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The scientific and sustainable utilization of marine space resources is of great significance for the high-quality development of China’s marine economy and the Ocean Power Strategy. This paper constructs the index system of marine space resources utilization intensity, analyzes the evolution law of China’s marine space resources utilization intensity and its influencing factors. The research results indicate that: (1) The overall utilization intensity of China’s marine space resources utilization is continuously increasing, and the imbalance in provincial utilization intensity of marine space resources was intensifying. (2) The utilization intensity of marine space resources in Tianjin increased significantly, while the utilization intensity of marine space resources in Shanghai fluctuated greatly. The utilization intensity of marine space resources in Zhejiang, Hainan, and Fujian remained at higher intensity and high intensity. The utilization intensity of marine space resources in Liaoning, Shandong, and Guangdong was at medium intensity and high intensity, while the utilization intensity of marine space resources in Jiangsu and Guangxi was at medium intensity and low intensity. The utilization intensity of marine space resources in Hebei remained at low intensity. (3) The overall utilization intensity of marine production space in 11 coastal provinces and cities was higher than that of marine ecological space and marine living space. The overall utilization intensity of marine living space shows a positive growth in 11 coastal provinces and cities, while the overall utilization intensity of marine ecological space shows a significant downward trend. (4) The economic level has the greatest positive effect on the utilization intensity of marine space resources, and industrial structure, government investment, and opening up also have significant positive effects on the utilization intensity of marine space resources. Coastline resources, marine-related employment, and environmental protection has negative effect on the utilization intensity of marine space resources.

C26H30Cl2CoN4O12S2, monoclinic, P21/c (no. 14), a = 11.4094(5) Å, b = 14.2343(6) Å, c = 11.6775(4) Å, β = 114.3130(10)∘, V = 1728.28(12) Å3, Z = 2, Rgt(F) = 0.0393, wRref(F2) = 0.1046, T = 293(2) K.

Objective： This study aimed to provide a basis for the post-harvest storage and preservation of fresh shoots from bamboo (Chimonobambusa quadrangularis). Methods: Fresh bamboo shoots were fumigated with 500 μL/L anhydrous ethanol and 0.1 mmol/L MeJA, and distilled water was used as blank control (CK) to determine the storage period, i. e. temperature (1.0±0.3) ℃ and relative humidity (90±5)%. The respiratory intensity, hardness, browning index, soluble protein, and activity of PAL, POD, PPO and APX were detected. The quality differences of fresh bamboo shoots during storage were analyzed using principal component analysis. Results: Combined fumigation treatment can reduce the increase of hardness and browning index of fresh bamboo shoots during storage, maintain the contents of total flavonoids and soluble protein, induce the changes of APX, POD, PAL and PPO enzyme activities, and delay lignification and browning. As stored for 60 days, the principal component analysis of combined fumigation was higher than that of other treatments. Conclusion: Compound fumigation can better maintain the quality of bamboo shoots during storage.

Thin-film transistors play an important role in ultra-high definition displays. The conventional physical model requires a significant amount of time and resources, while its generalizability is limited. This paper introduces a method for quickly incorporating the characteristics of emerging devices into circuit simulations using an artificial neural network (ANN) model. The multi-layer perceptron (MLP) model, with a simple structure and high modeling efficiency, is employed as a typical ANN model. The pivotal step in using the MLP model is to determine its topology. This hyperparameter problem can be easily solved using Bayesian search. To improve the accuracy of the model, a genetic algorithm is proposed to optimize the initial values of the weights and biases. Furthermore, by introducing the first derivative in the loss function, small signal parameters can be taken into consideration. This modeling approach significantly reduces the time required for compact device modeling. Our experimental results exhibit a strong correlation between the model’s output and the corresponding experimental data, thereby providing comprehensive validation for the effectiveness of our proposed model. Once the trained model parameters were extracted, we implemented the hybrid ANN model using Verilog-A. This circuit-level experiment demonstrates that this hybrid ANN model can accurately estimate various physical devices and circuits.

