Nowadays, the most widely used method for estimating location of autonomous vehicles in real time is the use of Global Navigation Satellite Systems (GNSS). However, positioning in urban environments using GNSS is hampered by poor satellite geometry due to signal obstruction created by both man-made and natural features of the urban environment. The presence of obstacles is the reason for the decreased number of observed satellites as well as uncertainty of GNSS positioning. It is possible that in some sections of the vehicle route there might not be enough satellites necessary to fix position. It is common to use software for static GNSS measurement campaign planning, but it is often only able to predict satellite visibility at one point. This article presents a proposal for dynamic GNSS mission planning using a Digital Terrain Model (DTM) and dead reckoning. The methodology and sample results of numerical experiments are also described. They clearly show that proper dynamic GNSS mission planning is necessary in order to complete a task by an autonomous vehicle in an obstructed environment.

Dynamic GNSS Mission Planning Using DTM for Precise Navigation of Autonomous Vehicles

With the incessant expansion of applications and the frequent update of the software, Science Gateway for Massive Remote Sensing Image Processing (SGMRSIP), developed by client/server model or traditional browser/server model, has received more and more challenges. Fortunately, the Web 2.0 technologies, proposed in recent years, bring us a new user experience (UE) that has a fast response speed and a good interface. In particular, the remote sensing image can be processed smoothly in the absence of client software by Web 2.0 technologies. Hence, a Web 2.0-based browser/server model is designed for SGMRSIP to enhance the UE in this paper. Firstly, functions of a parallel remote sensing image processing portal, based on high performance cluster and client/server model, are summarized. And then, a Web 2.0-based interaction model is built, and all these functions are accomplished again on the basis of this model. Finally, the Web 2.0-based Science Gateway is achieved. In addition, we design different workflows for different satellite data, and all the processing tasks are finished successfully to verify the feasibility of this Science Gateway. The experimental results showed that the software scalability and interaction were improved and a better UE was achieved, compared with the existing SGMRSIP. Copyright (c) 2013 John Wiley & Sons, Ltd.

A Web 2.0‐based science gateway for massive remote sensing image processing

The concept of a regional information-analytical system for emergency situations is presented. The three-level architecture of such a system and the functions of its main components are described. A generalized model for assessing plans for eliminating the consequences of emergencies is described. The goals and peculiarities of the structural modules for the regional information and analytical system for the prevention and elimination of emergencies are detailed; some examples of the implementation of local subsystems for Ukraine are considered.

The Concept of a Regional Information-Analytical System for Emergency Situations

The realization of automatic frequency tracking is of great significance in ultrasonic transducer due to its wide application area in nowadays industrial manufacture. However, excessive overshoot current, serious overheating and long response time remain the urgent issue. To tackle these existing ultrasonic frequency tracking problem, this paper proposes a hybrid technique that integrates fuzzy control theory with PID control on the system. The technique involves coarse adjustment by fuzzy control and accurate adjustment by PID. Then, direct digital synthesizer (DDS) is used to generate required PWM wave with high accuracy. Initial driving frequency of the system and its corresponding phase difference of the feedback voltage and current can both be acquired during sweep frequency test before the tracking process, which corresponds to the parallel resonant point where the current is the minimum. This phase difference is also regarded as the target tracking value. During the tracking process, fuzzy control will be adopted when phase difference value error between feedback value and target value is greater than 10%, or PID will be used. Current difference AI and change rate AI/Af are used as two input values while driving frequency is the output value in fuzzy control when coarse adjustment is needed. Incremental PID arithmetic is used when accurate adjustment is needed. The result shows that the technique can reduce overshoot current of the ultrasonic transducer by approximately 8%, shorten the time for achieving stabilization of the system by 12%. In conclusion, this novel hybrid technique can quickly and stably track the frequency of parallel resonant point of the ultrasonic transducer system, meanwhile keep the whole system operating more efficiency and stable.

