Application of a New Program,H1MACH,for Prediction of Iridoid Skeletons

Abstract

A procedure is presented that utilizes ¹H NMR for prediction of the skeleton of iridoids. A new program was developed, named H1MACH, that presents a database with 800 data points from the ¹H NMR spectra of iridoids. This program was widely tested for the prediction of the skeleton of 40 compounds and compared with other programs in the expert system SISTEMAT. The results obtained show that H1MACH is very useful for the prediction of the skeleton of iridoids, especially for the iridane skeleton.     

Computer-generated holograms from 3D-objects written on twisted-nematic liquid crystal displays

In order to optimize computer-generated holograms (CGHs) for three-dimensional objects, an extension of the well known Gerchberg-Saxton algorithm is used. Optical reconstructions using an electrically addressed twisted-nematic liquid crystal display are presented. For arbitrary CGHs, reconstructing 3D-objects, we will discuss the problems and solutions associated with periodic replication of holograms.     

最大平均相关高度滤波算法在畸变目标识别中的应用

为了解决在联合变换相关器上无法识别复杂背景下畸变目标(目标的平面内旋转或尺寸改变)的问题,对其应用最大平均相关高度滤波算法进行畸变目标识别.首先在频域内优化最大平均相关高度滤波器的三个性能控制参量|然后将优化好的最大平均相关高度频域滤波器映射到物空间,得到最大平均相关高度参考模板.作为实例,本文对复杂背景下的军舰和汽车目标进行了光学识别实验,结果表明,当滤波器的控制参量为γ=1,α=0,β=0.1时,得到的MACH参考模板最为清晰,目标产生的相关峰最为尖锐明亮.通过这种方法,在联合变换相关器上能够得到的比例畸变容差为28%,旋转畸变容差为20°,对于超出上述畸变容差范围的目标,相关峰强度逐步减弱,但部分仍然可以识别.改进后的MACH滤波器在畸变目标的探测领域具有很强的优势和良好的应用前景.     

最大平均相关高度滤波算法在畸变目标识别中的应用

为了解决在联合变换相关器上无法识别复杂背景下畸变目标(目标的平面内旋转或尺寸改变)的问题,对其应用最大平均相关高度滤波算法进行畸变目标识别.首先在频域内优化最大平均相关高度滤波器的三个性能控制参量;然后将优化好的最大平均相关高度频域滤波器映射到物空问,得到最大平均相关高度参考模板,作为实例,本文对复杂背景下的军舰和汽车...     

Recording a binary computer-generated hologram on a thermoplastic film

A computer-generated hologram was recorded on a thermoplastic film using an electron-beam recording device. The hologram was a binary one of detour phase type and of surface relief type. A bright image was reconstructed from the recorded hologram.     

Voltage-controlled liquid-crystal terahertz phase shifter and quarter-wave plate

Phase shift exceeding tau/2 at 1 THz is demonstrated by using electrically controlled birefringence in a homeotropically aligned nematic liquid crystal (E7) cell, 570 microm in thickness. The driving voltage required for a phase shift of 90 degrees is 125 V (rms). We demonstrate that the phase shifter works as an electrically switchable quarter-wave plate at 1 THz. The device can also be used as an electrically tuned phase compensator around the quarter-wave point near 1 THz.     

云层背景目标识别的匹配滤波器设计

提出一种利用最大平均相关高度(MACH)算法识别复杂云层背景目标的改进滤波器设计方法。在MACH滤波器设计中,通过对云层背景功率谱的统计特性分析,数据拟合得到云层背景功率谱的分布函数,用以代替传统的白噪声模型;提取飞行目标的姿态变化图像,并作阈值化处理,得到训练样本。对不同云层背景和姿态变化目标的相关识别结果表明:改进滤波器的平均峰值相关能量比为0.71%,峰值鉴别率为0.92,可以有效抑制云层背景的干扰,对姿态变化目标识别的鲁棒性较好。     

Techniques for recording holographic lenses for infrared wavelengths

Three approaches for recording holographic lenses for infrared wavelengths are discussed. For long wavelengths such as the 10.6 μm line from CO₂ lasers holographic lenses are best made as computer-generated holograms. For the near infrared holographic lenses can be made using visible wavelengths with a computer-generated hologram to provide aberration correction. Finally a two step procedure is described which can be used to make holographic lenses for most infrared wavelengths.     

