Xiu Zhang

• Western Academy of Beijing

The professional development of teachers is crucial for the education development of a country. For understanding the core qualities and ability development of teachers, it is very important to identify the associated influencing factors. In this paper, an improved genetic algorithm is used to find out the significant influencing factors among the...

This paper analyzed an orthogonal wireless power transmission (WPT) model which can transmit energy in all directions in space. In this paper, the orthorhombic transmission structure was divided into eight regions, and the working mode of the receivers in different regions was explored to obtain the highest energy when the three inputs are in phase...

Remote center of motion (RCM) constraint has attracted many research interests as one of the key challenges for robot-assisted minimally invasive surgery (RAMIS). Although it has been addressed by many studies, few of them treated the motion constraint with an independent workspace solution, which means they rely on the kinematics of the robot mani...

Electronic wireless equipment will produce electromagnetic interference, which can affect the surrounding environment and the normal operation of other equipment. This paper builds basic model of wireless energy transmission and electromagnetic shielding model, and analyzes the influence of structure and material of electromagnetic shielding to the...

Higher requirements must be put forward about wireless signal transmission in harsh environments. Energy loss mitigation, channel estimation, noise interference reduction demands high quality of service in wireless communication. In the fifth generation wireless communication, massive multiple-input multiple-output (MIMO) networks have been used an...

In order to better understand and optimize the learning process and learning environment, educational data mining technology is becoming more and more important in processing a large number of educational data. Through the analysis of large amounts of educational data, students' academic performance is predicted, identifying a “high risk” of droppi...

With the rise of artificial intelligence, machine learning methods have been widely used in more and more fields. The main content of this chapter is the application of machine learning methods in teacher award prediction problem. The content of this chapter is mainly divided into five parts: The first part mainly introduces the development status...

The Internet of Things (IoT) is a huge network consisting of various information-sensing devices combined with the Internet. The IoT aims to connect all things with the network to facilitate identification and management. The increasing number of things, connections and volume of data is challenging the reliability and sustainability of the IoT. To...

The technology of wireless power transfer (WPT) has broad applications especially in implantable biomedical devices. Because of the limitation of the size of the receiver coil, how to lengthen the power transfer distance is crucial in biomedical applications. In order to address this problem, in this paper, a novel three-coil WPT system is proposed...

In recent years, wireless power transfer technology has been recognized by users for its unique advantages such as convenience and distance transfer. It has been popularized in life and developed rapidly. The paper designs a wireless power charging system with two kinds of charging modes. The system mainly includes an electricity grid charging modu...

In order to detect the safe driving area in a non-invasive and accurate way in practical application, the architecture of three-dimensional inverse opal (3DIO) ZnO and molecular sieve modified 3DIO ZnO gas sensor are prepared by simple controllable sacrifice template method. Its morphology is characterized by scanning electron microscopy (SEM) and...

Wireless power transmission (WPT) technology has been applied to many areas that driven by batteries. WPT system based on coupling coils is a popular method to realize WPT. In general, two coils are used in such system including a transmitting coil and a receiving coil. Two coils have to reach the same resonant frequency and impedance matching to a...

In wireless and mobile communication, wireless spectrum is a limited and scarce resource. Properly allocating spectrum resource to different users is an important goal to meet the communication needs of people. The spectrum allocation problem in cellular network scenarios is studied in this paper. The network utility performance is assessed by two...

Due to the continuous development and progress of wireless communication technology and sensor network technology, wireless sensor networks (WSNs) have gradually become an attractive technology that facilitates people's lives. Due to the extensive use of WSNs, maximizing the lifetime of WSNs to obtain real-time and effective information has become...

In this paper, the double negative metamaterial is designed and analyzed using finite element method. Most of the structure of metamaterial is applied in radar stealth technology and superlens. Compared with the traditional material, the metamaterial can focus on electromagnetic waves, which can improve the wireless power transfer (WPT) system. In...

