Ziqi Guo

Fluctuation characteristics of arc voltage and jet flow in a non-transferred dc plasma generated at reduced pressure

A torch with a set of inter-electrode inserts between the cathode and the anode/nozzle with a wide nozzle exit was designed to generate plasma jets at chamber pressures of 500?10?000?Pa. The variation of the arc voltage was examined with the change in working parameters such as gas flow rate and chamber pressure. The fluctuation in the arc voltage was recorded with an oscilloscope, and the plasma jet fluctuation near the torch exit was observed with a high-speed video camera and detected with a double-electrostatic probe. Results show that the 300?Hz wave originated from the tri-phase rectified power supply was always detected under all generating conditions. Helmholtz oscillations over 3000?Hz was detected superposed on the 300?Hz wave at gas flow rates higher than 8.8?slm with a peak to valley amplitude lower than 5% of the average voltage value. No appreciable voltage fluctuation caused by the irregular arc root movement is detected, and mechanisms for the arc voltage and jet flow fluctuations are discussed.

A simplified aeromagnetic compensation model for low magnetism UAV platform

Magnetic interference generated by the air-borne platform is one of the most common system noises in aero-magnetic survey. The noise can be divided into 3 parts as the permanent, the induced and the eddy-current fields. A new air-borne platform called the Unmanned Aerial Vehicle (UAV) can be designed and manufactured with low magnetic interference. Analyzing the test measured data has shown that the UAV, compare with the traditional platform, has lower magnetic noises especially in eddy-current fields. Thus, the eddy-current terms may be ignored in magnetic compensation model. The simulation result shows that the new model reduced the multi-colinearity effect and can be useful in magnetic compensation for low magnetism UAV platform.

A tentative study of water quality retrieval in low-level-polluted Case II waters using analytical model

The problem of Case II water pollution has been paid more and more attention these years. Although traditional means could provide more accurate measured values, they are greatly limited by its temporal and spatial defects. Therefore, remote sensing technology is introduced in and it has become a hot spot in the study of water environment monitoring. In this study, Guanting Reservoir, which lies between Zhangjiakou (HeBeijing) and Beijing, is selected to be the research object. With the data obtained in situ and in the laboratory, the water quality retrial model is established to calculate the water quality parameters of Guanting Reservoir. Further, combining with the satellite data (CHRIS/Proba), the qualitative distribution of water quality parameters at the whole reservoir region scale is obtained, which could support the quantitative study in the next step with data and theory basis.

A design of ecological restoration and eco-revetment construction for the riparian zone of Xianghe Segment of China’s Grand Canal

ABSTRACT The riparian zone is a unique landscape component that represents an ecological transition between aquatic and terrestrial ecosystems. The restoration of riparian zones has become an ecological focus in the realms of both urban development planning and watershed management. This paper applies the concept of landsenses ecology, ecological restoration principles and a range of eco-revetment models in riparian zone restoration for Xianghe Segment of China’s Grand Canal (XSCGC). Based on field trip investigation, the restoration considerations involve the current status quo of the segment’s riparian zone. In addition to the analysis of key flood control areas, the restoration considers the main functions of various landscape components. The riparian zone is divided into five typical sections: the wetland ecological conservation section in the upper reaches, the wetland ecological conservation section in the lower reaches, the riverside leisure and entertainment section in the middle reaches, the restoration and reconstruction section in the middle reaches, and the ecological agricultural section in the lower reaches. Based on the spatial form, human senses and the flood control function of the riparian zone, three typical revetment models are applied, namely original natural revetment, natural revetment, and hybrid revetment. A vegetation plan was proposed for every functional section. The aim of the present study is to provide a reference for the restoration and ecological management of the riparian zone in XSCGC.

An application of three-band model for chlorophyll-a estimation in a turbid case-2 reservoir in Northern China

Three-band model was originally used to retrieve chlorophyll-a concentrations of terrestrial plant leaves. Since turbid productive waters also contain much chlorophyll-a, the model was then adjusted to aquatic medium. With a more accurate physical mechanism than statistical methods and a less complicated model than analytical methods, three-band model has obtained wide applications in chlorophyll-a monitor in water bodies. In this study, we applied the model into a turbid case-2 reservoir in northern China to investigate the applicability of three-band model for remote estimation of the reservoirs chlorophyll-a level. A three-band model was built as Cchla = 1088*X +165.87, where X = [Rrs-1 (711)-Rrs-2 (721)]*Rrs (750), with the RMSE of chl-a estimation was less than 3 mg/m3 and r2 =0.907. The adjusted model implied a good potential to chlorophyll-a concentration estimation in Guanting Reservoir, therefore could be used in the reservoirs water environment monitor.

Retrieval of water quality parameters by neural network and analytical algorithm in Guanting Reservoir in Hebei Province in China

Based on the measured spectra in the research area of Guangting reservoir, we build the model to retrieve chlorophyll-a, suspended solid and yellow substance. The paper mainly achieved the following results: we adopted matrix inversion method and L-M & NN method to analyse the water quality parameters, the selection schemes of the spectral band include REF, DER, RAN method, and then use the Guanting Reservoir experiment data for inspection and comparative analysis. The results showed that: the retrieval accuracy of L-M & NN method was better than matrix inversion method for three ocean color elements, the RAN weighted method overall had better retrieval accuracy. For Cchla, acdom (440), the best scheme in band selection is RAN, REF showed better retrieval accuracy for Cs.

The Path Planning Algorithm Based on the Improved Genetic Algorithm and the Artificial Potential Field Algorithm

For complex flight environment, it is the key how to plan quickly the flight track meeting the mission requirements and constraints. This paper proposed a kind of path planning method based on artificial potential field algorithm and improved genetic algorithm, the method take the idea of hierarchical planning. First it plans the initial path by the improved genetic algorithm, and will the constraint condition fusion to the terrain, at the same time gives the corresponding weights for each track and choose the optimal path. Then unmanned aerial vehicle (uav) flights according to the optimal flight path. When meet the threat, it will use the artificial potential field algorithm to avoid sudden threats, in order to get a satisfactory track. Simulation results show that the path planning algorithm can plan out the initial track quickly in the paper, and can effectively avoid the threats.

A simplified image fusion technique with sensor spectral response

Introducing the sensor spectral response into the wavelet-based image fusion methods may produce images closer to which obtained by the ideal sensor. But the wavelet-based image fusion methods are complex because of the wavelet decomposition. This paper presents a simplified image fusion method using sensor spectral response which derives from a wavelet-based one, but need not to do the wavelet decomposition at the last calculation. The experimental results demonstrate that it provides good performance both in processing speed and image fusion quality.