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Sample records for improved packet forwarding

  1. DPDK-based Improvement of Packet Forwarding

    Directory of Open Access Journals (Sweden)

    Bi Hao

    2016-01-01

    Full Text Available Reel-time processing of packets occupies a significant position in the field of computer network security. With theexplosive growth of the backbone link rate,which is consistent with Gilder's law, many bottlenecks of server performance leave the real-time data stream unprocessed.Thus, we proposedto take use of DPDK(Data Plan Development Kit framework to achieve an intelligent NIC packet forwarding system. During this research, we deeply analysis the forwarding process of packet in DPDK and improve its DMA mode.According to the results of experiment, the system greatly enhanced the performance of packet forwarding,and the throughput of forwarding 64-byet or random-length packets by 20Gbit NIC reaches13.3Gbps and 18.7Gbps(dual ports forwarding.

  2. An improved packet structure

    KAUST Repository

    Bader, Ahmed

    2014-05-22

    A multihop network transmits a packet including a RACH area and a hop number. The RACH area includes a list of subcarriers. A source node in the network dynamically determines the size of the RACH area. A node in the network performs an open-loop transmit power control.

  3. Efficient Packet Forwarding in Mesh Network

    CERN Document Server

    Kanrar, Soumen

    2012-01-01

    Wireless Mesh Network (WMN) is a multi hop low cost, with easy maintenance robust network providing reliable service coverage. WMNs consist of mesh routers and mesh clients. In this architecture, while static mesh routers form the wireless backbone, mesh clients access the network through mesh routers as well as directly meshing with each other. Different from traditional wireless networks, WMN is dynamically self-organized and self-configured. In other words, the nodes in the mesh network automatically establish and maintain network connectivity. Over the years researchers have worked, to reduce the redundancy in broadcasting packet in the mesh network in the wireless domain for providing reliable service coverage, the source node deserves to broadcast or flood the control packets. The redundant control packet consumes the bandwidth of the wireless medium and significantly reduces the average throughput and consequently reduces the overall system performance. In this paper I study the optimization problem in...

  4. REDUCING BURST PACKET LOSS THROUGH ROUTE-FREE FORWARDING

    Institute of Scientific and Technical Information of China (English)

    Ma Hailong; Guo Yunfei; Cheng Dongnian; Zhang Jianwei

    2010-01-01

    It is well known that today's inter-domain routing protocol,Border Gateway Protocol (BGP),converges slowly during network failures. Due to the distribution nature of Internet routing decisions and the rate-limiting timer Minimum Route Advertisement Interval (MRAI) of BGP,unavoidable convergence latency is introduced in reaction to network changes. During the period of convergence temporarily routing table inconsistencies cause short-term routing blackholes and loops which result in widespread temporary burst packet loss. In this paper,we present ROute-Free Forwarding (ROFF) - a novel technique for packet delivering continuously during periods of convergence. With slightly modifications on IP packet header and BGP,route loops and blackholes can be avoided. Our preliminary evaluation demonstrates that ROFF succeeds in reducing the number of Autonomous Systems (ASes) which experience burst packet loss and the duration of packet loss.

  5. Fast Packet forwarding Engine Based on Software Circuits

    NARCIS (Netherlands)

    Makkes, M.X.; Varabanescu, A.; Laat, C. de; Meijer, R.J.

    2015-01-01

    Forwarding packets is part of the performance critical path of routing devices, and affects the network performance at any scale. This operation is typically performed by dedicated routing boxes, which are fast, but expensive and inflexible. Recent work has shown that in many cases commodity

  6. Fast Packet forwarding Engine Based on Software Circuits

    NARCIS (Netherlands)

    Makkes, M.X.; Varabanescu, A.; Laat, C. de; Meijer, R.J.

    2015-01-01

    Forwarding packets is part of the performance critical path of routing devices, and affects the network performance at any scale. This operation is typically performed by dedicated routing boxes, which are fast, but expensive and inflexible. Recent work has shown that in many cases commodity hardwar

  7. Fast Packet forwarding Engine Based on Software Circuits

    NARCIS (Netherlands)

    Makkes, M.X.; Varabanescu, A.; Laat, C. de; Meijer, R.J.

    2015-01-01

    Forwarding packets is part of the performance critical path of routing devices, and affects the network performance at any scale. This operation is typically performed by dedicated routing boxes, which are fast, but expensive and inflexible. Recent work has shown that in many cases commodity hardwar

  8. Efficient Packet Forwarding Approach in Vehicular Ad Hoc Networks Using EBGR Algorithm

    CERN Document Server

    Prasanth, K; Jayasudha, K; Chandrasekar, C

    2010-01-01

    VANETs (Vehicular Ad hoc Networks) are highly mobile wireless ad hoc networks and will play an important role in public safety communications and commercial applications. Routing of data in VANETs is a challenging task due to rapidly changing topology and high speed mobility of vehicles. Conventional routing protocols in MANETs (Mobile Ad hoc Networks) are unable to fully address the unique characteristics in vehicular networks. In this paper, we propose EBGR (Edge Node Based Greedy Routing), a reliable greedy position based routing approach to forward packets to the node present in the edge of the transmission range of source/forwarding node as most suitable next hop, with consideration of nodes moving in the direction of the destination. We propose Revival Mobility model (RMM) to evaluate the performance of our routing technique. This paper presents a detailed description of our approach and simulation results show that packet delivery ratio is improved considerably compared to other routing techniques of V...

  9. Efficient Packet Forwarding Approach in Vehicular Ad Hoc Networks Using EBGR Algorithm

    Directory of Open Access Journals (Sweden)

    K. Jayasudha

    2010-01-01

    Full Text Available VANETs (Vehicular Ad hoc Networks are highly mobile wireless ad hoc networks and will play an important role in public safety communications and commercial applications. Routing of data in VANETs is a challenging task due to rapidly changing topology and high speed mobility of vehicles. Conventional routing protocols in MANETs (Mobile Ad hoc Networks are unable to fully address the unique characteristics in vehicular networks. In this paper, we propose EBGR (Edge Node Based Greedy Routing, a reliable greedy position based routing approach to forward packets to the node present in the edge of the transmission range of source/forwarding node as most suitable next hop, with consideration of nodes moving in the direction of the destination. We propose Revival Mobility model (RMM to evaluate the performance of our routing technique. This paper presents a detailed description of our approach and simulation results show that packet delivery ratio is improved considerably compared to other routing techniques of VANET.

  10. Gateway Node-Based Greedy Routing Algorithm for Efficient Packet Forwarding in Vehicular Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Mohamed Abbas A,

    2011-05-01

    Full Text Available In recent years, vehicular communications are one of the hottest research topics. It has also gained much attention in industry as well as academia. Vehicular Ad Hoc Networks (VANETs are advances of the wireless communication technologies. Routing is one of the key research issues in VANETs as long as it plays an important role in public safety and commercial applications. In VANET, routing of data is a challenging task due to high speed of nodes (i.e., vehicles movement and rapidly changing topology. Recent research showedthat existing routing algorithm solutions for Mobile Ad Hoc Networks (MANETs are not able to meet the unique requirements of vehicular networks. In this paper, we propose Gateway Node-Based Greedy Routing(GNGR, a reliable greedy position-based routing approach algorithm. In GNGR, we forward the packets to any of the nodes in the corner of the transmission range of source/forwarding node as most suitable next hop. With this consideration, the nodes move towards the direction of the destination. We propose Dynamic TransitionMobility Model (DTMM to evaluate our routing technique. This paper gives a complete description of our packet forwarding approach and simulation results. The simulation results are carried out based on Packet Delivery Ratio (PDR. Our routing technique is compared with other routing techniques; the PDR is improved significantly compared with other routing techniques of VANET.

  11. Novel Scheme for Packet Forwarding without Header Modifications in Optical Networks

    DEFF Research Database (Denmark)

    Wessing, Henrik; Christiansen, Henrik Lehrmann; Fjelde, Tina

    2002-01-01

    We present a novel scheme for packet forwarding in optical packet-switched networks and we further demonstrate its good scalability through simulations. The scheme requires neither header modification nor any label distribution protocol, thus reducing component cost while simplifying network...

  12. Packet transfer delay analysis of the RPR rings in the store-and-forward architecture

    Science.gov (United States)

    Yang, Yi; Cao, Mingcui; Huang, Ping

    2005-02-01

    RRP has two means to transmit data: store-and-forward and cut-through. In this paper, the high and low priority packet transfer delay of the N nodes Resilient Packet Rings (RPR) in store-and-forward architecture is analyzed based on the queuing theory. According to queuing theory, we set up the nodes model and analyzed the factors that influenced the packet transfer delay in a constrained condition. By calculation and simulation, the result indicates that both high priority and low priority packets" delay increase with the node number N of the RPR rings. The high priority traffic has less packet delay than the low priority traffic at the same node number N. The increase of the low priority transfer delay is much larger than the high priority traffic with the increase of the node number.

  13. Energy based reliable multicast routing protocol for packet forwarding in MANET

    Directory of Open Access Journals (Sweden)

    S. Gopinath

    2015-06-01

    Full Text Available Mobile Ad hoc Network consists of mobile nodes without any assisting infrastructure. Mobility of nodes causes network partition. This leads to heavy overhead and less packet forwarding ratio. In this research work, Residual Energy based Reliable Multicast Routing Protocol (RERMR is proposed to attain more network lifetime and increased packet delivery and forwarding rate. A multicast backbone is constructed to achieve more stability based on node familiarity and trustable loop. Reliable path criterion is estimated to choose best reliable path among all available paths. Data packets will be forwarded once the reliable path is chosen. We have also demonstrated that residual energy of paths aids to provide maximum network lifetime. Based on the simulation results, the proposed work achieves better performance than previous protocols in terms of packet reliability rate, network stability rate, end to end delay, end to end transmission and communication overhead.

  14. An Efficient Multi-Carrier Position-Based Packet Forwarding Protocol For Wireless Sensor Networks

    CERN Document Server

    Bader, Ahmed; Alouini, Mohamed-Slim

    2011-01-01

    Beaconless position-based forwarding protocols have recently evolved as a promising solution for packet forwarding in wireless sensor networks. However, as the node density grows, the overhead incurred in the process of relay selection grows significantly. As such, end-to-end performance in terms of energy and latency is adversely impacted. With the motivation of developing a packet forwarding mechanism that is tolerant to node density, an alternative position-based protocol is proposed in this paper. In contrast to existing beaconless protocols, the proposed protocol is designed such that it eliminates the need for potential relays to undergo a relay selection process. Rather, any eligible relay may decide to forward the packet ahead, thus significantly reducing the underlying overhead. The operation of the proposed protocol is empowered by exploiting favorable features of orthogonal frequency division multiplexing (OFDM) at the physical layer. The end-to-end performance of the proposed protocol is evaluated...

  15. Efficient packet forwarding using cyber-security aware policies

    Energy Technology Data Exchange (ETDEWEB)

    Ros-Giralt, Jordi

    2017-04-04

    For balancing load, a forwarder can selectively direct data from the forwarder to a processor according to a loading parameter. The selective direction includes forwarding the data to the processor for processing, transforming and/or forwarding the data to another node, and dropping the data. The forwarder can also adjust the loading parameter based on, at least in part, feedback received from the processor. One or more processing elements can store values associated with one or more flows into a structure without locking the structure. The stored values can be used to determine how to direct the flows, e.g., whether to process a flow or to drop it. The structure can be used within an information channel providing feedback to a processor.

  16. Coalition Games with Cooperative Transmission: A Cure for the Curse of Boundary Nodes in Selfish Packet-Forwarding Wireless Networks

    CERN Document Server

    Han, Zhu

    2008-01-01

    In wireless packet-forwarding networks with selfish nodes, application of a repeated game can induce the nodes to forward each others' packets, so that the network performance can be improved. However, the nodes on the boundary of such networks cannot benefit from this strategy, as the other nodes do not depend on them. This problem is sometimes known as {\\em the curse of the boundary nodes}. To overcome this problem, an approach based on coalition games is proposed, in which the boundary nodes can use cooperative transmission to help the backbone nodes in the middle of the network. In return, the backbone nodes are willing to forward the boundary nodes' packets. Here, the concept of core is used to study the stability of the coalitions in such games. Then three types of fairness are investigated, namely, min-max fairness using nucleolus, average fairness using the Shapley function, and a newly proposed market fairness. Based on the specific problem addressed in this paper, market fairness is a new fairness c...

  17. Coalition Games with Cooperative Transmission: A Cure for the Curse of Boundary Nodes in Selfish Packet-Forwarding Wireless Networks

    CERN Document Server

    Han, Zhu

    2007-01-01

    In wireless packet-forwarding networks with selfish nodes, applications of a repeated game can induce the nodes to forward each others' packets, so that the network performance can be improved. However, the nodes on the boundary of such networks cannot benefit from this strategy, as the other nodes do not depend on them. This problem is sometimes known as the curse of the boundary nodes. To overcome this problem, an approach based on coalition games is proposed, in which the boundary nodes can use cooperative transmission to help the backbone nodes in the middle of the network. In return, the backbone nodes are willing to forward the boundary nodes' packets. The stability of the coalitions is studied using the concept of a core. Then two types of fairness, namely, the min-max fairness using nucleolus and the average fairness using the Shapley function are investigated. Finally, a protocol is designed using both repeated games and coalition games. Simulation results show how boundary nodes and backbone nodes f...

  18. An efficient multi-carrier position-based packet forwarding protocol for wireless sensor networks

    KAUST Repository

    Bader, Ahmed

    2012-01-01

    Beaconless position-based forwarding protocols have recently evolved as a promising solution for packet forwarding in wireless sensor networks. However, as the node density grows, the overhead incurred in the process of relay selection grows significantly. As such, end-to-end performance in terms of energy and latency is adversely impacted. With the motivation of developing a packet forwarding mechanism that is tolerant to variation in node density, an alternative position-based protocol is proposed in this paper. In contrast to existing beaconless protocols, the proposed protocol is designed such that it eliminates the need for potential relays to undergo a relay selection process. Rather, any eligible relay may decide to forward the packet ahead, thus significantly reducing the underlying overhead. The operation of the proposed protocol is empowered by exploiting favorable features of orthogonal frequency division multiplexing (OFDM) at the physical layer. The end-to-end performance of the proposed protocol is evaluated against existing beaconless position-based protocols analytically and as well by means of simulations. The proposed protocol is demonstrated in this paper to be more efficient. In particular, it is shown that for the same amount of energy the proposed protocol transports one bit from source to destination much quicker. © 2012 IEEE.

  19. Forwarding techniques for IP fragmented packets in a real 6LoWPAN network.

    Science.gov (United States)

    Ludovici, Alessandro; Calveras, Anna; Casademont, Jordi

    2011-01-01

    Wireless Sensor Networks (WSNs) are attracting more and more interest since they offer a low-cost solution to the problem of providing a means to deploy large sensor networks in a number of application domains. We believe that a crucial aspect to facilitate WSN diffusion is to make them interoperable with external IP networks. This can be achieved by using the 6LoWPAN protocol stack. 6LoWPAN enables the transmission of IPv6 packets over WSNs based on the IEEE 802.15.4 standard. IPv6 packet size is considerably larger than that of IEEE 802.15.4 data frame. To overcome this problem, 6LoWPAN introduces an adaptation layer between the network and data link layers, allowing IPv6 packets to be adapted to the lower layer constraints. This adaptation layer provides fragmentation and header compression of IP packets. Furthermore, it also can be involved in routing decisions. Depending on which layer is responsible for routing decisions, 6LoWPAN divides routing in two categories: mesh under if the layer concerned is the adaptation layer and route over if it is the network layer. In this paper we analyze different routing solutions (route over, mesh under and enhanced route over) focusing on how they forward fragments. We evaluate their performance in terms of latency and energy consumption when transmitting IP fragmented packets. All the tests have been performed in a real 6LoWPAN implementation. After consideration of the main problems in forwarding of mesh frames in WSN, we propose and analyze a new alternative scheme based on mesh under, which we call controlled mesh under.

  20. Utilization of OFDM for efficient packet forwarding in wireless sensor networks

    KAUST Repository

    Bader, Ahmed

    2011-12-01

    Beaconless position-based forwarding protocols have recently evolved as a promising solution for packet forwarding in wireless sensor networks. However, as the network density grows, the overhead incurred grows significantly. As such, end-to-end energy and delay performance is adversely impacted. Motivated by the need for a forwarding mechanism that is more tolerant to growth in node density, an alternative position-based protocol is proposed in this paper. The protocol is designed such that it completely eliminates the need for potential relays to undergo a relay election process. Rather, any eligible relay may decide to forward the packet ahead, thus significantly reducing the overhead. The operation of the proposed protocol is empowered by exploiting favorable features of orthogonal frequency division multiplexing (OFDM) at the physical layer. End-to-end performance is evaluated here against existing beaconless protocols. It is demonstrated that the proposed protocol is more efficient since it is able to offer lower end-to-end delay for the same amount of energy consumption. © 2011 IEEE.

  1. Improving AODV Performance using Dynamic Density Driven Route Request Forwarding

    CERN Document Server

    Kanakaris, Venetis; Ovaliadis, Kyriakos

    2011-01-01

    Ad-hoc routing protocols use a number of algorithms for route discovery. Some use flooding in which a route request packet (RREQ) is broadcasted from a source node to other nodes in the network. This often leads to unnecessary retransmissions, causing congestion and packet collisions in the network, a phenomenon called a broadcast storm. This paper presents a RREQ message forwarding scheme for AODV that reduces routing overheads. This has been called AODV_EXT. Its performance is compared to that of AODV, DSDV, DSR and OLSR protocols. Simulation results show that AODV_EXT achieves 3% energy efficiency, 19.5% improvement in data throughput and 69.5% reduction in the number of dropped packets for a network of 50 nodes. Greater efficiency is achieved in high density network and marginal improvement in networks with a small number of nodes.

  2. Performance improvement for optical packet switch with shared buffers

    Institute of Scientific and Technical Information of China (English)

    Junjie Yang; Qingji Zeng; Jie Li; Tong Ye; Guolong Zhu

    2005-01-01

    @@ In this paper, an inner wavelength method is proposed to enlarge buffering capacity of shared fiber delay line buffers. In addition, an optical packet switch called extended shared buffer type optical packet switch(extended SB-OPS) is proposed to realize the inner wavelength method. In order to further improve performance of extended SB-OPS, a greedy algorithm based on inner wavelength method is introduced.The performance of extended SB-OPS is evaluated by simulation experiments.

  3. IMPROVEMENT OF TCAM-BASED PACKET CLASSIFICATION ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    Xu Zhen; Zhang Jun; Rui Liyang; Sun Jun

    2008-01-01

    The feature of Ternary Content Addressable Memories (TCAMs) makes them particularly attractive for IP address lookup and packet classification applications in a router system. However, the limitations of TCAMs impede their utilization. In this paper, the solutions for decreasing the power consumption and avoiding entry expansion in range matching are addressed. Experimental results demonstrate that the proposed techniques can make some big improvements on the performance of TCAMs in IP address lookup and packet classification.

  4. An Improved Dynamic Probabilistic Packet Marking for IP Traceback

    Directory of Open Access Journals (Sweden)

    Qiao Yan

    2010-12-01

    Full Text Available An improved dynamic probabilistic packet marking algorithm named IDPPM is presented, which not only can locate and attack a source rapidly and accurately, but also can reduce the marking overhead of routers near the attackers, which is its greatest contribution given by our technique. In contrast to previous work, the challenge of weakest node and weakest link is solved with the price of a little more numbers of packets to reconstruct the attack path. Theoretical analysis and NS2 simulation results in IPv4 and IPv6 testify that the approach is feasible and efficient respectively.

  5. Research and improvement on packet capture mechanism in linux for high-speed network

    Institute of Scientific and Technical Information of China (English)

    YANG Wu; FANG Bin-xing; YUN Xiao-chun; ZHANG Hong-li

    2005-01-01

    With the increasing enlargement of network scale and the rapid development of network techniques,large numbers of the network applications begin to appear. Packet capture plays an important role as one basic technique used in each field of the network applications. In a high-speed network, the heavy traffic of network transmission challenges the packet capture techniques. This paper does an in-depth analysis on the traditional packet capture mechanisms in Linux, and then measures the performance bottleneck in the process of packet capture. The methods for improving the packet capture performance are presented and an optimized packet capture scheme is also designed and implemented. The test demonstrates that the new packet capture mechanism (Libpacket) can greatly improve the packet capture performance of the network application systems in a highspeed network.

  6. I-Min: An Intelligent Fermat Point Based Energy Efficient Geographic Packet Forwarding Technique for Wireless Sensor and Ad Hoc Networks

    CERN Document Server

    Ghosh, Kaushik; Das, and Pradip K; 10.5121/jgraphoc.2010.2204

    2010-01-01

    Energy consumption and delay incurred in packet delivery are the two important metrics for measuring the performance of geographic routing protocols for Wireless Adhoc and Sensor Networks (WASN). A protocol capable of ensuring both lesser energy consumption and experiencing lesser delay in packet delivery is thus suitable for networks which are delay sensitive and energy hungry at the same time. Thus a smart packet forwarding technique addressing both the issues is thus the one looked for by any geographic routing protocol. In the present paper we have proposed a Fermat point based forwarding technique which reduces the delay experienced during packet delivery as well as the energy consumed for transmission and reception of data packets.

  7. Discrete Packet Analysis for Improved Atmospheric Rejection on Modulated Laser Signals

    Energy Technology Data Exchange (ETDEWEB)

    O& #x27; Neill, M., McKenna, I., DiBenedetto, J., Capelle, G., Trainham, R.

    2012-07-19

    This slide-show discusses how the method of discrete packet analysis improves atmospheric compensation for quasi-CW fluorescence detection methods. This is key to improving remote sensing capabilities.

  8. Improving Packet Processing Efficiency on Multi-core Architectures with Single Input Queue

    Directory of Open Access Journals (Sweden)

    Peter Orosz

    2012-06-01

    Full Text Available Generic purpose multi-core PC architectures are facing performance challenges of high rate packet reception on gigabit per second and higher speed network interfaces. In order to assign a CPU core to a networking softIRQ, the single input queue design of the low-level packet processing subsystem relies on the kernel's Symmetric Multiprocessing (SMP scheduler, which does not perform load balancing of the softIRQ instances between the CPU cores. In practice, when single receive queue is used all of the softIRQs are assigned to a single CPU core. This typical arrangement could easily drive to CPU resource exhaustion and high packet loss ratio on high bandwidth interfaces. The non-steady state of the system is triggered by the high arrival rate of the packets. This work presents a proposal for improving the packet processing efficiency in single input queue multi-core systems.

  9. Improved Multiple Descriptions Sinusoidal Coder Adaptive to Packet Loss Rate

    Institute of Scientific and Technical Information of China (English)

    LANG Yue; WANG Jing; ZHAO Sheng-hui; KUANG Jing-ming

    2008-01-01

    To make the multiple descriptions codec adaptive to the packet loss rate, which can minimize the final distortion, a novel adaptive multiple descriptions sinusoidal coder (AMDSC) is proposed, which is based on a sinusoidal model and a noise model. Firstly, the sinusoidal parameters are extracted in the sinusoidal model, and ordered in a decrease manner. Odd indexed and even indexed parameters are divided into two descriptions. Secondly, the output vector from the noise model is split vector quantized. And the two sub-vectors are placed into two descriptions too. Finally, the number of the extracted parameters and the redundancy between the two descriptions are adjusted according to the packet loss rate of the network. Analytical and experimental results show that the proposed AMDSC outperforms existing MD speech coders by taking network loss characteristics into account. Therefore, it is very suitable for unreliable channels.

  10. Detection of Packet Dropping Attack Using Improved Acknowledgement Based Scheme in MANET

    Directory of Open Access Journals (Sweden)

    Aishwarya Sagar Anand Ukey

    2010-07-01

    Full Text Available Mobile Ad hoc NETwork (MANET is self configuring network of mobile node connected by wireless links and considered as network without infrastructure. Routing protocol plays a crucial role for effective communication between mobile nodes and operates on the basic assumption that nodes are fully cooperative. Because of open structure and limited battery-based energy some nodes (i.e. selfish or malicious may not cooperate correctly. After becoming part of active path, theses nodes start refusing to forward or drop data packets thereby degrades the performance of network. In this paper, a new reputation based approach is proposed that deals with such routing misbehavior and consists of detection and isolation of misbehaving nodes. Proposed approach can be integrated on top of any source routing protocol and based on sending acknowledgement packets and counting the number of data packets of active path.

  11. A novel lost packets recovery scheme based on visual secret sharing

    Science.gov (United States)

    Lu, Kun; Shan, Hong; Li, Zhi; Niu, Zhao

    2017-08-01

    In this paper, a novel lost packets recovery scheme which encrypts the effective parts of an original packet into two shadow packets based on (2, 2)-threshold XOR-based visual Secret Sharing (VSS) is proposed. The two shadow packets used as watermarks would be embedded into two normal data packets with digital watermarking embedding technology and then sent from one sensor node to another. Each shadow packet would reveal no information of the original packet, which can improve the security of original packet delivery greatly. The two shadow packets which can be extracted from the received two normal data packets delivered from a sensor node can recover the original packet lossless based on XOR-based VSS. The Performance analysis present that the proposed scheme provides essential services as long as possible in the presence of selective forwarding attack. The proposed scheme would not increase the amount of additional traffic, namely, lower energy consumption, which is suitable for Wireless Sensor Network (WSN).

  12. Novel scheme for efficient and cost-effective forwarding of packets in optical networks without header modification

    DEFF Research Database (Denmark)

    Wessing, Henrik; Fjelde, Tina; Christiansen, Henrik Lehrmann

    2001-01-01

    We present a novel scheme for addressing the outputs in optical packet switches and demonstrate its good scalability. The scheme requires neither header modification nor distribution of routing information to the packet switches, thus reducing optical component count while simplifying network...

  13. Improving Packet Processing Performance in the ATLAS FELIX Project

    CERN Document Server

    Schumacher, Jorn; The ATLAS collaboration; Borga, Andrea; Boterenbrood, Hendrik; Chen, Hucheng; Chen, Kai; Drake, Gary; Francis, David; Gorini, Benedetto; Lanni, Francesco; Lehmann Miotto, Giovanna; Levinson, Lorne; Narevicius, Julia; Roich, Alexander; Ryu, Soo; Schreuder, Frans Philip; Vandelli, Wainer; Zhang, Jinlong; Vermeulen, Jos

    2015-01-01

    Experiments in high-energy physics (HEP) and related fields often impose constraints and challenges on data acquisition systems. As a result, these systems are implemented as unique mixtures of custom and commercial-off-the-shelf electronics (COTS), involving and connecting radiation-hard devices, large high-performance networks, and computing farms. FELIX, the Frontend Link Exchange, is a new PC-based general purpose data routing device for the data-acquisition system of the ATLAS experiment at CERN. Performance is a very crucial point for devices like FELIX, which have to be capable of processing tens of gigabyte of data per second. Thus it is important to understand the performance limitations for typical workloads on modern hardware. We present an analysis of a packet processing algorithm that is used in FELIX, and show how the PC system's memory architecture plays a key factor in the overall data throughput achieved by the application. Finally, we present optimizations that increase the processing throug...

  14. Improving Packet Processing Performance of a Memory-Bounded Application

    CERN Document Server

    Schumacher, Jorn; The ATLAS collaboration; Borga, Andrea; Boterenbrood, Hendrik; Chen, Hucheng; Chen, Kai; Drake, Gary; Francis, David; Gorini, Benedetto; Lanni, Francesco; Lehmann Miotto, Giovanna; Levinson, Lorne; Narevicius, Julia; Roich, Alexander; Ryu, Soo; Schreuder, Frans Philip; Vandelli, Wainer; Zhang, Jinlong; Vermeulen, Jos

    2015-01-01

    Experiments in high-energy physics (HEP) and related fields often impose constraints and challenges on data acquisition systems. As a result, these systems are implemented as unique mixtures of custom and commercial-off-the-shelf electronics (COTS), involving and connecting radiation-hard devices, large high-performance networks, and computing farms. FELIX, the Frontend Link Exchange, is a new PC-based general purpose data routing device for the data-acquisition system of the ATLAS experiment at CERN. Performance is a very crucial point for devices like FELIX, which have to be capable of processing tens of gigabyte of data per second. Thus it is important to understand the performance limitations for typical workloads on modern hardware. We present an analysis of a packet processing algorithm that is used in FELIX, and show how the PC system's memory architecture plays a key factor in the overall data throughput achieved by the application. Finally, we present optimizations that increase the processing throug...

  15. Improved optical packet switching structure with recirculation buffer and feedback tunable wavelength converter

    Institute of Scientific and Technical Information of China (English)

    Cheng Wu; Shilin Xiao

    2009-01-01

    The performance of an optical switching network is mainly determined by its core node structure.An improved optical packet switching(OPS)node structure based on recirculation optical fiber delay line(FDL)and feedback tunable wavelength converter(TWC),and a specific scheduling algorithm for the node structure are presented.This switching structure supports both point-to-point and point-to-multi-points broadcasting transmission with superior capacity expansion performance.Its superiority in packet loss probability is proved by simulation.

  16. Research on Packet Forwarding Among Virtual Routers in Identic Logic Network%面向虚拟路由器间传输机制的研究

    Institute of Scientific and Technical Information of China (English)

    甘宏; 潘丹

    2015-01-01

    When multiple virtual routers in identic logic network cohabit a shared router platform of physical network, proposes an Interiorly Fast Forwarding Technique based on study of Open Shortest Past First and investigation in generation of FIB. This technique is proved in which reducing delay is the yardstick of solving fast forwarding among multiple virtual routers. Its purpose is to eliminate the hops of packet forwarding and to advance the speed of packet transmitting. Meanwhile, this technique enhances network robustness by reducing network loss ratio that caused by single point of failure.%针对在同一逻辑网络中的多个虚拟路由器映射到物理网络中同一台路由器情形,结合IP开放式最短路径优先协议,分析路由表生成过程,提出一种针对在同一逻辑网络中虚拟路由器间的内部快速交换技术,称为IFFT。该技术实现报文在虚拟路由器间的快速传输,减少报文转发的跳数,提高报文传输速度。同时,该技术能降低单点故障造成的丢包率,从而增强网络的特性。

  17. FPGA Implementation of a Fixed Latency Scheme in a Signal Packet Router for the Upgrade of ATLAS Forward Muon Trigger Electronics

    CERN Document Server

    INSPIRE-00225390; Hu, Xueye; Schwarz, Thomas; Zhu, Junjie; Chapman, J.W.; Dai, Tiesheng; Zhou, Bing

    2015-01-01

    We propose a new fixed latency scheme for Xilinx gigabit transceivers that will be used in the upgrade of the ATLAS forward muon spectrometer at the Large Hadron Collider. The fixed latency scheme is implemented in a 4.8 Gbps link between a frontend data serializer ASIC and a packet router. To achieve fixed latency, we use IO delay and dedicated carry in resources in a Xilinx FPGA, while minimally relying on the embedded features of the FPGA transceivers. The scheme is protocol independent and can be adapted to FPGA from other vendors with similar resources. This paper presents a detailed implementation of the fixed latency scheme, as well as simulations of the real environment in the ATLAS forward muon region.

  18. Improved forwarding control design method and its application

    Institute of Scientific and Technical Information of China (English)

    Chen Yimei; Han Zhengzhi; Cai Xiushan

    2006-01-01

    Integrator forwarding is a recursive nonlinear design technique for the stabilization of feed-forward systems.However, this method still has some limitation. An improved design method is proposed to extend the field of application of this technique. This method is used to design a stabilizer for the inertia wheel pendulum system. Moreover, it is shown that the control Lyapunov function which is obtained from this method can also be used to design a globally asymptotically stabilizing controller with optimality.

  19. Packet Scheduling in High-speed Networks Using Improved Weighted Round Robin

    Directory of Open Access Journals (Sweden)

    Guikai Liu

    2014-03-01

    Full Text Available A variety of applications with different QoS requirements are supported simultaneously in the high-speed packet-switched networks, packet scheduling algorithms play a critical role in guaranteeing the performance of routing and switching devices. This study presents a simple, fair, efficient and easily implementary scheduling algorithm, called Successive Minimal-weight Round Robin (SMRR. In each round, SMRR provides the same service opportunity, which is equivalent to the minimal weight of the current round, for all active data flows. On the basis of the concept of Latency-Rate (LR servers, we obtain the upper bound on the latency of SMRR and WRR (Weighted Round Robin respectively and the results indicate that SMRR makes a significant improvement on the latency bound in comparison to WRR. We also discuss the fairness and implementation complexity of SMRR and the theoretical analysis shows that SMRR preserves the good implementation complexity of O (1 with respect to the number of flows and has better fairness than WRR.

  20. An Improved Speech Enhancement Method based on Teager Energy Operator and Perceptual Wavelet Packet Decomposition

    Directory of Open Access Journals (Sweden)

    Huan Zhao

    2011-06-01

    Full Text Available According to the distribution characteristic of noise and clean speech signal in the frequency domain, a new speech enhancement method based on teager energy operator (TEO and perceptual wavelet packet decomposition (PWPD is proposed. Firstly, a modified Mask construction method is made to protect the acoustic cues at the low frequencies. Then a level-dependent parameter is introduced to further adjust the thresholds in light of the noise distribution feature. At last the sub-bands which have very little influence are set directly 0 to improve the signal-to-noise ratio (SNR and reduce the computation load. Simulation results show that, under different kinds of noise environments, this new method not only enhances the signal-to-noise ratio (SNR and perceptual evaluation of speech quality (PESQ, but also reduces the computation load, which is very advantageous for real-time realizing.

  1. Intelligent Packet Shaper to Avoid Network Congestion for Improved Streaming Video Quality at Clients

    DEFF Research Database (Denmark)

    Kaul, Manohar; Khosla, Rajiv; Mitsukura, Y

    2003-01-01

    This paper proposes a traffic shaping algorithm based on neural networks, which adapts to a network over which streaming video is being transmitted. The purpose of this intelligent shaper is to eradicate all traffic congestion and improve the end-user's video quality. It possesses the capability...... to predict, to a very high level of accuracy, a state of congestion based upon the training data collected about the network behaviour. Initially, the current traffic shaping technologies are discussed and later a simulation in a controlled environment is illustrated to exhibit the effects...... of this intelligent traffic-shaping algorithm on the underlying network real time packet traffic and the eradication of unwanted abruption in the streaming video qualiy. This paper concluded from the end results of the simulation that neural networks are a very superior means of modeling real-time traffic...

  2. E-model MOS Estimate Improvement through Jitter Buffer Packet Loss Modelling

    Directory of Open Access Journals (Sweden)

    Adrian Kovac

    2011-01-01

    Full Text Available Proposed article analyses dependence of MOS as a voice call quality (QoS measure estimated through ITU-T E-model under real network conditions with jitter. In this paper, a method of jitter effect is proposed. Jitter as voice packet time uncertainty appears as increased packet loss caused by jitter memory buffer under- or overflow. Jitter buffer behaviour at receiver’s side is modelled as Pareto/D/1/K system with Pareto-distributed packet interarrival times and its performance is experimentally evaluated by using statistic tools. Jitter buffer stochastic model is then incorporated into E-model in an additive manner accounting for network jitter effects via excess packet loss complementing measured network packet loss. Proposed modification of E-model input parameter adds two degrees of freedom in modelling: network jitter and jitter buffer size.

  3. Improved Packet Forwarding Approach in Vehicular Ad Hoc Networks Using RDGR Algorithm

    CERN Document Server

    Prasanth, K; Jayasudha, K; Chandrasekar, Dr C; 10.5121/ijngn.2010.2106

    2010-01-01

    VANETs (Vehicular Ad hoc Networks) are highly mobile wireless ad hoc networks and will play an important role in public safety communications and commercial applications. Routing of data in VANETs is a challenging task due to rapidly changing topology and high speed mobility of vehicles. Position based routing protocols are becoming popular due to advancement and availability of GPS devices. One of the critical issues of VANETs are frequent path disruptions caused by high speed mobility of vehicle that leads to broken links which results in low throughput and high overhead . This paper argues the use of information on vehicles' movement information (e.g., position, direction, speed of vehicles) to predict a possible link-breakage event prior to its occurrence. So in this paper we propose a Reliable Directional Greedy routing (RDGR), a reliable position based routing approach which obtains position, speed and direction of its neighboring nodes from GPS. This approach incorporates potential score based strategy...

  4. Improved Genetic Algorithm Optimization for Forward Vehicle Detection Problems

    Directory of Open Access Journals (Sweden)

    Longhui Gang

    2015-07-01

    Full Text Available Automated forward vehicle detection is an integral component of many advanced driver-assistance systems. The method based on multi-visual information fusion, with its exclusive advantages, has become one of the important topics in this research field. During the whole detection process, there are two key points that should to be resolved. One is to find the robust features for identification and the other is to apply an efficient algorithm for training the model designed with multi-information. This paper presents an adaptive SVM (Support Vector Machine model to detect vehicle with range estimation using an on-board camera. Due to the extrinsic factors such as shadows and illumination, we pay more attention to enhancing the system with several robust features extracted from a real driving environment. Then, with the introduction of an improved genetic algorithm, the features are fused efficiently by the proposed SVM model. In order to apply the model in the forward collision warning system, longitudinal distance information is provided simultaneously. The proposed method is successfully implemented on a test car and evaluation experimental results show reliability in terms of both the detection rate and potential effectiveness in a real-driving environment.

  5. Improving TCP Throughput Using Modified Packet Reordering Technique (MPRT Over Manets

    Directory of Open Access Journals (Sweden)

    Prakash B. Khelage

    2014-08-01

    Full Text Available at the beginning of development of network technology TCP transport agent were designed assuming that communication is using wired network, but recently there is huge demand and use of wireless networks for communication. Those TCP variants which are successful in wired networks are neither able to detect exact causes of packet losses nor unnecessary transmission delays over wireless networks. The biggest challenge over MANET is design of robust and reliable TCP variant which should give best performance in different network scenarios. Till date more than dozens of TCP variants designed and modified by researcher and scientist communities even though the level of TCP performance have to be optimum in different scenarios, Such as congestion, link failure, signal loss and interferences. Over rod, grid and bulk network model also. As some of TCP-variant performs well in particular network scenarios but degrades in other scenarios. The objective of this research work, to modify packet reordering technique based TCP variant, implement and compare its performance with other variants. Validation of basic and main network model done using network simulator (NS2 and calculated throughput, delay and packet drop by processing trace files. The simulated result shows that, proposed technique performs outstanding almost in all network scenarios with minimum packet losses and minimum delay.

  6. A Packet Routing Model for Computer Networks

    Directory of Open Access Journals (Sweden)

    O. Osunade

    2012-05-01

    Full Text Available The quest for reliable data transmission in today’s computer networks and internetworks forms the basis for which routing schemes need be improved upon. The persistent increase in the size of internetwork leads to a dwindling performance of the present routing algorithms which are meant to provide optimal path for forwarding packets from one network to the other. A mathematical and analytical routing model framework is proposed to address the routing needs to a substantial extent. The model provides schemes typical of packet sources, queuing system within a buffer, links and bandwidth allocation and time-based bandwidth generator in routing chunks of packets to their destinations. Principal to the choice of link are such design considerations as least-congested link in a set of links, normalized throughput, mean delay and mean waiting time and the priority of packets in a set of prioritized packets. These performance metrics were targeted and the resultant outcome is a fair, load-balanced network.

  7. New efficiency algorithm for flooding the packet in wireless ad hoc networks

    Science.gov (United States)

    Lee, Kyuhwan; Ma, Joongsoo

    2002-08-01

    This paper proposes a novel flooding algorithm based on an existing IEEE 802.11 MAC protocol in wireless ad hoc networks. Currently when we use the multi-hop routing algorithm, such as the Ad hoc On-demand Distance Vector (AODV) algorithm, the Cluster-Based Routing Protocol (CBRP) and so on, we frequently use the broadcast packet in order to get the topology information. At this time all nodes receiving the packet try to forward the received packet to other nodes. If a number of nodes are located in the sender's coverage, the channel is busy due to the delivery of the received packet. With respect to the coverage of the IEEE 802.11, the utilization factor of the wireless network is decreased because of occupying the channel to distribute the received packet. Thus we propose the new algorithm to resolve this problem. In this algorithm, each node maintains a table of immediate neighbors as well as each neighbor's neighbors. When each node receiving broadcast packets in the sender's coverage forwards the packets, it decides whether to forward them or not by comparing the neighbor list of receiver with that of sender. The proposed algorithm can increase the network efficiency due to the decrease in frequency of broadcast packets in the multi-hop routing protocol. Finally, we evaluate the improved performance through the simulation.

  8. Improving Packet Delivery Performance of Publish/Subscribe Protocols in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Ernesto García Davis

    2013-01-01

    Full Text Available MQTT-S and CoAP are two protocols able to use the publish/subscribe model in Wireless Sensor Networks (WSNs. The high scalability provided by the publish/subscribe model may incur a high packet loss and therefore requires an efficient reliability mechanism to cope with this situation. The reliability mechanism of MQTT-S and CoAP employs a method which defines a fixed value for the retransmission timeout (RTO. This article argues that this method is not efficient for deploying publish/subscribe in WSN, because it may be unable to recover a packet, therefore resulting in a lower packet delivery ratio (PDR at the subscriber nodes. This article proposes and evaluates an adaptive RTO method, which consists in using a Smooth Round-trip Time and multiplying it by a constant parameter (K. Thanks to this method, the reliability mechanism of MQTT-S and CoAP would be able to react properly to packet loss and would also be lightweight in terms of energy, memory and computing for sensor nodes where these resources are critical. We present a detailed evaluation of the effects of the K value on the calculation of the adaptive RTO method. We also establish the setting for obtaining the highest PDR on the subscriber nodes for single-hop and multi-hop scenarios. The results for single-hop scenario show that use of the appropriate K value for the adaptive RTO method increases the PDR up to 76% for MQTT-S and up to 38% for CoAP when compared with the use of fixed RTO method for both protocols, respectively. Meanwhile the same comparison for multi-hop scenario, the adaptive RTO method increases the PDR up to 36% for MQTT-S and up to 14% for CoAP.

  9. Improving packet delivery performance of publish/subscribe protocols in wireless sensor networks.

    Science.gov (United States)

    Davis, Ernesto García; Calveras, Anna; Demirkol, Ilker

    2013-01-04

    MQTT-S and CoAP are two protocols able to use the publish/subscribe model in Wireless Sensor Networks (WSNs). The high scalability provided by the publish/subscribe model may incur a high packet loss and therefore requires an efficient reliability mechanism to cope with this situation. The reliability mechanism of MQTT-S and CoAP employs a method which defines a fixed value for the retransmission timeout (RTO). This article argues that this method is not efficient for deploying publish/subscribe in WSN, because it may be unable to recover a packet, therefore resulting in a lower packet delivery ratio (PDR) at the subscriber nodes. This article proposes and evaluates an adaptive RTO method, which consists in using a Smooth Round-trip Time and multiplying it by a constant parameter (K). Thanks to this method, the reliability mechanism of MQTT-S and CoAP would be able to react properly to packet loss and would also be lightweight in terms of energy, memory and computing for sensor nodes where these resources are critical. We present a detailed evaluation of the effects of the K value on the calculation of the adaptive RTO method. We also establish the setting for obtaining the highest PDR on the subscriber nodes for single-hop and multi-hop scenarios. The results for single-hop scenario show that use of the appropriate K value for the adaptive RTO method increases the PDR up to 76% for MQTT-S and up to 38% for CoAP when compared with the use of fixed RTO method for both protocols, respectively. Meanwhile the same comparison for multi-hop scenario, the adaptive RTO method increases the PDR up to 36% for MQTT-S and up to 14% for CoAP.

  10. Improving Packet Delivery Performance of Publish/Subscribe Protocols in Wireless Sensor Networks

    Science.gov (United States)

    Davis, Ernesto García; Calveras, Anna; Demirkol, Ilker

    2013-01-01

    MQTT-S and CoAP are two protocols able to use the publish/subscribe model in Wireless Sensor Networks (WSNs). The high scalability provided by the publish/subscribe model may incur a high packet loss and therefore requires an efficient reliability mechanism to cope with this situation. The reliability mechanism of MQTT-S and CoAP employs a method which defines a fixed value for the retransmission timeout (RTO). This article argues that this method is not efficient for deploying publish/subscribe in WSN, because it may be unable to recover a packet, therefore resulting in a lower packet delivery ratio (PDR) at the subscriber nodes. This article proposes and evaluates an adaptive RTO method, which consists in using a Smooth Round-trip Time and multiplying it by a constant parameter (K). Thanks to this method, the reliability mechanism of MQTT-S and CoAP would be able to react properly to packet loss and would also be lightweight in terms of energy, memory and computing for sensor nodes where these resources are critical. We present a detailed evaluation of the effects of the K value on the calculation of the adaptive RTO method. We also establish the setting for obtaining the highest PDR on the subscriber nodes for single-hop and multi-hop scenarios. The results for single-hop scenario show that use of the appropriate K value for the adaptive RTO method increases the PDR up to 76% for MQTT-S and up to 38% for CoAP when compared with the use of fixed RTO method for both protocols, respectively. Meanwhile the same comparison for multi-hop scenario, the adaptive RTO method increases the PDR up to 36% for MQTT-S and up to 14% for CoAP. PMID:23291579

  11. Intelligent Packet Shaper to Avoid Network Congestion for Improved Streaming Video Quality at Clients

    DEFF Research Database (Denmark)

    Kaul, Manohar; Khosla, Rajiv; Mitsukura, Y

    2003-01-01

    to predict, to a very high level of accuracy, a state of congestion based upon the training data collected about the network behaviour. Initially, the current traffic shaping technologies are discussed and later a simulation in a controlled environment is illustrated to exhibit the effects...... of this intelligent traffic-shaping algorithm on the underlying network real time packet traffic and the eradication of unwanted abruption in the streaming video qualiy. This paper concluded from the end results of the simulation that neural networks are a very superior means of modeling real-time traffic...

  12. Parallel Packet Forwarding for High End Routers%高性能路由器中的并行包转发机制研究

    Institute of Scientific and Technical Information of China (English)

    李胜磊; 张德运; 刘刚

    2003-01-01

    The invention and evolution of the Dense Wavelength Division Multiplexing (DWDM)technology have brought a breakthrough to high-speed networks ,and it has put a lot of pressure on research in the area of IP routers.Besides ,with up-coming Quality of Service requirements raised by a wide range of communication intensive ,the next-generation IP routers should be QoS-capable. In this paper,we propose a architecture called the Parallel QoS-capable IP Router (PQIR). We address one key design issue in our architecture - the distribution of IP packets to multiple independent routing agents so that the workload at routing agents is balanced and the packet ordering is preserved. We introduce the Enhanced Hash-based Distributing Scheme (EHDS)as the solution. Simulations are carried out to study the effectiveness of EHDS. The results show that EHDS does meet our design goals very well.

  13. BER IMPROVEMENT OF WIRELESS LAN IEEE 802.11 STANDARD USING WAVELET PACKET TRANSFORMS

    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar

    2012-09-01

    Full Text Available High data rates and spectral efficiency is the main requirements for wireless communication systems. Orthogonal Frequency Division Multiplexing (OFDM is a special form of multi carrier transmission used to achieve high data rates of the various WLAN standards. WLAN uses an Inverse Fast Fourier Transform (IFFT at the transmitter to modulate a high bit-rate signal onto a number of carriers and ensure orthogonality between the carriers. The FFT-OFDM has a disadvantage that it is inherently inflexible and requires a complex IFFT core. Recently, Wavelet Packet Transform is proposed as an alternate to FFT. It is a multiplexing method in which data is assigned to wavelet sub bands having different time and frequency resolutions. This paper presents a BER analysis of Fourier-based OFDM (FFT-OFDM and Wavelet Packet based OFDM (WPT-OFDM in WLAN standard (IEEE 802.11a. The performance of FFT and WPT OFDM for various modulation techniques such as PSK, DPSK and QAM for varying values of M was evaluated in AWGN Channel.

  14. A Novel Method of Fault Diagnosis for Rolling Bearing Based on Dual Tree Complex Wavelet Packet Transform and Improved Multiscale Permutation Entropy

    Directory of Open Access Journals (Sweden)

    Guiji Tang

    2016-01-01

    Full Text Available A novel method of fault diagnosis for rolling bearing, which combines the dual tree complex wavelet packet transform (DTCWPT, the improved multiscale permutation entropy (IMPE, and the linear local tangent space alignment (LLTSA with the extreme learning machine (ELM, is put forward in this paper. In this method, in order to effectively discover the underlying feature information, DTCWPT, which has the attractive properties as nearly shift invariance and reduced aliasing, is firstly utilized to decompose the original signal into a set of subband signals. Then, IMPE, which is designed to reduce the variability of entropy measures, is applied to characterize the properties of each obtained subband signal at different scales. Furthermore, the feature vectors are constructed by combining IMPE of each subband signal. After the feature vectors construction, LLTSA is employed to compress the high dimensional vectors of the training and the testing samples into the low dimensional vectors with better distinguishability. Finally, the ELM classifier is used to automatically accomplish the condition identification with the low dimensional feature vectors. The experimental data analysis results validate the effectiveness of the presented diagnosis method and demonstrate that this method can be applied to distinguish the different fault types and fault degrees of rolling bearings.

  15. Application and improvement of wavelet packet de-noising in satellite transponder

    Institute of Scientific and Technical Information of China (English)

    Yannian Lou; Chaojie Zhang; Xiaojun Jin; Zhonghe Jin

    2015-01-01

    The satel ite transponder is a widely used module in satel ite missions, and the most concerned issue is to reduce the noise of the transferred signal. Otherwise, the telemetry signal wil be pol uted by the noise contained in the transferred signal, and the additional power wil be consumed. Therefore, a method based on wavelet packet de-noising (WPD) is introduced. Compared with other techniques, there are two features making WPD more suit-able to be applied to satel ite transponders: one is the capability to deal with time-varying signals without any priori information of the input signals; the other is the capability to reduce the noise in band, even if the noise overlaps with signals in the frequency domain, which provides a great de-noising performance especial y for wideband signals. Besides, an oscil ation detector and an av-eraging filter are added to decrease the partial oscil ation caused by the thresholding process of WPD. Simulation results show that the proposed algorithm can reduce more noises and make less distortions of the signals than other techniques. In addition, up to 12 dB additional power consumption can be reduced at –10 dB signal-to-noise ratio (SNR).

  16. Trade-Offs between Energy Saving and Reliability in Low Duty Cycle Wireless Sensor Networks Using a Packet Splitting Forwarding Technique

    Directory of Open Access Journals (Sweden)

    Leonardi Alessandro

    2010-01-01

    Full Text Available One of the challenging topics and design constraints in Wireless Sensor Networks (WSNs is the reduction of energy consumption because, in most application scenarios, replacement of power resources in sensor devices might be unfeasible. In order to minimize the power consumption, some nodes can be put to sleep during idle times and wake up only when needed. Although it seems the best way to limit the consumption of energy, other performance parameters such as network reliability have to be considered. In a recent paper, we introduced a new forwarding algorithm for WSNs based on a simple splitting procedure able to increase the network lifetime. The forwarding technique is based on the Chinese Remainder Theorem and exhibits very good results in terms of energy efficiency and complexity. In this paper, we intend to investigate a trade-off between energy efficiency and reliability of the proposed forwarding scheme when duty-cycling techniques are considered too.

  17. Improved Multicast Traffic Scheduling Scheme in the Packet-Switching Systems

    Institute of Scientific and Technical Information of China (English)

    SONG Mei-na; SONG Jun-de; LI Hong-wen

    2004-01-01

    This paper proposes a new switching scheme of switch fabric, which is named Multicast-enabled Protocol Agnostic Forwarding Engine (M-PAFE). M-PAFE is a central scheduling crossbar-based switch fabric with embedded Combined Input and Output Queue from the queuing view. An extra switching path is dedicated for multicast cell processing in M-PAFE. And the simulation results are provided to evaluate the performance of M-PAFE in comparison with ESLIP, which is a well-known algorithm implemented in Cisco 12000 routers.

  18. Multipath packet switch using packet bundling

    DEFF Research Database (Denmark)

    Berger, Michael Stubert

    2002-01-01

    The basic concept of packet bundling is to group smaller packets into larger packets based on, e.g., quality of service or destination within the packet switch. This paper presents novel applications of bundling in packet switching. The larger packets created by bundling are utilized to extend...... switching capacity by use of parallel switch planes. During the bundling operation, packets will experience a delay that depends on the actual implementation of the bundling and scheduling scheme. Analytical results for delay bounds and buffer size requirements are presented for a specific scheduling...

  19. ENERGY EFFICIENT IMPROVEMENT GEOCAST FORWARDING IN MANET BASED ON A CLUSTERED STRUCTURE

    Directory of Open Access Journals (Sweden)

    PRASANTH K.

    2015-09-01

    Full Text Available Mobile sinks (MSs are very important in many wireless sensor network (WSN applications for efficient data gathering, restricted sensor reprogramming, and for characteristic and revoking compromised sensors. This paper presents a secure and energy-efficient geocast forwarding for MANET based on a hierarchical clustered structure with reduction of packet dropping from the base station (BS and access Point (AP all nodes placed in one or more geocast regions. Our protocol is composed of two major parts which are protects from attackers and allow over all energy savings. First of all the hierarchical formation based on cliques and a concept of data aggregation allows us to build a robust, fast and secure foundation for routing of information. Next geocast diffusion itself provides data forwarding and reduced a research phase in the network that is a step of sending data(s. Our protocol performs better in terms of less broadcast rounds overhead. For security a three-tier general framework is used, that permit utilize of any pair wise key pre distribution plan as its indispensable component. The innovative framework requires two disconnect key pools, solitary for to access the network, and one for pair wise key establishment between the sensors. To decrease the compensation caused by reproduction attacks we encompass strengthened the authentication device between the sensor nodes and the stationary access node (AP in the planned framework. Through in depth analysis, we show that our security framework has top network flexibility to a mobile sink reproduction attack as compared to the two-tier general frame work. The analysis is done using network simulator 2 (NS2 and it is a packet level simulator with trace level analysis.