After several stages of development, China has made great achievements in rural energy. However, the low-efficiency and high-pollution solid fuels that characterize the main source of energy consumption in rural areas remain unchanged. Under the constraints of achieving the carbon neutrality goal in 2060, the existing energy system needs to be transformed to create a sustainable energy system in order to further enhance the economy of rural areas in China. To accelerate the transition of rural energy, this paper answers the following questions based on rural energy consumption characteristics and policies, literature analysis: Why is the rural energy transition important for China at national and rural levels? How the rural energy transition can contribute to the development of rural areas? What are the challenges to implementing the rural energy transition? The paper concludes that China’s rural areas can achieve both economic and ecological development through rational use of its vast space and natural resources, which will be valued upwards of 450 billion CNY and 800 Mt CO2eq respectively. Rural energy transition will face a number of challenges from infrastructure, socio-cultural, and program development. Accordingly, Therefore, there is a need to strengthen infrastructure, raise public awareness and deepen the tripartite cooperation between government, enterprises and farmers to deal with the above problems.

Neuroinflammation mediated by microglia is an important pathophysiological mechanism in neurodegenerative diseases. However, there is a lack of effective drugs to treat neuroinflammation. N-acetyldopamine dimer (NADD) is a natural compound from the traditional Chinese medicine Isaria cicada. In our previous study, we found that NADD can attenuate DSS-induced ulcerative colitis by suppressing the NF-κB and MAPK pathways. Does NADD inhibit neuroinflammation, and what is the target of NADD? To answer this question, lipopolysaccharide (LPS)-stimulated BV-2 microglia was used as a cell model to investigate the effect of NADD on neuroinflammation. Nitric oxide (NO) detection, reactive oxygen species (ROS) detection and enzyme-linked immunosorbent assay (ELISA) results show that NADD attenuates inflammatory signals and proinflammatory cytokines in LPS-stimulated BV-2 microglia, including NO, ROS, tumor necrosis factor (TNF)-α, interleukin (IL)-1β and interleukin-6 (IL-6). Western blot analysis show that NADD inhibits the protein levels of Toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), ASC and cysteinyl aspartate specific proteinase (Caspase)-1, indicating that NADD may inhibit neuroinflammation through the TLR4/NF-κB and NLRP3/Caspase-1 signaling pathways. In addition, surface plasmon resonance assays and molecular docking demonstrate that NADD binds with TLR4 directly. Our study reveals a new role of NADD in inhibiting the TLR4/NF-κB and NLRP3/Caspase-1 pathways, and shows that TLR4-MD2 is the direct target of NADD, which may provide a potential therapeutic candidate for the treatment of neuroinflammation.

AA7204-T4 aluminum alloy plates were welded by friction stir welding(FSW), and the effect of post-weld heat treatment on the microstructure and mechanical properties of the FSW joints were studied. The results show that the average grain size(AGS) and recrystallization fraction of nugget zone(NZ) are 4.7 μm and 81.9% in as-welded(AW) treatment, 4.8 μm and 82.4% under the post-weld artificial aging(AA) treatment, 5.9 μm and 86.5% under the heat treatment of solid solution followed by artificial aging(SAA), respectively. The grain structure of NZ is not obviously affected by AA treatment, and the AGS and recrystallization fraction of NZ increase by 25.5% and 5.6% under SAA treatment. The ultimate tensile strength(UTS) of the FSW joints are 296.6, 318.2, 357.4 MPa under the heat treatments of AW, AA and SAA, respectively. The improvement of the mechanical properties of FSW joints is limited by AA treatment, while that can be effectively improved by SAA treatment which leads to the welding coefficient reaching 92.0%. Additionally, the microcracks tend to generate on the "S" line under the effect of water quenching after solid solution, which would lead to the fracture location at this zone and the serious decrease of the elongation.

