共查询到20条相似文献,搜索用时 46 毫秒
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本文提供了用白光信息处理技术作褪色透明彩色照片彩色复原的原理和实验,其中之一是由空间编码和彩色滤波两步骤完成的,即将待处理的透明彩色片用空间编码技术编制在一张黑白感光底片上,在白光光学处理系统的傅里叶平面中对这编码的黑白片的频谱进行彩色滤波,最后在系统的输出平面给出彩色增强或复原的图象,另一种是用白光处理技术作褪色透明彩色片的彩色复原实时处理,它可供及时的直接观察并且有操作简便,成本经济和能灵活多用的特点,这两种技术为彩色图象的彩色增强和复原提供了新方法。
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A polychromatic correlation detection technique by complex spatial filtering is presented. This technique utilizes a diffraction grating and three co-lineared (red, green, and blue) coherent sources. The technique of complex spatial filter synthesis for the polychromatic corelation detection is demonstrated. This technique offers true color correlation detection which is very suitable for color signal recognition and identification. The correlation diffraction efficiency with this technique is generally higher than that of the wavelength-multiplexed technique. Several interesting experimental demonstrations of this color signal correlation detection scheme are provided. Finally we note that this color signal detection technique is a simple and versatile processing technique which has broad range of applications of complex color signal detection, recognition and identification. 相似文献
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In interferogram or fringe pattern analysis, a technique capable of automatically analyzing interferograms that contain complex fringes and high-level noise as well as defects is highly demanded. In this paper, a hybrid technique combining the concepts of the two-dimensional continuous wavelet transform technique and the phase-shifting technique is proposed. The novel technique takes the advantages of the two existing techniques, and has the ability to accurately and automatically analyze multiple phase-shifted complex interferograms involving noise and defects. The validity of the technique is demonstrated by both computer simulation and real experiment. 相似文献
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In this paper, a novel greyscale image coding technique based on vector quantization (VQ) is proposed. In VQ, the reconstructed
image quality is restricted by the codebook used in the image encoding/decoding procedures. To provide a better image quality
using a fixed-sized codebook, the codebook expansion technique is introduced in the proposed technique. In addition, the block
prediction technique and the relatively address technique are employed to cut down the required storage cost of the compressed
codes. From the results, it is shown that the proposed technique adaptively provides better image quality at low bit rates
than VQ. 相似文献
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This paper describes a laser optical technique for the detection of in-plane (IP) motion of ultrasonic waves propagating in solids. This interference-based laser optical technique includes a tiny square indentation with a width of about 30 microm on the sample surface and a relatively simple optical arrangement. The current technique is applied for the detection of in-plane motions of Lamb waves propagating in a thin brass plate. Measurement of S(0) mode dominated by in-plane motion in the low fd (frequency times thickness) regime is successfully demonstrated with the current technique. The newly proposed non-contact technique provides an alternative other than the heterodyne and Fabry-Perot techniques for the detection of IP motions with a relatively simple optical arrangement. This technique is not readily applicable to general NDE applications, where a position scan or an arbitrary selection of inspection location is needed. However, this technique can be useful in the areas such as fixed-position ultrasound monitoring or laboratory research activities involving optical detection of IP motion. 相似文献
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脉冲序列控制(PT)是一种离散的非线性开关变换器控制方法,具有瞬态响应快、无需补偿网络、控制电路实现简单等优点.根据控制脉冲的产生方式不同,脉冲序列控制可分为电压型脉冲序列控制(voltage-mode PT,VM-PT)和电流型脉冲序列控制(current-mode PT,CM-PT).研究表明,工作于电感电流连续导电模式(continuous conduction mode,CCM)与工作于电感电流断续导电模式(discontinuous conduction mode)的VM-PT控制开关变换器的工作特性存在明显差别,VM-PT控制CCM开关变换器存在的低频振荡现象严重影响了其稳态及瞬态性能.目前,对CM-PT控制CCM开关变换器的工作特性还未见相关报道.研究了CM-PT控制CCM开关变换器的工作特性,对其控制参数以及稳定工作域进行了分析.分析结果表明,通过参数的合理设计,虽然可以避免低频振荡现象的发生以及开关管不能正常关断的问题,但存在变换器功率范围窄的缺点.最后针对这一缺点提出了一种改进的控制方法. 相似文献
