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充分利用光刻系统中光源的部分相干特性和一维图形的特性,提出了针对一维版图的快速平面光刻仿真算法。该方法由一维基元图形查表法、最小查找表及其边缘延伸和无切割的大面积版图仿真组成。仿真结果表明,在保证极高准确性的基础上,相比于传统的快速仿真方法,该方法将查找表的建立时间缩短了95%以上、基本图形的仿真速度提高了48%左右、大面积版图的仿真速度提高了70%以上。 相似文献
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为了降低空心脉冲发电机的能量损耗与励磁绕组发热,提出了一种具有剩余磁能回收功能的脉冲发电机励磁电路。通过在电容支路设置调节电感,使放电完成后的电容电压反向,迫使晶闸管与二极管关断,以切换电流流通路径来实现剩余励磁能量到电容器中的转移。该电路使用晶闸管作为主开关,电流关断能力强的特点使其在大功率脉冲发电机的应用中具有一定优势。对提出的励磁能量回收电路的工作过程进行了介绍,仿真分析了剩余能量回收对励磁绕组能量损耗和脉冲发电机发热的影响,并对该电路拓扑的工作原理进行了实验验证。结果表明:该电路可以迅速回收励磁绕组中的剩余能量,缩短励磁电流续流时间,减少励磁损耗与能量损耗。仿真与实验结果反映的规律与电路原理一致,表明了该电路方法的可行性。 相似文献
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视频字符的显示原理是将字符点阵信号与原始视频信号叠加。在视频图像上实时叠加字符,可以及时将关键的数据和工作状态显示出来,既醒目又直观,因此视频字符显示技术得到了广泛的应用。文中介绍一种视频字符显示方法,该方法利用CPLD(Complex Programmable Logic Device,复杂可编程逻辑器件)与单片机实现视频字符的显示功能,即通过监视器实时显示所需观测的字符信息。实验证明用这种方法设计的电路性能稳定且易于维护。 相似文献
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针对某型航管应答机串行控制接口电气特性、时序关系和数据定义的特殊要求,设计了以CPLD最小应用系统为核心,并扩展RS-232和三线控制接口电平转换的硬件电路,编制了基于计数器触发的输出接口信号状态转换程序,实现了RS-232接口与航管应答机三线串行控制接口信号的转换,较好的解决了航管应答机自动测试系统中控制接口电路的适配问题。该控制接口通过扩展输入和显示模块,可独立实现对航管应答机的功能控制和状态指示;通过改变计数器数值与输出接口信号状态转换之间的关系,可方便的调整三线串行接口信号的电平、时序、占空比等参数。应用结果表明,该控制接口具有性能稳定、使用方便、扩展性强等特点。 相似文献
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在无衍射光滤波法显微成像中,实际成像光斑的能量分布对成像质量影响较大,故需要对微弱成像光斑的能量分布进行准确测量。实验中采用扫描法测量光斑的能量分布,通过柔性铰链机构带动微米级小孔以很小的步距对成像微光斑进行精确的二维扫描,用光电倍增管接收扫描采样的微弱光信号,再以低噪声的I/V转换电路和电压放大电路处理取样信号后送入计算机处理,就可准确地复原光斑的能量分布。通过制作的测量装置对实际微弱光斑测量后,以三维能量分布图的形式给出了测量结果。该方法实现了对能量分布不规则、尺寸较小、能量密度小的光斑能量分布的测量,并且有很高的测量精度。 相似文献
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P. Dorenbos 《Journal of luminescence》2002,99(3):283-299
Information on the energy of 5d-levels of Ce3+ ions in aluminates and “simple” oxides has been collected. The crystal field splitting of the 5d-levels is interpreted in terms of the type and size of anion polyhedron coordinating the Ce3+ ion. The centroid (barycenter) shift of the 5d-configuration is analyzed by a ligand polarization model providing values for the spectroscopic polarizability αsp of the anion ligands. The data provide evidence that the centroid shift behaves independently from the crystal field splitting. By combining centroid shift and crystal field splitting, the “spectroscopic” redshift of the first electric dipole-allowed fd transition of Ce3+-doped in the compounds will be interpreted. The large crystal field splitting in garnet compounds and the small splitting in perovskite compounds will be discussed. 相似文献
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为了评估静态随机访问存储器(SRAM)型现场可编程门阵列(FPGA)器件的单粒子效应,寻求单粒子翻转敏感部位,以XCV300PQ240为实验样品,利用重离子辐照装置详细测试了该器件的静态翻转截面,并根据配置存储单元用途的不同,对翻转数据进行了分类。结果表明:SRAM型FPGA的内部存储单元对单粒子翻转效应十分敏感;配置存储器翻转主要由查找表(LUT)及互连线资控制位造成,这两者的翻转占总翻转数的97.46%;配置存储器中各类资源的单粒子翻转(SEU)敏感性并不一致,输入输出端口(IOB)控制位和LUT的单粒子翻转的敏感性远高于其它几类资源,但LUT在配置存储器中占有很大比例,在加固时应予以重点考虑。 相似文献
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PET用新型深度编码探测器设计 总被引:1,自引:0,他引:1
平行性问题或作用深度问题影响着正电子放射层析系统(PET)的成象分辨率。本文提出和评价了一种二阶深度编码探测器,这个探测器是由两层LSO晶体和位置灵敏型光电倍增管(PS-PMT)组成,上层的晶体相对于下层的晶体的位置在X和Y方向上都有半个晶体阵列单元的错位,因为每个晶体的输出光的重心位置分布在PS-PMT上不同的位置,所以通过计算其重心位置就可在象平面上区别开每个晶体。根据PET系统的应用要求,我们验证了探测器的性能。伽马射线垂直入射时,上层晶体阵列的固有空间分辨率为1.15mmFWHM,下层晶体列阵为1.34mm FWHM.钠伽马辐射源的511keV能量峰处的平均能量分辨率对于下层晶体为19.7%,上层为23.6%.通过类似的技术亦可实现3阶、4阶深度编码探测器。 相似文献
