variable pump displacement and variable motor speed electro-hydrostatic actuator(EHA),one of the three types of EHAs,has advantages such as short response time,flexible speed regulation,and high ***,the nonlinearity of its double-input single-output system poses a great challenge for system *** study proposes a novel EHA with adaptive pump displacement and variable motor speed(EHA-APVM).A closed-loop position is realized using a ***,the displacement varies with the system pressure;thus,the EHA-APVM is a single-input and single-output ***,the working principles of the EHA-APVM and the pump used in the system are ***,a nonlinear mathematical model of the proposed EHA-APVM control system is established,and a feedback back-stepping(FBBS)control algorithm is introduced to transform the complex nonlinear system into a linear system on the basis of the back-stepping control ***,simulation results prove that the EHA-APVM has a quick response and high robustness to variations of the load and the pump *** this work,the size and weight of the motor are significantly reduced because the maximum power requirement is reduced,which is very beneficial for using the actuator in airborne equipment.

关键词： Adaptive displacement pump Back-stepping control Electro-hydrostatic actuator Feedback linearization Robustness

Quasi-plane-hypothesis of strain coordination for RC beams seismically strengthened with externally-bonded or near-surface mounted fiber reinforced plastic

在线全文

学校读者我要写书评

暂无评论

Earthquake engineering and engineering Vibration 2013年第1期12卷 67-76页

作者： Ren Zhenhua Zeng Xiantao Liu Hanlong Zhou Fengjun School of Building engineering of Hunan Institute of engineering College of Civil and transportation engineering Hohai University The fourth engineer Scientific Research Institute of the Headquarters of the General Staff

The application of fiber reinforced plastic（FRP）,including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement（EBR） and near-surface mounted（NSM） strengthening *** paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC *** there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height（h 0） of the cross section is in direct proportion to the distance from the fiber to the neutral *** strain of the FRP and steel rebar satisfies the equation：ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.

关键词： strain coordination quasi-plane-hypothesis external-bonded near-surface mounted fiber reinforced plastic strengthening concrete beam

A Comparison of Floating Car *** Detector Estimated Freeway Travel Time Delay

在线全文

学校读者我要写书评

暂无评论

International Journal of transportation Science and Technology 2012年第2期1卷 147-169页

作者： Zhongren Wang Senior transportation engineer Division of Traffic OperationsCalifornia Department of Transportation1120 N StreetMS-36SacramentoCA 95814

Floating car-and loop detector-based methods are two different types of methods frequently used to collect travel time delay information across a freeway ***,it is necessary to use them jointly to achieve the necessary freeway network coverage,due to the high labor costs for the floating car-based method and the indispensability of sufficient network instrumentation for the loop detector-based *** example,both floating car-and loop detector-based methods were once used in the Highway Congestion Monitoring Program in the California Department of *** is therefore necessary to evaluate whether these two types of methods estimate similarly in terms of total travel time *** this end,corresponding delay information estimated using both types of methods from 37 freeway segments in the Greater Sacramento Area were collected and *** was found that these two types of methods do not estimate similarly in terms of total segment travel time *** mean absolute relative difference(MARD)can be as high as 78%,especially when delay is defined using a lower reference speed,such as 56 km/***,in terms of total segment travel time,the loop detector and the modified floating car method estimated *** MARD is 19%.It was also found that the estimation from the different methods did correlate fairly well,which provides a means of conversion when different methods are used to monitor the total delay across a freeway *** a spin-off,it was also found that a 1.5 km spacing of loop detectors is sufficient to achieve the 19%MARD as compared with the modified floating car method in terms of total travel time estimation.

