FoxBASE与ORACLE之间数据转载的实现

首先分析了ＤＯＳ支持的ＦｏｘＢＡＳＥ数据库与ＵＮＩＸ支持的ＯＲＡＣＬＥ数据的内部结构，进而以此为基础介绍一种ＦｏｘＢＡＳＥ与ＯＲＡＣＬＥ之间的数据转载方法。     

INTERNETHFC接入技术及其应用

本文介绍了ＩＮＴＥＲＥＮＴ接入技术,并重点介绍了ＨＦＣ网接入技术和深圳职业技术学院校园ＩＮＴＥＲＮＥＴＨＦＣ接入方案与实施。     

分布计算环境的实现技术

本文论述了分布式计算环境以及远过程调用、线程、目录服务等支持机制的概念；并以ＯＳＦ（ＯｐｅｎＳｏｆｔｗａｒｅＦｏｕｎｄａｔｉｏｎ）ＤＣＥ（ＤｉｓｔｒｉｂｕｔｅｄＣｏｍｐｕｔｉｎｇＥｎｖｉｒｏｒｍｅｎｔ）１．０为实例介绍ＤＣＥ的实现技术。ＯＳＦＤＣＥ提供了建立一个分布式应用的基础结构，随着它的逐步完善，建立在其上的分布式应用的增多，它趋向于成为分布式应用的标准平台。     

XBASE数据库文件与ORACLE之间的数据交换

本文介绍了Ｆｏｘｂａｓｅ、Ｆｏｘｐｒｏ等ＸＢＡＳＥ数据库中的数据文件同ＯＲＡＣＬＥ之间数据交换的方法。首先介绍如何使用ＳＱＬ＊ＵＬＯＡＤＥＲ将ＸＢＡＳＥ数据库的数据转储到ＯＲＡＣＬＥ数据库中。由于ＯＲＡＣＬＥ没有提供将ＯＲＡＣＬＥ数据库中的数据传储到ＸＢＡＳＥ数据库文件的工具，因此，本文然后给出了解决这一问题的方法。     

基于装配的全柔性化模具CAD技术研究

全柔性ＣＡＤ技术是参数化的重要发展,它从根本上革新了传统ＣＡＤ系统的思维模式,晃一种全新的概念,介绍了基于Ｔ－ＦＬＥＸ的全柔性模具ＣＡＤ的技术,提出了基于柔性化装配模型的模具的设计思想与想架,着重探讨了其具体实现策略的方法,并给出了一个应用实例。     

Visual Foxpro5.0与其他软件间的资源共享

本文介绍了 Ｖｉｓｕａｌ Ｆｏｘｐｒｏ提供的 ＯＬＥ技术及其应用方法,并引用了多个实例详细介绍 ＶＦＰ与 ＤＥＬＰＨＩ,ＥＸＣＥＬ,ＷＯＲＤ,ＶＢ,ＩＥ等应用程序间的相互联系。     

QPSK调制与FEC差错控制在DVB系统中的应用

在简要介绍ＤＶＢ接收系统基本结构的基础上,分析了ＤＶＢ－Ｓ标准下数字卫星接收机呆变码率的ＱＰＳＫ解调和ＦＥＣ的差错控制技术,最后结合自行开发的ＤＶＢ数字卫星接收机对包含解调与ＦＥＣ功能的两种集成电路芯片了比较。     

Windows环境中FoxPro与C之间的DDE通讯

本文讨论Ｗｉｎｄｏｗｓ环境中ＦｏｘＰｒｏ程序与Ｃ程序之间的数据通讯，介绍了ＤＤＥ通讯的原理和机制。着重阐述了利用ＤＤＥＭＬ实现的ＤＤＥ通讯，并进而实现了ＦｏｘＰｒｏ程序和Ｃ程序之间的实时数据交换。     

