一种基于NS-2的Internet视频码流传输研究方案

该文提出了一种基于NS-2网络仿真器的Internet视频码流传输研究方案，该方案通过修改NS-2的业务数据源发生器，将从视频码流中得出的IP分包信息注入NS-2虚拟网络进行传输，能将仿真和研究过程直接与真实码流发生联系。将在目标节点接收到的所有数据包按照时间戳信息重新拼接成一个视频文件，在码流播放器上回放，还可以直观看到网络传输效果，从而能直观论证网络通讯性能。利用该方案还可以进一步对视频和音频的多媒体混合码流传输算法或多媒体传输控制协议进行仿真，对于复杂网络拓扑及相关协议设计与研究将具有极为重要的意义和价值。     

Design and implementation of a VBR continuous media file server

We describe the design and implementation of a file server for variable bit rate continuous media. We address the problem of building a server where each stream may have a different bit rate and, more importantly, where the bit rate within a single stream may vary considerably. Such a server has been implemented within a high-speed network environment. The server is designed to be used in a heterogeneous environment and is linearly scalable. A significant aspect of the design of the system is the detailed consideration of the variable bit-rate profile of each data stream in performing admission control for the disk and for the network. This paper describes the system model, the user interface design, implementation details, and performance results based on initial experience with the server     

基于输入图像内容的比特率控制

在静止图像的压缩中 ,为得到固定大小的码流文件 ,有必要根据输入图像的特点 ,自适应地控制量化器的参数 ,从而控制输出压缩图像的比特率 .JPEG标准未给出比特率控制方法 ,而一些传统的比特率控制方法为专用的压缩解压缩系统设计 ,并不适用在于开放的基于交换格式的 JPEG压缩系统 .本文提出一种和 JPEG标准完全兼容的比特率控制算法 ,按照输入图像的活动性 ,计算相应的压缩质量因子 ,自适应地为每个 8× 8的块分配比特数 ,并且在熵编码时调整各块的比特数 ,适时启动块截除 ,保证压缩文件的大小不超过预先给定值 .本算法适用于存储容量有限的静止图像压缩的场合 ,可以保证存储规定帧数的压缩文件图像     

UBMBPT—unrestricted Hartree—Fock many-body perturbation theory program in C

The open-shell single-reference many-body perturbation theory (MBPT) method for electron correlation calculation has been implemented up to the third order. The inclusion of bubble as well as non-bubble diagrams allows the unrestricted Hartree—Fock (UHF) reference with the UHF as well as the restricted Hartree—Fock (RHF) optimized orbitals. The program has been implemented in C language for its efficiency and flexibility. Given the input requirements and physical resource limitations, dynamic memory allocation capability of C allows optimal use of physical memory automatically. Input data are taken from the standard input stream in text/ASCII form for generality; allowing interoperation with programs in other languages and piping for minimizing disk space requirements. If the correct input is provided by the appropriate SCF program and prefilter, user involvement in the calculation is minimal. Various command line options are provided to monitor the program progress through timings, memory allocation and deallocation as well as file and disk size tracing. The appropriate environment variables under UNIX operating system allow flexible reassignment of temporary files to different directories and/or disks without program recompilation.     

流文件MP4文件的核心技术

在MPEG4标准中,包括场景信息、对象信息、管理控制信息等信息都是以二进制形式进行编码并存放在流文件MP4中。MP4文件包含了与媒体数据时间序列相关的时间、结构、媒体信息(例如音频／视频表达文件),并通过轨道将它们联系在一起。本文重点介绍流文件MP4中的下列关键技术：与创建MP4文件相关的场景描述、对象描述、场景描述与对象描述之间的关系以及MP4流文件的组成机制和基于网络播放MP4流文件机制等,并基于MP4文件格式实现了汉字显示技术,这些内容有助于在实际研究中创建MPEG4流文件和应用MPEG4流技术。     

