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2D efficient ray tracing with a modified shortest path method

EXPLORATION GEOPHYSICS 2009年第4期40卷 301-307页

作者： Zhang, Meigen Fu, Liyun Li, Xinfu Li, Xiaofan Chinese Acad Sci Key Lab Engn Geomech Beijing 100029 Peoples R China Chinese Acad Sci Inst Geol & Geophys Key Lab Earths Deep Interior Beijing 100029 Peoples R China China Univ Geosci Beijing 100081 Peoples R China

The computation effort of ray tracing with the shortest path method (SPM) is strongly dependent on the number of the discretized nodes in a model and the number of ray directions emanating from a secondary source node. In the traditional SPM, a secondary source emanates rays to all the surrounding nodes. Obviously, most of them are not minimal traveltime raypaths. As a result, the efficiency of SPM can be greatly improved if some measures are taken to avoid those unnecessary computations. In the current study, we apply the traveltime information of neighbouring nodes and the incident rays to determine the effective target propagation directions of secondary source nodes in 2D case. Generally, the effective propagation directions are narrow bands with few surrounding nodes. Thus, most unnecessary ray directions of secondary source nodes are avoided. 2D model tests show that the computational speed of the improved method is about several to tens of times of that of the traditional SPM with the increase of network nodes and cells.

关键词： shortest path method efficient ray tracing effective propagation direction

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Automated robust crop-row detection in maize fields based on position clustering algorithm and shortest path method

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COMPUTERS AND ELECTRONICS IN AGRICULTURE 2018年 154卷 165-175页

作者： Zhang, Xiya Li, Xiaona Zhang, Baohua Zhou, Jun Tian, Guangzhao Xiong, Yingjun Gu, Baoxing Nanjing Agr Univ Coll Engn Nanjing 210031 Jiangsu Peoples R China

Crop row detection is critical for precision agriculture and automatic navigation. In this paper, a novel automatic and robust crop row detection method is proposed for maize fields based on images acquired from a vision system. As the image quality is easily affected by weed pressure and gaps in the crop rows, the proposed method was designed with the required robustness in order to deal with these undesirable conditions, and it consists of three sequentially linked phases: image segmentation, feature points extraction, and crop row detection. The image segmentation is based on the application of a modified vegetation index and double thresholding combining the Otsu method with the particle swarm optimization, thus achieving a separation between the weeds and crops. During the procedure of crop row detection, the position clustering algorithm and shortest path method were applied successively to confirm the final clustered feature point set. Finally, a linear regression method based on least squares was employed to fit the crop rows. The experimental results show that the detection accuracy of this proposed method is 0.5 degrees, which out-performs the classical approach based on the Hough transform.

关键词： Crop row detection Position clustering algorithm shortest path method Linear regression Autonomous navigation Machine vision

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A shortest path method for sequential change propagations in complex engineering design processes

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AI EDAM-ARTIFICIAL INTELLIGENCE FOR ENGINEERING DESIGN ANALYSIS AND MANUFACTURING 2016年第1期30卷 107-121页

作者： Li, Yuliang Zhao, Wei Ma, Yongsheng Zhejiang Univ State Key Lab CAD & CG 38 Zheda Rd Hangzhou 310027 Zhejiang Peoples R China Zhejiang Univ Finance & Econ Dept Foreign Language Hangzhou Zhejiang Peoples R China Univ Alberta Dept Mech Engn Edmonton AB Canada

Engineering design changes constantly occur in complex engineering design processes. Designers need appropriate measures to handle the numerous design changes in order to realize consistent and completely validated product models so that successful product development is assured. In this paper, a time-based mathematic model is presented to characterize the sequential change propagation process, and then the shortest path algorithm is given to find the most timesaving routes for changes to propagate to other dependent design tasks. An analysis method is introduced to compute the sensitivities of change impacts on the affected design tasks, which indicates that the more time consumed by a change to take its effect, the more sensitive the change impacts on those downstream dependent tasks. A case study of change propagations in motorcycle engine design process was presented to demonstrate the proposed method.

