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排序方式: 共有443条查询结果,搜索用时 62 毫秒
41.
应用微机数模转换接口控制小直流电机的转速   总被引:2,自引:2,他引:0  
洪小叶 《物理实验》2003,23(4):20-22,25
介绍了采用微机数模转换器接口技术实现对小直流电机转速控制的实验方案,并对实验结果进行了讨论.  相似文献   
42.
A disadvantage of using a galvanometer as the horizontal scanner in CSOM and OCT is its nonlinear distortion caused by the rotational inertial. This is inevitable even if a closed loop is equipped. Here, a second closed loop is introduced to provide pixel clocks to reduce the pincushion distortion of the images. A subdivided step motor is employed to be the vertical scanner as the result of price consideration. Nonetheless, the conventional linearity model of the peck torque with a winding current relationship is no longer in agreement with the experiment when the winding current is low, while a parabolic model is more likely to be reasonable. Relational treatment is proposed in the paper. Both methods have proved to be good enough to meet the requirement of a super resolution scanning imaging.  相似文献   
43.
本文从纵扭振动换能器理论出发,计算了一种新的复合换能器型超声马达,并进行了实验研究,测出了其主要性能参数。  相似文献   
44.
通过平面电机绘图机系统的设计,描述了机、电、微机控制技术一体化的优越性。一个重要的优点是机械、电气技术的结合将会大大地简化平面电机绘图系统的结构和制造工艺,因而降低了成本。另一个重要优点是微机控制技术将会大大地扩大机电产品的功能。最后结论:机、电、微机控制技术一体化是机电产品今后的发展趋势。  相似文献   
45.
直线电机磁性材料的选择对斯特林制冷机的性能具有重要影响。应用电机电磁场理论和有限元分析方法,建立动磁式直线电机的电磁场模型,基于Ansoft Maxwell软件对几种常用磁性材料的电磁场进行有限元分析,得到了相应的电磁推力和磁感应强度分布。经过分析比较,选择铷铁硼、铁钴钒和硅钢作为电机磁性材料,研制的斯特林制冷机应用于5L深冷冰箱,获得了-150℃的低温环境,对应温度的制冷量为7W。  相似文献   
46.
Chunhua Zeng  Ailing Gong  Yafang Tian 《Physica A》2010,389(10):1971-1977
Transport of an inertial Brownian motor moving in an asymmetric periodic potential driven by an external force and correlated noises is investigated. Using the numerical algorithm, the asymptotic mean velocity (AMV) for characterizing directed transport is obtained. The effects of the external driving force f and the correlation λ between the two noises on the AMV are discussed. The results manifest: (1) the external driving force and the correlation between the two noises can lead to the phenomena like current reversal. (2) The competitions among the external driving force and the correlation between the two noises are necessary for current reversal, i.e., fλ>0. (3) Different directions of transport are found for different masses of the Brownian particles under the condition fλ>0. Therefore a theoretical study is suggested for separating Brownian particles according to their different masses in the ratchet system.  相似文献   
47.
离散式任意充磁角度Halbach永磁电机解析模型研究   总被引:1,自引:0,他引:1       下载免费PDF全文
梁京辉  张晓锋  乔鸣忠  夏益辉  李耕  陈俊全 《物理学报》2013,62(15):150501-150501
Halbach电机因其自身优势在新型船舶推进、海洋洋流发电等方面受到广泛关注. 本文在假设铁磁材料线性和定子内表面光滑的条件下, 通过将任意充磁角度Halbach阵列等效为两组90° Halbach(或180° Halbach)阵列的矢量合成, 提出了一种分析离散式任意充磁角度Halbach永磁电机气隙磁场的解析方法; 通过对电机中磁标量势的傅里叶级数进行计算, 推导出了最简单的90° Halbach永磁电机在极坐标系下的气隙磁密表达式, 并在此基础上, 给出了任意充磁角度Halbach电机永磁体磁化强度在一个极下的表达式, 进而得出任意充磁角度Halbach电机气隙磁密的分布, 并分析了气隙磁密与电机极对数、永磁体厚度和充磁角度间的关系. 最后通过有限元和试验结果验证了本文方法的正确性. 关键词: 离散式Halbach电机 任意充磁角度 矢量等效 解析模型  相似文献   
48.
Cerebellar long-term depression (LTD) is a type of synaptic plasticity and has been considered as a critical cellular mechanism for motor learning. LTD occurs at excitatory synapses between parallel fibers and a Purkinje cell in the cerebellar cortex, and is expressed as reduced responsiveness to transmitter glutamate. Molecular induction mechanism of LTD has been intensively studied using culture and slice preparations, which has revealed critical roles of Ca2+, protein kinase C and endocytosis of AMPA-type glutamate receptors. Involvement of a large number of additional molecules has also been demonstrated, and their interactions relevant to LTD mechanisms have been studied. In vivo experiments including those on mutant mice, have reported good correlation of LTD and motor learning. However, motor learning could occur with impaired LTD. A possibility that cerebellar synaptic plasticity other than LTD compensates for the defective LTD has been proposed.  相似文献   
49.
A procedure is proposed to obtain the linearization of a class of non-linear physical systems using bond graphs. Also, a junction structure of a non-linear bond graph considering linearly dependent and independent state variables is described. From the junction structure of the non-linear bond graph a procedure to build a linearized bond graph is presented. Finally, an example of a Programmable Universal Manipulation Arm (PUMA) manipulator is given.  相似文献   
50.
A molecular motor is made of either a single macromolecule or a macromolecular complex. Just like their macroscopic counterparts, molecular motors “transduce” input energy into mechanical work. All the nano-motors considered here operate under isothermal conditions far from equilibrium. Moreover, one of the possible mechanisms of energy transduction, called Brownian ratchet, does not even have any macroscopic counterpart. But, molecular motor is not synonymous with Brownian ratchet; a large number of molecular motors execute a noisy power stroke, rather than operating as Brownian ratchet. We review not only the structural design and stochastic kinetics of individual single motors, but also their coordination, cooperation and competition as well as the assembly of multi-module motors in various intracellular kinetic processes. Although all the motors considered here execute mechanical movements, efficiency and power output are not necessarily good measures of performance of some motors. Among the intracellular nano-motors, we consider the porters, sliders and rowers, pistons and hooks, exporters, importers, packers and movers as well as those that also synthesize, manipulate and degrade “macromolecules of life”. We review mostly the quantitative models for the kinetics of these motors. We also describe several of those motor-driven intracellular stochastic processes for which quantitative models are yet to be developed. In part I, we discuss mainly the methodology and the generic models of various important classes of molecular motors. In part II, we review many specific examples emphasizing the unity of the basic mechanisms as well as diversity of operations arising from the differences in their detailed structure and kinetics. Multi-disciplinary research is presented here from the perspective of physicists.  相似文献   
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