Journal articles on the topic 'Military Power trains Computer simulation'
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1
Alnuman, Hammad, Daniel Gladwin, and Martin Foster. "Electrical Modelling of a DC Railway System with Multiple Trains." Energies 11, no. 11 (November 19, 2018): 3211. http://dx.doi.org/10.3390/en11113211.
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Electrical modelling of rail tracks with multiple running trains is complex due to the difficulties in solving the power flow. The train positions, speed and acceleration are constantly varying resulting in a nonlinear system. In this work, a method is proposed for modelling DC electric railways to support power flow analysis of a simulated metro train service. The method exploits the MathWorks simulation tool Simscape, using it to model the mechanical and electrical characteristics of the rail track system. The model can be simulated to provide voltages at any position in the track and additionally, the voltages seen by any train. The model includes regenerative braking on trains, this is demonstrated to cause overvoltage in the feeding line if it is higher than the power demand of the other trains at that time. Braking resistors are used to protect the network from overvoltage by burning the excess energy. Through the implementation of Energy Storage Systems (ESSs), it will be possible to improve the energy efficiency and remove timetabling restrictions of electric railways by effectively controlling the rail track voltage. The paper proposes several methods to validate the model.
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Cherepanov, Aleksandr, Vasily Zakaryukin, and Andrey Kryukov. "Modeling of traction power supply systems for movement of high-speed trains." MATEC Web of Conferences 216 (2018): 02006. http://dx.doi.org/10.1051/matecconf/201821602006.
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Upgrading of traction power supply systems will be required to transfer electrified railway lines to high-speed traffic. Coaxial cables and balancing transformers can be used as technical upgrading means. The article presents the results of computer simulation in the Fazonord software complex of the traditional 2x25 kV traction system, as well as systems with coaxial cables and Woodbridge symmetric transformers. Simulation results showed that the use of cables contributes to a significant increase in the level of voltage on current collectors of electric rolling stock. Use of modified Woodbridge transformers makes it possible to reduce the imbalance coefficient by the reverse sequence on high voltage buses of traction substations. However, the reduction is insignificant and depends on the modes of movement of trains in adjacent inter-station zones. The biggest positive effects occur in the integrated application of balancing transformers and coaxial cables.
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Hussen, Hamed Ali, Essam Lauibi Esmail, and Rahman A. Hussen. "Power Flow Simulation for Two-Degree-of-Freedom Planetary Gear Transmissions with Experimental Validation." Modelling and Simulation in Engineering 2020 (November 6, 2020): 1–14. http://dx.doi.org/10.1155/2020/8837605.
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The basic relationships among gear ratios, velocity succession, torque directions, power ratios, energy losses, and efficiency are derived from first principles. The techniques presented here can be applied to ordinary, planetary, or mixed gear trains. Also, these techniques provide more insight into how power is flowing through the different parts of the mechanism. Power flow relationships are a helpful tool to study power amplification and power circulation in multipath transmissions. They also provide more insight into how the gear pair entities (GPEs) or gear train entities (GTEs) affect total power losses and allow immediate derivation of the overall efficiency. A representative two-input mechanism is analyzed to demonstrate the effectiveness of improved techniques. The theoretical results are compared with experimental data of previous work. The theoretical and experimental curves exhibit identical trends with a distinct jump in friction loss. The jump is explained by a change in the way of the power flow through the mechanism. The conditions under which power circulation occurs are determined. The results have important implications for understanding how to improve the efficiency of multipath power flow systems.
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BAI, Yun, Baohua MAO, Fangming ZHOU, Yong DING, and Chengbing DONG. "Energy-Efficient Driving Strategy for Freight Trains Based on Power Consumption Analysis." Journal of Transportation Systems Engineering and Information Technology 9, no. 3 (June 2009): 43–50. http://dx.doi.org/10.1016/s1570-6672(08)60062-8.
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Salau, Ayodeji Olalekan, Candidus U. Eya, and Omeje Crescent Onyebuchi. "Nonzero Staircase Modulation Scheme for Switching DC-DC Boost Converter." Journal of Control Science and Engineering 2020 (July 18, 2020): 1–15. http://dx.doi.org/10.1155/2020/8347462.
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This paper presents a novel modulation scheme known as the nonzero staircase modulation scheme for switching DC-DC boost converters. This modulation scheme generates two distinct pulse trains/firing signals when a 50 Hz nonzero staircase modulating signal is compared with a 1.5 kHz triangular wave signal. Unlike the conventional modulation schemes, the proposed novel modulation scheme provides two distinctive trains of pulse-width modulated signals for mitigating low and high harmonics. It also possesses 0.56% total harmonic distortions (THD) of the output voltage waveform system, a power output of 4591 W, and THD of 1.12% in the DC-DC boost converter system. It has a simple design and low power loss of 209 W. The proposed scheme enables the single switch boost DC-DC converter used to have an efficiency of 96%. The proposed scheme can be applied in single switch or double switch boost DC-DC converter based-hospital equipment.
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Ramos, Germán Andrés, Tomàs Montobbio de Pérez-Cabrero, Carles Domènech-Mestres, and Ramon Costa-Castelló. "Industrial Robots Fuel Cell Based Hybrid Power-Trains: A Comparison between Different Configurations." Electronics 10, no. 12 (June 14, 2021): 1431. http://dx.doi.org/10.3390/electronics10121431.
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Electric vehicles are becoming more and more popular. One of the most promising possible solutions is one where a hybrid powertrain made up of a FC (Fuel Cell) and a battery is used. This type of vehicle offers great autonomy and high recharging speed, which makes them ideal for many industrial applications. In this work, three ways to build a hybrid power-train are presented and compared. To illustrate this, the case of an industrial robot designed to move loads within a fully automated factory is used. The analysis and comparison are carried out through different objective criteria that indicate the power-train performance in different battery charge levels. The hybrid configurations are tested using real power profiles of the industrial robot. Finally, simulation results show the performance of each hybrid configuration in terms of hydrogen consumption, battery and FC degradation, and dc bus voltage and current regulation.
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Morais, Vítor A., and António P. Martins. "Traction power substation balance and losses estimation in AC railways using a power transfer device through Monte Carlo analysis." Railway Engineering Science 30, no. 1 (January 17, 2022): 71–95. http://dx.doi.org/10.1007/s40534-021-00261-y.
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AbstractThe high dynamic power requirements present in modern railway transportation systems raise research challenges for an optimal operation of railway electrification. This paper presents a Monte Carlo analysis on the application of a power transfer device installed in the neutral zone and exchanging active power between two sections. The main analyzed parameters are the active power balance in the two neighbor traction power substations and the system power losses. A simulation framework is presented to comprise the desired analysis and a universe of randomly distributed scenarios are tested to evaluate the effectiveness of the power transfer device system. The results show that the density of trains and the relative branch length of a traction power substation should be considered in the evaluation phase of the best place to install a power transfer device, towards the reduction of the operational power losses, while maintaining the two substations balanced in terms of active power.
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Wu, Jie, Lizhong Bie, Nan Jin, Leilei Guo, Jitao Zhang, Jiagui Tao, and Václav Snášel. "Dual-Frequency Output of Wireless Power Transfer System with Single Inverter Using Improved Differential Evolution Algorithm." Energies 13, no. 9 (May 2, 2020): 2209. http://dx.doi.org/10.3390/en13092209.
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In wireless charging devices, a transmitter that applies a single inverter to output dual-frequency can effectively solve the charging incompatibility problem caused by different wireless charging standards and reduce the equipment volume. However, it is very difficult to solve the switching angle of the modulated dual-frequency waveform, which involves non-linear high-dimensional multi-objective optimization with multiple constraints. In this paper, an improved differential evolution (DE) algorithm is proposed to solve the transcendental equations of switching angle trains of dual-frequency programmed harmonic modulation (PHM) waveform. The proposed algorithm maintains diversity while preserving the elites and improves the convergence speed of the solution. The advantage of the proposed algorithm was verified by comparing with non-dominated sorting genetic algorithm II (NSGA II) and multi-objective particle swarm optimization (MOPSO). The simulation and experimental results validate that the proposed method can output dual-frequency with a single inverter for wireless power transfer (WPT).
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Yang, Ruixuan, Fulin Zhou, and Kai Zhong. "A Harmonic Impedance Identification Method of Traction Network Based on Data Evolution Mechanism." Energies 13, no. 8 (April 13, 2020): 1904. http://dx.doi.org/10.3390/en13081904.
