Hosemann's formula for X-ray scattering by a linear paracrystal is investigated using the distribution of intensity parallel to the fibre axis of oriented poly(butylene terephthalate). The formula was put into a form suitable for numerical analysis, and a stepping refinement procedure used to adjust the paracrystalline parameters so that the discrepancy between the calculated and measured intensity was minimised. The measured intensity had been corrected for the spread of scattering transverse to the fibre axis before making this comparison. The pin-hole collimation system was designed so that resolution was limited only by the linear position-sensitive detector, and was good enough not to distort the recorded scattering distribution. Although parasitic scatter could not be measured to the same accuracy, it was so small that negligible error was introduced when it was subtracted. "Top-hat", Gaussian and Reinhold distribution functions for the lengths of the two phases all fitted well in the region of the main peak although detailed analysis suggested significant disagreement on the low-angle side. Only the asymmetric Reinhold function fitted around the third-order peak and beyond. The range of parameter values giving a good fit for this distribution were determined.

To evaluate urban flood risk while considering spatial and temporal characteristics, this paper establishes an assessment method based on a coupled hydrodynamic model and a fuzzy comprehensive evaluation method. An assessment system is developed using hydrologic, social and economic factors. In addition, hydrology factors are obtained by the coupled hydrodynamic model. The hydrodynamic model is solved using the three-cascade method of the Saint-Venant equations for a river system, and the surface runoff is solved using a modified Roe-type approximate Riemann solver. The hydrology results are used as hydrologic factors and directly reflect the inundation of the subsequent assessment. Afterward, an analytic hierarchy process is used to calculate the weights of the assessment indices. Then, the urban flood risk is analyzed using the fuzzy comprehensive evaluation method. Five different rainfall events in Quzhou City are simulated and evaluated. The numerically computed results compare well with the statistical data and indicate an extreme inundation depth of more than 3 m. In addition, the assessment risk of Quzhou City is at level IV (high). This study shows that combining the assessment method with the coupled hydrodynamic model efficiently reflects the urban flood risk by considering flood, social and economic data.

In this letter, a compact frequency-tuned microstrip balun with a ring structure is proposed. By tuning the capacitance of varactor, the operating frequency of the balun can be tuned continuously. Also, by arranging the two loops on two layers, the difficulty in process caused by narrow gap can be avoided. Meanwhile, by introducing the lumped capacitors, the dimension of the balun is reduced greatly. The measured results indicate that the balun can operate at 620-1020 MHz when the voltage of varactor changes from 4 to 16 V. The phase difference of the two balanced ports is 180 7 , and the amplitude difference is less than 0.8 dB.The realized balun has a dimension of 19.6 16.8 mm 2 , equal to 0 25 0 29 ( 0 , the wavelength in vacuum at 620 MHz).

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