Microstrip antenna has been designed and applied to many practical scenarios for wireless communications. To meet increasing requirements of wireless communication and quality of service, array antenna design deserves studying and analyzing. A novel design of 2.45-GHz microstrip array antenna has been proposed in the paper. The novel array antenna...

Resource allocation is very important in mobile communication. This paper studies the assignment of spectrum in cellular networks operated on orthogonal frequency division multiple access (OFDMA) system. Both network utility and fairness among all linked users are taken to measure quality of service in cellular networks. The problem is expressed as...

The left-handed material (LHM) composed of a combination of magnetic and electrical resonator is an important method for designing the structure of the LHM. In this paper, a novel structure of LHM is designed and analyzed based on the traditional LHM structure. The parameter extraction method is applied to calculate the effective dielectric constan...

Abstract Massive multiple input multiple output (MIMO) has drawn intensive attention of researchers for solving huge data transmissions in the fifth generation wireless communication. Antennas aligning in array bring in advantages for interference reduction of incoming wave signals and interference offset among antenna elements. The design of anten...

Antenna array has been extensively applied to wireless communication systems. Optimal design of antenna array is very useful to attain desired spatial beam and reduce signal degradation. Potential search directions in artificial bee colony (ABC) algorithm are mixed with both large step size and small step size. This could lead to the malfunction of...

The Internet of things (IoT) provides a beautiful and intelligent landscape for humanity’s future. The connections of various sensors and devices in the IoT result in a large consumption of energy. Therefore, research on energy saving and energy efficient methods is imperative. For wireless sensors in an IoT network, sustainable operation in an ene...

The technology of wireless power transfer (WPT) is used to transfer the power wirelessly through the magnetic field in the space and to charge the electrical equipment such as computer, mobile phone, electric vehicle, implantable medical devices. During the process of transmission, the radiation of magnetic field will reduce the systems’ efficiency...

As the degree of dependence on the mobile equipment such as smart phones, smart watches, wearable equipment, is more and more serious, the battery seems to be the restricts for people. In order to overcome the battery technology bottleneck, one method is quick charge, and the other method is wireless charging. However, quick charge often impacts th...

Along with the progress of the technology, people have an increasing demand of electricity. In the process of power transmission, the copper loss and wire aging will bring hidden trouble to the equipment. On special occasions, such as mining engineering and underwater working, the traditional power transmission system with wire will lead fatal harm...

Sorptive barrier technology is a recently developed tool to separate hazardous contaminants from friendly environment. The design of sorptive barrier refers to configuring different amendments with sorptive ability of organic pollutant, which is an integer programming problem and a relatively time consuming problem as well. In this paper, sorptive...

Different from the traditional electromagnetic material, the electromagnetic metamaterial has tremendous application potential in antenna designing, superlens and stealth fields because of its negative properties in permeability and/or permittivity. In this paper, a novel structure of electromagnetic metamaterial with middle-frequency band is desig...

Spectrum access and assignment in cognitive radio networks are hot topics in wireless communications. Dynamic spectrum access and assignment could greatly improve spectrum resource efficiency and help to satisfy the explosively increasing communication demands of wireless devices. The problem of spectrum access and assignment in an underlay cogniti...

Differential evolution (DE) has been extensively studied in the past decade, though researchers may ignore the effect of an archive storing previous search information. Moreover, boundary repair issue is seldom handled in the literature. This paper attempts to improve the performance of DE algorithm from these two aspects. First, a differential vec...

Massive multiple input multiple output antenna array is crucial for the fifth generation wireless communication. Proper antenna array design can reduce interference among different signals and generate desirable beamforming. Sparse antenna array is able to form narrower beam with lower sidelobe than equally spaced antenna array given the same numbe...

Optimal design of antennas is very useful to attain narrow beam and low sidelobe, while keeping a low manufacturing cost. Artificial bee colony algorithm (ABC) has shown good performance in solving electromagnetic inverse problems. However, the ABC algorithm costs too much number of iterations and converges slowly in antenna design. This paper prop...