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The double-random phase-encoding (DRPE) technique is a typical optical image encryption technique, which can also be used for image hiding. Usually, the secret image is encrypted with the DRPE technique and the encoded image is hidden into the host image via superimposition to obtain the stego-image. The attack technique on the DRPE-based image hiding method was proposed in this paper. Firstly, a randomly selected superimposition coefficient was used to approximate the original superimposition coefficient to extract the hidden encoded images from the stego-images approximately. Then, the chosen-plaintext attack technique on the DRPE-based optical image encryption technique was applied to recover the random phase masks used in the DRPE technique. The theoretical analysis indicated that, without considering the computational error, the recovered secret image via the proposed attack technique is identical to the original one. Even considering the computational error, it is identical to the secret image recovered with the original DRPE-based image hiding method, which demonstrates that the attack on the DRPE-based image hiding method is successfully achieved. The numerical simulation results demonstrated the correctness of the theoretical analysis. 相似文献
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Jegathisvaran Balakrishnan Bernd M. Fischer Derek Abbott 《Optics Communications》2010,283(10):2301-2307
Double-modulated terahertz differential time-domain spectroscopy (double-modulated THz-DTDS), is a technique that is based on dithering the sample under test. In this paper, we report a measurement technique based on mounting the sample on a spinning wheel, in order to overcome fundamental limitations imposed by linear dithering. We demonstrate a proof-of-principle showing that noise decreases as a function of the spinning wheel modulation frequency. This technique does not suffer the mechanical noise limitation of traditional linear dithering and thus opens up future scope for further noise reduction via hardware advances in the modulation frequency of the wheel. The spinning wheel technique enables a rapid succession of measurements between the reference and sample signals with a single mechanical delay scan. As a result, an improvement in measurement time by at least a factor of two, as compared to the conventional THz-TDS measurement technique is observed. The spinning wheel technique is experimentally verified by measuring the dielectric properties of a thick polymer material. 相似文献
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To remove the scattering effect of the disturbing sound on the target source when implementing nearfield acoustic holography in a non-free field, a free field recovery technique based on the spherical wave superposition method is proposed. In the method, the sound field separation technique based on the spherical wave superposition method is first used to separate the incoming and outgoing fields, and a further step for separating the radiated and scattered fields is performed by utilizing the surface admittance of the target source as the boundary condition. The technique makes it possible to correctly identify noise sources in a non-free sound field. The basic principle of the technique is described firstly, a method for choosing the optimal number of spherical wave expansion terms is given, and two numerical simulations are used to demonstrate the validity of this technique. It is shown that, for the lower frequency, the scattering effect can be neglected, and the radiated field of the target source can be obtained by the sound field separation technique, however, as the increasing of the frequency, the scattering effect cannot be neglected, and the free field recovery technique has to be used to obtain the radiated field of the target source. 相似文献
