The Marple algorithm for the autoregressive spectral estimates of the SMMW fourier transform spectroscopy data

The Marple algorthm for the autoregressive spectral estimates has been applied to the SMMW Fourier transform spectrum analysis. The experimental results have shown that this method yields AR spectra with three times higher resolution than the FFT method does. The improvements obtained from the Marple algorithm over the maximum entropy algorithm include higher resolution, less bias in the spectral peak frequency estimation and absence of observed spectral line splitting. The effects of the structure of the spectral lines and the noise on the resolution are discussed.Projects supported by National Natural Science Foundation of China     

Super S_(25)与New S_(25)光电阴极的光谱响应特性的数值模拟

根据多碱光电阴极的光谱响应理论表达式 ,对荷兰DEP公司和日本Hamamatsu公司美国分公司开发的两种SuperS2 5阴极的光谱响应曲线进行了理论模拟 ,得到了这些阴极的有关特性参量 ,并通过对模拟结果的分析以及与美国夜视实验室研制的NewS2 5光电阴极特性的比较 ,揭示了两种SuperS2 5光电阴极内在机理和可能采用的工艺处理方法 ,对多碱光电阴极的理论研究和实际操作具有指导意义     

Influence of the UV radiation wavelength on the curing of oligourethaneacrylate compositions for protective coatings of optical fibers

The curing kinetics of films produced from compositions based on UV-curable oligourethaneacrylates is investigated using, as a source of radiation, an individual spectral line separated by a monochromator from the radiation of a DRT-400 mercury tubular lamp. It has been established that in the region of spectral sensitivity of the composition, the curing time of the film is inversely proportional to the intensity of volumetric absorption of the radiation-source photons by the initiator at the lower surface of the film under study. Individual contributions of some of the lines to the process of composition curing by using the integral spectrum of the radiation source have been evaluated. The spectral-kinetic results obtained were confirmed when using the compositions under study as protective coatings of optical quartz fibers.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 836–840, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Extension of the distributed point source method for ultrasonic field modeling

The distributed point source method (DPSM) was recently proposed for ultrasonic field modeling and other applications. This method uses distributed point sources, placed slightly behind transducer surface, to model the ultrasound field. The acoustic strength of each point source is obtained through matrix inversion that requires the number of target points on the transducer surface to be equal to the number of point sources. In this work, DPSM was extended and further developed to overcome the limitations of the original method and provide a solid mathematical explanation of the physical principle behind the method. With the extension, the acoustic strength of the point sources was calculated as the solution to the least squares minimization problem instead of using direct matrix inversion. As numerical examples, the ultrasound fields of circular and rectangular transducers were calculated using the extended and original DPSMs which were then systematically compared with the results calculated using the theoretical solution and the exact spatial impulse response method. The numerical results showed the extended method can model ultrasonic fields accurately without the scaling step required by the original method. The extended method has potential applications in ultrasonic field modeling, tissue characterization, nondestructive testing, and ultrasound system optimization.     

A study on radial directional natural frequency and damping ratio in a vehicle tire

The measurement of radial directional natural frequency and damping ratio in a vehicle tire has been studied. Natural frequencies and damping ratios in the radial direction of various tires, from passenger car tires to truck bus tires, are reported. The radial direction modal parameters of tires subjected to different levels of inflation pressure, have been determined by using a frequency response function method. To obtain the theoretical natural frequency and mode shape, the plane vibration of a tire has been modeled as though it were that of a circular beam. By using the Tielking method that is based on Hamilton’s principle, theoretical results have been determined by considering the rotational velocity, tangential and radial stiffness, radial directional velocity and tension force which is due to tire inflation pressure. The results show that experimental conditions can be considered as the parameters that shift the natural frequency and damping ratio.     

