一种基于小波-Contourlet变换的图像编码算法

根据小波-Contourlet变换对图像分解具有多尺度和多方向性的特点,提出了一种结合小波-Contourlet 变换和集合分裂嵌入块(SPECK)编码的图像压缩算法(CSPECK).小波-Contourlet通过方向滤波器组把小波分解的高频子带进一步分解为多个方向子带,从而可更稀疏地表示图像的边缘和纹理.SPECK算法编码具有复杂度低和编码效率高的优点.实验结果表明,CSPECK算法对纹理丰富的图像有很好的压缩效果,与基于小波-Contourlet 变换的CSPIHT算法相比,峰值信噪比提高了0.2～0.6 dB.     

基于整数小波变换与双阈值交替的遥感图像压缩

提出一种基于双阈值交替的遥感图像编码（DTAC）算法。根据整数小波变换（IWT）分解后不同阈值上的重要系数分布状况，对重要系数相对集中的区间用整数平方代替2的整数幂（IPT）作为量化阈值，在其他阈值区间中仍使用IPT，然后对每个阈值平面上的重要系数采用统一的编码策略。实验表明，新算法具有较低编码复杂度，不仅支持单一码流下从有损到无损的遥感图像编码，而且峰值信噪比（PSNR）高于采用IWT的SPECK编码算法。     

一种基于小波变换的遥测图像编码新方法

为了实现火箭遥测图像的高效处理,优化火箭遥测图像的编码流程,提出了一种基于小波变换的火箭遥测图像编码新方法。在图像小波变换的基础上,以空间方向树为编码单位,采用改进的分层树集合分割(SPIHT)算法实现图像重要小波系数的比特平面编码,并采用联合码率优化截取方法,优先截取和传输重要比特平面的遥测图像数据。通过系统测试,结果表明：与传统的火箭遥测图像编码方法相比,新的遥测图像编码方法具有丢帧率低、重构图像质量好、编码效率高等优点,满足运载火箭遥测图像处理和传输的工程需求。     

一种基于低复杂度嵌入零块编码的遥感图像压缩编码方法

该文针对遥感图像的数据特点,提出了一种新的遥感图像编码方法。它基于一种改进的小波变换嵌入零块编码算法。新算法中改进了零块编码中四叉树分裂算法(quadtree),并设计亍新的链表生成和不重要集合排序策略。通过这些方法的改进,不仅提高了图像编码性能,同时还大大提高了运算效率。实验表明该文阐述的算法具有很低的复杂度和高的压缩率,PSNR和计算速度均超过SPIHT和SPECK。在1bpp下,该文方法的PSNR比SPIHT提高了0.3dB以上,计算速度比SPIHT提高了35％。     

基于人眼视觉特性的ROI渐进编码算法

一般基于感兴趣区域(ROI)的图像编码算法都没有充分考虑人眼视觉特性,在分析了JPEG2000中感兴趣区域编码的优缺点后,利用小波变换的特点并结合人眼视觉的掩蔽效应,提出了一种改进的ROI图像编码算法。首先将图像小波域中的所有低频系数进行移位处理,而对于小波域中的高频系数,仅对其属于ROI区域的系数进行移位处理,再利用等级树集合分割(SPIHT)算法进行编码传输。仿真实验证明了该算法比原有算法的图像主观质量更好。     

整数小波框架下基于阈值分割的静止图像编码

首先,选定分割阈值Th。然后,对大于Th的小波系数采用整数平方阈值进行量化、缩短阈值间的距离,并对阈值平面上的系数采用改进的二进制SPECK编码框架,对小于Th的系数采用2的整数幂作为量化阈值。最后,在每个阈值平面上均采用无乘法的二进制算术编码。通过与嵌入式零树小波(EZW)、SPIHT及SPECK算法的实验结果比较,ETSC算法不仅有较低的计算复杂度,而且提高了整数小波变换(IWT)在低比特率下的编码效率。此外,该算法支持有损和无损解码在单一码流下完成。     

SPECK图像编码的改进算法

为了解决SPECK（Set Partitioning Embedded Block Coder集合分裂嵌入块）算法占用大量存储空间的问题，给出了一种无链表SPECK图像压缩算法LSK。LSK编码算法不需要链表，算法简单编码速度很快，适合硬件实现。改进方法用状态表来代替链表保存编码的码块和信息，状态表中每个小波系数由2个比特来表示。图像数据以z字形扫描后的一维数组形式储存，这种方法计算高效，算法简单。文中小波变换采用9／7提升分解算法，量化为均匀标量量化。实验结果表明，该算法与SPECK相近，比SPIHT效果好。     

基于四叉树分割量化与关联模型的图像编码算法

本文以整型提升小波变换和SPIHT编码算法为基础，提出了一种基于四叉树分割量化与关联模型的新图像编码算法，该算法的基本工作步骤为：(1)对原图像进行整型提升小波变换，以得到不同分辨率不同方向的多个图像子带；(2)对最低频子带进行DPCM编码，对高频子带进行四叉树分割量化编码；(3)采用关联模型完成最后的算术编码。对比实验表明：本文算法在编解码速度、图像复原质量等方面均优于SPIHT等算法。     

基于内存优化的小波零块嵌入图像编码算法

小波嵌入零块编码算法(Set Partitioned Embedded bloCK,SPECK)是一种高效的具有渐进传输特性的图像编码算法,但其在编解码过程中的巨大内存占用致使编解码速度慢且不利于硬件实现.本文提出了一种基于内存优化的小波零块嵌入图像编码算法,采用标志状态图和块深度优先搜索策略完成嵌入编码中的排序和细化过程.两张标志状态图分别标识编解码过程中的重要系数和不重要集合,同时结合块深度优先搜索策略检索块结构中的不重要集合,代替排序和细化过程中的重要系数链表和不重要集合链表,较大地节省了内存占用.实验结果表明,与SPECK算法相比,在保持相当信噪比的情况下,内存占用仅为原来的1/12,与另一种低内存零树编码算法LZC(Listless Zerotree Coding)相比,在内存略有增加的情况下,信噪比至少提高1.1dB,为硬件实现小波零块编码算法探讨了一条有效途径.     

提升小波图像编码技术实验研究

主要对基于邻域预测、基于线性预测和基于双线性预测的提升算法进行了研究,并结合集合分裂零树(SPIHT)算法,对标准图像进行嵌入式编码.实验表明,在同样的比特率和同样分解级数的情况下,对于纹理丰富的图像,基于双线性预测提升的小波图像编码算法,具有更好的图像主客观质量,最差的是基于邻域的预测方法,而线性预测方法则介于两者之间.     

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.     

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.     

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.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

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.