Transmission Conditions Research Articles

Помехоустойчивость многопользовательских систем MIMO при неидеальной оценке канала и других искажениях

The technology of multi-antenna MIMO (Multiple Input Multiple Output) systems is actively used in modern wireless communication systems. MIMO can enhance the performance of wireless data transmission systems, but their effectiveness depends on the transmission conditions. Ideal conditions are represented as a channel with a large number of possible signal propagation paths and an error-free estimation of its parameters. The estimation error significantly affects the performance of the beamforming algorithms used to mitigate inter-user interference in multi-user MIMO (MU-MIMO) systems. Spatial correlation of the channel results in a decrease in the number of independent information transmission streams. These factors can significantly reduce the performance of multi- antenna systems. For this reason, operating MIMO communication systems under non-ideal conditions is a topical issue. The paper examines the performance of various beamforming algorithms in such conditions. It describes the communication systems with MIMO, beamforming algorithms, and distorting effects. The paper includes a developed simulation model of the communication channel with MU-MIMO accounting for a variety of distorting factors. The results demonstrate the bit-error probability dependences for different simulation scenarios.

Effect of Phase Shift Definition on Power Characterization of Isolated DC–DC Converter Under PWM Plus Phase Shift Modulation

PWM plus phase shift (PPS) modulation is a popular modulation technique for the current fed dual active bridge (CFDAB) converter. Power transfer characteristics for any modulation technique are important for converters. However, in the literature, different power characteristics of CFDAB are presented for PPS modulation. This disparity in power transfer behavior creates confusion and ambiguity to the readers. This brief reveals the reason for such disparity. This is primarily due to the definition of the phase shift considered. When the phase shift is considered between the rising edges of high frequency voltages, asymmetric power transfer characteristics are obtained. On the contrary, symmetric power transfer characteristics are obtained if phase shift is considered between the mid point of high level of high frequency voltage signals. Thus the latter provides useful features and universal conditions for power reversal and peak power transmission individually. Steady state power under different modulation is obtained from unified model of CFDAB. The analytical results and experimental investigations are in agreement with each other.

Bacterial Vector-Borne Zoonotic Diseases and One Health Approach. A Review

Abstract One Health is a collaborative, multisectoral, and transdisciplinary approach with the goal of achieving optimal health outcomes recognizing the interconnection between people, animals, plants, and their shared environments. The main goal of this paper is to highlight the significance of the One Health concept in relation to the large group of diseases that transmits through arthropods and their worldwide distribution, with a closer look at the zoonoses. The importance of knowledge increases as the globalization and climate changes increases the likelihood of transmission, as both cause favourable conditions for transmission of bacteria and viruses. The increase in reservoir abundance, climate change, changing habitat structure, socio-political changes, and import of animals for welfare reasons, trade and traveling are considered to be potential factors for the pathogen and vector introductions to new areas. This article highlights the selected agents of bacterial zoonoses as sources of human and animal diseases and shows the number of cases of Lyme disease, which is the most common bacterial tick-borne disease in humans in Slovakia and Norway, and the trend in incidence over the past twelve years.

Non-equilibrium steady states as saddle points and EDP-convergence for slow-fast gradient systems

The theory of slow-fast gradient systems leads in a natural way to non-equilibrium steady states, because on the slow time scale the fast subsystem stays in steady states that are controlled by the interaction with the slow system. Using the theory of convergence of gradient systems depending on a small parameter ɛ (here the ratio between the slow and the fast time scale) in the sense of the energy-dissipation principle shows that there is a natural characterization of these non-equilibrium steady states as saddle points of a so-called B-function where the slow variables are fixed. We give applications to slow-fast reaction-diffusion systems based on the so-called cosh-type gradient structure for reactions. It is shown that two binary reactions give rise to a ternary reaction with a state-dependent reaction coefficient. Moreover, we show that a reaction-diffusion equation with a thin membrane-like layer convergences to a transmission condition, where the formerly quadratic dissipation potential for diffusion convergences to a cosh-type dissipation potential for the transmission in the membrane limit.

