A Stream Control Transmission Protocol Based OAM System of 3G Cellular Network

OAM (Operations, Administration and Maintenance) system is a very impo rtant component of 3G cellular network. In order to acquire overall managemen t, fast response and steady operation, an SCTP (Stream Control Transmission Prot ocol) based OAM, i.e., SOAM system was proposed. SOAM implements new characters of SCTP such as multi-stream, enforced SACK and heartbeat mechanism on its tran sport layer. These characters help SOAM decrease the message transmission delay and accelerate the link failure detection. Besides, a new component named SOAM agent was introduced to improve the operation efficiency of SOAM. The experim ental results prove the proposed SOAM system achieves better performance on sign aling transmission compared with conventional TCP based OAM system.

Control of reactive dividing wall column for selective hydrogenation and separation of C3 stream

In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.

Load Shedding Strategy Based on Combined Feed-Forward Plus Feedback Control over Data Streams

In data stream management systems (DSMSs), how to maintain the quality of queries is a difficult problem because both the processing cost and data arrival rates are highly unpredictable. When the system is overloaded, quality degrades significantly and thus load shedding becomes necessary. Unlike processing overloading in the general way which is only by a feedback control (FB) loop to obtain a good and stable performance over data streams, a feedback plus feed-forward control (FFC) strategy is introduced in DSMSs, which have a good quality of service (QoS) in the aspects of miss ratio and processing delay. In this paper, a quality adaptation framework is proposed, in which the control-theory-based techniques are leveraged to adjust the application behavior with the considerations of the current system status. Compared to previous solutions, the FFC strategy achieves a good quality with a waste of fewer resources.

Dynamic multimedia stream adaptation and rate control for heterogeneous networks

Dynamic adaptation of multimedia content is seen as an important feature of next generation networks and pervasive systems enabling terminals and applications to adapt to changes in e.g. context, access network, and available Quality-of-Service(QoS) due to mobility of users, devices or sessions. We present the architecture of a multimedia stream adaptation service which enables communication between terminals having heterogeneous hardware and software capabilities and served by heterogeneous networks. The service runs on special content adaptation nodes which can be placed at any location within the network. The flexible structure of our architecture allows using a variety of different adaptation engines. A generic transcoding engine is used to change the codec of streams. An MPEG-21 Digital Item Adaptation (DIA) based transformation engine allows adjusting the data rate of scalable media streams. An intelligent decision-taking engine implements adaptive flow control which takes into account current network QoS parameters and congestion information. Measurements demonstrate the quality gains achieved through adaptive congestion control mechanisms under conditions typical for a heterogeneous network.

基于DVB和IP双结构传输模式的复合流式虚拟视频点播系统设计

当虚拟视频点播系统遇到高访问量时会使其服务器负荷过大,导致视频传输速度下降、播放不连续。因此,设计一种基于DVB和IP双结构传输模式的复合流式虚拟视频点播系统,以适应用户需求和网络条件,动态调整视频流的传输质量和分辨率。构建基于DVB和IP双结构传输模式的复合流式虚拟视频点播系统框架,终端用户通过基础服务层的Web页面提交视频点播申请后,从视频编排层获取点播视频;控制层的播出控制模块调取PBHS算法来实现网络资源受限下的带宽自适应分配,以动态地调整不同带宽占用,优化网络资源利用,提高传输效率。通过视频传送模块输出点播视频,利用传输层的IP和DVB双结构传输模式将其输送到应用层,最终可视化呈现给用户。实验结果表明,所设计系统可实现虚拟视频点播,视频播放连续不卡顿、画面分辨率高,信令延迟仅34 ms,视频传输速度达到18 Mb/s,平均点播时间为1 320 ms,且拒绝用户数少。

UNIX系统V中的STREAMS机制

STREAMS机制是操作系统设计和实现中使用的一种重要新技术.本文说明这种机制的主要优点、它的基本结构和工作原理,包括:队列、消息、流首、模块、流量控制和基于流的管理等.

基于Spark Streaming流技术的机动车缉查布控系统设计

机动车缉查布控系统以治安交通卡口系统为基础,将公路运行车辆的构成、流量分布、违章情况等信息进行汇总,实现对车辆轨迹的查询分析,从而为交通规划、管理和案件侦破等提供有效决策。由于机动车的数量增长迅猛,且机动车违规违章具有流动性、偶发性的特点,造成卡口系统录入的数据量巨大,传统的机动车缉查布控技术只能在预设条件下对数据进行查询,不能实现快速地实时分析查询。通过采用Spark Streaming技术进行大数据实时处理,实现实时显示和告警机动车违规违章活动热点,分析和预测机动车活动轨迹。