AutoCAD与FoxBASE的数据共享

介绍了一种ＡｕｔｏＣＡＤ与ＦｏｘＢＡＳＥ数据共享的思路，给出了ＤＢＦ文件或ＴＸＴ文件转换为ＤＷＧ文件格式的一种手段。采用文件方法可以做到ＡｕｔｏＣＡＤ下数据的一次性录入，多次使用。     

计算机辅助FMECA

故障模式影响及危害性分析（ＦＭＥＣＡ）是一种可靠性分析方法，其中ＦＭＥＡ矩阵法的结构性比较强，清晰地体现了系统中故障模式与故障影响之间的因果关系。从矩阵法可以总结出ＦＭＥＡ迭代，通过迭代，可以减轻分析人员的工作量，保持数据的一致性。本文详细说明了迭代的过程，并介绍了一个自动迭代和可视化的计算机辅助ＦＭＥＣＡ工具，说明了其软件结构和功能。     

单向信道的信息可靠传输机制研究

提出了两级FEC的机制来解决单向信道的信息可靠传输的问题。数据包级FEC（第一级）通过添加冗余数据包来恢复传输过程中数据包的丢失。比特级FEC（第二级）通过添加冗余比特来纠正数据在传输过程中比特差错。鉴于包头信息是数据包级FEC的关键,提出数据包包头FEC机制来尽量保证包头信息的正确。提出的方案能很好地恢复丢失的数据包,特别是连续数据包的丢失,能很好地纠正比特差错。     

An unequal packet loss resilience scheme for video over the Internet

We present an unequal packet loss resilience scheme for robust transmission of video over the Internet. By jointly exploiting the unequal importance existing in different levels of syntax hierarchy in video coding schemes, GOP-level and Resynchronization-packet-level Integrated Protection (GRIP) is designed for joint unequal loss protection (ULP) in these two levels using forward error correction (FEC) across packets. Two algorithms are developed to achieve efficient FEC assignment for the proposed GRIP framework: a model-based FEC assignment algorithm and a heuristic FEC assignment algorithm. The model-based FEC assignment algorithm is to achieve optimal allocation of FEC codes based on a simple but effective performance metric, namely distortion-weighted expected length of error propagation, which is adopted to quantify the temporal propagation effect of packet loss on video quality degradation. The heuristic FEC assignment algorithm aims at providing a much simpler yet effective FEC assignment with little computational complexity. The proposed GRIP together with any of the two developed FEC assignment algorithms demonstrates strong robustness against burst packet losses with adaptation to different channel status.     

实时视频通信中的自适应前向纠错方案设计

本文针对实时视频通信中的网络丢包问题，提出了一种基于Reed Solomon算法的自适应FEC方案。与以往的静态FEC编解码方案不同，该方案引入一种新的基于SIP／RTP的QoS反馈机制，根据丢包率大小在发送端调整FEC冗余度、整体发送速率以及封包大小来保证服务质量；并针对网络突发丢包情况，在对数据包进行FEC编码时采用了交织技术     

Video loss recovery with FEC and stream replication

Packet loss is inevitable in video multicast. In this paper, we propose and study an effective feedback-free loss recovery scheme for layered video which combines forward error correction (FEC) and stream replication. In our scheme, the server multicasts the video in parallel with FEC packets and a number of replicated delayed (ReD) version of the stream. Receivers autonomously and dynamically join the FEC and ReD streams to repair their losses. On the server side, we analyze and optimize the number of replicated streams and FEC packets to meet a certain residual loss requirement (i.e., error after correction). On the receiver side, we analyze the optimal combination of FEC and ReD packets to minimize its loss. We also present a fast yet accurate approximation algorithm for receiver to make such decision. We show that FEC combined with merely one or two replicated streams can effectively reduce the residual error rate (by as much as 50%) as compared with pure FEC or replication alone. Both subjective and objective video measures confirm that our recovery scheme achieves much better visual quality.     

