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Sample records for carrying tcp traffic

  1. Analytical Models for Energy Consumption in Infrastructure WLAN STAs Carrying TCP Traffic

    CERN Document Server

    Agrawal, Pranav; Kuri, Joy; Panda, Manoj; Navda, Vishnu; Ramjee, Ramachandran

    2009-01-01

    We develop analytical models for estimating the energy spent by stations (STAs) in infrastructure WLANs when performing TCP controlled file downloads. We focus on the energy spent in radio communication when the STAs are in the Continuously Active Mode (CAM), or in the static Power Save Mode (PSM). Our approach is to develop accurate models for obtaining the fraction of times the STA radios spend in idling, receiving and transmitting. We discuss two traffic models for each mode of operation: (i) each STA performs one large file download, and (ii) the STAs perform short file transfers. We evaluate the rate of STA energy expenditure with long file downloads, and show that static PSM is worse than just using CAM. For short file downloads we compute the number of file downloads that can be completed with given battery capacity, and show that PSM performs better than CAM for this case. We provide a validation of our analytical models using the NS-2 simulator. In contrast to earlier work on analytical modeling of P...

  2. Dynamics of TCP traffic over ATM networks

    Energy Technology Data Exchange (ETDEWEB)

    Floyd, S. [Lawrence Berkeley Lab., CA (United States). Information and Computing Sciences Div.; Romanow, A. [Sun Microsystems Inc., Mountain View, CA (United States)

    1994-08-01

    The authors investigate the performance of TCP (Transport Control Protocol) connections over ATM (Asynchronous Transfer Mode) networks without ATM-level congestion control, and compare it to the performance of TCP over packet-based networks. For simulations of congested networks, the effective throughput of TCP over ATM can be quite low when cells are dropped at the congested ATM switch. The low throughput is due to wasted bandwidth as the congested link transmits cells from ``corrupted`` packets, i.e., packets in which at least one cell is dropped by the switch. This fragmentation effect can be corrected and high throughput can be achieved if the switch drops whole packets prior to buffer overflow; they call this strategy Early Packet Discard. They also discuss general issues of congestion avoidance for best-effort traffic in ATM networks.

  3. Analysis of Malicious Traffic in Modbus/TCP Communications

    Science.gov (United States)

    Kobayashi, Tiago H.; Batista, Aguinaldo B.; Medeiros, João Paulo S.; Filho, José Macedo F.; Brito, Agostinho M.; Pires, Paulo S. Motta

    This paper presents the results of our analysis about the influence of Information Technology (IT) malicious traffic on an IP-based automation environment. We utilized a traffic generator, called MACE (Malicious trAffic Composition Environment), to inject malicious traffic in a Modbus/TCP communication system and a sniffer to capture and analyze network traffic. The realized tests show that malicious traffic represents a serious risk to critical information infrastructures. We show that this kind of traffic can increase latency of Modbus/TCP communication and that, in some cases, can put Modbus/TCP devices out of communication.

  4. Allocating Network Resources by Weight Between TCP Traffics

    Institute of Scientific and Technical Information of China (English)

    xU ChangBiao(徐昌彪); LONG KePing(隆克平); YANG ShiZhong(杨士中)

    2003-01-01

    Under the current TCP/IP architecture, all TCP traffics compete for networkresources completely fairly, which makes it difficult to satisfy applications' versatile communicationrequirements. This paper presents an improved TCP congestion control mechanism where thecongestion window becomes ω(1 - b)W rather than (1 - b)W for every window W containing apacket loss. Theoretical analysis and simulation results show that it can be easily implementedwith less additional overhead and can easily perform network resource allocation by weightedparameter w for traffics under the similar communication environments, which can efficiently leadto guaranteed relative quality of services and improve network performances.

  5. Identifying online traffic based on property of TCP flow

    Institute of Scientific and Technical Information of China (English)

    HONG Min-huo; GU Ren-tao; WANG Hong-xiang; SUN Yong-mei; JI Yue-feng

    2009-01-01

    Classification of network traffic using port-based or payload-based analysis is becoming increasingly difficult when many applications use dynamic port numbers, masquerading techniques, and encryption to avoid detection. In this article, an approach is presented for online traffic classification relying on the observation of the first n packets of a transmission control protocol (TCP) connection. Its key idea is to utilize the properties of the observed first ten packets of a TCP connection and Bayesian network method to build a classifier. This classifier can classify TCP flows dynamically as packets pass through it by deciding whether a TCP flow belongs to a given application. The experimental results show that the proposed approach performs well in online Internet traffic classification and that it is superior to naive Bayesian method.

  6. Revisiting multifractality of TCP traffic using multifractal detrended fluctuation analysis

    International Nuclear Information System (INIS)

    Understanding the characteristics of network traffic is critical to many network design and engineering problems, such as router buffer dimensioning and delay-sensitive service provisioning in the Internet backbone. We re-analyze the multifractal features of TCP traffic collections spanning 19 years by means of multifractal detrended fluctuation analysis. Through multifractal analysis, the generalized Hurst exponents and scaling exponents are derived. These results indicate that the TCP traffic is multifractal. The widths of the singularity spectrum show that the multifractal features of TCP traffic are weakened with increasing bandwidth and statistical multiplexing, but cannot be eliminated. In particular, comparing the generalized Hurst exponent of the original TCP traffic series with the shuffled and surrogate series, we conclude that the multifractal nature of TCP traffic is due to both long-range correlation and fat-tailed probability distributions. Moreover, the results show that the multifractality due to the correlation has a greater contribution than that from a fat-tailed probability distribution. (paper)

  7. Flow-aggregation Accelerating Strategy for TCP Traffic

    Directory of Open Access Journals (Sweden)

    Xiaoguo Zhang

    2014-06-01

    Full Text Available A great number of researches on network flow characteristics show a large proportion of the network flows are single-packet flows. However, almost all existing flow termination strategies have no optimization for single-packet flows, so the efficiency of flow-aggregation is lower. Based on in-depth study of flow characteristics and TCP protocol specifications, we find the packet status, packet arrival interval and SYN packet size can identify single-packet flows accurately, and then propose a flow-aggregation accelerating strategy for TCP traffic that aims to quickly identify single-packet flows. We build efficiency model and accuracy model to compare our strategy performance with others and make a lot of experiments on the traces collected from a main channel in the CERNET during the latest five years. The results prove our strategy can greatly improve the efficiency of flow-aggregation at the cost of very little loss of accuracy

  8. PERFORMANCE ANALYSIS OF ROUTING PROTOCOLS AND TCP VARIANTS UNDER HTTP AND FTP TRAFFIC IN MANETS

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    Ghassan A. QasMarrogy

    2014-12-01

    Full Text Available MANET stands for mobile ad-hoc network that has multi-hop and dynamic nature, where each station changes its location frequently and automatically configures itself. In this paper, four routing protocols that are OLSR, GRP, DSR, and AODV are discussed along with three TCP variants that are SACK, New Reno and Reno. The main focus of this paper is to study the impact scalability, mobility and traffic loads on routing protocols and TCP variants. The paper results shows that the proactive protocols OLSR and GRP outperform the reactive protocols AODV and DSR with the same nodes size, nodes speed, and traffic load. On the other hand, the TCP variants research reveal the superiority of the TCP SACK variant over the other two variants in case of adapting to varying network size, while the TCP Reno variant acts more robustly in varying mobility speeds and traffic loads

  9. TCP TRAFFIC PERFORMANCE IMPROVING IN LTE-A NETWORKS

    Institute of Scientific and Technical Information of China (English)

    Yang Bo; Wu Weimin; Zhu Guangxi; Yu Hongtao

    2013-01-01

    This paper presents a novel way to improve Transmission Control Protocol (TCP) performance of the users at the edge areas of the macro cells in Long Term Evolution Advanced (LTE-A) systems.Previous works on improving wireless TCP performance are reviewed and current considerations on TCP in LTE-A are explained.Howev5r,those solutions are neither too complex nor limited to some presuppositions which are too restricting for the deployment of LTE-A networks.In this paper a substituted TCP acknowledgement transmission scheme based on Automatic Repeat reQuest (ARQ) information in layer 2 is proposed.The simulation result shows that the proposed method can reduce the delay and improve the throughput of the edging users of the cell,as well as reducing radio resources in LTE-A macro cells.

  10. Parameter optimization in AQM controller design to support TCP traffic

    Science.gov (United States)

    Yang, Wei; Yang, Oliver W.

    2004-09-01

    TCP congestion control mechanism has been widely investigated and deployed on Internet in preventing congestion collapse. We would like to employ modern control theory to specify quantitatively the control performance of the TCP communication system. In this paper, we make use of a commonly used performance index called the Integral of the Square of the Error (ISE), which is a quantitative measure to gauge the performance of a control system. By applying the ISE performance index into the Proportional-plus-Integral controller based on Pole Placement (PI_PP controller) for active queue management (AQM) in IP routers, we can further tune the parameters for the controller to achieve an optimum control minimizing control errors. We have analyzed the dynamic model of the TCP congestion control under this ISE, and used OPNET simulation tool to verify the derived optimized parameters of the controllers.

  11. Integrated Proactive Admission Control Technique For both UDP And TCP Traffic Flows

    Directory of Open Access Journals (Sweden)

    Lakshmanan Senthilkumar

    2007-02-01

    Full Text Available Real time traffic adopting UDP at the transport layer needs some quality of service. It is offered through an admission control scheme. This paper adopts one such scheme which is extended for elastic traffics adopting TCP at the transport layer. The proposed scheme operates on reserving network resources on a proactive manner. It is based on the principle of telephone networks Erlang-B model. The blocking probability measured is used as a flow admission decision parameter. The effectiveness of the proposed admission control algorithm is determined here through simulation. It offers a fair admission rate to both UDP and TCP traffic flows. It also results in a better bottleneck link utilization at a comparatively lower overhead traffic.

  12. Robust control tools for traffic monitoring in TCP/AQM networks

    CERN Document Server

    Ariba, Yassine; Rahme, Sandy; Labit, Yann

    2009-01-01

    Several studies have considered control theory tools for traffic control in communication networks, as for example the congestion control issue in IP (Internet Protocol) routers. In this paper, we propose to design a linear observer for time-delay systems to address the traffic monitoring issue in TCP/AQM (Transmission Control Protocol/Active Queue Management) networks. Due to several propagation delays and the queueing delay, the set TCP/AQM is modeled as a multiple delayed system of a particular form. Hence, appropriate robust control tools as quadratic separation are adopted to construct a delay dependent observer for TCP flows estimation. Note that, the developed mechanism enables also the anomaly detection issue for a class of DoS (Denial of Service) attacks. At last, simulations via the network simulator NS-2 and an emulation experiment validate the proposed methodology.

  13. Performance analysis of TCP traffic and its influence on ONU's energy saving in energy efficient TDM-PON

    Science.gov (United States)

    Alaelddin, Fuad Yousif Mohammed; Newaz, S. H. Shah; Lee, Joohyung; Uddin, Mohammad Rakib; Lee, Gyu Myoung; Choi, Jun Kyun

    2015-12-01

    The majority of the traffic over the Internet is TCP based, which is very sensitive to packet loss and delay. Existing research efforts in TDM-Passive Optical Networks (TDM-PONs) mostly evaluate energy saving and traffic delay performances under different energy saving solutions. However, to the best of our knowledge, how energy saving mechanisms could affect TCP traffic performance in TDM-PONs has hardly been studied. In this paper, by means of our state-of-art OPNET Modular based TDM-PON simulator, we evaluate TCP traffic delay, throughput, and Optical Network Unit (ONU) energy consumption performances in a TDM-PON where energy saving mechanisms are employed in ONUs. Here, we study the performances under commonly used energy saving mechanisms defined in standards for TDM-PONs: cyclic sleep and doze mode. In cyclic sleep mode, we evaluate the performances under two well-known sleep interval length deciding algorithms (i.e. fixed sleep interval (FSI) and exponential sleep interval deciding (ESID)) that an OLT uses to decide sleep interval lengths for an ONU. Findings in this paper put forward the strong relationship among TCP traffic delay, throughput and ONU energy consumption under different sleep interval lengths. Moreover, we reveal that under high TCP traffic, both FSI and ESID will end up showing similar delay, energy and throughput performance. Our findings also show that doze mode can offer better TCP throughput and delay performance at the price of consuming more energy than cyclic sleep mode. In addition, our results provide a glimpse on understanding at what point doze mode becomes futile in improving energy saving of an ONU under TCP traffic. Furthermore, in this paper, we highlight important research issues that should be studied in future research to maximize energy saving in TDM-PONs while meeting traffic Quality of Service requirements.

  14. STUDY ON NONLINEAR DYNAMICS OF TCP-RENO TRAFFIC UNDER RED

    Institute of Scientific and Technical Information of China (English)

    Wang Li; Li Zengzhi; Xue Ke

    2006-01-01

    A discrete time feedback control system model based on a multi-router network has been presented. The model can be described by a set of recurrence equations. The numerical examples about the bifurcation of average and instantaneous queue size along with the variety of RED control parameter are shown. The simulate experiments about those of the RED control parameters are also presented. All of these results show that instability in TCP-Reno traffic under RED can be induced by the inherent nonlinear behavior of the network.

  15. Experimental Evaluation of Memory Effects on TCP Traffic in Congested Networks

    Directory of Open Access Journals (Sweden)

    Kulvinder Singh

    2010-09-01

    Full Text Available Today the Internet is a worldwide-interconnected computer network that transmits data by packet switching based on the TCP/IP protocol suite. Internet has TCP as the main protocol of the transport layer. The performance of TCP is studied by many researchers. They are trying to analytically characterizing the throughput of TCP's congestion control mechanism. Internet routers were widely believed to need big memory spaces. Commercial routers today have huge packet memory spaces, often storing millions of packets, under the assumption that big memory spaces lead to good statistical multiplexing and hence efficient use of expensive long-haul links. In this paper, we summarize the works and present the experimental study result with big memory space size and give a qualitative analysis of the result. Our conclusion is that the, round-trip time (RTT is not increased by linear, but by quadric when the memory space size of the bottleneck is big enough. Our goal is to estimate the average queue length of the memory space size and develop a TCP model based on RTT and the average queue length.

  16. STUDY ON NONLINEAR DYNAMICS OF TCP-RENO TRAFFIC UNDER RED

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The traditional net work management can tmeet the users requirements about quality of servicealong with the fast increasing of the scale of net-work.So service management has been proposed toguarantee the QoS of net work services and has beena hot topic in the research community for a fewyears now,and a lot of research has been carriedout[1-6].The net work traffic management is one ofthe key compositions of service management,andplays ani mportant role inthe QoS,congestion con-trol and net work design.The s...

  17. TCP Performance in Heterogeneous Wireless Networks

    OpenAIRE

    Sarolahti, Pasi

    2007-01-01

    The TCP protocol is used by most Internet applications today, including the recent mobile wireless terminals that use TCP for their World-Wide Web, E-mail and other traffic. The recent wireless network technologies, such as GPRS, are known to cause delay spikes in packet transfer. This causes unnecessary TCP retransmission timeouts. This dissertation proposes a mechanism, Forward RTO-Recovery (F-RTO) for detecting the unnecessary TCP retransmission timeouts and thus allow TCP to take appropri...

  18. A Flow-Level Performance Model for Mobile Networks Carrying Adaptive Streaming Traffic

    OpenAIRE

    Bonald, Thomas; Elayoubi, Salah-Eddine; Lin, Yu-Ting

    2015-01-01

    International audience This paper proposes a performance model for mobile networks carrying adaptive streaming traffic. The proposed model takes into account the flow dynamics in addition to the main parameters influencing the performance of adaptive streaming, such as the playout buffer and the video bit rates. We show how to compute several performance metrics like the average video bit rate, the deficit rate, defined as the probability of having an instantaneous throughput lower than th...

  19. Throughput Analysis in 802.11 WLANs using TCP

    Directory of Open Access Journals (Sweden)

    Chandra Mouli Venkata Srinivas, Akana

    2009-11-01

    Full Text Available There is a vast literature on the throughput analysis of the IEEE 802.11 media access control (MAC protocol. However, very little has been done on investigating the interplay between the collision avoidance mechanisms of the 802.11 MAC protocol and the dynamics of upper layer transport protocols. In this paper, we tackle this issue from an analytical perspective. Specifically, we develop Markov chain models to compute the distribution of the number of active stations in an 802.11 wireless local area network (WLAN when long-lived Transmission Control Protocol (TCP connections compete with finite-load User Datagram Protocol (UDP flows. By embedding these distributions in the MAC protocol modeling, we derive approximate but accurate expressions of the TCP and UDP throughput. We validate the model accuracy through performance tests carried out in a real WLAN for a wide range of configurations. Our analytical model and the supporting experimental outcomes show that 1 the total TCP t hroughput is basically independent of the number of open TCP connections and the aggregate TCP traffic can be equivalently modeled as two saturated flows and 2 in the saturated regime, n UDP flows obtain about n times the aggregate throughput achieved by the TCP flows, which is independent of the overall number of persistent TCP connections.

  20. Carry

    DEFF Research Database (Denmark)

    Koijen, Ralph S.J.; Moskowitz, Tobias J.; Heje Pedersen, Lasse;

    that include global equities, global bonds, currencies, commodities, US Treasuries, credit, and equity index options. This predictability underlies the strong returns to "carry trades" that go long high-carry and short low-carry securities, applied almost exclusively to currencies, but shown here...... with global recessions....

  1. Long-Haul TCP vs. Cascaded TCP

    OpenAIRE

    Feng, Wu-chun

    2006-01-01

    In this work, we investigate the bandwidth and transfer time of long-haul TCP versus cascaded TCP [5]. First, we discuss the models for TCP throughput. For TCP flows in support of bulk data transfer (i.e., long-lived TCP flows), the TCP throughput models have been derived [2, 3]. These models rely on the congestion-avoidance algorithm of TCP. Though these models cannot be applied with short-lived TCP connections, our interest relative to logistical networking is in longer-li...

  2. The Method of the Evaluation of the Efficiency of the Processes Carried Out at Traffic Maintenance Subsystem Posts

    Science.gov (United States)

    Migawa, Klaudiusz

    2012-12-01

    In the systems of the exploitation of means of transport in order to assure correct carrying out of the assigned transport tasks, it is necessary to maintain the required number of vehicles in the state of task availability. It is obtained as a result of carrying out of service and repair processes at the traffic maintenance subsystem posts. From the point of view of the effectiveness of the operation of the systems of the exploitation of means of transport, the damaged technological objects should be serviced in the shortest possible time. In the case of the system of the exploitation of means of transport the task of the traffic maintenance subsystem is the servicing of the required number of damaged means of transport over the assigned time interval defined by the transport task timetable. One of the methods of the evaluation of the degree of carrying out of the processes at the traffic maintenance subsystem posts is defining the efficiency of the posts of the subsystem. This paper presents the method of defining the efficiency of traffic maintenance subsystem in the system of the exploitation of means of transport measured by the probability value of servicing of the required number of technological objects over the assigned time interval. The resulting characteristics were presented on a general basis as well as in the form of exponential distribution and Erlang distribution. Moreover, for the utilization data obtained in tests carried out in an actual means of transport system the values of the analyzed characteristics were defined. The evaluation of the efficiency of the traffic maintenance subsystem posts may serve as the basis of decision making as to the change of the number and type of the used service and repair posts in the tested system as well as modification of the carried out exploitation strategy. The suggested method may be used for individual post, a group of posts of a given type as well as for a subsystem of traffic maintenance analyzed as a

  3. TCP-Rab:a receiver advertisement based TCP protocol

    Institute of Scientific and Technical Information of China (English)

    汤旭红; 刘正蓝; 朱淼良

    2004-01-01

    With the evolution of network technologies,the deficiencies of TCP protocol are becoming more and more distinct. The new TCP implementation,called Receiver Advertisement Based TCP(TCP-Rab)proposed here to eliminate these deficiencies,adopts two basic mechanisms:(1)Bandwidth Estimation and(2)Immediate Recovery. Bandwidth estimation is carried out at the receiver,and the result is sent back to the sender via the acknowledgments. Immediate Recovery guarantees high performance even in lossy link. Rab can distinguish the reason for packet loss,and thus adopt appropriate recovery strategy. For loss by network congestion,it will back off its congestion window,and for loss by link errors,it will recover the congestion window immediately. Simulations indicated that Rah has superiority over other TCP implementations.

  4. TCP-Rab: a receiver advertisement based TCP protocol

    Institute of Scientific and Technical Information of China (English)

    汤旭红; 刘正蓝; 朱淼良

    2004-01-01

    With the evolution of network technologies, the deficiencies of TCP protocol are becoming more and more distinct. The new TCP implementation, called Receiver Advertisement Based TCP (TCP-Rab) proposed here to eliminate these deficiencies, adopts two basic mechanisms: (1) Bandwidth Estimation and (2) Immediate Recovery. Bandwidth estimation is carried out at the receiver, and the result is sent back to the sender via the acknowledgments. Immediate Recovery guarantees high performance even in lossy link. Rab can distinguish the reason for packet loss, and thus adopt appropriate recovery strategy. For loss by network congestion, it will back off its congestion window, and for loss by link errors, it will recover the congestion window immediately. Simulations indicated that Rab has superiority over other TCP implementations.

  5. Performance evaluation of TCP over ABT protocols

    Science.gov (United States)

    Ata, Shingo; Murata, Masayuki; Miyahara, Hideo

    1998-10-01

    ABT is promising for effectively transferring a highly bursty data traffic in ATM networks. Most of past studies focused on the data transfer capability of ABT within the ATM layer. In actual, however, we need to consider the upper layer transport protocol since the transport layer protocol also supports a network congestion control mechanism. One such example is TCP, which is now widely used in the Internet. In this paper, we evaluate the performance of TCP over ABT protocols. Simulation results show that the retransmission mechanism of ABT can effectively overlay the TCP congestion control mechanism so that TCP operates in a stable fashion and works well only as an error recovery mechanism.

  6. Analytical Models for Dimensioning of OFDMA-based Cellular Networks Carrying VoIP and Best-Effort Traffic

    Directory of Open Access Journals (Sweden)

    Bruno Baynat

    2012-10-01

    Full Text Available The last years have seen an exponentially growing interest for mobile telecommunication services. As a consequence, a great diversity of applications is expected to be supported by cellular networks. To answer this ever increasing demand, the ITU-R defined the requirements that the fourth generation (4G of mobile standards must fulfill. Today, two especially promising candidates for 4G stand out: WiMAX and LTE. However, 4G cellular networks are still far from being implemented, and the high deployment costs render over-provisioning out of question. We thus propose in this paper accurate and convenient analytical models well-suited for the complex dimensioning of these promising access networks. Our main interest is WiMAX, yet, we show how our models can be easily used to consider LTE cells since both technologies are based on OFDMA. Generic Markovian models are developed specifically for three service classes defined in the WiMAX standard: UGS, ertPS and BE, respectively corresponding to VoIP, VoIP with silence suppression and best-effort traffic. First, we consider cells carrying either UGS, ertPS or BE traffic. Three methods to combine the previous models are then proposed to assume both UGS and BE traffic in the studied cell. Finally, we provide a way to easily integrate the ertPS traffic and obtain a UGS/ertPS/BE model able to account for multiple traffic profiles in each service class while keeping an instantaneous resolution. The proposed models are compared in depth with realistic simulations that show their accuracy. Lastly, we demonstrate through different examples how our models can be used to answer dimensioning issues which would be intractable with simulations.

  7. Historical and Contemporary Aspects of the Market for the Cargo Traffic carried on the Romanian Ports

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    Florin-Dan Puşcaciu

    2014-05-01

    Full Text Available We hereby try to approach some aspects about the port traffic, analyzing this activity from the marketing point of view, on the one side, and looking at the ports as entities which represented real emblems, symbols of economic and social development, cities like Galaţi, Brăila, Tulcea, being zones which were wholly identified with the port activity, on the other side. This analysis is necessary in the context of the favorable geographical placement of Romania, which benefits both of the Danube river road, and also the Black Sea. Despite of all these historical and geographic aspects, and also of some directions of developing the commercial Romanian fleet in the past period, the Danube ports are going on a regress stage. In order to catch the now on quantitative and qualitative changes over which are on this market, we consider necessary an incursion in the inter-war period, basing both on the tradition of these maritime and river ports, and on the assertion of Joseph Schumpeter as per which the economic aspects can be studied by history, theory and statistics. The conclusion of the study points to that the port activities estimated by the tonnage shipped in these sea-Danube ports regressed, and the Romanian fleet is now almost absent, non-existent. We firmly underline the necessity of a national strategy in this field.

  8. Investigation on TCP/IP Congestion Control in Optical Burst Switched (OBS Network

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    Ms. Payal Daryani

    2012-03-01

    Full Text Available Transport Control Protocol (TCP is the dominant protocol in modern communication networks, in which the issues of reliability, flow, and congestion control must be handled efficiently. In this review paper an analytical switching is used to exploit the huge bandwidth of optical fibers for future high speed internet backbone. It carries multiple packets, in their turn. Different aggregation schemes have been considered and evaluated.TCP performance greatly depends on the TCP congestion window behavior that is related to loss events occurring in the optical burst switched network, there is a special term called traffic shaping by which we control over the network according to the network load .that means we increase or decrease the send rate according to the network demand.

  9. Investigation on TCP/IP Congestion Control in Optical Burst Switched (OBS Network

    Directory of Open Access Journals (Sweden)

    Payal Daryani

    2012-03-01

    Full Text Available Transport Control Protocol (TCP is the dominant protocol in modern communication networks, in which the issues of reliability, flow, and congestion control must be handled efficiently. In this review paper an analytical switching is used to exploit the huge bandwidth of optical fibers for future high speed internet backbone. It carries multiple packets, in their turn. Different aggregation schemes have been considered and evaluated. TCP performance greatly depends on the TCP congestion window behavior that is related to loss events occurring in the optical burst switched network, there is a special term called traffic shaping by which we control over the network according to the network load .that means we increase or decrease the send rate according to the network demand.

  10. Researching Multipath TCP Adoption

    OpenAIRE

    Warma, Henna; Hämmäinen, Heikki

    2010-01-01

    International audience The adoption process of a new Internet protocol or only a change to an existing one is anything but trivial. The classical diffusion theory does not apply as such for studying protocol adoption because the deployment of a protocol usually requires the involvement of multiple stakeholders with varying interests. Multipath TCP (MPTCP) is a new interesting change to the TCP/IP protocol suite which is an extension to regular TCP. MPTCP exploits the idea of resource pooli...

  11. Analysis and Improvement of TCP Congestion Control Mechanism Based on Global Optimization Model

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Network flow control is formulated as a global optimization problem of user profit. A general global optimization flow control model is established. This model combined with the stochastic model of TCP is used to study the global rate allocation characteristic of TCP. Analysis shows when active queue manage ment is used in network TCP rates tend to be allocated to maximize the aggregate of a user utility function Us (called Us fairness). The TCP throughput formula is derived. An improved TCP congestion control mecha nism is proposed. Simulations show its throughput is TCP friendly when competing with existing TCP and its rate change is smoother. Therefore, it is suitable to carry multimedia applications.

  12. Characterizing End-to-End Delay Performance of Randomized TCP Using an Analytical Model

    Directory of Open Access Journals (Sweden)

    Mohammad Shorfuzzaman

    2016-03-01

    Full Text Available TCP (Transmission Control Protocol is the main transport protocol used in high speed network. In the OSI Model, TCP exists in the Transport Layer and it serves as a connection-oriented protocol which performs handshaking to create a connection. In addition, TCP provides end-to-end reliability. There are different standard variants of TCP (e.g. TCP Reno, TCP NewReno etc.which implement mechanisms to dynamically control the size of congestion window but they do not have any control on the sending time of successive packets. TCP pacing introduces the concept of controlling the packet sending time at TCP sources to reduce packet loss in a bursty traffic network. Randomized TCP is a new TCP pacing scheme which has shown better performance (considering throughput, fairness over other TCP variants in bursty networks. The end-to-end delay of Randomized TCP is a very important performance measure which has not yet been addressed. In the current high speed networks, it is increasingly important to have mechanisms that keep end-to-end to delay within an acceptable range. In this paper, we present the performance evaluation of end-to-end delay of Randomized TCP. To this end, we have used an analytical and a simulation model to characterize the end-to-end delay performance of Randomized TCP.

  13. A simulation-based study of HighSpeed TCP and its deployment

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Evandro de

    2003-04-29

    The current congestion control mechanism used in TCP has difficulty reaching full utilization on high speed links, particularly on wide-area connections. For example, the packet drop rate needed to fill a Gigabit pipe using the present TCP protocol is below the currently achievable fiber optic error rates. HighSpeed TCP was recently proposed as a modification of TCP's congestion control mechanism to allow it to achieve reasonable performance in high speed wide-area links. In this research, simulation results showing the performance of HighSpeed TCP and the impact of its use on the present implementation of TCP are presented. Network conditions including different degrees of congestion, different levels of loss rate, different degrees of bursty traffic and two distinct router queue management policies were simulated. The performance and fairness of HighSpeed TCP were compared to the existing TCP and solutions for bulk-data transfer using parallel streams.

  14. A comparative study of aggregate TCP retransmission rates

    CERN Document Server

    Pentikousis, Kostas; Andrade, Asha; 10.2316/Journal.202.2010.4.202-2660

    2011-01-01

    Segment retransmissions are an essential tool in assuring reliable end-to-end communication in the Internet. Their crucial role in TCP design and operation has been studied extensively, in particular with respect to identifying non-conformant, buggy, or underperforming behaviour. However, TCP segment retransmissions are often overlooked when examining and analyzing large traffic traces. In fact, some have come to believe that retransmissions are a rare oddity, characteristically associated with faulty network paths, which, typically, tend to disappear as networking technology advances and link capacities grow. We find that this may be far from the reality experienced by TCP flows. We quantify aggregate TCP segment retransmission rates using publicly available network traces from six passive monitoring points attached to the egress gateways at large sites. In virtually half of the traces examined we observed aggregate TCP retransmission rates exceeding 1%, and of these, about half again had retransmission rate...

  15. TCP throughput adaptation in WiMax networks using replicator dynamics.

    Science.gov (United States)

    Anastasopoulos, Markos P; Petraki, Dionysia K; Kannan, Rajgopal; Vasilakos, Athanasios V

    2010-06-01

    The high-frequency segment (10-66 GHz) of the IEEE 802.16 standard seems promising for the implementation of wireless backhaul networks carrying large volumes of Internet traffic. In contrast to wireline backbone networks, where channel errors seldom occur, the TCP protocol in IEEE 802.16 Worldwide Interoperability for Microwave Access networks is conditioned exclusively by wireless channel impairments rather than by congestion. This renders a cross-layer design approach between the transport and physical layers more appropriate during fading periods. In this paper, an adaptive coding and modulation (ACM) scheme for TCP throughput maximization is presented. In the current approach, Internet traffic is modulated and coded employing an adaptive scheme that is mathematically equivalent to the replicator dynamics model. The stability of the proposed ACM scheme is proven, and the dependence of the speed of convergence on various physical-layer parameters is investigated. It is also shown that convergence to the strategy that maximizes TCP throughput may be further accelerated by increasing the amount of information from the physical layer. PMID:20083460

  16. TCP throughput adaptation in WiMax networks using replicator dynamics.

    Science.gov (United States)

    Anastasopoulos, Markos P; Petraki, Dionysia K; Kannan, Rajgopal; Vasilakos, Athanasios V

    2010-06-01

    The high-frequency segment (10-66 GHz) of the IEEE 802.16 standard seems promising for the implementation of wireless backhaul networks carrying large volumes of Internet traffic. In contrast to wireline backbone networks, where channel errors seldom occur, the TCP protocol in IEEE 802.16 Worldwide Interoperability for Microwave Access networks is conditioned exclusively by wireless channel impairments rather than by congestion. This renders a cross-layer design approach between the transport and physical layers more appropriate during fading periods. In this paper, an adaptive coding and modulation (ACM) scheme for TCP throughput maximization is presented. In the current approach, Internet traffic is modulated and coded employing an adaptive scheme that is mathematically equivalent to the replicator dynamics model. The stability of the proposed ACM scheme is proven, and the dependence of the speed of convergence on various physical-layer parameters is investigated. It is also shown that convergence to the strategy that maximizes TCP throughput may be further accelerated by increasing the amount of information from the physical layer.

