Photometric Invariants Related to Solid Shape

An attempt is made to identify the structural invariants of the field of isophotes on lambertian surfaces of arbitrary shape under arbitrary illumination. It is a priori clear that such invariants play an important part in the perception of solid shape by means of chiaroscuro. We have found several such invariants. The topological structure of the field of isophotes is determined by the collection of nested, closed parabolic curves on the surface. An important class of stationary points of the field clings to these parabolic lines. The isophotes cut the parabolic lines at a constant angle, irrespective of the location of the light sources. For certain canonical surface undulations the field of isophotes is explicitly given.     

矢量概率统计方法及转子不平衡矢量合成

统计学的研究对象为标量,但在转子动力学研究中有时需要对具有分布概率的矢量进行统计,利用现有的统计学方法无法解决此类问题.本文从统计学基本原理出发建立了一套解决具有任意相角矢量的概率统计合成方法,并成功应用于双层筒转子内外简的不平衡矢量合成计算.对判断转子是否符合加工要求提供了新的依据.     

得分向量偏序集上Schur函数和奇异得分向量

所有ｎ维得分向量集合Ｌｎ在优超关系下是一个偏序集。Ｌ上的实函数ｇ（ｓ）称为（严格）Ｓｃｈｕｒ凸的，若对任意ｓ，ｓ′∈Ｌｎ，ｓ≠ｓ′，ｓ优超ｓ，恒有ｇ（ｓ）≥（〉）ｇ（ｓ）。本文证明了ｆ（ｘ）＝ｓ＾Ｔｓ和得分向量为ｓ的竞赛图Ｔｎ中３－圈个数ｃ３（ｓ）在Ｌｎ上分别是严格Ｓｃｈｕｒ凸和严格Ｓｃｈｕｒ凹的，称ｎ维得分向量ｓ为奇异的，若得分向量为ｓ的每个ｎ阶竞赛图Ｔｎ的邻接矩阵都是奇异的。最后，应用Ｌ上严格     

Polymorphism of the Ag8S4O4 and Ag6S3O4 compounds

Experimental results of the reaction occurring between aqueous solutions of AgNO₃ and Na₂S₂O₃ were presented in this work. It has been demonstrated that these reagents form two phases to which the summary formulas: -Ag₈S₄O₄ and -Ag₆S₃O₄ were ascribed. The -Ag₈S₄O₄ phase crystallizes in a tetragonal system and has the following parameters of the unit cell: a = b = 0.72052 nm, c = 0.51140 nm, V = 0.26550 nm³, Z = 1, d_x = 6.60 g/cm³. At 223°C -Ag₈S₄O₄ undergoes an irreversible, endothermic polymorphic transition. The heat of this transition amounts 8.03 × 10^–3 J/mol. A high-temperature polymorphic form -Ag₈S₄O₄ melts at 400°C. The -Ag₆S₃O₄ phase crystallizes in a monoclinic system and has the following parameters of the unit cell:a = 2.09616 nm, b = 0.53118 nm, c = 1.49885 nm, = 102.78°, V = 1.62753 nm³, Z = 8, d_x = 6.59 g/cm³. -Ag₆S₃O₄ also undergoes an irreversible, endothermic polymorphic transition at 221°C. The heat of this transition amounts 7.65 × 10^–3 J/mol. A high-temperature form, -Ag₆S₃O₄, melts at 390°C.     

Invariants of polarization transformations

The use of polarization-sensitive sensors is being explored in a variety of applications. Polarization diversity has been shown to improve the performance of the automatic target detection and recognition in a significant way. However, it also brings out the problems associated with processing and storing more data and the problem of polarization distortion during transmission. We present a technique for extracting attributes that are invariant under polarization transformations. The polarimetric signatures are represented in terms of the components of the Stokes vectors. Invariant algebra is then used to extract a set of signature-related attributes that are invariant under linear transformation of the Stokes vectors. Experimental results using polarimetric infrared signatures of a number of manmade and natural objects undergoing systematic linear transformations support the invariancy of these attributes.     

The elastic behaviour of Ce3S4 and La3S4

The hydrostatic pressure and temperature dependences of the elastic stiffnesses of the cubic, Th₃P₄ structure compounds Ce₃S₄ and La₃S₄ have been measured using the ultrasonic pulse echo overlap technique. Although Ce₃S₄, unlike La₃S₄ (T _c = 103 K), does not undergo a phase transition when its temperature is lowered to 16 K, its elastic stiffnesses (C₁₁-C₁₂)/2 and C₁₁ soften with decreasing temperature (in a similar manner but less markedly than those of La₃S₄); this lattice instability indicates an incipient phase transition. In both compounds the elastic constants increase under pressure: the long-wavelength acoustic-mode Grüneisen parameters are all positive, and the application of pressure does not induce acoustic phonon-mode softening.     

MPEG-4形状编码的系统设计及实现

MPEG-4中的形状编码是用于支持其基于对象操作最大特性的最为关键的技术。本文提出了一种快速合理的能够满足MPEG-4实时处理的系统结构并可以在23．5NHz的速度下实现MPEG-4CPL2的实时视频编码。     

Invariants in metrology and technical diagnostics

The interrelationship between metrology and technical diagnostics is analyzed. Parallels are noted in the ideas, concepts, and metrological and diagnostic procedures, including aims, objects, models, parameters, methods, apparatus, processing, and estimation of results. It is found to be promising to utilize the theory of invariants in metrology and technical diagnostics. Different types of invariant are given for linear dynamic systems. Translated from Izmeritel'naya Tekhnika, No. 6, pp. 3–14, June, 1996.     

