基于Linux系统对btrfs文件系统性能的对比分析

btrfs(b-tree文件系统)新增了ext系列文件系统没有的功能特性.本文简要阐述了btrfs文件系统新增的一些特性,并主要对比分析了与ext4文件系统在创建文件系统、删除文件、拷贝文件、读写文件方面的性能差异.对比分析了btrfs是否启用COW(Copy-on-write)机制,和选择不同压缩算法对文件读写性能的影响.通过对比分析ext4,btrfs在创建文件系统、拷贝文件和随机读写文件性能方面,其明显优于ext4.btrfs新增了COW机制,同时新增的zlib和lzo算法能够大幅提升文件的读写性能,目前btrfs已取代ext4作为Fedora33中的默认文件系统,后期有望在Linux平台得到广泛使用.     

用于智能电视操作系统的加密文件系统设计

随着智能电视的普及,如何确保用户数据的安全成了当前智能电视操作系统面临的一个重要研究课题.提出了一种用于智能电视操作系统的加密文件系统的设计,能够抵御恶意超级用户的攻击,可以透明地对用户数据提供机密性和完整性保护,支持ext2、ext3、ext4和jfs等多种文件系统,加密算法可以由用户选择和更改,可以根据用户的策略对指定文件、文件夹或者整个文件系统进行加密保护.     

Calculation and Improvement on External Quantum Efficiency of OLEDs

The calculation of the external quantum efficiency （ηext） of organic light-emitting devices （OLEDs） is presented theoretically. The basic idea is to obtain ηext by calculating the fraction of the generated light that can escape through the top surface and the average transmittance over the escape cone. During the calculation, the effects of the interference, absorption and multiple reflections are neglected. Then a result of a typical 8-tris-hydroxyquinoline aluminum（Alq3）-based OLEDs on a planar glass substrate is obtained. And a twice increase in ηext, can be achieved by using a high-index-glass substrate with an antireflection coating（SiO2） on substrate surface.     

嵌入式μClinux下NOR FLASH管理方案的实现

在嵌入式μClinux下通过移植MTD子系统和JFFS 2日志型文件系统,为实现NOR FLASH存储器中数据的动态操作和管理提供了一种理想的解决方案.这里以AM29LV160DB芯片为例,讨论基于S3C44B0X+μClinux平台构建JFFS 2文件系统的方法.最后通过实验测试,可使JFFS 2文件系统稳定地运行在ARM-μClinux开发板上.     

嵌入式Linux根文件系统的研究

在嵌入式Linux系统中,根文件系统是构建嵌入式Linux系统的重要组成部分,是Linux／Unix系统不可或缺的组件。这里从Linux根文件系统底层出发,详细分析根文件系统的组成和如何利用Busybox配置完整的根文件系统,并给出了启动脚本和配置文件以实现简单的根文件系统,并且以Cramfs和Jffs2为例详述了根文件系统的制作过程,为其他文件系统的制作提供参考。     

嵌入式Linux文件系统的研究与应用

随着ARM技术的广泛应用,建立面向ARM构架的嵌入式操作系统成为当前研究的热点问题。为此,研究了cramfs根文件系统和jffs2普通文件系统的实现及其应用,成功设计了一个cramfs根文件系统并实现自启动Qt应用程序,最后验证了所设计的文件系统的运行情况。     

JFFS2文件系统在μClinux中的实现

FLASH作为新型非易失性半导体存储器在嵌入式系统的开发中占有重要的地位.为了在嵌入式系统中实现数据的动态操作,介绍μClinux下的FLASH文件系统,特别是日志型文件系统的设计原理及特点;利用Linux提供的MTD接口,通过添加与FLASH对应的map driver和FLASH驱动,修改设备节点,配置内核等步骤,将JFFS2文件系统移植到s3c44bO使用的FLASH芯片上.通过挂载,用户可以像使用普通硬盘分区一样对此目录下面的文件进行操作,从而实现对FLASH的动态操作和管理.结果表明,在JFFS2文件系统下,保存的文件是可读写的,系统掉电后创建的文件也不会丢失.     