  17. Performance of TCP-Throughput on NS2 by Using Different Simulation Parameters

    Directory of Open Access Journals (Sweden)

    Dr. Neeraj Bhargava , Dr. Ritu Bhargava, Anchal Kumawat , Bharat Kumar

    2012-12-01

    Full Text Available ns2 is a discrete event simulator for networkingresearch, which works at the packet level. Here, wewill be using ns2 to simulate traffic congestion ofTCP and UDP packets inside a network. ns2 ispopularly used in the simulation of routing andmulticast protocols and is heavily used in ad-hocnetworking research. ns2 supports networkprotocols (TCP, UDP, HTTP, Routing algorithms,MAC etc. for offering simulation results for wiredand wireless networks. When using TCP to transferdata the two most important factors are the TCPwindow size and the round trip latency. This paperdeals the effect that the size of the flow controlwindow has on the throughput of a TCP connectionby using simulation parameters like-packet delay(sec, bandwidth, file-size (bytes and to implementnetwork fed with TCP traffic and backgroundtraffic. The objective of this paper is to observe theperformance of TCP

  18. TCP smart framing: a segmentation algorithm to reduce TCP latency

    OpenAIRE

    Mellia, Marco; Meo, Michela; Casetti, Claudio Ettore

    2005-01-01

    TCP Smart Framing, or TCP-SF for short, enables the Fast Retransmit/Recovery algorithms even when the congestion window is small. Without modifying the TCP congestion control based on the additive-increase/multiplicative-decrease paradigm, TCP-SF adopts a novel segmentation algorithm: while Classic TCP always tries to send full-sized segments, a TCP-SF source adopts a more flexible segmentation algorithm to try and always have a number of in-flight segments larger than 3 so as to enable Fast ...

  19. Study on Early Warning of Traffic Resources and Environment Carrying Capacity%交通资源环境承载力预警研究

    Institute of Scientific and Technical Information of China (English)

    蒋恵园; 黄永燊

    2015-01-01

    新常态下快速发展的综合交通运输对资源环境的胁迫作用日益明显,资源环境对交通运输的承载能力成为地区健康发展的重要衡量标准。在界定交通资源环境承载力概念的基础上,从资源承载力和生态环境承载力两个方面构建交通资源环境承载力指标体系。结合可拓学的模糊物元理论和信息论的熵理论,建立基于模糊物元的交通资源环境承载力的预警模型,并对长江经济带七省二市的交通资源环境承载力进行预警研究。实例结果表明,构建的交通资源环境承载力指标体系基本合理,模糊物元预警模型在资源环境承载力的预警研究中具有较强的适用性和可操作性。%The rapid development of integrated transportation in the new normal poses an increasing threat to environment and resources. The bearing capacity of environment and resources to transportation becomes a significant criterion to measure whether an area is developing healthily. Based on the definition of traffic resource environmental bearing capacity, a traffic resource and environmental bearing capacity index system is built from both resources carrying capacity and environmental carrying capacity aspects. Through combining fuzzy matter-element theory of extension theory with entropy theory, an early-warning model of traffic resource and environmental bearing capacity is established, this model is applied to study the traffic resources and environmental carrying capacity of Yangtze River economic belt (include seven provinces and two municipalities as well). The results demonstrate that:The traffic resources and environmental carrying capacity index system is reasonable and the fuzzy matter-element model used in studying the early-warning of resources environmental bearing capacity is of sound applicability and operability.

  20. Analysis of TCP performance in data center networks

    CERN Document Server

    Kulkarni, Santosh

    2014-01-01

    This book addresses the need to improve TCP’s performance inside data centers by providing solutions that are both practical and backward compatible with standard TCP versions. The authors approach this challenge first by deriving an analytical model for TCP’s performance under typical data center workload traffic.  They then discuss some solutions that are designed to improve TCP performance by either proactively detecting network congestion through probabilistic retransmission or by avoiding timeout penalty through dynamic resizing of TCP segments. Experimental results show that each of techniques discussed outperforms standard TCP inside a data center.  ·         Analyzes the reasons behind TCP performance slump inside data centers when operating under synchronized workload traffic; ·         Introduces solutions to TCP performance slump inside data centers that are both practical and backward compatible; ·         Describes mechanisms that are responsible for TCP’s relia...

  1. Performance Analysis of Different MANET Specific TCP variants

    Directory of Open Access Journals (Sweden)

    Debajyoti Pal

    2012-09-01

    Full Text Available - Transmission Control Protocol(TCP is implemented in the transport layer of a MANET, which enjoys the advantage of reliable data transmission over the Internet. However, due to certain unique characteristics of a MANET, modification of classical TCP has been done so as to improve its performance in such an environment. Accordingly, several MANET specific TCP versions like TCP Reno, TCP New Reno, TCP Tahoe and TCP Vegas have come into prominence. This paper evaluates the performance of the different TCP versions for the same network topology over certain fixed parameters like number of packets generated/node, average packet loss, average delay incurred by the packets while in transit from source to destination and the processing time taken by the intermediate nodes. For routing purpose, we have assumed Ad-HocOn Demand Distance Vector Routing (AODV as the standard. To address the common issues of congestion control as with TCP, the experiment has been carried out under different network loading conditions that have been achieved by slowly increasing the node density.

  2. Improving the Performance of Interactive TCP Applications using End-point Based and Network Level Techniques

    Directory of Open Access Journals (Sweden)

    Varun G Menon

    2012-04-01

    Full Text Available Recent measurement based studies reveal that most of the Internet connections are short in terms of the amount of traffic they carry, while a small fraction of the connections are carrying a largeportion of the traffic.. Most of these short flows are from interactive applications like telnet, gaming that use TCP protocol for connection establishment and data transfer. These short TCP flows suffer from severe response-time performance degradations when multiplexed with long-lived flows during times of network congestion. The reasons for this problem is that, in the absence of large number of packets the short flows are unable to get a detailed knowledge about the level of underlying network congestion and even a single packet loss forces long retransmission timeouts. Also as the numbers of packets are less they are not able to develop large congestion windows and thus unable to jumpstart the next data burst. Due to this, clients of interactive applications suffer from increased response time for data packets sent and they try to upgrade their short flows to long flows by sending dummy packets into the network even when they do not have any data to send. This behavior can lead to severe congestion in the network and causes harm to statistical multiplexing in the Internet. This paper aims at providing easy to implement techniques that can be used by the clients of interactive applications to get much better performance without causing any serious congestion in the network.

  3. Review of different TCP Variants in Adhoc networks

    Directory of Open Access Journals (Sweden)

    Varsha Sharma,

    2011-03-01

    Full Text Available Mobile Ad-Hoc networks (MANETs are collection of mobile nodes that dynamically forming a temporary network without pre-existing network infrastructure and communicate with its neighbours to perform peer to peer communication and transmission. Transmission Control Protocol (TCP provides connection oriented, reliable and end to end echanism. It tries to control packet losses, which are due to traffic congestion or transmission errors. In this article we present the review and comparison of existing TCP variants: TCP Tahoe, Reno, Lite, New Reno, elective Acknowledgement (Sack, Westwood, Vegas and Forward Acknowledgement (Fack. The behaviour of TCP was different depending on the type of TCP variants because of improper activation or missing of congestion control algorithms such as Slow Start, Congestion Avoidance, Fast Retransmission, Fast Recovery, etransmission, Congestion Control and Selective Acknowledgement echanism. This analysis is necessary to be aware of which TCP implementation is better for a specific scenario, where from an ppropriate one will be selected. This paper covers all the variants and its algorithms to observe their nature regarding to their eatures.

  4. Performance Improvement of TCP by TCP Reno and SACK Acknowledgement

    Directory of Open Access Journals (Sweden)

    Mrs. Reena Rai

    2012-03-01

    Full Text Available Transmission Control Protocol (TCP is the dominating end-to-end transport layer protocol which provides secure and reliable data transfer together with some other protocols. In this review paper, we contend that existing approaches to improve TCP performance over mobile ad-hoc networks have focused only on a subset of the factors affecting TCP performance by TCP Reno, SACK and Vegas. Effective resource utilization, such as bandwidth utilization, retransmission rate and window size, is compared. for evaluate these TCP congestion control algorithms from many aspects are present and We also concern fair resource allocation from two main categories, one is fairness between different delay links, and the other is competition between different TCP congestion control algorithms

  5. Research on TCP/IP computer network congestion control%对TCP/IP计算机网络拥塞控制的研究

    Institute of Scientific and Technical Information of China (English)

    余学杰

    2014-01-01

    为提升计算机的网络性能,更好地避免拥塞现象的发生,需要对其进行必要的技术控制。鉴于此,对基于TCP/IP协议的网络拥塞控制方法进行分析。在TCP拥塞控制中主要采用TCP Tahoe,TCP Reno,TCP New Reno以及TCP Sack四种方法,其中TCP New Reno对快速恢复算法进行了改进,通过对TCP协议中的Reno进行可视化处理,实行对网络拥塞的有效管理。而IP拥塞控制方法则分为FIFO,FQ和WFQ,RED以及ECN四种类型,通过队列调度管理方式实现了对网络拥塞的有效管理。%To enhance the performance of the computer network and avoid the occurrence of the congestion phenomenon,it is necessary to carry out the effective technical control. In view of this,the network congestion control methods based on TCP/IP protocol are analyzed. Four methods of TCP Tahoe,TCP Reno,TCP New Reno and TCP Sack are used for TCP congestion control;in which fast recovery algorithm was improved by means of TCP New Reno. The visualization processing can be per-formed through the Reno in TCP protocol to implement the effective management of network congestion. The IP congestion con-trol method can be divided into FIFO,FQ/WFQ,RED and ECN to realize the effective management of network congestion by queue scheduling management pattern.

  6. TCP-ADaLR: TCP with adaptive delay and loss response for broadband GEO satellite networks

    OpenAIRE

    Omueti, Modupe Omogbohun

    2007-01-01

    Transmission Control Protocol (TCP) performance degrades in broadband geostationary satellite networks due to long propagation delays and high bit error rates. In this thesis, we propose TCP with algorithm modifications for adaptive delay and loss response (TCP-ADaLR) to improve TCP performance. TCP-ADaLR incorporates delayed acknowledgement mechanism recommended for Internet hosts. We evaluate and compare the performance of TCP-ADaLR, TCP SACK, and TCP NewReno, with and without delayed ackno...

  7. TCP/IP foundations

    CERN Document Server

    Blank, Andrew G

    2006-01-01

    The world of IT is always evolving, but in every area there are stable, core concepts that anyone just setting out needed to know last year, needs to know this year, and will still need to know next year. The purpose of the Foundations series is to identify these concepts and present them in a way that gives you the strongest possible starting point, no matter what your endeavor. TCP/IP Foundations provides essential knowledge about the two protocols that form the basis for the Internet, as well as many other networks. What you learn here will benefit you in the short term, as you acquire and

  8. CW-HSTCP: Fair TCP in high-speed networks

    Institute of Scientific and Technical Information of China (English)

    PAN Xue-zeng; SU Fan-jun; L(U) Yong; PING Ling-di

    2006-01-01

    The congestion control mechanisms of the current standard TCP constrain the congestion windows that can be achieved by TCP in high-speed networks, which leads to low link utilization. HSTCP is one solution to solve this problem by modifying the congestion control mechanism to have the characteristics of TCP friendliness in high loss rate environment and high scalability in low loss rate environment. However, experiments revealed that HSTCP has severe RTT unfairness. After analyzing the RTT unfairness in HSTCP with a model, we proposed CW-HSTCP, which added a fair factor to decrease the difference of congestion window caused by different RTT. Fair factor of long RTT flows can cause a sharp window increment that is easy to cause a bursty traffic, so a method called block-pacing was adopted. Simulation results showed that our new proposal could alleviate the RTT unfairness while keeping advantages of HSTCP.

  9. Improving TCP Performance in Multi Hop Mobile Adhoc Network

    Directory of Open Access Journals (Sweden)

    Raghuraj Singh

    2012-01-01

    Full Text Available –TCP is a window-based flow and congestion control protocol that uses a sliding window mechanism to manage its data transmission. The purpose of this scheme is to guarantee that the sender adjusts its transmission rate to meet both sender and receiver needs. Thus, the TCP sender contains a variable denoted window determining the amount of packets it can send into the network before receiving an ACK. This variable changes dynamically over time to properly limit the connection’s sending rate. The sending rate of a TCP connection is regulated by two distinct mechanisms, the flow control and the congestion control. Although these mechanisms are similar, in the sense that both attempt to prevent the connection from sending at an excessive rate, they have specific purposes. Flow control is implemented to avoid that a TCP sender overflows the receiver’s buffer. Thus, the receiver advertises in every ACK transmitted a window limit to the sender. This window is named receiver advertised window (rwin and changes over time depending on both the traffic conditions and the application speed in reading the receiver’s buffer. Therefore, the sender may not increase its window at any time beyond the value specified in rwin. In contrast to flow control, congestion control is concerned with the traffic inside the network. Its purpose is to prevent collapse inside the network when the traffic source (sender is faster than the network in forwarding data. To this end, the TCP sender also uses a limiting window called congestion window (cwnd. Assuming that the receiver is not limiting the sender, cwnd defines the amount of data the sender may send into the network before an ACK is received. Considering flow control and congestion control, the sender faces two limiting factors for its window size, namely the rwin and the cwnd. To conform with both control schemes, the TCP sender adjusts its window to the minimum between rwin and cwnd. In general, however, cwnd

  10. Analyzing the Effect of TCP and Server Population on Massively Multiplayer Games

    Directory of Open Access Journals (Sweden)

    Mirko Suznjevic

    2014-01-01

    Full Text Available Many Massively Multiplayer Online Role-Playing Games (MMORPGs use TCP flows for communication between the server and the game clients. The utilization of TCP, which was not initially designed for (soft real-time services, has many implications for the competing traffic flows. In this paper we present a series of studies which explore the competition between MMORPG and other traffic flows. For that aim, we first extend a source-based traffic model, based on player’s activities during the day, to also incorporate the impact of the number of players sharing a server (server population on network traffic. Based on real traffic traces, we statistically model the influence of the variation of the server’s player population on the network traffic, depending on the action categories (i.e., types of in-game player behaviour. Using the developed traffic model we prove that while server population only modifies specific action categories, this effect is significant enough to be observed on the overall traffic. We find that TCP Vegas is a good option for competing flows in order not to throttle the MMORPG flows and that TCP SACK is more respectful with game flows than other TCP variants, namely, Tahoe, Reno, and New Reno. Other tests show that MMORPG flows do not significantly reduce their sending window size when competing against UDP flows. Additionally, we study the effect of RTT unfairness between MMORPG flows, showing that it is less important than in the case of network-limited TCP flows.

  11. Analysis of Next Generation TCP

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, K; Hurst, A; Nelson, J

    2004-12-13

    The Transmission Control Protocol (TCP) has been around for around 30 years, and in that time computer networks have increased in speed and reliability many times over. TCP has done very well to maintain stability and avoid collapse from congestion in the Internet with this incredible increase in speed. But as the speed of networks continues to increase, some assumptions about the underlying network that influenced the design of TCP may no longer hold valid. Additionally, modern networks often span many different types of links. For example, one end-to-end transmission may traverse both an optical link (high-bandwidth, low-loss) and a wireless network (low-bandwidth, high loss). TCP does not perform well in these situations. This survey will examine some of the reasons for this, focusing on high-bandwidth networks, and offer some solutions that have been proposed to fix these problems. This paper assumes basic knowledge of the TCP protocol.

  12. Improving Throughput For TCP Vegas

    Institute of Scientific and Technical Information of China (English)

    LIU Gang; ZHANG De-yun; LIU Jing; DING Hui-ning

    2004-01-01

    To slove the problem that the implementation of Transmission Control Protocol (TCP) Vegas does not consider the impact of TCP's segment size on Round-Trip Time (RTT) while calculating RTT and the smallest RTT (base_rtt), this paper proposes a modified congestion control mechanism for TCP Vegas. It first groups segments on the basis of segments size and updates base_rtt based on groups. In congestion avoidance phase, TCP Vegas changes its window size according to the measured RTT of the segment corresponding to the latest received ACK and the base_rtt retrieved from the group that the segment belongs to. Simulations illustrate that the enhanced TCP Vegas can achieve higher throughput up to 40 percent.

  13. PERFORMANCE ANALYSIS OF MULTI-PATH TCP NETWORK

    Directory of Open Access Journals (Sweden)

    Hamzah M A Hijawi

    2016-03-01

    Full Text Available MPTCP is proposed by IETF working group, it allows a single TCP stream to be split across multiple paths. It has obvious benefits in performance and reliability. MPTCP has implemented in Linux-based distributions that can be compiled and installed to be used for both real and experimental scenarios. In this article, we provide performance analyses for MPTCP with a laptop connected to WiFi access point and 3G cellular network at the same time. We prove experimentally that MPTCP outperforms regular TCP for WiFi or 3G interfaces. We also compare four types of congestion control algorithms for MPTCP that are also implemented in the Linux Kernel. Results show that Alias Linked Increase Congestion Control algorithm outperforms the others in the normal traffic load while Balanced Linked Adaptation algorithm outperforms the rest when the paths are shared with heavy traffic, which is not supported by MPTCP.

  14. Congestion detection within multi-service TCP/IP networks using wavelets.

    OpenAIRE

    Jarrett, W. O. B.

    2004-01-01

    Using passive observation within the multi-service TCP/IP networking domain, we have developed a methodology that associates the frequency composition of composite traffic signals with the packet transmission mechanisms of TCP. At the core of our design is the Discrete Wavelet Transform (DWT), used to temporally localise the frequency variations of a signal. Our design exploits transmission mechanisms (including Fast Retransmit/Fast Recovery, Congestion Avoidance, Slow start, and Retransmissi...

  15. Review of different TCP Variants in Adhoc networks

    OpenAIRE

    Varsha Sharma; Mandakini Tayade,

    2011-01-01

    Mobile Ad-Hoc networks (MANETs) are collection of mobile nodes that dynamically forming a temporary network without pre-existing network infrastructure and communicate with its neighbours to perform peer to peer communication and transmission. Transmission Control Protocol (TCP) provides connection oriented, reliable and end to end echanism. It tries to control packet losses, which are due to traffic congestion or transmission errors. In this article we present the review and comparison of e...

  16. Consistency Analysis of Network Traffic Repositories

    NARCIS (Netherlands)

    Lastdrager, Elmer; Pras, Aiko

    2009-01-01

    Traffic repositories with TCP/IP header information are very important for network analysis. Researchers often assume that such repositories reliably represent all traffic that has been flowing over the network; little thoughts are made regarding the consistency of these repositories. Still, for var

  17. Experimental evaluation of TCP protocols for high-speed networks

    OpenAIRE

    Li, Yee-Ting; Leith, Douglas J.; Shorten, Robert N.

    2007-01-01

    In this paper, we present experimental results evaluating the performance of the scalable-TCP, HS-TCP, BIC-TCP, FAST-TCP, and H-TCP proposals in a series of benchmark tests. In summary, we find that both Scalable-TCP and FAST-TCP consistently exhibit substantial unfairness, even when competing flows share identical network path characteristics. Scalable-TCP, HS-TCP, FAST-TCP, and BIC-TCP all exhibit much greater RTT unfairness than does standard TCP, to the extent that long RTT flows ma...

  18. Interfacing network coding with TCP: an implementation

    CERN Document Server

    Sundararajan, Jay Kumar; Medard, Muriel; Mitzenmacher, Michael; Barros, Joao

    2009-01-01

    In previous work (`Network coding meets TCP') we proposed a new protocol that interfaces network coding with TCP by means of a coding layer between TCP and IP. Unlike the usual batch-based coding schemes, the protocol uses a TCP-compatible sliding window code in combination with new rules for acknowledging bytes to TCP that take into account the network coding operations in the lower layer. The protocol was presented in a theoretical framework and considered only in conjunction with TCP Vegas. In this paper we present a real-world implementation of this protocol that addresses several important practical aspects of incorporating network coding and decoding with TCP's window management mechanism. Further, we work with the more widespread and practical TCP Reno. Our implementation significantly advances the goal of designing a deployable, general, TCP-compatible protocol that provides the benefits of network coding.

  19. Analysis of the role of Arabidopsis class I TCP genes AtTCP7, AtTCP8, AtTCP22, and AtTCP23 in leaf development

    OpenAIRE

    Aguilar-Martínez, José A.; Sinha, Neelima

    2013-01-01

    TCP family of plant-specific transcription factors regulates plant form through control of cell proliferation and differentiation. This gene family is comprised of two groups, class I and class II. While the role of class II TCP genes in plant development is well known, data about the function of some class I TCP genes is lacking. We studied a group of phylogenetically related class I TCP genes: AtTCP7, AtTCP8, AtTCP22, and AtTCP23. The similar expression pattern in young growing leaves found...

  20. Performance of TCP variants over LTE network

    Science.gov (United States)

    Nor, Shahrudin Awang; Maulana, Ade Novia

    2016-08-01

    One of the implementation of a wireless network is based on mobile broadband technology Long Term Evolution (LTE). LTE offers a variety of advantages, especially in terms of access speed, capacity, architectural simplicity and ease of implementation, as well as the breadth of choice of the type of user equipment (UE) that can establish the access. The majority of the Internet connections in the world happen using the TCP (Transmission Control Protocol) due to the TCP's reliability in transmitting packets in the network. TCP reliability lies in the ability to control the congestion. TCP was originally designed for wired media, but LTE connected through a wireless medium that is not stable in comparison to wired media. A wide variety of TCP has been made to produce a better performance than its predecessor. In this study, we simulate the performance provided by the TCP NewReno and TCP Vegas based on simulation using network simulator version 2 (ns2). The TCP performance is analyzed in terms of throughput, packet loss and end-to-end delay. In comparing the performance of TCP NewReno and TCP Vegas, the simulation result shows that the throughput of TCP NewReno is slightly higher than TCP Vegas, while TCP Vegas gives significantly better end-to-end delay and packet loss. The analysis of throughput, packet loss and end-to-end delay are made to evaluate the simulation.

  1. 基于TCP Reno和TCP Vegas拥塞控制性能研究%Research of congestion control performance based on TCP Reno and TCP Vegas

    Institute of Scientific and Technical Information of China (English)

    刘国柱; 高文娟

    2011-01-01

    介绍了传输控制协议(TCP)的拥塞控制技术,对两种典型的TCP拥塞控制算法TCP Reno和TCP Vegas进行了详尽的分析,对其性能进行了比较.同时对TCP Reno和TCP Vegas在混存网络环境下的性能进行分析,并针对TCP Vegas中的α和β参数进行修改,提出了Vegas.A+算法使它们能并存于网络中.在NS2仿真环境下对改进的控制算法进行了仿真,仿真结果表明了改进算法的有效性.%The TCP (Transmission Control Protocol) congestion control techniques, and a detailed analysis of TCP Reno and TCP Vegas which are two typical TCP congestion control algorithms are mainly focused on. The performance of the TCP Reno and TCP Vegas in the mixed network environment is also analyzed, and not only the parameters α and β of the TCP Vegas are modified properly, but also an algorithm called Vegas-A+ is proposed, so that they can co-exist in the network. It is simulated by NS2, and proved the validity of the improved method.

  2. An Empirical Study on variants of TCP over AODV routing protocol in MANET

    CERN Document Server

    Morshed, Md Monzur; Islam, Md Rafiqul

    2011-01-01

    The cardinal concept of TCP development was to carry data within the network where network congestion plays a vital role to cause packet loss. On the other hand, there are several other reasons to lose packets in Mobile Ad Hoc Networks due to fading, interfaces, multi-path routing, malicious node, and black hole. Along with throughput, fairness of TCP protocols is important to establish a good communication. In this paper, an empirical study has been done by simulation and analysis of TCP variations under AODV routing protocol. In our simulation, we studied multiple variations of TCP, such as Reno, New-Reno, Vegas, and Tahoe. The simulation work has been done in NS2 environment. Based on the analysis simulation result of we carried out our observations with respect to the behavior of AODV routing protocol for different TCP packets under several QoS metrics such as drop, throughput, delay, and jitter.

  3. Internetworking with TCP/IP

    CERN Document Server

    Comer, Douglas E

    2014-01-01

    An internationally best-selling, conceptual introduction to the TCP/IP protocols and Internetworking, this book interweaves a clear discussion of fundamentals and scientific principles with details and examples drawn from the latest technologies. Leading author Douglas Comer covers layering and packet formats for all the Internet protocols, includingTCP, IPv4, IPv6, DHCP, and DNS. In addition, the text explains new trends in Internet systems, including packet classification, Software Defined Networking (SDN), and mesh protocols used in The Internet of Things. The text is appropriate for individuals interested in learning more about TCP/IP protocols, Internet architecture, and current networking technologies, as well as engineers who build network systems. It is suitable for junior to graduate-level courses in Computer Networks, Data Networks, Network Protocols, and Internetworking.

  4. Optimizing TCP Performance over UMTS with Split TCP Proxy

    DEFF Research Database (Denmark)

    Hu, Liang; Dittmann, Lars

    2009-01-01

    Abstract: The TCP performance over UMTS network is challenged by the large delay bandwidth product. Large delay bandwidth product is mainly caused by the latency from the link layer ARQ retransmissions and diversity technique at physical layer which are used to cope with radio transmission errors...

  5. 针对跑道侵入开展空管系统抵御%Against the runway intrusion to carry out air traffic control system to resist

    Institute of Scientific and Technical Information of China (English)

    赵阳

    2015-01-01

    Along with the prosperity and development of the social economy,air traffic was also people make full use of and global civil aviation transportation is more and more frequent,resulting in airport ground traffic becomes congested.The runway incursion is becoming increasingly serious,the slightest mistake will cause the plane crash tragedy.This paper introduces the definition and types of the intrusion runway, analyzes the reasons of the intrusion of the runway,and puts forward the technology leading of the air traffic control system to prevent runway intrusion and improve the safety operation level of airport runway..%随着社会经济的繁荣发展,空中交通也被人们充分地利用,全球民航业的运输交通也越来越频繁,造成机场的地面交通也随之拥挤不堪。跑道侵入的现象日益严重,稍有不慎就会会造成机毁人亡的悲剧。本文介绍侵入跑道的定义及种类,分析侵入跑道产生的原因,提出空管系统对预防跑道侵入的技术主导,改善机场跑道的安全运行水平。

  6. TCP Performance Enhancement for UMTS Access Network

    DEFF Research Database (Denmark)

    Hu, Liang

    2008-01-01

    is between UMTS access network and Internet. The split proxy divides the bandwidth delay product into two parts, resulting in two TCP connections with smaller bandwidth delay products. Simulation results show, the split TCP proxy can significantly improve the TCP performance under high bit rate DCH channel......We aim at optimize the TCP performance over UMTS access network challenged by the large delay bandwidth product that is mainly caused by the latency from the link layer ARQ retransmissions and diversity technique at physical layer. We propose to place a split TCP proxy at GGSN nodes which...

  7. A TCP-Over-UDP Test Harness

    Energy Technology Data Exchange (ETDEWEB)

    Dunigan, TH

    2002-10-31

    This report describes an implementation of a TCP-like protocol that runs over UDP. This TCP-like implementation, which does not require kernel modifications, provides a test harness for evaluating variations of the TCP transport protocol over the Internet. The test harness provides a tunable and instrumented version of TCP that supports Reno, NewReno, and SACK/FACK. The test harness can also be used to characterize the TCP-performance of a network path. Several case studies illustrate how one can tune the transport protocol to improve performance.

  8. Experimental and Theoretical Analysis of Storage Friendly TCP Performance in Distributed Storage Area Network

    Directory of Open Access Journals (Sweden)

    Suresh Muknahallipatna

    2007-08-01

    Full Text Available Fibre channel storage area networks (SAN are widely implemented in production data center environments. Recently the storage industry has moved towards deployment of distributed SANs (DSAN, geographically dispersed across large physical distances. In a DSAN, specialized gateway devices interconnect the individual Fibre Channel (FC fabrics over IP networks using TCP/IP based protocols (iFCP or FCIP or over metro to long distance optical networks such as Dense Wavelength Division Multiplexing (DWDM based networks that utilize native FC ports supporting large numbers of link credits. When using TCP/IP based storage networking protocols to interconnect local FC fabrics in a DSAN, the sustained throughput achievable depends upon the link characteristics and TCP/IP stack implementation. Sustaining maximum possible storage traffic throughput across the wide area network enables practical DSAN deployments by maintaining the required site to site service level agreements.This study explores the effects of several TCP/IP modifications on sustained traffic throughput for a DSAN interconnected via iFCP gateways across an impaired network. The TCP/IP stack modifications, known as storage friendly, include changes to the window scaling, congestion avoidance, and fast recovery algorithms. The theoretical background and experimental results are presented to explain and illustrate these modifications.

  9. Microstructure control of TCP/TCP-(t-ZrO2)/t-ZrO2 composites for artificial cortical bone

    International Nuclear Information System (INIS)

    In this study, bone like continuously porous TCP/TCP-(t-ZrO2)/t-ZrO2 composites with a central channel were fabricated using a multi-pass extrusion process and their mechanical properties and microstructure at different sintering temperatures were investigated. Hydroxyapatite (HAp) powder was used as the raw powder which undergoes a phase transformation into the α-tricalcium phosphate phase (α-TCP) at a sintering temperature of 1500 deg. C. The external diameter and inside cylindrical hollow core were approximately 10.3 mm and 4.8 mm, respectively. The frame region contained numerous microchannels that extended from one side of the fabricated body to the other. The channeled frame region had a multi-layer microstructure with a TCP/TCP-(t-ZrO2)/t-ZrO2 layer configuration. The inner layer consisted of TCP, which make the wall of the microchannel. The material properties were characterized and microstructural analysis was carried out. The maximum pore size, compressive strength, and relative density of the fabricated system were approximately 86 μm, 53 MPa, and 77% when sintered at 1500 deg. C. The composites exhibited excellent biocompatibility and cell proliferation behavior resulted in the MTT assay and cell adhesion test using osteoblast-like MG-63 cells. Highlights: → In this work we fabricated a composites preform that is a biomimetic structure of bone architecture. → Unidirectional porous channel with lamellar elcloser, like that of the natural bone was fabricated. → The HAp-ZrO2 composites system was mechanically strong and showed excellent biocompatibility to be used as an artificial bone.

  10. AN ENHANCEMENT SCHEME OF TCP PROTOCOL IN MOBILE AD HOC NETWORKS: MME-TCP

    Institute of Scientific and Technical Information of China (English)

    Kai Caihong; Yu Nenghai; Chen Yuzhong

    2007-01-01

    Transmission Control Protocol (TCP) optimization in Mobile Ad hoc NETworks (MANETs) is a challenging issue because of some unique characteristics of MANETs. In this paper,a new end-to-end mechanism based on multiple metrics measurement is proposed to improve TCP performance in MANETs. Multi-metric Measurement based Enhancement of TCP (MME-TCP)designs the metrics and the identification algorithm according to the characteristics of MANETs and the experiment results. Furthermore, these metrics are measured at the sender node to reduce the overhead of control information over networks. Simulation results show that MME-TCP mechanism achieves a significant performance improvement over standard TCP in MANETs.

  11. OSI and TCP/IP

    Science.gov (United States)

    Randolph, Lynwood P.

