Problem Of Mutual Interference Research Articles

Research on key technologies for automatic planning of multiple links on a single node

Abstract Aiming at the problems of slow speed and low efficiency existing in the traditional manual planning method of multiple links on a single node, which cannot fully meet the rapid deployment needs of communication nodes, this paper studies and puts forward two automatic planning technologies of single-node-multi-link based on shortest distance priority and minimum angle priority. This is an automatic planning technology that uses the shortest distance priority to determine the pairing relationship between the multi-scattering antenna of the local communication node and the far-end scattering antenna. It aims to solve the issue of cross-redundancy of distance in wrong planning. Automatic planning technology of single-node-multi-link based on minimum angle priority simulates manual planning mode. Using the concept of minimum angle priority, the pairing relationship between the multi-scattering antenna of the local communication node and the remote scattering antenna is determined. This is achieved by calculating and optimizing the minimum angle of two rays that are formed from the origin of the coordinate system of the local communication node to the local scattering antenna and the remote scattering antenna, respectively. Comparative analysis and simulation experiments prove that the two key technologies proposed in this paper can not only effectively avoid the problem of mutual interference between multiple scattering antennas in this node but also improve the efficiency of multi-link planning on a single node.

A feature and optimized RRT algorithm-based assembly path planning method of complex products

Currently, manufacturing enterprises lack strict regulations and plans for complex products. The actual assembly path mainly relies on technicians’ experience, leading to an unreasonable assembly path for each part at the workstation, an unreasonable transportation path across the workstation, and the problem of mutual interference between parts. To solve these problems, this paper studies the assembly path planning technology of complex products based on the basic geometric features and assembly sequence information. The complexity of assembly path planning is reduced by converting the assembly problem into a disassembly problem. The disassembly direction and distance of each part are determined based on the geometric feature type of each mating face, and the rapid disassembly of the assembly body is achieved. The Rapidly-exploring Random Trees (RRT) algorithm is optimized by target-tendency and double random tree strategy, and the optimal assembly path of each component is quickly generated by combining the path optimization method and interference checking method. Finally, the effectiveness of the proposed method and the superiority of the path planning algorithm are verified using the cylinder head of a Marine diesel engine (MDE) as a case study.

Forward-Looking Passive Radar With Non-Uniform Linear Array for Automotive Applications

With the rapid and growing spread of automotive radar systems in modern vehicles, the problem of their mutual interference is becoming a major safety concern. This paper considers the use of receive-only sensors onboard the vehicles, which exploit an external illumination source to provide automotive radar functionalities. The passive radar paradigm would solve the problem of mutual interference, allowing different systems to share the same transmitted signal. A preliminary analysis of the feasibility of this concept is carried out, exploiting real-world transmitters of opportunity. The potentialities offered by both satellite and ground-based illuminators are investigated and the expected performance is evaluated in terms of achievable coverage and spatial resolution. Aiming to enable a practical implementation of the proposed concept, an appropriate signal processing scheme is proposed to obtain maps of the observed scene. A Doppler beam sharpening approach is adopted to discriminate and localize stationary scatterers in azimuth based on the differences in their relative Doppler shift. The problem of left/right ambiguity arising from the forward-looking geometry is tackled by exploiting an array of few antenna elements on receive. Specifically, an ambiguity removal approach is proposed, based on digital beam pattern adaptation, designed to maximise the response in the desired direction and suppress unwanted echoes from the corresponding ambiguous one. The effectiveness of this approach is further improved by cascading an apodization technique that prevents the undesirable increase in the noise level. Moreover, some criteria are introduced for the design of the antenna layout, resorting to non-uniform linear array configurations. The proposed system is tested against a simulated environment, where the multi-channel signal processing, combined with a properly designed array layout, is shown to provide an unambiguous mapping of the observed scene over wide angular sectors, even operating with few antenna elements on receive.