An improved frequency tracking strategy in ultrasonic transducer

The resonance characteristics of ultrasonic transducer are analyzed based on the equivalent circuit of transducer and the quantitative calculation of admittance circle, and a control method of frequency tracking based on variable step length is proposed, and the limits of step switching are deduced, and the control parameters of the control method based on variable step length is designed in this paper. The results of simulation and experiment show that the system based on the control method can control output frequency in high precision. And while ultrasonic power supply ensure steady-state error minimum, holding a good dynamic performance, which meets the requirements of the technology of ultrasonic power supply.

http://ieeexplore.ieee.org/iel7/7027308/7037809/07037889.pdf

The research on phase lock method of ultrasonic power supply with variable step length control

In this paper, a new type of intelligent high-power ultrasonic power supply based on Digital Signal Processor (DSP) has been developed. According to the characteristic of ultrasonic power supply, the control system software has been programmed. It deals mainly with the drift of the slow frequency for the resonance frequency search module in whole and the frequency automatic tracking module deals with the small transient frequency change. This module is executed in each sampling period. In order to keep fast track the mutations resonance frequency, we has taken strategy in a variable step length in the program module. The further, it improves the stability of the control system. On-line testing shows that, this ultrasonic power supply based on DSP can make the system work at the resonance state, and the vibration process is stable. Both the hardware and software can achieve the expected function.

http://ieeexplore.ieee.org/iel5/6322910/6329590/06329627.pdf

Research and application on the frequency automatic tracking of ultrasonic power based on DSP

Traditional Savonius wind turbine has advantages such as simple structure, fast start-up, etc., however, it also has significant disadvantages of low wind energy utilization efficiency. A novel wind turbine is proposed by improving structure of Savonius wind turbine in order to increase the low wind energy utilization efficiency. To compare performance of the novel wind turbine and the Savonius wind turbines with two and three blades, two working conditions are investigated. The first is that the wind turbines work in a certain wind speed level to investigate influence of the changing load. The other is that the wind turbines work in a certain tip speed ratio level to investigate influence of environment such as wind speed changing. Considering costs of prototypes, the Computational Fluid Dynamics transient simulation method is used to achieve the analysis. The simulation results show that the novel wind turbine has high load capacities at different situation. The novel wind turbine has higher wind energy utilization efficiency and has good operating characteristics in low wind speed range than traditional Savonius wind turbines.

Simulation analysis based performance comparison for vertical axis wind turbines

With the rapid increase in expressway mileage, accidents and casualties are increasing frequently. Expressway construction in China starts later than developed countries and lack of mature and comprehensive emergency rescue systems. There are some limitations in accident rescue process and information processing such as low coordination level between multi departments and low level of information communication and sharing. An expressway emergency rescue information management system (EERIMS) using Browser/Server framework is developed, the organizational system and rescue process of the provincial expressway system are analyzed, system design, main functional modules and technical points are described. A Case study indicates that it can improve processing and analysis capabilities of the emergency rescue information, enhance communication and sharing between departments and reduce the burden of managers.

Construction of expressway emergency rescue information management system using Browser/Server framework

The wind permanent-magnet generator experimental platform will be developed which drives directly through three phase asynchronous motor. The system hardware is mainly composed of the three phase power supply unit, the inverter, three phase asynchronous motor, External rotor permanent generator, three phase resistive load, the torque and rotational speed sensor, data collector with the USB interface, three phase electric parameter tester, etc. The software of the System includes the PC monitoring software, torque and rotational speed data processing software, three-phase electric parameters data processing software, inverter driving software. The height of three-phase asynchronous motor may be adjusted freely by lifting mechanism screw. Through experimental platform, we tested performance of external rotor permanent magnet generator on 100W, the generators was tested respectively under the load in 3, 6, 9, 12 lights. According to the test data, we get the response curve of the corresponding results.The developed platform is applied successfully to testing an external rotor permanent magnet generator.

http://ieeexplore.ieee.org/iel7/6676471/6681691/06681775.pdf

Development of wind permanent-magnet generator experimental platform

Expressway electromechanical equipment operation status is related to many factors, it exists a lot of uncertainty and randomness. First, the relation among the transition probabilities, the limit probabilities and the equipment state of the time rolling window is calculated by using the Markov chain theory to master the variation of equipment failure. Then, according to the bathtub curve theory and combining with the method of Markov chain, the transfer probabilities and the probabilities limit are analysed to determine the effective life of the equipment. Based on the Markov chain, a new life prediction model is established to study the fault probability trend and the historical fault data are analysed to verify the effectiveness and practicability of the prediction model.

Guan-Qiang Dong

Papers

Research and application on the frequency automatic tracking of ultrasonic power based on DSP

Simulation analysis based performance comparison for vertical axis wind turbines

Construction of expressway emergency rescue information management system using Browser/Server framework

Development of wind permanent-magnet generator experimental platform

A Novel Prediction Model of Expressway Electromechanical Equipment Life