    1994-01-01

    The Open Systems Interconnection Transmission Control Protocol/Internet Protocol (OSI TCP/IP) and the Government Open Systems Interconnection Profile (GOSIP) are compared and described in terms of Federal internetworking. The organization and functions of the Federal Internetworking Requirements Panel (FIRP) are discussed and the panel's conclusions and recommendations with respect to the standards and implementation of the National Information Infrastructure (NII) are presented.

  12. TCP-friendly source adaptation for multimedia applications over the Internet

    Institute of Scientific and Technical Information of China (English)

    CHEN Cheng; LI Zheng-guo; SOH Yeng-chai

    2006-01-01

    In this paper, we propose a simply TCP-friendly source adaptation framework to provide a proportional bandwidth sharing service. Our scheme is based on the framework of Monotonic Response Function (MRF), can be used to bound the sending rate of a source within a predefined interval and provide very smooth traffic, and is suitable for multimedia applications over the Internet. As our scheme is also very simple and TCP-friendly, it is easy to be deployed over the current Internet. We verify our scheme with experimental studies.

  13. MULTIMEDIA DATA TRANSMISSION THROUGH TCP/IP USING HASH BASED FEC WITH AUTO-XOR SCHEME

    Directory of Open Access Journals (Sweden)

    R. Shalin

    2012-09-01

    Full Text Available The most preferred mode for communication of multimedia data is through the TCP/IP protocol. But on the other hand the TCP/IP protocol produces huge packet loss unavoidable due to network traffic and congestion. In order to provide a efficient communication it is necessary to recover the loss of packets. The proposed scheme implements Hash based FEC with auto XOR scheme for this purpose. The scheme is implemented through Forward error correction, MD5 and XOR for providing efficient transmission of multimedia data. The proposed scheme provides transmission high accuracy, throughput and low latency and loss.

  14. Potential performance bottleneck in Linux TCP

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wenji; Crawford, Matt; /Fermilab

    2006-12-01

    TCP is the most widely used transport protocol on the Internet today. Over the years, especially recently, due to requirements of high bandwidth transmission, various approaches have been proposed to improve TCP performance. The Linux 2.6 kernel is now preemptible. It can be interrupted mid-task, making the system more responsive and interactive. However, we have noticed that Linux kernel preemption can interact badly with the performance of the networking subsystem. In this paper we investigate the performance bottleneck in Linux TCP. We systematically describe the trip of a TCP packet from its ingress into a Linux network end system to its final delivery to the application; we study the performance bottleneck in Linux TCP through mathematical modeling and practical experiments; finally we propose and test one possible solution to resolve this performance bottleneck in Linux TCP.

  15. An Enhancement On Mobile TCP Socket

    OpenAIRE

    S. Saravanan; T. Ravi

    2010-01-01

    A TCP session uses IP addresses (+ IP port) of both end points as identifiers. Therefore when a mobile handover to a new AP that belong to a different subnet/domain, the IP address will changes and ongoing TCP connections are reset. Several approaches have been proposed to solve this problem, and one of which was to modified the TCP/IP stack to update the changes of the IP address for the ongoing connections [5] [6]. However, these proposals causes unnecessary processing when TCP is used in a...

  16. TCP/IP Network Administration

    CERN Document Server

    Hunt, Craig

    2002-01-01

    This complete guide to setting up and running a TCP/IP network is essential for network administrators, and invaluable for users of home systems that access the Internet. The book starts with the fundamentals -- what protocols do and how they work, how addresses and routing are used to move data through the network, how to set up your network connection -- and then covers, in detail, everything you need to know to exchange information via the Internet. Included are discussions on advanced routing protocols (RIPv2, OSPF, and BGP) and the gated software package that implements them, a tutorial

  17. Analysis list: TCP1 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available TCP1 Digestive tract,Epidermis,Prostate + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/TCP...1.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/TCP1.5.tsv http://dbarc...hive.biosciencedbc.jp/kyushu-u/hg19/target/TCP1.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/TCP...1.Digestive_tract.tsv,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/TCP...1.Epidermis.tsv,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/TCP1.Prostate.tsv http://dbarchive.bios

  18. Analysis of Proactive and Reactive Manet Routing Protocols Under Selected TCP Variants

    Directory of Open Access Journals (Sweden)

    Iffat Syad

    2013-08-01

    Full Text Available A Mobile Ad hoc Network (MANET, with its inherent dynamic and flexible architecture, demonstrates attractive potential for military applications. It is able to overcome traditional communications limitations through its automatic relaying and self - healing/forming features. MANE T nodes perform the routing functions themselves. Due to the limited wireless transmission range, the routing generally consists of multiple hops. Therefore, the nodes depend on one another to forward packets to the destinations. In a Mobile Ad Hoc Network (MANET, temporary link failures and route changes happen frequently. With the assumption that all packet losses are due to congestion, Transport Control Protocol (TCP performs poorly in such an environment. One problem of TCP in such environments is its inability to distinguish losses induced by the lossy wireless channel from the ones due to network congestion. Many TCP variants have been developed for the improved performance of TCP in MANET. In this research, through simulations that were carried out by using Network Simulator-2 (NS-2 , the selected MANET Routing protocols i.e. DSR and DSDV were analyzed in accordance with their finest performance of packets delivery rate, average end - to - end delay, and packet dropping, under TCP Vegas and TCP Newreno with mobility consideration. The simulation results indicate that DSDV has a b etter throughput performance but higher average end-to-end delay and packet drop ratioas compared to DSR

  19. 浅析TCP/IP协议及其安全%Analysis on TCP/IP Protocol and Its Security

    Institute of Scientific and Technical Information of China (English)

    李东灵; 毛自民

    2012-01-01

    本文主要讨论TCP/IP协议内容,以及TCP/IP协议的安全问题和几种常见的网络攻击手段.%This paper mainly discusses the TCP/IP protocol, and TCP/IP protocol security problems and some common network attack means.

  20. Analyzing the Performance I-TCP and TCP with Explicit Lose Notification over Wireless Links for the Purpose of Further Improvement

    OpenAIRE

    Atheer Yousif Oudah

    2014-01-01

    Many researchers have been proposed different enhancements over wireless network for the Purpose of Further Improvement .in this research we do comparative study on the performance of the standard TCP over two other approaches meant for the advancement namely Indirect TCP (I-TCP) and TCP with Explicit Loss Notification (ELN-TCP).the main aim of this research is to improve the performance of TCP by providing analyzing approach for the I-TCP) and TCP with Explicit Loss Notificat...

  1. TCP/IP Network In Process Control Plants%过程控制中的TCP/IP网络

    Institute of Scientific and Technical Information of China (English)

    牟连佳; 王立明

    2002-01-01

    提出TCP/IP在过程控制中的应用. 评价TCP/IP控制系统性能,通过传统控制系统与TCP/IP控制系统的比较,指出采用TCP/IP 控制系统的优缺点. 说明过程控制技术中,采用TCP/IP是一种更好的选择.

  2. Psychological Carrying Capacity of Non-motorized Traffic Environment in Historical Districts%历史街区非机动车交通环境心理承载力研究

    Institute of Scientific and Technical Information of China (English)

    王秋平; 韩霞

    2015-01-01

    Travel by non-motor vehicles accounts for a big proportion in historical districts, but because of the limitation of the space scale and road network pattern of historical districts, non-motor vehicles drive chaotically with pedestrians and motor vehicles, which results in a poor travel environment. Through the practical survey in Shuyuan historical district in Zhengzhou, Gulou historical district in Kaifeng and Dongxinanyu historical district in Luoyang , the influence factors and evaluation index of psychological carrying capacity of non-motorized traffic environment in historical districts is studied, and its evaluation models of negative binomial distribution is established by introducing tolerance thresholds. According to the data of Shuyuan historical district in Zhengzhou and Gulou historical district in Kaifeng, which show that the study method is feasible, also suitable for accurately evaluating the non-motor vehicle lane capacity and optimizing the road cross-section, to improve the environment of non-motorized traffic for a sustainable development in historical districts.%历史街区非机动车交通所占出行比例较大,但由于街区空间尺度和路网格局的限制,人、机、非混行严重,非机动车出行环境较差.通过对郑州书院街、开封鼓楼、洛阳东西南隅3个历史街区的实地调研,研究了历史街区非机动车交通环境心理承载力的影响因素和评价指标,以郑州书院街和开封鼓楼2个历史街区的观测数据建立了非机动车流量的负二项评估模型,引入骑行速度容忍阈值,得到非机动车交通环境心理承载力评估模型,最后以洛阳东西南隅历史街区的观测数据进行验证,结果表明该研究方法是可行的,可以为更准确的评估历史街区非机动车道通行能力,优化历史街区道路横断面,改善街区非机动车交通环境,实现街区交通的可持续发展提供理论依据.

  3. Experimental Assessment of BitTorrent Completion Time in Heterogeneous TCP/uTP swarms

    CERN Document Server

    Testa, Claudio; Rao, Ashwin; Legout, Arnaud

    2011-01-01

    BitTorrent, one of the most widespread used P2P application for file-sharing, recently got rid of TCP by introducing an application-level congestion control protocol named uTP. The aim of this new protocol is to efficiently use the available link capacity, while minimizing its interference with the rest of user traffic (e.g., Web, VoIP and gaming) sharing the same access bottleneck. In this paper we perform an experimental study of the impact of uTP on the torrent completion time, the metric that better captures the user experience. We run BitTorrent applications in a flash crowd scenario over a dedicated cluster platform, under both homogeneous and heterogeneous swarm population. Experiments show that an all-uTP swarms have shorter torrent download time with respect to all-TCP swarms. Interestingly, at the same time, we observe that even shorter completion times can be achieved under careful mixtures of TCP and uTP traffic.

  4. Carrying Capacity

    DEFF Research Database (Denmark)

    Schroll, Henning; Andersen, Jan; Kjærgård, Bente

    2012-01-01

    carrying capacity (SCC) and assimilative carrying capacity (ACC). The act mandates that the latter two aspects must be taken into consideration in the local spatial plans. The present study aimed at developing a background for a national guideline for carrying capacity in Indonesian provinces and districts...... carrying capacity (ACC). The act mandates that the latter two aspects must be taken into consideration in the local spatial plans. The present study aimed at developing a background for a national guideline for carrying capacity in Indonesian provinces and districts/cities. Four different sectors (water...

  5. Cryptographic Defence against Misbehaving TCP Receivers

    CERN Document Server

    Chan, Aldar C-F

    2008-01-01

    The congestion control algorithm in TCP relies on {\\em correct} feedback from the receiver to determine the rate at which packets should be sent into the network. Hence, correct receiver feedback (in the form of acknowledgements in TCP) is essential to the goal of sharing the scarce bandwidth resources fairly and avoiding congestion collapse in the Internet. However, the assumption that a TCP receiver can always be trusted (to generate feedback correctly) no longer holds as there are plenty of incentives for a receiver to deviate from the protocol. In fact, it has been shown that a misbehaving receiver (whose aim is to bring about congestion collapse) can easily generate acknowledgements to conceal loss and drive a number of honest, innocent senders arbitrary fast to create a significant number of non-responsive packet flows leading to denial of service to other Internet users. We give two efficient, provably secure mechanisms to force a receiver to generate feedback correctly; any incorrect acknowledgement w...

  6. Priority probability deceleration deadline-aware TCP

    Institute of Scientific and Technical Information of China (English)

    Jin Ye; Jing Lin; Jiawei Huang

    2015-01-01

    In modern data centers, because of the deadline-agnostic congestion control in transmission control protocol (TCP), many deadline-sensitive flows can not finish before their deadlines. Therefore, providing a higher deadline meeting ratio becomes a critical chal enge in the typical online data intensive (OLDI) ap-plications of data center networks (DCNs). However, a problem named as priority synchronization is found in this paper, which de-creases the deadline meeting ratio badly. To solve this problem, we propose a priority probability deceleration (P2D) deadline-aware TCP. By using the novel probabilistic deceleration, P2D prevents the priority synchronization problem. Simulation results show that P2 D increases the deadline meeting ratio by 20%compared with D2TCP.

  7. 10 Gbps TCP/IP streams from the FPGA for the CMS DAQ Eventbuilder Network

    CERN Document Server

    Bauer, Gerry; Branson, James; Chaze, Olivier; Cittolin, Sergio; Coarasa Perez, Jose Antonio; Darlea, Georgiana Lavinia; Deldicque, Christian; Dobson, Marc; Dupont, Aymeric; Erhan, Samim; Gigi, Dominique; Glege, Frank; Gomez Ceballos, Guillelmo; Gomez-Reino Garrido, Robert; Hartl, Christian; Hegeman, Jeroen Guido; Holzner, Andre Georg; Masetti, Lorenzo; Meijers, Franciscus; Meschi, Emilio; Mommsen, Remigius; Morovic, Srecko; Nunez Barranco Fernandez, Carlos; O'Dell, Vivian; Orsini, Luciano; Ozga, Wojciech Andrzej; Paus, Christoph Maria Ernst; Petrucci, Andrea; Pieri, Marco; Racz, Attila; Raginel, Olivier; Sakulin, Hannes; Sani, Matteo; Schwick, Christoph; Spataru, Andrei Cristian; Stieger, Benjamin Bastian; Sumorok, Konstanty; Veverka, Jan; Wakefield, Christopher Colin; Zejdl, Petr

    2013-01-01

    For the upgrade of the DAQ of the CMS experiment in 2013/2014 an interface between the custom detector Front End Drivers (FEDs) and the new DAQ eventbuilder network has to be designed. For a loss-less data collection from more then 600 FEDs a new FPGA based card implementing the TCP/IP protocol suite over 10Gbps Ethernet has been developed. We present the hardware challenges and protocol modifications made to TCP in order to simplify its FPGA implementation together with a set of performance measurements which were carried out with the current prototype.

  8. Enhanced TCP for maritime communications over satellite network

    Science.gov (United States)

    Zong, Liang; Du, Wencai; Bai, Yong

    2014-10-01

    For maritime communications over satellite network, TCP performance is essential for data transmissions. TCP ADaLR is congestion control algorithm that the sender judgments the relevant window change and measures roundtrip time to control congestion window. It can adapt to the characteristics of the satellite link and improve the performance of TCP than conventional TCP. However, it does not take into account distinction of random packet loss and congestion loss like TCP Veno. In this paper, we propose further enhancement of TCP ADaLR, called TCP ADaLR+, that can distinguish between random packet loss and congestion loss. The improved performance of proposed TCP ADaLR+ is demonstrated by simulations.

  9. A Survey: variants of TCP in Ad-hoc networks

    Directory of Open Access Journals (Sweden)

    Komal Zaman

    2013-11-01

    Full Text Available MANET (Mobile Ad-hoc network forms a temporary network of wireless mobile nodes without any infrastructure where all nodes are allowed to move freely, configure themselves and interconnect with its neighbors to perform peer to peer communication and transmission. TCP (Transmission Control Protocol offers reliable, oriented connection and mechanism of end to end delivery. This article provides the review and comparison of existing variants of TCP for instance: The TCP Tahoe, The TCP Reno, The TCP New Reno, The Lite, The Sack, The TCP Vegas, Westwood and The TCP Fack. TCP’s performance depends on the type of its variants due to missing of congestion control or improper activation procedures such as Slow Start, Fast Retransmission, and Congestion Avoidance, Retransmission, Fast Recovery, Selective Acknowledgement mechanism and Congestion Control. This analysis is essential to be aware about a better TCP implementation for a specific scenario and then nominated a suitable one.

  10. 大白菜BrTCP24基因的克隆与功能分析%Cloning and Functional Analysis of BrTCP24 Gene in Chinese Cabbage (Brassica rapa L.ssp.pekinensis)

    Institute of Scientific and Technical Information of China (English)

    王凤德; 谭婷婷; 张一卉; 李景娟; 李化银; 李利斌; 刘立锋; 高建伟

    2013-01-01

    It is very important to isolate and characterize the genes responsible for negative control of the leaf heading growth of Chinese cabbage,which can be help to speed up breeding progress of the small heading Chinese cabbage varieties that meet the current market demands.Here,a full-length TCP cDNA named BrTCP24,which belongs to the second subgroups of TCP domain family,was isolated from leaves of Chinese cabbage inbred line Fushanbaotou (Brassica rapa L.ssp.pekinensis).The full-length cDNA of BrTCP24 consisted of 1 221 nucleotides,and was predicted to code a 406-amino acid polypeptide.In addition,there were no introns in BrTCP24 gene.The phylogenetic analysis about BrTCP24 and TCP families in Arabidopsis was carried out using the software of MEGA4.0.The result indicated that BrTCP24 gene and Arabidopsis AtTCP3 gene would belong to the same branch,which suggested they had closely genetic relationship.The alignment of predicted amino acid sequences of BrTCP24 and Arabidopsis AtTCP3 indicated that there was 55.15% identity between them.Additionally,these two proteins contained conserved TCP domain and had 91.53% identity in this domain.These results suggested that BrTCP24 and Arabidopsis AtTCP3 would have similar biological functions.The semiquantitive RT-PCR indicated that BrTCP24 gene was expressed in roots,dwarf stems,rosette leaves,folding leaves,flowers,siliques and bud flowers examined in Chinese cabbage.Among them,rosette leaves had the highest mRNA level,followed by roots,folding leaves,flowers,siliques and bud flowers,while dwarf stems had the lowest mRNA level.Interestingly,the expression level of BrTCP24 didn't effect by 5 μmol NAA treatment in 12 h period.To test the function of BrTCP24,we then engineered Arabidopsis plants that would over-express BrTCP24 ectopically,driven by CaMV 35S promoter,and obtained 17 transgenic lines by Kanamycin and PCR screening.Using RT-PCR method,we randomly detected 5 transgenic lines and found all of them could express

  11. Chitosan Fibers Modified with HAp/beta-TCP Nanoparticles

    OpenAIRE

    Dariusz Wawro; Luciano Pighinelli

    2011-01-01

    This paper describes a method for preparing chitosan fibers modified with hydroxyapatite (HAp), tricalcium phosphate (β-TCP), and HAp/β-TCP nanoparticles. Fiber-grade chitosan derived from the northern shrimp (Pandalus borealis) and nanoparticles of tricalcium phosphate (β-TCP) and hydroxyapatite (HAp) suspended in a diluted chitosan solution were used in the investigation. Diluted chitosan solution containing nanoparticles of Hap/β-TCP was introduced to a 5.16 wt% solution of chitosan in 3.0...

  12. A Survey: variants of TCP in Ad-hoc networks

    OpenAIRE

    Komal Zaman; Muddesar Iqbal; Muhammad Shafiq; Azeem Irshad; Saqib Rasool

    2013-01-01

    MANET (Mobile Ad-hoc network) forms a temporary network of wireless mobile nodes without any infrastructure where all nodes are allowed to move freely, configure themselves and interconnect with its neighbors to perform peer to peer communication and transmission. TCP (Transmission Control Protocol) offers reliable, oriented connection and mechanism of end to end delivery. This article provides the review and comparison of existing variants of TCP for instance: The TCP Tahoe, The TCP Reno, Th...

  13. Making TCP/IP Viable for Wireless Sensor Networks

    OpenAIRE

    Dunkels, Adam; Alonso, Juan; Voigt, Thiemo

    2003-01-01

    The TCP/IP protocol suite, which has proven itself highly successful in wired networks, is often claimed to be unsuited for wireless micro-sensor networks. In this work, we question this conventional wisdom and present a number of mechanisms that are intended to enable the use of TCP/IP for wireless sensor networks: spatial IP address assignment, shared context header compression, application overlay routing, and distributed TCP caching (DTC). Sensor networks based on TCP...

  14. A survey of TCP over ad hoc networks

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Altman, Eitan; Nain, Philippe

    2005-01-01

    The Transmission Control Protocol (TCP) was designed to provide reliable end-to-end delivery of data over unreliable networks. In practice, most TCP deployments have been carefully designed in the context of wired networks. Ignoring the properties of wireless ad hoc networks can lead to TCP implemen

  15. A Survey of Network Optimization Techniques for Traffic Engineering

    OpenAIRE

    Fedrigo, Enrico; Granelli, Fabrizio

    2008-01-01

    TCP/IP represents the reference standard for the implementation of interoperable communication networks. Nevertheless, the layering principle at the basis of interoperability severely limits the performance of data communication networks, thus requiring proper configuration and management in order to provide effective management of traffic flows. This paper presents a brief survey related to network optimization using Traffic Engineering algorithms, aiming at providing additional insight to t...

  16. SET: Session Layer-Assisted Efficient TCP Management Architecture for 6LoWPAN with Multiple Gateways

    Directory of Open Access Journals (Sweden)

    Akbar AliHammad

    2010-01-01

    Full Text Available 6LoWPAN (IPv6 based Low-Power Personal Area Network is a protocol specification that facilitates communication of IPv6 packets on top of IEEE 802.15.4 so that Internet and wireless sensor networks can be inter-connected. This interconnection is especially required in commercial and enterprise applications of sensor networks where reliable and timely data transfers such as multiple code updates are needed from Internet nodes to sensor nodes. For this type of inbound traffic which is mostly bulk, TCP as transport layer protocol is essential, resulting in end-to-end TCP session through a default gateway. In this scenario, a single gateway tends to become the bottleneck because of non-uniform connectivity to all the sensor nodes besides being vulnerable to buffer overflow. We propose SET; a management architecture for multiple split-TCP sessions across a number of serving gateways. SET implements striping and multiple TCP session management through a shim at session layer. Through analytical modeling and ns2 simulations, we show that our proposed architecture optimizes communication for ingress bulk data transfer while providing associated load balancing services. We conclude that multiple split-TCP sessions managed in parallel across a number of gateways result in reduced latency for bulk data transfer and provide robustness against gateway failures.

  17. A Security Architecture of TCP/IP Protocol Suite%TCP/IP协议族的安全架构

    Institute of Scientific and Technical Information of China (English)

    陈晓苏; 朱国胜; 肖道举

    2001-01-01

    The Security architecture of TCP/IP protocol suite is given. The internet protocol security IPSec and the transport layer security TLS are studied. The encryption and authentication services at the network layer and transport layer respectively are provided. ISAKMP is introduced to carry through the association of SAs by IPSec and TLS handshake protocol is presented to carry through the association of security parameters by TLS.%给出了TCP/IP协议族的整体安全架构,讨论了网络层安全协议IPSec和传输层安全协议TLS,以实现在网络层和传输层提供加密和认证等安全服务.阐述了IPSec提供安全服务之前如何通过ISAKMP协议进行SA的协商以及TLS如何通过握手协议进行安全协商的问题.

  18. Security Tools 2: TCP-Wrapper

    OpenAIRE

    Lehle, Bernd; Reutter, Oliver

    1996-01-01

    In Analogie mit den Fantasy-Rollenspielen sehen die Hacker im Internet sich gerne alsNachfolger der mittelalterlichen Ritter und benutzen auch entsprechende Terminologie. In diesem Sinne wollen wir nach dem zweischneidigen Schwert SATAN nun einen rechtwirksamen Schild vorstellen - den TCP-Wrapper.

  19. Running TCP/IP over ATM Networks.

    Science.gov (United States)

    Witt, Michael

    1995-01-01

    Discusses Internet protocol (IP) and subnets and describes how IP may operate over asynchronous transfer mode (ATM). Topics include TCP (transmission control protocol), ATM cells and adaptation layers, a basic architectural model for IP over ATM, address resolution, mapping IP to a subnet technology, and connection management strategy. (LRW)

  20. A Robust Statistical Estimation of Internet Traffic

    CERN Document Server

    Chabchoub, Yousra; Guillemin, Fabrice; Robert, Philippe

    2009-01-01

    A new method of estimating flow characteristics in the Internet is developped in this paper. For this purpose, a new set of random variables (referred to as observables) is defined. When dealing with sampled traffic, these observables can easily be computed from sampled data. By adopting a convenient mouse/elephant dichotomy also {\\em dependent on traffic}, it is shown how these variables give a {\\em robust} statistical information of long flows. A mathematical framework is developed to estimate the accuracy of the method. As an application, it is shown how one can estimate the number of long TCP flows when only sampled traffic is available. The algorithm proposed is tested against experimental data collected from different types of IP traffic.

  1. Network Characteristics of Video Streaming Traffic

    CERN Document Server

    Rao, Ashwin; Barakat, Chadi; Legout, Arnaud; Towsley, Don; Dabbous, Walid

    2011-01-01

    Video streaming represents a large fraction of Internet traffic. Surprisingly, little is known about the network characteristics of this traffic. In this paper, we study the network characteristics of the two most popular video streaming services, Netflix and YouTube. We show that the streaming strategies vary with the type of the application (Web browser or native mobile application), and the type of container (Silverlight, Flash, or HTML5) used for video streaming. In particular, we identify three different streaming strategies that produce traffic patterns from non-ack clocked ON-OFF cycles to bulk TCP transfer. We then present an analytical model to study the potential impact of these streaming strategies on the aggregate traffic and make recommendations accordingly.

  2. TCP/IP拥塞控制研究%A Survey of Congestion Control in the Internet

    Institute of Scientific and Technical Information of China (English)

    罗万明; 林闯; 阎保平

    2001-01-01

    综述了Internet上TCP/IP拥塞控制研究方面一些最新的工作,分析了拥塞控制的原理、TCP/IP拥塞控制所使用的典型技术,并着重论述了TCP/IP拥塞控制所面临的问题,这包括自相似性问题、效率问题、公平性问题、算法改进、区分服务和多点广播中拥塞控制和TCP/IP在特殊网络(ATM网和卫星网)上拥塞控制等问题,并提出了其进一步的研究方向.%This is a review paper on recent works about TCP/IP congestioncontrol of Internet. A summary of the techniques considered in the literatures is presented. Several reasons cause Internet congestion control. The typical techniques of congestion control include TCP and IP congestion control. The traditional end-to-end congestion control mechanisms of TCP which employs an Additive Increase Multiplicative Decrease (AIMD) algorithm have been a critical factor in the robustness of the Internet.Modern implementations of TCP contain four intertwined algorithms: slow start, congestion avoidance, fast retransmit and fast recovery. In this paper, the details of the above four algorithms and the improvements to TCP, such as Reno, Tahoe, SACK, Vegas, are investigated. Self-similarity, efficiency and fairness of TCP congestion control are also discussed. However, the Internet is no long a small community, and it is no longer practical to rely on all end-nodes to use end-to-end congestion control for best effort traffic. Similarly, it is no longer possible to rely on all developers to incorporate end-to-end congestion control in their Internet applications. The network itself must now participates in controlling its own resource utilization. Assuming the Internet will continue to become congested due to a scarcity of resources such as bandwidth and buffer, this proposition leads to several possible approaches for congestion control. One approach is to improve the continued use of end-to-end congestion control, as the primary mechanism to share

  3. 提高TCP吞吐量的拥塞控制算法%Congestion control algorithm for TCP throughput enhancement

    Institute of Scientific and Technical Information of China (English)

    徐功文; 李学东; 张志军; 许丽娜

    2011-01-01

    为了在有线和无线共存的网络中提高TCP吞吐量,基于常量窗口理论,提出了一种新的拥塞控制算法C-TCP.分析了C-TCP算法发送方在生命周期中经历的3个阶段,设计了有线/无线网络方案,通过NS2仿真平台获取了C-TCP拥塞窗口的最佳值,把该值设置为实验所需的常量值.基于无拥塞的单TCP链路和拥塞的多TCP链路两种情况,无线子网在常量差错率和突发差错两种状态下,分别仿真实现了C-TCP、TCP Reno和TCPW这3种算法的吞吐量性能实验.仿真实验结果表明,C-TCP算法在吞吐量上优于其他两种算法.%To enhance TCP throughput in wired/wireless network, a new congestion control algorithm (C-TCP) is proposed based on the constant windows theory. Firstly three phases in C-TCP sender lifetime are analyzed, and a wired/wireless network is designed. Based on NS2 simulation platform, an optimal congestion window for C-TCP is determined and this window is kept constant for the following experiment. Based on no-congestion single TCP link and congestion multiple TCP links, in the context of wireless subnet under both constant bit error rates and burst error, the simulations on throughput are carried out including C-TCP, TCP Reno and TCPW these three algorithms. The results show that C-TCP algorithm is superior to the other two algorithms in throughput.

  4. IMPLEMENTASI PROTOKOL TCP/IP UNTUK PENGENDALIAN KOMPUTER JARAK JAUH

    Directory of Open Access Journals (Sweden)

    Rudy Adipranata

    2002-01-01

    Full Text Available This day, computer networking has become important necessity for data exchange between computers. And along with the growing of number of computer in a network, the difficulty for managing that network also increased. Because of that reality, in this paper will be build application for remote controlling computer using TCP/IP protocol. This application build using Delphi 5.0 programming language and dWinsock 2.75, component interface for Windows Socket API which is created especially for Delphi language, and separate to two sub applications, namely server application, which run on computer to be controlled and the secondly is client application, run on controller computer. In this application, data text or binary will be send, so two pair components will be used : TTextServer - TTextClient and TBinaryServer- TBinaryClient. The functions which implemented in this applications are : lock and unlock computer, reboot, shutdown, execute remote program, send message, capture screen and view remote programs. Test is doing on internal network and internet network, and the result of that test for internal network, all of functions can be activated perfectly without significant delay (less than 1 second. But for internet network, there is delay, which the number variable depend on data traffic at that moment. Abstract in Bahasa Indonesia : Sekarang ini jaringan komputer sudah menjadi suatu kebutuhan yang sangat penting untuk mempermudah pertukaran data antar komputer. Dan seiring dengan makin berkembangnya jumlah komputer pada suatu jaringan, maka makin bertambah pula tingkat kesulitan untuk mengelola jaringan tersebut. Oleh sebab itu pada penelitian ini akan dibuat aplikasi untuk mengendalikan komputer secara jarak jauh dengan menggunakan protokol TCP/IP. Aplikasi ini dibuat dengan menggunakan bahasa pemrograman Delphi 5.0 dan dWinsock 2.75 yang merupakan komponen antar muka Windows Socket API yang dikhususkan untuk bahasa pemrograman Delphi, dan terdiri

  5. Gantry crane control via Modbus TCP

    OpenAIRE

    Arm, Jakub

    2012-01-01

    Modbus TCP je protokol pro komunikaci po ethernetovém rozhraní. Cílem této práce je realizace řízení daného modelu jeřábu z osobního počítače pomocí daného zařízení komunikujícího protokolem Modbus TCP přes ethernetové rozhraní. Řízení je realizováno z uživatelské aplikace naprogramované v C# a z webového rozhraní běžícího na vytvořeném HTTP serveru. Oboje rozhraní využívá vytvořenou knihovnu, která je naprogramována v jazyce C a komunikují přes Modbus TCP se zařízením Modicon Momentum, které...

  6. Identification of a TcpC-TcpQ Outer Membrane Complex Involved in the Biogenesis of the Toxin-Coregulated Pilus of Vibrio cholerae

    OpenAIRE

    Bose, Niranjan; Taylor, Ronald K.

    2005-01-01

    The toxin-coregulated pilus (TCP) of Vibrio cholerae and the soluble TcpF protein that is secreted via the TCP biogenesis apparatus are essential for intestinal colonization. The TCP biogenesis apparatus is composed of at least nine proteins but is largely uncharacterized. TcpC is an outer membrane lipoprotein required for TCP biogenesis that is a member of the secretin protein superfamily. In the present study, analysis of TcpC in a series of strains deficient in each of the TCP biogenesis p...

  7. An analysis of network traffic classification for botnet detection

    DEFF Research Database (Denmark)

    Stevanovic, Matija; Pedersen, Jens Myrup

    2015-01-01

    Botnets represent one of the most serious threats to the Internet security today. This paper explores how can network traffic classification be used for accurate and efficient identification of botnet network activity at local and enterprise networks. The paper examines the effectiveness of detec...... to the optimization of traffic analysis and the correlation of findings from the three analysis methods in order to identify compromised hosts within the network.......Botnets represent one of the most serious threats to the Internet security today. This paper explores how can network traffic classification be used for accurate and efficient identification of botnet network activity at local and enterprise networks. The paper examines the effectiveness...... of detecting botnet network traffic using three methods that target protocols widely considered as the main carriers of botnet Command and Control (C&C) and attack traffic, i.e. TCP, UDP and DNS. We propose three traffic classification methods based on capable Random Forests classifier. The proposed methods...

