scholarly journals Cell Area-Based Method for Analyzing the Coverage Capacity of Satellite Constellations

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhiming Song ◽  
Haidong Liu ◽  
Guangming Dai ◽  
Maocai Wang ◽  
Xiaoyu Chen
Keyword(s):  
High Efficiency ◽  
Cell Area ◽  
Satellite Constellations ◽  
Coverage Area ◽  
Computation Efficiency ◽  
Coverage Analysis ◽  
Satellite Applications ◽  
A Cell ◽  
Ground Coverage ◽  
Coverage Problems

Constellation-to-ground coverage analysis is an important problem in practical satellite applications. The classical net point method is one of the most commonly used algorithms in resolving this problem, indicating that the computation efficiency significantly depends on the high-precision requirement. On this basis, an improved cell area-based method is proposed in this paper, in which a cell is used as the basic analytical unit. By calculating the accuracy area of a cell that is partly contained by the ground region or partly covered by the constellation, the accurate coverage area can be obtained accordingly. Experiments simulating different types of coverage problems are conducted, and the results reveal the correctness and high efficiency of the proposed analytical method.

scholarly journals DATA-DRIVEN REAL-TIME ANALYSIS SERVICE FOR SATELLITE AREA COVERAGE

2020 ◽  
Vol XLII-3/W10 ◽  
pp. 769-774
Author(s):  
W. J. Lu ◽  
Q. Xu ◽  
C. Z. Lan ◽  
S. Q. Shi ◽  
L. Lyu ◽  
...  
Keyword(s):  
Real Time ◽  
Area Coverage ◽  
Data Driven ◽  
Analysis Model ◽  
Time Analysis ◽  
Online Services ◽  
Coverage Area ◽  
Real Time Analysis ◽  
Coverage Analysis ◽  
Ground Coverage

Abstract. Satellite area coverage analysis is complex, especially when the satellite operating state changes. Traditional algorithms cannot quickly and efficiently obtain the satellite area coverage analysis results, and are incapable of providing efficient online services. To overcome these shortcomings and meet the needs of 21st century geospatial science and applications for real-time response and online services for handling high concurrent requests, a data-driven real-time analysis service for satellite area coverage is proposed. Firstly, to optimize traditional algorithms, an extended bounding rectangle of the ground area is constructed, and the spatial relationship with the central point of satellite ground coverage area is determined to avoid large number of calculations of satellite ground coverage areas, thus, improving efficiency. Secondly, the data-driven real-time analysis model is constructed, and is used to further improve the efficiency of satellite area coverage analysis. Finally, a simulation analysis scenario is developed, the service proposed in this study is verified, and the results are visualized. The experimental results show that the proposed data-driven real-time analysis service can cope well with the requests from users for online service of satellite area coverage, improve the cognitive capability of users and operators, and help in completely utilizing the application performance of observation satellites.

scholarly journals Judgement Theorems and an Approach for Solving the Constellation-to-Ground Coverage Problem

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Zhiming Song ◽  
Xiangyun Hu ◽  
Maocai Wang ◽  
Guangming Dai
Keyword(s):  
The State ◽  
Coverage Problem ◽  
Satellite Constellation ◽  
Novel Approach ◽  
Satellite Applications ◽  
Ground Coverage ◽  
Multiple Coverage ◽  
Coverage Problems

The satellite constellation-to-ground coverage problem is a basic and important problem in satellite applications. A group of judgement theorems is given, and a novel approach based on these judgement theorems for judging whether a constellation can offer complete single or multiple coverage of a ground region is proposed. From the point view of mathematics, the constellation-to-ground coverage problem can be regarded as a problem entailing the intersection of spherical regions. Four judgement theorems that can translate the coverage problem into a judgement about the state of a group of ground points are proposed, thus allowing the problem to be efficiently solved. Single- and multiple-coverage problems are simulated, and the results show that this approach is correct and effective.

scholarly journals Authentic Replication and Recombination of Tomato Bushy Stunt Virus RNA in a Cell-Free Extract from Yeast

