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Taking into account the wind speed distribution and correlation, the units in the field are first clustered according to the wind speed distribution, and the wind speed distribution modeling scheme is proposed for practical applications. Then, each area is selected according to the European distance. Finally, considering the uncertainty between wind speed and available inertia, neural network is used to predict the available inertia distribution of each cluster. A wind farm in China is selected as the simulation example. The simulation results show that compared with the equivalent machine method based on average wind speed, the prediction accuracy of the proposed method in the low wind speed range is significantly improved, and the calculation efficiency of the proposed algorithm based on the clustered central unit is higher.

In order to solve the problem of cumbersome external parameter calibration of solid-state lidar and overcome the difficulty in verifying its calibration results, a simple calibration and verification method for solid-state lidar is proposed. This method designs a simple calibration field and markers, uses the markers to complete the angle calibration of the lidar, and completes the distance calibration of the lidar by using the surveying method, so as to reduce the correlation of the external parameters of the angle and the distance, and to ensure the accuracy of the calibration result. Finally, the error of external parameter is obtained through comparison and calculation, and the calibration result of the lidar is verified. The experimental results show that the method proposed is reasonable and effective, and greatly reduces the equipment preparation time and cost required for lidar calibration and verification results, which has a certain application value.

In order to study the dynamic response of a single pile foundation under combined action of wind and wave loads in the marine environment, a three-dimensional unidirectional coupling numerical model of wind wave-seabed-single pile is established. The Reynolds average N-S equation and the Biot dynamic equation are used to control the wave motion and seabed response respectively. Based on the verification of the rationality of the model, the influence of wind and wave parameters (such as wind speed, wind shear coefficient, and wave height) on the response of fluid and pile foundation under combined action of wind and wave loads are explored. The results show that the increase of wind speed, wind shear coefficient, and wave height will aggravate the fluid deformation around the pile, accelerate the wave propagation, and then affect the horizontal displacement and bending moment of the pile. Therefore, when calculating the bearing capacity of offshore pile foundations, the combined effect of wind and wave loads on the pile foundation should be considered comprehensively. The results will provide an important theoretical basis for the study of the bearing performance of pile foundations in harsh marine environments.

The volatility and randomness of wind speed have caused potential safety hazards to wind power grid integration. Improving wind speed forecasting is crucial to the stability of wind power systems and the development of wind energy. A novel short-term wind speed forecasting model (MI-RNN) was proposed based on mutual information (MI) and recursive neural network (RNN). In this model, the MI theory was introduced to select the optimal length of historical wind speed sequence (τ), and the method of using each τ step to forecast wind speed at the next time point was adopted to input the historical wind speed data into RNN for model training. The final wind speed forecasting result was output by the trained RNN model. Besides, the MI-RNN model was applied to the wind speed dataset collected from a wind farm and the forecasting accuracy was compared with that of the traditional wind forecasting methods. The results show that the MI-RNN model has achieved a higher forecasting accuracy compared with the commonly used wind farm wind speed forecasting methods, and can accurately forecast the future wind direction, which is expected to be applied to wind speed forecasting of wind farms with spatial dimensions.

Accurate measurement of soil moisture is crucial in agricultural water management. A mini inside-out nuclear magnetic resonance (NMR) sensor has been designed to measure the moisture in model soils, consisting of three cylindrical magnets magnetized in the axial direction and four arc spiral coils with the same size in series. A circumferential symmetric constant gradient field can be obtained by adjusting the radius and height between the cylinders. To improve the signal-to-noise ratio of the sensor, this a wide-band matching method was proposed in this work to expand the excitation region of the radio frequency coils. The Carr-Purcell-Meiboom-Gill (CPMG) signal was analyzed through inverse Laplace transformation. With the results obtained, moisture content of the sample was found to be positively correlated with the integral area of T2 spectrum peak, verifying the feasibility of the sensor in soil moisture measurement.

The wind flow oscillation effect is an important characteristic of the post-disaster mine ventilation network, but there are few studies on the wind flow oscillation phenomenon and there is a lack of in-depth discussion on the wind flow oscillation characteristics. In order to solve the above problems, taking the parallel downward ventilation network as the research object, the oscillation effects of disaster wind flow and gas mass are studied.Based on the damped vibration theory, an open-loop airflow oscillation model is constructed and the Runge-Kuttamethod is used to solve the numerical problem in Matlab software so as to analyze the oscillation characteristics of the gas mass in the parallel roadway. As the initial wind speed increases, the amplitude of the gas mass increases and the impact range of gas in the parallel pipeline is expanded.A similar model of the actual roadway is established to simulate the change of wind speed in parallel roadways with time. The experimental results show that due to the effect of gas wind pressure and ventilator wind pressure, the wind speed repeatedly increases and decreases in the parallel roadways, i.e. wind flow oscillation phenomenon. When the initial wind speed increases from 0.35 m/s to 0.62 m/s, the wind flow oscillation time is shortened from 50 s to 35 s, and the maximum reverse wind speed is changed from -0.4 m/s to -0.12 m/s. This shows that the increase of the initial wind speed is more conducive to the diffusion and discharge of gas mass.The prevention and control measures of wind flow oscillation in parallel inclined gas accumulation shaft are proposed, including imposing wind-blocking measures on the air branch; strengthening local ventilation and increasing wind speed on the gas branch.