Reliable communication is a key factor in the development of the fifth generation wireless communication systems. To achieve reliable communication, designing desirable antenna arrays is the basis so as to realize wireless data transmission. Artificial bee colony (ABC) algorithm has shown its powerfulness in engineering design problems, though the...

Artificial bee colony (ABC) algorithm builds on simulating the intelligent behavior of honey bees. It shows good performance in many applications. As standard ABC algorithm does not employ any crossover operator, the dispersal of good genetic information amongst the solutions is undermined. In this paper, the impact of crossover operators on the pe...

This article has been withdrawn at the request of the editor and publisher. The publisher regrets that an error occurred which led to the premature publication of this paper. This error bears no reflection on the article or its authors. The publisher apologizes to the authors and the readers for this unfortunate error. The full Elsevier Policy on A...

A three-dimensional inverse opal (3DIO) WO3 architecture has been synthesized via a simple sacrificial template method. Morphology features of the 3DIO were characterized by scanning electron microscope (SEM) and its structure was characterized by X-ray diffraction (XRD). The shrinking ratio of the PMMA spheres was ~28.2% through measuring the dist...

Proportional-integral-derivative (PID) controllers are the most popular control systems equipped in industries due to their simplicity, effectiveness, and functionality. In this article, an adaptive differential evolution (DE) algorithm is presented to tune controller parameters of PID systems. The proposed algorithm uses shift based parameter cont...

Wireless power transfer (WPT) technology has many applications by virtue of its intrinsic safety and convenience characteristics. This is particularly so when the WPT systems are used in conjunction with implanted medical devices, as they can greatly reduce the pain of patients and their financial burdens. In previous researches, the optimal system...

Left-handed material (LHM) is also known as the double negative medium. This paper put forward a novel structure of LHM with equal magnetic and electric resonance frequency, it realized the overlap between electric and magnetic resonant frequency according to structure element coplanar coupled. After simulation, we find the novel structure material...

The traditional method to obtain the response of electromagnetic devices over a wide frequency range is to use a frequency sweeping method. However, this method is very time consuming, especially in time-domain analysis. In order to save the heavy computational time, a novel fast algorithm based on finite-element method (FEM) to obtain the response...

An effective non-revisiting artificial bee colony (NrABC) algorithm based on the paradigm of artificial bee colony (ABC) is developed in this paper. NrABC is applied to tackle the synthesis of phased linear arrays. Pros and cons of NrABC is provided along with a comparison to standard ABC. Binary space partitioning tree structure is used to record...

Electromagnetic (EM) inverse problems are usually modeled as simulation-based optimization problems with multimodal and non-differentiable properties. These properties justify the invention of more effective optimization algorithms. Artificial bee colony (ABC) has already been applied to tackle EM inverse problems. This paper applies a tree structu...

As an artificial material, the metamaterial has great applications in radar, stealth and electronic countermeasure because of its special electromagnetic properties. Considering its negative permittivity and negative permeability, the metamaterial is applied in wireless power transfer system to improve its performance. In this paper, a novel struct...

Cognitive radio (CR) networks have drawn great attention in wireless communication fields. Efficient and reliable communication is a must to provide good services and assure a high-quality life for human beings. Resource allocation is one of the key problems in information transmission of CR networks. This paper studies power allocation in cognitiv...

To accomplish reliable and efficient information routing, strong paths connecting all nodes are required in vehicular ad hoc networks (VANETs). Classical algorithms in graphic theory could find only one minimum spanning tree (MST) in VANETs. Swarm intelligence paradigms are able to obtain several alternatives to MST, which is useful for improving r...

Vehicular ad hoc networks (VANETs) have drawn great attention in wireless communications. Prompt and reliable vehicular communication is a must to provide a good service. Routing is the key problem in information transmission of VANETs. This paper studies quality of service (QoS) constrained multicast routing problem. This problem has been proved t...

