Parallel Algorithms for Image Template Matching on Hypercube SIMD Computers

This correspondence presents several parallel algorithms for image template matching on an SIMD array processor with a hypercube interconnection network. For an N by N image and an M by M window, the time complexity is reduced from O(N2M2) for the serial algorithm to O(M2/K2 + M * log2 N/K + log2 N * log2 K) for the N2K2-PE system (1 ? K ? M), or to O(N2M2/L2) for the L2-PE system (L ? N). With efficient use of the inter-PE communication network, each PE requires only a small local memory, many unnecessary data transmissions are eliminated, and the time complexity is greatly reduced.     

A sliding memory plane array processor

A mesh-connected single-input multiple-data (SIMD) architecture called a sliding memory plane (SliM) array processor is proposed. Differing from existing mesh-connected SIMD architectures, SliM has several salient features such as a sliding memory plane that provides inter-PE communication during computation. Two I/O planes provide an I/O overlapping capability. Thus, inter-PE communication and I/O overhead can be overlapped with computation. Inter-PE communication time is invisible in most image processing tasks because the computation time is larger than the communication time on SliM. The ability to overlap inter-PE communication with computation, regardless of window size and shape and without using a coprocessor or an on-chip DMA controller is unique to SliM     

Implementation of a Sliding Memory Plane Image Processor

This paper presents architectures and implementation of a Sliding Memory Plane (SliM) Image Processor to build a SIMD parallel computer. The paper also proposes an enhanced multiplication algorithm to reduce the gate count and the number of cycles. The SliM chip consists of mesh-connected 5×5 PEs. Due to the idea ofsliding, that is, overlapping the inter-PE communication time with the computation time, SliM can greatly reduce the inter-PE communication overhead. In addition, four operations corresponding to ALU, shift, data I/O, and inter-PE communication can be grouped into an instruction to be executed in a cycle simultaneously. The implemented SliM chip operates at 25 MHz and gives 625 MIPS. Because of a mesh topology, a large number of chips can be easily connected to form a SIMD parallel computer. We have implemented the scalable SliM Array Processor and developed parallel algorithms for real-time image processing.     

Q-PSO: Fast Quaternion-Based Pose Estimation from RGB-D Images

This paper investigates the leader–follower formation control problem for a group of networked nonholonomic mobile robots that are subject to bounded time-varying communication delays and an asynchronous clock. First we convert the formation control problem into a trajectory tracking problem, and then a fully distributed unified control framework based on the receding horizon control is implemented to converge the tracking errors. By adding an auxiliary acceleration term into the receding horizon controller, the framework is able to solve the impractical velocity jump problem. Considering the time-varying delays, the timing and order features of the messages are utilized to guarantee their logical correctness. To compensate for the delay effect, an improved control framework that exploits the predictability of the receding horizon controller is proposed. The asynchronous clock problem, which makes the communication delay unmeasurable, is studied. We give a definition of the syn point that is inspired from investigation of the property that messages are received out of order in a bounded time-varying delayed network. A novel method that detects the occurrence of syn points is integrated into the control framework to solve the asynchronous clock problem. Finally the effectiveness of the proposed approaches is demonstrated in the Player/Stage simulation environment.     

基于绘图板程序的家政机器人室内定位系统实现

针对目前家政服务机器人在可视化定位上的不足,提出一种将房屋布局图加载到上位机绘图板程序中,通过在上位机上绘制路线,实时控制家政服务机器人位置的方案.在该系统中,上位机按照RS-232协议传输路线信息到无线模块并发送,机器人端采用Ahera公司的SoPC技术,使用Nios Ⅱ软核作为核心处理器读取无线模块接收到的信息,并...     

Multimodal messages: the pen and voice opportunity

Analyses of the costs and benefits of asynchronous communication, and the complementary properties of writing and speech, are used to predict that messages containing both writing and speech will be more communicative than either medium alone. Two experimental studies of asynchronous messaging are presented. Both experiments examine the use of pen-and-voice messages, that is voice messages attached to ‘scribbled’, i.e., uninterpreted text. The control conditions were voice messages alone, equivalent to an answerphone, and scribbled messages alone, equivalent to a fax. In Experiment 1 the visual component of the pen-and-voice messages was static, in Experiment 2 users could record short ‘movies’ including speech and pen movements over a document surface. Users showed a significant preference for the pen-and-voice messages in both experiments. In Experiment 2 half the number of pen-and-voice messages were required to achieve the same task performance as in the control conditions. It is concluded that dynamic pen-and-voice messages have considerable potential advantages over current single medium asynchronous communication facilities such as fax, answerphone, voicemail and e-mail.     

一种串口与远程GPRS设备通信适配器的设计与开发

工业现场内置GPRS设备种类众多,技术人员需要分别使用各厂家的上位机软件对设备进行远程监控.为了解决这个不兼容问题,基于Modbus和Modbus TCP协议设计并实现了串口通讯软件与远程GPRS设备通信适配器.串口通讯软件将控制和数据采集的Modbus报文发送给适配器,适配器维护GPRS设备列表,将串口报文转为Mod...     

