机电产品动态分析与控制：第四讲 振动与噪声的调谐阻尼器控？…

本文介绍了调谐阻尼器的工作原理、结构基本形式、调谐阻尼器的优化设计方法和工程应用实例。     

半主动TMD控制双跨轴系过临界振动的研究

针对多轴串联机械通过临界转速时振动过大的问题,对调谐质量阻尼器在双跨轴系振动控制中的应用进行了研究。并基于转子结构,设计了具有对称结构的笼式半主动调谐质量阻尼器用于控制轴系振动;搭建了双跨转子实验台,在不改变转子轴系原有支撑形式上,在两根轴上分别安装了调谐质量阻尼器,对调谐质量阻尼器对轴系各跨转子振动的影响规律进行了实验研究。研究结果表明,不可控调谐质量阻尼器可以有效抑制安装所在轴临界转速附近的振动,对相邻轴影响较小,但会引起新共振峰。根据此实验结果通过开关控制策略实现调谐质量阻尼器半主动控制,说明半主动调谐质量阻尼器可以在不停机的情况下,抑制转子轴系通过各阶临界转速时的振动,避免失谐。     

半主动电流控制阻尼器的调谐减振性能研究

随着建筑高度不断增加,低频振动严重影响其安全运行。被动式阻尼器仅在调谐点处具有良好的减振效果,存在减振带宽较窄的问题,磁性液体为解决这个问题提供了新的途径。以磁性液体为工作液体,提出一种半主动调谐式电流控制阻尼器。首先,建立了阻尼器固有频率的理论模型,表明通过调节电流可改变固有频率。其次,搭建测试平台,进行了不同激励下阻尼器的调谐减振能力测试。结果表明半主动电流控制阻尼器的减振率为22%左右,调谐液体滚球阻尼器的减振率仅为12.3%左右,且调谐液体滚球阻尼器与主结构的频率比>1.11时,减振率将低于10%,半主动电流控制阻尼器则具有良好的鲁棒性,可以有效降低位移响应,弥补了被动式阻尼器减振带宽较窄的不足。     

五坐标龙门加工中心动特性分析与振动控制

通过对机床整机有限元模型的动力学分析。找出对整机动态性能影响最大的主振型，并以这些振型的模态参数进行抑制振动的调谐阻尼器的设计。通过分析可以看出，在原结构模型上安装该调谐阻尼器后。整机的动态性能得到了进一步的提高。     

利用调谐质量阻尼器进行管路系统减振

对既成管系存在的振动进行了减振研究。考虑到既成管线增加额外支撑的困难,设计了可拆分的环形调谐质量阻尼器结构,建立管系实验装置并进行模拟计算。分析了在有、无调谐质量阻尼器时实验管系振动在时域和频域的情况,并进行了实验验证。结果表明,设计的调谐质量阻尼器可大幅减缓管系的稳态振动和快速衰减管系的瞬态振动,是一种有效、实用的管系减振手段。     

精铣削中抑制柔性工件颤振的阻尼器设计

针对精铣削过程中柔性工件的颤振抑制问题,提出了一种利用空气黏性的新型被动质量阻尼器。首先,该质量阻尼器由一个可在薄壁壳体内自由移动的圆柱形重物组成,通过重物和壳体之间的适当间隙提供了密集的能量耗散;其次,给出了该阻尼器的理论模型,并提出了一种合理的宽带调谐策略,使该阻尼器能够在较宽的工作范围内通过固定调谐来提供足够的阻尼效率。通过冲击实验和铣削实验对该阻尼器进行了有效性验证。结果表明:该阻尼器的临界轴向切削深度显著增加约100倍;与同等质量颗粒阻尼器相比,该阻尼器的阻尼效率明显提升,过度切削量减少了14倍;与传统调谐质量阻尼器相比,该阻尼器的峰值效率更小,但工作范围更大,因此适用于细长柔性工件的铣削加工。     

一种控制梁振动用调谐阻尼器的优化方法

本文提出了一种连续梁等效计算方法,可使控制梁振动用调谐阻尼器的参数优化得到简化。应用此法优化设计的调谐阻尼器用来控制有梭织布机投梭棒的振动,取得了令人满意的降噪减振效果。     