New massively parallel linear-response coupled-cluster module in ACES III: application to static polarisabilities of closed-shell molecules and oligomers and of open-shell radicals

ABSTRACT

Stemming from our implementation of parallel coupled-cluster (CC) capabilities for electron spin resonance properties [J. Chem. Phys. 139, 174103 (2013)], we present a new massively parallel linear response CC module within ACES III. Unlike alternative parallel CC modules, this general purpose module evaluates any type of first- and second-order CC properties of both closed- and open-shell molecules employing restricted, unrestricted and restricted-open-shell Hartree–Fock (HF) references. We demonstrate the accuracy and usefulness of this module through the calculation of static polarisabilities of large molecules. Closed-shell calculations are performed at the following levels: second-order many-body perturbation theory [MBPT(2)], CC with single- and double-excitations (CCSD), coupled-perturbed HF and density functional theory (DFT), and open-shell calculations at the unrestricted CCSD (UCSSD) one. Applications involve eight closed-shell organic-chemistry molecules (Set I), the first four members of the closed-shell thiophene oligomer series (Set II), and five open-shell radicals (Set III). In Set I, all calculated average polarisabilities agree reasonably well with experimental data. In Set II, all calculated average polarisabilities vs. the number of monomers show comparable values and saturation patterns and demonstrate that experimental polarisabilities may be inaccurate. In Set III, UCCSD perpendicular polarisabilities show a reasonable agreement with previous UCCSD(T) and restricted-open-shell-MBPT(2) values.     

结合小波分析法与导数光声光谱技术测量弱光谱信号的实验研究

结合导数光声光谱技术与小波分析方法,精确测量了光声光谱中的弱光谱信号.首先利用自己设计的仪器装置实现光声光谱的一阶导数,在此基础上,根据导数光声光谱的数据选择合理的分析小波,将光声光谱信号分解为不同频率信号的叠加,被分解的信号满足线性性质且原信号的峰值信息保持不变,由频率的差异可区分出光声信号和噪声信号,从而提取出光声光谱中的弱光谱信号.结合物理方法与软件方法的分析结果,准确地测量了氙灯的输出光声光谱中3个不明显的弱峰值,位置分别为699.7nm、753.4nm和776.5nm.该方法可以更准确地提取出光声光谱的峰值信息,有效地提高了光声光谱的测量精度,为光声光谱分析法在生物医学及化学分析中的应用提供了一种更精确的分析方法.     

Supernova neutrino detection by terrestrial nuclear detectors

We present and discuss differential cross sections for the ^128,130Te isotopes, contents of the COBRA double beta decay detector. The response of these isotopes to energy spectra of supernova neutrinos is explored by convoluting the original results, calculated in the context of the quasi-particle random phase approximation (QRPA) using realistic two-body forces, with a two-parameter Fermi-Dirac (FD) and a Power-Law (PL) neutrino energy distributions.     

Numerical analysis of three-colour HgCdTe detectors

The performance of three-colour HgCdTe photovoltaic heterostructure detector is examined theoretically. In comparison with two-colour detectors with two back-to-back junctions, three-colour structure contains an absorber of intermediate wavelength placed between two junctions and electronic barriers are used to isolate this intermediate region. This structure was first proposed by British workers. Three-detector structures with different localizations of separating barriers are analyzed. The calculation results are presented in the form of spatial distributions of bandgap energy and quantum efficiency. Enhanced original computer programs are applied to solve the system of non-linear continuity equations for carriers and Poisson equations. In addition, the numerical analysis includes the dependence of absorption coefficient on Burstein effect as well as interference effects in heterostructure with metallic electrical contacts. It is shown that the performance of the detector is critically dependent on the barrier’s doping level and position in relation to the junction. This behaviour is serious disadvantage of the considered three-colour detector. A small shift of the barrier location and doping level causes serious changes in spectral responsivity.     

Modeling of IR Spectra of Selectively Substituted Glucopyranoside Nitrates

The frequencies of the normal vibrations of the molecules of 2,6- and 3,6-di-O-nitro-methyl--D-glucopyranosides and 2,3,6-tri-O-nitro-methyl--D-glucopyranoside have been calculated within the valence-force-field approximation in combination with calculation of the absolute intensities of the IR absorption bands of these molecules by the CNDO/2 method. The regularities in the structure of the complex IR absorption bands characteristic for nitro groups formed as a result of selective nitrosubstitution have been explained.