球棒系统的近似线性化及Matlab实现

以典型多变量非线性系统一球棒系统为研究对象,用微分几何理论中的状态反馈的近似线性化方法设计该非线性系统的控制器.无论小球在棒的什么位置,棒的角度如何,该控制方法都能使小球稳定在棒的中心位置.利用数学工具Mat-lab仿真此过程,给出了Matlab具体实现模块,结果表明状态反馈方法的有效性.     

基于ETAP的海上风电场接入对电能质量的评估分析

由于海上风资源的多变性,以及风力发电机中存在较多的电力电子元器件,海上风电场并网后会产生电能质量问题。本文选取某海上风电场作为研究对象,基于风电场实际运行数据,参考国标规定,对该风电场的电能质量（电压偏差、电压闪变、电压波动、谐波）进行求解。基于风机的无功特性,本文对某海上风电场接入电网公用变电站的无功补偿容量进行研究。在电能质量计算与分析方面,参考相关规程规定,完成电压偏差、电压闪变、电压波动部分指标的限值与实际值计算,并进行对比;通过ETAP软件中的谐波分析模块,进行谐波模拟仿真,得到谐波指标的实际值,并与理论计算的限值对比。当谐波电流超出国家标准的时候,通过在母线接入单调谐滤波器的方法,进行谐波治理,达到电能质量相关要求。     

Shareability-Exclusivity Representation on Product Grassmann Manifolds for Multi-camera video clustering

With the rapid popularity of multi-camera networks, one human action is usually captured by multiple cameras located at different angles simultaneously. Multi-camera videos contain the distinct perspectives of one action, therefore multiple views can overcome the impacts of illumination and occlusion. In this paper, we propose a novel multi-camera video clustering model, named Shareability-Exclusivity Representation on Product Grassmann Manifolds (PGM-SER), to address two key issues in traditional multi-view clustering methods (MVC): (1) Most MVC methods directly construct a shared similarity matrix by fusing multi-view data or their corresponding similarity matrices, which ignores the exclusive information in each view; (2) Most MVC methods are designed for multi-view vectorial data, which cannot handle the nonlinear manifold structure hidden in multi-camera videos. The proposed PGM-SER firstly adopts Product Grassmann Manifolds to represent multi-camera videos, then simultaneously learn their shared and exclusive information in global structures to achieve multi-camera video clustering. We provide an effective optimization algorithm to solve PGM-SER and present the corresponding convergence analysis. Finally, PGM-SER is tested on three multi-camera human action video datasets and obtain satisfied experimental results.     

基于流量调度的多链路负载均衡算法

针对多重上联链路负载不均衡问题,提出CIAP算法。基于链路时延和剩余带宽的协方差值,对路由表进行二次调整,调用PBA算法将IP碎片映射到各个链路上,使多链路负载达到相对均衡。实验结果表明,在网络重载状况下,CIAP算法的优化性能较DTIA有较大提高。     

免疫检测器证据理论集成的机组复合故障诊断

针对机组复合故障诊断准确率较低的状况,基于免疫机理的人工免疫智能方法,构建对故障比较敏感的无量纲指标免疫检测器．采用自适应调节匹配阈值和从非己空间产生的候选检测器,能有效减少黑洞和边界不清晰．通过免疫编程优化策略获得最佳识别能力的新特征指标．利用证据理论对多类免疫检测器进行集成诊断,提炼出能直接应用于复合故障诊断的优秀无量纲免疫检测器,机组实验结果表明,所得免疫检测器能快速、准确地进行复合故障诊断．     

Validity of facial features’ geometric measurements for real-time assessment of mental fatigue in construction equipment operators

Operating construction equipment for extended periods of time may lead to mental fatigue and, as a result, an increased risk of human error-related accidents and jeopardized health problems for the operators. Therefore, to limit the risk of accidents and protect operators' wellbeing, their mental fatigue must be monitored reliably and in real time. Recently, many invasive technologies have been employed to alleviate this problem, but they entail the wearing of physical sensors, which may instigate irritation and discomfort. This study proposes a non-invasive mental fatigue monitoring method using geometric measurements of their facial features that does not require the operators to wear sensors on their body. The study further validates the proposed method by comparing it with wearable electroencephalography (EEG) technology to establish its ecological validity for construction equipment operators. To serve the purpose, a one-hour excavator operation by sixteen construction equipment operators was conducted on a construction site. Ground truth, brain activity using wearable EEG, and geometric measurements of facial features were extracted and analyzed at the baseline and every 20 min for one hour. A considerable temporal variation was found in the reported metrics (eye aspect ratio, eye distance, mouth aspect ratio, face area, and head motion) and were significantly correlated with ground truth and EEG metric. Furthermore, the brain visualization pattern obtained from EEG was also associated with the variations in the facial features. The findings of the study reveal that construction equipment operators’ mental fatigue can be monitored non-invasively using geometrical measurements of facial features.     

