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The temperature measurement system for switch gear based on surface acoustic wave (SAW) is gradually mature. The feedback frequency of the SAW chip represents the temperature measured by the sensor. However there is a common issue that the SAW chip feedback frequency will appear a deviation in temperature measurement after running for a period. This paper firstly research on the phenomenon of frequency deviation, then provide a method to compensate this deviation. Theoretical analysis and experimental results show the effectiveness of this method.

This paper describes the development and design of a novel online detector for condition monitoring of switchgears based on Modbus technology. The equipment is based on host-and-slave structure. Each salve module, which collects different sensed information such as mechanical condition, partial discharge and temperature, is installed on the target switch gear cabinet to comprehensively monitor all the connected switchgears in the substation. Once there is any potential faults happened, the defective switch cabinet can be automatically picked out by the host. Overall system construction and its practical application are proposed.

A transformer is one of the most important units in power networks. Its performance status will affect the safe and stable operation of the entire power system. Various stresses and faults present during the active service life of the transformer accelerate its ageing. It makes sense to accurately determine the operating state of the transformer. The operation performance of the transformer is affected by many aspects, including the original factory quality, operating environment and so on. In this paper, a state assessment method based on the whole life cycle of transformers is proposed. Taking the real field data of 15 working transformers for example, the proposed condition assessment model have been tested. The results obtained are not only accurate, but also flexible and easy. It shall prove to be very significant to the utility managers and power utilities.

There are many fuzzy problems in the power system, such as fault diagnosis, condition assessment, etc. Despite the rapid development of science and technology, uncertain and incomplete information still exists to varying degrees. These problems of ten involve multiple factors. It is very important to choose a suitable method to deal with such problems. In this paper, a new uncertainty algorithm is proposed based on fuzzy theory, rough set theory and evidence theory to solve the problem of multi-index uncertainty in power system. This algorithm can process inaccurate data and then analyze it. Taking the transformer state evaluation as an example, the application of this algorithm is illustrated.

Power transformer is key electrical plant in power system. This paper presents condition assessment of 330kV power transformers using assessment approach based on set-pair analysis theory. Condition indicators involving dissolved gas in transformer oil, electrical tests, and transformer accessories were used to assess the power transformer conditions. Then, condition assessment approach based on set-pair analysis theory and improved weight calculation method was located in the paper. Finally, the field data of a 330 kV power transformer were used to assess the power transformer state by the proposed approach. Assessment results show that it is correspond with the actual situation.

A generating system of very fast transient overvoltage (VFTO) and lightning impulse (LI) was established. The effects of voltage polarity, gas pressure and voltage waveform on discharge characteristics of SF 6 gas with and without insulators under VFTO and LI were investigated. Experimental results show that the 50% breakdown voltage of rod-plane gap under VFTO is higher than that under LI in positive polarity. However, for negative polarity, the breakdown voltage and voltage-time curve under VFTO fall below those under LI at the pressure of 0.5MPa. Moreover, the polarity effect of the rod-plane gap under LI is reversed at a certain pressure. The flashover voltage of defective insulator under VFTO can be lower than that under LI by near 10%. The flashover voltage is the lowest when the particle is attached on some position nearby high voltage electrode of insulator. The decrease of pulse rise time will increase the discharge channel number. It is concluded that the polarity effect is related with the distortion effect of ion clusters formed by SF 6 on electric field. The steepness and rise time of impulse play an important role in the initiation and further development of leader discharge in SF 6 and on insulator surface.

Gas discharge includes many pre-discharge current pulses with rise time of several nanoseconds and amplitude of several milliamperes. The breakdown current after pre-discharge process can reach up to several kiloamperes. To measure pre-discharge current safely and accurately, a novel current transducer should be developed. The scheme that a transient voltage suppressor (TVS) paralleled with self-integral resistor of Rogowski coil was adopted and a novel Rogowski coil with the function of overcurrent protection was designed. The parameters of integral resistor and overvoltage protection device were optimized by many experiments. The results showed that the integral resistor should decrease when the measuring sensitivity was satisfied, and the optimal value of resistance was 10Ω∼50Ω. The response time of overvoltage protection device should be smaller than rise time of measurement current. The distributed capacitance of TVS, which could not exceed 0.5nF∼1nF, should decrease when the peak current of Rogowski coil was larger than breakdown current of the circuit. The test results show that the newly developed Rogowski coil can measure current with a rise time smaller than 5ns and amplitude of several milliamperes accurately, and can also protect posteriori measuring equipment when large current up to several kiloamperes appears.