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Direct RF sampling receiver – a fully digital receiver architecture – undoubtedly becomes a favored choice for HF/VHF as this approach inherently bypasses the legacy nonlinearities caused by analog components. In DRF-RF and wideband multichannel in general, LNA is still an indispensable component to ensure the receiver’s sensitivity. However, with the presence of multiple channels, the total RF power often surpasses the linear threshold that LNA and the amplified signal become severely distorted. This paper proposed a method for mitigating the LNA distortion using the look-up table (LUT) approach. Specifically, our receiver is designed with two modes of operation. In training mode, a built-in signal circuit generates a training signal for extracting the LNA characteristic and eventually reconstructs the inverse LNA nonlinear model in the form of a LUT memory. During the receiving mode, a linearization circuit reverses the distortion impact by matching the RF power level with the inverse nonlinear model pre-stored in the LUT. The effectiveness of the proposed distortion compensation method first is evaluated by a MATLAB simulation with a multi-channel DRF-RF model. The simulation results show that the proposed approach significantly improved the SNDR for the channel of interest. Furthermore, the model has been practically verified, where the actual distorted signals are sampled from a commercial LNA (ZFL-500LN+) by a customized FPGA board. Results from measurements show an improvement of 7 dB for SNDR and 27% for EVM in a strong distortion scenario of QPSK modulation signal. 相似文献
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Anthony JM Garrett 《Contemporary Physics》2013,54(2):163-165
The dynamic electronic structure of atoms and molecules can be directly observed by means of the (e, 2e) reaction, which measures the distribution of energies and momenta of two electrons in coincidence after a knockout reaction initiated by an electron beam of known momentum incident on a molecular gas target. The molecular state for each event is identified by the electron separation energy. The recoil momentum for each event is known from the difference of measured initial and final momenta. It has been verified that values of this momentum are equal under suitable conditions to the momentum of the electron in the target immediately before knockout. Thus the spherically-averaged electron momentum distribution for each molecular orbital is measured. This is directly related to molecular orbitals calculated by the methods of quantum chemistry. Properties obtained by this method for different types of molecules are discussed. 相似文献
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A possible way to estimate the reaction plane of the ion-ion collision is to measure the sideward deflection of the spectator
neutrons. In the ALICE experiment this kind of measurement can be performed by means of the two neutron zero degree calorimeters
(ZN), which are located at opposite sides with respect to the beam intersection point (IP). In fact the ZN calorimeters, thanks
to their segmentation in four towers, are position sensitive devices. Concerning their localizing capability, a spatial resolution
of ∼3 mm has been measured for a 100 GeV/c hadron beam. This performance will be used to reconstruct, event by event, the
centroid coordinate of the spectator neutron spot on the ZN front-face, which is sensitive to the directed flow (“bounce off”)
of spectator neutrons. The measurement of the centroid will therefore allow to reconstruct the 1st-order event plane azimuth.