In order to simulate the effect of free-moving ice on the hydrodynamic performance of the propeller, a non-contact model of ice-impeller interaction was established by using the overlapping grid method. In the calculation process, the hexahedral mesh was used to conduct mesh division of the computational domain, and the dynamic fluid body interaction (DFBI) method was used to simulate the motion of ice blocks under the propeller suction effect. The accuracy of the numerical method is verified by the experimental study on the action of the ice under the influence of the ice propeller. On this basis, the influences of different parameters such as ice size, the initial radial position of ice, and the initial axial position on the hydrodynamic performance of the propeller are obtained. The results show that there are a certain accelerating area and a certain blocking area behind the moving ice block. The size of ice block has a direct influence on the hydrodynamic performance of the propeller.

When the aircraft is flying at high angle of attack, the local separation of the air flow on the surface of the aircraft, the linear change of aerodynamic force is destroyed, and the maneuverability and stability are reduced to varying degrees, resulting in the aircraft stalling or entering the spin. The stall characteristics and spin characteristics directly affect the safety of the aircraft. In order to analyze the stall and spin characteristics, a full-scale 6-DOF nonlinear high angle of attack dynamic model is established for a two-seater electric high aspect ratio aircraft based on the wind tunnel test data. The stall characteristics of an electric aircraft at high angle of attack are obtained by numerical simulation and analysis. According to the stall characteristics of simulation calculation, flight test is carried out to verify the reliability of numerical simulation, which provides reference for the later analysis of stall/spin test of large aspect ratio series electric aircraft at nonlinear high angle of attack.

In order to study the influence of propeller pumping action on ice trajectory during the process of ice propeller interference, this paper built a motion trajectory measurement platform based on circulating water tank, combining high-speed camera and the Photron FASTCAM Analysis (PFA) method, and tested and analyzed the trajectory of ice at different propeller rotation speeds. After systematic analysis of the test results, it is found that when the propeller rotates at a high speed and the flow velocity is small, the pumping action effect is obvious, which apparently changes the model ice trajectory and even makes the ice and propeller collide. When the model ice volume is large and the water flow velocity is fast, the propeller pumping action effect is small, and it is difficult for the pumping action effect to change the ice trajectory because of the influence of the water flow velocity, which has little effect on the model ice motion trajectory.

In order to study the microcosmic mechanism of ice formation in ship structure, a numerical simulation is conducted. Based on the Wheeler phase field model, the finite difference method is used to simulate the solidification shape of seawater at different undercoolings. In the process of simulation, sea water is regarded as the binary mixture of salt and pure water, and the authenticity of ice crystal growth is ensured by setting ice physical parameters and introducing crystal nucleus. In the calculation, four nuclei are set up to simulate the ice crystal growth, and the influence of different undercoolings on the ice crystal growth is discussed. The results show that the growth rate of ice crystal increases with the increase of undercooling, and it is linear with the change of undercooling. When the dimensionless undercooling is less than 0.85, the dendrite has only a few branches which are thin. When the dimensionless undercooling is higher than 0.85, the ice crystal has more than two-stages of branches which are obviously thicker. When the dimensionless undercooling reaches 1.0, the branches are squeezed by the main branches and lessned, and the crystal cores are finally filled.

Real-time and accurate acquisition of wind speed data is helpful for precise control of mine wind flow. The existing mine wind speed sensors such as hot-wire type, impeller type, ultrasonic vortex street type and differential pressure type are either susceptible to interference, or unable to detect breeze, or small ranged. Moreover, all these sensors obtain wind speed through electrical signals, and there are safety risks. Based on the light-to-heat conversion characteristics of doped optical fiber and fiber Bragg grating(FBG) temperature measurement principle, a mine-used hot-wire-based optical fiber wind speed sensor is designed. The light energy is converted into heat energy through the doped fiber, and demodulating the amount of FBG center wavelength drift under heat exchange is used to calculate the temperature change of the sensor probe and the wind speed. In the FBG demodulation process, the grating multiplexing technology is applied to realize multiple sensors sharing the same light source and demodulator, which reduces the cost. Laboratory test results show that the FBG center wavelength drift is non-linearly related to wind speed. In the lower wind speed range, the higher the pump light source power, the greater the FBG center wavelength drift range, and the higher the wind speed detection sensitivity. When the wind speed is 0-0.57 m/s, the sensor sensitivity is 1 370 pm/(m·s-1), and the highest resolution is 0.7 mm/s. The response time of the sensor decreases with the increase of wind speed, and the wavelength dynamic range increases with the increase of wind speed. The field test results show that the sensor can realize the detection of breeze and low wind speed in coal mines with good stability, and the monitoring value can show the change of wind speed on site accurately.