  20. Two Novel Structures of Optical Packet Switching Nodes

    Institute of Scientific and Technical Information of China (English)

    YIN Hongxi; XU Anshi; WU Deming

    2001-01-01

    All-optical packet switching networkis currently one of the research hotspots of all-opticalcommunication networks and optical packet switchingnodes are the key technique of optical packet switch-ing network. In this paper, two novel structures ofoptical packet switching nodes are put forward, and the switching capacity of the node and the packet con-tention resolution are analyzed. These two switchingarchitectures can realize wavelength routing switchingfunction and broadcast-and-select switching functionrespectively. They are simple but efficient for realizingoptical packet switching network.

  1. Intrusion Detection Systems Based On Packet Sniffing

    Directory of Open Access Journals (Sweden)

    Ushus Maria Joseph

    2013-01-01

    Full Text Available In the present era of networks, security of network systems is becoming increasingly important, as more and more sensitive information is being stored and manipulated online. The paper entitled ’Packet Sniffing’ is a IDS where it monitors packets on the network wire and attempts to the discovery of hacker/cracker who is attempting to break into system. Packet Sniffing also finds the contents and tracks the data packet in the network system. This sniffing is being performed by comparing the captured packet with the intruder details stored in the database .If the packet is found to be an intruder it is then forwarded to the firewall with the respective message for blocking. The Emotional Ants module contains the sender and receiver .The sender will inform all the other Ants running in other machines about the detection of intruder through his pheromone (Messages. The receiver in Ants will listen for the messages from other Ants

  2. 拍卖机制的包转发路由模型及其仿真研究%Auction mechanism for packet forwarding routing model and simulation study

    Institute of Scientific and Technical Information of China (English)

    徐名霞

    2012-01-01

    In this paper,with the idea of the auction game,taking into account the various parameters of the entire sensor network routing influential,giving the process of an auction game in the form of packet forwarding routing algorithm,the algorithm flow can be achieved efficiently promote the nodes cooperate with each other,thus effectively reducing the number of control packets in the transmission process,to achieve the full and effective implementation of multiple distributed scientific control and take advantage of the NS2 platform as the auction game algorithm simulation,Comparative analysis the entire experimental results.%本文结合拍卖博弈的思想,考虑到对整个传感器网络路由有影响的各种有关参数,给出了一种以拍卖博弈形式的包转发路由算法流程,通过该算法流程可以达到高效地促进多个节点的相互合作,从而有效地减少控制包在传输过程中的次数,全面有效地实现多个分布式的科学控制,并充分利用NS2平台作为对拍卖博弈算法进行仿真验证,对整个实验结果进行对比分析。

  3. Needs and Opportunities to Improve the Operational Quality of Forwarding Companies

    Directory of Open Access Journals (Sweden)

    Dovilė Kontautaitė

    2013-04-01

    Full Text Available It is essential for forwarding companies to improve their activity by improving their internal and external processes in order to provide for a client an estimated basic and added value and effectively manage the flow of information in the general logistic supply chain. The article analyses the concepts of quality management and activity process, emphasising the main process of a forwarding enterprise and the demand to optimise the activity establishing quality management systems. The scientific literature analysis assists in the provision of quality assessment indicators of forwarding companies and ascertaining quality management systems that are suitable for transport companies.Article in Lithuanian

  4. Needs and Opportunities to Improve the Operational Quality of Forwarding Companies

    OpenAIRE

    Dovilė Kontautaitė; Virgilija Zinkevičiūtė

    2013-01-01

    It is essential for forwarding companies to improve their activity by improving their internal and external processes in order to provide for a client an estimated basic and added value and effectively manage the flow of information in the general logistic supply chain. The article analyses the concepts of quality management and activity process, emphasising the main process of a forwarding enterprise and the demand to optimise the activity establishing quality management systems. The scienti...

  5. Improved Cuckoo Search Algorithm for Feed forward Neural Network Training

    OpenAIRE

    Ehsan Valian; Shahram Mohanna; Saeed Tavakoli

    2011-01-01

    The cuckoo search algorithm is a recently developed meta-heuristic optimization algorithm, which is suitable for solving optimization problems. To enhance the accuracy and convergence rate of this algorithm, an improved cuckoo search algorithm is proposed in this paper. Normally, the parameters of the cuckoo search are kept constant. This may lead to decreasing the efficiency of the algorithm. To cope with this issue, a proper strategy for tuning the cuckoo search parameters is pr...

  6. 改进的HyperSplit报文分类算法%Improved HyperSplit Packet Classification Algorithm

    Institute of Scientific and Technical Information of China (English)

    马腾; 陈庶樵; 张校辉

    2014-01-01

    In order to solve the problem of too much memory usage in existing work for high speed large volume multi-field packet classification, an improved HyperSplit algorithm is proposed. By analyzing the cause of too much memory usage, the heuristic algorithms are modified and designed to choose the cutting points and dimensions and eliminate redundancy. Rule replication is greatly reduced, redundant rules and nodes are removed, and the decision tree’s structure is optimized. Simulation results demonstrate that compared with the existing work, independent of rule base’s type and characteristic, the algorithm can greatly reduce memory usage without increasing the number of memory accesses and ensure that packets can be processed at wire speed, and when the volume of classifier is 105, the algorithm consumes about 80%memory usage as that of HyperSplit.%针对现有高速、大容量、多域报文分类算法普遍存在内存使用量大的问题,提出一种改进的 HyperSplit 多域报文分类算法。通过分析现有算法内存使用量大的原因,修正和设计选择分割维度与分割点、去除冗余结构的启发式算法,最大限度减少决策树中的复制规则数量,消除决策树中存在的冗余规则和冗余节点,优化决策树结构。仿真结果表明,该算法与现有多域报文分类算法陒比,不依赖于规则集类型和特征,在保证内存访问次数不增加、报文得到陑速处理的情况下,可降低算法的内存使用量,当规则集容量为105时,内存使用量降低到HyperSplit算法的80%。

  7. Extensible packet processing architecture

    Science.gov (United States)

    Robertson, Perry J.; Hamlet, Jason R.; Pierson, Lyndon G.; Olsberg, Ronald R.; Chun, Guy D.

    2013-08-20

    A technique for distributed packet processing includes sequentially passing packets associated with packet flows between a plurality of processing engines along a flow through data bus linking the plurality of processing engines in series. At least one packet within a given packet flow is marked by a given processing engine to signify by the given processing engine to the other processing engines that the given processing engine has claimed the given packet flow for processing. A processing function is applied to each of the packet flows within the processing engines and the processed packets are output on a time-shared, arbitered data bus coupled to the plurality of processing engines.

  8. Extensible packet processing architecture

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Perry J.; Hamlet, Jason R.; Pierson, Lyndon G.; Olsberg, Ronald R.; Chun, Guy D.

    2013-08-20

    A technique for distributed packet processing includes sequentially passing packets associated with packet flows between a plurality of processing engines along a flow through data bus linking the plurality of processing engines in series. At least one packet within a given packet flow is marked by a given processing engine to signify by the given processing engine to the other processing engines that the given processing engine has claimed the given packet flow for processing. A processing function is applied to each of the packet flows within the processing engines and the processed packets are output on a time-shared, arbitered data bus coupled to the plurality of processing engines.

  9. Optical packet switching without packet alignment

    DEFF Research Database (Denmark)

    Hansen, Peter Bukhave; Danielsen, Søren Lykke; Stubkjær, Kristian

    1998-01-01

    Operation without packet alignment of an all-optical packet switch is proposed and predicted feasible through a detailed traffic analysis. Packet alignment units are eliminated resulting in a simple switch architecture while optimal traffic performance is maintained through the flexibility provided...

  10. Comparison of Ring-Buffer-Based Packet Capture Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Steven Andrew [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2015-10-01

    Traditional packet-capture solutions using commodity hardware incur a large amount of overhead as packets are copied multiple times by the operating system. This overhead slows sensor systems to a point where they are unable to keep up with high bandwidth traffic, resulting in dropped packets. Incomplete packet capture files hinder network monitoring and incident response efforts. While costly commercial hardware exists to capture high bandwidth traffic, several software-based approaches exist to improve packet capture performance using commodity hardware.

  11. Analysis of a WDM Packet Switch with Improved Performance under Bursty Traffic Conditions due to Tuneable Wavelength Converters

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Jørgensen, Carsten; Mikkelsen, Benny;

    1998-01-01

    in the wavelength domain and accounts for bursty traffic. The theoretical model is verified by simulations and from the model we find that higher traffic loads as well as burstiness can be accepted when tuneable wavelength converters are used. Consequently, a larger throughput of the photonic packet switches...

  12. MAC Centered Cooperation - Synergistic Design of Network Coding, Multi-Packet Reception, and Improved Fairness to Increase Network Throughput (PREPRINT)

    Science.gov (United States)

    2011-02-08

    each packet individually using two time slots. With COPE, the relay R will generate one coded message, aEflb (where Efl indicates mod 2 addition), and...that the wireless channel is loss less, feedback is perfect, and the load required for acknowledgments is contained as part of the initial

  13. Efficient incremental relaying for packet transmission over fading channels

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-07-01

    In this paper, we propose a novel relaying scheme for packet transmission over fading channels, which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from the destination. Our scheme capitalizes on the fact that relaying is only required when direct transmission suffers deep fading. We calculate the packet error rate for the proposed efficient incremental relaying (EIR) scheme with both amplify and forward and decode and forward relaying. We compare the performance of the EIR scheme with the threshold-based incremental relaying (TIR) scheme. It is shown that the efficiency of the TIR scheme is better for lower values of the threshold. However, the efficiency of the TIR scheme for higher values of threshold is outperformed by the EIR. In addition, three new threshold-based adaptive EIR are devised to further improve the efficiency of the EIR scheme. We calculate the packet error rate and the efficiency of these new schemes to provide the analytical insight. © 2014 IEEE.

  14. Improving marketing strategies of sea freight forwarding services - Thien Hong Joint Stock company

    OpenAIRE

    Pham, Thanh Huyen

    2015-01-01

    Analyzing and improving marketing strategies of Thien Hong Joint Stock company - a newborn company in the field of sea freight forwarding service in Vietnam. This thesis focused on the 4Ps (product, price, placement, promotion) in marketing strategy, how to apply the theory of services marketing in a business to business company and a special industry effectively.

  15. Atorvastatin preconditioning improves the forward blood flow in the no-reflow rats.

    Science.gov (United States)

    Shao, Liang; Zhang, Yong; Ma, Aiqun; Zhang, Ping; Wu, Dayin; Li, Wenzhu; Wang, Jue; Liu, Kun; Wang, Zhaohui

    2014-02-01

    Atorvastatin is not only an antilipemic but also used as an anti-inflammatory medicine in heart disease. Our working hypothesis was that atorvastatin preconditioning could improve the forward blood flow in the no-reflow rats associated with inflammation. We investigated that two doses of atorvastatin preconditioning (20 and 5 mg/kg/day) could alleviate deterioration of early cardiac diastolic function in rats with inflammation detected by echocardiography and haemodynamics. This benefit was obtained from the effect of atorvastatin preconditioning on improving forward blood flow and preserving the infarct cardiomyocytes, which was estimated by Thioflavin S and TTC staining in rats with myocardial ischemia/reperfusion. Subsequently, the improving of forward blood flow was ascribed to reduction of microthrombus in microvascular and myocardial fibrosis observed by MSB and Masson's trichrome staining with atorvastatin preconditioning. Ultimately, we found that atorvastatin preconditioning could reduce inflammation factor, such as tumor necrosis factor-α and fibrinogen-like protein 2, both in myocardial and in mononuclear cells, which probably attribute to microcirculation dysfunction in no-reflow rats detected by immunohistochemistry staining, western blot, and ELISA detection, respectively. In conclusion, atorvastatin preconditioning could alleviate deterioration of early cardiac diastolic function and improve the forward blood flow in the no-reflow rats attributing to reduction of TNF-α and fgl-2 expression.

  16. 无线传感器网络中基于拍卖博弈的数据包转发算法%Auction Game Based Packet Forwarding Algorithm in Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    刘群; 张立娇

    2013-01-01

    在无线传感器网络中,为了提高能量的利用率和增强数据包转发的可靠性,设计了PFAG(Packet Forwarding Algorithm Based on Auction Game)算法.该算法将数据包转发过程看作一种多阶段拍卖博弈过程,其中源节点作为买方,邻居节点作为卖方.邻居节点根据拍卖博弈模型中的标价函数给出相应标价,源节点通过选择最佳的转发节点以使自己的收益最大化.当数据包转发成功后,源节点退出此次博弈,转发节点作为买方启动新一轮拍卖博弈,依次迭代,直到数据包被成功发送到目的节点.经过这样一个多阶段的拍卖博弈过程,源节点最终可找出一条能耗低、稳定且可靠的包转发路径.仿真结果表明,PFAG算法可有效的降低和平衡网络能耗,具备传输可靠性高和适应网络规模变化性强的特点.

  17. Efficient Packet Forwarding in Mesh Network

    OpenAIRE

    Soumen Kanrar

    2012-01-01

    Wireless Mesh Network (WMN) is a multi hop low cost, with easy maintenance robust network providing reliable service coverage. WMNs consist of mesh routers and mesh clients. In this architecture, while static mesh routers form the wireless backbone, mesh clients access the network through mesh routers as well as directly meshing with each other. Different from traditional wireless networks, WMN is dynamically self-organized and self-configured. In other words, the nodes in the mesh network au...

  18. Transporting live video over high packet loss networks

    Science.gov (United States)

    Werdin, Dave

    2013-05-01

    Transport of live video requires a robust backbone as live video decoders are subject to dropouts and buffer starvation. A short duration packet loss will many times cause a decoder to go black for many seconds as it reacquires the stream and clock. IP networks due to their connectionless approach and support for variable length packets, inherently display packet delivery variability. These characteristics most typically include packet loss, packet delay variation, and packets being delivered out of order. Deep Packet Recovery (DPR) techniques provide correction to IP network induced errors and issues. DPR can provide a much broader and stronger protection than traditional Forward Error Correction techniques enabling transport of live video across severely impaired networks.

  19. Efficient Vector-Based Forwarding for Underwater Sensor Networks

    Directory of Open Access Journals (Sweden)

    Peng Xie

    2010-01-01

    Full Text Available Underwater Sensor Networks (UWSNs are significantly different from terrestrial sensor networks in the following aspects: low bandwidth, high latency, node mobility, high error probability, and 3-dimensional space. These new features bring many challenges to the network protocol design of UWSNs. In this paper, we tackle one fundamental problem in UWSNs: robust, scalable, and energy efficient routing. We propose vector-based forwarding (VBF, a geographic routing protocol. In VBF, the forwarding path is guided by a vector from the source to the target, no state information is required on the sensor nodes, and only a small fraction of the nodes is involved in routing. To improve the robustness, packets are forwarded in redundant and interleaved paths. Further, a localized and distributed self-adaptation algorithm allows the nodes to reduce energy consumption by discarding redundant packets. VBF performs well in dense networks. For sparse networks, we propose a hop-by-hop vector-based forwarding (HH-VBF protocol, which adapts the vector-based approach at every hop. We evaluate the performance of VBF and HH-VBF through extensive simulations. The simulation results show that VBF achieves high packet delivery ratio and energy efficiency in dense networks and HH-VBF has high packet delivery ratio even in sparse networks.

  20. Improved Reconstruction of Radio Holographic Signal for Forward Scatter Radar Imaging.

    Science.gov (United States)

    Hu, Cheng; Liu, Changjiang; Wang, Rui; Zeng, Tao

    2016-05-07

    Forward scatter radar (FSR), as a specially configured bistatic radar, is provided with the capabilities of target recognition and classification by the Shadow Inverse Synthetic Aperture Radar (SISAR) imaging technology. This paper mainly discusses the reconstruction of radio holographic signal (RHS), which is an important procedure in the signal processing of FSR SISAR imaging. Based on the analysis of signal characteristics, the method for RHS reconstruction is improved in two parts: the segmental Hilbert transformation and the reconstruction of mainlobe RHS. In addition, a quantitative analysis of the method's applicability is presented by distinguishing between the near field and far field in forward scattering. Simulation results validated the method's advantages in improving the accuracy of RHS reconstruction and imaging.

  1. Improved Reconstruction of Radio Holographic Signal for Forward Scatter Radar Imaging

    Directory of Open Access Journals (Sweden)

    Cheng Hu

    2016-05-01

    Full Text Available Forward scatter radar (FSR, as a specially configured bistatic radar, is provided with the capabilities of target recognition and classification by the Shadow Inverse Synthetic Aperture Radar (SISAR imaging technology. This paper mainly discusses the reconstruction of radio holographic signal (RHS, which is an important procedure in the signal processing of FSR SISAR imaging. Based on the analysis of signal characteristics, the method for RHS reconstruction is improved in two parts: the segmental Hilbert transformation and the reconstruction of mainlobe RHS. In addition, a quantitative analysis of the method’s applicability is presented by distinguishing between the near field and far field in forward scattering. Simulation results validated the method’s advantages in improving the accuracy of RHS reconstruction and imaging.

  2. An Improvement of Cover/El Gamal's Compress-and-Forward Relay Scheme

    CERN Document Server

    Xie, Liang-Liang

    2009-01-01

    The compress-and-forward relay scheme developed by (Cover and El Gamal, 1979) is improved with a modification on the decoding process. The improvement follows as a result of realizing that it is not necessary for the destination to decode the compressed observation of the relay; and even if the compressed observation is to be decoded, it can be more easily done by joint decoding with the original message, rather than in a successive way. An extension to multiple relays is also discussed.

  3. Multi-policy improvement in stochastic optimization with forward recursive function criteria

    Science.gov (United States)

    Chang, Hyeong Soo

    2005-05-01

    Iwamoto recently established a formal transformation via an invariant imbedding to construct a controlled Markov chain that can be solved in a backward manner, as in backward induction for finite-horizon Markov decision processes (MDPs), for a given controlled Markov chain with non-additive forward recursive objective function criterion. Chang et al. presented formal methods, called "parallel rollout" and "policy switching," of combining given multiple policies in MDPs and showed that the policies generated by both methods improve all of the policies that the methods combine. This brief paper extends the methods of parallel rollout and policy switching for forward recursive objective function criteria and shows that the similar property holds as in MDPs. We further discuss how to implement these methods via simulation.

  4. Novel multipath routing protocol integrated with forward error correction in MANET

    Institute of Scientific and Technical Information of China (English)

    AN Hui-yao; LU Xi-cheng; PENG Wei; WANG Yang-yuan

    2006-01-01

    In order to improve the data transmission reliability of mobile ad hoc network, a routing scheme called integrated forward error correction multipath routing protocol was proposed, which integrates the techniques of packet fragmenting and forward error correction encoding into multipath routing. The scheme works as follows:adding a certain redundancy into the original packets; fragmenting the resulting packets into exclusive blocks of the same size; encoding with the forward error correction technique, and then sending them to the destination node.When the receiving end receives a certain amount of information blocks, the original information will be recovered even with partial loss. The performance of the scheme was evaluated using OPNET modeler. The experimental results show that with the method the average transmission delay is decreased by 20% and the transmission reliability is increased by 300%.

  5. Packet Tracer network simulator

    CERN Document Server

    Jesin, A

    2014-01-01

    A practical, fast-paced guide that gives you all the information you need to successfully create networks and simulate them using Packet Tracer.Packet Tracer Network Simulator is aimed at students, instructors, and network administrators who wish to use this simulator to learn how to perform networking instead of investing in expensive, specialized hardware. This book assumes that you have a good amount of Cisco networking knowledge, and it will focus more on Packet Tracer rather than networking.

  6. Wave-packet motion

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, R.A.; Robinson, J.E.

    1980-02-15

    The time-dependent Schroedinger equation is integrated numerically to obtain the time evolution of an initially Gaussian packet in the presence of Eckart, truncated quadratic, and untruncated quadratic potentials. Potential and packet parameters are chosen with hydrogen interstitials in transition metals in mind and are varied over significant ranges. Use of the smooth, bounded Eckart potential eliminates the pronounced structure and the anomalous spreading reported previously for other potentials. An interesting transient feature of the scattered packet is found and discussed in terms of the Wigner time delay. Packet transmission coefficients are discussed, and a quasiclassical approximation is found to agree closely with the exact results.

  7. Application of Wavelet Packet De-noising in Time-Frequency Analysis of the Local Wave Method

    Institute of Scientific and Technical Information of China (English)

    LI Hong-kun; MA Xiao-jiang; WANG Zhen; ZHU Hong

    2003-01-01

    The local wave method is a very good time-frequency method for nonstationary vibration signal analysis. But the interfering noise has a big influence on the accuracy of time-frequency analysis. The wavelet packet de-noising method can eliminate the interference of noise and improve the signal-noise-ratio. This paper uses the local wave method to decompose the de-noising signal and perform a time-frequency analysis. We can get better characteristics. Finally, an example of wavelet packet de-noising and a local wave time-frequency spectrum application of diesel engine surface vibration signal is put forward.

  8. MAC2: A Multi-Hop Adaptive MAC Protocol with Packet Concatenation for Wireless Sensor Networks

    Science.gov (United States)

    Nguyen, Kien; Meis, Ulrich; Ji, Yusheng

    Wireless sensor network MAC protocols switch radios off periodically, employing the so-called duty cycle mechanism, in order to conserve battery power that would otherwise be wasted by energy-costly idle listening. In order to minimize the various negative side-effects of the original scheme, especially on latency and throughput, various improvements have been proposed. In this paper, we introduce a new MAC protocol called MAC2(Multi-hop Adaptive with packet Concatenation-MAC) which combines three promising techniques into one protocol. Firstly, the idea to forward packets over multiple hops within one operational cycle as initially introduced in RMAC. Secondly, an adaptive method that adjusts the listening period according to traffic load minimizing idle listening. Thirdly, a packet concatenation scheme that not only increases throughput but also reduces power consumption that would otherwise be incurred by additional control packets. Furthermore, MAC2 incorporates the idea of scheduling data transmissions with minimum latency, thereby performing packet concatenation together with the multi-hop transmission mechanism in a most efficient way. We evaluated MAC2 using the prominent network simulator ns-2 and the results show that our protocol can outperform DW-MAC — a state of the art protocol both in terms of energy efficiency and throughput.

  9. Improving the character recognition efficiency of feed forward BP neural network

    CERN Document Server

    Choudhary, Amit

    2011-01-01

    This work is focused on improving the character recognition capability of feed-forward back-propagation neural network by using one, two and three hidden layers and the modified additional momentum term. 182 English letters were collected for this work and the equivalent binary matrix form of these characters was applied to the neural network as training patterns. While the network was getting trained, the connection weights were modified at each epoch of learning. For each training sample, the error surface was examined for minima by computing the gradient descent. We started the experiment by using one hidden layer and the number of hidden layers was increased up to three and it has been observed that accuracy of the network was increased with low mean square error but at the cost of training time. The recognition accuracy was improved further when modified additional momentum term was used.

  10. Throughput and delay performance analysis of packet aggregation scheme for PRMA

    DEFF Research Database (Denmark)

    Zhang, Qi; Iversen, Villy Bæk; Fitzek, F.H.P.

    2007-01-01

    Packet reservation multiple access (PRMA) protocol is an implicit reservation MAC protocol. It is initially designed for voice packets in the cellular networks [2, 3] but it is currently also used for data packets in OFDM based fixed wireless access networks [8, 9]. When it is applied for data...... packets, the system throughput depends on the size of packets and the number of consecutive packets. From the statistics of existent wireless data networks using PRMA protocol, it shows that the system throughput is quite low because of the inconsecutive small packets. In order to improve the throughput......, packet aggregation scheme is considered to be applied in PRMA. Before designing packet aggregation algorithm, it is worth investigating the effect of packet aggregation scheme on the performance of throughput and delay. In this paper we develop a generic Markov chain model for PRMA with packet...

  11. Throughput and Delay Performance Analysis of Packet Aggregation Scheme for PRMA

    DEFF Research Database (Denmark)

    Zhang, Qi; Iversen, Villy Bæk; Fitzek, Frank H.P.

    2008-01-01

    Packet reservation multiple access (PRMA) protocol is an implicit reservation MAC protocol. It is initially designed for voice packets in the cellular networks, but it is currently also used for data packets in OFDM based fixed wireless access networks. When it is applied for data packets......, the system throughput depends on the size of packets and the number of consecutive packets. From the statistics of existent wireless data networks using PRMA protocol, it shows that the system throughput is quite low because of the inconsecutive small packets. In order to improve the throughput, packet...... aggregation scheme is considered to be applied in PRMA. Before designing packet aggregation algorithm, it is worth investigating the effect of packet aggregation scheme on the performance of throughput and delay. In this paper we develop a generic Markov chain model for PRMA with packet aggregation. Based...

  12. Looking forward by looking back: using historical calibration to improve forecasts of human disease vector distributions.

    Science.gov (United States)

    Acheson, Emily Sohanna; Kerr, Jeremy Thomas

    2015-03-01

    Arthropod disease vectors, most notably mosquitoes, ticks, tsetse flies, and sandflies, are strongly influenced by environmental conditions and responsible for the vast majority of global vector-borne human diseases. The most widely used statistical models to predict future vector distributions model species niches and project the models forward under future climate scenarios. Although these methods address variations in vector distributions through space, their capacity to predict changing distributions through time is far less certain. Here, we review modeling methods used to validate and forecast future distributions of arthropod vectors under the effects of climate change and outline the uses or limitations of these techniques. We then suggest a validation approach specific to temporal extrapolation models that is gaining momentum in macroecological modeling and has great potential for epidemiological modeling of disease vectors. We performed systematic searches in the Web of Science, ScienceDirect, and Google Scholar to identify peer-reviewed English journal articles that model arthropod disease vector distributions under future environment scenarios. We included studies published up to and including June, 2014. We identified 29 relevant articles for our review. The majority of these studies predicted current species niches and projected the models forward under future climate scenarios without temporal validation. Historically calibrated forecast models improve predictions of changing vector distributions by tracking known shifts through recently observed time periods. With accelerating climate change, accurate predictions of shifts in disease vectors are crucial to target vector control interventions where needs are greatest.

  13. Network Packet Length Covert Channel Based on Empirical Distribution Function

    Directory of Open Access Journals (Sweden)

    Lihua Zhang

    2014-06-01

    Full Text Available Network packet length covert channel modulates secret message bits onto the packet lengths to transmit secret messages. In this paper, a novel network packet length covert channel is proposed. The proposed scheme is based on the empirical distribution function of packet length series of legitimate traffic. Different from the existing schemes, the lengths of packets which are generated by the covert sender follow the distribution of normal traffic more closely in our scheme. To validate the security of the proposed scheme, the state-of-the-art packet length covert channel detection algorithm is adopted. The experimental results show that the packet length covert channel provides a significant performance improvement in detection resistance meanings

  14. Laser Induced Forward Transfer for front contact improvement in silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Colina, M., E-mail: monicacolinb@gmail.com; Morales-Vilches, A.; Voz, C.; Martín, I.; Ortega, P.; Orpella, A.; López, G.; Alcubilla, R.

    2015-05-01

    Highlights: • LIFT technique is investigated to improve heterojunction HJ solar cells. • Doped silicon films are adequate precursors for LIFT application in HJ cells. • LIFT leads to a reduction of the series resistance of a-Si HJ diodes. • LIFT allows the improvement of the front contact resistance in a-Si HJ solar cells. - Abstract: In this work the Laser Induced Forward Transfer (LIFT) technique is investigated to create n-doped regions on p-type c-Si substrates. The precursor source of LIFT consisted in a phosphorous-doped hydrogenated amorphous silicon layer grown by Plasma Enhanced Chemical Vapor Deposition (PECVD) onto a transparent substrate. Transfer of the doping atoms occurs when a sequence of laser pulses impinging onto the doped layer propels the material toward the substrate. The laser irradiation not only transfers the doping material but also produces a local heating that promotes its diffusion into the substrate. The laser employed was a 1064 nm, lamp-pumped system, working at pulse durations of 100 and 400 ns. In order to obtain a good electrical performance a comprehensive optimization of the applied laser fluency and number of pulses was carried out. Subsequently, arrays of n + p local junctions were created by LIFT and the resulting J–V curves demonstrated the formation of good quality n+ regions. These structures were finally incorporated to enhance the front contact in conventional silicon heterojunction solar cells leading to an improvement of conversion efficiency.

  15. Quantum wave packet revivals

    CERN Document Server

    Robinett, R W

    2004-01-01

    The numerical prediction, theoretical analysis, and experimental verification of the phenomenon of wave packet revivals in quantum systems has flourished over the last decade and a half. Quantum revivals are characterized by initially localized quantum states which have a short-term, quasi-classical time evolution, which then can spread significantly over several orbits, only to reform later in the form of a quantum revival in which the spreading reverses itself, the wave packet relocalizes, and the semi-classical periodicity is once again evident. Relocalization of the initial wave packet into a number of smaller copies of the initial packet (`minipackets' or `clones') is also possible, giving rise to fractional revivals. Systems exhibiting such behavior are a fundamental realization of time-dependent interference phenomena for bound states with quantized energies in quantum mechanics and are therefore of wide interest in the physics and chemistry communities. We review the theoretical machinery of quantum w...

  16. Optical packet switched networks

    DEFF Research Database (Denmark)

    Hansen, Peter Bukhave

    1999-01-01

    Optical packet switched networks are investigated with emphasis on the performance of the packet switch blocks. Initially, the network context of the optical packet switched network is described showing that a packet network will provide transparency, flexibility and bridge the granularity gap...... between the electrical switched layer and the WDM transport layer. Analytical models are implemented to determine the signal quality ghrough the switch blocks in terms of power penalty and to assess the traffic performance of different switch block architectures. Further, a computer simulation model...... is used to investigate the influence on the traffic performance of asynchronous operation of the switch blocks. The signal quality investigation illustrates some of the component requirements in respect to gain saturation in SOA gates and crosstalk in order to obtain high cascadability of the switch...

  17. Mobile learning module improves knowledge of medical shock for forward surgical team members.

    Science.gov (United States)

    Schulman, Carl I; Garcia, George D; Wyckoff, Mary M; Duncan, Robert C; Withum, Kelly F; Graygo, Jill

    2012-11-01

    Acute trauma care is characterized by dynamic situations that require adequate preparation to ensure success for military health professionals. The use of mobile learning in this environment can provide a solution that standardizes education and replaces traditional didactic lectures. A comparative evaluation with a pre-post test design regarding medical shock was delivered via either a didactic lecture or a mobile learning video module to U.S. Army Forward Surgical Team (FST) members. Participants completed a pretest, were randomly assigned to treatment group by FST, and then completed the post-test and scenario assessment. One-hundred and thirteen FST members participated with 53 in the mobile learning group and 60 in the lecture group (control). The percent mean score for the mobile learning group increased from 43.6 to 70 from pretest to post-test, with a scenario mean score of M = 56.2. The percent mean score for the control group increased from 41.5 to 72.5, with a scenario mean score of M = 59.7. The two-way analysis of variance mean score difference was 26.4 for the mobile learning group and 31.0 for the control, F = 2.18, (p = 0.14). Mobile learning modules, coupled with a structured assessment, have the potential to improve educational experiences in civilian and military settings.

  18. Laser-induced forward transfer for improving fine-line metallization in photovoltaic applications

    Science.gov (United States)

    Sanchez-Aniorte, M. I.; Mouhamadou, B.; Alloncle, A. P.; Sarnet, T.; Delaporte, P.

    2016-06-01

    Grand challenges to create new front metallization techniques in photovoltaic focus considerable attention on laser-induced forward transfer (LIFT) approach. This alternative method aims to overcome the limitations of the well-established and mature screen-printing (SP) technique. Such limitations are for instance restrictions in the grid pattern design, high-temperature steps, and limited aspect ratio of the line contact (Poulain et al. in Appl Surf Sci 257:5241-5244, 2011). Although different new front contact metallization concepts have been studied, most of them require a second print step to increase the volume of the contact (Gao et al. in Proceedings of 25th EU PVSEC conference, 2010; Beaucarne and Schubert in Energy Proc 67:2-12, 2015; Lossen and Matusovsky in Energy Proc 67:156-162, 2015; Green in Phys E 14:65-70, 2002; Lennon et al. in Prog Photovolt Res Appl V21:1454-1468, 2012). As a result, it is desirable to find innovative metallization techniques to improve the cell efficiency without significantly increasing the cost. Although many challenges remain before to obtain high-quality, robust, and high-performance LIFT contact formation, it required a fully theoretical and experimental assessment. This paper presents the results of a study of the LIFT technique in picosecond regime and thick silver pastes to create high-quality conductive lines for photovoltaic applications.

  19. Loss Analysis of the Software-based Packet Capturing

    Directory of Open Access Journals (Sweden)

    Tamas Skopko

    2012-06-01

    Full Text Available Gigabit per second and higher bandwidths imply greater challenge to perform lossless packet capturing on generic PC architectures. This is because of software based capture solutions, which did not improve as fast as network bandwidth and they still heavily rely on the OS's packet processing mechanism. There are hardware and operating system factors that primarily affect capture performance. This paper summarizes these parameters and shows how to predict packet loss ratio during the capture process.

  20. Quantum wave packet revivals

    Energy Technology Data Exchange (ETDEWEB)

    Robinett, R.W

    2004-03-01

    The numerical prediction, theoretical analysis, and experimental verification of the phenomenon of wave packet revivals in quantum systems has flourished over the last decade and a half. Quantum revivals are characterized by initially localized quantum states which have a short-term, quasi-classical time evolution, which then can spread significantly over several orbits, only to reform later in the form of a quantum revival in which the spreading reverses itself, the wave packet relocalizes, and the semi-classical periodicity is once again evident. Relocalization of the initial wave packet into a number of smaller copies of the initial packet ('minipackets' or 'clones') is also possible, giving rise to fractional revivals. Systems exhibiting such behavior are a fundamental realization of time-dependent interference phenomena for bound states with quantized energies in quantum mechanics and are therefore of wide interest in the physics and chemistry communities. We review the theoretical machinery of quantum wave packet construction leading to the existence of revivals and fractional revivals, in systems with one (or more) quantum number(s), as well as discussing how information on the classical period and revival time is encoded in the energy eigenvalue spectrum. We discuss a number of one-dimensional model systems which exhibit revival behavior, including the infinite well, the quantum bouncer, and others, as well as several two-dimensional integrable quantum billiard systems. Finally, we briefly review the experimental evidence for wave packet revivals in atomic, molecular, and other systems, and related revival phenomena in condensed matter and optical systems.

  1. Quantum wave packet revivals

    Science.gov (United States)

    Robinett, R. W.

    2004-03-01

    The numerical prediction, theoretical analysis, and experimental verification of the phenomenon of wave packet revivals in quantum systems has flourished over the last decade and a half. Quantum revivals are characterized by initially localized quantum states which have a short-term, quasi-classical time evolution, which then can spread significantly over several orbits, only to reform later in the form of a quantum revival in which the spreading reverses itself, the wave packet relocalizes, and the semi-classical periodicity is once again evident. Relocalization of the initial wave packet into a number of smaller copies of the initial packet (‘minipackets’ or ‘clones’) is also possible, giving rise to fractional revivals. Systems exhibiting such behavior are a fundamental realization of time-dependent interference phenomena for bound states with quantized energies in quantum mechanics and are therefore of wide interest in the physics and chemistry communities. We review the theoretical machinery of quantum wave packet construction leading to the existence of revivals and fractional revivals, in systems with one (or more) quantum number(s), as well as discussing how information on the classical period and revival time is encoded in the energy eigenvalue spectrum. We discuss a number of one-dimensional model systems which exhibit revival behavior, including the infinite well, the quantum bouncer, and others, as well as several two-dimensional integrable quantum billiard systems. Finally, we briefly review the experimental evidence for wave packet revivals in atomic, molecular, and other systems, and related revival phenomena in condensed matter and optical systems.

  2. Fusion of forward looking infrared and ground penetrating radar for improved stopping distances in landmine detection

    Science.gov (United States)

    Malof, Jordan M.; Morton, Kenneth D.; Collins, Leslie M.; Torrione, Peter A.

    2014-06-01

    Ground penetrating radar (GPR) is a popular sensing modality for buried threat detection that offers low false alarm rates (FARs), but suffers from a short detection stopping or standoff distance. This short stopping distance leaves little time for the system operator to react when a threat is detected, limiting the speed of advance. This problem arises, in part, because of the way GPR data is typically processed. GPR data is first prescreened to reduce the volume of data considered for higher level feature-processing. Although fast, prescreening introduces latency that delays the feature processing and lowers the stopping distance of the system. In this work we propose a novel sensor fusion framework where a forward looking infrared (FLIR) camera is used as a prescreener, providing suspicious locations to the GPRbased system with zero latency. The FLIR camera is another detection modality that typically yields a higher FAR than GPR while offering much larger stopping distances. This makes it well-suited in the role of a zero-latency prescreener. In this framework, GPR-based feature processing can begin without any latency, improving stopping distances. This framework was evaluated using well-known FLIR and GPR detection algorithms on a large dataset collected at a Western US test site. Experiments were conducted to investigate the tradeoff between early stopping distance and FAR. The results indicate that earlier stopping distances are achievable while maintaining effective FARs. However, because an earlier stopping distance yields less data for feature extraction, there is a general tradeoff between detection performance and stopping distance.

  3. Optical Packet Switching Demostrator

    DEFF Research Database (Denmark)

    Mortensen, Brian Bach; Berger, Michael Stübert

    2002-01-01

    In the IST project DAVID (data and voice integration over DWDM) work is carried out defining possible architectures of future optical packet switched networks. The feasibility of the architecture is to be verified in a demonstration set-up. This article describes the demonstrator set-up and the m......In the IST project DAVID (data and voice integration over DWDM) work is carried out defining possible architectures of future optical packet switched networks. The feasibility of the architecture is to be verified in a demonstration set-up. This article describes the demonstrator set...

  4. Three-dimensional forward modelling and inversion of complex resistivity based on the improved quasi-linear approximation

    Science.gov (United States)

    Liu, Y.; Li, T.; Zhu, C.; Zhang, R.; Wu, Y.

    2015-12-01

    Three-dimensional (3-D) electromagnetic (EM) forward modelling and inversion continues to be an important issue for the correct interpretation of EM data.To this end,approximate solutions have been developed that allow the construction of relatively fast forward modelling and inversion schemes.We have developed an improved quasi-linear approximation which is more appropriate in solving the linear equation for greatly shortening calculation time.We achieved this by using green's function properties.Then we introduced the improved quasi-linear approximation to spectral induced polarization (SIP) to tackle the problem of the resolution and the efficiency.The localized quasi-linear (LQL) approximation theory is appropriate for multisource array-type surveys assuming that the normal field is slowly varying within the inhomogeneity domain.However,the normal field of attenuates severely which dose not satisfy the assumption of the LQL approximation.As a consenquence,the imaginary part is not accurate when LQL approximation is adopted for the simulation.The improved quasi-linear approximation provide a new approach with the same resolution of QL approximation and much less calculation time.We have also constructed three-dimensional SIP forward modeling based on improved quasi-linear approximation method.It only takes 0.8s for forward modeling when inhomogeneity domain is divided into 2000 blocks.Beyond that, we have introduced the Cole-Cole model to the algorithm and complete the three-dimensional complex resistivity conjugate gradient inversion with parameter restraint.The model trial results show that this method can obtain good inversion results in physical parameters such as zero frequency resistivity, polarization.The results demonstrate the stability and the efficiency of the improved quasi-linear approximation and the method may be a practical solution for3-D EM forward modelling and inversion of SIP.

  5. Cross‐Layer optimization of the packet loss rate in mobile videoconferencing applications

    Directory of Open Access Journals (Sweden)

    R. Rivera‐Rodríguez

    2010-04-01

    Full Text Available Videoconferencing transmission over wireless channels presents relevant challenges in mobile scenarios at vehicular speeds.Previous contributions are focused on the optimization of the transmission of multimedia and delay‐sensitive applications overthe forward link. In this paper, a new Quality of Service (QoS parameter adaptation scheme is proposed. This scheme appliesthe Cross‐Layer Design technique on the reverse link of an 1xEV‐DO Revision 0 channel. As the wireless channel parameters andthe vehicle speed have significant influence in the network layer packet loss rate, it is proposed that the data rate generated bythe application adapts itself to the throughput offered by the lower layers as a function of such packet loss rate. Simulations ofthe proposed model show a significant reduction in losses caused by wireless channel impairments and vehicle mobility,resulting in an improvement in the performance of the mobile videoconferencing session.

  6. 深度包检测中一种正则表达式匹配算法的改进%Improvement of regular expression matching algorithm for deep packet inspection

    Institute of Scientific and Technical Information of China (English)

    张巍; 陈佼; 赵美凯

    2015-01-01

    网络数据包内容检测技术已在网络安全、网络监视、HTTP负载均衡等方面得到广泛的应用,因此,对快速数据包内容的检测就变得异常重要。在数据包内容检测过程中,数据包的净载数据要通过一系列已经定义好的正则表达式模式进行数据匹配。在此,阐述目前数据包检测存在的问题,如传统数据包检测应用程序要求很大的内存空间去存储相应的正则表达式模式,提出一种大大降低对内存空间使用的改进算法。通过将该改进算法应用到以DFA为基础的包检测应用程序中,说明经过真实网络数据来检测算法的改进成果。结果表明了改进算法的有效性。%Content inspection technology for network data packet has been widely used in network security,network moni⁃toring,HTTP load balancing,etc. In content scanning of data packet,the payload data of the packet needs to be matched by a set of the specified regular expressions. The problem existing in the current data packet inspection is elaborated in this paper. That is,the traditional application program of data packet inspection needs a large memory space to store the corresponding regu⁃lar expression pattern. A improved algorithm that effectively reduces memory space usage is proposed. The application of the im⁃proved algorithm in DFA⁃based packet inspection program indicates the improvement achievements,which were obtained by de⁃tection of the true network data.

  7. Improving the local relevance of large scale water demand predictions: the way forward

    Science.gov (United States)

    Bernhard, Jeroen; Reynaud, Arnaud; de Roo, Ad

    2016-04-01

    use and water prices. Subsequently, econometric estimates allow us to make a monetary valuation of water and identify the dominant drivers of domestic and industrial water demand per country. Combined with socio-economic, demographic and climate scenarios we made predictions for future Europe. Since this is a first attempt we obtained mixed results between countries when it comes to data availability and therefore model uncertainty. For some countries we have been able to develop robust predictions based on vast amounts of data while some other countries proved more challenging. We do feel however, that large scale predictions based on regional data are the way forward to provide relevant scientific policy support. In order to improve on our work it is imperative to further expand our database of consistent regional data. We are looking forward to any kind of input and would be very interested in sharing our data to collaborate towards a better understanding of the water use system.

  8. All optical contention detection and resolution for asynchronous variable length optical packets switching

    Science.gov (United States)

    Farhat, Rim; Farhat, Amel; Menif, Mourad

    2016-04-01

    We proposed a novel 2×2 all optical packet switching router architecture supporting asynchronous, labelled and variablelength packet. A proof of concept through Matlab Simulink simulation is validated. Then we discussed the three possible scenarios to demonstrate the contention resolution technique based on deflection routing. We have showing that the contending packet is detected and forwarded according FIFO (First In First Out) strategy to another output.

  9. Hoover Dam Learning Packet.

    Science.gov (United States)

    Bureau of Reclamation (Dept. of Interior), Washington, DC.

    This learning packet provides background information about Hoover Dam (Nevada) and the surrounding area. Since the dam was built at the height of the Depression in 1931, people came from all over the country to work on it. Because of Hoover Dam, the Colorado River was controlled for the first time in history and farmers in Nevada, California, and…

  10. Packet transport network in metro

    Science.gov (United States)

    Huang, Feng; Yi, Xiaobo; Zhang, Hanzheng; Gong, Ping

    2008-11-01

    IP packet based services such as high speed internet, IP voice and IP video will be widely deployed in telecom network, which make transport network evolution to packet transport network. Characteristics of transport network and requirements of packet transport network are analyzed, T-MPLS/MPLS-TP based PTN technology is given and it will be used in metro (access, aggregation and core) network.

  11. Feed-forward active contour analysis for improved brachial artery reactivity testing.

    Science.gov (United States)

    Pugliese, Daniel N; Sehgal, Chandra M; Sultan, Laith R; Reamer, Courtney B; Mohler, Emile R

    2016-08-01

    The object of this study was to utilize a novel feed-forward active contour (FFAC) algorithm to find a reproducible technique for analysis of brachial artery reactivity. Flow-mediated dilation (FMD) is an important marker of vascular endothelial function but has not been adopted for widespread clinical use given its technical limitations, including inter-observer variability and differences in technique across clinical sites. We developed a novel FFAC algorithm with the goal of validating a more reliable standard. Forty-six healthy volunteers underwent FMD measurement according to the standard technique. Ultrasound videos lasting 5-10 seconds each were obtained pre-cuff inflation and at minutes 1 through 5 post-cuff deflation in longitudinal and transverse views. Automated segmentation using the FFAC algorithm with initial boundary definition from three different observers was used to analyze the images to measure diameter/cross-sectional area over the cardiac cycle. The %FMD was calculated for average, minimum, and maximum diameters/areas. Using the FFAC algorithm, the population-specific coefficient of variation (CV) at end-diastole was 3.24% for transverse compared to 9.96% for longitudinal measurements; the subject-specific CV was 15.03% compared to 57.41%, respectively. For longitudinal measurements made via the conventional method, the population-specific CV was 4.77% and subject-specific CV was 117.79%. The intraclass correlation coefficient (ICC) for transverse measurements was 0.97 (95% CI: 0.95-0.98) compared to 0.90 (95% CI: 0.84-0.94) for longitudinal measurements with FFAC and 0.72 (95% CI: 0.51-0.84) for conventional measurements. In conclusion, transverse views using the novel FFAC method provide less inter-observer variability than traditional longitudinal views. Improved reproducibility may allow adoption of FMD testing in a clinical setting. The FFAC algorithm is a robust technique that should be evaluated further for its ability to replace the

  12. Using Hybrid Algorithm to Improve Intrusion Detection in Multi Layer Feed Forward Neural Networks

    Science.gov (United States)

    Ray, Loye Lynn

    2014-01-01

    The need for detecting malicious behavior on a computer networks continued to be important to maintaining a safe and secure environment. The purpose of this study was to determine the relationship of multilayer feed forward neural network architecture to the ability of detecting abnormal behavior in networks. This involved building, training, and…

  13. Using Hybrid Algorithm to Improve Intrusion Detection in Multi Layer Feed Forward Neural Networks

    Science.gov (United States)

    Ray, Loye Lynn

    2014-01-01

    The need for detecting malicious behavior on a computer networks continued to be important to maintaining a safe and secure environment. The purpose of this study was to determine the relationship of multilayer feed forward neural network architecture to the ability of detecting abnormal behavior in networks. This involved building, training, and…

  14. An overview of packet-switching communications

    Science.gov (United States)

    Heggestad, H. M.

    1984-04-01

    A brief introduction is provided to an alternative computer-based technique for connecting a source to a destination, one which is not an evolutionary improvement in circuit switching but a radical departure from traditional techniques, namely packet switching. It is noted that this mechanism is becoming firmly established as a method for communicating digital data. Advances are also being made rapidly in the transmission of voice by this means, and packet switching may in fact be ideal for some future systems in which voice and data are fully integrated. The distinguishing feature of a packet-switched system is that a computer organizes outgoing digital information into segments which make their way independently to the receiving stations. Here, other computers reassemble them into replicas of the original message. One of the objectives conveniently achieved by packet systems is robustness with respect to blockage on particular links in the network. It is pointed out that two significant limitations affect the design and use of packet-switched systems; one is the need for substantial computer processing and bit manipulation at the network nodes, the other is accumulation of delay for real-time traffic.

  15. OFDM Scheme Based on Wavelet Packet Transform-OrientedGraded Multi-Service

    Institute of Scientific and Technical Information of China (English)

    赵慧; 侯春萍

    2003-01-01

    In this paper, a concept of image grading transmission is put forward to enhance data rate and to improve the usage of subcarriers in orthogonal frequency division multiplexing (OFDM). The idea originates from the wavelet packets representative of an image in which information is graded in terms of different priorities. The graded image facilitates more efficient use of adaptive subcarriers and bits allocation. The results of simulation in typical mobile environment prove that the output signal noise ratio (SNR) of the graded image excels that of the ungraded image by 1-2 dB under the same channel condition.

  16. Optical packet switching

    Science.gov (United States)

    Shekel, Eyal; Ruschin, Shlomo; Majer, Daniel; Levy, Jeff; Matmon, Guy; Koenigsberg, Lisa; Vecht, Jacob; Geron, Amir; Harlavan, Rotem; Shfaram, Harel; Arbel, Arnon; McDermott, Tom; Brewer, Tony

    2005-02-01

    We report here a scalable, multichassis, 6.3 terabit core router, which utilizes our proprietary optical switch. The router is commercially available and deployed in several customer sites. Our solution combines optical switching with electronic routing. An internal optical packet switching network interconnects the router"s electronic line cards, where routing and buffering functions take place electronically. The system architecture and performance will be described. The optical switch is based on Optical Phased Array (OPA) technology. It is a 64 x 64, fully non-blocking, optical crossbar switch, capable of switching in a fraction of a nanosecond. The basic principles of operation will be explained. Loss and crosstalk results will be presented, as well as the results of BER measurements of a 160 Gbps transmission through one channel. Basic principles of operation and measured results will be presented for the burst-mode-receivers, arbitration algorithm and synchronization. Finally, we will present some of our current research work on a next-generation optical switch. The technological issues we have solved in our internal optical packet network can have broad applicability to any global optical packet network.

  17. Packet combining based on cross-packet coding

    Institute of Scientific and Technical Information of China (English)

    LIN DengSheng; XIAO Ming; LI ShaoQian

    2013-01-01

    We propose a packet combining scheme of using cross-packet coding. With the coding scheme, one redundant packet can be used to ensure the error-correction of multiple source packets. Thus, the proposed scheme can increase the code rate. Moreover, the proposed coding scheme has also advantages of decoding complexity, reducing undetectable errors (by the proposed low-complexity decoder) and flexibility (applicable to channels with and without feedback). Theoretical analysis under the proposed low-complexity decoding algorithm is given to maximize the code rate by optimizing the number of source packets. Finally, we give numerical results to demonstrate the advantages of the proposed scheme in terms of code rates compared to the traditional packet combining without coding or ARQ (automatic repeat-request) techniques.

  18. Forward modeling to improve seismic reflection energy of a protective coal seam based on Zoeppritz equation

    Institute of Scientific and Technical Information of China (English)

    TAO Wen-peng; DONG Shou-hua; LI Yang

    2008-01-01

    In seismic exploration for coal, seismic waves are very difficult to transmit downward because of high velocity protec-tive layers, making the reflection information very hard to receive above ground. Based on the Snell law and the Zoeppritz equation, we studied the relationship between the incidence angle and reflection seismic wave energy using a forward model of level media. The result shows that the seismic wave energy has a sudden increase at the critical angle. Based on the energy propagation rule, using big offset to receive the seismic wave energy under a protective layer can effectively reduce its protection effect.

  19. Estimating TCP Packet Loss Ratio from Sampled ACK Packets

    Science.gov (United States)

    Yamasaki, Yasuhiro; Shimonishi, Hideyuki; Murase, Tutomu

    The advent of various quality-sensitive applications has greatly changed the requirements for IP network management and made the monitoring of individual traffic flows more important. Since the processing costs of per-flow quality monitoring are high, especially in high-speed backbone links, packet sampling techniques have been attracting considerable attention. Existing sampling techniques, such as those used in Sampled NetFlow and sFlow, however, focus on the monitoring of traffic volume, and there has been little discussion of the monitoring of such quality indexes as packet loss ratio. In this paper we propose a method for estimating, from sampled packets, packet loss ratios in individual TCP sessions. It detects packet loss events by monitoring duplicate ACK events raised by each TCP receiver. Because sampling reveals only a portion of the actual packet loss, the actual packet loss ratio is estimated statistically. Simulation results show that the proposed method can estimate the TCP packet loss ratio accurately from a 10% sampling of packets.

  20. Improving and Assessing Planet Sensitivity of the GPI Exoplanet Survey with a Forward Model Matched Filter

    Science.gov (United States)

    Ruffio, Jean-Baptiste; Macintosh, Bruce; Wang, Jason J.; Pueyo, Laurent; Nielsen, Eric L.; De Rosa, Robert J.; Czekala, Ian; Marley, Mark S.; Arriaga, Pauline; Bailey, Vanessa P.; Barman, Travis; Bulger, Joanna; Chilcote, Jeffrey; Cotten, Tara; Doyon, Rene; Duchêne, Gaspard; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Goodsell, Stephen J.; Graham, James R.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Morzinski, Katie M.; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler

    2017-06-01

    We present a new matched-filter algorithm for direct detection of point sources in the immediate vicinity of bright stars. The stellar point-spread function (PSF) is first subtracted using a Karhunen-Loéve image processing (KLIP) algorithm with angular and spectral differential imaging (ADI and SDI). The KLIP-induced distortion of the astrophysical signal is included in the matched-filter template by computing a forward model of the PSF at every position in the image. To optimize the performance of the algorithm, we conduct extensive planet injection and recovery tests and tune the exoplanet spectra template and KLIP reduction aggressiveness to maximize the signal-to-noise ratio (S/N) of the recovered planets. We show that only two spectral templates are necessary to recover any young Jovian exoplanets with minimal S/N loss. We also developed a complete pipeline for the automated detection of point-source candidates, the calculation of receiver operating characteristics (ROC), contrast curves based on false positives, and completeness contours. We process in a uniform manner more than 330 data sets from the Gemini Planet Imager Exoplanet Survey and assess GPI typical sensitivity as a function of the star and the hypothetical companion spectral type. This work allows for the first time a comparison of different detection algorithms at a survey scale accounting for both planet completeness and false-positive rate. We show that the new forward model matched filter allows the detection of 50% fainter objects than a conventional cross-correlation technique with a Gaussian PSF template for the same false-positive rate.