Two techniques for improving performance on bus-based multiprocessors

In this paper, we explore two techniques for reducing memory latency in bus-based multiprocessors. The first one, designed for sector caches, is a snoopy cache coherence protocol that uses a large transfer block to take advantage of spatial locality, while using a small coherence block (called a subblock) to avoid false sharing. The second technique is read snarfing (or read broadcasting), in which all caches can acquire data transmitted in response to a read request to update invalid blocks in their own cache.

We evaluated the two techniques by simulating 6 applications that exhibit a variety of reference patterns. We compared the performance of the new protocol against that of the Illinois protocol with both small and large block sizes and found that it was effective in reducing memory latency and providing more consistent, good results than the Illinois protocol with a given line size. Read snarfing also improved performance mostly for protocols that use large line sizes.     

Steganography via running short text messages

Steganography, or covert communication between two parties through public channels, has been received a lot of attention, since the mere existence of encrypted message might cause suspicion and could even provide useful information to eavesdroppers. In some cases, secret information needs to be covertly broadcast to receivers in multiple locations at the same time. In this paper, we propose a novel steganographic scheme, which covertly sends secret message to multiple receivers via a stream of running short text messages displayed on a media output screen, assuming appropriate optical character recognition (OCR) functionality at the decoder. We use Thai language short text messages as a case study. We analyze the characteristics of Thai short text messages and introduce some effective message-to-bit transformation methods. We find that one Thai short text message can be transformed into multiple secret bits. In principle, the proposed transformation methods can be applied to short text messages in any language. We use a provably secure construction that guarantees covertness, privacy, and authenticity of the secret data against active attacks. In an experimental evaluation, we show that four secret message bits can be embedded in each short text message. In addition, we find that the embedded bits can be retrieved correctly and easily by human observers without OCR functionality at the decoder. Thus, the scheme is practical and effective for covert communication from one sender to multiple receivers over public channels.     

存储器替换机制及其实现

提出一种解决PACT01一种结合动态可编程逻辑阵列(DPGA)的处理器的新型体系结制中cache的一致性与同步性问题的算法,并且解决多线程支持的快速上下文切换及快速用户级操作问题。存储器替换机制是解决cache的一致性问题及当cache未命中时从局部或远程存储器到cacbe存储器的数据替换问题的一种硬件实现方法,产生冲突的原因是由于多线程并行的写入／读取的位置相同和读或写的位置相同。文中选择的是相联映射策略,同时也选择了最少最近使用LRU算法,即在cache未命中时替换最少最近使用的参考块,为实现LRU算法设置了与每块相对应的计数器。     

基于ZYNQ的千兆以太网数据记录器设计

针对航空航天领域飞行器传感数据信息采集、存储和传输等需求,设计了基于ZYNQ的千兆以太网数据记录器。以ZYNQ为主控芯片,通过以太网接口实时接收数据包,编码后写入缓存单元,逻辑端提取缓存数据写入eMMC存储单元,并可读取eMMC内存储数据经以太网接口传回电脑,用于数据验证、分析。试验结果表明,该记录器实现了千兆网TCP通信,读、写平均速率达到500 Mbit/s,以太网包解析后数据以60 MB/s平均速度写入存储单元,瞬时写入最大速度可达100 MB/s。系统将主控与存储单元分离,便于对存储单元进行过载保护,用于实验后回收数据,为高过载情况下飞行器数据记录提供解决方案。     

A protocol to achieve independence in constant rounds

Independence is a fundamental property needed to achieve security in fault-tolerant distributed computing. In practice, distributed communication networks are neither fully synchronous or fully asynchronous, but rather loosely synchronized. By this, we mean that in a communication protocol, messages at a given round may depend on messages from other players at the same round. These possible dependencies among messages create problems if we need n players to announce independently chosen values. This task is called simultaneous broadcast. In this paper, we present the first constant round protocol for simultaneous broadcast in a reasonable computation model (which includes a common shared random string among the players). The protocol is provably secure under general cryptographic assumptions. In the process, we develop a new and stronger formal definition for this problem. Previously known protocols for this task required either O(log n) or expected constant rounds to complete (depending on the computation model considered)     

高可靠性控制系统容错设计模式的新发展

在建立高可靠性控制系统的过程中，提出了一种基于软件冗余的容错模式——流程对模式，该模式虽然具有故障恢复时间短等优点，但是无法解决校验点信息在传输过程中出错或接收不完全的问题。针对上述问题应用LDPC码将主服务器发送到备用服务器中的校验点信息进行通信编码，并采用RS码将备用服务器接收到的校验点信息进行本地编码，分析结果表明改进方法可以有效解决前述问题，进一步增强了控制系统的可靠性。     

残疾人呼叫系统研究与设计

呼叫系统的主要功能是残疾人的手持呼叫终端通过GPS从卫星获取坐标数据,将位置信息通过移动网络或短信发送至政府调度部门或其监护人手持设备中.其中监护人端设备将直接读取短信坐标并显示位置,同时提醒其进行救助,政府调度部门接收信号将与数据库比对从而对该残疾人提供针对性的帮助.     