两种宽频调谐质量阻尼器仿真及应用

提出了两种宽频调谐质量阻尼器(TurnedMassDamper-TMD),即梁式调谐质量阻尼器(Girder-ModelTunedMassDamper-GTMD)和环式调谐质量阻尼器(Ring-ModelTunedMassDamper-RTMD)。将GTMD安装到振动结构上,对比安装前后振动结构的位移响应,仿真实验表明GTMD能够在较宽的频率范围内有效地抑制结构的振动。随后将RTMD应用到桥式5轴联动加工中心的主轴系统上,仿真实验表明,RTMD有效地抑制了主轴系统加工部位的振动。     

尾流作用下风机振动的控制研究

上游风电机组的扰动效应使风机尾流处风场湍流强度增大,因此,下游风电机组的疲劳荷载显著增大。为了降低下游风电机组的风致响应,利用调谐质量阻尼器与旋转惯性双调谐质量阻尼器,开展尾流作用下的风机结构振动控制研究。采用致动线方法,实现了风机尾流风场仿真,风场数值仿真结果与实验值吻合;依据广义坐标理论,编制陆上风机结构风致响应分析程序,以实现读取任意风场数据并考虑旋转叶片与塔体耦合时变结构的风机整机风致动力响应分析,自编程序计算结果与商业程序基本吻合;采用调谐质量阻尼器与旋转惯性双调谐质量阻尼器对下游风电机组进行振动控制,降低风电机组风振响应,减小疲劳荷载。     

主被动调谐控制结构动力响应分析与试验

针对地震和风振下结构的振动控制,提出了结构主被动复合调谐控制的策略,以及采用直线电机驱动主动质量阻尼器(active mass damper,简称AMD)、中空橡胶隔震支座作为调谐质量阻尼器(tune mass damper,简称TMD)弹性单元、滑轨作为TMD支撑轨道的主被动复合调谐控制装置实现方法,进行了主被动复合调谐控制对结构动力响应控制的效果及减震机理分析,探讨了反馈响应向量对控制效果、AMD控制力和AMD位移的影响,完成了线性二次高斯算法(linear quadratic Gaussian,简称LQG)控制算法和H2/H∞控制算法时的主被动复合调谐控制结构振动台试验。研究结果表明:结构主被动复合调谐控制能有效减小结构的动力响应,改善TMD的性能;采用直线电机驱动的AMD作为主动控制装置,为防止AMD"飘移",AMD位移应作为目标向量和反馈响应;LQG控制算法总体控制效果优于H2/H∞控制算法。试验验证了提出的主被动复合调谐控制硬件系统方案的可行性,为工程应用提供了支撑。     

Fixed-point and stratified analysis of the fine structure and composition of five gallstones with Fourier transform infrared (FT-IR) specular reflection spectroscopy

By investigating the identities, amounts, and distributions of the major components of human gallstones, the formation mechanism of calculi may be elucidated. Using FT-IR specular reflection spectroscopy, the compositions of five common types of gallstones, including cholesterol calculus, bile pigment calculus, cholesterol-bilirubin calculus, mixed calculus, and black stones, were positionally, qualitatively, and quantitatively analyzed. Several organic and inorganic substances were found in human gallstones, including cholesterol, calcium bilirubinate, calcium carbonate, calcium phosphate, and calcium stearate. Among them, cholesterol and calcium bilirubinate were the main components. The amounts of these substances varied in different types of gallstone. The distributions of cholesterol and calcium salts (with the exception of calcium bilirubinate) were also closely associated with location. In the various calculi, the amounts of cholesterol and calcium bilirubinate in the cores, the layered structures outside the cores, and the outer shells were higher than those of other substances. The identities of the major components of calculi were similar in different types of gallstones, but their amounts and distributions were significantly different. The analytical method used in this study, which was able to accurately determine the location, quality, and quantity of the major components of gallstones, would be an effective tool to study the formation mechanism of calculi.     

ICP-MS顺次分析鸡蛋壳中微量元素

本研究基于顺次电离质谱分析技术,发展了一种直接质谱分析方法分析鸡蛋蛋壳中微量元素.在仅需少量样品预处理的条件下,分别用水和5％稀硝酸作为洗脱液,对鸡蛋壳中水溶性微量元素组分和酸溶性微量元素组分进行顺次提取,然后在线传输至ICP-MS进行分析.该方法可在10 min内实现单个样品中15种微量元素水溶性组分和酸溶性组分的顺...     

