离散旋转抖动的空间点统计分析

离散旋转抖动是一种对Bayer离散抖动矩阵进行离散的点对点旋转的抖动技术。它所生成的半色调模型减少了Bayer半色调模型中水平和垂直方向上的干涉条纹。而且 ,由于离散旋转抖动在中等灰度级处形成族点 ,它在点增益现象严重的打印得到了更好的色调再生。在本文中 ,引进了一种新的分析方法———空间点统计方法来代替传统的频谱分析 。

离散旋转对称三角法及其应用

针对传统激光三角法在测量孔、台阶等表面丌连续处易导致精度下降或无法测量。这一问题,本文提出了离散式旋转对称三角法。首先,基于Scheimpflug条件提出了系统约束模型,建立了光斑点不高度映射模型;然后,对系统在不同深度情况下的成像特性进行了仿真,分析研究了系统在不同物体表面、倾斜和遮挡情况下的性能,验证了本方法在克服方向依赖性上的优势;最后,构建了原型系统,在机床上分别进行了单点测量实验和阶梯面测量实验。实验表明,本文系统具有0.027mm的测量精度,并且不受阶跃表面遮挡的影响,有效测量了阶梯角落区域,相对于接触式测量,具有更广泛的测量区域。

可控旋转离散杆空间运动分析

基于理想爆轰假设和刚体运动学原理.建立了可控旋转离散杆空间运动模型。对不同尺寸、斜角的杆条进行空间运动状态分析.并和试验结果进行比较.结果表明该模型能较好地描述可控旋转离散杆空间运动状态.为可控旋转离散杆战斗部的设计提供参考。

旋转式离散杆战斗部对反舰导弹的毁伤数值模拟研究

针对细长杆状目标，以亚音速反舰导弹为典型目标，进行了目标特性分析和易损性分析，得出了这类目标的有效毁伤机理。在小脱靶量情况下，提出利用双束旋转式离散杆战斗部对这类目标实施切割毁伤，使其在空中解体或作用失效。建立了双束旋转式离散杆战斗部攻击亚音速反舰导弹的弹目交会数学模型，计算了弹目交会参数。根据交会参数，利用LS—DYNA三维动力有限元程序对杆条打击到发动机舱段上进行了三维数值模拟分析，为反舰导弹毁伤评估提供参考。

旋转式离散杆战斗部的杆条旋转规律试验研究

先利用多重纸靶观察旋转式离散杆战斗部的杆条飞行姿态变化，再由“直靶法”获得杆条旋转角度与飞行距离之间的关系，结合靶网测速取得了杆条旋转角速度的定量描述。相同状态试验件的静爆试验结果表明：由“直靶法”得到的旋转角度和飞行距离之间的关系式计算出的旋转特征距离与试验结果基本一致，可为旋转特征距离设计提供参考。

一种可随意调节的旋转对称离散坐标格式

提出了一种既可随意布置离散方向 ,又能满足 90°旋转对称要求的新的离散坐标格式 ,其基本思路是 :先将每个卦限中的单位球表面划分为三个相等的部分 ,再在其中一部分内根据需要任意地布置离散方向 ,然后根据对称性得到其他两部分内的设置 .

利用六边形网格实现半色调抖动技术的研究

针对传统的半色调抖动技术存在水平和竖直方向上的人工痕迹以及网格化轮廓等缺陷,提出了一种新颖的基于六边形网格的抖动矩阵构造方法。首先,将原驱散式Bayer抖动矩阵进行元素重组和离散旋转以构造一个更为合理的抖动矩阵,然后按照新矩阵对图像进行半色调化处理。实验结果表明,该抖动算法不但能够显著消除传统抖动技术所存在的不利因素,而且比其他同类的改进抖动算法具有更强的色调再现能力和细节表现力。

DSL中基于MTL的共模传输

该文提出一种基于MTL理论进行DSL共模传输的建模思想,把传统的矢量传输技术通过在发送端和接收端进行阻抗匹配应用于实际的电缆包的信道建模当中,从而实现了基于传输共模信号的电缆包MIMO模型,解决了在非屏蔽状态下双绞线如何进行共模传输的问题,基于此模型DSL中的数据传输速率有可能有进一步的提高。实验仿真表明基于该理论形成的差模信道非常接近实测数据,此外线与线之间的电磁干扰非常强。

Distribution patterns of rock mass displacement in deeply buried areas induced by active fault creep slip at engineering scale

Active fault creep slip induces deformation of rock mass buried deeply in fault zones that significantly affect the operational safety of long linear projects passing through it.Displacement distribution patterns of rock masses in active fault zones which have been investigated previously are the key design basis for such projects.Therefore,a discrete element numerical model with different fault types,slip time,dip angles,and complex geological features was established,and then the creep slip for normal,reverse,and strike-slip faults were simulated to analyze the displacement distribution in the fault rock mass.A disk rotation test system and the corresponding laboratory test method were developed for simulating rock mass displacement induced by creep slippage of faults.A series of rotation tests for softand hard-layered specimens under combined compression and torsional stress were conducted to verify the numerical results and analyze the factors influencing the displacement distribution.An S-shaped displacement distribution independent of fault dip angle was identified corresponding to reverse,normal,and strike-slip faults.The results indicated that the higher the degree of horizontal extrusion,the softer the rock mass at the fault core,and the higher the degree of displacement concentration in the fault core;about 70%of the creep slip displacement occurs within this zone under 100 years of creep slippage.