Adaptive and Contract Aware Configuration for Industrial Wireless Networks

Planning the transmission routing and scheduling is a challenging issue in industrial wireless networks (IWN) due to high quality of service (QoS) requirements. Moreover, in many applications we face the problem of node mobility, changes of transmission conditions, node resource and powering limitations. This paper initially formulates the problem of searching optimal network configuration covering the outlined features and subsequently proposes an effective solution. It is designed for typical industrial FDMA and TDMA networks with horizontal communication. The goal of our studies is to find IWN configuration (routing, time slot and channel allocation) that maximizes the number of successfully concluded contracts. The presented method is compatible with the ISA100.11a standard and integrates relevant QoS requirements for different periodic and aperiodic contracts. Our approach is based on original deterministic algorithms for planning the traffic. They are optimized with a genetic algorithm and facilitate the adaptation to changing operation conditions of network nodes. Extensive simulation experiments have been used in the development and evaluation of the proposed algorithms. The introduced test environment and benchmarks confirmed the advantages of our approach and revealed drawbacks of other approaches.

Detection of scatterers using an XFEM-BEM level set solver based on the topological derivative

A numerical method is proposed for the solution of the inverse scattering problem. This problem consists of determining the location and shape of an unknown number of inclusions composed by a homogeneous material with known mechanical properties different that those of the surrounding medium. The information available to solve the inverse problem are measurements of the fundamental mechanical magnitude of the wave propagation problem. At the boundary of the scatterers, transmission conditions depending on the material properties are considered. For the solution of the forward problem, a coupled extended finite element method (XFEM)-boundary element method (BEM) is proposed, where the XFEM is used for the bounded region where the scatterers are supposed to be located, and the BEM is used for the exterior domain. The inverse problem is formulated as a topology optimization problem, and solved by means of a heuristic algorithm based on the topological derivative and a level set representation of the scatterers.

On the use of a tailored fluid-fluid Green's function to predict scattering from two-phase fluid interfaces

In naval applications, the precise knowledge of the acoustical behaviour of two-phase fluids is of interest. Indeed, they appear in many configurations as bubbles curtains, cavitation (along propellers and pipes) or two-phase turbulent boundary layers and wakes (gas exhaust). To model this problem, we focus on a Boundary Element/ Boundary Element coupling for low to moderate frequencies. We propose two approaches: (a) solving the Helmholtz equations in each phase by introducing the free field Green's function and (b) determining a tailored Green's function, taking into account the presence of the two-phase fluid. The determination of a tailored Green's function has two main advantages: (i) it allows a reduction of the numerical model, since it contains all the information on the fluid-fluid coupling, in particular the transmission conditions and resonances and (ii) it is source-independent and thus it gives directly the answer to any source. Numerical tests on the evaluation of radiated noise are performed to determine the efficiency of the approach based on a tailored Green's function compared to the free-field based one.

Power Supply Reliability Analysis of Distribution Systems Considering Data Transmission Quality of Distribution Automation Terminals

A distribution automation system is the integration of physical power distribution systems and information systems. Its information system guarantees the safe operation and reliable power supply of physical systems by monitoring, collecting and transmitting information. In the information system, the remote terminal unit of distribution automation is the hub of the information system, connecting it to the physical power system. Considering the unreliability of terminal information transmission in the information system, this paper aims to build a model to quantitatively evaluate the impact of unreliable transmission information on the power supply reliability of distribution systems. Firstly, the m-segment and n-connection unit model of distribution feeders is established, and then, the power supply reliability indices in the process of handling feeder terminal unit error are analyzed and calculated under the configuration modes of “three-remote” and “two-remote” of remote terminals. Then, considering the impact of a transmission error in the information system, the reliability index calibration model under the condition of unreliable information transmission is established. Finally, a case study is presented to illustrate how the proposed model is implemented.

