旋滤波法对噪声抑制作用的仿真比较研究

在光学干涉条纹图像处理方法中,旋滤波法得到广泛的使用,但是当噪声比较大时,不能准确的求出条纹方向图,无法得到很好的滤波效果。本文以仿真为方法研究噪声对旋滤波法的影响,并指出条纹图预处理的重要性。仿真结果表明,当噪声强度大于0.125时可以加入中值或者均值滤波作为预处理,可以有效的抑制噪声。     

空间目标姿态吊挂控制装置半实物仿真研究

文中运用静力学中的空间任意力系平衡的两个必要与充分条件,结合实际目标姿态吊挂控制系统的结构特性,建立了空间目标吊挂模型姿态调整的数学模型,后联立并求解多元方程组,得到在各种确定姿态下的各吊绳的长度,准确的实现整个目标姿态吊挂控制系统对目标模型的姿态调整.     

一种加速的PCA-L1 增量子空间学习跟踪方法

为解决PCA-L1增量子空间学习跟踪方法运算量大、实时性不强的不足,分析了PCA-L1的目标跟踪算法的运算瓶颈,应用、改进了边界误差重采样(bounded particle resampling,BPR)算法,引进了加速近似梯度法(accelerated proximal gradient,APG),并测试、比较了该方法与其他经典方法的跟踪效果及运算速度.实验结果表明:该方法加速效果明显,能提高跟踪的实时性,有较强的工程应用价值.     

基于提升可靠性关键措施的配电网规划实用方法

随着配电网用户对供电质量要求日趋增强,提高供电可靠性已成为配电网规划中关注的热点。针对传统电网可靠性规划存在的目标性弱或可操作性不强等弊端,提出一种基于提升供电可靠性关键措施的配电网规划实用方法。结合国内的配电网接线模式及运行、检修特点,建议重点采用"双接入"和"小分段"接线模式。通过实际数据评估和应用分析,验证了该方法可在短期内大幅提升供电可靠性。     

基于物元模型的电力系统中长期负荷预测

在综合考虑电力负荷预测及物元理论特点的基础上,将两者结合,提出了一种基于物元理论(可拓工程学)的中长期负荷预测方法,对物元理论在电力系统中的实际运用进行了探讨.方法首先运用逐步回归与层次分析技术确定各种因素对电力负荷的影响权重,然后利用物元理论对选中的各影响因素与电力负荷及其增长率建立物元模型,再根据系统聚类分析的方法对电力负荷及其相关环境因素的历史样本进行归纳分类,最后采用合适的物元关联函数及灰色关联函数结合未来环境因素状态对未来负荷变化模式进行识别,从而预测出电力负荷的未来值.并以我国某地区的中期负荷预测为例,说明了其有效性.     

浅议现有变电站备用电源自投装置

采用现场统计数据分析目前备用电源自动化投入装置存在的问题,并探讨解决方向.     

Physical and thermal properties of l‐lactide/ϵ‐caprolactone copolymers: the role of microstructural design

Understanding the underlying role of microstructural design in polymers allows for the manipulation and control of properties for a wide range of specific applications. As such, this work focuses on the study of microstructure–property relationships in l‐ lactide/?‐caprolactone (LL/CL) copolymers. One‐step and two‐step bulk ring‐opening polymerization (ROP) procedures were employed to synthesize LL/CL copolymers of various compositions and chain microstructures. In the one‐step procedure, LL and CL were simultaneously copolymerized to yield P(LL‐<i>stat</i>‐CL) statistical copolymers. In the two‐step procedure, poly(l‐ lactide) (PLL) and poly(?‐caprolactone) (PCL) prepolymers were synthesized in the first step before CL and LL respectively were added in the second step to yield P[LL‐<i>b</i>‐(CL‐<i>stat</i>‐LL)‐<i>b</i>‐LL] and P[CL‐<i>b</i>‐(LL‐<i>stat</i>‐CL)‐<i>b</i>‐CL] block copolymers as the final products. The findings reveal that, in addition to the copolymerization procedure employed, the length and type of the prepolymer play important roles in determining the chain microstructure and thereby the overall properties of the final copolymer. Moreover, control over the degree of crystallinity and the type of crystalline domains, which is controlled during the polymer chemistry process, heavily influences the physical and mechanical properties of the final polymer. In summary, this work describes an interesting approach to the microstructural design of biodegradable copolymers of LL and CL for potential use in biomedical applications. © 2019 Society of Chemical Industry     

Effect of the composition and degree of crosslinking on the properties of poly(l‐lactic acid)/crosslinked polyurethane blends

Poly(l ‐lactic acid)/crosslinked polyurethane (PLLA/CPU) blends which were prepared via reactive blending of PLLA with poly(<i>?</i>‐caprolactone) (PCL), glycerol and 4,4′‐methylenediphenyl diisocyanate showed excellent toughness. The effects of the composition of the mixture and degree of crosslinking of CPU on the toughness of the PLLA/CPU blends (80/20 w/w) were studied in detail. Dynamic mechanical analysis and rheological measurements were used to characterize the structure of the <i>in situ</i> formed CPU in the PLLA matrix. A novel netlike phase structure was observed when the average molecular weight of PCL and degree of crosslinking were 1 kDa and 10%, respectively. The impact strength of the blend was enhanced from 2.2 kJ m<sup>?2</sup> for pure PLLA to 62.4 kJ m<sup>?2</sup>; meanwhile, the elongation at break was increased to 489.8%. Therefore, the mechanical properties of PLLA/CPU blends can be easily tailored by tuning the composition of the mixture and the degree of crosslinking of CPU. © 2018 Society of Chemical Industry     

Influence of aliphatic polycarbonate middle block on mechanical and microstructural behaviour of triblock copolymers based on poly(l‐lactide) and polycarbonate

Three different ABA‐type triblock copolymers each containing biodegradable aliphatic polycarbonate as the middle block and poly(l ‐lactide) as the outer blocks were synthesized and the influence of the methylene chain length of the aliphatic polycarbonate middle block on various properties of the triblock copolymers was evaluated. Differential scanning calorimetry and wide‐angle X‐ray diffraction studies revealed that the incorporation of the outer blocks reduced the crystallinity of the middle aliphatic polycarbonate block. Variation of methylene chain length of the middle block led to a change in morphology from spherical to cylindrical as evidenced from atomic force microscopy studies. In addition, the mechanical properties of the block copolymers showed semi‐ductile to quasi‐brittle behaviour depending upon the composition of the middle block which was also confirmed using scanning electron microscopy. Dynamic mechanical analysis of the triblock copolymers indicated that storage modulus increased with a decrease in methylene chain length. © 2018 Society of Chemical Industry