With the gradual popularization of 5G communications,the application of multi-antenna broadcasting technology has become ***,this study aims to investigate the wireless covert communication in the two-user cooperative...
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With the gradual popularization of 5G communications,the application of multi-antenna broadcasting technology has become ***,this study aims to investigate the wireless covert communication in the two-user cooperative multi-antenna broadcast *** focus on the issue that the deteriorated reliability and undetectability are mainly affected by the transmission *** tackle this issue,we design a scheme based on beamforming to increase the reliability and undetectability of wireless covert communication in the multi-antenna broadcast *** first modeled and analyzed the cooperative multi-antenna broadcasting system,and put forward the target *** we use the SCA(successive convex approximation)algorithm to transform the target problem into a series of convex *** the convex problems are solved and the covert channel capacity is *** order to verify the effectiveness of the scheme,we conducted simulation *** simulation results show that the proposed beamforming scheme can effectively improve the reliability and undetectability of covert communication in multi-antenna broadcast channels.
The integrated on-board battery chargers (IOBCs) can be used to repurpose the existing high-rated power electronic devices in electric vehicles (EVs) for charging, thereby cutting costs. However, non-isolated IOBCs fa...
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The integrated on-board battery chargers (IOBCs) can be used to repurpose the existing high-rated power electronic devices in electric vehicles (EVs) for charging, thereby cutting costs. However, non-isolated IOBCs face significant common-mode (CM) leakage currents owing to the lack of current isolation and coupling between the AC and DC side CM filters. A method that combines topology and modulation to suppress the CM leakage currents in a non-isolated integrated charger is proposed. The touch current can be suppressed below a reaction threshold of 1 MIU. This enhancement enables the safe usage and commercialization of transformer-less chargers, presenting superior charger efficiency, power density, and cost-effectiveness. The CM model of the proposed system is derived to guide the design of the circuit topology and modulation schemes. The simulation results are used to determine the feasibility of these techniques. Finally, a prototype of the 6.6 kW experimental charger is proposed, and the experimental results demonstrate the effectiveness of the proposed solution.
This manuscript explores the influences of the Foucault current on bracket vibration. Noise measurements are obtained in conditions that the coils are enclosed by the bracket, and exposed to the air for confirming the...
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This manuscript explores the influences of the Foucault current on bracket vibration. Noise measurements are obtained in conditions that the coils are enclosed by the bracket, and exposed to the air for confirming the impact of Foucault current on bracket vibration. The outcomes illustrate that the bracket increases the primary noise to 21 d B. Throughout investigational modal computation, ordinary frequencies of the coils stay afar from the exciting frequency of 100 Hz but the ordinary frequency 72.924 Hz of the bracket stands near to 100 Hz, which similarly explicates the upsurge of the noise level. To do the computations on bracket vibrations instigated by the Foucault current, a finite-element method(FEM) has been utilized for evaluating the eddy current density, electromagnetic forces(EMF), coupled with bracket response in frequency domain. The calculations displayed a proper approval by mean of theoretic investigations, and the simulations analyzed effectively the bracket vibration produced by Eddy current, and the electromagnetic force(EMF). Referring to the simulation, the primary vibration characteristics, and noise level, the method by applying weights(stress) on the top bracket of transformer is proposed to lessen the vibration amplitude, and noise level. To indorse the utility, and application of the suggested technique, the experiment results are obtained, analyzed, and compared with those of simulations, primary vibration characteristics, and noise level.
This study investigates the controllability of a general heterogeneous networked sampled-data system(HNSS) consisting of nonidentical node systems, where the inner coupling between any pair of nodes can be described b...
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This study investigates the controllability of a general heterogeneous networked sampled-data system(HNSS) consisting of nonidentical node systems, where the inner coupling between any pair of nodes can be described by a unique *** signals on control and transmission channels are sampled and held by zero-order holders, and the control sampling period of each node can be different. Necessary and sufficient controllability conditions are developed for the general HNSS, using the Smith normal form and matrix equations, respectively. The HNSS in specific topology or dynamic settings is discussed subsequently with easier-to-verify conditions derived. These heterogeneous factors have been determined to independently or jointly affect the controllability of networked sampled-data systems. Notably, heterogeneous sampling periods have the potential to enhance the overall controllability, but not for systems with some special dynamics. When the node dynamics are heterogeneous,the overall system can be controllable even if it is topologically uncontrollable. In addition, in several typical heterogeneous sampled-data multi-agent systems, pathological sampling of single-node systems will necessarily cause overall uncontrollability.