  8. Media-TCP: A Quality-Centric TCP-Friendly Congestion Control for Multimedia Transmission

    CERN Document Server

    Shiang, Hsien-Po

    2009-01-01

    In this paper, we propose a quality-centric congestion control for multimedia streaming over IP networks, which we refer to as media-TCP. Unlike existing congestion control schemes that adapt a user's sending rate merely to the network condition, our solution adapts the sending rate to both the network condition and the application characteristics by explicitly considering the distortion impacts, delay deadlines, and interdependencies of different video packet classes. Hence, our media-aware solution is able to provide differential services for transmitting various packet classes and thereby, further improves the multimedia streaming quality. We model this problem using a Finite-Horizon Markov Decision Process (FHMDP) and determine the optimal congestion control policy that maximizes the long-term multimedia quality, while adhering to the horizon- TCP-friendliness constraint, which ensures long-term fairness with existing TCP applications. We show that the FHMDP problem can be decomposed into multiple optimal...

  9. Research on Application of Perceived QoS Guarantee through Infrastructure Specific Traffic Parameter Optimization

    Directory of Open Access Journals (Sweden)

    Vikram Jeet Singh

    2014-02-01

    Full Text Available The technological developments in the fields of multimedia clinical applications and communication networks require a specific analysis to increase the efficiency of network based healthcare services. In this work, we computed the optimum transmission parameter (data packet size for applications needed to guarantee the perceived quality of service in the proposed ubiquitous healthcare network. This has been carried out through NS2 based simulation of a state wide area network infrastructure implemented in Himachal Pradesh, a state with diverse geographical terrain situated in the Western Himalayan region of India. The various types of healthcare applications and services have been classified into different classes according to their perceived QOS requirements as per the guidelines in ITU report on network performance objectives. The infrastructure specific optimum values of data packet size for these QoS classes have been computed. Network based healthcare applications and services running on both TCP and UDP type of traffic have been presented in this paper.

  10. TCP-ATCA: Improved Transmission Control Algorithm in Satellite Network

    Institute of Scientific and Technical Information of China (English)

    Liu Feng; Liu Hengna; Zhao Han

    2008-01-01

    An adaptive transmission control algorithm based on TCP (TCP-ATCA) is proposed to reduce the effects of long propagation de- lay and high link error rate of the satellite network on the performances. The flow control and the error recovery are differentiated by combined dynamic random early detection-explicit congestion notification (DRED-ECN) algorithm, and, moreover, the pertaining con- gestion control methods are used in TCP-ATCA to improve the throughput. By introducing the entire recovery algorithm, the unneces- sary congestion window decrease is reduced, and the throughput and fairness are improved. Simulation results show that, compared with TCP-Reno, TCP-ATCA provides a better throughput performance when the link capacity is higher (≥ 600 packet/s), and roughly the same when it is lower. At the same time, TCP-ATCA also increases fairness and reduces transmission delay.

  11. Evaluating the Performance of TCP Stacks for High-Speed Networks.

    OpenAIRE

    Even, B.; Li, Y.; Leith, D. J.

    2006-01-01

    In this paper we present experimental results evaluating the performance of the Scalable-TCP, HS-TCP, BICTCP, FAST-TCP and H-TCP proposals for changes to the TCP congestion control algorithm to improve performance in highspeed network paths.

  12. Compatibility Issues of IPSec and TCP in Wireless Networks

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hai-yang; XIN Yang

    2004-01-01

    Due to the problems arising when the Transmission Control Protocol (TCP) is applied over wireless networks, many TCP performance enhancement mechanisms have been proposed. However, such mechanisms aren't compatible with IPSec protocol. The paper reviews the TCP performance enhancement mechanisms in wireless networks. Then the conflicts between them are analyzed. Several proposals for solving theconflicts are discussed, and their benefit and limitations are examined.

  13. Updatable Queue Protocol Based On TCP For Virtual Reality Environment

    CERN Document Server

    Al-Howaide, Ala'a Z; Salhieh, Ayad M

    2011-01-01

    The variance in number and types of tasks required to be implemented within Distributed Virtual Environments (DVE) highlights the needs for communication protocols can achieve consistency. In addition, these applications have to handle an increasing number of participants and deal with the difficult problem of scalability. Moreover, the real-time requirements of these applications make the scalability problem more difficult to solve. In this paper, we have implemented Updatable Queue Abstraction protocol (UQA) on TCP (TCP-UQA) and compared it with original TCP, UDP, and Updatable Queue Abstraction based on UDP (UDP-UQA) protocols. Results showed that TCP-UQA was the best in queue management.

  14. Wire-Compatible Unordered Delivery in TCP and TLS

    CERN Document Server

    Iyengar, Janardhan; Amin, Syed Obaid; Nowlan, Michael F; Tiwari, Nabin

    2011-01-01

    The performance of many common Internet applications can benefit from out-of-order delivery, a feature all IETF transports since TCP have included. Yet latency-sensitive applications still frequently build on in-order TCP despite its performance drawbacks, for reasons such as network compatibility and TCP's cultural inertia. We introduce uTCP, an API extension that adds out-of-order delivery support without changing TCP's wire protocol, by delivering received TCP segments to the application immediately on arrival along with sequence number metadata. To obtain robust out-of-order delivery across middleboxes that may re-segment TCP flows, the application employs a "record-marking" content encoding such as COBS, allowing the receiver to extract records from a byte stream with arbitrary holes. TLS can also serve as such an encoding, enabling applications to obtain out-of-order delivery in a stream indistinguishable in the network from conventional TLS over TCP. With uTCP, for example, voice/videoconferencing appl...

  15. Transformation and biodegradation of 1,2,3-trichloropropane (TCP)

    OpenAIRE

    Samin, Ghufrana; Janssen, Dick B.

    2012-01-01

    Purpose 1,2,3-Trichloropropane (TCP) is a persistent groundwater pollutant and a suspected human carcinogen. It is also is an industrial chemical waste that has been formed in large amounts during epichlorohydrin manufacture. In view of the spread of TCP via groundwater and its toxicity, there is a need for cheap and efficient technologies for the cleanup of TCP-contaminated sites. In situ or on-site bioremediation of TCP is an option if biodegradation can be achieved and stimulated. This pap...

  16. Transformation and biodegradation of 1,2,3-trichloropropane (TCP)

    OpenAIRE

    Samin, Ghufrana; Janssen, Dick B.; Kronberg, Leif

    2012-01-01

    1,2,3-Trichloropropane (TCP) is a persistent groundwater pollutant and a suspected human carcinogen. It is also is an industrial chemical waste that has been formed in large amounts during epichlorohydrin manufacture. In view of the spread of TCP via groundwater and its toxicity, there is a need for cheap and efficient technologies for the cleanup of TCP-contaminated sites. In situ or on-site bioremediation of TCP is an option if biodegradation can be achieved and stimulated. This paper prese...

  17. Traffic Measurement for Traffic Engineering in IP/MPLS Based Telecom Core Networks

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Telecommunication networks will become IP-based networks with all voice, data and multimedia traffic carried as packets with appropriate quality and class of service for each traffic type. It is very important for service provider to apply Traffic Engineering (TE) with the dramatic growth of networks traffic. In this paper, we discuss traffic engineering based on IP/MPLS and emphasize traffic measurement in telecom core networks. We specify the technology and scientific principles of the measurement, modeling, characterization, and the traffic flow matrix. The paper concludes with a preliminary analysis of TE measurement and a discussion about the development of TE measurement.

  18. Modeling of Packet Switched Network over TCP Veno: TCP Improvement for Transmission over Wireless Access Networks.

    Directory of Open Access Journals (Sweden)

    Baswaraj

    2012-02-01

    Full Text Available Computer networks form an essential substrate for the multitude of distributed application which is nowan essential part of modern business and personal life. It is important to optimize the performance ofcomputer networks, so that users can derive optimum utility from the expertise in network infrastructure.Most networks perform well when lightly used, but problems appear when network load increases. Thisloss of network performance when a network is heavily loaded is called congestion. Wired networks arebecoming an integral part of the Internet. Unlike wireless networks, random packet loss due to bit errorsis not negligible in wired networks, and this causes significant performance degradation of transmissioncontrol protocol (TCP. We propose and study a novel end-to-end congestion control mechanism calledTCP Veno that is simple and effective for dealing with random packet loss. A key ingredient of Veno isthat it monitors the network congestion level and uses that information to decide whether packet lossesare likely to be due to congestion or random bit errors. Specifically: A. it refines the multiplicativedecrease algorithm of TCP Reno—the most widely deployed TCP version in practice—by adjusting theslow-start threshold according to the perceived network congestion level rather than a fixed drop factorand B it refines the linear increase algorithm so that the connection can stay longer in an operatingregion in which the network bandwidth is fully utilized, based on extensive network testbed experimentsand live Internet measurements.

  19. Phase diagram distortion from traffic parameter averaging.

    NARCIS (Netherlands)

    Stipdonk, H. Toorenburg, J. van & Postema, M.

    2010-01-01

    Motorway traffic congestion is a major bottleneck for economic growth. Therefore, research of traffic behaviour is carried out in many countries. Although well describing the undersaturated free flow phase as an almost straight line in a (k,q)-phase diagram, congested traffic observations and theori

  20. Poster: Evaluating Android Applications with Multipath TCP

    OpenAIRE

    De Coninck, Quentin; Baerts, Matthieu; Hesmans, Benjamin; Bonaventure, Olivier; 21st Annual International Conference on Mobile Computing and Networking

    2015-01-01

    Smartphones are the most popular mobile multihomed devices. End-user expects that thanks to their WiFi and cellular interfaces, they are able to seamlessly use all available networks. Unfortunately, reality tells us that seamless coexistence between cellular and WiFi is not as simple as what the user expect. Several cellular/WiFi coexistence technologies have been proposed during the last years. Some of them have been deployed. Recently, Multipath TCP received a lot of attention when it was s...

  1. TCP- ja UDP-porttien uudelleenohjaus ohjelmallisesti

    OpenAIRE

    Rapo, Kari

    2010-01-01

    Tämän työn tarkoituksena oli suunnitella ja toteuttaa ohjelma, joka kykenee ohjaamaan tietokoneen UDP- ja TCP-porteista vastaanotettua liikennettä uuteen osoitteeseen. Kohdeosoite voi sijaita missä tahansa verkossa, mihin kyseisellä tietokoneella on suora yhteys tai reitti. Ohjelma suorittaa liikenteelle osoitemuunnoksen, jonka jälkeen liikenne lähetetään edelleen ennalta määriteltyihin kohdeosoitteisiin. Tätä kutsutaan porttien uudelleenohjaamiseksi. Ohjelman suunnittelu aloitettiin, kosk...

  2. Performance Analysis of TCP-Reno and TCP-Sack in the Case of a Single Source

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This work explores the behavior of both TCP-Reno and TCP-Sack under a simple scenario, where a single TCP source transmits the packets continuously over a single bottleneck node characterized by its queue size, bandwidth and propagation delay. The analysis allows to derive the performance of TCP, the utilization tends to 75% of the bottleneck throughput when the bandwidth × propagation delay pipe becomes very large, while it tends to 100% when the queuing delays are predominant because the queue is never empty. In the transient analysis we show how the initial phase of the session can degrade the performances. These results are proved through simulation.

  3. TCP flow control using link layer information in mobile networks

    Science.gov (United States)

    Koga, Hiroyuki; Kawahara, Kenji; Oie, Yuji

    2002-07-01

    Mobile Networks have been expanding and IMT-2000 further increases their available bandwidth over wireless links. However, TCP, which is a reliable end-to-end transport protocol, is tuned to perform well in wired networks where bit error rates are very low and packet loss occurs mostly because of congestion. Although a TCP sender can execute flow control to utilize as much available bandwidth as possible in wired networks, it cannot work well in wireless networks characterized by high bit error rates. In the next generation mobile systems, sophisticated error recovery technologies of FEC and ARQ are indeed employed over wireless links, i.e., over Layer 2, to avoid performance degradation of upper layers. However, multiple retransmissions by Layer 2 ARQ can adversely increase transmission delay of TCP segments, which will further make TCP unnecessarily increase RTO (Retransmission TimeOut). Furthermore, a link bandwidth assigned to TCP flows can change in response to changing air conditions to use wireless links efficiently. TCP thus has to adapt its transmission rate according to the changing available bandwidth. The major goal of this study is to develop a receiver-based effective TCP flow control without any modification on TCP senders, which are probably connected with wired networks. For this end, we propose a TCP flow control employing some Layer 2 information on a wireless link at the mobile station. Our performance evaluation of the proposed TCP shows that the receiver-based TCP flow control can moderate the performance degradation very well even if FER on Layer 2 is high.

  4. Traffic Monitor

    Science.gov (United States)

    1992-01-01

    Mestech's X-15 "Eye in the Sky," a traffic monitoring system, incorporates NASA imaging and robotic vision technology. A camera or "sensor box" is mounted in a housing. The sensor detects vehicles approaching an intersection and sends the information to a computer, which controls the traffic light according to the traffic rate. Jet Propulsion Laboratory technical support packages aided in the company's development of the system. The X-15's "smart highway" can also be used to count vehicles on a highway and compute the number in each lane and their speeds, important information for freeway control engineers. Additional applications are in airport and railroad operations. The system is intended to replace loop-type traffic detectors.

  5. Protection Methods in Traffic Engineering MPLS Networks

    OpenAIRE

    Kimani, Peter

    2013-01-01

    The objective of this project was to perform a theoretical review of Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) technology and traffic protection methods in the Traffic Engineering on MPLS networks and implement traffic protection in an ISP’s (Internet Service Provider’s) network. The project was carried out first by introducing VPN (Virtual Private Network) and its different categories and modes. VPN is closely related to MPLS. The MPLS-TE was introduced and its operat...

  6. 轻量级嵌入式TCP/IP协议栈的设计%Design of Light-weight TCP/IP Stack in Embedded System

    Institute of Scientific and Technical Information of China (English)

    王力生; 梅岩; 曹南洋

    2007-01-01

    介绍了引入轻量级TCP/IP协议栈的背景,描述了标准TCP/IP协议栈,分析了嵌入式系统中TCP/IP协议栈的特点和设计的思路,总结了轻量级TCP/IP协议栈和标准TCP/IP协议栈的区别.

  7. RATE-ADJUSTMENT ALGORITHM FOR AGGREGATE TCP CONGESTION CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    P. TINNAKORNSRISUPHAP, ET AL

    2000-09-01

    The TCP congestion-control mechanism is an algorithm designed to probe the available bandwidth of the network path that TCP packets traverse. However, it is well-known that the TCP congestion-control mechanism does not perform well on networks with a large bandwidth-delay product due to the slow dynamics in adapting its congestion window, especially for short-lived flows. One promising solution to the problem is to aggregate and share the path information among TCP connections that traverse the same bottleneck path, i.e., Aggregate TCP. However, this paper shows via a queueing analysis of a generalized processor-sharing (GPS) queue with regularly-varying service time that a simple aggregation of local TCP connections together into a single aggregate TCP connection can result in a severe performance degradation. To prevent such a degradation, we introduce a rate-adjustment algorithm. Our simulation confirms that by utilizing our rate-adjustment algorithm on aggregate TCP, connections which would normally receive poor service achieve significant performance improvements without penalizing connections which already receive good service.

  8. Genome-wide analysis of TCP family in tobacco.

    Science.gov (United States)

    Chen, L; Chen, Y Q; Ding, A M; Chen, H; Xia, F; Wang, W F; Sun, Y H

    2016-01-01

    The TCP family is a transcription factor family, members of which are extensively involved in plant growth and development as well as in signal transduction in the response against many physiological and biochemical stimuli. In the present study, 61 TCP genes were identified in tobacco (Nicotiana tabacum) genome. Bioinformatic methods were employed for predicting and analyzing the gene structure, gene expression, phylogenetic analysis, and conserved domains of TCP proteins in tobacco. The 61 NtTCP genes were divided into three diverse groups, based on the division of TCP genes in tomato and Arabidopsis, and the results of the conserved domain and sequence analyses further confirmed the classification of the NtTCP genes. The expression pattern of NtTCP also demonstrated that majority of these genes play important roles in all the tissues, while some special genes exercise their functions only in specific tissues. In brief, the comprehensive and thorough study of the TCP family in other plants provides sufficient resources for studying the structure and functions of TCPs in tobacco. PMID:27323069

  9. Optimising TCP for cloud-based mobile networks

    DEFF Research Database (Denmark)

    Artuso, Matteo; Christiansen, Henrik Lehrmann

    2016-01-01

    protocols should therefore be adjusted to cope with the peculiarities of these networks. In this paper, we investigate an optimized design of the Transmission Control Protocol (TCP), as it plays a central role in all-IP mobile networks to ensure optimal performances for application-layer services. TCP...

  10. Transformation and biodegradation of 1,2,3-trichloropropane (TCP)

    NARCIS (Netherlands)

    Samin, Ghufrana; Janssen, Dick B.; Kronberg, Leif

    2012-01-01

    1,2,3-Trichloropropane (TCP) is a persistent groundwater pollutant and a suspected human carcinogen. It is also is an industrial chemical waste that has been formed in large amounts during epichlorohydrin manufacture. In view of the spread of TCP via groundwater and its toxicity, there is a need for

  11. Recent TCP(Tidal Current Power) projects in Korea

    Institute of Scientific and Technical Information of China (English)

    Chul; Hee; JO; Kang; Hee; LEE; Yu; Ho; RHO

    2010-01-01

    Having strong current on the west coast with up to 10 m tidal range in Korea,there are many suitable and applicable locations for TCP(Tidal Current Power) application in Korea.Not only the west coast,but also the south west regions having narrow channels between islands creating fast ocean stream are suitable for TCP.The first TCP application in Korea is 1 MW helical VAT(Vertical Axis Turbine) device installed in Wooldolmog area in 2008.The first HAT(Horizontal Axis Turbine) TCP device of 25 KW was developed and installed in cooling water weir of Samchonpo power plant in 2008.Furthermore,a 100 kW prototype HAT TCP device is being planned to be installed in Daebang strait in 2009.Another big project would be Inchon TCP farm of 200 MW on the west coast in Korea.The consortium of 5 members was formed in April,2009.This site will be the largest TCP site in the world.The paper describes recent TCP projects in Korea with background and environmental conditions of the projects.

  12. Genome-wide Identification of TCP Family Transcription Factors from Populus euphratica and Their Involvement in Leaf Shape Regulation

    Science.gov (United States)

    Ma, Xiaodong; Ma, Jianchao; Fan, Di; Li, Chaofeng; Jiang, Yuanzhong; Luo, Keming

    2016-01-01

    Higher plants have been shown to experience a juvenile vegetative phase, an adult vegetative phase, and a reproductive phase during its postembryonic development and distinct lateral organ morphologies have been observed at the different development stages. Populus euphratica, commonly known as a desert poplar, has developed heteromorphic leaves during its development. The TCP family genes encode a group of plant-specific transcription factors involved in several aspects of plant development. In particular, TCPs have been shown to influence leaf size and shape in many herbaceous plants. However, whether these functions are conserved in woody plants remains unknown. In the present study, we carried out genome-wide identification of TCP genes in P. euphratica and P. trichocarpa, and 33 and 36 genes encoding putative TCP proteins were found, respectively. Phylogenetic analysis of the poplar TCPs together with Arabidopsis TCPs indicated a biased expansion of the TCP gene family via segmental duplications. In addition, our results have also shown a correlation between different expression patterns of several P. euphratica TCP genes and leaf shape variations, indicating their involvement in the regulation of leaf shape development. PMID:27605130

  13. Genome-wide Identification of TCP Family Transcription Factors from Populus euphratica and Their Involvement in Leaf Shape Regulation.

    Science.gov (United States)

    Ma, Xiaodong; Ma, Jianchao; Fan, Di; Li, Chaofeng; Jiang, Yuanzhong; Luo, Keming

    2016-01-01

    Higher plants have been shown to experience a juvenile vegetative phase, an adult vegetative phase, and a reproductive phase during its postembryonic development and distinct lateral organ morphologies have been observed at the different development stages. Populus euphratica, commonly known as a desert poplar, has developed heteromorphic leaves during its development. The TCP family genes encode a group of plant-specific transcription factors involved in several aspects of plant development. In particular, TCPs have been shown to influence leaf size and shape in many herbaceous plants. However, whether these functions are conserved in woody plants remains unknown. In the present study, we carried out genome-wide identification of TCP genes in P. euphratica and P. trichocarpa, and 33 and 36 genes encoding putative TCP proteins were found, respectively. Phylogenetic analysis of the poplar TCPs together with Arabidopsis TCPs indicated a biased expansion of the TCP gene family via segmental duplications. In addition, our results have also shown a correlation between different expression patterns of several P. euphratica TCP genes and leaf shape variations, indicating their involvement in the regulation of leaf shape development. PMID:27605130

  14. Effect of Water-Glass Coating on HA and HA-TCP Samples for MSCs Adhesion, Proliferation, and Differentiation.

    Science.gov (United States)

    Bajpai, Indu; Kim, Duk Yeon; Kyong-Jin, Jung; Song, In-Hwan; Kim, Sukyoung

    2016-01-01

    Ca-P and silicon based materials have become very popular as bone tissue engineering materials. In this study, water-glass (also known as sodium silicate glass) was coated on sintered hydroxyapatite (HA) and HA-TCP (TCP stands for tricalcium phosphate) samples and subsequently heat-treated at 600°C for 2 hrs. X-rays diffraction showed the presence of β- and α-TCP phases along with HA in the HA-TCP samples. Samples without coating, with water-glass coating, and heat-treated after water-glass coating were used to observe the adhesion and proliferation response of bone marrow derived-mesenchymal stem cells (MSCs). Cell culture was carried out for 4 hrs, 1 day, and 7 days. Interestingly, all samples showed similar response for cell adhesion and proliferation up to 7-day culture but fibronectin, E-cadherin, and osteogenic differentiation related genes (osteocalcin and osteopontin) were significantly induced in heat-treated water-glass coated HA-TCP samples. A water-glass coating on Ca-P samples was not found to influence the cell proliferation response significantly but activated some extracellular matrix genes and induced osteogenic differentiation in the MSCs. PMID:27429988

  15. Chitosan Fibers Modified with HAp/β–TCP Nanoparticles

    Directory of Open Access Journals (Sweden)

    Dariusz Wawro

    2011-10-01

    Full Text Available This paper describes a method for preparing chitosan fibers modified with hydroxyapatite (HAp, tricalcium phosphate (β-TCP, and HAp/β-TCP nanoparticles. Fiber-grade chitosan derived from the northern shrimp (Pandalus borealis and nanoparticles of tricalcium phosphate (β-TCP and hydroxyapatite (HAp suspended in a diluted chitosan solution were used in the investigation. Diluted chitosan solution containing nanoparticles of Hap/β-TCP was introduced to a 5.16 wt% solution of chitosan in 3.0 wt% acetic acid. The properties of the spinning solutions were examined. Chitosan fibers modified with nanoparticles of HAp/β-TCP were characterized by a level of tenacity and calcium content one hundred times higher than that of regular chitosan fibers.

  16. Novel evaluation method of TCP performance over satellite links

    Institute of Scientific and Technical Information of China (English)

    Wang Lina; Gu Xuemai

    2006-01-01

    A novel and efficient method to evaluate the transmission control protocol (TCP) performance over satellite links is presented. A TCP module is divided into three functional blocks, namely data processing, congestion control and error control. The re-established TCP module is easy to update TCP congestion control strategy or error control strategy. With the proposed analysis approach, the interactions between different congestion control and error control mechanisms, as well as the performance of various combination protocols in satellite environments have been investigated. Simulation results obtained through a series of experiments have shown that SNACK-based error control strategy can perform well with any other congestion control strategy. The best performance can be achieved by TCP New Reno congestion control strategy and SNACK-based error control strategy.

  17. Characterization of P2P IPTV Traffic: Scaling Analysis

    CERN Document Server

    Silverston, Thomas; Salamatian, Kave

    2007-01-01

    P2P IPTV applications arise on the Internet and will be massively used in the future. It is expected that P2P IPTV will contribute to increase the overall Internet traffic. In this context, it is important to measure the impact of P2P IPTV on the networks and to characterize this traffic. During the 2006 FIFA World Cup, we performed an extensive measurement campaign. We measured network traffic generated by broadcasting soccer games by the most popular P2P IPTV applications, namely PPLive, PPStream, SOPCast and TVAnts. From the collected data, we characterized the P2P IPTV traffic structure at different time scales. To the best of our knowledge, this is the first work, which presents a complete multiscale analysis of the P2P IPTV traffic. Our observations show that the network traffic has not the same scale behavior whether the applications use TCP or UDP. For all the applications, the download traffic is different from the upload traffic and the signaling traffic has an impact on the download traffic.

  18. Active Queue Management in TCP Networks Based on Fuzzy-Pid Controller

    Directory of Open Access Journals (Sweden)

    Hossein ASHTIANI

    2012-01-01

    Full Text Available We introduce a novel and robust active queue management (AQM scheme based on a fuzzy controller, called hybrid fuzzy-PID controller. In the TCP network, AQM is important to regulate the queue length by passing or dropping the packets at the intermediate routers. RED, PI, and PID algorithms have been used for AQM. But these algorithms show weaknesses in the detection and control of congestion under dynamically changing network situations. In this paper a novel Fuzzy-based proportional-integral derivative (PID controller, which acts as an active queue manager (AQM for Internet routers, is proposed. These controllers are used to reduce packet loss and improve network utilization in TCP/IP networks. A new hybrid controller is proposed and compared with traditional RED based controller. Simulations are carried out to demonstrate the effectiveness of the proposed method and show that, the new hybrid fuzzy PID controller provides better performance than random early detection (RED and PID controllers

  19. Truncated power control for improving TCP/IP performance over CDMA wireless links

    DEFF Research Database (Denmark)

    Cianca, Ernestina; Prasad, Ramjee; De Sanctis, Mauro;

    2005-01-01

    The issue of the performance degradation of transmission control protocol/Internet Protocol (TCP/IP) over wireless links due to the presence of noncongestion-related packet losses has been addressed with a physical layer approach. The effectiveness of automatic repeat request techniques...... in enhancing TCP/IP performance depends on the tradeoff between frame transmission delay and residual errors after retransmissions. The paper shows how a truncated power control can be effectively applied to improve that tradeoff so that a higher transmission reliability is provided without increasing...... the frame transmission delay through the radio link layer and without increasing the energy consumption. An analytical framework has been developed to show the feasibility and effectiveness of the proposed power control. The analytical results, which are carried out assuming a constant multiuser...

  20. ON THE RELEVANCE OF ON-LINE TRAFFIC ENGINEERING

    NARCIS (Netherlands)

    Fu, B.; Uhlig, S.P.W.G.

    The evaluation of dynamic Traffic Engineering (TE) algorithms is usually carried out using some specific network(s), traffic pattern(s) and traffic engineering objective(s). As the behavior of a TE algorithm is a consequence of the interactions between the network, the traffic demand and the algorit

  1. Splitting TCP for MPI Applications Executed on Grids

    OpenAIRE

    Glück, Olivier; Mignot, Jean-Christophe

    2011-01-01

    In this paper, we first study the interaction between MPI applications and TCP on grids. Then, we propose MPI5000, a transparent applicative layer between MPI and TCP, using proxies to improve the execution of MPI applications on a grid. Proxies aim at splitting TCP connections in order to detect losses faster and avoid to return in a slow-start phase after an idle time. Finally, we evaluate our layer executing the NAS Parallel Benchmarks on Grid5000, the French research grid, using MPICH2. T...

  2. The quantitative analysis of the problem of TCP Incast%TCP Incast 问题的定量分析

    Institute of Scientific and Technical Information of China (English)

    赵智勇

    2014-01-01

    TCP Incast is the typical problem that influences the capability of the modern data center . Comprehending the method of resolving TCP Incast is very important for improving business ability of the data center .Through mathematical models , this paper quantitatively analyzes the factors , such as data block size, the number of concurrent senders and TCP minimum retransmission time out (RTOmin), which impact on TCP Incast , and also sets up a mathematical model for predicting the onset of incast leaded by small data blocks .%TCP Incast问题是影响现代数据中心性能的典型问题。正确理解TCP Incast问题的解决方案,对提高数据中心的业务能力具有重要意义。通过数学模型,定量分析了数据块大小、并发数量及TCP最小重传超时( RTOmin )等因素对TCP Incast 问题的影响,构建并验证了一个预测小数据块Incast问题发生的数学模型。

  3. In Vitro Characterizations of PLLA/β-TCP Porous Matrix Materials and RMSC-PLLA-β-TCP Composite Scaffolds

    Institute of Scientific and Technical Information of China (English)

    Dali ZHOU; Weizhong YANG; Guangfu Yin; Changqiong ZHENG; Yun ZHANG; Huaiqing CHEN; Rui CHEN

    2004-01-01

    To develop a novel degradable poly (L-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) bioactive materials for bone tissue engineering, β-TCP powder was produced by a new wet process. Porous scaffolds were prepared by three steps, I.e. Solvent casting, compression molding and leaching stage. Factors influencing the compressive strength and the degradation behavior of the porous scaffold, e.g. Weight fraction of pore forming agent-sodium chloride (NaCl), weight ratio of PLLA: β-TCP, the particle size ofβ-TCP and the porosity, were discussed in details. Rat marrow stromal cells (RMSC) were incorporated into the composite by tissue engineering approach. Biological and osteogenesis potential of the composite scaffold were determined with MTT assay, alkaline phosphatase (ALP) activity and bone osteocalcin (OCN) content evaluation. Results show that PLLA/β-TCP bioactive porous scaffold has good mechanical and pore structure with adjustable compressive strength needed for surgery. RMSCs seeding on porous PLLA/β-TCP composite behaves good seeding efficacy, biocompatibility and osteoinductive potential. Osteoprogenitor cells could well penetrate into the material matrix and begin cell proliferation and osteogenic differentiation. Osseous matrix could be formed on the surface of the composite after culturing in vitro. It is expected that the PLLA/β-TCP porous composites are promising scaffolds for bone tissue engineering in prosthesis surgery.

  4. Efficient IP Traffic over Optical Network Based on Wavelength Translation Switching

    DEFF Research Database (Denmark)

    Jha, Vikas; Kalia, Kartik; Chowdhary, Bhawani Shankar;

    2016-01-01

    With the advent of TCP/IP protocol suite the overall era of communication technologies had been redefined. Now, we can’t ignore the presence of huge amount of IP traffic; data, voice or video increasing day by day creating more pressure on existing communicating media and supporting back bone...

  5. Release Kinetics and Antibacterial Efficacy of Microporous β-TCP Coatings

    Directory of Open Access Journals (Sweden)

    Michael Seidenstuecker

    2013-01-01

    Full Text Available Purpose. The aim of this study was to impregnate microporous β-TCP scaffolds with different antibiotic solutions and to determine their release behavior. Materials and Methods. We impregnated a β-TCP scaffold with antibiotics by using three methods: drop, dip, and stream coating with 120 mg/mL of antibiotic solution. After drying for 72 h at 37°C, 2 mL of distilled water was added to the antibiotic-coated plugs and incubated at 37°C. After defined time points (1, 2, 3, 6, 9, and 14 days, the liquid was completely replaced. The extracted liquid was analyzed by capillary zone electrophoresis and the Kirby Bauer disc diffusion test. For statistical analysis, we calculated a mean and standard deviation and carried out an analysis of variance using ANOVA. Results. The VAN and CLI release from the β-TCP scaffolds was rapid, occurring within 24 h with 89 ± 0.8% VAN and 90.4 ± 1.5% CLI regardless of the type of insulation. After six days, the VAN and CLI were completely released. All samples taken at later time points had a VAN or CLI concentration below the detection limit of 4 µg/mL. The released amounts of VAN and CLI within the first three days revealed antimicrobial activity.

