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In order to meet the specific application requirements of stepper motor in space optical remote sensor, such as large load current, low operating frequency, sufficient safety margin, anti radiation and other space environment indicators, a spaceborne stepper motor driver based on antifuse Field Programmable Gate Array (FPGA) is designed. The driver consists of power conversion module, control module, drive module, and position detection module. Using P-channel Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) and N-channel MOSFET to design bipolar drive circuit, the driver hardware circuit is simple and the software resource occupancy rate is low. Through the experiments of the dual functions of logic protection circuit in hardware and dead zone protection in software, it is verified that the design of spaceborne stepper motor driver based on FPGA meets the requirements of space optical remote sensor mechanism control.

At present, the trend of improving the mobility of fast acquisition, long-term tracking and high-precision control has been formed in China. The continuous observation ability of non-cooperative targets and good imaging performance in motion are important trends in the development of optical remote sensing technology. Aiming at the high-precision observation and real-time tracking requirements of high orbit space satellites, this paper studies the high-precision relative navigation of space non cooperative targets. In order to solve the problem that the estimation accuracy of Cubature Kalman filter (CKF) decreases when the system visibility is low, a modified Cubature Kalman filter (MCKF) based on the visibility is proposed. This algorithm defines a system visibility characterization method based on the error gain matrix of the filtering process, and proposes the visibility scaling parameter based on this method, The filter gain covariance matrix is adjusted online, so that the algorithm can adjust the weight of state prediction and system observation online according to the observability of the current time. Numerical simulation shows that compared with CKF, the estimation accuracy of MCKF is improved by about 4 times, and MCKF stabilizes faster and has higher accuracy.

The focus of this paper is on the development of micro-displacement measurement system of Beam Steering Mechanism (BSM) and Fast Sweeping Mirror (FSM) using in space remote sensor. The main objective is to design a micro-capacitance measuring technology based on Pcap01. In the proposed approach, first, the principle of capacitance measurement and the design of hardware and software of the system are introduced; then, the system is implemented to high-precision results below 3.5nF. The experiment results show that under the 1KHz output data rate, the system can achieve a resolution of 1.4fF in the range of 1pF~30pF, which can meet the system requirements of range and accuracy ratio of 20000.

To achieve high-precision imaging in the calibration area of a sub-satellite point, this paper proposes a method for assessing the scanning accuracy and how it affects the agility of the maneuvering process. In addition, simulations and experimental validation are also conducted using a position-velocity dual-loop control algorithm. The design is based on the control theory and the operating characteristics of the actual flexible scanning mechanism, the control law is designed using the control method based on the permanent magnet synchronous motor model, and the interference is simulated and analyzed. The results show that the design can combine the control performance indexes of practical applications and meet the requirements of in-orbit high-precision scanning, which can provide a reference for the subsequent development of space high-precision scanning control.

A high precision direct drive control two axis servo scanning system in space is designed and developed. Based on the requirement of technical indicators, the high-precision direct drive control two axis servo scanning system is divided into an rotating telescope and a half angle mirror servo system. The design and analysis of the servo system’s structural design, shafting accuracy and motor options are carried out. Taking the half angle mirror servo system as an example, the electrical structure of servo system is expounded, and a compound control strategy based on all digital control drive and high precision photoelectric encoder is established, which directly drives PMSM. The circuit design and working process of servo control module are described in detail. The test results show that the speed stability performance of the scanning system can reach ±0.28%, and the servo precision can reach ±16″, and it has the characteristics of long life, anti pollution, etc, which can meet the requirements of the space high precision and long life scanning system.

With the rapid development of large scale sky surveys like the Sloan Digital Sky Survey (SDSS), GAIA and LAMOST (Guoshoujing telescope), stellar spectra can be obtained on an ever-increasing scale. Therefore, it is necessary to estimate stellar atmospheric parameters such as Teff, log g and [Fe/H] automatically to achieve the scientific goals and make full use of the potential value of these observations. Feature selection plays a key role in the automatic measurement of atmospheric parameters. We propose to use the least absolute shrinkage selection operator (Lasso) algorithm to select features from stellar spectra. Feature selection can reduce redundancy in spectra, alleviate the influence of noise, improve calculation speed and enhance the robustness of the estimation system. Based on the extracted features, stellar atmospheric parameters are estimated by the support vector regression model. Three typical schemes are evaluated on spectral data from both the ELODIE library and SDSS. Experimental results show the potential performance to a certain degree. In addition, results show that our method is stable when applied to different spectra.

