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Traffic services for vehicles: the process from receiving raw probe data to space-time diagrams and theresulting traffic service

Markus AUER, Hubert REHBORN, Sven-Eric MOLZAHN, Micha KOLLER

《工程管理前沿(英文)》 2017年 第4卷 第4期   页码 490-497 doi: 10.15302/J-FEM-2017008

摘要: Today, large quantities of vehicle data (FCD: floating car data) are widely used by traffic service providers to create and broadcast traffic states in road networks. As a first processing step, all raw position data received from Global Positioning Systems (GPS) have to be map matched in a digital road map. The technical aspects of such a matching process for GPS data are described in this report. After the matching process, space-time-diagrams are created of the probe data showing traffic situation details over space and time. Various examples illustrate how traffic service quality depends on the number of matched GPS raw data; it will be stated that when 2% of connected vehicles in the total traffic flow are sending their GPS data in shorter time intervals, a high quality and precise reconstruction of the current traffic phases is achieved. Traffic reconstruction is followed by a translation into traffic information messages, which can be sent and used in vehicle navigation systems for driver information and dynamic route guidance.

关键词: floating car data     map matching     three phase traffic theory     traffic reconstruction     traffic service quality     navigation systems    

Multi-class dynamic network traffic flow propagation model with physical queues

Yanfeng LI, Jun LI

《工程管理前沿(英文)》 2017年 第4卷 第4期   页码 399-407 doi: 10.15302/J-FEM-2017041

摘要: This paper proposes an improved multi-class dynamic network traffic flow propagation model with a consideration of physical queues. Each link is divided into two areas: Free flow area and queue area. The vehicles of the same class are assumed to satisfy the first-in-first-out (FIFO) principle on the whole link, and the vehicles of the different classes also follow FIFO in the queue area but not in the free flow area. To characterize this phenomenon by numerical methods, the improved model is directly formulated in discrete time space. Numerical examples are developed to illustrate the unrealistic flows of the existing model and the performance of the improved model. This analysis can more realistically capture the traffic flow propagation, such as interactions between multi-class traffic flows, and the dynamic traffic interactions across multiple links.

关键词: first-in-first-out (FIFO)     multi-class traffic     physical queues     traffic flow modeling    

Integrating storm surge modeling with traffic data analysis to evaluate the effectiveness of hurricane

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1301-1316 doi: 10.1007/s11709-021-0765-1

摘要: An integrated storm surge modeling and traffic analysis were conducted in this study to assess the effectiveness of hurricane evacuations through a case study of Hurricane Irma. The Category 5 hurricane in 2017 caused a record evacuation with an estimated 6.8 million people relocating statewide in Florida. The Advanced Circulation (ADCIRC) model was applied to simulate storm tides during the hurricane event. Model validations indicated that simulated pressures, winds, and storm surge compared well with observations. Model simulated storm tides and winds were used to estimate the area affected by Hurricane Irma. Results showed that the storm surge and strong wind mainly affected coastal counties in south-west Florida. Only moderate storm tides (maximum about 2.5 m) and maximum wind speed about 115 mph were shown in both model simulations and Federal Emergency Management Agency (FEMA) post-hurricane assessment near the area of hurricane landfall. Storm surges did not rise to the 100-year flood elevation level. The maximum wind was much below the design wind speed of 150–170 mph (Category 5) as defined in Florida Building Code (FBC) for south Florida coastal areas. Compared with the total population of about 2.25 million in the six coastal counties affected by storm surge and Category 1–3 wind, the statewide evacuation of approximately 6.8 million people was found to be an over-evacuation due mainly to the uncertainty of hurricane path, which shifted from south-east to south-west Florida. The uncertainty of hurricane tracks made it difficult to predict the appropriate storm surge inundation zone for evacuation. Traffic data were used to analyze the evacuation traffic patterns. In south-east Florida, evacuation traffic started 4 days before the hurricane’s arrival. However, the hurricane path shifted and eventually landed in south-west Florida, which caused a high level of evacuation traffic in south-west Florida. Over-evacuation caused Evacuation Traffic Index (ETI) to increase to 200% above normal conditions in some sections of highways, which reduced the effectiveness of evacuation. Results from this study show that evacuation efficiency can be improved in the future by more accurate hurricane forecasting, better public awareness of real-time storm surge and wind as well as integrated storm surge and evacuation modeling for quick response to the uncertainty of hurricane forecasting.