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In railway electrification systems, the harmonic impedance of the traction network is of great value for avoiding harmonic resonance and electrical matching of impedance parameters between trains and traction networks. Therefore, harmonic impedance identification is beneficial to suppress harmonics and improve the power quality of the traction network. As a result of the coupling characteristics of the traction power supply system, the identification results of harmonic impedance may be inaccurate and controversial. In this context, an identification method based on a data evolution mechanism is proposed. At first, a harmonic impedance model is established and the equivalent circuit of the traction network is established. According to the harmonic impedance model, the proposed method eliminates the outliers of the measured data from trains by the Grubbs criterion and calculates the harmonic impedance by partial least squares regression. Then, the data evolution mechanism based on the sample coefficient of determination is introduced to estimate the reliability of the identification results and to divide results into several reliability levels. Furthermore, in the data evolution mechanism through adding new harmonic data, the low-reliability results can be replaced by the new results with high reliability and, finally, the high-reliability results can cover all frequencies. Moreover, the identification results based on the simulation data show the higher reliability results are more accurate than the lower reliability results. The measured data verify that the the data evolution mechanism can improve accuracy and reliability, and their results prove the feasibility and validation of the proposed method.
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Noh, Hee-Min. "Numerical analysis of aerodynamic noise from pantograph in high-speed trains using lattice Boltzmann method." Advances in Mechanical Engineering 11, no. 7 (July 2019): 168781401986399. http://dx.doi.org/10.1177/1687814019863995.
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A pantograph in contact with a catenary for power supply is one of the major aerodynamic noise sources in high-speed trains. To reduce pantograph noise, it is essential to understand the noise generation mechanism of the pantograph. However, it is difficult to determine this mechanism through measurement. Therefore, in this study, the aerodynamic and acoustic performances of a pantograph in a high-speed train were investigated through numerical analysis using the lattice Boltzmann method. First, a real-scaled pantograph was modeled through computer-aided design. Then, the surface and volume meshes of the pantograph model were generated for simulation analysis. Numerical simulation was conducted at a speed of 300 km/h based on the lattice Boltzmann method. Based on the time derivative analysis of flow pressures, it was concluded that the panhead, joint, and base were the dominant noise sources in the pantograph. In particular, various vortexes were generated from the metalized carbon strip of the panhead. The peaks of the sound pressure level propagated from the panhead were 242, 430, and 640 Hz. The noise generation mechanism was analyzed through numerical simulation using noise characteristics.
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Flumian, Didier, Philippe Ladoux, and Emmanuel Sarraute. "Calculation of the Voltage Unbalance Factor for High-Speed Railway Substations with V-Connection Scheme." Electronics 11, no. 4 (February 15, 2022): 595. http://dx.doi.org/10.3390/electronics11040595.
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In France, high-speed railway lines are powered by a 2 × 25 kV/50 Hz electrification system. The substations include two single-phase transformers connected to the high-voltage electrical transmission network on different pairs of phases according to a so-called “V-connection scheme”. In practice, due to the large variations in the power absorbed by the trains, this connection does not make it possible to satisfactorily limit the unbalance in the three-phase voltages. In order to correctly size a balancing system to be associated with the substation, it is necessary to calculate, with precision, the voltage unbalance factor as a function of the power drawn by the trains. In its first part, this paper presents modelling of the substation and proposes an algorithm which allows for the calculation of the upstream line voltage as a function of the power consumption at the secondary of the transformers. The voltage unbalance factor can then be determined over a long period of operation. In the second part of this paper, the same approach is applied with an unbalance-compensator based on Steinmetz circuits controlled by AC choppers. Finally, in both cases, the results of the calculations are validated by simulations performed with PLECS simulation software.
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Liu, Yuxing, Jiazhu Xu, Zhikang Shuai, Yong Li, Yanjian Peng, Chonggan Liang, Guiping Cui, Sijia Hu, Mingmin Zhang, and Bin Xie. "A Novel Harmonic Suppression Traction Transformer with Integrated Filtering Inductors for Railway Systems." Energies 13, no. 2 (January 18, 2020): 473. http://dx.doi.org/10.3390/en13020473.
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This study analyzes and evaluates the feasibility of a harmonic suppression traction transformer (HSTT) for harmonic reduction in railway systems. This new type of transformer can improve the power quality of railway systems by preventing high-frequency harmonic currents from injecting into the traction grid. As the physical size of available space in high-speed trains is strictly limited, low space-occupying filtering techniques are needed. Therefore, an HSTT with integrated filtering inductors (IFIs) capable of being implemented in regular trains is proposed. Taking advantage of the HSTT, a specially constructed inductive-capacitive-inductive (LCL)-type filter is used for harmonic suppression instead of a regular LCL-type filter. The proposed filter is composed of an integrated inductor, leakage inductor of the traction transformer, and an external filter capacitor. In this paper, we analyze the topology of the proposed system, construct a mathematical model to reveal the magnetic decoupling theory of IFIs, and discuss the design and calculation procedures of the HSTT with IFIs. The field circuit coupling simulation of the HSTT with IFIs is performed to validate the effectiveness of the proposed system. Finally, the practical operation based on a 10 kVA prototype shows that the proposed scheme can not only suppress the high-order frequency harmonics but also decrease the installed space of filter devices.
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Fernández-Rodríguez, Adrián, Antonio Fernández-Cardador, Asunción Cucala, and Maria Falvo. "Energy Efficiency and Integration of Urban Electrical Transport Systems: EVs and Metro-Trains of Two Real European Lines." Energies 12, no. 3 (January 24, 2019): 366. http://dx.doi.org/10.3390/en12030366.
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Transport is a main source of pollutants in cities, where air quality is a major concern. New transport technologies, such as electric vehicles, and public transport modalities, such as urban railways, have arisen as solutions to this important problem. One of the main difficulties for the adoption of electric vehicles by consumers is the scarcity of a suitable charging infrastructure. The use of the railway power supplies to charge electric vehicle batteries could facilitate the deployment of charging infrastructure in cities. It would reduce the cost because of the use of an existing installation. Furthermore, electric vehicles can use braking energy from trains that was previously wasted in rheostats. This paper presents the results of a collaboration between research teams from University of Rome Sapienza and Comillas Pontifical University. In this work, two real European cases are studied: an Italian metro line and a Spanish metro line. The energy performance of these metro lines and their capacity to charge electric vehicles have been studied by means of detailed simulation tools. Their results have shown that the use of regenerated energy is 98% for short interval of trains in both cases. However, the use of regenerated energy decreases as the train intervals grow. In a daily operation, an important amount of regenerated energy is wasted in the Italian and Spanish case. Using this energy, a significant number of electric vehicles could be charged every day.
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Vemulapati, Venkatasupura, Yerram N. Vijaykumar, and Nagalamadaka Visali. "Performance enhancement of a high-speed railway supply system with multi module converter: a laboratory prototype model for Indian railways." Indonesian Journal of Electrical Engineering and Computer Science 25, no. 2 (February 1, 2022): 680. http://dx.doi.org/10.11591/ijeecs.v25.i2.pp680-689.
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The present Indian traction supply system’s complications (neutral sections of the catenary line and issues of power quality) restrict the growth of railway transportation, particularly high-speed rail networks that are fast growing globally. The neutral sections (NS) results in loss of speed, momentum and mechanical failures that are all threatening the fast and stable operation of trains and systems. In the meantime, issues with the power quality such as the negative sequence currents (NSC), the reactive power and harmonics may create problems on the three phase grid side that cannot be overlooked. To address these two issues concurrently, a new traction power supply system is designed in this paper. The proposal will also analyses the theory of operation, build the mathematical model and develop the control system for back to back converters. Small scale prototype is also made for validation of simulation results. The results shows that it can fulfil the practical requirements. The experimental results shows that the overall system is practically more appropriate for the high speed railway.
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Satava, Richard M., and Shaun B. Jones. "Virtual Environments for Medical Training and Education." Presence: Teleoperators and Virtual Environments 6, no. 2 (April 1997): 139–46. http://dx.doi.org/10.1162/pres.1997.6.2.139.
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There are a number of modalities for implementing Virtual Environments (VE) for medical training and simulation. Integrating them for a seamless transition from one to another presents the next challenge. The three applications of (1) individual anatomic education and training, (2) medical crisis planning and training, and (3) medical virtual prototyping have been integrated into a single program approach by the military for battlefield trauma care. With this model as a template, the power of VE for the many different aspects of medical education can be explored and exploited.