An automatic frequency tuning loop (ATL) for the low pass filter is fabricated in TSMC 0.18-μm CMOS technology for 400–800 MHz Spectrum Sensing. The whole ATL system employs a divide-by-four, a low pass filter, a phase-frequency-detector (PFD), charge pump (CP), a comparator and a successive approximations register (SAR) to calibrate the low pass filter of 400–800 MHz spectrum sensing system. The ATL provides 3.33% corner frequency accuracy. The ATL operates in the range from 207 kHz to 350 kHz, and the frequency steps are from 8 kHz to 10 kHz.

Dissolved gas analysis (DGA) has been approved as an accurate method to assess the insulation condition of power transformer. The ant colony optimization algorithm is competent to obtain the global optimum values of the support vector machine (SVM). This paper presents an approach of ant colony optimization SVM to recognize histograms of characteristic dissolved gas in transformer oil. DGA data of transformer oil with normal operation and four types of typical power transformer faults were selected, and characteristic dissolved gas were used to establish histograms. Statistical characteristic parameters involving mean, skewness and kurtosis, etc. were calculated as recognition features. Three approaches including IEC three ratio method, SVM and ant colony optimization SVM were used to diagnosis DGA of power transformer. Results show that the proposed approach can effectively improve the accuracy of the recognition for characteristic dissolved gas histograms compared with the other two methods.

Long-reach passive optical networks are one of the proposed solutions to the merging of access and metro networks into a single system for lowering deployment costs. As propagation delays increase proportional to the network range, new designs of scheduling and bandwidth distribution schemes need to be considered to mitigate its effects on overall packet delay. This paper presents an interleaved polling scheme for Ethernet Passive Optical Networks based on the well-known IPACT algorithm with Limited Service granting. The proposed algorithm takes advantage of the idle time gaps caused by heterogeneous propagation delays and bursty traffic, and utilizes an enhanced Limited Service granting scheme based on the packet delay approximation of ONUs. Simulation results show that the proposed scheduling and bandwidth distribution schemes achieve lower packet delays in providing multimedia services in long-reach EPON systems when compared to IPACT.

This paper reports the flux density measurements of 23 pulsar sat radio frequencies centered at 1540 and 4850∼MHz, using the new pulsar observing system PDFB (Pulsar Digital Filter Banks) mounted at the 25-m radio telescope at Xinjiang Astronomical Observatory. The new de-dispersion system PDFB is described and the method of calibration for pulsar intensity measurements are introduced. Spectra indices of these pulsars were given based on our measurement combined with previously published data at other frequencies.

As bearingless motors have all advantages of magnetic bearings; they play an important role in solving difficult problems of special electric drives. The simplest and most versatile form of bearingless motor is the bearingless slice rotor motor. This kind of motor with centrifugal pump has a wide range of applications in life science, chemical processing industry, semiconductor manufacturing industry, foodstuff processing industry, and so on. This paper presents the analysis of the operational principle, basic equations is given for a bearingless permanent magnet slice electromotor first. Then a modeling of a bearingless permanent magnet slice electromotor is built using Maxwell 3D of ANSOFT finite element software. Finally, the magnetic field and the torque force are analyzed for the two different structures of P B =P M ±1. According to the analytic results, the structure of P B =P M +1 is more steady. In addition; its control is easier to get in the actual implementation and application.

This paper focus on the digital control system for bearingless permanent magnet rotor motors. The bearingless permanent magnet synchronous motor (BPMSM) is an innovational type of motor, as bearingless motors have all advantages of magnetic bearings, they play an important role in solving difficult problems of special electric drives in life science, chemical processing industry, semiconductor manufacturing industry, foodstuff processing industry, and so on. In the paper, based on the basic working principle of BPMSM, the mathematics models of the radial forces and rotation part on BPMSM are deduced by adopting rotor magnetic field oriented control (FOC) strategy. A digital vector control system according to the demand of decoupling is designed and presented using DSP technique. An experimental platform of digital control system is developed to meet the need, The experiment results have shown that the steady suspension of the rotor is realized and the speed of the rotor can be continuously adjusted within the range of 0–3000 r/min.

As a popular way of entertainment, game has played an important role in our daily life, and more and more people have dreams to design some kinds of games by themselves. Thanks to the emergence of game engine, people's dreams come into reality. With the help of game engine, designing a game becomes easier, and the development time is also reduced considerably. This paper introduces an education-oriented game engine, named logical animation platform. The features of logical animation platform are presented, and the basic development process to design a game is summed up. The design process of an aircraft game is given as an example to demonstrate how to use the logical animation platform to develop games, and to show the advantages of the game engine. Finally, the future of the logical animation platform and game development are outlined.