关键词： Freeway Travel Time Delay Floating Car Loop Detector Comparison spacing

Placement Design of Changeable Message Signs on Curved Roadways

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of transportation Science and Technology 2015年第4期4卷 431-441页

作者： Zhongren Wang Hiep Nguyen Chiu Liu Senior transportation engineer Calitornia Department of Transportation2389 Gateway Oaks Dr.Suite 200MS-91 SacramentoCA 95833 transportation engineer California Department of Transportation 1120N StreetSacramentoCA 95833 California Department of Transpartation 1120N StreetSacramentoCA 95814

This paper presented a fundamental framework for Changeable Message Sign(CMS)placement design along roadways with horizontal *** analytical framework determines the available distance for motorists to read and react to CMS messages based on CMS character height,driver's cone of vision,CMS pixel's cone of legibility,roadway horizontal curve radius,and CMS lateral and vertical *** design charts were developed to illustrate how the analytical framework may facilitate CMS placement design.

关键词： Changeable Message Sign Placement design Cone of vision Curved roadways Analytical framework

HAPE3D—a new constructive algorithm for the 3D irregular packing problem

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic engineering 2015年第5期16卷 380-390页

作者： Xiao LIU Jia-min LIU An-xi CAO Zhuang-le YAO School of Civil and transportation engineering South China University of Technology School of Information Science and engineering Shenyang University of Technology College of Ocean Science and engineer Shanghai Maritime University

We propose a new constructive algorithm, called HAPE3 D, which is a heuristic algorithm based on the principle of minimum total potential energy for the 3D irregular packing problem, involving packing a set of irregularly shaped polyhedrons into a box-shaped container with fixed width and length but unconstrained height. The objective is to allocate all the polyhedrons in the container, and thus minimize the waste or maximize profit. HAPE3 D can deal with arbitrarily shaped polyhedrons, which can be rotated around each coordinate axis at different angles. The most outstanding merit is that HAPE3 D does not need to calculate no-fit polyhedron(NFP), which is a huge obstacle for the 3D packing problem. HAPE3 D can also be hybridized with a meta-heuristic algorithm such as simulated annealing. Two groups of computational experiments demonstrate the good performance of HAPE3 D and prove that it can be hybridized quite well with a meta-heuristic algorithm to further improve the packing quality.

关键词： 3D packing problem Layout design Simulation Optimization Constructive algorithm Meta-heuristics

Smoothed response spectra including soil-structure interaction effects

在线全文

学校读者我要写书评

暂无评论

Earthquake engineering and engineering Vibration 2020年第1期19卷 37-51页

作者： Farhad Behnamfar Amir HBabaei Mehdi Ghandil Department of Civil engineering Isfahan University of TechnologyIsfahan 841568311Iran Senior Structural engineer TehranIran Department of Civil and transportation engineering University of IsfahanIsfahan ***Iran

Elastic response spectra that take into account the effects of soil-structure interaction on soft soils are developed. The response spectra are calculated utilizing a 3 DOF system including deformations of the superstructure and foundation. The equations of motion of the system are solved using direct integration under normalized earthquake records. Statistical processing of the results is implemented resulting in response spectra for "short and dense buildings with low interaction", "short and dense buildings with high interaction", "tall and light buildings with low interaction" and "tall and light buildings with high interaction". The resulting response spectra are smoothed and discussed.

关键词： response spectrum soil-structure interaction soft soil

Cascade control based on minimum sensitivity in outer loop for processes with time delay

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2012年第9期19卷 2689-2696页

作者：尹成强惠鸿忠岳继光高洁郑丽萍 School of Automobile and transportation engineering Liaocheng University College of Electronics and Information engineer Tongji University School of Computer Science Liaocheng University

A new cascade control program was proposed based on modified internal model control to handle stable,unstable and integrating processes with time *** program had totally four controllers of which the secondary loop had two controllers and the primary loop had two *** two secondary loop controllers were designed using IMC *** were decoupled completely and could be adjusted independently,which avoided the undesirable influence on performance of the primary *** main controller in the primary loop was devised as a PID using the method of minimum sensitivity,which could guarantee not only the nominal performance but also the robust stability of the system.A setpoint filter was added in the primary loop to improve the tracking *** the controllers of the two closed-loops were designed analytically,and could be adjusted and optimized by single parameter *** were carried out on three various processes with time delay,and the results show that the proposed method can provide a better performance of both set-point tracking and disturbance rejection and robustness against parameters perturbation.

关键词： cascade control time delay H∞ performance specification modified internal mode control multiple degrees of freedom