The dissolution behavior of equilibrium η(MgZn2), T(Al2Mg3Zn3), S(Al2CuMg) and Fe-containing Al7Cu2Fe insoluble phases of hot rolled 7050 aluminum alloy during solid solution treatment was studied. The dissolution kinetics data of the equilibrium phases were obtained by means of in-situ scanning electron microscope tissue detection method. On the basis of bulk diffusion controlled dissolution kinetics models, the effects of curvature and interfacial reaction on atomic migration rate were introduced, and the dissolution kinetics models of η, T and S phases were established. The results show that η and T phases of 7050 aluminum alloy can be completely dissolved within 2 min at the usual solution temperature (470℃); it takes a long time for S phase to completely dissolve, while the Fe-containing phase hardly dissolves; the curvature has little effect on the phase dissolution, but the dissolution rate can be greatly reduced by the interfacial reaction. The predicted results of the second-phase dissolution kinetics models are in good agreement with the measured results, such as η, T and S phase, which can provide guidance for optimizing the solid solution process of Al-Zn-Mg-Cu alloy.

China is currently rich in biomass resources, and is in a period of energy transition, the development of biomass is the general trend. However, the development of biomass pellet fuel is still immature and faces many obstacles. At this stage, the sales of biomass pellet fuel has problems such as unclear parameters or insufficient coverage. Therefore, it is proposed to build a one-stop platform to promote the development of biomass fuel industry by using modern means to widely collect information on pellet fuel, calculate the reduction potential of pellet fuel, and build an online platform to reduce the information difference. This paper constructs a database by obtaining a large amount of information on biomass fuels through questionnaires, telephone consultations and access to information on websites. Based on the established database, Jupyter was used to analyze the number of fuel types, the provincial contribution, the fuel price distribution and the calorific value distribution. Among them, Guangdong, Shandong, Jiangsu, Hebei and other large grain provinces have the highest contribution of biomass fuels; most of the fuel types are mainly wood fuels, with wood chips, pine and redwood being the main types; the calorific value of fuels is mainly concentrated in the range of 3800-4600kcal/kg; and the price of fuels is mainly concentrated in the range of 600-1000 RMB. In order to reflect the cleanliness of biomass fuels, the article accounts for the carbon emissions of biomass fuel substitutes at different stages of their life cycle, with the aim of providing a reference for users. Eventually a one-stop platform for supply and demand of biomass fuel was established based on a database and carbon accounting methodology. The idea is to import the database into the backend of the WeChat app for retrieval, display it on the front end and sort it according to the user's choice, and give an estimate of emission reductions based on the user's purchase volume and transport distance.

The homogenized Mg-5.3Gd-2.6Y-1.1Nd-0.3Zr(mass fraction/%) ingots were extruded at different temperatures.The microstructures and mechanical properties of the solution-treated ingot and those extruded at different temperatures were investigated by optical microscopy(OM) and tensile test. The corrosion resistance of the alloys in Hank's solutions was evaluated by mass loss, hydrogen evolution and Tafel polarization tests. The surface corrosion morphology of the specimens after immersion was examined by scanning electron microscopy. The results show that the grains of the investigated alloy are refined substantially after extrusion, and their strength and ductility increase along with the decrease of the extrusion temperature, and the yield strength of the extruded alloy under 450℃ reaches 223.4MPa, which is about 60% higher than that of T4 alloy (139.8MPa). The extrusion deformation also has positive effects on the alloys' corrosion resistance, and corrosion resistance of the alloy increases first and then decreases along with the decrease of the extrusion temperature. The one extruded under 450℃ seems to show the best corrosion resistance,whose corrosion rate is 0.74mm/a.