关键词: storm surge modeling     traffic     evacuation     Hurricane Irma    

Isogeometric analysis based on geometric reconstruction models

《机械工程前沿(英文)》 2021年 第16卷 第4期   页码 782-797 doi: 10.1007/s11465-021-0648-0

摘要: In isogeometric analysis (IGA), the boundary representation of computer-aided design (CAD) and the tensor-product non-uniform rational B-spline structure make the analysis of three-dimensional (3D) problems with irregular geometries difficult. In this paper, an IGA method for complex models is presented by reconstructing analysis-suitable models. The CAD model is represented by boundary polygons or point cloud and is embedded into a regular background grid, and a model reconstruction method is proposed to obtain the level set function of the approximate model, which can be directly used in IGA. Three 3D examples are used to test the proposed method, and the results demonstrate that the proposed method can deal with complex engineering parts reconstructed by boundary polygons or point clouds.

关键词: isogeometric analysis     reconstruction model     level set function     trimmed element     point cloud    

Fractal characteristic evaluation and interpolation reconstruction for surface topography of drilled

《机械工程前沿(英文)》 2021年 第16卷 第4期   页码 840-854 doi: 10.1007/s11465-021-0643-5

摘要: In this paper, an improved fractal interpolation model is proposed to reconstruct the surface topography of composite hole wall. This model adopts the maximum positive deviations and maximum negative deviations between the measured values and trend values to determine the contraction factors. Hole profiles in 24 directions are measured. Fractal parameters are calculated to evaluate the measured surface profiles. The maximum and minimum fractal dimension of the hole wall are 1.36 and 1.07, whereas the maximum and minimum fractal roughness are 4.05 × 10 −5 and 4.36 × 10 −10 m, respectively. Based on the two-dimensional evaluation results, three-dimensional surface topographies in five typical angles (0°, 45°, 90°, 135°, and 165°) are reconstructed using the improved model. Fractal parameter D s and statistical parameters Sa, Sq, and Sz are used to evaluate the reconstructed surfaces. Average error of D s, Sa, Sq, and Sz between the measured surfaces and the reconstructed surfaces are 1.53%, 3.60%, 5.60%, and 9.47%, respectively. Compared with the model in published literature, the proposed model has equal reconstruction effect in relatively smooth surface and is more advanced in relatively rough surface. Comparative results prove that the proposed model for calculating contraction factors is more reasonable.

关键词: surface topography     fractal evaluation     fractal interpolation     reconstruction     composite    

Percolation-based health management of complex traffic systems

《工程管理前沿(英文)》 2021年 第8卷 第4期   页码 557-571 doi: 10.1007/s42524-021-0174-0

摘要: System health management, which aims to ensure the safe and efficient operation of systems by reducing uncertain risks and cascading failures during their lifetime, is proposed for complex transportation systems and other critical infrastructures, especially under the background of the New Infrastructure Projects launched in China. Previous studies proposed numerous approaches to evaluate or improve traffic reliability or efficiency. Nevertheless, most existing studies neglected the core failure mechanism (i.e., spatio–temporal propagation of traffic congestion). In this article, we review existing studies on traffic reliability management and propose a health management framework covering the entire traffic congestion lifetime, from emergence, evolution to dissipation, based on the study of core failure modes with percolation theory. Aiming to be “reliable, invulnerable, resilient, potential, and active”, our proposed traffic health management framework includes modeling, evaluation, diagnosis, and improvement. Our proposed framework may shed light on traffic management for megacities and urban agglomerations around the world. This new approach may offer innovative insights for systems science and engineering in future intelligent infrastructure management.

关键词: traffic health     health management     critical infrastructure     systems science and engineering    

Semantic Consistency and Correctness Verification of Digital Traffic Rules

Lei Wan,Changjun Wang,Daxin Luo,Hang Liu,Sha Ma,Weichao Hu,

《工程(英文)》 doi: 10.1016/j.eng.2023.04.016

摘要: The consensus of the automotive industry and traffic management authorities is that autonomous vehicles must follow the same traffic laws as human drivers. Using formal or digital methods, natural language traffic rules can be translated into machine language and used by autonomous vehicles. In this paper, a translation flow is designed. Beyond the translation, a deeper examination is required, because the semantics of natural languages are rich and complex, and frequently contain hidden assumptions. The issue of how to ensure that digital rules are accurate and consistent with the original intent of the traffic rules they represent is both significant and unresolved. In response, we propose a method of formal verification that combines equivalence verification with model checking. Reasonable and reassuring digital traffic rules can be obtained by utilizing the proposed traffic rule digitization flow and verification method. In addition, we offer a number of simulation applications that employ digital traffic rules to assess vehicle violations. The experimental findings indicate that our digital rules utilizing metric temporal logic (MTL) can be easily incorporated into simulation platforms and autonomous driving systems (ADS).