The key of wireless power transfer technology rests on finding the most suitable means to improve the efficiency of the system. The wireless power transfer system applied in implantable medical devices can reduce the patients’ physical and economic burden because it will achieve charging in vitro. For a deep brain stimulator, in this paper, the tra...

When designing radar, mobile, or satellite communication systems, optimization problems often come out and need to be handled to accomplish certain requirements. Polyphase code design and circular antenna array design problems are considered in this paper. To deal with the two problems, a novel artificial bee colony (ABC) algorithm is proposed. A p...

Waveform design and diversity is the technology that allows one or more sensors (e.g., radar or radar sensor networks) on board a platform to automatically change operating parameters, e.g., frequency, gain pattern, and pulse repetition frequency, to meet the varying environments. Optimization problems in the design of radar waveforms such as polyp...

The key of wireless power transfer technology rests on finding the most suitable means to improve the power transfer efficiency when the transfer distance is extended. In this paper, a new shape of transmitter coil, which is developed as part of a deep brain stimulator for stroke patients, is proposed. Because the receiver coil to be implanted in t...

When designing a radar system based on pulse compression technique, optimization problem needs to be handled to achieve a good system efficiency. Polyphase code is a popular method to implement pulse compression. To deal with the design problem, a novel artificial bee colony (ABC) algorithm is proposed which includes a population reduction method a...

This paper proposes a novel artificial bee colony (NABC) algorithm for handling electromagnetic inverse problems. NABC consists of a one-position inheritance scheme, a neighborhood-based onlooker bee phase, and a history-driven scout bee phase. All components are designed to accelerate the convergence and improve the performance of standard ABC. Ex...

The doubly fed dual-rotor flux-modulated (DFDRFM) machine is a promising electrical continuously variable transmission (E-CVT) concept for the hybrid electric vehicles as it has two mechanical ports and two electrical ports, which are highly desirable for E-CVT. In this paper, a novel DFDRFM machine is proposed. Compared with previous designs, the...

Synchronous machines (SMs) have wide applications in many areas including industrial, agricultural, and domestic. The torque-load angle relationship is an essential parameter governing the characteristics of SMs. Conventionally, for each load angle, a transient magnetic field model using the time-domain finite element method (FEM) needs to be solve...

Design of electromagnetic devices has multimodal, multidimensional, and constrained characteristics. Metaheuristic approaches are good choices for tackling these design problems owing to their simulation-based property. As many electromagnetic design problems require a long computing time to solve (even on modern computers) and many heuristic appro...

In the design of electric devices, the designers are usually required to extract the equivalent circuit parameters of electromagnetic fields at different frequencies. A traditional method is to solve a frequency-domain problem of eddy-current fields using FEM and to calculate the parameters in postprocessing. To obtain the parameters at different f...

Optimal design problems of electromagnetic devices are generally multimodal, nondifferentiable, and constrained. This makes metaheuristic algorithm a good choice for solving such problems. In this paper, a newly developed metaheuristic algorithm is presented to address the aforementioned issues. The proposed algorithm is based on the paradigm of ar...

A multi-slice finite element model for wireless magnetic resonant energy transfer systems with circular spiral tape coils is presented. As the system is constructed using distributive capacitance, it is difficult to determine the parameters in the equivalent circuits analytically. To address the aforementioned problem, a multi-slice axisymmetric fi...

Applications of magnetic-resonant wireless power transfer technology have been extensively researched because of its high efficiency, security and convenience. To recharge batteries, the induced ac voltage in the receiver coil of wireless systems must be rectified to dc, hence the power transfer systems are inevitably nonlinear. In this paper, a no...

A hybrid optimal design strategy for wireless magnetic-resonant charger of deep brain stimulation devices is presented. It is proposed that a differential evolution algorithm with discrete variables (turn numbers of coils) and constrains (induced current and voltage in the load loop) is used to design the wireless power transfer system. The variabl...

