Distributed patching for mobile wireless sensor networks

Mobile wireless sensor networks (MWSNs), the continuous movement of sensor nodes, may cause complete disconnection of the network or at best a part of it. The design of such networks should guarantee that all sensor nodes at all times have a path to the sink node(s). Prolonging the lifetimes of the MWSNs is a crucial design issue but should not be at the expense of other essential functions such as connectivity. In this paper, we propose an energy efficient distributed framework for connectivity maintenance of MWSNs. In the proposed framework, sensor nodes of the MWSNs schedule and control their radio frequency (RF) modules based on dynamic coordinated reconstruction mechanism, some senor nodes may lose their connectivity with the network due to mobility, depletion of energy and/or incurred faults. Two protocols are developed to patch up the disconnection of the MWSNs. The first protocol reestablishes the network connection consuming far less energy than state-of-the-art alternatives. However, it is capable of reestablishing the connection when no more than 20% of the MWSN backbone nodes lose connection concurrently. The second protocol extends this limit to operate when up to 35% of the MWSN backbone nodes lose connection simultaneously.     

一步法制备芳基微孔聚酰亚胺及其性能表征

以均苯四酸二酐和多苯基多异氰酸酯为原料,采用一步合成法,通过浇注发泡成型,限定空间发泡,制备了一种孔径均匀的微孔聚酰亚胺材料。经红外光谱测定,在1 778cm-1、1 723cm-1、1 371cm-1处观察到聚酰亚胺特征峰。扫描电镜照片显示,所得聚酰亚胺微孔材料孔径均匀,闭孔结构,泡孔平均尺寸在0.2～0.3 mm之间,密度为0.4g/cm3。热失重分析结果表明,微孔聚酰亚胺样品的起始分解温度为550℃,热稳定性较好。力学性能测试结果表明,在样品形变量为10%时,抗压强度为6.12MPa。     

Novel transparent and flexible nanocomposite film prepared from chrysotile nanofibres

In the present study, chrysotile nanofibres, obtained from physicochemical dispersion of natural chrysotile, were used to prepare nanofibre sheets by vacuum filtration. As-prepared sheets were then impregnated by UV-curable resin and cured by ultraviolet light to fabricate the flexible and transparent nanocomposite films. Observed from SEM, the transparent films showed a smooth surface and a typical sandwich structure in cross section, viz. nanofibre sheet filled with resin was sandwiched by two layers of resin. XRD patterns indicated the amorphous nature of cured resin and characteristic crystallographic structure of chrysotile in nanocomposite films. Though the nanofibre sheets were white in colour, and nanofibre contents in nanocomposites were as much as 43.4 wt%, the nanocomposite films displayed an excellent optical transparency with about 85% light transmittance in the visible light range. Tensile tests showed that the addition of nanofibres resulted in a great improvement in mechanical strength of the nanocomposite films; with the increase of nanofibre contents, the modulus and tensile strength of nanocomposite films increased gradually.     

数字图像三点中值去隔行技术研究

对传统三点中值去隔行算法进行改进,采用同步更新迭代的方法,提高了图像的画面质量.实验证明,该算法不仅降低了时间复杂度,保护图像边缘,而且明显改善了噪声滤波效果.     

Elevated temperature combined erosion-corrosion of steels

The effects of erodent particle size and elevated temperatures on the combined erosion-corrosion behavior of a series of chromium-containing steels were investigated in an oxidizing gas stream.It was determined that corrosion was the dominant mechanism at all test conditions for all alloys. Particle impacts enhanced the growth rate of multilayered iron oxide and Fe-Cr oxide spinel scales and markedly changed the morphology of the scale surface and the thickness of the various scale layers.     

Staebler-Wronski effect is a bulk effect

The temperature dependence of dark conductivity (G_d) and the spectra of photoconductivity (G_p) of GD a-Si:H films with top coplanar, bottom coplanar and staggered sandwich electrode configurations were measured and compared for two states of the samples: after annealing in vacuum at 200°C for 1 h (state A) and then exposed to 6000–9000 Å light (200 mW/cm²) for 3 h (state B). Both G_d and G_p decrease significantly after the transition of the films from state A to state B. However, the curves for three kinds of samples almost coincide, which proves the bulk nature of the Staebler-Wronski effect.     

四川盆西平原区裸土扬尘中Pb、Cd化学形态的生物有效性

为探究四川盆西平原区裸土扬尘中Pb、Cd总质量分数与其生物有效性的规律,在构建的"阳离子型污染物土壤表层运移行为研究系统"内进行模拟起尘试验,对土壤样品进行Pb、Cd模拟污染试验,结果表明:试验条件下,四川盆西平原区裸土扬尘颗粒物中Pb、Cd的总质量分数随着粒径的减小而增大,其中Pb的化学形态以碳酸盐结合态为主(44....     

No reference image blurriness assessment with local binary patterns

In this paper, we put forward an effective and efficient no reference image blurriness assessment metric on the basis of local binary pattern (LBP) features. In this proposal, we reveal that part of the LBP histogram bins present monotonously with the degree of blurriness. The proposed method contains the following steps. Firstly, the LBP maps of an input image are extracted with multiple radiuses. And then, the frequency of pattern histogram is analyzed before part of bins are chosen as the features. In addition, we also take the entropy of these bins as another feature. Finally, we learn the extracted features to predict the image blurriness score. Validation of the proposed method is conducted on the blurred images of LIVE-II, CSIQ, TID2008, TID2013, LIVE3D IQA Phase I and LIVE3D IQA Phase II. Experimental results demonstrate that compared with the state-of-the-art image quality assessment (IQA) methods, the proposed algorithm has notable advantage in correlation with subjective perception and computational complexity.