Additional Information Exchange Research Articles

Ensuring situational awareness of the moving objects group using one reference navigation station

Problem statement. In the conditions of radio suppression of the global navigation satellite systems, situational awareness of a group of moving objects can be provided using local navigation. Known methods based on the use of local navigation to ensure situational awareness require the mutual exchange of information between the objects of the group, and used several reference stations to determine the coordinates. Purpose. To develop and research of a method of mutual awareness of each moving object about the spatio-temporal state of all moving objects of the group without organizing additional information exchange between the objects of the group, based on the use of one reference navigation station with known local coordinates. Results. A method for ensuring situational awareness of a group of moving objects is proposed. Method based on the use of one reference navigation station equipped with a radio direction finder. The method ensures positioning accuracy of the follower object on board the lead object up to 10 m when the follower object is within the interfocal space of the goniometric-difference-range-measuring system formed by the reference navigation station and the lead object. When the follower object leaves the interfocal space degradation of the accuracy characteristics up to 100 m is observed, which is associated with an increase in the values of the geometric factor. In this case, the accuracy of estimating the delay of interrogation and response signals should be no worse than 5×10-7 s, and the measurement error of the azimuth angle in the radio direction finder of the reference navigation station should not exceed 3-5°. Practical significance. The proposed method can be used in practice to ensure situational awareness of a group of subscribers of a local communication system for special purposes.

An Improved Dynamic Programming-Based Decentralized Algorithm for AC-OPF of Radially Connected Multi-Level Networks

In this paper, an improved dynamic programming (IDP)-based decentralized algorithm is proposed for the AC-optimal power flow (AC-OPF) of radially connected transmission-distribution-microgrid networks (RCTDMNs). Most of the existing decentralized algorithms need to iterate among networks, which may lead to additional computational and information exchange burden. Different from these algorithms, we decompose the original AC-OPF problem into small-scale subproblems based on dynamic programming (DP) theory, and then solve them in a decentralized manner without iteration among networks. In order to improve the computational performance of DP, its value functions are directly obtained by solving Galerkin projection equations (GPEs) instead of traversing the whole state space. Moreover, a parallel technique is proposed to further accelerate the proposed IDP algorithm when dealing with the AC-OPF problem of RCTDMNs. Case studies on various test systems demonstrate the effectiveness of the proposed method.

Stabilization of Symmetric Formations

This work proposes a solution to the distance-constrained formation control problem to attain symmetric formations. Utilizing recent results from rigidity theory for symmetric frameworks, we design a gradient-based control strategy that simultaneously drives the agents to the desired inter-agent distances and also a special position characterizing additional symmetry constraints on the graph. We show that for graphs where there exist edges between agents in the same vertex orbit induced by the automorphism group, no additional information exchange links are required. Furthermore, leveraging the symmetry constraints of the system it is possible to solve the formation control problem with fewer edges than standard approaches. In particular, the framework is not required to be minimally infinitesimally rigid in this case. Our results are demonstrated with a numerical example.

Low-Complexity Data Collection Scheme for UAV Sink Nodes in Cellular IoT Networks

Owing to the nature of battery-operated sensors, the residual energy of their battery should be considered when a sink node collects sensory data from them. If a sink attempts to collect data from a sensor that does not have sufficient residual energy to transmit data, the utilization of wireless communication resources may be degraded. However, requiring a periodic residual energy report of the sensors considerably reduces the energy efficiency of them. Consequently, the sink node must be able to estimate the residual energy of the sensors without additional information exchange before attempting to collect data. To tackle this problem, we propose a data collection scheme for mobile sinks in cellular Internet-of-things (IoT) networks. The scheme consists of two phases. In the first phase, the mobile sink estimates the residual energy of the surrounding sensors. To reduce the complexity, we design a state diagram composed of three states based on the Markov chain of the sensor. The sink node calculates the communicable likelihood of each sensor based on the state diagram and collects data from the sensor with the highest likelihood. In the second phase, a cellular base station (BS) selects the appropriate mobile sink to improve the signal-to-interference-plus-noise ratio (SINR) of the signal from a cellular user. Each sink node delivers the bidding price to the BS based on the likelihoods of the sensors. The BS determines an appropriate sink node to allocate resources based on the received bidding prices. Moreover, we show the performance of the proposed method in terms of SINR and IoT network utilization through simulation.

