The lion and man problem revisited

A pursuerP, whose speed is bounded by 1, wants to get closer to an evaderE, whose speed is bounded by >1.P wants to reduce his distancePE fromE below the capture radius . Both players are confined to a circular arena. This problem is equivalent to a problem discussed by Flynn, who characterized and gave numerical bounds to the least upper boundd* on the values ofPE thatE can maintain. He used direct methods and did not use Isaacs' theory.We solve our problem relying on the theory of singular surfaces in differential games. We construct and investigate barriers of the game of kind, and we replace Flynn's bounds ond* by analytical (exact) values for various speeds .The support of the TW Department of THT, Enschede, Holland, is gratefully acknowledged.     

Ab initio study of the ground state and conformational stability of peroxyacetyl nitrate in internal rotation about the peroxide bond

The molecular and electronic structure of the ground state of peroxyacetyl nitrate (PAN) was calculated by the unrestricted Hartree-Fock-Roothaan method with the use of the standard 3–21G and 6–31G basis set. The potential curve of the internal rotation about the peroxide bond of PAN was calculated with the 6–31G basis set. The curve contains two maxima. The ground state of PAN is characterized by a structure in which groups of atoms adjacent to the peroxide bond lie in planes that are perpendicular to each other (the dihedral angle ϱ(COON) is 89.9°). The calculated barriers to rotation are 19.6 and 66.8 kJ mol⁻¹. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 600–604, April, 1998.     

Synthesis and inversion barriers of undeca- and dodeca-substituted saddle shaped porphyrin complexes

Synthesis and barriers to inversion of a series of highly saddle shaped complexes are reported. The ΔG^≠ has decreased by 8 kJ mol⁻¹ at 243 K when the meso phenyl groups are replaced by bulkier 2,6-dichlorophenyl groups, and by 17 kJ mol⁻¹ when one of the peripheral ethyl groups is removed.     

A Background and noise elimination method for quantitative calibration of near infrared spectra

A new hybrid algorithm is proposed to eliminate the varying background and noise simultaneously for multivariate calibration of near infrared (NIR) spectral signals. The method is based on the use of multi-resolution, which is one of the main advantages provided by wavelet transform. The signals are firstly split into different frequency components, which keep the same data points of the original signals. In conjunction with a modified uninformative variable elimination (mUVE) criterion, the new method can be used to remove the low-frequency varying background and the high-frequency noise simultaneously. The method is successfully applied to simulated spectral data set and experimental NIR spectral data, resulting in more parsimonious multivariate models with higher precision. In addition, the proposed strategy can be applied to other spectral signals as well.     

振动噪声等高图的电驱动桥噪声预测及优化*

在项目开发前期通过优化电驱动桥扭矩特性的设计,可以规避噪声大问题。根据电驱动桥台架在对应扭矩下的振动噪声特性,提出了一套稳定高效的测试流程和分析方法。首先设计了一套完整的试验流程,制定了精准的数据分析方法。然后绘制出能够全面反映电驱动桥振动噪声特性的等高图。最后利用电驱动桥台架的振动噪声等高图,准确评估电驱动桥加速工况下振动噪声风险,为主机厂和电驱动桥零部件企业提供电驱动桥扭矩特性设计前期指导。利用该方法成功识别到某电驱动桥匀速及加速工况下电机及齿轮的啸叫问题。通过优化电驱动桥扭矩特性设计,电机48阶噪声峰值降低了8.5dB(A),确认该方法准确可靠,具备推广应用价值。     

基于经验模态分解的SO_2浓度检测信号处理方法

荧光法测量SO2浓度是大气监测中常用的检测手段.双光路技术可以消除光源和光路的噪音干扰,但光电转换器件在激发光照射下产生的背景噪音也会影响定量分析的准确度.本文采用经验模态分解滤波算法降低检测中存在的各种噪音,在实现有效降噪的基础上较好地保存了有用的原始信号.仿真结果表明,针对SO2浓度检测系统,利用经验模态分解去噪后信号的信噪比达到204.273 6,均方误差为0.007 0.与小波去噪法相比,经验模态分解检测效果更佳.最后将经两组不同方法处理后的信号应用于气体检测系统中,实验数据的线性关系更好地验证了经验模态分解方法应用到浓度检测系统的可行性.     

利用海洋环境噪声互相关实现阵形校准

阵列信号处理需要准确的阵形,然而海底水平阵的阵形很难精确测量。利用海洋环境噪声可以提取两点间的格林函数,这为无源校准阵形提供了新的可能。通过海洋环境噪声互相关叠加可以获取两个阵元之间的距离信息,一种方法是可以通过该距离与位置之间的关系构建非线性方程组并利用最小二乘法(LS)求解阵形。本文利用多维尺度变换法(MDS)求解,通过对度量矩阵的特征值分解获得阵形。数值仿真和实验数据证明了该方法的可行性,并且MDS相比于LS有更稳健的性能。     

Low dose measurement with thick gate oxide MOSFETs

The low dose limit and the accuracy of high sensitivity MOS ionizing radiation dosimeters fabricated at LAAS-CNRS are investigated.     

Barriers to Internal Rotation and Conformational Behaviour of the MESO and D,L Isomers of Pt(II) Complexes with Antitumour Activity

Abstract

The conformational behaviour of a series of ring substituted (ortho-Cl, F and meta or para OH) Pt(II) complexes of general formula [(1,2-hydroxyphenyl)ethylenediamine]PtL₂ [L ? Cl, 1] has been studied by molecular mechanics (MM) methods. Preferred orientations of the phenyl rings, which are important for the complexes′ biological activity, were obtained by calculations of rotational energies about C_sp3?C_ar bonds for all theoretically possible isomers and conformers, meso-λ (R,S/S,R-λ), meso-δ (R,S/S,R-δ), d,l-δ (S,S/R,R-λ) and d,l-λ (S,S/R, R-δ). The influence of the ring substituents and the conformation type on the positions of the energy minima and barriers to rotations about C_sp3?C_ar and C_ar-O(H) bonds were investigated in detail. Theoretical predictions were compared with the experimental results where appropriate.     

Polymeric Electron Carriers

Polymers containing 1,4-dihydronicotinamide (P-NAH) alloxan (P-A), and viologen (P-V²⁺) moieties were synthesized and characterized. P-NAH reduced various organic substances such as lipoic acid, alloxan, and viologens and also immobilized quinone mediated by alloxan. P-A was reduced to the polymer-bearing alloxan radical and the dialuric acid structure without crosslinks by one- and two-electron reduction, respectively, and P-A also mediated the redox reaction occurring between aqueous and organic (water-immiscible) layers. P-V²⁺ was converted to the stable viologen radical reversibly by one-electron reduction. Electric potentials and currents on photo-reduction of P-V²⁺ and catalytic behavior of P-V²⁺ in the reduction of carbonyl compounds were examined.