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Aiming at the problem that it is difficult to balance the accuracy and velocity of the fixed-step solution of standard parabolic equation in the study of radio wave propagation in a wide range of complex environments, a variable-step solution method of standard parabolic equation is proposed. Firstly, after deducing the relationship between the error of SSFT solution and step size, frequency and other factors; And the basic selection range of step size for SPE variable step size solution is given. Secondly, the action mechanism of different environmental factors and the requirement of changing trend for step size are expounded through simulation, and the complex environment of SPE application is classified according to the requirement of error. Finally, the method is used to simulate the characteristics of the typical complex environment. The simulation results show that the method can save up to 71.4% of the time compared with the fixed-step method of parabolic equation under the condition of ensuring the calculation accuracy. The reliability and efficiency of the proposed method are verified, and the calculation efficiency of the parabolic equation radio wave prediction can be greatly improved. Therefore, the parabolic equation method with variable step size can ensure the accuracy of calculation, reduce the memory and time required for calculation, greatly improves the efficiency of calculation, and has practical significance in the application of real-time prediction of electromagnetic wave propagation in a wide range of complex environments.

In this paper, a variable step size method for the PE (Parabolic Equation) is proposed to solve the problem of low computational efficiency in the study of radio wave propagation at a large range of complex environments. Firstly, the relationship between the error and the step size, the frequency and other factors of the SSFT (Split-Step Fourier Transform) solution in the standard atmosphere is deduced, and then the basic selection range of the step size is given for the variable step size method. Secondly, the action mechanism of different environmental factors and the requirement of changing trend for step size are expounded through simulation, and the complex environment of PE application is classified according to the requirement of error. Finally, the electric wave characteristics of typical complex environment are advanced by the method. The simulation results show that compared with the small step method, the variable step size method of the PE can reduce the horizontal sampling point by 55.9% and the calculation time by 69.6% when the accuracy is close to the small step method, and the variable step size method is more accurate than the fixed large size step method. Therefore, the variable step size on the PE can not only ensure the accuracy of calculation, but also reduce the memory and time required, which greatly improves the reliability and efficiency. Moreover, it is suitable for solving the problem of the radio wave propagation in complex environment.

The La0.7SrxCa0.3-xMnO3 (x=0, 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3) were prepared by combining sol-gel method and high temperature sintering. The effects of Sr doping content on the structure and morphologies of the La0.7SrxCa0.3-xMnO3 finally sintered at 1050°C/1250°C were investigated based on the analyses of X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). The results show that the La0.7SrxCa0.3-xMnO3 exhibit single perovskite phase and the change of Sr doping content can result in phase structure transition. The La0.7SrxCa0.3-xMnO3 samples are rhombohedra structure in the range of 0.15≤x≤0.3. When x is no more than 0.1, the La0.7SrxCa0.3-xMnO3 samples sintered at 1050°C present distorted cubic structure. The microstructure of La0.7SrxCa0.3-xMnO3 sintered at 1050°C for 5h becomes more and more looser and its grains tend to refinement with the increase of Sr doping content when x is no less than 0.05. Increasing the final sintering temperature can improve the density and promote the grain growth of La0.7SrxCa0.3-xMnO3. In order to gain a dense microstructure, the final sintering temperature of La0.7SrxCa0.3-xMnO3 should be higher than 1050°C and should be suitably increased with the increase of Sr doping content.

The La0.8SrxCa0.2-xMnO3 (x=0, 0.05 and 0.15) compounds were synthesized by combining sol-gel method and high temperature sintering. The effects of Sr doping content on the microstructure, metal-insulator transition and magnetoresistance (MR) of the La0.8SrxCa0.2-xMnO3 were investigated. The results show that the La0.8SrxCa0.2-xMnO3 exhibit single perovskite phase and the change of Sr doping content can result in phase structure transition. The La0.8Sr0.15Ca0.05MnO3 is rhombohedra structure and the La0.8SrxCa0.2-xMnO3 shows distorted cubic structure when x is no more than 0.05. Increasing Sr doping content causes the degeneration of microstructure homogeneity and density and the decrease of average grain size of the La0.8SrxCa0.2-xMnO3, which can be attributed to the weakening of atomic diffusion during the sintering process. The metal-insulator transition temperature (TMI) of the compounds increases with the decrease of Sr doping content due to the improvement of microstructure. The La0.8Sr0.15Ca0.05MnO3 has the highest MR peak value, which is about 95%. The La0.8Ca0.2MnO3 has the highest room temperature MR, which is about 28%. Moreover, the magnetoresistance of the La0.8Ca0.2MnO3 is very stable between 125~300K.