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Huang, Xinxing, Yihua Yao, Qinfen Lu, Xiaoyan Huang, and Youtong Fang. "Control simulation of PMSM traction system of high speed train when passing neutral section." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 35, no. 2 (March 7, 2016): 782–95. http://dx.doi.org/10.1108/compel-12-2015-0445.
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Purpose – In electric system of high-speed trains, neutral sections are set to balance the three-phase load. When passing neutral sections, the train should detach from the power supply for a short time. To permanent magnet synchronous motors (PMSMs) traction system, the voltage of DC link will increase quickly due to the back-EMF of PMSM during this time. Although the energy consumption braking method can be adopted to consume the feedback energy. It not only wastes energy, but also causes more speed drop of the train. The paper aims to discuss these issues. Design/methodology/approach – In order to get better performance when the train is under passing neutral section condition, a suitable control method is proposed, in which the torque command is set to zero and d-axis current order remains unchanged during passing neutral section. Based on a co-simulation model, the influences of this method on the PMSMs traction system are compared with that of traditional method, which is used in induction motors traction system. This model combines both control strategy and finite element model of motor, which can take the effects of magnetic saturation and power loss into consideration. Findings – In PMSMs traction system, PMSMs work as generators during neutral section, and charge to DC bus, which may cause over-voltage damage. Moreover, there would be strong torque shock at the moment of power cut-off. It is finally found that, with the suitable control method, the high-speed train can pass the neutral section with less speed drop, less torque shock and little DC link voltage rise. Originality/value – The control method proposed in this paper is easier to achieve and gets a better performance of PMSMs traction system in high-speed train compared with the traditional method. Furthermore, the co-simulation model is much closer to reality than the analytical model.
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Bai, Na, Liang Wang, Yaohua Xu, and Yi Wang. "Design of a Digital Baseband Processor for UHF Tags." Electronics 10, no. 17 (August 26, 2021): 2060. http://dx.doi.org/10.3390/electronics10172060.
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In this paper, we present a new digital baseband processor for UHF tags. It is a low-power and low-voltage digital circuit and adopts the Chinese military standard protocol GJB7377.1. The processor receives data or commands from the RF front-end and carries out various functions, such as receiving and writing data to memory, reading and sending memory data to the RF front-end and killing tags. The processor consists of thirteen main sub-modules: TPP decoding, clock management, random number generator, power management, memory controller, cyclic redundancy check, FM0 encoding, input data processing, output data processing, command detection module, initialization module, state machine module and controller. We use ModelSim for the TPP decoding simulation and communication simulation between tag and reader, and the simulation results meet the design requirements. The processor can be applied to UHF tags and has been taped out using a TSMC 0.18 um CMOS process.
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Ai, Yibo, Haonan Ma, Xu Qu, Yuhan Qian, Yue Liu, and Weidong Zhang. "The Cross-Scale Life Prediction for the High-Speed Train Gearbox Shell Based on the Three-Interval Method." Scientific Programming 2022 (March 3, 2022): 1–10. http://dx.doi.org/10.1155/2022/6439229.
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The gearbox shell is a key component of class A of high-speed trains. In engineering applications, the fatigue life prediction of the gearbox shell is a critical issue to be addressed. It is not feasible to obtain fatigue life results for the gearbox shell experimentally because of its long design life, lack of actual failure data, complex structure, high test cost, and material dispersion. Therefore, the cross-scale method was introduced to accurately predict the fatigue life of the gearbox shell. In this study, the entire gearbox shell is divided into two scales of “material structure.” Firstly, the S-N curve is plotted within the material layer, based on the data from the rotating bending fatigue test. Secondly, the finite element model of the gearbox shell is established within the structural layer via the simulation platform. The characteristics and random vibration of the established model are analyzed and presented. Additionally, the first ten-order frequency of modal analysis and power spectral density responses of the gearbox are obtained. The fatigue life of the gearbox shell and the safe running distance of the train are calculated by using the three-interval method and the linear cumulative damage rule, respectively, by combining the fatigue analysis from the material layer with the simulation analysis from the structure layer. Finally, to illustrate the application of the proposed method, a group of small-scale test examples is provided. The proposed method can be used in fatigue life prediction more effectively than the single finite element simulation method.
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Peterson, Christopher J., Douglas L. Van Bossuyt, Ronald E. Giachetti, and Giovanna Oriti. "Analyzing Mission Impact of Military Installations Microgrid for Resilience." Systems 9, no. 3 (September 15, 2021): 69. http://dx.doi.org/10.3390/systems9030069.
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This article develops a method to model, analyze, and design military microgrids with the objective to improve their resilience in the face of disconnections from the larger electrical grid. Military microgrids provide power to installation and base facilities to enable base mission objective accomplishments that are related to national security. Previous research, tools, and methods for microgrid design and assessment do not adequately address resilience in terms of accomplishing mission objectives and instead primarily focus on economic outcomes. This article proposes a novel metric to quantify microgrid resilience in terms of its ability to minimize the impact of power disruption on missions supported by the microgrid. The metric is used in a novel design method to ensure an islanded military microgrid can continue operations while disconnected for a two-week duration. Our model examines the ability to continue mission operations subject to various microgrid disruptions as well as equipment reliability.
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Rodič, Miran, Miro Milanovič, and Mitja Truntič. "Digital Control of an Interleaving Operated Buck-Boost Synchronous Converter Used in a Low-Cost Testing System for an Automotive Powertrain." Energies 11, no. 9 (August 30, 2018): 2290. http://dx.doi.org/10.3390/en11092290.
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Based on the standardization in the automotive industry, systems require extensive testing, which represents significant costs regarding personnel and equipment. The testing systems must be built in such a way that a bidirectional power flow is possible between the power source and the tested system. Additionally, applied testing systems have to possess high disturbance immunity. Classical current programmed control performed using an analogue approach suffers from low disturbance rejection during switching operation. The digital control of DC–DC converter can solve this problem with the use of digital integration in a measurement chain. The integrals of values are obtained by using a Voltage Control Oscillator (VCO) and appropriate counters. Digital control of an interleaving operated bidirectional buck-boost synchronous converter can be applied in the testing system for automotive powertrains. The voltage and current measurements with the application of an integral-measurement principle act as low-pass filters, which remove the disturbances from the measured values. The digital implementation of a compensation ramp (current mode control) and method for choice of control parameters are described. All the tasks for measurements, as well as current and voltage control, were implemented within the FPGA (Field Programmable Gate Array). The presented converter can operate as a close to ideal voltage or current source, and satisfies the requirements of testing electric motor drive-trains with bidirectional DC–AC converters that are applied in automotive applications. The proposed system was verified by simulation
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Yevseyev, K. B. "Mathematical model of the movement of a tracked train for off-road container transportation." Traktory i sel hozmashiny 88, no. 5 (October 15, 2021): 18–29. http://dx.doi.org/10.31992/0321-4443-2021-5-18-29.
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To determine the indicators of the mobility properties of unmanned tracked trains and the formation of traffic control laws, it is advisable to use mathematical simulation. On the example of a tracked semitrailer train, a mathematical model is being developed. It consists of a large number of rigid bodies connected by kinematic and power connections; therefore, it is proposed to use software systems that make it possible to synthesize a system of equations for the dynamics of a tracked train in an automated mode. The article discusses general approaches to the formation of such systems of equations in modern software packages for automated analysis of the dynamics of body systems. There are given a structural diagram of the developed mathematical model of a tracked train and a description of its main structural elements (blocks), which are responsible for the operation of various systems: a power plant, transmission and running system.
The features of the interaction of active sections of a caterpillar propeller with a low-deformable support base of the dense soil type are considered. On the example of the maneuver turn with a given radius, an imitation mathematical modeling of the movement of a caterpillar train was carried out, and on the basis of an analysis of the results obtained, the operability of the developed mathematical model was confirmed. The developed mathematical model of the movement of a tracked semitrailer train makes it possible to study its movement in space, taking into account the mutual influence of the tractor and the semitrailer, taking into account the interaction of the active sections of the tracked propeller with the sup-port base and taking into account the modeling of the working processes of its systems.
