基于改进蚁群算法的机器人路径规划研究

针对基本蚁群算法在路径规划时出现收敛速度慢,易陷局部最优的问题,提出一种改进的蚁群算法。首先,为使算法在搜索时更具导向性引入方向夹角启发因子减少提高搜索速度;其次,融入A*算法的估价函数思想来改进启发函数,降低死锁可能性;最后,提出基于拉普拉斯概率分布的信息素挥发因子自适应策略,加快了算法收敛速度。多次仿真实验表明,所提出的改进算法能够快速,高效地寻找到最优路径,且路径质量优于基本蚁群算法规划出的路径。     

A compromise between piezoelectricity and transparency in KNN-based ceramics: The dual functions of Li2O addition

Transparent ceramics with good electrical performance have recently drawn broad interest as promising multifunctional materials. Here, we report that a superior transmittance (T = 75 % at 2000 nm) and good piezoelectricity (d₃₃ ∼ 150 pC/N) can be simultaneously realized in 0.93K_0.5Na_0.5NbO₃-0.07SrZrO₃ (KNN-SZ) ceramics by Li₂O regulation. The effect of Li₂O regulation has two parts: first, the presence of Li₂O facilitates the grain growth of KNN-SZ, considering that it melts at a relatively low temperature as a proper sintering aid; second, the introduced Li⁺ causes local lattice distortion, resulting in the coexistence of orthogonal and tetragonal (O–T) phases. The enlarged grains reduce the light scattering by grain boundaries for a higher optical transmittance; meanwhile, large grains stand as a prerequisite for the macroscopic domain structure favoured for decent piezoelectricity, which could also be partly caused by the coexistence of O–T phases. We believe that these findings might make KNN-based ceramics a preferable candidate for optoelectronic devices.     

消防服用多层织物的热防护性能

研究了消防服用多层织物的热防护性能,对单层织物的热防护性能及十种多层组合织物的热防护性能分别进行了研究分析,得出以下结论:就单层纤维成分相同的阻燃面料而言,热防护系数(TPP)值与织物的厚度、面密度具有显著的正相关性;多层组合织物中,外层及防水透湿层为覆聚四氟乙烯(PTFE)膜的阻燃帆布、隔热层为芳纶1313针刺毡、舒适层为芳纶-阻燃黏胶的8#样品的防护性能最好,就阻燃防护性能方面而言,是最适合用于消防员灭火消防服的面料。     

绿色有机蒙脱石的制备、表征及其抗菌活性

为了提高天然粘土矿物的除藻能力,并降低其对环境的毒性,本研究使用环境友好型季铵盐[1,5-(戊撑)双(N,N’-乙酸十二酯溴化铵)对粘土矿物进行了改性,制备了新型的有机粘土矿物O-MMT2。对O-MMT2进行了结构表征和抗菌特性的研究。结果表明,相对于天然粘土矿物有机粘土矿物O-MMT2的表面疏水性有了明显的提高。O-MMT2的抗菌活性不但优于天然的粘土矿物,而且也优于单季铵盐十六烷基三甲基溴化铵改性的粘土矿物O-MMT1。在使用量分别为0.6 g/L和1.0 g/L时,O-MMT2就可以完全杀死藻类和细菌,而对于O-MMT1要达到同样的效果,则分别需要1.0 g/L和1.2 g/L。     

耐水性水性聚氨酯合成工艺研究

选用聚醚多元醇与聚酯多元醇进行复配,制得耐水性较好的WPU。以DMBA作为亲水扩链剂,探讨了DMBA加入方式以及聚氨酯自乳化方法对水性聚氨酯外观、稳定性、成膜性能的影响。     

Ecology dynamics model on Chinese apparel industry cluster

To explore the crucial driving forces and dynamics of the Chinese apparel industry cluster, the authors analysed current situations, characteristics and the dilemma in the Chinese apparel industry based on surveys conducted in the Yangtze River Delta. This study classified the factors impacting apparel industry cluster development into necessary conditions and evolutionary factors according to logistic differential equation, and proposed a dynamics model framework of apparel industry cluster with positive and negative feedback mechanism. The authors believe that the Chinese apparel industry cluster is an ecology system involving outsourcing, specialisation agglomerating, competition, resource complementary, etc. and has a quick response ability of adapting to environment.     