  6. TCP Congestion Control for the Networks with Markovian Jump Parameters

    Directory of Open Access Journals (Sweden)

    MOMENI, H. R.

    2011-05-01

    Full Text Available This paper is concerned with the problem of TCP congestion control for the class of communication networks with random parameters. The linear dynamic model of TCP New Reno in congestion avoidance mode is considered which contains round trip delays in both state and input. The randomness of link capacity, round trip time delay and the number of TCP sessions is modeled with a continuous-time finite state Markov process. An Active Queue Management (AQM technique is then used to adjust the queue level of the congested link to a predefined value. For this purpose, a dynamic output feedback controller with mode dependent parameters is synthesized to stochastically stabilize the TCP/AQM dynamics. The procedure of the control synthesis is implemented by solving a linear matrix inequality (LMI. The results are tested within a simulation example and the effectiveness of the proposed design method is verified.

  7. TO IMPROVE THE TCP PERFORMANCE USING CROSS LAYER IN WIRED CUM WIRELESS NETWORK.

    Directory of Open Access Journals (Sweden)

    KANNADASAN. R

    2012-04-01

    Full Text Available Recent development mostly based on the high speed internet access of large amount of data at any time over wireless network. Packets loss can also occur due to link failure in wired cum wireless environment. To reduce the loss rate, packet delay, retransmission time, Wi-Max is proposed with cross layer design. In this paper, to improve the performance TCP in the WI-MAX flow its estimating bandwidth of the each packet, reduce the RTT in retransmission which gives more data transfer rate and also reduce the packet drop ratio. Some layers are merging their functions and provide traffic flow with ARQ in Wi-Max. Each node provides information through Access Point which can uplink and downlink feedback about packet as an ACK or NACK. Retransmission mechanism is used for NACK to resend the lost frame through the access point.

  8. Traffic Dynamics of Computer Networks

    CERN Document Server

    Fekete, Attila

    2008-01-01

    Two important aspects of the Internet, namely the properties of its topology and the characteristics of its data traffic, have attracted growing attention of the physics community. My thesis has considered problems of both aspects. First I studied the stochastic behavior of TCP, the primary algorithm governing traffic in the current Internet, in an elementary network scenario consisting of a standalone infinite-sized buffer and an access link. The effect of the fast recovery and fast retransmission (FR/FR) algorithms is also considered. I showed that my model can be extended further to involve the effect of link propagation delay, characteristic of WAN. I continued my thesis with the investigation of finite-sized semi-bottleneck buffers, where packets can be dropped not only at the link, but also at the buffer. I demonstrated that the behavior of the system depends only on a certain combination of the parameters. Moreover, an analytic formula was derived that gives the ratio of packet loss rate at the buffer ...

  9. Study of dynamical properties in β-Tcp/Ch layers

    Energy Technology Data Exchange (ETDEWEB)

    Mina, A.; Caicedo, J. C. [Universidad del Valle, Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Cali, Valle del Cauca (Colombia); Aperador, W., E-mail: jacaicedoangulo1@gmail.com [Universidad Militar Nueva Granada, Departamento de Ingenieria, 80 Entrada A La KR11 No. 101, Bogota (Colombia)

    2015-07-01

    β-Tricalcium phosphate/Chitosan (β-Tcp/Ch) coatings were deposited on 316l stainless steel (316l Ss) substrates by a cathodic electrodeposition technique at different coating compositions. The crystal lattice arrangements were analyzed by X-ray diffraction, and the results indicated that the crystallographic structure of β-Tcp was affected by the inclusion of the chitosan content. The changes in the surface morphology as a function of increasing chitosan in the coatings via scanning electron microscopy and atomic force microscopy showed the root-mean squares hardness of the β-Tcp/Ch coatings decreased by further increasing chitosan percentage. The elastic-plastic characteristics of the coatings were determined by conducting nano indentation test, indicating that the increase if chitosan percentage is directly related to increasing the hardness and elastic modulus of the β-Tcp/Ch coatings. Tribological characterization was performed by scratch test and pin-on-disk test to analyze the changes in the surface wear the β-Tcp/Ch coatings. Finally, the results indicated an improvement in the mechanical and tribological properties of the β-Tcp/Ch coatings as a function of increasing of the chitosan percentage. (Author)

  10. Biological Evaluation of α-TCP/TTCP Composite Bone Cement

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    α-tricalcium phosphate(α-TCP)/tetracalcium phosphate(TTCP) composite bone cement had good hydration characteristic.In our system,α-TCP/TTCP powder mixture was mixed with water at a powder/liquid (P/L) ratio of 1.50g*mL-1.The setting time could be adjusted,the maximum compressive strength was 45.36MPa,and the hydration product was hydroxyapatite (HAP).In vitro biological simulated experiments indicate that α-TCP/TTCP bone cement has α certain dissolubility.The hardened product is mainly HAP after soaking in simulated body fluid (SBF) for 10 weeks.The results of in vitro test and animal experiments and SEM analyses show that no local or general toxicity response,no muscle stimulation,no haemolysis,no cruor,no inflammatory reaction and no exclusion response are caused by α-TCP/TTCP cement, which can be contributed to bone tissue spreading and impinging.α-TCP/TTCP cement hydrated and hardened continually in vivo.The materials fused with host bone together with implanting time prolonging.Therefore,it is believed that α-TCP/TTCP composite bone cement has a high biocompatibility and bioactivity,a certain biodegradation and good osteogenesis as well.

  11. TCP/IP协议脆弱性分析%The Analysis of the Fragility of the TCP/IP Protocol

    Institute of Scientific and Technical Information of China (English)

    陆余良; 李永祥; 孙乐昌; 朱俊茂

    2001-01-01

    @@ 一、概述 传输控制协议/互联网协议(以下简称TCP/IP)最初是为美国的ARPANET设计的,其目的在于能使各种各样的计算机都能在一个共同的网络环境中运行.经过二十多年的研究与发展,已充分显示出TCP/IP协议具有强大的连网能力.目前已形成了用TCP/IP协议连接世界各国、各部门、各机构计算机网络的数据通信网Internet,TCP/IP协议已成为事实上的国际标准和工业标准.

  12. Effects of added ZnTCP on mechanical and biological properties of apatite cement

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, K.; Suzuki, K. [Okayama Univ. Dental School (Japan). Dept. of Biomaterials; Miyamoto, Y.; Toh, T.; Yuasa, T.; Nagayama, M. [Tokushima Univ. (Japan). First Dept. of Oral and Maxillofacial Surgery; Ito, A. [National Inst. for Advanced Interdisciplinary Research, MITT, Ibaragi (Japan)

    2001-07-01

    Effects of added Zn doped {beta}-tricalcium phosphate (ZnTCP) on mechanical and biological properties of apatite cement (AC) was studied. Powder X-ray diffractometer revealed that ZnTCP shows no reactivity with AC. The mechanical strength of AC decreased increasing amounts of added ZnTCP. We observed no effect on the setting time of AC when the amount of ZnTCP was 10% or less. Proliferation of the osteoblastic cells was significantly increased on the surface of AC containing 5% ZnTCP when compared with that containing no ZnTCP. In contrast, proliferation of the cells decreased on the surface of AC containing 10% ZnTCP when compared with that free from ZnTCP; indicating cytotoxity. We concluded therefore, that addition of ZnTCP to AC might be useful to enhance the osteoconductivity of AC when release of Zn{sup 2+} can be carefully regulated. (orig.)

  13. A Survey of TCP Reno, New Reno and Sack Over Mobile Ad-Hoc Network

    CERN Document Server

    Khan, Md Nazmul Islam; Aziz, Md Tariq

    2012-01-01

    Transmission Control Protocol (TCP) is often preferred to be implemented at the transport layer of a Mobile Ad-hoc Network (MANET) because of its wide range of applications, which enjoys the advantage of reliable data transmission in the Internet. However, because of some unique characteristics of MANET, TCP cannot offer reliable services while using e-mail, internet search and file transmission in such a network. The research investigates how well the different versions of TCP respond to various performance differentials when subjected to different network stresses and topology changes, aside from identifying the most efficient and robust TCP version(s) for different MANET scenarios. Among several TCP variants, three types are considered important for the analysis, namely TCP Reno, TCP New Reno and TCP Selective Acknowledgment (SACK). In most cases, the TCP performance is found in our study to decrease when the node size and mobility rate is increased in the network. There is, however, exception to this. As ...

  14. Experimental Evaluation of TCP and ICMP in Network Measurement

    Institute of Scientific and Technical Information of China (English)

    LI Wen-wei; ZHANG Da-fang; XIE Gao-gang; YANG Jin-ming

    2005-01-01

    Network measurement is an important approach to understand network behaviors, which has been widely studied. Both Transfer Control Protocol (TCP) and Internet Control Messages Protocol (ICMP) are applied in network measurement, while investigating the differences between the measured results of these two protocols is an important topic that has been less investigated. In this paper, to compare the differences between TCP and ICMP when they are used in measuring host connectivity, RTT, and packet loss rate, two groups of comparison programs have been designed, and after careful evaluation of the program parameters, a lot of comparison experiments are executed on the Internet. The experimental results show that, there are significant differences between the host connectivity measured using TCP or ICMP; in general, the accuracy of connectivity measured using TCP is 20%- 30% higher than that measured using ICMP. The case of RTT and packet loss rate is complicated, which are related to path loads and destination host loads. While commonly, the RTT and packet loss rate measured using TCP or ICMP are very close. According to the experimental results, some advices are also given on protocol selection for conducting accurate connectivity, RTT and packet loss rate measurements.

  15. A Novel Congestion Detection Scheme in TCP Over OBS Networks

    KAUST Repository

    Shihada, Basem

    2009-02-01

    This paper introduces a novel congestion detection scheme for high-bandwidth TCP flows over optical burst switching (OBS) networks, called statistical additive increase multiplicative decrease (SAIMD). SAIMD maintains and analyzes a number of previous round-trip time (RTTs) at the TCP senders in order to identify the confidence with which a packet loss event is due to network congestion. The confidence is derived by positioning short-term RTT in the spectrum of long-term historical RTTs. The derived confidence corresponding to the packet loss is then taken in the developed policy for TCP congestion window adjustment. We will show through extensive simulation that the proposed scheme can effectively solve the false congestion detection problem and significantly outperform the conventional TCP counterparts without losing fairness. The advantages gained in our scheme are at the expense of introducing more overhead in the SAIMD TCP senders. Based on the proposed congestion control algorithm, a throughput model is formulated, and is further verified by simulation results.

  16. El alba-tcp mirado con buenos ojos

    Directory of Open Access Journals (Sweden)

    Christopher David Absell

    2012-01-01

    Full Text Available El surgimiento de la Alianza Bolivariana para los Pueblos de Nuestra América-Tratado de Comercio de los Pueblos (alba-tcp representa una novedad de importancia regional e internacional; sin embargo hasta la fecha el trabajo académico sobre la organización ha sido escaso y se ha caracterizado por tener un enfoque metodológico descriptivo carente de investigación empírica comprensiva. En este artículo sostengo que este enfoque metodológico ha imbuido la literatura de un sesgo positivo a favor del alba-tcp y sus proyectos de desarrollo. El objetivo de este artículo es examinar esta literatura para determinar una agenda de investigación para el estudio del alba-tcp.

  17. A simulation study of TCP performance in ATM networks

    Energy Technology Data Exchange (ETDEWEB)

    Chien Fang; Chen, Helen; Hutchins, J.

    1994-08-01

    This paper presents a simulation study of TCP performance over congested ATM local area networks. We simulated a variety of schemes for congestion control for ATM LANs, including a simple cell-drop, a credit-based flow control scheme that back-pressures individual VC`s, and two selective cell-drop schemes. Our simulation results for congested ATM LANs show the following: (1) TCP performance is poor under simple cell-drop, (2) the selective cell-drop schemes increase effective link utilization and result in higher TCP throughputs than the simple cell-drop scheme, and (3) the credit-based flow control scheme eliminates cell loss and achieves maximum performance and effective link utilization.

  18. TCP/IP协议与端口号应用

    Institute of Scientific and Technical Information of China (English)

    倪显利

    2003-01-01

    @@ TCP/IP(Transmission Control Protocol/Internet Protocol,传输控制协议/网际协议)协议产生于1975年,1983年1月1日成为因特网的标准协议,并已融入Windows、UMX、Linux等操作系统,源自美国国防部的高级研究计划署网(ARPANET,Advanced Research Propject Agency Network)的套接字(Socket API)是在TCP/IP网络环境下进行通信的重要工具.

  19. Analogues between tuning TCP for Data Acquisition and Datacenter Networks

    CERN Document Server

    Jereczek, G; Malone, D

    2015-01-01

    A many-to-one communication pattern is present both in Data Acquisition (DAQ) and datacenter networks. The problem arising from this pattern is widely known in the literature as incast and can be observed as TCP throughput collapse. It is a result of overloading the switch buffers, when a specific node in a network requests data from multiple sources. This paper provides two contributions. First, we confirm that there are strong analogies between the TCP behavior in DAQ and datacenter networks. Second, we evaluate different proposals from datacenter for application in DAQ to improve performance and reduce buffer requirements.

  20. Improving Network Performance by Ameliorating TCP Congestion Control Mechanism

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With the rapid growth of rate-based services and wireless applications,improving Transmission Control Protocol (TCP) congestion control has been becoming more important in the network research field. This paper first briefly introduces the Additive-Increase Multiplicative-Decrease (AIMD) (a,b) algorithm,and then presents an improved TCP congestion control mechanism (D-AIMD) whose principles and simulation results are discussed in detail. This mechanism can be easily implemented with lower additional overheads and can efficiently improve network performance.

  1. BIFURCATIONS AND CHAOS CONTROL IN TCP-RED SYSTEM

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Internet is heterogeneous in nature,and ex-tremely wide variations in parametric perturbationlead to a very rich world of dynamical behaviorsranging from s mooth,stable operation to rathercomplicated irregular patterns.In[1],the occur-rence of chaotic behavior in TCP has been reportedfor the first ti me.Since the seminal work of Mathisand Floyd[2-3],there have been increasing interestsin the dynamical characteristics of Internet.In theprevious work,TCP congestion control algorithmplus RED queue management m...

  2. TCP-Call Admission Control Interaction in Multiplatform Space Architectures

    Directory of Open Access Journals (Sweden)

    Georgios Theodoridis

    2007-06-01

    Full Text Available The implementation of efficient call admission control (CAC algorithms is useful to prevent congestion and guarantee target quality of service (QoS. When TCP protocol is adopted, some inefficiencies can arise due to the peculiar evolution of the congestion window. The development of cross-layer techniques can greatly help to improve efficiency and flexibility for wireless networks. In this frame, the present paper addresses the introduction of TCP feedback into the CAC procedures in different nonterrestrial wireless architectures. CAC performance improvement is shown for different space-based architectures, including both satellites and high altitude platform (HAP systems.

  3. Chiba Tendril-Less locus determines tendril organ identity in melon (Cucumis melo L.) and potentially encodes a tendril-specific TCP homolog.

    Science.gov (United States)

    Mizuno, Shinji; Sonoda, Masatoshi; Tamura, Yayoi; Nishino, Eisho; Suzuki, Hideyuki; Sato, Takahide; Oizumi, Toshikatsu

    2015-11-01

    Tendrils are filamentous plant organs that coil on contact with an object, thereby providing mechanical support for climbing to reach more sunlight. Plant tendrils are considered to be modified structure of leaves, stems, or inflorescence, but the origin of cucurbit tendrils is still argued because of the complexity in the axillary organ patterning. We carried out morphological and genetic analyses of the Chiba Tendril-Less (ctl) melon (Cucumis melo) mutant, and found strong evidence that the melon tendril is a modified organ derived from a stem-leaf complex of a lateral shoot. Heterozygous (CTL/ctl) plants showed traits intermediate between tendril and shoot, and ontogenies of wild-type tendrils and mutant modified shoots coincided. We identified the CTL locus in a 200-kb region in melon linkage group IX. A single base deletion in a melon TCP transcription factor gene (CmTCP1) was detected in the mutant ctl sequence, and the expression of CmTCP1 was specifically high in wild-type tendrils. Phylogenetic analysis demonstrated the novelty of the CmTCP1 protein and the unique molecular evolution of its orthologs in the Cucurbitaceae. Our results move us closer to answering the long-standing question of which organ was modified to become the cucurbit tendril, and suggest a novel function of the TCP transcription factor in plant development.

  4. Histological and Histomorphometric Human Results of HA-Beta-TCP 30/70 Compared to Three Different Biomaterials in Maxillary Sinus Augmentation at 6 Months: A Preliminary Report

    Directory of Open Access Journals (Sweden)

    Susanna Annibali

    2015-01-01

    Full Text Available Objective. The aim of this investigation was to examine the bone regenerative potential of newly biphasic calcium phosphate ceramics (HA-β-TCP 30/70, by assessing histological and histomorphometric results of human specimens retrieved from sinuses augmented with HA-β-TCP 30/70, and comparing them to anorganic bovine bone (ABB, mineralized solvent-dehydrated bone allograft (MSDBA, and equine bone (EB, after a healing period of 6 months. Materials and Methods. Four consecutive patients with edentulous atrophic posterior maxilla were included in this report. A two-stage procedure was carried out for sinus augmentation with HA-β-TCP 30/70, ABB, MSDBA, and EB. After 6 months, specimens were retrieved at the time of implant placement and processed for histological and histomorphometric analyses. Results. At histological examination, all biomaterials were in close contact with the newly formed bone and showed the same pattern of bone formation; the grafted granules were surrounded by a bridge-like network of newly formed bone. A limited number of ABB particles were partially covered by connective tissue. The histomorphometric analysis revealed 30.2% newly formed bone for Ha-β-TCP 30/70, 20.1% for ABB, 16.4% for MSDBA, and 21.9% for EB. Conclusions. Within the limitations of the present investigation, these results support the successful use of HA-β-TCP 30/70 for sinus augmentation.

  5. Cloning, expression and alternative splicing of the novel isoform of hTCP11 gene

    DEFF Research Database (Denmark)

    Ma, Yong-xin; Zhang, Si-zhong; Wu, Qia-qing;

    2003-01-01

    To identify a novel isoform of hTCP11 gene and investigate its expression and alternative splicing.......To identify a novel isoform of hTCP11 gene and investigate its expression and alternative splicing....

  6. Analysis of Network Model OSI and TCP / IP%OSI与TCP/IP网络模型分析

    Institute of Scientific and Technical Information of China (English)

    王田

    2013-01-01

    针对OSI与TCP/IP网络参考模型构成,对OSI与TCP/IP网络参考模型各层进行拆解分析和研究.通过对两种网络模型的分析研究,能更准确的认识与理解网络的结构化构成,有益于日后相关网络相关组件的深入研发工作.

  7. TCP-HY: Improving TCP Performance in Hybrid IP Network%TCP-HY:优化TCP在混合IP网络环境中的效率

    Institute of Scientific and Technical Information of China (English)

    徐航宇; 罗键

    2007-01-01

    在混合网络环境下,由于数据包传输的非时序性以及在传输过程中相对较高的误码率,TCP的传输效率极大地被降低了.对此,提出了一种新的TCP改进版本:TCP-HY,它能够有效解决数据包延迟以及高误码率的问题.试验表明,TCP-HY在混合网络环境中能够大大提高TCP的效率,充分利用有效带宽,是一种优秀的解决方案.

  8. Analyzing and evaluating the three-line rail traffic

    Institute of Scientific and Technical Information of China (English)

    GAO ZiYou; ZHOU HuaLiang; LI KePing; NING Bing; TANG Tao

    2008-01-01

    In this paper,we propose a method to simulate the three-line rail traffic.The aim is to evaluate the carrying capacity of the three-line rail traffic by studying the rail traffic flow when the passenger flow is unsymmetrical.The simulation results demonstrate that under the unsymmetrical condition,the three-line rail traffic sys-tem has almost the same carrying capacity as that of a four-line rail traffic system.Compared with the four-line rail traffic system,the three-line rail traffic system has better utilization of rail line.As a result,building the three-line rail traffic system is a more economical and rational selection.

  9. Analyzing and evaluating the three-line rail traffic

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, we propose a method to simulate the three-line rail traffic. The aim is to evaluate the carrying capacity of the three-line rail traffic by studying the rail traffic flow when the passenger flow is unsymmetrical. The simulation results demonstrate that under the unsymmetrical condition, the three-line rail traffic system has almost the same carrying capacity as that of a four-line rail traffic system. Compared with the four-line rail traffic system, the three-line rail traffic system has better utilization of rail line. As a result, building the three-line rail traffic system is a more economical and rational selection.

  10. File list: Oth.ALL.10.TCP1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.10.TCP1.AllCell hg19 TFs and others TCP1 All cell types SRX663251,SRX019786...38,SRX277135,SRX018991,SRX105187,SRX099055,SRX105186,SRX514839,SRX514838,SRX099053 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.ALL.10.TCP1.AllCell.bed ...

  11. File list: Oth.Epd.50.TCP1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Epd.50.TCP1.AllCell hg19 TFs and others TCP1 Epidermis SRX663250,SRX663252,SRX6...X514838,SRX099053,SRX099055,SRX514844 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Epd.50.TCP1.AllCell.bed ...

  12. File list: Oth.ALL.05.TCP1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.05.TCP1.AllCell hg19 TFs and others TCP1 All cell types SRX663251,SRX663249...44,SRX663252,SRX105186,SRX514838,SRX018991,SRX277138,SRX105187,SRX277132,SRX099055 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.ALL.05.TCP1.AllCell.bed ...

  13. File list: Oth.Epd.05.TCP1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Epd.05.TCP1.AllCell hg19 TFs and others TCP1 Epidermis SRX663251,SRX663249,SRX6...X514838,SRX018991,SRX105187,SRX099055 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Epd.05.TCP1.AllCell.bed ...

  14. File list: Oth.ALL.20.TCP1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.20.TCP1.AllCell hg19 TFs and others TCP1 All cell types SRX019786,SRX663250...39,SRX514843,SRX018991,SRX277132,SRX212375,SRX514838,SRX099053,SRX099055,SRX514844 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.ALL.20.TCP1.AllCell.bed ...

  15. File list: Oth.ALL.50.TCP1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.50.TCP1.AllCell hg19 TFs and others TCP1 All cell types SRX663250,SRX663252...43,SRX018992,SRX212375,SRX514838,SRX277135,SRX277132,SRX099053,SRX099055,SRX514844 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.ALL.50.TCP1.AllCell.bed ...

  16. File list: Oth.Epd.20.TCP1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Epd.20.TCP1.AllCell hg19 TFs and others TCP1 Epidermis SRX019786,SRX663250,SRX6...X514838,SRX099053,SRX099055,SRX514844 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Epd.20.TCP1.AllCell.bed ...

  17. File list: Oth.Epd.10.TCP1.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Epd.10.TCP1.AllCell hg19 TFs and others TCP1 Epidermis SRX663251,SRX019786,SRX5...X105186,SRX514839,SRX514838,SRX099053 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/assembled/Oth.Epd.10.TCP1.AllCell.bed ...

  18. A Survey Of Tcp Reno, New Reno And Sack Over Mobile Ad-Hoc Network

    Directory of Open Access Journals (Sweden)

    Md Nazmul Islam Khan

    2012-02-01

    Full Text Available Transmission Control Protocol (TCP is often preferred to be implemented at the transport layer of a Mobile Ad-hoc Network (MANET because of its wide range of applications, which enjoys the advantage of reliable data transmission in the Internet. However, because of some unique characteristics of MANET, TCP cannot offer reliable services while using e-mail, internet search and file transmission insuch a network. The research investigates how well the different versions of TCP respond to various performance differentials when subjected to different network stresses and topology changes, aside from identifying the most efficient and robust TCP version(s for different MANET scenarios. Among several TCP variants, three types are considered important for the analysis, namely TCP Reno, TCP New Reno and TCP Selective Acknowledgment (SACK. In most cases, the TCP performance is found in our study to decrease when the node size and mobility rate is increased in the network. There is, however, exception to this. As our simulation results demonstrate, the increases in the node velocity sometimes help the TCP to attain a better performance. The study also reveals that out of the three variants, TCP SACK can adaptrelatively well to the changing network sizes while TCP Reno performs most robustly in the presence ofdifferent mobility rates within MANET.

  19. Traffic Dynamics of Computer Networks

    Science.gov (United States)

    Fekete, Attila

    2008-10-01

    Two important aspects of the Internet, namely the properties of its topology and the characteristics of its data traffic, have attracted growing attention of the physics community. My thesis has considered problems of both aspects. First I studied the stochastic behavior of TCP, the primary algorithm governing traffic in the current Internet, in an elementary network scenario consisting of a standalone infinite-sized buffer and an access link. The effect of the fast recovery and fast retransmission (FR/FR) algorithms is also considered. I showed that my model can be extended further to involve the effect of link propagation delay, characteristic of WAN. I continued my thesis with the investigation of finite-sized semi-bottleneck buffers, where packets can be dropped not only at the link, but also at the buffer. I demonstrated that the behavior of the system depends only on a certain combination of the parameters. Moreover, an analytic formula was derived that gives the ratio of packet loss rate at the buffer to the total packet loss rate. This formula makes it possible to treat buffer-losses as if they were link-losses. Finally, I studied computer networks from a structural perspective. I demonstrated through fluid simulations that the distribution of resources, specifically the link bandwidth, has a serious impact on the global performance of the network. Then I analyzed the distribution of edge betweenness in a growing scale-free tree under the condition that a local property, the in-degree of the "younger" node of an arbitrary edge, is known in order to find an optimum distribution of link capacity. The derived formula is exact even for finite-sized networks. I also calculated the conditional expectation of edge betweenness, rescaled for infinite networks.

  20. OPTIMIZATION OF URBAN MULTI-INTERSECTION TRAFFIC FLOW VIA Q-LEARNING

    OpenAIRE

    Yit Kwong Chin; Heng Jin Tham; N.S.V. Kameswara Rao; Nurmin Bolong; Kenneth Tze Kin Teo

    2013-01-01

    Congestions of the traffic flow within the urban traffic network have been a challenging task for all the urban developers. Many approaches have been introduced into the current system to solve the traffic congestion problems. Reconfiguration of the traffic signal timing plan has been carried out through implementation of different techniques. However, dynamic characteristics of the traffic flow increase the difficulties towards the ultimate solutions. Thus, traffic congestions still remain a...

  1. Jamitons: Phantom Traffic Jams

    Science.gov (United States)

    Kowszun, Jorj

    2013-01-01

    Traffic on motorways can slow down for no apparent reason. Sudden changes in speed by one or two drivers can create a chain reaction that causes a traffic jam for the vehicles that are following. This kind of phantom traffic jam is called a "jamiton" and the article discusses some of the ways in which traffic engineers produce…

  2. Ohio Marketing Management and Research. Technical Competency Profile (TCP).

    Science.gov (United States)

    Ray, Gayl M.; Wilson, Nick; Mangini, Rick

    This document provides a framework for a broad-based secondary and postsecondary curriculum to prepare students for employment in marketing management and research (MMR). The first part of the technical competency profile (TCP) contains the following items: an explanation of the purpose and scope of Ohio's TCPs; college tech prep program…

  3. TCP-IP Model in Data Communication and Networking

    Directory of Open Access Journals (Sweden)

    Pranab Bandhu Nath

    2015-10-01

    Full Text Available The Internet protocol suite is the computer networking model and set of communications protocols used on the Internet and similar computer networks. It is commonly known as TCP/IP, because it’s most important protocols, the Transmission Control Protocol (TCP and the Internet Protocol (IP, were the first networking protocols defined in this standard. Often also called the Internet model, it was originally also known as the DoD model, because the development of the networking model was funded by DARPA, an agency of the United States Department of Defense. TCP/IP provides end-to-end connectivity specifying how data should be packetized, addressed, transmitted, routed and received at the destination. This functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope of networking involved. From lowest to highest, the layers are the link layer, containing communication technologies for a single network segment (link; the internet layer, connecting hosts across independent networks, thus establishing internetworking; the transport layer handling host-to-host communication; and the application layer, which provides process-to-process application data exchange. Our aim is describe operation & models of TCP-IP suite in data communication networking

  4. Ohio Medical Office Management. Technical Competency Profile (TCP).

    Science.gov (United States)

    Ray, Gayl M.; Wilson, Nick; Mangini, Rick

    This document provides a framework for a broad-based secondary and postsecondary curriculum to prepare students for employment in medical office management. The first part of the technical competency profile (TCP) contains the following items: an explanation of the purpose and scope of Ohio's TCPs; college tech prep program standards; an overview…

  5. Construction of a nuclear data server using TCP/IP

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Toshihiko; Sakai, Osamu [Kyushu Univ., Fukuoka (Japan)

    1997-03-01

    We construct a nuclear data server which provides data in the evaluated nuclear data library through the network by means of TCP/IP. The client is not necessarily a user but a computer program. Two examples with a prototype server program are demonstrated, the first is data transfer from the server to a user, and the second is to a computer program. (author)

  6. Simulation of traffic flow at a signalised intersection

    OpenAIRE

    Foulaadvand, M. Ebrahim; Belbaasi, Sommayeh

    2008-01-01

    We have developed a Nagel-Schreckenberg cellular automata model for describing of vehicular traffic flow at a single intersection. A set of traffic lights operating either in fixed-time or traffic adaptive scheme controls the traffic flow. Closed boundary condition is applied to the streets each of which conduct a uni-directional flow. Extensive Monte Carlo simulations are carried out to find the model characteristics. In particular, we investigate the dependence of the flows on the signalisa...

  7. An Investigation into Traffic Turning Movement at Jibowu

    OpenAIRE

    S. I. Oni; S.A. Oke

    2008-01-01

    This paper aims at understanding the behavioral pattern of traffic at Jibowu intersection with a view of using the results obtained as a model for understudying traffic movement at similar intersections in the Lagos metropolis. Consequently, an evaluation of the sampled intersections was carried out by employing a physical measurement of the layout, traffic volume at each turning point, and evaluating it against the back drop of traffic delays at the intersections. The paper reviews the traff...

  8. TRANSIMS traffic flow characteristics

    OpenAIRE

    Nagel, Kai; Stretz, Paula; Pieck, Martin; Donnelly, Rick; Barrett, Christopher L.

    1997-01-01

    Knowledge of fundamental traffic flow characteristics of traffic simulation models is an essential requirement when using these models for the planning, design, and operation of transportation systems. In this paper we discuss the following: a description of how features relevant to traffic flow are currently under implementation in the TRANSIMS microsimulation, a proposition for standardized traffic flow tests for traffic simulation models, and the results of these tests for two different ve...

  9. 未来高带宽网络中FAST TCP与TCP Vegas的公平性分析%Fairness analysis of FAST TCP and TCP Vegas over future high-bandwidth internet

    Institute of Scientific and Technical Information of China (English)

    朱小松

    2012-01-01

    FAST TCP, a modern end-to-end protocol adopting queuing delay as a congestion measure. However, the lack of a precise measurement of queuing delay leads to a potential unfairness problem that FAST TCP flows may be discriminated against according to their starting times in a persistent congestion scenario, TCP Vegas also encounters the unfairness problem. The unfairness problem is quantitatively assessed by mathematical analysis and ns2 simulations, then, we compared FAST TCP with TCP Vegas. Consequently, FAST TCP demonstrates a competitive edge over TCP Vegas, under future high bandwidth-delay product environment. This conclusion will contribute to the improvement of FAST TCP for future reference.%FAST TCP是先进的端到端拥塞控制协议,采用队列时延作为拥塞度量.由于不能准确测得精确的队列时延,此协议中存有不公平的隐患,即在某些持续拥塞场景下,不同时刻启动的FAST TCP流会受到差别对待,TCP Vegas中同样存在不公平问题.通过数学分析和ns2仿真对这种不公平问题进行量化,进而比较FASTTCP与TCP Vegas在公平性问题上的性能差异.结果证明了在将来高带宽时延乘积网络环境下,FAST TCP在公平性上要明显优于TCP Vegas.这为对FAST TCP协议的改进给出了有价值的参照.