Geoic: an interactive terminal-based geochemical data processing system

A series of interactive terminal-based FORTRAN IV programs have been developed for processing and evaluating major and trace element data produced in the analysis of rock samples. The GEOIC system consists of three stages. The first is concerned with the processing of analytical data produced in the X-ray fluorescence (XRF) analysis of fused samples for major elements and pressed powder briquettes for trace elements. In the second stage, the major and trace element results are linked together by a tabulation program which creates an input file for CIPW norm programs. The tabulation program will sort also the analyses into groups according to an 8 character “group identifier” keyword attached to each analysis. Average analyses are calculated also for each group. The tabulation program combines the major, trace and normative data to produce a data base file as well as a tabulated output file for dispatch to a line printer. In the third stage, the data base file serves as the input to interactive programs for graphical and statistical evaluation of the geochemical data. The graphics program allows the user to plot rapidly binary and ternary diagrams for all samples or plotting may be restricted to specified groups or only to the group averages. The statistical program allows the user to calculate various parameters as well as a correlation coefficient matrix for all samples, for selected groups or for only group averages.The group identifier keyword attached by the user to each sample analysis facilitates the division of the suite of samples under study into groups and subgroups. This important feature adds considerable flexibility to the processing and evaluation of data via the tabulation, graphics and statistics programs.The tabulation program will accept also free-format major and trace element data produced by analytical methods other than XRF. The second and third stages of the system may be used, therefore, as a general purpose geochemical data processing and evaluation package.     

Design of a Simulation Package for Automated Guided Vehicle Systems

The lack of analytical techniques in designing optimal network configurations and control policies in Automated Guided Vehicle Systems (AGVS) leaves simulation as the designer's primary tool. ASP is a general purpose AGVS Simulation Package developed in SIMAN and FORTRAN. This interactive package is designed to relieve the user of programming the simulation model and allow the user to input different design configurations quickly. The package consists of an interactive user interface, a model file which contains the generic portion of the system model and an experiment file which contains user defined parameters which are problem specific. The user enters the network topology, vehicle operating characteristics and selects system and simulation control policies. Waiting time at each intersection and station and total system time are the general output of the package and may be further analyzed using the SIMAN Output Processor.     

二维码位流长度最小化算法

目的 快速响应矩阵码(quick response code,QR code)简称二维码,是一种由深色和浅色模块组成的正方形符号。给定输入数据,不同编码算法可能输出不同的位流。位流长度决定了二维码的版本,进而决定了二维码每条边上的模块数量。减小二维码的版本能够在不减小模块大小的前提下节省面积,或者在不改变面积的前提下增大模块大小。为了减小二维码面积、提高二维码识读率,本文提出了位流长度最小化算法。方法 首先,根据二维码位流可以分段切换编码模式的特点,归纳了6种编码状态;然后,根据二维码位流编码标准推导了状态转移关系,从而将位流长度最小化问题转换成动态规划问题;最后,通过求解动态规划问题,计算出最短位流。针对统一资源定位符(uniform resource locator,URL)类型数据,利用其部分字段对大小写不敏感、部分字段可以转义的性质,提出了统一资源定位符的最短位流计算算法,进一步缩短位流。结果 本文构建了一个测试集,包含603个编码了非URL数据的二维码,以及1 679个编码了URL数据的二维码。实验结果表明,本文算法与二维码标准相比,对于非URL测试集,位流长度减小的二维码占比9.1%,版本减小的二维码占比1.2%;对于URL测试集,位流长度减小的二维码占比98.4%,版本减小的二维码占比31.7%。结论 二维码位流长度最小化算法输出的位流长度最短,输出的二维码版本最小,能在兼容标准二维码解码器且不影响纠错能力的前提下提升二维码的数据容量。同时,本文算法运行速度快,易于使用,没有需要调节的参数。     

The URICA! II interactive collation system

URICA! II is an interactive collation system for the Apple Macintosh family of personal computers. It is designed to facilitate the collation of texts for the purpose of determining textual variants. The URICA! II system provides several utilities which support the collation and conflation of texts. The collation utilities allow a user to compare interactively two text files and record their differences in a variant data file. If desired, the computer can resolve simple variants automatically, involving the user only to resolve the more difficult variants. The conflation utility combines the variant data files from multiple collations into a single file which lists all of the textual variants, keyed against a common master text.     

利用LDOPE工具解码MODIS陆地产品质量信息

MODIS 十余种陆地产品都包含像元尺度的质量评估信息(QA),这些信息是用户合理利用这些产品的基础。由于QA类型多但数值小,通常是把多个QA以二进制格式压缩成整型数据的一个波段,这样节省了归档空间,加快了网络传输,并期望用户使用MODIS陆地数据业务化产品质量评估工具包( LDOPE Tools)把压缩的二进制恢复为通常的十进制波段。但是,由于LDOPE是由25个独立的软件组成的工具包,并没有按照特定功能进行组合,使得LDOPE普及受到限制,导致大量具有潜在应用价值的QA未能得到应有的开发利用。以MODIS 森林覆盖率产品中的一个QA(云量,Cloud)为例,介绍了把二进制恢复为十进制的主要过程,包括:①识别MODIS陆地产品中与QA相关的科学数据集；②LDOPE和 MRT软件安装；③利用LDOPE的3个命令进行QA的提取、解码、地图投影恢复；④利用MRT对解码后QA进行地图投影和文件格式转换；⑤利用ENVI对QA进行地理定位与属性验证。经过上述处理,QA即可与MODIS陆地产品进行像元尺度的综合分析。     

