Recent Advances in Electrical & Electronic Engineering - Volume 14, Issue 1, 2021

Background: In order to solve the safety hazard of computer network security, a special congestion control strategy is adopted. Methods: This strategy is used to discuss the design and implementation technology of a network adapter, a bridge, concentrator, a device driver, Netware interface software, and a complete set of FDDI optical fiber computer networks. The following functions i.e. source address tracking, frame forwarding, frame format conversion, spanning tree protocol, and other functions were achieved. Results: The research shows that the Sunrays micro-computer follows the SNMP simple network management protocol, which can support multiple Ethernet protocols and multiple ports, and the number of ports is scalable. Conclusion: The proposed method is useful for the multiple input and output ports in a computer network with security enabled congestion control for data traffic.

Background: Min-min and max-min algorithms were combined on the basis of the traditional genetic algorithm to make up for its shortcomings. Methods: In this paper, a new cloud computing task-scheduling algorithm that introduces min-min and max-min algorithms to generate initialization population, selects task completion time and load balancing as double fitness functions, and improves the quality of initialization population, algorithm searchability and convergence speed, was proposed. Results: The simulation results proved that the cloud computing task-scheduling algorithm was superior to and more effective than the traditional genetic algorithm. Conclusion: The paper proposes the possibility of the fusion of the two quadratively improved algorithms and completes the preliminary fusion of the algorithm, but the simulation results of the new algorithm are not ideal and need to be further studied.

Background: Mass movement trajectory data with real scenarios has been evolved with big data mining to solve the data redundancy problem. Methods: This paper proposes a parallel path based on the Map Reduce compression method, using two kinds of piecewise point mutual crisscross, the classified method of trajectory, and then segment trajectory distribution to multiple nodes to parallelize the compression. Results: Finally, the results based on both compression methods have been simulated for the different real-time data by merging both techniques. Conclusion: The performance test results show that the parallel trajectory compression method proposed in this paper can greatly improve the compression efficiency and completely eliminate the error caused by the failure of the correlation between the segments.

Background: Background: To improve the information efficiency in web text mining, filtration is utilized. Methods:A web content mining technology based on web text mining, augmented information support (AIS), is proposed for improving the web text mining efficiency. Additionally, the AIS technology is applied to the Xiangshan science conference website, and AIS4XSSC text mining system is developed. The developed system is tested for its efficiency, and its main functions are discussed. Results: 192 documents are represented by 8352 vectors, and 192x8352 vectors are obtained; the similarity between 192 vectors is calculated using the cosine of the included angle, 192x192 symmetric matrix is obtained, and 35 categories are formed by hierarchical clustering by using similarity between texts. Conclusion: The results show that the AIS technology can effectively extract information from a large number of web texts. The proposed system improves information retrieval efficiently and can provide valuable information to users.

Background: In the recent era of technology, the traditional Ant Colony Algorithm (ACO) is insufficient in solving the problem of network congestion and load balance, and network utilization. Methods: This paper proposes an improved ant colony algorithm, which considers the price factor based on the theory of elasticity of demand. The price factor is denominated in the impact on the network load which means indirect control of network load, congestion or auxiliary solution to calculate the idle resources caused by the low network utilization and reduced profits. Results: Experimental results show that the improved algorithm can balance the overall network load, extend the life of path by nearly 3 hours, greatly reduce the risk of network paralysis, and increase the profit of the manufacturer by 300 million Yuan. Conclusion: Furthermore, the results show that the improved method has great application value in improving network efficiency, balancing network load, prolonging network life and increasing network operating profit.

Background: At present, China's logistics industry is trying to change from laborintensive to technology-intensive, from the traditional model to modernization, intelligent upgrade, accompanied by the application and popularization of various advanced technologies and equipment. Nowadays, intelligent robots with functions such as handling, stacking, and sorting have become a hot topic in the logistics industry. To solve the problem of labor costs increase the logistics demand of logistics, improve the efficiency of processing of materials, the authors have designed main STM32F427 microcontroller chip, with smooth, round of omnidirectional mobile platform of vehicle chassis, external collision distance sensor, gyroscope and infrared sensors, temporary storage, and transportation of goods such as multi-functional integrated logistics robot. Methods: According to the actual application requirements, the mechanical structure of the logistics robot, the hardware, and the software of the control system is designed. Results: The experimental results show that the transportation and storage of materials in specific sites are well realized. The grasping and releasing accuracy and the positioning accuracy of the robot are relatively reliable. The study of the behavior of average tracking accuracy and average obstacle avoiding capability is the major contribution in this paper. Conclusion: The experimental results fully prove that the robot designed in this paper has many functions, high intelligence, and strong practicability.

Background: In order to obtain reliable cloud resources, reduce the impact of resource node faults in cloud computing environment and reduce the fault time perceived by the application layer, a task scheduling model based on reliability perception is proposed. Methods: The model combines the two-parameter weibull distribution and analyzes various interaction relations between parallel tasks to describe the local characteristics of the failure rules of resource nodes and communication links in different periods. The model is added into the particle swarm optimization (PSO) algorithm, and an adaptive inertial weighted PSO resource scheduling algorithm based on reliability perception is obtained. Results: Simulation results show that when A increases to 0.3, the average scheduling length of the task increases rapidly. When it is 0.4-0.6, the growth rate is relatively slow. When greater than 0.8, the average scheduling length increases sharply, it can be seen that the r-PSO algorithm proposed in this paper can accurately estimate the relevant parameters of cloud resource failure rule, and the generated resource scheduling scheme has better fitness, and the optimization effect is more significant with the increase in the number of tasks. Conclusion: With only a small amount of time added, the reliability of cloud services is greatly improved.