  10. Effects of β-TCP Ceramics on Ostcoblast Cellular Proliferating, Mineralization and Osteocalcin Expression

    Institute of Scientific and Technical Information of China (English)

    QI Zhitao; ZHANG Qihuan; ZHENG Qiang; DAI Honglian; WANG Zisheng; QIU Ming; LI Shipu

    2012-01-01

    After co-cultrured osteoblast with β-TCP ceramics,the cellular proliferating,mineralization and osteocalcin expression were studied.MTT assay showed that β-TCP ceramics had no affect on cellular proliferating.Laser scanning confocal detection showed that β-TCP ceramics could increase the mineralization level of osteoblast.Furthermore,RT-PCR showed that β-TCP could increase the expression level of osteocalcin.Those results indicate β-TCP ceramics had perfect biocompatibility and increased the mineralization of osteoblast to accelerate osteogenesis by means of affecting the expression of genes involving in osteogeneticprocess.

  11. A New Analytical Model for TCP Reno with Bursts Error Considered

    Institute of Scientific and Technical Information of China (English)

    DENG Jian-min; JI Hong; YUE Guang-xin; YIN Chang-chuan

    2003-01-01

    In this paper, we present a new analytical model for TCP Reno, and this method can also be used in other versions of TCP. The first order two-state Markovian model is used to describe the wireless link, so as to deal with the burst error in wireless links very well. The tineout mechanism of TCP is also considered and a geometric method describes the erponential growth of TCP timeout . Also this method is effective for the study of the growth of TCP transmission window. Analytical results indicate that this model is effective.

  12. Investigation of TCP Veno Performance over Wirless Ad Hoc Network%TCP Veno在无线Ad Hoc网络中的性能分析

    Institute of Scientific and Technical Information of China (English)

    唐述; 谢显中; 赵锐

    2007-01-01

    分析了TCP Veno在无线Ad Hoc这样的多跳的网络中的性能,并分SANET(静态无线多跳网络)和MANET(移动无线多跳网络)两种网络环境进行仿真分析,结果显示TCP Veno的性能较TCP Reno有一定程度的改进,但并没有在无线单跳网络中的性能优势出色,这对实际应用TCP Veno很重要.

  13. 使用Sniffer软件透视TCP/IP协议的安全%To Analyze the Security of TCP/IP Protocol Using Sniffer Software

    Institute of Scientific and Technical Information of China (English)

    张保江

    2014-01-01

    TCP/IP协议是当前计算机局域网和Internet普遍使用的组网协议,该文结合TCP/IP的一个通信实例,使用Sniffer软件,截取并分析其通信数据,得出TCP/IP协议缺乏相应的安全机制的结论,并在此基础上,讨论了基于TCP/IP协议的有关安全的常用做法。%TCP/IP is the protocol that commonly used to build the Ethernet or Internet. Based on an instance of TCP/IP com-munication, the thesis uses the sniffer software to capture and analyze the data of TCP/IP communications and draws the conclu-sion that TCP/IP protocol has no measures to ensure the security of the communications. At last the thesis introduces some ways to ensure the security of TCP/IP communications.

  14. VB客户——服务器(TCP/IP)编程%Using VB Design Client-Server(TCP/IP) Network Program

    Institute of Scientific and Technical Information of China (English)

    陶运道

    2002-01-01

    利用VB的 WinSock 控件可以与远程计算机建立连接,并通过用户数据文报协议(UDP)或者传输控制协议(TCP)进行数据交换.TCP/IP协议是Internet最重要的协议.VB提供了WinSock控件,用于在TCP/IP的基础上进行网络通信.本文介绍如何用VB来实现TCP/IP网络编程.

  15. TCP10L acts as a tumor suppressor by inhibiting cell proliferation in hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Jie; Cai, Hao; Wu, Yanhua; Ma, Haijie; Jiang, Wei; Liu, Chao; Han, Dingding; Ji, Guoqing [State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433 (China); Yu, Long, E-mail: longyu@fudan.edu.cn [State Key Laboratory of Genetic Engineering, Institute of Genetics, Fudan University, Shanghai 200433 (China); Institutes of Biomedical Sciences, Fudan University, Shanghai 200032 (China)

    2014-03-28

    Highlights: • TCP10L was down-regulated in clinical hepatocellular carcinoma (HCC). • Expression of TCP10L correlated significantly with tumor size and Milan criteria. • Overexpression of TCP10L attenuated growth of HCC cells both in vitro and in vivo. • Knocking down TCP10L promoted cell proliferation and tumorigenesis of HCC cells. - Abstract: TCP10L (T-complex 10 (mouse)-like) has been identified as a liver and testis-specific gene. Although a potential transcriptional suppression function of TCP10L has been reported previously, biological function of this gene still remains largely elusive. In this study, we reported for the first time that TCP10L was significantly down-regulated in clinical hepatocellular carcinoma (HCC) samples when compared to the corresponding non-tumorous liver tissues. Furthermore, TCP10L expression was highly correlated with advanced cases exceeding the Milan criteria. Overexpression of TCP10L in HCC cells suppressed colony formation, inhibited cell cycle progression through G0/G1 phase, and attenuated cell growth in vivo. Consistently, silencing of TCP10L promoted cell cycle progression and cell growth. Therefore, our study has revealed a novel suppressor role of TCP10L in HCC, by inhibiting proliferation of HCC cells, which may facilitate the diagnosis and molecular therapy in HCC.

  16. 10 Gbps TCP/IP streams from the FPGA for High Energy Physics

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Gerry; et al.

    2014-01-01

    The DAQ system of the CMS experiment at CERN collects data from more than 600 custom detector Front-End Drivers (FEDs). During 2013 and 2014 the CMS DAQ system will undergo a major upgrade to address the obsolescence of current hardware and the requirements posed by the upgrade of the LHC accelerator and various detector components. For a loss-less data collection from the FEDs a new FPGA based card implementing the TCP/IP protocol suite over 10Gbps Ethernet has been developed. To limit the TCP hardware implementation complexity the DAQ group developed a simplified and unidirectional but RFC 793 compliant version of the TCP protocol. This allows to use a PC with the standard Linux TCP/IP stack as a receiver. We present the challenges and protocol modifications made to TCP in order to simplify its FPGA implementation. We also describe the interaction between the simplified TCP and Linux TCP/IP stack including the performance measurements.

  17. TCP Veno在无线AdHoc网络中的性能比较研究

    Institute of Scientific and Technical Information of China (English)

    唐述; 谢显中; 赵锐

    2007-01-01

    TCP Veno是一种新的无线网络环境下TCP的拥塞控制机制,它综合了TCP Reno和TCP Vegas的特点,对单跳无线网络的性能有了较大的改善。对TCP Veno应用于无线多跳网络中的性能进行研究,将TCP Veno在三种不同的无线AdHoc路由协议下的性能进行了仿真分析和比较,结果显示TCP Veno在不同的路由协议下的性能有所不同,通过比较,可以找到一个在无线AdHoc网络中更适合TCP Veno的路由协议。

  18. 10 Gbps TCP/IP streams from the FPGA for High Energy Physics

    Science.gov (United States)

    Bauer, Gerry; Bawej, Tomasz; Behrens, Ulf; Branson, James; Chaze, Olivier; Cittolin, Sergio; Coarasa, Jose Antonio; Darlea, Georgiana-Lavinia; Deldicque, Christian; Dobson, Marc; Dupont, Aymeric; Erhan, Samim; Gigi, Dominique; Glege, Frank; Gomez-Ceballos, Guillelmo; Gomez-Reino, Robert; Hartl, Christian; Hegeman, Jeroen; Holzner, Andre; Masetti, Lorenzo; Meijers, Frans; Meschi, Emilio; Mommsen, Remigius K.; Morovic, Srecko; Nunez-Barranco-Fernandez, Carlos; O'Dell, Vivian; Orsini, Luciano; Ozga, Wojciech; Paus, Christoph; Petrucci, Andrea; Pieri, Marco; Racz, Attila; Raginel, Olivier; Sakulin, Hannes; Sani, Matteo; Schwick, Christoph; Cristian Spataru, Andrei; Stieger, Benjamin; Sumorok, Konstanty; Veverka, Jan; Wakefield, Christopher Colin; Zejdl, Petr

    2014-06-01

    The DAQ system of the CMS experiment at CERN collects data from more than 600 custom detector Front-End Drivers (FEDs). During 2013 and 2014 the CMS DAQ system will undergo a major upgrade to address the obsolescence of current hardware and the requirements posed by the upgrade of the LHC accelerator and various detector components. For a loss-less data collection from the FEDs a new FPGA based card implementing the TCP/IP protocol suite over 10Gbps Ethernet has been developed. To limit the TCP hardware implementation complexity the DAQ group developed a simplified and unidirectional but RFC 793 compliant version of the TCP protocol. This allows to use a PC with the standard Linux TCP/IP stack as a receiver. We present the challenges and protocol modifications made to TCP in order to simplify its FPGA implementation. We also describe the interaction between the simplified TCP and Linux TCP/IP stack including the performance measurements.

  19. A Marine Traffic Flow Model

    OpenAIRE

    Tsz Leung Yip

    2013-01-01

    A model is developed for studying marine traffic flow through classical traffic flow theories, which can provide us with a better understanding of the phenomenon of traffic flow of ships. On one hand, marine traffic has its special features and is fundamentally different from highway, air and pedestrian traffic. The existing traffic models cannot be simply extended to marine traffic without addressing marine traffic features. On the other hand, existing literature on marine traffic focuses on...

  20. SELF-SIMILAR TRAFFIC GENERATOR

    OpenAIRE

    Linawati Linawati; I Made Suartika

    2009-01-01

    Network traffic generator can be produced using OPNET. OPNET generates the traffic as explicit traffic or background traffic. This paper demonstrates generating traffic in OPNET 7.0 as background traffic. The traffi generator that was simulated is self-similar traffic with different Hurst parameter. The simulation results proved that OPNET with background traffic function can be as a qualified self-similar traffic generator. These results can help in investigating and analysing network perfor...

  1. Performance Evaluation of AODV and DSR with Varying Pause Time and Speed Time Over TCP and CBR Connections in VANET

    Directory of Open Access Journals (Sweden)

    Bijan Paul

    2012-01-01

    Full Text Available VANET (Vehicular Ad-hoc Network is a new technology which has taken enormous attention in the recent years. Vehicular ad hoc network is formed by cars which are called nodes; allow them to communicate with one another without using any fixed road side unit. It has some unique characteristics which make it different from other ad-hoc network as well as difficult to define any exact mobility model and routing protocols because of their high mobility and changing mobility pattern. Hence performance of routing protocols can vary with the various parameters such as speed, pause time, node density and traffic scenarios. In this research paper, the performance of two on-demand routing protocols AODV and DSR has been analyzed by means of packet delivery ratio, loss packet ratio average end-to-end delay with varying pause time, speed time and node density under TCP and CBR connection.

  2. Performance Evaluation of AODV & DSR with Varying Pause Time & Speed Time Over TCP & CBR Connections in VANET

    CERN Document Server

    Paul, Bijan; Bikas, Md Abu Naser

    2012-01-01

    VANET (Vehicular Ad-hoc Network) is a new technology which has taken enormous attention in the recent years. Vehicular ad hoc network is formed by cars which are called nodes; allow them to communicate with one another without using any fixed road side unit. It has some unique characteristics which make it different from other ad hoc network as well as difficult to define any exact mobility model and routing protocols because of their high mobility and changing mobility pattern. Hence performance of routing protocols can vary with the various parameters such as speed, pause time, node density and traffic scenarios. In this research paper, the performance of two on-demand routing protocols AODV & DSR has been analyzed by means of packet delivery ratio, loss packet ratio & average end-to-end delay with varying pause time, speed time and node density under TCP & CBR connection.

  3. Performance Evaluation of Aodv&DSR with Varying Pause Time & Node Density Over TCP&CBR Connections in Vanet

    CERN Document Server

    Paul, Bijan; Bikas, Md Abu Naser

    2012-01-01

    Vehicular ad hoc network is formed by cars which are called nodes; allow them to communicate with one another without using any fixed road side unit. It has some unique characteristics which make it different from other ad hoc network as well as difficult to define any exact mobility model and routing protocols because of their high mobility and changing mobility pattern. Hence performance of routing protocols can vary with the various parameters such as speed, pause time, node density and traffic scenarios. In this research paper, the performance of two on-demand routing protocols AODV & DSR has been analyzed by means of packet delivery ratio, loss packet ratio & average end-to-end delay with varying pause time and node density under TCP & CBR connection.

  4. 尼罗罗非鱼TCP-1-beta和TCP-1-eta的分子特征及其低温诱导表达%MOLECULAR CHARACTERIZATION AND INDUCTION EXPRESSION OF TCP-1-BETA AND TCP-1-ETA UNDER LOW TEMPERATURES IN TILAPIA OREOCHROMIS NILOTICUS

    Institute of Scientific and Technical Information of China (English)

    谢建丽; 林勇; 曾兰; 王忠卫; 桂建芳

    2012-01-01

    为了研究尼罗罗非鱼耐寒性状的分子基础并为耐寒品种选育提供参考,研究从尼罗罗非鱼中克隆了HSP60家族TCP-1-beta和TCP-1-eta基因并对其在低温诱导下的表达特征进行了分析.尼罗罗非鱼TCP-1-beta cDNA长度为1755 bp,包括1605 bp的完整开放阅读框,编码534个氨基酸;尼罗罗非鱼TCP-1-eta cDNA长度1651 bp,包括1638 bp的完整开放阅读框,编码545个氨基酸.与其他物种同源基因的蛋白序列比对结果显示,TCP-1-beta和TCP-1-eta蛋白在物种间同源性很高,且都具有保守的ATP结合结构域等,预示其在物种间功能的保守性.实时荧光定量PCR结果表明:TCP-1-beta和TCP-1-eta在各组织中呈遍在表达,但在肌肉中表达量最高;诱导温度从22℃降至12℃,不同低温诱导48h后TCP-1-beta和TCP-1-eta均呈上调表达,在18℃时表达开始上调,随着低温胁迫程度加强,表达上调幅度增大,至12℃时表达量达到最高,TCP-1-beta和TCP-1-eta上调幅度分别达到常温的12.2倍和10.7倍.这些结果预示在尼罗罗非鱼中,TCP-1-beta和TCP-1-eta是潜在的耐寒相关基因.%Nile tilapia (Oreochromis niloticus) is one of the commercially important fish species in the southern China, but the lack of cold-resistant strains in tilapia results in a large number of deaths in winter and early spring. Some heat-shock proteins (Hsps) have been revealed to facilitate correct folding of other proteins under diverse forms of physiological stresses, such as extreme temperatures, chemical toxicity and oxidative stress. To understand the molecular mechanism of cold tolerance in fish, we cloned the full-length cDNAs of TCP-1-beta and TCP-1-eta of the Hsp60 family in nile tilapia {Oreochromis niloticus), and studied their expression patterns under normal and low temperature treatments. The TCP-1-beta cDNA consisted of 1755 bp and encoded a peptide of 534 amino acids. The TCP-1-eta cDNA consisted of 1651 bp and encoded a peptide of 545

  5. Improved Datagram Transport Protocol over Wireless Sensor Networks- TCP Fairness

    Directory of Open Access Journals (Sweden)

    Senthil Kumaran .M

    2011-09-01

    Full Text Available TCP connections have small bandwidth-delay product and frequent packet loss in wireless sensor networks due to route breakages and radio interference. Datagram transport protocol provides a reliable end-to-end transport protocol over wireless sensor networks. This paper deals with improvement of TCP Fairness as Fairness in wireless sensor networks plays a major role to have maximum fair share of available bandwidth among the nodes, thus energy is consumed. A distributed adaptive max-min algorithm has been proposed in order to improve the fairness in WSNs. The proposed scheme incorporates two techniques: a fixed-size window-based flow-control algorithm and a cumulative bit-vector-based selective ACK strategy. Security has got the major impact over WSNs and that has been overcome by logical Tunneling. The simulation results show the improvement in terms of fairness, throughput and delay and packet loss using Network Simulator NS-2.

  6. BIFURCATIONS AND CHAOS CONTROL IN TCP-RED SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Liu Fang

    2006-01-01

    Objective Analyzing the nonlinear dynamics of the TCP-RED congestion control system is of great importance. This study will help investigate the loss of stability in Internet and design a proper method for controlling bifurcation and chaos in such system. Methods Based on bifurcation diagram, the effect of parameter on system performance is discussed. By using the state feedback and parameter variation strategy, a simple real time control method is proposed to modify the existing RED scheme. Results With our control method, the parametric sensitivity of RED mechanism is attenuated. Moreover, a sufficient condition on the robust stability of the system is also derived to adjust the parameters in TCP-RED system. Conclusion The proposed method has the advantages of simple implementation and unnecessary knowledge of the exact system.

  7. TCP J17154683-3128303 = Nova Scorpius 2014

    Science.gov (United States)

    Jelinek, M.; Cunniffe, R.; Castro-Tirado, A. J.; Rabaza, O.; Hudec, R.

    2014-03-01

    Following the discovery on Mar 26 of a 10th mag new source in Scorpius dubbed TCP J17154683-3128303 by Nishiyama & Kabashima (CBAT Transient Object Follow-up Reports), also detected by Swift on Mar 27 (ATEL#6015), we report an optical spectrum obtained with the COLORES spectrograph at the TELMA 0.6m robotic telescope (equipped by COLORES) at the BOOTES-2 astronomical station in EELM-CSIC (Malaga, Spain). ...

  8. Modeling of TCP-Rab throughput and its empirical study%TCP-Rab的吞吐量模型及实验研究

    Institute of Scientific and Technical Information of China (English)

    汤旭红; 刘正蓝; 朱淼良

    2004-01-01

    基于接收端通告的TCP(TCP-Rab,receiver advertisement based TCP)协议是我们实现的一种新的TCP协议,在文献[1]中对TCP-Rab的算法设计、实现进行了详细阐述.本文对TCP-Rab进行了少量改进,重点导出了TCP-Rab的吞吐量性能模型,并对TCP-Rab进行了试验研究.该模型采用统计的方法,在导出TCP-Rab的吞吐量性能模型的时候,不仅考虑了TCP连接的拥塞避免阶段对吞吐量的影响,也考虑了慢启动阶段对吞吐量的影响,同时还考虑了一个发送窗口内多个数据包随机丢失对吞吐量的影响,因此该模型能适用于实际的网络环境中.

  9. A novel implementation of TCP Vegas for optical burst switched networks

    KAUST Repository

    Shihada, Basem

    2010-07-01

    TCP performance over bufferless Optical Burst Switched (OBS) networks could be significantly degraded due to the misinterpretation of network congestion status (referred to as false congestion detection). It has been reported that burst retransmission in the OBS domain can improve the TCP throughput by hiding burst loss events from the upper TCP layer, which can effectively reduce the congestion window fluctuation at the expense of introducing additional delay. However, the additional delay may cause performance degradation for delay-based TCP implementations that are sensitive to packet round trip time in estimating the network congestion status. In this paper, a novel implementation of TCP Vegas that adopts a threshold-based mechanism is proposed for identifying the network congestion status in OBS networks. Analytical models are developed to evaluate the throughput of conventional TCP Vegas and threshold-based Vegas over OBS networks with burst retransmission. Simulation is conducted to validate the analytical model and to compare threshold-based Vegas with a number of legacy TCP implementations, such as TCP Sack and TCP Reno. The analytical model can be used to obtain a proper threshold value that results in an optimal steady state TCP throughput.

  10. TCP Upload and Download Fairness over IEEE 802.11 Wired-cum-Wireless Heterogeneous Networks

    Institute of Scientific and Technical Information of China (English)

    REN Wei; JIN Hai

    2007-01-01

    A scheme of setting a limit to the TCP sending window size is proposed to improve the TCP fairness between upload and/or download flows in wired-cum-wireless networks. The goodput and delay of the upload and download TCP flows are compared to evaluate the TCP fairness for different schemes, which are the different combinations of setting a limit (64 or 4) to the sending window size and using the delayed acknowledgement (ACK) scheme or not. Extensive simulation results and analysis show that ( 1 )for TCP download flows, setting the limit of sending window size to 4 can improve the fairness; (2) for TCP upload flows, limiting the sending window size and using the delayed ACK strategy are both beneficial to fairness; (3) for TCP download and upload mixture flows, limiting the sending window size to a small value ( e. g. , 4) rather than using the delayed ACK strategy, is the solution to improvement of the fairness; (4) a large delay interval (200 ms or 300 ms) does not result in improvement in fairness and performance; (5) a larger TCP packet size ( 1 400 B) can improve the TCP upload goodput and decrease the download goodput; in contrast, a smaller TCP packet size (560 B) can increase the download goodput and decrease the upload goodput.

  11. TCP Issues in Mobile Ad Hoc Networks: Challenges and Solutions

    Institute of Scientific and Technical Information of China (English)

    Wei-Qiang Xu; Tie-Jun Wu

    2006-01-01

    Mobile ad hoc networks (MANETs) are a kind of very complex distributed communication systems with wireless mobile nodes that can be freely and dynamically self-organized into arbitrary and temporary network topologies. MANETs inherit several limitations of wireless networks, meanwhile make new challenges arising from the specificity of MANETs, such as route failures, hidden terminals and exposed terminals. When TCP is applied in a MANET environment, a number of tough problems have to be dealt with. In this paper, a comprehensive survey on this dynamic field is given. Specifically, for the first time all factors impairing TCP performance are identified based on network protocol hierarchy, I.e., lossy wireless channel at the physical layer; excessive contention and unfair access at the MAC layer; frail routing protocol at the network layer, the MAC layer and the network layer related mobile node; unfit congestion window size at the transport layer and the transport layer related asymmetric path. How these factors degrade TCP performance is clearly explained. Then, based on how to alleviate the impact of each of these factors listed above, the existing solutions are collected as comprehensively as possible and classified into a number of categories, and their advantages and limitations are discussed. Based on the limitations of these solutions, a set of open problems for designing more robust solutions is suggested.

  12. TCP/IP Sockets in C# Practical Guide for Programmers

    CERN Document Server

    Makofske, David; Calvert, Kenneth L

    2004-01-01

    "TCP/IP sockets in C# is an excellent book for anyone interested in writing network applications using Microsoft .Net frameworks. It is a unique combination of well written concise text and rich carefully selected set of working examples. For the beginner of network programming, it''s a good starting book; on the other hand professionals could also take advantage of excellent handy sample code snippets and material on topics like message parsing and asynchronous programming."Adarsh Khare, SDT, .Net Frameworks Team, Microsoft CorporationThe popularity of the C# language and the .NET framework is ever rising due to its ease of use, the extensive class libraries available in the .NET Framework, and the ubiquity of the Microsoft Windows operating system, to name a few advantages. TCP/IP Sockets in C# focuses on the Sockets API, the de facto standard for writing network applications in any programming language. Starting with simple client and server programs that use TCP/IP (the Internet protocol suite), students ...

  13. Traffic Flow Theory

    OpenAIRE

    Maerivoet, Sven; De Moor, Bart

    2005-01-01

    The scientific field of traffic engineering encompasses a rich set of mathematical techniques, as well as researchers with entirely different backgrounds. This paper provides an overview of what is currently the state-of-the-art with respect to traffic flow theory. Starting with a brief history, we introduce the microscopic and macroscopic characteristics of vehicular traffic flows. Moving on, we review some performance indicators that allow us to assess the quality of traffic operations. A f...

  14. Optimizing Traffic Flow

    OpenAIRE

    Huberman, Bernardo A.; Helbing, Dirk

    1998-01-01

    We present an economics-based method for deciding the optimal rates at which vehicles are allowed to enter a highway. The method exploits the naturally occuring fluctuations of traffic flow and is flexible enough to adapt in real time to the transient flow characteristics of road traffic. Simulations based on realistic parameter values show that this strategy is feasible for naturally occuring traffic, and that even far from optimality, injection policies can improve traffic flow. Our results...

  15. Traffic-flow simulation

    OpenAIRE

    OMAHEN, ANDRAŽ

    2015-01-01

    This diploma thesis presents the behavior of program, which uses the traffic light enhanced transport network to simulate the traffic flow of vehicles that behave according to the IDM model. We upgraded the program to allow, for the given network, to optimize the traffic flow. Because of the overwhelming problem of road closures or their rearrangement, we added a graphical user interface with which a user can create or modify the road network to observe changes in traffic. The objective of...

  16. Traffic Flow Estimates.

    Science.gov (United States)

    Hart, Vincent G.

    1981-01-01

    Two examples are given of ways traffic engineers estimate traffic flow. The first, Floating Car Method, involves some basic ideas and the notion of relative velocity. The second, Maximum Traffic Flow, is viewed to involve simple applications of calculus. The material provides insight into specialized applications of mathematics. (MP)

  17. TCP-RC增强Ad hoc网络TCP性能%Enhance TCP Performance in Ad hoc Network by TCP-RC

    Institute of Scientific and Technical Information of China (English)

    周建新; 石冰心

    2006-01-01

    目前改善Ad hoc网络中TCP性能的方法通常在路由中断/变化时暂时性地冷冻TCP连接,在路由重建后从冷冻的状态继续TCP传输.但TCP源端和目的端之间的路由在中断前和重建后可能完全不同,所以路由重建后TCP仍从路由中断前的状态继续TCP传输并不一定合适.本文提出了TCP-RC,它在路由重建后重新计算cwnd和ssthresh,使得TCP恢复传输时能根据当前TCP连接上的容量自适应地调整发送速率,降低突发流量造成网络拥塞的可能性.仿真表明TCP-RC在Ad hoc网络中取得了更好TCP性能.

  18. Modelling the Traffic System

    Directory of Open Access Journals (Sweden)

    Važan Pavel

    2014-12-01

    Full Text Available The paper presents the simulation study results of the traffic system in the city of Hlohovec. The authors describe the process of building the model in Witness 2013c simulator. The individual entities of simulation model are explained in details, as the Witness simulator is primarily suitable for manufacture or service simulation and not for traffic system simulation. The goal of this paper is to analyse the traffic system and to suggest the changes for improving the traffic in the city of Hlohovec. All proposed measures will bring about 20% improvement of traffic when compared to the current state.

  19. Structural and chemical analysis of silica-doped β-TCP ceramic coatings on surgical grade 316L SS for possible biomedical application

    Directory of Open Access Journals (Sweden)

    Karuppasamy Prem Ananth

    2015-09-01

    Full Text Available We have developed a novel approach to introduce silica-doped β-tricalcium phosphate (Si-β-TCP on 316L SS substrates for enhanced biological properties. Doping of β-TCP with silica loadings ranging from 0 to 8 mol% was carried out using chemical precipitation method. Si-β-TCP powder was sintered at 800 °C followed by coating it on 316L SS substrate using electrophoretic deposition. The coated and uncoated samples were investigated by various characterization techniques such as X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, field emission scanning electron microscopy (FESEM and X-ray fluorescence spectroscopy (XRF. Biomineralization ability of the coatings was evaluated by immersing in simulated body fluid (SBF solution for different number of days such as 7, 14, 21 and 28 days. The results obtained in our study have shown that the apatite formation ability was high for the 8 mol% of Si-β-TCP. This will promote better biomineralization ability compared to the other coatings.

  20. WinCE下科维可编程控制器Modbus/TCPIO驱动设计%DESIGN OF MODBUS/TCP IO DRIVER FOR KW PROCONOS UNDER WINCE

    Institute of Scientific and Technical Information of China (English)

    方崇全; 陈玮; 赵勇

    2014-01-01

    ProConOS (programmable controller operating system),developed by KW-Software GmbH,is a programmable logical control kernel software.Through customising WinCE on ARM processor,we design a Modbus/TCP client IO driver and a Modbus/TCP server IO driver supported by ProConOS,the test and analysis are carried out as well.It provides a way to realise the industrial field Modbus communi-cation based ProConOS IO driver and has been practically used in industrial field.%ProConOS(Programmable Controller Operating System)是德国科维公司开发的可编程逻辑控制内核软件。通过在 ARM处理器上定制 WinCE,设计了 ProConOS Modbus/TCP 客户端 IO 驱动和 Modbus/TCP 服务器 IO 驱动,并进行测试与分析。提供一种基于 ProConOS IO 驱动方式解决工业现场 Modbus 通信的方法,并在工业现场得到实际运用。

  1. FAST TCP over optical burst switched networks: Modeling and stability analysis

    KAUST Repository

    Shihada, Basem

    2013-04-01

    FAST TCP is important for promoting data-intensive applications since it can cleverly react to both packet loss and delay for detecting network congestion. This paper provides a continuous time model and extensive stability analysis of FAST TCP congestion-control mechanism in bufferless Optical Burst Switched Networks (OBS). The paper first shows that random burst contentions are essential to stabilize the network, but cause throughput degradation in FAST TCP flows when a burst with all the packets from a single round is dropped. Second, it shows that FAST TCP is vulnerable to burst delay and fails to detect network congestion due to the little variation of round-trip time, thus unstable. Finally it shows that introducing extra delays by implementing burst retransmission stabilizes FAST TCP over OBS. The paper proves that FAST TCP is not stable over barebone OBS. However, it is locally, exponentially, and asymptotically stable over OBS with burst retransmission.

  2. A new Grid Product of Tropical Cyclone Precipitation (TCP) for North America from 1930 to 2013

    Science.gov (United States)

    Zhu, L.

    2015-12-01

    We first developed a new method that collects daily TCP by using historical storm tracks and precipitation observation based on daily rain gauges in both U.S. and Mexico and calibrated it with satellite precipitation observation. We used a parametrized wind field to correct the possible under-estimations of precipitation in rain gauges. Grid interpolation parameters were optimized by testing different historical rain gauge densities and comparing our grid estimation of TCP and the observation from TRMM Multi-satellite Precipitation Analysis (3B42) by for the data available period from 1998 to 2013. The calibrated method was then used for the whole 94 years of TCP estimation. The preliminary result shows that the frequency of TCP events does not have significant change but the TCP intensity has significant increasing trends, especially in certain locations in North Carolina and Yucatan Peninsula in Mexico. This new long term TCP climatology can potentially assist model calibration and disaster prevention/mitigation.

  3. Traffic Flow Analysis Model based Routing Protocol For Multi-Protocol Label Switching Network

    Directory of Open Access Journals (Sweden)

    E. R. Naganathan

    2011-01-01

    Full Text Available Problem statement: Multi-Protocol Label Switching (MPLS is a mechanism which is used in high-performance telecommunications networks that directs and carries data from one network node to the next with the help of labels. Traffic management is still an issue in MPLS network as it involves high speed internet. Approach: This study proposed a traffic flow analysis of the real time MPLS traffic and segregates the MPLS traffic as three major class based on the outcome of traffic flow analysis. Using the traffic class. This study proposed a reliable transmission methodology which provides traffic free routing in the MPLS networks. Results: The proposed traffic flow analysis based reliable routing model overcomes the network traffic and provides effective routing by offering traffic free path. Conclusion: The proposed traffic flow analysis model outperforms existing routing protocol and offers comparatively negligible packet loss.