关键词： Change Propagation Design Process Sensitivity Analysis shortest path method

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Seismic source location using the shortest path method based on boundary discretisation scheme for microseismic monitoring in underground mines

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INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 2022年第0期149卷 104982-104982页

作者： Duan, Yi Luo, Xun Si, Guangyao Canbulat, Ismet CSIRO Mineral Resources POB 883 Brisbane Qld Australia Univ New South Wales Sch Minerals & Energy Resources Engn Sydney NSW Australia

In seismic monitoring at underground mines, the velocity models can be highly complex, particularly in presence of major geological structures. In practice, homogeneous velocity models have been widely used for the purposes of seismic event location in mine seismology. Although heterogeneous velocity models can be incorporated, ray tracing methods need be adopted in these velocity models to compute the travel times for accurately locating seismic events. These methods require each geological unit to be discretised to grids (corner-node or center-node discretisation scheme), which requires large computational capacity. In this research, the shortest path method (SPM) (Moser, 1991) based on a novel Boundary Discretisation Scheme (BDS) is proposed to compute the travel times for seismic event location in heterogeneous velocity models. Only the boundaries of each geological unit are discretised to nodes. The graphical network is constructed by establishing ray paths between discretised nodes on the boundaries of geological units. Dijkstra's algorithm (Dijkstra et al., 1959) using heap sorting method (Cao et al., 1993) is applied to search for the shortest ray paths with the first arrivals for seismic event location. The accuracy and efficiency of this method are validated using a 2D synthetic example. The seismic events recorded during the field monitoring of a dyke-roadway intersected area are located with the proposed BDS-SPM method. The results demonstrate that, compared with the conventional location method using homogeneous velocity models, the proposed method can provide more accurate seismic event locations for microseismic monitoring in underground mines.

关键词： Seismic source location Boundary discretisation scheme shortest path method Heterogeneous velocity model Geological structure

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The shortest path method (SPM) webserver for computational enzyme design

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PROTEIN ENGINEERING DESIGN & SELECTION 2024年第37期37卷 gzae005-gzae005页

作者： Casadevall, Guillem Casadevall, Jordi Duran, Cristina Osuna, Silvia Univ Girona Inst Quim Computac & Catalisi C-Maria Aurelia Capmany 69 Girona 17003 Spain Univ Girona Dept Quim C-Maria Aurelia Capmany 69 Girona 17003 Spain Carrer Tancat 2 Vilajuiga 17493 Spain ICREA Pg Lluis Co 23 Barcelona 08010 Spain Univ Girona Inst Quim Computac & Catalisi C-MariaAurelia Capmany 69 Girona 17003 Spain Univ Girona Dept Quim C-Maria Aurelia Capmany 69 Girona 17003 Spain

SPMweb is the online webserver of the shortest path Map (SPM) tool for identifying the key conformationally-relevant positions of a given enzyme structure and dynamics. The server is built on top of the *** code and enables the calculation and visualization of the SPM pathways. SPMweb is easy-to-use as it only requires three input files: the three-dimensional structure of the protein of interest, and the two matrices (distance and correlation) previously computed from a Molecular Dynamics simulation. We provide in this publication information on how to generate the files for SPM construction even for non-expert users and discuss the most relevant parameters that can be modified. The tool is extremely fast (it takes less than one minute per job), thus allowing the rapid identification of distal positions connected to the active site pocket of the enzyme. SPM applications expand from computational enzyme design, especially if combined with other tools to identify the preferred substitution at the identified position, but also to rationalizing allosteric regulation, and even cryptic pocket identification for drug discovery. The simple user interface and setup make the SPM tool accessible to the whole scientific community. SPMweb is freely available for academia at http://***/.

关键词： shortest path method webserver computational enzyme design distal mutations

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Research of Reconstruction Technology in Aircraft Anti-skid Braking System Based on shortest path method

Research of Reconstruction Technology in Aircraft Anti-skid ...