  1. Time-varying wing-twist improves aerodynamic efficiency of forward flight in butterflies.

    Directory of Open Access Journals (Sweden)

    Lingxiao Zheng

    Full Text Available Insect wings can undergo significant chordwise (camber as well as spanwise (twist deformation during flapping flight but the effect of these deformations is not well understood. The shape and size of butterfly wings leads to particularly large wing deformations, making them an ideal test case for investigation of these effects. Here we use computational models derived from experiments on free-flying butterflies to understand the effect of time-varying twist and camber on the aerodynamic performance of these insects. High-speed videogrammetry is used to capture the wing kinematics, including deformation, of a Painted Lady butterfly (Vanessa cardui in untethered, forward flight. These experimental results are then analyzed computationally using a high-fidelity, three-dimensional, unsteady Navier-Stokes flow solver. For comparison to this case, a set of non-deforming, flat-plate wing (FPW models of wing motion are synthesized and subjected to the same analysis along with a wing model that matches the time-varying wing-twist observed for the butterfly, but has no deformation in camber. The simulations show that the observed butterfly wing (OBW outperforms all the flat-plate wings in terms of usable force production as well as the ratio of lift to power by at least 29% and 46%, respectively. This increase in efficiency of lift production is at least three-fold greater than reported for other insects. Interestingly, we also find that the twist-only-wing (TOW model recovers much of the performance of the OBW, demonstrating that wing-twist, and not camber is key to forward flight in these insects. The implications of this on the design of flapping wing micro-aerial vehicles are discussed.

  2. Forward di-jet production in p+Pb collisions in the small-x improved TMD factorization framework

    CERN Document Server

    van Hameren, A; Kutak, K; Marquet, C; Petreska, E; Sapeta, S

    2016-01-01

    We study the production of forward di-jets in proton-lead and proton-proton collisions at the Large Hadron Collider. Such configurations, with both jets produced in the forward direction, impose a dilute-dense asymmetry which allows to probe the gluon density of the lead or proton target at small longitudinal momentum fractions. Even though the jet momenta are always much bigger than the saturation scale of the target, $Q_s$, the transverse momentum imbalance of the di-jet system may be either also much larger than $Q_s$, or of the order $Q_s$, implying that the small-$x$ QCD dynamics involved is either linear or non-linear, respectively. The small-$x$ improved TMD factorization framework deals with both situation in the same formalism. In the latter case, which corresponds to nearly back-to-back jets, we find that saturation effects induce a significant suppression of the forward di-jet azimuthal correlations in proton-lead versus proton-proton collisions.

  3. Forward di-jet production in p+Pb collisions in the small-x improved TMD factorization framework

    CERN Document Server

    van Hameren, A.; Kutak, K.; Marquet, C.; Petreska, E.; Sapeta, S.

    2016-01-01

    We study the production of forward di-jets in proton-lead and proton-proton collisions at the Large Hadron Collider. Such configurations, with both jets produced in the forward direction, impose a dilute-dense asymmetry which allows to probe the gluon density of the lead or proton target at small longitudinal momentum fractions. Even though the jet momenta are always much bigger than the saturation scale of the target, $Q_s$, the transverse momentum imbalance of the di-jet system may be either also much larger than $Q_s$, or of the order $Q_s$, implying that the small-$x$ QCD dynamics involved is either linear or non-linear, respectively. The small-$x$ improved TMD factorization framework deals with both situation in the same formalism. In the latter case, which corresponds to nearly back-to-back jets, we find that saturation effects induce a significant suppression of the forward di-jet azimuthal correlations in proton-lead versus proton-proton collisions.

  4. Technology Corner: Internet Packet Sniffers

    Directory of Open Access Journals (Sweden)

    Nick Flor

    2011-03-01

    Full Text Available A packet sniffer is a piece of software that allows a person to eavesdrop on computer communications over the internet.  A packet sniffer can be used as a diagnostic tool by network administrators or as a spying tool by hackers who can use it to steal passwords and other private information from computer users.  Whether you are a network administrator or information assurance specialist, it helps to have a detailed understanding of how packet sniffers work.  And one of the best ways to acquire such an understanding is to build and modify an actual packet sniffer.

  5. Improvement of multi-parameter-based feed-forward coagulant dosing control systems with feed-back functionalities.

    Science.gov (United States)

    Liu, W; Ratnaweera, H

    2016-01-01

    Coagulant dosing control in drinking and wastewater treatment plants (WWTPs) is often limited to flow proportional concepts. The advanced multi-parameter-based dosing control systems have significantly reduced coagulant consumption and improved outlet qualities. Due to the long retention time in separation stages, these models are mostly based on feed-forward (FF) models. This paper demonstrates the improvement of such models with feed-back (FB) concepts with simplifications, making it possible to use even in systems with long separation stages. Full-scale case studies from a drinking water treatment plant and a WWTP are presented. The model qualities were improved by the dosage adjustment of the FB model, ranging from 66% to 197% of the FF model. Hence, the outlet qualities became more stable and coagulant consumption was further reduced in the range of 3.7%-15.5%.

  6. The improvement paradox in project contexts: A clue to the way forward?

    OpenAIRE

    Brady, Tim; Maylor, Harvey

    2010-01-01

    This paper emerged as the authors struggled to make sense of a phenomenon observed during fieldwork. We had entered the field knowing a project-based organisation to be performing poorly and to be in need of improvement in its management of projects. We expected that the organisation would be actively trying to achieve the necessary improvement. We found that the organisation as a matter of course was not pursuing any improvement activities. It was only following a crisis wi...

  7. Prospects for improving the LHC W boson mass measurement with forward muons.

    Science.gov (United States)

    Bozzi, Giuseppe; Citelli, Luca; Vesterinen, Mika; Vicini, Alessandro

    Measurements of the W boson mass are planned by the ATLAS and CMS experiments, but for the time being, these may be unable to compete with the current world average precision of 15 MeV, due to uncertainties in the PDFs. We discuss the potential of a measurement by the LHCb experiment based on the charged lepton transverse momentum [Formula: see text] spectrum in [Formula: see text] decays. The unique forward acceptance of LHCb means that the PDF uncertainties would be anti-correlated with those of [Formula: see text] based measurements by ATLAS and CMS. We compute an average of ATLAS, CMS and LHCb measurements of [Formula: see text] from the [Formula: see text] distribution. Considering PDF uncertainties, this average is a factor of 1.3 more precise than an average of ATLAS and CMS alone. Despite the relatively low rate of W production in LHCb, we estimate that with the Run-II dataset, a measurement could be performed with sufficient experimental precision to exploit this anti-correlation in PDF uncertainties. The modelling of the lepton-pair transverse momentum distribution in the neutral current Drell-Yan process could be a limiting factor of this measurement and will deserve further studies.

  8. Prospects for improving the LHC W boson mass measurement with forward muons

    Energy Technology Data Exchange (ETDEWEB)

    Bozzi, Giuseppe, E-mail: giuseppe.bozzi@mi.infn.it [Dipartimento di Fisica, Sezione di Milano, Università degli Studi di Milano and INFN, Via Celoria 16, 20133, Milan (Italy); Citelli, Luca, E-mail: luca.citelli@studenti.unimi.it [Dipartimento di Fisica, Universita degli Studi di Milano, Via Celoria 16, 20133, Milan (Italy); Vesterinen, Mika, E-mail: mika.vesterinen@cern.ch [Physikalisches Institut, Ruprecht-Karls-Universitat, Im Neuenheimer Feld, 226, 69120, Heidelberg (Germany); Vicini, Alessandro, E-mail: alessandro.vicini@mi.infn.it [Dipartimento di Fisica, Universita degli Studi di Milano and INFN Sezione di Milano and TIF Lab, Via Celoria 16, 20133, Milan (Italy)

    2015-12-17

    Measurements of the W boson mass are planned by the ATLAS and CMS experiments, but for the time being, these may be unable to compete with the current world average precision of 15 MeV, due to uncertainties in the PDFs. We discuss the potential of a measurement by the LHCb experiment based on the charged lepton transverse momentum p{sub T}{sup ℓ} spectrum in W→μν decays. The unique forward acceptance of LHCb means that the PDF uncertainties would be anti-correlated with those of p{sub T}{sup ℓ} based measurements by ATLAS and CMS. We compute an average of ATLAS, CMS and LHCb measurements of m{sub W} from the p{sub T}{sup ℓ} distribution. Considering PDF uncertainties, this average is a factor of 1.3 more precise than an average of ATLAS and CMS alone. Despite the relatively low rate of W production in LHCb, we estimate that with the Run-II dataset, a measurement could be performed with sufficient experimental precision to exploit this anti-correlation in PDF uncertainties. The modelling of the lepton-pair transverse momentum distribution in the neutral current Drell–Yan process could be a limiting factor of this measurement and will deserve further studies.

  9. Prospects for improving the LHC W boson mass measurement with forward muons

    Energy Technology Data Exchange (ETDEWEB)

    Bozzi, Giuseppe [INFN, Sezione di Milano, Milan (Italy); Universita degli Studi di Milano, Dipartimento di Fisica, Milan (Italy); Citelli, Luca [Universita degli Studi di Milano, Dipartimento di Fisica, Milan (Italy); Vesterinen, Mika [Physikalisches Institut, Ruprecht-Karls-Universitat, Heidelberg (Germany); Vicini, Alessandro [TIF Lab, Ravina di Trento (Italy); INFN, Sezione di Milano, Milan (Italy); Universita degli Studi di Milano, Dipartimento di Fisica, Milan (Italy)

    2015-12-15

    Measurements of the W boson mass are planned by the ATLAS and CMS experiments, but for the time being, these may be unable to compete with the current world average precision of 15 MeV, due to uncertainties in the PDFs. We discuss the potential of a measurement by the LHCb experiment based on the charged lepton transverse momentum p{sub T}{sup l} spectrum in W → μν decays. The unique forward acceptance of LHCb means that the PDF uncertainties would be anti-correlated with those of p{sub T}{sup l} based measurements by ATLAS and CMS. We compute an average of ATLAS, CMS and LHCb measurements of m{sub W} from the p{sub T}{sup l} distribution. Considering PDF uncertainties, this average is a factor of 1.3 more precise than an average of ATLAS and CMS alone. Despite the relatively low rate of W production in LHCb, we estimate that with the Run-II dataset, a measurement could be performed with sufficient experimental precision to exploit this anti-correlation in PDF uncertainties. The modelling of the lepton-pair transverse momentum distribution in the neutral current Drell-Yan process could be a limiting factor of this measurement and will deserve further studies. (orig.)

  10. A new class of draw solutions for minimizing reverse salt flux to improve forward osmosis desalination.

    Science.gov (United States)

    Nguyen, Hau Thi; Nguyen, Nguyen Cong; Chen, Shiao-Shing; Ngo, Huu Hao; Guo, Wenshan; Li, Chi-Wang

    2015-12-15

    The applications of forward osmosis (FO) have been hindered because of the lack of an optimal draw solution. The reverse salt flux from the draw solution not only reduces the water flux but also increases the cost of draw solute replenishment. Therefore, in this study, Tergitol NP7 and NP9 with a long straight carbon chain and low critical micelle concentration (CMC) were coupled with highly charged ethylenediaminetetraacetic acid (EDTA) as an innovative draw solution to minimize reverse salt diffusion in FO for the first time. The results showed that the lowest reverse salt flux of 0.067 GMH was observed when 0.1M EDTA-2Na coupled with 15mM NP7 was used as a draw solution and deionized water was used as a feed solution in FO mode (active layer facing with the feed solution). This is due to the hydrophobic interaction between the tails of NP7 and the FO membrane, thus creating layers on the membrane surface and constricting the FO membrane pores. Moreover, 1M EDTA-2Na coupled with 15mM NP7 is promising as an optimal draw solution for brackish water and sea water desalination. Average water fluxes of 7.68, 6.78, and 5.95 LMH were achieved when brackish water was used as a feed solution (5, 10, and 20g/L NaCl), and an average water flux of 3.81 LMH was achieved when sea water was used as a feed solution (35g/L NaCl). The diluted draw solution was recovered using a nanofiltration (NF-TS80) membrane with a high efficiency of 95% because of the high charge and large size of the draw solution.

  11. New packet scheduling algorithm in wireless CDMA data networks

    Science.gov (United States)

    Wang, Yu; Gao, Zhuo; Li, Shaoqian; Li, Lemin

    2002-08-01

    The future 3G/4G wireless communication systems will provide internet access for mobile users. Packet scheduling algorithms are essential for QoS of diversified data traffics and efficient utilization of radio spectrum.This paper firstly presents a new packet scheduling algorithm DSTTF under the assumption of continuous transmission rates and scheduling intervals for CDMA data networks . Then considering the constraints of discrete transmission rates and fixed scheduling intervals imposed by the practical system, P-DSTTF, a modified version of DSTTF, is brought forward. Both scheduling algorithms take into consideration of channel condition, packet size and traffic delay bounds. The extensive simulation results demonstrate that the proposed scheduling algorithms are superior to some typical ones in current research. In addition, both static and dynamic wireless channel model of multi-level link capacity are established. These channel models sketch better the characterizations of wireless channel than two state Markov model widely adopted by the current literature.

  12. Operational research for improved tuberculosis control: the scope, the needs and the way forward.

    Science.gov (United States)

    Lienhardt, C; Cobelens, F G J

    2011-01-01

    The promotion of research is one of the main components of the World Health Organizations Stop TB Strategy, which includes 'programme-based operational research (OR)' and 'research on introducing new tools into practice'. The importance of OR in improving tuberculosis (TB) control was recognised a long time ago, and historical OR studies have been instrumental in the development of major strategies for TB control. Although a growing number of OR projects are being conducted in the world today, little is known about their results or their likely impact on TB control programmes. As funding organisations increasingly recognise the need for OR, we propose a rational framework to conduct OR, which covers a spectrum from local setting-oriented to international policy guiding research, and determines the relevance, replicability and generalisability of the results. OR in TB control is aimed at 1) improving programme performance; 2) assessing the feasibility, effectiveness and impact of new strategies or interventions on TB control; and 3) collecting evidence to guide policy recommendations on specific interventions. This requires strengthened capacity to plan and conduct OR in low-income countries and appropriate support to conduct both nationally and internationally led OR projects. Suggestions are made for potential steps for improved purpose-driven OR, which may help to improve TB control locally and inform policy recommendations internationally.

  13. Node design in optical packet switched networks

    DEFF Research Database (Denmark)

    Nord, Martin

    2006-01-01

    The thesis discusses motivation, realisation and performance of the Optical Packet Switching (OPS) network paradigm. The work includes proposals for designs and methods to efficiently use both the wavelength- and time domain for contention resolution in asynchronous operation. The project has also...... adapting network performance to the different acceptable packet loss rate levels of supported applications, while improving overall bandwidth efficiency. The project has evaluated QoS differentiation methods and proposed schemes with improved efficiency, which also include jitter sensitivity as a Qo...... proposed parallel designs to overcome scalability constraints and to support migration scenarios. Furthermore, it has proposed and demonstrated optical input processing schemes for hybrids networks to simultaneously support OPS and Optical Circuit Switching. Quality of Service (QoS) differentiation enables...

  14. 概率转发的AODV路由协议的改进%Improvement of AODV routing protocol based on probabilistic forwarding

    Institute of Scientific and Technical Information of China (English)

    荆文礼; 乐红兵

    2011-01-01

    Ad hoc on-demand distance vector routing (AODV) send Route REQuest (RREQ) through flooding when it wantto search routing. Flooding can find the routing but the delay is long and it is generate many retransmission. Even worse, it is easily bring broadcast storm. This paper researched AODV routing protocol and gived a mechanism based on probabilistic forward. This mechanism choose different probabilistic forwarding RREQ through neighbor's numbers. The NS2 simulation results shows that this idea can decrease delay and can increase thoughput as well as packet delivery fraction ratio.%按需距离矢量路由协议(AODV)在寻找路由时是通过洪泛法发送路由请求(RREQ)实现的。洪泛法能较好地找到所需的路由,但时延较大,产生了许多不必要的重传,易造成广播风暴。针对AODV路由协议,提出了一种基于概率转发的机制。这种机制根据邻居节点的个数,选用不同的概率转发RREQ。NS2仿真模拟结果表明,该方法可以降低时延,提高吞吐量,提高分组投递率。

  15. A Modified Structure for Feed Forward Active Noise Control Systems With Improved Performa

    Directory of Open Access Journals (Sweden)

    P.Babu

    2010-09-01

    Full Text Available Several approaches have been introduced in literature for active noise control (ANC systems. SinceFxLMS algorithm appears to be the best choice as a controller filter, researchers tend to improveperformance of ANC systems by enhancing and modifying this algorithm. In this paper, the existingFxLMS algorithm is modified which provides a new structure for improving the noise reduction andconvergence rate. Here the proposed method uses two variable step sizes, one for control filter andanother for modelling filter. The control filter step size is varied based on the secondary path thresholdsignal l dˆ . The modelling filter step size is varied based on error signal f (n . It is shown that in theproposed method ANC system noise reduction rate and convergence rate are improved dynamically thanthe FxLMS variable step size methods. The computer simulations results indicate effectiveness of theproposed method.

  16. Embedded wavelet packet transform technique for texture compression

    Science.gov (United States)

    Li, Jin; Cheng, Po-Yuen; Kuo, C.-C. Jay

    1995-09-01

    A highly efficient texture compression scheme is proposed in this research. With this scheme, energy compaction of texture images is first achieved by the wavelet packet transform, and an embedding approach is then adopted for the coding of the wavelet packet transform coefficients. By comparing the proposed algorithm with the JPEG standard, FBI wavelet/scalar quantization standard and the EZW scheme with extensive experimental results, we observe a significant improvement in the rate-distortion performance and visual quality.

  17. Improving the Response Time of Online Buyers in Nigeria: The Way Forward

    Directory of Open Access Journals (Sweden)

    Anu Ajayi

    2008-04-01

    Full Text Available Though electronic commerce (e-commerce is yet at its infancy in Africa and other developing countries, several factors such as lack of trust, technology infrastructure, funds and shortage of manpower can be attributed to this. However, the current model of web server response time as it pertains to developing countries will however hinder its general acceptability. The ability of E-commerce sites to satisfy and retain their customers will no doubt depend largely on the quality of their service delivery. Existing Quality of Service (QoS provisioning architectures for E-commerce placed emphasis on WWW server and bandwidth inadequacies. This study identified the necessity to include client’s device limitation into e-commerce QoS frameworks especially for web applications to be deployed in Africa, if user-perceived QoS (usually measured by response time is to be improved. As indicated in the study, client’s device limitation is an important factor that should be given priority. Most computer users in Africa due to the high cost of ownership of PCs used outdated or cloned PCs whose performance could not be guaranteed

  18. Evaluation and Improvement of Spectral Features for the Detection of Buried Explosive Hazards Using Forward-Looking Ground-Penetrating Radar

    Science.gov (United States)

    2012-07-01

    for the NIITEK ground penetrating radar using order weighted averaging operators for landmine detection”, Proc. SPIE 5415, 953-962 (2004). [9] Sun, Y...and Li, J., "Plastic landmine detection using time-frequency analysis for forward-looking ground - penetrating radar ”, Proc. SPIE 5089, 851-862...REPORT Evaluation and Improvement of Spectral Features for the Detection of Buried Explosive Hazards Using Forward-Looking Ground - Penetrating Radar 14

  19. Group-normalized processing of complex wavelet packets

    Institute of Scientific and Technical Information of China (English)

    石卓尔; 保铮

    1997-01-01

    Linear phase is not possible for real valued FIR QMF, while linear phase FIR biorthogonal wavelet filter banks make the mean squared error of the constructed signal exceed that of the quantization error. W Lawton’ s method for complex valued wavelets construction is extended to generate the complex valued compactly supported wavelet packets that are symmetrical and unitary orthogonal; then well-defined wavelet packets are chosen by the analysis remarks on their time-frequency characteristics. Since the traditional wavelel packets transform coefficients do not exactly represent the strength of signal components, a modified adaptive wavelets transform, group-normalized wavelet packet transform (GNWPT), is presented and utilized for target extraction from formidable clutter or noises with the time-frequency masking technique. The extended definition of lp-norm entropy improves the performance cf GNWPT. Similar method can also be applied to image enhancement, clutter and noise suppression, optimal detection

  20. Bohmian trajectories of Airy packets

    Energy Technology Data Exchange (ETDEWEB)

    Nassar, Antonio B., E-mail: anassar@hw.com [Science Department, Harvard-Westlake School, 3700 Coldwater Canyon, Studio City, 91604 (United States); Department of Sciences, University of California, Los Angeles, Extension Program, 10995 Le Conte Avenue, Los Angeles, CA 90024 (United States); Miret-Artés, Salvador [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid (Spain)

    2014-09-15

    The discovery of Berry and Balazs in 1979 that the free-particle Schrödinger equation allows a non-dispersive and accelerating Airy-packet solution has taken the folklore of quantum mechanics by surprise. Over the years, this intriguing class of wave packets has sparked enormous theoretical and experimental activities in related areas of optics and atom physics. Within the Bohmian mechanics framework, we present new features of Airy wave packet solutions to Schrödinger equation with time-dependent quadratic potentials. In particular, we provide some insights to the problem by calculating the corresponding Bohmian trajectories. It is shown that by using general space–time transformations, these trajectories can display a unique variety of cases depending upon the initial position of the individual particle in the Airy wave packet. Further, we report here a myriad of nontrivial Bohmian trajectories associated to the Airy wave packet. These new features are worth introducing to the subject’s theoretical folklore in light of the fact that the evolution of a quantum mechanical Airy wave packet governed by the Schrödinger equation is analogous to the propagation of a finite energy Airy beam satisfying the paraxial equation. Numerous experimental configurations of optics and atom physics have shown that the dynamics of Airy beams depends significantly on initial parameters and configurations of the experimental set-up.

  1. An Internet-based store-and-forward video home telehealth system for improving asthma outcomes in children.

    Science.gov (United States)

    Chan, Debora S; Callahan, Charles W; Sheets, Scott J; Moreno, Carol N; Malone, Francis J

    2003-10-01

    The adherence and disease-control outcomes associated with the use of an Internet-based store-and-forward video home telehealth system to manage asthma in children were studied. Pediatric patients with persistent asthma were provided with home computers and Internet access and monitored biweekly over the Internet. All patients were seen in the pediatric clinic at 0, 2, 6, 12, and 24 weeks. Half of the patients received asthma education in person and half via an interactive Web site. Adherence measures were assessed by therapeutic and diagnostic monitoring. Therapeutic monitoring included digital videos of patients using their controller medication inhaler. Diagnostic monitoring included an asthma symptom diary and a video of peak flow meter use. Videos were submitted electronically twice a week by using in-home telemonitoring with store-and-forward technology. Feedback was provided electronically to each patient. Disease control was assessed by examining quality of life, utilization of services, rescue-therapy use, symptom control, satisfaction with home telemonitoring, and retention of asthma knowledge. Patients were randomly assigned to an asthma education group (Internet versus office), and the data were analyzed by comparing results for study days 0-90 and 91-180. Ten children participated. A total of 321 videos of inhaler use and 309 videos of peak flow meter use were submitted. Inhaler technique scores improved significantly in the second study period. Submission of diagnostic monitoring videos and asthma diary entries decreased significantly. Peak flow values as a percentage of personal best values increased significantly. Overall, there was no change in quality of life reported by patients. However, the caregivers in the virtual-education group reported an increase in the patients' quality-of-life survey scores. Emergency department visits and hospital admissions for asthma were avoided. Rescue therapy was infrequent. A high rate of satisfaction with home

  2. Investigating Dependences in Packet-queues

    Institute of Scientific and Technical Information of China (English)

    Cao Weihua(曹卫华); Girigi Deogratias; Wu Min

    2004-01-01

    Many packet communication networks carry several classes of traffic,each with its own service characteristics. The packet arrival processes from each source are also often bursty (highly variable),which can contribute to long packet delay. Ssociated dependence among successive service times and between service times and inter arrival times also can be for packet queues involving variable packet lengths. These dependence effects are demonstrated analytically by considering a multi class single server queue with batch Poisson arrival process.

  3. More Than 10 Gbps Photonic Packet-Switched Networks Using WDM-Based Packet Compression

    Institute of Scientific and Technical Information of China (English)

    Hiroaki Harai; Naoya Wada

    2003-01-01

    We propose photonic packet-switched networks in which more than 10Gbps optical packets are transferred. WDM- based packet compression at edge nodes plays an important role in resolving interface gap between core and metro.

  4. DESIGN OF AN ARRAYED WAVEGUIDE GRATINGS BASED OPTICAL PACKET SWITCH

    Directory of Open Access Journals (Sweden)

    VAIBHAV SHUKLA

    2016-12-01

    Full Text Available Optical packet switching is considered as the future of data transfer technologyin combination with middle-aged electronics. The biggest challenge encountered in optical packet switching is the lack of optical buffers for storing the contending packets. Therefore, for the contention resolution of packets, a temporary storage in terms of fiber delay lines is used. This task is accomplished by an optical packet switch. In this paper, a design modification in the AWGR (Arrayed Waveguide Grating Router is presented for improving the switch performance. The power budget analysis of the switch is also presented to estimate the sufficient power level of the switch. The obtained results clearly reveal that the architecture presented in this paper can be operated in micro-watts in comparison to the earlier optical switch which operates in milli watts regime. Finally, simulation results are presented to obtain packet loss probability and average delay. Even at the higher load of 0.6, the switch presented in this paper provides a very low loss probability (10^6 and delay remain within 2 slots.

  5. A Hybrid Backward-Forward Iterative Model for Improving Capacity Building of Earth Observations for Sustainable Societal Application

    Science.gov (United States)

    Hossain, F.; Iqbal, N.; Lee, H.; Muhammad, A.

    2015-12-01

    When it comes to building durable capacity for implementing state of the art technology and earth observation (EO) data for improved decision making, it has been long recognized that a unidirectional approach (from research to application) often does not work. Co-design of capacity building effort has recently been recommended as a better alternative. This approach is a two-way street where scientists and stakeholders engage intimately along the entire chain of actions from design of research experiments to packaging of decision making tools and each party provides an equal amount of input. Scientists execute research experiments based on boundary conditions and outputs that are defined as tangible by stakeholders for decision making. On the other hand, decision making tools are packaged by stakeholders with scientists ensuring the application-specific science is relevant. In this talk, we will overview one such iterative capacity building approach that we have implemented for gravimetry-based satellite (GRACE) EO data for improved groundwater management in Pakistan. We call our approach a hybrid approach where the initial step is a forward model involving a conventional short-term (3 day) capacity building workshop in the stakeholder environment addressing a very large audience. In this forward model, the net is cast wide to 'shortlist' a set of highly motivated stakeholder agency staffs who are then engaged more directly in 1-1 training. In the next step (the backward model), these short listed staffs are then brought back in the research environment of the scientists (supply) for 1-1 and long-term (6 months) intense brainstorming, training, and design of decision making tools. The advantage of this backward model is that it allows for a much better understanding for scientists of the ground conditions and hurdles of making a EO-based scientific innovation work for a specific decision making problem that is otherwise fundamentally impossible in conventional

  6. A Better Memoryless Online Algorithm for FIFO Buffering Packets with Two Values

    CERN Document Server

    Li, Fei

    2010-01-01

    We consider scheduling weighted packets in a capacity-bounded buffer. In this model, there is a buffer with a limited capacity B such that at any time, the buffer cannot accommodate more than B packets. Packets arrive over time. Each packet has a non-negative real value. Packets do not expire and they leave the buffer only because either we send them or we drop them. The packets that have left the buffer will not be reconsidered for delivery any more. In each time step, at most one packet in the buffer can be sent. The order in which the packets are sent should comply with the order of their arriving time. The objective is to maximize the total value of the packets sent in an online manner. In this paper, we study a variant of this model in which packets have value 1 or alpha > 1. We present a deterministic memoryless 1.305-competitive algorithm, improving the previously best known result 1.544 (Kesselman and Mansour. Journal of Algorithms 2003). In designing our algorithm, we apply a few new ideas. We do not...

  7. Long Maturity Forward Rates

    DEFF Research Database (Denmark)

    Christiansen, Charlotte

    2001-01-01

    The paper aims to improve the knowledge of the empirical properties of the long maturity region of the forward rate curve. Firstly, the theoretical negative correlation between the slope at the long end of the forward rate curve and the term structure variance is recovered empirically and found...... to be statistically significant. Secondly, the expectations hypothesis is analyzed for the long maturity region of the forward rate curve using "forward rate" regressions. The expectations hypothesis is numerically close to being accepted but is statistically rejected. The findings provide mixed support...

  8. Efficient Optimal Packet Management in Distributed Wireless Ad-Hoc Environment using DST

    Directory of Open Access Journals (Sweden)

    J. Amudhavel,

    2010-06-01

    Full Text Available Effective Packet Management (PM is widely used in distributed wireless environments to reduce the access costs and improve data availability. Therefore, packet transmission in wireless environment becomes one of the important challenges for effective data transfer and maintaining the reliability of data . This paper addresses theissues in maintaining the effective packet management in the wireless ad hoc network environments and proposes an effective solution for the same using an optimization technique. The proposed approach concentrates on effective packet management in the dynamic environment and maintaining local consistency issues which occur in the Distributed Wireless Ad-Hoc network environment. Therefore, this paper evaluates the efficiency of existing techniques, and proposes a more efficient local packet management algorithm. The new algorithm leverages existing techniques which are shown to be efficient. This paper also addresses the advantages and disadvantages of various packet management and its issues.

  9. Packet scheduling for OFDMA based relay networks

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The combination of relay networks with orthogonal frequency division multiple access (OFDMA) has been proposed as a promising solution for the next generation wireless system. Considering different traffic classes and user quality of service (QoS), three efficient scheduling algorithms are introduced in such networks. The round-robin (RR) algorithm in relay networks serves as a performance benchmark. Numerical results show that the proposed algorithms achieve significant improvement on system throughput and decrease system packet loss rate, compared with the RR and absence of relaying system (traditional network). Furthermore, comparisons have been carried out among the three proposed algorithms.

  10. Key Technologies for Optical Packet Switching

    Institute of Scientific and Technical Information of China (English)

    Akira; Okada

    2003-01-01

    The paper describes our recent progress on key technologies and components for realizing optical packet switching, including an out-of-band optical label switching technique, an optical packet synchronizer and a burst-mode optical receiver.

  11. Key Technologies for Optical Packet Switching

    Institute of Scientific and Technical Information of China (English)

    Akira Okada

    2003-01-01

    The paper describes our recent progress on key technologies and components for realizing optical packet switching,including an out-of-band optical label switching technique, an optical packet synchronizer and a burst-mode optical receiver.

  12. Orthogonal Matrix-Valued Wavelet Packets

    Institute of Scientific and Technical Information of China (English)

    Qingjiang Chen; Cuiling Wang; Zhengxing Cheng

    2007-01-01

    In this paper,we introduce matrix-valued multiresolution analysis and matrixvalued wavelet packets. A procedure for the construction of the orthogonal matrix-valued wavelet packets is presented. The properties of the matrix-valued wavelet packets are investigated. In particular,a new orthonormal basis of L2(R,Cs×s) is obtained from the matrix-valued wavelet packets.

  13. Dynamics of quantum wave packets

    Energy Technology Data Exchange (ETDEWEB)

    Gosnell, T.R.; Taylor, A.J.; Rodriguez, G.; Clement, T.S.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to develop ultrafast laser techniques for the creation and measurement of quantum vibrational wave packets in gas phase diatomic molecules. Moreover, the authors sought to manipulate the constitution of these wave packets in terms of harmonic-oscillator basis wavefunctions by manipulating the time-dependent amplitude and phase of the incident ultrashort laser pulse. They specifically investigated gaseous diatomic potassium (K{sub 2}), and discovered variations in the shape of the wave packets as a result of changing the linear chirp in the ultrashort preparation pulse. In particular, they found evidence for wave-packet compression for a specific degree of chirp. Important ancillary results include development of new techniques for denoising and deconvolution of femtosecond time traces and techniques for diagnosing the phase and amplitude of the electric field of femtosecond laser pulses.

  14. Ancient Chinese Bronzes: Teacher's Packet.

    Science.gov (United States)

    Smithsonian Institution, Washington, DC. Arthur M. Sackler Gallery.

    The focus of this teacher's packet is the bronze vessels made for the kings and great families of the early Chinese dynasties between 1700 B.C. and 200 A.D. The materials in the guide are intended for use by teachers and students visiting the exhibition, "The Arts of China," at the Arthur M. Sackler Gallery of the Smithsonian Institution…

  15. USAID Forward

    Data.gov (United States)

    US Agency for International Development — USAID Forward is an effort to strengthen the Agency by embracing new partnerships, investing in the catalytic role of innovation and demanding a relentless focus on...

  16. IEATH: Improved Energy Aware and Two Hop Multipath Routing Protocol in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    S. Saqaeeyan

    2012-06-01

    Full Text Available Wireless sensor networks in terms of energy sources are limited. Furthermore due to this type of network infrastructure wireless communications and channel errors not possible to reach the correct packet to the destination exists; hence the proposing algorithms to improve the quality of service in these networks and sending packets are very important. In this paper we proposed a reliable and energy aware packet delivery mechanism to ensure quality of service in wireless sensor networks. In our proposed algorithm to ensure that a packet of information sent to the destination, the multi-path Forwarding method is used; So that several copies of an information packet via separate routes are sent to the destination, also routing decisions in this way occurs by considering the remaining energy in the neighborhood of nodes that are located in two hop of sender node. Simulation results show that the rate of release of data packets reduced in this way and thus the reliability of packet is increased, also the energy efficiency of sensor nodes effectively improved. Therefore this algorithm increase overall lifetime in wireless sensor networks.

  17. System and method for forward error correction

    Science.gov (United States)

    Cole, Robert M. (Inventor); Bishop, James E. (Inventor)

    2006-01-01

    A system and method are provided for transferring a packet across a data link. The packet may include a stream of data symbols which is delimited by one or more framing symbols. Corruptions of the framing symbol which result in valid data symbols may be mapped to invalid symbols. If it is desired to transfer one of the valid data symbols that has been mapped to an invalid symbol, the data symbol may be replaced with an unused symbol. At the receiving end, these unused symbols are replaced with the corresponding valid data symbols. The data stream of the packet may be encoded with forward error correction information to detect and correct errors in the data stream.

  18. SECURE SERVICE DISCOVERY BASED ON PROBE PACKET MECHANISM FOR MANETS

    Directory of Open Access Journals (Sweden)

    S. Pariselvam

    2015-03-01

    Full Text Available In MANETs, Service discovery process is always considered to be crucial since they do not possess a centralized infrastructure for communication. Moreover, different services available through the network necessitate varying categories. Hence, a need arises for devising a secure probe based service discovery mechanism to reduce the complexity in providing the services to the network users. In this paper, we propose a Secure Service Discovery Based on Probe Packet Mechanism (SSDPPM for identifying the DoS attack in MANETs, which depicts a new approach for estimating the level of trust present in each and every routing path of a mobile ad hoc network by using probe packets. Probing based service discovery mechanisms mainly identifies a mobile node’s genuineness using a test packet called probe that travels the entire network for the sake of computing the degree of trust maintained between the mobile nodes and it’s attributed impact towards the network performance. The performance of SSDPPM is investigated through a wide range of network related parameters like packet delivery, throughput, Control overhead and total overhead using the version ns-2.26 network simulator. This mechanism SSDPPM, improves the performance of the network in an average by 23% and 19% in terms of packet delivery ratio and throughput than the existing service discovery mechanisms available in the literature.

  19. Perceptual Wavelet packet transform based Wavelet Filter Banks Modeling of Human Auditory system for improving the intelligibility of voiced and unvoiced speech: A Case Study of a system development

    Directory of Open Access Journals (Sweden)

    Ranganadh Narayanam

    2015-10-01

    Full Text Available The objective of this project is to discuss a versatile speech enhancement method based on the human auditory model. In this project a speech enhancement scheme is being described which meets the demand for quality noise reduction algorithms which are capable of operating at a very low signal to noise ratio. We will be discussing how proposed speech enhancement system is capable of reducing noise with little speech degradation in diverse noise environments. In this model to reduce the residual noise and improve the intelligibility of speech a psychoacoustic model is incorporated into the generalized perceptual wavelet denoising method to reduce the residual noise. This is a generalized time frequency subtraction algorithm which advantageously exploits the wavelet multirate signal representation to preserve the critical transient information. Simultaneous masking and temporal masking of the human auditory system are modeled by the perceptual wavelet packet transform via the frequency and temporal localization of speech components. To calculate the bark spreading energy and temporal spreading energy the wavelet coefficients are used from which a time frequency masking threshold is deduced to adaptively adjust the subtraction parameters of the discussed method. To increase the intelligibility of speech an unvoiced speech enhancement algorithm also integrated into the system.

  20. Foreign Material in the Gastrointestinal Tract: Cocaine Packets

    Directory of Open Access Journals (Sweden)

    Nurten Turkel Kucukmetin

    2014-01-01

    Full Text Available Smuggling drugs by swallowing or inserting into a body cavity is not only a serious and growing international crime, but can also lead to lethal medical complications. The most common cause of death in ‘body packers', people transporting drugs by ingesting a packet into the gastrointestinal tract, is acute drug toxicity from a ruptured packet. However, more than 30 years after the initial report of body packing, there is still no definitive treatment protocol for the management of this patient group. The treatment strategy is determined according to the particular condition of the patient and the clinical experience of the treatment center. Surgical intervention is also less common now, due to both the use of improved packaging materials among smugglers and a shift towards a more conservative medical approach. Herein, we report a case of toxicity from ingested packets of cocaine that leaked and, despite surgery, resulted in exitus of the patient.

  1. Causal evolution of wave packets

    CERN Document Server

    Eckstein, Michał

    2016-01-01

    Drawing from the optimal transport theory adapted to the relativistic setting we formulate the principle of a causal flow of probability and apply it in the wave packet formalism. We demonstrate that whereas the Dirac system is causal, the relativistic-Schr\\"odinger Hamiltonian impels a superluminal evolution of probabilities. We quantify the causality breakdown in the latter system and argue that, in contrast to the popular viewpoint, it is not related to the localisation properties of the states.

  2. Study of denial of service attack & improved deterministic packet marking scheme based on IPv6%基于IPv6拒绝服务攻击和改进确定包算法研究

    Institute of Scientific and Technical Information of China (English)

    赵树枫

    2012-01-01

    This paper studied the DoS attacks under IPv6, and according to the new features of IPv6 protocol, proposed the ADPM-v6 scheme based on improved MAC-authentication. By using a new IPv6 feature hop-by-hop options and the improved MAC authentication method, the scheme could quickly locate the source of attacker. The scheme could prevent compromised router which could forge the marking effectively. Simultaneous, analysis of a real attack environment verifying IPv6 packet size distribution, made the algorithm have a strong practicality and more effective. The implementation and evaluation shows that the ADPM-v6 scheme can greatly reduce the reconstruction time and reduce the amount of reconstruction computing and false positive.%对IPv6下拒绝服务攻击进行了研究,并根据IPv6协议的特点,提出一种基于IPv6的MAC认证改进确定包标记(ADPM-v6)算法.ADPM -v6利用IPv6新特性,即逐跳选项和改进的MAC认证方法,有效解决了受控路由器修改标记的问题,能直接快速地追踪攻击源.同时分析验证了IPv6真实攻击环境的数据包大小分布,使得算法有效且更具有较强的实用性.理论分析和仿真实验结果表明,该算法在IPv6下大大缩短了重构时间,减少了重构计算量和误报率.

  3. Differential AR algorithm for packet delay prediction

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Different delay prediction algorithms have been applied in multimedia communication, among which linear prediction is attractive because of its low complexity. AR (auto regressive) algorithm is a traditional one with low computation cost, while NLMS (normalize least mean square) algorithm is more precise. In this paper, referring to ARIMA (auto regression integrated with moving averages) model, a differential AR algorithm (DIAR) is proposed based on the analyses of both AR and NLMS algorithms. The prediction precision of the new algorithm is about 5-10 db higher than that of the AR algorithm without increasing the computation complexity.Compared with NLMS algorithm, its precision slightly improves by 0.1 db on average, but the algorithm complexity reduces more than 90%. Our simulation and tests also demonstrate that this method improves the performance of the average end-to-end delay and packet loss ratio significantly.

  4. Packet Skipping and Network Coding for Delay-Sensitive Network Communication

    CERN Document Server

    Aoun, Marc; Argyriou, Antonios; Denteneer, Dee; van der Stok, Peter

    2012-01-01

    We provide an analytical study of the impact of packet skipping and opportunistic network coding on the timely communication of messages through a single network element. In a first step, we consider a single-server queueing system with Poisson arrivals, exponential service times, and a single buffer position. Packets arriving at a network node have a fixed deadline before which they should reach the destination. To preserve server capacity, we introduce a thresholding policy, based on remaining time until deadline expiration, to decide whether to serve a packet or skip its service. The obtained goodput improvement of the system is derived, as well as the operating conditions under which thresholding can enhance performance. Subsequently, we focus our analysis on a system that supports network coding instead of thresholding. We characterize the impact of network coding at a router node on the delivery of packets associated with deadlines. We model the router node as a queueing system where packets arrive from...

  5. Round robin based Secure-Aware Packet Scheduling in Wireless Networks

    Directory of Open Access Journals (Sweden)

    Arun Raj

    2013-03-01

    Full Text Available Packet scheduling algorithms enhances the packet delivery rate effectively in wireless networks; it helps to improve the quality of service of the wireless networks. Many algorithms had been deployed in the area of packet scheduling in wireless networks but less attention is paid to security. Some algorithms which offer security often compromise performances such as schedulability, this is not desirable. This performance problem will become worse when the system is under heavy load. In this paper we propose Round robin based Secure- Aware Packet Scheduling algorithm (RSAPS for wireless networks which focuses on secure scheduling. RSAPS is an adaptive algorithm which gives priority to scheduling when system is under heavy load. Under light load RSAPS provide maximum security for the incoming packets. Simulation has been performed using the proposed method and compared with existing algorithms SPSS and ISPAS. And it is found that RSAPS shows excellent scheduling quality holding the security levels.

  6. A New Wireless Packet Scheduling Algorithm Based on EDF and Its Application in Multi-bottleneck Networks

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Most of current wireless packet scheduling algorithms aim at resource allocation as fairly as possible or maximizing throughput. This paper proposed a new packet scheduling algorithm that aims at satisfying delay requirement and is the improvement of earliest due first (EDF) algorithm in wired networks. The main idea is to classify the packets based on their delay bound, scheduling the most "urgent" class of user and the users that have the best channel condition with higher priority. This algorithm can easily integrate with common buffer management algorithms, when buffer management algorithm cannot accept new arrival packets, try to modify scheduling policy. Packet scheduling algorithms in multiple bottleneck wireless networks were also discussed. A new variable multi-hop factor was defined to estimate the congestion situation (including channel condition) of future hops.Multi-hop factor can be integrated into packet scheduling algorithms as assistant and supplement to improve its performance in multi-bottleneck wireless networks.

  7. A Fuzzy Logic Classification of Incoming Packet for VoIP

    Directory of Open Access Journals (Sweden)

    Suardinata

    2010-08-01

    Full Text Available The Voice over Internet Protocol (VoIP technology is cheaper and does not need new infrastructure because it has available in the global computer (IP network. Unfortunately, transition from PSTN to VoIP networks have emerged new problems in voice quality. Furthermore, the transmission of voice over IP networks can generate network congestion due to weak supervision of the traffic incoming packet, queuing and scheduling. This congestion affects the Quality of Service (QoS such as delay, packet drop and packet loss. Packet delay effects will affect the other QoS such as: unstable voice packet delivery, packet jitter, packet loss and echo. Priority Queuing (PQ algorithm is a popular technique used in the VoIP network to reduce delays. But, the method can result in repetition. This recursive leads to the next queue starved. To solving problems, there are three phases namely queuing, classifying and scheduling. It will be applied to the fuzzy inference system to classify the queuing incoming packet (voice, video and text. To justify the research of the improved PQ algorithm be compared against the algorithm existing.

  8. AN EFFICIENT PACKET SCHEDULING ALGORITHM FOR 4G IP-BASED MOBILE NETWORKS

    Directory of Open Access Journals (Sweden)

    Hussaim Mohammed

    2010-09-01

    Full Text Available Next generation mobile networks are expected to provide seamless personal mobile communication and quality of service (QoS. Lossless handoff is a key issue for providing the QoS. This paper presents 4G node B Architecture, a two-layer downlink queuing model and proposes a scheduling mechanism for providing lossless handoff and QoS in mobile networks, which exploit IP as a transport technology for transferring datagrams between base stations and the high-speed downlink packet access (HSDPA at the radio layer. In order to reduce handoff packet dropping rate at the radio layer and packet forwarding rate at the IP layer and to provide high system performance, new scheduling algorithms are performed at both IP and radio layer, which exploit handoff priority scheduling principles and take into account buffer occupancy and channel conditions. Performance results obtained by computer simulation show that, by exploiting the downlink queuing model and scheduling algorithms, the system is able to provide low handoff packet dropping rate, low packet forwarding rate, and high downlink throughput.

  9. An Opportunistic Forwarding Scheme Exploiting both Long Progress and Adaptive Rate in Wireless Networks

    Science.gov (United States)

    Tang, Suhua; Shirazi, Mehdad N.; Shagdar, Oyunchimeg; Suzuki, Ryutaro; Obana, Sadao

    In Mobile Ad hoc Networks (MANET) geographic routing is characterized by local forwarding decision. Links with a long progress are preferred under the greedy forwarding rule. However in a real system long links tend to have a high packet loss rate due to multipath fading. A sub-optimal solution may separately exploit path diversity or rate adaptation. In this paper we study channel efficiency of multi-hop forwarding and try to jointly optimize rate adaptation and forwarder selection in geographic routing by the tradeoff between progress and instantaneous rate. We define a new metric-Bit Transfer Speed (BTS)-as the ratio of the progress made towards the destination to the equivalent time taken to transfer a payload bit. This metric takes overhead, rate and progress into account. Then we propose a packet forwarding scheme that Opportunistically exploits both long Progress and Adaptive Rate (OPAR) by a cross-layer design of routing and MAC. In OPAR each node selects for a packet the forwarder with the highest BTS. The forwarder changes as local topology (progress), packet size (overhead ratio) or channel state (data rate) varies. Simulation results show that compared with the normalized advance (NADV) [7] scheme and contention-based forwarding (CBF) [17] scheme, OPAR has lower packet loss and can effectively reduce channel occupation time by over 30% in the scenario with moderate mobility speeds.

  10. Packet Queueing Delay in Resilient Packet Ring Network Nodes

    Institute of Scientific and Technical Information of China (English)

    史国炜; 方红波; 曲建岭; 曾烈光

    2004-01-01

    The packet queueing delay is one of the most important performance measures of a data network and is also a significant factor to be considered in the scheduling buffer design for a network node.This paper presents a traffic queueing model for resilient packet ring (RPR) networks and a method for quantitatively analyzing queueing delays in RPR nodes.The method was used to calculate the average queueing delays of different priority traffic for different transit queue modes.The simulations show that,in the transmit direction,lower priority traffic is delayed more than higher priority traffic,and that Class-A traffic is delayed more in a single-queue ring than in a dual-queue ring.In the transit direction,the secondary transit buffer in the dual-queue ring contributes more to the traffic delay than the primary transit buffer in the single-queue ring,which in turn causes more delay than the primary transit buffer in the dual-queue ring.

  11. Avoiding Loops and Packet Losses in Internet Service Protocol Networks

    Directory of Open Access Journals (Sweden)

    B. Priyanka

    2014-03-01

    Full Text Available Abstract - Even in well managed Large ISP networks, failures of links and routers are common. Due to these failures the routers update their routing tables. Transient loops can occur in the networks when the routers adapt their forwarding tables. In this paper, a new approach is proposed that lets the network converge to its optimal state without loops and the related packet lossless. The mechanism (OUTFC-Ordered Updating Technique with Fast Convergence is based on an ordering of the updates of the forwarding tables of the routers and fast convergence. Typically we have chosen a Network consisting of routers and Link costs for simulation. Link failures are simulated. Avoiding transient loops in each case is demonstrated, by constructing a Reverse Shortest Path Tree (RSPT.

  12. A Novel Queuing Method for DiffServ Traffic over Resilient Packet Ring Networks

    Directory of Open Access Journals (Sweden)

    Hadi Khosravi

    2008-09-01

    Full Text Available Resilient Packet Ring (RPR is a new kind of metropolitan area network which technically provides complete flexibility in defining service classes that can be sold to the end user. On the other side, the IETF Diffserv group has created specific definitions for class based services over IP networks. Hereby, we are going to propose a more effective queuing for RPR which considers the mapping between DiffServ and RPR QOS provisioning mechanisms. This novel method is used to support the requested quality for IP over RPR delivery. Only the standard PHBs have been considered for such a mapping consisting EF (expedited forwarding, AF (assured forwarding, and default PHB. The EF class is preferred to be transmitted via class A, while AF class is more distinctive. AF includes four different flows each including up to three drop precedence. To improve the quality for AF flows, we have proposed a multi-level queuing method considering different levels of drop precedence. The default PHB is also preferred to be mapped as class C traffic. Our proposed method has been investigated using some simulations over NS2. The simulation results have shown superior performance in terms of loss and delay parameters.

  13. Grooming. Instructor's Packet. Learning Activity Package.

    Science.gov (United States)

    Stark, Pamela

    This instructor's packet accompanies the learning activity package (LAP) on grooming. Contents included in the packet are a time sheet, suggested uses for the LAP, an instruction sheet, final LAP reviews, a final LAP review answer key, suggested activities, an additional resources list, and student completion cards to issue to students as an…

  14. Effective Packet-level FEC Software Coding

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper introduces an effective software-based FEC redundant packets generating algorithm. The algorithm is based on Reed-Solomon coding over Galois Field. By operating on words of packets and performing polynomial multiplication via lookup tables, software coding efficiency is achieved to satisfy the needs of most of computer network applications. The approach to generate lookup tables is detailed.

  15. Oral Hygiene. Instructor's Packet. Learning Activity Package.

    Science.gov (United States)

    Hime, Kirsten

    This instructor's packet accompanies the learning activity package (LAP) on oral hygiene. Contents included in the packet are a time sheet, suggested uses for the LAP, an instruction sheet, final LAP reviews, a final LAP review answer key, suggested activities, additional resources (student handouts), student performance checklists for both…

  16. Method and Apparatus for Processing UDP Data Packets

    Science.gov (United States)

    Murphy, Brandon M. (Inventor)

    2017-01-01

    A method and apparatus for processing a plurality of data packets. A data packet is received. A determination is made as to whether a portion of the data packet follows a selected digital recorder standard protocol based on a header of the data packet. Raw data in the data packet is converted into human-readable information in response to a determination that the portion of the data packet follows the selected digital recorder standard protocol.

  17. Influences of clock resolution of bandwidth measurement on packet pair algorithm

    Institute of Scientific and Technical Information of China (English)

    Wu Weiguo; Zhang Wenjie; Qian Depei; Liu Yi

    2007-01-01

    Influences of the clock resolution of bandwidth estimator on the accuracy and stability of the packet pair algorithm was analyzed. A mathematic model has been established to reveal the relationship between the result deviation coefficient and the packet size, clock resolution and real bandwidth(value)of the measured route. A bandwidth self-adapting packet pair algorithm was presented based on the mathematic model to reduce the estimation error resulting from the clock resolution and to improve the accuracy and stability of measurement by adjusting the deviation coefficient. Experimental results have verified the validity and stability of the algorithm.

  18. Fast Forwarding with Network Processors

    OpenAIRE

    Lefèvre, Laurent; Lemoine, E.; Pham, C; Tourancheau, B.

    2003-01-01

    Forwarding is a mechanism found in many network operations. Although a regular workstation is able to perform forwarding operations it still suffers from poor performances when compared to dedicated hardware machines. In this paper we study the possibility of using Network Processors (NPs) to improve the capability of regular workstations to forward data. We present a simple model and an experimental study demonstrating that even though NPs are less powerful than Host Processors (HPs) they ca...

  19. Content-Adaptive Packetization and Streaming of Wavelet Video over IP Networks

    Directory of Open Access Journals (Sweden)

    Chien-Peng Ho

    2007-03-01

    Full Text Available This paper presents a framework of content-adaptive packetization scheme for streaming of 3D wavelet-based video content over lossy IP networks. The tradeoff between rate and distortion is controlled by jointly adapting scalable source coding rate and level of forward error correction (FEC protection. A content dependent packetization mechanism with data-interleaving and Reed-Solomon protection for wavelet-based video codecs is proposed to provide unequal error protection. This paper also tries to answer an important question for scalable video streaming systems: given extra bandwidth, should one increase the level of channel protection for the most important packets, or transmit more scalable source data? Experimental results show that the proposed framework achieves good balance between quality of the received video and level of error protection under bandwidth-varying lossy IP networks.