Convergence analysis of Schwarz waveform relaxation method to compute coupled advection–diffusion–reaction equations

We study the computation of coupled advection–diffusion–reaction equations with the same or different coefficients by the Schwarz waveform relaxation method. The study starts with linear equations and analyzes the computation’s convergence with a Dirichlet condition, a Robin condition, and a combination of them as the transmission conditions. Then, it presents an optimized algorithm for the Dirichlet condition, and this algorithm leads to a substantial speedup in the convergence. Furthermore, the optimized algorithm extends to the computation of nonlinear equations, including the viscous Burgers equation, and the algorithm largely remains effective for convergence speedup. Finally, the study compares waveform relaxation and conventional methods. Numerical experiments indicate that the former tends to be much more expensive than the latter regarding the number of times to solve the involved linear systems.

Analyzing electromagnetic scattering from complex multi-layer patch objects using a multi-trace domain decomposition method

The local-coupling multi-trace and domain decomposition method originally developed to analyze electromagnetic scattering from closed composite objects is extended to solve the scattering from complex multilayer patch objects. Different from the traditional global radiation coupling surface integral equation domain decomposition method and contact-region modeling method (CRM), the local-coupling property yields many excellent properties, highly sparse matrix, better computational performance, etc. In this novel proposed method, the multilayer patch objects are decomposed into many independent sub-domains, and each sub-domain is assumed as a homogeneous dielectric subdomain to formulate the electric-field integral equation (EFIE) and the magnetic-field integral equation (MFIE) for dielectrics as the governing equations. The corresponding boundary condition of the perfect electric conducting (PEC) surface sheet is then achieved by adopting Robin transmission conditions (RTCs) to PEC surfaces, termed PEC-RTCs. The final resulting equation yield a better performance than the traditional method. Numerical examples validate the advantages of the proposed method.

Operational status monitoring of smart grid and power communication network coupling and collaboration based on multi-head attention mechanism

Smart grid is an organic combination of traditional power grid and advanced digital communication technology, and power communication network plays a vital role in ensuring its steady operation. However, as the coupling correlation between the smart grid and the power communication network increases, the propagation of coupled network failures may constitute a great threat to the safe and stable operation of the power system. To address this phenomenon, based on the algorithm of the multi-head attention mechanism (MHA) and convolutional neural network (CNN), this paper proposes a framework that integrates the multi-head attention mechanism with the convolutional neural network (MHA-CNN) for the monitoring of the coupling network’s operation status. In the proposed algorithm, Hilbert–Huang transform (HHT) is used to extract the intrinsic features of the operational data, and MHA employs multi-subspace analysis and extracts the key feature information of the fault data to maximize the fault information extraction and help the system to discover the fault as soon as possible. Simulation results demonstrate that the proposed algorithm can effectively realize a better detection speed and higher detection probability compared with CNN and ResNet-50, and maintain certain robustness under poor transmission conditions, ensuring the steady operation of the coupled network.

Spatial transferability of an agent-based model to simulate Taenia solium control interventions

BackgroundModels can be used to study and predict the impact of interventions aimed at controlling the spread of infectious agents, such as Taenia solium, a zoonotic parasite whose larval stage causes epilepsy and economic loss in many rural areas of the developing nations. To enhance the credibility of model estimates, calibration against observed data is necessary. However, this process may lead to a paradoxical dependence of model parameters on location-specific data, thus limiting the model’s geographic transferability.MethodsIn this study, we adopted a non-local model calibration approach to assess whether it can improve the spatial transferability of CystiAgent, our agent-based model of local-scale T. solium transmission. The calibration dataset for CystiAgent consisted of cross-sectional data on human taeniasis, pig cysticercosis and pig serology collected in eight villages in Northwest Peru. After calibration, the model was transferred to a second group of 21 destination villages in the same area without recalibrating its parameters. Model outputs were compared to pig serology data collected over a period of 2 years in the destination villages during a trial of T. solium control interventions, based on mass and spatially targeted human and pig treatments.ResultsConsidering the uncertainties associated with empirical data, the model produced simulated pre-intervention pig seroprevalences that were successfully validated against data collected in 81% of destination villages. Furthermore, the model outputs were able to reproduce validated pig seroincidence values in 76% of destination villages when compared to the data obtained after the interventions. The results demonstrate that the CystiAgent model, when calibrated using a non-local approach, can be successfully transferred without requiring additional calibration.ConclusionsThis feature allows the model to simulate both baseline pre-intervention transmission conditions and the outcomes of control interventions across villages that form geographically homogeneous regions, providing a basis for developing large-scale models representing T. solium transmission at a regional level.Graphical

