基于无传感器的PMSM电流控制策略的研究

提出一种新型的滑模观测器,并分别研究在4种不同的电流控制策略下,基于该新型滑模观测器的PMSM伺服系统的控制问题。该新型滑模观测器引进了Sigmoid函数作为控制函数用来抑制抖振,并根据PMSM的反电动势模型构建了反电势观测器来提取所需的连续信号,因此取消了传统的一阶低通滤波器和相角补偿环节。为了对电机的转子位置和转速进行更加精确的估算,引入了转子位置锁相环结构。在Matlab/Simulink平台基础上建立了4种不同的电流控制策略,基于新型滑模观测器PMSM无位置传感器三闭环控制系统仿真模型,分别对反电动势估算、速度估算、位置估算和突加负载扰动进行了仿真分析。仿真结果表明,该新型滑模观测器在4种不同的电流控制策略下,对电机转子位置和转速的估算、电磁转矩以及定子三相电流有着不同的影响,验证了该新型滑模观测器算法的可行性。     

一种基于DNA计算的指定结点路由算法

带指定结点约束的路由问题是一个NP难问题,该问题是电信行业路山智能化和交通电力运输等领域的关键问题之一.基于DNA计算的高度并行性,文中提出一种将电子计算机与DNA计算机相结合的方法求解指定结点路由问题.算法由转化算法Transform()、首末结点搜索切割算法FirstEndSearcher()、转化图结果搜索算法DNASearcher()和结果读取算法ResultReader()共4个子算法组成.分析表明:算法的电子计算机部分缩小了问题结点和边的规模,从而使解决问题所需的DNA分子链数数量级从O((n-2)!)减少至O((m-2)!)(n≥2为图中结点数,m≥2为图中指定必经结点数).算法的DNA计算机部分采用了有针对性的DNA编码新方案,提高了边权值编码的信噪比,通过一系列生物操作,筛选出问题的精确解.和单纯DNA超级计算或电子计算机指定结点路由算法相比,文中算法可显著扩大理论上待求解问题的规模.     

Effect of superfine grinding on properties of <Emphasis Type="Italic">Vaccinium bracteatum</Emphasis> Thunb leaves powder

Vaccinium bracteatum Thunb, have been widely used in various traditional medicines and food products. The narrow and uniform particle size distribution in V. bracteatum Thunb leaves (VBTL) can be achieved through a new emerging type of foodstuff processing and superfine grinding. The VBTL powders were subjected to four particle sizes as followed: 300–125, 125–75, 75–40, and <40 μm. The VBTL powders were observed to be with smaller size and bulk density, greater surface area, tapped density and the angle of repose. Water solubility index, water holding capacity and total flavonoid extraction increased slightly with the decrease in particle size. Differential scanning calorimetry showed that the VBTL exhibiting particle size of <40 μm had the lowest peak temperature; whereas, powder with a particle size of 125–300 μm displayed the largest endothermic enthalpy. Our results of the properties of VBTL superfine powder supplied the basis for VBTL in potential industrial applications of foods.     

Crystal structure and microwave dielectric properties of temperature stable (CoxZn1–x)TiNb2O8 ceramics

(Co_xZn_1–x)TiNb₂O₈ (x = 0.2–0.8) microwave dielectric ceramics were synthesized via the conventional solid-state reaction route, and the correlation of microwave dielectric properties on the crystal structure was discussed. Crystal structures of ceramic samples were systematically investigated by X-ray powder diffraction. Moreover, composition-induced phase transitions were confirmed via the following sequence: for x ≤ 0.2, single-phase orthorhombic ixiolite (ZnTiNb₂O₈) was formed, whereas for 0.3 ≤ x<0.8, ixiolite and rutile coexisted. When x ≥ 0.8, only single-phase rutile was detected. For the (Co_xZn_1–x)TiNb₂O₈ ceramics, the microwave dielectric properties were changed with the crystal structural transitions: the dielectric constant (ε_r) and the temperature coefficient of resonant frequency (τ_f) increased upon increasing the Co²⁺, but the quality factor (Q) decreased. A near-zero τ_f = +1.6 ppm/°C was obtained in the Co_0.38Zn_0.62TiNb₂O₈ ceramics with ε_r = 40.7 and high Q × f = 16 790 GHz. These research outcomes are expected to have great significance for developing microwave dielectric ceramics in practical applications.     