Based on the study, it can be concluded that the use of the method of computer modeling of the dynamics of body systems is an effective tool for predicting the performance indicators of tracked trains, determining the laws of traffic control, and also for assessing energy efficiency when performing virtual maneuvers. The developed mathematical model of the dynamics of a tracked train allows a wide range of studies to assess the mobility of tracked trains of various design and layout.
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Tran, Tien, and Dung T. Huynh. "Symmetric Connectivity in Wireless Sensor Networks with π/3 Directional Antennas." International Journal of Foundations of Computer Science 33, no. 02 (February 2022): 119–40. http://dx.doi.org/10.1142/s0129054122500022.
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Directional Wireless Sensor Networks (DWSNs) have been a very active research topic as they have a wide range of applications in both military and civilian areas. In this paper, we study the Antenna Orientation (AO) and Antenna Orientation and Power Assignment (AOPA) problems, two important issues in DWSNs. In the AO problem, given a set [Formula: see text] of sensors equipped with directional antennas with beam-width [Formula: see text], the objective is to determine an orientation of the antennas and a minimum transmission range [Formula: see text] such that the induced symmetric communication graph is connected. We prove that the AO problem is NP-hard. We then extend our proof technique and show that the AOPA problem for DWSNs equipped with [Formula: see text] directional antennas is also NP-hard where we have to determine an orientation of the antennas as well as a power assignment [Formula: see text] to the nodes such that the resulting symmetric communication graph is connected, and (2) [Formula: see text] is minimized ([Formula: see text] is the distance-power gradient, [Formula: see text]). We propose an [Formula: see text] heuristic algorithm and demonstrate by simulation that our method is better than the Ice-cream method.
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Qiao, Yuan, Xucheng Duan, Kaisheng Huang, Yizhou Song, and Jianan Qian. "Scavenging Ports’ Optimal Design of a Two-Stroke Small Aeroengine Based on the Benson/Bradham Model." Energies 11, no. 10 (October 12, 2018): 2739. http://dx.doi.org/10.3390/en11102739.
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The two-stroke engine is a common power source for small and medium-sized unmanned aerial vehicles (UAV), which has wide civil and military applications. To improve the engine performance, we chose a prototype two-stroke small areoengine, and optimized the geometric parameters of the scavenging ports by performing one-dimensional (1D) and three-dimensional (3D) computational fluid dynamics (CFD) coupling simulations. The prototype engine is tested on a dynamometer to measure in-cylinder pressure curves, as a reference for subsequent simulations. A GT Power simulation model is established and validated against experimental data to provide initial conditions and boundary conditions for the subsequent AVL FIRE simulations. Four parameters are considered as optimal design factors in this research: Tilt angle of the central scavenging port, tilt angle of lateral scavenging ports, slip angle of lateral scavenging ports, and width ratio of the central scavenging port. An evaluation objective function based on the Benson/Bradham model is selected as the optimization goal. Two different operating conditions, including the take-off and cruise of the UAV are considered. The results include: (1) Orthogonal experiments are analyzed, and the significance of parameters are discussed; (2) the best factors combination is concluded, followed by simulation verification; (3) results before and after optimization are compared in details, including specific scavenging indexes (delivery ratio, trapping efficiency, scavenging efficiency, etc.), conventional performance indicators, and the sectional views of gas composition distribution inside the cylinder.
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Doru, Coșofreț. "Reducing GHG Emissions at Military Vessels." Scientific Bulletin of Naval Academy XXIII, no. 2 (December 15, 2020): 93–97. http://dx.doi.org/10.21279/1454-864x-20-i2-012.
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The shipping industry is responsible for 3% of global greenhouse gas (GHG) emissions, emissions mainly resulting from the combustion of fuels in naval energy aggregates. The current requirements for a 50% reduction in GHG emissions by 2050 represent a challenge for maritime transport, as there is no effective solution to reduce this emissions from ships. Thus, the current problem is represented by insufficient methods to reduce CO2 emissions on board ships, in particular for ships which are in service for more than 10 years, which are the most affected by these environmental requirements, since their design did not take into account the reduction of ecological parameters. In this context, even if military vessels are not subject to IMO GHG emission reduction requirements, they must be aligned with global emissions reduction efforts. This article presents actually operational and technological solutions to reduce CO2 emissions that can be deployed on board military vessels, until other technical solutions or power supply solutions for non-polluting renewable energy aggregates are identified.
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Huhtinen, Aki-Mauri. "From Military Threats to Everyday Fear." International Journal of Cyber Warfare and Terrorism 2, no. 2 (April 2012): 1–10. http://dx.doi.org/10.4018/ijcwt.2012040101.
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The history of combat is primarily the history of radically changing fields of perception. In other words, war consists not so much of scoring territorial, economic or other material victories but of appropriating the immateriality of perceptual field. The function of the eye has become the function of the weapons (Virilio, 1989; 2009). To understand information age warfare we have to understand the concept of representation as a part of our process of violence. The idea of information warfare or an information operation is based on the process where the physical target is no longer destroyed with the kinetic systems, but the process where the non-kinetic systems, like information, scan the symbols-semiotics networks. We like to consume safety different kind of fears. The feeling of the safety fear based on the virtual boundaries, which are set in the movement from “principle” to “practice, in other words in the actualization of the cyber-form. The power of fear is not a form. It is not abstract. It is the movement of form into the content outside of which it is a void of potential function, of the abstract into the particular it cannot be or do without. (see Massumi 1993, 20-21) Today, particularly the advanced mobile technology, the Internet and the entertainment industry immensely exploit the experiences from different wars and conflicts for example as ideas of computer games. In return the military industrial complex represents its own language for example in the concept of information operations with the help of applications particularly rising from the entertainment industry. The roles of Hector and Achilles, the teachings of Jomini and Clausewitz have an effect in the background of games and gaming. Opposite to Clauseiwitz’s thinking, Jomini took the view that the amount of force deployed should be kept to the minimum in order to lower casualties and that war was a science, not an art. The most central genres in gaming are ”strategy”, ”adventure”, ”shooter”, ”sports”, ”simulation”, ”music”, ”role playing” and ”puzzle”. All of these are related to warfare one way or another. Another interesting fact is that in the 1950’s the first computer games were mathematic strategy based games that that had been developed in universities (Czosseck, 2009; Peltoniemi, 2009).
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Orgeira-Crespo, Pedro, Carlos Ulloa, José M. Núñez, and José A. Pérez. "Development of a Transient Model of a Lightweight, Portable and Flexible Air-Based PV-T Module for UAV Shelter Hangars." Energies 13, no. 11 (June 5, 2020): 2889. http://dx.doi.org/10.3390/en13112889.
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This research paper introduces a mathematical model to predict the performance of photovoltaic–thermal systems (PV-T), based on a thin layer flexible panel and an air pipe, by using the Trnsys® software tool to simulate energetic systems. The main advantage of these types of panels is their easy portability, making them ideal to address thermal needs in several scenarios. In the military field, there is an important concern about the use of sustainable energy; for instance, cooling facilities for infantry tents used in their deployments. In this research, a PV-T panel to cover electrical power needs for an infantry’s hangar unmanned air vehicle (UAV) is introduced. The proposed thermal model, based on the novelty of inertial mass (lump) as an approach to real panel behavior, has been validated through the comparison between Trnsys’ model simulation data, a real weather station, and data obtained in a test bed. Genopt’s simulation software is used to fit the model, allowing for the prediction of heat transmission coefficient values. The good match between simulated and experimental data makes the proposed model suitable for the photovoltaic–thermal prediction of panel behavior.
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Safronov, Oleksandr. "AN APPROACH TO EVALUATION OF FREIGHT TRAINS BRAKING EFFICIENCY BY THE RESULTS OF EXPERIMENTAL STUDIES IN COMPLIANCE WITH HOST 34434-2018 REQUIREMENTS." Railbound Rolling Stock, no. 23 (December 16, 2021): 140–63. http://dx.doi.org/10.47675/2304-6309-2021-23-140-163.