Concurrent multipath transmission combining forward error correction and path interleaving for video streaming

Video streaming is a popular application on next generation networks (NGNs). However, video streaming over NGNs has many challenges due to the high bit error rates of these networks. Forward error correction (FEC) is often applied to improve the quality of video streaming. However, continuous lost packets decrease the recovery performance of FEC protection in NGNs. To disperse continuous lost packets to different FEC blocks, we propose a concurrent multipath transmission that combines FEC with path interleaving. Our proposed control scheme adaptively adjusts the FEC block length and concurrently sends data interleaved over multiple paths. Experimental results with our approach show improved packet loss and signal to noise ratio performance.     

Sub-packet forward error correction mechanism for video streaming over wireless networks

Traditional Forward Error Correction (FEC) mechanisms can be divided into Packet level FEC (PFEC) mechanisms and Byte level FEC (BFEC) mechanisms. The PFEC mechanism of recovering from errors in a source packet requires an entire FEC redundant packet even though the error involves a few bit errors. The recovery capability of the BFEC mechanism is only half of the FEC redundancy. Accordingly, an adaptive Sub-Packet FEC (SPFEC) mechanism is proposed in this paper to improve the quality of video streaming data over wireless networks, simultaneously enhancing the recovery performance and reducing the end-to-end delay jitter. The SPFEC mechanism divides a packet into n sub-packets by means of the concept of a virtual packet. The SPFEC mechanism uses a checksum in each sub-packet to identify the position of the error sub-packet. Simulation experiments show the adaptive SPFEC mechanism achieves high recovery performance and low end-to-end delay jitter. The SPFEC mechanism outperforms traditional FEC mechanism in terms of packet loss rate and video Peak Signal-to-Noise Ratio (PSNR). SPFEC offers an alternative for improved efficiency video streaming that will be of interest to the designers of the next generation environments.     

视频传输中的FEC技术综述

对几种视频差错控制技术进行了概括与比较,总结了前向纠错算法的基本原理及其优缺点.重点讨论了几种改进的前向纠错算法,包括动态前向纠错机制、自适应模型、主观质量控制策略和组播环境中的前向纠错方法.     

视频传输中的FEC技术综述

对几种视频差错控制技术进行了概括与比较,总结了前向纠错算法的基本原理及其优缺点。重点讨论了几种改进的前向纠错算法,包括动态前向纠错机制、自适应模型、主观质量控制策略和组播环境中的前向纠错方法。     

Generic forward error correction of short frames for IP streaming applications

If the frame size of a multimedia encoder is small, Internet Protocol (IP) streaming applications need to pack many encoded media frames in each Real-time Transport Protocol (RTP) packet to avoid unnecessary header overhead. The generic forward error correction (FEC) mechanisms proposed in the literature for RTP transmission do not perform optimally in terms of stability when the RTP payload consists of several individual data elements of equal priority. In this paper, we present a novel approach for generating FEC packets optimized for applications packing multiple individually decodable media frames in each RTP payload. In the proposed method, a set of frames and its corresponding FEC data are spread among multiple packets so that the experienced frame loss rate does not vary greatly under different packet loss patterns. We verify the performance improvement gained against traditional generic FEC by analyzing and comparing the variance of the residual frame loss rate in the proposed packetization scheme and in the baseline generic FEC.     

基于Kalman滤波的无线流媒体自适应混合FEC/ ARQ控制策略

提出了一种用于无线实时流媒体传输的数据链路层自适应混合FEC/ARQ控制策略,以显著提高接收方的播放质量。该策略采用跨层设计的方法,基于Kalman滤波器预测当前的网络状态,自适应地调整FEC参数N和ARQ参数Nmax;另一方面,在应用层采用自适应FEC策略,在视频源数据和冗余数据之间动态分配网络带宽。数学分析和仿真验证均表明,该策略能使接收方获得最大的可播放帧率,有效地提高了流媒体传输的可靠性和实时性。