Aimed at the problem of avoidance strategy of formation satellites when facing the threat of space debris, a non-dominated sorting genetic algorithm (NSGA-II) is improved and used to code satellites. Besides, the improved differential evolution algorithm is used as the orbital generation model, while Pareto dominance is used to select the optimal solution set. By introducing maneuver consumption, collision probability, work efficiency, and other indicators of formation satellites, the avoidance orbits of satellite are screened to ensure that all the indicators of formation satellites are taken into account. Taking the 3-satellite formation of ocean reconnaissance satellite as an example, the phase adjustment, probability calculation, and horizontal dilution of precision (HDOP) calculation models are introduced. The optimal solution of avoiding orbits is obtained by utilzing the multi-objective optimization algorithm. The simulation results show that this method can formulate a more targeted formation satellite avoidance strategy with different objectives.

In order to improve the aerodynamic performance and stability of the floating platform of an isolated vertical axis wind turbine, a novel structure design concept of the wind turbine with a coaxial counter-rotating vertical axis was proposed. Based on the computational fluid dynamics theory, a numerical simulation was conducted with the application of the Reynolds-averaged Navier-Stokes (RANS) shear stress transfer (SST) k-ω turbulence model, and combined with the eddy current theory, the aerodynamic performance and stability with different tip speed ratios (TSR) were further compared. The results show that in the same flow field, the floating platform of the counter-rotating wind turbine is more stable. When TSR1.3, the wind energy in outflow field is more absorbed by the rotor of the counter-rotating wind turbine. In addition, the length of remote vortex is shorter and the intensity is lower. Therefore, the wind energy utilization efficiency is higher. Coaxial counter-rotating has a certain reference value for the performance optimization of the vertical axis wind turbine.

The ice shell is a spatial thin shell building constructed with ice and snow as the main materials. Ice and snow are easily obtained and fabricated, produce no pollution, and are visually appealing. Therefore, ice shells play an important role in the ice industry and cold regions. In order to promote the innovation of ice shell structures in China, the integration techniques for the design and construction of large-span ice shells were presented. The key techniques were summarized from four aspects: thermal-mechanical coupling analysis, shape control of inflatable formwork, simulation of praying construction and structural monitoring. The application of key techniques was introduced based on the typical engineering cases conducted in recent years. The research results have broadened the appearance modeling and building scale of ice structures, realized the scientific construction and safety assessment of large-span ice shells, and provided theoretical and practical bases for the formulation of design and construction standards for ice shells.

The BDS triple-frequency carrier phase ambiguity resolution is greatly affected by the residual of atmospheric error between long range stations, and GEO satellites are also unfavorable for carrier phase ambiguity resolution relative to geostationary. Taking advantage of the relatively stable signal path of GEO satellites and the influence of atmospheric delay which do not change with the space position of satellites, the constraint of atmospheric delay errors more in line with actual conditions for GEO satellites are carried out. Using the linear relationship of carrier phases ambiguities of GEO satellites B2 and B3 to reduce the effect of single-difference ionospheric delay error between stationson the ambiguity candidates, the candidates of carrier phases ambiguity of B2 and B3 areselected. The linear relationship of triple-frequency phase ambiguity which does not include the influence of errors makes evaluation of the ambiguity candidates, and the ambiguity search space can be constrained. The ambiguity candidates of the GEO satellites are used to determine the residual change of the ionospheric delay between adjacent epochs, and the parameter estimation of GEO satellites is more constrained in accordance with actual situation.The method of long range BDS triple-frequency carrier phase ambiguity resolution with actual atmospheric delay variation constraints and the integer ambiguity constraints of GEO satellite is studied.And determining the ionospheric delay constraint value by using the candidates of ambiguity between epochs is proposed, adjusting the constraint value of the random walk between GEO satellite according to the actual situation.The experimental results show that the method in this paper can improve the efficiency of the triple-frequency carrier phase ambiguity resolution and the accuracy of positioning.

