多线切割张力控制系统研究

对多线切割张力控制技术进行论述,分析了多线切割机中张力控制技术的特点,在此基础上,提出了一种多线张力的控制方法。该方法基于对张力信号变化的实时检测,将检测张力的变化转变为电机扭矩的变化,通过控制扭矩电机的扭矩来调整切割线张力,由控制软件来实现对切割线张力的检测、分析与控制。控制精度高,成功实现了在双主辊系统驱动下的多线切割机张力控制。实验证明,该方法可靠、稳定,能很好地检测并控制多线切割系统张力精度。     

基于增加动量项的神经网络左逆张力辨识策略

以两电机张力控制系统为研究对象,为实现两电机张力控制系统的高性能控制及无传感器运行,张力的准确检测是其中的关键。文中提出了基于人工神经网络和左逆系统理论的两电机张力系统的一个新的识别方法。考虑到系统的参数是时变的和张力易受负载变化影响。神经网络左逆辨识被用在该系统中中,这是很容易实现的左逆模型。针对运用中传统BP网络的收敛速度慢,易陷入极小值的缺点,提出了增加动量项的改进神经网络左逆辨识策略,通过仿真模型对在负载扰动下两电机的张力进行辨识。仿真结果表明,辨识准确,策略可行。     

船舶电力系统断电预防控制的研究

针对船舶电力系统的短路,接地故障、过载、有功或无功负载共享等系统故障引起的全网断电问题,利用一种新的基于观测器的快速减负荷系统,设计了一种负载转矩限制控制器。利用船舶推进器模型建立被控对象的数学模型;引入全波傅式测频算法,并实时的测得电网的频率;最后针对船舶推进器转矩控制进行仿真和分析。仿真结果显示,当观测器测得的频率低于某一限定的频率时,负载转矩限制控制器快速的减少推进器的转矩。     

基于特征线方法的无源传输线模型

基于特征线方法的传输线模型只能保证模型的因果性,但是不能保证模型的无源性。针对上述问题,该文提出了一种无源性补偿方法来实现传输线宏模型的无源性。该方法扩展了现有的用于集总模型的无源性补偿算法,以等式约束的二次规划方法为基础,采用拉格朗日乘数法进行优化。数值例子表明该方法在有限的仿真时间内产生了精确的无源宏模型。     

模糊自适应PID控制的恒张力收卷系统研究

针对真空镀膜机收卷张力控制具有多变量、时滞性、非线性且系统难以建立精确模型的问题,为了降低张力波动,提高收卷张力精度、测试的稳定性,建立收卷恒张力模糊自适应PID系统结构模型。运用模糊推理对参数进行自整定的方法设计了一种二维自适应模糊PID控制器。应用Matlab/Simulink模块实现系统仿真,仿真结果表明模糊自适应PID算法相比常规PID控制具有较强的鲁棒性,良好的动态、静态稳定性。把该控制器运用到现场测试中,测试结果表明该控制器有效地减少了张力波动,提高了镀膜质量。     

张力控制系统MTALAB仿真研究

为了研究MATLAB的仿真功能,文章建立了一个关于印刷包装方面的张力模型,首先利用了MATLAB强大的仿真建模能力,设计出一个张力的仿真模型,并且在此基础上用了PID控制,最后建立了一个卷筒织印刷机张力控制系统的仿真模型。相关的多个张力干扰因素也做了对比研究仿真,最终在不同干扰占主导因素时都得出了相应的的张力控制系统仿真数据结果。     

一种适用于快衰落信道的ICI抑制方案

针对高速移动环境下多普勒频偏造成信道的快衰落和正交频分复用(OFDM)系统中子载波间干扰(ICI)的问题,提出了一种适合快衰落环境的OFDM系统子载波间干扰抑制算法。此算法用线性变化模型来近似一个OFDM符号周期内的信道冲激响应,并以此为基础采用迭代MMSE均衡方法抑制载波间干扰。分析和仿真结果表明,此方法能有效地保证载波间的正交性,从而改善了OFDM系统的误码率(BER)性能。     

基于子空间比较的宽带信号下辐射源 功放"指纹"分类方法

 本文提出了一种基于功放宽带Volterra级数模型的辐射源"指纹"分类方法,以用于电子侦察对宽带信号源的特定辐射源识别.针对传统Volterra系统MIMO建模方法的适应性不足,以及系统辨识过程存在维数爆炸问题,本文推导出一种对编码类和调频类宽带信号都适用的MIMO建模方法,然后直接基于参数子空间比较来实现功放的指纹分类.对本方法的"独立性"和"可测性"进行了分析.数值仿真实验对子空间比较方法进行了验证.     

一种新型的OFDMA比例公平资源分配算法

针对已有算法对系统容量和高公平性兼顾较差的情况,提出了一种满足公平性的系统容量最大化资源分配算法。在子载波分配中通过建立信道效率控制模型,给当前用户分配信道效率最高的子载波,将信道增益低于门限值的子载波重新分配,改进了最大化最小(max-min)用户速率模型。在功率分配中将系统模型转化成用注水线表示的数学模型,首先求解各用户的注水线,再求解各用户的功率分配,保证了用户间比例公平性。两种信噪比情形下的仿真和分析表明,整个方案计算复杂度稍低,系统容量获得较大提升,并且用户间的公平性始终为1。     

永磁同步直线电机模型参考自适应动子质量辨识

本文首先建立了永磁同步直线伺服系统的数学模型,并在MATLAB环境下搭建了相应结构图,在此基础上针对动子质量变化扰动,采用离散模型参考自适应方法实时估计系统动子质量的变化,用辨识得到的动子质量当前值依照规则对速度控制器各参数进行整定,使伺服系统在动子质量发生变化时仍具有良好的动静态性能。仿真结果表明采用该方案辨识参数收敛速度快,使伺服系统具有实时性好,能够无超调的跟踪输入等优点,系统的精度也有了很大的提高。     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-