Due to the desirable performance, polyphase codes have been widely used in low probability of intercept radar. By analyzing the characteristic of the time-frequency distribution of polyphase codes, a new parameter estimation method based on time-frequency distribution is proposed. Simulation results show that this method have good estimate precision even in low signal-to-noise ratios.

This document analyses the field evenness of the 150 mm Strip-Line Cell. Based on the international standards ISO11452–5 and CISPR-25, we selected suitable line lengths function as the equipments under test, compared the measurement results between CISPR-25 antenna method and the ISO 11452–5 strip-line method, then proposed the best usable frequency band for the Strip-Line automobile electronics EMI test.

Supporting a multimode mobile device to seamlessly switch its connections between various wireless access networks, such as WiMAX, Wi-Fi, and LTE, is an important research issue in 4G communications. The IEEE 802.21 working group defines the Media Independent Handover (MIH) standard to provide cross layer control and the information of network environment and services to optimize the handoff process. This work designs and implements the MIH middleware in a Linux platform to provide MIH event services (MIH-ES), MIH command services (MIH-CS) and MIH information services (MIH-IS). Based on the MIH software, we develop a high quality VoIP system which integrates Stream Control Transmission Protocol (SCTP), two MIH-IS based user motion detection (UMD) services and an adaptive QoS playout algorithm (AQP). The MIH services, multi-homing capability and dynamic address configuration extension of SCTP are applied in the VoIP system to perform seamless handoffs. Moreover, AQP adjusts the playout buffer by using the retransmission of partial reliable SCTP (PR-SCTP) and the MIH-ES to reduce the packet loss rate and improve speech quality. The experiment results indicate that MIH can enhance the performance of the handoff process and the quality of wireless VoIP services.

Web dynamic geometry intelligent drawing is of great significance in the network distance education, particularly in the geometry distance education. On the analysis of the mutual relation between elements of dynamic geometry graphics and methods on how to save graphics in text mode and also strategy of inducting intelligently, this paper realizes a intelligent drawing system of dynamic geometry based on Web, which uses B/S structure and Silverlight as the drawing technique, having basic functions such as drawing geometry graphics dynamically and intelligently. Storing and retrieving graphics are also discussed.

A parallel doubly coupled stepped impedance resonators (SIRs) structure is proposed in this paper to build a 2.4/5.2 GHz dual-band bandpass filter for a WLAN application. The prototype filter is a three-stage design composed by four SIRs in conjunction with the tapped-line used in the I/O ports to create zeros by the passband skirts. The proposed filter has the advantages of a much wider fractional bandwidth in both the passbands without sacrificing the passband's insertion losses. The conventional parallel-coupled microstrip line model is applicable in the proposed filter design. The filter has obtained almost twice wider bandwidth compared to that possessed by the counterpart filter of a conventional parallel-coupled line configuration. It is convinced that this filter design can be apply to the 2.4/5-GHz dual-band operation that needs a wider second passband. The experiment is conducted for filter performance validation. A very good agreement is observed between the simulation and the measurements.

This paper presents a new non-unit voltage protection algorithm for extra high voltage (EHV) transmission lines. This scheme is developed using wavelet analysis, in which the singularity of fault transient voltage signals in one terminal is utilized to discriminate clearly between internal and external faults. Lipschitz exponent (LE) is obtained from wavelet modulus maximum to detect singularity of signals. A typical 500-kV EHV transmission system has been simulated by ATP to evaluate the scheme. The simulation results show that this scheme is capable of providing correct responses under various system configurations and fault conditions

This paper takes a linear least-squares approach to develop a procedure for reducing effects of environmental luminance and turbidity on underwater imaging. The first step is to divide all pixels in each row of the original image to several data sets. Each data set is fitted to a straight line by the least-squares error method. Once each row has been processed, the profile of the row estimate is saved as a new image. The next step is to fit all pixels in each column of the new image by repeating the least-squares error process. Then the profile of the column estimate will provide a better imaging quality than the original one if values of the design parameters are properly assigned. As an example of an optical triangulation system, this paper carried out a series of DOE process runs to study effects of the design parameters on quality of range finding. To make the numerical technique robust against noises, both environmental luminance and turbidity are forced into the experiments by utilizing an outer array. From results of experiments and ANOVA, it is concluded that the sampling range utilized for peak detection, the number of line segments in each row, and the overlapping ratio of adjacent lines in each row are influential on changing quality of range finding.