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The approach of experimental study of the freight trains braking efficiency using computer simulation based on the implementation of the simulation model in the form of a differential equation of the wagon motion during braking, is proposed. The methodology of experimental studies is based on universal formulas for power-law dependences of braking parameters. The braking efficiency is evaluated by the use of computer software packages written in VBA (Visual Basic for Application) in Excel. The software package al-lows you to increase the automation of testing, the accuracy of calculations, to reduce the time for testing, and also minimize the number of errors caused by the human factor. The presented methodology significantly extends the number of parameters of the braking process used to analyze the braking efficiency of a freight train based on the results of running braking tests: actual values of braking coefficients; braking distances of a freight train not only on the site, but also on normalized gradient descents for a given number of wagons in the train, taking into account the increase in the braking force along the wagons in the train formation; actual values of wheel and rail adhesion coefficients during braking; the deceleration of the freight wagon and the train during braking, as well as the braking time. Examples of computational and experimental studies of a freight train with tread brake are given. A comparative analysis of experimental and computational studies demonstrates sufficiently satisfactory matching of their results. Key words: freight train, braking distance, braking speed, braking coefficient, increase in braking force, mathematical model, trend line, braking wave.
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Chen, Yong, Kaiyu Niu, and Wei Zhang. "Handover Optimization Algorithm Based on T2RFS-FNN." Computational Intelligence and Neuroscience 2022 (December 14, 2022): 1–10. http://dx.doi.org/10.1155/2022/6293192.
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As a key technology for highly reliable communication in the fifth generation mobile communication for railway (5G-R) high-speed railway wireless communication system, once the handover fails, it will pose a serious risk to the safe operation of high-speed railway. As the speed of high-speed trains continues to increase, the handover will become more frequent, and how to improve the success rate of the handover is a key problem that needs to be solved. In this paper, we proposed an optimization algorithm based on the interval type 2 feature selection recurrent fuzzy neural network (T2RFS-FNN), which is a recurrent fuzzy neural network with interval type 2 feature selection, to address the problem of fixed hysteresis threshold and single consideration for the handover algorithm between the control plane and the user plane of the high-speed railway under 5G-R. The algorithm integrates reference signal receiving power (RSRP). Reference signal receiving quality (RSRQ) and throughput to optimise the hysteresis threshold. First, a feedforward neural network structure is designed to implement fuzzy logic inference, and an interval type-two Gaussian subordination function is used to improve the nonlinear expressiveness of the model. Then, a feature selection layer is added to determine the output of the affiliation function, which completes the optimization of the hysteresis threshold and overcomes the drawback of the fixed hysteresis threshold of the handover algorithm. Finally, simulation analysis of the control-plane and user-plane handover algorithms is carried out separately. The results show that the proposed method can effectively improve the success rate and reduce the ping-pong handover rate compared to the comparison algorithms. The results provide a theoretical reference for the speedup of high-speed railway trains and the evolution of the global system for mobile communications for railway (GSM-R) to 5G-R.
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Ajayi-Obe, Akinola A., Mohamed A. Khan, and Paul S. Barendse. "Techno-economic evaluation of five-level nested neutral point clamped converter topology for transformer-less connection of high-power wind energy conversion systems." Journal of Energy in Southern Africa 30, no. 3 (September 18, 2019): 33–43. http://dx.doi.org/10.17159/2413-3051/2019/v30i3a5691.
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Developers and operators are interested in improving the reliability and reducing the associated costs of wind power plants (WPPs) because of the continuous increase in the power capacity of wind energy conversion systems (WECSs) and the increasing development of WPPs. The electrical subsystem of the WPP experiences the highest failure rate and constitutes a significant proportion of its total cost. Reliability of the WECS can be increased and its cost reduced by eliminating the wind turbine transformer from the electrical subsystem. This study gives a techno-economic evaluation of a five-level nested neutral point clamped (NNPC) converter topology for transformer-less connection of high- power WECSs. The approach entailed the calculation of reliability of five-level NNPC converter topology deployed in the grid-side of a WECSs. This method presents a mathematical formula for deriving the reliability of a five-level NNPC converter topology by using the reliability block diagram and reliability estimation-based models in the military handbook (MIL-HDBK-217F). The cost analysis model shows that the total cost of the five-level diode clamped converter topology was higher than the five-level NNPC converter topology. The study could be extended by carrying out accurate modelling of the mission profile of the presented converter by using multi-domain simulation technique.
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Sedak, Miloš, and Božidar Rosić. "Multi-Objective Optimization of Planetary Gearbox with Adaptive Hybrid Particle Swarm Differential Evolution Algorithm." Applied Sciences 11, no. 3 (January 25, 2021): 1107. http://dx.doi.org/10.3390/app11031107.
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This paper considers the problem of constrained multi-objective non-linear optimization of planetary gearbox based on hybrid metaheuristic algorithm. Optimal design of planetary gear trains requires simultaneous minimization of multiple conflicting objectives, such as gearbox volume, center distance, contact ratio, power loss, etc. In this regard, the theoretical formulation and numerical procedure for the calculation of the planetary gearbox power efficiency has been developed. To successfully solve the stated constrained multi-objective optimization problem, in this paper a hybrid algorithm between particle swarm optimization and differential evolution algorithms has been proposed and applied to considered problem. Here, the mutation operators from the differential evolution algorithm have been incorporated into the velocity update equation of the particle swarm optimization algorithm, with the adaptive population spacing parameter employed to select the appropriate mutation operator for the current optimization condition. It has been shown that the proposed algorithm successfully obtains the solutions of the non-convex Pareto set, and reveals key insights in reducing the weight, improving efficiency and preventing premature failure of gears. Compared to other well-known algorithms, the numerical simulation results indicate that the proposed algorithm shows improved optimization performance in terms of the quality of the obtained Pareto solutions.
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Lluesma-Rodríguez, Federico, Temoatzin González, and Sergio Hoyas. "CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method." Applied Sciences 11, no. 9 (April 27, 2021): 3934. http://dx.doi.org/10.3390/app11093934.
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One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.
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I., Ciocioi. "Electromagnetic compatibility testing procedures of naval radars for installation on board military ships." Scientific Bulletin of Naval Academy XXII, no. 2 (December 15, 2019): 325–36. http://dx.doi.org/10.21279/1454-864x-19-i2-039.
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The electromagnetic environment on board a military ship represents a delimited space in which there are disruptive sources and disturbance receptors. It is defined by the maximum disruptive levels in each point of the specified space. This electromagnetic environment is extremely complex because it is heavily dependent on: the density of the equipment on board, characteristics of installed equipment (frequency bands, power, modulation types, etc.), the design of the ship so that the electromagnetic field intensity within it is as small as possible. In order to install commercial radars on board military ships it is important to determine whether they can be installed in the Electromagnetic environment on board ships. An analysis of the standards of electromagnetic compatibility applied to them may determine whether commercial radars can be installed on board military ships.
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Chen, Xiao, Sun, Wang, Jin, and Feng. "Energy-Efficient Driving Strategies for Multi-Train by Optimization and Update Speed Profiles Considering Transmission Losses of Regenerative Energy." Energies 12, no. 18 (September 18, 2019): 3573. http://dx.doi.org/10.3390/en12183573.
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This paper aims at minimizing the total energy consumption of multi-train in an urban rail transit (URT) system by optimizing and updating speed profiles considering regenerative braking power losses on the catenary. To make full use of regenerative energy and decrease traction energy consumption simultaneously, energy-efficient control strategies of multi-train and a corresponding solution method are proposed. The running process of multi-train is divided into several sections based on passenger stations. Speed profiles of each train in each section are collaboratively optimized by searching only one transition point from the optimized single-train speed profile, which can be worked out by searching the switching point of coasting mode, and the optimized multi-train speed profiles are updated based on departure orders of trains. Moreover, an electrical network model is established to analyze energy flows, and dynamic losses of recovered regenerative energy on the line can be calculated. Besides, an improved optimization strategy of multi-train, which contains seven motion phases, is presented for steep slope. Simulation results based on Guangzhou Metro Line 8 verify the effectiveness of the proposed methods. Total energy consumption of optimized multi-train can be decreased by 6.95% compared with multi-train adopted single-train optimal control strategy, and the energy-saving rate of 21.08% can be achieved compared with the measured data by drivers under same trip time. In addition, the influence of departure interval on total energy consumption is analyzed and the optimal departure interval can be obtained.
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Chaiel, Hussain K., Zainab S. M. Al-Husseini, and Khaldun I. Arif. "Energy Enhancement Techniques for Structure-Free Wireless Sensor Network with Encrypted Data." International Journal of Sensors, Wireless Communications and Control 10, no. 3 (November 2, 2020): 402–12. http://dx.doi.org/10.2174/2210327909666190627155223.