Interference Mitigation Method for Millimeter-Wave Frequency-Modulation Continuous-Wave Radar Based on Outlier Detection and Variational Modal Decomposition

Aiming at the problem of mutual interference between millimeter-wave frequency-modulation continuous-wave (FMCW) radars, an interference mitigation method based on outlier detection and variational mode decomposition (VMD) is proposed in this paper. Firstly, by differential processing of the raw millimeter-wave FMCW radar data, combined with threshold detection, the interfered sample area is located. Adaptive amplitude limiting is applied to the interfered samples to achieve initial suppression of the interference. Then, based on the VMD algorithm, the processed data are adaptively decomposed to obtain multiple intrinsic mode functions (IMFs). The Pearson correlation coefficient between each IMF and the signal before decomposition is calculated, and the IMF with the maximum Pearson correlation coefficient is extracted as the signal component to achieve the separation of the target signal from the interference and noise. The proposed method was validated based on simulation and experimental data. The results show that the proposed method achieves the best performance in terms of signal-to-interference-plus-noise ratio (SINR), mean square error (MSE), and kurtosis in frequency (KF) compared with empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD), and complete ensemble empirical mode decomposition (CEEMD). Further comparison was made with two typical methods, and the Range–Doppler (RD) map and SINR results showed that the proposed method exhibited certain performance advantages.

Mitigation of Millimeter-Wave Radar Mutual Interference Using Spectrum Sub-Band Analysis and Synthesis

Millimeter-wave radars are widely used in automotive radars because of their all-weather and all-day operation capability. However, as more and more radar sensors are used, the possibility of mutual interference between radars increases dramatically. Severe interference increases the noise level, affects target detection performance, and can lead to missed detection and wrong detection. In this study, a novel solution to the problem of mutual radar interference is introduced. The method is based on the analysis and synthesis of spectrum sub-bands. Specifically, the received radar signal is partitioned into sub-bands, after which interference mitigation is carried out in each sub-band. Finally, the signals are reconstructed to obtain interference-free data. The effectiveness of this approach is evaluated using both a simulated multi-target scenario and a real-life experimental environment. The results demonstrate that the proposed method outperforms existing techniques in terms of interference mitigation while exhibiting rapid processing speeds.

Theoretical analysis of a multi-grating-based cross-dispersed spatial heterodyne spectrometer.

This paper presents a multi-grating-based cross-dispersed spatial heterodyne spectrometer (MGCDSHS). The principle of generation of two-dimensional interferograms for two cases, where the light beam is diffracted by one sub-grating or two sub-gratings, is given and equations for the interferogram parameters in these two cases are derived. An instrument design with numerical simulations is presented that demonstrates the spectrometer's ability to simultaneously record separate interferograms corresponding to different spectral features with high resolution over a broad spectral range. The design solves the mutual interference problem caused by overlapping of the interferograms, and also provides the high spectral resolution and broad spectral measurement range that cannot be achieved using conventional SHSs. Additionally, by introducing cylindrical lens groups, the MGCDSHS solves the throughput loss and light intensity reduction problems caused by direct use of multi-gratings. The MGCDSHS is compact, highly stable, and high-throughput. These advantages make the MGCDSHS suitable for high-sensitivity, high-resolution, and broadband spectral measurements.

Coordinated control algorithm of lateral stability of hybrid electric commercial vehicle

Focusing on the problem of mutual interference between the vehicle controller and the lateral stability control system in the stability control of hybrid electric vehicles (HEV), this study proposes a coordinated control algorithm for hybrid power systems and lateral stability, which can meet the real-time control requirements of the vehicle stability. First, the overall architecture of coordinated control between the hybrid power system and the vehicle lateral stability control system is designed. The judgment logic of lateral stability control system intervention and exit is determined on this basis. Second, in the upper layer of the control algorithm, the model predictive control algorithm is used to calculate the additional yaw moment required to maintain stability control under lateral instability of the vehicle with the vehicle two-degrees-of-freedom model as a reference. The motor output torque control and braking force distribution are then carried out in the lower layer of the control algorithm. The target braking wheel is determined according to the oversteering and understeering state of the hybrid vehicle. The additional yaw torque distribution control is formulated based on the quadratic programing algorithm. The strategy is to perform dynamic compensation for unstable or critically unstable vehicles to solve the optimal control problem under multiple constraints. Finally, through Matlab/Simulink and Trucksim co-simulation and hardware-in-the-loop test, the validity and real-time performance of the control algorithm proposed are verified to solve the interference problem in the lateral stability control process of HEVs and further improve the stability of vehicle rideability and active safety.