并行文件系统在集群系统中的应用研究

随着集群系统得到广泛应用,集群系统计算能力的不断提高,在并行运算的过程中,对数据读写速度的要求也越来越高,I/O的吞吐能力成为该过程的瓶颈。为了提高读写速度,以解决I/O瓶颈问题,通过并行文件系统替代以前的NFS文件系统。并行文件系统具有管理简单,可合理保护已有投资的优势。并行文件系统由于其多I/O服务器并行读写,可有效提高数据的读写速度,解决数据读写瓶颈,缩短资料处理周期。在此基础上建立存储池,可为地震资料处理解释一体化打下坚实的基础。     

广州亚运会IBC-MAP系统运行总结(下)

3.文件系统采用新奥特的64位文件系统ASFS,专门对视音频存储和传输进行优化。ASFS采用虚拟化技术和多卷体系结构,将存储设备提供的物理卷通过条带化、镜像等组合方式虚拟化为文件系统使用的逻辑卷,文件系统对逻辑卷配置数据卷、元数卷等不同文件系统属性,不仅可以提高系统的性能可扩展性(跨设备)、容量的可扩展性(在线添加设备),而且通过基于卷的故障隔离策略可以有效提高ASFS整体系统的可靠性、容错性和数据的安全性。     

基于S3C2410的嵌入式Linux系统构建

主要研究Linux在ARM芯片上的移植。首先介绍ARM微核在嵌入式系统中发展的趋势,然后在分析S3C2410体系结构的基础上给出从准备移植环境BootLoader vivi移植、Linux2.6.14移植、YAFFS2文件系统的移植,一直到根文件系统的建立的全过程。按提供的方法和技巧可以很方便地建立一个ARM Linux开发平台。     

基于多尺度特征提取的MRI脑肿瘤图像分割研究

针对磁共振成像(magnetic resonance imaging, MRI)脑部肿瘤区域误识别及肿瘤形状 差异较大的问题,提出一种基于多尺度特征提取的 MRI 脑肿瘤图像分割方法。分割模型以 U-Net 为骨干网络,使用密集金字塔卷积(dense pyramidal convolution, DPC)提取多尺度特征, 以适应不同尺寸肿瘤的分割,同时引入条状池化(strip pooling, SP),凭借其能捕获肿瘤中远 距离区域的依赖关系,进一步加强对肿瘤图像的分割能力。提出的方法在 Kaggle_3m 数据 集上进行了实验验证,实验结果表明该方法具有良好的脑部肿瘤分割性能, 其中Dice相似 系数、杰卡德系数分别达到了91.66%,84.38% 。     

基于表面等离激元共振效应及表面钝化提高异质结太阳电池效率的研究

基于硅纳米孔(SiNHs)/银纳米颗粒(AgNPs)纳米复合薄膜制备了无机/有机物混合太阳电池,并且研究它们的光吸收谱和光电转换等性能.SiNHs/AgNPs纳米复合薄膜利用金属辅助化学刻蚀方法获得,然后在制备好的薄膜上旋涂一层有机聚合物PEDOT∶PSS作为空穴传输层.从光吸收谱可以看出,有AgNPs的纳米复合薄膜有明显的吸收峰,并且在短波区域,相比于没有AgNPs的纳米复合薄膜,整体的吸收有较大的提高.同时,有AgNPs的太阳电池的短路电流密度和外量子效率均有明显的提高.尤其在对纳米复合薄膜表面进行钝化处理后,该混合异质结太阳电池的光电转换效率最高可达到5.5％.认为,这主要是由于AgNPs的局域表面等离激元共振效应和钝化减少纳米复合薄膜表面缺陷等原因使电池的性能有较大的提高.     

基于BSIM3的超深亚微米器件建模及模型参数提取

对适用于超深亚微米电路模拟的 MOSFET器件模型进行了研究 ,完成计入量子效应、多晶硅耗尽效应等基于 BSIM3的 MOSFET模型。针对阈值电压模型以及 I- V模型中的参数编写了模型参数提取程序 ,采用最小二乘法原理 ,并采用麦夸脱算法以降低参数提取结果对初值的依赖 ,对已有参数进行了修正。模型以及参数提取结果都分别进行了验证。     

基于改进生成对抗网络的低剂量CT去噪算法

针对低剂量计算机断层扫描(computerized tomography,CT)在图像采集过程中引入较多噪声,造成图像质量严重下降的问题, 提出一种基于残差注意力机制与复合感知损失的低剂量CT去噪算法。在该算法中,利用生 成对抗网络完成对低剂量CT图像的去噪,在网络框架中引入多尺度特征提取及残差注意力 模块,以融合图像中不同尺度的信息,提高网络对噪声特征的区分能力,避免在去噪过程中 丢失图像细节信息。同时采用复合感知损失函数,以加快网络收敛速度,促使去噪图像在感 知上与原图像更接近。实验结果表明:与现有的算法相比,所提算法能够有效抑制低剂量 CT图像中的噪声,并恢复更多的纹理细节;对比低剂量CT图像,所提算法处理后的CT 图像峰值信噪比(peak signal-to-noise ratio,PSNR) 值提高了31.72%, 结构相似性(structural similarity,SSIM)值提高了13.15%,可以满足更高的医学影像诊断要求 。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

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.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.