  20. Enhanced cooperative packet retransmission employing joint cooperative diversity and symbol mapping diversity

    Institute of Scientific and Technical Information of China (English)

    Wei JI; Bao-yu ZHENG

    2008-01-01

    A joint cooperation diversity and symbol mapping diversity (SMD) strategy is proposed for cooperative packet retransmission system with high-order modulation such as 16QAM.Substantial SER/BER (symbol error rate/bit error rate) gains result from multiple packet transmissions over independent paths and distinct bit-to-symbol mappings for each packet transmission.The SER/BER performance of relay assisted retransmission system is analyzed.Simulation results show that the joint-diversity strategy can provide more BER gains than other relaying strategies (i.e.,decode-and-forward and constellation rearrangement relaying strategies) when no relay makes a decision error;but if some relays make decision errors,the joint-diversity strategy outperforms other relaying strategies only when the relays are closer to the source than to the destination.

  1. Forward Intensity-Modulated Radiotherapy Planning in Breast Cancer to Improve Dose Homogeneity: Feasibility of Class Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Peulen, Heike, E-mail: h.peulen@nki.nl [Department of Radiation Oncology, MAASTRO Clinic, Maastricht (Netherlands); Hanbeukers, Bianca; Boersma, Liesbeth; Baardwijk, Angela van; Ende, Piet van den; Houben, Ruud; Jager, Jos; Murrer, Lars; Borger, Jacques [Department of Radiation Oncology, MAASTRO Clinic, Maastricht (Netherlands)

    2012-01-01

    Purpose: To explore forward planning methods for breast cancer treatment to obtain homogeneous dose distributions (using International Commission on Radiation Units and Measurements criteria) within normal tissue constraints and to determine the feasibility of class solutions. Methods and Materials: Treatment plans were optimized in a stepwise procedure for 60 patients referred for postlumpectomy irradiation using strict dose constraints: planning target volume (PTV){sub 95%} of >99%; V{sub 107%} of <1.8 cc; heart V{sub 5Gy} of <10% and V{sub 10Gy} of <5%; and mean lung dose of <7 Gy. Treatment planning started with classic tangential beams. Optimization was done by adding a maximum of four segments before adding beams, in a second step. A breath-hold technique was used for heart sparing if necessary. Results: Dose constraints were met for all 60 patients. The classic tangential beam setup was not sufficient for any of the patients; in one-third of patients, additional segments were required (<3), and in two-thirds of patients, additional beams (<2) were required. Logistic regression analyses revealed central breast diameter (CD) and central lung distance as independent predictors for transition from additional segments to additional beams, with a CD cut-off point at 23.6 cm. Conclusions: Treatment plans fulfilling strict dose homogeneity criteria and normal tissue constraints could be obtained for all patients by stepwise dose intensity modification using limited numbers of segments and additional beams. In patients with a CD of >23.6 cm, additional beams were always required.

  2. A Novel Idea to Improve Cardiac Output of Mechanical Circulatory Support Devices by Optimizing Kinetic Energy Transfer Available in Forward Moving Aortic Blood Flow.

    Science.gov (United States)

    Qureshi, Muhammad B; Glower, Jacob; Ewert, Daniel L; Koenig, Steven C

    2017-06-01

    Mechanical circulatory support devices (MCSDs) have gained widespread clinical acceptance as an effective heart failure (HF) therapy. The concept of harnessing the kinetic energy (KE) available in the forward aortic flow (AOF) is proposed as a novel control strategy to further increase the cardiac output (CO) provided by MCSDs. A complete mathematical development of the proposed theory and its application to an example MCSDs (two-segment extra-aortic cuff) are presented. To achieve improved device performance and physiologic benefit, the example MCSD timing is regulated to maximize the forward AOF KE and minimize retrograde flow. The proof-of-concept was tested to provide support with and without KE control in a computational HF model over a wide range of HF test conditions. The simulation predicted increased stroke volume (SV) by 20% (9 mL), CO by 23% (0.50 L/min), left ventricle ejection fraction (LVEF) by 23%, and diastolic coronary artery flow (CAF) by 55% (3 mL) in severe HF at a heart rate (HR) of 60 beats per minute (BPM) during counterpulsation (CP) support with KE control. The proposed KE control concept may improve performance of other MCSDs to further enhance their potential clinical benefits, which warrants further investigation. The next step is to investigate various assist technologies and determine where this concept is best applied. Then bench-test the combination of kinetic energy optimization and its associated technology choice and finally test the combination in animals.

  3. Packet Guide to Routing and Switching

    CERN Document Server

    Hartpence, Bruce

    2011-01-01

    Go beyond layer 2 broadcast domains with this in-depth tour of advanced link and internetwork layer protocols, and learn how they enable you to expand to larger topologies. An ideal follow-up to Packet Guide to Core Network Protocols, this concise guide dissects several of these protocols to explain their structure and operation. This isn't a book on packet theory. Author Bruce Hartpence built topologies in a lab as he wrote this guide, and each chapter includes several packet captures. You'll learn about protocol classification, static vs. dynamic topologies, and reasons for installing a pa

  4. An embedded packet train and adaptive FEC scheme for effective video adaptation over wireless broadband networks

    Institute of Scientific and Technical Information of China (English)

    HUANG Chih-wei; HWANG Jenq-neng

    2006-01-01

    With the rapid growth of wireless broadband technologies, such as WLAN and WiMAX, quality streaming video contents are available through portable devices anytime, anywhere. The layered multicast system using scalable video codecs has been proposed as an efficient architecture for video dissemination taking account of user and link diversities. However, in the wired/wireless combined best-effort based heterogeneous IP networks which provide more fluctuation in available bandwidth and end-to-end delay, the performance of streaming systems has been greatly degraded due to frequent packet loss, resulting from either wired congestion or wireless fading/shadowing. In this paper, we present a real-time embedded packet train probing scheme for estimating end-to-end available bandwidth so as to accomplish effective congestion and error control. This is facilitated by effective classification of packet loss sources, delay trend detection algorithm and flexible transmission rate of packets. Under the proper wireless channel modelling and estimation, our layered structure can allow appropriate subscription of video layers and adaptively insert necessary amount of forward error correction (FEC) packets so as to achieve QoS optimized system for scalable video multicasting.

  5. Sparsely-Packetized Predictive Control by Orthogonal Matching Pursuit

    DEFF Research Database (Denmark)

    Nagahara, Masaaki; Quevedo, Daniel; Østergaard, Jan

    2012-01-01

    We study packetized predictive control, known to be robust against packet dropouts in networked systems. To obtain sparse packets for rate-limited networks, we design control packets via an ℓ0 optimization, which can be eectively solved by orthogonal matching pursuit. Our formulation ensures asym...

  6. Sparse Packetized Predictive Control for Networked Control over Erasure Channels

    DEFF Research Database (Denmark)

    Nagahara, Masaaki; Quevedo, Daniel E.; Østergaard, Jan

    2014-01-01

    We study feedback control over erasure channels with packet-dropouts. To achieve robustness with respect to packet-dropouts, the controller transmits data packets containing plant input predictions, which minimize a finite horizon cost function. To reduce the data size of packets, we propose to a...

  7. Downlink Transmission of Short Packets: Framing and Control Information Revisited

    DEFF Research Database (Denmark)

    Trillingsgaard, Kasper Fløe; Popovski, Petar

    2017-01-01

    Cellular wireless systems rely on frame-based transmissions. The frame design is conventionally based on heuristics, consisting of a frame header and a data part. The frame header contains control information that provides pointers to the messages within the data part. In this paper, we revisit...... the principles of frame design and show the impact of the new design in scenarios that feature short data packets, which are central to various 5G and Internet of Things applications. We~treat framing for downlink transmission in an AWGN broadcast channel with $K$ users, where the sizes of the messages...... to the users are random variables. Using approximations from finite blocklength information theory, we establish a framework in which a message to a given user is not necessarily encoded as a single packet, but may be grouped with messages to other users and benefit from the improved efficiency of longer codes...

  8. Performance optimization for multicast packet authentication

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In secure multicast, one of the challenging problems is the authentication of multicast packets. This paper presents a novel scheme to address this problem, which combines ideas in both the hash tree schemes and the hash chain schemes. In this scheme, a group of packets is partitioned into equal-sized subgroups. Then a Merkle hash tree is built for each subgroup of packets, and the hash value of every root is appended to preceding packets to form hash chains. Its performance is analyzed and simulated using Biased Coin Toss loss model and 2-state Markov Chain loss model, respectively. Compared with the original hash chain schemes, results show that this scheme is much more efficient in term of communication overhead.

  9. Fair Scheduling in Networks Through Packet Election

    CERN Document Server

    Jagabathula, Srikanth

    2008-01-01

    We consider the problem of designing a fair scheduling algorithm for discrete-time constrained queuing networks. Each queue has dedicated exogenous packet arrivals. There are constraints on which queues can be served simultaneously. This model effectively describes important special instances like network switches, interference in wireless networks, bandwidth sharing for congestion control and traffic scheduling in road roundabouts. Fair scheduling is required because it provides isolation to different traffic flows; isolation makes the system more robust and enables providing quality of service. Existing work on fairness for constrained networks concentrates on flow based fairness. As a main result, we describe a notion of packet based fairness by establishing an analogy with the ranked election problem: packets are voters, schedules are candidates and each packet ranks the schedules based on its priorities. We then obtain a scheduling algorithm that achieves the described notion of fairness by drawing upon ...

  10. Multiwavelet Packets and Frame Packets of $L^2(\\mathbb{R}^d)$

    Indian Academy of Sciences (India)

    Biswaranjan Behera

    2001-11-01

    The orthonormal basis generated by a wavelet of $L^2(\\mathbb{R})$ has poor frequency localization. To overcome this disadvantage Coifman, Meyer, and Wickerhauser constructed wavelet packets. We extend this concept to the higher dimensions where we consider arbitrary dilation matrices. The resulting basis of $L^2(\\mathbb{R}^d)$ is called the multiwavelet packet basis. The concept of wavelet frame packet is also generalized to this setting. Further, we show how to construct various orthonormal bases of $L^2(\\mathbb{R}^d)$ from the multiwavelet packets.

  11. WBWTP+: A Packet Scheduling Algorithm for Achieving Proportional Delay Differentiation in IP Networks

    Directory of Open Access Journals (Sweden)

    MELO JR., A.

    2013-06-01

    Full Text Available The Proportional Differentiation Model (PDM is currently one of the main service proposals for the Next Generation Internet. This paper presents a new packet scheduling algorithm for implementing the PDM model using measurement windows and a mechanism of dynamic adjustment of packet delay estimation. Window Based Waiting-Time Priority Plus (WBWTP+, the proposed algorithm, is an evolution of the WBWTP algorithm that adjusts dynamically the relative weights of transmitted and waiting for transmission packets according to the current state of the system. The WBWTP+ delay estimator makes possible to accelerate or to delay the transmission of backlogged packets. Simulations performed to asses the performance of the WBWTP+ show that it presents significant improvement in the attendance of the PDM objective in relation to WBWTP in most scenarios, excepted when the link utilization rate is 100%. Even in that case the performance of WBWTP+ was better than that of WTP and PAD algorithms.

  12. Packet Reordering Procedure with Ubiquous Communication Systems

    Directory of Open Access Journals (Sweden)

    Giridhar Akula

    2012-11-01

    Full Text Available Satellite links are going to play a vital role in the deployment of ubiquous broad band systems. Non- Geostationary (NGEO satellite communication systems are more advantageous than terrestrial satellites. This paper presents an exchange of information on cooperation status among neiboring satellites. The new explicit load balancing scheme is used to avoid congestion and packet drops at the satellite. A TTL based algorithm is used for packet reordering.

  13. Asymmetric Best Effort Service for Packet Networks

    OpenAIRE

    Le Boudec, Jean-Yves; Hamdi, M; Blazevic, L.; P. Thiran

    1998-01-01

    We propose a system and method for providing a ``throughput versus delay'' differentiated service for IP packets. We distinguish two types of traffic: type A and type B. It is expected that type A traffic receives less throughput per flow than type B. On the other hand, type A packets experience considerably smaller delay. The method is intended to be implemented in Internet routers. No bandwidth or buffer reservation is assumed in this system. The service remains a Best Effort service, thus ...

  14. Asymmetric Best Effort Service for Packet Networks

    OpenAIRE

    Blazevic, Ljubica; Le Boudec, Jean-Yves; Thiran, Patrick

    1998-01-01

    We propose a system and method for providing a ``throughput versus delay`` differentiated service for IP packets. We distinguish two types of traffic: type A and type B. It is expected that type A traffic receives less throughput per flow than type B. On the other hand, type A packets experience considerably smaller delay. The method is intended to be implemented in Internet routers. No bandwidth or buffer reservation is assumed in this system. The service remains a Best Effort service, thus...

  15. Protocol Software for a Packet Voice Terminal

    Science.gov (United States)

    1983-11-16

    III satellite. The PVTs with their attached telephone instrument serve as the interface with the voice user. The PVTs prepare speech for transmission...through a packet network by digitizing the speech, preparing speech data packets, and sending speech data messages. The PVT handles the speech coming...TOTALKin. Thes Foori alControle wilno trani speech message s unlTreessin ithas note rcenie s speehdfr ao sufficentpo toefl erAcofitt cdng atei t pfres

  16. Detecting the BAO using Discrete Wavelet Packets

    Science.gov (United States)

    Garcia, Noel Anthony; Wu, Yunyun; Kadowaki, Kevin; Pando, Jesus

    2017-01-01

    We use wavelet packets to investigate the clustering of matter on galactic scales in search of the Baryon Acoustic Oscillations. We do so in two ways. We develop a wavelet packet approach to measure the power spectrum and apply this method to the CMASS galaxy catalogue from the Sloan Digital Sky Survey (SDSS). We compare the resulting power spectrum to published BOSS results by measuring a parameter β that compares our wavelet detected oscillations to the results from the SDSS collaboration. We find that β=1 indicating that our wavelet packet methods are detecting the BAO at a similar level as traditional Fourier techniques. We then use wavelet packets to decompose, denoise, and then reconstruct the galaxy density field. Using this denoised field, we compute the standard two-point correlation function. We are able to successfully detect the BAO at r ≈ 105 h-1 Mpc in line with previous SDSS results. We conclude that wavelet packets do reproduce the results of the key clustering statistics computed by other means. The wavelet packets show distinct advantages in suppressing high frequency noise and in keeping information localized.

  17. Effect of Inter Packet Delay in performance analysis of coexistence heterogeneous Wireless Packet Networks

    CERN Document Server

    Tamilselvan, G M

    2010-01-01

    As the explosive growth of the ISM band usage continues, there are many scenarios where different systems operate in the same place at the same time. One of growing concerns is the coexistence of heterogeneous wireless network systems. For the successful deployment of mission-critical systems such as wireless sensor networks, it is required to provide a solution for the coexistence. In this paper, we propose a new scheme using inter packet delay for the coexistence of IEEE 802.15.4 LRWPAN and IEEE 802.11b WLAN. To evaluate the effectiveness of the proposed scheme, measurement and simulation study are conducted using Qualnet 4.5 simulation software. The simulation results show that the proposed scheme is effective in performance improvement for coexistence network of IEEE 802.15.4 for various topologies.

  18. New hybrid frequency reuse method for packet loss minimization in LTE network.

    Science.gov (United States)

    Ali, Nora A; El-Dakroury, Mohamed A; El-Soudani, Magdi; ElSayed, Hany M; Daoud, Ramez M; Amer, Hassanein H

    2015-11-01

    This paper investigates the problem of inter-cell interference (ICI) in Long Term Evolution (LTE) mobile systems, which is one of the main problems that causes loss of packets between the base station and the mobile station. Recently, different frequency reuse methods, such as soft and fractional frequency reuse, have been introduced in order to mitigate this type of interference. In this paper, minimizing the packet loss between the base station and the mobile station is the main concern. Soft Frequency Reuse (SFR), which is the most popular frequency reuse method, is examined and the amount of packet loss is measured. In order to reduce packet loss, a new hybrid frequency reuse method is implemented. In this method, each cell occupies the same bandwidth of the SFR, but the total system bandwidth is greater than in SFR. This will provide the new method with a lot of new sub-carriers from the neighboring cells to reduce the ICI which represents a big problem in many applications and causes a lot of packets loss. It is found that the new hybrid frequency reuse method has noticeable improvement in the amount of packet loss compared to SFR method in the different frequency bands. Traffic congestion management in Intelligent Transportation system (ITS) is one of the important applications that is affected by the packet loss due to the large amount of traffic that is exchanged between the base station and the mobile node. Therefore, it is used as a studied application for the proposed frequency reuse method and the improvement in the amount of packet loss reached 49.4% in some frequency bands using the new hybrid frequency reuse method.

  19. Maximizing Throughput of SW ARQ with Network Coding through Forward Error Correction

    Directory of Open Access Journals (Sweden)

    Farouq M. Aliyu

    2015-06-01

    Full Text Available Over the years, several techniques for improving throughput of wireless communication have been developed in order to cater for the ever increasing demand of high speed network service. However, these techniques can only give little improvement in performance because packets have to be delivered as is. As such researchers have begun thinking outside the box by proposing ideas that require relay nodes to temper packets’ contents in order to improve the throughput of a network. One of the state of the art techniques in this field is called Network Coding (NC. NC is a state of the art technique that allows relay nodes linearly combine two or more packets in a way they can be recovered upon reaching their destination. However, increasing packet size increases possibility of error affecting it. In this paper, the authors decide to investigate whether adding data recovery technique can improve the performance of a network that uses network coding, if it can, by how much can it? Is it worth the trouble? In order to answer these questions, the authors carried out a quantitative analysis of throughput in a Stop-and-Wait Automatic Repeat reQuest (SW-ARQ data transmission system with Network Coding (NC and Forward Error Correction (FEC. Vandermonde matrix is chosen as the coding technique for this research because it has both NC and data recovery characteristics. Python programming language is used to develop three Discrete Event Simulations: SW-ARQ without any NC, SW-ARQ with NC and SW-ARQ with NC and FEC. The obtained results show that SW-ARQ with NC and FEC is superior to traditional SW-ARQ in terms of throughput, especially in channels with high error rates.

  20. Architecture of fast IP forwarding engine in gigabit ethernet system

    Science.gov (United States)

    Do, Han C.; Lee, Hyeong H.; Cha, Kyoon Hyun

    1999-11-01

    In recent years, Internet traffic has been increased rapidly as a result of the Internet which accommodates multimedia traffic such as IP telephony and video conference. Gigabit routing technology is one possible approach to handle such internet traffic. This paper presents an efficient IP forwarding architecture adequate for Gigabit Ethernet switching system. The presented IP forwarding architecture is based upon distributed and pipelined process, which can effectively facilitate searching, editing, traffic classification, forwarding, and traffic management in parallel. Additionally, it can also process packets at full wire-speed in the ASIC level.

  1. 面向智能变电站二次设备的网络报文管控技术%Network Packet Control Technology for Secondary Equipments in Smart Substation

    Institute of Scientific and Technical Information of China (English)

    周华良; 郑玉平; 姚吉文; 姜雷; 谢黎; 王凯

    2015-01-01

    随着智能变电站以太网应用往混合组网、多网共口的方向发展,网络的安全稳定性对于智能变电站设备可靠运行至关重要。文中深入研究了电力二次设备在多种报文共网共口条件下接收与发送的优化处理机制。在接收方向上针对变电站网络风暴条件下的报文特点,提出多级过滤、分组流量控制的方法实现网络风暴抑制,保证了正常报文的接收与处理;在发送方向上提出以优先级划分为前提的优化调度发送策略,保证了报文发送的实时性并充分利用了网络带宽。同时,基于纯硬件片上系统实现了上述机制的实际应用与测试,有效提升了智能变电站二次设备网络通信的稳定性与可靠性。%With the application of the Ethernet tending to be hybridized in networking in smart substation and packets in multiple protocols existing in the same network,the security and stability of the network has become the crucial point for the reliability of smart substation equipments.The optimization of network packets in two directions of sending and receiving is studied.That is,according to the characteristics of packets in smart substation network,packet flow control in groups and the multi-stage filtering in the receiving direction is put forward to suppress network packet storms and processing normal packet effectively;while in the sending direction,an optimization scheduling strategy based on packet priority classification is used to get the real-time performance and make full use of network bandwidth.Meanwhile all the strategies in this paper are implemented on the SoC hardware system,the test results showing that the stability and reliability of network communication in smart substation equipments is effectively improved.

  2. Inclusion of quantum fluctuations in wave packet dynamics

    CERN Document Server

    Ohnishi, A

    1996-01-01

    We discuss a method by which quantum fluctuations can be included in microscopic transport models based on wave packets that are not energy eigenstates. By including the next-to-leading order term in the cumulant expansion of the statistical weight, which corresponds to the wave packets having Poisson energy distributions, we obtain a much improved global description of the quantum statistical properties of the many-body system. In the case of atomic nuclei, exemplified by 12C and 40Ca, the standard liquid-drop results are reproduced at low temperatures and a phase transformation to a fragment gas occurs as the temperature is raised. The treatment can be extended to dynamical scenarios by means of a Langevin force emulating the transitions between the wave packets. The general form of the associated transport coefficients is derived and it is shown that the appropriate microcanonical equilibrium distribution is achieved in the course of the time evolution. Finally, invoking Fermi's golden rule, we derive spec...

  3. Packet-Scheduling Algorithm by the Ratio of Transmit Power to the Transmission Bits in 3GPP LTE Downlink

    Directory of Open Access Journals (Sweden)

    Gil Gye-Tae

    2010-01-01

    Full Text Available Packet scheduler plays the central role in determining the overall performance of the 3GPP long-term evolution (LTE based on packet-switching operation. In this paper, a novel minimum transmit power-based (MP packet-scheduling algorithm is proposed that can achieve power-efficient transmission to the UEs while providing both system throughput gain and fairness improvement. The proposed algorithm is based on a new scheduling metric focusing on the ratio of the transmit power per bit and allocates the physical resource block (PRB to the UE that requires the least ratio of the transmit power per bit. Through computer simulation, the performance of the proposed MP packet-scheduling algorithm is compared with the conventional packet-scheduling algorithms by two primary criteria: fairness and throughput. The simulation results show that the proposed algorithm outperforms the conventional algorithms in terms of the fairness and throughput.

  4. Feasibility of Optical Packet Switched WDM Networks without Packet Synchronisation Under Bursty Traffic Conditions

    DEFF Research Database (Denmark)

    Fjelde, Tina; Hansen, Peter Bukhave; Kloch, Allan;

    1999-01-01

    We show that complex packet synchronisation may be avoided in optical packetswitched networks. Detailed traffic analysis demonstrates that packet lossratios of 1e-10 are feasible under bursty traffic conditions for a highcapacity network consisting of asynchronously operated add-drop switch...

  5. Hierarchical trie packet classification algorithm based on expectation-maximization clustering

    Science.gov (United States)

    Bi, Xia-an; Zhao, Junxia

    2017-01-01

    With the development of computer network bandwidth, packet classification algorithms which are able to deal with large-scale rule sets are in urgent need. Among the existing algorithms, researches on packet classification algorithms based on hierarchical trie have become an important packet classification research branch because of their widely practical use. Although hierarchical trie is beneficial to save large storage space, it has several shortcomings such as the existence of backtracking and empty nodes. This paper proposes a new packet classification algorithm, Hierarchical Trie Algorithm Based on Expectation-Maximization Clustering (HTEMC). Firstly, this paper uses the formalization method to deal with the packet classification problem by means of mapping the rules and data packets into a two-dimensional space. Secondly, this paper uses expectation-maximization algorithm to cluster the rules based on their aggregate characteristics, and thereby diversified clusters are formed. Thirdly, this paper proposes a hierarchical trie based on the results of expectation-maximization clustering. Finally, this paper respectively conducts simulation experiments and real-environment experiments to compare the performances of our algorithm with other typical algorithms, and analyzes the results of the experiments. The hierarchical trie structure in our algorithm not only adopts trie path compression to eliminate backtracking, but also solves the problem of low efficiency of trie updates, which greatly improves the performance of the algorithm. PMID:28704476

  6. Satellite link augmentation of ground based packet switched data networks

    Science.gov (United States)

    Farrell, J. B.; McLane, P. J.; Campbell, L. L.

    Use of satellite link augmentation to improve the performance of a packet switched data network is considered. Particular attention is paid to the analysis of two queues in series from the standpoint of time delay. A finite state machine model is used to aid the analysis. The results from the analysis are then used in a flow deviation routing algorithm. This algorithm is applied to study the performance improvement when satellite links are used to augment the Canadian DATAPAC network. The results are backed up by extensive simulations on a digital computer.

  7. An Improved PRoPHET Routing Protocol in Delay Tolerant Network

    Directory of Open Access Journals (Sweden)

    Seung Deok Han

    2015-01-01

    Full Text Available In delay tolerant network (DTN, an end-to-end path is not guaranteed and packets are delivered from a source node to a destination node via store-carry-forward based routing. In DTN, a source node or an intermediate node stores packets in buffer and carries them while it moves around. These packets are forwarded to other nodes based on predefined criteria and finally are delivered to a destination node via multiple hops. In this paper, we improve the dissemination speed of PRoPHET (probability routing protocol using history of encounters and transitivity protocol by employing epidemic protocol for disseminating message m, if forwarding counter and hop counter values are smaller than or equal to the threshold values. The performance of the proposed protocol was analyzed from the aspect of delivery probability, average delay, and overhead ratio. Numerical results show that the proposed protocol can improve the delivery probability, average delay, and overhead ratio of PRoPHET protocol by appropriately selecting the threshold forwarding counter and threshold hop counter values.

  8. Fictitious time wave packet dynamics: I. Nondispersive wave packets in the quantum Coulomb problem

    CERN Document Server

    Fabčič, T; Wunner, G

    2009-01-01

    Nondispersive wave packets in a fictitious time variable are calculated analytically for the field-free hydrogen atom. As is well known by means of the Kustaanheimo-Stiefel transformation the Coulomb problem can be converted into that of a four-dimensional harmonic oscillator, subject to a constraint. This regularization makes use of a fictitious time variable, but arbitrary Gaussian wave packets in that time variable in general violate that constraint. The set of "restricted Gaussian wave packets" consistent with the constraint is constructed and shown to provide a complete basis for the expansion of states in the original three-dimensional coordinate space. Using that expansion arbitrary localized Gaussian wave packets of the hydrogen atom can be propagated analytically, and exhibit a nondispersive periodic behavior as functions of the fictitious time. Restricted wave packets with and without well defined angular momentum quantum n umbers are constructed. They will be used as trial functions in time-depende...

  9. Survival of the Fittest: An Active Queue Management Technique for Noisy Packet Flows

    Directory of Open Access Journals (Sweden)

    Shirish S. Karande

    2007-01-01

    Full Text Available We present a novel active queue management (AQM technique to demonstrate the efficacy of practically harnessing the predictive utility of SSR indications for improved video communication. We consider a network within which corrupted packets are relayed over multiple hops, but a certain percentage of packets needs to be dropped at an intermediate node due to congestion. We propose an AQM technique, survival of the fittest (SOTF, to be employed at the relay node, within which we use packet state information, available from SSR indications and checksums, to drop packets with the highest corruption levels. On the basis of actual 802.11b measurements we show that such a side information (SI aware processing within the network can provide significant performance benefits over an SI-unaware scheme, random queue management (RQM, which is forced to randomly discard packets. With trace-based simulations, we show the utility of the proposed AQM technique in improving the error recovery performance of cross-layer FEC schemes. Finally, with the help of H.264-based video simulations these improvements are shown to translate into a significant improvement in video quality.

  10. Fair packet scheduling in Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal

    2014-02-01

    In this paper we study the interactions of TCP and IEEE 802.11 MAC in Wireless Mesh Networks (WMNs). We use a Markov chain to capture the behavior of TCP sessions, particularly the impact on network throughput due to the effect of queue utilization and packet relaying. A closed form solution is derived to numerically determine the throughput. Based on the developed model, we propose a distributed MAC protocol called Timestamp-ordered MAC (TMAC), aiming to alleviate the unfairness problem in WMNs. TMAC extends CSMA/CA by scheduling data packets based on their age. Prior to transmitting a data packet, a transmitter broadcasts a request control message appended with a timestamp to a selected list of neighbors. It can proceed with the transmission only if it receives a sufficient number of grant control messages from these neighbors. A grant message indicates that the associated data packet has the lowest timestamp of all the packets pending transmission at the local transmit queue. We demonstrate that a loose ordering of timestamps among neighboring nodes is sufficient for enforcing local fairness, subsequently leading to flow rate fairness in a multi-hop WMN. We show that TMAC can be implemented using the control frames in IEEE 802.11, and thus can be easily integrated in existing 802.11-based WMNs. Our simulation results show that TMAC achieves excellent resource allocation fairness while maintaining over 90% of maximum link capacity across a large number of topologies.

  11. ETHERNET PACKET PROCESSOR FOR SOC APPLICATION

    Directory of Open Access Journals (Sweden)

    Raja Jitendra Nayaka

    2012-07-01

    Full Text Available As the demand for Internet expands significantly in numbers of users, servers, IP addresses, switches and routers, the IP based network architecture must evolve and change. The design of domain specific processors that require high performance, low power and high degree of programmability is the bottleneck in many processor based applications. This paper describes the design of ethernet packet processor for system-on-chip (SoC which performs all core packet processing functions, including segmentation and reassembly, packetization classification, route and queue management which will speedup switching/routing performance. Our design has been configured for use with multiple projects ttargeted to a commercial configurable logic device the system is designed to support 10/100/1000 links with a speed advantage. VHDL has been used to implement and simulated the required functions in FPGA.

  12. Voice communications over packet radio networks

    Science.gov (United States)

    Seah, M. M.

    1985-03-01

    The use of packet virtual circuit technique for voice communications in military radio networks was investigated. The work was concerned with various aspects of networking which include network modeling, communications techniques, traffic analysis and network control. An attempt has been made to develop a simple yet efficient time slot assignment algorithm . This was analyzed under a variety of slot depths and networks topologies using computer simulation. The Erlang' B results were used to provide more insight into the channel characteristics of the packet radio networks. The capabilities of implementing TDMA/CDMA hybrid schemes in the system were scrutinized. A method to estimate the transmission capacity of the inter-node links was found. We demonstrate its effectiveness in controlling local congestion by computer simulation. Graphical results were presented to highlight the behavior of the proposed packet radio networks. We concluded that an appropriate link weight function would provide efficient and reliable network services.

  13. Packet Filtering using IP Tables in Linux

    Directory of Open Access Journals (Sweden)

    Bhisham Sharma

    2011-07-01

    Full Text Available Firewalls are core elements in network security. However, managing firewall rules, especially for enterprise networks, has become complex and error-prone. Firewall filtering rules have to be carefully written and organized in order to correctly implement the security policy. In addition, inserting or modifying a filtering rule requires thorough analysis of the relationship between the rules in order to determine the proper order. In this paper work has been done on creating the virtual network environment using Microsoft virtual PC(SP1 and Capturing and analyzing of network packets using the most popular open source network protocol analyzer Wireshark and on the basis of analyzing the packet work has been done on writing the script to block/allow the network traffic using IPtables and after blocking traffic further capturing and analyzing of packets using Wireshark.

  14. Dynamic Packet Scheduling in Wireless Networks

    CERN Document Server

    Kesselheim, Thomas

    2012-01-01

    We consider protocols that serve communication requests arising over time in a wireless network that is subject to interference. Unlike previous approaches, we take the geometry of the network and power control into account, both allowing to increase the network's performance significantly. We introduce a stochastic and an adversarial model to bound the packet injection. Although taken as the primary motivation, this approach is not only suitable for models based on the signal-to-interference-plus-noise ratio (SINR). It also covers virtually all other common interference models, for example the multiple-access channel, the radio-network model, the protocol model, and distance-2 matching. Packet-routing networks allowing each edge or each node to transmit or receive one packet at a time can be modeled as well. Starting from algorithms for the respective scheduling problem with static transmission requests, we build distributed stable protocols. This is more involved than in previous, similar approaches because...

  15. Towards a Fair and Efficient Packet Scheduling Scheme in Inter-Flow Network Coding

    Directory of Open Access Journals (Sweden)

    Jin Wang

    2014-11-01

    Full Text Available Network coding techniques are usually applied upon network-layer protocols to improve throughput in wireless networks. In scenarios with multiple unicast sessions, fairness is also an important factor. Therefore, a network coding-aware packet-scheduling algorithm is required. A packet-scheduling algorithm determines which packet to send next from a node’s packet backlog. Existing protocols mostly employ a basic round-robin scheduling algorithm to give “equal” opportunities to different packet flows. In fact, this “equal”-opportunity scheduling is neither fair, nor efficient. This paper intends to accentuate the importance of a coding-aware scheduling scheme. With a good scheduling scheme, we can gain more control over the per-flow throughput and fairness. Specifically, we first formulate a static scheduling problem and propose an algorithm to find the optimal scheduling scheme. We then extend the technique to a dynamic setting and, later, to practical routing protocols. Results show that the algorithm is comparatively scalable, and it can improve the throughput gain when the network is not severely saturated. The fairness among flows is drastically improved as a result of this scheduling scheme.

  16. Maintaining Packet Order in Reservation-Based Shared-Memory Optical Packet Switch

    Science.gov (United States)

    Wang, Xiaoliang; Jiang, Xiaohong; Horiguchi, Susumu

    Shared-Memory Optical Packet (SMOP) switch architecture is very promising for significantly reducing the amount of required optical memory, which is typically constructed from fiber delay lines (FDLs). The current reservation-based scheduling algorithms for SMOP switches can effectively utilize the FDLs and achieve a low packet loss rate by simply reserving the departure time for each arrival packet. It is notable, however, that such a simple scheduling scheme may introduce a significant packet out of order problem. In this paper, we first identify the two main sources of packet out of order problem in the current reservation-based SMOP switches. We then show that by introducing a “last-timestamp” variable and modifying the corresponding FDLs arrangement as well as the scheduling process in the current reservation-based SMOP switches, it is possible to keep packets in-sequence while still maintaining a similar delay and packet loss performance as the previous design. Finally, we further extend our work to support the variable-length burst switching.

  17. Wavelet and wavelet packet compression of electrocardiograms.

    Science.gov (United States)

    Hilton, M L

    1997-05-01

    Wavelets and wavelet packets have recently emerged as powerful tools for signal compression. Wavelet and wavelet packet-based compression algorithms based on embedded zerotree wavelet (EZW) coding are developed for electrocardiogram (ECG) signals, and eight different wavelets are evaluated for their ability to compress Holter ECG data. Pilot data from a blind evaluation of compressed ECG's by cardiologists suggest that the clinically useful information present in original ECG signals is preserved by 8:1 compression, and in most cases 16:1 compressed ECG's are clinically useful.

  18. ON CONVERGENCE OF WAVELET PACKET EXPANSIONS

    Institute of Scientific and Technical Information of China (English)

    Morten Nielsen

    2002-01-01

    It is well known that the-Walsh-Fourier expansion of a function from the block space ([0, 1 ) ), 1 <q≤∞, converges pointwise a.e. We prove that the same result is true for the expansion of a function from in certain periodixed smooth periodic non-stationary wavelet packets bases based on the Haar filters. We also consider wavelet packets based on the Shannon filters and show that the expansion of Lp-functions, 1<p<∞, converges in norm and pointwise almost everywhere.

  19. Squeezed Wave Packets in Quantum Cosmology

    Science.gov (United States)

    Pedram, Pouria

    2010-11-01

    We use an appropriate initial condition for constructing squeezed wave packets in the context of Wheeler-DeWitt equation with complete classical description. This choice of initial condition does not alter the classical paths and only affect the quantum mechanical picture. To demonstrate the method, we consider an empty 4+1-dimensional Kaluza-Klein quantum cosmology in the presence of a negative cosmological constant. We show that these wave packets do not disperse and sharply peak on the classical trajectories in the whole configuration space. So, the probability of finding the corresponding physical quantities approaches zero everywhere except on the classical paths.

  20. Mesoporous Silica Gel-Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler.

    Science.gov (United States)

    Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y; Huo, Fengwei

    2015-11-23

    The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4-30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores.

  1. Mesoporous Silica Gel-Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler

    Science.gov (United States)

    Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y.; Huo, Fengwei

    2015-11-01

    The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4-30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores.

  2. Utility Optimal Coding for Packet Transmission over Wireless Networks - Part II: Networks of Packet Erasure Channels

    CERN Document Server

    Karumbu, Premkumar; Leith, Douglas J

    2011-01-01

    We define a class of multi--hop erasure networks that approximates a wireless multi--hop network. The network carries unicast flows for multiple users, and each information packet within a flow is required to be decoded at the flow destination within a specified delay deadline. The allocation of coding rates amongst flows/users is constrained by network capacity. We propose a proportional fair transmission scheme that maximises the sum utility of flow throughputs. This is achieved by {\\em jointly optimising the packet coding rates and the allocation of bits of coded packets across transmission slots.}

  3. To Forward The Freight Forwarding Industry

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    China's freight forwarding industry is suffering a lot as the country's foreign trade has slowed down. The dwindling overseas markets, the rising RMB exchange rates and the soaring prices of raw materials have been restraining the exports and the imports, and have thereby been depressing the freight volumes, Besides, the global leading freight forwarding companies have expanded their shares in the Chinese market. China'sfreight forwarders are losing the comparative advantages in local market and human resources,

  4. Improved laser-induced forward transfer of organic semiconductor thin films by reducing the environmental pressure and controlling the substrate-substrate gap width

    Energy Technology Data Exchange (ETDEWEB)

    Shaw-Stewart, James [Empa Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers, Duebendorf (Switzerland); Paul Scherrer Institut, Materials Group, General Energies Department, Villigen-PSI (Switzerland); Chu, Bryan; Maniglio, Ylenia; Nagel, Matthias; Nueesch, Frank [Empa Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Functional Polymers, Duebendorf (Switzerland); Lippert, Thomas; Wokaun, Alexander [Paul Scherrer Institut, Materials Group, General Energies Department, Villigen-PSI (Switzerland)

    2011-11-15

    Laser-induced forward transfer (LIFT) has been investigated for bilayer transfer material systems: silver/organic film (Alq{sub 3} or PFO). The LIFT process uses an intermediate dynamic release layer of a triazene polymer. This study focuses on the effect of introducing a controlled donor-receiver substrate gap distance and the effect of doing the transfer at reduced air pressures, whilst varying the fluence up to {proportional_to}200 mJ/cm{sup 2}. The gap between 'in-contact' substrates has been measured to be a minimum of 2-3 {mu}m. A linear variation in the gap width from 'in contact' to 40 {mu}m has been achieved by adding a spacer at one side of the substrate-substrate sandwich. At atmospheric pressure, very little transfer is achieved for Alq{sub 3}, although PFO shows some signs of successful doughnut transfer (with a large hole in the middle) in a narrow fluence range, at gaps greater than 20 {mu}m. For the transfer of Ag/PFO bilayers at atmospheric pressure, the addition of a PFO layer onto the receiver substrate improved the transfer enormously at smaller gaps and higher fluences. However, the best transfer results were obtained at reduced pressures where a 100% transfer success rate is obtained within a certain fluence window. The quality of the pixel morphology at less than 100 mbar is much higher than at atmospheric pressure, particularly when the gap width is less than 20 {mu}m. These results show the promise of LIFT for industrial deposition processes where a gap between the substrates will improve the throughput. (orig.)

  5. A Packetized SPIHT Algorithm with Overcomplete Wavelet Coefficients for Increased Robustness

    Directory of Open Access Journals (Sweden)

    Sriraja Y

    2006-01-01

    Full Text Available This paper presents a wavelet-based image encoding scheme with error resilience and error concealment suitable for transmission over networks prone to packet losses. The scheme involves partitioning the data into independent descriptions of roughly equal lengths, achieved by a combination of packetization and modifications to the wavelet tree structure without additional redundancy. With a weighted-averaging-based interpolation method, our proposed encoding scheme attains an improvement of about 0.5–1.5 dB in PSNR over other similar methods. We also investigate the use of overcomplete wavelet transform coefficients as side information for our encoding scheme to improve the error resilience when severe packet losses occur. Experiments show that we are able to achieve a high coding performance along with a good perceptual quality for the reconstructed image.

  6. Wave packet dynamics and factorization of numbers

    CERN Document Server

    Mack, H; Haug, F; Straub, F S; Freyberger, M; Schleich, W P; Mack, Holger; Bienert, Marc; Haug, Florian; Straub, Frank S.; Freyberger, Matthias; Schleich, Wolfgang P.

    2002-01-01

    We connect three phenomena of wave packet dynamics: Talbot images, revivals of a particle in a box and fractional revivals. The physical origin of these effects is deeply rooted in phase factors which are quadratic in the quantum number. We show that the characteristic structures in the time evolution of these systems allow us to factorize large integers.

  7. Relativistic suppression of wave packet spreading.

    Science.gov (United States)

    Su, Q; Smetanko, B; Grobe, R

    1998-03-30

    We investigate numerically the solution of Dirac equation and analytically the Klein-Gordon equation and discuss the relativistic motion of an electron wave packet in the presence of an intense static electric field. In contrast to the predictions of the (non-relativistic) Schroedinger theory, the spreading rate in the field's polarization direction as well as in the transverse directions is reduced.

  8. Packet models revisited: tandem and priority systems

    NARCIS (Netherlands)

    Mandjes, M.R.H.

    2004-01-01

    We examine two extensions of traditional single-node packet-scale queueing models: tandem networks and (strict) priority systems. Two generic input processes are considered: periodic and Poisson arrivals. For the two-node tandem, an exact expression is derived for the joint distribution of the total

  9. Packet models revisited: tandem and priority systems

    NARCIS (Netherlands)

    M.R.H. Mandjes

    2004-01-01

    Abstract : We examine two extensions of traditional single-node packet-scale queueing models: tandem networks and (strict) priority systems. Two generic input processes are considered: periodic and Poisson arrivals. For the two-node tandem, an exact expression is derived for the joint distribution o

  10. Humane Education Teachers' Packet (Preschool & Kindergarten).

    Science.gov (United States)

    Sammut-Tovar, Dorothy

    Designed to sensitize preschoolers and kindergartners to the responsibilities involved in caring for living things, this teacher's packet provides a variety of student worksheets and activity suggestions. Teaching plans are provided for a total of nine lessons, which can be easily integrated into other learning areas such as numbers, colors,…

  11. Satcom access in the Evolved Packet Core

    NARCIS (Netherlands)

    Cano Soveri, M.D.; Norp, A.H.J.; Popova, M.P.

    2011-01-01

    Satellite communications (Satcom) networks are increasingly integrating with terrestrial communications networks, namely Next Generation Networks (NGN). In the area of NGN the Evolved Packet Core (EPC) is a new network architecture that can support multiple access technologies. When Satcom is consid

  12. Satcom access in the evolved packet core

    NARCIS (Netherlands)

    Cano, M.D.; Norp, A.H.J.; Popova, M.P.

    2012-01-01

    Satellite communications (Satcom) networks are increasingly integrating with terrestrial communications networks, namely Next Generation Networks (NGN). In the area of NGN the Evolved Packet Core (EPC) is a new network architecture that can support multiple access technologies. When Satcom is consid

  13. Solid Waste Activity Packet for Teachers.

    Science.gov (United States)

    Illinois Univ., Urbana. Cooperative Extension Service.

    This solid waste activity packet introduces students to the solid waste problem in Illinois. Topics explore consumer practices in the market place, packaging, individual and community garbage generation, and disposal practices. The activities provide an integrated approach to incorporating solid waste management issues into subject areas. The…

  14. Multiple descriptions for packetized predictive control

    DEFF Research Database (Denmark)

    Østergaard, Jan; Quevedo, Daniel

    2016-01-01

    In this paper, we propose to use multiple descriptions (MDs) to achieve a high degree of robustness towards random packet delays and erasures in networked control systems. In particular, we consider the scenario, where a data-rate limited channel is located between the controller and the plant...

  15. Cashier/Checker Learning Activity Packets (LAPs).

    Science.gov (United States)

    Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Twenty-four learning activity packets (LAPs) are provided for six areas of instruction in a cashier/checker program. Section A, Orientation, contains an LAP on exploring the job of cashier-checker. Section B, Operations, has nine LAPs, including those on operating the cash register, issuing trading stamps, and completing the cash register balance…

  16. Peninsula Humane Society Teacher's Packet. Secondary Level.

    Science.gov (United States)

    Peninsula Humane Society, San Mateo, CA.

    Activities in this teacher's packet are designed to familiarize secondary school students with the responsibilities involved in pet ownership. Teaching plans are provided for a total of 12 lessons grouped under social studies, language arts, math, and health sciences. Activities focus on pet overpopulation, expressions of social responses in…

  17. Peninsula Humane Society Teacher's Packet. Secondary Level.

    Science.gov (United States)

    Peninsula Humane Society, San Mateo, CA.

    Activities in this teacher's packet are designed to familiarize secondary school students with the responsibilities involved in pet ownership. Teaching plans are provided for a total of 12 lessons grouped under social studies, language arts, math, and health sciences. Activities focus on pet overpopulation, expressions of social responses in…

  18. EFFICIENT PACKET DELIVERY APPROACH FOR ADHOC WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    Sharvani G S

    2011-01-01

    Full Text Available A wireless ad-hoc network is a collection of nodes which are selfconfiguring, connected by wireless links. The nodes are free to move randomly and organize themselves arbitrarily; thus, the network's topology may change rapidly and unpredictably. These kinds of networks are very flexible and they do not require any existing infrastructure. Therefore, ad-hoc wireless networks are suitable for temporary communication links. The biggest challenge in these kinds of networks is to find a path between the communication end points of nodes that are mobile. Due to the limited transmission range of wireless interfaces, the communication traffic has to be relayed over several intermediate nodes to enable the communication between two nodes. Therefore, these kinds of networks are also called multi-hop ad-hoc networks. The proposed model is designed to improve the problems of real-time event-based communication. It improves the packet delivery ratio by prior prediction and reduces end-to-end packet delay. This in turn improves performance of the routing process significantly and increases the Quality of Service (QoS.

  19. Cooperative Compute-and-Forward

    CERN Document Server

    Nokleby, Matthew

    2012-01-01

    We examine the benefits of user cooperation under compute-and-forward. Much like in network coding, receivers in a compute-and-forward network recover finite-field linear combinations of transmitters' messages. Recovery is enabled by linear codes: transmitters map messages to a linear codebook, and receivers attempt to decode the incoming superposition of signals to an integer combination of codewords. However, the achievable computation rates are low if channel gains do not correspond to a suitable linear combination. In response to this challenge, we propose a cooperative approach to compute-and-forward. We devise a lattice-coding approach to block Markov encoding with which we construct a decode-and-forward style computation strategy. Transmitters broadcast lattice codewords, decode each other's messages, and then cooperatively transmit resolution information to aid receivers in decoding the integer combinations. Using our strategy, we show that cooperation offers a significant improvement both in the achi...

  20. Segregation of helicity in inertial wave packets

    Science.gov (United States)

    Ranjan, A.

    2017-03-01

    Inertial waves are known to exist in the Earth's rapidly rotating outer core and could be important for the dynamo generation. It is well known that a monochromatic inertial plane wave traveling parallel to the rotation axis (along positive z ) has negative helicity while the wave traveling antiparallel (negative z ) has positive helicity. Such a helicity segregation, north and south of the equator, is necessary for the α2-dynamo model based on inertial waves [Davidson, Geophys. J. Int. 198, 1832 (2014), 10.1093/gji/ggu220] to work. The core is likely to contain a myriad of inertial waves of different wave numbers and frequencies. In this study, we investigate whether this characteristic of helicity segregation also holds for an inertial wave packet comprising waves with the same sign of Cg ,z, the z component of group velocity. We first derive the polarization relations for inertial waves and subsequently derive the resultant helicity in wave packets forming as a result of superposition of two or more waves. We find that the helicity segregation does hold for an inertial wave packet unless the wave numbers of the constituent waves are widely separated. In the latter case, regions of opposite color helicity do appear, but the mean helicity retains the expected sign. An illustration of this observation is provided by (a) calculating the resultant helicity for a wave packet formed by superposition of four upward-propagating inertial waves with different wave vectors and (b) conducting the direct numerical simulation of a Gaussian eddy under rapid rotation. Last, the possible effects of other forces such as the viscous dissipation, the Lorentz force, buoyancy stratification, and nonlinearity on helicity are investigated and discussed. The helical structure of the wave packet is likely to remain unaffected by dissipation or the magnetic field, but can be modified by the presence of linearly stable stratification and nonlinearity.

  1. UNICAST FORWARDED MULTI-SOURCE MULTICAST ROUTING PROTOCOL FOR MANET

    Directory of Open Access Journals (Sweden)

    J. Rangarajan

    2013-03-01

    Full Text Available In mobile ad hoc network, nodes co-operatively form a network independent of any fixed base station infrastructure. Every node in a mobile ad-hoc network can function as a router and forwards the data packets to the other nodes. Multicasting plays an important role whenever group communications are required. Most of the existing multicast routing protocols in mobile ad hoc networks consider only one source in a multicast group and become inefficient when the protocol is extended to multi-source multicasting. In this paper, we propose a unicast forwarded multi-source multicast routing protocol, for ad hoc networks which is having more than one source in a group. Here, the sources of the group also act as a receiver for other sources in that group. The proposed routing method is a cluster based one and avoids the flooding or broadcasting of control packets to form routing structure. On executing source joining and receiver joining procedures, a complete path for multicast data transfer was established. As the join request control packets are forwarded only through cluster-heads and junction nodes, lower amount of control overhead is incurred. Simulation result shows that the proposed protocol maintains the delivery ratio with reduced control overhead and utilizes the bandwidth efficiently.

  2. Effect of Coulomb interaction on multi-electronwave packet dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Shiokawa, T. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571 (Japan); Takada, Y. [Faculty of Engineering, Tokyo University of Science, Chiyoda, Tokyo, 102-0073, Japan and CREST, Japan Science and Technology Agency (Japan); Konabe, S.; Hatsugai, Y. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and CREST, Japan Science and Technology Agency (Japan); Muraguchi, M. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and CREST, Japan Science and Technology Agency (Japan); Endoh, T. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and Center for Spintronics Integrated Systems, Tohoku University, Sendai, 980-8577, Japan and CREST, Japan Science and Technology Agency (Japan); Shiraishi, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and Center for Computational Science, University of Tsukuba, Tsukuba, 305-8577, Japan and CREST, Japan Science and Technology Agency (Japan)

    2013-12-04

    We have investigated the effect of Coulomb interaction on electron transport in a one-dimensional nanoscale structure using a multi-electron wave packet approach. To study the time evolution, we numerically solve the time-dependent Hartree-Fock equation, finding that the electron wave packet dynamics strongly depends on the Coulomb interaction strength. When the Coulomb interaction is large, each electron wave packet moves separately in the presence of an electric field. With weak Coulomb interaction, however, the electron wave packets overlap, forming and moving as one collective wave packet.

  3. On the Effects of Heterogeneous Packet Lengths on Network Coding

    DEFF Research Database (Denmark)

    Compta, Pol Torres; Fitzek, Frank; Roetter, Daniel Enrique Lucani

    2014-01-01

    Random linear network coding (RLNC) has been shown to provide increased throughput, security and robustness for the transmission of data through the network. Most of the analysis and the demonstrators have focused on the study of data packets with the same size (number of bytes). This constitutes...... a best case scenario as coded packets will incur little overhead to handle such packets. However, packet lengths are quite heterogeneous in real networks, which can cause a high overhead or, alternatively, a high delay in the transmission of data packets. As we show, this can have a severe effect...

  4. SR-MAC: A Low Latency MAC Protocol for Multi-Packet Transmissions in Wireless Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    Hong-Wei Tang; Jian-Nong Cao; Xue-Feng Liu; Cai-Xia Sun

    2013-01-01

    Event detection is one of the major applications of wireless sensor networks (WSNs).Most of existing medium access control (MAC) protocols are mainly optimized for the situation under which an event only generates one packet on a single sensor node.When an event generates multiple packets on a single node,the performance of these MAC protocols degrades rapidly.In this paper,we present a new synchronous duty-cycle MAC protocol called SR-MAC for the event detection applications in which multiple packets are generated on a single node.SR-MAC introduces a new scheduling mechanism that reserves few time slots during the SLEEP period for the nodes to transmit multiple packets.By this approach,SR-MAC can schedule multiple packets generated by an event on a single node to be forwarded over multiple hops in one operational cycle without collision.We use event delivery latency (EDL) and event delivery ratio (EDR) to measure the event detection capability of the SR-MAC protocol.Through detailed ns-2 simulation,the results show that SR-MAC can achieve lower EDL,higher EDR and higher network throughput with guaranteed energy efficiency compared with R-MAC,DW-MAC and PR-MAC.

  5. Network Packet Inspection to Identify Contraband File Sharing Using Forensic Tools

    Directory of Open Access Journals (Sweden)

    K.Arulanandam

    2012-04-01

    Full Text Available This Paper discusses the digital forensic tool that uses a field Programmable Gate Array [FPGA] based software for deep packet inspection in network Router for a Bit Torrent Handshake message. Extracts the “Information Hashing” of the file being shared, compares the hash against a list of known contraband files for forensic analysis and it matches the message to a log file. Forensic analysis gives several optimization techniques for reducing the CPU time required for reducing the CPU time required to process packets are investigated along with their ability to improve packet capture performance. Experiments demonstrate that the system is able to successfully capture and process Bit Torrent Handshake message with a probability of at least 99.0% under a network traffic load of 89.6 Mbps on a 100 Mbps network.