Satellite Network Transmission of Cooperative Relay Superimposed Signal Reconstructed in Spatial Dimension

In order to save frequency resources, a new remote sensing satellite service can gradually adopt relay cooperation transmission to realize the same frequency and common channel transmission of multiple data. To solve the problem of mutual interference between messages, this study proposes a universal model of relay cooperative channel transmission, and the separation mechanism of heterogeneous signals for simultaneous unicast and multicast transmission is also studied. In this study, a signal space is used to reconstruct the degrees of freedom, and an orthogonalized spatial alignment direction is designed to obtain the equivalent parallel transmission channel. We also propose a constellation point remapping scheme under the optimal constraint of spatial separation of transmission signals. Furthermore, we merge constellation points to solve the problem of fuzzy mapping of physical layer network coding. The simulation results show that the co-channel transmission with interference suppression can be realized when the equivalent degrees of freedom of the signal intersection subspace is not less than dpK(K−1)+dcK. The Euclidean distance between constellation points is increased by constructing orthogonal signal spatial alignment directions, which brings an additional BER performance gain of 2 dB. If the signal alignment direction and channel quality are jointly designed, the transmission quality can be further improved.

Background Scene Recovery From an Image Looking Through Colored Glass

Colored glass, which is commonly seen in modern city life, often degrades images taken through it with co-occurring reflection and color bias due to its optical property of simultaneous transmission, reflection, and wavelength-selective absorption.~Recovering the clean background behind colored glass is inherently challenging due to the mutual interference of two degradations within a single mixture observation, and has barely been specifically considered by existing image restoration methods. In this paper, we aim at realizing faithful background scene recovery for an image taken in front of colored glass. We first analyze the formation model of mixed degradations caused by colored glass, and propose a cooperative framework to address the mutual interference problem, featuring a novel glass color invariant loss and progressive refinement. Besides, we propose a data synthesis strategy for network training. Experimental results on our newly collected real-world dataset show that our proposed method achieves state-of-the-art performance.

Directed acyclic graphs-based diagnosis approach using small data sets for sustainability

Improving the ability of crop disease diagnosis in agriculture to reduce water pollution caused by pesticide abuse plays a key role in realizing the model of “sustainable intensification”. The current common methods of disease diagnosis through machine vision need an extremely large image data set to reduce the interference of light, background, and other factors. Unfortunately, even common crops will have the problem of lack of suitable and sufficient disease image data sets. In this paper, a disease model based on graph theory is designed to solve the problem of large data sets required by machine vision methods. The model adds the concept of guidepost to the standard directed acyclic graph, which solves the problem of mutual interference between the paths of different diseases. Based on the disease model, the disease diagnosis algorithm designed in this paper achieves effective disease diagnosis under the missing input indicator sequence. Based on the above, a disease diagnosis system with B/S structure is constructed. The system includes two core modules: knowledge base and inference engine. Finally, based on the disease diagnosis system, the disease diagnosis algorithm is tested. The test takes the disease diagnosis of watermelon as an example. Under the scenario of complete and partial missing input indicator sequence, the specific cases are divided into 11 kinds, and three tests are carried out respectively. The results show that the algorithm not only reduces the dependence on data sets, but also can still achieve effective disease diagnosis through fuzzy inference when the input indicator sequence is chaotic and missing. Due to its low data set requirements, the results of this study have good applicability, which will greatly improve the intelligent development of crop disease diagnosis in agriculture.

Formation of double-hump solitons and their applications in optical communication systems

Optical communication system with optical solitons has the characteristics of low relay cost, low bit error rate and long relay distance. The modern optical communication system is developing towards large capacity, long distance and high speed. The width of optical pulse has been increased to femtosecond. With the increase of signal frequency, the effects of dispersion and nonlinear involved in it become more and more complex. Therefore, using femtosecond soliton communication to overcome these problems has urgent practical significance. In this paper, starting from the coupled nonlinear Schrödinger equation describing soliton transmission, we use the bilinear method to study the transmission characteristics and interaction of double-hump solitons under the interaction of dispersion and nonlinear effects, solve the problem of mutual interference between adjacent optical solitons, and realize the non-interaction transmission between adjacent solitons. This conclusion lays a theoretical foundation for the optical soliton propagation without distortion and interference in optical communication systems.

A Cross-Attention Mechanism Based on Regional-Level Semantic Features of Images for Cross-Modal Text-Image Retrieval in Remote Sensing

With the rapid development of remote sensing (RS) observation technology over recent years, the high-level semantic association-based cross-modal retrieval of RS images has drawn some attention. However, few existing studies on cross-modal retrieval of RS images have addressed the issue of mutual interference between semantic features of images caused by “multi-scene semantics”. Therefore, we proposed a novel cross-attention (CA) model, called CABIR, based on regional-level semantic features of RS images for cross-modal text-image retrieval. This technique utilizes the CA mechanism to implement cross-modal information interaction and guides the network with textual semantics to allocate weights and filter redundant features for image regions, reducing the effect of irrelevant scene semantics on retrieval. Furthermore, we proposed BERT plus Bi-GRU, a new approach to generating statement-level textual features, and designed an effective temperature control function to steer the CA network toward smooth running. Our experiment suggested that CABIR not only outperforms other state-of-the-art cross-modal image retrieval methods but also demonstrates high generalization ability and stability, with an average recall rate of up to 18.12%, 48.30%, and 55.53% over the datasets RSICD, UCM, and Sydney, respectively. The model proposed in this paper will be able to provide a possible solution to the problem of mutual interference of RS images with “multi-scene semantics” due to complex terrain objects.