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CSAA/IET International Conference on Aircraft Utility Systems

作者： Zehua Liu Jing Su Zhenshui Li Cheng Qin Department of Mechanical & Electronic System AVIC The First Aircraft Institute AVIC The First Aircraft Institute Committee on Science and Technology AVIC The First Aircraft Institute

ISBN: (纸本)9781510872745

The current situation of design of braking system is that high failure rate during landing and take-off status, and switching to emergency braking system automatically once faults appearing in normal braking system, it causes the braking system to fail to maximize its effectiveness. Based on this situation, a kind of reconstruction system of anti-skid braking system has been constructed by establishing the optimization model of shortest path based on the Dijkstra algorithm. In this paper, through establishing optimization model of signal flow, and reconstructing and optimizing the system by shortest path algorithm, the safety level of the anti-skid braking system of aircraft can be improved. The simulation results show that for indicated random faults, the system can be quickly and accurately reconstructed under braking process, and the safety of braking system can be improved.

关键词： Anti-skid braking system System reconstruction Dijkstra algorithm shortest path method System simulation

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A Source Signal Recovery method for Underdetermined Blind Source Separation based on shortest path

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APPLIED COMPUTATIONAL ELECTROMAGNETICS SOCIETY JOURNAL 2020年第4期35卷 406-414页

作者： Wang, Chuanchuan Jia, Rui State Key Lab Complex Electromagnet Environm Effe Luoyang 471003 Peoples R China

A new shortest path source recovery algorithm is presented for source signal recovery issue in underdetermined blind source separation, by which the source signals can be recovered in case the observed signals are no less than two dimensions. In this algorithm, two adjacent observed signals are taken everytime among m observed signals, marked as the ith and jth signals, and form a two-dimensional observed signal combination, i = 1,2,...,m-1, j = i +1. The first and mth signals are used to form another two-dimensional observed signal combination, then m two-dimensional observed signal combinations are obtained. The number of source signals is n, the n signals can be obtained respectively after signal recovery by using each two-dimensional observed signal combination A matrix (i.e., (s) over tilde (p,q,:) = [(s) over cap (1,1,:),(s) over cap (1,2,:),...,(s) over cap (1, n,:),(s) over cap (2,1,:),...,(s) over cap (m,n,:)](T)) which is a mn-dimensional vector combination matrix can be obtained using each signal combination A mnxmn-dimensional square matrix can be gotten by calculating the vector angle between rows of (s) over tilde (p,q,:) matrix, for the first n rowsxmn columns, position the vector where the matrix elements are between 0 and theta(0). The mean is calculated for the signal vector with angle smaller than theta(0) as the estimate of the source signals. Thus, the estimates (s) over cap (1,:), (s) over cap (2,:),...,(s) over cap (n,:) of n source signals can be obtained eventually. The method presented provides a new option for solving underdetermined blind source signal recovery problem.

关键词： shortest path method Source Signal Recovery Sparsity Underdetermined Blind Source Separation

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CAD of human resource configuration in project scheduling for construction engineering applications

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COMPUTER APPLICATIONS IN ENGINEERING EDUCATION 2018年第5期26卷 1255-1269页

作者： Lin, Jeng-Wen Shen, Pu Fun Lee, Bing-Jean Feng Chia Univ Dept Civil Engn Taichung Taiwan TY Lin Taiwan Consulting Engineers Inc Taipei Taiwan