The effects of extrusion ratio on microstructure and properties of Al-0.68Mg-0.60Si alloy were studied by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), transmission electron microscope (TEM), hardness test and tensile test at room temperature. The results show that with the increase of extrusion ratio, the size of the dispersed particles in the matrix of Al-0.68Mg-0.60Si alloy profile decreases gradually, the degree of dispersion increases, the fraction of small angle grain boundaries decreases, but the recrystallization fraction increases. When the extrusion ratio reaches above 39.6, the texture of the alloy is cubic texture. In addition, in the extrusion deformation process, the hardness and tensile strength of the alloy profile increase first and then decrease with the increase of extrusion ratio (λ=26.8-55.7);when λ is 39.6, the maximum tensile strength of the alloy reaches 284.00MPa.

The application of high-strength aluminum alloy on the vehicle body will be the development trend of automobile lightweight in the future.The effects of two-step aging on the microstructure and properties of high-strength aluminum alloys for automobile were investigated by tensile tests, electrical conductivity, and transmission electron microscopy (high resolution). The effect of aging temperature on the overall performance is greater than the aging time. The effect of the second-stage aging temperature in the two-step aging parameters is the greatest. As the aging temperature and aging time of the second-stage increase, the size of the aging strengthening phase increases. The mechanical properties decrease and the conductivity increases. The optimized T76 aging system is 120℃/6h+160℃/12h. The precipitation phase is completely coherent with the matrix. The size of length is about 5-8nm, and the size of thickness is about 3-5nm. The optimized T73 aging system is 120℃/6h+170℃/12h, the precipitation phase is semi-coherent with the matrix.The size of length is about 8-15nm, and the size of thickness is about 4-8nm.

Thick-section Al-Zn-Mg aluminum alloy extrusions are key materials for manufacturing rail transit vehicles, and stress corrosion cracking (SCC) is an important engineering application problem during the service life of these materials. The effect of sampling direction on the stress corrosion cracking behavior of Al-Zn-Mg alloys was investigated through constant load tensile stress corrosion and electrochemical tests. The microstructures of specimens were analyzed in different sampling directions both before and after stress corrosion via optical microscopy, scanning electron microscopy, and electron backscatter diffraction. Specimens with their tensile axes parallel or perpendicular to the extrusion direction of the extruded profiles were labeled as longitudinal specimens and transverse specimens, respectively. The specimens were completely immersed in a corrosive solution, a mixture of 35 g Na Cl and 1 L deionized water, with a constant unidirectional loading of 225 MPa for 360 h at 50 ± 2 ℃. The experimental results show that the transverse specimen is fractured at 315 h, whereas the longitudinal specimen does not break during the entire loading process. Thus, the transverse specimens have poor resistance to stress corrosion cracking. The corrosion current density of the longitudinal section (L-S) is0. 980 m A·cm-2, which is approximately 5 times that of the transverse section (T-S). Thus, corrosion tends to propagate along the longitudinal direction. The L-S is more susceptible to corrosion than the T-S owing to the larger misorientation difference and higher energy of the grain boundary. During the stress corrosion loading process, anodic dissolution occurs and forms corrosion pits. Then, the cooperation of the wedge force produced by the accumulation of corrosion products and constant load causes the crack to propagate along the grain boundary. Intergranular corrosion of the two types of samples is obvious under all immersion corrosion conditions. Different specimens exhibit the tendency to undergo stress corrosion cracking.

The influence of the retrogression time on properties and microstructure of 7150-T77 aluminum alloy was studied by hardness testing, tensile property testing, exfoliation corrosion test and TEM. Results indicate that the matrix precipitated η' phase re-dissolves first, and then η phase re-precipitates and becomes coarsened with the extending of retrogression time. The ultimate mechanical properties increase first then decrease as retrogression time increases. The critical time of the η' phase re-dissolution and the η phase precipitation is 30min, At this point, alloys have the highest ultimate mechanical properties, and the grain boundary precipitated η phase becomes coarsened and discontinuous, leading to lower mechanical properties and better corrosion resistance, peak hardness exists at re-aging stage. With the retrogression time extending, the time for the alloy to reach the peak hardness becomes shorter. Optimal T77 aging treatment is 105℃/17h+190℃/30min+120℃/23h. With this treatment, the ultimate tensile strength (σb), yield strength (σ0.2) and elongation (δ) are 608,544MPa and 10.4%, respectively, the exfoliation corrosion test gets EA level, the σb and δ loss in constant loading tensile testing is 4.9% and 5.0%, respectively.