Investigation into microstructure of carbon nanotube multi-yarn

Structural analysis at the nano and micro scale was performed on a carbon nanotube (CNT) multi-yarn. The yarns were made by a process of drawing CNTs into a ribbon and twisting the ribbon into a yarn. Scanning electron microscopy (SEM) was used to view the exterior of the yarn. Polarized microscopy was used to examine details of the 1-yarn, and it also identified ribbon–ribbon boundaries. Further examination of interior structure was done by NanoCT scans which showed that folding of the ribbons had occurred causing complicated structures. The interior folding was found by milling into the yarn with a focus ion beam gun (FIB) and imaging with SEM. These different methods thus provided various microstructural details (structure, ribbon–ribbon boundary, folding and void fraction) of CNT multi-yarn which could be used to compare with other yarns fabricated with different procedures/sources as well to provide parameters for analytical tools. Further, these microstructural details can be related to macro mechanical and physical properties.     

Photoluminescent and electrical properties of novel Nd3+ doped ZnV2O6 and Zn2V2O7

Nd³⁺ doped ZnV₂O₆ and Zn₂V₂O₇ samples were synthetized by using melt-quenching method. X-ray diffraction patterns indicate that both samples are polycrystalline. The crystallinity was also verified by Raman scattering, from which the different vibrational modes of ZnV₂O₆ and Zn₂V₂O₇ were detected. Electron dispersive spectroscopy (EDS) analysis shows that the Nd³⁺ incorporation into the ZnV₂O₆ and Zn₂V₂O₇ hosts is around 0.9±0.1 and 0.2±0.1 at%, respectively. The micrographs obtained by Scanning Electron Microscopy, reveal that the Nd³⁺ doped ZnV₂O₆ sample is predominantly composed by micro-rods, whereas the Nd³⁺ doped Zn₂V₂O₇ one is only composed by irregular blocks. The band gap energies (E_g) were calculated from the diffuse reflectance spectra by the Kubelka–Munk equation; E_g values resulted to be 2.24 and 2.86 eV for the Nd³⁺ doped ZnV₂O₆ and Zn₂V₂O₇ samples, respectively. By means of two points dark conductivity measurements, conductivity values in the 10⁻⁴–10⁻⁶ and 10⁻⁶–10⁻⁸(Ω cm)⁻¹range for the Nd³⁺ doped ZnV₂O₆ and Zn₂V₂O₇ samples were measured, respectively. The conductivity as a function of the temperature indicated a semiconductor behavior. The photoluminescence spectra upon Ar⁺ laser excitation at 488 nm, exhibited the Nd³⁺ characteristics emissions. For instance, the Nd³⁺ doped ZnV₂O₆ sample displayed the Nd^{3+ 4}F_5/2→⁴I_9/2 and ⁴F_3/2→⁴I_9/2 emissions; while the Nd³⁺ doped Zn₂V₂O₇ one showed the Nd³⁺ characteristic emissions associated with the ⁴G_7/2, ⁴F_9/2, ⁴F_5/2 and ⁴F_3/2→⁴I_9/2 transitions. The lifetimes were 80 and 130 µs for the Nd³⁺ doped ZnV₂O₆ and Zn₂V₂O₇ samples, respectively. All these results suggest a successful synthesis of Nd³⁺ doped zinc vanadate compounds by the melt-quenching technique.     

欠发达地区高职院校人才培养模式的探究——以茂名职业技术学院为例

高职院校人才培养模式的发展具有极强的区域性和地方性,从欠发达地方区域产业发展的角度,以茂名职业技术学院人才培养模式为例,从工学结合人才培养的实践形式和手段出发,分析当前欠发达地区工学结合人才培养模式的现状、困难及改革方向。     

Synthesis of needle-like aragonite from limestone in the presence of magnesium chloride

Needle-like aragonite was synthesized with a reversible solution reaction from limestone without calcinations. Scan Electron Microscope (SEM) and X-ray Diffraction (XRD) were used to characterize the morphology and the crystal structure of aragonite. The synthesis of aragonite whisker involves two steps. At first GCC (Ground Calcium Carbonate) was dissolved in an aqueous solution of magnesium chloride with reflux and air flush. Then CO₂ was bubbled into the suspension at a low temperature to produce aragonite whisker. An in-house designed reactor and acid–base titration analysis were used to measure the remaining GCC content in the reaction mixture. A kinetics equation of GCC dissolution was developed, which showed a first-order kinetic feature to magnesium chloride concentration. A reaction rate constant of 0.04234 h^?1 was obtained. The dissolution rate of GCC in magnesium chloride is much higher than that in the magnesium sulfate solution. Some aragonite whiskers with a length of ca. 20 μm and an aspect ratio of 8–12 can be synthesized.