创建FTP服务器和设计磁盘配额的方法与实现

FTP是网络系统提供的基本服务之一．用户可以通过FTP上传和下载文件。本文介绍Linux系统的FTP服务器的原理以及建立FTP服务器和对FTP用户的磁盘配额进行设置。     

Block Copolymer Surface Reconstuction: A Reversible Route to Nanoporous Films

Thin films of block copolymers have been used as templates and scaffolds for the fabrication of arrays of nanostructured materials. In general, a chemical modification of the film or the removal of one of the components by photodegradative methods is required to produce a nanoporous film that serves as a template or scaffold. Here, however, the preferential interaction of one of the components with a solvent is shown to produce a reconstruction of the block copolymer film that, upon drying, leads to the generation of a nanoporous template. The area density of the pores is identical to that of the original copolymer thin film. Since no chemical reactions occurr, the process is fully reversible. Upon heating the copolymer film above its glass‐transition temperature, mobility is imparted to the copolymer and the original copolymer film with oriented domains is recovered. The film reconstruction significantly simplifies the generation of nanoporous templates.     

MAXIMUM ENTROPY DECONVOLUTION OF XPS PEAK

Necessity of XPS spectrum,deconvolution,disadvantages of the traditional Fast Fourier Tranderm decon-volution method(FFT),princtple,method and advantage ofMaximum Entropy Deconvolution Method (MEM) are de-scribed.Criteria for determing the number of data points sam-pled in MEM are the main point disccussed in the paper,someXPS deconvolution applications of our MEM software showthat the MEM makes XPS deconvolution much easier than thetraditional FFT method.     

MIMO系统中的分组全分集全码率空时编码

针对未编码的多输入多输出（MIMO，Multi—Input Multi—Output）系统，提出一种复杂度适中的分组全分集全码率（GFDFR，Group—wise Full Diversity Full Rate）空时编码方案。该方案通过在发送端进行天线分组，各组独立编码，减小全分集全码率（FDFR，Full Diversity Full Rate）编码块的大小从而降低系统编解码复杂度；在频率选择性信道中，进一步对子载波分组进行独立编码，获得频率分集（或多径分集），以适中的复杂度在不降低系统分集度的情况下保证了信息的全码率传输，是一种在MIMO信道中极具实用价值的空时编码方案。     

准连续波体制雷达最大熵方法的算法选择

准连续体制作为一种新型雷达体制以其固有的优越性给雷达界带来了巨大的冲击。其数字信号处理系统的开发是进一步完善该体制雷达的关键。本文针对数字信号处理系统中最大熵谱外推电路的算法选择进行了研究。     

东营凹陷滚动勘探开发技术研究与应用

东营凹陷已进入勘探开发成熟期 ,滚动勘探开发是增储稳产的主要手段 ,精细油藏描述是其关键。总结滚动勘探开发的 4种方式 (老区扩边、发现新块、发现新层系和新区滚动勘探开发 ) ,对断块复杂程度提出按每平方千米内所有断层的累加长度划分的新方法 ,从构造描述、储集层描述和油藏描述方面介绍了滚动勘探开发的技术方法。以永 8断块为例 ,在层位标定、反射特征分析、构造描述流程、地震地质分析等方面进行深入分析 ,归纳精细油藏描述的具体方法 ,强调了三维地震数据体的相干分析、属性分析等技术的重要作用。应用这一滚动勘探开发技术 ,使东营凹陷每年新增滚动储量近2 0 0 0× 10 4 t。图 3参 10     

压缩奇偶相干态的熵压缩特性

用数值方法讨论了相干态强度、相位角和压缩参数对压缩奇偶相干态位置熵和动量熵压缩特性的影响。结果表明，压缩奇偶相干态的位置熵和动量熵均可呈现压缩性，压缩偶相干态的最大熵压缩度比压缩奇相干态的要大。熵压缩度与相干态强度、相位角和压缩参数均有关系，但压缩因子对场熵压缩的影响最大。当其它条件一定时，压缩偶相干态在压缩参数|β|=O．95时，位置熵(或动量熵)的压缩度最大，但压缩奇相干态无此特点。     

Concurrent error detection of fault-based side-channel cryptanalysis of 128-bit RC6 block cipher

Fault-based side channel cryptanalysis is very effective against symmetric and asymmetric encryption algorithms. Although straightforward hardware and time redundancy based concurrent error detection (CED) architectures can be used to thwart such attacks, they entail significant overhead (either area or performance). In this paper we investigate two systematic approaches to low-cost, low-latency CED for symmetric encryption algorithm RC6. The proposed techniques have been validated on FPGA implementations of RC6, one of the advanced encryption standard finalists.     

A Micellar Route to Ordered Arrays of Magnetic Nanoparticles: From Size‐Selected Pure Cobalt Dots to Cobalt–Cobalt Oxide Core–Shell Systems

Starting with Co‐salt‐loaded inverse micelles, which form if the diblock copolymer polystyrene‐block‐poly(2‐vinylpyridine) is dissolved in a selective solvent like toluene and CoCl₂ is added to the solution, monomicellar arrays of such micelles exhibiting a significant hexagonal order can be prepared on top of various substrates with tailored intermicellar distances and structure heights. In order to remove the polymer matrix and to finally obtain arrays of pure Co nanoparticles, the micelles are first exposed to an oxygen plasma, followed by a treatment in a hydrogen plasma. Applying in‐situ X‐ray photoelectron spectroscopy, it is demonstrated that: 1) The oxygen plasma completely removes the polymer, though conserving the original order of the micellar array. Furthermore, the resulting nanoparticles are entirely oxidized with a chemical shift of the Co 2p_3/2 line pointing to the formation of Co₃O₄. 2) By the subsequent hydrogen plasma treatment the nanoparticles are fully reduced to metallic Co. 3) By exposing the pure Co nanoparticles for 100 s to various oxygen partial pressures pequation/tex2gif-inf-5.gif, a stepwise oxidation is observed with a still metallic Co core surrounded by an oxide shell. The data allow the extraction of the thickness of the oxide shell as a function of the total exposure to oxygen (pequation/tex2gif-inf-7.gif × time), thus giving the opportunity to control the ferromagnetic–antiferromagnetic composition of an exchange‐biased magnetic system.     

茨21-133井CO2吞吐技术初步试验

茨榆坨油田茨13块原油属于普通稠油，1993年开始蒸汽吞吐采油，从第二轮开始效果明显变差，注汽返排率低，有效周期短，产量下降快，套管变形井增多。针对这些问题，在该区块茨21—133井进行CO2吞吐采油工艺现场试验，获得成功，增油效果明显。