  6. Multicomponent Kinetic Determination by Wavelet Packet Transform Based Elman Recurrent Neural Network Method

    Institute of Scientific and Technical Information of China (English)

    REN Shou-xin; GAO Ling

    2004-01-01

    This paper covers a novel method named wavelet packet transform based Elman recurrent neural network(WPTERNN) for the simultaneous kinetic determination of periodate and iodate. The wavelet packet representations of signals provide a local time-frequency description, thus in the wavelet packet domain, the quality of the noise removal can be improved. The Elman recurrent network was applied to non-linear multivariate calibration. In this case, by means of optimization, the wavelet function, decomposition level and number of hidden nodes for WPTERNN method were selected as D4, 5 and 5 respectively. A program PWPTERNN was designed to perform multicomponent kinetic determination. The relative standard error of prediction(RSEP) for all the components with WPTERNN, Elman RNN and PLS were 3.23%, 11.8% and 10.9% respectively. The experimental results show that the method is better than the others.

  7. ALICE Forward Multiplicity Detector

    CERN Multimedia

    Christensen, C

    2013-01-01

    The Forward Multiplicity Detector (FMD) extends the coverage for multiplicity of charge particles into the forward regions - giving ALICE the widest coverage of the 4 LHC experiments for these measurements.

  8. Forward tracking detectors

    Indian Academy of Sciences (India)

    Klaus Mönig

    2007-11-01

    Forward tracking is an essential part of a detector at the international linear collider (ILC). The requirements for forward tracking are explained and the proposed solutions in the detector concepts are shown.

  9. Congestion Control Algorithm for Resilient Packet Ring

    Institute of Scientific and Technical Information of China (English)

    孔红伟; 葛宁; 阮方; 冯重熙

    2003-01-01

    A congestion control algorithm is proposed for resilient packet ring (RPR) in this paper. In thisalgorithm, nonlinear explicit rate feedback control is used to ensure fast convergence and smooth equilibriumbehavior. The algorithm combines explicit rate control with a deficit round robin (DRR) scheduler, which notonly ensures fairness, but also avoids the implementation difficulties of explicit rate control algorithms. Thealgorithm has good features of fairness, fast convergence, smooth equilibrium, Iow queue depth, and easyimplementation. It is insensitive to the loss of congestion control packets and can adapt to a wide range of linkrates and network scales. It has solved the unbalanced traffic problem of spatial reuse protocol (SRP). Thealgorithm can be implemented on the multi-access control layer of RPR nodes to ensure fair and efficient accessof the best-effort traffic.

  10. SURVEY OF PACKET DROPPING ATTACK IN MANET

    Directory of Open Access Journals (Sweden)

    A.Janani

    2014-03-01

    Full Text Available Mobile Ad-hoc NETwork (MANET is an application of wireless network with self-configuring mobile nodes. MANET does not require any fixed infrastructure. Its development never has any threshold range. Nodes in MANET can communicate with each other if and only if all the nodes are in the same range. This wide distribution of nodes makes MANET vulnerable to various attacks, packet dropping attack or black hole attack is one of the possible attack. It is very hard to detect and prevent. To prevent from packet dropping attack, detection of misbehavior links and selfish nodes plays a vital role in MANETs. In this paper, a omprehensive investigation on detection of misbehavior links and malicious nodes is carried out.

  11. Frequency Domain Packet Scheduling Under Fractional Load for the UTRAN LTE Downlink

    DEFF Research Database (Denmark)

    Pokhariyal, Akhilesh; Monghal, Guillaume Damien; Pedersen, Klaus I.

    2007-01-01

     In this paper we investigate performance of frequency domain packet scheduling (FDPS) under fractional load (FL), based on the UTRAN Long Term Evolution downlink. FL may be regarded as an inter-cell interference (ICI) mitigation technique, which can improve the user experienced SINR. We consider...

  12. Removing Signal Intensity Inhomogeneity From Surface Coil MRI Using Discrete Wavelet Transform and Wavelet Packet

    Science.gov (United States)

    2001-10-25

    We evaluate a combined discrete wavelet transform (DWT) and wavelet packet algorithm to improve the homogeneity of magnetic resonance imaging when a...image and uses this information to normalize the image intensity variations. Estimation of the coil sensitivity profile based on the wavelet transform of

  13. Carrier Load Balancing and Packet Scheduling for Multi-Carrier Systems

    DEFF Research Database (Denmark)

    Wang, Yuanye; Pedersen, Klaus; Sørensen, Troels Bundgaard

    2010-01-01

    methods for allocating the CCs to the users- Round Robin (RR) and Mobile Hashing (MH) balancing by means of a simple theoretical formulation, as well as system level simulations. At Layer-2 we propose a simple cross-CC packet scheduling algorithm that improves the coverage performance and the resource...

  14. Ship-Shore Packet Switched Communications System.

    Science.gov (United States)

    1986-06-01

    a fatal flaw for sea service communications. This instability is described in several texts [ Stallings , 85; Tanenbaum, 81]. 68 b. Token Systems Again... decompressor in the data path. otherwise, the decompression algorithm would compound errors and make different instances of errored packets different lengths...Further detail may be found in several sources including listed references [ Stallings , 85]. DoD’s seminal ARPANET work predated the ISO model and evolved a

  15. Teleportation of Nonclassical Wave Packets of light

    CERN Document Server

    Lee, Noriyuki; Takeno, Yuishi; Takeda, Shuntaro; Webb, James; Huntington, Elanor; Furusawa, Akira

    2012-01-01

    We report on the experimental quantum teleportation of strongly nonclassical wave packets of light. To perform this full quantum operation while preserving and retrieving the fragile non-classicality of the input state, we have developed a broadband, zero-dispersion teleportation apparatus that works in conjunction with time-resolved state preparation equipment. Our approach brings within experimental reach a whole new set of hybrid protocols involving discrete- and continuous-variable techniques in quantum information processing for optical sciences.

  16. Voice Communications Over Packet Radio Networks.

    Science.gov (United States)

    1985-03-01

    standpoint, the major difference between telephone networks and packet radio networks concerns the availabilty of time slots over each frame. The...mentioning that simulations require large amounts of detailed knowledge about the structure of the system and about patterns of usage . Simulation is...proposed time slot algorithm adopts. Moreover, the proposed time slot scheme may give more uniform usage of time slots in each time frame. In addition

  17. Spectral Modulation by Rotational Wave Packets

    Science.gov (United States)

    Baertschy, Mark; Hartinger, Klaus

    2005-05-01

    Periodic rephasing of molecular rotational wave packets can create rapid fluctuations in the optical properties of a molecular gas which can be used to manipulate the temporal phase and spectral content of ultrashort light pulses. We have demonstrated spectral control of a time-delayed ultrafast probe pulse propagating through the rotational wave packet prepared by a pump laser pulse. The spectrum of the probe pulse can be either broadened or compressed, depending on the relative sign of the temporal phase modulation and the initial chirp of the probe pulse. Adjustment of the spectral phase at the output of the interaction region allows controlled temporal pulse streching^1 and compression^2. The degree to which the spectrum of an ultrafast pulse can be modified depends on the strength and shape of the rotational wavepacket. We are studying the optimization of the rotational wave packet excitation with complex, shaped pump laser pulses for the purpose of optimizing probe pulse spectra modulation. ^1 Klaus Hartinger and Randy A. Bartels, Opt. Lett., submitted (2005). ^2 R.A. Bartels, T.C. Weinacht, N. Wagner, M. Baertschy, Chris H. Greene, M.M. Murnane, and H.C. Kapteyn , Phys. Rev. Lett., 88, 013903 (2002). This work was supported by the NSF.

  18. Turbulent Spot Pressure Fluctuation Wave Packet Model

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    Wave packet analysis provides a connection between linear small disturbance theory and subsequent nonlinear turbulent spot flow behavior. The traditional association between linear stability analysis and nonlinear wave form is developed via the method of stationary phase whereby asymptotic (simplified) mean flow solutions are used to estimate dispersion behavior and stationary phase approximation are used to invert the associated Fourier transform. The resulting process typically requires nonlinear algebraic equations inversions that can be best performed numerically, which partially mitigates the value of the approximation as compared to a more complete, e.g. DNS or linear/nonlinear adjoint methods. To obtain a simpler, closed-form analytical result, the complete packet solution is modeled via approximate amplitude (linear convected kinematic wave initial value problem) and local sinusoidal (wave equation) expressions. Significantly, the initial value for the kinematic wave transport expression follows from a separable variable coefficient approximation to the linearized pressure fluctuation Poisson expression. The resulting amplitude solution, while approximate in nature, nonetheless, appears to mimic many of the global features, e.g. transitional flow intermittency and pressure fluctuation magnitude behavior. A low wave number wave packet models also recover meaningful auto-correlation and low frequency spectral behaviors.

  19. ATLAS forward physics program

    CERN Document Server

    HELLER, M; The ATLAS collaboration

    2010-01-01

    The variety of forward detectors installed in the vicinity of the ATLAS experiment allows to look over a wide range of forward physics topics. They ensure a good information about rapidity gaps, and the installation of very forward detectors (ALFA and AFP) will allow to tag the leading proton(s) remaining from the different processes studied. Most of the studies have to be done at low luminosity to avoid pile-up, but the AFP project offers a really exiting future for the ATLAS forward physics program. We also present how these forward detectors can be used to measure the relative and absolute luminosity.

  20. Wireless Local Area Networks with Multiple-Packet Reception Capability

    CERN Document Server

    Zhang, Ying Jun; Liew, Soung Chang

    2007-01-01

    Thanks to its simplicity and cost efficiency, wireless local area network (WLAN) enjoys unique advantages in providing high-speed and low-cost wireless services in hot spots and indoor environments. Traditional WLAN medium-access-control (MAC) protocols assume that only one station can transmit at a time: simultaneous transmissions of more than one station causes the destruction of all packets involved. By exploiting recent advances in PHY-layer multiuser detection (MUD) techniques, it is possible for a receiver to receive multiple packets simultaneously. This paper argues that such multipacket reception (MPR) capability can greatly enhance the capacity of future WLANs. In addition, it provides the MAC-layer and PHY-layer designs needed to achieve the improved capacity. First, to demonstrate MUD/MPR as a powerful capacity-enhancement technique, we prove a "super-linearity" result, which states that the system throughput per unit cost increases as the MPR capability increases. Second, we show that the commonly...

  1. Improve the performance of orthogonal ASK/DPSK optical label switching by DC-balanced line encoding

    DEFF Research Database (Denmark)

    Chi, Nan; Xu, Lin; Zhang, J.;

    2006-01-01

    Orthogonal amplitude shift keying/differential phase-shift keying (ASK/DPSK) labeling is a promising approach to ultrahigh packet-rate routing and forwarding in the optical layer. However, the limitation on the payload extinction ratio (ER) is a detrimental effect for network scalability and tran......Orthogonal amplitude shift keying/differential phase-shift keying (ASK/DPSK) labeling is a promising approach to ultrahigh packet-rate routing and forwarding in the optical layer. However, the limitation on the payload extinction ratio (ER) is a detrimental effect for network scalability...... and transparency. This paper presents theoretical and experimental studies of ASK/DPSK labeling. It proposes that dc-balanced 8B10B coding can greatly improve ER tolerance, which in turn leads to better system performance. By using the 8B10B coding method, the paper demonstrates transmission and optical label...

  2. Tunable locally-optimal geographical forwarding in wireless sensor networks with sleep-wake cycling nodes

    CERN Document Server

    Naveen, K P

    2009-01-01

    We consider a wireless sensor network whose main function is to detect certain infrequent alarm events, and to forward alarm packets to a base station, using geographical forwarding. The nodes know their locations, and they sleep-wake cycle, waking up periodically but not synchronously. In this situation, when a node has a packet to forward to the sink, there is a trade-off between how long this node waits for a suitable neighbor to wake up and the progress the packet makes towards the sink once it is forwarded to this neighbour. Hence, in choosing a relay node, we consider the problem of minimizing average delay subject to a constraint on the average progress. By constraint relaxation, involving a Lagrange multiplier, we formulate this next hop relay selection problem as a Markov decision process (MDP). The exact optimal solution (BF (Best Forward)) can be found, but is computationally intensive. Next, we consider a mathematically simplified model for which the optimal policy (SF (Simplified Forward)) turns ...

  3. 一种用于网络攻击犯罪防范的数据包分配防护方法%Network Packets Distribution Protection Method of Preventing Network Attack Crime

    Institute of Scientific and Technical Information of China (English)

    朱超军; 赵丹丹

    2016-01-01

    Network attack crime is considered to be the one of the most important threats to network especially the Internet security, packet distribution protection algorithm USES linear combination of the traditional retransmission approach to cyber attacks in the prevention of crime. But the volatility of the network environment, making the receiver of information produced by negative feedback effect, lead to packet distribution balance differential protection algorithm. Put forward a kind of used for network packet distribution of attack crime prevention protection method. Distributed computing method, and the fusion in random network coding method, access to a wireless network packet coding decoding linear equation, using the equation of network node information feedback mechanisms, encoding and decoding optimize network packets, improve the distribution of the network packet protection performance. The simulation results show that this algorithm effectively reduce the distribution of bit error rate of wireless network packets, improve the performance of network packet distribution protection is balanced, can be applied to a good network attack in the prevention of crime.%网络攻击犯罪被认为是目前影响网络尤其是因特网安全的重要威胁之一,传统的数据包分配防护算法采用线性组合重传方式进行网络攻击犯罪的防范。但网络环境的波动性,使得接收方对信息产生的负反馈效应,导致数据包分配防护算法的均衡性差。提出一种用于网络攻击犯罪防范的数据包分配防护方法。采用分布式计算方法,并融合于随机网络编码方法,获取无线网络数据包的编码解码线性方程,利用方程中网络节点信息反馈机制,编码解码并优化重组网络数据包,提高网络数据包的分配防护性能。仿真结果表明,采用该算法有效降低无线网络数据包的分配误比特率,提高了网络数据包分配防护均衡性能,

  4. Hybrid Packet-Pheromone-Based Probabilistic Routing for Mobile Ad Hoc Networks

    Science.gov (United States)

    Kashkouli Nejad, Keyvan; Shawish, Ahmed; Jiang, Xiaohong; Horiguchi, Susumu

    Ad-Hoc networks are collections of mobile nodes communicating using wireless media without any fixed infrastructure. Minimal configuration and quick deployment make Ad-Hoc networks suitable for emergency situations like natural disasters or military conflicts. The current Ad-Hoc networks can only support either high mobility or high transmission rate at a time because they employ static approaches in their routing schemes. However, due to the continuous expansion of the Ad-Hoc network size, node-mobility and transmission rate, the development of new adaptive and dynamic routing schemes has become crucial. In this paper we propose a new routing scheme to support high transmission rates and high node-mobility simultaneously in a big Ad-Hoc network, by combining a new proposed packet-pheromone-based approach with the Hint Based Probabilistic Protocol (HBPP) for congestion avoidance with dynamic path selection in packet forwarding process. Because of using the available feedback information, the proposed algorithm does not introduce any additional overhead. The extensive simulation-based analysis conducted in this paper indicates that the proposed algorithm offers small packet-latency and achieves a significantly higher delivery probability in comparison with the available Hint-Based Probabilistic Protocol (HBPP).

  5. Defending of IP Spoofing by Ingress Filter in Extended-Inter Domain Packet Key Marking System

    Directory of Open Access Journals (Sweden)

    G.Velmayil

    2013-04-01

    Full Text Available The significance of the DDoS problem and the increased occurrence and strength of attacks has led to the dawn of numerous prevention mechanisms. IP spoofing is most frequently used in denial-of-service attacks. In such attacks, the goal is to flood the victim with overwhelming amounts of traffic, and the attacker does not care about receiving responses to the attack packets. IP spoofing is one of the basic weaknesses in the Internet Protocol to launch the DDOS attack. Each prevention mechanism has some unique advantages and disadvantages over the others. The existing methods become ineffective due to a large number of filters required and they lack in information about where to place the filter. We propose Ingress filter in Extended Inter Domain Packet Key marking system .This paper comprises of two functional blocks namely, Key marking system and filtering blocks. In the marking block, each source is labeled with a key. The key is changed continuously for a certain period of time to provide secured system and is validated at border routers. In the filtering block, spoofed packets are filtered at the border router using Ingress filter to filter beyond periphery routers. The filter placement algorithm clearly put forwards the conditions under which the filter can operate accurately. The accuracy of the proposed systems is validated using Network Simulator (NS-2.

  6. On Limits of Embedded Systems in Network Packet Processing

    Directory of Open Access Journals (Sweden)

    Ondrej Vondrous

    2016-01-01

    Full Text Available The paper deals with a measurement of single-hop one way packet delay on embedded systems used for networking. The single-hop one way packet delay is essential parameter when we need to process packets with strict delivery time constrains. Comparison of different approaches to single-hop one way packet delay measurements is presented in this work along with discussion about strong and weak points in specific measurement approach. The impact of different types of system load and number of CPU cores are also covered by presented results. The presented results of measurement single-hop one way packet delay in embedded Linux system show that for the specific system configuration the packet processing delay depends (in different ways on system load and network stack load.

  7. Traffic-Aware Frequent Elements Matching Algorithms for Deep Packet Inspection

    Directory of Open Access Journals (Sweden)

    Kefu Xu

    2011-05-01

    Full Text Available     Deep packet inspection sometimes is called application level semantic detection, which capable of examining the content of data packets in order to provide application-specific services and improve network security. Application traffic classification based on regular expressions is an essential step for deep packet inspection. However regular expression, especially multiple regular expressions matching is known to require intensive system resources and is often a performance bottleneck. Currently, the DFAs of regular expression are constructed in the preprocessing stage and the context of network streams is excluded which leads to low throughputs. In this paper, we analyzed the application level protocols and found that the protocols are uniformly distributed and it is changing dynamically. From the protocol distribution characteristic, we proposed an adaptive multiple regular expressions matching method for application traffic classification with deep packet inspection. The adaptive method, schedule the multiple DFAs through splay tree by matching probability other than linear scheduling in linked list, can adjust scheduling sequence according with the changing dynamic traffics. We evaluate the proposed method with the L7 rules; experiments proved that our method can improve the throughputs more than three times.

  8. Advanced Radio Resource Management for Multi Antenna Packet Radio Systems

    OpenAIRE

    Stanislav Nonchev; Mikko Valkama

    2010-01-01

    In this paper, we propose fairness-oriented packet scheduling (PS) schemes with power-efficientcontrol mechanism for future packet radio systems. In general, the radio resource managementfunctionality plays an important role in new OFDMA based networks. The control of the networkresource division among the users is performed by packet scheduling functionality based on maximizingcell coverage and capacity satisfying, and certain quality of service requirements. Moreover, multiantennatransmit-r...

  9. Compressed Domain Packet Loss Concealment of Sinusoidally Coded Speech

    DEFF Research Database (Denmark)

    Rødbro, Christoffer A.; Christensen, Mads Græsbøll; Andersen, Søren Vang

    2003-01-01

    We consider the problem of packet loss concealment for voice over IP (VoIP). The speech signal is compressed at the transmitter using a sinusoidal coding scheme working at 8 kbit/s. At the receiver, packet loss concealment is carried out working directly on the quantized sinusoidal parameters......, based on time-scaling of the packets surrounding the missing ones. Subjective listening tests show promising results indicating the potential of sinusoidal speech coding for VoIP....

  10. Packet Selection and Scheduling for Multipath Video Streaming

    OpenAIRE

    Jurca, Dan; Frossard, Pascal

    2004-01-01

    This paper addresses the problem of choosing the best streaming policy for distortion optimal multipath video delivery, under delay constraints. The streaming policy consists in a joint selection of the video packets to be transmitted, as well as their sending time, and the transmission path. A simple streaming model is introduced, which takes into account the video packet importance, and the dependencies among packets, and allows to compute the quality perceived by the receiver, as a functio...

  11. Fast packet switch architectures for broadband integrated services digital networks

    Science.gov (United States)

    Tobagi, Fouad A.

    1990-01-01

    Background information on networking and switching is provided, and the various architectures that have been considered for fast packet switches are described. The focus is solely on switches designed to be implemented electronically. A set of definitions and a brief description of the functionality required of fast packet switches are given. Three basic types of packet switches are identified: the shared-memory, shared-medium, and space-division types. Each of these is described, and examples are given.

  12. Square-integrability of multivariate metaplectic wave-packet representations

    Science.gov (United States)

    Ghaani Farashahi, Arash

    2017-03-01

    This paper presents a systematic study for harmonic analysis of metaplectic wave-packet representations on the Hilbert function space {{L}2}≤ft({{{R}}d}\\right) . The abstract notions of symplectic wave-packet groups and metaplectic wave-packet representations will be introduced. We then present an admissibility condition on closed subgroups of the real symplectic group \\text{Sp}≤ft({{{R}}d}\\right) , which guarantees the square-integrability of the associated metaplectic wave-packet representation on {{L}2}≤ft({{{R}}d}\\right) .

  13. Development of optical packet and circuit integrated ring network testbed.

    Science.gov (United States)

    Furukawa, Hideaki; Harai, Hiroaki; Miyazawa, Takaya; Shinada, Satoshi; Kawasaki, Wataru; Wada, Naoya

    2011-12-12

    We developed novel integrated optical packet and circuit switch-node equipment. Compared with our previous equipment, a polarization-independent 4 × 4 semiconductor optical amplifier switch subsystem, gain-controlled optical amplifiers, and one 100 Gbps optical packet transponder and seven 10 Gbps optical path transponders with 10 Gigabit Ethernet (10GbE) client-interfaces were newly installed in the present system. The switch and amplifiers can provide more stable operation without equipment adjustments for the frequent polarization-rotations and dynamic packet-rate changes of optical packets. We constructed an optical packet and circuit integrated ring network testbed consisting of two switch nodes for accelerating network development, and we demonstrated 66 km fiber transmission and switching operation of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10GbE frames. Error-free (frame error rate < 1×10(-4)) operation was achieved with optical packets of various packet lengths and packet rates, and stable operation of the network testbed was confirmed. In addition, 4K uncompressed video streaming over OPS links was successfully demonstrated.

  14. Moving Forward - Progress on Forward Detectors

    CERN Multimedia

    Grafstrom, P.

    2006-01-01

    You might have been sitting in some meeting hearing about the ATLAS forward detectors. Coming back to your office wanting to learn more you look in the ATLAS TDR’s and disappointingly you find nothing about forward detectors. The explanation is of course that the forward detectors are newcomers in the ATLAS detector arsenal. ATLAS is designed to measure high Pt particles with pseudo rapidities up to 5 which in terms of angles means angles bigger than one degree (0.8 degree to be more accurate). Particles produced with smaller angles close to the beam escape detection. The hole in the forward direction will now partly be filled. Several new detectors have recently been proposed. These detectors are designed for various luminosity measurements but they also have a physics potential in themselves. Closest to the IP there is LUCID (LUminosity measurement using Cerenkov Integrating Detector). LUCID comprises some 170 Cerenkov tubes sitting around the beam pipe at about 17 m away from the IP. The tubes are 1.5 ...

  15. Spreading of Ultrarelativistic Wave Packet and Redshift

    CERN Document Server

    Lev, Felix M

    2012-01-01

    The red shift of light coming to the Earth from distant objects is usually explained as a consequence of the fact that the Universe is expanding. Such an explanation implies that photons emitted by distant objects travel in the interstellar medium practically without interaction with interstellar matter and hence they can survive their long journey to the Earth. We analyze this assumption by considering wave-packet spreading for an ultrarelativistic particle. We derive a formula which shows that spreading in the direction perpendicular to the particle momentum is very important and cannot be neglected. The implications of the results are discussed.

  16. On Steganography in Lost Audio Packets

    CERN Document Server

    Mazurczyk, Wojciech; Szczypiorski, Krzysztof

    2011-01-01

    The paper presents a new hidden data insertion procedure based on estimated probability of the remaining time of the call for steganographic method called LACK (Lost Audio PaCKets steganography). LACK provides hidden communication for real-time services like Voice over IP. The analytical results presented in this paper concern the influence of LACK's hidden data insertion procedures on the method's impact on quality of voice transmission and its resistance to steganalysis. The proposed hidden data insertion procedure is also compared to previous steganogram insertion approach based on estimated remaining average call duration.

  17. Quantization of wavelet packet audio coding

    Institute of Scientific and Technical Information of China (English)

    Tan Jianguo; Zhang Wenjun; Liu Peilin

    2006-01-01

    The method of quantization noise control of audio coding in the wavelet domain is proposed. Using the inverse Discrete Fourier Transform (DFT), it converts the masking threshold coming from MPEG psycho-acoustic model in the frequency domain to the signal in the time domain; the Discrete Wavelet Packet Transform (DWPT) is performed; the energy in each subband is regarded as the maximum allowed quantization noise energy. The experimental result shows that the proposed method can attain the nearly transparent audio quality below 64kbps for the most testing audio signals.

  18. PHACK: An Efficient Scheme for Selective Forwarding Attack Detection in WSNs

    Directory of Open Access Journals (Sweden)

    Anfeng Liu

    2015-12-01

    Full Text Available In this paper, a Per-Hop Acknowledgement (PHACK-based scheme is proposed for each packet transmission to detect selective forwarding attacks. In our scheme, the sink and each node along the forwarding path generate an acknowledgement (ACK message for each received packet to confirm the normal packet transmission. The scheme, in which each ACK is returned to the source node along a different routing path, can significantly increase the resilience against attacks because it prevents an attacker from compromising nodes in the return routing path, which can otherwise interrupt the return of nodes’ ACK packets. For this case, the PHACK scheme also has better potential to detect abnormal packet loss and identify suspect nodes as well as better resilience against attacks. Another pivotal issue is the network lifetime of the PHACK scheme, as it generates more acknowledgements than previous ACK-based schemes. We demonstrate that the network lifetime of the PHACK scheme is not lower than that of other ACK-based schemes because the scheme just increases the energy consumption in non-hotspot areas and does not increase the energy consumption in hotspot areas. Moreover, the PHACK scheme greatly simplifies the protocol and is easy to implement. Both theoretical and simulation results are given to demonstrate the effectiveness of the proposed scheme in terms of high detection probability and the ability to identify suspect nodes.

  19. Routing Diverse Evacuees with the Cognitive Packet Network Algorithm

    Directory of Open Access Journals (Sweden)

    Huibo Bi

    2014-04-01

    Full Text Available Regarding mobility, health conditions and personal preferences, evacuees can be categorized into different classes in realistic environments. Previous emergency navigation algorithms that direct evacuees with a single decision rule cannot fulfil civilians’ distinct service requirements and increase the likelihood of inducing destructive crowd behaviours, such as clogging, pushing and trampling, due to diverse mobility. This paper explores a distributed emergency navigation algorithm that employs the cognitive packet network concept to tailor different quality of service needs to different categories of evacuees. In addition, a congestion-aware algorithm is presented to predict the future congestion degree of a path with respect to the observed population density, arrival rate and service rate of each route segment. Experiments are implemented in a simulated environment populated with autonomous agents. Results show that our algorithm can increase the number of survivors while providing improved quality of service.

  20. SOFOMORE: Combined EEG source and forward model reconstruction

    DEFF Research Database (Denmark)

    Stahlhut, Carsten; Mørup, Morten; Winther, Ole;

    2009-01-01

    We propose a new EEG source localization method that simultaneously performs source and forward model reconstruction (SOFOMORE) in a hierarchical Bayesian framework. Reconstruction of the forward model is motivated by the many uncertainties involved in the forward model, including the representat......We propose a new EEG source localization method that simultaneously performs source and forward model reconstruction (SOFOMORE) in a hierarchical Bayesian framework. Reconstruction of the forward model is motivated by the many uncertainties involved in the forward model, including...... the representation of the cortical surface, conductivity distribution, and electrode positions. We demonstrate in both simulated and real EEG data that reconstruction of the forward model improves localization of the underlying sources....

  1. DATA FORWARDING IN OPPORTUNISTIC NETWORK USING MOBILE TRACES

    Directory of Open Access Journals (Sweden)

    B.Poonguzharselvi

    2012-10-01

    Full Text Available Opportunistic networks are usually formed spontaneously by mobile devices equipped with short range wireless communication interfaces. The idea is that an end-to-end connection may never be present. Designing and implementing a routing protocol to support both service discovery and delivery in such kinds of networks is a challenging problem on account of frequent disconnections and topology changes. In these networks one of the most important issues relies on the selection of the best intermediate node to forward the messages towards the destination. This paper presents a mobile trace based routing protocol that uses the location information of the nodes in the network. Using the trace information, next hop is selected to forward the packets to destination. Data forwarding is done via the selected nodes. The effectiveness is shown using simulation.

  2. Scattering of wave packets with phases

    CERN Document Server

    Karlovets, Dmitry

    2016-01-01

    A general problem of $2\\rightarrow N_f$ scattering is addressed with all the states being wave packets with arbitrary phases. Depending on these phases, one deals with coherent states in $(3+1)$ D, vortex particles with orbital angular momentum, the Airy beams, and their generalizations. A method is developed in which a number of events represents a functional of the Wigner functions of such states. Using width of a packet $\\sigma_p/\\langle p\\rangle$ as a small parameter, the Wigner functions, the number of events, and a cross section are represented as power series in this parameter, the first non-vanishing corrections to their plane-wave expressions are derived, and generalizations for beams are made. Although in this regime the Wigner functions turn out to be everywhere positive, the cross section develops new specifically quantum features, inaccessible in the plane-wave approximation. Among them is dependence on an impact parameter between the beams, on phases of the incoming states, and on a phase of the...

  3. Scattering of wave packets with phases

    Science.gov (United States)

    Karlovets, Dmitry V.

    2017-03-01

    A general problem of 2 → N f scattering is addressed with all the states being wave packets with arbitrary phases. Depending on these phases, one deals with coherent states in (3 + 1) D, vortex particles with orbital angular momentum, the Airy beams, and their generalizations. A method is developed in which a number of events represents a functional of the Wigner functions of such states. Using width of a packet σ p /p> as a small parameter, the Wigner functions, the number of events, and a cross section are represented as power series in this parameter, the first non-vanishing corrections to their plane-wave expressions are derived, and generalizations for beams are made. Although in this regime the Wigner functions turn out to be everywhere positive, the cross section develops new specifically quantum features, inaccessible in the plane-wave approximation. Among them is dependence on an impact parameter between the beams, on phases of the incoming states, and on a phase of the scattering amplitude. A model-independent analysis of these effects is made. Two ways of measuring how a Coulomb phase and a hadronic one change with a transferred momentum t are discussed.

  4. Bilateral Waveform Similarity Overlap-and-Add Based Packet Loss Concealment for Voice over IP

    Directory of Open Access Journals (Sweden)

    J.F. Yeh

    2013-08-01

    Full Text Available This paper invested a bilateral waveform similarity overlap-and-add algorithm for voice packet lost. Since Packet lost will cause the semantic misunderstanding, it has become one of the most essential problems in speech communication. This investment is based on waveform similarity measure using overlap-and-Add algorithm and provides the bilateral information to enhance the speech signal reconstruction. Traditionally, it has been improved that waveform similarity overlap-and-add (WSOLA technique is an effective algorithm to deal with packet loss concealment (PLC for real-time time communication. WSOLA algorithm is widely applied to deal with the length adaptation and packet loss concealment of speech signal. Time scale modification of audio signal is one of the most essential research topics in data communication, especially in voice of IP (VoIP. Herein, the proposed the bilateral WSOLA (BWSOLA that is derived from WSOLA. Instead of only exploitation one direction speech data, the proposed method will reconstruct the lost voice data according to the preceding and cascading data. The related algorithms have been developed to achieve the optimal reconstructing estimation. The experimental results show that the quality of the reconstructed speech signal of the bilateral WSOLA is much better compared to the standard WSOLA and GWSOLA on different packet loss rate and length using the metrics PESQ and MOS. The significant improvement is obtained by bilateral information and proposed method. The proposed bilateral waveform similarity overlap-and-add (BWSOLA outperforms the traditional approaches especially in the long duration data loss.

  5. COMPARISON AND ANALYSIS OF GREEDY FORWARDING USING BNGF METHOD IN DIFFERENT VEHICULAR TRAFFIC SCENARIOS

    Directory of Open Access Journals (Sweden)

    Ram Shringar Raw

    2011-06-01

    Full Text Available A Vehicular Ad hoc Network (VANET is a most popular application of Mobile Ad hoc Networks (MANETs. A lot of research work around the world is being conducted to design an efficient routing protocol for VANETs. In this paper, we examine the significance of Greedy Forwarding with Border Node based approach for VANETs. We propose a position based routing protocol to forward packet to the border nodes of the forwarding nodeas the next-hop node. This protocol is called Border Node based Greedy Forwarding (BNGF since it uses border nodes with greedy forwarding. We categorize BNGF as BNGF-H for highway and BNGF-C for city traffic scenario. We have simulated this protocol using NS-2 simulator and evaluated the performance in terms of end-to-end delay and packet delivery ratio. We have compared both the methods for highway and city traffic scenarios. The results clearly show that the end-toend delay for BNGF-C is significantly lower and packet delivery ratio is higher than BNGF-H.

  6. 两次随机丢包的被动队列管理算法%Passive Queue Management Algorithm Based on Twice Randomly Dropping Packets

    Institute of Scientific and Technical Information of China (English)

    姜文刚; 孙金生; 王执铨

    2011-01-01

    The active queue management increases the spending of hardware resources and computation amount,and also there exists sensitive parameter settings and the phenomenon of response lagging behind actual network in it,so the active queue management has not been widely used in actual network.Therefore,the drop tail passive queue management was improved,which is most widely used now,and the passive queue management algorithm based on twice randomly dropping packets was proposed.When the queue is full,randomly dropping packets in twice,which will improve the defects of drop tail,and develop the transmission performance of the network;the concept of speed fairness was put forward.This passive queue management algorithm based on twice randomly dropping packets will punish "TCP link" greatly,which occupies more spaces in the queue,and improve the RTT fairness and speed fairness effectively;Computation of this algorithm is small;the NS2 simulation results show the effectiveness of the algorithm.%主动队列管理算法增加了硬件资源和运算量的开销,并且存在参数设置敏感,响应相对滞后于实际网络状况的缺陷,并没有在实际网络上推广使用。因此对目前使用最多的弃尾被动队列管理进行改进,提出了两次随机丢包的被动队列管理算法。在队列满时,两次随机丢弃队列中的数据包,改善弃尾队列管理的缺陷,提高了网络传输性能;提出了速度公平性的概念,两次随机丢包的被动队列管理算法对占据队列较多的TCP链接有更好的惩罚作用,能有效提高RTT公平性和速度公平性;该算法计算量小;NS2仿真表明该算法的有效性。

  7. Controlling the spreading of wave packets of a dissociating molecule

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2007-01-01

    in the Franck-Condon region whereas, as well known, the positively chirped pulses focus the wave packet in the asymptotic region. For the negatively chirped pulses, we show that the time corresponding to the minimum in the width of the wave packet can be predicted by an analytical formula. (C) 2007 Elsevier B.V...

  8. Equations of motion for a relativistic wave packet

    Indian Academy of Sciences (India)

    L Kocis

    2012-05-01

    The time derivative of the position of a relativistic wave packet is evaluated. It is found that it is equal to the mean value of the momentum of the wave packet divided by the mass of the particle. The equation derived represents a relativistic version of the second Ehrenfest theorem.

  9. All-optical devices for ultrafast packet switching

    DEFF Research Database (Denmark)

    Dorren, H.J.S.; HerreraDorren, J.; Raz, O.;

    2007-01-01

    We discuss integrated devices for all-optical packet switching. We focus on monolithically integrated all-optical flip-flops, ultra-fast semiconductor based wavelength converters and explain the operation principles. Finally, a 160 Gb/s all-optical packet switching experiment over 110 km of field...

  10. Comparison of Deep Packet Inspection (DPI) Tools for Traffic Classification

    DEFF Research Database (Denmark)

    Bujlow, Tomasz; Carela-Español, Valentín; Barlet-Ros, Pere

    a dataset, which can be used to test all the traffic classifiers. In order to do that, we used our system to collect the complete packets from the network interfaces. The packets are grouped into flows, and each flow is collected together with the process name taken from Windows / Linux sockets, so...

  11. Continuing Development of California State Packet Radio Project.

    Science.gov (United States)

    Brownrigg, Edwin

    1992-01-01

    Provides background on the California State Library Packet Radio project, which will use packet radios to deploy a wireless, high-speed, wide-area network of 600 nodes, including 100 libraries, in the San Francisco Bay Area. Project goals and objectives, plan of operation, equipment, and evaluation plans are summarized. (MES)

  12. On Generalized Carleson Operators of Periodic Wavelet Packet Expansions

    Directory of Open Access Journals (Sweden)

    Shyam Lal

    2013-01-01

    Full Text Available Three new theorems based on the generalized Carleson operators for the periodic Walsh-type wavelet packets have been established. An application of these theorems as convergence a.e. for the periodic Walsh-type wavelet packet expansion of block function with the help of summation by arithmetic means has been studied.

  13. The Surgical Scrub. Instructor's Packet. Learning Activity Package.

    Science.gov (United States)

    Runge, Lillian

    This instructor's packet accompanies the learning activity package (LAP) on the surgical scrub. Contents included in the packet are a time sheet, suggested uses for the LAP, an instruction sheet, final LAP reviews, a final LAP review answer key, a student performance checklist, suggested activities, an additional resources list, and student…

  14. Detecting Black Holes in Packet-Radio Networks (SRNTN-56)

    Science.gov (United States)

    1989-01-01

    Black holes can occur in packet-switched networks that use distance- vector route calculation algorithms such as tier routing. This section briefly...reviews tier routing and defines new terms relevant to black holes . Packet radios use tier routing, a variation on distance-vector routing, to maintain

  15. Sculpture of Indonesia. [Teacher's Packet for a Teacher Workshop.

    Science.gov (United States)

    Asian Art Museum of San Francisco, CA.

    This teacher's packet accompanies a slide presentation on the sculpture found in Indonesia. The packet contains: (1) a slide list with descriptions listing time period and dimensions of each piece; (2) an introductory essay describing the setting of Indonesia, the Central Javanese Period and the Eastern Javanese Period; (3) descriptions of how to…

  16. Packet Delay Variation Analysis of the CQ Switch

    OpenAIRE

    I. Radusinović; I. Maljević; M. Radonjić

    2012-01-01

    Packet delay variation analysis for a 32x32 crosspoint queued switch under uniform and IBP arrival traffic is presented in this paper. Different buffer sizes and several scheduling algorithms are observed: longest queue first, round robin, exhaustive round robin and frame based round robin matching. Results show that the least packet delay variation, among observed algorithms, causes round robin algorithm.

  17. Packet Delay Variation Analysis of the CQ Switch

    Directory of Open Access Journals (Sweden)

    I. Radusinović

    2012-06-01

    Full Text Available Packet delay variation analysis for a 32x32 crosspoint queued switch under uniform and IBP arrival traffic is presented in this paper. Different buffer sizes and several scheduling algorithms are observed: longest queue first, round robin, exhaustive round robin and frame based round robin matching. Results show that the least packet delay variation, among observed algorithms, causes round robin algorithm.

  18. Wearable sensors for patient-specific boundary shape estimation to improve the forward model for electrical impedance tomography (EIT) of neonatal lung function.

    Science.gov (United States)

    Khor, Joo Moy; Tizzard, Andrew; Demosthenous, Andreas; Bayford, Richard

    2014-06-01

    Electrical impedance tomography (EIT) could be significantly advantageous to continuous monitoring of lung development in newborn and, in particular, preterm infants as it is non-invasive and safe to use within the intensive care unit. It has been demonstrated that accurate boundary form of the forward model is important to minimize artefacts in reconstructed electrical impedance images. This paper presents the outcomes of initial investigations for acquiring patient-specific thorax boundary information using a network of flexible sensors that imposes no restrictions on the patient's normal breathing and movements. The investigations include: (1) description of the basis of the reconstruction algorithms, (2) tests to determine a minimum number of bend sensors, (3) validation of two approaches to reconstruction and (4) an example of a commercially available bend sensor and its performance. Simulation results using ideal sensors show that, in the worst case, a total shape error of less than 6% with respect to its total perimeter can be achieved.

  19. An Experimental Investigation of Hyperbolic Routing with a Smart Forwarding Plane in NDN

    CERN Document Server

    Lehman, Vince; Zhang, Beichuan; Zhang, Lixia; Aldecoa, Rodrigo; Krioukov, Dmitri; Wang, Lan

    2016-01-01

    Routing in NDN networks must scale in terms of forwarding table size and routing protocol overhead. Hyperbolic routing (HR) presents a potential solution to address the routing scalability problem, because it does not use traditional forwarding tables or exchange routing updates upon changes in network topologies. Although HR has the drawbacks of producing sub-optimal routes or local minima for some destinations, these issues can be mitigated by NDN's intelligent data forwarding plane. However, HR's viability still depends on both the quality of the routes HR provides and the overhead incurred at the forwarding plane due to HR's sub-optimal behavior. We designed a new forwarding strategy called Adaptive Smoothed RTT-based Forwarding (ASF) to mitigate HR's sub-optimal path selection. This paper describes our experimental investigation into the packet delivery delay and overhead under HR as compared with Named-Data Link State Routing (NLSR), which calculates shortest paths. We run emulation experiments using va...

  20. Learning packets in nursing education: reviving the past.

    Science.gov (United States)

    Xu, Yin; Martin, Madeleine; Gribbins, Ashley

    2010-05-01

    Learning packets gained popularity in nursing education in the 1960's. Recently, they have been cited as strategies for distance learning. The aim of this project was to integrate Topic Focused Learning Packets as a complementary teaching strategy for presentation of new content to large classes of undergraduate nursing students. In addition to reducing in-class content presentation time, goals included: fostering critical thinking, actively engaging the student, and providing opportunities for team-based interaction. Rationale, design process and packets will be described. The learning packet was viewed positively by the students and faculty. Among 134 students, 119 strongly agreed or agreed that the learning packet was effective in increasing their understanding of the content and achieving the course objectives. Copyright 2009 Elsevier Ltd. All rights reserved.

  1. Packet Classification using Support Vector Machines with String Kernels

    Directory of Open Access Journals (Sweden)

    Sarthak Munshi

    2016-08-01

    Full Text Available Since the inception of internet many methods have been devised to keep untrusted and malicious packets away from a user’s system . The traffic / packet classification can be used as an important tool to detect intrusion in the system. Using Machine Learning as an efficient statistical based approach for classifying packets is a novel method in practice today . This paper emphasizes upon using an advanced string kernel method within a support vector machine to classify packets .There exists a paper related to a similar problem using Machine Learning [2]. But the researches mentioned in their paper are not up-to date and doesn’t account for modern day string kernels that are much more efficient . My work extends their research by introducing different approaches to classify encrypted / unencrypted traffic / packets .

  2. Rotating Gaussian wave packets in weak external potentials

    Science.gov (United States)

    Goussev, Arseni

    2017-07-01

    We address the time evolution of two- and three-dimensional nonrelativistic Gaussian wave packets in the presence of a weak external potential of arbitrary functional form. The focus of our study is the phenomenon of rotation of a Gaussian wave packet around its center of mass, as quantified by mean angular momentum computed relative to the wave-packet center. Using a semiclassical approximation of the eikonal type, we derive an explicit formula for a time-dependent change of mean angular momentum of a wave packet induced by its interaction with a weak external potential. As an example, we apply our analytical approach to the scenario of a two-dimensional quantum particle crossing a tilted ridge potential barrier. In particular, we demonstrate that the initial orientation of the particle wave packet determines the sense of its rotation, and report a good agreement between analytical and numerical results.

  3. Poisson Packet Traffic Generation Based on Empirical Data

    Directory of Open Access Journals (Sweden)

    Andrej Kos

    2003-10-01

    Full Text Available An algorithm for generating equivalent Poisson packet traffic based on empirical traffic data is presented in this paper. Two steps are required in order to produce equivalent Poisson packet traffic. Real traffic trace is analyzed in the first step. In the second step, a new equivalent synthetic Poisson traffic is generated in such a way that the first order statistical parameters remain unchanged. New packet inter-arrival time series are produced in a random manner using negative exponential probability distribution with a known mean. New packet size series are also produced in a random manner. However, due to specified minimum and maximum packet sizes, a truncated exponential probability distribution is applied.

  4. Packet throughput performance of multiservice, multirate OCDMA in elastic networks

    DEFF Research Database (Denmark)

    Raddo, Thiago R.; Sanches, Anderson L.; Tafur Monroy, Idelfonso

    2016-01-01

    of both multirate techniques is proposed. The proposed formalism can be successfully applied for performance evaluation of any arbitrary number of user classes in the system as well as for both 1-D and 2-D codes. The bit error rate (BER) and packet correct probability expressions are derived considering......In this paper, the packet throughput performance of multiservice, multirate optical code-division multiple-access (OCDMA) networks is addressed based on two distinct multirate techniques, namely multilength code and multicode. A new analytical formalism to evaluate the packet throughput performance...... the multiple-access interference (MAI) as binomially distributed. The packet throughput expression, by its turn, is derived considering a Poisson distribution for the composite packet arrivals. Numerical results show that the multicode technique is a good candidate for future multiservice, multirate OCDMA...

  5. Scheduling Issues in ECOFRAME Optical Packet Switched Ring

    Directory of Open Access Journals (Sweden)

    P. Gravey

    2011-06-01

    Full Text Available In the metropolitan area, traditional SONET/SDH circuit switched rings are likely to be replaced with optical packet/burst switching technologies. In this paper we consider a slotted WDM optical packet ring operating without resource reservation mechanisms. In such rings, optical packets in transit have priority over traffic to be inserted by the node. Packets to be inserted are thus queued according to their destination, in order to avoid headof-line blocking. We focus on scheduling policies and compare several MaxWeight scheduling policies, including Oldest Packet First (OPF which emulates FIFO queueing while avoiding head-of-line blocking. We show that there is a trade-off between implementation complexity and fairness, and identify the Largest Virtual Waiting Time First (LVWTF scheduling policy as presenting both a low complexity and a good fairness performance.

  6. Performance analysis of a scalable optical packet switching architecture

    Science.gov (United States)

    Wu, Ho-Ting; Tuan, Chia-Wei

    2010-10-01

    We carry out the analysis of a scalable switching architecture for all-optical packet switching networks. The underlying switch is based on a 2×2 two-stage multibuffer switched delay-line-based optical switching node. By incorporating an additional bypass line and employing a novel switch control strategy, the optical packet switching node can effectively resolve packet contentions, thus reducing the packet deflection probability substantially. In this work, we develop an exact queueing model from a discrete time Markov chain (DTMC) to evaluate the system performance under bursty, nonbursty, symmetric, and asymmetric traffic conditions. The accurate deflection probability and mean packet delay are obtained from this analytical model. Furthermore, we derive an approximate analysis to calculate the lower bound of deflection probability without the heavy computational complexities incurred by the exact analytical model. Simulation results are performed to confirm the validity of our analytic models.

  7. Image coding based on energy-sorted wavelet packets

    Science.gov (United States)

    Kong, Lin-Wen; Lay, Kuen-Tsair

    1995-04-01

    The discrete wavelet transform performs multiresolution analysis, which effectively decomposes a digital image into components with different degrees of details. In practice, it is usually implemented in the form of filter banks. If the filter banks are cascaded and both the low-pass and the high-pass components are further decomposed, a wavelet packet is obtained. The coefficients of the wavelet packet effectively represent subimages in different resolution levels. In the energy-sorted wavelet- packet decomposition, all subimages in the packet are then sorted according to their energies. The most important subimages, as measured by the energy, are preserved and coded. By investigating the histogram of each subimage, it is found that the pixel values are well modelled by the Laplacian distribution. Therefore, the Laplacian quantization is applied to quantized the subimages. Experimental results show that the image coding scheme based on wavelet packets achieves high compression ratio while preserving satisfactory image quality.

  8. Advanced Radio Resource Management for Multi Antenna Packet Radio Systems

    CERN Document Server

    Nonchev, Stanislav; 10.5121/ijwmn.2010.2201

    2010-01-01

    In this paper, we propose fairness-oriented packet scheduling (PS) schemes with power-efficient control mechanism for future packet radio systems. In general, the radio resource management functionality plays an important role in new OFDMA based networks. The control of the network resource division among the users is performed by packet scheduling functionality based on maximizing cell coverage and capacity satisfying, and certain quality of service requirements. Moreover, multiantenna transmit-receive schemes provide additional flexibility to packet scheduler functionality. In order to mitigate inter-cell and co-channel interference problems in OFDMA cellular networks soft frequency reuse with different power masks patterns is used. Stemming from the earlier enhanced proportional fair scheduler studies for single-input multiple-output (SIMO) and multiple-input multipleoutput (MIMO) systems, we extend the development of efficient packet scheduling algorithms by adding transmit power considerations in the ove...

  9. Wavelet Packet Function Based RAKE/Adaptive Multichannel DFE for a WPMA System over Frequency Selective Rayleigh Fading Channels

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaodong; BI Guangguo

    2001-01-01

    A wavelet packet function based multiple access (WPMA) system is developed in this paper to maximize capacity and improve receiver performance over frequency selective multipath fading channels. To design an efficient receiver that mitigates residual multiple access interference (MAI) and intersymbol interference, while improving received signal-to-interference and noise ratio (SINR) simultaneously on the uplink, a multichannel decision feedback equalizer (DFE) following a wavelet packet function based RAKE receiver is proposed. Simulation results show that, over GSM TU channels the developed receiver performs quite well if the power of each user is perfectly controlled or the space diversity combining (SDC) technique is applied.

  10. Enhanced multi-hop operation using hybrid optoelectronic router with time-to-live-based selective forward error correction.

    Science.gov (United States)

    Nakahara, Tatsushi; Suzaki, Yasumasa; Urata, Ryohei; Segawa, Toru; Ishikawa, Hiroshi; Takahashi, Ryo

    2011-12-12

    Multi-hop operation is demonstrated with a prototype hybrid optoelectronic router for optical packet switched networks. The router is realized by combining key optical/optoelectronic device/sub-system technologies and complementary metal-oxide-semiconductor electronics. Using the hop count monitored via the time-to-live field in the packet label, the optoelectronic buffer of the router performs buffering with forward error correction selectively for packets degraded due to multiple hopping every N hops. Experimental results for 10-Gb/s optical packets confirm that the scheme can expand the number of hops while keeping the bit error rate low without the need for optical 3R regenerators at each node.

  11. "Ms. B changes doctors": using a comic and patient transition packet to engineer patient-oriented clinic handoffs (EPOCH).

    Science.gov (United States)

    Pincavage, Amber T; Lee, Wei Wei; Venable, Laura Ruth; Prochaska, Megan; Staisiunas, Daina D; Beiting, Kimberly J; Czerweic, M K; Oyler, Julie; Vinci, Lisa M; Arora, Vineet M

    2015-02-01

    Few patient-centered interventions exist to improve year-end residency clinic handoffs. Our purpose was to assess the impact of a patient-centered transition packet and comic on clinic handoff outcomes. The study was conducted at an academic medicine residency clinic. Participants were patients undergoing resident clinic handoff 2011-2013 PROGRAM DESCRIPTION: Two months before the 2012 handoff, patients received a "transition packet" incorporating patient-identified solutions (i.e., a new primary care provider (PCP) welcome letter with photo, certificate of recognition, and visit preparation tool). In 2013, a comic was incorporated to stress the importance of follow-up. Patients were interviewed by phone with response rates of 32 % in 2011, 43 % in 2012 and 36 % in 2013. Most patients who were interviewed were aware of the handoff post-packet (95 %). With the comic, more patients recalled receiving the packet (44 % 2012 vs. 64 % 2013, pcomic was associated with increased packet recall and improved follow-up rates.

  12. Backpressure-Based Packet-By-Packet Adaptive Routing For Traffic Management in Communication Networks

    Directory of Open Access Journals (Sweden)

    P. Swetha,

    2014-06-01

    Full Text Available Back pressure-based adaptive routing algorithms where each packet is routed along a possibly different pathhave been extensively studied in the literature. However, suchalgorithms typically result in poor delay performance and involvehigh implementation complexity. In this paper, we develop anew adaptive routing algorithm built upon the widely-studiedback-pressure algorithm. We decouple the routing and schedulingcomponents of the algorithm by designing a probabilistic routingtable which is used to route packets to per-destination queues.The scheduling decisions in the case of wireless networks aremade using counters called shadow queues. The results arealso extended to the case of networks which employ simpleforms of network coding. In that case, our algorithm provides alow-complexity solution to optimally exploit the routing-codingtrade-off.

  13. One Packet Suffices - Highly Efficient Packetized Network Coding With Finite Memory

    CERN Document Server

    Haeupler, Bernhard

    2011-01-01

    Random Linear Network Coding (RLNC) has emerged as a powerful tool for robust high-throughput multicast. Projection analysis - a recently introduced technique - shows that the distributed packetized RLNC protocol achieves (order) optimal and perfectly pipelined information dissemination in many settings. In the original approach to RNLC intermediate nodes code together all available information. This requires intermediate nodes to keep considerable data available for coding. Moreover, it results in a coding complexity that grows linearly with the size of this data. While this has been identified as a problem, approaches that combine queuing theory and network coding have heretofore not provided a succinct representation of the memory needs of network coding at intermediates nodes. This paper shows the surprising result that, in all settings with a continuous stream of data, network coding continues to perform optimally even if only one packet per node is kept in active memory and used for computations. This l...