Global positioning system interferometric reflectometry (GPS-IR) is a new remote sensing technique that can be used to estimate near-surface soil moisture from signal-to-noise ratio (SNR) data recorded by a measurement receiver. Considering that there are few studies on the inversion of soil moisture by multi-satellite combination, a multi-star linear regression soil moisture inversion model is proposed. The experiment shows that: ①The multi-satellite combination inversion mode can more comprehensively reflect the soil moisture information within the effective monitoring range near the station, and effectively improve the phenomenon that the inversion process is prone to abnormal jump when using single satellite inversion. At the same time, it improves the accuracy of soil moisture inversion during sudden rainfall periods. ②When the number of combined satellites reaches 6 or more, the correlation coefficient between the inversion result and the soil moisture reference value is greater than 0.9, which is at least 20.8% higher than that of a single satellite.

The development and characteristics of high-resolution optical/SAR satellites are introduced. Geometric radiometric calibration is an important means to improve the image quality. The basic principles of optical/SAR geometric radiometric calibration are summarized, and the research progress of geometric radiometric calibration is summarized. Finally, the frontier issues of satellite geometric radiometric calibration are summarized.

In the process of aviation gamma dose rate measurement, due to the large altitude span, the gamma-ray air attenuation coefficient will be affected by altitude, temperature, air pressure and air density, so corresponding corrections are needed. The Monte Carlo method is used to simulate the linear attenuation coefficient of γ-ray in the air at different densities. First, use empirical formulas to calculate the air density at different altitudes; then use MCNP software to build a gamma spectrometer model to calculate the gamma photon fluence at different altitudes and different densities; finally, calculate the air density at different air densities based on the principle of exponential decay line attenuation coefficient. The results show that the maximum relative error between the air quality attenuation coefficient obtained by the air density simulation calculated by the empirical formula and the recommended value of NIST in the United States is -17.3%; the attenuation plate is used for experimental verification in the γ-ray reference radiation field, and the results show the theoretical calculation and the actual measurement relative error of value: the maximum relative error of 60Co source is 6.0%, and the maximum relative error of 137Cs is 5.3%. This work lays the foundation for the follow-up study of low-altitude near-earth radiation dose.

Using AIS for radar calibration has been widely used in the military field. However, during the calibration process, it was found that the accuracy of the post-school radar was not significantly improved. This paper analyzes the causes of radar accuracy from the error sequence processing level, and proposes a high-precision error calibration method based on AIS. The new method first proposed adding the error distribution analysis to the traditional calibration process, and screening the associated and aligned error sequence for two outliers. The measured data proves that the proposed method can obtain more accurate system error estimates, and effectively calibrates the radar system error, which improves the radar detection accuracy.

We combine k-means cluster algorithm with the statistical model of SAR(synthetic aperture radar) images and develop the probabilistic water body mapping algorithm based on the priori probability estimation. Firstly, we make the statistical model assumption about backscatter values based on Bayesian theory. Then, we classify the images based on cluster algorithm, calculate the prior probability of the water body mapping and estimate the parameters of the statistical model of water distribution.Thewater body probabilistic maps based on GF-3 images in Luquan and Xianning are calculated and then validated with GF-1 images. The algorithm is effective on high-precision probabilistic water body mapping of SAR images.

Due to the rapid development of small satellite technology，and the advantages of low earth orbit satellite(LEO) with low delay and low propagation loss as compared with the traditional geosynchronous orbit satellite(GEO), the broadband LEO constellation satellite communication system has gradually become one of the most important hot spots in the field of satellite communications. Many countries and satellite communication companies in the world are formulating the project of broadband satellite communication system. In view of the actual demand of China, in order to construct the broadband LEO constellation satellite communication system reasonably and effectively, and to research an efficient networking scheme, it is necessary to analyze traffic demand. This paper constructs the location-based traffic model and time-based traffic model. A method to simulate the traffic of broadband LEO constellation satellite communication system is proposed. And the traffic in one satellite and one orbit of the broadband LEO constellation satellite communication system were simulated respectively by using STK and MATLAB simulation software. It provides certain reference and guiding significance for constructing our country′s independent broad band LEO constellation satellite communication system.

Feature extraction and its selection are one of the most important steps in the SAR sea ice classification. The key to improve the classification accuracy is to select effective features and to construct the feature space that effectively expresses the type of ground objects. For this purpose, a full polarimetric SAR sea ice classification algorithm based on target decomposition features is proposed in this paper. First of all, multilook process and filter operation are preformed to full-pol SAR data and result in coherency matrix. Secondly, in order to construct the feature space, target decomposition on coherency matrix is employed to extract related scattering feature parameters. Thirdly, after analysis of statistical correlation about extracting features, PCA feature reduction operation is carried out on those higher relevant features for the purpose of optimizing the combination of features. Finally, a BP neural network-based classification algorithm is designed to classify sea ice, and the optimization of the feature vector as input layer, the class of sea ice as output layer. In experiment, the central Greenland area is regard as the research area and L-band ALOS PALSAR full polarimetric data are utilized as experimental data. Through the qualitative and quantitative analysis for the proposed and comparing algorithms, it can be found that the feature space built up can efficiently distinguish various sea ices. Furthermore, by analyzing the performance of sea ice classification results with different feature combination, we can conclude that the features of the target decomposition based on scattering model can provide a better capability to identify water and sea ices compared to H/α/A decomposition based on eigenvalue.