Bandwidth reservation with selectable bit-rate streams

Video and audio compression techniques allow continuous media streams to be transmitted at bit rates that are a function of the delivered quality of service. Digital networks will be increasingly used for the transmission of such continuous media streams. This paper describes an admission control policy in which the quality of service is negotiated at stream initiation, and is a function of both the desired quality of service and the available bandwidth resources. The advantage of this approach is the ability to robustly service large numbers of users, while providing increased quality of service during low usage periods. Several simple algorithms for implementing this policy are described and evaluated via simulation for a video-on-demand scenario.     

结合容量伪装和双文件系统的文件隐藏方法

针对现有基于通用串行总线(USB)移动存储设备的文件隐藏方法存在的鲁棒性差及隐藏强度低的问题,提出一种结合容量伪装和双文件系统的文件隐藏方法。在分析Nand flash芯片的特点及其管理机制的基础上,该方法通过篡改命令状态包(CSW)中的设备容量值,实现容量伪装,达到欺骗主机的目的;利用闪存转换层(FTL)存储管理机制,通过在物理块冗余区标记不同的内容把物理块分成两部分,划分隐藏区和普通区,利用格式化功能建立双文件系统;用户通过写特定数据发送切换文件系统请求,设备进行用户认证后完成文件系统切换,实现隐藏区的安全访问。理论分析和实验结果表明,该方法实现了对操作系统透明的文件隐藏;相对于挂接应用程序编程接口(API)、基于文件分配表(FAT)的修改以及加密等实现的文件隐藏方法,该方法不受系统对设备操作的影响,具有更好的鲁棒性和更高的隐藏强度。     

A general-purpose natural language interface to an operating system

One of the most difficult tasks facing new computer users is the management of data and programs through an operating system (OS) interface. Both command languages and graphical interfaces can impede a user unfamiliar with the terminology and organizational techniques of modern file management systems. Various attempts have been made in recent years to develop systems that will enable users to interact with the computer in natural language. By simplifying the form of user input to an OS, such interfaces allow the user to concentrate on file management tasks rather than on the means of expressing OS-specific instructions. The Informational Network for a Natural Talking (INFANT) System was originally developed as a conversational system for communication at the level of a small child. It has since been adapted for use as a general-purpose English language interface for standard OS file management operations. The INFANT System reduces an input sentence to a hierarchy of standardized propositional forms, which are mapped through a propositional knowledge base and a compositional semantics process into a high-level representation of meaning. Its effectiveness as a working natural language interface has been verified in a pair of experiments performed in a college computer lab. © 1996 John Wiley & Sons, Inc.     

The impending demise of the file system

The file system has been a trusted part of most computers for many years, and will likely continue as such in operating systems for many more. However, several emerging trends in user interfaces indicate that the basic file-system model is inadequate to fully satisfy the needs of new users, despite the flexibility of the underlying code and data structures. There is no need for users to know how their information is stored inside the guts of the computer. Indeed, the notion of a continuous file is itself is an abstraction: It masks the fact that the information is normally stored on noncontiguous sectors of a hard disk. From a user perspective, current file systems are based on three assumptions: Information is partitioned into coherent and disjunct units, each of which is treated as a separate object (file). Users typically manipulate information using a file and are restricted to be “in” one file at a time. Information objects are classified according to a single hierarchy: the subdirectory structure. Each information object is given a single, semi-unique name, which is fixed. This file name is the main way users access information inside the object. Window systems have made these assumptions less intolerable, but they still exist. Modern computing, particularly the Internet, is further undermining these assumptions in several ways     

Robust multi bit and high quality audio watermarking using pseudo-random sequences

