Posture Control for Personal Mobility Robot Using Feedback Compensation with Unstable Pole

This paper presents a novel posture control approach using feedback compensation with an unstable pole. For a narrow and small personal mobility robot (PMR), this is needed in order to control its posture for achieving quick turning and high acceleration. However, in the conventional control approach that uses the posture angle as a controlled variable, the zero moment point (ZMP) does not settle to the desired point in the following cases: an unknown disturbance force given to the PMR, a fluctuation in the center of gravity of the PMR, and a change in the conditions between the tires and the road surface. In this paper, a novel control method using feedback compensation with an unstable pole is proposed to achieve the desired ZMP in the steady state. The proposed controller changes the control input for the actuator of posture control to zero in order to achieve the desired posture angle. The effectiveness of the proposed approach is verified through experiments using a prototype of the PMR.     

基于ARM7的高精度频率计的设计

文章通过对相位重合检测技术的分析，提出了基于此理论并用ARM7作为主控芯片的高精度频率计的设计方法。该设计方法通过捕捉相位之间的重合点，能够有效消除±1个字的计数误差。在此基础上由于ARM7具有32位的处理器内核以及流水线技术，使得频率计的测量速度和精度比传统的使用16位单片机设计的频率计要高很多。本频率计最大测量频率为10MHz。同时本设计采用安捷伦公司生产的恒温晶振10811A作为标准频率，能够有效保证测量精度能够达到10-10量级。为了降低成本，在设计中选用采用ARM7芯片内部的计数器以及用简单的逻辑电路进行设计。由于其测量精度要超过多周期同步测量法，而成本又比模拟内插法和游标法低很多，因此此频率计拥有很广泛的市场前景。     

Recovery of polyphenols from camu-camu (Myrciaria dubia H.B.K. McVaugh) depulping residue by cloud point extraction

In this study the potential of cloud point extraction formed by a non-ionic surfactant was used in order to separate polyphenols from industrial residues of camu-camu. The effects of operational conditions of the cloud point extraction (CPE) on the polyphenol recovery and volumetric ratio were investigated. The results showed a maximum recovery of 95.71% that was obtained using 7.0 wt% Triton X-114, native pH (3.25), and 80 wt% polyphenol extract at 30 °C. The use of cloud point extraction was successful to recover the polyphenols from agroindustrial residue since it is a simple as well as of low-cost technique.     

Analysis of Cerebrospinal Fluid Extracellular Vesicles by Proximity Extension Assay: A Comparative Study of Four Isolation Kits

There is a lack of reliable biomarkers for disorders of the central nervous system (CNS), and diagnostics still heavily rely on symptoms that are both subjective and difficult to quantify. The cerebrospinal fluid (CSF) is a promising source of biomarkers due to its close connection to the CNS. Extracellular vesicles are actively secreted by cells, and proteomic analysis of CSF extracellular vesicles (EVs) and their molecular composition likely reflects changes in the CNS to a higher extent compared with total CSF, especially in the case of neuroinflammation, which could increase blood–brain barrier permeability and cause an influx of plasma proteins into the CSF. We used proximity extension assay for proteomic analysis due to its high sensitivity. We believe that this methodology could be useful for de novo biomarker discovery for several CNS diseases. We compared four commercially available kits for EV isolation: MagCapture and ExoIntact (based on magnetic beads), EVSecond L70 (size-exclusion chromatography), and exoEasy (membrane affinity). The isolated EVs were characterized by nanoparticle tracking analysis, ELISA (CD63, CD81 and albumin), and proximity extension assay (PEA) using two different panels, each consisting of 92 markers. The exoEasy samples did not pass the built-in quality controls and were excluded from downstream analysis. The number of detectable proteins in the ExoIntact samples was considerably higher (~150% for the cardiovascular III panel and ~320% for the cell regulation panel) compared with other groups. ExoIntact also showed the highest intersample correlation with an average Pearson’s correlation coefficient of 0.991 compared with 0.985 and 0.927 for MagCapture and EVSecond, respectively. The median coefficient of variation was 5%, 8%, and 22% for ExoIntact, MagCapture, and EVSecond, respectively. Comparing total CSF and ExoIntact samples revealed 70 differentially expressed proteins in the cardiovascular III panel and 17 in the cell regulation panel. To our knowledge, this is the first time that CSF EVs were analyzed by PEA. In conclusion, analysis of CSF EVs by PEA is feasible, and different isolation kits give distinct results, with ExoIntact showing the highest number of identified proteins with the lowest variability.     