Interference Avoidance through Periodic UAV Scheduling in RIS-Aided UAV Cluster Communications

This article investigates the transmission of downlink control signals for multiple unmanned aerial vehicle (UAV) clusters in collaborative search and rescue operations in mountainous environments. In this scenario, a reconfigurable intelligent surface (RIS) mounted on the UAV is utilized to overcome obstacles between the ground base station (BS) and UAVs. By leveraging the fixed channel of the RIS to the BS, the line-of-sight (LoS) path characteristics of the air-to-air channel, and the position information of the UAV, the RIS forms a directional beam by adjusting the RIS coefficient, which points towards UAVs in the cluster. To ensure low delay in control signaling and UAV state transmission, we adopt semi-persistent scheduling (SPS), which allocates pre-specified periodic intervals to each UAV for the formation of corresponding RIS coefficients. The allocation of time slots is constrained by the transmission intervals required by different UAVs and the number of RISs available. We propose a time slot scheduling scheme for UAVs to reduce inter-cluster interference caused by RIS beams. The time slot allocation problem is formulated as a combinatorial optimization problem. To solve this problem, we first propose an intuitive greedy scheme called local interference minimization (LIM). Building upon the LIM scheme, we propose a rollout-based algorithm called rollout interference minimization (RIM). Through simulation, we compare the LIM and RIM schemes with the benchmark scheduling scheme. The results demonstrate that our proposed scheme significantly reduces interference between UAV clusters while satisfying the conditions of periodic transmission and RIS quantity constraints.

Asymptotics of eigenvalues and eigenfunctions of a discontinuous boundary value problem with a spectral parameter in the transmission condition

We determine asymptotics of eigenvalues and eigenfunctions of a discontinuous boundary value problem with a spectral parameter in the transmission condition.

Electromagnetic Guided Wave in Goubau Line with Graphene Covering: TE Case

This paper focuses on the problem of monochromatic terahertz TE-polarized wave propagation in a special type of circle cylindrical waveguides, the so-called Goubau line. The outer shell of the waveguide is covered with graphene characterized by complex surface conductivity. This covering affects electromagnetic wave propagation due to the generation of a surface current in graphene. The nonlinear interaction of graphene with the electromagnetic field is taken into account via a nonlinear term involving in graphene conductivity. Starting from the rigorous formulation for Maxwell’s equations with appropriate boundary and transmission conditions, we derive the dispersion equation for propagation constants. We discuss this result and point out some methods of studying the dispersion equation analytically. At the same time, we suggest numerical experiments shedding light on how cubic nonlinearity affects electromagnetic wave propagation.

Convergence analysis and optimization of a Robin Schwarz waveform relaxation method for time-periodic parabolic optimal control problems

This paper is concerned with a novel convergence analysis of the optimized Schwarz waveform relaxation method (OSWRM) for the solution of optimal control problems governed by periodic parabolic partial differential equations (PDEs). The new analysis is based on a Fourier-type technique applied to a semidiscrete-in-time form of the optimality condition. This leads to a precise characterization of the convergence factor of the method at the semidiscrete level. Using this characterization, the optimal transmission condition parameter is obtained at the semidiscrete level and its asymptotic behavior as the time discretization converges to zero is analyzed in detail.