The La0.7M0.3MnO3(M=Ca, Sr) were synthesized by combining sol-gel technique and solid state sintering method. The evolutions of phase structure and micro-morphologies of the La0.7M0.3MnO3with final sintering temperature (950-1250°C) were investigated. The results show that the La0.7Ca0.3MnO3compounds exhibit single perovskite phase with cubic structure and the La0.7Sr0.3MnO3compounds exhibit single perovskite phase with rhombohedra structure. The final sintering temperature has no obvious effect on the phase structure of La0.7Ca0.3MnO3. However, the density and grain size of La0.7M0.3MnO3(M=Ca, Sr) increase with the increase of the final sintering temperature. Moreover, the micro-morphologies of La0.7Ca0.3MnO3are more sensitive to final sintering temperature compared with that of La0.7Sr0.3MnO3. When sintering temperature is no less than 1150°C, the La0.7Ca0.3MnO3has hardly any pore. After sintering at no less than 1250°C, the La0.7Sr0.3MnO3becomes dense.

Silk fibroin film (SFF) has good mechanical property, cells compatibility and biodegradability, and was widely used in the biomedical area as controlling materials. In this work, silk fibroin (SF) was obtained from cocoons. It was dissolved in distilled water to form 5 % and 8 % (W/V) SF solution, which was used to prepare 0.5 %, 1.0 % and 2 % (W/V) sulfadiazine sodium (SD) solution. Five layers of SFF was prepared with salivation method, dried under 37 °C, and annealed with 90 % (V/V) methanol. The structure information was analyzed by FT-IR and SEM, SD release in PBS (0.2 mol/L, pH 7.4) and PBS containing 2 U/ml trypsin at 37 °C was measured. The FT-IR spectra showed that more β-sheet was formed after annealed by methanol; a lot of pores were in the SFF and SD was embedded in SFF through analyzing the image of SEM. The release speed from SFF made by 5 % SF solution was faster than that from SFF made by 8 % SF solution. As for SFF containing different concentration of SD, the release rate improved with the increase of concentration of SD, however, the time of reaching the maximum were approximate. In PBS with trypsin, the time of reaching the maximum accumulative release was one hour earlier compared with in the PBS. Therefore, we draw a conclusion that the SFF incorporating SD has good properties and it has the feasibility to be used as artificial skin for burned patients.

The civil aircraft’s manufacturing process is complicated because of its complex structure and various parts in need. The stability and high efficiency of the based supply network decides the coordination ability among departments and the development cycle completion date. Now it’s very urgent to study the robustness of the collaborative supply network. This paper optimized and designed the robustness of the civil aircraft supply network, first with the project evaluation and review technique (PERT) we set a supply network model; then optimized the critical path to make the system functions remain constant, and the civil aircraft supply network robustness got optimized

Civil aircraft is a complex product to manufacture, and the collaborative supply network consist of grades suppliers plays an important part in the progress of development. Due to the interferences from every kind of uncertainties to the network, it’s necessary to find out the critical supply path which decides the completion date for the network going well. This paper first sets the supply network model based on the hierarchical structure of civil aircraft, and then uses Dijkstra and ant colony optimization (ACO) searching for the critical path respectively, in the last the two methods are compared in order to prove performance and superiority.

the paper analyzes reason for the higher uncertainty in the planeness measurement of wood-working machine tools by leveling ruler with adjustable gauge block; proposes a new design idea of new adjustable gauge block and its measuring performance and calibration requirements; and analyzes its uncertainty of measurement.

Through woodworking four-side planer vibration test, this article studiesits dynamic characteristics and dynamic response to identify the vibration magnitudes law of each feed roll shafts of the four-side feed beam; then finds the natural frequency and damping ratio of the feed beam and lathe bed; obtains the mathematical model of feed roll shaft vibration magnitude changing with the feed rate U under different process thicknesses. The analysis of feeding quantity and the rationality of lathe bed from the perspective of vibration design supplies the designs and operation staff with reference data.

The effect of microstructure on transport properties of nano-polycrystalline La0.7Sr0.3MnO3-δ films, which were prepared by DC magnetron sputtering at various working pressures and followed by air annealing at 973K for 1h, has been investigated. The result indicates that the change of working pressure can change the microstructure, metal-insulator transition temperature (TIM) and peak resistance but does not change the transport mechanism for the films. The vacancy defects have an important effect on the transport properties of the films. Higher working pressure tends to decrease the density of vacancy defects. Low vacancy defects account for the high TIM and low resistance of the films. In the region of T > TIM, the charge carriers are moving in variable range hopping mode. The behavior of resistance decreasing with the increasing of temperature at low temperature (T