不均匀不稳定磁场下高分辨液体核磁共振新技术的研究进展

高分辨核磁共振（Nuclear Magnetic Resonance,NMR）谱的获得通常需要高度稳定且均匀的强静磁场. 阻抗磁体或阻抗－超导混合磁体可获得比超导磁体高得多的磁场, 但它们的磁场的稳定性与均匀性比较差;另一方面, 在活体定域波谱研究中,样品内部组分的磁化率差异,运动或生理活动等作用将不可避免地导致磁场的不均匀不稳定,并且这些不稳定不均匀性无法通过锁场匀场等传统的方法消除. 基于分子间零量子相干的方法、空间编码单扫描快速方法、反卷积技术等日渐成为在不均匀不稳定磁场下获取高分辨率的NMR谱的研究热点.     

一种易于硬件实现的图像有损压缩算法

原始图像数据经过小波变换后,根据子带系数之间在空间上和方向上所呈现出的带间相似性,将像素集合重新定义为集合树。通过对直流系数量化编码和交流系数比特深度编码中的参数K和熵编码中长度分别为3bit码字（choicel）和4bit码字（choice2）的编码方式的选择实现数据的渐进性编码,使产生的码流具有内嵌特性,可以对任意码流进行截取和译码,实现对码率的有效控制。提出了一种具有复杂度低、易于硬件实现的图像有损压缩算法。经过系统仿真证明此算法有利于提高重建图像的质量。     

Geometric Analysis and Symbol Calculus: Fourier Transform Magnetic Resonance Imaging and Wavelets

Due to its unequalled advantages, the magnetic resonance imaging (MRI) modality has truly revolutionized the diagnosis and evaluation of pathology. Because many morphological anatomic details that may not be visualized by other high tech imaging methods can now be readily shown by diagnostic MRI, it has already become the standard modality by which all other clinical imaging techniques are measured. The unique quantum physical basis of the MRI modality combined with the imaging capabilities of current computer technology has made this imaging modality a target of interdisciplinary interest for clinicians, physicists, biologists, engineers, and mathematicians. Due to the fact that MRI scanners perform corticomorphic processing, this modality is by far more complex than all the other high tech clinical imaging techniques. The purpose of this paper is to outline a phase coherent wavelet approach to Fourier transform MRI. It is based on distributional harmonic analysis on the Heisenberg nilpotent Lie group G and the associated symplectically invariant symbol calculus of pseudodifferential operators. The contour and contrast resolution of MRI scans which is controlled by symplectic filter bank processing gives the noninvasive MRI modality superiority over X-ray computed tomography (CT) in soft tissue differentiation.     

衰减相移掩模及其编码制作方法研究

在霍普金斯理论的基础上,对方孔的传统掩模、衰减相移以及加入光学邻近效应校正的衰减相移掩模在硅片表面光强分布的计算表明,衰减相掩模有提高光刻分辨率的显著功能,提出一种制作衰减相移掩模的编码方法。理论计算表明,该编码方法能够达到预定的衰减参数。     

Wavelet-modified maximum average correlation height filter for out-of-plane rotation invariance

In this paper, we implement a wavelet-modified maximum average correlation height (WaveMACH) filter for recognition of 0-360° out-of-plane rotated targets employing hybrid digital-optical correlator architecture. A chirp function is used with the synthesized WaveMACH filter, which focuses the correlation signals in three different planes, thereby providing the choice of recording a single correlation peak at a particular plane. Signal-to-noise ratio and peak-to-sidelobe ratio have been calculated as metrics of goodness of the proposed WaveMACH filter.     

Wave theory of light leading to the generalized vectorial laws of reflection and refraction

This paper deals with the application of Huygens’ wave theory of light for the derivation of the generalized vectorial laws of reflection and refraction discovered by the author in 2005. The long-running literature falls short of such a theoretical proof of the generalized vectorial laws of reflection and refraction on the basis of wave theory. As such the present work is novel and original. At the same time it also enhances the theoretical foundation of the discovery of the generalized vectorial laws of reflection and refraction there by proving the efficiency and increasing the range of applicability of the wave theory of light as well.     

New practical tools for the implementation and use of ultrafast 2D NMR experiments

Ultrafast (UF) 2D NMR is a very promising methodology enabling the acquisition of 2D spectra in a single scan. In the last few years, the analytical performance of UF 2D NMR has been highly increased, consequently maximizing its range of applications. However, its implementation and use by non‐specialists are far from being straightforward, because of the specific acquisition and processing procedures and parameters characterizing UF NMR. To make this methodology implementable and applicable by non‐specialists, we developed a simple routine capable of translating conventional parameters (spectral widths and transmitter frequencies) into specific UF parameters (gradient and chirp pulse parameters). This macro was subsequently implemented in a Web page, which is available for external users. Although the algorithm was designed for two widely used 2D experiments, COSY and HSQC, it can easily be extended to any other pulse sequence. The robustness of this routine was verified successfully on a variety of small molecules. We believe that this tool will eliminate much of the technical difficulties related to UF 2D NMR and will make the technique accessible to a wider audience of organic and analytical chemists. Copyright © 2013 John Wiley & Sons, Ltd.     

Vibrational spectroscopic encoding of polystyrene-based resin beads: converting the encoding peaks into barcodes

A detailed approach is described for the vibrational spectroscopic encoding of polystyrene-based resin beads by converting the infrared absorption peaks suitable for encoding (encoding peaks) into barcodes. Based on combining the FT-IR measurements and the quantum-chemical computations, the vibrational characteristics of p-tert-butylstyrene monomer, polystyrene and poly(p-tert-butylstyrene) resin beads are analyzed, which are helpful for the selection of encoding peaks. The vibrational spectroscopic encoding of polystyrene-based resin beads could be obtained by converting the wavenumber, intensity and full width at half maximum (FWHM) of the encoding peaks into barcodes automatically through a computer program designed in our laboratory.