With the depletion of high-quality iron ore resources,high-phosphorus oolitic hematite(HPOH)has attracted great attention due to its large reserve and relatively high iron ***,HPOH is very difficult to be used in iron...
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With the depletion of high-quality iron ore resources,high-phosphorus oolitic hematite(HPOH)has attracted great attention due to its large reserve and relatively high iron ***,HPOH is very difficult to be used in ironmaking process due to its special structure.A two-step method of gas-based direct reduction and magnetic separation was thus proposed to recover iron and reduce *** results showed that the powdery reduced iron produced contained 92.31%iron and 0.1%phosphorus,and the iron recovery was 92.65%under optimum reduction condition,which is suitable for following *** apatite will be reduced under long reduction time and a large reducing gas flow rate,resulting in more phosphorus found in the metallic *** the hydrogen–carbon ratio will inhibit the formation and growth of iron particles and prevent the breakage of oolitic *** adjustment of reduction temperature is recommended as it affects the oolitic structure and reduction.
This work presents an adaptive tracking guidance method for robotic fishes. The scheme enables robots to suppress external interference and eliminate motion jitter. An adaptive integral surge line-of-sight guidance ru...
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This work presents an adaptive tracking guidance method for robotic fishes. The scheme enables robots to suppress external interference and eliminate motion jitter. An adaptive integral surge line-of-sight guidance rule is designed to eliminate dynamics interference and sideslip issues. Limited-time yaw and surge speed observers are reported to fit disturbance variables in the model. The approximation values can compensate for the system's control input and improve the robots' tracking ***, this work develops a terminal sliding mode controller and third-order differential processor to determine the rotational torque and reduce the robots' run jitter. Then, Lyapunov's theory proves the uniform ultimate boundedness of the proposed method. Simulation and physical experiments confirm that the technology improves the tracking error convergence speed and stability of robotic fishes.
Due to the complex structure and large size of large-capacity oil-immersed power transformers,it is difficult to predict the winding temperature distribution directly by numerical analysis.A 180 MVA,220 kV oil-immerse...
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Due to the complex structure and large size of large-capacity oil-immersed power transformers,it is difficult to predict the winding temperature distribution directly by numerical analysis.A 180 MVA,220 kV oil-immersed self-cooling power transformer is used as the research *** authors decouple the internal fluid domain of the power transformer into four regions:high voltage windings,medium voltage windings,low voltage windings,and radiators through fluid networks and establish the 3D fluidtemperature field numerical analysis model of the four regions,*** results of the fluid network model are used as the inlet boundary conditions for the 3D fluidtemperature numerical analysis *** turn,the fluid resistance of the fluid network model is corrected according to the results of the 3D fluid-temperature field numerical analysis *** prediction of the temperature distribution of windings is realised by the coupling calculation between the fluid network model and the 3D fluid-temperature field numerical analysis *** on this,the effect of the loading method of the heat source is also investigated using the proposed *** hotspot temperatures of the high-voltage,medium-voltage,and low-voltage windings are 89.43,86.33,and 80.96°C,***,an experimental platform is built to verify the *** maximum relative error between calculated and measured values is 4.42%,which meets the engineering accuracy requirement.
The design, simulation, and testing of intelligent trajectory-tracking control in narrow waters are essential issues for unmanned surface vehicles (USVs). Due to limited actuators, spatial constraints, and obstacles i...
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A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies t...
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A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies the generalized Lipschitz *** a complex nonlinear system primarily governed by statistical laws rather than Newtonian mechanics,the output of non-Newtonian mechanics systems is difficult to describe through deterministic variables such as state variables,which poses difficulties in predicting and estimating the system’s *** this article,the temporal variation of the system is described by constructing pattern category variables,which are non-deterministic *** pattern category variables have statistical attributes but not operational attributes,operational attributes are assigned to them by posterior probability density,and a method for analyzing their motion laws using probability density evolution is ***,a data-driven form of pattern motion probabilistic density evolution prediction method is designed by combining pseudo partial derivative(PPD),achieving prediction of the probability density satisfying the system’s output *** on this,the final prediction estimation of the system’s output value is realized by minimum variance unbiased ***,a corresponding PPD estimation algorithm is designed using an extended state observer(ESO)to estimate the parameters to be estimated in the proposed prediction *** effectiveness of the parameter estimation algorithm and prediction method is demonstrated through theoretical analysis,and the accuracy of the algorithm is verified by two numerical simulation examples.
Since human beings are of limited reasoning ability as well as the machines do not usually know human intentions, how to learn human cognitive levels in shared control to enhance the machines’ intelligence is a chall...
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