THE IDEA OF THE TUTORIAL SYSTEM OF TEACHING IN CLASSICAL UNIVERSITIES

The study as the original philosophy of education and the leading way of organizing the educational system originates in the medieval European universities of the XII–XIV centuries. The author of the article has done an analysis of origin and development of tutoring in British educational practice. In English language “tutor” means a teacher, usually instructing individual pupils and often engaged privately (at universities, colleges, etc); a member of staff responsible for the teaching and supervision of a certain number of students. Tutoring technology appeared in XII century and from then had a long road from medieval European universities of Oxford and Cambridge to implementation into educational practice in most countries. The article reviews basic principles of tutor work, historical and educational meaning of tutoring as a technique of help and support for learners. Ukrainian scientists have studied the problem of tutoring and extended the main functions of tutoring: 1) the organizational leadership of the educational and cognitive activities of the student; 2) determination of its capabilities and interests; 3) justification of the student rating; 4) assistance in correct and effective use of teaching and methodological support from a certain discipline; 5) personal formation, education, formation of a way of life, definition of prospects; 6) ensuring the exchange of additional information between the student and the teachers. Tutor technique is relevant at the present time and requires detailed studing and implementation in educational practice. Tutoring in the modern world is a pedagogical position, which is tied to a special rank of the organizational system.

Weighted cooperative reinforcement learning‐based energy‐efficient autonomous resource selection strategy for underlay D2D communication

Underlay Device-to-Device (D2D) communication is a key technology responsible for high data rate, ultra-low latency with high spectral and energy efficiency in 5G cellular networks. But to achieve its full potential, optimal channel allocation and effective co-channel interference management must be accomplished. To address this challenge, we propose a multi-agent reinforcement learning based autonomous channel selection scheme for D2D communication. The proposed scheme, Weighted Cooperative Q -Learning based Resource Selection (WCopQLRS), allows a D2D pair to learn to select a channel from the available resources autonomously. Learning process of each D2D transmitter involves cooperation from neighboring D2D agents by exchanging their latest Q -values. An additional parameter called cooperation range is used to determine the neighboring pairs whose Q -values can be used for learning the optimal policy. The limited prior information prevents a linear increase in the dimensions of Q -value matrix of each learning agent when the number of D2D pairs within the cell is huge. Though WCopQL-RS involves additional information exchange among agents as compared to independent learning but also provides improved system throughput and convergence speed. It is shown through simulation results that WCopQL-RS outperforms other existing schemes in terms of average D2D user throughput, energy consumption and fairness value.

Joint Space-Frequency Block Codes and Signal Alignment for Heterogeneous Networks

In this paper, we propose a new diversity-oriented space-frequency block codes (SFBC) and signal alignment (SA) enabled physical network coding (PNC) method for the uplink of heterogeneous networks. The proposed joint Dual-SFBC with SA-PNC design substantially reduces interference and enables connecting a larger number of users when compared with methods adopting interference alignment (IA) or PNC. The main motivation behind the dual SFBC and SA-PNC design is that it allows the efficient coexistence of macro and small cells without any inter-system channel information requirements. Numerical results also verify that the proposed method outperforms the existing SA-PNC static method without any additional information exchange requirement between the two systems while achieving the main benefits of IA and SA-PNC coordinated methods recently proposed.

On the emergence of oscillations in distributed resource allocation

We consider the problem of resource allocation in a decentralised market where users and suppliers trade for a single commodity. Due to the lack of strict concavity, convergence to the optimal solution by means of classical gradient type dynamics for the prices and demands, is not guaranteed. In the paper we explicitly characterise in this case the asymptotic behaviour of trajectories and provide an exact characterisation of the limiting oscillatory solutions. Methods of modifying the dynamics are also given, such that convergence to an optimal solution is guaranteed, without requiring additional information exchange among the users.

