scholarly journals Completion Time Minimization for Multi-UAV Information Collection via Trajectory Planning

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 4032 ◽  
Author(s):  
Zhen Qin ◽  
Aijing Li ◽  
Chao Dong ◽  
Haipeng Dai ◽  
Zhengqin Xu
Keyword(s):  
Completion Time ◽  
Low Cost ◽  
High Mobility ◽  
Complete Information ◽  
Mixed Integer ◽  
Information Collection ◽  
Coverage Problem ◽  
Point Selection ◽  
Cycle Cover ◽  
Multi Uav

Unmanned Aerial Vehicles (UAVs) are widely used as mobile information collectors for sensors to prolong the network time in Wireless Sensor Networks (WSNs) due to their flexible deployment, high mobility, and low cost. This paper focuses on the scenario where rotary-wing UAVs complete information collection mission cooperatively. For the first time, we study the problem of minimizing the mission completion time for a multi-UAV system in a monitoring scenario when considering the information collection quality. The mission completion time includes flying time and hovering time. By optimizing the trajectories of all UAVs, we minimize the mission completion time while ensuring that the information of each sensor is collected. This problem can be formulated as a mixed-integer non-convex one which has been proved to be NP-hard. To solve the formulated problem, we first propose a hovering point selection algorithm to select appropriate hovering points where the UAVs can sequentially collect the information from multiple sensors. We model this problem as a BS coverage problem with the information collection quality in consideration. Then, we use a min-max cycle cover algorithm to assign these hovering points and get the trajectory of each UAV. Finally, with the obtained UAVs trajectories, we further consider the UAVs can also collect information when flying and optimize the time allocations. The performance of our algorithm is verified by simulations, which show that the mission completion time is minimum compared with state-of-the-art algorithms.

scholarly journals Energy-Efficient UAV Communication with Multiple GTs Based on Trajectory Optimization

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yu Xu ◽  
Lin Xiao ◽  
Dingcheng Yang ◽  
Laurie Cuthbert ◽  
Yapeng Wang
Keyword(s):  
Trajectory Optimization ◽  
Low Cost ◽  
High Mobility ◽  
Optimization Techniques ◽  
Mixed Integer ◽  
Flight Trajectory ◽  
Special Cases ◽  
Standard Linear ◽  
Standard Linear Programming

Wireless communications with unmanned aerial vehicles (UAVs) is a promising technology offering potential high mobility and low cost. This paper studies a UAV-enabled communication system, in which a fixed-wing UAV is deployed to collect information from a group of distributed ground terminals (GTs). Considering the requirements for quality of service (QoS) (i.e., the throughput of each GT is above a given threshold) and GT scheduling, we maximize the energy efficiency (EE) of the UAV in bits/Joule by optimizing the UAV’s flight trajectory. In this paper, a mixed integer nonconvex optimization problem is formulated. As that is difficult to solve, we divide the formulated problem into two subproblems and apply standard linear programming (LP) and successive convex optimization techniques. We further propose an efficient iterative algorithm that jointly optimizes GT scheduling and the UAV’s trajectory. Moreover, we set two special cases as benchmarks to measure the performance of the proposed design. The numerical results show that our proposed design achieves much better performance than the other two benchmark designs.

scholarly journals Visual Measurement System for Wheel–Rail Lateral Position Evaluation

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1297
Author(s):  
Viktor Skrickij ◽  
Eldar Šabanovič ◽  
Dachuan Shi ◽  
Stefano Ricci ◽  
Luca Rizzetto ◽  
...  
Keyword(s):  
Measurement System ◽  
Inertial Sensor ◽  
Low Cost ◽  
Image Point ◽  
Low Velocity ◽  
Point Selection ◽  
Lateral Direction ◽  
Initial Field ◽  
Visual Measurement ◽  
Track Geometry

Railway infrastructure must meet safety requirements concerning its construction and operation. Track geometry monitoring is one of the most important activities in maintaining the steady technical conditions of rail infrastructure. Commonly, it is performed using complex measurement equipment installed on track-recording coaches. Existing low-cost inertial sensor-based measurement systems provide reliable measurements of track geometry in vertical directions. However, solutions are needed for track geometry parameter measurement in the lateral direction. In this research, the authors developed a visual measurement system for track gauge evaluation. It involves the detection of measurement points and the visual measurement of the distance between them. The accuracy of the visual measurement system was evaluated in the laboratory and showed promising results. The initial field test was performed in the Vilnius railway station yard, driving at low velocity on the straight track section. The results show that the image point selection method developed for selecting the wheel and rail points to measure distance is stable enough for TG measurement. Recommendations for the further improvement of the developed system are presented.

scholarly journals Customer order scheduling with job-based processing on a single-machine to minimize the total completion time