An Intelligent Access Channel Algorithm Based on Distributed Double Q Learning

Aiming at the problem of mutual interference between nodes and external malicious jamming in wireless communication networks, this paper proposes an intelligent communication anti-jamming algorithm based on distributed double Q-learning. First of all, the proposed algorithm anti-jamming problem is modeled as a time-frequency two-dimensional optimization problem. The decoupled relationship between subframe and channel is used. Each node uses two Q-learning. According to the automatically received feedback signal, users choose their subframe and channel to avoid malicious external jamming and mutual interference between users. It maximizes the sum of all user throughput. Simulation results show that the proposed algorithm can effectively shorten the convergence time and improve the performance of the system.

A scheme of motor drive and control based on simultaneous wireless information and power transfer with tapped coil

Wireless power transfer (WPT) technology has been widely used in industrial and household fields. This technology is of great significance in the field of motor drives. However, if the WPT technology is applied to the motor drive and control system, power and control signals need to be transmitted at the same time, which will cause the problem of mutual interference between signals of different frequencies, and will also increase the difficulty of frequency decomposition on the secondary side. To solve the above problems, a dual-frequency simultaneous wireless information and power transfer (SWIPT) system using a tapped coil structure scheme is proposed and the design principle of the tapped coil is given. Based on this scheme, a multi-frequency pulse width modulation (MFPWM) method is used to generate two components of different frequencies by the same inverter, which are automatically decoupled by the tapped coil, and finally transmitted to drive and control the motor. A closed-loop control strategy is used to solve the problem of precise motor speed control when the driving voltage of the wireless motor fluctuates. In the experiment, the motor speed increased from 1965 rpm to 2265 rpm, and the DC voltage corresponding to the set reference speed increased from 1.26 V to 2.30 V. The experimental results show that the scheme can control the BLDC motor speed stably and accurately.

Uncertainty analysis of MSD crack propagation based on polynomial chaos expansion

Widespread fatigue damage (WFD) is one of the main damages in aging aircraft structures, and the prediction of multi-site damage (MSD) crack propagation plays an important role in the safety assessment of aging aircraft. However, the existing multi-crack propagation stochastic models need to calculate multiple integrals, and the calculation efficiency is low. Based on the Polynomial Chaos Expansion (PCE) method, this paper proposes a new uncertainty analysis method to effectively solve the problem of multi-crack mutual interference. The rivet area of aircraft skin mostly appears randomly in the form of short cracks. Therefore, 30 groups of multi-crack fatigue propagation experiments are carried out to obtain the data of multi-cracks at different stages. On the basis of the existing multi-crack mutual interference model, a new semi-analytical multi-crack propagation model is designed by considering the uncertainty of multi-crack initiation and the interaction factors between cracks. The random variables are substituted into the improved multi-crack propagation model, and the Hermite polynomials are introduced and expanded into orthogonal polynomial series, and the time-varying polynomial coefficients, moments and probability densities are solved by stochastic regression method. The accuracy and effectiveness of the method are verified by comparing with the experimental and Monte Carlo methods.

Optimization design method of infill well trajectory with bypassing obstacles in the fractured area of shale gas reservoir

In the design of infill well trajectory in fractured area of shale gas reservoir, it is necessary to consider the problem how to bypass the fractured influence area of the old shale gas wells, as well as the problem of mutual interference between the different fractured sections during production. In this paper, the geometric model of the obstacles in fractured area of shale gas reservoir, which considers the trajectory error and fracturing effect, is established by vector algebra method. The trajectory type is classified according to positional relations among the obstacle, the directional line of initial point and target point. The trajectory optimization model for bypassing obstacles takes the minimum total well length as objective function, the safety distance to obstacle as one of the constraints. In addition, the geometric check method for judging whether there is interference between the different fractured sections is proposed based on the geometric obstacle model. Case studies have been carried out according to the field data from Fuling, and the results indicate that the trajectory optimization model in this paper can obtain the optimum trajectory to meet the needs for bypassing obstacle, minimum trajectory length and avoiding trial calculation. Besides, if the fracturing effect is ignored, the size of the obstacle will be significantly underestimated in fractured area of shale gas reservoir, which will result in drilling accidents. In sum, the obstacle model in this paper is more consistent with the situation of field fractured area drilling practice than that of the published model. This study will provide a more safer and briefer design method for optimizing the infill well trajectory in fractured area of shale gas reservoir, which is of great significance to the shale gas drilling design and drilling safety.