不可能Hitting集的剔除与可能Hitting集的概率排序

在基于模型的故障诊断中，并非由候选产生出的所有ｈｉｔｉｎｇ集都是真实的故障解，同时，各可能ｈｉｔｉｎｇ集的发生概率也不尽相同。为此，本文提出了一种对不可能ｈｉｔｉｎｇ集进行剔除及对可能ｈｉｔｉｎｇ集进行概率排序的诊断方法。     

Synthesis and Luminescent Properties of Eu-Activated CaGa2S4 and SrGa2S4

SrS, CaS, SrGa₂S₄:Eu, and CaGa₂S₄:Eu were prepared, and the luminescent properties of the latter two compounds were studied. It is shown that sufficiently pure SrS and CaS powders can be prepared via long-term sulfurization. SrGa₂S₄:Eu and CaGa₂S₄:Eu offer bright green photo-, roentgeno-, and electroluminescence and compare well with commercial analogues.     

Sets and Uncertainty

Arguments are presented indicating coincidence between the concepts of uncertainty and precision, and also on the undesirability of using the uncertainty propagation law for estimating dispersion. It is possible to estimate the reproducibility without performing an interlaboratory experiment and ways are characterized for estimating the closeness between the actual (or true) value of a measured quantity to the measurement result in the presence of influencing factors.We continue the selection of papers from the seminar “Mathematical methods in providing quality and mutual acceptance in measurement results,” with the start of the selection found in Nos. 4 and 5 for 2005.__________Translated from Izmeritel’naya Tekhnika, No. 6, pp. 20–25, June, 2005.     

Shape analysis of pulsed second sound in crystalline4He

We have observed that second-sound pulses in crystalline⁴He contain features corresponding to the input pulse power densityp(t) as well as to its time derivative, (t). By curve-fitting to an analytical expression for the entire response, values of the second-sound velocity and of the normal-process relaxation time _N have been obtained. The results for _N are in fair agreement with previous determinations. However, our values for the velocity lie systematically lower in a manner that can be qualitatively explained if the driving terms of the second-sound wave equation are properly taken into account. A new feature in our data is the emergence at low temperatures of a driving term with the time dependence ofp(t).Supported by the National Science Foundation.     

Structures des composes CdTm2S4 et CdYb2S4

The structures of CdTm₂S₄ and CdYb₂S₄ were refined in order to establidh the exact cationic distribution. The R factors are 0.037 for 104 reflections (CdTm₂S₄) and 0.039 for 98 reflections (CdYb₂S₄) Unlike CdHo₂S₄ abd CdY₂S₄, the structures are of normal spinel type and intersticial cation defects are not observed.     

Cu-Sn-P-ZnCr2S4(CdCr2S4)纳米复合镀层的性质和组成研究

为了获得耐蚀性能优异的复合化学镀层,利用中性化学复合镀技术,在A3碳钢片表面制备了金黄色光亮致密的Cu-Sn-P-ZnCr2S4和Cu-Sn-P-CdCr2S4纳米复合化学镀层.用扫描电子显微镜(SEM)观察了镀层外貌;以称重法测定厚度;通过5%NaCl溶液、1%H2S气体加速腐蚀试验、抗粘性试验及室温氧化试验等多种手段测定了其性能;用X射线光电子谱(XPS)及俄歇电子能谱(AES)测定了其价态及组成.结果表明:Cu-Sn-P-ZnCr2S4(CdCr2S4)纳米复合材料镀层的性能优于Cu-Sn-P合金镀层,复合镀层Cu-Sn-P-ZnCr2S4中,各原子百分数(%)约为: Cu 68.00,Sn 3.50,P 6.90,Zn 2.10,Cr 4.20, S 8.40,C 6.80;Cu-Sn-P-CdCr2S4中:Cu 69.00,Sn 3.30,P 5.90,Cd 2.4,Cr 4.8, S 9.60,C 4.80.Cu-Sn-P-ZnCr2S4占镀层的93.10%,Cu-Sn-P-CdCr2S4占镀层的95.00%.所得镀层耐蚀性好,耐盐水及室温氧化性能均优于Q235钢片和相近厚度的Cu-Sn-P合金镀层.     

Invariants of electromechanical coupling coefficients in piezoceramics

The relationships between coefficients of electromechanical coupling (CEMC) of various types of piezoceramic resonator (PR) vibrations are considered. Being constant for a given piezoceramic state, the range of variation of piezoceramics dielectric permittivity from a mechanically "free" condition at relatively low frequencies up to an "overall clamped" condition at high frequencies is determined by a consecutive "clamping", caused by a complex of CEMCs of various particular vibrational modes peculiar to the resonator. As the difference between "free" and "overall clamped" permittivities is always determined by the maximal piezomaterial /spl kappa//sub i3/ coupling coefficient, the difference does not depend on the path that was gone through the low-high frequency range, which includes all the vibrational modes possible for a particular PR. The influence of the piezoelectric and elastic anisotropy of lead-zirconate-titanate (PZT) piezoceramic materials on relative CEMC variations was experimentally investigated.