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Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Complete targets coverage that leverages traditional fixed wireless sensor network has limited lifetime and high maintenance cost. In order to solve these issues, this paper proposed to completely cover targets using unmanned aerial vehicle（UAV）. The aim was to ensure that all targets were monitored by at least one UAV at all times. This paper proposed the optimal hovering problem when the UAVs monitor multiple targets through coordination and relay, and used the computational geometry to solve the optimal hovering point of different combined targets. Finally, this paper modeled the UAV complete targets coverage problem as the integer linear programming to determine the minimum number of UAV requirements. In the simulation experiment, the effects of flight speed, charging time and coverage range on the number of UAV requirements were tested by simulating three different types and parameters of rotor UAV. The results show that the number of required UAVs increases with the increasing of distance between targets and the UAV base. In addition, the number of required UAV is reduced to 1/3 when the coverage range increased from 100 m to 200 m. [ABSTRACT FROM AUTHOR]

Objectives: Voronoi diagram is a fundamental structure in geo-computing, but it still encounters the problem of exactness and the challenge of an exact algorithm comparable to planar Voronoi diagrams in the topographic space. Methods: The geodesic distance field of computational geometry is introduced into the triangulated irregular network in the discrete topographic surface. The hyperbolic curves representing the bisector are gradually grown from the singularity of the distance field on the edge of the grid. The precise division of the discrete surface is obtained by the arrangement of the hyperbolic curves, and the exact geodesic Voronoi diagram (GVD) is obtained by clustering the divided patches. Then, the exact Voronoi diagrams are tested quantitatively and qualitatively. Results and Conclusions: It is found that the exact GVD can bring a basic improvement for the spatial analysis of topographic surface. The direct algorithm based on singular growth and hyperbolic arrangement is intuitive and easy to implement, which avoids the excessive subdivision and preprocessing of grid patches by the existing algorithms, and provides a useful exploration for the development of Voronoi diagram analysis in digital topographic analysis. [ABSTRACT FROM AUTHOR]

Aiming at multi-robot online evacuation from unknown polygon, this paper proposed the problem of multirobot online evacuation from a regular hexagon based on the original evacuation model（triangle, square, circle）. 2 k（ k≥1） robots with wireless communication start from the same starting point, search for the exit on the regular hexagon boundary cooperatively and evacuate. The evacuation cost is the time it takes for all robots to be evacuated from the exit. This paper analyzed the efficiency of the algorithm using evacuation overhead. According to the number of robots and the initial position, when k=1, robots are initially at the regular hexagonal boundary or inside; when k>1, robots are initially at the regular hexagon boundary. This paper proposed respectively efficient online algorithms of multirobot evacuation for the above situations. It proves that increasing the number of robots has a positive significance in reducing the algorithm overhead when the starting point of the robots is the same. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the problem of low efficiency of direction region query in space, Voronoi diagram in computational geometry is introduced to divide the data space, and a direction region query method based on Voronoi diagram is proposed. This method is based on the index structure of Voronoi diagram generated by Delaunay triangulation. Firstly, the first node is connected with the query object to form a directed line segment, by using Voronoi diagram, the location of query object can be determined by the feature of point extension generated by adjacency. Then, by judging the location relationship between the spatial object and the query region, adding the corresponding related data points to the candidate set, and determining whether the data point is the correct result, it gets the query result set. The theoretical research and experimental results show that this method can effectively reduce the access of unnecessary data in the process of determining the location of query points. In the filtering stage, the number of candidate points is greatly reduced, thus the efficiency of direction region query of spatial data is improved. [ABSTRACT FROM AUTHOR]

Searching for a target in an unknown environment is a basic task scenario of robots. It has a wide range of applications in real life. The related problem has received much attention in the study of computational geometry and robotics. This paper considers an online problem of searching in a street by two limited sensing robots. The street is defined as a simple polygon P with LR-visibility. Two robots equipped with limited sensing sensor start from the starting point s of P, and they can communicate with each other but have no previous knowledge of P. The goal of them is to search the ending point t of P with cooperation. The limited sensing sensor can only detect the discontinuities of the boundary of P in its visibility region, but cannot infer any other geometric information, such as distances or angles. Although the sensing capability is limited, the robot can provide low-cost solutions to challenging problems while achieving greater reliability in the face of uncertainties. Based on the geometry properties of the online searching model, this paper presents a 3-competitive online coordination algorithm and proves that it is optimal by showing a matching lower bound.