User Equipment Beamforming Optimization for Multi-Cell Massive MIMO Systems

A user equipment (UE) beamforming method is proposed in this letter for massive MIMO systems with multi-antenna UEs. The method requires no additional channel information exchange among UEs and has a low computational cost. The beamforming vector is obtained by the semi-definite relaxation based method. Simulations under various environmental configurations demonstrate the performance improvement of the proposed method.

Adaptive Consensus-Based Distributed Target Tracking in Sensor Networks With Limited Sensing Range

In this brief, consensus-based algorithms for distributed target tracking are discussed, and a new algorithm with decentralized adaptation is proposed for sensor networks with limited sensing range. The given comparative analysis shows that tuning of the gains in the consensus scheme is of crucial importance for getting simple, yet efficient tracking algorithms, requiring the exchange of only local state estimates between the nodes. The proposed algorithm, which gives higher importance to the nodes currently receiving measurements, is based on the exchange of additional binary information and represents a robust and efficient tool for practice. Stability of the algorithm is theoretically discussed on a given scenario. Selected examples illustrate its performance in terms of the estimation error and the disagreement between the nodes.

Cooperative Driving With a Heavy-Duty Truck in Mixed Traffic: Experimental Results

This paper describes the implementation and testing of a Cooperative Adaptive Cruise Control (CACC) strategy on a heavy-duty truck. The adopted control strategy utilizes additional information exchange through wireless communication to improve the vehicle-following behavior achieved by the underlying adaptive cruise controller (ACC). The control method is evaluated in a mixed traffic condition. It is shown that the truck can perform smooth predecessor following in most of the test scenarios, even for small intervehicle distances. Furthermore, the results demonstrate how string stability is affected by wireless communication imperfections and acceleration (deceleration) limitations of the heavy-duty truck in an inhomogeneous platoon.

이동 궤적을 고려한 링크 상태 예측을 통한 공중 백본 네트워크 라우팅 성능 향상 방법

The airborne backbone network(ABN) provides communication transport services between airborne nodes, surface nodes and satellite nodes. Such ABN is generally constructed with wide-body and high-capacity planes such as AWACS, which can fly long-term along pre-defined flight paths. In this paper, we propose an efficient method to improve routing performances by reconfiguring routing path before link failure based on the prediction of link state with the information of pre-defined backbone nodes' trajectories. Since the proposed method does not need additional information exchange between airborne nodes in order to acknowledge the link failure, it can be effectively used for airborne backbone network with limited bandwidths.

Teenagers in cyberspace: an investigation of language use and language change in internet chatrooms

This article reports on a small‐scale investigation into the use of Internet chatrooms by teenage girls. Based on interview and observational data, it illustrates how the use of popular electronic communication is resulting in linguistic innovation within new, virtual social networks in a way that reflects more wide‐reaching changes in the communication landscape. The paper suggests that teenagers and young people are in the vanguard of these processes of change as they fluently exploit the possibilities of digital technology, radically changing the face of literacy. The study looks at teenagers’ perceptions of chatroom encounters and their learning about new ways of social and linguistic interaction. Observations of teenagers online show how rapid written conversations which combine features of face‐to‐face talk with explorations in interactive writing and the exchange of additional digital information, such as image files and web addresses, are enabling these young people to develop sophisticated and marketable skills. These innovations are contrasted with recent media and educational criticism of the language use associated with new technology. This tension between change and conservatism is explored by applying Bourdieu’s concept of ‘linguistic capital’.

Comparative operating characteristics of large vs. small ferroalloy units

The silicon recovery is not affected by increased furnace loads when present design precepts are followed. There is an improvement in production efficiency up to about 24,000 kva. A fairly wide range of voltages, loads, and electrode size relationships are available to the operator without severe production penalty. It is hoped this release of data will encourage additional information exchange for the optimum operation of the industry’s furnaces.