In order to investigate the moisture property of carbon fiber reinforced resin composite stiffened panel in hygrothermal environment, moisture experiments were conducted in condition of 70℃/85%RH. Stage moisture model was proposed and moisture behaviors were analyzed by finite element method. The results show that the moisture curve of experimental result agrees with Fick's diffusion law perfectly in initial moisture stage. However, stage moisture behavior exists in later moisture period. The moisture curve of stage moisture model agrees with finite element result,with an error less than 5% compared with the experimental result. The composite stiffened panel moisture mechanism is revealed by moisture concentration distribution. Additionally, the saturated moisture rate in different thickness zones is not synchronous, which is main reason resulting in stage moisture.

The ice shell is a spatial thin shell building constructed with ice and snow as the main materials. Ice and snow are easily obtained and fabricated, produce no pollution, and are visually appealing. Therefore, ice shells play an important role in the ice industry and cold regions. In order to promote the innovation of ice shell structures in China, the integration techniques for the design and construction of large-span ice shells were presented. The key techniques were summarized from four aspects: thermal-mechanical coupling analysis, shape control of inflatable formwork, simulation of praying construction and structural monitoring. The application of key techniques was introduced based on the typical engineering cases conducted in recent years. The research results have broadened the appearance modeling and building scale of ice structures, realized the scientific construction and safety assessment of large-span ice shells, and provided theoretical and practical bases for the formulation of design and construction standards for ice shells.

Geostationary remote sensing satellite is relatively static to the earth.However,because of the influences suffered from inner factors and outer environment,an error of geometric would be happened to satellite's pointing to the ground,and it will cause a large position error on the ground,so that,an effective modification is needed.This paper proposed a set calculation method of pointing to the ground based on landmark matching,which centered on the problem of pointing to the ground when the three-axis stabilization geostationary remote sensing satellite was shooting the earth disk.This method mainly solved the following problems:the generator method of landmark data which was the datum reference,robust matching method between image and landmark,the calculation method of pointing to the ground based on error elimination,and so on.The experiment showed that,this set of method had superior accuracy and stability in solving the error of pointing to the ground of geostationary remote sensing image.This technique had been applied in the online processing of related satellite data in our country.

The aerodynamic parameters of morphing aircraft can vary significantly in the morphing process; the aerodynamic data model is complex and high-order nonlinear. This paper presents a new method of aerodynamic modeling of morphing aircraft by using multivariate splines. Firstly, the aerodynamic coefficient model of morphing aircraft based on the multivariate splines model structure is presented. This model can describe symmetric and asymmetric aerodynamic forces. Then, the multivariate simple splines estimation process is introduced in detail and the concrete formulation is deduced. Finally, the final model structure is determined by error analysis, and the aerodynamic parameter polynomial model in the global coordinate system is obtained by coordinate transformation. The results show that this method can accurately describe the aerodynamic model of morphing aircraft during arbitrary symmetric and asymmetric morphing process without predicting the specific model structure of the aerodynamic parameters related to varying process.

Prompt gamma neutron activation analysis (PGNAA) is a method for quantitative analysis of multiple elements, which is applied in the analysis of coal, concrete, and solid mine. For the purpose of coal PGNAA study, experiment in lab is necessary. But, restricted by the situation of lab, infinite coal material is impracticable. So, designing a coal PGNAA experimental device to stand of the process of PGNAA of bulk coal and achieve the goal of radiation protection is very practical. Monte Carlo is a kind of mature method, by which can simulate the transportation of neutrons and the process of the interaction of particles and material, and calculate the complicate-constructed nuclear incidents. So, using the Monte Carlo method to design experiment of nuclear reactor is common. This research used a special Mont Carlo program-MOCA to design a coal PGNAA experimental device to reach the aim of promoting the PGNAA technique. Firstly, the field distribution of 252Cf neutron source which was used in PGNAA common was constructed with MOCA. Then, by simulating the neutron field formed by 252Cf neutron sources in bulk of coal and polyethylene, the relationship curves of neutron flux and its distance from the source were obtained. Based on the principles of infinite coal material and radiation protection, according to the curves obtained in the previous work, an experimental coal PGNAA device was designed. Finally, the PGNAA experiments of seven different components of coal material were carried out with the device. The spectrums from lab experiment showed element characteristic peaks obviously and quantitative analysis results with good linear. The successful experiment proved that the device was designed reasonably, and MOCA program was an effective method in the study process of coal PGNAA and could be used more in the further.