The critical path method is the primary technique for project scheduling in construction engineering. However, the development of enterprises outside Taiwan has recently encountered difficulties in personnel dispatch and human resource acquisition. The management of time schedules without the consideration of human resource configuration may cause enterprises to make unrealistic decisions. Hence, the problems of project scheduling with limited human resources have been increasingly attracting attention from construction enterprises. Based on limited human resource configuration, this study uses computer aided design tool with a linear programming method to conduct a project scheduling for the optimal model with minimized costs for construction engineering applications. We find that the programming trial balance can effectively solve the problem of limited human resource configuration and compute the lowest construction costs. Specifically, the lowest cost obtained from the programming solution is RMB 25,315,752, which is RMB 1,920,632 lower than that in the former solution without resource constraints. Further, the scheduling procedure obtained by using the shortest path method connects with the programming trial balance to resolve the problem by changing the decision variables and relevant data, whose connection is easier and more convenient than under the pure critical path method. Moreover, according to the idea of CDIO engineering education, allowing the students to participate in scientific research project and scientific and technological innovation activities of different levels and types, it improves students' learning capacity, innovation capability, cooperation capability, and engineering practical ability.

关键词： CAD cost optimization engineering education human resource constraint project scheduling shortest path method

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A Practical Large-Scale Distribution Network Planning Model Based on Elite Ant-Q

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IEEE ACCESS 2020年 8卷 58912-58922页

作者： Wang, Ziyao Lin, Dan Zeng, Guangxuan Yu, Tao South China Univ Technol Sch Elect Power Guangzhou 510640 Peoples R China South China Univ Technol Guangdong Key Lab Clean Energy Technol Guangzhou 510641 Peoples R China

In order to effectively apply the detailed geographic and load information provided by digital technology, this paper proposes a practical double-Q planning model for large-scale medium voltage distribution network. Meanwhile, a coding method and an elite Ant-Q algorithm(EAQ) suitable for solving the model in this paper are proposed. Based on the basic characteristics of the medium voltage distribution network, the components in the distribution network are abstracted into nodes and branches in the graph theory. A variety of practical issue, such as cost parameters (investments, maintenance, reliability) and technical constraints (feeder capacity constraints, number constraints of substation feeder), as well as road network constraints and connection mode constraints are taken into consideration. In addition, the storage of road network matrix information, reliability evaluation algorithm and model solving algorithm are suitable for large-scale distribution network. Finally, the proposed model and algorithm are applied to a business area to be planned in Guangzhou, which verifies the effectiveness of the proposed model and algorithm.

关键词： Large-scale distribution network planning double-Q planning EAQ sequence coding shortest path method closed loop design

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A credibility-based fuzzy programming model for the hierarchical multimodal hub location problem with time uncertainty in cargo delivery systems

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INTERNATIONAL JOURNAL OF MACHINE LEARNING AND CYBERNETICS 2021年第5期12卷 1413-1426页

作者： Shang, Xiaoting Jia, Bin Yang, Kai Yuan, Yaping Ji, Hao Beijing Jiaotong Univ Sch Traff & Transportat Beijing 100044 Peoples R China Xian Technol Univ Sch Econ & Management Xian 710021 Peoples R China Univ Massachusetts Dept Math & Stat Amherst MA 01003 USA

This paper studies the fuzzy hierarchical multimodal hub location problem for cargo delivery systems. It differs from traditional hub location problem in two ways. First, this paper constructs a hierarchical multimodal hub-and-spoke distribution network for the cargo delivery systems, which involves two transportation modes (road and air), two types of hubs (ground and airport) and three corresponding layers. Second, this paper develops a credibility-based fuzzy programming model capturing the uncertainty in travel time and handling time of the cargo delivery systems. This new model aims to minimize the latest arrival time (travel time plus handling time) for delivering cargoes from each pair of origin and destination nodes under diverse credibility of chance constraints. Under mild assumptions, the original model can be turned into an equivalent deterministic integer linear programming model. However, even for small instances of the problem, the equivalent model becomes too hard to be tackled by a general solver, e.g., CPLEX. This fact motivates the development of a two-stage heuristic procedure, wherein the first stage for the hub location subproblem is solved by a variable neighborhood search algorithm. These location solutions are then embedded into the second-stage process for the link assignment subproblem based on a shortest path method. To verify the proposed model and method, extensive numerical experiments are conducted on the well-known Turkish network data set.

关键词： Fuzzy optimization Hierarchical multimodal hub location Cargo delivery system Variable neighborhood search shortest path method

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