scholarly journals A Random Sampling O(n) Force-calculation Algorithm for Graph Layouts

2019 ◽  
Author(s):  
Robert Gove
Keyword(s):  
Random Sample ◽  
Linear Time ◽  
Fast Multipole Method ◽  
Repulsive Force ◽  
Calculation Algorithm ◽  
Calculation Algorithms ◽  
Graph Layouts ◽  
Repulsive Forces ◽  
Space Requirements ◽  
Force Calculation

This paper proposes a linear-time repulsive-force-calculation algorithm with sub-linear auxiliary space requirements, achieving an asymptotic improvement over the Barnes-Hut and Fast Multipole Method force-calculation algorithms. The algorithm, named random vertex sampling (RVS), achieves its speed by updating a random sample of vertices at each iteration, each with a random sample of repulsive forces. This paper also proposes a combination algorithm that uses RVS to derive an initial layout and then applies Barnes-Hut to refine the layout. An evaluation of RVS and the combination algorithm compares their speed and quality on 109 graphs against a Barnes-Hut layout algorithm. The RVS algorithm performs up to 6.1 times faster on the tested graphs while maintaining comparable layout quality. The combination algorithm also performs faster than Barnes-Hut, but produces layouts that are more symmetric than using RVS alone. Data and code: https://osf.io/nb7m8/

DETERMINATION OF THE REPULSIVE FORCE OF A THICK HIGH-COERCIVE PERMANENT MAGNETS IN THE AXIAL BEARING OF A VERTICAL PUMP

2021 ◽  
pp. 23-27
Author(s):  
A. Ya. Krasil’nikov ◽  
A. A. Krasil’nikov
Keyword(s):  
Standard Method ◽  
Permanent Magnets ◽  
Magnetic System ◽  
Repulsive Force ◽  
Cobalt Alloy ◽  
Average Value ◽  
The North ◽  
Repulsive Forces ◽  
North And South

The article considers the possibility of applying a standard method for calculating the repulsive force for a thick high-coercive permanent magnets from samarium-cobalt alloy in a magnetic system. The results of the research allowed us to introduce correction coefficients in the method of calculating the repulsive force in a magnetic system with such magnets, depending on the air gap between of them. It is shown that the repulsive forces of the North poles of permanent magnets differ from the repulsive forces of the South poles. The research was carried out with magnets manufactured by different enterprises. When calculating the repulsive force, the average value of the repulsive force between the North and South poles of magnets is found.

scholarly journals Simulator Demonstrations of Different Retrofit Options of a Self-propelled Inland Vessel

2017 ◽  
Vol 47 (2) ◽  
pp. 111-117 ◽  
Author(s):  
Csaba Hargitai ◽  
Juha Schweighofer ◽  
Győző Simongáti
Keyword(s):  
European Union ◽  
Framework Programme ◽  
The European Union ◽  
Single Screw ◽  
Seventh Framework Programme ◽  
Custom Made ◽  
Inland Waterway ◽  
Calculation Algorithms ◽  
Force Calculation ◽  
Naval Architect

The project MoVe IT! (www.moveit-fp7.eu), funded by the Seventh Framework Programme of the European Union, was focussed on modernisation of inland waterway vessels by retrofitting. In order to stimulate an implementation of the results by the industry, visualization of the positive impacts was realised by a set of vivid demonstrators. In this paper, the demonstrations by simulators for a single screw motor cargo vessel of the type Johann Welker are described.The motion simulations are carried out by a custom made (for inland vessels developed) computer program, which use common naval architect force calculation algorithms and a new approximation theory for added masses.The simulator demonstrations comprise descriptions and visualisations of ship lengthening, application of different rudder and a new propulsion device. Five different cases are examined, the original vessel and four retrofit options.First retrofit variant is the lengthened vessel with original rudder and propeller. Other two analysis are performed changing only the rudder system. In fourth simulator demonstration the original propeller is changed to a pump propeller (a novel propulsion device).The environment are in the simulator demonstrations: constant draught of the vessel, and calm, infinite deep waterway.As results of simulator demonstrations the effects on fuel consumption and manoeuvrability are discussed in the paper.