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Background: Nowadays, in military and border surveillance application, the WSNs become an effective part of the command and control system. This requires an efficient type of cryptography. Due to small size requirement, elliptic curve becomes the most suitable for such purpose. Objective: The encryption operation, in turn, increases the power required to transmit data through the network. The aim of this work is to reduce such power. Methods: This work suggests three methods to reduce the needed power. The first method is based on spread spectrum technology, which reduces the total number of levels in the network. The second method deals with algorithm used to choose the sensing node, while the third method suggests a cost function related directly to the available energy. Results: Computer simulation tests show a reduction in the required energy by 40% when we apply the first method, while the second and third methods together reduce the energy by 12% of the total value of the whole network. Conclusion: The energy required to transmit encrypted data can be reduced with the aid of routing algorithms. These algorithm increase the coverage radius of the node transmission.
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Vijayan, Sneha, and Nagarajan Munusamy. "Deterministic Centroid Localization for Improving Energy Efficiency in Wireless Sensor Networks." Cybernetics and Information Technologies 22, no. 1 (March 1, 2022): 24–39. http://dx.doi.org/10.2478/cait-2022-0002.
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Abstract Wireless sensor networks are an enthralling field of study with numerous applications. A Wireless Sensor Network (WSN) is used to monitor real-time scenarios such as weather, temperature, humidity, and military surveillance. A WSN is composed of several sensor nodes that are responsible for sensing, aggregating, and transmitting data in the system, in which it has been deployed. These sensors are powered by small batteries because they are small. Managing power consumption and extending network life is a common challenge in WSNs. Data transmission is a critical process in a WSN that consumes the majority of the network’s resources. Since the cluster heads in the network are in charge of data transmission, they require more energy. We need to know where these CHs are deployed in order to calculate how much energy they use. The deployment of a WSN can be either static or random. Although most researchers focus on random deployment, this paper applies the proposed Deterministic Centroid algorithm for static deployment. Based on the coverage of the deployment area, this algorithm places the sensors in a predetermined location. The simulation results show how this algorithm generates balanced clusters, improves coverage, and saves energy.
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Kannimuthu, Prathapchandran, and Janani Thangamuthu. "Decision Tree Trust (DTTrust)-Based Authentication Mechanism to Secure RPL Routing Protocol on Internet of Battlefield Thing (IoBT)." International Journal of Business Data Communications and Networking 17, no. 1 (January 2021): 1–23. http://dx.doi.org/10.4018/ijbdcn.2021010101.
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Providing security on the internet of battlefield things (IoBT) is a crucial task because of various factors such as heterogeneous, dynamic, and resource-constrained devices. Besides, authentication is essential, and it ensures the initial level of security in the network; therefore, ensuring authentication of various interconnected battlefield sensors/devices is the primary attention for the military applications. With this idea in mind, in this paper, a trust model that uses a decision tree to identify and isolate the misbehaving battlefield thing in the IoBT environment is proposed. The decision tree is the predictive modeling and machine learning technique that provides an accurate estimation for selecting authenticated nodes in IoBT by addressing the rank attack by the way security of IoBT environment can be ensured. The mathematical model shows the applicability of the proposed work. The simulation results show the proposed model is better than the existing routing protocol for low power lossy network (RPL) and the protocol which is similar to the proposed one.
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Daanoune, Ikram, Abdennaceur Baghdad, and Abdelhakim Ballouk. "Improved LEACH protocol for increasing the lifetime of WSNs." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 4 (August 1, 2021): 3106. http://dx.doi.org/10.11591/ijece.v11i4.pp3106-3113.
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<p>Recently, wireless sensor network (WSN) is taking a high place in several applications: military, industry, and environment. The importance of WSNs in current applications makes the WSNs the most developed technology at the research level and especially in the field of communication and computing. However, WSN’s performance deals with a number of challenges. Energy consumption is the most considerable for many researchers because nodes use energy to collect, treat, and send data, but they have restricted energy. For this reason, numerous efficient energy routing protocols have been developed to save the consumption of power. Low energy adaptive clustering hierarchy (LEACH) is considered as the most attractive one in WSNs. In the present document, we evaluate the LEACH approach effectiveness in the cluster-head (CH) choosing and in data transmission, then we propose an enhanced protocol. The proposed algorithm aims to improve energy consumption and prolong the lifetime of WSN through selecting CHs depending on the remaining power, balancing the number of nodes in clusters, determining abandoned nodes in order to send their data to the sink. Then CHs choose the optimal path to achieve the sink. Simulation results exhibit that the enhanced method can decrease the consumption of energy and prolong the life-cycle of the network.</p>
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Psotka, Joseph. "Advancing the Mind/Machine Interface: Qualitative Simulations, Hypertext, and Natural Language Processing." Proceedings of the Human Factors Society Annual Meeting 33, no. 19 (October 1989): 1334–38. http://dx.doi.org/10.1177/154193128903301921.
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Advanced technologies, including artificial intelligence (Al), hypertext, and natural language processing (NLP), are transforming the Mind/Machine Interface. This presentation focuses on two large development projects underway that use these technologies in unique ways. Their use is guided by the three natural means of communication between people: saying, coaching, and showing; as metaphors for using advanced technology interfaces. The two projects are aimed at developing job and training aids for the Army. The most complete example is the Maintenance Aid Computer for HAWK–Intelligent Institutional Instructor (MACH-III). This is the largest and most successful implementation of an ITS to date (Psotka, Massey, and Mutter, 1988). MACH-III was developed by Bolt, Beranek, and Newman (BBN), to provide training in organizational maintenance of the main radar of the HAWK air defense guided missile system. Its core is a huge qualitative simulation of the radar. The complexity of the simulation and the troubleshooting problem space demand a unique hypertext interface, whose structure and function are only beginning to be understood. Some preliminary evaluation results from the U.S. Army Air Defense Artillery School (USAADASCH), Ft. Bliss, Texas are beginning to show its effectiveness. The other project, Building Robust Dual Grammar Exercisers (BRIDGE), will begin to explore the architextual structure of hypertext systems within the context of advanced technologies for military machine translation and military foreign language training. From this perspective, hypertext is a bridging technology that links the existing strengths of qualitative simulations with the future power of natural language processing.
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Abraham, Benjamin. "Video Game Visions of Climate Futures." Games and Culture 13, no. 1 (September 21, 2015): 71–91. http://dx.doi.org/10.1177/1555412015603844.
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This article discusses ARMA 3 (2013), a military simulation game from Bohemia Interactive. Through the prominent placement of visual representations of renewable power generation the game offers a compelling vision of the future in which current resistance to low-carbon and renewable economies have been overcome. I argue that the potential of this vision to challenge cultural futures and imaginaries is dependent on its presentation aesthetically and not, as is often suggested, on game mechanics operating in a “persuasive” mode. Instead, I argue that ARMA 3’s aesthetic vision can skirt around the ideological resistances players may have against accepting more didactic modes of engagement with the highly charged and ideologically contested reality of anthropogenic climate change. In this way, I suggest ARMA 3 offers a compelling challenge to current theories about games ability to persuade or influence players.
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FREEMAN, WALTER J., GYöNGYI GAÁL, and REBECKA JORSTEN. "A NEUROBIOLOGICAL THEORY OF MEANING IN PERCEPTION PART III: MULTIPLE CORTICAL AREAS SYNCHRONIZE WITHOUT LOSS OF LOCAL AUTONOMY." International Journal of Bifurcation and Chaos 13, no. 10 (October 2003): 2845–56. http://dx.doi.org/10.1142/s0218127403008260.
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Information transfer and integration among functionally distinct areas of cerebral cortex of oscillatory activity require some degree of phase synchrony of the trains of action potentials that carry the information prior to the integration. However, propagation delays are obligatory. Delays vary with the lengths and conduction velocities of the axons carrying the information, causing phase dispersion. In order to determine how synchrony is achieved despite dispersion, we recorded EEG signals from multiple electrode arrays on five cortical areas in cats and rabbits, that had been trained to discriminate visual or auditory conditioned stimuli. Analysis by time-lagged correlation, multiple correlation and PCA, showed that maximal correlation was at zero lag and averaged 0.7, indicating that 50% of the power in the gamma range among the five areas was at zero lag irrespective of phase or frequency. There were no stimulus-related episodes of transiently increased phase locking among the areas, nor EEG "bursts" of transiently increased amplitude above the sustained level of synchrony. Three operations were identified to account for the sustained correlation. Cortices broadcast their outputs over divergent–convergent axonal pathways that performed spatial ensemble averaging; synaptic interactions between excitatory and inhibitory neurons in cortex operated as band pass filters for gamma; and signal coarse-graining by pulse frequency modulation at trigger zones enhanced correlation. The conclusion is that these three operations enable continuous linkage of multiple cortical areas by activity in the gamma range, providing the basis for coordinated cortical output to other parts of the brain, despite varying axonal conduction delays, something like the back plane of a main frame computer.