In order to screen the endophytic fungi of ginkgo biloba with high flavonoid yield, the surface of the sample was disinfected by immersing with 75% ethanol, 3% sodium hypochlorite and sterile water alternating. The endophytic fungi of ginkgo biloba were separated by tissue culture method. 47 strains of endophytic fungi were obtained, and 16, 17 and 14 strains were found in the branches, leaves and roots respectively. The flavonoid-producing strains and its content of total flavonoids in the fermentation broth were determined by chromogenic reaction and colorimetric method of aluminum chloride respectively. Finally, four strains with the highest flavonoid-producing (Y6, Y8, Y10 and G8) were screened, and theirs total flavonoids content in the fermentation broth were 25.33±1.29 mg/L, 32.04±1.38 mg/L, 20.48±0.83 mg/L and 20.19±1.59 mg/L respectively.

Cyanine dyes are widely used in biological labeling and imaging because of their narrow near infrared emission, good brightness and high flexibility in functionalization, which not only enables multiplex analysis and multi-color imaging, but also greatly reduces autofluorescence from biological matter and increases signal-to-noise ratio. Unfortunately, their poor chemical- and photo-stability strongly limits their applications. The incorporation of cyanine dyes in silica nanoparticles provides a solution to the problem. On one hand, the incorporation of cyanine dyes in silica matrix can enhance their chemical- and photo-stability and increase brightness of the nanomaterials. On the other hand, silica matrix provides an optimized condition to host the dye, which helps to maintain their fluorescent properties during application. In addition, the well-established silane technique provides numerous functionalities for diverse applications. However, commercially available cyanine dyes are not very stable at high alkaline conditions, which will gradually lose their fluorescence over time. Our results showed that cyanine dyes are very vulnerable in the reverse micelle system, in which they will lose their fluorescence in less than half an hour. The existence of surfactant could greatly promote degradation of cyanine dyes. Fluorescent silica nanoparticles cannot be obtained at the high alkaline condition with the existence of surfactant. In contrast, the cyanine dyes are relatively stable in Stöber media. Owing to the fast formation of silica particles in Stöber media, the exposure time of cyanine dye in alkaline solution was greatly reduced, and highly fluorescent particles with good morphology and size distribution could be obtained via Stöber approach. However, the increasing water content in the Stöber could reduce the stability of cyanine dyes, which should be avoided. This research here provides a clear guidance on how to successfully synthesize cyanine dye-doped silica nanoparticles with good morphology, size distribution, stability and brightness.

By means of the nuclear parton distribution studied only with lepton deep-inelastic scattering experimental data, the effect of spatially inhomogeneous shadowing is studied in the p-A Drell - Yan dimuon production process. Using multiple soft rescattering theory, the initial state energy loss effect is also considered within the Glauber framework. The calculated results are compared to the E772 and E866 data. It is shown that the theoretical results while considering the energy loss effect are in good agreement with the experimental data. In this paper, we also compare the calculated results of inhomogeneous shadowing with those of homogeneous and find that the inhomogeneous shadowing results exhibit a stronger energy loss effect than the homogeneous results at the same parameter.

In order to promote biogas-slurry commercialization, A method was put forward to valuate biogas slurry based on its nutrient contents. Firstly, element contents of biogas slurry was measured; Secondly, each element was valuated based on its market price, and then traffic cost, using cost and market effect were taken into account, the pricing method of biogas slurry were obtained lastly. This method could be useful in practical production. Taking cattle manure raw meterial biogas slurry and con stalk raw material biogas slurry for example, their price were 38.50 yuan RMB per ton and 28.80 yuan RMB per ton. This paper will be useful for recognizing the value of biogas projects, ensuring biogas project running, and instructing the cyclic utilization of biomass resources in China.

We discuss the consequence of local duality for elastic scattering, and derive a model-independent equation between structure functions at x ~ 1 and elastic electromagnetic form factors. Then the electromagnetic form factors of proton are discussed using the quark-hadron duality theory. We also debate the form factor of proton in a bound state. It may be an effective approach to study the form factor of proton in media.

Marine disasters are a more prevalent problem in China than in many other countries. Based on the development of a status quo of China's marine disaster the space-time process model is used. The model uses the ocean's temperature field, salinity field, water density field, surface wind field, wave field and other four-dimensional spatio-temporal quantities. This paper studies that model in detail. This study aims at using the theory to provide support during marine disasters in an effort to prevent or decrease their frequency in the future.