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光谱分析技术在作物生长信息检测中的应用研究进展 总被引:6,自引:1,他引:5
获取作物的相关生长信息可以预测作物的生长和健康状态,是实现作物生产管理智能化的基础。植物的生长信息获取技术主要包括利用其电学特性、光学特性和机器视觉技术等,随着光谱技术的发展,近红外光谱技术、多光谱技术和高光谱技术在作物生长信息的获取应用上开始大量应用,并显示了其分析速度快、效率高、成本低、无需制备样品等优点,已成为一种快速、无损的现代分析技术。文章介绍了国内外运用光谱分析技术在作物生长信息获取上的研究情况,并分析了该技术应用于作物生长信息获取时尚存在的问题和今后的研究方向,提出了进行作物生长实时、智能化管理的必要性,需要加快研制相关的光谱自动分析设备,提高作物生长信息获取的速度,最后指出了结合机器视觉技术、红外成像技术、光谱分析技术等多种技术进行作物生长多种信息获取是未来发展的趋势。 相似文献
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We demonstrate a high-resolution technique to measure the optical magnitude and phase responses of fiber gratings. The technique employs single-sideband modulation of an optical source and has spectral resolution in the hertz regime. The technique is demonstrated by measurement of the phase ripples of unapodized and apodized chirped gratings as well as the transmission spectrum of a pi-phase-shifted grating. Although it is demonstrated on fiber gratings, the technique is applicable to any optical device. 相似文献
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在法庭科学领域中,由于案件现场提取到的物证通常是极微量的,另外样品形态各异、成分复杂,常规红外光谱分析技术常常无法达到检测要求。显微红外技术是基于傅里叶变换红外光谱技术与显微镜技术的结合发展起来的。与常规红外光谱技术相比,显微红外技术具有检测灵敏度高、微区分析和无损检测等优点,测试时几乎不引入外部干扰,卓有成效地解决了法庭科学领域中微量物证鉴定的难题,可以满足微量物证必须保留以用于法庭作证的特殊需要。通过本实验中心测试的真实案例分析,详细阐述了显微红外技术在法庭科学领域中微量物证鉴定方面的优势。采用显微红外技术,本文分别对油漆物证、塑料物证、橡胶物证、纤维物证、药物和毒物物证进行了红外光谱振动特征的比对分析,为各类刑事案件和交通肇事案件的定性提供有力的谱学依据。实验结果表明,显微红外技术具有常规红外测试技术无法比拟的优势,是法庭科学领域中微量物证鉴定的有效手段。 相似文献
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《Journal of sound and vibration》2006,289(1-2):130-147
As a basic study for developing an identification technique for boundary conditions of machines and structures, a new technique for a circular plate is proposed. This technique has features that do not require data measured on the boundary and is applicable to nonlinear boundary conditions. In the proposed technique, the boundary is modelled by springs and dampers as well as effective mass and moment of inertia. Then their characteristics are determined by using the analytical solution together with the experimental data. Since the technique is based on the analytical solution, it is applicable to any structure, provided that its analytical solution can be derived. Numerical simulation is conducted to show that the procedure determines the boundary conditions accurately. 相似文献
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Multi-objective strategy to optimize dithering technique for high-quality three-dimensional shape measurement
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《中国物理 B》2019,(10)
Dithering optimization techniques can be divided into the phase-optimized technique and the intensity-optimized technique. The problem with the former is the poor sensitivity to various defocusing amounts, and the problem with the latter is that it cannot enhance phase quality directly nor efficiently. In this paper, we present a multi-objective optimization framework for three-dimensional(3D) measurement by utilizing binary defocusing technique. Moreover, a binary patch optimization technique is used to solve the time-consuming issue of genetic algorithm. It is demonstrated that the presented technique consistently obtains significant phase performance improvement under various defocusing amounts. 相似文献
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激光诱导击穿光谱技术的研究与应用新进展 总被引:2,自引:0,他引:2
激光诱导击穿光谱技术(LIBS)是一种近年来随着激光技术和光谱检测技术的发展而兴起的对元素定性和定量分析的光谱技术。详细介绍了LIBS技术最新的研究发展情况,以及在冶金、环境污染检测、生物医学、植物学、空间探索等领域的最新应用进展。 相似文献
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We propose a new technique for an interconversion between a three dimensional (3-D) spatial signal and a temporal signal. It is realized by combination of a holographic technique, a 2-D spatial filtering technique and a time-space conversion technique. Using this method, we can physically utilize the multiplicity between a temporal domain parameter and all of the spatial domain parameters of light. To demonstrate the proposed technique, we achieved experimentally conversion from different three point light sources as 3-D spatial signals into a temporal signal and vice versa. 相似文献