Electrically controlled optical switch in the hybrid opto-electromechanical system

To promote the future quantum information technologies, we demonstrate an electrically driven optical switch based on quantum interference in a hybrid opto-electromechanical system, which consists of an opto-mechanical cavity and an external electric circuit. The key element of our scheme is a moveable mirror of cavity as a charged mechanical oscillator capacitively coupled to a fixed charged plate in a variable capacitor. By adjusting the voltage of the capacitor, the displacement of the moveable mirror is modulated, then the cavity field can be electrically turned on or off due to the detuning of the cavity. Based on the cavity induced transparency, the transparency window can be electrically switched on or off by turning on or off the cavity field. Therefore, the susceptibility of the medium in the cavity can be electrically controlled, i.e., the scheme of the electrically controlled absorption switching can be demonstrated. This electrically driven optical switch will excite a development trend and implementation prospect towards the integration and miniaturization of quantum module device in a chip.     

增强现实技术综述

增强现实技术是将计算机渲染生成的虚拟场景与真实世界中的场景无缝融合起来的一种技术,它通过视频显示设备将虚实融合的场景呈现给用户,使人们与计算机之间的交互更加的自然,同时具有广泛的应用前景,因此成为近年来的一个研究热点。随着跟踪注册技术的进步、计算机性能的飞速发展、深度摄像机的普及,以及Light Field投影技术在增强现实中的应用,增强现实技术逐渐成为下一代人机交互的发展方向。该文章首先概述了增强现实的主要研究内容和发展情况,并详细介绍了增强现实的关键技术、开发工具,然后分类概述了增强现实应用案例。     

云层背景目标识别的匹配滤波器设计

提出一种利用最大平均相关高度(MACH)算法识别复杂云层背景目标的改进滤波器设计方法。在MACH滤波器设计中,通过对云层背景功率谱的统计特性分析,数据拟合得到云层背景功率谱的分布函数,用以代替传统的白噪声模型;提取飞行目标的姿态变化图像,并作阈值化处理,得到训练样本。对不同云层背景和姿态变化目标的相关识别结果表明:改进滤波器的平均峰值相关能量比为0.71%,峰值鉴别率为0.92,可以有效抑制云层背景的干扰,对姿态变化目标识别的鲁棒性较好。     

Electrically Controlled Dimensionality of Magnetic Systems in Organic Materials

Electrically controlling charge density in materials using electronic device structures shows various interesting phenomena, such as electrically induced ferromagnetism and superconductivity, owing to strong charge interactions. However, electrically controlled dimensionality of magnetic systems has not yet been fully investigated. Here we report electrically controlled magnetic interactions and dimensionality of magnetic systems in organic materials from a microscopic viewpoint, which were revealed by electron spin resonance (ESR) spectroscopy using ionic liquid-gated devices. The ESR investigation demonstrated that the magnetic systems’ dimensionality of electrically accumulated charges varied from zero dimensional to two dimensional in a regioregular polymer, regioregular poly(3-hexylthiophene) (RR-P3HT), by increasing charge densities. This phenomenon is in contrast to those in a small molecule pentacene and a regiorandom polymer, regiorandom poly(3-hexylthiophene) (RRa-P3HT), where it varied from zero to three dimensional when their charge densities increased. Moreover, the formation of the complete spinless states of electrically induced charges was observed. Our investigation demonstrates the novel magnetic systems based on electrically induced charges.     