For a large collection of satellite images,because of the differences in season,light,atmospheric conditions and so on,adjacent satellite images may have different color and there will be obviously "seam-line" in mosaic satellite image.In this paper,a method of satellite image color normalization was proposed,it was implemented to correct the color of image automatically based on better color low resolution satellite imagery which covered the mapping area.We selected a large collection and long time interval GF-1 satellite images as experiment data,results show that the mosaic image have a good visual effect,the color transition of two images smoothly,statistical indicators of overlap area obviously improved,all of those verified the validity and reliability of the algorithm.

Troposphere and ionosphere are two important components of the near-earth space environment. They are close to the surface of the earth and have great influence on human life. The developments of Global Navigation Satellite System (GNSS) over the past several decades provide a great opportunity for the GNSS-based space environment science. This review summarizes the research progress and prospect of the GNSS-based research of the Earth's troposphere and ionosphere. On the tropospheric perspective, modeling of the key tropospheric parameters and inversion of precipitable water vapor (PWV) are dominant researching fields. On the ionospheric perspective, 2D/3D ionospheric models and regional/global ionospheric monitoring are dominant researching fields.

This paper briefly analyzes the basic development and technical situation of oceanic spatial information datum, reviews the main processes of oceanic vertical datum and correlative oceanic tidal study, such as improvement and perfect methods of determining tidal station vertical datum, realizing form of vertical datum controlled by tidal station, effect on maintaining vertical datum by long-term tidal station, oceanic tidal model establishing, and also construction and transformation of tidal datum, and then forecasts the key development directions of oceanic spatial information datum on high-accuracy marine position service, vertical datum and the transferring model refinement and spatial datum application.

Global high-precision geolocation of satellite imagery without GCP is the main goal of satellite photogrammetry,and the fundamental supporting technology of mapping in abroad area.For the developing technology of domestic remote sensing satellite,this paper presents the high-precision geometric processing theory and method of high-resolution optical remote sensing satellite imagery without GCP.Based on rigorous analysis of satellite observation error model,on-orbit geometric calibration method,virtual re-imaging processing method and large-scale block adjustment method are proposed.Experiments were conducted by using ZY-3 imagery.The result fulfills the demand of 1:50 000 mapping,and proves the correctness of proposed theory and method.

Autonomous orbit determination is a crucial step for GNSS development to improve GNSS vulnerability, integrity, reliability and robustness. The newly launched BeiDou (BD) satellites are capable of conducting satellite to satellite tracking (SST), which can be used for autonomous orbit determination. However, using SST data only, the BD satellite system (BDS) will have whole constellation rotation in the absence of absolute constraints from ground or other celestial body over time, due to various force perturbations. The perturbations can be categorized into conservative forces and non-conservative forces. The conservative forces, such as the Earth non-spherical perturbations, tidal perturbation, the solar, lunar and other third-body perturbations, can be precisely modeled with latest force models. The non-conservative forces (i.e. Solar Radiation Pressure (SRP)), on the other hand, are difficult to be modeled precisely, which are the main factors affecting satellite orbit determination accuracy. In recent years, accelerometers onboard satellites have been used to directly measure the non-conservative forces for gravity recovery and atmosphere study, such as GRACE, CHAMP, and GOCE missions. This study investigates the feasibility to use accelerometers onboard BD satellites to improve BD autonomous orbit determination accuracy and service span. Using simulated BD orbit and SST data, together with the error models of existing space-borne accelerometers, the orbit determination accuracy for BD constellation is evaluated using either SST data only or SST data with accelerometers. An empirical SRP model is used to extract non-conservative forces. The simulation results show that the orbit determination accuracy using SST with accelerometers is significantly better than that with SST data only. Assuming 0.33 m random noises and decimeter level signal transponder system biases in SST data, IGSO and MEO satellites decimeter level orbit accuracy can be achieved over a service life of two months using SST data and accelerometers. If only SST data are used, the orbit accuracy is 3~6 m with the same time period, which is an order worse.

Based on the synthetic aperture radar(SAR) convolution model, the convolution computation formula about the derivative of three parameters of time migration, rise time and amplitude are deduced. The SAR waveform retracking is completed using numerical integration and Fourier transform. Besides, the echo waveform under SAR model is generated using the simulation orbit, troposphere, ionosphere and tide model. The comparison shows that the shape of echo waveform under SAR model is the same as that of CryoSat-2 1 Hz SAR. The experiments show that the accuracy of SAR altimeter retracking is about 5 cm under the 20 Hz data(about 350 m resolution), which are improved compared with that of the traditional model.