  4. Genome-Wide Comparative Analysis and Expression Pattern of TCP Gene Families in Arabidopsis thaliana and Oryza sativa

    Institute of Scientific and Technical Information of China (English)

    Xuan Yao; Hong Ma; Jian Wang; Dabing Zhang

    2007-01-01

    Several TCP genes have been reported to play important roles in plant development; the TCP homologs encode a plant-specific family of putative transcription factors. To understand the evolutionary relationship of TCP genes of Arabidopsis thaliana and Oryza sativa L. (hereafter called rice), we have identified 23 and 22 TCP genes in the Arabidopsls and rice genomes, respectively. Using phylogenetic analysis, we grouped these TCP genes into three classes. In addition, the motifs outside the TCP domain further support the evolutionary relationships among these genes. The genome distribution of the TCP genes strongly supports the hypothesis that genome-wide and tandem duplication contributed to the expansion of the TCP gene family. The expression pattern of the TCP genes was analyzed further, providing useful clues about the function of these genes.

  5. Transport Congestion Events Detection (TCED): Towards Decorrelating Congestion Detection from TCP

    OpenAIRE

    Anelli, Pascal; Lochin, Emmanuel; Harivelo, Fanilo; Lopez-Pacheco, Dino Martin

    2010-01-01

    International audience TCP(Transmission Control Protocol ) uses a loss-based algorithm to estimate whether the network is congested or not. The main difficulty for this algorithm is to distinguish spurious from real network congestion events. Other research studies have proposed to enhance the reliability of this congestion estimation by modifying the internal TCP algorithm. In this paper, we propose an original congestion event algorithm implemented independently of the TCP source code. B...

  6. OPTIMIZATION OF URBAN MULTI-INTERSECTION TRAFFIC FLOW VIA Q-LEARNING

    Directory of Open Access Journals (Sweden)

    Yit Kwong Chin

    2013-01-01

    Full Text Available Congestions of the traffic flow within the urban traffic network have been a challenging task for all the urban developers. Many approaches have been introduced into the current system to solve the traffic congestion problems. Reconfiguration of the traffic signal timing plan has been carried out through implementation of different techniques. However, dynamic characteristics of the traffic flow increase the difficulties towards the ultimate solutions. Thus, traffic congestions still remain as unsolvable problems to the current traffic control system. In this study, artificial intelligence method has been introduced in the traffic light system to alter the traffic signal timing plan to optimize the traffic flows. Q-learning algorithm in this study has enhanced the traffic light system with learning ability. The learning mechanism of Q-learning enables traffic light intersections to release itself from traffic congestions situation. Adjacent traffic light intersections will work independently and yet cooperate with each others to a common goal of ensuring the fluency of the traffic flows within the traffic network. The simulated results show that the Q-Learning algorithm is able to learn from the dynamic traffic flow and optimize the traffic flow accordingly.

  7. Performance Analysis of TCP Vegas-based LTE Network Congestion Control Algorithm%基于TCP Vegas的LTE网络拥塞控制算法性能分析

    Institute of Scientific and Technical Information of China (English)

    刘靖

    2015-01-01

    TCP Vegas和TCP Reno相比,虽然性能更强,吞吐量更高,但若将TCP Vegas部署在新的网络上仍存在较多障碍.以4G的LTE系统中部署TCP Vegas为例,分别对慢启动阶段的阈值设置和拥塞避免阶段的拥塞避免机制作相应改进.使用NS-2网络仿真LTE模型,结果表明TCP Vegas与TCP Reno相比具有更好的性能.

  8. Efficient enhancing scheme for TCP performance over satellite-based internet

    Institute of Scientific and Technical Information of China (English)

    Wang Lina; Gu Xuemai

    2007-01-01

    Satellite link characteristics drastically degrade transport control protocol (TCP) performance. An efficient performance enhancing scheme is proposed. The improvement of TCP performance over satellite-based Intemet is accomplished by protocol transition gateways at each end ora satellite link. The protocol which runs over a satellite link executes the receiver-driven flow control and acknowledgements- and timeouts-based error control strategies. The validity of this TCP performance enhancing scheme is verified by a series of simulation experiments. Results show that the proposed scheme can efficiently enhance the TCP performance over satellite-based Intemet and ensure that the available bandwidth resources of the satellite link are fully utilized.

  9. Fabrication of Porous α-TCP/Gellan Gum Scaffold for Bone Tissue Engineering.

    Science.gov (United States)

    Wen, Jian; Kim, Ill Yong; Kikuta, Koichi; Ohtsuki, Chikara

    2016-03-01

    α-tricalcium phosphate (α-TCP, α-Ca3(PO4)2) receives great attention for bone repairing due to its biodegradability and capability of transformation to human bone's main inorganic components, hydroxyapatite (HAp). α-TCP porous scaffold is easily procurable by sintering of the low-temperature polymorph of TCP, β-TCR Still, porous body of α-TCP is too brittle to being handled and shaped, limiting its clinical application as implant materials. To improve mechanical properties of α-TCP porous scaffold, the present study focused on coating of a type of polysaccharides on α-TCP scaffolds. Gellan gum was chosen as the polysaccharide for coating because of its biodegradability as well as the potential acting as substrate for HAp deposition during hydration of α-TCP after exposure to body fluid. After coating of gellan gum on α-TCP scaffolds with porosity of 75 vol%, the compressive strength increased from 0.45 MPa to around 2.00 MPa. Among the coated scaffold, the maximum compressive strength, 3.97 MPa, was obtained on the scaffold with porosity of 63 vol%. Improvement of mechanical properties of α-TCP/gellan gum composites was achieved to show easy handling performance for a bone substitute for tissue repairing. The dissolving rate of the coated scaffolds was also controlled by adjusting the concentration of GG solutions. PMID:27455764

  10. A Comparison of the TCP Variants Performance over different Routing Protocols on Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    S. R. Biradar

    2010-03-01

    Full Text Available We describe a variant of TCP (Tahoe, Vegas, TCP is most widely used transport protocol in both wired and wireless networks. In mobile ad hoc networks, the topology changes frequently due to mobile nodes, this leads to significant packet losses and network throughput degradation. This is due to the fact that TCP fails to distinguish the path failure and network congestion. In this paper, the performances of TCP over different routing (DSR, AODV and DSDV protocols in ad hoc networks wasstudied by simulation experiments and results are reported.

  11. Preparation and Drug-release Behavior of β-TCP Ceramics Drug Carrier in vitro

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qihuan; YAN Xin; YAN Yuhua; DAI Honglian; JIANG Xin; LI Shipu

    2012-01-01

    β-TCP ceramics drug carrier was first prepared and characterized.SEM showed that β-TCP carrier was in porous amorphous structure with diameters around 10 μm.The physical properties including apparent porosity,volume-weight,tensile strength and the permeability were measured and the results indicated those properties fit the clinical usage of β-TCP drug carrier.Furthermore,drug release experiment in vitro showed that the carrier could prolong drug release in simulated body fluid which provides basis for the clinical use of β-TCP ceramics as drug carrier.

  12. Implications of traffic characteristics on interdomain traffic engineering

    OpenAIRE

    Uhlig, Steve

    2004-01-01

    This thesis discusses the implications of the traffic characteristics on interdomain traffic engineering with BGP. We first provide an overview of the interdomain traffic control problem. Then, we present results concerning the characteristics of the interdomain traffic, based on the analysis of real traffic traces gathered from non-transit ASes. We discuss the implications of the topological properties of the traffic on interdomain traffic engineering. Based on this knowledge of the...

  13. TCP Freeze-Probing Enhancement for Mobile Ad Hoc Networks%基于无线自组织网络的TCP Freeze-Probing改进协议

    Institute of Scientific and Technical Information of China (English)

    王波; 范平志

    2005-01-01

    传统的TCP协议在有线网络中能够良好地工作,但用于无线自组织网络时则性能有所下降.其原因在于,传统的TCP协议无法分辨网络丢包原因,如网络拥塞、链路断开、信道错误或者链路改变.为了提高TCP协议在无线自组织网络中的性能,提出了一种TCP协议的改进方案TCP Freeze-Probing.该方案是一种端到端方法,不需要网络中间节点的反馈合作同时,提出了一种基于TCP Freeze-Probing的吞吐量模型并利用仿真对模型进行了验证.分析和仿真结果表明,该方案能够有效地改进TCP在无线自组织网络的性能.%Traditional Transmission Control Protocol (TCP) works well in wired network but suffers from performance degradation in mobile ad-hoc networks (MANET) due to the fact that it cannot distinguish packet losses due to congestion from packet losses due to link breakage, channel error and route changes. In this paper, an enhanced TCP, named TCP Freeze-Probing, is proposed to improve the TCP performance in mobile ad-hoc networks. TCP Freeze-Probing is an end-to-end approach that does not need the cooperation of the intermediate nodes in the network. Besides, a throughput model for TCP Freeze-Probing is given, which is validated through simulation. It is shown by analysis and simulation that the proposed approach can greatly improve the TCP performance in MANET.

  14. Comparison of TCP automatic tuning techniques for distributed computing

    Energy Technology Data Exchange (ETDEWEB)

    Weigle, E. H. (Eric H.); Feng, W. C. (Wu-Chun)

    2002-01-01

    Rather than painful, manual, static, per-connection optimization of TCP buffer sizes simply to achieve acceptable performance for distributed applications, many researchers have proposed techniques to perform this tuning automatically. This paper first discusses the relative merits of the various approaches in theory, and then provides substantial experimental data concerning two competing implementations - the buffer autotuning already present in Linux 2.4.x and 'Dynamic Right-Sizing.' This paper reveals heretofore unknown aspects of the problem and current solutions, provides insight into the proper approach for various circumstances, and points toward ways to further improve performance. TCP, for good or ill, is the only protocol widely available for reliable end-to-end congestion-controlled network communication, and thus it is the one used for almost all distributed computing. Unfortunately, TCP was not designed with high-performance computing in mind - its original design decisions focused on long-term fairness first, with performance a distant second. Thus users must often perform tortuous manual optimizations simply to achieve acceptable behavior. The most important and often most difficult task is determining and setting appropriate buffer sizes. Because of this, at least six ways of automatically setting these sizes have been proposed. In this paper, we compare and contrast these tuning methods. First we explain each method, followed by an in-depth discussion of their features. Next we discuss the experiments to fully characterize two particularly interesting methods (Linux 2.4 autotuning and Dynamic Right-Sizing). We conclude with results and possible improvements.

  15. 无线网络中TCP/NC协议性能分析与仿真验证%Performance Analysis and Simulation Verification of TCP/NC Protocol in Wireless Network

    Institute of Scientific and Technical Information of China (English)

    葛卫民; 朱海颖; 李娟

    2015-01-01

    In order to improve the traditional Transmission Control Protocol( TCP) performance in wireless networks, this paper solves throughput rate model of three TCP protocols,TCP Reno,TCP Vegas and TCP/NC based on network coding through Matlab,and analyzes the theoretical value of the three models in different networks,and verifies whether TCP/NC model can improve its throughput rate. The three models are simulated through NS-2,and simulation results show the effectiveness of TCP/NC protocol and its analysis model.%为改进传统传输控制协议( TCP)在无线网络中的性能,运用Matlab对TCP Reno,TCP Vegas和基于网络编码的TCP/NC吞吐率分析模型进行数值求解,分析3个模型在不同网络环境下应达到的理论值,验证TCP/NC模型在理论上能否提高其吞吐率。基于NS-2对3种吞吐率模型进行仿真,结果表明,TCP/NC及其分析模型可有效改进TCP协议。

  16. Comparative study of stability in different TCP/RED models

    International Nuclear Information System (INIS)

    This paper studies the stability issue of the average queue length of a Transmission Control Protocol (TCP) model when interacting with Random Early Detection (RED). The model used for the study has shown period doubling bifurcation (PDB) and border collision bifurcation (BCB) in the average queue size at certain values of parameters when original RED is deployed. In this paper, we adopt a gentle version of RED and a newly derived RED algorithm into the model to study the improvement in stability of average queue size of the system

  17. Trajectory Based Traffic Analysis

    DEFF Research Database (Denmark)

    Krogh, Benjamin Bjerre; Andersen, Ove; Lewis-Kelham, Edwin;

    2013-01-01

    We present the INTRA system for interactive path-based traffic analysis. The analyses are developed in collaboration with traffic researchers and provide novel insights into conditions such as congestion, travel-time, choice of route, and traffic-flow. INTRA supports interactive point-and-click a......We present the INTRA system for interactive path-based traffic analysis. The analyses are developed in collaboration with traffic researchers and provide novel insights into conditions such as congestion, travel-time, choice of route, and traffic-flow. INTRA supports interactive point......-and-click analysis, due to a novel and efficient indexing structure. With the web-site daisy.aau.dk/its/spqdemo/we will demonstrate several analyses, using a very large real-world data set consisting of 1.9 billion GPS records (1.5 million trajectories) recorded from more than 13000 vehicles, and touching most...

  18. Controlled release of NELL-1 protein from chitosan/hydroxyapatite-modified TCP particles.

    Science.gov (United States)

    Zhang, Yulong; Dong, Rui; Park, Yujin; Bohner, Marc; Zhang, Xinli; Ting, Kang; Soo, Chia; Wu, Benjamin M

    2016-09-10

    NEL-like molecule-1 (NELL-1) is a novel osteogenic protein that showing high specificity to osteochondral cells. It was widely used in bone regeneration research by loading onto carriers such as tricalcium phosphate (TCP) particles. However, there has been little research on protein controlled release from this material and its potential application. In this study, TCP was first modified with a hydroxyapatite coating followed by a chitosan coating to prepare chitosan/hydroxyapatite-coated TCP particles (Chi/HA-TCP). The preparation was characterized by SEM, EDX, FTIR, XRD, FM and Zeta potential measurements. The NELL-1 loaded Chi/HA-TCP particles and the release kinetics were investigated in vitro. It was observed that the Chi/HA-TCP particles prepared with the 0.3% (wt/wt) chitosan solution were able to successfully control the release of NELL-1 and maintain a slow, steady release for up to 28 days. Furthermore, more than 78% of the loaded protein's bioactivity was preserved in Chi/HA-TCP particles over the period of the investigation, which was significantly higher than that of the protein released from hydroxyapatite coated TCP (HA-TCP) particles. Collectively, this study suggests that the osteogenic protein NELL-1 showed a sustained release pattern after being encapsulated into the modified Chi/HA-TCP particles, and the NELL-1 integrated composite of Chi/HA-TCP showed a potential to function as a protein delivery carrier and as an improved bone matrix for use in bone regeneration research. PMID:27349789

  19. TCP- Costco Reno: New Variant by Improving Bandwidth Estimation to adapt over MANETs

    Directory of Open Access Journals (Sweden)

    Prakash B. Khelage

    2014-01-01

    Full Text Available The Transmission Control Protocol (TCP is traditional, dominant and has been de facto standard protocol, used as transport agent at transport layer of TCP/IP protocol suite. Basically it is designed to provide reliability and assure guaranty to end-to-end delivery of data over unreliable networks. In practice, most TCP deployments have been carefully designed in the context of wired networks. Ignoring the properties of wireless Ad Hoc Networks, therefore it can lead to TCP implementations with poor performance. The problem of TCP and all its existing variations within MANETs resides in its inability to distinguish between different data packet loss causes, whenever the data loss occur traditional TCP congestion control algorithm assumes loss is due to congestion episode and reduces sending parameters value unnecessary. Thus, TCP has not always the optimum behavior in front of packet losses which might cause network performance degradation and resources waste. In order to adapt TCP over mobile Ad hoc environment, improvements have been proposed based on RTT and BW estimation technique in the literature to help TCP to differentiate accurate causes between the different types of losses. But still does not handle all the problems accurately and effectively. In this paper, a proposed TCP-Costco Reno a New Variant, accurately estimates the available bandwidth over Mobile Ad Hoc networks and sets sending rate accordingly to maximize utilization of available resources and hence improves performance of TCP over mobile Ad hoc networks. The results of the simulation indicate an improvement in throughput over interference, link failure and signal loss validation scenarios. Further, it shows highest average of average throughput then those variants which are most successful over MANETs.

  20. Distributing Content Simplifies ISP Traffic Engineering

    OpenAIRE

    Sharma, Abhigyan; Venkataramani, Arun; Sitaraman, Ramesh

    2012-01-01

    Several major Internet service providers (e.g., Level-3, AT&T, Verizon) today also offer content distribution services. The emergence of such "Network-CDNs" (NCDNs) are driven by market forces that place more value on content services than just carrying the bits. NCDNs are also necessitated by the need to reduce the cost of carrying ever-increasing volumes of traffic across their backbones. An NCDN has the flexibility to determine both where content is placed and how traffic is routed within ...

  1. Normality of Ethernet Traffic at Large Time Scales

    Directory of Open Access Journals (Sweden)

    Zhiping Lu

    2013-01-01

    Full Text Available We contribute the quantitative descriptions of the large time scales for the Ethernet traffic to be Gaussian. We focus on the normality property of the accumulated traffic data under different time scales. The investigation is carried out graphically by the quantile-quantile (QQ plots and numerically by statistical tests. The present results indicate that the larger the time scale, the more normal the Ethernet traffic.

  2. Internet Traffic Engineering

    OpenAIRE

    Bonaventure, Olivier; Trimintzios, Panos; Pavlou, George; Quoitin, Bruno; Azcorra, Arturo; Bagnulo, Marcelo; Fegkas, Paris; García-Martínez, Alberto; Georgatsos, Panos; Georgiadis, Leonidas; Jacquenet, Christian; Swinnen, Louis; Tandel, Sebastien; Uhlig, Steve

    2004-01-01

    Traffic engineering encompasses a set of techniques that can be used to control the flow of traffic in data networks. We discuss several of those techniques that have been developed during the last few years. Some techniques are focused on pure IP networks while others have been designed with emerging technologies for scalable Quality of Service (QoS) such as Differentiated Services and MPLS in mind. We first discuss traffic engineering techniques inside a single domain. We show that by using...

  3. Distraction in traffic.

    OpenAIRE

    2013-01-01

    Many drivers, as well as cyclists and pedestrians, are occupied with all kinds of activities that can distract their attention from traffic, like listening to music, conducting a conversation on their mobile phone, or texting. Distraction has negative effects on traffic behaviour. Most studies estimate that distraction plays a role in the occurrence of about 5-25% of the car crashes. Considering the increasing diffusion of electronic devices in traffic, portable media devices as well as advan...

  4. Traffic Signs Inventory System

    Directory of Open Access Journals (Sweden)

    J. Ružbarský

    2013-06-01

    Full Text Available The paper is focused on practical application of Cambridge Correlator. The goal is to propose a traffic signs inventory system by using excellent characteristics of correlator in the rapid optical correlation. The proposal of this inventory system includes obtaining of traffic signs to create the database either collecting the GPS coordinates. It is necessary to know the traffic signs position and also to document the entire surface route for later evaluation in offline mode.

  5. Destabilizing Carry Trades

    OpenAIRE

    Plantin, Guillaume; Shin, Hyun Song

    2014-01-01

    We offer a model of currency carry trades in which carry traders generate self-sustained excess returns if they coordinate on supplying excessive capital to a target economy. The interest-rate differential between their funding currency and the target currency is their coordination device. Such self-fulfilling pro table currency trades arise when the central bank of the target economy ignores the impact of carry-trade in flows on domestic asset prices, and responds only to their effect on inf...

  6. Destabilizing carry trades

    OpenAIRE

    Guillaume Plantin; Hyun Song Shin

    2015-01-01

    We offer a model of currency carry trades in which carry traders generate self-sustained excess returns if they coordinate on supplying excessive capital to a target economy. The interest-rate differential between their funding currency and the target currency is their coordination device. Such self-fulfilling pro table currency trades arise when the central bank of the target economy ignores the impact of carry-trade in flows on domestic asset prices, and responds only to their effect on inf...

  7. 基于Modbus TCP/IP通信的研究与实现%Research and implementation of the communication based on the Modbus TCP/IP

    Institute of Scientific and Technical Information of China (English)

    黄建军; 陈西曲

    2014-01-01

    Modbus TCP/IP通信协议是在TCP/IP协议栈上嵌入Modbus报文,Modbus协议与以太网的结合扩展了Modbus的应用,该协议已经成为通用的工业通信协议标准之一.现在工业控制领域基于Modbus的通信仍然以串行链路的Modbus RTU为主,所以对Modbus TCP/IP通信协议的研究与应用都非常有意义.分析Modbus TCP/IP协议的总体结构描述,介绍其客户机/服务器模型以及实现客户机/服务器的通信.

  8. On the Impact of Zero-padding in Network Coding Efficiency with Internet Traffic and Video Traces

    DEFF Research Database (Denmark)

    Taghouti, Maroua; Roetter, Daniel Enrique Lucani; Pedersen, Morten Videbæk;

    2016-01-01

    the efficiency of RLNC or other erasure coding techniques. Our goal is to characterize the overhead generated by this zero-padding under real-traffic traces. These include TCP and UDP traces from traffic at core routers from CAIDA and a collection of video traces for different codecs and video resolution...... compiled by Arizona State University. Our numerical results show the dependence of the zero-padding overhead with the number of packets combined in a generation using RLNC. Surprisingly, medium and large TCP generations are strongly affected with more than 100% of padding overhead. Although all video...... traces are affected, our results show that higher resolution video has a lower overhead, due in part to the fact that most of the transmitted data packets are of the maximum size of packet in the network....

  9. Cross-layer TCP Performance Analysis in IEEE 802.11 Vehicular Environments

    Directory of Open Access Journals (Sweden)

    T. Janevski

    2014-06-01

    Full Text Available In this paper we provide a performance analysis of TCP in IEEE 802.11 vehicular environments for different well-known TCP versions, such as Tahoe, Reno, New Reno, Vegas, and Sack. The parameters of interest from the TCP side are the number of Duplicate Acknowledgements - DupAck, and the number of Delayed Acknowledgements - DelAck, while on the wireless network side the analyzed parameter is the interface queue - IFQ. We have made the analysis for the worst-case distance scenario for single-hop and worst-case multihop vehicular environments. The results show that the number of wireless hops in vehicular environments significantly reduces the TCP throughput. The best average performances considering all scenarios were obtained for TCP Vegas. However, the results show that the interface queue at wireless nodes should be at least five packets or more. On the other side, due to shorter distances in the vehicular wireless network, results show possible flexibility of using different values for the DupAck without degradation of the TCP throughput. On the other side, the introduction of the DelAck parameter provides enhancement in the average TCP throughput for all TCP versions.

  10. Functionally graded PCL/ β-TCP biocomposites in a multilayered structure for bone tissue regeneration

    Science.gov (United States)

    Kim, Yong Bok; Kim, GeunHyung

    2012-09-01

    Functionally graded (FG) composites consisting of polycaprolactone (PCL) and beta-tricalcium phosphate ( β-TCP) particles were fabricated with a multilayered structure using a melt plotter with a two-heating-barrel system. Using this process, the concentration of β-TCP particles varied in each layered strut. Scanning electron microscopy (SEM) and energy dispersive spectroscopy mapping of calcium on the fabricated scaffolds indicated that the β-TCP particles were well distributed in each PCL strut, according to conceptual design. By incorporating β-TCP, the FG-PCL/ β-TCP scaffolds had meaningful increases in water absorption (30 % increase) and showed good mechanical properties, although the mechanical properties are slightly low compared to pure PCL/ β-TCP composite. We performed biological assessments to evaluate the capability of these FG scaffolds to act as a biomaterial for bone tissue regeneration with osteoblast-like cells (MG63). SEM images of cell-seeded FG scaffolds showed that the concentrated β-TCP struts were affected as good cell attachment/proliferation sites. Additionally, calcium deposition on the FG scaffolds was higher than that of normal scaffolds after 14 days. In particular, we observed high levels of mineralization in the highly concentrated β-TCP struts in the FG scaffolds. Based on these results, we believe that the FG scaffolds having various spatially designed structures with graded properties will be widely applicable for hard tissue engineering applications.

  11. Robustness of Multiple High Speed TCP CUBIC Connections Under Severe Operating Conditions

    DEFF Research Database (Denmark)

    Pilimon, Artur; Ruepp, Sarah Renée; Berger, Michael Stübert

    2015-01-01

    We study the adaptation capabilities and robustness of the high-speed TCP CUBIC algorithm. For this purpose we consider a network environment with variable and high random packet loss and a large Bandwidth-Delay product, shared by multiple heterogeneous TCP connections. The analysis is based...

  12. DETERMINATION OF 3,5,6-TRICHLORO-2-PYRIDINOL (TCP) BY ELISA

    Science.gov (United States)

    A sensitive, competitive enzyme-linked immunosorbent assay (ELISA) for 3,5,6-trichloro-2pyridinol (TCP) has been developed to quantitate parts per billion (ppb) amounts of the analyte in urine. TCP is a major metabolite and environmental degradation product of the insecticide c...

  13. TCP and web browsing performance in case of bi-directional packet loss

    NARCIS (Netherlands)

    Kooij, R.E.; Mei, R.D. van der; Yang, R.

    2010-01-01

    Performance modeling of the transport control protocol (TCP) has received a lot of attention over the past few years. The most commonly quoted results are approximate formulas for TCP throughput (Padhye et al. (2000) [1]) and document download times (Cardwell et al. (2000) [2]) which are used for di

  14. Research on the Congest Control Algorithm of TCP/IP%基于TCP/IP拥塞控制的算法研究

    Institute of Scientific and Technical Information of China (English)

    李学渊

    2005-01-01

    在WPAN上使用TCP的关键在于拥塞控制,根据TCP的拥塞控制机制,通过分析拥塞控制的闭环控制原理、TCP/IP拥塞控制所使用的典型技术,研究TCP/IP拥塞控制在无线网上应用的算法.

  15. TCP/IP Protocol Security and IP Layer Encryption Technology%TCP/IP协议安全与IP层加密技术

    Institute of Scientific and Technical Information of China (English)

    谭兴烈

    2001-01-01

    @@ 由于互联网的广泛使用和TCP/IP协议在全球的风靡,对IP层安全处理技术的研究及在IP层开发的安全产品层出不穷,IP层安全成为一个受到广泛关注的问题,因此研究IP层的安全体系十分重要.TCP/IP协议的安全

  16. Calorimetry investigations of milled α-tricalcium phosphate (α-TCP) powders to determine the formation enthalpies of α-TCP and X-ray amorphous tricalcium phosphate.

    Science.gov (United States)

    Hurle, Katrin; Neubauer, Juergen; Bohner, Marc; Doebelin, Nicola; Goetz-Neunhoeffer, Friedlinde

    2015-09-01

    One α-tricalcium phosphate (α-TCP) powder was either calcined at 500°C to obtain fully crystalline α-TCP or milled for different durations to obtain α-TCP powders containing various amounts of X-ray amorphous tricalcium phosphate (ATCP). These powders containing between 0 and 71wt.% ATCP and up to 2.0±0.1wt.% β-TCP as minor phase were then hydrated in 0.1M Na2HPO4 aqueous solution and the resulting heat flows were measured by isothermal calorimetry. Additionally, the evolution of the phase composition during hydration was determined by in situ XRD combined with the G-factor method, an external standard method which facilitates the indirect quantification of amorphous phases. Maximum ATCP hydration was reached after about 1h, while that of crystalline α-TCP hydration occurred between 4 and 11h, depending on the ATCP content. An enthalpy of formation of -4065±6kJ/mol (T=23°C) was calculated for ATCP (Ca3(PO4)2), while for crystalline α-TCP (α-Ca3(PO4)2) a value of -4113±6kJ/mol (T=23°C) was determined.

  17. Efficient Frame Schedule Scheme for Real-time Video Transmission Across the Internet Using TCP

    Directory of Open Access Journals (Sweden)

    Yonghua Xiong

    2009-05-01

    Full Text Available The great end-to-end delays are the major factor to influence the visual quality of real-time video across the Internet using TCP as transport layer protocol. In this paper, we present a video frame schedule scheme for rate adaptive real-time video transmission over TCP. The scheme schedules video frames between the application layer sender-buffer, the TCP sender-buffer and TCP receiver-buffer and can regulate automaticlly the video frame rate and play out buffer delays according to the network congestion level. The sheme requires only an extra buffer of application layer and can significantly cut down the end-to-end delays of real-time video without any modification to the network infrastructure or TCP protocol stack. The performance of the proposed solution is evaluated through extensive simulations using the NS-2 simulator.

  18. A Novel Onboard-gateway-based Mechanism to Improve TCP Performance in Aeronautical Satellite Networks

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The IP-based networks on aircraft serve to support Internet services via satellites. However, in aeronautical satellite hybrid networks, the TCP protocol performance often deteriorates due to improper decreases and slow recovery of the congestion window. This paper proposes a window size determination and notification mechanism, onboard-gateway-based mechanism (OGBM), which is based on the onboard gateway in the networks on aircraft. A cross-layer approach is adopted by the onboard gateway to obtain the satellite link bandwidth information. And then, by the gateway, through changing the receiver's advertised window field in ACK packets, TCP sources are notified of the window size of each TCP source calculated on the ground of bandwidth delay product and flow numbers. The mechanism is able to avoid improper changes of TCP window and serve multiple users. Simulation results show that the mechanism with the fairness index close to 1 improves TCP performance in aeronautical satellite networks.

  19. Model Based System Engineering Approach of a Lightweight Embedded TCP/IP

    Directory of Open Access Journals (Sweden)

    M. Z. Rashed

    2011-04-01

    Full Text Available The use of embedded software is growing very rapidly. Accessing the internet is a necessaryservice which has large range of applications in many fields. The Internet is based on TCP/IPwhich is a very important stack. Although TCP/IP is very important there is not a softwareengineering model describing it. The common method in modeling and describing TCP/IP is RFCswhich is not sufficient for software engineer and developers. Therefore there is a need for softwareengineering approach to help engineers and developers to customize their own web basedapplications for embedded systems.This research presents a model based system engineering approach of lightweight TCP/IP. Themodel contains the necessary phases for developing a lightweight TCP/IP for embedded systems.The proposed model is based on SysML as a model based system engineering language.

  20. A Study and Detection of TCP SYN Flood Attacks with IP spoofing and its Mitigations

    Directory of Open Access Journals (Sweden)

    Deepak Singh Rana

    2012-07-01

    Full Text Available Flooding attacks are major threats on TCP/IP protocol suite these days; Maximum attacks are launched through TCP and exploit the resources and bandwidth of the machine. Flooding attacks are DDOS (Distributed denial of service attacks and utilize the weakness of the network protocols. SYN flood exploits the 3-way handshaking of the TCP by sending many SYN request with IP spoofing technique to victim host and exhaust the backlog queue resource of the TCP and deny legitimate user to connect. Capturing the packet flow is very important to detecting the DOS attack. This paper present how the TCP SYN flood takes place and show the number of packets received by the victim server under the attack.

  1. Evaluation of replacement protocols and modifications to TCP to enhance ASC Wide Area Network performance.

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Randy L. Jr.

    2004-09-01

    Historically, TCP/IP has been the protocol suite used to transfer data throughout the Advanced Simulation and Computing (ASC) community. However, TCP was developed many years ago for an environment very different from the ASC Wide Area Network (WAN) of today. There have been numerous publications that hint of better performance if modifications were made to the TCP algorithms or a different protocol was used to transfer data across a high bandwidth, high delay WAN. Since Sandia National Laboratories wants to maximize the ASC WAN performance to support the Thor's Hammer supercomputer, there is strong interest in evaluating modifications to the TCP protocol and in evaluating alternatives to TCP, such as SCTP, to determine if they provide improved performance. Therefore, the goal of this project is to test, evaluate, compare, and report protocol technologies that enhance the performance of the ASC WAN.

  2. Distraction in traffic.

    NARCIS (Netherlands)

    2013-01-01

    Many drivers, as well as cyclists and pedestrians, are occupied with all kinds of activities that can distract their attention from traffic, like listening to music, conducting a conversation on their mobile phone, or texting. Distraction has negative effects on traffic behaviour. Most studies estim

  3. Costs of traffic injuries

    DEFF Research Database (Denmark)

    Kruse, Marie

    2015-01-01

    assessed using Danish national healthcare registers. Productivity costs were computed using duration analysis (Cox regression models). In a subanalysis, cost per severe traffic injury was computed for the 12 995 individuals that experienced a severe injury. RESULTS: The socioeconomic cost of a traffic...