2021 ◽  
Vol 12 (3) ◽  
pp. 273-292 ◽  
Author(s):  
Ferda Can Çetinkaya ◽  
Pınar Yeloğlu ◽  
Hale Akkocaoğlu Çatmakaş
Keyword(s):  
Completion Time ◽  
Numerical Control ◽  
Total Completion Time ◽  
Mixed Integer ◽  
Order Scheduling ◽  
Customer Order ◽  
Processing Approach ◽  
Problem Instances ◽  
Customer Order Scheduling ◽  
Customer Orders

This study considers a customer order scheduling (COS) problem in which each customer requests a variety of products (jobs) processed on a single flexible machine, such as the computer numerical control (CNC) machine. A sequence-independent setup for the machine is needed before processing each product. All products in a customer order are delivered to the customer when they are processed. The product ordered by a customer and completed as the last product in the order defines the customer order’s completion time. We aim to find the optimal schedule of the customer orders and the products to minimize the customer orders’ total completion time. We have studied this customer order scheduling problem with a job-based processing approach in which the same products from different customer orders form a product lot and are processed successively without being intermingled with other products. We have developed two mixed-integer linear programming models capable of solving the small and medium-sized problem instances optimally and a heuristic algorithm for large-sized problem instances. Our empirical study results show that our proposed tabu search algorithm provides optimal or near-optimal solutions in a very short time. We have also compared the job-based and order-based processing approaches for both setup and no-setup cases and observed that the job-based processing approach yields better results when jobs have setup times.

An approach for the efficient immobilization of 79Se using Fe-OOH modified GMZ bentonite

2020 ◽  
Vol 108 (2) ◽  
pp. 113-126
Author(s):  
Junqiang Yang ◽  
Keliang Shi ◽  
Xuejie Sun ◽  
Xiaoqing Gao ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Low Cost ◽  
High Mobility ◽  
Synthesis Process ◽  
Gmz Bentonite ◽  
Filling Material ◽  
Xps Spectra ◽  
Ft Ir ◽  
High Level ◽  
Critical Consideration ◽  
Formation Of Complexes

AbstractBecause of high mobility, the immobilization of long-lived fission product 79Se (often existed as 79Se(IV) and 79Se(VI) anions) is a critical consideration in the repository of high-level radioactive waste. In this work, a Fe-OOH modified bentonite (Fe-OOH-bent) was synthesized as a potential filling material in the repository site for effective adsorption and present the migration of different species of 79Se. The adsorbent was characterized using FT-IR, XRD, XFS, zeta potential and BET to clarify its physical properties, compositions and structures. A good thermal and radiation stabilities of Fe-OOH-bent was confirmed by its stable uptake ratio for Se(IV) and Se(VI) compared to original samples. The batch experimental results show that Se(IV) and Se(VI) can be efficiently removed from aqueous by Fe-OOH-bent within 60 min with maximum adsorption capacities of 68.45 mg/g for Se(IV) and 40.47 mg/g for Se(VI) in the optimal conditions, indicating its high potential application in consideration of its simple synthesis process, low cost and high adsorption capacity in view of immobilization of 79Se. The surface species and variation of oxide state of Fe as well as Se(IV) and Se(VI) onto Fe-OOH-bent were investigated by XPS analysis. The values of relative area of Se(IV)–O and Se(VI)–O in XPS spectra followed the same tendency as their adsorption ratio with the variation of system pH, suggesting that the formation of complexes between selenium species and Fe-OOH-bent surface.

EXPORT SUBSIDIES AND THE FIRST-MOVER (DIS)ADVANTAGE

2011 ◽  
Vol 56 (01) ◽  
pp. 41-50
Author(s):  
MATLOOB PIRACHA
Keyword(s):  
Private Information ◽  
Optimal Policy ◽  
Low Cost ◽  
Complete Information ◽  
Full Information ◽  
Investment Choice ◽  
Export Subsidies ◽  
The Government ◽  
The Impact ◽  
First Mover

In the presence of home firm's ability to make a cost-reducing investment before or after the government set its subsidy level, this paper analyzes the impact of timing on the optimal policy of the government. We find that under complete information assumption, the firm will overinvest and consequently, the government will over-subsidize, resulting in lower welfare levels than would arise under non-intervention. We extend the model to the case in which the home firm has private information about its own costs, which it may want to signal to the government through its investment choice. We find that under this setup, the low-cost firm overinvests even more than under full information case, making the policy of non-intervention even more attractive.

scholarly journals Predicting Topology Propagation Messages in Mobile Ad Hoc Networks: The Value of History