A relative calibration method used in a novel dual-satellite formation flying altimetry mode is proposed, and a complete formula for calculating relative bias between altimeters is presented. Power spectrum analysis of each correction term in relative bias calculation formula and statistical analysis of differential sequences are respectively conducted with Jason-2 altimetry data. Under the premise that a centimeter level calibration accuracy is ensured, the formula is simplified and error budget is made. The results show that all correction items have low frequency characteristic, and the relative bias error is mainly related to the relative radial orbit error between two satellites, range error, sea state bias as well as the differential geoid height error between two comparison points. As for single overflight, the accuracy of relative bias between two altimeters is about 1.99 cm.

The existing visualization method in the virtual globe mainly uses the projection grid to organize the ocean grid. This special grid organization has the defects in reflecting the difference characteristics of different ocean areas. The method of global ocean visualization based on global discrete grid can make up the defect of the projection grid method by matching with the discrete space of the virtual globe, so it is more suitable for the virtual ocean surface simulation application.But the available global discrete grids method has many problems which limiting its application such as the low efficiency of rendering and loading, the need of repairing grid crevices. To this point, we propose an optimization for the global discrete grids method. At first, a GPU-oriented multi-scale grid model of ocean surface which develops on the foundation of global discrete grids was designed to organize and manage the ocean surface grids. Then, in order to achieve the wind-drive wave dynamic rendering, this paper proposes a dynamic wave rendering method based on the multi-scale ocean surface grid model to support real-time wind field updating. At the same time, considering the effect of repairing grid crevices on the system efficiency, this paper presents an efficient method for repairing ocean surface grid crevices based on the characteristics of ocean grid and GPU technology. At last, the feasibility and validity of the method are verified by the comparison experiment. The experimental results show that the proposed method is efficient, stable and fast, and can compensate for the lack of function of the existing methods, so the application range is more extensive.

The satellite shadow parameters can be numerically calculated with high accuracy from the positions of the sun, the earth and the specific satellite. Unfortunately, it is difficult for the numerical calculation to give a general profile of the variations and distributions of these parameters for some certain types of orbital spacecraft. A satellite shadow model was presented based on the spatial view at the altitude of the satellite and the correlative geometry amongst the sun, the earth and the satellite. Firstly, the size and location of the satellite shadow were determined by the semi-major axis of the satellite orbit and the annual motion of the apparent sun, respectively. Secondly, the computing formulae of the satellite shadow parameters were derived, together with the correction formulae for the long-term prediction of the parameters due to oblateness perturbation, etc. Examinations on the three types of orbits for the BeiDou navigation constellation show that the proposed satellite shadow model and its shadow parameters computing formulae can provide a prompt profile of the eclipse parameters for the medium-high altitude circular orbit satellites.

The influence of water temperature on composite moisture absorption parameters was investigated in temperature-controlled water bath. Experiments of carbon fiber/bismaleimide resin composites immersed in water of 60℃, 70℃and 80℃ were developed respectively. According to the moisture content-time curves obtained from the experimental results, the diffusion coefficient and the balanced moisture content of the composites immersed in different water temperature could be calculated. What's more, the effect of water temperature on the diffusion coefficient and the balanced moisture content were discussed too. According to the Arrhenius equation and the law of Fick, a moisture absorption model was proposed to simulate the hygroscopic behaviour of the composite laminates immersed in different water temperature which can predict the absorption rate of water of the composites immersed in distilled water of 95℃ at any time precisely and can calculate how long it will take to reach the specific absorption rate.

Synthetic aperture radar (SAR) satellite remote sensing images can greatly increase the frequency of the coastline coverage all over the country. However, due to the influence of the random sea surface roughness caused by waves, it's a challenge to distinguish the coastline and sea boundary. To solve this problem, this paper proposes regional distance regularized geometric active contour models (RDRGAC), in which the distance regularized term is introduced to avoid periodically initializing the degraded function with a signed distance function, accelerating the speed of convergence. Besides, it establishes the nonlinear regression relationship between the regional term parameters and equivalent number of looks (ENL) in SAR images, leading to the adaptive setting of RDRGAC model with different SAR images, which could improve the accuracy of coastline automatic detection in return. In the experiments, SAR images in Beidaihe and Dalian Jinzhou Bay respectively are adopted to detect the coastline, verifying the effective of the proposed method.

Water vapor tomography is of crucial theoretical importance to and widely applied in meteorology and climatology, for instance, extreme weather forecasting and now casting, numerical weather prediction and climate change study. Conventional water vapor tomography strategy for calculating equation coefficient needs extensive calculation. To solve this problem, projection plane algorithm is developed for improving the speed of calculation and the accuracy of inversion. The GPS signal data used in this article comes from Hong Kong SatRef. The result, which is compared to the traditional algorithm, indicated that new algorithm reduces the computing time greatly and is not affected by size of tomography area and there is consistency in the results of tomographic inversion and radiosonde.