The flow stress behavior of 5083 aluminum alloy was investigated under hot compression deformation at 523-723K,strain rates of 0.01-10s-1 and true strains of 0-0.7 with Gleeble-3800 thermal simulator. Based on the heat transfer effect on alloy deformation heat effect, the flow stress curves were corrected. The results show that influence of heat conduction can not be neglected and becomes more obvious with the increase of true strain. The corrected flow stress has little influence on the peak stress, but the steady flow stress softening trends to be diminished to some degree. The flow stress can be predicted by the Zener-Hollomon parameters in the constitutive equation. The corrected measured value exhibits a good agreement with the flow stress predicted by the constitutive equation, and the average relative error is only 5.21%.

The effect of quenching rate on microstructure and hardness of Al-Zn-Mg-Cu-Cr alloy extruded bar was studied by hardness test, scanning electron microscopy and transmission electron microscopy. The results show that at quenching rate below 100℃/s, during the cooling process, the hardness begins to fall significantly; and it decreases by 43% at the quenching rate of 2℃/s. At quenching rate below 100℃/s, the number and size of equilibrium η phase heterogeneously nucleated at(sub)grain boundaries and on dispersoids inside grains increase obviously with the decrease of quenching rate, leading to greatly reduced age-hardening response. At the same quenching rate, the equilibrium η phase inside grains is larger than that at grain boundaries. In the range of the studied quenching rates, a quantitative relationship between hardness and equilibrium η phase area fraction has been established.

The microstructure of alloy Mg-3Si(mass fraction/%, same as below) after successive additions with different elements of Zn, Nd, Gd and Y was observed and the microstructure evolution was investigated by scanning electron microscopy and X-ray diffraction. The results show the primary Mg2Si particles co-exist with eutectic Mg2Si particles in binary alloy Mg-Si. With minor addition of Zn element, only primary Mg2Si can be found in ternary Mg-3Si-3Zn system while eutectic Mg2Si particles disappear. In quaternary alloy Mg-2.0Nd-3.0Zn-3.0Si, the addition of Nd element can effectively refine the primary Mg2Si particles and form some Mg41Nd5 particles. After continuous adding of Gd and Y elements into quaternary system, Gd5Si3 and YSi particles increase significantly in the alloy Mg-8.0Gd-4.0Y-2.0Nd-3.0Zn-3.0Si, while volume fraction of primary Mg2Si decrease significantly. Thermo-Calc calculation predicts that the Gibbs free energy for primary particles Gd5Si3, YSi is lower, and therefore Gd, Y atom and Si are more likely to form compounds. In Mg-8Gd-4Y-2Nd-3Zn-3Si alloy, room temperature Gibbs free energy for primary particles Mg2Si, Gd5Si3, YSi is -9.56×104, -8.72×104, -2.83×104J/mol, respectively, and the mass fraction of these particles is 8.07%, 5.27%, 1.40% respectively.

This article uses machine learning technology to analyze the correlation of climate factors that affect crop yields, and conduct prediction and comprehensive evaluation to guide agricultural production. This paper selects early rice crops in Guangxi as the research object. Based on the climatic data of early rice planting areas in Guangxi from 1990 to 2017, a cart decision tree is constructed to generate a random forest model to analyze the correlation between early rice yield and climatic factors in each growth period, and obtain the various growth periods The ranking of the importance of climatic factors on the yield, thus forming the basis for calculating the weights of the climatic factors in each growth period of early rice; based on the climatic data in Guilin, Guangxi from 2008 to April to July 2017, predicted by the long and short-term memory network Guilin's various climate data from April to July 2018.

