A new beam propagation method based on least-squares expansion approximating

A new finite difference wide-angle beam propagation method is developed by introducing the least-squares expansion approximant in the propagator expansion. In this new method it is not necessary to select the reference index point because of the whole region approaching the lease-square expansion. This method avoids the problems induced by error selection of the reference index in the old methods based on Taylor or Pade expansion. Several typical structures are simulated by the new method and the results prove the validity of it.

Decomposition of circular dichroism of norepinephrine by singular value decomposition-least square method

Singular value decomposition - least squares (SVDLS), a new method for processing the multiple spectra with multiple wavelengths and multiple components in thin layer spectroelectrochemistry has been developed. The CD spectra of three components, norepinephrine reduced form of norepinephrinechrome and norepinephrinequinone, and their fraction distributions with applied potential were obtained in three redox processes of norepinephrine from 30 experimental CD spectra, which well explains electrochemical mechanism of norepinephrine as well as the changes in the CD spectrum during the electrochemical processes.

LEAST-SQUARES POLYNOMIAL SMOOTHING FOR INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTRA

The use of least-squres polynomial smoothing in ICP-AES is discussed and a method of points insertion into spectral scanning intervals is proposed in the present paper. Optimal FWHM/SR ratio can be obtained, and distortion of smoothed spectra can be avoided by use of the recommended method.

Weighted least-squares phase unwrapping algorithm based on derivative variance correlation map

Among different phase unwrapping approaches, the weighted least-squares minimization methods are gaining attention. In these algorithms, weighting coefficient is generated from a quality map. The intrinsic drawbacks of existing quality maps constrain the application of these algorithms. They often fail to handle wrapped phase data contains error sources, such as phase discontinuities, noise and undersampling. In order to deal with those intractable wrapped phase data, a new weighted least-squares phase unwrapping algorithm based on derivative variance correlation map is proposed. In the algorithm, derivative variance correlation map, a novel quality map, can truly reflect wrapped phase quality, ensuring a more reliable unwrapped result. The definition of the derivative variance correlation map and the principle of the proposed algorithm are present in detail. The performance of the new algorithm has been tested by use of a simulated spherical surface wrapped data and an experimental interferometric synthetic aperture radar (IFSAR) wrapped data. Computer simulation and experimental results have verified that the proposed algorithm can work effectively even when a wrapped phase map contains intractable error sources. (c) 2006 Elsevier GmbH. All rights reserved.

In situ surface topography measurement method of granite base in scanning wafer stage with laser interferometer

Topography of a granite surface has an effect on the vertical positioning of a wafer stage in a lithographic tool, when the wafer stage moves on the granite. The inaccurate measurement of the topography results in a bad leveling and focusing performance. In this paper, an in situ method to measure the topography of a granite surface with high accuracy is present. In this method, a high-order polynomial is set up to express the topography of the granite surface. Two double-frequency laser interferometers are used to measure the tilts of the wafer stage in the X- and Y-directions. From the sampling tilts information, the coefficients of the high-order polynomial can be obtained by a special algorithm. Experiment results shows that the measurement reproducibility of the method is better than 10 nm. (c) 2006 Elsevier GmbH. All rights reserved.

Determination of ethenzamide and acetoaminophen in quaternary powdered samples by near infrared spectroscopy and searching combination moving window partial least squares algorithm: effects of spectral resolution and signal-to-noise ratio

The present study reports an application of the searching combination moving window partial least squares (SCMWPLS) algorithm to the determination of ethenzamide and acetoaminophen in quaternary powdered samples by near infrared (NIR) spectroscopy. Another purpose of the study was to examine the instrumentation effects of spectral resolution and signal-to-noise ratio of the Buchi NIRLab N-200 FT-NIR spectrometer equipped with an InGaAs detector. The informative spectral intervals of NIR spectra of a series of quaternary powdered mixture samples were first located for ethenzamide and acetoaminophen by use of moving window partial least squares regression (MWPLSR). Then, these located spectral intervals were further optimised by SCMWPLS for subsequent partial least squares (PLS) model development. The improved results are attributed to both the less complex PLS models and to higher accuracy of predicted concentrations of ethenzamide and acetoaminophen in the optimised informative spectral intervals that are featured by NIR bands. At the same time, SCMWPLS is also demonstrated as a viable route for wavelength selection.