Analytical Convolution Model of Cutting Forces in 3-D Ball End Milling

2001 ◽  
Author(s):  
Richard Y. Chiou ◽  
Bing Zhao
Keyword(s):  
Cutting Force ◽  
Frequency Domain ◽  
Cutting Forces ◽  
End Milling ◽  
Force Model ◽  
Three Dimensional Model ◽  
Calculation Algorithm ◽  
Ball End Milling ◽  
Convolution Model ◽  
Force Calculation

Abstract This paper presents an analytical convolution model of dynamic cutting forces in ball end milling of 3-D plane surfaces. The model takes into account the instantaneous slope on a sculptured surface to establish the chip geometry in cutting force calculation algorithm. A three-dimensional model of cutting forces in ball end milling is presented in terms of material properties, cutting parameters, machining configuration, and tool/work geometry. Based on the relationship of the local cutting force, chip load and engaged boundary, the total cutting force model is established via the angle domain convolution integration of the local forces in the feed, cross feed, axial direction, and inclination angle. The convolution integral leads to a periodic function of cutting forces in the angle domain and an explicit expression of the dynamic cutting force components in the frequency domain. Following the theoretical analysis, experimental study is discussed to illustrate the implementation procedure for force identification, and frequency domain data are presented to verify the analytical results.

A cross-modal tactile sensor design for measuring robotic grasping forces

2019 ◽  
Vol 46 (3) ◽  
pp. 337-344 ◽  
Author(s):  
Bin Fang ◽  
Hongxiang Xue ◽  
Fuchun Sun ◽  
Yiyong Yang ◽  
Renxiang Zhu
Keyword(s):  
Visual Information ◽  
Tactile Sensor ◽  
Circuit Board ◽  
Three Dimension ◽  
Robotic Grasping ◽  
Calculation Algorithm ◽  
Content Type ◽  
Grasping Forces ◽  
And Performance ◽  
Force Calculation

PurposeThe purpose of the paper is to present a novel cross-modal sensor whose tactile is computed by the visual information. The proposed sensor can measure the forces of robotic grasping.Design/methodology/approachThe proposed cross-modal tactile sensor consists of a transparent elastomer with markers, a camera, an LED circuit board and supporting structures. The model and performance of the elastomer are analyzed. Then marker recognition method is proposed to determine the movements of the marker on the surface, and the force calculation algorithm is presented to compute the three-dimension force.FindingsExperimental results demonstrate that the proposed tactile sensor can accurately measure robotic grasping forces.Originality/valueThe proposed cross-modal tactile sensor determines the robotic grasping forces by the images of markers. It can give more information of the force than traditional tactile sensors. Meanwhile, the proposed algorithms for forces calculation determine the superior results.

A hierarchical O(N log N) force-calculation algorithm

Nature ◽  
1986 ◽  
Vol 324 (6096) ◽  
pp. 446-449 ◽  
Author(s):  
Josh Barnes ◽  
Piet Hut
Keyword(s):  
Calculation Algorithm ◽  
Force Calculation

scholarly journals Comparison of treatment plans calculated by Ray Tracing and Monte Carlo algorithms for head and thorax radiotherapy with Cyberknife

2017 ◽  
Vol 3 (2) ◽  
pp. 647-650 ◽  
Author(s):  
Kirsten Galonske ◽  
Martin Thiele ◽  
Iris Ernst ◽  
Ralph Lehrke ◽  
Waldemar Zylka
Keyword(s):  
Monte Carlo ◽  
Ray Tracing ◽  
Stereotactic Radiotherapy ◽  
Calculation Algorithm ◽  
Monte Carlo Algorithms ◽  
Body Regions ◽  
Calculation Algorithms ◽  
Treatment Plans ◽  
Homogeneous Regions ◽  
Tumor Types

AbstractThis study investigates differences between treatment plans generated by Ray Tracing (RT) and Monte Carlo (MC) calculation algorithms in homogeneous and heterogeneous body regions. Particularly, we focus on the head and on the thorax, respectively, for robotic stereotactic radiotherapy and radiosurgery with Cyberknife. Radiation plans for tumors located in the head and in the thorax region have been calculated and compared to each other in 47 cases and several tumor types.Assuming MC as the algorithm of highest accuracy it is shown that based on selected dose parameters, RT slightly underestimates the dose in homogeneous regions and overestimates in heterogeneous regions. In addition, deviations occur due to tumor size rendering large differences for small tumors. We conclude that dose prescriptions for radiotherapy treatments should differentiate between RT and MC calculation algorithm. This is especially important for small tumors in heterogeneous body regions.

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