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 24
Author(s):  
Pere Millán ◽  
Carles Aliagas ◽  
Carlos Molina ◽  
Roc Meseguer ◽  
Sergio F. Ochoa ◽  
...  
Keyword(s):  
Ad Hoc ◽  
Low Cost ◽  
High Mobility ◽  
Message Routing ◽  
Link State ◽  
Previous Proposal ◽  
Mobile Ad Hoc ◽  
Hoc Networks ◽  
Optimized Link State Routing ◽  
Prediction Strategy

The mobile ad hoc communication in highly dynamic scenarios, like urban evacuations or search-and-rescue processes, plays a key role in coordinating the activities performed by the participants. Particularly, counting on message routing enhances the communication capability among these actors. Given the high dynamism of these networks and their low bandwidth, having mechanisms to predict the network topology offers several potential advantages; e.g., to reduce the number of topology propagation messages delivered through the network, the consumption of resources in the nodes and the amount of redundant retransmissions. Most strategies reported in the literature to perform these predictions are limited to support high mobility, consume a large amount of resources or require training. In order to contribute towards addressing that challenge, this paper presents a history-based predictor (HBP), which is a prediction strategy based on the assumption that some topological changes in these networks have happened before in the past, therefore, the predictor can take advantage of these patterns following a simple and low-cost approach. The article extends a previous proposal of the authors and evaluates its impact in highly mobile scenarios through the implementation of a real predictor for the optimized link state routing (OLSR) protocol. The use of this predictor, named OLSR-HBP, shows a reduction of 40–55% of topology propagation messages compared to the regular OLSR protocol. Moreover, the use of this predictor has a low cost in terms of CPU and memory consumption, and it can also be used with other routing protocols.

Control System for Automatic Positioning the Working Device of Metamorphic Concrete Grouting Machine

2013 ◽  
Vol 336-338 ◽  
pp. 1281-1285
Author(s):  
Tian Fu Cai ◽  
Jian Zhong Zhou ◽  
Xue Min Wu ◽  
Wei Ping Peng ◽  
Xi Yan
Keyword(s):  
Control System ◽  
Complete Information ◽  
Information Collection ◽  
Signal Acquisition ◽  
Hydraulic Control ◽  
Positioning Control ◽  
Reference Position ◽  
Hydraulic Cylinders ◽  
Working Device ◽  
Automatic Positioning

In order to improve the automation level of the metamorphic concrete grouting machine, an automatic positioning control system was developed based on the knowledge of signal acquisition and hydraulic control technology with PLC and HMI. Angle sensors installed on the arms of the grouting machine and the grouting working device were used in this system. Firstly, users determine the reference position according to practical needs, and use the PLC to complete information collection and respective reference positions recording. Then, before the grouting starts, PLC makes a real-time detection and compares the positions of the excavator boom, arm and the grouting working device, and controls the hydraulic cylinders of the excavator sequentially to adjust the positions through electro-hydraulic proportional velocity regulating valve and solenoid control valves. This control system can realize automatic positioning.

scholarly journals UAV PHOTOGRAMMETRY WITH OBLIQUE IMAGES: FIRST ANALYSIS ON DATA ACQUISITION AND PROCESSING

2016 ◽  
Vol XLI-B1 ◽  
pp. 835-842 ◽  
Author(s):  
I. Aicardi ◽  
F. Chiabrando ◽  
N. Grasso ◽  
A. M. Lingua ◽  
F. Noardo ◽  
...  
Keyword(s):  
Low Cost ◽  
Complete Information ◽  
Point Of View ◽  
Historical Building ◽  
Critical Issues ◽  
Commercial Off The Shelf ◽  
Aerial Platforms ◽  
High Level ◽  
Architectural Survey ◽  
Oblique Images

In recent years, many studies revealed the advantages of using airborne oblique images for obtaining improved 3D city models (e.g. including façades and building footprints). Expensive airborne cameras, installed on traditional aerial platforms, usually acquired the data. The purpose of this paper is to evaluate the possibility of acquire and use oblique images for the 3D reconstruction of a historical building, obtained by UAV (Unmanned Aerial Vehicle) and traditional COTS (Commercial Off-the-Shelf) digital cameras (more compact and lighter than generally used devices), for the realization of high-level-of-detail architectural survey. The critical issues of the acquisitions from a common UAV (flight planning strategies, ground control points, check points distribution and measurement, etc.) are described. Another important considered aspect was the evaluation of the possibility to use such systems as low cost methods for obtaining complete information from an aerial point of view in case of emergency problems or, as in the present paper, in the cultural heritage application field. The data processing was realized using SfM-based approach for point cloud generation: different dense image-matching algorithms implemented in some commercial and open source software were tested. The achieved results are analysed and the discrepancies from some reference LiDAR data are computed for a final evaluation. The system was tested on the S. Maria Chapel, a part of the Novalesa Abbey (Italy).

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