Individual risks in evacuation under toxic gas diffusion conditions were quantified on the basis of the human vulnerability model. The alert communication and people transition laws were used to determine individual risks at different deployment ratios of alert receiving devices. A bi-objective mathematical model of deployment for alert receiving devices around natural gas wells in operation was built by the graph theory and multi-objective optimization method,and based on the greedy algorithm a practical algorithm was introduced to solve a better non-inferior solution of the model. Finally,taking the emergency warning project of a montanic gas well as an example,the border of deployment sub-regions and the corresponding deployment proportion were achieved by program computation. The results show that,for the same risk mitigation goals,this method has a better economy than the average deployment method in reducing deployment costs and relieving road congestion.

Multi-channel in azimuth is a technique to achieve high-resolution as well as wide-swath in Synthetic Aperture Radar (SAR) systems. Channel error is inevitable in multi-channel systems and it induces blurring in subsequent SAR imagery. Existing compensation approaches are sensitive to system parameters as well as the imaging scenes. Uncertainty of the parameters impacts the validation of these algorithms. In this paper, an improved approach is presented to remove the channel error. Based on the error form, this approach models channel error as three parts: the range gain error, the pulse sampling clock error, and the transmission phase error. The range gain error and the pulse sampling clock error are removed alternately. Then the proposed approach uses cost function to estimate the transmission phase error so that it is independent from the imaging scene. Point target simulations are carried out to investigate the performance, and real data comparison experiments are carried out to verify this approach.

HJ-1-C is a Synthetic Aperture Radar (SAR) satellite in the Constellation of “2+1” for China environment and disaster monitoring. It works at S-band with a resolution of 5 m. SAR payload uses a reflector antenna and a high-power concentrated transmitter. Its light weight and high efficiency is very suitable for a small satellite platform. Now HJ-1-C satellite has been launched into orbit and has acquired Chinese first S-band SAR images from space, which demonstrate excellent quality and rich information about scenes imaged. This success verifies our design, testing and experiment work on the payload. With its following operation, HJ-1-C satellite is expected to make a great contribution to the applications of environment protection and disaster monitoring in China. This paper introduces the design and development of HJ-1-C SAR payload, present its main parameters and performance, describes its device details and its manufacture, testing and experiment process. Some images acquired in the orbit are showed.

Road network extraction in SAR images is one of the key tasks of military and civilian technologies. To solve the issues of road extraction of HJ-1-C SAR images, a road extraction algorithm is proposed based on the integration of ratio and directional information. Due to the characteristic narrow dynamic range and low signal to noise ratio of HJ-1-C SAR images, a nonlinear quantization and an image filtering method based on a multi-scale autoregressive model are proposed here. A road extraction algorithm based on information fusion, which considers ratio and direction information, is also proposed. By processing Radon transformation, main road directions can be extracted. Cross interferences can be suppressed, and the road continuity can then be improved by the main direction alignment and secondary road extraction. The HJ-1-C SAR image acquired in Wuhan, China was used to evaluate the proposed method. The experimental results show good performance with correctness (80.5%) and quality (70.1%) when applied to a SAR image with complex content.

Bistatic Synthetic Aperture Radar (BiSAR) in one-stationary mode has many advantages over the traditional monostatic SAR. Its echo, however, shows serious space variance in both range and azimuth directions due to its complex imaging geometry, making it hard to be processed by the frequency methods used in the monostatic SAR. To solve that problem, a method based on blocks and interpolation has been proposed by Wang Yu et al.. With this method, points can be well focused except for those located on the edge of each block. In this paper, a modified method is put forward, which adopts new block-dividing strategy and new mapping relationship in the interpolation. With the proposed method, points on the edge can also be well focused, making the quality of the final image greatly improved.

