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71.
At millimeter wavelengths uncontrollable parasitics are of ten large enough to significantly degrade circuit performance when they are not compensated by adjustable elements. It is difficult to add adjustable elements to planar millimeter-wave circuits without increasing their size, weight, and cost. In this paper we investigate three adjustable elements, all involving movement of a short along a section of coplanar waveguide (CPW). These tuners are incorporated in a planar detector circuit for purposes of demonstration and characterization. Their losses are determined. The precision with which they can be adjusted is also considered. Of the three, a tuner based on the laser-assisted etching of molybdenum is shown to have the highest performance at millimeter wavelengths. This tuner employs laser direct write etching1 with a recently developed photochemical reaction for trimming molybdenum.University of California, Berkeley Berkeley, California 94720M.I.T. Lincoln Laboratory 244 Wood St. Lexington, Massachusetts 0217  相似文献   
72.
Results of an experimental study and a calculation of the quasi-optical multilayered structure formed by an adjustable dielectric interferometer and a liquid investigated filling its gabs are presented. It is shown that this structure may be used for quality tests of liquid petroleum products, for measurement and investigation of physical parameters of liquid media in the millimeter wavelengths region. This structure is realized practically in the form of uncomplicated adjustable quazi-optical quvette filled with liquid and connected with beam-guiding elements. Comparison of experimental data with theoretical calculations gives us the opportunity to choose a value region of the values for the physical parameters interesting for us for each material under investigation.  相似文献   
73.
Adjustable robust solutions of uncertain linear programs   总被引:9,自引:0,他引:9  
We consider linear programs with uncertain parameters, lying in some prescribed uncertainty set, where part of the variables must be determined before the realization of the uncertain parameters (``non-adjustable variables'), while the other part are variables that can be chosen after the realization (``adjustable variables'). We extend the Robust Optimization methodology ([1, 3-6, 9, 13, 14]) to this situation by introducing the Adjustable Robust Counterpart (ARC) associated with an LP of the above structure. Often the ARC is significantly less conservative than the usual Robust Counterpart (RC), however, in most cases the ARC is computationally intractable (NP-hard). This difficulty is addressed by restricting the adjustable variables to be affine functions of the uncertain data. The ensuing Affinely Adjustable Robust Counterpart (AARC) problem is then shown to be, in certain important cases, equivalent to a tractable optimization problem (typically an LP or a Semidefinite problem), and in other cases, having a tight approximation which is tractable. The AARC approach is illustrated by applying it to a multi-stage inventory management problem.Research was partially supported by the Israeli Ministry of Science grant #0200-1-98, the Israel Science Foundation founded by The Israel Academy of Sciences and Humanities, grant #683/99-10.0, and the Fund for Promotion of Research at the Technion.  相似文献   
74.
无约束非线性l_p问题的调节熵方法   总被引:1,自引:0,他引:1  
本文构造了求解无约束非线性lp问题的新方法——调节熵函数法。给出了数值算法,证明了算法的收敛性。通过数值仿真将该方法与求解无约束非线性lp问题的极大熵函数法进行了比较,表明该算法是十分有效的。  相似文献   
75.
研制了一台磁场可调微波离子源, 在离子源放电室处需要的磁场由一组永久磁铁产生, 永久磁铁外部安装了铁磁回路, 铁磁回路的结构可以很容易的手动调整, 通过调整铁磁回路的结构, 可以在放电室产生要求的磁场. 在调试过程中, 也可以调整铁磁回路以改变离子源内部磁场结构, 有利于获得最佳放电条件. 该源在测试中, 从3mm直径的引出孔引出了17mA的离子束.  相似文献   
76.
A zinc(Ⅱ) coordination polymer [Zn2(2-mBIM)2(SUC)2]n (1, 2-mBIM = bis(2-methylimidazo-1-yl) methane, SUC = succinate anion) has been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in the triclinic space group P1 with a = 9.4871(8), b = 12.9789(5), c = 14.0230(5), α = 90.474(1), β = 90.3560(10), γ = 109.691(1)°, V = 1529.94(15)3 , Z = 2, Dc = 1.553 mg/m3 , μ = 1.63 mm-1 , F(000) = 736, the final R = 0.0645 and wR = 0.0951 for 4067 observed reflections with I > 2σ(I). Each Zn atom was coordinated by two individual 2-mBIM ligands in a cis-conformation and two monodentate coordinated succinate anions in a gauche conformation, resulting in the formation of a two-dimensional supramolecular network containing a cationic 16-membered macrometallacycle and a 28-membered macrometallacycle. The result also indicates that the conformation of the ligands has a strong influence on the structure of the supramolecular network.  相似文献   
77.
本文根据半导体理论,分析差分放大器的特点;讨论双平衡模拟乘法器的产生和工作原理.列举几个典型电路的实际应用,写出这些电路工作过程的数学模型.  相似文献   
78.
自然数八度周期律暨丢番图四定理   总被引:1,自引:0,他引:1  
在发现自然数八度周期律的基础上,明确而系统地制定了丢番图四定理,从而准确、彻底、全面地解决了数论中任意正整数究竟能分解成几个平方数之和的这一古老问题.  相似文献   
79.
在发现自然数八度周期律的基础上,明确而系统地制定了丢番图四定理,从而准确、彻底、全面地解决了数论中任意正整数究竟能够分解成几个平方数之和的这一古老问题。  相似文献   
80.
分析了集成峰值鉴频器的工作原理,得出鉴频中周失谐的原因是内置的配谐瓷管电容容量的衰减。衰减机理是该电容内外表面的银涂覆层受空气中硫化氢的侵蚀,局部或大面积生成硫化银而变黑,电极的有效面积减小,导致电容量减小。改进配谐瓷管电容生产工艺,在内外层圆柱型银的表面加保护层可有效防止中周失谐。  相似文献   
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