Low-temperature heat capacity and standard molar enthalpy of formation of 9-fluorenemethanol (C14H12O)

Low-temperature heat capacities of the 9-fluorenemethanol (C14H12O) have been precisely measured with a small sample automatic adiabatic calorimeter over the temperature range between T = 78 K and T = 390 K. The solid-liquid phase transition of the compound has been observed to be T-fus = (376.567 +/- 0.012) K from the heat-capacity measurements. The molar enthalpy and entropy of the melting of the substance were determined to be Delta(fus)H(m) = (26.273 +/- 0.013) kJ (.) mol(-1) and Delta(fus)S(m) = (69.770 +/- 0.035) J (.) K-1 (.) mol(-1). The experimental values of molar heat capacities in solid and liquid regions have been fitted to two polynomial equations by the least squares method. The constant-volume energy and standard molar enthalpy of combustion of the compound have been determined, Delta(c)U(C14H12O, s) = -(7125.56 +/- 4.62) kJ (.) mol(-1) and Delta(c)H(m)degrees(C14H12O, s) = -(7131.76 +/- 4.62) kJ (.) mol(-1), by means of a homemade precision oxygen-bomb combustion calorimeter at T = (298.15 +/- 0.001) K. The standard molar enthalpy of formation of the compound has been derived, Delta(f)H(m)degrees (C14H12O, s) = -(92.36 +/- 0.97) kJ (.) mol(-1), from the standard molar enthalpy of combustion of the compound in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle. (C) 2004 Elsevier Ltd. All rights reserved.

Conformational transition of DNA induced by cationic lipid vesicle in acidic solution: spectroscopy investigation

The conformational transition of DNA induced by the interaction between DNA and a cationic lipid vesicle, didodecyidimethylammonium bromide (DDAB), had been investigated by circular dichroism (CD) and UV spectroscopy methods. We used singular value decomposition least squares method (SVDLS) to analyze the experimental CD spectra. Although pH value influenced the conformation of DNA in solution, the results showed that upon binding to double helical DNA, positively charged liposomes induced a conformational transition of DNA molecules from the native B-form to more compact conformations. At the same time, no obvious conformational changes occurred at single-strand DNA (ssDNA). While the cationic lipid vesicles and double-strand DNA (dsDNA) were mixed at a high molar ratio of DDAB vesicles to dsDNA, the conformation of dsDNA transformed from the B-form to the C-form resulting in an increase in duplex stability (DeltaT(m) = 8 +/- 0.4 degreesC). An increasing in T-m was also observed while the cationic lipid vesicles interacted with ssDNA.

Photochemical synthesis and crystal structure of a charge transfer salt [HMDH2][(H2PMoMo11O40)-Mo-v]center dot 2AA center dot 3H(2)O center dot DMF

The title supramolecular compound, [HMDH2][(H2PMoMo11O40)-Mo-V] . 2AA . 3H(2)O . DMF (HMD = hexamethylene diamine; AA=acetaldehyde; DMF=N,N-dimethyl formamide), has been photochemically synthesized by using elemental analysis, IR, solid diffusion reflectance, electronic spectra, ESR spectra and X-ray single-crystal analysis. The crystallographic data: triclinic, P (1) over bar, a=14.092(2), b=14.347(3), c=14.358(3)Angstrom, alpha = 75.10(3), beta = 80.70(3), gamma = 80.73(3)degrees, V = 2746.6(10)Angstrom (3), Z = 2, M-r = 2081.68, D-c=2.517g/cm(3), F(000) =1970, mu (MoK alpha) =2.766mm(-1). The structure has been refined to R =0.0832 and wR=0.2638, by full-matrix least-squares method. The title compound is composed of hexamethylene diamine, two acetaldehyde molecules, three water molecules, one N,N-dimethylformamide and [(H2PMoMo11O40)-Mo-V](2-) heteropoly anion.

Simultaneous spectrophotometric determination of zinc, cadmium and mercury with hybrid linear analysis

A new method for simultaneous spectrophotometric determination of Zn, Cd and Hg using 2-(5-Br-2-pyridylazo)-5-diethylaminophenol as the color developing reagent was proposed. The absorption spectra of these three complexes have similar features with severe overlap in visible spectral range. For resolving these spectra, hybrid linear analysis was used, and the pure spectrum of each component was obtained from the calibration mixtures by least squares method. The effects of reaction condition, selection of wavelengths, determination of pure spectrum and additivity of absorbances etc. on the determination were discussed. The proposed method offers the advantages of simple, rapid, and accuracy. It has been successfully applied to the simultaneous determination of Zn, Cd and Hg in synthetic sample. A comparison was also made with the partial least squares method.