基于功能参数的渐进成形件表面质量表征研究

目的 以圆锥台成形件为例，基于粗糙表面的区域支承率曲线，进行了用功能参数表征表面几何形貌的研究，以全面、准确、定量地表征渐进成形件的表面质量，预测表面性能。方法 用渐进成形工艺加工成形角分别为35°、45°和55°的圆锥台件，将各圆锥台的成形面分为顶部、中部和底部三个区域，并使用三维表面轮廓仪，在上述三个区域中随机测量各4个样本。根据ISO 25178-2:2012，将各样本表面的区域支承率曲线分为峰区、核心区和谷区，选用部分功能参数——核心区高度Sk、峰区材料体积Vmp、核心区材料体积Vmc和谷区空隙体积Vvv表征表面，并与常用的高度表征参数——Sa、Sq、Ssk和Sku进行比较。结果 成形件表面的Ssk和Sku的计算值极不稳定，变异系数（标准偏差与均值之比）最高值分别可达127.67%和39.11%，Sa、Sq的最大变异系数分别为4.41%和4.26%，虽然它们的参数计算值较为稳定，但常无法体现表面形貌的实际差异。功能参数独立表征不同功能区，Sk和Vmc的最大变异系数分别为9.32%和7.73%，说明同一表面各处，在长期工作阶段具有较为一致的表面性能，Vmp和Vvv的最大变异系数分别为60.53%和31.25%，说明表面各处峰、谷区的形貌有所不同，因而在磨合时间、磨粒存储等方面会有不同的表现。结论 粗糙表面的三维本质要求用三维表征参数才能全面表征其几何形貌。高度参数虽然计算简单，但常难以解读它们的物理意义，无法定量评价表面性能；功能参数具有明确的物理意义，可为表征表面质量、预测表面性能提供定量、实用的方法。     

降凝降黏剂在原油开采集输中的应用

降凝降黏剂已成为钻高难度的高温深井、大斜度定向井、水平井和各种复杂地层的重要手段,并且还可广泛地用作解卡液、射孔完井液、修井液和取心液等。由于稠油的黏度以及凝点低,防止在开采过程中出现困难,降凝降黏剂的应用需要进行一定的关注,解决其发展困难。     

Advance application of Raman spectroscopy for quantitative analysis of noncrystalline components in thin films of poly(ε-caprolactone)/poly(butadiene) blends

A quantitative analysis method for the distribution of noncrystalline poly(butadiene) component in poly(ε-caprolactone)/poly(butadiene) (PCL/PB) binary blends have been analyzed by advance application of Raman spectroscopy, optical microscopy, and differential scanning calorimetry (DSC) techniques. Thin films of different compositions of PCL/PB binary blends were prepared from solution and isothermally crystallized at a certain temperature. After calibration with real data, quantitative analyses by Raman spectroscopy revealed the amorphous PB are trapped inside the PCL crystals. Polarized optical microscopy and real time atomic force microscopy were used to collect data for the crystal morphology and crystal growth rate. For pure PCL crystals, a morphology of truncated lozenge shape was observed, independent of crystallization temperature and regardless of the blends compositions. For the pure PCL and their blends, almost unique crystal growth rate was found. The miscibility behaviors using DSC were drawn through melting point depression method. The Hoffman-Weeks extrapolations of the blends were found to be linear and identical with those of the neat PCL. The interaction parameter for the blends indicating that the PCL and PB blends have no intermolecular interaction, confirming the blends are immiscible. Despite the immiscibility of the blend, the PCL crystals do not bend during the growth process and do not reduce the growth rate as they do for miscible blend systems.     

Classification and identification of gas–liquid dispersion states in a jet bubbling reactor

Three gas–liquid dispersion states including flooding, loading, and complete dispersion are observed sequentially in a jet bubbling reactor with an increase of the liquid jet velocity at the nozzle outlet (u_j). The gas–liquid dispersion states are identified through the slope (k) of the curve of fluctuation distribution index (FI) versus u_j as follows: (a) under the flooding, k = 0; (b) under the loading, k > 0; (c) under the complete dispersion, k < 0. In particular, the u_j at the transition points from flooding to loading and from loading to complete dispersion are referred to flooding jet velocity (u_jf, the transition point between k = 0 and k > 0) and complete dispersion jet velocity (u_jcd, the transition point from k > 0 to k < 0), respectively. The average relative deviations of the u_j at the transition points obtained through the acoustic emission measurement and visual observation are less than 5%.     

区域自动气象站常见故障及维修方法

区域自动气象站当中的设施设备是否可以正常、稳定运行,不仅会直接决定气象监测工作质量,同时还会形成严重的经济损失。对此,为了更好地保障气象监测工作质量,文章简要分析区域自动气象站常见故障及维修方法,希望可以为相关工作者提供理论帮助。     

Enhanced control strategies for a hybrid battery/photovoltaic system using FGS-PID in grid-connected mode

This paper suggests improved control strategies using Fuzzy Gain Scheduling of Proportional-Integral-Derivative (FGS-PID) controller for a hybrid Photovoltaic (PV) and Battery Energy Storage (BES) system under different weather conditions. The proposed scheme is implemented using a two-level control system structure, combining the benefits of the PID as well as the fuzzy logic controller (FLC) for maximum power point tracking (MPPT). Ziegler-Nichols tuning method is also employed to select the initial values of PID gains. Within the period of steady-states and transients, FGS-PID adopts the gains to ensure the stability of the control scheme. It also damps out transient fluctuations and reduces settling time. Also, BES could be employed to provide a stable and reliable power from the output of PV sources to loads. It can enhance the performance of the entire power system during the grid-connected mode. The simulation results under Matlab/Simulink show that the suggested control strategies are robustness, fast transient response and proper steady-state performance in the grid-connected mode in comparison other presented methods.