  14. Dynamic Homeostasis in Packet Switching Networks

    CERN Document Server

    Oka, Mizuki; Ikegami, Takashi

    2014-01-01

    In this study, we investigate the adaptation and robustness of a packet switching network (PSN), the fundamental architecture of the Internet. We claim that the adaptation introduced by a transmission control protocol (TCP) congestion control mechanism is interpretable as the self-organization of multiple attractors and stability to switch from one attractor to another. To discuss this argument quantitatively, we study the adaptation of the Internet by simulating a PSN using ns-2. Our hypothesis is that the robustness and fragility of the Internet can be attributed to the inherent dynamics of the PSN feedback mechanism called the congestion window size, or \\textit{cwnd}. By varying the data input into the PSN system, we investigate the possible self-organization of attractors in cwnd temporal dynamics and discuss the adaptability and robustness of PSNs. The present study provides an example of Ashby's Law of Requisite Variety in action.

  15. Waveform and packet structure of lion roars

    Directory of Open Access Journals (Sweden)

    W. Baumjohann

    Full Text Available The Equator-S magnetometer is very sensitive and has a sampling rate of normally 128 Hz. The high sampling rate allows for the first time fluxgate magnetometer measurements of ELF waves between the ion cyclotron and the lower hybrid frequencies in the equatorial dayside magnetosheath. The so-called lion roars, typically seen by the Equator-S magnetometer at the bottom of the magnetic troughs of magnetosheath mirror waves, are near-monochromatic packets of electron whistler waves lasting for a few wave cycles only, typically 0.25 s. They are right-hand circularly polarized waves with typical amplitudes of 0.5–1 nT at around one tenth of the electron gyrofrequency. The cone angle between wave vector and ambient field is usually smaller than 1.5°.

    Key words. Interplanetary physics (MHD waves and turbulence; plasma waves and turbulence

  16. 面向IP地址集过滤的高效包分类技术%Efficient packet classification technique for IP address set filtering

    Institute of Scientific and Technical Information of China (English)

    乔龙飞; 刘剑英; 郑建生

    2015-01-01

    Traditional network firewall uses a linear package matching algorithm which is very inefficient, and it”s also very difficult to manage complex rules and tables. To improve this, this paper designed and implemented a Netfilter extension framework called Salist ( simple address list) . Salist contains a table management module based on kernel virtual file system, a rule management module that can automatically merge and sort rules in tables and an efficient packet matching module based on Bsearch algorithm. The time complexity of the packet matching algorithm declines to O ( log n ) from O ( n ) . The kernel memory space to store the rules reduces by at lease 10 percent. The management of the rules is much easier because rules are stored in different files in kernel space. The results show that the Salist framework can substantially improve the network packet forwarding speed.%针对传统防火墙线性匹配算法匹配效率低、维护困难等问题,提出并实现了一种面向IP地址集过滤的高效、灵活的Netfilter扩展框架Salist。 Salist包含一个基于内核虚拟文件的表管理模块,一个可自动对IP地址集进行去重、归并和排序的表内规则管理模块,一个基于Bsearch算法的高效的包匹配模块。通过理论分析和实际测试证明, Salist使包匹配算法时间复杂度由传统线性匹配的O( n)降低为O( log n),规则合并减少了规则表占用的内核内存空间10%以上,按文件分离的规则管理机制简化了对规则集进行维护的难度。结果表明Salist使用在核心网络设备中可极大提高包转发速率,降低规则的内存占用和管理难度。

  17. Interconnection between packet switching national networks and local packet radio communication networks

    Science.gov (United States)

    Talone, P.; Trigila, S.

    1985-07-01

    Multipoint topology networks based on a single statistically distributed radiocommunication channel are considered, referring only to restricted area networks with line of sight type links. The architecture and protocols of such networks are reviewed. The problems related to the interconnection of such networks with large public packet switching communication networks are examined. Several hypothesis are studied concluding that mainly in the case of emergencies or catastrophic events these networks are an extremely useful resource.

  18. Low-loss optical packet synchronization architecture

    Science.gov (United States)

    Franzen, Andre; Hunter, David K.; Andonovic, Ivan

    1998-10-01

    A novel synchronization architecture is presented for packet based optical networks, exhibiting low insertion loss and reduced crosstalk, taking advantage of the characteristics of AWG (arrayed waveguide grating) filters. Thus far, only logarithmic delay lines have been investigated rigorously, the generic structures either based on 2 X 2 switches or on a 1-to-m splitter combined with semiconductor optical amplifier gates. The first scheme introduces not only high loss but also crosstalk, producing a high amount of interferometric noise. The latter has a lot of splitting loss to accommodate but overall, fewer stages are necessary to achieve the same delay as more than two paths per stage can be set up. In this paper, AWGs in combination with wavelength converters replace the splitter/SOA-gate geometry minimizing the optical loss, ensuring that higher levels of optical power remain to traverse the adjacent switching matrix. This novel set-up ensures that only low levels of amplification are needed minimizing concomitant noise accumulation. An incoming cell or data stream will be converted to a distinct wavelength determined by an evaluation circuit in the electronic domain. The chosen wavelength maps the input to a length of fiber which in turn represents the necessary delay, effectively executing path length (and hence time alignment) equalization of different incoming packets. Once the wavelength conversion is executed the cell is fed into an AWG, governed by a `hardwired' translation-table (input/output), ensuring cells propagate to the correct output. Finer delays are realized by cascading the principle stage.

  19. Balancing forward and feedback error correction for erasure channels with unreliable feedback

    CERN Document Server

    Sahai, Anant

    2007-01-01

    The traditional information theoretic approach to studying feedback is to consider ideal instantaneous high-rate feedback of the channel outputs to the encoder. This was acceptable in classical work because the results were negative: Shannon pointed out that even perfect feedback often does not improve capacity and in the context of symmetric DMCs, Dobrushin showed that it does not improve the fixed block-coding error exponents in the interesting high rate regime. However, it has recently been shown that perfect feedback does allow great improvements in the asymptotic tradeoff between end-to-end delay and probability of error, even for symmetric channels at high rate. Since gains are claimed with ideal instantaneous feedback, it is natural to wonder whether these improvements remain if the feedback is unreliable or otherwise limited. Here, packet-erasure channels are considered on both the forward and feedback links. First, the feedback channel is considered as a given and a strategy is given to balance forwa...

  20. Three-dimensional electromagnetic strong turbulence. II. Wave packet collapse and structure of wave packets during strong turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Graham, D. B.; Robinson, P. A.; Cairns, Iver H. [School of Physics, University of Sydney, New South Wales 2006 (Australia); Skjaeraasen, O. [ProsTek, Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway)

    2011-07-15

    Large-scale simulations of wave packet collapse are performed by numerically solving the three-dimensional (3D) electromagnetic Zakharov equations, focusing on individual wave packet collapses and on wave packets that form in continuously driven strong turbulence. The collapse threshold is shown to decrease as the electron thermal speed {nu}{sub e}/c increases and as the temperature ratio T{sub i}/T{sub e} of ions to electrons decreases. Energy lost during wave packet collapse and dissipation is shown to depend on {nu}{sub e}/c. The dynamics of density perturbations after collapse are studied in 3D electromagnetic strong turbulence for a range of T{sub i}/T{sub e}. The structures of the Langmuir, transverse, and total electric field components of wave packets during strong turbulence are investigated over a range of {nu}{sub e}/c. For {nu}{sub e}/c < or approx. 0.17, strong turbulence is approximately electrostatic and wave packets have very similar structure to purely electrostatic wave packets. For {nu}{sub e}/c > or approx. 0.17, transverse modes become trapped in density wells and contribute significantly to the structure of the total electric field. At all {nu}{sub e}/c, the Langmuir energy density contours of wave packets are predominantly oblate (pancake shaped). The transverse energy density contours of wave packets are predominantly prolate (sausage shaped), with the major axis being perpendicular to the major axes of the Langmuir component. This results in the wave packet becoming more nearly spherical as {nu}{sub e}/c increases, and in turn generates more spherical density wells during collapse. The results obtained are compared with previous 3D electrostatic results and 2D electromagnetic results.

  1. Destination directed packet switch architecture for a geostationary communication satellite network

    Science.gov (United States)

    Ivancic, W. D.; Shalkhauser, M. J.; Bobinsky, E. A.; Soni, N. J.; Quintana, J. A.; Kim, H.; Wagner, P.; Vanderaar, M.

    1992-01-01

    A major effort at NASA/Lewis is to identify and develop critical digital technologies and components that enable new commercial missions or significantly improve the performance, cost efficiency, and/or reliability of existing and planned space comunications systems. NASA envisions the need for low data rate, direct to the user communications services, for data, facsimile, voice, and video conferencing. A report that focuses on destination directed packet switching architectures for geostationary communication satellites is presented.

  2. Destination directed packet switch architecture for a geostationary communication satellite network

    Science.gov (United States)

    Ivancic, W. D.; Shalkhauser, M. J.; Bobinsky, E. A.; Soni, N. J.; Quintana, J. A.; Kim, H.; Wagner, P.; Vanderaar, M.

    1992-08-01

    A major effort at NASA/Lewis is to identify and develop critical digital technologies and components that enable new commercial missions or significantly improve the performance, cost efficiency, and/or reliability of existing and planned space comunications systems. NASA envisions the need for low data rate, direct to the user communications services, for data, facsimile, voice, and video conferencing. A report that focuses on destination directed packet switching architectures for geostationary communication satellites is presented.

  3. Novel Adaptive Beamforming Algorithm Based on Wavelet Packet Transform

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiaofei; Xu Dazhuan

    2005-01-01

    An analysis of the received signal of array antennas shows that the received signal has multi-resolution characteristics, and hence the wavelet packet theory can be used to detect the signal. By emplying wavelet packet theory to adaptive beamforming, a wavelet packet transform-based adaptive beamforming algorithm (WP-ABF) is proposed . This WP-ABF algorithm uses wavelet packet transform as the preprocessing, and the wavelet packet transformed signal uses least mean square algorithm to implement the adaptive beamforming. White noise can be wiped off under wavelet packet transform according to the different characteristics of signal and white under the wavelet packet transform. Theoretical analysis and simulations demonstrate that the proposed WP-ABF algorithm converges faster than the conventional adaptive beamforming algorithm and the wavelet transform-based beamforming algorithm. Simulation results also reveal that the convergence of the algorithm relates closely to the wavelet base and series; that is, the algorithm convergence gets better with the increasing of series, and for the same series of wavelet base the convergence gets better with the increasing of regularity.

  4. Research on Improving Machining Precision of CNC Machine Based on Velocity Feed-forward of FANUC System%基于FANUC系统速度前馈提高CNC机床加工精度的研究

    Institute of Scientific and Technical Information of China (English)

    刘萍; 王民权; 王劲

    2013-01-01

    CNC servo system has time delay in machine process of high-speed and high-precision which would cause form error because of deviation between instruction and real trajectory. Feed-forward control was introduced into servo system of CNC machine. Through theoretical analysis, it is shown that the form error can be effectively reduced by adopting proper feed-forward controller. CNC machine test results show; by adjusting the speed feed-forward coefficient, the speed loop gain can be improved, the form error due to changing acceleration is reduced, so surface quality and form precision are increased. Further the precision of CNC machine tools is improved.%针对高速高精加工过程中,因数控伺服系统时滞而导致的指令轨迹与实际轨迹存在偏差、进而导致形状误差的问题,将前馈控制引入数控机床伺服系统.通过理论分析可知:选用适当的前馈控制器,可以有效减小形状误差.数控机床测试结果表明:通过调整速度前馈系数,可以提高速度环的增益,从而减小因加速度变化引起的形状误差,改善表面精度和加工形状精度,进而提高CNC机床的加工精度.

  5. An On-Demand Emergency Packet Transmission Scheme for Wireless Body Area Networks

    Directory of Open Access Journals (Sweden)

    Moshaddique Al Ameen

    2015-12-01

    Full Text Available The rapid developments of sensor devices that can actively monitor human activities have given rise to a new field called wireless body area network (BAN. A BAN can manage devices in, on and around the human body. Major requirements of such a network are energy efficiency, long lifetime, low delay, security, etc. Traffic in a BAN can be scheduled (normal or event-driven (emergency. Traditional media access control (MAC protocols use duty cycling to improve performance. A sleep-wake up cycle is employed to save energy. However, this mechanism lacks features to handle emergency traffic in a prompt and immediate manner. To deliver an emergency packet, a node has to wait until the receiver is awake. It also suffers from overheads, such as idle listening, overhearing and control packet handshakes. An external radio-triggered wake up mechanism is proposed to handle prompt communication. It can reduce the overheads and improve the performance through an on-demand scheme. In this work, we present a simple-to-implement on-demand packet transmission scheme by taking into considerations the requirements of a BAN. The major concern is handling the event-based emergency traffic. The performance analysis of the proposed scheme is presented. The results showed significant improvements in the overall performance of a BAN compared to state-of-the-art protocols in terms of energy consumption, delay and lifetime.

  6. An On-Demand Emergency Packet Transmission Scheme for Wireless Body Area Networks.

    Science.gov (United States)

    Al Ameen, Moshaddique; Hong, Choong Seon

    2015-12-04

    The rapid developments of sensor devices that can actively monitor human activities have given rise to a new field called wireless body area network (BAN). A BAN can manage devices in, on and around the human body. Major requirements of such a network are energy efficiency, long lifetime, low delay, security, etc. Traffic in a BAN can be scheduled (normal) or event-driven (emergency). Traditional media access control (MAC) protocols use duty cycling to improve performance. A sleep-wake up cycle is employed to save energy. However, this mechanism lacks features to handle emergency traffic in a prompt and immediate manner. To deliver an emergency packet, a node has to wait until the receiver is awake. It also suffers from overheads, such as idle listening, overhearing and control packet handshakes. An external radio-triggered wake up mechanism is proposed to handle prompt communication. It can reduce the overheads and improve the performance through an on-demand scheme. In this work, we present a simple-to-implement on-demand packet transmission scheme by taking into considerations the requirements of a BAN. The major concern is handling the event-based emergency traffic. The performance analysis of the proposed scheme is presented. The results showed significant improvements in the overall performance of a BAN compared to state-of-the-art protocols in terms of energy consumption, delay and lifetime.

  7. A Model for Video Quality Assessment Considering Packet Loss for Broadcast Digital Television Coded in H.264

    Directory of Open Access Journals (Sweden)

    Jose Joskowicz

    2014-01-01

    Full Text Available This paper presents a model to predict video quality perceived by the broadcast digital television (DTV viewer. We present how noise on DTV can introduce individual transport stream (TS packet losses at the receiver. The type of these errors is different than the produced on IP networks. Different scenarios of TS packet loss are analyzed, including uniform and burst distributions. The results show that there is a high variability on the perceived quality for a given percentage of packet loss and type of error. This implies that there is practically no correlation between the type of error or the percentage of packets loss and the perceived degradation. A new metric is introduced, the weighted percentage of slice loss, which takes into account the affected slice type in each lost TS packet. We show that this metric is correlated with the video quality degradation. A novel parametric model for video quality estimation is proposed, designed, and verified based on the results of subjective tests in SD and HD. The results were compared to a standard model used in IP transmission scenarios. The proposed model improves Pearson Correlation and root mean square error between the subjective and the predicted MOS.

  8. Robust transmission of packet-based H.264/AVC video with data partitioning over DS-CDMA wireless channels

    Science.gov (United States)

    Mantravadi, Anand V. S.; Bansal, Manu; Kondi, Lisimachos P.

    2006-01-01

    In this paper, we address the problem of robust transmission of packet based H.264/AVC video over direct sequence-code division multiple access (DS-CDMA) channels. H.264 based data partitioning is used to produce video packets of unequal importance with regards to their need in terms of the decoded video quality. In the proposed transmission system, the data partitioned video packets are packetized as per IP/UDP/RTP protocol stack and are sorted into different levels for giving unequal error protection (UEP) using Rate Compatible Punctured Convolutional (RCPC) codes. Constant size framing is done at the link layer and Cyclic Redundancy Check header (CRC) is attached for error detection. Link layer buffering and packet interleaving schemes are proposed to improve the efficiency of the system. A multipath Rayleigh fading channel with Additive White Gaussian Noise (AWGN) and interference from other users is considered at the physical layer. The link layer frames are channel encoded, spread and transmitted over the channel. The received data is despread/demodulated using the Auxiliary Vector (AV) filter or RAKE matched filter (RAKE-MF) receiver and subsequently channel and source decoded. Our experimental results show the effectiveness of using data partitioning for wireless transmissions when compared to the system not using data partitioning. Also the superior interference mitigation capabilities of AV receiver is shown in comparison to the RAKE-MF receiver.

  9. Research on Performance between IP and Vector Forwarding

    Directory of Open Access Journals (Sweden)

    Aqun Zhao

    2013-03-01

    Full Text Available With the rapid development of network size and great increase of Internet traffic, it has become a crucial work to improve the forwarding performance of the core devices of Internet or the routers. In this study, the analysis and comparison of instruction cycles occupied by the machine in the process of route lookup in IP forwarding and vector forwarding were carried out which may determine the forwarding performance of a router. The simulation experiments were also made to study the forwarding efficiency of IP forwarding and vector forwarding. The theoretical and experimental results prove that the vector forwarding method is more efficient than IP forwarding which can provide powerful evidence to the application of vector network in the Internet.

  10. Analysis of circular wave packets generated by pulsed electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, S., E-mail: shuhei@concord.itp.tuwien.ac.at [Institute for Theoretical Physics, Vienna University of Technology, Vienna (Austria); Reinhold, C.O. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6372 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Burgdoerfer, J. [Institute for Theoretical Physics, Vienna University of Technology, Vienna (Austria); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Wyker, B.; Ye, S.; Dunning, F.B. [Department of Physics and Astronomy and the Rice Quantum Institute, Rice University, Houston, TX 77005-1892 (United States)

    2012-05-15

    We demonstrate that circular wave packets in high Rydberg states generated by a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wave packets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficients.

  11. Lost Audio Packets Steganography: The First Practical Evaluation

    CERN Document Server

    Mazurczyk, Wojciech

    2011-01-01

    This paper presents first experimental results for an IP telephony-based steganographic method called LACK (Lost Audio PaCKets steganography). This method utilizes the fact that in typical multimedia communication protocols like RTP (Real-Time Transport Protocol), excessively delayed packets are not used for the reconstruction of transmitted data at the receiver, i.e. these packets are considered useless and discarded. The results presented in this paper were obtained basing on a functional LACK prototype and show the method's impact on the quality of voice transmission. Achievable steganographic bandwidth for the different IP telephony codecs is also calculated.

  12. Architectures of electro-optical packet switched networks

    DEFF Research Database (Denmark)

    Berger, Michael Stubert

    2004-01-01

    and examines possible architectures for future high capacity networks with high capacity nodes. It is assumed that optics will play a key role in this scenario, and in this respect, the European IST research project DAVID aimed at proposing viable architectures for optical packet switching, exploiting the best......, Constraint Based Routing is examined, and the effect from taking the link load into account is evaluated. It is believed that electrical packet switching will satisfy demands in the coming years, and this work covers several aspects hereof. A new load balancing scheme for multipath packet switches...

  13. SDRAM-based packet buffer model for high speed switches

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Ruepp, Sarah Renée; Berger, Michael Stübert

    2011-01-01

    This article investigates the how the performance of SDRAM based packet buffering systems for high performance switches can be simulated using OPNET. In order to include the access pattern dependent performance of SDRAM modules in simulations, a custom SDRAM model is implemented in OPNET Modeller...... based on the specifications of a real-life DDR3-SDRAM chip. Based on this model the performance of different schemes for optimizing the performance of such a packet buffer can be evaluated. The purpose of this study is to find efficient schemes for memory mapping of the packet queues and I/O traffic...

  14. IP Lookup as a Critical Functionality of Packet Processors

    Directory of Open Access Journals (Sweden)

    Z. G. Čiča

    2013-06-01

    Full Text Available Packet processing represents the most significant part of a router’s data plane and has a large impact on router’s scalability. Packet processing consists of many functions and some of them can become critical for the future router’s scalability. In this paper, the IP lookup as one of the most critical packet processing functions is analyzed to determine its impact on the Internet router’s scalability. Also, in this paper we propose a new modification of our previously proposed IP lookup algorithm BPFL.

  15. A channel distortion model for video over lossy packet networks

    Institute of Scientific and Technical Information of China (English)

    CHENG Jian-xin; GAO Zhen-ming; ZHANG Zhi-chao

    2006-01-01

    Error-resilient video communication over lossy packet networks is often designed and operated based on models for the effect of losses on the reconstructed video quality. This paper analyzes the channel distortion for video over lossy packet networks and proposes a new model that, compared to previous models, more accurately estimates the expected mean-squared error distortion for different packet loss patterns by accounting for inter-frame error propagation and the correlation between error frames. The accuracy of the proposed model is validated with JVT/H.264 encoded standard test sequences and previous frame concealment, where the proposed model provides an obvious accuracy gain over previous models.

  16. FIFO Queueing Policies for Packets with Heterogeneous Processing

    CERN Document Server

    Kogan, Kirill; Nikolenko, Sergey I; Sirotkin, Alexander V; Tugaryov, Denis

    2012-01-01

    We consider the problem of managing a bounded size First-In-First-Out (FIFO) queue buffer, where each incoming unit-sized packet requires several rounds of processing before it can be transmitted out. Our objective is to maximize the total number of successfully transmitted packets. We consider both push-out (when the policy is permitted to drop already admitted packets) and non-push-out cases. In particular, we provide analytical guarantees for the throughput performance of our algorithms. We further conduct a comprehensive simulation study which experimentally validates the predicted theoretical behaviour.

  17. Research on performance of multicasting in optical packet switched networks

    Institute of Scientific and Technical Information of China (English)

    Xin Liu; Yuefeng Ji; Lin Bai; Hongxiang Wang; Yongmei Sun

    2009-01-01

    @@ Different multicasting schemes in optical packet switched networks are discussed, including the parallel mode, serial mode, and hybrid mode multicasting schemes.Simulated modeling technique is applied to compare the network-level performance of the three multicasting schemes.A conclusion can be drawn from the results that since the hybrid-mode multicasting scheme can increase the multicast success ratio and reduce the packet retransmission times compared with the other two schemes, it is the best choice for delivering multicasting sessions in the optical packet switched networks.

  18. Moving forward in fall prevention: an intervention to improve balance among patients in a quasi-experimental study of hospitalized patients.

    Science.gov (United States)

    Villafañe, Jorge H; Pirali, Caterina; Buraschi, Riccardo; Arienti, Chiara; Corbellini, Camilo; Negrini, Stefano

    2015-12-01

    We investigated the effectiveness of three different rehabilitative programs: group exercise, individual core stability or balance training intervention with a stabilometric platform to improve balance ability in elderly hospitalized patients. We used a prospective quasi-experimental study design. Twenty-eight patients, 39.3% women [age (mean±SD) 72.4±6.5 years], known to have had at least a fall in the last 12 months, were consecutively assigned to one of the following three groups: group exercise intervention, individual core stability or balance training with a stabilometric platform (five sessions a week for 3 weeks in each group). Outcomes were collected at baseline and immediately following the intervention period. In each intervention group, patients showed improvement in balance and mobility, shown as an improvement in the three functional tests score (the Tinetti scale, the Berg Balance Scale, and the Time Up and Go test) (all, PStability Test and Fall Risk Test) were not significant for all the interventions. No significant group-by-time interaction was detected for any of the intervention groups, which suggests that the groups improved in the same way. These findings indicate that participation in an exercise program can improve balance and functional mobility, which might contribute toward the reductions of the falls of elderly hospitalized patients and the subsequent fall-related costs. Functional scales might be more appropriate than an instrumental test (Postural Stability Test and Fall Risk Test of the Biodex Balance System) in detecting the functional improvement because of a rehabilitative intervention.

  19. Comparison of AFITPAC versus NOS and a packet radio network design

    Science.gov (United States)

    Iannelli, Thomas A.

    1991-12-01

    This thesis encompasses two themes: (1) A comparison of the Network Operating System (NOS) software package, developed by Phil Karn and others, and AFITPAC, written by Marsh and Geier at the Air Force Institute of Technology. The comparison is based on the Air Force Logistics Command's requirements for the development of a Packet Radio Network program. The results of the comparison are a recommendation that use of the NOS package be pursued because it can meet all twelve of the requirements and compiles with five of the Military Standard Protocols. (2) The design of a personal computer Packet Radio Network Simulator used to analyze the network performance of AFITPAC and NOS is proposed. The proposal concludes with a discussion of problems in development of the simulation which used MODSIM IITM, C++, and a 80386/25Mhz personal computer. Recommendations are made for pursuing the simulation effort on other hardware platforms and for improvements to the design.

  20. A New Iterated Local Search Algorithm for Solving Broadcast Scheduling Problems in Packet Radio Networks

    Directory of Open Access Journals (Sweden)

    Chih-Chiang Lin

    2010-01-01

    Full Text Available The broadcast scheduling problem (BSP in packet radio networks is a well-known NP-complete combinatorial optimization problem. The broadcast scheduling avoids packet collisions by allowing only one node transmission in each collision domain of a time division multiple access (TDMA network. It also improves the transmission utilization by assigning one transmission time slot to one or more nodes; thus, each node transmits at least once in each time frame. An optimum transmission schedule could minimize the length of a time frame while minimizing the number of idle nodes. In this paper, we propose a new iterated local search (ILS algorithm that consists of two special perturbation and local search operators to solve the BSPs. Computational experiments are applied to benchmark data sets and randomly generated problem instances. The experimental results show that our ILS approach is effective in solving the problems with only a few runtimes, even for very large networks with 2,500 nodes.

  1. Review on buffer management schemes for packet queues in wired & wireless network

    Directory of Open Access Journals (Sweden)

    Shaheen C. Pathan,

    2015-08-01

    Full Text Available Mobile AdHoc Network (MANET is a wireless network with a set of mobile nodes that can communicate with each other with no access point and without any fixed infrastructure. But mobile devices usually have limited resources (battery power, memory, CPU which limit their transmission range. Hence, in order to conserve the limited resource, it is highly desirable that transmission should be as efficient as possible. MANET can be implemented in any environment because of its dynamic nature. For routing of information packets queuing is done at the buffer and transferred through intermediate nodes to the destination on priority basis which help to improve the overall network performance. This paper provides a review of various buffer management schemes for packet queues in wired & wireless networks (specialy MANET.

  2. Enhancement of Non-Air Conducted Speech Based on Wavelet-Packet Adaptive Threshold

    Directory of Open Access Journals (Sweden)

    Xijing Jing

    2013-01-01

    Full Text Available This study developed a new kind of speech detecting method by using millimeter wave. Because of the advantage of the millimeter wave, this speech detecting method has great potential application and may provide some exciting possibility for wide applications. However, the MMW conduct speech is in less intelligible and poor audibility since it is corrupted by additive combined noise. This paper, therefore, also developed an algorithm of wavelet packet threshold by using hard threshold and soft threshold for removing noise based on the good capability of wavelet packet for analyzing time-frequency signal. Comparing to traditional speech enhancement algorithm, the results from both simulation and listening evaluation suggest that the proposed algorithm takes on a better performance on noise removing while the distortion of MMW radar speech remains acceptable, the enhanced speech also sounds more pleasant to human listeners, resulting in improved results over classical speech enhancement algorithms.

  3. A ttack analysis and improvement on the signcryption scheme with public verifiability and forward security%公开验证和前向安全数字签密方案的分析与改进

    Institute of Scientific and Technical Information of China (English)

    周克元

    2015-01-01

    T he signcryption scheme proposed by Zhang Jian‐hang et al is analyzed , and the scheme don’t have the forward security . An improvement scheme is proposed with public verifiability and forward security , the correctness and security are proved . The efficiency of the scheme is increased significantly compared with two existing schemes . Moreover , a new signcryption scheme based on elliptic curves is proposed with public verifiability and forward security . In the algorithm , both the numbers of model multiplication and model inverse are reached the minimum four times and zero times , the efficiency of the algorithm is increased significantly compared with the existing signcryption scheme .%指出张建航等提出的数字签密方案无前向安全性,提出了一个新的可公开验证和前向安全的数字签密方案,并进行了正确性和安全性分析,与已有方案比较,降低了算法复杂度。同时,指出张建航等提出的椭圆曲线数字签密方案复杂度过高,给出了一个新的签密方案,方案具有前向安全性和公开验证性,模乘运算达到最小值4次,模逆运算达到最小值0次,复杂度达到理论最小值。

  4. Massachusetts Bay - Internal wave packets digitized from SAR imagery

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery at 1:350,000 scale in Massachusetts Bay. Internal waves are nonsinusoidal waves that...

  5. Neutrino Oscillations in Intermediate States.II -- Wave Packets

    CERN Document Server

    Asahara, A; Shimomura, T; Yabuki, T

    2004-01-01

    We analyze oscillations of intermediate neutrinos in terms of scattering of particles described by Gaussian wave packets. We study a scalar model as in the previous paper (I) but in realistic situations, where two particles of the initial state and final state are wave packets and neutrinos are in the intermediate state. The oscillation of the intermediate neutrino is found from the time evolution of the total transition probability between the initial state and final state. The effect of a finite lifetime and a finite relaxation time $\\tau$ are also studied. We find that the oscillation pattern depends on the magnitude of wave packet sizes of particles in the initial state and final state and the lifetime of the initial particle. For $\\Delta m^2=10^{-2}$ eV$^2$, the oscillation probability deviates from the standard formula, if the wave packet sizes are around $10^{-13}$ m for 0.4 MeV neutrino.

  6. IMPLEMENTATION OF LABVIEW BASED PACKET LOGGER FOR ZIGBEE NETWORK

    Directory of Open Access Journals (Sweden)

    B. UDAYA KUMAR,

    2010-08-01

    Full Text Available ZigBee is a wireless technology being deployed for wireless sensor networks. Low data rate personal area network applications like smart home automation, greenhouse monitoring and healthcare use ZigBee, a high level communication protocol as a standard to acquire the data. The data from the sensor nodes are monitored and logged using packet sniffer. The available sniffers in the market need additional hardware with dedicated software which costs more. Also the packet sniffer has to be compatible with the sensor node hardware. In this paper, sniffing of packets at the base station is implemented using LabView. With Texas Instruments Z-Accel Modules, a tree topology is established and temperature is monitored, logged with time stamping and packet data analysis is presented.

  7. Stabilization of Networked Control System with Packet-Dropout

    Directory of Open Access Journals (Sweden)

    Hooman Sanatizadeh

    2014-10-01

    Secondly, by above method an inverted pendulum which was controlled in a network with delays, is controlled in a network through packet-dropouts. simulation results show the effectiveness of the above method.

  8. Resonance-Assisted Decay of Nondispersive Wave Packets

    OpenAIRE

    Wimberger, S.; Schlagheck, P.; Eltschka, C.; Buchleitner, A.

    2006-01-01

    We present a quantitative semiclassical theory for the decay of nondispersive electronic wave packets in driven, ionizing Rydberg systems. Statistically robust quantities are extracted combining resonance assisted tunneling with subsequent transport across chaotic phase space and a final ionization step.

  9. [Monte Vista National Wildlife Refuge livestock grazing lawsuit : Information packet

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Packet of information from the Colorado Cattlemen's Association concerning the 1992 lawsuit filed against the Monte Vista National Wildlife Refuge. The suit was...

  10. Value of Optical Bypass in Packet Ring Networks

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This paper firstly examines the value of optical bypass scheme in packet ring networks. An Integer Linear Program (ILP) formulation is presented and analytical results under different traffic patterns are given.

  11. Some Results on the Wavelet Packet Decomposition of Nonstationary Processes

    Directory of Open Access Journals (Sweden)

    Touati Sami

    2002-01-01

    Full Text Available Wavelet/wavelet packet decomposition has become a very useful tool in describing nonstationary processes. Important examples of nonstationary processes encountered in practice are cyclostationary processes or almost-cyclostationary processes. In this paper, we study the statistical properties of the wavelet packet decomposition of a large class of nonstationary processes, including in particular cyclostationary and almost-cyclostationary processes. We first investigate in a general framework, the existence and some properties of the cumulants of wavelet packet coefficients. We then study more precisely the almost-cyclostationary case, and determine the asymptotic distributions of wavelet packet coefficients. Finally, we particularize some of our results in the cyclostationary case before providing some illustrative simulations.

  12. A Novel Algorithm for Efficient Downlink Packet Scheduling for Multiple-Component-Carrier Cellular Systems

    Directory of Open Access Journals (Sweden)

    Yao-Liang Chung

    2016-11-01

    Full Text Available The simultaneous aggregation of multiple component carriers (CCs for use by a base station constitutes one of the more promising strategies for providing substantially enhanced bandwidths for packet transmissions in 4th and 5th generation cellular systems. To the best of our knowledge, however, few previous studies have undertaken a thorough investigation of various performance aspects of the use of a simple yet effective packet scheduling algorithm in which multiple CCs are aggregated for transmission in such systems. Consequently, the present study presents an efficient packet scheduling algorithm designed on the basis of the proportional fair criterion for use in multiple-CC systems for downlink transmission. The proposed algorithm includes a focus on providing simultaneous transmission support for both real-time (RT and non-RT traffic. This algorithm can, when applied with sufficiently efficient designs, provide adequate utilization of spectrum resources for the purposes of transmissions, while also improving energy efficiency to some extent. According to simulation results, the performance of the proposed algorithm in terms of system throughput, mean delay, and fairness constitute substantial improvements over those of an algorithm in which the CCs are used independently instead of being aggregated.

  13. Analysis of Transmissions Scheduling with Packet Fragmentation

    Directory of Open Access Journals (Sweden)

    Nir Menakerman

    2001-12-01

    Full Text Available We investigate a scheduling problem in which packets, or datagrams, may be fragmented. While there are a few applications to scheduling with datagram fragmentation, our model of the problem is derived from a scheduling problem present in data over CATV networks. In the scheduling problem datagrams of variable lengths must be assigned (packed into fixed length time slots. One of the capabilities of the system is the ability to break a datagram into several fragments. When a datagram is fragmented, extra bits are added to the original datagram to enable the reassembly of all the fragments. We convert the scheduling problem into the problem of bin packing with item fragmentation, which we define in the following way: we are asked to pack a list of items into a minimum number of unit capacity bins. Each item may be fragmented in which case overhead units are added to the size of every fragment. The cost associated with fragmentation renders the problem NP-hard, therefore an approximation algorithm is needed. We define a version of the well-known Next-Fit algorithm, capable of fragmenting items, and investigate its performance. We present both worst case and average case results and compare them to the case where fragmentation is not allowed.

  14. Packet QoS level classifier based on optical binary priority comparison.

    Science.gov (United States)

    Song, Seoksu; Nguyen, Vancanh; Park, Jinwoo

    2010-07-19

    Next generation High-Speed optical packet switching networks require components capable of classifying incoming packet into the appropriate priority queue according to the service class of the packet. For the first time, we proposed an all-optical packet QoS (Quality of Service) level classifier employing a sequential binary packet priority comparator, which is implemented using the SOA-based optical logic gates. The performance of the optical binary packet priority comparator was verified experimentally at 1 Gbit/s showing that the proposed scheme can operate higher data rates. These packet level classifier structures are attractive for all-optical network and applications.

  15. Wave packet dynamics of potassium dimers attached to helium nanodroplets

    OpenAIRE

    Claas, P.; Droppelmann, G.; Schulz, C. P.; Mudrich, M.; Stienkemeier, F.

    2006-01-01

    The dynamics of vibrational wave packets excited in K$_2$ dimers attached to superfluid helium nanodroplets is investigated by means of femtosecond pump-probe spectroscopy. The employed resonant three-photon-ionization scheme is studied in a wide wavelength range and different pathways leading to K$^+_2$-formation are identified. While the wave packet dynamics of the electronic ground state is not influenced by the helium environment, perturbations of the electronically excited states are obs...

  16. Bandwidth and Detection of Packet Length Covert Channels

    Science.gov (United States)

    2011-03-01

    hidden or covert information. This contrasts with methods like steganography , which refers to hiding information in content [4]. In this thesis, we...series of packets. Nair then used a technique that has been applied in steganography of images to compare the normal packet length vector to a covert...Papadopoulos, and J. Neil, “Eliminating steganography in internet traffic with active wardens,” in Information Hiding, ser. Lecture Notes in

  17. Electronic Wave Packet in a Quantized Electromagnetic Field

    Institute of Scientific and Technical Information of China (English)

    程太旺; 薛艳丽; 李晓峰; 吴令安; 傅盘铭

    2002-01-01

    We study a non-stationary electronic wave packet in a quantized electromagnetic field. Generally, the electron and field become entangled as the electronic wave packet evolves. Here we find that, when the initial photon state is a coherent one, the wavefunction of the system can be factorized if we neglect the transferred photon number. In this case, the quantized-field calculation is equivalent to the semi-classical calculation.

  18. On wave-packet dynamics in a decaying quadratic potential

    DEFF Research Database (Denmark)

    Møller, Klaus Braagaard; Henriksen, Niels Engholm

    1997-01-01

    We consider the time-dependent Schrodinger equation for a quadratic potential with an exponentially decaying force constant. General analytical solutions are presented and we highlight in particular, the signatures of classical mechanics in the wave packet dynamics.......We consider the time-dependent Schrodinger equation for a quadratic potential with an exponentially decaying force constant. General analytical solutions are presented and we highlight in particular, the signatures of classical mechanics in the wave packet dynamics....

  19. Label-controlled optical packet routing technologies and applications

    DEFF Research Database (Denmark)

    Koonen, A.M.J.; Yan, N.; Vegas Olmos, Juan José;

    2007-01-01

    An overview is given of various optical packet labeling techniques. The architecture and technologies are discussed for optical packet routing nodes using orthogonal labeling with optoelectronic label processing, and for nodes using time-serial labeling with all-optical time-serial label processing....... An example of a nearterm application is given, and a comparison of routing technologies is made regarding their cost and reliability aspects....

  20. Improvements in Routing for Packet-Switched Networks

    Science.gov (United States)

    1975-02-18

    the routing table at X is then updated by a simple averaging process. 2.3.6 Negative Reinfafccrnent Negative reinforcement is a class of techniques...is to reduce the "ping-pong" effect. 2.3.7 Bi-adaptive Bi-adaptivc is still a further synthesis of backwards learning and negative reinforcement , where...table en- tries can only be increased by negative reinforcement and decreased by backward learning. 2 .-.8 Superposition Superposition is

  1. TCP Packet Trace Analysis. M.S. Thesis

    Science.gov (United States)

    Shepard, Timothy J.

    1991-01-01

    Examination of a trace of packets collected from the network is often the only method available for diagnosing protocol performance problems in computer networks. This thesis explores the use of packet traces to diagnose performance problems of the transport protocol TCP. Unfortunately, manual examination of these traces can be so tedious that effective analysis is not possible. The primary contribution of this thesis is a graphical method of displaying the packet trace which greatly reduce, the tediousness of examining a packet trace. The graphical method is demonstrated by the examination of some packet traces of typical TCP connections. The performance of two different implementations of TCP sending data across a particular network path is compared. Traces many thousands of packets long are used to demonstrate how effectively the graphical method simplifies examination of long complicated traces. In the comparison of the two TCP implementations, the burstiness of the TCP transmitter appeared to be related to the achieved throughput. A method of quantifying this burstiness is presented and its possible relevance to understanding the performance of TCP is discussed.

  2. Modeling On-Body DTN Packet Routing Delay in the Presence of Postural Disconnections

    Science.gov (United States)

    Quwaider, Muhannad; Taghizadeh, Mahmoud; Biswas, Subir

    2014-01-01

    This paper presents a stochastic modeling framework for store-and-forward packet routing in Wireless Body Area Networks (WBAN) with postural partitioning. A prototype WBANs has been constructed for experimentally characterizing and capturing on-body topology disconnections in the presence of ultrashort range radio links, unpredictable RF attenuation, and human postural mobility. Delay modeling techniques for evaluating single-copy on-body DTN routing protocols are then developed. End-to-end routing delay for a series of protocols including opportunistic, randomized, and two other mechanisms that capture multiscale topological localities in human postural movements have been evaluated. Performance of the analyzed protocols are then evaluated experimentally and via simulation to compare with the results obtained from the developed model. Finally, a mechanism for evaluating the topological importance of individual on-body sensor nodes is developed. It is shown that such information can be used for selectively reducing the on-body sensor-count without substantially sacrificing the packet delivery delay. PMID:25530749

  3. Highly survivable communications: Complementary media packet switched networks

    Science.gov (United States)

    Yavuz, D.; Eken, F.; Karavassilis, N.

    1994-07-01

    The requirement for highly survivable communications (HSC) for essential command functions in military operations does not need any justification. The ability to communicate under extreme jamming levels and adverse propagation conditions, including high altitude nuclear events, is a very important requirement. There are also many natural disaster related requirements that also need such highly survivable communications. The prevalent and in a sense classical, approach to provide highly assured connectivity can be summarized as follows: Take a particular propagation medium and try to obtain the ultimate performance from it. There are many examples of this philosophy some successful, most not. Our approach, on the other hand, is to use complementary multi-media or mixed-media where communication links utilizing essentially commercial-off-the-shelf (COTS) equipment are integrated using packet radio (PR) techniques. There is also, in our view, an even more fundamental, recently discovered consideration why the expectation of continuous incremental refinement of a system using a given single media may be be achievable. This is derived from the theory of 'deterministic uncertainty' or more popularly known as 'theory of CHAOS', systems whose state space behavior has fractal characteristics. We will elaborate on this novel argument. Complementary multi-media approach has been the focus for all HSC communications activities at STC since 1982. The original STC studies and prototypes were in response to requirements of broadcasting (i.e., one-way transmission) information. A high frequency (HF)/meteorburst (MB) system was developed/prototyped/tested demonstrating the cost effectiveness of the approach. These results are reviewed. More recently, in 1992 STC has completed the development/test of an Open Systems Interconnection (OSI) HF packet radio protocol as no such open or non-proprietary protocol exists. This protocol has been fully tested, documented and made available to

  4. Psychology, not educational neuroscience, is the way forward for improving educational outcomes for all children: Reply to Gabrieli (2016) and Howard-Jones et al. (2016).

    Science.gov (United States)

    Bowers, Jeffrey S

    2016-10-01

    In Bowers (2016), I argued that there are (a) practical problems with educational neuroscience (EN) that explain why there are no examples of EN improving teaching and (b) principled problems with the logic motivating EN that explain why it is likely that there never will be. In the following article, I consider the main responses raised by both Gabrieli (2016) and Howard-Jones et al. (2016) and find them all unconvincing. Following this exchange, there are still no examples of EN providing new insights to teaching in the classroom, there are still no examples of EN providing new insights to remedial instructions for individuals, and, as I detail in this article, there is no evidence that EN is useful for the diagnosis of learning difficulties. The authors have also failed to address the reasons why EN is unlikely to benefit educational outcomes in the future. Psychology, by contrast, can (and has) made important discoveries that can (and should) be used to improve teaching and diagnostic tests for learning difficulties. This is not a debate about whether science is relevant to education, rather it is about what sort of science is relevant. (PsycINFO Database Record

  5. Hybrid single-packet IP traceback with low storage and high accuracy.

    Science.gov (United States)

    Yang, Ming Hour

    2014-01-01

    Traceback schemes have been proposed to trace the sources of attacks that usually hide by spoofing their IP addresses. Among these methods, schemes using packet logging can achieve single-packet traceback. But packet logging demands high storage on routers and therefore makes IP traceback impractical. For lower storage requirement, packet logging and packet marking are fused to make hybrid single-packet IP traceback. Despite such attempts, their storage still increases with packet numbers. That is why RIHT bounds its storage with path numbers to guarantee low storage. RIHT uses IP header's ID and offset fields to mark packets, so it inevitably suffers from fragment and drop issues for its packet reassembly. Although the 16-bit hybrid IP traceback schemes, for example, MORE, can mitigate the fragment problem, their storage requirement grows up with packet numbers. To solve the storage and fragment problems in one shot, we propose a single-packet IP traceback scheme that only uses packets' ID field for marking. Our major contributions are as follows: (1) our fragmented packets with tracing marks can be reassembled; (2) our storage is not affected by packet numbers; (3) it is the first hybrid single-packet IP traceback scheme to achieve zero false positive and zero false negative rates.

  6. Combining control electronics with SOA to equalize packet-to-packet power variations for optical 3R regeneration in optical networks at 10 Gbit/s

    DEFF Research Database (Denmark)

    Wessing, Henrik; Lavigne, B.; Sørensen, Brian Michael;

    2004-01-01

    We report on the combined effects of control electronics and a SOA as to suppress packet to packet power fluctuations. Associated to a SOA-MZI based 3R regenerator, we demonstrate a power dynamic range of 9 dB.......We report on the combined effects of control electronics and a SOA as to suppress packet to packet power fluctuations. Associated to a SOA-MZI based 3R regenerator, we demonstrate a power dynamic range of 9 dB....

  7. An Efficient Algorithm for Detection of Selfish Packet Dropping Nodes in Wireless Mesh Networks

    CERN Document Server

    Sen, Jaydip

    2011-01-01

    In a wireless mesh network (WMN), high speed routers equipped with advanced antennas, communicate with each other in a multi-hop fashion over wireless channels and form a broadband backhaul. WMNs provide reliable connectivity and fault-tolerance, as each node is connected to several other nodes. If a node fails due to hardware problems, its neighbors can find another route. Extra capacity can be achieved by introducing additional nodes in the network. However, the throughput of a WMN may be severely degraded due to presence of some selfish routers that avoid forwarding packets for other nodes even as they send their own traffic through the network. This paper presents an algorithm for detection of selfish nodes in a WMN that uses statistical theory of inference for reliable clustering of the nodes. Simulation results show that the algorithm has a high detection rate and a low rate of false positives.

  8. A Framework to Move Forward on the Path to Eco-innovation in the Construction Industry: Implications to Improve Firms' Sustainable Orientation.

    Science.gov (United States)

    Segarra-Oña, María-del-Val; Peiró-Signes, Angel; Cervelló-Royo, Roberto

    2015-12-01

    This paper examines key aspects in the innovative behavior of the construction firms that determine their environmental orientation while innovating. Structural equation modeling was used and data of 222 firms retrieved from the Spanish Technological Innovation Panel (PITEC) for 2010 to analyse the drivers of environmental orientation of the construction firms during the innovation process. The results show that the environmental orientation is positively affected by the product and process orientation of construction firms during the innovation process. Furthermore, the positive relation between the importance of market information sources and environmental orientation, mediated by process and product orientation, is discussed. Finally, a model that explains these relations is proposed and validated. Results have important managerial implications for those companies worried about their eco-innovative focus as the types of actions and relations within firms most suitable for improving their eco-innovative orientation are highlighted.

  9. Packet Size Based Routing for Stable Data Delivery in Mobile Ad-Hoc Networks

    Science.gov (United States)

    Khan, Ashiq; Suzuki, Toshihiro; Kobayashi, Motonari; Takita, Wataru; Yamazaki, Kenichi

    In Mobile AD-hoc Networks (MANET), transportation capability of wireless links' varies according to the size of the packets they transport. This instability, which is more acute in long links, has received little attention in the stabilizing schemes proposed so far for MANET. A lot of research has been carried out to utilize more reliable links in making end-to-end routes to avoid frequent route failures and realize higher packet delivery ratio. However, these approaches mainly consider the availability of a link over time and depend on link history which is difficult to acquire in highly dynamic systems. In this paper, we present an easy-to-implement but efficient method to find suitable end-to-end routes that are capable of transporting different sizes of the application data packets. Our scheme is stateless and does not rely on the underlying data link and physical layers. An extensive simulation shows the validity of our concept and highlights the improvement achieved by our proposal.

  10. Seismic Target Classification Using a Wavelet Packet Manifold in Unattended Ground Sensors Systems

    Directory of Open Access Journals (Sweden)

    Enliang Song

    2013-07-01

    Full Text Available One of the most challenging problems in target classification is the extraction of a robust feature, which can effectively represent a specific type of targets. The use of seismic signals in unattended ground sensor (UGS systems makes this problem more complicated, because the seismic target signal is non-stationary, geology-dependent and with high-dimensional feature space. This paper proposes a new feature extraction algorithm, called wavelet packet manifold (WPM, by addressing the neighborhood preserving embedding (NPE algorithm of manifold learning on the wavelet packet node energy (WPNE of seismic signals. By combining non-stationary information and low-dimensional manifold information, WPM provides a more robust representation for seismic target classification. By using a K nearest neighbors classifier on the WPM signature, the algorithm of wavelet packet manifold classification (WPMC is proposed. Experimental results show that the proposed WPMC can not only reduce feature dimensionality, but also improve the classification accuracy up to 95.03%. Moreover, compared with state-of-the-art methods, WPMC is more suitable for UGS in terms of recognition ratio and computational complexity.

  11. Diversity Techniques for Single-Carrier Packet Retransmissions over Frequency-Selective Channels

    Directory of Open Access Journals (Sweden)

    Inbar Fijalkow

    2009-01-01

    Full Text Available In data packet communication systems over multipath frequency-selective channels, hybrid automatic repeat request (HARQ protocols are usually used in order to ensure data reliability. For single-carrier packet transmission in slow fading environment, an identical retransmission of the same packet, due to a decoding failure, does not fully exploit the available time diversity in retransmission-based HARQ protocols. In this paper, we compare two transmit diversity techniques, namely, cyclic frequency-shift diversity and bit-interleaving diversity. Both techniques can be integrated in the HARQ scheme in order to improve the performance of the joint detector. Their performance in terms of pairwise error probability is investigated using maximum likelihood detection and decoding. The impact of the channel memory and the modulation order on the performance gain is emphasized. In practice, we use low complexity linear filter-based equalization which can be efficiently implemented in the frequency domain. The use of iterative equalization and decoding is also considered. The performance gain in terms of frame error rate and data throughput is evaluated by numerical simulations.

  12. Improvements on robust email protocols with perfect forward secrecy%具有完美前向机密性的鲁棒电子邮件协议的改进

    Institute of Scientific and Technical Information of China (English)

    蒋睿; 胡爱群; 杨晓辉

    2008-01-01

    According to the security shortages of two robustpractical email protocols with perfect forward secrecy, attacks onthe two protocols are analyzed and corresponding improvementson the two protocols are proposed. First, by analyzing the twoemail protocols, the corresponding man-in-the-middle attacks areproposed, where the adversary forges the messages in thereceiving phase to cheat the two communication participants andmakes them share the wrong session keys with him.Consequently, the man-in-the-middle attacks can make the twoprotocols fail to provide perfect forward secrecy. Secondly, byadding corresponding signatures in the receiving phases of thetwo protocols, two corresponding improvements on the protocolsare proposed to overcome the man-in-the-middle attacks on thetwo protocols and make them provide perfect forward secrecy.Moreover, the two improved protocols can retain all the merits ofthe former protocols.%针对2个具有完美前向机密性的鲁棒电子邮件协议所存在的安全缺陷,分析了2个协议所面临的协议攻击,并得出了相应的改进方案.首先,通过对2个电子邮件协议的分析,提出了相应的中间人攻击方法,其中攻击者在协议的接收阶段通过伪造信息来欺骗通信双方,并使通信双方与其共享错误的会话密钥.由此中间人攻击使得2个电子邮件协议的完美前向机密性得不到保证.其次,通过在2个协议的接收阶段加入相应的签名信息,提出了对2个协议的改进方案,以确保改进协议能够克服中间人攻击并且提供协议的完美前向机密性.此外,经改进的协议仍然能够保持原协议的所有优点.

  13. LHC Forward Physics

    CERN Document Server

    Akiba, K.

    2016-10-17

    The goal of this report is to give a comprehensive overview of the rich field of forward physics, with a special attention to the topics that can be studied at the LHC. The report starts presenting a selection of the Monte Carlo simulation tools currently available, chapter 2, then enters the rich phenomenology of QCD at low, chapter 3, and high, chapter 4, momentum transfer, while the unique scattering conditions of central exclusive production are analyzed in chapter 5. The last two experimental topics, Cosmic Ray and Heavy Ion physics are presented in the chapter 6 and 7 respectively. Chapter 8 is dedicated to the BFKL dynamics, multiparton interactions, and saturation. The report ends with an overview of the forward detectors at LHC. Each chapter is correlated with a comprehensive bibliography, attempting to provide to the interested reader with a wide opportunity for further studies.

  14. LHC forward physics

    Energy Technology Data Exchange (ETDEWEB)

    Cartiglia, N. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Royon, C. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). et al.

    2015-10-02

    The goal of this report is to give a comprehensive overview of the rich field of forward physics, with a special attention to the topics that can be studied at the LHC. The report starts presenting a selection of the Monte Carlo simulation tools currently available, chapter 2, then enters the rich phenomenology of QCD at low, chapter 3, and high, chapter 4, momentum transfer, while the unique scattering conditions of central exclusive production are analyzed in chapter 5. The last two experimental topics, Cosmic Ray and Heavy Ion physics are presented in the chapter 6 and 7 respectively. Chapter 8 is dedicated to the BFKL dynamics, multiparton interactions, and saturation. The report ends with an overview of the forward detectors at LHC. Each chapter is correlated with a comprehensive bibliography, attempting to provide to the interested reader with a wide opportunity for further studies.

  15. Forward Osmosis Process

    KAUST Repository

    Duan, Jintang

    2013-12-05

    A process that can alleviate the internal concentration polarization and can enhance membrane performance of a forward osmosis system includes the steps of passing a fluid in a forward osmosis system from a feed solution with a first osmotic pressure, through a membrane into a draw solution comprising a draw solute with a second osmotic pressure, where the first osmotic pressure is lower than the second osmotic pressure, the membrane includes an active layer and a support layer, and the membrane is oriented such that the active layer of the membrane faces a draw side, and the support layer faces a feed side; and applying an external force to the fluid on the feed side of the membrane.