关键词: Autonomous driving     Traffic rules     Digitization     Formalization     Verification    

Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0731-1

摘要: Blade strain distribution and its change with time are crucial for reliability analysis and residual life evaluation in blade vibration tests. Traditional strain measurements are achieved by strain gauges (SGs) in a contact manner at discrete positions on the blades. This study proposes a method of full-field and real-time strain reconstruction of an aero-engine blade based on limited displacement responses. Limited optical measured displacement responses are utilized to reconstruct the full-field strain. The full-field strain distribution is in-time visualized. A displacement-to-strain transformation matrix is derived on the basis of the blade mode shapes in the modal coordinate. The proposed method is validated on an aero-engine blade in numerical and experimental cases. Three discrete vibrational displacement responses measured by laser triangulation sensors are used to reconstruct the full-field strain over the whole operating time. The reconstructed strain responses are compared with the results measured by SGs and numerical simulation. The high consistency between the reconstructed and measured results demonstrates the accurate strain reconstructed by the method. This paper provides a low-cost, real-time, and visualized measurement of blade full-field dynamic strain using displacement response, where the traditional SGs would fail.

关键词: aero-engine blade     displacement response     dynamic strain reconstruction     mode shape     strain gauge    

Shape reconstruction of parallelogram flaw

ZHENG Gangfeng, WU Bin, HE Cunfu

《机械工程前沿(英文)》 2008年 第3卷 第1期   页码 17-22 doi: 10.1007/s11465-008-0015-4

摘要: To reconstruct the shape of the scatterer in elastic media, the authors deduce the Born approximation solution of the two-dimensional scattering problem, which includes the shape factor that embodies all information about the shape of the scatterer. Accordingly, the change in the shape of the scatterer only necessitates the number of the corresponding new shape factors. For a parallelogram void in a long Al rod, its shape factor can be obtained. In view of the definition of a characteristic function, the shape factor has a corresponding integral representation. Obviously, the shape factor can be considered as a Fourier transform of the characteristic function, which is reconstructed from the inverse Fourier transform. The integral equation is considered as the basic equation to reconstruct the shape of the scatterer. The identification of the geometrical character of a flaw is then given by the two dimensional inverse Born approximation in a low-frequency range. For the parallelogram void, a theoretical calculating identification is performed. At the same time, the numerical results are obtained by the finite element method.

关键词: approximation     scatterer     scattering problem     information     inverse    

The ecological system and the regionalization of landscape reconstruction in northwest of China

Peicheng LI,Guoyuan DU,Qilei LI,Jinfeng WANG,Feimin ZHENG

《农业科学与工程前沿(英文)》 2014年 第1卷 第4期   页码 291-298 doi: 10.15302/J-FASE-2014033

摘要: The northwest of China is a vast area with abundant resources and significant potential for development. However, the ecological system is extremely vulnerable to damage and must be managed carefully. Thus, the Chinese government is strengthening research on improvement and reconstruction of the ecological system and landscape in northwest of China while moving forward with large-scale development in west China. The disadvantages and vulnerabilities in the northwest area in China are presented. It is suggested that the reconstruction of landscape should be conducted by step by step regionalization across the various ecological systems in the 3.04 million km northwest area of China. The first level regionalization results of reconstruction of landscape are discussed.

关键词: reconstruction of landscape     ecological system     the northwest area of China     science and technology action    

Fine-grained P2P traffic classification by simply counting flows

Jie HE,Yue-xiang YANG,Yong QIAO,Wen-ping DENG

《信息与电子工程前沿(英文)》 2015年 第16卷 第5期   页码 391-403 doi: 10.1631/FITEE.1400267

摘要: The continuous emerging of peer-to-peer (P2P) applications enriches resource sharing by networks, but it also brings about many challenges to network management. Therefore, P2P applications monitoring, in particular, P2P traffic classification, is becoming increasingly important. In this paper, we propose a novel approach for accurate P2P traffic classification at a fine-grained level. Our approach relies only on counting some special flows that are appearing frequently and steadily in the traffic generated by specific P2P applications. In contrast to existing methods, the main contribution of our approach can be summarized as the following two aspects. Firstly, it can achieve a high classification accuracy by exploiting only several generic properties of flows rather than complicated features and sophisticated techniques. Secondly, it can work well even if the classification target is running with other high bandwidth-consuming applications, outperforming most existing host-based approaches, which are incapable of dealing with this situation. We evaluated the performance of our approach on a real-world trace. Experimental results show that P2P applications can be classified with a true positive rate higher than 97.22% and a false positive rate lower than 2.78%.

关键词: Traffic classification     Peer-to-peer (P2P)     Fine-grained     Host-based    

Evaluating the short-term effect of ambient temperature on non-fatal outdoor falls and road traffic injuries

《环境科学与工程前沿(英文)》 2023年 第17卷 第9期 doi: 10.1007/s11783-023-1705-1

摘要:

● A study assessing the temperature-injury relationship was conducted among students.