This study concentrates on the results of several advanced hybrid bistatic SAR experiments. The hybrid bistatic configuration applies to the case in which the transmitter and receiver are mounted on different types of platforms, e.g., spaceborne/airborne, airborne/stationary, spaceborne/stationary, and so on. Several hybrid bistatic SAR experiments have been performed successfully, i.e., TerraSAR-X/PAMIR, PAMIR/stationary, and TerraSAR-X/stationary. Furthermore, Multiple Baseline Interferometry SAR (MB-InSAR) and Digital Beam-Forming (DBF) technologies are validated in the TerraSAR-X/stationary configuration. Note that the DBF experiment results based on the spaceborne illuminator are discussed for the first time in SAR community. In addition, this paper emphasizes imaging geometry, image analysis, and focusing results.

Employing Polarimetric Interferometry Synthetic Aperture Radar (PolInSAR) data to inverse forest parameters is a hot topic in the research field of PolInSAR. The typical forest parameter inversion algorithm is the three-stage inversion algorithm based on Random Volume over Ground (RVoG) model. The errors of linear fitting and volume scattering correlation estimation are the major factors for parameter estimation accuracy. In this paper, straight line fitting employing the total least squares method is used to estimate the ground phase. Then, the Gamma function is applied as the line measure to adaptively estimate the volume scattering correlation. The improved three-stage inversion algorithm with PolInSAR is presented. The experiment result proves the forest parameters inversion result is accurate and reliable.

Phylogenetic models of molecular evolution are central to numerous biological applications spanning diverse timescales, from hundreds of millions of years involving orthologous proteins to just tens of days relating to single cells within an organism. A fundamental problem in these applications is estimating model parameters, for which maximum likelihood estimation is typically employed. Unfortunately, maximum likelihood estimation is a computationally expensive task, in some cases prohibitively so. To address this challenge, we here introduce CherryML, a broadly applicable method that achieves several orders of magnitude speedup by using a quantized composite likelihood over cherries in the trees. The massive speedup offered by our method should enable researchers to consider more complex and biologically realistic models than previously possible. Here we demonstrate CherryMLs utility by applying it to estimate a general 400 × 400 rate matrix for residue-residue coevolution at contact sites in three-dimensional protein structures; we estimate that using current state-of-the-art methods such as the expectation-maximization algorithm for the same task would take >100,000 times longer.

A Fast Back Projection (FBP) algorithm for spotlight mode Bistatic Synthetic Aperture Radar (Bi-SAR) was presented. Sync channel signal from land receiver was taken as matched filter for echo signal in the phase of range compression, and the secondary phase calibration decreased the approximation error effects for FBP algorithm in the phase of azimuth compression. Computational complexity of this algorithm was O(N2.5 ). In addition, this algorithm was validated on Graphic Processing Unit (GPU) by simulation data and measured data.

Spaceborne SAR, which is a kind of initiatively microwave imaging sensor, plays an important role in gathering information with its capability of all-day and all-weather imaging, and has become an indispensable sensor for observing the earth. With the development of SAR techniques, Spaceborne SAR has been provided with the ability of High-Resolution Wide-Swath, miniaturization with low cost, bistatic and multi-mode imaging, and Ground Moving Target Indicating (GMTI), so more accurate information about the culture could be obtained with lower cost. In the meantime, more technique problems with muliti-mode, new work system and complex environment are arising and needed to be solved. The main work of this paper is discussing the current situation and the future development of Spaceborne SAR.

An irregular LDPC decoder with a code length of 7 493 bits for DTMB system was implemented based on SMIC 0.13μm CMOS process.A new method to control memories was proposed,which can reuse memories for three different code rates only by increasing 5% memory usage.The throughput of the LDPC decoder is up to 150Mbit/s with the max iterative number of 15.While keeping the throughout of 50Mbit/s,its max iterative number can reach 45.The FPGA synthesis reports and the decoder layout in SMIC 0.13μm CMOS technology are given.