Two-step anodization of maltilayer TiO2 nanotube and its photocatalytic activity under UV light

A double-layer TiO2 nanotube arrays were formed by two-step anodization of Ti foils in different electrolytes. First, Ti in 0.5 wt% HF was anodized to form thin nanotube layer. Afterwards a second anodization was conducted in a formamide based electrolyte, which allowed the second layer of nanotube growing directly underneath the first one. From FESEM investigation we found that the thickness of second layer corresponded to the anodization time, the increasing of which would lead to the excessive etching on the first layer. The first layer protected the lower one from fluoride corrosion during anodization process. The double layer TiO2 nanotube arrays showed no benefit to photodegradation effect in methyl orange degradation experiments.     

一类大时滞网络控制系统的H_∞鲁棒控制

研究一类大时滞不确定网络控制系统的输出反馈H∞鲁棒控制问题。将具有随机大时滞的网络控制系统模型化为具有不确定系数的离散时间系统模型,然后利用构造的Lyapunov函数和线性矩阵不等式,证明并给出了输出反馈H∞鲁棒控制问题有解的充分条件。所设计的控制器使系统具有鲁棒性,能满足所给H∞范数指标。最后通过算例验证结果的有效性。     

基于模糊控制的锂动力电池快速充电技术研究与实现

锂动力电池充电过程和具有多变量、离散性和非线性等特点,传统的PID控制很难从它的数学模型出发进行控制,而模糊控制技术可以不要数学模型进行控制。将模糊控制技术应用于充电控制,提出了模糊PID的充电模型,并与PID控制模型进行对比。仿真实验证明该充电模型具有充电时间短、鲁棒性强等特点,具有重要的实际意义和推广价值。     

加强型和削弱型梁柱节点对钢框架性能的影响

针对加强型和削弱型两种梁柱连接节点,分别进行了钢框架的有限元单向加载和循环加载分析,探讨了两种节点类型对结构承载能力、抗侧刚度、耗能能力等性能的影响.有限元计算结果表明:两种节点都可以使梁端形成塑性铰,具有较好的耗能能力,但与削弱型节点相比,加强型节点可以显著提高钢框架的屈服荷载、抗侧刚度和极限承载力,而且有效降低了梁端翼缘的轴向应力,便于实现强连接弱构件,更适合于抗震设防地区采用.     

线上线下结合的实时手势跟踪系统

手势识别跟踪一般采用线下训练分类器,不能有效检测跟踪形变的手势,针对手势形变及在窗口的暂时性消失等问题,提出了一种通过线下训练结合线上提取样本对分类器进行训练的检测方法,同时采用跟踪一检测一学习(TLD)的方法不断对跟踪器的结果进行纠正.试验结果表明,本算法对手势形变、短暂消失具有很好的适应性,与TLD算法相比较具有更好的稳定性.     

基于多颜色空间信息融合的视频车辆检测方法

利用图像颜色空间各分量的相对独立性和互补性,通过理论分析和实验,提出了有选择地将RGB、YCbCr和HSI3个颜色空间9个分量的检测结果进行融合的方法,提高了车辆视频检测的准确性。该法在S和I分量较大时依据H分量的值选择不同3个分量的检测结果进行有差别融合,而S和I分量较小时再选择另外3个分量的检测结果融合。实验证明,同只利用亮度分量的检测结果相比,检测到的车辆更加充实,空洞大幅度减少,很大程度提高了依赖于该结果的交通信息数据的精确性。     

基于精益供应链的工程建设项目价值分析

结合精益供应链理论,以价值作为方案决策要点,对工程建设项目价值分析进行研究,通过案例说明价值分析在工程建设项目中的应用流程。采用模糊质量功能展开法综合评价各方案的价值,并进行对比分析,找出价值最优方案。基于精益供应链的工程建设项目价值分析是一种行之有效的方案决策方法。     

Overcoming challenges in the study of nitrided microalloyed steels using atom probe

Nitrided steels are widely used in the engineering field due to their superior hardness and other attractive properties. Atom probe tomography (APT) was employed to study two Nb-microalloyed CASTRIP steels with different N contents. A major challenge of using APT to study this group of materials is the presence of tails after Fe peaks in the mass spectra, which overestimates the composition for alloying elements such as Nb and Cu in the steels. One important factor that contributes to the tails is believed to be delayed field evaporation from Fe²⁺. This artefact of the mass spectrum was observed to be the most severe when voltage pulsing was used. The application of laser pulses with energy ranging from 0.2 to 1.2 nJ successfully reduced the tails and lead to better compositional measurement accuracy. Spatial resolution in the z-direction (along the tip direction) was observed to be less affected by changing laser energy but deteriorates in x-y direction with increasing laser energy. This investigation suggests that pulsed-laser atom probe with ∼0.4 nJ laser energy can be used to study this group of materials with improved mass resolution while still maintaining high spatial resolution.     

Nanofiltration process of glyphosate simulated wastewater

Nanofiltration separation of glyphosate simulated wastewater was investigated using a DK membrane. The effects of operating parameters and the addition of impurities on membrane performance were studied in detail. It was found that at 20 °C, with a glyphosate concentration of 500 mg/L and pH of 2.96, the glyphosate retention rate and the membrane permeate flux increased slightly with increasing transmembrane pressure. With an increase in operating temperature, the permeate flux increased linearly while the retention rate decreased. The permeate flux and glyphosate retention rate decreased with increasing feed concentration. Within the pH range of 3-5, the glyphosate retention rate decreases with increasing pH and reaches a minimum at the isoelectric point of the membrane, while the permeate flux reaches a maximum level at this point. In the pH range of 5-11, with the increases of pH, the glyphosate retention rate increases and the permeate flux decreases. Glyphosate retention decreases slightly with increasing NaCl and phosphite concentrations. This can be explained in terms of the shielding phenomenon.