MDICA: Maintenance of data integrity in column-oriented database applications

Current information technologies generate large amounts of data for management or further analysis, storing it in NoSQL databases which provide horizontal scaling and high performance, supporting many read/write operations per second. NoSQL column-oriented databases, such as Cassandra and HBase, are usually modelled following a query-driven approach, resulting in denormalized databases where the same data can be repeated in several tables. Therefore, maintaining data integrity relies on client applications to ensure that, for data changes that occur, the affected tables will be appropriately updated. We devise a method called MDICA that, given a data insertion at a conceptual level, determines the required actions to maintain database integrity in column-oriented databases. This method is implemented for Cassandra database applications. MDICA is based on the definition of (1) rules to determine the tables that will be impacted by the insertion, (2) procedures to generate the statements to ensure data integrity and (3) messages to warn the user about errors or potential problems. This method helps developers in two ways: generating the statements needed to maintain data integrity and producing messages to avoid problems such as loss of information, redundant repeated data or gaps of information in tables.     

镇定网络化线性系统的数据率定理

传统控制理论研究如何利用反馈信息实现控制目标,且通常假定通信链路的物理局限性对控制系统没有显著影响.通信理论研究如何将信息从信道的一端可靠地传输到另一端,但忽略传输信息的具体用途.因此,控制和通信在过去是两门相对独立发展的学科.网络化控制系统的涌现促使研究者综合利用控制和通信理论来刻画反馈通信网络对控制系统的影响.本文回顾了基于数字通信网络的离散线性系统的可镇定性问题.特别地,基于信息理论的控制方法,讨论了镇定网络化线性系统所需的最低通信数据率问题.结果表明,最低数据率本质上取决于开环系统的拓扑熵率.     

Unicast-based multicast communication in wormhole-routed networks

Multicast communication, in which the same message is delivered from a source node to an arbitrary number of destination nodes, is being increasingly demanded in parallel computing. System supported multicast services can potentially offer improved performance, increased functionality, and simplified programming, and may in turn be used to support various higher-level operations for data movement and global process control. This paper presents efficient algorithms to implement multicast communication in wormhole-routed direct networks, in the absence of hardware multicast support, by exploiting the properties of the switching technology. Minimum-time multicast algorithms are presented for n-dimensional meshes and hypercubes that use deterministic, dimension-ordered routing of unicast messages. Both algorithms can deliver a multicast message to m-1 destinations in [log ₂ m] message passing steps, while avoiding contention among the constituent unicast messages. Performance results of implementations on a 64-node nCUBE-2 hypercube and a 168-node Symult 2010 2-D mesh are given     

无线 Ad hoc 网络和传感网络中基于位置的、可靠的无信标传输路由方法

Existing position-based routing algorithms, where packets are forwarded in the geographic direction of the destination, normally require that the forwarding node should know the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages that each node sends out periodically. Several beaconless greedy routing schemes have been proposed recently. However, none of the existing beaconless schemes guarantee the delivery of packets. Moreover, they incur communication overhead by sending excessive control messages or by broadcasting data packets. In this paper, we describe how existing localized position based routing schemes that guarantee delivery can be made beaconless, while preserving the same routes. In our guaranteed delivery beaconless routing scheme, the next hop is selected through the use of control RTS/CTS messages and biased timeouts. In greedy mode, the neighbor closest to destination responds first. In recovery mode, nodes closer to the source will select shorter timeouts, so that other neighbors, overhearing CTS packets, can eliminate their own CTS packets if they realize that their link to the source is not part of Gabriel graph. Nodes also cancel their packets after receiving data message sent by source to the selected neighbor. We analyze the behavior of our scheme on our simulation environment assuming ideal MAC, following GOAFR+ and GFG routing schemes. Our results demonstrate low communication overhead in addition to guaranteed delivery.     

Political mobilization through social network sites: The mobilizing power of political messages received from SNS friends

Recent political communication scholarship has examined whether social network sites (SNSs) contribute to political participation. Regarding SNSs’ mobilization effect, however, mixed results have been reported. This study, relying on representative survey data from the 2012 South Korean general election, investigates interplay between three factors influencing electoral participation: (1) type of SNS use (i.e., political versus nonpolitical use), (2) user characteristics (i.e., past voters versus nonvoters), and (3) directionality of SNS messages (i.e., messages received from versus those sent to SNS friends). Results indicate SNSs’ mobilization effect emerges when conditions are met. Voting intention is increased among past nonvoters who use SNSs through political messages received from their SNS friends. Theoretical and practical implications of SNSs’ mobilization effect are discussed.