关键词: Ambient temperature     Fall     Road traffic injury     Student     China    

Extrapolation reconstruction of wind pressure fields on the claddings of high-rise buildings

Yehua SUN, Guquan SONG, Hui LV

《结构与土木工程前沿(英文)》 2019年 第13卷 第3期   页码 653-666 doi: 10.1007/s11709-018-0503-5

摘要: Recent research about reconstruction methods mainly used the interpolation reconstruction of the fluctuating wind pressure field on the surface. However, to investigate wind pressure at the edge of the building, the work presented in this paper focuses on the extrapolation reconstruction of wind pressure fields. Here, we propose an improved proper orthogonal decomposition (POD) and Kriging method with a von Kármán correlation function to resolve this issue. The studies show that it works well for not only interpolation reconstruction but also extrapolation reconstruction. The proposed method does require determination of the Hurst exponent and other parameters analysed from the original data. Hence, the fluctuating wind fields have been characterized by the von Kármán correlation function, as an a priori function. Compared with the cubic spline method and different variogram, preliminary results suggest less time consumption and high efficiency in extrapolation reconstruction at the edge.

关键词: extrapolation reconstruction     proper orthogonal decomposition     Kriging method     von Kármán function     Hurst exponent     rescaled range analysis    

Special issue: Management of road and railway traffic and transportation engineering

Yongfu SUN, Ziyou GAO

《工程管理前沿(英文)》 2017年 第4卷 第4期   页码 385-387 doi: 10.15302/J-FEM-2017110

A dynamic stiffness-based framework for harmonic input estimation and response reconstruction considering

Yixian LI; Limin SUN; Wang ZHU; Wei ZHANG

《结构与土木工程前沿(英文)》 2022年 第16卷 第4期   页码 448-460 doi: 10.1007/s11709-022-0805-5

摘要: In structural health monitoring (SHM), the measurement is point-wise but structures are continuous. Thus, input estimation has become a hot research subject with which the full-field structural response can be calculated with a finite element model (FEM). This paper proposes a framework based on the dynamic stiffness theory, to estimate harmonic input, reconstruct responses, and to localize damages from seriously deficient measurements. To begin, Fourier transform converts the dynamic equilibrium equation to an equivalent static one in the frequency domain, which is under-determined since the dimension of measurement vector is far less than the FEM-node number. The principal component analysis has been adopted to “compress” the under-determined equation, and formed an over-determined equation to estimate the unknown input. Then, inverse Fourier transform converts the estimated input in the frequency domain to the time domain. Applying this to the FEM can reconstruct the target responses. If a structure is damaged, the estimated nodal force can localize the damage. To improve the damage-detection accuracy, a multi-measurement-based indicator has been proposed. Numerical simulations have validated that the proposed framework can capably estimate input and reconstruct multi-types of full-field responses, and the damage indicator can localize minor damages even with the existence of noise.

关键词: dynamic stiffness     principal component analysis     response reconstruction     damage localization     under-determined equation    

标题 作者 时间 类型 操作

Traffic services for vehicles: the process from receiving raw probe data to space-time diagrams and theresulting traffic service

Markus AUER, Hubert REHBORN, Sven-Eric MOLZAHN, Micha KOLLER

期刊论文

Multi-class dynamic network traffic flow propagation model with physical queues

Yanfeng LI, Jun LI

期刊论文

Integrating storm surge modeling with traffic data analysis to evaluate the effectiveness of hurricane

期刊论文

Isogeometric analysis based on geometric reconstruction models

期刊论文

Fractal characteristic evaluation and interpolation reconstruction for surface topography of drilled

期刊论文

Percolation-based health management of complex traffic systems

期刊论文

Semantic Consistency and Correctness Verification of Digital Traffic Rules

Lei Wan,Changjun Wang,Daxin Luo,Hang Liu,Sha Ma,Weichao Hu,

期刊论文

Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

期刊论文

Shape reconstruction of parallelogram flaw

ZHENG Gangfeng, WU Bin, HE Cunfu

期刊论文

The ecological system and the regionalization of landscape reconstruction in northwest of China

Peicheng LI,Guoyuan DU,Qilei LI,Jinfeng WANG,Feimin ZHENG

期刊论文

Fine-grained P2P traffic classification by simply counting flows

Jie HE,Yue-xiang YANG,Yong QIAO,Wen-ping DENG

期刊论文

Evaluating the short-term effect of ambient temperature on non-fatal outdoor falls and road traffic injuries

期刊论文

Extrapolation reconstruction of wind pressure fields on the claddings of high-rise buildings

Yehua SUN, Guquan SONG, Hui LV

期刊论文

Special issue: Management of road and railway traffic and transportation engineering

Yongfu SUN, Ziyou GAO

期刊论文

A dynamic stiffness-based framework for harmonic input estimation and response reconstruction considering

Yixian LI; Limin SUN; Wang ZHU; Wei ZHANG

期刊论文