A simulation is performed in order to estimate the dependence of the event plane resolution on the magnitude of the directed
flow v1 of the spectator neutrons and on the neutron multiplicity (event centrality). In particular, it will be shown that the event
plane resolution is not dominated by the smearing on the centroid measurement, but by the smearing due to the transverse lead
beam divergence at the IP. Finally a possible tool to select events with small lead beam divergence at IP is discussed, using
the information coming from both the ZN calorimeters. 相似文献
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Isochromatic demodulation in digital photoelasticity using RGB calibration is a two step process. The first step involves the construction of a look-up table (LUT) from a calibration experiment. In the second step, isochromatic data is demodulated by matching the colors of an analysis image with the colors existing in the LUT. As actual test and calibration experiment tint conditions vary due to different sources, color adaptation techniques for modifying an existing primary LUT are employed. However, the primary LUT is still generated from bending experiments. In this paper, RGB demodulation based on a theoretically constructed LUT has been attempted to exploit the advantages of color adaptation schemes. Thereby, the experimental mode of LUT generation and some uncertainties therein can be minimized. Additionally, a new color adaptation algorithm is proposed using quadratic Lagrangian interpolation polynomials, which is numerically better than the two-point linear interpolations available in the literature. The new calibration and color adaptation schemes are validated and applied to demodulate fringe orders in live models and stress frozen slices. 相似文献
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Shihong Zhou 《Journal of luminescence》2006,118(2):179-185
Bulk and nanoscale powders of YAG:Re (Re=Ce, Pr, Tb) were synthesized by solid-state and sol-gel method. The changes of spectra and energy level were studied. Compared with the bulk YAG:Re (Re=Ce, Pr, Tb) crystals, the lattice parameter of YAG:Re (Re=Ce, Pr, Tb) nanocrystals decreases. It is also found that the excitation peaks of 5d energy levels shift in nanocrystals. The physical reason for spectral and energy level changes is a comprehensive result from the shift of energy centroid of the 5d orbit, the Coulomb interaction between 4f and 5d electrons and the crystal field splitting of the 5d energy level. 相似文献
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PET image reconstruction with a system matrix containing point spread function derived from single photon incidence response 下载免费PDF全文
A point spread function(PSF)for the blurring component in positron emission tomography(PET)is studied.The PSF matrix is derived from the single photon incidence response function.A statistical iterative reconstruction(IR)method based on the system matrix containing the PSF is developed.More specifically,the gamma photon incidence upon a crystal array is simulated by Monte Carlo(MC)simulation,and then the single photon incidence response functions are calculated.Subsequently,the single photon incidence response functions are used to compute the coincidence blurring factor according to the physical process of PET coincidence detection.Through weighting the ordinary system matrix response by the coincidence blurring factors,the IR system matrix containing the PSF is finally established.By using this system matrix,the image is reconstructed by an ordered subset expectation maximization(OSEM)algorithm.The experimental results show that the proposed system matrix can substantially improve the image radial resolution,contrast,and noise property.Furthermore,the simulated single gamma-ray incidence response function depends only on the crystal configuration,so the method could be extended to any PET scanner with the same detector crystal configuration. 相似文献