BASIC BOUNDARY VALUE PROBLEM WITH RETARDED ARGUMENT CONTAINING AN EIGENPARAMETER IN THE TRANSMISSION CONDITION

In this paper basic boundary value problem with retarded argument that has a discontinuity point inside the interval will be studied. At the discontinuity point transmission conditions contain eigenparameter. Existence of eigenvalues and eigenfunctions will be studied. Asmyptotic properties of eigenvalues and eigenfunctions will be obtained.

Uniqueness in determining rectangular grating profiles with a single incoming wave (part II): TM polarization case

This paper is concerned with an inverse transmission problem for recovering the shape of a penetrable rectangular grating sitting on a perfectly conducting plate. We consider a general transmission problem with the coefficient λ ≠ 1 which covers the transverse magnetic (TM) polarization case. It is proved that a rectangular grating profile can be uniquely determined by the near-field observation data incited by a single plane wave and measured on a line segment above the grating. In comparison with the transverse electric (TE) case (λ = 1), the wave field cannot lie in H 2 around each corner point, bringing essential difficulties in proving uniqueness with one plane wave. Our approach relies on singularity analysis for Helmholtz transmission problems in a right-corner domain and also provides an alternative idea for treating the TE transmission conditions which were considered in the authors’ previous work (Xiang and Hu 2023 Inverse Problems 39 055004).

Ways to improve performance of an internal combustion engine regarding the loading conditions of vehicle transmission

BACKGROUND: Import substitution has become the most important direction of the development of the country's economy in the conditions of the sanctions policy. In this regard, high requirements are imposed on the production to ensure the competitiveness of automotive machinery. Automotive machinery is a key component of the country's economy that is confirmed by the growth of road transport. Meanwhile, growth of the vehicle fleet leads to increase in consuming of petroleum-derived fuel, which main disadvantage is emission of harmful substances, therefore, internal combustion engines of automotive machinery should ensure low fuel consumption and less emissions of harmful substances with exhaust gases. However, the engine operating modes largely depend on the loads generated in the vehicle transmission.
 AIMS: To determine the possibilities of expanding the ranges of power regulation of an internal combustion engine of a vehicle, on the one hand, ensuring low fuel consumption and less emission of harmful substances with exhaust gases, and on the other hand, providing with the power required for a vehicle to move, regarding the type of transmission and propulsion.
 METHODS: The analysis of possible conventional and unconventional operating cycles of an internal combustion engine is carried out. The method of mathematical modeling of the formation of torques in various types of vehicle transmission is used.
 RESULTS: Possible ways of expanding the ranges of power regulation of an internal combustion engine providing with the required power, low fuel consumption and less emission of harmful substances with exhaust gases, as well as transmission layouts and processes of forming the required power in them to ensure the vehicle movement are considered.
 CONCLUSIONS: The considered in the article approach of expanding the ranges of power regulation of an internal combustion engine of a vehicle makes it possible to conclude that it is necessary to use the principles of a scientific approach to the process of development of vehicle transmissions capable of controlling an internal combustion engine depending on loads, ensuring its operation with minimal fuel consumption and emission of harmful substances.

Dual Event-Triggered Controller Co-Design for Networked Control Systems with Network-Induced Delays

To address the presence of network-induced delays in networked control systems (NCSs), a dual event-triggered mechanism (DETM) is used to investigate the problem of reducing network delays and controller co-design. Firstly, the DETM of the sensor–controller (SC) and the controller–actuator (CA) is adopted. By determining whether the sampled data meet the event-triggered threshold conditions for network transmission, we effectively reduce the sampled data transmitted over the network, which can reduce a network delay by reducing occupation of the network resources. Secondly, a dual event-triggered NCS model with a network-induced delay is developed, and a Lyapunov function including a DETM and network-induced delay is chosen. The functional upper limit of the Lyapunov function is estimated by combining the Wirtinger’s-based integral inequality with the reciprocally convex approach. This results in a stability criterion for systems with low conservativeness and a controller co-design method for a DETM. Finally, the availability of this method was verified through a numerical example and case study.