可见光通信中一种大围长可快速编码的QC-LDPC码构造方法

为了改善可见光通信(VLC)系统的性能,针对准循环低密度奇偶校验(QC-LDPC)码码字间最小距离不够大而导致纠错性能下降的问题,提出一种新颖的QC-LDPC码构造方法。该方法将最大公约数(GCD)算法和Lucas序列相结合构造QC-LDPC码的信息位;同时,为了降低编码复杂度,校验位采用了准双对角线的形式,在保证大围长的同时实现QC-LDPC码的快速编码。然后用所提出的构造方法构造了码率为0.5的GL-QC-LDPC(2650,1325)码,并运用所搭建的VLC系统仿真模型进行了仿真性能分析。仿真结果表明,在误码率为10-6时,该GL-QC-LDPC(2650,1325)码与基于阵列码(AC)构造的AC-QC-LDPC(2652,1326)码、直接使用GCD算法与修饰技术构造的GM-QC-LDPC(2650,1325)码,以及基于群可分设计(GDD)的GDD-QC-LDPC(2652,1326)码相比,其净编码增益(NCG)分别提高了0.10,0.14和0.25dB。     

光通信中一种基于有限域的QC-LDPC码构造方法分析

针对光通信系统日益发展的需要,提出了一种的基于有限域准循环低密度奇偶校验(QC-LDPC)码的构造方法.该构造方法简单易行,可以有效避免四环的出现,具有良好的围长特性,同时能够自由地选择码长码率.仿真分析表明:通过该构造方法所构造的码率为93.7％的QC-LDPC(3780,3540)码的纠错性能优于利用随机构造方法所构造的SCG-LDPC (3969,3720)码和已广泛用于ITU-T G.975中的RS(255,239)码和ITU-T G.975.1中的LDPC(32640,30592)码,因而其更适合于光通信系统.     

光通信系统中基于伽罗华域乘群的QC-LDPC码的一种新颖构造方法

基于Galois域GF(q)乘群,提出了一种构造简单且编码容易实现的新颖准循环低密度奇偶校验(QC-LDPC)码构造方法,可灵活地调整码长、码率,且编译码复杂度低。用本文方法构造了适用于光通信系统的非规则QC-LDPC(3843,3603)码,仿真表明,与已广泛用于光通信系统中的经典RS(255,239)码相比,用本文方法构造的码具有更好的纠错性能,且其性能优于用SCG方法构造的LDPC码和规则的QC-LDPC(4221,3956)码,适合用于高速长距离光通信系统。     

光通信中基于有限域加群的一种QC-LDPC码

针对光通信系统传输特性要求的日益提高,基于有限域GF(q)加群提出了一种构造简单且适合光通信系统的新颖准循环低密度奇偶校验(QC-LDPC)码构造方法,该构造方法可灵活的调整码长、码率且其编译码复杂度低。用此方法构造了适用于光通信系统的规则QC-LDPC(4599,4307)码。仿真结果表明,在BER=10-7时且码率均为93.7%的情况下,所构造的QC-LDPC(4599,4307)码的净编码器增益(NCG)比已广泛应用于光通信系统中的经典RS(255,239)码提高了约2.2dB,比用SCG构造方法构造的SCG-LDPC(3969,3720)码和非规则的QC-LDPC(3843,3603)码的NCG分别提高了约0.47dB和0.25dB,距离香农限约1dB。因而其纠错性能更强,更适用于高速长距离光通信系统。     

一种改进的基于中国剩余定理的QC-LDPC码构造方法

为增大QC-LDPC码围长的同时减少码中包含的短环,提高其纠错性能,提出了一种基于中国剩余定理( CRT)的QC-LDPC码改进联合构造方法。该方法将设计围长为g的长码长的QC-LD-PC码的问题简化为设计一个围长为g的短分量码的问题,然后通过对其余分量码校验矩阵的列块进行适当置换,使得构造出的QC-LDPC码具有更少的短环和更优的性能,更适于可靠性要求较高的通信系统。仿真结果表明,与已有的CRT联合构造方法设计的QC-LDPC码相比,新方法构造的QC-LDPC码具有更少的短环,在误码率为10-6时获得了1.2 dB的编码增益。     