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V, Dobref. "Total Harmonic Distortion Factor Evaluation in Shipboard Electrical Networks." Scientific Bulletin of Naval Academy XXI, no. 2 (December 15, 2018): 61–67. http://dx.doi.org/10.21279/1454-864x-18-i2-006.
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Electric propulsion systems for modern civil and military ships, as well as the growing number of electric consumers on board, are a topical issue in terms of onboard electric power quality. In this respect, a growing number of high power static converters are used, which inevitably leads to the appearance, in the electricity distribution network, of voltage and current harmonics with very high weights. Through this work, the authors made a study of these harmonics for two classical cases encountered aboard a ship, namely a nonlinear consumer and a consumer powered by a static six-pulse converter. Also, the highlight of these harmonics has been made in both shore and onboard power supplies. As a result of these measurements, some conclusions were drawn regarding the analyzed situations.
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Pérez, J. L., L. H. Benítez, M. Oliver, and H. Climent. "Survey of aircraft structural dynamics non-linear problems and some recent solutions." Aeronautical Journal 115, no. 1173 (November 2011): 653–68. http://dx.doi.org/10.1017/s0001924000006382.
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Abstract Structural dynamics is a key discipline in aircraft design and certification. The realm of structural dynamics includes problems in which structure flexibility is important, such as dynamic loads (landing, taxi, gust, turbulence...), but it also includes other areas like environmental vibration or impacts technology. This is closely related with its sister discipline Aeroelasticity. Linearity has been the cornerstone assumption in aircraft design engineering solutions. In the past, linearity allowed to solve many structural dynamics problems that otherwise would have been unaffordable. Nowadays, the necessity of highly optimised structures, combined to an increase of computer power, has made this assumption to be reconsidered. This paper presents a wide survey on non-linear topics in structural dynamics and the way they have been solved at EADS-CASA (Airbus military) in the past 25 years. Although the paper has been mainly focused on numerical simulation using the Finite Element Method technique, component tests and full aircraft tests are also presented.
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D, Ravi Tej, Sri Kavya Ch K, and Sarat K. Kotamraju. "An improved peak side lobe reduction method for linear array antenna for military applications." International Journal of Intelligent Computing and Cybernetics 14, no. 2 (March 4, 2021): 186–98. http://dx.doi.org/10.1108/ijicc-09-2020-0127.
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PurposeThe purpose of this paper is to improve energy efficiency and further reduction of side lobe level the algorithm proposed is firework algorithm. In this paper, roused by the eminent swarm conduct of firecrackers, a novel multitude insight calculation called fireworks algorithm (FA) is proposed for work enhancement. The FA is introduced and actualized by mimicking the blast procedure of firecrackers. In the FA, two blast (search) forms are utilized and systems for keeping decent variety of sparkles are likewise all around planned. To approve the presentation of the proposed FA, correlation tests were led on nine benchmark test capacities among the FA, the standard PSO (SPSO) and the clonal PSO (CPSO).Design/methodology/approachThe antenna arrays are used to improve the capacity and spectral efficiency of wireless communication system. The latest communication systems use the antenna array technology to improve the spectral efficiency, fill rate and the energy efficiency of the communication system can be enhanced. One of the most important properties of antenna array is beam pattern. A directional main lobe with low side lobe level (SLL) of the beam pattern will reduce the interference and enhance the quality of communication. The classical methods for reducing the side lobe level are differential evolution algorithm and PSO algorithm. In this paper, roused by the eminent swarm conduct of firecrackers, a novel multitude insight calculation called fireworks algorithm (FA) is proposed for work enhancement. The FA is introduced and actualized by mimicking the blast procedure of firecrackers. In the FA, two blast (search) forms are utilized and systems for keeping decent variety of sparkles are likewise all around planned. To approve the presentation of the proposed FA, correlation tests were led on nine benchmark test capacities among the FA, the standard PSO (SPSO) and the clonal PSO (CPSO). It is demonstrated that the FA plainly beats the SPSO and the CPSO in both enhancement exactness and combination speed. The results convey that the side lobe level is reduced to −34.78dB and fill rate is increased to 78.53.FindingsSamples including 16-element LAAs are conducted to verify the optimization performances of the SLL reductions. Simulation results show that the SLLs can be effectively reduced by FA. Moreover, compared with other benchmark algorithms, fireworks has a better performance in terms of the accuracy, the convergence rate and the stability.Research limitations/implicationsWith the use of algorithms radiation is prone to noise one way or other. Even with any optimizations we cannot expect radiation to be ideal. Power dissipation or electro magnetic interference is bound to happen, but the use of optimization algorithms tries to reduce them to the extent that is possible.Practical implications16-element linear antenna array is available with latest versions of Matlab.Social implicationsThe latest technologies and emerging developments in the field of communication and with exponential growth in users the capacity of communication system has bottlenecks. The antenna arrays are used to improve the capacity and spectral efficiency of wireless communication system. The latest communication systems use the antenna array technology which is to improve the spectral efficiency, fill rate and the energy efficiency of the communication system can be enhanced.Originality/valueBy using FA, the fill rate is increased to 78.53 and the side lobe level is reduced to 35dB, when compared with the bench mark algorithms.
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Edwards, Tom, Nicolas Foloppe, Sarah Anne Harris, and Geoff Wells. "The future of biomolecular simulation in the pharmaceutical industry: what we can learn from aerodynamics modelling and weather prediction. Part 1. understanding the physical and computational complexity of in silico drug design." Acta Crystallographica Section D Structural Biology 77, no. 11 (October 27, 2021): 1348–56. http://dx.doi.org/10.1107/s2059798321009712.
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The predictive power of simulation has become embedded in the infrastructure of modern economies. Computer-aided design is ubiquitous throughout industry. In aeronautical engineering, built infrastructure and materials manufacturing, simulations are routinely used to compute the performance of potential designs before construction. The ability to predict the behaviour of products is a driver of innovation by reducing the cost barrier to new designs, but also because radically novel ideas can be piloted with relatively little risk. Accurate weather forecasting is essential to guide domestic and military flight paths, and therefore the underpinning simulations are critical enough to have implications for national security. However, in the pharmaceutical and biotechnological industries, the application of computer simulations remains limited by the capabilities of the technology with respect to the complexity of molecular biology and human physiology. Over the last 30 years, molecular-modelling tools have gradually gained a degree of acceptance in the pharmaceutical industry. Drug discovery has begun to benefit from physics-based simulations. While such simulations have great potential for improved molecular design, much scepticism remains about their value. The motivations for such reservations in industry and areas where simulations show promise for efficiency gains in preclinical research are discussed. In this, the first of two complementary papers, the scientific and technical progress that needs to be made to improve the predictive power of biomolecular simulations, and how this might be achieved, is firstly discussed (Part 1). In Part 2, the status of computer simulations in pharma is contrasted with aerodynamics modelling and weather forecasting, and comments are made on the cultural changes needed for equivalent computational technologies to become integrated into life-science industries.
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Zhu, Junmin, Shuaibing Li, Yang Liu, and Haiying Dong. "A Hybrid Method for the Fault Diagnosis of Onboard Traction Transformers." Electronics 11, no. 5 (March 1, 2022): 762. http://dx.doi.org/10.3390/electronics11050762.
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As vital equipment in high-speed train power supply systems, the failure of onboard traction transformers affect the safe and stable operation of the trains. To diagnose faults in onboard traction transformers, this paper proposes a hybrid optimization method based on quickly and accurately using support vector machines (SVMs) as fault diagnosis systems for onboard traction transformers, which can accurately locate and analyze faults. Considering the limitations of traditional transformers for identifying faults, this study used kernel principal component analysis (KPCA) to analyze the feature quantity of dissolved gas analysis (DGA) data, electrical test data, and oil quality test data. The improved seagull optimization algorithm (ISOA) was used to optimize the SVM, and a Henon chaotic map was introduced to initialize the population. Combined with differential evolution (DE) based on the adaptive formula, the foraging formula of the seagull optimization algorithm (SOA) was improved to increase the diversity of the algorithm and enhance its ability to find the optimal parameters of SVM, which made the simulation results more accurate. Finally, the KPCA–ADESOA–SVM model was constructed and applied to fault diagnosis for the traction transformer. The example analysis compared the diagnosis results of the proposed diagnosis model with those of the traditional diagnosis model, showing further optimization of the feature quantity and improvements in the diagnosis accuracy. This proves that the proposed diagnosis model has high generalization performance and can effectively increase the fault diagnosis accuracy and speed of traction transformers.