2008 ◽  
Vol 82 (12) ◽  
pp. 5967-5980 ◽  
Author(s):  
Judit Pogany ◽  
Peter D. Nagy
Keyword(s):  
High Efficiency ◽  
Tomato Bushy Stunt Virus ◽  
Free System ◽  
Cell Free System ◽  
Virus Rna ◽  
A Cell ◽  
Viral Replicase ◽  
Template Specificity ◽  
Rna Complex

ABSTRACT To study the replication of Tomato bushy stunt virus (TBSV), a small tombusvirus of plants, we have developed a cell-free system based on a Saccharomyces cerevisiae extract. The cell-free system was capable of performing a complete replication cycle on added plus-stranded TBSV replicon RNA (repRNA) that led to the production of ∼30-fold-more plus-stranded progeny RNAs than the minus-stranded replication intermediate. The cell-free system also replicated the full-length TBSV genomic RNA, which resulted in production of subgenomic RNAs as well. The cell-free system showed high template specificity, since a mutated repRNA, minus-stranded repRNA, or a heterologous viral RNA could not be used as templates by the tombusvirus replicase. Similar to the in vivo situation, replication of the TBSV replicon RNA took place in a membraneous fraction, in which the viral replicase-RNA complex was RNase and protease resistant but sensitive to detergents. In addition to faithfully replicating the TBSV replicon RNA, the cell-free system was also capable of generating TBSV RNA recombinants with high efficiency. Altogether, tombusvirus replicase in the cell-free system showed features remarkably similar to those of the in vivo replicase, including carrying out a complete cycle of replication, high template specificity, and the ability to recombine efficiently.

scholarly journals Integrating UAV and TLS Approaches for Environmental Management: A Case Study of a Waste Stockpile Area

2020 ◽  
Vol 12 (10) ◽  
pp. 1615 ◽  
Author(s):  
Seung Woo Son ◽  
Dong Woo Kim ◽  
Woong Gi Sung ◽  
Jae Jin Yu
Keyword(s):  
Environmental Management ◽  
Point Cloud ◽  
Laser Scanning ◽  
High Efficiency ◽  
Point Clouds ◽  
Fusion Model ◽  
Spatial Features ◽  
Computation Efficiency ◽  
Volume Computation ◽  
Mean Square Errors

A methodology for optimal volume computation for the environmental management of waste stockpiles was derived by integrating the terrestrial laser scanning (TLS) and unmanned aerial vehicle (UAV) technologies. Among the UAV-based point clouds generated under various flight scenarios, the most accurate point cloud was selected for analysis. The root mean square errors (RMSEs) of the TLS- and UAV-based methods were 0.202 and 0.032 m, respectively, and the volume computation yielded 41,226 and 41,526 m3, respectively. Both techniques showed high accuracy but also exhibited drawbacks in terms of their spatial features and efficiency. The TLS and UAV methods required 800 and 340 min, respectively, demonstrating the high efficiency of the UAV method. The RMSE and volume obtained using the TLS/UAV fusion model were calculated as 0.030 m and 41,232 m3, respectively. The UAV approach generally yielded high point cloud accuracy and volume computation efficiency.

scholarly journals Target-oriented Gaussian beam migration using a modified ray tracing scheme

2019 ◽  
Vol 16 (6) ◽  
pp. 1301-1319 ◽  
Author(s):  
Rui Zhang ◽  
Jian-Ping Huang ◽  
Su-Bin Zhuang ◽  
Zhen-Chun Li
Keyword(s):  
Gaussian Beam ◽  
Ray Tracing ◽  
Large Scale ◽  
High Efficiency ◽  
Complex Structure ◽  
Back Propagation ◽  
Imaging Method ◽  
Computation Efficiency ◽  
Simple Implementation ◽  
Gaussian Beam Migration