Recognition Method of Digital Meter Readings in Substation Based on Connected Domain Analysis Algorithm

Aiming at the problem that the number and decimal point of digital instruments in substations are prone to misdetection and missed detection, a method of digital meter readings in a substation based on connected domain analysis algorithm is proposed. This method uses Faster R-CNN (Faster Region Convolutional Neural Network) as a positioning network to localize the dial area, and after acquiring the partial image, it enhances the useful information of the digital area. YOLOv4 (You Only Look Once) convolutional neural network is used as the detector to detect the digital area. The purpose is to distinguish the numbers and obtain the digital area that may contain a decimal point or no decimal point at the tail. Combined with the connected domain analysis algorithm, the difference between the number of connected domain categories and the area ratio of the digital area is analyzed, and the judgment of the decimal point is realized. The method reduces the problem of mutual interference among categories when detecting YOLOv4. The experimental results show that the method improves the detection accuracy of the algorithm.

Stackelberg Game Theory for Rectifying Mutual Interferences among Secondary Users of Cognitive Radio Network in Comparison with Cournot Game Theory

Aim: The aim of the study is to solve the problem of mutual interference among SUs based on Stackelberg game theory. Materials and Methods: This paper proposes an innovative algorithm based on Stackelberg game theory to reduce interference among secondary users. MATLAB software is used to implement the algorithm. The algorithm is tested to find Signal to Interference noise ratio (SINR) of about 10 secondary users in CRN using novel Stackelberg game theory and compared with the SINR of Secondary users using Cournot game theory. Results: The Statistical analysis is done by performing Independent Variable test and T-test using SPSS software. The mean SINR is maximum for Stackelberg game theory (100.9±1 mdb), and the least SINR (13.11±1mdb) is seen for Cournot game theory. Conclusion: The algorithm based on Stackelberg game theory shows maximum SINR than the Cournot game theory. Since SINR is maximum Signal quality will be high and Interference will be less among the users due to which the network performance is improved.

A flexible wearable device with decoupled hydrophobic properties and sensing functions

The construction of hydrophobic coatings for flexible sensors is an effective way to improve the stability of sensors-based wearable devices. However, currently available fabrication methods produce coating layers with two simultaneous functions, causing the problem of mutual interference between functions. To independently regulate the two functions, a simple two-step dip-coating process was used in this study to construct independently hydrophobic coatings based on a porous template for sensing purposes. The as-constructed device showed good and independently adjustable hydrophobic (CA = 90°–135°) and sensing performances (GF = 2.5–20). Moreover, the as-obtained strain sensor effectively resisted acid and base corrosion, and displayed a good response to human motion. In sum, the proposed method looks promising for preparing flexible wearable device with decoupled hydrophobic properties and sensing functions.

A Large-Scale True Triaxial Apparatus with Rigid-Flexible-Flexible Boundary for Granular Materials

The true triaxial apparatus is applied to test the deformation properties of coarse soil under three principal stress loadings without mutual interference. In this paper, based on the true triaxial apparatus mechanism under a vertical rigid boundary and an orthogonal two-direction flexible boundary on the horizontal plane loading, the small-scale true triaxial instrument with a specimen size of 70 by 70 by 70 mm and 70 by 70 by 140 mm is further developed into a large-scale true triaxial instrument with a specimen size of 300 by 300 by 600 mm. The two characteristics of the chamber loading mechanism are the adjacent flexible hydraulic capsule isolated by the balance plate device and servo hydraulic loading with Proportional-Integral-Differential (PID) closed control algorithm. The problem of mutual interference between two orthogonal flexible capsules on the horizontal plane is solved by using the isolation balance plate device. PID closed control optimization algorithm is used to solve the stability problem of an automatic control system. Finally, to verify the effectiveness and accuracy of a large-scale true triaxial instrument, a series of coarse soil tests were carried out to investigate the strength and deformation characteristics of geotechnical materials.