等离子体合成射流改善S弯进气道气动性能的实验研究

为了对狭缝式S弯进气道中的流动分离进行有效控制,本文基于等离子体合成射流开展了激励特性和相关流动控制实验研究。结果表明:在激励器能量沉积比确定的条件下,等离子体合成射流激励器的放电能量与激励频率无关,然而不同能量沉积比都存在一个最佳激励频率,使得射流速度达到最大。在激励特性诊断的基础上通过风洞实验验证了等离子体合成射流改善狭缝式S弯进气道气动性能的有效性,最佳激励效果为在出口速度为Ma=0.25时使得总压畸变指数降低22.59%。

基于GStreamer的嵌入式流媒体播放器的设计

本文主要研究了基于GStreamer的流媒体播放器的设计,该设计的关键在于实现流媒体传输功能的RTP/RTCP插件的构建,并为RTP/RTCP插件找到了一种在嵌入式环境下可以实现的、简单、稳定的自适应拥塞控制算法。

UNIX中STREAMS机构的流控机制

STREAMS 机构是 UNIX 系统V3.0及其以后版本所增加的新功能,它是 UNIX 中为支持网络服务和数据通信驱动器而开发的内核机构。本文全面地讨论了 STREAMS 机构中流控机制的实现问题,并给出了相应的实现程序。这些程序在 SUN3/160上运行良好。

基于Control-mind数控系统的电液束设备控制功能开发

现有的电液束加工设备存在控制可扩展性不够、无对刀功能、加工孔的入口孔型一致性难以得到保证、人工输入及修改数控程序时易出现错误等问题。基于Control-mind数控系统,开发出具有定制界面和特定功能的新电液束加工设备,以满足新的加工工艺需求。

Adaptive rate control on wireless transcoder

To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dynamically determining the transcoder＇s objective bit rate, according to the bandwidth variation of the wireless channel and the buffer occupancy. Then the transient performance, steady performance, and computational complexity of the algorithm are analyzed. Finally, the experiment results demonstrate that the algorithm can improve the synthetic performance of rate control through the compromise between the end-to-end delay and the playout quality.

Wireless Hybrid QoS Architecture with an Enhancement of Fair Intelligent Congestion Control

More subtle and explicit QoS control mechanisms are required at the radio access level, even though the simple and scalable Differentiated Services (DiffServ) QoS control model is acceptable for the core of the network. At the radio access level, available resources are severely limited and the degree of traffic aggregation is not significant, thus rendering the DiffServ principles less effective. In this paper we present a suitable hybrid QoS architecture framework to address the problem. At the wireless access end, the local QoS mechanism is designed in the context of IEEE 802.11 WLAN with 802.11e QoS extensions;so streams of those session-based applications are admitted, established according to the traffic profile they require, and guaranteed. As the core in the Admission Control of the hybrid QoS architecture, the Fair Intelligent Congestion Control (FICC) algorithm is applied to provide fairness among traffic aggregates and control congestion at the bottleneck interface between the wireless link and the network core via mechanisms of packet scheduling, buffer management, feedback and adjustments. It manages effectively the overloading scenario by preventing traffic violation from uncontrolled traffic, and providing guarantee to the priority traffic in terms of guaranteed bandwidth allocation and specified delay.

The Nonlinear Filter Boolean Function of LILI-128 Stream Cipher Generator Is Successfully Broken Based on the Complexity of Nonlinear 0 1 Symbol Sequence

The nonlinear filter Boolean function of LILI-128 stream cipher generator is studied in this paper. First we measure the complexity of the stream ciphers sequence of LILI-128 stream cipher generator and obtain the shortest bit stream sequence reconstructed Boolean function of nonlinear filter in LILI-128 stream cipher generator. Then the least nonlinear Boolean function of generating stream cipher sequence is reconstructed by clusterig, nonlinear predictive and nonlinear synchronization from shortest bit stream sequence. We have verified the correctness of our reconstruction result by simulating the block diagram of Lili-128 keystream generator using our getting Boolean function and implement designers’ reference module of Lili-128 stream cipher public online, and two methods produce the same synchronous keystream sequence under same initial state, so that our research work proves that the nonlinear Boolean function of LILI-128 stream cipher generator is successfully broken.

QUALITY-AWARE CROSS-LAYER SCHEDULING FOR ROBUST VIDEO STREAMING OVER WIRELESS CHANNELS

In the case of video streaming over wireless channels, burst errors may lead to serious video quality degradation. By jointly exploiting the scheduling mechanism on different communication layers, this paper proposes a quality-aware cross-layer scheduling scheme to achieve unequal error control for each Latency-constraint Frame Set (LFS) of a video stream. After a network-layer agent at base station firstly utilizes the network-layer packet scheduling to provide packet-granularity importance classifi-cation for the current LFS, a link-layer agent at base station further utilizes the Radio-Link-Unit (RLU) scheduling to implement finer selective retransmission of the current LFS. Under scheduling delay and bandwidth constraints, the proposed scheme can be aware of the application-layer quality and time-varying channel conditions, and hence burst errors can simply be shifted to lower-priority transmission units in the current LFS. Simulation results demonstrate that the proposed scheme has strong robustness against burst errors, and thus improves the overall received quality of the video stream over wireless channels.