Hydrothermal synthesis and crystal structure of sandwich-like heteropolymolybdophosphates

Sandwich-like heteropoly molybdochromophosphates of supermolecular compound [NH3(CH2)(6)NH3](2)H-3{Cr[Mo6O15(HPO4)(H2PO4)(3)](2)}. 4H(2)O has been hydrothermally synthesized and the single crystal structure has been determined by X-ray diffraction. The crystal data are has follows: triclinic, space group P (1) over bar a=12.156(2), b=12.809(3), c=13.530(3) Angstrom, alpha=102.46(3)degrees, beta=93.67(3)degrees, gamma=93.46(3)degrees, V=2046.9(7) Angstrom(3), Z=1, M-r=2768.69, D-c=2.246 g/cm(-3), F(000)=1337, mu=2.162 mm(-1). The structure has been refined to R=0.0666 and wR=0.1745 by full-matrix least-squares method. The title compound is composed of 1, 6-diaminohexane, water molecules, and {Cr[Mo6O15(HPO4)(H2PO4)(3)](2)}(7-) anion which consists of six oxygen atoms from two [Mo6P4] units with a sandwich-like transition metal atom Cr located at the center of symmetry.

Synthesis and crystal structure of aluminium complex with 3-hydroxyflavone

[Al(C15H9O3)(3)](2) . 2CHCl(3) . 8H(2)O was synthesized, and its crystal structure was determined. It belongs to trigonal system, R3, a=b=1. 655 8(3) nm, c=3. 646 5(20) nm, alpha = beta = 90 degrees, gamma = 120 degrees, V = 8. 656 08(0. 005 86) nm(3). D-c = 1.45 g/cm(3), mu(Mo K alpha) = 3. 20 cm(-1), F (000) = 3 924. The crystal structure was solved by Patterson and Fourier techniques, and refined by a block-diagonal least-squares method. A total of 3 737 independent intensity data were collected, of which 1 033 with I greater than or equal to 3 sigma(I-0) were observed, R = 0. 091 8, Rw=0. 091 8. Al3+ ion was 6-coordinated, bound to six oxygen atoms from three 3-hydroxyflavones to form a distortional coordination octahedron.

共反射面元叠加

The seismic survey is the most effective prospecting geophysical method during exploration and development of oil/gas. The structure and the lithology of the geological body become increasingly complex now. So it must assure that the seismic section own upper resolution if we need accurately describe the targets. High signal/noise ratio is the precondition of high-resolution. As one important seismic data processing method, Stacking is an effective means to suppress the records noise. Broadening area of surface stacked is more important to enhance genuine reflection signals and suppressing unwanted energy in the form of coherent and random ambient noise. Common reflection surface stack is a macro-model independent seismic imaging method. Based on the similarity of CRP trace gathers in one coherent zone, CRS stack effectively improves S/N ratio by using more CMP trace gathers to stack. It is regarded as one important method of seismic data processing. Performing CRS stack depends on three attributes. However, the equation of CRS is invalid under condition of great offset. In this thesis, one method based on velocity model in depth domain is put forward. Ray tracing is used to determine the traveltime of CRP in one common reflection surface by the least squares method to regress the equation of CRS. Then we stack in the coherent seismic data set according to the traveltime, and get the zero offset section. In the end of flowchart of implementing CRS stack, one method using the dip angle to enhance the ratio of S/N is used. Application of the method on synthetic examples and field seismic records, the results of this method show an excellent performance of the algorithm both in accuracy and efficiency.

Intensity-moments characterization of general pulsed paraxial beams with the Wigner distribution function

On the basis of the space-time Wigner distribution function (STWDF), we use the matrix formalism to study the propagation laws for the intensity moments of quasi-monochromatic and polychromatic pulsed paraxial beams. The advantages of this approach are reviewed. Also, a least-squares fitting method for interpreting the physical meaning of the effective curvature matrix is described by means of the STWDF. Then the concept is extended to the higher-order situation, and what me believe is a novel technique for characterizing the beam phase is presented. (C) 1999 Optical Society of America [S0740-3232(99)001009-1].