Computer-generated holograms using (Se,S)-based chalcogenide amorphous film

New computer-generated holograms using As-Se-S-Ge chalcogenide amorphous film are presented. The chalcogenide film is sensitive to an electron beam and has a high resolution (3000 lines/mm). Utilizing a fine focused electron beam and a high resolution of the amorphous film, full size computer-generated holograms can be directly fabricated without reducing process, and thus a real-time process is possible. Computer-generated holograms with 64 × 64 cells have been experimentally demonstrated in 560 μm × 560 μm hologram size.     

Directional response pattern simulator

Experiments designed to measure the directional response patterns of acoustic radiators and receivers have basically to be carried out in an anechoic room. If, however, a simulator capable of electrically imitating the real process of forming the directional response pattern is available, one can carry out a directional response determination whenever one wants to.The simulator described here uses a bucket brigade device (BBD) and other electronic components. A technique for describing the polar diagram of the directional response pattern is also discussed. Model experiments for obtaining the simple directional response patterns and for suppressing the side lobe can be successfully carried out with the aid of such a simulator.     

Computer-generated holograms: Reconstruction of curves in 3-D

The complex amplitude of a wave which gives rise to a focal curve of desired shape and position in space is determined in an analytical form and stored in a computer-generated hologram. Optical reconstructions of continuous foci are shown. The resolution limit due to diffraction effects is discussed.     

Polymeric, electrically tunable diffraction grating based on artificial muscles

We demonstrate a low-cost, electrically tunable diffraction grating that is driven by a dielectric elastomer actuator. The angular tuning range of the polymer-based device is up to 118 mrad for the first diffracted order. The achievable grating period change of 32% is an improvement by more than a factor of 150 compared with existing analog tunable diffraction gratings based on hard materials. We show that in combination with a white light source, the presented diffraction grating can be used as a wavelength-adjustable luminous source. Such an illuminant has a potential application in inexpensive color displays that could reproduce all perceivable colors.     

Improvement of fabrication and characterization methods for micromechanical disk resonators

In this paper we present a novel method to fabricate reliable micro-electro-mechanical system(MEMS) disk resonators with high yield and good performance.The key breakthrough in the fabrication process is a novel approach to effectively restraining electro-chemical corrosion of polycrystalline silicon(polysilicon) electrically coupled with noble metals of MEMS devices by hydrofluoric acid(HF)-based solutions.In addition,a measurement architecture based on a differential readout topology is demonstrated.The differential circuit proposed here can effectively suppress noise and feed-through current by common-mode rejection of the differential amplifier.This differential amplifier circuit configuration is also used to build up a notch filter.The preliminary result about the temperature dependence of the resonance frequency is discussed,and the device failure is analysed.     

Optoelectronic-VLSI packaging with polarization-selective computer-generated holograms

We present what is believed to be the first packaged module incorporating polarization-based beam-forming optics integrated with an optoelectronic-VLSI device. The chip has multiple quantum-well modulators and detectors that are flip-chip bonded onto a silicon CMOS integrated circuit. In the assembled module a polarization-selective computer-generated hologram converts linearly polarized light into a two-dimensional spot array to illuminate the output modulators. The lenslets do not interfere with the input data or the reflected output, which is orthogonally polarized. We demonstrate a 9x10 modulator array, showing good spot-intensity uniformity and registration with modulators.     

High-density wavelength switching obtained from a tunable multisection laser diode

We describe a method based on multistability in wavelength for obtaining high-density wavelength switching for application to signal routing. The method relies on the use of a 1550-nm wavelength-tunable multielectrode laser diode that is fed back electrically. The system operates as a multistable device that exhibits multiple steady states in wavelength. The device can be used to convert time-multiplexed packets into wavelength-multiplexed signals.     

Fully electrical read-write device out of a ferromagnetic semiconductor

We report the realization of a read-write device out of the ferromagnetic semiconductor (Ga,Mn)As as the first step to a fundamentally new information processing paradigm. Writing the magnetic state is achieved by current-induced switching and readout of the state is done by the means of the tunneling anisotropic magnetoresistance effect. This 1?bit demonstrator device can be used to design an electrically programmable memory and logic device.