The coverage evaluation of traditional land observation for optical satellite is based on ideal coverage of satellite, which has no consideration of the influence of physical condition, such as satellite storage, satellite data transmission and observation time. It also has no consideration of the influence of meteorological condition in observation area. According to land observation requirements of remote sensing, an index evaluation system of effective coverage ability for remote sensing on land observation is build up. According to data storage capacity, data transmission capacity between satellite and ground, longest observation time in one loop, solar elevation angle of satellite observation and so on, an effective coverage calculation method is proposed based on physical capacity constraint for optical remote sensing satellite. On the basis of the climate data of meteorological station over the years, an effective coverage calculation method based on climate constraint is raised for optical remote sensing satellite. Synthesizing satellite physical capacity constraint and climate constraint, effective coverage capacity of earth observation for optical remote sensing satellite is calculated. Meanwhile, based on index evaluation weight of effective coverage capacity for land observation by experts, analytical hierarchical process (AHP) is used to evaluate requirement satisfactory degree for land observation. The experimental result shows that the proposed algorithm is more accurate in estimation and evaluation for effective coverage on land observation, which is able to provide a more precise solution for effective coverage capacity evaluation on earth observation.

Formulas for direct solutions of meridian written by the reduced and geocentric latitudes respectively were derived by series expansion. Meanwhile, according to Lagrange inversion theorem, formulas for inverse solutions of the issue were also expressed in terms of the same latitudes. These two formulas were structurally consistent with that expressed by geodetic latitude ones. In these sets of formulas, internal connection between meridian and three different types of latitude were realized. Analysis and numerical calculation showed that the direct and inverse meridional solution with reduced latitude was of higher precision than that with geodetic latitude, and furthermore, there had a unified theory between meridian theory and classical geodetic problems expressed by reduced latitude.

The collinear rigorous geometric model contains the atmosphere refraction geometric error in off-nadir observation. In order to estimate and correct the atmosphere refraction geometric error, the ISO international standard atmospheric model and Owens atmosphere refractive index algorithm are applied to calculate the index of atmosphere refraction in different latitude and altitude. The paper uses the weighted mean algorithm to reduce the eight layers ISO standard atmospheric model into a simple troposphere and stratosphere two layers spherical atmosphere. And the LOS vector track geometric algorithm is used to estimate the atmosphere refraction geometric error in different observation off-nadir angle. The results show that the atmosphere refraction will introduce about 2.5 m or 9 m geometric displacement in 30 or 45 degree off-nadir angle individual. Therefore, during geo-location processing of agile platform and extra wide high spatial resolution imagery, there is need to take into account the influence of atmosphere refraction and correct the atmosphere refraction geometric error to enhance the geo-location precision without GCPs.

A wind turbine located in Yunnan is taken as an example in this paper. By using the analytical method and the finite element method, the modal analysis of wind turbine tower is carried out, then the structural dynamic behavior is obtained. Based on the comparison of the results from different calculation methods, the rigidity and the resonance of tower induced by wind wheel rotation are studied. The research shows that, the finite element model is simplified, while the results of this method are rich; the transient resonance inevitably appears for two times in the starting process for the flexible wind tower which has the structure of symmetry basically; while in the normal operation stage, the wind wheel would not induce the resonance for flexible tower. The research provides a theoretical basis for the design of wind turbine tower.

A correlation model between along-track gravity anomaly accuracy, spatial resolution and altimeter accuracy is proposed. This new model is based on along-track gravity anomaly recovery and resolution estimation. Firstly, an error propagation formula of along-track gravity anomaly is derived from the principle of satellite altimetry. Then the mathematics between the SNR (signal to noise ratio) and cross spectral coherence is deduced. The analytical correlation between altimeter accuracy and spatial resolution is finally obtained from the results above. Numerical simulation results show that along-track gravity anomaly accuracy is proportional to altimeter accuracy, while spatial resolution has a power relation with altimeter accuracy. e.g., with altimeter accuracy improving m times, gravity anomaly accuracy improves m times while spatial resolution improves m0.4644 times. This model is verified by real-world data.

Base on the comprehensive literature review,this paper summarized the recent studies on measurements and simulations of atmospheric ultrafine particles in various regions and environments.The observations show that the time-spatial variations,formation and growth,compositions of ultrafine particles are strongly related to meteorological conditions and local pollution sources,therefore,the characteristic of ultrafine particles varied widely in different regions.The ultrafine particles can be directly emitted from combustion processes both stationary and mobile sources,or formed in the atmosphere through nucleation.Some aerosol dynamic module contained particulate number concentration diffusion models are introduced,but most of them are applied in a motor vehicle emission simulation.Little research has been conducted in applying particle number concentration simulation to city range.Finally,this paper provides and discusses the challenges to address the ultrafine particles pollution