Estimating Reduced-Reference Video Quality for Quality-Based Streaming Video

Reduced-reference （RR） video-quality estimators send a small signature to the receiver. This signature comprises the original video content as well as the video stream. RR quality estimation provides reliability and involves a small data payload. While significant in theory, RR estimators have only recently been used in practice for quality monitoring and adaptive system con- trol in streaming-video frameworks. In this paper, we classify RR algorithms according to whether they are based on a） model- ing the signal distortion, b） modeling the human visual system, or c） analyzing the video signal source. We review proposed RR techniques for monitoring and controlling quality in streaming video systems.

Content-adaptive robust error concealment for packet-lossy H.264 video streaming

In this paper, we present a spatio-temporal post-processing error concealment (EC) algorithm designed initially for a H.264 video-streaming scheme over packet-lossy networks. It aims at optimizing the subjective quality of the restored video under the constraints of low delay and computational complexity, which are critical to real-time applications and portable devices having limited resources. Specifically, it takes into consideration the physical property of motion field in order to achieve more meaningful perceptual video quality, in addition to the improved objective PSNR. Further, a simple bilinear spatial interpolation approach is combined with the improved boundary-match (B-M) based temporal EC approach according to texture and motion activity analysis. Finally, we propose a low complexity temporal EC method based on motion vector interpolation as a replacement of the B-M based approach in the scheme under low-computation requirement, or as a complement to further improve the scheme's performance in applications having enough computation resources. Extensive experiments demonstrated that the proposal features not only better reconstruction, objectively and subjectively, than JM benchmark, but also robustness to different video sequences.

实现重症医学科导管相关血流零感染不是梦

导管相关血流感染(catheter related blood stream infection, CRBSI)是重症医学科的常见并发症,可导致患者住院时间延长、医疗费用增加,甚至发生脓毒症致使死亡率增加。CRBSI的感染控制已成为重症医学科乃至医院管理的重点及质量控制的核心。目前,重症医学科的CRBSI预防方案已基本完善,并建立了中心静脉导管置入和维护的国家标准,这些规范的建立和实施可有效降低CRBSI的发生率。重症医学科的CRBSI问题广泛存在且后果严重,表明临床中心静脉置管及使用过程中的无菌操作存在缺陷,针对其操作流程进行改进,从理论、管理、教育、规范、监督等多个层面努力,完善和落实各项感染控制要求,可有效避免和减少CRBSI的发生,甚至实现零感染。

多工序制造中的误差流模型及其应用研究进展

航空发动机结构件、汽车车身等复杂产品通常为多工序制造件,其制造过程中多种误差的产生和累积会对产品质量产生耦合影响,使产品质量控制处于暗箱状态。将误差流理论与精度控制理论、工程数据处理方法相结合,构建对误差的传递、累积、湮灭进行描述和分析的误差流模型对于多工序制造复杂产品质量控制具有重要意义。因此,总结和归纳了误差流模型的构建方法及其应用研究,提出了多工序制造的误差流模型质量控制总体框架,从小数据驱动的时间序列数学解析模型和大数据驱动的复杂网络统计分析模型两个方面对多工序制造的误差流模型进行了分类综述。最后,展望了误差流模型在高端装备和复杂产品等未来多工序制造领域中的发展趋势。

超重力⁃水热法制备形貌可控的钛酸锶钡粉体

零维和多维结构的钛酸锶钡(Ba_(1-x)Sr_(x)TiO_(3),BST)粉体分别具有高比表面积和高长径比的优势,为提升材料性能并扩大电子元件中原材料的工业化应用,改善粉体制备过程中分布不均、耗时长的问题,采用撞击流-旋转填料床(IS-RPB)结合水热法制备了添加丙三醇的BST粉体,考察了水热温度、水热时间及丙三醇添加量等因素对BST粉体形貌的影响规律。结合X-射线衍射仪(XRD)、扫描电子显微镜(SEM)以及透射电子显微镜(TEM)对BST粉体的形貌、晶相及组成进行了表征分析。结果表明:在超重力因子为40、撞击初速度10.61m/s、水热温度180℃、水热时间12h的条件下,当添加少量丙三醇时,其充当分散剂的作用,所制得的BST粉体为均匀性与分散性良好的纳米球形颗粒;当添加较多丙三醇时,其充当溶剂的作用,在水热条件下沿单元晶面生长得到了片状及花状形貌。本文提出的超重力-水热法及丙三醇的添加对于工业化形貌可控制备BST粉体探索提供了一种方便快捷的途径。