In situ hydrothermal synthesis of Y-TiO2/graphene heterojunctions with improved visible-light-driven photocatalytic properties

The Y-TiO₂/graphene heterojunctions were prepared using a facile one-pot hydrothermal method. The SEM and TEM images showed that titanium dioxide and flaky graphene were tightly bound together, and XPS indicated that yttrium was doped uniformly into the complex. The crystal phase of titanium dioxide in Y-TiO₂/graphene composite was anatase, and the yttrium doping caused distortion of the titanium dioxide lattice, resulting in a new valence type and more defects. An appropriate amount of yttrium doping and graphene modification significantly improved the separation of photogenerated electron-hole pairs. In the degradation of rhodamine B, the co-modification of yttrium and graphene effectively improved the photocatalytic activity under visible and UV–vis light irradiation. With the amount of yttrium increasing, the photocatalytic activity of the Y-TiO₂/graphene complex first increased and reached the highest level of 40% and 63% for visible and ultraviolet-visible light, respectively, when the ratio of yttrium was increased to 1.0%. The enhancement of photocatalytic activity can be explained by the presence of yttrium ions increased the visible light absorption of titanium dioxide. Besides, the synergistic effect between yttrium ions and graphene effectively improved the separation rate of photoinduced electron-hole pairs.     

基于旋滚比的电主轴轴承预紧力优化研究

为研究不同工况下轴承预紧力对电主轴轴承动力学的影响规律,基于外轨道控制理论,建立了一种以旋滚比可优化的轴承预紧力动力学模型。通过分析高速状态下滚动体载荷和特征参数动态变化过程,构建综合考虑滚动体滚动、自旋转、陀螺运动和离心力的轴承动力学分析模型,在此基础上,计算旋滚比动态变化结果;研究Jones发现的阈值与旋滚比之间的动态定量映射关系;以轴承滚动体打滑状态为优化目标,使用MATLAB仿真分析不同工况下轴承最佳预紧力。建模分析表明,轴承旋滚比大小可以反映轴承预紧效果,也可实现轴承预紧力动态定量优化。     

基于MRGP的普适计算可用性度量

普适计算模式追求随时随地的计算境界,对可用性管理提出了很高的要求。该文基于定量分析的角度,提出了一种基于马尔科夫重生过程(MRGP)的普适计算系统可用性度量方法,以解决关联用户的普适计算系统可用性度量问题。建立了具有双扩展特点的用户模型,分析了用户行为特征;构建了普适计算系统可用性的MRGP模型,对可用性进行了随机过程分析,并给出了对应瞬态和稳态行为的度量方法;结合普适计算模式的特点,定义了普适计算系统请求可用性度量。进行了数值分析,评价了用户和系统参数等因素对普适计算系统可用性度量的影响。     

Accurate segmentation of land regions in historical cadastral maps

Historical cadastral maps are valuable sources for historians to study social and economic background of changes in land uses or ownerships. In order to conduct large-scale historical research, it is essential to digitize the cadastral maps. As being established in antiquity, however, they suffer from significant noise artifacts attributed to hand-drawn cartography. In this paper, we propose a novel method of extracting land regions automatically in historical cadastral maps. First, we remove grid reference lines based on the density of the black pixel with the help of the jittering. Then, we remove land owner labels by considering morphological and geometrical characteristics of thinned image. We subsequently reconstruct land boundaries. Finally, the land regions of a user’s interest are modeled by their polygonal approximations. Our segmentation results were compared with manually segmented results and showed that the proposed method extracted the land regions accurately for assisting cadastral mapping in historical research.