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High-power high-frequency transformer is a crucial component of isolated DC-DC converters. To optimize the structure and efficiency of high-frequency high-power transformer, high-precision estimation of transformer parameters is necessary. This paper proposes to adopt high-precision FEA simulations in parameter estimation including the dielectric strength for insulation design and the core loss. In addition, the difference of core loss estimation principle between different types of core material is pointed out. The proposed methods are applied to a specific case of transformer design to demonstrate the effects of the proposed methods in structure and efficiency optimization. Experiments will be performed in future research to verify the accuracy of the proposed core loss estimation methods and the feasibility and high efficiency of the proposed design scheme.

In the application of photovoltaic power generation integrated into the MVDC grid, the design of high-power and high-voltage converters is often a difficult point due to the limitations of devices and converters themselves. Aiming at high efficiency, adaptive voltage regulation and high power density, the interleaved-Boost and full-bridge LLC converter (IB-FBLLC) based on all SiC devices is studied and designed. For the core topology, LLC topology, a parameter design method based on high efficiency and wide bus voltage range is proposed. The losses of each part of the LLC converter as a function of main parameters are analyzed in this paper, and it is concluded that the switching loss is independent of the frequency when considering the maximum efficiency. In the design based on the wide bus voltage range, the FHA method is innovatively applied to the decoupling solution of resonance parameters by introducing intermediate variables k and Q, which significantly optimizes the parameter design process and simplifies calculations that are almost impossible to solve. It turns out that the maximum voltage gain or minimum bus voltage is independent of the switching frequency. These design methods and considerations are verified on a 80kW prototype, whose efficiency and power density reaches 98.08% and 1.562 W/cm3, respectively.

Nowadays, the research and design of the DC-DC conversion system has become more and more popular in the application of photovoltaic generation into the medium voltage DC (MVDC)grids. A novel high power modular isolated DC-DC converter with high step-up ratio is proposed as a module of the DC-DC conversion system in this paper. Based on the input parallel and output series (IPOS)connections of the proposed modular converters, the system is easy to achieve high capacity and high voltage. A two-stage structure is employed in the proposed converter. The interleaved boost topology is applied to the front-stage, which realizes MPPT for PV arrays with low input current ripples. The full-bridge LLC topology is employed as the back-stage, which lowers power losses by the implementation of soft-switching. The voltage gain of the proposed converter is derived in detail. The theoretical analysis and control strategy are studied in depth. Simulation and experiment verify the feasibility and effectiveness of the proposed converter.

In recent years, since DC grids provide higher power supply reliability, higher equipment redundancy, more adaptable power supply mode and more secure power flow control, the medium voltage DC (MVDC) grid is becoming a strategic industry that is widely developed and focused in the world. Particularly, power generation based on large-capacity photovoltaic (PV) is growing rapidly, and a corresponding power conversion system is critical for integrating large PV systems to medium voltage dc grid. In order to improve the reliability and efficiency of PV generation system, the high voltage gain and high efficiency for large capacity dc conversion are required. However, researches on this issue have been relatively few and limited so far. An in-depth analysis and study about high step-up ratio conversion system for MVDC grid connected with PV system is carried out in this paper. Specifically, the characteristics suitable for high step-up ratio conversion system in structure are discussed. According to these characteristics, the conversion systems fall into four categories by series-parallel connection scheme of power modules. Then, three conversion system solutions are identified and compared in terms of input/output performances, conversion efficiency, modulation method, control complexity, power density, reliability and hardware cost. Through thorough analysis, how to select the most suitable conversion system in various applications is also discussed.

Eliminating redundant readers is a significant way to improve the performance of the radio frequency identification (RFID) networks. This paper proposes a middleware-based model for redundant reader elimination, which is formulated as a multi-dimensional optimization problem. It uses the data in RFID middleware to distinguish redundant readers and no "write-to-tag" operations are required. The Plant Growth Simulation Algorithm (PGSA) is employed to search the optimal adjustable parameters. The simulation results reveal that the proposed approach outperforms other algorithms in terms of optimization precision and computing time.

The HJ-1 A/B satellite of China is widely used to monitor pollution, ecosystem destruction and natural disasters. Land surface temperature (LST) is required for a wide variety of scientific studies, from climatology to hydrology and ecology. In this paper, we propose Jimenez-Mufloz and Sobrino (JM&S) single-channel algorithm for retrieving LST from the infrared scanner (IRS) data of HJ-1B. Firstly, we got radiation intensity and brightness temperature from HJ-1B data. Then we calculated the atmospheric water vapor content with MODIS data. Afterwards, the emissivity was acquired with normalized difference vegetation index (NDVI). Finally, we retrieved LST with JM&S single-channel algorithm with these parameters. Through comparing LST retrieved from HJ-1B/IRS and MODIS LST product, we find that HJ-1B/IRS LST is basically consistent with the MODIS LST. Therefore, owing to high temporal resolution and large width, HJ-1B will play an important role on the research of LST retrieval.

Wenchuan in Sichuan Province, China, was hit by an 8.0 magnitude earthquake on 12 May 2008. Thousands of buildings were destroyed and thousands of people were hurt. History tells us that after earthquakes, floods and other natural disaster, infectious diseases often outbreaks. In this study, with the help of spatial information technologies including remote sensing and geography information system, we acquired environmental factors including population, earthquake intensity, route distance, direct distance, Normalized Difference Vegetation Index, Normalized Difference Water Index, and Digital Elevation Model for each township in Anxian after earthquake. Then we constructed a Back Propagation Neural Network to train environmental factors and incidence of communicable diseases, and predicted the incidence of communicable diseases. The results showed that incidence of communicable diseases after earthquake could be predicted using remote sensing to some extent.

Multi-spectral image refers to the use of multi-spectral sensors from the same object (target or region) to obtain the spectral range of more than one image. With the development of multi-spectral imaging technology, the existence of non-rigid mismatch among the original inter-band images requires a higher accuracy and faster registration. Here an automatic elastic registration method based on mutual information and thin-plate spline interpolation is presented, we carried out HJ-1A/B satellite Level 1 visible light inter-band images registration. This does not require other priori assumptions among multi-spectral image gray relationships, or the need for image segmentation and pre-processing (such as feature extraction, classification, etc.). Through the research about multi-spectral image inter-band registration, deviations may be controlled within an acceptable range, we can get more information about multi-spectral images.

The urban heat island (UHI) effect is becoming an influential factor on the city's environment along with the rapid development of urbanization process. This paper uses Landsat-5 TM RS image of the year 1988, 2007 and 2010 based on NDVITEM model and land temperature retrieval method to obtain Beijing land surface temperature distribution map through digital image processing and land surface temperature (LST) retrieval calculating using thermal infrared (TIR) remotely sensed satellite observation. The analysis showcases that urban heat island effect in Beijing has been dramatically intensified since 1988. Especially in recent years, the urban heat island effect has become increasingly apparent and seriously affected human's health in the way of changing temperature, barometric pressure, humidity, wind as well as air.

Heat-related disorders, productivity falling and safety problems are common phenomena when people working in hot and humid environments. In this research, the physiological parameters (oral temperature, heart rate and blood pressure) of people working in hot and humid environments were obtained. Based on the physiological limits, the safe work times in different conditions were determined. Then Cox regression method was adopted to determine and rank the significant covariates. The hazard function, survival function curve and hazard function curve were also obtained. The results show the effectives of Cox regression method in analyzing safe work time in hot and humid environments.