  16. Forward-Looking Betas

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory

    -looking. This paper introduces a radically different approach to estimating market betas. Using the tools in Bakshi and Madan (2000) and Bakshi, Kapadia and Madan (2003) we employ the information embedded in the prices of individual stock options and index options to compute our forward-looking market beta......Few issues are more important for finance practice than the computation of market betas. Existing approaches compute market betas using historical data. While these approaches differ in terms of statistical sophistication and the modeling of the time-variation in the betas, they are all backward...... at the daily frequency. This beta can be computed using option data for a single day, and is able to reflect sudden changes in the structure of the underlying company. Based on an empirical investigation of daily cross-sections of option contracts on thirty underlying companies, we conclude that these forward...

  17. Ellipsoidal electrogastrographic forward modelling

    Energy Technology Data Exchange (ETDEWEB)

    Irimia, Andrei; Bradshaw, L Alan [Living State Physics Laboratories, Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235-1807 (United States)

    2005-09-21

    The theoretical and computational study of the electromagnetic forward and inverse problems in ellipsoidal geometry is important in electrogastrography because the geometry of the human stomach can be well approximated using this idealized body. Moreover, the anisotropies inherent to this organ can be highlighted by the characteristics of the electric potential associated with current dipoles in an ellipsoid. In this paper, we present a forward simulation for the stomach using an analytic expression of the gastric electric potential that employs a truncated expansion of ellipsoidal harmonics; we then demonstrate that an activation front of dipoles propagating along the body of an ellipsoid can simulate gastric electrical activity. In addition to the usefulness of our model, we also discuss its limitations and accuracy.

  18. Ellipsoidal electrogastrographic forward modelling.

    Science.gov (United States)

    Irimia, Andrei; Bradshaw, L Alan

    2005-09-21

    The theoretical and computational study of the electromagnetic forward and inverse problems in ellipsoidal geometry is important in electrogastrography because the geometry of the human stomach can be well approximated using this idealized body. Moreover, the anisotropies inherent to this organ can be highlighted by the characteristics of the electric potential associated with current dipoles in an ellipsoid. In this paper, we present a forward simulation for the stomach using an analytic expression of the gastric electric potential that employs a truncated expansion of ellipsoidal harmonics; we then demonstrate that an activation front of dipoles propagating along the body of an ellipsoid can simulate gastric electrical activity. In addition to the usefulness of our model, we also discuss its limitations and accuracy.

  19. An Energy Scaled and Expanded Vector-Based Forwarding Scheme for Industrial Underwater Acoustic Sensor Networks with Sink Mobility.

    Science.gov (United States)

    Wadud, Zahid; Hussain, Sajjad; Javaid, Nadeem; Bouk, Safdar Hussain; Alrajeh, Nabil; Alabed, Mohamad Souheil; Guizani, Nadra

    2017-09-30

    Industrial Underwater Acoustic Sensor Networks (IUASNs) come with intrinsic challenges like long propagation delay, small bandwidth, large energy consumption, three-dimensional deployment, and high deployment and battery replacement cost. Any routing strategy proposed for IUASN must take into account these constraints. The vector based forwarding schemes in literature forward data packets to sink using holding time and location information of the sender, forwarder, and sink nodes. Holding time suppresses data broadcasts; however, it fails to keep energy and delay fairness in the network. To achieve this, we propose an Energy Scaled and Expanded Vector-Based Forwarding (ESEVBF) scheme. ESEVBF uses the residual energy of the node to scale and vector pipeline distance ratio to expand the holding time. Resulting scaled and expanded holding time of all forwarding nodes has a significant difference to avoid multiple forwarding, which reduces energy consumption and energy balancing in the network. If a node has a minimum holding time among its neighbors, it shrinks the holding time and quickly forwards the data packets upstream. The performance of ESEVBF is analyzed through in network scenario with and without node mobility to ensure its effectiveness. Simulation results show that ESEVBF has low energy consumption, reduces forwarded data copies, and less end-to-end delay.

  20. Congestion control in wireless links based on selective delivery of erroneous packets

    DEFF Research Database (Denmark)

    Korhonen, Jari; Perkis, Andrew; Reiter, Ulrich

    2011-01-01

    of retransmissions derived from bit errors. In this case, it might be beneficial to allow delivery of partly corrupted packets up to the application layer instead of reducing the transmission rate. This would decrease the number of retransmissions in the link layer and therefore relieve congestion, but at the cost...... the performance of the proposed mechanism against traditional congestion control with a simulation study. The results show that the proposed approach can improve the overall performance both by increasing the throughput over the wireless and improving the video quality in terms of peak signal-to-noise ratio (PSNR...

  1. From the combat medic to the forward surgical team: the Madigan model for improving trauma readiness of brigade combat teams fighting the Global War on Terror.

    Science.gov (United States)

    Sohn, Vance Y; Miller, Joseph P; Koeller, Craig A; Gibson, Steven O; Azarow, Kenneth S; Myers, Jerome B; Beekley, Alec C; Sebesta, James A; Christensen, Jon B; Rush, Robert M

    2007-03-01

    Medics assigned to combat units have a notable paucity of trauma experience. Our goal was to provide intense trauma refresher training for the conventional combat medic to better prepare them for combat casualty care in the War on Terror. Our Tactical Combat Casualty Care Course (TC3) consisted of the following five phases: (1) One and one-half-day didactic session; (2) Half-day simulation portion with interactive human surgical simulators for anatomical correlation of procedures and team building; (3) Half-day of case presentations and triage scenarios from Iraq/Afghanistan and associated skills stations; (4) Half-day live tissue lab where procedures were performed on live anesthetized animals in a controlled environment; and (5) One-day field phase where live anesthetized animals and surgical simulators were combined in a real-time, field-training event to simulate realistic combat injuries, evacuation problems, and mass casualty scenarios. Data collection consisted of surveys, pre- and posttests, and after-action comments. A total of 1317 personnel participated in TC3 from October 2003 through May 2005. Over the overlapping study period from December 2004 to April 2005, 327 soldiers participated in the formal five-phase course. Three hundred four (94%) students were combat medics who were preparing for combat operations in Iraq or Afghanistan. Of those completing the training, 97% indicated their confidence and ability to treat combat casualties were markedly improved. Moreover, of those 140 medics who took the course and deployed to Iraq for 1 year, 99% indicated that the principles taught in the TC3 course helped with battlefield management of injured casualties during their deployment. The hybrid training model is an effective method for training medical personnel to deal with modern battle injuries. This course increases the knowledge and confidence of combat medics deploying and fighting the Global War on Terrorism.

  2. Constrained traffic regulation in variable-length packet networks

    Science.gov (United States)

    Karumanchi, Ashok; Varadarajan, Sridhar; Rao, Kalyan; Talabattula, Srinivas

    2004-02-01

    The availability of high bandwidth in optical networks coupled with the evolution of applications such as video on demand and telemedicine create a clear need for providing quality-of-service (QoS) guarantees in optical networks. Proliferation of the IP-over-WDM model in these networks requires the network to provide QoS guarantees for variable-length packets. In this context, we address the problem of constrained traffic regulation--traffic regulation with buffer and delay constraints--in variable-length packet networks. We use the filtering theory under max-plus (max, +) algebra to address this problem. For a constrained traffic-regulation problem with maximum tolerable delay and maximum buffer size, the traffic regulator that generates g-regular output traffic minimizing the number of discarded packets is a concatenation of the f clipper and the minimal g regulator. f is a function of g, maximum delay, and maximum buffer size. The f clipper is a bufferless device, which drops the packets as necessary so that its output is f regular. The minimal g regulator is a buffered device that delays packets as necessary so that its output is g regular. The g regulator is a linear shift-invariant filter with impulse response g, under the (max, +) algebra.

  3. Flood Avoidance Mechanisms for Bridged Resilient Packet Rings

    Institute of Scientific and Technical Information of China (English)

    Pisai Setthawong; Surat Tanterdtid

    2008-01-01

    Resilient Packet Ring (RPR), or the Standard IEEE 802.17, is a new IP-based network technology proposed to replace SONET/SDH in metropolitan area networks. RPR is well-adapted to handle multimedia traffic and is efficient.However, when RPR networks are bridged, inter-ring packets, or packets with the destination on a remote RPR network other than on the source network, are flooded on the source and the destination networks, and also on the path of the intermediate networks between the source and the destination networks. This decreases the available bandwidth for othertraffic in those networks and is inefficient. As a result, we propose two solutions based on topology discovery, global topologydiscovery (GTD) and enhanced topology discovery (ETD), that prevent the flooding of inter-ring packets. GTD enables the bridges to determine the next-hop bridge for each destination. ETD enables the source node to determine a default ringlet,so that packets reach the next-hop bridge without flooding the source network. The proposed solutions were analyzed and the overhead bandwidth and stabilization time were shown to be bounded. Simulations performed showed that the proposed solutions successfully avoid flooding and achieve optimal efficiency in the intermediate and destination networks, and in the source networks with one bridge.

  4. "Keeping each patient safe": quality safety teaching/learning packets.

    Science.gov (United States)

    Benezo, Chris; Gaudy, Doris; White, T Michael

    2004-12-01

    University of Pittsburgh Medical Center (UPMC) McKeesport developed a tool, the UPMC McKeesport Quality Safety Teaching/Learning Packet, to provide physicians, nurses, and therapists with a common language to address complex safety issues. Teaching/learning packets were developed to "keep each patient safe": by calling for help early; from falls and confusion; and from hospital-acquired infections (http://McKeesport.upmc.com/KeepingPatientsSafe.htm). In July 2002, the concept of calling for help early became a requirement at UPMC McKeesport. The code team was to be called for any significant change in status and for traditional code arrests. In 2004, a teaching/learning packet addressed the concepts of fall risk and acute (delirium) and chronic (dementia) confusion. Strategies were implemented to reduce the rate of falls through risk screening and interventions for falls and delirium. In April 2004, a teaching/learning packet was introduced to reduce hospital-acquired infections, and professionals were positioned to better address isolation, hand hygiene, central-line-associated bacteremia, Clostridium difficile, and appropriate antibiotic usage. Three quality safety teaching/learning packets, which provided the professionals in the organization with the common language (culture) to advance patient safety, accomplished rapid change and were well accepted by staff and physicians.

  5. Integrated optical buffers for packet-switched networks

    Science.gov (United States)

    Burmeister, Emily Frances

    Routers form the backbone of the Internet, directing data to the right locations with huge throughput capacity of terabits/second) and very few errors (1 error allowed in 1012 bits). However, as the Internet continues to grow rapidly, so must the capacity of electronic routers, thereby also growing in footprint and power consumption. The energy bill alone has developers looking for an alternate solution. Today's routers can only operate with electrical signals although Internet data is transmitted optically. This requires the data to be converted from the optical domain to the electrical domain and back again. Optical routers have the potential of saving in power by omitting these conversions, but have been held back in part by the lack of a practical optical memory device. This work presents the first integrated optical buffer for next generation optical packet-switched networks. Buffering is required in a router to move packets of data in order to avoid collisions between packets heading to the same destination at the same time. The device presented here uses an InP-based two-by-two switch with a silica waveguide delay to form a recirculating buffer. Packet storage was shown with 98% packet recovery for 5 circulations. Autonomous contention resolution was demonstrated with two buffered channels to show that the technology is a realistic solution for creating multiple element buffers on multiple router ports. This thesis proposes and demonstrates the first integrated optical random access memory, thereby making a great stride toward high capacity optical routers.

  6. A NEURAL NETWORK BASED TRAFFIC-AWARE FORWARDING STRATEGY IN NAMED DATA NETWORKING

    Directory of Open Access Journals (Sweden)

    Parisa Bazmi

    2016-11-01

    Full Text Available Named Data Networking (NDN is a new Internet architecture which has been proposed to eliminate TCP/IP Internet architecture restrictions. This architecture is abstracting away the notion of host and working based on naming datagrams. However, one of the major challenges of NDN is supporting QoS-aware forwarding strategy so as to forward Interest packets intelligently over multiple paths based on the current network condition. In this paper, Neural Network (NN Based Traffic-aware Forwarding strategy (NNTF is introduced in order to determine an optimal path for Interest forwarding. NN is embedded in NDN routers to select next hop dynamically based on the path overload probability achieved from the NN. This solution is characterized by load balancing and QoS-awareness via monitoring the available path and forwarding data on the traffic-aware shortest path. The performance of NNTF is evaluated using ndnSIM which shows the efficiency of this scheme in terms of network QoS improvementof17.5% and 72% reduction in network delay and packet drop respectively.

  7. Multi-level forward mutation genetic algorithm to improve the efficiency for VRP%多级正向变异的遗传算法提高求解VRP问题效率

    Institute of Scientific and Technical Information of China (English)

    胡中栋; 谢金伟

    2014-01-01

    应用遗传算法对车辆路径问题(VRP)求解时,由于遗传算法在解决VRP问题时,交叉操作难以保留优秀基因片段,可能导致算法收敛较慢等问题。在一定程度上影响了遗传算法解决VRP问题的实用性。在前人的基础上,通过一种多级正向变异方法,使变异最大程度向好的方向进行,拆除基因片段中较差的基因连接并建立新基因连接,从而得到较优的新基因片段,重复一定的变异次数,让变异达到最优效果。通过实验表明多级正向变异明显提高了遗传算法解决此类问题的效率。%When using genetic algorithm to solve VRP problem, a slower convergence problem may be generated because the crossover operation could not keep good genes, which affects the usefulness of genetic algorithms to solve the VRP problem to a certain extent. On the basis of our predecessors, we have created a multi-level forward mutation method which dismantles poor gene fragment connection and creates a new connection to get a better gene. A large number of experiments show that forward mutation can greatly improve the genetic algorithm to solve such problems efficiently.

  8. Analysis of the interaction of participants freight forwarding system

    Directory of Open Access Journals (Sweden)

    Pavlo Popovych

    2016-12-01

    Full Text Available Main goal of this work is the analysis of the interaction of participants of freight forwarding activities. Research methods included analysis of scientific literature, theory of systems and systems analysis, methods of induction and deduction. As sources of information used and applied work of fundamental importance known foreign and local scientists and regulatory and legislative documents of Ukraine for the state transport policy. In the article the basic interactions of participants of freight forwarding activities. Classified components freight forwarding services. Assign the concept freight forwarding system and its aim. Established element and forms of cooperation in the freight forwarding system. The main task of forwarding companies are organizing, coordinating and ensuring the delivery from shipper to consignee. Freight forwarding company responsible for the timely delivery of the goods on the condition of preservation of the quantity and quality specified time conditions. Currently used methods are uneffective decision-making, leading to losses. These circumstances require improvement methodology management of freight forwarding companies. This is possible only using modern mathematical methods and information technologies that will improve the operation of freight forwarding companies. The article presents a theoretical exposition of the basic processes of interaction between participants in freight forwarding system. The article may be of interest to specialists of freight forwarding companies.

  9. Forward-Looking Betas

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory

    Few issues are more important for finance practice than the computation of market betas. Existing approaches compute market betas using historical data. While these approaches differ in terms of statistical sophistication and the modeling of the time-variation in the betas, they are all backward......-looking. This paper introduces a radically different approach to estimating market betas. Using the tools in Bakshi and Madan (2000) and Bakshi, Kapadia and Madan (2003) we employ the information embedded in the prices of individual stock options and index options to compute our forward-looking market beta...

  10. The way forward

    CERN Document Server

    Fridlund, Malcolm; Liseau, René

    2016-01-01

    For the last few decades the study of disks around stars young and old and of different types have progressed significantly. During the same time a completely new discipline, the study of exoplanets, planets orbiting stars other than our Sun, have emerged. Both these fields, which are interconnected, have benefited from the development of new instrumentation, and especially by telescopes and detectors deployed in space. In this chapter we are describing the state of the art of such instruments and make an inventory of what is being currently developed. We also state some of the requirements of the next steps and what type of instruments will lead the way forward.

  11. Improved 60 GHz Millimeter-Wave Generator Based on Feed-Forward Modulation%一种改进的基于前向调制技术生成60 GHz毫米波方案

    Institute of Scientific and Technical Information of China (English)

    许丽丽; 宁提纲; 李晶; 裴丽; 油海东; 陈宏尧; 张婵

    2013-01-01

    光载无线通信(ROF)技术是通信业宽带化和无线化的产物,该技术将光纤通信技术与毫米波通信技术进行融合,具有广阔的应用前景.目前世界众多国家在60 GHz毫米波频段相继划出免许可连续频谱,这使得60 GHz毫米波无线通信成为近距离无线通信领域的研究热点之一.为了降低ROF系统的成本,提高系统的性能,提出了一种改进的基于前向调制(FFM)技术生成60 GHz毫米波方案,分析了系统各光电器件的工作原理,仿真了不同的参量设置对系统性能的影响曲线.该方案结合了前向调制技术和光波分复用技术的优点,简化了整个系统的复杂程度,降低了ROF系统的造价成本,同时减小了误码率,提高了系统的性能.%A radio over fiber (ROF) system is a product of the broad band and wireless in the communication industry. It combines the optical fiber communication technology and millimeter-wave communication technology, and has a broad application prospect. At present many countries mark off unlicensed continuous-frequency spectra in 60 GHz millimeter wave frequency band, which makes 60 GHz millimeter-wave wireless communication become one of the hot researches in the field of close wireless communication. In order to reduce the cost of a ROF system and improve its performance, an improved 60 GHz millimeter-wave generator based on feed-forward modulation (FFM) technique is proposed. The principle of the photoelectric device is analysed and the effect of different parameters setting in the performance of the system curve is simulated. The scheme combines with the advantages of forward modulation technology and light wavelength division multiplexing technology. It simplifies the complexity of the system, reduces the cost of the ROF system, reduces the error rate and improves the performance of the whole system.

  12. High Performance Ethernet Packet Processor Core for Next Generation Networks

    Directory of Open Access Journals (Sweden)

    Raja Jitendra Nayaka

    2012-10-01

    Full Text Available As the demand for high speed Internet significantly increasing to meet the requirement of large datatransfers, real-time communication and High Definition ( HD multimedia transfer over IP, the IP basednetwork products architecture must evolve and change. Application specific processors require highperformance, low power and high degree of programmability is the limitation in many general processorbased applications. This paper describes the design of Ethernet packet processor for system-on-chip (SoCwhich performs all core packet processing functions, including segmentation and reassembly, packetizationclassification, route and queue management which will speedup switching/routing performance making itmore suitable for Next Generation Networks (NGN. Ethernet packet processor design can be configuredfor use with multiple projects targeted to a FPGA device the system is designed to support 1/10/20/40/100Gigabit links with a speed and performance advantage. VHDL has been used to implement and simulatedthe required functions in FPGA.

  13. Optimization and Assessment of Wavelet Packet Decompositions with Evolutionary Computation

    Directory of Open Access Journals (Sweden)

    Schell Thomas

    2003-01-01

    Full Text Available In image compression, the wavelet transformation is a state-of-the-art component. Recently, wavelet packet decomposition has received quite an interest. A popular approach for wavelet packet decomposition is the near-best-basis algorithm using nonadditive cost functions. In contrast to additive cost functions, the wavelet packet decomposition of the near-best-basis algorithm is only suboptimal. We apply methods from the field of evolutionary computation (EC to test the quality of the near-best-basis results. We observe a phenomenon: the results of the near-best-basis algorithm are inferior in terms of cost-function optimization but are superior in terms of rate/distortion performance compared to EC methods.

  14. DIESEL ENGINES' VIBROACOUSTIC SIGNATURE EXTRACTION BY WAVELET PACKET TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    邹剑; 陈进; 邹军; 耿遵敏

    2002-01-01

    Multisource unstable impulsive excitations, time-varying transmission path, concentrated mode, dispersion and reverberation that are important characteristics of reciprocating machines such as diesel engines result in wide-band non-stationary vibroacoustic responses which influence the effective extraction of vibroacoustic signatures and become a key factor to limit diesel engines' vibration diagnosis. In this paper, a serial theoretical deduction on the unstable dynamic properties of diesel engines was made; the mechanism of non-stationary vibroacoustic responses was elucidated. Based upon that, the wavelet packet technique was introduced. The reason for the existence of frequency aliasing in the Paley series from wavelet packets' decomposition was analyzed, and the wavelet packet frequency-shifting algorithm was given. Experiments on 190 serial diesel engines verify the given method's significant validity in vibroacoustic signature extraction and reciprocating machines' vibration diagnosis.

  15. Climatology of extratropical atmospheric wave packets in the northern hemisphere

    CERN Document Server

    Grazzini, Federico

    2010-01-01

    Planetary and synoptic scale wave-packets represents one important component of the atmospheric large-scale circulation. These dissipative structures are able to rapidly transport eddy kinetic energy, generated locally (e.g. by baroclinic conversion), downstream along the upper tropospheric flow. The transported energy, moving faster than individual weather systems, will affect the development of the next meteorological system on the leading edge of the wave packet, creating a chain of connections between systems that can be far apart in time and space, with important implications on predictability. In this work we present a different and novel approach to investigate atmospheric variability, based on the objective recognition of planetary and synoptic wave packets. We have developed an objective tracking algorithm which allows to extract relevant statistical properties of the wave trains as a function of their dominant wavelength. We have applied the algorithm to the daily analysis (every 12h) from 1958-2009...

  16. The Spatiotemporal Evolution of Wave Packets under Chaotic Condition

    Institute of Scientific and Technical Information of China (English)

    LIU Fang; LI Jun-Qing; LUO Yi-Xiao; XU Gong-Ou; ZUO Wei

    2001-01-01

    Using the minimum uncertainty state of quantum integrable system H0 as initial state,the spatiotemporal evolution of the wave packet under the action of perturbed Hamiltonian is studied causally as in classical mechanics. Due to the existence of the avoided energy level crossing in the spectrum there exist nonlinear resonances between somepairs of neighboring components of the wave packet,the deterministic dynamical evolution becomes very complicated and appears to be chaotic.It is proposed to use expectation values for the whole set of basic dynamical variables and the corresponding spreading widths to describe the topological features concisely such that the quantum chaotic motion can be studied in contrast with the quantum regular motion and well characterized with the asymptotic behaviors.It has been demonstrated with numerical results that such a wave packet has indeed quantum behaviors of ergodicity asin corresponding classical case.

  17. Detection and Defense Against Packet Drop Attack in MANET

    Directory of Open Access Journals (Sweden)

    Tariq Ahamad

    2016-02-01

    Full Text Available MANET is a temporary network for a specified work and with the enormous growth MANETs it is becoming important and simultaneously challenging to protect this network from attacks and other threats. Packet drop attack or gray hole attack is the easiest way to make a denial of service in these dynamic networks. In this attack the malicious node reflects itself as the shortest path and receives all the packets and drops the selected packets in order to give the user the service that that is not correct. It is a specific kind of attack and protects the network and user from detecting this malicious activity. In this article I have proposed an efficient for step technique that confirms that this attack can be detected and defended with least efforts and resource consumption.

  18. Forward Osmosis Brine Drying

    Science.gov (United States)

    Flynn, Michael; Shaw, Hali; Hyde, Deirdre; Beeler, David; Parodi, Jurek

    2015-01-01

    The Forward Osmosis Brine Drying (FOBD) system is based on a technique called forward osmosis (FO). FO is a membrane-based process where the osmotic potential between brine and a salt solution is equalized by the movement of water from the brine to the salt solution. The FOBD system is composed of two main elements, the FO bag and the salt regeneration system. This paper discusses the results of testing of the FO bag to determine the maximum water recovery ratio that can be attained using this technology. Testing demonstrated that the FO bag is capable of achieving a maximum brine water recovery ratio of the brine of 95%. The equivalent system mass was calculated to be 95 kg for a feed similar to the concentrated brine generated on the International Space Station and 86 kg for an Exploration brine. The results have indicated that the FOBD can process all the brine for a one year mission for between 11% to 10% mass required to bring the water needed to make up for water lost in the brine if not recycled. The FOBD saves 685 kg and when treating the International Space Station brine and it saves 829 kg when treating the Exploration brine. It was also demonstrated that saturated salt solutions achieve a higher water recovery ratios than solids salts do and that lithium chloride achieved a higher water recovery ratio than sodium chloride.

  19. Store and forward teledermatology

    Directory of Open Access Journals (Sweden)

    Kanthraj Garehatty

    2007-01-01

    Full Text Available Store and forward and real time or videoconferences are the two types of teledermatology services practiced. Dermatology and radio-diagnosis are visual specialties suited for store-and-forward teledermatology (SAFT. Advances in information technology, electronic instruments and biotechnology have revolutionized and brought changes in SAFT. Cellular phone, digital camera, personal digital assistants, Wi-Fi, Wi-Max and computer- aided-design software are incorporated to deliver the quality health care to remote geographic regions. Complete SAFT care equivalent to face-to-face consultation (Gold standard is essential. Health care providers in rural areas are the ′eyes′ for the consultants. Consultants to guide them should have a rapid periodic audit of visual parameters and dimensions of lesions. Given this background, this article reviews advances in 1 capture, store and transfer of images. 2 Computer Aided measurements of generalized and localized lesions and 3 the integration model to meet all the above two requirements in a centralized location. This process enables diagnosis, management, periodic assessment and complete follow-up care to achieve patient and physician satisfaction. Preservation of privacy and confidentiality of digital images is important. Uniform rules and regulations are required. Indian space research organization (ISRO, Government of India has demonstrated telemedicine pilot projects utilizing the satellite communication and mobile telemedicine units to be useful in meeting the health care needs of remote and rural India. we have to join hands with them to meet dermatology problems in rural areas.

  20. Store and forward teledermatology.

    Science.gov (United States)

    Kanthraj, Garehatty Rudrappa; Srinivas, Chakravarty Rangachari

    2007-01-01

    Store and forward and real time or videoconferences are the two types of teledermatology services practiced. Dermatology and radio-diagnosis are visual specialties suited for store-and-forward teledermatology (SAFT). Advances in information technology, electronic instruments and biotechnology have revolutionized and brought changes in SAFT. Cellular phone, digital camera, personal digital assistants, Wi-Fi, Wi-Max and computer- aided-design software are incorporated to deliver the quality health care to remote geographic regions. Complete SAFT care equivalent to face-to-face consultation (Gold standard) is essential. Health care providers in rural areas are the 'eyes' for the consultants. Consultants to guide them should have a rapid periodic audit of visual parameters and dimensions of lesions. Given this background, this article reviews advances in 1) capture, store and transfer of images. 2) Computer Aided measurements of generalized and localized lesions and 3) the integration model to meet all the above two requirements in a centralized location. This process enables diagnosis, management, periodic assessment and complete follow-up care to achieve patient and physician satisfaction. Preservation of privacy and confidentiality of digital images is important. Uniform rules and regulations are required. Indian space research organization (ISRO), Government of India has demonstrated telemedicine pilot projects utilizing the satellite communication and mobile telemedicine units to be useful in meeting the health care needs of remote and rural India. we have to join hands with them to meet dermatology problems in rural areas.

  1. Wave packet propagation across barriers by semiclassical initial value methods

    Science.gov (United States)

    Petersen, Jakob; Kay, Kenneth G.

    2015-07-01

    Semiclassical initial value representation (IVR) formulas for the propagator have difficulty describing tunneling through barriers. A key reason is that these formulas do not automatically reduce, in the classical limit, to the version of the Van Vleck-Gutzwiller (VVG) propagator required to treat barrier tunneling, which involves trajectories that have complex initial conditions and that follow paths in complex time. In this work, a simple IVR expression, that has the correct tunneling form in the classical limit, is derived for the propagator in the case of one-dimensional barrier transmission. Similarly, an IVR formula, that reduces to the Generalized Gaussian Wave Packet Dynamics (GGWPD) expression [D. Huber, E. J. Heller, and R. Littlejohn, J. Chem. Phys. 89, 2003 (1988)] in the classical limit, is derived for the transmitted wave packet. Uniform semiclassical versions of the IVR formulas are presented and simplified expressions in terms of real trajectories and WKB penetration factors are described. Numerical tests show that the uniform IVR treatment gives good results for wave packet transmission through the Eckart and Gaussian barriers in all cases examined. In contrast, even when applied with the proper complex trajectories, the VVG and GGWPD treatments are inaccurate when the mean energy of the wave packet is near the classical transmission threshold. The IVR expressions for the propagator and wave packet are cast as contour integrals in the complex space of initial conditions and these are generalized to potentially allow treatment of a larger variety of systems. A steepest descent analysis of the contour integral formula for the wave packet in the present cases confirms its relationship to the GGWPD method, verifies its semiclassical validity, and explains results of numerical calculations.

  2. Fast Packet Classification Using Multi-Dimensional Encoding

    Science.gov (United States)

    Huang, Chi Jia; Chen, Chien

    Internet routers need to classify incoming packets quickly into flows in order to support features such as Internet security, virtual private networks and Quality of Service (QoS). Packet classification uses information contained in the packet header, and a predefined rule table in the routers. Packet classification of multiple fields is generally a difficult problem. Hence, researchers have proposed various algorithms. This study proposes a multi-dimensional encoding method in which parameters such as the source IP address, destination IP address, source port, destination port and protocol type are placed in a multi-dimensional space. Similar to the previously best known algorithm, i.e., bitmap intersection, multi-dimensional encoding is based on the multi-dimensional range lookup approach, in which rules are divided into several multi-dimensional collision-free rule sets. These sets are then used to form the new coding vector to replace the bit vector of the bitmap intersection algorithm. The average memory storage of this encoding is Θ (L · N · log N) for each dimension, where L denotes the number of collision-free rule sets, and N represents the number of rules. The multi-dimensional encoding practically requires much less memory than bitmap intersection algorithm. Additionally, the computation needed for this encoding is as simple as bitmap intersection algorithm. The low memory requirement of the proposed scheme means that it not only decreases the cost of packet classification engine, but also increases the classification performance, since memory represents the performance bottleneck in the packet classification engine implementation using a network processor.

  3. Improving the Nephrology Match: the Path Forward.

    Science.gov (United States)

    Hsu, Chi-yuan; Parker, Mark G; Ross, Michael J; Schmidt, Rebecca J; Harris, Raymond C

    2015-11-01

    The Fellowship Match process was designed to provide applicants and program directors with an opportunity to consider all their options before making decisions about post-residency training. In a Match, applicants can choose the programs that best suit their career goals, and program directors can consider all candidates before preparing a rank order list. The Match is a contract, requiring obligations of both programs and applicants to achieve success, ensure uniformity, and standardize participation.

  4. Analysis of Circular Wave Packets Generated by Pulsed Electric Fields

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, S. [Vienna University of Technology, Austria; Reinhold, Carlos O [ORNL; Burgdorfer, J. [Vienna University of Technology, Austria; Wyker, B. [Rice University; Ye, S. [Rice University; Dunning, F. B. [Rice University

    2011-01-01

    We demonstrate that circular wave packets in high Rydberg states generated using a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wavepackets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficient.

  5. Wave packet dynamics under effect of a pulsed electric field

    Science.gov (United States)

    da Silva, A. R. C. B.; de Moura, F. A. B. F.; Dias, W. S.

    2016-06-01

    We studied the dynamics of an electron in a crystalline one-dimensional model under effect of a time-dependent Gaussian field. The time evolution of an initially Gaussian wave packet it was obtained through the numerical solution of the time-dependent Schrödinger equation. Our analysis consists of computing the electronic centroid as well as the mean square displacement. We observe that the electrical pulse is able to promote a special kind of displacement along the chain. We demonstrated a direct relation between the group velocity of the wave packet and the applied electrical pulses. We compare those numerical calculations with a semi-classical approach.

  6. Observer-based H∞ control over packet dropping networks

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new controller design problem of networked control systems with packet dropping is proposed. Depending on the place that the observer is put in the system, the network control systems with packet dropping are modeled as stochastic systems with the random variables satisfying the Bernoulli random binary distribution. The observer-based controller is designed to stabilize the networked system in the sense of mean square, and the prescribed H∞ disturbance attenuation level is achieved. The controller design problem is formulated as the feasibility of the convex optimization problem, which can be solved by a linear matrix inequality (LMI) approach. Numerical examples illustrate the effectiveness of the proposed methods.

  7. Wave packets and initial conditions in quantum cosmology

    CERN Document Server

    Gousheh, S S

    2000-01-01

    We discuss the construction of wave packets resulting from the solutions of a class of Wheeler-DeWitt equations in Robertson-Walker type cosmologies. We present an ansatz for the initial conditions which leads to a unique determination of the expansion coefficients in the construction of the wave packets with probability distributions which, in an interesting contrast to some of the earlier works, agree well with all possible classical paths. The possible relationship between these initial conditions and signature transition in the context of classical cosmology is also discussed.

  8. Multicasting in a WDM-upgraded Resilient Packet Ring

    Science.gov (United States)

    Scheutzow, Michael; Seeling, Patrick; Maier, Martin; Reisslein, Martin

    2007-05-01

    The recently approved IEEE 802.17 Resilient Packet Ring (RPR) network deteriorates under multicast traffic to legacy ring technologies that do not support spatial reuse. We extend our multicast approach with spatial reuse from a currently single-channel RPR to WDM-upgraded multichannel RPR networks, where each node can transmit packets on all wavelengths and receive on one wavelength, and analyze their multicast capacity. Our analysis provides a convenient method for evaluating the multicast and reception capacities of WDM-upgraded RPR networks for a wide range of uniform unicast, multicast, and broadcast traffic scenarios.

  9. Symmetry and conservation laws in semiclassical wave packet dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Tomoki, E-mail: tomoki@utdallas.edu [Department of Mathematical Sciences, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, Texas 75080-3021 (United States)

    2015-03-15

    We formulate symmetries in semiclassical Gaussian wave packet dynamics and find the corresponding conserved quantities, particularly the semiclassical angular momentum, via Noether’s theorem. We consider two slightly different formulations of Gaussian wave packet dynamics; one is based on earlier works of Heller and Hagedorn and the other based on the symplectic-geometric approach by Lubich and others. In either case, we reveal the symplectic and Hamiltonian nature of the dynamics and formulate natural symmetry group actions in the setting to derive the corresponding conserved quantities (momentum maps). The semiclassical angular momentum inherits the essential properties of the classical angular momentum as well as naturally corresponds to the quantum picture.

  10. Short-time Chebyshev wave packet method for molecular photoionization

    Science.gov (United States)

    Sun, Zhaopeng; Zheng, Yujun

    2016-08-01

    In this letter we present the extended usage of short-time Chebyshev wave packet method in the laser induced molecular photoionization dynamics. In our extension, the polynomial expansion of the exponential in the time evolution operator, the Hamiltonian operator can act on the wave packet directly which neatly avoids the matrix diagonalization. This propagation scheme is of obvious advantages when the dynamical system has large Hamiltonian matrix. Computational simulations are performed for the calculation of photoelectronic distributions from intense short pulse ionization of K2 and NaI which represent the Born-Oppenheimer (BO) model and Non-BO one, respectively.

  11. Electron acceleration by Landau resonance with whistler mode wave packets

    Science.gov (United States)

    Gurnett, D. A.; Reinleitner, L. A.

    1983-01-01

    Recent observations of electrostatic waves associated with whistler mode chorus emissions provide evidence that electrons are being trapped by Landau resonance interactions with the chorus. In this paper, the trapping, acceleration and escape of electrons in Landau resonance with a whistler mode wave packet are discussed. It is shown that acceleration can occur by both inhomogeneous and dispersive effects. The maximum energy gained is controlled by the points where trapping and escape occur. Large energy changes are possible if the frequency of the wave packet or the magnetic field strength increase between the trapping and escape points. Various trapping and escape mechanisms are discussed.

  12. Forward Instrumentation for ILC Detectors

    CERN Document Server

    Abramowicz, Halina; Afanaciev, Konstantin; Aguilar, Jonathan; Ambalathankandy, Prasoon; Bambade, Philip; Bergholz, Matthias; Bozovic-Jelisavcic, Ivanka; Castro, Elena; Chelkov, Georgy; Coca, Cornelia; Daniluk, Witold; Dragone, Angelo; Dumitru, Laurentiu; Elsener, Konrad; Emeliantchik, Igor; Fiutowski, Tomasz; Gostkin, Mikhail; Grah, Christian; Grzelak, Grzegorz; Haller, Gunter; Henschel, Hans; Ignatenko, Alexandr; Idzik, Marek; Ito, Kazutoshi; Jovin, Tatjana; Kielar, Eryk; Kotula, Jerzy; Krumstein, Zinovi; Kulis, Szymon; Lange, Wolfgang; Lohmann, Wolfgang; Levy, Aharon; Moszczynski, Arkadiusz; Nauenberg, Uriel; Novgorodova, Olga; Ohlerich, Marin; Orlandea, Marius; Oleinik, Gleb; Oliwa, Krzysztof; Olshevski, Alexander; Pandurovic, Mila; Pawlik, Bogdan; Przyborowski, Dominik; Sato, Yutaro; Sadeh, Iftach; Sailer, Andre; Schmidt, Ringo; Schumm, Bruce; Schuwalow, Sergey; Smiljanic, Ivan; Swientek, Krzysztof; Takubo, Yosuke; Teodorescu, Eliza; Wierba, Wojciech; Yamamoto, Hitoshi; Zawiejski, Leszek; Zhang, Jinlong

    2010-01-01

    Two special calorimeters are foreseen for the instrumentation of the very forward region of the ILC detector, a luminometer designed to measure the rate of low angle Bhabha scattering events with a precision better than 10-3 and a low polar angle calorimeter, adjacent to the beam-pipe. The latter will be hit by a large amount of beamstrahlung remnants. The amount and shape of these depositions will allow a fast luminosity estimate and the determination of beam parameters. The sensors of this calorimeter must be radiation hard. Both devices will improve the hermeticity of the detector in the search for new particles. Finely segmented and very compact calorimeters will match the requirements. Due to the high occupancy fast front-end electronics is needed. The design of the calorimeters developed and optimised with Monte Carlo simulations is presented. Sensors and readout electronics ASICs have been designed and prototypes are available. Results on the performance of these major components are summarised.

  13. Forward instrumentation for ILC detectors

    Science.gov (United States)

    Abramowicz, H.; Abusleme, A.; Afanaciev, K.; Aguilar, J.; Ambalathankandy, P.; Bambade, P.; Bergholz, M.; Bozovic-Jelisavcic, I.; Castro, E.; Chelkov, G.; Coca, C.; Daniluk, W.; Dragone, A.; Dumitru, L.; Elsener, K.; Emeliantchik, I.; Fiutowski, T.; Gostkin, M.; Grah, C.; Grzelak, G.; Haller, G.; Henschel, H.; Ignatenko, A.; Idzik, M.; Ito, K.; Jovin, T.; Kielar, E.; Kotula, J.; Krumstein, Z.; Kulis, S.; Lange, W.; Lohmann, W.; Levy, A.; Moszczynski, A.; Nauenberg, U.; Novgorodova, O.; Ohlerich, M.; Orlandea, M.; Oleinik, G.; Oliwa, K.; Olshevski, A.; Pandurovic, M.; Pawlik, B.; Przyborowski, D.; Sato, Y.; Sadeh, I.; Sailer, A.; Schmidt, R.; Schumm, B.; Schuwalow, S.; Smiljanic, I.; Swientek, K.; Takubo, Y.; Teodorescu, E.; Wierba, W.; Yamamoto, H.; Zawiejski, L.; Zhang, J.

    2010-12-01

    Two special calorimeters are foreseen for the instrumentation of the very forward region of the ILC detector, a luminometer designed to measure the rate of low angle Bhabha scattering events with a precision better than 10-3 and a low polar angle calorimeter, adjacent to the beam-pipe. The latter will be hit by a large amount of beamstrahlung remnants. The amount and shape of these depositions will allow a fast luminosity estimate and the determination of beam parameters. The sensors of this calorimeter must be radiation hard. Both devices will improve the hermeticity of the detector in the search for new particles. Finely segmented and very compact calorimeters will match the requirements. Due to the high occupancy fast front-end electronics is needed. The design of the calorimeters developed and optimised with Monte Carlo simulations is presented. Sensors and readout electronics ASICs have been designed and prototypes are available. Results on the performance of these major components are summarised.

  14. Forward instrumentation for ILC detectors

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, H [Tel Aviv University, Tel Aviv (Israel); Abusleme, A [Stanford University, Stanford (United States); Afanaciev, K; Emeliantchik, I [NCPHEP, Minsk (Belarus); Aguilar, J; Ambalathankandy, P; Fiutowski, T [AGH University of Science and Technology, Cracow (Poland); Bambade, P [Laboratoire de l Accelerateur Lineaire, Orsay (France); Bergholz, M; Castro, E; Grah, C [DESY, Zeuthen (Germany); Bozovic-Jelisavcic, I [Vinca Institute of Nuclear Sciences, University of Belgrade (Serbia); Chelkov, G; Gostkin, M [JINR, Dubna (Russian Federation); Coca, C; Dumitru, L [IFIN-HH, Bucharest (Romania); Daniluk, W; Grzelak, G [INP PAN, Cracow (Poland); Dragone, A [SLAC, Menlo Park (United States); Elsener, K, E-mail: Wolfgang.Lohmann@desy.d [CERN, Geneva (Switzerland)

    2010-12-15

    Two special calorimeters are foreseen for the instrumentation of the very forward region of the ILC detector, a luminometer designed to measure the rate of low angle Bhabha scattering events with a precision better than 10{sup -3} and a low polar angle calorimeter, adjacent to the beam-pipe. The latter will be hit by a large amount of beamstrahlung remnants. The amount and shape of these depositions will allow a fast luminosity estimate and the determination of beam parameters. The sensors of this calorimeter must be radiation hard. Both devices will improve the hermeticity of the detector in the search for new particles. Finely segmented and very compact calorimeters will match the requirements. Due to the high occupancy fast front-end electronics is needed. The design of the calorimeters developed and optimised with Monte Carlo simulations is presented. Sensors and readout electronics ASICs have been designed and prototypes are available. Results on the performance of these major components are summarised.

  15. Error resilient H.264/AVC Video over Satellite for low Packet Loss Rates

    DEFF Research Database (Denmark)

    Aghito, Shankar Manuel; Forchhammer, Søren; Andersen, Jakob Dahl

    2007-01-01

    The performance of video over satellite is simulated. The error resilience tools of intra macroblock refresh and slicing are optimized for live broadcast video over satellite. The improved performance using feedback, using a cross- layer approach, over the satellite link is also simulated. The ne...... Inmarsat BGAN system at 256 kbit/s is used as test case. This systems operates at low loss rates guaranteeing a packet loss rate of not more than 10~3. For high-end applications as 'reporter-in-the-field' live broadcast, it is crucial to obtain high quality without increasing delay....

  16. Limiting Energy Consumption by Decreasing Packets Retransmissions in 5G Network

    Directory of Open Access Journals (Sweden)

    Łukasz Apiecionek

    2017-01-01

    Full Text Available This article presents the potential of using Multipath Transmission Control Protocol for limiting the energy consumption in 5G network. The number of errors occurring during packet transmissions and in effect the number of retransmissions affect the consumption of energy by the devices in the network. The paper analyzes the potential energy savings from implementing an algorithm for detecting problems and predicting the future retransmissions. Although this is the main object of the paper, it must be emphasized that the proposed method also allows increasing the speed of transmission and improving the security of the data and it is easy to implement in 5G networks.

  17. Synchronization, retiming and OTDM of an asynchronous 10 Gigabit Ethernet NRZ packet using a time lens for Terabit Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Laguardia Areal, Janaina; Mulvad, Hans Christian Hansen;

    2011-01-01

    An asynchronous 10G Ethernet packet is synchronized and retimed to a master clock using a time lens. The NRZ packet is converted into an RZ packet and multiplexed with a serial 1.28 Tb/s signal.......An asynchronous 10G Ethernet packet is synchronized and retimed to a master clock using a time lens. The NRZ packet is converted into an RZ packet and multiplexed with a serial 1.28 Tb/s signal....

  18. Forward Deployed Robotic Unit

    Science.gov (United States)

    Brendle, Bruce E., Jr.; Bornstein, Jonathan A.

    2000-07-01

    Forward Deployed Robotic Unit (FDRU) is a core science and technology objective of the US Army, which will demonstrate the impact of autonomous systems on all phases of future land warfare. It will develop, integrate and demonstrate technology required to achieve robotic and fire control capabilities for future land combat vehicles, e.g., Future Combat Systems, using a system of systems approach that culminates in a field demonstration in 2005. It will also provide the required unmanned assets and conduct the demonstration. Battle Lab Warfighting Experiments and data analysis required to understand the effects of unmanned assets on combat operations. The US Army Tank- Automotive & Armaments Command and the US Army Research Laboratory are teaming in an effort to leverage prior technology achievements in the areas of autonomous mobility, architecture, sensor and robotics system integration; advance the state-of-the-art in these areas; and to provide field demonstration/application of the technologies.

  19. IDMA: improving the defense against malicious attack for mobile ad hoc networks based on ARIP protocol

    Science.gov (United States)

    Peng, Chaorong; Chen, Chang Wen

    2008-04-01

    Malicious nodes are mounting increasingly sophisticated attacking operations on the Mobile Ad Hoc Networks (MANETs). This is mainly because the IP-based MANETs are vulnerable to attacks by various malicious nodes. However, the defense against malicious attack can be improved when a new layer of network architecture can be developed to separate true IP address from disclosing to the malicious nodes. In this paper, we propose a new algorithm to improve the defense against malicious attack (IDMA) that is based on a recently developed Assignment Router Identify Protocol (ARIP) for the clustering-based MANET management. In the ARIP protocol, we design the ARIP architecture based on the new Identity instead of the vulnerable IP addresses to provide the required security that is embedded seamlessly into the overall network architecture. We make full use of ARIP's special property to monitor gateway forward packets by Reply Request Route Packets (RREP) without additional intrusion detection layer. We name this new algorithm IDMA because of its inherent capability to improve the defense against malicious attacks. Through IDMA, a watching algorithm can be established so as to counterattack the malicious node in the routing path when it unusually drops up packets. We provide analysis examples for IDMA for the defense against a malicious node that disrupts the route discovery by impersonating the destination, or by responding with state of corrupted routing information, or by disseminating forged control traffic. The IDMA algorithm is able to counterattack the malicious node in the cases when the node lunch DoS attack by broadcast a large number of route requests, or make Target traffic congestion by delivering huge mount of data; or spoof the IP addresses and send forge packets with a fake ID to the same Target causing traffic congestion at that destination. We have implemented IDMA algorism using the GloMoSim simulator and have demonstrated its performance under a variety of

  20. Application of the Wavelet Packet Method in Discrimination Between Nuclear Explosion and Earthquake

    Institute of Scientific and Technical Information of China (English)

    Yang Xuanhui; Shen Ping; Liu Xiqiang; Zheng Zhizhen

    2004-01-01

    Although the CTBT (Comprehensive Nuclear Test-Ban Treaty) was passed in 1996, it is still necessary to develop new and highly efficient methods (Wu Zhongliang, Chen Yuntai, et al.,1993; Xu Shaoxie, et al. 1994; Richard L. Garwin, 1994) to monitor possible events. Many discrimination criteria (Xu Shaoxie, et al., 1994; Institute of Geophysics, Chinese Academy of Sciences, 1976; Richard L. Garwin, 1994) have been put forward since the 1950s. The results show that each of the existing criteria has its own limitation, but the seismological method is an important and efficient method in the discrimination between nuclear explosion and earthquake. Especially in recent years, because of the little and little equivalent as well as the increasing hiding steps used in the test, a number of more efficient seismological methods have been worked out. In this paper, a new discrimination method, the Wavelet Packet Component Ratio (WPCR) method, is put forward. This method makes full use of the difference in variation with time between the spectra of nuclear explosions and earthquakes. Its discrimination efficiency is rather high.

  1. 160 Gbit/s optical packet switching using a silicon chip

    DEFF Research Database (Denmark)

    Hu, Hao; Ji, Hua; Galili, Michael;

    2012-01-01

    We have successfully demonstrated 160 Gbit/s all-optical packet switching based on cross-phase modulation using a silicon chip. Error free performance is achieved for the 4-to-1 switched 160 Gbit/s packet....

  2. Massachusetts Bay - Internal Wave Packets Digitized from SAR Imagery and Intersected with Bathymetry

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery and intersected with bathymetry for Massachusetts Bay. The internal wave packets were...

  3. Massachusetts Bay - Internal Wave Packets Digitized from SAR Imagery and Intersected with Tidal Zones

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery and intersected with tidal zones for Massachusetts Bay. The internal wave packets were...

  4. A multi-ring optical packet and circuit integrated network with optical buffering.

    Science.gov (United States)

    Furukawa, Hideaki; Shinada, Satoshi; Miyazawa, Takaya; Harai, Hiroaki; Kawasaki, Wataru; Saito, Tatsuhiko; Matsunaga, Koji; Toyozumi, Tatuya; Wada, Naoya

    2012-12-17

    We newly developed a 3 × 3 integrated optical packet and circuit switch-node. Optical buffers and burst-mode erbium-doped fiber amplifiers with the gain flatness are installed in the 3 × 3 switch-node. The optical buffer can prevent packet collisions and decrease packet loss. We constructed a multi-ring optical packet and circuit integrated network testbed connecting two single-ring networks and a client network by the 3 × 3 switch-node. For the first time, we demonstrated 244 km fiber transmission and 5-node hopping of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10 Gigabit Ethernet frames on the testbed. Error-free (frame error rate < 1 × 10(-4)) operation was achieved with optical packets of various packet lengths. In addition, successful avoidance of packet collisions by optical buffers was confirmed.

  5. CCNA Experimental Environment Simulation with Cisco Packet Tracer%使用Cisco Packet Tracer模拟CCNA实验环境

    Institute of Scientific and Technical Information of China (English)

    王金恒; 王煜林

    2010-01-01

    Cisco Packet Tracer是一款由Cisco公司发布的网络辅助学习工具,它能够给思科课程爱好者提供一个设计、配置网络及排除网络故障的网络模拟环境.根据的实验需求,在Cisco Packet Tracer模拟器上设计了两个实用的CCNA实验拓朴,让思科学习者能够更好地学习网络.

  6. Forward Tracking in the ILD Detector

    CERN Document Server

    Glattauer, Robin; Lettenbichler, Jakob; Mitaroff, Winfried

    2012-01-01

    The reconstruction software for ILD is currently subject to a major revision, aiming at improving its accuracy, speed, efficiency and maintainability in time for the upcoming DBD Report. This requires replacing old code by novel methods for track search and fit, together with modern standards for interfaces and tools. Track reconstruction in the "forward region", defined by the silicon Forward Tracking Detector (FTD), relies heavily on a powerful stand-alone track search. The new software makes use of a Cellular Automaton, a Kalman filter, and a Hopfield Neural Network. We give an overview of the project, its methods and merits.

  7. Optical frame synchronizer for 10 G Ethernet packets aiming at 1 Tb/s OTDM Ethernet

    DEFF Research Database (Denmark)

    Hu, Hao; Palushani, Evarist; Laguardia Areal, Janaina;

    2010-01-01

    Synchronization of 10 G Ethernet packets to a local clock was demonstrated using a phase modulator and a SMF as retiming elements. Error free performances for the synchronized packets with different lengths were achieved.......Synchronization of 10 G Ethernet packets to a local clock was demonstrated using a phase modulator and a SMF as retiming elements. Error free performances for the synchronized packets with different lengths were achieved....

  8. Packet loss characteristics of IPTV-like traffic on residential links

    OpenAIRE

    2010-01-01

    Packet loss is one of the principal threats to quality of experience for IPTV systems. However, the packet loss characteristics of the residential access networks which carry IPTV are not widely understood. We present packet level measurements of streaming IPTV-like traffic over four residential access links, and describe the extent and nature of packet loss we encountered. We discuss the likely impact of these losses for IPTV traffic, and outline steps which can ameliorate this.

  9. Modeling and performance analysis of IP access interface in optical transmission networks with packet switching

    OpenAIRE

    Lackovic, Marko; Bungarzeanu, Cristian

    2006-01-01

    The article analyzes the influence of the Internet Protocol (IP) access interface on the packet loss probability and delay times in the optical packet switched network. The network and node model have been proposed, and the structure of the IP access interface, including assembler and holder, have been included in the analysis. It has been shown that the increase of the maximum optical packet sizes, as well as use of the holding feature as contention resolution mechanism, decrease the packet ...

  10. An Efficient handoff and buffer Management Scheme to Minimize Packet Loss Rate through Check-PointRetransmission in WiMAX 16m Networks

    Directory of Open Access Journals (Sweden)

    D.Karunkuzhali

    2012-05-01

    Full Text Available IEEE 802.16m standard redefined with many improvements on IEEE 802.16e standard to provide the best connectivity and to perform the error-free data transmission. In this paper we propose a buffer management system to reduce the packet loss rate during WiMax Communication where the internetworking involves designated distress regarding buffer range and traffic management. We evident that our proposed framework for 802.16m based network frames have efficient buffer management with effort from BS scheduler and subscriber station scheduler. These processes incur least bandwidth utilisation thereby reducing the transmission delay. All these domains were put forth through admission control (AC mechanism and a dynamic buffer allocation (DBA process which directly clears packet sizing and Buffer ranging. with accession from check point constraints where the left packets will be put into retransmission. Thereby it gives effective buffer management system with improved handoff standards between the sender BS and subscriber BS.

  11. Designs and algorithms for packet and content inspection

    NARCIS (Netherlands)

    Sourdis, I.