电感耦合等离子发射光谱测定乳扇中的铝含量

目的 建立电感耦合等离子发射光谱法测定乳扇中铝含量的分析方法。调查市售样品中铝的含量是否异常。方法 采用湿式消解法处理乳扇样品, 电感耦合等离子发射光谱测定样品中铝的含量, 同时进行精密度实验和加标回收实验。测定市场收集的乳扇样品中铝的含量, 并与严格按云南省地方标准(DBS 53/010-2016)制作的乳扇样品进行比较。结果 铝在0~10 mg/L范围内线性关系良好, 相关系数r达0.999928, 方法的检出限为0.5 mg/kg, 定量限为1.5 mg/kg, 精密度为2.5%~3.1%, 加标回收率在96.6%~105.0%之间。按地方标准制作的乳扇样品中铝含量较低, 在3.2~5.3 mg/kg之间, 部分市场收集的样品中铝含量偏高。结论 本方法操作简便、结果准确, 可作为乳扇中铝含量检测的方法。乳扇应严格按照地方标准制作。     

Design and realization of a non-actuated glass-curtain wall-cleaning robot prototype with dual suction cups

This paper describes a non-actuated glass-curtain wall-cleaning robot prototype that has been designed and realized based on some wall-climbing robots developed recently and common traits of glass-curtain walls of high-rise buildings. The robot hasn’t its own driving mechanism, but it can move on smooth glass surfaces depending on its own gravity and the lifting force of the trolley crane on the roof while adhering to the surfaces using dual vacuum suction cups. Obstacles, such as horizontal window frames, can be crossed while cleaning. The safety analysis ensures that the robot can work reliably. The analysis on characteristics of suction cups using fluidic network theory is to enhance the adhering capacity of the robot. The control system utilizes two-level computer control strategy to achieve the robot’s moving, cleaning and crossing obstacles. Experiments proved the robotic system is feasible and practical.     

城市河流生态修复的环境价值及实现机制

探讨了城市河流环境价值的内涵、分类体系及常用度量方法,并以上海市长宁区的河流生态修复为案例,测算其环境价值,分析其投入产出。据此分析我国城市河流生态修复资金短缺的原因,探讨城市河流生态修复的环境价值实现机制。计算结果表明:(1)生态修复后的城市河流环境价值增值显著,本案例总计约为4.7亿元/年,相当于2007年长宁区GDP的1.22%,年均产出投入比为14.63;(2)城市河流生态修复的正外部经济效应显著,河流沿线居民和企业是最大的受益者;(3)政府进行河流两岸统一开发、水资源定价、税费征收与转移支付是城市河流生态修复环境价值的主要实现途径;(4)营造全社会参与河流保护氛围,并使公众理解城市河流环境价值,是价值实现的关键步骤。     

板栗及其加工副产物的活性物质研究进展

板栗是我国重要的经济作物,投产面积覆盖广,在加工过程中易产生诸如板栗壳总苞、板栗壳、板栗花、板栗次果等副产物,大量资源常被当作废弃物丢弃,未得到有效利用,造成资源浪费甚至环境污染。板栗加工业存在科技含量低、抗风险能力差、经济实力不足等问题,板栗加工副产物开发问题得到关注。因此,本文从多酚、单宁、黄酮、多糖、原花青素及淀粉分别论述了板栗及其加工副产物的提取方法、结构特点和活性作用及其机制,对板栗加工副产物开发前景进行展望,为探索其新的开发途径提供方向,以期完善板栗加工产业链。     

马兰头黄酮粗提物对油脂的抗氧化活性研究

目的 分析马兰头黄酮粗提物对油脂的抗氧化性能及体外自由基清除能力。方法 以酸价、过氧化值为指标, 分析2,6二叔丁基对甲酚(butylated hydroxytoluene, BHT)、马兰头黄酮粗提物对花生油、大豆油、猪油的抗酸败氧化性能; 以抗坏血酸为对照, 分析马兰头黄酮粗提物对2,2’-联氮-双-3-乙基苯并噻唑-6-硫酸二铵盐[2,2''-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), ABTS+]自由基的清除能力。结果 马兰头黄酮粗提物可以有效抑制油脂酸价的升高, 可分别将猪油、大豆油的过氧化值超标耐受天数从3、4 d延长至4、5 d, 与BHT作用效果差异不显著(P>0.05), 它对花生油过氧化值的升高抑制作用无实际应用意义; 马兰头黄酮粗提物水溶液对ABTS+自由基清除率最高可达到104.0%±0.9%。结论 马兰头黄酮粗提物具有较好的抑制油脂氧化的作用和很好的自由基清除能力, 具有较好的天然油脂抗氧化剂开发前景。     

碰撞池-电感耦合等离子体质谱法同时测定水果中26种微量元素的含量

目的建立碰撞池-电感耦合等离子体质谱法(collision cell technology--inductively coupled plasma massspectrometry,CCT-ICP-MS)同时测定水果中26种微量元素的含量,了解主要水果中微量元素本底值。方法采用微波消解处理样品,选择合适同位素、内标元素和碰撞池技术(collision cell technology,CCT)消除被测元素的干扰,利用苹果标准物质(GBW10019)进行能力验证,确定方法的准确性。结果方法检出限0.01~4.0μg/kg,相对标准偏差1.7%~8.2%(n=7),标准曲线相关系数均大于0.9998,标准物质测定值与指定值相符,能力验证结果满意。结论该方法具有简便、准确、灵敏等特点,满足水果中微量元素同时测定,可以用来进行水果的质量监控和安全评价。