Abstract For large-scale 3D seismic data, target-oriented reservoir imaging is more attractive than conventional full-volume migration, in terms of computation efficiency. Gaussian beam migration (GBM) is one of the most robust depth imaging method, which not only keeps the advantages of ray methods, such as high efficiency and flexibility, but also allows us to solve caustics and multipathing problems. But conventional Gaussian beam migration requires slant stack for prestack data, and ray tracing from beam center location to subsurface, which is not easy to be directly applied for target-oriented imaging. In this paper, we modify the conventional Gaussian beam migration scheme, by shooting rays from subsurface image points to receivers to implement wavefield back-propagation. This modification helps us to achieve a better subsurface illumination in complex structure and allows simple implementation for target reservoir imaging. Significantly, compared with the wavefield-based GBM, our method does not reconstruct the subsurface snapshots, which has higher efficiency. But the proposed method is not as efficient as the conventional Gaussian beam migration. Synthetic and field data examples demonstrate the validity and the target-oriented imaging capability of our method.

scholarly journals Performance Evaluation of a Dual Coverage System for Internet of Things Environments

2016 ◽  
Vol 2016 ◽  
pp. 1-20 ◽  
Author(s):  
Omar Said ◽  
Amr Tolba
Keyword(s):  
Internet Of Things ◽  
Packet Loss ◽  
The Internet ◽  
Network Coverage ◽  
Coverage Area ◽  
End To End Delay ◽  
High Altitude Platforms ◽  
Multiple Levels ◽  
Coverage Problems ◽  
Simulation Package

A dual coverage system for Internet of Things (IoT) environments is introduced. This system is used to connect IoT nodes regardless of their locations. The proposed system has three different architectures, which are based on satellites and High Altitude Platforms (HAPs). In case of Internet coverage problems, the Internet coverage will be replaced with the Satellite/HAP network coverage under specific restrictions such as loss and delay. According to IoT requirements, the proposed architectures should include multiple levels of satellites or HAPs, or a combination of both, to cover the global Internet things. It was shown that the Satellite/HAP/HAP/Things architecture provides the largest coverage area. A network simulation package, NS2, was used to test the performance of the proposed multilevel architectures. The results indicated that the HAP/HAP/Things architecture has the best end-to-end delay, packet loss, throughput, energy consumption, and handover.

scholarly journals Adaptive Access Class Barring Method for Machine Generated Communications

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Jaesung Park ◽  
Yujin Lim
Keyword(s):  
Success Probability ◽  
Access Network ◽  
Random Access ◽  
Original Method ◽  
Collision Probability ◽  
Data Traffic ◽  
Coverage Area ◽  
Access Channel ◽  
Communication Devices ◽  
A Cell

Cellular network is provisioned to serve traffic demands generated by human being. The random access channel used for nodes to compete for a connection with an eNB is limited. Even though machines generate very small amount of data traffic, the signaling channel of a network becomes overloaded and collisions occur to fail the access if too many MTC (Machine Type Communication) devices attempt to access network. To tackle the issue, 3GPP specifies an access class barring but leaves a specific algorithm as an implementation issue. In this paper, we propose an adaptive access barring method. Generally, an eNB does not know the number of MTC devices in its coverage area. Thus, it is difficult to control the barring factor by predicting the number of MTC devices in a service area of a cell. On the contrary, we control the barring factor based on the prediction of access intensity which can be measured at an eNB. Simulation results show that since the proposed method can manipulate the barring factor autonomously according to the access intensity, it is superior to the original method in terms of the access success probability and the collision probability.

scholarly journals DESIGN AND PERFORMANCE OF MOBILE PHONE JAMMER

2020 ◽  
Vol 6 (12) ◽  
pp. 1-5
Author(s):  
Priti Y. Umratkar ◽  
Harshali Chalfe ◽  
S. K. Totade
Keyword(s):  
Mobile Phone ◽  
Mobile Phones ◽  
Mobile Communication ◽  
Cell Phone ◽  
Base Station ◽  
Cellular Phones ◽  
Coverage Area ◽  
Medical Centers ◽  
A Cell ◽  
And Performance

