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.     

Dynamics of laser hole drilling with nanosecond periodically pulsed laser

Results are presented on the dynamics of the laser drilling process for a single hole using a periodically pulsed nanosecond laser with a repetition rate up to 60 kHz. The intensity dependence of drilling velocity was determined by measuring the delay time between the beginning of exposure and the moment when the hole opens. The hole collapse phenomenon was observed in our experiments. The competition process between material ejection and the flow of the liquid phase into the ejected area is supposed to be responsible for the hole collapse.     

Synthesis of High χ–Low N Diblock Copolymers by Polymerization-Induced Self-Assembly

Polymerization-induced self-assembly (PISA) enables the scalable synthesis of functional block copolymer nanoparticles with various morphologies. Herein we exploit this versatile technique to produce so-called “high χ–low N” diblock copolymers that undergo nanoscale phase separation in the solid state to produce sub-10 nm surface features. By varying the degree of polymerization of the stabilizer and core-forming blocks, PISA provides rapid access to a wide range of diblock copolymers, and enables fundamental thermodynamic parameters to be determined. In addition, the pre-organization of copolymer chains within sterically-stabilized nanoparticles that occurs during PISA leads to enhanced phase separation relative to that achieved using solution-cast molecularly-dissolved copolymer chains.     

Detecting pipe changes via acoustic matched field processing

Detecting pipe irregularities such as intrusions can be challenging. However, subtle changes can be identified in the complex acoustic fields measured over a range of frequencies and over a time interval given an “array” of receivers. In particular, for two receivers one can coherently process the signals via matched field processing (MFP) to infer whether or not there have been changes such as new intrusions relative to undisturbed fields measured earlier. There is no acoustic modelling of the fields required, only the simple linear processor is applied, and only test data (five scenarios) are used in this demonstration. A key advantage to using MFP plus two (or more) microphones is that absolute sound levels need not be carefully measured.     

双色红外制导信息处理系统研究

介绍双色红外制导信息处理系统的基本原理，包括双色红外玫瑰线扫描制导原理，双色信号处理硬件原理，目标识别及方位角计算技术。     

Theorie und Optimierung der radiometrischen Absorptionsmethode zur Analyse von Binärsystemen

Die Arbeit behandelt theoretisch das Auflösungsvermögen der Absorptionsmethode zur Analyse von Binārsystemen bei Anwendung von monoenergetischer Gamma- und Rötgenstrahlung. Es wird eine analytische Beziehung für die Funktion Δp abgeleitet, die die kleinstmöglichen Veränderung in der Zusammensetzung des Systems chgarakterisiert und die wir noch mittelts dieser Methode in Abhängigkeit von allen zu berückischtigenden Faktoren bestimmen könne. Aus den Extremwerten der Funktion Δp werden dann die optimalen Werte der Energine, der Schichtdicke, der Strahlungshäufigkeit und die Optimalwerte der restlichen Parameter so bestimmt, daβ das Auflösungsvermögen der Methode maximal ist. Die Theorie wird auf eine Ag-Cu-Legierung angewendet.     

The technical efficiency of vacuum-pan sugar industry of India: An application of a stochastic frontier production function using panel data

A stochastic production frontier method is used to examine technical efficiency among Indian vacuum-pan sugar factories over a five-year period. Most factories are close to Indian best practice in terms of technical efficiency. Smaller firms and firms with access to sweeter cane are likely to be more efficient than other firms, while publicly owned firms are less efficient. There are transitory positive effects of a long crushing season on technical efficiency.     

基于标志点识别的自主车视觉导航

提出了一种基于室内标志点识别的单目视觉导航的方法。在地面上有规律地旋转一些标志点,采用辅助先验知识对标志点进行识别和分割,利用透视投影变换得到标志点与摄像机之间的相对距离,达到通过单目摄像机获得景物深度信息的目的。整个算法结构简单,易于实现,对由照明不均匀和地面反光所引起的各种干扰有较好地抑制作用。     

十六元树、二值图象数据压缩

本文介绍了一种二值图象数据压缩的十六元树方法,它具有效率高、便于实现,无失真恢复等特点,是处理二值图象中极为实用的方法,