    2007-01-01

    This dissertation deals with essential issues pertaining to high performance processing for network security and deep packet inspection. The proposed solutions keep pace with the increasing number and complexity of known attack descriptions providing multi-Gbps processing rates. We advocate the use

  12. Construction of Multivariate Tight Framelet Packets Associated with Dilation Matrix

    Institute of Scientific and Technical Information of China (English)

    Firdous A Shah; Abdullah

    2015-01-01

    In this paper, we present a method for constructing multivariate tight framelet packets associated with an arbitrary dilation matrix using unitary extension principles.We also prove how to construct various tight frames for L2(Rd) by replac-ing some mother framelets.

  13. Weisskopf-Wigner model for wave packet excitation

    CERN Document Server

    Paloviita, A; Stenholm, S; Paloviita, Asta; Suominen, Kalle-Antti; Stenholm, Stig

    1997-01-01

    We consider a laser induced molecular excitation process as a decay of a single energy state into a continuum. The analytic results based on Weisskopf-Wigner approach and perturbation calculations are compared with numerical wave packet results. We find that the decay model describes the excitation process well within the expected parameter region.

  14. Application of Cellular Automata to Detection of Malicious Network Packets

    Science.gov (United States)

    Brown, Robert L.

    2014-01-01

    A problem in computer security is identification of attack signatures in network packets. An attack signature is a pattern of bits that characterizes a particular attack. Because there are many kinds of attacks, there are potentially many attack signatures. Furthermore, attackers may seek to avoid detection by altering the attack mechanism so that…

  15. Hardware packet pacing using a DMA in a parallel computer

    Science.gov (United States)

    Chen, Dong; Heidelberger, Phillip; Vranas, Pavlos

    2013-08-13

    Method and system for hardware packet pacing using a direct memory access controller in a parallel computer which, in one aspect, keeps track of a total number of bytes put on the network as a result of a remote get operation, using a hardware token counter.

  16. PACKET ROUTING ALGORITHM FOR LEO SATELLITE CONSTELLATION NETWORK

    Institute of Scientific and Technical Information of China (English)

    Wang Kaidong; Tian Bin; Yi Kechu

    2005-01-01

    A novel distributed packet routing algorithm for Low Earth Orbit (LEO) satellite networks based on spiderweb topology is presented. The algorithm gives the shortest path with very low computational complexity and without on-board routing tables, which is suitable and practical for on-board processing. Simulation results show its practicability and feasibility.

  17. Green partial packet recovery in wireless sensor networks

    KAUST Repository

    Daghistani, Anas

    2015-08-18

    Partial packet recovery is well known for increasing network throughput and reducing frame retransmissions. However, partial packet recovery methods in the literature are not energy-aware and hence they are not suitable for the battery powered wireless sensor motes. We propose Green-Frag, a novel adaptive partial packet recovery mechanism that is energy friendly. It can help prolonging the battery life of wireless sensor motes that are usually resource constrained. It dynamically partitions the frame into smaller blocks to avoid dropping the whole frame due to a single bit error. Also, Green-Frag is able to tolerate high interference and save energy by varying the transmit power based on channel quality and interference pattern. We experimentally evaluate the energy efficiency as well as goodput and delay of Green-Frag using our TelosB sensor mote testbed. We find that Green-Frag reduces energy consumption by 33% on average compared to the state of the art partial packet recovery scheme in the literature in the presence of Wi-Fi interference. In the worst case, this reduction in energy consumption comes at the cost of 10% reduction in goodput. Finally, Green-Frag reduces the latency by 22% on average compared to other static frame fragmentation schemes.

  18. Anti-Litter Curriculum Packet, Interdisciplinary, K-12.

    Science.gov (United States)

    Tillis, Richard

    This curriculum packet consists of 20 illustrated cards with 15 activities designed to create "positive feelings" about a clean environment. Activities range from picture coloring for younger students, to lessons such as the economic and health problems litter creates for older students. Objectives include encouraging anti-litter and…

  19. Analysis and implementation of packet preemption for Time Sensitive Networks

    DEFF Research Database (Denmark)

    Zhou, Zifan; Yan, Ying; Ruepp, Sarah Renée

    2017-01-01

    level simulation in Riverbed Modeler. The simulation is complemented by numerical analysis which provides the average queuing delay for both types of traffic (preemptable and express). Furthermore, the paper describes an approach to implement the packet preemption solution on an FPGA in VHDL, which...

  20. Time-lens based optical packet pulse compression and retiming

    DEFF Research Database (Denmark)

    Laguardia Areal, Janaina; Hu, Hao; Palushani, Evarist;

    2010-01-01

    This paper presents a new optical circuit that performs both pulse compression and frame synchronization and retiming. Our design aims at directly multiplexing several 10G Ethernet data packets (frames) to a high-speed OTDM link. This scheme is optically transparent and does not require clock...

  1. A CURRICULUM FOR ENGLISH, STUDENT PACKET, GRADE 7.

    Science.gov (United States)

    Nebraska Univ., Lincoln. Curriculum Development Center.

    THE SEVENTH-GRADE STUDENT PACKET, PRODUCED BY THE NEBRASKA CURRICULUM DEVELOPMENT CENTER, BEGINS WITH THE UNIT ENTITLED "THE MAKING OF STORIES" IN WHICH STUDENTS CONSIDER WRITERS' AUDIENCES AND METHODS OF COMPOSITION AND PRESENTATION. SUCH MATERIAL AS "A CHRISTMAS CAROL" AND SELECTIONS FROM "THE ODYSSEY,""BEOWULF,""HYMN TO HERMES," AND GRIMM'S…

  2. The Effect of Double Buffer Management in Packet Analysis of ...

    African Journals Online (AJOL)

    ISSN 1816-3378. The Effect of Double Buffer Management in Packet Analysis of Adhoc .... Temporary memory. 1 GBofRAM. NIC ... A URL is always a single, unbroken line of text with no spaces. Web browser ..... Files, data, music and video.

  3. Generic Multi–Packet Communication through Object Serialization

    NARCIS (Netherlands)

    Evers, L.; Lijding, M.E.M.; Kuper, J.

    2008-01-01

    Wireless sensor networks communication protocols and abstractions have remained fairly simple until now, dealing only with payloads the size of individual network packets. A method to transparently communicate variably sized data in a platform-agnostic manner may ease building energy-efficient and rob

  4. Application of Cellular Automata to Detection of Malicious Network Packets

    Science.gov (United States)

    Brown, Robert L.

    2014-01-01

    A problem in computer security is identification of attack signatures in network packets. An attack signature is a pattern of bits that characterizes a particular attack. Because there are many kinds of attacks, there are potentially many attack signatures. Furthermore, attackers may seek to avoid detection by altering the attack mechanism so that…

  5. Propagation of gravity wave packet near critical level

    Institute of Scientific and Technical Information of China (English)

    YUE Xianchang; YI Fan

    2005-01-01

    A couple of two-dimensional linear and fully nonlinear numerical models for compressible atmosphere are used to numerically study the propagation of the gravity wave packet into a mean wind shear. For a linear propagation wave packet, the critical level interactions are in good agreement with the linear critical level theory. The dynamically and convectively unstable regions are formed due to the critical level interaction of a finite-amplitude wave packet, but they would not break. The free exchange of potential energy with kinetic energy in the background atmosphere at rest ceases after entering the mean wind shear. However, it still goes on in the nonlinear propagation. It is shown that the nonlinear effects modify the mean flow markedly, reduce the momentum and energy propagation velocity and drop the elevation of the critical level.The gravity wave packet becomes unstable and breaks down into smaller scales in some regions. It expends much more kinetic energy than potential energy in the early phase of the breakdown. This means that the wave breakdown sets up due to the action of the shear instability rather than a convective one.

  6. An Efficient Conflict Detection Algorithm for Packet Filters

    Science.gov (United States)

    Lee, Chun-Liang; Lin, Guan-Yu; Chen, Yaw-Chung

    Packet classification is essential for supporting advanced network services such as firewalls, quality-of-service (QoS), virtual private networks (VPN), and policy-based routing. The rules that routers use to classify packets are called packet filters. If two or more filters overlap, a conflict occurs and leads to ambiguity in packet classification. This study proposes an algorithm that can efficiently detect and resolve filter conflicts using tuple based search. The time complexity of the proposed algorithm is O(nW+s), and the space complexity is O(nW), where n is the number of filters, W is the number of bits in a header field, and s is the number of conflicts. This study uses the synthetic filter databases generated by ClassBench to evaluate the proposed algorithm. Simulation results show that the proposed algorithm can achieve better performance than existing conflict detection algorithms both in time and space, particularly for databases with large numbers of conflicts.

  7. "Macbeth." A Play Packet To Accompany "Elementary, My Dear Shakespeare."

    Science.gov (United States)

    Engen, Barbara; Campbell, Joy

    Intended for use by elementary school teachers as a supplement to the book, "Elementary, My Dear Shakespeare," or for use by itself to produce one Shakespeare play, this play packet contains ready-to-reproduce materials for the production of "Macbeth." Materials include: staging suggestions for scenery, props, lighting, and…

  8. Energy Crisis: Libya's and Nigeria's Role. Resource Packet.

    Science.gov (United States)

    African-American Inst., New York, NY. School Services Div.

    This resource packet contains practical suggestions and resource materials to help secondary teachers teach about Libya's and Nigeria's roles in the energy crisis. Students become acquainted with the governments and cultures of the two countries, examine their social problems, and learn how the Libyan and Nigerian governments are using money from…

  9. Analysis Of Packets Delay In Wireless Data Networks

    Directory of Open Access Journals (Sweden)

    Krivchenkov Aleksandr

    2015-12-01

    Full Text Available The networks with wireless links for automation control applications traffic transmission when packets have small size and application payload is predictable are under consideration. Analytical model for packets delay on their propagation path through the network is proposed. Estimations for network architectures based on WiFi and Bluetooth wireless technologies are made. The specifications for physical layer 802.11 a/b/g/n and 802.15.1 are under consideration. Analytical and experimental results for delivered network bandwidth for different network architecture, traffic structure and wireless technologies were compared to validate that basic mechanisms are correctly taken into account in the model. It is shown that basic effects are taken into account and further accuracy “improvement” of the model will give not more than 5%. As a result that is important for automation control applications we have reliably received the lowest possible level for packets delay in one wireless link. For 802.11 it is of order of 0.2 ms, for 802.15.1 it is 1.25 ms and is true when application packet can be transferred by one data frame.

  10. Chirp dependence of wave packet motion in oxazine 1.

    Science.gov (United States)

    Malkmus, Stephan; Dürr, Regina; Sobotta, Constanze; Pulvermacher, Horst; Zinth, Wolfgang; Braun, Markus

    2005-11-24

    The motion of vibrational wave packets in the system oxazine 1 in methanol is investigated by spectrally resolved transient absorption spectroscopy. The spectral properties of the probe pulse from 600 to 700 nm were chosen to cover the overlap region where ground-state bleach and stimulated emission signals are detected. The spectral phase of the pump pulse was manipulated by a liquid crystal display based pulse-shaping setup. Chirped excitation pulses of negative and positive chirp can be used to excite vibrational modes predominantly in the ground or excited state, respectively. To distinguish the observed wave packets in oxazine 1 moving in the ground or excited state, spectrally resolved transient absorption experiments are performed for various values of the linear chirp of the pump pulses. The amplitudes of the wave packet motion show an asymmetric behavior with an optimum signal for a negative chirp of -0.75 +/- 0.2 fs/nm, which indicates that predominantly ground-state wave packets are observed.

  11. On the Effects of Heterogeneous Packet Lengths on Network Coding

    DEFF Research Database (Denmark)

    Compta, Pol Torres; Fitzek, Frank; Roetter, Daniel Enrique Lucani

    2014-01-01

    Random linear network coding (RLNC) has been shown to provide increased throughput, security and robustness for the transmission of data through the network. Most of the analysis and the demonstrators have focused on the study of data packets with the same size (number of bytes). This constitutes...

  12. Packet track and traceback mechanism against denial of service attacks

    Institute of Scientific and Technical Information of China (English)

    LI Li; SHEN Su-bin

    2008-01-01

    The denial of service attack is a main type of threat on the Internet today. On the basis of path identification (Pi) and Internet control message protocol (ICMP) traceback (iTrace) methods, a packet track and traceback mechanism is proposed, which features rapid response and high accuracy. In this scheme, routers apply packet marking scheme and send traceback messages, which enables the victim to design the path tree in peace time. During attack times the victim can trace attackers back within the path tree and perform rapid packet filtering using the marking in each packet. Traceback messages overcome Pi's limitation, wherein too much path information is lost in path identifiers; whereas path identifiers can be used to expedite the design of the path-tree, which reduces the high overhead in iTrace. Therefore, our scheme not only synthesizes the advantages but also compromises the disadvantages of the above two methods. Simulation results with NS-2 show the validity of our scheme.

  13. Energy Crisis: Libya's and Nigeria's Role. Resource Packet.

    Science.gov (United States)

    African-American Inst., New York, NY. School Services Div.

    This resource packet contains practical suggestions and resource materials to help secondary teachers teach about Libya's and Nigeria's roles in the energy crisis. Students become acquainted with the governments and cultures of the two countries, examine their social problems, and learn how the Libyan and Nigerian governments are using money from…

  14. Teacher Education Packet for Illinois Core Curriculum in Agriculture.

    Science.gov (United States)

    Hemp, Paul; Pepple, Jerry

    Developed for use by teacher educators or state staff, this teaching packet provides preservice or inservice training to teachers and prospective teachers on how to use the Illinois Core Curriculum in Agriculture. (It is recommended that copies of the Illinois core materials be available to the students.) Three problem areas are included:…

  15. Non-linear wave packet dynamics of coherent states

    Indian Academy of Sciences (India)

    J Banerji

    2001-02-01

    We have compared the non-linear wave packet dynamics of coherent states of various symmetry groups and found that certain generic features of non-linear evolution are present in each case. Thus the initial coherent structures are quickly destroyed but are followed by Schrödinger cat formation and revival. We also report important differences in their evolution.

  16. "Macbeth." A Play Packet To Accompany "Elementary, My Dear Shakespeare."

    Science.gov (United States)

    Engen, Barbara; Campbell, Joy

    Intended for use by elementary school teachers as a supplement to the book, "Elementary, My Dear Shakespeare," or for use by itself to produce one Shakespeare play, this play packet contains ready-to-reproduce materials for the production of "Macbeth." Materials include: staging suggestions for scenery, props, lighting, and costumes; a short…

  17. Scalable In-Band Optical Notch-Filter Labeling for Ultrahigh Bit Rate Optical Packet Switching

    DEFF Research Database (Denmark)

    Medhin, Ashenafi Kiros; Galili, Michael; Oxenløwe, Leif Katsuo

    2014-01-01

    with only 0.9-dB power penalty to achieve BER of 1E-9. Using the proposed labeling scheme, optical packet switching of 640 Gb/s data packets is experimentally demonstrated in which two data packets are labeled by making none and one spectral hole using a notch filter and are switched using a LiNbO$_3...

  18. What does it cost to deliver information using position-based beaconless forwarding protocols?

    KAUST Repository

    Bader, Ahmed

    2012-04-01

    Beaconless position-based forwarding protocols have recently evolved as a promising solution for packet forwarding in wireless sensor networks. Quite a few variants of this class of forwarding protocols have been proposed over the years. One common observation is that they have all been evaluated from the perspective of a single node. Although useful, but a solid understanding of the end-to-end performance is still necessary. In this paper, we shed light on the end-to-end performance of beaconless position-based protocols along three distinct dimensions: energy, latency, and back-off probability. The latter is used as a direct indicator of the network\\'s transport capacity. Consequently, we are able to provide an elaborate response to the question: what does it really cost to deliver a packet in a wireless sensor network using position-based beaconless forwarding protocols? In responding to this question, we highlighted the different performance tradeoffs inherent to beaconless position-based protocols. Furthermore, some operational recommendations are also provided. © 2012 IEEE.

  19. FuGeF: A Resource Bound Secure Forwarding Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Idris Abubakar Umar

    2016-06-01

    Full Text Available Resource bound security solutions have facilitated the mitigation of spatio-temporal attacks by altering protocol semantics to provide minimal security while maintaining an acceptable level of performance. The Dynamic Window Secured Implicit Geographic Forwarding (DWSIGF routing protocol for Wireless Sensor Network (WSN has been proposed to achieve a minimal selection of malicious nodes by introducing a dynamic collection window period to the protocol’s semantics. However, its selection scheme suffers substantial packet losses due to the utilization of a single distance based parameter for node selection. In this paper, we propose a Fuzzy-based Geographic Forwarding protocol (FuGeF to minimize packet loss, while maintaining performance. The FuGeF utilizes a new form of dynamism and introduces three selection parameters: remaining energy, connectivity cost, and progressive distance, as well as a Fuzzy Logic System (FLS for node selection. These introduced mechanisms ensure the appropriate selection of a non-malicious node. Extensive simulation experiments have been conducted to evaluate the performance of the proposed FuGeF protocol as compared to DWSIGF variants. The simulation results show that the proposed FuGeF outperforms the two DWSIGF variants (DWSIGF-P and DWSIGF-R in terms of packet delivery.

  20. Selective Jamming Attack Prevention Based on Packet Hiding Methods and Wormholes

    Directory of Open Access Journals (Sweden)

    Divya Ann Luke

    2014-06-01

    Full Text Available The wireless networks are more sensitive to the Denial-of-Service (DoS attacks. The existing system is based on Spread Spectrum (SS. This technique mainly focuses on an external threat model. In wireless network the communications between nodes take place through broadcast communication. That is why, if an attacker present within the network can easily eavesdrop the message sent by any node. The main attack present in the wireless network is the selective jamming attack. This type of attack mainly focuses a single node termed as target node. Attacker always tries to block the message sent by the target node. This leads to the Denial-of-Service attack. We are proposing a new method to prevent the selective jamming attack in an internalthreat model. A wormhole is used, which will generate an alarm to indicate the presence of jammer and sent IP address of jammer node to all other nodes in the network. Using a method called packet hiding, we can send message through the network even though a jammer is present. This method is based on the technique called Strong Hiding Commitment Scheme (SHCS. Here, the access point in a network region becomes the wormhole whenever it finds out any node that violates the rules in a particular network region. That node is then considered as a jammer node. The wormhole send s IP address of jammer to all other nodes. Wormhole then prevents the jamming activity of the jammer by encrypting the source ID of message along with the message packet.So that the jammer is unable to identify its target node and the source can forward its message safely through jammer node itself

  1. Forward physics at the LHC

    CERN Document Server

    de Roeck, Albert

    2004-01-01

    We discuss opportunities for forward physics at the LHC. We start with the classical forward physics topics, such as total arid elastic cross sections and general diffraction. Then we discuss the so called 'new forward physics' topics. The forward physics program at the LHC presently contains the following topics: soft and hard diffraction, parton saturation, BFKL/CCFM dynamics, proton structure, multi-parton scattering, disoriented chiral condensates, incoherent pion emission, centauro events, forward energy and particle flows/minimum bias event structure, two-photon interactions and peripheral collisions, forward physics in pA and AA collisions, and QED processes to determine the luminosity to O(1%) e.g. pp rightward arrow ppee, pp rightward arrow ppmumu.

  2. Secure and Reliable IPTV Multimedia Transmission Using Forward Error Correction

    Directory of Open Access Journals (Sweden)

    Chi-Huang Shih

    2012-01-01

    Full Text Available With the wide deployment of Internet Protocol (IP infrastructure and rapid development of digital technologies, Internet Protocol Television (IPTV has emerged as one of the major multimedia access techniques. A general IPTV transmission system employs both encryption and forward error correction (FEC to provide the authorized subscriber with a high-quality perceptual experience. This two-layer processing, however, complicates the system design in terms of computational cost and management cost. In this paper, we propose a novel FEC scheme to ensure the secure and reliable transmission for IPTV multimedia content and services. The proposed secure FEC utilizes the characteristics of FEC including the FEC-encoded redundancies and the limitation of error correction capacity to protect the multimedia packets against the malicious attacks and data transmission errors/losses. Experimental results demonstrate that the proposed scheme obtains similar performance compared with the joint encryption and FEC scheme.

  3. Forward energy measurement with CMS

    CERN Document Server

    Kheyn, Lev

    2016-01-01

    Energy flow is measured in the forward region of CMS at pseudorapidities up to 6.6 in pp interactions at 13 TeV with forward (HF) and very forward (CASTOR) calorimeters. The results are compared to model predictions. The CMS results at different center-of-mass energies are intercompared using pseudorapidity variable shifted by beam rapidity, thus studying applicability of hypothesis of limiting fragmentation.

  4. A Security Mechanism for Cluster-Based WSN against Selective Forwarding

    Directory of Open Access Journals (Sweden)

    Hai Zhou

    2016-09-01

    Full Text Available A wireless sensor network (WSN faces a number of outsider and insider attacks, and it is difficult to detect and defend against insider attacks. In particular, an insider selective-forwarding attack, in which the attackers select some of the received packets to drop, most threatens a WSN. Compared to a distributed WSN, a cluster-based WSN will suffer more losses, even the whole network’s destruction, if the cluster head is attacked. In this paper, a scheme solving the above issues is proposed with three types of nodes, the Cluster Head (CH, the Inspector Node (IN and Member Nodes (MNs. The IN monitors the CH’s transmission to protect the cluster against a selective-forwarding attack; the CH forwards packets from MNs and other CHs, and randomly checks the IN to ascertain if it works properly; and the MNs send the gathered data packets to the CH and evaluate the behaviors of the CH and IN based on their own reputation mechanism. The novelty of our scheme is that in order to take both the safety and the lifespan of a network into consideration, the composite reputation value (CRV including forwarding rate, detecting malicious nodes, and surplus energy of the node is utilized to select CH and IN under the new suggested network arrangement, and the use of a node’s surplus energy can balance the energy consumption of a node, thereby prolonging the network lifespan. Theoretical analysis and simulation results indicate that the proposed scheme can detect the malicious node accurately and efficiently, so the false alarm rate is lowered by 25.7% compared with Watchdog and the network lifespan is prolonged by 54.84% compared with LEACH (Low Energy Adaptive Clustering Hierarchy.

  5. A Security Mechanism for Cluster-Based WSN against Selective Forwarding.

    Science.gov (United States)

    Zhou, Hai; Wu, Yuanming; Feng, Li; Liu, Daolei

    2016-09-20

    A wireless sensor network (WSN) faces a number of outsider and insider attacks, and it is difficult to detect and defend against insider attacks. In particular, an insider selective-forwarding attack, in which the attackers select some of the received packets to drop, most threatens a WSN. Compared to a distributed WSN, a cluster-based WSN will suffer more losses, even the whole network's destruction, if the cluster head is attacked. In this paper, a scheme solving the above issues is proposed with three types of nodes, the Cluster Head (CH), the Inspector Node (IN) and Member Nodes (MNs). The IN monitors the CH's transmission to protect the cluster against a selective-forwarding attack; the CH forwards packets from MNs and other CHs, and randomly checks the IN to ascertain if it works properly; and the MNs send the gathered data packets to the CH and evaluate the behaviors of the CH and IN based on their own reputation mechanism. The novelty of our scheme is that in order to take both the safety and the lifespan of a network into consideration, the composite reputation value (CRV) including forwarding rate, detecting malicious nodes, and surplus energy of the node is utilized to select CH and IN under the new suggested network arrangement, and the use of a node's surplus energy can balance the energy consumption of a node, thereby prolonging the network lifespan. Theoretical analysis and simulation results indicate that the proposed scheme can detect the malicious node accurately and efficiently, so the false alarm rate is lowered by 25.7% compared with Watchdog and the network lifespan is prolonged by 54.84% compared with LEACH (Low Energy Adaptive Clustering Hierarchy).

  6. Adaptive Packet Buffering Algorithm Based on Priority and Traffic Throughput for Reducing Packet Loss in Fast Handover for Mobile IPv6

    Directory of Open Access Journals (Sweden)

    Anesa Maolod Omar Al-Najeh

    2012-07-01

    Full Text Available The packet loss has become an important issue to the research community, which needs to be addressed. In FMIPv6, Packet losses are significantly related to the handover latency and buffer size used for packet buffering. In the case of increased handover latency or decreased buffer size, packet losses will be increased. To solve the problem, we propose an adaptive packet buffering (APT algorithm based on priority of packets and traffic throughput in layer 3 (L3 were the packets are buffered by the predefined rule in the new access point during handover. This algorithm is designed to reduce packet loss in FMIPv6 and high level of throughput and low delay can be achieved through the proposed technique. To achieve a fair comparison with Adaptive Buffer Limit Tuning (ALT algorithm, we have implemented the APT algorithm in Omnet++ along with the FMIPv6 to develop the model and the algorithm. The results of the simulation study show that the proposed algorithm can reduce the packet loss as well as the delay.

  7. 1×4 Optical packet switching of variable length 640 Gbit/s data packets using in-band optical notch-filter labeling

    DEFF Research Database (Denmark)

    Medhin, Ashenafi Kiros; Kamchevska, Valerija; Galili, Michael;

    2014-01-01

    We experimentally perform 1×4 optical packet switching of variable length 640 Gbit/s OTDM data packets using in-band notch-filter labeling with only 2.7-dB penalty. Up to 8 notches are employed to demonstrate scalability of the labeling scheme to 1×256 switching operation.......We experimentally perform 1×4 optical packet switching of variable length 640 Gbit/s OTDM data packets using in-band notch-filter labeling with only 2.7-dB penalty. Up to 8 notches are employed to demonstrate scalability of the labeling scheme to 1×256 switching operation....

  8. Energy and Information Transfer Via Coherent Exciton Wave Packets

    Science.gov (United States)

    Zang, Xiaoning

    Electronic excitons are bound electron-hole states that are generated when light interacts with matter. Such excitations typically entangle with phonons and rapidly decohere; the resulting electronic state dynamics become diffusive as a result. However, if the exciton-phonon coupling can be reduced, it may be possible to construct excitonic wave packets that offer a means of efficiently transmitting information and energy. This thesis is a combined theory/computation investigation to design condensed matter systems which support the requisite coherent transport. Under the idealizing assumption that exciton-phonon entanglement could be completely suppressed, the majority of this thesis focuses on the creation and manipulation of exciton wave packets in quasi-one-dimensional systems. While each site could be a silicon quantum dot, the actual implementation focused on organic molecular assemblies for the sake of computational simplicity, ease of experimental implementation, potential for coherent transport, and promise because of reduced structural uncertainty. A laser design was derived to create exciton wave packets with tunable shape and speed. Quantum interference was then exploited to manipulate these packets to block, pass, and even dissociate excitons based on their energies. These developments allow exciton packets to be considered within the arena of quantum information science. The concept of controllable excitonic wave packets was subsequently extended to consider molecular designs that allow photons with orbital angular momentum to be absorbed to create excitons with a quasi-angular momentum of their own. It was shown that a well-defined measure of topological charge is conserved in such light-matter interactions. Significantly, it was also discovered that such molecules allow photon angular momenta to be combined and later emitted. This amounts to a new way of up/down converting photonic angular momentum without relying on nonlinear optical materials. The

  9. Wavelet packet based feature extraction and recognition of license plate characters

    Institute of Scientific and Technical Information of China (English)

    HUANG Wei; LU Xiaobo; LING Xiaojing

    2005-01-01

    To study the characteristics of license plate characters recognition, this paper proposes a method for feature extraction of license plate characters based on two-dimensional wavelet packet. We decompose license plate character images with two dimensional-wavelet packet and search for the optimal wavelet packet basis. This paper presents a criterion of searching for the optimal wavelet packet basis, and a practical algorithm. The obtained optimal wavelet packet basis is used as the feature of license plate character, and a BP neural network is used to classify the character.The testing results show that the proposed method achieved higher recognition rate than the traditional methods.

  10. Feasibility Study of Encoding Operational Mission Metadata into IPv6 Packet Headers

    Science.gov (United States)

    2008-03-01

    2tu tim e = ptf + ptu 2nd node transmits update and then packet onto next node update update update update update packet3 tim e = 2tf + tu tim e = 2tf...ptf + ptu 2nd node transmits update and then packet onto next node update update update update update packet3 tim e = 2tf + tu tim e = 2tf + 2tu...tim e = 0 tim e = tf tim e = tf + tu tim e = 2tf + tu tim e = ptf + (p-1)tu tim e = 2tf + 2tu tim e = ptf + ptu Intermediate node transmits packet

  11. Integrity Verification for SCADA Devices Using Bloom Filters and Deep Packet Inspection

    Science.gov (United States)

    2014-03-27

    packet is completely inspected the finished state is only cleared through a reset by the CPU. The Packet FIFO is the only non-custom designed hardware...Packet FIFO . This signal is provided to the core by the software running on the PowerPC CPU. After start goes high (logic ’1’) the block transitions...the block transitions to the Decode state. In this state, it reads the first 62 bytes of the packet from the Packet FIFO two bytes at a time. This takes

  12. Networked Estimation for Event-Based Sampling Systems with Packet Dropouts

    Directory of Open Access Journals (Sweden)

    Young Soo Suh

    2009-04-01

    Full Text Available This paper is concerned with a networked estimation problem in which sensor data are transmitted over the network. In the event-based sampling scheme known as level-crossing or send-on-delta (SOD, sensor data are transmitted to the estimator node if the difference between the current sensor value and the last transmitted one is greater than a given threshold. Event-based sampling has been shown to be more efficient than the time-triggered one in some situations, especially in network bandwidth improvement. However, it cannot detect packet dropout situations because data transmission and reception do not use a periodical time-stamp mechanism as found in time-triggered sampling systems. Motivated by this issue, we propose a modified event-based sampling scheme called modified SOD in which sensor data are sent when either the change of sensor output exceeds a given threshold or the time elapses more than a given interval. Through simulation results, we show that the proposed modified SOD sampling significantly improves estimation performance when packet dropouts happen.

  13. Reliable and Efficient Broadcasting in Asymmetric Mobile Ad Hoc Networks Using Minimized Forward Node List Algorithm

    Directory of Open Access Journals (Sweden)

    Marimuthu Murugesan

    2011-01-01

    Full Text Available Problem statement: Network wide broadcasting is a fundamental operation in ad hoc networks. In broadcasting, a source node sends a message to all the other nodes in the network. Unlike in a wired network, a packet transmitted by a node in ad hoc wireless network can reach all neighbors. Therefore, the total number of transmissions (Forwarding nodes used as the cost criterion for broadcasting. Approach: This study proposes a reliable and efficient broadcasting algorithm using minimized forward node list algorithm which uses 2-hop neighborhood information more effectively to reduce redundant transmissions in asymmetric Mobile Ad hoc networks that guarantees full delivery. Among the 1-hop neighbors of the sender, only selected forwarding nodes retransmit the broadcast message. Forwarding nodes are selected such a way that to cover the uncovered 2-hop neighbors. Results: Simulation results show that the proposed broadcasting algorithm provides high delivery ratio, low broadcast forward ratio, low overhead and minimized delay. Conclusion: In this study, reliable and efficient broadcasting algorithm in asymmetric Mobile Ad Hoc Networks using minimized forward node list algorithm has been proposed which provides low forward ratio, high delivery ratio while suppressing broadcast redundancy.

  14. Design of Scheduler in High Speed Packet Switching Networks%高速分组交换网络中调度器的设计

    Institute of Scientific and Technical Information of China (English)

    魏艳艳; 孟李林

    2012-01-01

    The rapid development of internet business puts forward higher request for the quality of service in the network, the queue scheduler of the high speed packet switching network can effectively provide the higher quality of service in the network. It uses hierarchical scheduling and four queue scheduling algorithms to realize the design of queue scheduler. What's more,it compares and analyses deeply advantages and disadvantages among kinds of scheduling algorithms in the queue scheduler, especially, improves and optimizes DRR scheduling algorithm. At last, It completes the simulation verification and circuit synthesis for the circuit design, and the results show that the scheduler can satisfy the higher quality of service of the network and can be applied to scheduler design of high speed packet switching network.%为了满足迅猛发展的网络业务对网络服务质量提出的更高要求,使用高速分组网络交换机中的队列调度器可以有效地提供高质量的网络服务.通过采用分级式队列调度和四种队列调度算法有效地实现了队列调度器的设计.并且深入地比较和分析了队列调度器中多种队列调度算法的优缺点,尤其是对DRR调度算法进行了优化和改进.最后,对所设计的电路进行了仿真验证和电路综合,结果表明该调度器可以满足网络对服务质量的更高要求,并且能够应用到高速分组交换网络的调度器设计中.

  15. Medicaid Moving Forward

    Data.gov (United States)

    U.S. Department of Health & Human Services — As the improvements to the Medicaid and CHIP programs brought about by the Affordable Care Act take full effect, the information provided in this section outlines...

  16. Detection techniques of selective forwarding attacks in wireless sensor networks: a survey

    CERN Document Server

    Sharma, Preeti; Saluja, Krishan Kumar

    2012-01-01

    The wireless sensor network has become a hot research area due its wide range of application in military and civilian domain, but as it uses wireless media for communication these are easily prone to security attacks. There are number of attacks on wireless sensor networks like black hole attack, sink hole attack, Sybil attack, selective forwarding attacks etc. in this paper we will concentrate on selective forwarding attacks In selective forwarding attacks, malicious nodes behave like normal nodes and selectively drop packets. The selection of dropping nodes may be random. Identifying such attacks is very difficult and sometimes impossible. In this paper we have listed up some detection techniques, which have been proposed by different researcher in recent years, there we also have tabular representation of qualitative analysis of detection techniques

  17. Towards Effective Trust-Based Packet Filtering in Collaborative Network Environments

    DEFF Research Database (Denmark)

    Meng, Weizhi; Li, Wenjuan; Kwok, Lam-For

    2017-01-01

    Overhead network packets are a big challenge for intrusion detection systems (IDSs), which may increase system burden, degrade system performance, and even cause the whole system collapse, when the number of incoming packets exceeds the maximum handling capability. To address this issue, packet...... filtration is considered as a promising solution, and our previous research efforts have proven that designing a trust-based packet filter was able to refine unwanted network packets and reduce the workload of a local IDS. With the development of Internet cooperation, collaborative intrusion detection...... compromised by insider attacks. In this paper, we adopt the existing CIDN framework and aim to apply a collaborative trust-based approach to reduce unwanted packets. More specifically, we develop a collaborative trust-based packet filter, which can be deployed in collaborative networks and be robust against...

  18. Enhanced real-time ECG coder for packetized telecardiology applications.

    Science.gov (United States)

    Alesanco, Alvaro; Olmos, Salvador; Istepanian, Robert S H; García, José

    2006-04-01

    A new real-time compression method for electrocardiogram (ECG) signals has been developed based on the wavelet transform approach. The method is specifically adaptable for packetized telecardiology applications. The signal is segmented into beats and a beat template is subtracted from them, producing a residual signal. Beat templates and residual signals are coded with a wavelet expansion. Compression is achieved by selecting a subset of wavelet coefficients. The number of selected coefficients depends on a threshold which has different definitions depending on the operational mode of the coder. Compression performance has been tested using a subset of ECG records from MIT-BIH Arrhythmia database. This method has been designed for real-time packetized telecardiology scenarios both in wired and wireless environments.

  19. Packet routing algorithm for polar orbit LEO satellite constellation network

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Broadband satellite networks are capable of providing global coverage and support various services. The networks constructed by Low Earth Orbit (LEO) satellite constellations have attracted great interests because of their short round-trip delays and wide bandwidths. A challenging problem is to develop a simple and efficient packet routing algorithm for the LEO satellite constellation network. This paper presents a SpiderWeb Topological Network (SWTN) and a distributed packet routing algorithm for the LEO satellite constellation network based on the SWTN. The algorithm gives the minimum propagation delay paths with low computational complexity and requires no routing tables, which is practical for on-board processing. The performance of the algorithm is demonstrated through simulations.

  20. Traffic analysis and signal processing in optical packet switched networks

    DEFF Research Database (Denmark)

    Fjelde, Tina

    2002-01-01

    Gbit/s demultiplexing and 2x10 to 20 Gbit/s multiplexing. Lastly, the IWC’s capabilities as an optical logic gate for enabling more complex signal processing are demonstrated and four applications hereof are discussed. Logic OR and AND are verified in full at 10 Gbit/s using PRBS sequences coupled......This thesis focuses on functionalities that are important for the realisation of future all-optical packet switched networks, and which may be implemented using the interferometric wavelength converter. The European IST research project DAVID, with the aim of demonstrating the feasibility of a Tbit....../s optical packet switched network exploiting the best of optics and electronics, is used as a thread throughout the thesis. An overview of the DAVID network architecture is given, focussing on the MAN and WAN architecture as well as the MPLS-based network hierarchy. Subsequently, the traffic performance...

  1. Wave packet dynamics in the optimal superadiabatic approximation

    CERN Document Server

    Betz, Volker; Manthe, Uwe

    2016-01-01

    We explain the concept of superadiabatic approximations and show how in the context of the Born- Oppenheimer approximation they lead to an explicit formula that can be used to predict transitions at avoided crossings. Based on this formula, we present a simple method for computing wave packet dynamics across avoided crossings. Only knowledge of the adiabatic electronic energy levels near the avoided crossing is required for the computation. In particular, this means that no diabatization procedure is necessary, the adiabatic energy levels can be computed on the fly, and they only need to be computed to higher accuracy when an avoided crossing is detected. We test the quality of our method on the paradigmatic example of photo-dissociation of NaI, finding very good agreement with results of exact wave packet calculations.

  2. Modelling of packet traffic with matrix analytic methods

    DEFF Research Database (Denmark)

    Andersen, Allan T.

    1995-01-01

    scenario was modelled using Markovian models. The Ordinary Differential Equations arising from these models were solved numerically. The results obtained seemed very similar to those obtained using a different method in previous work by Akinpelu & Skoog 1985. Recent measurement studies of packet traffic...... process. A heuristic formula for the tail behaviour of a single server queue fed by a superposition of renewal processes has been evaluated. The evaluation was performed by applying Matrix Analytic methods. The heuristic formula has applications in the Call Admission Control (CAC) procedure of the future...... network services i.e. 800 and 900 calls and advanced mobile communication services. The Markovian Arrival Process (MAP) has been used as a versatile tool to model the packet arrival process. Applying the MAP facilitates the use of Matrix Analytic methods to obtain performance measures associated...

  3. Stochastic Acceleration of Ions Driven by Pc1 Wave Packets

    Science.gov (United States)

    Khazanov, G. V.; Sibeck, D. G.; Tel'nikhin, A. A.; Kronberg, T. K.

    2015-01-01

    The stochastic motion of protons and He(sup +) ions driven by Pc1 wave packets is studied in the context of resonant particle heating. Resonant ion cyclotron heating typically occurs when wave powers exceed 10(exp -4) nT sq/Hz. Gyroresonance breaks the first adiabatic invariant and energizes keV ions. Cherenkov resonances with the electrostatic component of wave packets can also accelerate ions. The main effect of this interaction is to accelerate thermal protons to the local Alfven speed. The dependencies of observable quantities on the wave power and plasma parameters are determined, and estimates for the heating extent and rate of particle heating in these wave-particle interactions are shown to be in reasonable agreement with known empirical data.

  4. Particle-like wave packets in complex scattering systems

    CERN Document Server

    Gérardin, Benoît; Ambichl, Philipp; Prada, Claire; Rotter, Stefan; Aubry, Alexandre

    2016-01-01

    A wave packet undergoes a strong spatial and temporal dispersion while propagating through a complex medium. This wave scattering is often seen as a nightmare in wave physics whether it be for focusing, imaging or communication purposes. Controlling wave propagation through complex systems is thus of fundamental interest in many areas, ranging from optics or acoustics to medical imaging or telecommunications. Here, we study the propagation of elastic waves in a cavity and a disordered waveguide by means of laser interferometry. We demonstrate how the direct experimental access to the information stored in the scattering matrix of these systems allows us to selectively excite scattering states and wave packets that travel along individual classical trajectories. Due to their limited dispersion, these particle-like scattering states will be crucially relevant for all applications involving selective wave focusing and efficient information transfer through complex media.

  5. The Formation of Packets of Hairpins in Shear Flows

    Science.gov (United States)

    Cohen, Jacob; Karp, Michael; Shukhman, Ilia

    2009-11-01

    In the present work we utilize a recently developed new method in an attempt to understand the generation of packets of hairpin vortices from a pair of counter rotating streamwise vortices embedded in uniform shear flow. This analytical-based solution method is capable of following (numerically) the evolution of finite-amplitude localized vortical disturbances embedded in shear flows. Due to their localization in space, the surrounding base flow is assumed to have homogeneous shear to leading order. The method can solve in a novel way the interaction between a general family of unbounded planar homogeneous shear flows and any localized disturbance. The solution is carried out using Lagrangian variables in Fourier space which is convenient and enables fast computations. The revealed mechanism for generation of packets of hairpins seems to be universal and has been observed in the past both in fully developed wall-bounded shear flows as well as in wall-bounded transitional shear flows.

  6. Service Time Analysis for Secondary Packet Transmission with Adaptive Modulation

    KAUST Repository

    Wang, Wen-Jing

    2017-05-12

    Cognitive radio communications can opportunistically access underutilized spectrum for emerging wireless applications. With interweave cognitive implementation, secondary user transmits only if primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission time and waiting time. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary system. In this paper, we study the EDT of secondary packet transmission with adaptive modulation under interweave implementation to facilitate the delay and throughput analysis of such cognitive radio system. In particular, we propose an analytical framework to derive the probability density functions of EDT considering random-length transmission and waiting slots. We also present selected numerical results to illustrate the mathematical formulations and to verify our analytical approach.

  7. Reconfigurable Data Communications Packet-Switch Emulation Test Bed Demonstrated

    Science.gov (United States)

    Chu, Pong P.; Jones, Robert E.

    1999-01-01

    The Communications Technology Division at the NASA Lewis Research Center has an ongoing program to develop advanced switching and routing technology concepts for future satellite onboard processing systems. Through a university grant as a part of this research, the Cleveland State University is using a flexible reconfigurable data communications packet switch emulation test bed to investigate packet switching techniques. Because of the switching speed and protocol complexity, implementing a data communications network is a tremendous task. Various alternatives should be carefully studied and evaluated in the development stage so that the optimal system configuration can be obtained and implemented later. Therefore, it is desirable to predict the performance of the network before it is actually constructed. This is especially true in the case of satellite systems. In the past, theoretical analysis, software simulation, and prototyping were used to evaluate performance. However, each method has its drawback. There are basic tradeoffs among accuracy, cost, and required evaluation time. No method is completely satisfactory.

  8. Wavelet packet transform-based robust video watermarking technique

    Indian Academy of Sciences (India)

    Gaurav Bhatnagar; Balasubrmanian Raman

    2012-06-01

    In this paper, a wavelet packet transform (WPT)-based robust video watermarking algorithm is proposed. A visible meaningful binary image is used as the watermark. First, sequent frames are extracted from the video clip. Then, WPT is applied on each frame and from each orientation one sub-band is selected based on block mean intensity value called robust sub-band. Watermark is embedded in the robust sub-bands based on the relationship between wavelet packet coefficient and its 8-neighbour $(D_8)$ coefficients considering the robustness and invisibility. Experimental results and comparison with existing algorithms show the robustness and the better performance of the proposed algorithm.

  9. Evaluation of packet loss impairment on streaming video

    Institute of Scientific and Technical Information of China (English)

    RUI Hua-xia; LI Chong-rong; QIU Sheng-ke

    2006-01-01

    Video compression technologies are essential in video streaming application because they could save a great amount of network resources. However compressed videos are also extremely sensitive to packet loss which is inevitable in today's best effort IP network. Therefore we think accurate evaluation of packet loss impairment on compressed video is very important. In this work, we develop an analytic model to describe these impairments without the reference of the original video (NR) and propose an impairment metric based on the model, which takes into account both impairment length and impairment strength. To evaluate an impaired frame or video, we design a detection and evaluation algorithm (DE algorithm) to compute the above metric value. The DE algorithm has low computational complexity and is currently being implemented in the real-time monitoring module of our HDTV over IP system. The impairment metric and DE algorithm could also be used in adaptive system or be used to compare diffeient error concealment strategies.

  10. SDN architecture for optical packet and circuit integrated networks

    Science.gov (United States)

    Furukawa, Hideaki; Miyazawa, Takaya

    2016-02-01

    We have been developing an optical packet and circuit integrated (OPCI) network, which realizes dynamic optical path, high-density packet multiplexing, and flexible wavelength resource allocation. In the OPCI networks, a best-effort service and a QoS-guaranteed service are provided by employing optical packet switching (OPS) and optical circuit switching (OCS) respectively, and users can select these services. Different wavelength resources are assigned for OPS and OCS links, and the amount of their wavelength resources are dynamically changed in accordance with the service usage conditions. To apply OPCI networks into wide-area (core/metro) networks, we have developed an OPCI node with a distributed control mechanism. Moreover, our OPCI node works with a centralized control mechanism as well as a distributed one. It is therefore possible to realize SDN-based OPCI networks, where resource requests and a centralized configuration are carried out. In this paper, we show our SDN architecture for an OPS system that configures mapping tables between IP addresses and optical packet addresses and switching tables according to the requests from multiple users via a web interface. While OpenFlow-based centralized control protocol is coming into widespread use especially for single-administrative, small-area (LAN/data-center) networks. Here, we also show an interworking mechanism between OpenFlow-based networks (OFNs) and the OPCI network for constructing a wide-area network, and a control method of wavelength resource selection to automatically transfer diversified flows from OFNs to the OPCI network.

  11. Performance Characteristics of a Kernel-Space Packet Capture Module

    Science.gov (United States)

    2010-03-01

    a simple sniffer. Mar- tin Roesch first created Snort to gain experience with cross-platform libpcap development and to more easily see the...lightweight N2d capabil- ity. Also written by Martin Roesch , DaemonLogger is a libpcap-based capture service with an extremely straightforward and...space, libpcap-based packet capture applica- tion written by Martin Roesch —author of the Snort Intrusion Detection Sys- tem. DaemonLogger provides a

  12. High Performance Fairness Algorithm for Resilient Packet Ring

    Institute of Scientific and Technical Information of China (English)

    Kangbok; Lee; Sangyeoun; Lee; Heyungsub; Lee; Hyeongho; Lee

    2003-01-01

    Resilient Packet Ring (RPR) is MAN technology with two counter-rotating rings that multiple stations share the bandwidth. The stations on ring must negotiate the allowed rate that they can transmit fairness eligible traffic based on the total amount of uncommitted bandwidth. RPR draft employs distributed bandwidth control algorithm in order to assure global fairness. In this paper, we suggest a new fairness control algorithm termed Congestion Distributed Fairness Algorithm (CDFA) that exhibits better pe...

  13. Lossless Compression of Data into Fixed-Length Packets

    Science.gov (United States)

    Kiely, Aaron B.; Klimesh, Matthew A.

    2009-01-01

    A computer program effects lossless compression of data samples from a one-dimensional source into fixed-length data packets. The software makes use of adaptive prediction: it exploits the data structure in such a way as to increase the efficiency of compression beyond that otherwise achievable. Adaptive linear filtering is used to predict each sample value based on past sample values. The difference between predicted and actual sample values is encoded using a Golomb code.

  14. Measurement and Evaluation Studies of Packet Radio Telecommunications Systems

    Science.gov (United States)

    2014-01-07

    terminals. Finite buffer space and FIFO transmission order are assumed at the repeaters. When there is a packet in its buffer for...against the FIFO algorithm in previous CAP protocol specifications C12D. The impact of network configuration is embedded in the specification of...scheduling algorithm can be parametrical1y selected as FIFO (CAP4)» CAP4.9 cyclic. or CAPS. The linear-backoff retransmission algorithm specified in

  15. Optical Packet Switching Scheme Using Multi-optical-code Labels

    Institute of Scientific and Technical Information of China (English)

    LI Shu-wen; ZHANG Qi; YU Chong-xiu; XIN Xiang-jun; XIONG Fei

    2009-01-01

    Proposed is a novel optical code(OC) label switching scheme in which an optical label is constructed by multiple parallel optical codes. The performances of splitting loss and BER are simulated and analyzed. Simulation results show that the proposed label can be correctly recognized to perform packet switching. Compared with reported schemes using one OC as a label, the splitting loss in our proposal is lowered.

  16. The performance analysis of linux networking - packet receiving

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wenji; Crawford, Matt; Bowden, Mark; /Fermilab

    2006-11-01

    The computing models for High-Energy Physics experiments are becoming ever more globally distributed and grid-based, both for technical reasons (e.g., to place computational and data resources near each other and the demand) and for strategic reasons (e.g., to leverage equipment investments). To support such computing models, the network and end systems, computing and storage, face unprecedented challenges. One of the biggest challenges is to transfer scientific data sets--now in the multi-petabyte (10{sup 15} bytes) range and expected to grow to exabytes within a decade--reliably and efficiently among facilities and computation centers scattered around the world. Both the network and end systems should be able to provide the capabilities to support high bandwidth, sustained, end-to-end data transmission. Recent trends in technology are showing that although the raw transmission speeds used in networks are increasing rapidly, the rate of advancement of microprocessor technology has slowed down. Therefore, network protocol-processing overheads have risen sharply in comparison with the time spent in packet transmission, resulting in degraded throughput for networked applications. More and more, it is the network end system, instead of the network, that is responsible for degraded performance of network applications. In this paper, the Linux system's packet receive process is studied from NIC to application. We develop a mathematical model to characterize the Linux packet receiving process. Key factors that affect Linux systems network performance are analyzed.

  17. Modelling Packet Departure Times using a Known PDF

    Directory of Open Access Journals (Sweden)

    Stanislav Klucik

    2014-01-01

    Full Text Available This paper deals with IPTV traffic source modelling and describes a packet generator based on a known probability density function which is measured and formed from a histogram. Histogram based probability density functions destroy an amount of information, because classes used to form the histogram often cover significantly more events than one. In this work, we propose an algorithm to generate far more output states of random variable X than the input probability distribution function is made from. In this generator is assumed that all IPTV packets of the same video stream are the same length. Therefore, only packet times are generated. These times are generated using the measured normalized histogram that is converted to a cumulative distribution function which acts as a finite number of states that can be addressed. To address these states we use an ON/OFF model that is driven by an uniform random number generator in (0, 1. When a state is chosen then the resulting value is equal to a histogram class. To raise the number of possible output states of the random variable X, we propose to use an uniform random number generator that generates numbers within the range of the chosen histogram class. This second uniform random number generator assures that the number of output states is far more larger than the number of histogram classes.

  18. An Adaptive Power Efficient Packet Scheduling Algorithm for Wimax Networks

    CERN Document Server

    Prasad, R Murali

    2010-01-01

    Admission control schemes and scheduling algorithms are designed to offer QoS services in 802.16/802.16e networks and a number of studies have investigated these issues. But the channel condition and priority of traffic classes are very rarely considered in the existing scheduling algorithms. Although a number of energy saving mechanisms have been proposed for the IEEE 802.16e, to minimize the power consumption of IEEE 802.16e mobile stations with multiple real-time connections has not yet been investigated. Moreover, they mainly consider non real- time connections in IEEE 802.16e networks. In this paper, we propose to design an adaptive power efficient packet scheduling algorithm that provides a minimum fair allocation of the channel bandwidth for each packet flow and additionally minimizes the power consumption. In the adaptive scheduling algorithm, packets are transmitted as per allotted slots from different priority of traffic classes adaptively, depending on the channel condition. Suppose if the buffer s...

  19. Hardware Accelerators Targeting a Novel Group Based Packet Classification Algorithm

    Directory of Open Access Journals (Sweden)

    O. Ahmed

    2013-01-01

    Full Text Available Packet classification is a ubiquitous and key building block for many critical network devices. However, it remains as one of the main bottlenecks faced when designing fast network devices. In this paper, we propose a novel Group Based Search packet classification Algorithm (GBSA that is scalable, fast, and efficient. GBSA consumes an average of 0.4 megabytes of memory for a 10 k rule set. The worst-case classification time per packet is 2 microseconds, and the preprocessing speed is 3 M rules/second based on an Xeon processor operating at 3.4 GHz. When compared with other state-of-the-art classification techniques, the results showed that GBSA outperforms the competition with respect to speed, memory usage, and processing time. Moreover, GBSA is amenable to implementation in hardware. Three different hardware implementations are also presented in this paper including an Application Specific Instruction Set Processor (ASIP implementation and two pure Register-Transfer Level (RTL implementations based on Impulse-C and Handel-C flows, respectively. Speedups achieved with these hardware accelerators ranged from 9x to 18x compared with a pure software implementation running on an Xeon processor.

  20. HTTP Packet Inspection Policy for Improvising Internal Network Security

    Directory of Open Access Journals (Sweden)

    Kuldeep Tomar

    2014-10-01

    Full Text Available Past few years the use of Internet and its applications has increased to a great extent. There is also an enormous growth in the establishment of computer networks by large, medium and small organizations, for data transfer and information exchange. Due to this huge growth, incidents of cyber-attacks and security breaches have also increased. Data on a network is transferred using protocols such as Hyper Text Transfer Protocol, which is very vulnerable. Many types of malicious contents are hidden in packets that are transferred over a network or system, which may can to get it slow, crash or buffer overflow etc. Thus it is very important to secure networks from such types of attacks. There are lots of mechanisms available but still they are not good enough because of dynamic environment. Such kind of attacks can be countered by applying appropriate policies on network edge devices like Adaptive Security Appliance, firewalls, web servers, router etc. Also the packets which are transferred between networks, they should deeply inspect for malicious or any insecure contents. In this paper firstly we would study Network security issues and available mechanism to counter them our focus would be on inspecting the HTTP packets deeply by applying policies on ASA. Finally we would use Graphical Network Simulator (GNS3 to test such a policy.