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71.
空间有源消声的微机控制   总被引:1,自引:0,他引:1       下载免费PDF全文
本文讨论用通用微机控制空间有源消声.以修正的PID(比例、积分、微分)算法加上逻辑判断构成的控制软件,使得系统收敛迅速,跟踪速度快,消声效果令人满意,而且系统工作稳定可靠,  相似文献   
72.
自动线性跟踪Butterworth有源滤波器研究   总被引:2,自引:0,他引:2  
滤波是通信、测试、数据采集和实时控制等领域至关重要的环节。通常的模拟滤波器,由于截止频率固定,在某些宽频率动态范围且有实时性要求的应用场合,往往达不到预期的滤波效果,有时甚至影响整个系统的正常运行。本文从有源滤波器的机理分析入手,提出了一种由单片机参与的滤波系统,它能自动跟踪输入信号频率,线性地选择合适的滤波器截止频率,弥补了原有滤波器的不足。  相似文献   
73.
随机化交通灯的二维元胞自动机交通模型   总被引:8,自引:0,他引:8  
元胞自动机交通模型以简单的规则反映交通系统中的多种因素,可以分析各种交通现象,且可在计算机上方便、高效地运作·Biham-Middleton-Levine模型(BML模型)实现了二维交通问题的元胞自动机模型的模拟研究·本文对BML模型作了改进,解除了该模型中关于交通灯同步变化的限制·在新模型中,每个路口的交通灯可以自由选定起始工作时间和变化节奏,于是可以更全面、准确地反映交通灯对交通系统性能的影响·本文还对新模型中出现的若干新效应作了解释·  相似文献   
74.
Summary A novel approach to solid phase extraction, based on the use of a highly selective molecularly imprinted polymer, is presented. The versatility of this type of sorbent for solid phase extraction was demonstrated in a model batch-wise pre-concentration of sameridine prior to gas chromatography. Problems associated with leakage of remaining imprint molecules during the desorption phase could be eliminated by the use of a close structural analogue of sameridine as the imprint species. It was found that a major benefit of the imprinted polymer was its specificity, which lead to distinctly cleaner chromatographic traces and ability to improve sensitivity by extracting sameridine from larger sample volumes.  相似文献   
75.
Ahn  In-Ae  Woong Kim  Sang  Ro  Seonggu 《Molecular diversity》1998,4(1):23-24
Peptides containing azaglycine located terminally or within the backbone have been prepared in the solid phase by means of an automatic synthesizer.  相似文献   
76.
一种铁氧体移相驱动器专用集成电路   总被引:1,自引:1,他引:0  
介绍了SA018铁氧体移相驱动器专用集成电路的工作原理,电路设计和实验结果。该电路的内部电路设计有双路激励驱动器,放大器,积分器和双路高速比较器等功能单元。将铁氧体移相器的激励驱动器和相位控制器融于一体,大大减少了铁氧体移相器的外围设计。  相似文献   
77.
Unique crystallization and melting behavior in poly(aryl ether ketone ketone) containing alternated terephthalic and isophthalic moieties were studied by time-resolved synchrotron x-ray methods. Recently, this material has been shown to exhibit three polymorphs (forms I, II, and III). In this work, we further investigated their distinctive thermal properties and found that form I is the dominating and the most thermally stable phase while form II is favored by fast nucleation conditions and is the least stable phase. On the other hand, form III represents a minor intermediate phase that usually coexists with form I and can be transferred from form II and to form I. Structural and morphological changes in form I have been followed by simultaneous wide-angle x-ray diffraction (WAXD)/small-angle x-ray scattering (SAXS) measurements during cold- or melt-crystallization and subsequent melting. In all cases, a larger dimensional change was found in the crystallographic a-axis than the b-axis during heating and cooling. This may be due to the greater lateral stress variation with respect to temperature along the a direction of the primary lamellae which is induced by either the formation of secondary lamellae or the preferential chain-folding direction in poly(aryl ether ketone ketone)s. During the phase transitions of form II ← III in the cold-crystallized specimen and form III ← I in the melt-crystallized samples, lamellar variables (long period, lamellar thickness, and invariant) obtained from SAXS remain almost constant. This indicates that the density distribution in the long spacing is independent of the melting in form II or III. For melt-crystallization, the corresponding changes in unit-cell dimensions and lamellar morphology during the annealing-induced low endotherm are most consistent with the argument that these changes are due to the melting of thin lamellar population. © 1995 John Wiley & Sons, Inc.  相似文献   
78.
Chemiluminescence (CL) was found upon the isomerization of dimethyldioxirane in the gas phase under argon atmosphere. The intensity of CL increases as temperature increases and decreases with time at constant temperature. If Silipor is placed in a cell containing the dimethyldioxirane vapor in argon, the intensity of CL sharply increases (more than 10 times) and then decreases following the exponential law. In all cases tripletly excited methyl acetate is the emitter of chemiluminescence.[/ p]Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2582–2583, October 1996.  相似文献   
79.
A method employing a wide pore polymeric reversed phase column has been developed for the separation of most of the chlorophylls and related compounds previously described as occurring in marine microalgae. The high selectivity toward molecular shape of this kind of stationary phase has enabled compounds of very similar structure, such as chlorophylls c1, c2 and Mg-divinylpheoporphyrin a5 monomethyl ester, and chlorophyll a and the phytol-substituted chlorophyll c-like pigments, which commonly coelute on monomeric bonded phases, to be resolved in a single run. Some of these pigments, formerly thought to be a single compound, have, in fact, been demonstrated to be groups of two or more. The method has been successfully applied to both algal cultures and natural sea water samples. When visible light absorbance detection was used, the method proved suitable for separation of various carotenoids.  相似文献   
80.
激光相位成像雷达的研究   总被引:1,自引:0,他引:1  
贺安之  罗必凯 《光学学报》1993,13(7):67-669
利用无合作目标漫反射激光相位测距的原理,对关键单元技术进行分析和设计,研制成一种用于自主式车辆视觉导引的激光相位成像雷达的原理样机.  相似文献   
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