A robust multi bit and high quality audio watermarking technique in time domain is proposed in this paper. Watermarking is a technique used to label digital media by hiding copyright or other information into the underlying data. The watermark must be imperceptible and undetectable by the user and should be robust to various types of distortion. To enhance the robustness and taper-resistance of the embedded watermark, in this paper a multi bit technique is employed. Instead of embedding one bit into an audio frame, multiple bits can be embedded into each audio sub-frame. For attackers, since they do not know the parameters, this significantly reduces the possibility of unauthorized bit detection and removal of watermark. In real-time watermarking applications, robustness is not the only factor that plays an important role. The other factor that plays a very an important role is computational complexity. In general, audio file is transmitted in compressed form. Real-time watermark embedding must take into account this compressed form, because first decompressing the data, adding a watermark and then recompressing the data is computationally too demanding. In this paper, we propose robust and low complexity audio watermarking algorithm. To evaluate the performance of the proposed audio watermarking algorithm, subjective and objective quality tests including bit error rate (BER) and signal-to-noise ratio (SNR) were conducted. Compared to traditional one bit embedding algorithm, the proposed algorithm gives highly recovery rate after attack by commonly used audio data manipulations, such as low pass filtering, requantization, resampling, and MP3 compression.     

An integrated paleomagnetic analysis program for stratigraphy labs and research projects

This paper describes a Windows-based paleomagnetic analysis program integrates on-screen visualization and analysis of paleomagnetic data and printing graphic outputs. The program is easy to understand and use with its graphic user interface. It accepts fixed length or delimited data files, each of which can contain up to 500 samples with a variable number of demagnetization steps (up to 50). The integrated toolboxes accept keyboard or copy-and-paste data input, and allow the user to calculate paleolatitudes, convert between spherical and Cartesian coordinates, and perform many functions of the main program.The main program converts an ASCII data file into a specially formatted file (*.mag) for random read/write access. After conversion, the *.mag file is automatically opened, and a list of sample is displayed in a small window. When a sample on the list is clicked, the associated demagnetization data are displayed in a nearby window. The user can visualize the data using the Zijderveld (/modified Zijderveld) projection and the stereographic (/Lambert equal-area) projection simultaneously or individually. The data visualized can be in either geographic or tilt-corrected coordinates, from all or certain demagnetization steps of a sample, or from a single demagnetization step of all samples. Characteristic directions of each sample are derived from a three-dimensional least-squares fit of selected demagnetization steps by principal component analysis (PCA). Mean directions from “Fisher” analysis are computed from click-selected samples using a designated demagnetization step or the characteristic directions. These mean directions are automatically computed for each polarity by a routine that compensates for pervasive overprint directions, and that can also utilize subjective weighting of sample directions. The graphic outputs can be printed on paper or screen-captured into graphic software, and the analytical results can be copied and pasted into word-processing programs.     

An Overview of the Runtime Verification Tool Java PathExplorer

We present an overview of the Java PathExplorer runtime verification tool, in short referred to as JPAX. JPAX can monitor the execution of a Java program and check that it conforms with a set of user provided properties formulated in temporal logic. JPAX can in addition analyze the program for concurrency errors such as deadlocks and data races. The concurrency analysis requires no user provided specification. The tool facilitates automated instrumentation of a program's bytecode, which when executed will emit an event stream, the execution trace, to an observer. The observer dispatches the incoming event stream to a set of observer processes, each performing a specialized analysis, such as the temporal logic verification, the deadlock analysis and the data race analysis. Temporal logic specifications can be formulated by the user in the Maude rewriting logic, where Maude is a high-speed rewriting system for equational logic, but here extended with executable temporal logic. The Maude rewriting engine is then activated as an event driven monitoring process. Alternatively, temporal specifications can be translated into automata or algorithms that can efficiently check the event stream. JPAX can be used during program testing to gain increased information about program executions, and can potentially furthermore be applied during operation to survey safety critical systems.     

Action range communication (ARC): A digital architecture for user and device interaction

We propose a new networking interface (ARC) for electronic devices. This interface will unify display, user input, and data transmission into one information broadcasting structure. The concept is based on the dependence of action on vision. Because action and vision are consecutive steps, they should be considered together as one information transmission process. We propose a model to describe this digital information transmission. In this model, a new information carrier containing both image and data is broadcasted to a receiver through the user. The user acts like a network switch that selects information to receiver. On‐screen user input and short‐range data transmission represent such transmission but in different environments. The display function is also included by incorporating the “null” data concept. The display matrix can be converted into an information broadcaster, and the panel becomes a transceiver for ARC. This reduces the cost and leads to a simpler device architecture with only networking interfaces. The information carrier is a generalization of data carrier. A general information transmission is proposed to include both ARC and data communication. We also discuss new interactions based on ARC such as cyborg input.