Effect of moving baffle on average velocity and mixing of binary particles in rotating drums

Adding a moving baffle to the drum is a new way to enhance the motion and mixing of particles in rotating drums.To obtain its influence on binary particles,horizontal rotating drums provided with a moving baffle were investigated by discrete element method(DEM).AtΩ=15 r/min,increasing the length of moving baffle can increase the fluctuation amplitude of average particle velocity.AtΩ=60 r/min,the influence of the moving baffle on the average velocity fluctuation tends to be more random.At both rotational speeds,the moving baffle causes the average particle velocity to fluctuate more sharply.The moving baffle can enhance particle mixing.AtΩ=15 r/min,the moving baffle with length ofδ=1/3 can best enhance particle mixing.However,atΩ=60 r/min,only the moving baffle with a specific length(δ=1/4)can enhance mixing.This basic research has a positive reference value for the application of the moving baffle in industry.

Implementation of Quantum Fourier Transform and Its Applications via Quantum-Dot Spins and Microcavity

A scheme for implementing discrete quantum Fourier transform is proposed via quantum dots embedded in a microcavity, and then some of its applications are investigated, i.e., Deutsch 3ozsa. algorithm and Shor＇s quantum factoring. In particular, the detailed process of implementing one^qubit Deutsch Jozsa algorithm and the factorization of N = 15 are given. The microcavity mode is only virtually excited in the whole interaction, so the effective decoherent has slight effect on the current scheme. These schemes would be an important step to fabricate a solid quantum computer.

Different Kinds of Discrete Breathers in Three Types of One-Dimensional Models

The dynamics of different kinds of discrete breathers in three types of one-dimensionai monatomic chains with on-site and inter-site potentiais are investigated. The existence and evolution of symmetric breather, antisymmetric breather, and multibreather in one-dimensionai models are proved by using rotating wave approximation, local anharmonic approximation, and the numerical method. The linear stability of these breathers is investigated by using Lyapunov stable anaiysis. The localization and stability of breathers in three types of models correlate closely to the system nonlinear parameter β.

Fault Feature Extraction of Rotating Machinery Based on Wavelet Transformation and Multi-resolution Analysis

This paper expounded in detail the principle of energy spectrum analysis based on discrete wavelet transformation and multiresolution analysis. In the aspect of feature extraction method study, with investigating the feature of impact factor in vibration signals and considering the non-placidity and non-linear of vibration diagnosis signals, the authors import wavelet analysis and fractal theory as the tools of faulty signal feature description. Experimental results proved the validity of this method. To some extent, this method provides a good approach of resolving the wholesome problem of fault feature symptom description.

2D DEM simulation of particle mixing in rotating drum: A parametric study

Mixing behaviors of equal-sized glass beads in a rotating drum were investigated by both DEM simula- tions and experiments. The experiments indicated that higher rotation speed can significantly enhance mixing. The particle profiles predicted by 2D DEM simulation were compared with the experimental results from a quasi-2D drum, showing inconsistency due to reduction of contacts in the single-layer 2D simulation which makes the driving friction weaker than that in the quasi-2D test, better results could be reached by specifying a higher frictional coefficient between the particles and the cylinder wall. In order to explore the influences of physical properties （density, size or friction） on mixing behavior, numerical 2D simulations were carried out systematically, in which one examined specific property being examined was exaggerated while the others were kept the same as that in the control group. The DEM simulations reveal that particle density and size are the dominating factors affecting mixing behaviors, while the effect of frictional coefficient is less significant. However, segregation due to any of the factors can be diminished by specifying a proper particle size distribution （multi-size with lower size ratio）. 2009 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Scattering Characteristics of Liquid Droplets Spun Off from Rotating Disk Edge

Scattering characteristics of liquid droplets spun off from a rotating disk edge are experimentally investigated. In the present research, aluminum disks are utilized and ethanol is employed for liquid. Scattering phenomena of the droplets are captured by the high-speed digital camera. Frequency distribution of the droplet diameter is evaluated from these images and distributions of horizontal flying velocity and angle of the droplets were measured by PTV. Liquid filaments are stretched outward from the stagnant liquid layer by centrifugal force and skew complicatedly by aerodynamic force. Some peaks appear in the distribution of the scattered droplet diameter and they are origi- nated from large terminal droplets and small droplets generated from filamentwise breakup. Most of the scattered droplets fly slightly inside in the tangential direction of the disk edge. The droplets spun off from the thin disk scatter widely compared with that from the thick one.