The continuously use of mobile phone can be attributed to it can use in any places and thus have become one of the most widely used devices in mobile communication which makes it so important in our lives. The convenience and portability of cellphones has made it possible to be carried everywhere. e.g Churches, lecture halls, medical centers etc. Its benefit can create disturbance in some places when there is continuous beeping or ringtones of cell phones which becomes annoying when such noise is disturbance in areas where silence is required or the use or of mobile phone is restricted or prohibited like Libraries and Study rooms A mobile phone jammer is an instrument used to prevent cellular phones from receiving signals from base station. It is a device that transmit signal on the same frequency at which the GSM system operates, the jamming success when the mobile phones in the area where the jammer is located are disabled. The mobile phone jammer unit is intended for blocking all mobile phone types within designated indoor areas. The mobile Phone Jammer is a 'plug and play' unit, its installation is quick and its operation is easy. Once the mobile Phone Jammer is operating, all mobile phones present within the jamming coverage area are blocked, and cellular activity in the immediate surroundings (including incoming and outgoing calls, SMS, pictures sending, etc.) is jammer. This paper focuses on the design of a cell phone jammer to prevent the usage of mobile communication in restricted areas without interfering with the communication channels outside its range.

Structure and Function of the Urokinase Receptor

1999 ◽  
Vol 82 (S 01) ◽  
pp. 19-22 ◽  
Author(s):  
Massimo Resnati ◽  
Anna Mondino ◽  
Francesco Blasi
Keyword(s):  
Conformational Change ◽  
Tyrosine Kinases ◽  
High Efficiency ◽  
Cytoskeletal Organization ◽  
Surface Molecules ◽  
Experimental Systems ◽  
Recombinant Receptor ◽  
A Cell ◽  
And Function

SummaryThe binding of the urokinase plasminogen activator (uPA) to its receptor (uPAR) regulates cell adhesion, surface proteolysis, chemotaxis and cell extravasation in a number of experimental systems. Recent evidences have suggested that uPAR can by itself mediate chemotaxis of human monocytes and cause profound changes in cytoskeletal organization indicating that this receptor has the properties of a cell-surface regulated chemokine. Indeed, it is likely that upon binding to uPA, uPAR undergoes a conformational change that uncovers a new epitope located in the linker region between domain 1 and 2 of the receptor and is endowed with a potent chemotactic activity. This conformational change can be mimicked in vitro by enzymatic processing of a recombinant receptor. We have shown that chymotrypsin cleaves uPAR between domain 1 and 2 in an area that can be also cleaved by uPA at high efficiency and generate a receptor that can mediate monocytes migration independently of uPA binding. This mechanism is pertussis-toxin sensitive and involves activation of tyrosine kinases and cytoskeletal reorganization events in vitro. These studies indicate that in addition to its receptor function, upon binding to uPA, uPAR becomes a pleiotropic ligand for other still to be identified surface molecules.

scholarly journals A high-efficiency, information-based exploration path planning method for active simultaneous localization and mapping

2020 ◽  
Vol 17 (1) ◽  
pp. 172988142090320
Author(s):  
Peng Li ◽  
Cai-yun Yang ◽  
Rui Wang ◽  
Shuo Wang
Keyword(s):  
Path Planning ◽  
Information Entropy ◽  
High Efficiency ◽  
Dead Reckoning ◽  
Simultaneous Localization And Mapping ◽  
Planning Method ◽  
Coverage Area ◽  
High Coverage ◽  
Full Coverage ◽  
Localization And Mapping

The efficiency of exploration in an unknown scene and full coverage of the scene are essential for a robot to complete simultaneous localization and mapping actively. However, it is challenging for a robot to explore an unknown environment with high efficiency and full coverage autonomously. In this article, we propose a novel exploration path planning method based on information entropy. An information entropy map is first constructed, and its boundary features are extracted. Then a Dijkstra-based algorithm is applied to generate candidate exploration paths based on the boundary features. The dead-reckoning algorithm is used to predict the uncertainty of the robot’s pose along each candidate path. The exploration path is selected based on exploration efficiency and/or high coverage. Simulations and experiments are conducted to evaluate the proposed method’s effectiveness. The results demonstrated that the proposed method achieved not only higher exploration efficiency but also a larger coverage area.

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