Histochemical and ultrahistochemical localization of heavy metals in calf organs

Cadmium, zinc, selenium, and copper were administered, singly or in combination, orally or subcutaneously. Experiment I included 32 calves of both sexes; six received Cd (two groups), Zn, Cd, and Zn, and Cd and Se (two groups) and one group was a control. In Experiment II (21 bulls), three were given Cd, Cd, and Cu, and Cd and Zn, respectively, and one group was a control. For light microscopy, in Experiment I the highest amounts of silver granules were present in the samples of liver, small intestine, and vesicular gland of all the exposed groups; in Experiment II the most affected organs were liver, kidney, and small intestine. For electron microscopy, in Experiment I, after administration of Cd and Zn, the highest amounts of granules were seen in the cytoplasm of hepatocytes and cells of the proximal and distal renal tubules and the lowest amounts were found in glandular cells of the pancreas. Administration of Cd and Se resulted in the presence of large numbers of granules in the nuclei and nucleoli of spermatogonies. In Experiment II, ingestion of Cd and Zn in feed led to the appearance of highest amounts of granules in the nucleoli, nuclei, and cytoplasm of cells in testes, kidneys, and pancreas. Following Cd intake, the highest accumulation of granules was observed in the nucleoli of hepatocytes and cells of the proximal and distal renal tubules. Combined Cd and Cu produced the highest number of granules in cells of the proximal and distal renal tubules and in the nucleoli and nuclei of germinal epithelium.     

Effects of polydatin on the proliferation,migration, and invasion of ovarian cancer

To investigate the effects of polydatin on the proliferation, migration, and invasion of ovarian cancer, the change of proliferative ability, migration ability, and invasive ability of human ovarian cancer cell OVCAR-3, A2780, and HO-8910 was detected by using polydatin and up-regulating PI3K. The anticancer activity and mechanism of polydatin in ovarian cancer were analyzed. Polydatin could effectively inhibit the proliferation, migration, and invasion of OVCAR-3, A2780, and HO-8910, and inhibit the expression of PI3K protein. After the expression level of PI3K protein was up-regulated, the inhibitory effect of polydatin on the proliferative ability, migration ability, and invasive ability of OVCAR-3, A2780, and HO-8910 significantly decreased, suggesting that PI3K was the target of polydatin. Therefore, we concluded that polydatin could inhibit the proliferation, migration, and invasion of ovarian cancer cells by inhibiting the expression of PI3K protein, which provides an experimental basis for polydatin in the treatment of ovarian cancer.     

Mice embryology: A microscopic overview

In this work, we studied the embryology of mice of 12, 14, and 18 days of gestation by gross observation, light microscopy, and scanning electron microscopy. Grossly, the embryos of 12 days were observed in C‐shaped region of the brain, eye pigmentation of the retina, first, second, and third pharyngeal arches gill pit nasal region on the fourth ventricle brain, cervical curvature, heart, liver, limb bud thoracic, spinal cord, tail, umbilical cord, and place of the mesonephric ridge. Microscopically, the liver, cardiovascular system and spinal cord were observed. In the embryo of 14 days, we observed structures that make up the liver and heart. At 18 days of gestation fetuses, it was noted the presence of eyes, mouth, and nose in the cephalic region, chest and pelvic region with the presence of well‐developed limbs, umbilical cord, and placenta. Scanning electron microscopy in 18 days of gestation fetuses evidenced head, eyes closed eyelids, nose, vibrissae, forelimb, heart, lung, kidney, liver, small bowel, diaphragm, and part of the spine. The results obtained in this work describe the internal and external morphology of mice, provided by an integration of techniques and review of the morphological knowledge of the embryonic development of this species, as this animal is of great importance to scientific studies. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

智能机床发展现状与技术体系框架

智能机床成为机床装备发展的趋势。在介绍国内外智能机床的研究现状的基础上,分析目前智能机床技术研究的三个问题,提出智能机床的狭义和广义定义;给出智能机床的包括人计机的协同性、整体与局部的协调性、智能的恰当性与无止性、自学习及其能力持续提高性、自治与集中的统一性、结构的开放性和可扩展性、制造和加工的绿色性、智能的贯穿性八个智能技术特征;阐述包括以人为中心的人计机动态交互功能、三个基本功能——执行智能功能、准备智能功能、维护智能功能的智能功能特征,以及功能之间的相互关系;建立八个理论与技术的智能机床技术理论框架,包括人计机一体化融合理论与技术、多源信息的感知理论与技术、智能决策理论与技术、智能执行理论与技术、智能维护理论与技术、智能机床综合能力评价理论与技术、智能机床标准化技术、智能机床支撑技术等,形成了智能机床的技术体系框架,同时指出上述内容将随着技术的进步和应用的深入不断充实和丰富。     