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Parkhomenko, Larysa, Tetiana Butko, Viktor Prokhorov, Tetiana Kalashnikova, and Tetiana Golovko. "Building a model for planning rapid delivery of containers by rail under the conditions of intermodal transportation based on robust optimization." Eastern-European Journal of Enterprise Technologies 5, no. 3(119) (October 30, 2022): 6–16. http://dx.doi.org/10.15587/1729-4061.2022.265668.
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This paper considers the possibility of devising a technology of fast railroad communication for the transportation of containers between the port and customer enterprises in the course of intermodal transportation. The purpose of technology development is to reduce the share of the use of trucks on intermodal routes and thus solve a number of related environmental, transport, municipal, and economic problems. The devised technology is based on the principles of bringing the railroad as close as possible to the end points of the route, minimizing the number of intermediate modes of transport, and enabling the maximum speed of movement of containers by rail. For this purpose, the use of MetroCargo™ freight terminals and CargoSprinter modular trains is proposed. In the course of the study, the task to reliably plan the operation of the fleet of such trains for the delivery of containers between the port and enterprises under the conditions of "noisy" initial data was set and solved. To this end, the problem was formalized in the form of a model of mixed programming, based on the principles of robust optimization. To optimize the model taking into consideration the principles of robustness, a procedure was proposed that uses a two-circuit genetic algorithm. As a result of the simulation, it was found that the resulting plan was only 6.5 % inferior to the objective criterion of the plan, which was compiled without taking into consideration robustness. It was proved that the devised model makes it possible to build an operational plan for the delivery of containers by rail, which is close to optimal. At the same time, the plan is implemented even in the case of the most unfavorable set of circumstances in the form of delays, shifts in the time windows of the cargo fronts, etc., that is, under the actual conditions of the transport process
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Hu, Feng, Hongyan Qian, and Liangjun Liu. "A Random Label and Lightweight Hash-Based Security Authentication Mechanism for a UAV Swarm." Wireless Communications and Mobile Computing 2021 (June 28, 2021): 1–17. http://dx.doi.org/10.1155/2021/6653883.
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Nowadays, the application of a UAV swarm is becoming more and more widespread in the military field, and more and more attention is paid to the security of mission resource allocation. However, the relay node forwarding in the wireless transmission process brings greater risks to data leakage, and the computing power and energy of the UAV consumption is limited, so a lighter solution is required. This paper proposes a mechanism for the safe allocation of UAV swarm mission resources based on random labels. Each task has a random label to solve the problem of database security and wireless transmission security in the process of UAV task assignment. Furthermore, a lightweight stream cipher encryption scheme is illustrated to ensure the security of the UAV database. The irreversible hash function SHA-256 and the lightweight foam structure hash function SPONGENT-128 are used to generate random labels and then allocate task resources. In the case of energy consumption, it reduces the possibility of the enemy successfully obtaining private data. The simulation results show that the scheme has good performance in terms of security and has better performance than existing methods in terms of throughput and delay, without increasing too much energy consumption.
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Fan, Zhenquan, Xiaoyu Wang, Zijin Wang, Sijia Gao, and Sheng Lin. "Distributed variable stiffness joint assist mechanism based on laminated structure." International Journal of Advanced Robotic Systems 18, no. 6 (November 1, 2021): 172988142110606. http://dx.doi.org/10.1177/17298814211060661.
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Exoskeleton technology is more and more widely used in military, human rehabilitation, and other fields, but exoskeleton assisting mechanisms have problems such as high quality, concentrated driving sources, and poor flexibility. This article proposes a distributed variable stiffness joint power-assisted mechanism based on a laminated structure, which uses a giant magnetostrictive material as the driving source and the variable stiffness source of the structure. The distributed driving is realized by multiple driving units connected in series and parallel. Firstly, the drive unit stiffness matrix is deduced, and the expression equations of the cascaded total stiffness matrix of the drive module are obtained. After the simulation study, the curve of the stiffness of a single drive unit with a magnetic field and the stiffness of multiple drive units connected in series and parallel are in the absence of the magnetic field. The change curve of the stiffness of the booster module with the number of drive units under the excitation and saturation magnetic field excitation conditions is to achieve the effect of dynamically controlling the structural stiffness of the drive unit by controlling the size of the magnetic field and to obtain a general formula through data fitting. The number of drive units required under a fixed magnetic field excitation can ensure that the error is within 5%. The research results lay the foundation for further analysis of the distributed variable stiffness joint assist technology.
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Thirukumaran, Sanmugasundaram, Paul Ratnamahilan Polycarp Hoole, Harikrishnan Ramiah, Jeevan Kanesan, Kandasamy Pirapaharan, and Samuel Ratnajeevan Herbert Hoole. "A new electric dipole model for lightning-aircraft electrodynamics." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 33, no. 1/2 (December 20, 2013): 540–55. http://dx.doi.org/10.1108/compel-12-2012-0385.
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Purpose – As commercial and military aircraft continue to be subject to direct lightning flashes, there is a great need to characterize correctly the electrical currents and electric potential fluctuations on an aircraft to determine alternative design approaches to minimizing the severity of the lightning-aircraft dynamics. Moreover, with the increased severity of thunderstorms due to global warming, the need arises even more to predict and quantify electrical characteristics of the lightning-aircraft electrodynamics, which is normally not measurable, using a reliable electric model of the aircraft. Such a model is advanced here. The paper aims to discuss these issues. Design/methodology/approach – The case considered in this paper is that of an aircraft directly attached to an earth flash lightning channel. The paper develops a new approach to modelling the aircraft using electric dipoles. The model has the power to represent sharp edges such as wings, tail ends and radome for any aircraft with different dimensions by using a number of different sized dipoles. The distributed transmission line model (TLM) of the lightning return stroke incorporating the distributed aircraft model is used to determine aircraft electrical elements and finally the electric current induced on the aircraft body due to lightning's interaction with the aircraft. The model is validated by the waveform method and experimental results. Findings – The dipole model proposed is a very powerful tool for minute representation of the different shapes of aircraft frame and to determine the best geometrical shape and fuselage material to reduce electric stress. This charge simulation method costs less computer storage and faster computing time. Originality/value – The paper for the first time presents a computer-based simulation tool that allows scientists and engineers to study the dynamics of voltage and current along the aircraft surface when the aircraft is attached to a cloud to ground lightning channel.
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Qin, Xiaofei, Xu Wu, Mudi Xiong, Ye Liu, and Yue Zhang. "Multi-UAV Clustered NOMA for Covert Communications: Joint Resource Allocation and Trajectory Optimization." Electronics 11, no. 23 (December 6, 2022): 4056. http://dx.doi.org/10.3390/electronics11234056.
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Due to strong survivability and flexible scheduling, multi-UAV (Unmanned Aerial Vehicle)-assisted communication networks have been widely used in civil and military fields. However, the open accessibility of wireless channels brings a huge risk of privacy disclosure to UAV-based networks. This paper considers a multi-UAV-assisted covert communication system based on Wireless Powered Communication (WPC) and Clustered-Non-Orthogonal-Multiple-Access (C-NOMA), aiming to hide the transmission behavior between UAVs and legitimate ground users (LGUs). Specifically, the UAVs serve as aerial base stations to provide services to LGUs, while avoiding detection by the ground warden. In order to improve the considered covert communication performance, the average uplink covert rate of all clusters in each slot is maximized by jointly optimizing the cluster scheduling variable, subslot allocation, LGU transmit power and multi-UAV trajectory subject to covertness constraints. The original problem is a mixed integer non-convex problem, which are typically difficult to solve directly. To solve this challenge, this paper decouples it into four sub-problems and solves the sub-problems by alternating iterations until the objective function converges. The simulation results show that the proposed multi-UAV-assisted covert communication scheme can effectively improve the average uplink covert rate of all clusters compared with the benchmark schemes.