Chemical action and chemical bonding

New chemical bonding paradigm in terms of chemical action functional and of its reformulations by means of electronegativity, linear response and density softness kernels is advanced; it makes no use of traditional molecular orbital bonding analysis while providing reliability in identifying the bonding regions through appropriate specialization of the chemical action variational (conservation) principle along the bond length.     

Dynamical power-equalized fiber laser arrays using strain-tunable pump reflectors

By using strain-tunable gratings as pump reflectors for power equalization, both the parallel and serial types, pump-shared linear cavity laser arrays are produced. A 11-channel, parallel type fiber laser arrays are used to simulate the feasibility. After the central reflected wavelengths of these pump reflectors are appropriately adjusted, the maximum power variation among channels is reduced from 7.2- to 0.1 dB and the average output power is nearly 100% increased.     

A quantitative measure of bond polarity from the electron localization function and the theory of atoms in molecules

 A quantitative measure of the polarity of a bond can be obtained through combining the two complementary topological partitionings of the electron density obtained from the atoms in molecules theory, on the one hand, and the electron localization function, on the other. This requires an integration of the electron density in the atomic subbasins of a common bond electron localization basin. We present the first numerical application of the resulting topological definition of bond polarity to a set of small linear systems consisting of the FCN, HF, HCl, HBr, and NaCl molecules and the NeAr van der Waals dimer. It is shown that the findings are essentially in line with common expectation for these simple molecules, thus confirming the potential value of the novel bond polarity index for the analysis of controversial bonding situations. Additional insight is provided through the detailed investigation of fluctuations in the basin populations. Received: 10 January 2001 / Accepted 12 February 2001 / Published online: 22 May 2001     

Electronegativity and Molecular Properties

The paradigm that the properties of the atoms determine the properties of the molecules that they form is systematically presented. To this end, three types of atomic properties are differentiated: (a) those that can be determined directly by spectroscopy, (b) those based on theoretical concepts, and (c) those that can be assigned to the atoms interacting in molecules. On the basis of the electronegativity values of the atoms, which can be determined from spectroscopic data together with the assumption that the electronegativities are equalized in bonds, partial charges of the atoms in molecules are determined. These partial charges are correlated with ESCA data and proton affinities. In addition, simple expressions are given for the reliable estimation of bond lengths, bond energies, and force constants. For corrigendum see DOI: 10.1002/anie.199607811     

Dynamic Programming in Digital Communications: Viterbi Decoding to Turbo Multiuser Detection

Many important signal processing tasks in digital communications are based on integer programming problems whose raw complexity is extremely high. Such problems include the decoding of convolutional codes, channel equalization, multiuser detection, and the joint performance of these tasks. In each of these problems, the high complexity arises from the need to perform simultaneous processing on long sequences of finite-valued symbols in order to optimally detect or decode them. Fortunately, the complexity of these optimization problems can often be greatly reduced through the use of dynamic programming, which efficiently finds optimal [e.g., maximum likelihood (ML) or maximum a posteriori probability (MAP)] decisions in long sequences of symbols. This paper reviews four decades of progress in this area: the Viterbi algorithm for ML decoding of convolutional codes of the 1960s; the ML sequence detectors for channel equalization and the BCJR algorithm for MAP decoding of convolutional codes of the 1970s; the ML and MAP multiuser detectors of the 1980s; and combinations of these through the turbo processing of the 1990s.     

Application of digital speckle pattern interferometry and wavelet transform in measurement of transverse vibrations in square plate

In this paper the study of out-of-plane or transverse vibrations in a square plate using digital speckle pattern interferometry (DSPI) is presented. To improve the measurement accuracy, we have implemented a new filtering scheme based on combination of average/median filtering and Symlet wavelet filtering which enhances the signal to noise ratio in the speckle interferogram obtained from DSPI. A large number of fringe patterns are shown for square plate with two different boundary conditions. Experimentally obtained resonance frequencies for the square plate for the boundary condition one edge fixed and other edges being free, the resonance frequencies obtained from DSPI show good agreement with that obtained from classical theory for thin plates.     

Thermodynamic correlations and band gap calculations in metal oxides

Thermodynamic parameters and energy-band gap of a given metal oxide, are suitable measures of its stability. For this reason, direct correlations between energy-band gap or chemical hardness, and thermodynamic parameters (e.g. standard enthalpy of formation) have been constructed for different metal oxides. Furthermore, a simple relationship to calculate values of energy-band gaps, for metal oxides, from values of their enthalpies of formation, is presented here. When tested, an appreciable number of metal oxides from s- , p- and d-blocks well obeyed the relationship, while a number of metal oxides deviated. A qualitative theoretical account for such different behaviors is presented here.     

相干水声通信系统中均衡器长度设计方法

基于自适应均衡技术的相干通信被证明是有效的水声通信方式之一。在均衡器设计过程中,确定均衡长度的方法主要是经验确定与搜索算法,前者依赖于特定的环境,后者一般计算量较大。本文提出一种应用于相干水声通信系统的根据信道冲激响应确定均衡长度的设计方法。仿真及试验结果证明了该方法可以有效地提高通信的可靠性。     

产业核心技术突破的多主体多级均衡问题研究

产业核心技术研发具有“投入大、周期长、突破难”的特点,需走多主体参与、多级利益均衡、递阶式技术突破之路。基于此,立足产业外围技术发展和核心技术突破不同阶段,分别构建了“政府-企业”间的委托-代理博弈模型以及“政府-企业-学研机构”间的多方合作博弈模型;通过模型求解和数值仿真,分析各方博弈主体的损益关系以及影响其行为的关键因素。研究表明,影响外围技术发展的主要因素有企业的创新努力水平、政府激励、企业的风险规避度以及政企之间信息不对称的程度等,而影响核心技术突破的主要因素有政府激励、产学研创新费用、技术实现突破方式的概率等,相应地,不同阶段的对策与策略也应重点围绕上述因素进行设计。     

极值温差红外图像的自适应双局部增强算法

针对目前红外焦平面成像系统在观察目标、特别是极值温差目标时,各温度段灰度描述不均匀和细节不够的问题,提出了一种自适应红外图像双局部增强算法。详细介绍了通过空间分布和灰度统计特性两个方向实现对极值温差图像自适应增强的方法,该方法首先从红外图像的空间分布特性出发,将图像切割成多个局部图像,然后再从直方图灰度分布出发,将局部图像的直方图进行聚类分段,并对分段直方图均衡增强,最后对生成的每个局部图像增强结果进行线性插值拼接完成增强算法。通过在红外焦平面系统中实验证明了极值温差自适应的红外图像双局部增强算法的可行性,并获得了很好的效果,成像质量有明显提高。