Distribution curves of sectional areas through some families of convex particles

We outline the results of a computer program which calculates frequency distributions of functions of cross-sectional regions of convex planar-faced polyhedra, ‘sphero-polyhedra’, and populations of perturbed polyhedra. This is done by ‘cutting’ a computer representation of the figure by a large number of random planes. The procedure is applied to cubes, dodecahedra, truncated octahedra, and approximate β-tetrakaidecahedra. Certain aspects of the shape of the object, e.g. sharpness of corners, angularity, compactness, and degree of symmetry are related to aspects of the shape of the distribution curves, e.g. beginning and ending points of the curves, rate of rise of the peak, relative location of the peak, and height and width of the peak.     

Discussion on advanced manufacturing

Advanced manufacturing consists of continuity of manufacturing, its broad sense, and the core of the manufacturing process. The technology of continuous manufacturing is discussed according to both historical and modern perspectives. The relationship between human development and manufacturing technology is also discussed. Manufacturing is a continuously evolving topic. It is not only the foundation and means of imagination, conception, the science, and the technology of material change, but also the expression of national economy, national defense, and the support industries. The broad sense of manufacturing theory, which extends the concept of manufacturing, is an important development in the 20th century. The sense is analyzed in connection with design, material forming theory, synthesis of manufacturing technology, manufacturing modes, life cycle of product, hardware and software, and support environment, etc. At the same time, the core action and the development of the theory and technology of process is also discussed. At the end of this paper, the development directions of mechanical manufacturing science and technology are mentioned.     

微波消解-电感耦合等离子体质谱法同时测定茶叶中42种元素

建立了电感耦合等离子体质谱法（IcP—Ms）标准模式和优化的碰撞池模式（CCT）结合同时测定茶叶中Li、Be、Mg、Al、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Ga、As、Se、Sr、Mo、Ag、Cd、Sn、Sb、Cs、Ba、Tl、Pb、Bi和16种稀土元素共42种元素的方法。样品经过微波消解,以Ge、In、Re为内标消除基体干扰,通过碰撞池技术消除多原子质谱干扰测定上述元素。对于所测元素校准曲线的相关系数均大于0．9990,回收率范围为90％-110％,相对标准偏差为0．22％-3．97％,大部分元素检出限均小于0．5μg·kg^-1。该方法简便、省时、准确、灵敏度高,适用于实际样品的检测。     

A review of studies on estimating the discharge coefficient of flow control structures based on the soft computing models

The discharge coefficient (Cd) plays a vital role in the accurate design and safety of weirs, spillways, and dams. In the last decade, Soft Computing(SC) models, which showed excellent capabilities for non-linear mapping between parameters, were widely used to estimate the discharge coefficient of flow control structures. This study provides a comprehensive review of the application of SC models for estimating Cd of different flow control structures such as ogee spillways, orifices, side weirs, etc. In addition, the most common empirical relations which are obtained from laboratory experiments are discussed briefly. The findings revealed that weir length/flow depth ratio, weir length/channel width ratio, weir height/flow depth, and Froude number are widely used to estimate Cd in the side weirs. Besides, the ratio of orifice crest height to height of side orifice, the ratio of main channel width to length of side orifice, ratio of main channel width to height of side orifice, and ratio of the height of side orifice to upstream flow depth were extensively employed to calculate Cd of orifice structures. The common parameters for measuring Cd of labyrinth weirs are, discharge over a labyrinth cycle, weir height, channel width, apex constant, upstream head, discharge over the weir, effective length, convergence constant, sidewall angle, and Froude number. In the weir-gate structure, some factors such as contraction coefficient of the gate, head loss, and weir height are key parameters for the accurate evaluation of Cd. The trends of SC models, features of popular models, and the background of models are discussed briefly in this paper. Also, research gaps and possible directions for new studies are suggested.