Background: To solve an electric power enterprise for a safe operation of power systems. Methods: A data acquisition technology based on multi-thread mechanism of data collection technology is proposed; its application may provide a data acquisition rate of 1832/min and an update cycle of approximately 30 s to ensure efficient and reliable performance on a large-scale electric power realtime data acquisition. Results: A power state index diagnosis algorithm is designed. Conclusion: The on-line real-time diagnosis of the current operating state for the power system is realized, and its importance is given.

Background: In order to study the interference of wired transmission mode on robot motion, a mobile robot attitude calculation and debugging system based on radio frequency (RF) technology are proposed. Methods: Microcontroller STM32 has been used as the control core for the attitude information of the robot by using MEMS gyroscope and accelerometer. The optimal attitude Angle of the robot is calculated through nRF24L01, which is the core of the wireless communication module, attitude acquisition module and wireless data communication upper computer application platform. Results: The results show that the positioning accuracy is better than ± 5mm. Conclusion: The experimental results show that the proposed attitude solving and debugging system of mobile robot based on RF technology has better reliability and real-time performance. The propped model is convenient for the debugging of the mobile robot system and has certain engineering application value.

Background: Patch antennas are composed of the substrate material with patch and ground plane on both sides of the substrate. The dimensions and performance characteristics of the antenna are highly influenced by choice of the appropriate substrate depending upon the value of their dielectric constant. Generally, low index substrate materials are used to design the patch antenna, but there are also some of the applications, which require the implementation of patch antenna design on high index substrates like silicon and gallium arsenide. Objective: The objective of this article was to review the design of antennas developed on high index substrate and the problems associated with the use of these materials as a substrate. Also, main challenges and solutions have been discussed to improve the performance characteristics while using the high index substrates. Methods: This review article is divided into various sections, including the solution of the problems associated with the high index substrates in the form of the micro-machining process. Along with this, types of micro-machining and its applications have been discussed in detail. Results: This review article investigates the various patch antennas designed with micro-machining technology and also discusses the impact of the micro-machining process on the performance parameters of the patch antennas designed on high index substrates. Conclusion: By using the micro-machining process, the performance of the patch antenna improves drastically, but fabrication and tolerances at such minute structures are very tedious task for the antenna designers.

Background: Brushless DC motors are highly efficient motors due to their high torque to weight ratio, compact design, high speed operating capability and higher power density. Conventional Hall sensor based rotor position sensing is affected by the heating, vibration, interference and noise. Objective: The innovative, cost-effective and easily implementable sensorless techniques are essential in order to achieve high efficiency, reduced current and reduced torque pulsations. Furthermore, a delay free, high load fast startup is also an important issue. Methods: In this paper, an extensive review of various techniques based on the detection of freewheeling diode current, phase back EMF zero crossing point detection, back EMF integration method and third harmonic back EMF was done. The effect of various PWM strategies on back EMF detection were studied. Later on, the sensorless schemes based on flux linkage estimation and flux linkage increment were introduced. The load torque observers, unknown input observers, sliding mode observers, L∞- induced observers, H∞- deconvolution filter for back EMF estimation were also reviewed. As the brushless DC motors have no back EMF at starting and for back EMF based commutation, minimum speed is required for sufficient back EMF. Therefore various strategies of an open and close-loop reduced current startup have been studied to achieve effective commutation without reverse torque. Initial Position Detection (IPD) schemes, which are mostly based on saliency and current response to inductance variation, are effective where reverse torque is strictly prohibited. A detailed review of these Initial Position Detection techniques (IPD) has also been presented. Results: The detailed mathematical and graphical analysis has been presented here in order to understand the working of the state-of-the-art sensorless techniques. Conclusion: The back EMF detection using direct and indirect methods of terminal voltage filtering has the problem of delay and attenuation. PWM noise, freewheeling diode spikes and disturbance in detected back EMFs are also major drawbacks. The problems such as, parameter detuning, underestimation and overestimation, offset problem, system noise and observer gain variation, etc. limit the applicability of observer based technique. Therefore, a more robust and precise position estimation scheme is essential.

Background: Electrical trees can affect the distribution of electric field and space charge in cross-linked polyethylene (XLPE) cables, and play an important role in insulation aging and breakdown of cables. Therefore, it is important to study the influence of electrical trees in cables. Methods: In this study, the finite element method of second-order tetrahedral element and electromagnetic theory method is used for calculation. A model of XLPE cable with three-dimensional electrical trees is taken as an example for calculation. Results: The results show that the longer the trunk length is, the greater the electric field intensity at the end of the branch is; the farther the electrical trees are from the insulation side of the high voltage, the more the electric field intensity of each location decreases. Conclusion: With the increase of the resistivity of the trees, the electric field intensity and charge density tend to be stable at the end of the tree.

Background: Community detection is significant for the understanding of the structure and function of networks, and becomes an attractive topic for researchers. However, many existing local methods only focus on disjoint communities and some recently proposed overlapping community detection methods are global methods with high computational cost. Objective: To improve the accuracy and speed of community detection and obtain the fuzzy coefficients of overlapping nodes with low computational cost, a local fuzzy agglomerative method is proposed in this paper. Methods: In the detection process, each local community is determined based on community strength. The overlapping communities and fuzzy coefficients of nodes are obtained by coordinating and normalizing the contribution of the overlapping nodes to their belonging communities. Results: Theoretical analysis and data simulations show that our local method can detect disjoint and overlapping communities in linear time with the network size. The overlapping communities and the fuzzy coefficients of overlapping nodes are obtained accurately. Conclusion: The accuracy of our method is higher than the existing local methods for detecting disjoint communities. And it also detects the overlapping communities same as the global overlapping methods but with remarkably low computational cost.