Simultaneous localization and mapping (SLAM) play a vital role in implementing autonomous navigation of mobile robots in an unknown environment. Especially, visual odometry (VO) is a core component for a localization module in the SLAM system. The pose and velocity of a robot can, therefore, be estimated using computational geometry. Furthermore, the learning-based VO has gained great success in joint estimation camera ego-motion and depth from videos. In this study, a novel self-supervised VO model was proposed to realize the autonomous operation of a mobile robot in a greenhouse. The consistency constraint of temporal depth was also introduced for the learning framework using the binocular baseline supervision. Stereo video sequences were selected to train the model. The pose network after training was then used for pose estimation. A pre-test found that the stillness between video frames caused the prediction value of the model to shrink. Therefore, a soft mask was used in photometric re-projection error to remove the static region from the apparent difference measurement, and the non-rigidity scene and occlusion were further solved with normalized mask planes. Meanwhile, a new type of star dilated convolution (SDC) was also designed, where the filter was used to extract image features from the center 3×3 solid kernel and eight directions of 1-D kernel. The computational cost of SDC was thus less than that of the regular convolution of the same receptive field. Moreover, SDC was superimposed on spatial dimensions using depth-wise convolution with different dilation rates, particularly without the necessary to modify the existing deep learning framework. A convolutional auto-encoder (CAE) with residual network architecture was constructed using the SDC and inverse residual module (IRM), further serving as the backbone network for the VO model. With the aid of a binocular camera, the video sequences were collected in the solar greenhouses with tomato as the crop. The stereo video dataset was constructed to carry out the training and testing experiments. The static samples of the video sequence were removed from the image apparent difference measurement with a soft mask. The results showed that the mean relative errors (MREs) of translation and rotation estimation in the model were cut down by 5.06% and 11.05%, respectively, while the mean square root errors (RMSE) were reduced by 24.78% and 30.65%, respectively. Once a normalized mask plane was utilized in the model to deal with non-rigidity scenes and occlusion, the MREs of translation and rotation estimation were reduced by 4.15% and 3.86%, respectively. It inferred that both masks significantly improved the accuracy of the model. Meanwhile, the SDC-based IRM (SDC-IRM) reduced the MRE of rotation by 7.54% under the unchanged network parameters. Since the SDC-IRM structure presented significant effectiveness in reducing model error, the increase of perceptive field was an effective way to improve the accuracy of the model. The MRE and RMSE of rotation estimation were reduced by 2.74% and 36.48%, respectively, whereas, the mean cumulative rotation error per hundred frames (MCRE) decreased by 54.75%, when the consistency constraint of temporal depth was used in the model, indicating high accuracy and stability of pose estimation. The MRE of rotation estimation was reduced by 7.30% when extending the expansion factor of IRMs. The data demonstrated that the increase of receptive fields in the SDC kernel contributed to the higher accuracy of rotation estimation. Nevertheless, there was no longer obvious improvement of the model, when the maximum dilation rate was more than 6. More importantly, the calculation speed was up to 56.5 frames per second in the final pose estimation network. The MREs of translation and rotation estimation were 8.29% and 5.71%, respectively. The pose estimation performed better, compared with the previous VO model under similar input settings. This finding can provide sound support for the design of the navigation system for mobile robots in a greenhouse. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Frontiers of Computer Science & Technology is the property of Beijing Journal of Computer Engineering & Applications Journal Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A secure determination problem of point-sphere relationship based on different coordinate systems is a basic problem in privacy-preserving computational geometry. This paper presented a new solution for this problem, and designed a new secure determination protocol of point-sphere based on the scalar product protocol. The two sides completed the coordinate system conversion, and determined whether the sphere contained the point, but didn't disclose any information about their own. In the end, this paper analyzed it's correctness, security and efficiency, and proposed to use this protocol to resolve the similar problems that are geometric objects relations problem determination based on the different coordinate systems. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to meet design requirement of high-performance tailored airfoil for wind turbine rotor blades, a parametric representation method for wind turbine airfoil shape is presented. Firstly, based on computational geometry theory, a class of Bezier curves with shape parameter are developed. These curves is more flexible to express geometry profile because they have good features inherently possessed by the Bezier curves and the ability of shape adjustability maintaining the feature polygon. Secondly, the controllability is improved considering the characteristics of wind turbine airfoils. A novel parametric representation method for wind turbine airfoils is developed. Finally, with the comparison results of the comprehensive and detailed representation ability shown through fitting typical wind turbine airfoils, the effectiveness of the method is proved. [ABSTRACT FROM AUTHOR]

Projection twin support vector machine (PTSVM) is a recently developed pattern classification algorithm with good generalization performance. However, the training speed of PTSVM is slow because it has to solve quadratic programming (QP) problem using interior point algorithm. To overcome this drawback, this paper proposed a novel model based on computational geometry with fast training speed. First, in the spirit of PTSVM, this paper presented a novel QP model in order to generate a projection axis for a class. The corresponding dual problem is derived on the basis of optimization theory. It owned an explicit geometric interpretation and could be solved by using computational geometry algorithm. The experimental results show that the proposed method owns faster training speed and achieves better generalization performance in comparison with PTSVM. [ABSTRACT FROM AUTHOR]

Rooting in the basic principles of set theory and geometry, this paper proposed a vector-based algorithm. The algorithm firstly discerned three types of topological relations between polygons, i. e. intersectional, contained, separated. If the two polygons were separated or contained, then it could easily get the difference of them; otherwise, it obtained the difference using the parallel line scanning method. The proposed algorithm can be used for computing the differences of two arbitrary polygons, including two polygons with multiply embedded holes (polygons), which is of great useful in computer-aided design, geographic information systems and cartography. [ABSTRACT FROM AUTHOR]

For any positive integer n>1, if n= d1d1 ···dk, where di (i=l,2,···,k) is the divisor of n, then d1d2 ... dk are a F. Smarandache factor partitions of n. Using the elementary and combinational methods, the computational problem of F(1#n) for some special positive integers is studied, and an exact computational formula is given. Finally, two conjectures proposed by Amarnath Murthy and Charles Ashbacher in reference are solved. [ABSTRACT FROM AUTHOR]