A novel and general method to quickly obtain frequency-domain solutions based on one or a few time-domain solutions is presented. The time-domain solution of electromagnetic field is found by using either two-dimensional (2-D) or three-dimensional (3-D) finite-element methods (FEM). The time-domain FEM is first used to obtain a solution for step fu...

A fast algorithm for finding the frequency-domain solutions of electromagnetic field computation using time-domain finite-element method (FEM) is presented. Base solutions, which are time-domain solutions when the excitations are substituted by step functions, are computed first using time-stepping FEM in time domain. Then, based on these base solu...

Wireless power transfer systems are finding increasing applications which can enhance the living standard of the general public. Typical examples are wireless charging of mobile phone batteries and car batteries. Thanks to the advent of power electronics in the past few decades, some wireless charging systems are now emerging in the commercial sect...

The technology of wireless power transfer has made a great contribution to the quality of life of many people, especially to those relying on implantable devices in the past decades. In order to improve the performance of wireless power transfer systems, a dual-layer nested optimization method using differential evolution (DE) algorithm is proposed...

Magnetic resonant wireless power transfer (MRWPT) is a developing technology to transfer power over a relatively long distance. It offers a promising solution in avoiding costly and risky battery replacement surgery in bio-implantable devices. One of the obstacles of the application of this transfer technique is that its efficiency is not satisfact...

With the advent of electronic technology, researchers are devoting increasing interests to wireless power transfer methods. Generally finite-element method (FEM) is a powerful tool for numerical simulation of such systems. Due to the relatively high operating frequency, the presence of inductance and distributed capacitance in the system as well as...

A novel error estimator for adaptive mesh refinement in finite element analysis (FEA) of magnetic field using quadratic finite elements is presented. The method uses a novel heuristic a posteriori error estimator, which is easy to compute and simple to implement, as an indicator of the numerical errors of the computed solution. The proposed error e...

A numerical method for analyzing eddy current magnetic field in high-speed moving conductors using local discontinuous Galerkin (LDG) method is presented. A typical numerical example is chosen to illustrate the accuracy and nonoscillatory nature of the method for a convection dominated case. The simulation results using the proposed algorithm are v...

An emerging technology of wireless power transfer technique based on electromagnetic resonant coupling, also known as witricity, has been drawing a lot of attention from academia as well as from practitioners since it was reported in 2007 by a group of researchers from the Massachusetts Institute of Technology (MIT). In this paper, a prototype with...

A large number of studies reveal that repetitive TMS (rTMS) can have strong influences on cortical functions, even though the effect is very dependent on the stimulation parameters. At the same time, it is commonly acknowledged that acupuncture plays an important role in traditional Chinese medicine, and it is indeed receiving more and more attenti...

Magnetic stimulation has become a very topical research area in bioelectromagnetics studies. One of the major problems in understanding the observed changes in biological systems resulting from exposures to magnetic fields is the relationship of biological changes to physical processes. It is well known that acupuncture has many varied physiologic...

As an emerging technology of wireless power transfer, an electromagnetic resonant coupling technique, also known as witricity, has been widely discussed. In this paper, a prototype with square planar spiral structure based on witricity is proposed. To compute the resonant frequency, an equivalent circuit model is presented. The inductance is calcul...

Magnetic stimulation has become a very topical research area in brain studies because of its non-invasiveness, painlessness and security. It is well known that acupuncture has many varied physiologic effects on a number of functional systems of human subjects. In this paper, the EEG is recorded while the acupoint of Zusanli (St36) is stimulated by...

Transcranial magnetic stimulation (TMS) is a powerful, non-invasive tool for investigating functions in the brain. The target inside the head is stimulated with eddy currents induced in the tissues by the time-varying magnetic field. TMS has been used in several applications in medical and clinical research which include brain mapping, treatment of...

To investigate the relationship of electroencephalographic activities and transcutaneous magnetic stimulation at acupoints. Three healthy male volunteers participated in this study. 64-channel electroencephalogram was recorded and its power spectrum was analyzed during sham magnetic stimulation and during real magnetic stimulation. Slow-wave compon...