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Definition based on the incremental theory of plasticity of J integral, combining the method of experiment and computer simulation, the method of crack propagation rate based on elastic-plastic mechanics is studied, the research shows that the crack growth rate curve obtained by the incremental plastic J integral is well described the material fracture mechanics performance characteristics, ΔJ integral as the crack growth driving force is verified the rationality of the parameters, in order to further research to explore mechanism of crack extension provides research foundation, a new model is proposed based on the 7N01 aluminum alloy test data, it takes into account the effect of stress ratio on crack propagation, and it is suitable for estimating fatigue life of materials in engineering practice.

In order to obtain the novel poly(ε-caprolactone) (PCL) cross-linked networks with good shape memory properties, the cross-linked networks of PCL with different molecular weights were prepared by thiol-ene click chemistry method, and its microstructure, thermal properties, mechanical properties and shape memory properties were characterized. The results show that the hydroxyl end of PCL was successfully converted to acrylate-terminated PCL, and almost all the samples show perfect cross-linked network, and the cross-linked polymer has a thermally induced shape memory effect; with the increase of the molecular weight of PCL diol, the melting temperature and crystallinity of the cross-linked network also show an upward trend; the molecular weight of PCL diol has a certain influence on its fixation ability, but regardless of the length of PCL diol, the shape recovery rate of all samples can reach more than 90%. The efficient thiol-ene click chemistry reaction ensures the uniform distribution of PCL chains between cross-linked nodes, the cross-linked network has good network structure, good mechanical and shape memory properties. The exploration of new PCL cross-linked network provides a feasible way for the end functionalization of polymers.

The paper discusses teaching mode of European universities during the epidemic period and proposes the characteristics of digital education which has realized another ideological change from face-to-face teaching to self-learning and from systematic teaching output to individual learning input. Hence the shift can also be understood as the change from digital education to literacy education centered on flexible learning. Based on shift from digital education to literacy education in European universities the developing trend of literacy education in European universities during the epidemic period are put forward in the construction of lifelong education in Europe.

High-resolution synthetic aperture radar presents a significant challenge to imaging algorithms and computing power. Slide spotlight is an important mode that has both high resolution and wide azimuth swath. Generally, in the slide spotlight mode, the performance of conventional frequency domain imaging algorithms degrades because of orbit curvature, the time-variant azimuth chirp rate, and other factors. We adopt the Back-Projection (BP) algorithm in this study to counteract this limitation. We also propose a CPU/GPU heterogeneous BP algorithm to deal with the high computing complexity O(N3) of the BP algorithm. This heterogeneous BP algorithm makes full use of computing resources and accelerates imaging progress, and the design of a scheduling thread improves the flexibility of the algorithm.

Batch time requirements are provided for the separation of binary zeotropic mixtures in two different multivessel columns (with and without vapor bypass), a non-cyclic two-vessel column and a regular batch column based on dynamic simulations. The first three columns are operated as closed (total reflux) systems and the regular batch column is operated as an open (partial reflux) system. We analyze the effects of feed composition, relative volatility and product specification on the time requirements. The multivessel arrangements perform better than the regular batch column, which requires from 4.00 to 34.67% more time to complete a given separation. The elimination of the vapor bypass in the multivessel column is impractical though it has a positive effect on the batch time requirements. Thus, the multivessel column, with the vapor stream bypassing the intermediate vessel, is proposed as the best candidate for a binary zeotropic mixture with low concentration of light component, low relative volatility and high product purity demand. Furthermore, an experimental multivessel column with vapor bypass is built and the corresponding experiments verify the simulations.

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.