光通信系统中基于BIBD对QC-LDPC码的研究

基于平衡不完全区组设计(BIBD),深入分析与研究了准循环低密度奇偶校验(QC-LDPC)码的一种新颖构造方法,并通过该构造方法构造了3种同码率不同码长的QC-LDPC码,通过对这3种QC-LDPC码的仿真分析表明,同码率下,码长越长性能越好。同时在BER=10-6时码率均为93.7%的情况下,所构造的BIBD-QC-LDPC(5392,5056)码的净编码增益(NCG)比已广泛应用于光通信系统中的经典RS(255,239)码和ITU-T G.975.1中的LDPC(32640,30592)码分别提高了约2.13dB和1.41dB。因而其纠错性能更强,更适用于高速长距离光通信系统。该新颖构造方法简单灵活且编译码更容易实现。     

光通信系统中一种新颖的满秩QC-LDPC码的构造方法研究

为使低密度奇偶校验(LDPC)码高效地应用于光通信系统中,针对光通信系统的传输特点,提出了一种新颖的基于循环置换矩阵和掩蔽矩阵构造满秩准循环低密度奇偶校验(QC-LDPC)码的方法。该方法定义了一类基矩阵,由基矩阵扩展出循环置换矩阵,构造出围长至少为8的校验矩阵;提出了掩蔽矩阵的设计规则,并利用设计的掩蔽矩阵对前面得到的校验矩阵进行变换,构造出围长至少为8的满秩QC-LDPC码。与多种不同的QC-LDPC码构造方法进行理论分析和性能仿真比较,结果表明,利用该方法构造出的LDPC码字是满秩的,具有严格的准循环特性和优异的纠错性能,且构造灵活。该方法构造的码字适用于光通信系统。     

光通信中一种基于有限域循环子群的QC-LDPC码构造方法

基于有限域循环子群方法提出了一种结构简单,可以灵活选择码长、码率,并且编译码复杂度低的准循环低密度奇偶校验(QC-LDPC)码构造方法。利用此方法构造出适合光通信系统传输的规则QC-LDPC(5334,4955)码。仿真结果表明该码型利用和积迭代译码算法在加性高斯白噪声信道中取得了很好的性能,比已广泛应用于光通信中的经典RS(255,239)码具有更好的纠错性能。因此所构造的QC-LDPC(5334,4955)码能较好地适用于高速长距离光通信系统。     

卫星激光通信中基于Zig-Zag结构的原模图QC-LDPC码构造方法

为应对卫星激光通信信道的时变性、改善传输的可靠性,提出一种基于Zig-Zag结构的原模图QC-LDPC码构造方法.该方法将原模图与Zig-Zag结构的移位系数设计方法相结合,构造校验矩阵围长至少为8且码长码率可灵活选择的ZZ-QC-LDPC码.仿真结果表明:该方法所构造的ZZ-QC-LDPC码在误码率为10-6时,与同码率下基于等差数列和原模图构造的QC-LDPC码和基于最大公约数构造的QC-LDPC码以及具有大围长快速编码特性的QC-LDPC码相比,其净编码增益分别提高了约0.2,0.1和0.64 dB,且在较大码率范围内均具有良好的纠错性能.     

光通信中基于伽罗华域的QC-LDPC码构造方法

为了满足光通信系统对纠错码高码率、低误码率的要求,基于伽罗华域中域的特征提出了一种结构简单、易于编码并且可以有效避免四环的 QC-LDPC(准循环低密度奇偶校验)码的新构造方法。并运用该方法构造了适用于光通信系统的 FC-QC-LDPC(基于域特征的 QC-LDPC)(3969,3729)码。仿真结果表明,在误码率=10-7时,所构造的码率为0.937的 FC-QC-LDPC(3969,3729)码的 NCG (净编码增益)比 QC-LDPC(4288,4020)码提高了约0.15 dB,比 Linshu-QC-LDPC(3780,3542)码和经典的 RS(255,239)码的 NCG分别提高了约0.35和2.1 dB。此外,所构造的码的性能与 Mackay码的性能相当。因而其纠错性能更强,更适用于高速长距离光通信系统。     

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。     

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.     

A Versatile Mixed-Signal Pin Approach for Cost-Effective Test of Automotive ICs

Integrated circuits (ICs) intended for increasingly sophisticated automotive applications bring unique test demands. Advanced ICs for applications such as highly integrated automatic braking system (ABS) and airbag controllers combine high voltage digital channels, significant VI demands and precise timing capability. Along with continued missioncritical reliability concerns, the trend toward higher voltage operation and increased device integration requires specialized test capabilities able to extend across the wide operating ranges found in automotive applications. Among these capabilities, automotive test requirements increasingly dictate a need for a cost-effective versatile mixed-signal pin electronics with very high data rates reaching up to 50MHz with a voltage swing of-2 V to +28 V.     

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.     

Optical vibration and deviation measurement of rotating machine parts

It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer （LDV）.