  4. The Traffic Light Challenge

    Science.gov (United States)

    Roman, Harry T.

    2014-01-01

    Traffic lights are an important part of the transportation infrastructure, regulating traffic flow and maintaining safety when crossing busy streets. When they go awry or become nonfunctional, a great deal of havoc and danger can be present. During power outages, the street lights go out all over the affected area. It would be good to be able to…

  5. Road Traffic in China

    NARCIS (Netherlands)

    Jie, L.; Van Zuylen, H.J.

    2014-01-01

    Traffic is tightly related to the social and economic development in a country. In China the development of the economy has been very fast in the past 30 years and this is still continuing. The transport infrastructure shows a similar pattern, while traffic is also rapidly growing. In urban areas th

  6. Controlled Traffic Farming

    OpenAIRE

    Controlled Traffic Farming Europe

    2011-01-01

    Metadata only record Controlled Traffic Farming (CTF) is a farming method used to reduce soil compaction, decrease inputs, and improve soil structure when coupled with reduced-till or no-till practices. This practices utilizes permanent traffic/wheel zones to limit soil compaction to a specific area. This website provides practical information on CTF, case studies, workshops, and links to additional resources.

  7. Hierarchical structures of β-TCP/45S5 bioglass hybrid scaffolds prepared by gelcasting.

    Science.gov (United States)

    Lopes, João Henrique; Magalhães, Jéssica Aparecida; Gouveia, Rubia Figueredo; Bertran, Celso Aparecido; Motisuke, Mariana; Camargo, Samira E A; Trichês, Eliandra de Sousa

    2016-09-01

    This paper investigates the microstructure and the mechanical properties of β-tricalcium phosphate (β-TCP) three-dimensional (3D) porous materials reinforced with 45S5 bioactive glass (BG). β-TCP and β-TCP/x%-BG scaffolds with interconnected pores networks, suitable for bone regeneration, were fabricated by gel-casting method. Mechanical properties, porosity, and morphological characteristics were evaluated by compressive strength test, scanning electron microscopy (SEM) and X-ray microtomography analysis, whereas the structures were fully explored by XRD, and Raman spectroscopy. To the best of our knowledge, this is the first time where the mechanism for understanding the effect of bioglass on the mechanical properties and microstruture of β-TCP/45S5-BG scaffolds has been systematically studied. The findings showed that ionic product lixiviated from 45S5 bioactive glass, rich in silicon species and sodium ion, catalyzes a phase transition from β-TCP to Si-TCP by replacement of phosphorus for silicon and contributes to the improvement of scaffolds mechanical properties. The compressive strength of β-TCP/5%-BG and β-TCP/7.5%-BG was improved around 200% in comparison to pure β-TCP. Osteoblast-like cells (MG 63) were exposed to the materials for 24h through the use of medium conditioned by β-tricalcium phosphate/bioactive glass. Cell viability was measured by MTT assay in the cells and the data obtained were submitted to ANOVA, Tukey׳s multiple comparison (p<0.05). The β-TCP/7.5-BG promoted an increase of cell proliferation. The results suggest that compositions and processing method studied may provide appropriate materials for tissue engineering. PMID:27161958

  8. Turning Traffic Jams to Jelly

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Beijing, known for having the worst traffic in China, is brewing up a traffic plan with the harshest ever measures to ensure smooth traffic flow as the capital’s gridlock during rush hour and private car sales soar.

  9. Traffic Light Options

    DEFF Research Database (Denmark)

    Jørgensen, Peter Løchte

    2007-01-01

    light solvency stress test system introduced by the Danish Financial Supervisory Authority (DFSA) in June 2001. This monitoring system requires L&P companies to submit regular reports documenting the sensitivity of the companies' base capital to certain pre-defined market shocks - the red and yellow......This paper introduces, prices, and analyzes traffic light options. The traffic light option is an innovative structured OTC derivative developed independently by several London-based investment banks to suit the needs of Danish life and pension (L&P) companies, which must comply with the traffic...... light scenarios. These stress scenarios entail drops in interest rates as well as in stock prices, and traffic light options are thus designed to pay off and preserve sufficient capital when interest rates and stock prices fall simultaneously. Sweden's FSA implemented a traffic light system in January...

  10. Traffic Light Options

    DEFF Research Database (Denmark)

    Jørgensen, Peter Løchte

    light solvency stress test system introduced by the Danish Financial Supervisory Authority (DFSA) in June 2001. This monitoring system requires L&P companies to submit regular reports documenting the sensitivity of the companies' base capital to certain pre-defined market shocks - the red and yellow......This paper introduces, prices, and analyzes traffic light options. The traffic light option is an innovative structured OTC derivative developed independently by several London-based investment banks to suit the needs of Danish life and pension (L&P) companies, which must comply with the traffic...... light scenarios. These stress scenarios entail drops in interest rates as well as in stock prices, and traffic light options are thus designed to pay off and preserve sufficient capital when interest rates and stock prices fall simultaneously. Sweden's FSA implemented a traffic light system in January...

  11. The Putative O-Linked N-Acetylglucosamine Transferase SPINDLY Inhibits Class I TCP Proteolysis to Promote Sensitivity to Cytokinin.

    Science.gov (United States)

    Steiner, Evyatar; Livne, Sivan; Kobinson-Katz, Tammy; Tal, Lior; Pri-Tal, Oded; Mosquna, Assaf; Tarkowská, Danuše; Mueller, Bruno; Tarkowski, Petr; Weiss, David

    2016-06-01

    Arabidopsis (Arabidopsis thaliana) SPINDLY (SPY) is a putative serine and threonine O-linked N-acetylglucosamine transferase (OGT). While SPY has been shown to suppress gibberellin signaling and to promote cytokinin (CK) responses, its catalytic OGT activity was never demonstrated and its effect on protein fate is not known. We previously showed that SPY interacts physically and functionally with TCP14 and TCP15 to promote CK responses. Here, we aimed to identify how SPY regulates TCP14/15 activities and how these TCPs promote CK responses. We show that SPY activity is required for TCP14 stability. Mutation in the putative OGT domain of SPY (spy-3) stimulated TCP14 proteolysis by the 26S proteasome, which was reversed by mutation in CULLIN1 (CUL1), suggesting a role for SKP, CUL1, F-box E3 ubiquitin ligase in TCP14 proteolysis. TCP14 proteolysis in spy-3 suppressed all TCP14 misexpression phenotypes, including the enhanced CK responses. The increased CK activity in TCP14/15-overexpressing flowers resulted from increased sensitivity to the hormone and not from higher CK levels. TCP15 overexpression enhanced the response of the CK-induced synthetic promoter pTCS to CK, suggesting that TCP14/15 affect early steps in CK signaling. We propose that posttranslational modification of TCP14/15 by SPY inhibits their proteolysis and that the accumulated proteins promote the activity of the CK phosphorelay cascade in developing Arabidopsis leaves and flowers. PMID:27208284

  12. Performance Analysis of TCP NewReno over a Cellular Last-Mile: Buffer and Channel Losses

    NARCIS (Netherlands)

    M. Panda; H.L. Vu; M. Mandjes; S.R. Pokhrel

    2015-01-01

    TCP NewReno is one of the most widely deployed TCP versions in today's Internet. However, a full understanding of the complex inter-dependencies between the losses due to wireless channel errors and those due to buffer overflows, and their (joint) impact on TCP NewReno's congestion control algorithm

  13. Preparation and Characterization ofβ-TCP/CS Scaffolds by Freeze-extraction and Freeze-gelation

    Institute of Scientific and Technical Information of China (English)

    HAO Ruiran; WANG Deping; YAO Aihua; HUANG Wenhai

    2011-01-01

    The freeze-extraction and freeze-gelation methods were used to prepare highly porous β-TCP/CS scaffolds with different β-TCP/CS ratio. In these methods, the suspending mixture of β-TCP and chitosan was frozen, the frozen mixture was immersed in a non-solvent(0.05 mol/L NaOH/ehanol aqueous) bath to allow the exchange between solvent(acetic-acid aqueous) and non-solvent at a temperature lower than the freezing point of the acetic-acid. Then, the β-TCP/CS scaffolds were formed and dried at room temperature. Scanning electron microscopy (SEM), X-ray diffraction (XRD), gas chromatography (GC) and omnipotence material testing machine were employed to characterize theβ-TCP/CS scaffolds. The results of GC show that the freeze extraction of the β-TCP/chitosan scaffolds was completed when the extraction time is above 24 h. The SEM results show that the β-TCP/CS scaffolds are composed of interconnected pore network. The porosity of the β-TCP/CS scaffolds decrease with the increase of the content of the β-TCP. The β-TCP/CS scaffolds have a highest compressive strength when the chitosan/β-TCP ratio is 30:70. The present work displays that the β-TCP/CS composite scaffolds with appropriate mechanical properties and high porosity can be successfully prepared by the freeze-extraction and freeze-gelation methods.

  14. ¿Hacia una Nueva Arquitectura Financiera Regional? Problemas y perspectivas de la cooperación monetaria en el ALBA-TCP

    Directory of Open Access Journals (Sweden)

    Benzi, D.

    2016-05-01

    Full Text Available This paper addresses the experiences of the monetary and financial cooperation carried out within the framework of ALBA-TCP. The first part describes the context of global crisis and emerging multipolarity in which the debate on the reform of the International Financial Architecture (IFA and regional monetary initiatives are inserted. The second part revises the Latin American initiative of a New Regional Financial Architecture. Later, we analyze the origins, processes and effects of mechanisms implemented within the ALBA-TCP, such as the ALBA Bank and the SUCRE. Finally, the essay concludes by presenting both potential and limitations of these experiences within a regional and global scenario marked by a high degree of uncertainty that, paradoxically so far, seems to delay and inhibit rather than consolidate the strengthening of a New Regional Financial Architecture.

  15. The curves not carried

    OpenAIRE

    Gadre, Vaibhav; Schleimer, Saul

    2014-01-01

    Suppose $\\tau$ is a train track on a surface $S$. Let $C(\\tau)$ be the set of isotopy classes of simple closed curves carried by $\\tau$. Masur and Minsky [2004] prove $C(\\tau)$ is quasi-convex inside the curve complex $C(S)$. We prove the complement, $C(S) - C(\\tau)$, is quasi-convex.

  16. Sister Carrie in China

    Institute of Scientific and Technical Information of China (English)

    殷希

    2015-01-01

    Sister Carrie has received many Chinese scholar's attention, and it has quantity relevance researches. Therefore, it is valuable to study why it is popular in China and it's education meaning for Chinese people. In addition, to analysis the domestic re-searches and find it's exist problems can help us make a new breakthrough from the study.

  17. Light-weight TCP/IP stack based on wireless embedded system%基于无线嵌入式系统的轻量级TCP/IP协议栈

    Institute of Scientific and Technical Information of China (English)

    吕俊龙; 陈春燕; 和卫星

    2010-01-01

    提出了一种基于小型无线嵌入式系统的轻量级TCP/IP协议栈CW_TCP/IP(compact wireless-TCP/IP).CW-TCP/IP使用适于小型嵌入式系统的简单数据结构调用CCB(connection control block)来处理TCP/IP,它创建TCP/IP头文件时不需参考其它数据结构,可以采用TCP Veno拥塞控制算法来提高其无线性能.该协议栈具有很高的便携性,因此可开发为处理器和独立的操作系统,目前它可以移植到Linux系统.通过实验对适用于小型嵌入式操作系统的CW-TCP/IP、Linux TCP/IP和μC/TCP-IP的性能进行了比较,比较的结果表明了CW-TCP/IP具有卓越的无线性能.

  18. 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.

  19. Application of Azolla for 2, 4, 6-Trichlorophenol (TCP Removal from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Zazouli

    2013-11-01

    Full Text Available Background & Aims of the Study: The 2, 4, 6-Trichlorophenol (TCP is a phenolic compound which it can produce adverse effects on human and environment. Therefore, the removal of these compounds is necessary. The aim of this study is the investigation of TCP removal by using Azolla filiculoides biomass. Materials & Methods: The Azolla biomass was dried in the sunlight, and then it was crushed and sieved to particle sizes in range of 1-2 mm. Next treated with 0.1M HCl for a period of 5h. The Azolla was washed with distilled water and it was used as adsorbent. The effect of operating parameters such as pH, contact time, TCP concentration and adsorbent dose on the TCP removal efficiency was investigated. The residues concentration of TCP was measured by spectrophotometer in λ max of 296 nm. Results: In optimum condition (pH 3, contact time 120 min , adsorbent dose 10 gr/l and TCP concentration 10 ppm, Azolla was able to remove 95% of TCP from aqueous solutions. The equilibrium data follows the Langmuir isotherm and the proper kinetic model is pseudo-second model. Conclusions: Adsorption process by Azolla filiculoides is an efficient method for removal of 2, 4, 6-Trichlorophenol from aqueous solutions.

  20. Models of TCP in high-BDP environments and their experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Vardoyan, G. [University of Massachusetts; Rao, Nageswara S [ORNL; Towlsey, D. [University of Massachusetts

    2016-01-01

    In recent years, the computer networking community has seen a steady growth in bandwidth-delay products (BDPs). Several TCP variants were created to combat the shortcomings of legacy TCP when it comes to operation in high-BDP environments. These variants, among which are CUBIC, STCP, and H-TCP, have been extensively studied in some empirical contexts, and some analytical models exist for CUBIC and STCP. However, since these studies have been conducted, BDPs have risen even more, and new bulk data transfer tools have emerged that utilize multiple parallel TCP streams. In view of these new developments, it is imperative to revisit the question: Which congestion control algorithms are best adapted to current networking environments? In order to help resolve this question, we contribute the following: (i) using first principles, we develop a general throughput-prediction framework that takes into account buffer sizes and maximum window constraints; (ii) we validate the models using measurements and achieve low prediction errors; (iii) we note differences in TCP dynamics between two experimental configurations and find one of them to be significantly more deterministic than the other; we also find that CUBIC and H-TCP outperform STCP, especially when multiple streams are used; and (iv) we present preliminary results for modelling multiple TCP streams for CUBIC and STCP.

  1. Genomewide analysis of TCP transcription factor gene family in Malus domestica

    Indian Academy of Sciences (India)

    Ruirui Xu; Peng Sun; Fengjuan Jia; Longtao Lu; Yuanyuan Li; Shizhong Zhang; Jinguang Huang

    2014-12-01

    Teosinte branched1/cycloidea/proliferating cell factor1 (TCP) proteins are a large family of transcriptional regulators in angiosperms. They are involved in various biological processes, including development and plant metabolism pathways. In this study, a total of 52 TCP genes were identified in apple (Malus domestica) genome. Bioinformatic methods were employed to predicate and analyse their relevant gene classification, gene structure, chromosome location, sequence alignment and conserved domains of MdTCP proteins. Expression analysis from microarray data showed that the expression levels of 28 and 51 MdTCP genes changed during the ripening and rootstock–scion interaction processes, respectively. The expression patterns of 12 selected MdTCP genes were analysed in different tissues and in response to abiotic stresses. All of the selected genes were detected in at least one of the tissues tested, and most of them were modulated by adverse treatments indicating that the MdTCPs were involved in various developmental and physiological processes. To the best of our knowledge, this is the first study of a genomewide analysis of apple TCP gene family. These results provide valuable information for studies on functions of the TCP transcription factor genes in apple.

  2. Efficacy of Honeycomb TCP-induced Microenvironment on Bone Tissue Regeneration in Craniofacial Area.

    Science.gov (United States)

    Watanabe, Satoko; Takabatake, Kiyofumi; Tsujigiwa, Hidetsugu; Watanabe, Toshiyuki; Tokuyama, Eijiro; Ito, Satoshi; Nagatsuka, Hitoshi; Kimata, Yoshihiro

    2016-01-01

    Artificial bone materials that exhibit high biocompatibility have been developed and are being widely used for bone tissue regeneration. However, there are no biomaterials that are minimally invasive and safe. In a previous study, we succeeded in developing honeycomb β-tricalcium phosphate (β-TCP) which has through-and-through holes and is able to mimic the bone microenvironment for bone tissue regeneration. In the present study, we investigated how the difference in hole-diameter of honeycomb β-TCP (hole-diameter: 75, 300, 500, and 1600 μm) influences bone tissue regeneration histologically. Its osteoconductivity was also evaluated by implantation into zygomatic bone defects in rats. The results showed that the maximum bone formation was observed on the β-TCP with hole-diameter 300μm, included bone marrow-like tissue and the pattern of bone tissue formation similar to host bone. Therefore, the results indicated that we could control bone tissue formation by creating a bone microenvironment provided by β-TCP. Also, in zygomatic bone defect model with honeycomb β-TCP, the result showed there was osseous union and the continuity was reproduced between the both edges of resected bone and β-TCP, which indicated the zygomatic bone reproduction fully succeeded. It is thus thought that honeycomb β-TCP may serve as an excellent biomaterial for bone tissue regeneration in the head, neck and face regions, expected in clinical applications. PMID:27279797

  3. Osteogenesis Capacity of a Novel BMP/α-TCP Bioactive Composite Bone Cement

    Institute of Scientific and Technical Information of China (English)

    YANG Wei-zhong; ZHOU Da-li; YIN Shao-ya; YIN Guang-fu; GAO Li-da; ZHANG Yun

    2004-01-01

    To improve the osteogenesis ability of α-tricalcium phosphate (α-TCP) bone cement,a novel BMP/α-TCP composite bone cement was prepared.By measuring the setting time and compressive strength,the hydration characteristic of bone cement was evaluated.Animal experiments including histological observation,radiographic investigation as well as digital image analyses reveal the difference of osteogenesis ability among BMP,α-TCP bone cement and BMP/α-TCP composite bone cement.Results show that α-TCP bone cement possesses excellent hydration and setting properties as well as high mechanical property.Comparison experiments show that BMP/α-TCP composite bone cement has a stronger osteogenesis ability.The gross observation of the implant site does not exhibit any inflammation or necrosis.Histological analyses reveal that the material has good osteointegration with host bone,and new bone formation is detected within the materials,which are degrading.Strong osteogenesis ability of the composite is due to not only the excellent osteoconductive potential but also the osteoinductive potential contributed by active BMP releasing and the material degradation.Large skull defect could be well-healed by filling BMP/α-TCP composite bone cement.This novel material proves itself to be an absorbable and bioactive bone cement with an osteogenesis ability.

  4. TCP with header checksum option for wireless links: An analytical approach towards performance evaluation

    Indian Academy of Sciences (India)

    Pawan Kumar Gupta; Joy Kuri

    2007-06-01

    TCP performs poorly in wireless mobile networks due to large bit error rates. Basically, the TCP sender responds to these losses as if they were due to congestion in the network, and reduces the congestion window unnecessarily. In earlier work, it has been shown that adding a TCP header checksum is very useful in differentiating between congestion loss and corruption loss. With the modified TCP, receivers can explicitly indicate corruption of received packets by generating “Explicit Loss Notifications (ELNs).” This paper focuses on an analytical study of this modified TCP protocol. We derive an expression for the probability of a receiver generating successful ELN, assuming a generic link layer protocol for data transfer over wireless links. Next, we develop an analytical approach for TCP throughput evaluation under the modified scheme. We compare the throughput results obtained by analysis and simulation, and find very close agreement between the two sets. We also compare the performance of the modified scheme with the standard NewReno TCP, and find considerable improvement in data throughput over wireless links.

  5. VBR video traffic models

    CERN Document Server

    Tanwir, Savera

    2014-01-01

    There has been a phenomenal growth in video applications over the past few years. An accurate traffic model of Variable Bit Rate (VBR) video is necessary for performance evaluation of a network design and for generating synthetic traffic that can be used for benchmarking a network. A large number of models for VBR video traffic have been proposed in the literature for different types of video in the past 20 years. Here, the authors have classified and surveyed these models and have also evaluated the models for H.264 AVC and MVC encoded video and discussed their findings.

  6. Road Traffic Injuries

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-guo

    2005-01-01

    @@ As everybody knows that automobiles have been greatly changing our life. However, everything has two sides, motor vehicles have also caused a huge number of people's deaths, injuries and property damage. Traffic crashes are perhaps the number one public health problem in developed countries [1]. In the United States, pre-retirement years of life lost in traffic crashes are more than that of the two combined leading diseases: cancer and heart disease [1]. Today road traffic crash (RTC) ranks 11th in leading cause of death and accounts for 2.1% of all deaths globally.

  7. TCP-friendliness Analysis and Evaluation for TCP-like IVS Flow Control Algorithm%TCP-like IVS流量控制算法TCP友好性的模拟评价和分析

    Institute of Scientific and Technical Information of China (English)

    贺凯健; 林亚平

    2002-01-01

    TCP-like IVS流量控制算法是对IVS流量控制算法的改进,提高了数据流稳定性和减小数据流抖动.文章研究TCP-like ⅣS流与TCP流争抢带宽资源中的TCP友好性问题.通过理论分析和模拟实验指出TCP-1ikeIVS流TCP友好性差的原因,提出未来改进的方向,为深入研究英特网上视频会议系统的QoS保证打下基础.

  8. Two dimensional mixed traffic flow considering the transit traffic

    OpenAIRE

    Lingjiang Kong; Junhui Hu; Li Yang

    2012-01-01

    Based on the two-dimension cellular automaton traffic flow model (BML model), a mixed traffic flow model for urban traffic considering the transit traffic is established in this paper by using the Don't block the box rules. We have investigated the influences of the transit traffic ratio, and found that, in most cases, the urban traffic flow exhibited jam phase. Moreover, focusing on the traffic lights cycle, it is found that the average flow has the periodic fluctuation phenomenon, and we ha...

  9. Modbus-Modbus TCP/IP的网关设计%Design of Modbus-Modbus TCP/IP gateway

    Institute of Scientific and Technical Information of China (English)

    李英奇; 吴桂初

    2013-01-01

    介绍一种基于STM32芯片的Modbus-Modbus TCP/IP网关系统,系统采用μCOSII嵌入式实时操作系统,实现Modbus串行链路到以太网的协议转换,利用多线程与存储池技术解决速率不匹配问题,最后对系统的通信质量进行相关测试.实验结果表明,系统方案能够在低廉的成本下,有效、准确地进行Modbus串行链路与以太网的相互通信.

  10. Desarrollo de alternativas al protocolo TCP para redes inalámbricas

    OpenAIRE

    FERNÁNDEZ HERNÁNDEZ, MARÍA

    2012-01-01

    Muchas de las investigaciones que se han llevado a cabo para mejorar el comportamiento del protocolo TCP en redes inalámbricas, consisten en modificaciones a dicho protocolo, mayormente centradas en cambios a su algoritmo de control de congestión. El objetivo de este trabajo es la implementación de dos de estas propuestas, TCP Vegas y TCP Westwood, para la suite IP INET Framework, del simulador de redes OMNeT++, y su posterior análisis. Fernández Hernánd...

  11. A New Route for Preparation of β-TCP/PLLA Composite

    Institute of Scientific and Technical Information of China (English)

    Feng ZHANG; Fang MEI; Xin Zhi WANG; Xiao Yang HU; Yong Ming LUO; Xu Liang DENG

    2006-01-01

    A new facile route for preparation of β-TCP/PLLA composites is reported in this letter.SEM images display that β-TCP particles with average diameter of 400 nm were well bonded and distributed within the pore walls of the PLLA scaffolds. The mixture of the novel complex and human dental pulp cells was transplanted subcutaneously into the dorsal surface of a nude mouse.Two months later histological examination showed that new collagen and new dentin formed.The results revealed that the new nano β-TCP/PLLA composite combined with human pulp cells could induce dentin formation, offering a new way to dental tissue engineering.

  12. Reducing Communication Overhead by Scheduling TCP Transfers on Mobile Devices using Wireless Network Performance Maps

    DEFF Research Database (Denmark)

    Højgaard-Hansen, Kim; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

    2012-01-01

    of such performance maps. We demonstrate how the framework can be used to reduce the retransmissions and to better utilise network resources when performing TCP-based file downloads in vehicular M2M communication scenarios. The approach works on top of a standard TCP stack hence has to map identified transmission......The performance of wireless communication networks has been shown to have a strong location dependence. Measuring the performance while having accurate location information available makes it possible to generate performance maps. In this paper we propose a framework for the generation and use...... potential for improvement in reducing the communication overhead compared with an ordinary TCP transfer....

  13. Traffic Accident Prediction Model Implementation in Traffic Safety Management

    OpenAIRE

    Wen, Keyao

    2009-01-01

    As one of the highest fatalities causes, traffic accidents and collisions always requires a large amounteffort to be reduced or prevented from occur. Traffic safety management routines therefore always needefficient and effective implementation due to the variations of traffic, especially from trafficengineering point of view apart from driver education.Traffic Accident Prediction Model, considered as one of the handy tool of traffic safety management,has become of well followed with interest...

  14. Non-Traffic Citations

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — Non-traffic citations (NTCs, also known as "summary offenses") document low-level criminal offenses where a law enforcement officer or other authorized official...

  15. Dementia and Traffic Accidents

    DEFF Research Database (Denmark)

    Petersen, Jindong Ding; Siersma, Volkert; Nielsen, Connie Thurøe;

    2016-01-01

    BACKGROUND: As a consequence of a rapid growth of an ageing population, more people with dementia are expected on the roads. Little is known about whether these people are at increased risk of road traffic-related accidents. OBJECTIVE: Our study aims to investigate the risk of road traffic...... Central Research Register, and/or (2) at least one dementia diagnosis-related drug prescription registration in the Danish National Prescription Registry. Police-, hospital-, and emergency room-reported road traffic-related accidents occurred within the study follow-up are defined as the study outcome...... selection bias due to nonparticipation and loss to follow-up. Furthermore, this ensures that the study results are reliable and generalizable. However, underreporting of traffic-related accidents may occur, which will limit estimation of absolute risks....

  16. Toll/Interleukin-1 Receptor Domain Derived from TcpC (TIR-TcpC) Ameliorates Experimental Autoimmune Arthritis by Down-modulating Th17 Cell Response.

    Science.gov (United States)

    Pasi, Shweta; Kant, Ravi; Surolia, Avadhesha

    2016-06-01

    Evasion through immunomodulation is one of the several strategies adopted by pathogens to prolong their survival within the host. One such pathogen, Escherichia coli CFT073, utilizes an immunomodulatory protein, TcpC, to combat the host's innate immune defense. TcpC abrogates the function of MyD88 in macrophages, thus perturbing all the signaling processes that involve this adaptor protein. Although central to various signaling pathways initiated by IL-1, IL-18, and toll-like receptors, the precise contribution of MyD88 to the development of autoimmunity, particularly rheumatoid arthritis, still needs extensive exploration. Herein, by using the toll/interleukin-1 receptor (TIR) domain homologous C-terminal motif of TcpC, i.e. TIR-TcpC, we found MyD88 to be critical for the induction and progression of rheumatoid arthritis through its pivotal role in the development of Th17 cells, the subset of CD4(+) T-cells widely implicated in various autoimmune disorders. The TIR-TcpC mediated inhibition of signaling through MyD88, and subsequent amelioration of experimental autoimmune arthritis was observed to be an outcome of perturbations in the NFκB-RORγt (RAR-related orphan receptor γt) axis. PMID:27022030

  17. Turning Traffic Jams to Jelly

    Institute of Scientific and Technical Information of China (English)

    LI LI

    2010-01-01

    @@ Beijing, known for having the worst traffic in China, is brewing up a traffic plan with the harshest ever measures to ensure smooth traffic flow as the capital's gridlock during rush hour and private car sales soar. On December 13, the Beijing Municipal Government started soliciting public opinions for a draft plan designed to relieve the city's traffic problems.

  18. Traffic-Adaptive Routing

    OpenAIRE

    Kammenhuber, Nils

    2011-01-01

    Despite the bursty and highly volatile traffic, routing in the Internet today is optimised only on coarse time scales, as load-adaptive routing is known to induce performance deterioration by causing massive oscillations. We describe ReplEx, an universally applicable distributed algorithm for dynamic routing/traffic engineering, which is based on game theory. We show through extensive realistic simulations that ReplEx does not oscillate, and that it achieves performance gains comparable to tr...

  19. Traffic engineering eye diagram

    OpenAIRE

    Kowalik, Karol; Collier, Martin

    2005-01-01

    It is said that a picture is worth a thousand words - this statement also applies to networking topics. Thus, to effectively monitor network performance we need tools which present the performance metrics in a graphical way which is also clear and informative. We propose a tool for this purpose which we call the traffic engineering eye diagram (TEED). Eye diagrams are used in digital communications to analyse the quality of a digital signal; the TEED can similarly he used in the traffic engin...

  20. Penalties in traffic.

    OpenAIRE

    2009-01-01

    Traffic offenders are penalized in various ways: fines, (temporary) driving licence suspensions, confiscation of their vehicles, penalty points, mandatory participation in rehabilitation programmes, prison sentences or community service. The aim of penalties is to punish offenders, to protect society and to influence the behaviour of offenders and all citizens (prevention). Many studies have found that the combination of enforcement and penalties prevent the violation of traffic regulations a...

  1. Ant traffic rules.

    Science.gov (United States)

    Fourcassié, Vincent; Dussutour, Audrey; Deneubourg, Jean-Louis

    2010-07-15

    Many animals take part in flow-like collective movements. In most species, however, the flow is unidirectional. Ants are one of the rare group of organisms in which flow-like movements are predominantly bidirectional. This adds to the difficulty of the task of maintaining a smooth, efficient movement. Yet, ants seem to fare well at this task. Do they really? And if so, how do such simple organisms succeed in maintaining a smooth traffic flow, when even humans experience trouble with this task? How does traffic in ants compare with that in human pedestrians or vehicles? The experimental study of ant traffic is only a few years old but it has already provided interesting insights into traffic organization and regulation in animals, showing in particular that an ant colony as a whole can be considered as a typical self-organized adaptive system. In this review we will show that the study of ant traffic can not only uncover basic principles of behavioral ecology and evolution in social insects but also provide new insights into the study of traffic systems in general. PMID:20581264

  2. 不对称链路中ACK优先调度算法的研究%Improving TCP performance over asymmetric links with acks-first scheduling

    Institute of Scientific and Technical Information of China (English)

    田辉; 仇洪冰

    2001-01-01

    在带宽不对称网络中,分析ACK密集对TCP传输带来的影响,采(用ACK优先调度算法来提高传输性能,通过仿真验证了分析的结论.仿真结果表明:在带宽不对称环境下采用ACK优先调度算法,可以减小报文的突发,减小ACK延时,提高链路利用率.%Over asymmetric links, that the effect of ack compression will cause reduction in network throughput is demonstrated and a scheme for improving the performance of TCP traffic is studied. The approach makes use of a acks-first scheduling mechanism to reduce ack compression. By analysis and simulation, this approach is shown to reduce the burst of the data segments, minimize the queuing delay for acks and improve TCP performance.

  3. Traffic Information System for Hanoi

    OpenAIRE

    Sohr, Alexander; Brockfeld, Elmar; Sauerländer-Biebl, Anke; Melde, Eric

    2016-01-01

    To improve the traffic situation in Hanoi it is necessary to have a good overview of the existing traffic situation and to monitor the development of the traffic over longer time periods. Floating Car Data (FCD) Systems can help to acquire area wide traffic information; here a FCD system based on taxis, busses and motor-cycles is described. It consists of Web and App tools and a Hotspot-Monitoring for long term traffic analysis.

  4. Research TCP/IP Network Communication Programming on Java Socket%JAVA TCP/IP Socket网络通信编程研究

    Institute of Scientific and Technical Information of China (English)

    戴歆

    2013-01-01

    First Java is a programming language for Internet. network Communication is the advantage of Java language. Using TCP/IP communication protocol in the program development is to realize the C/S model of point to point communication net-work. This thesis focuses on the study of Java Socket network programming framework and network communication program implementation in C/S mode.%Java最初是一种网络编程语言网络通信是Java语言的优势,在程序开发中利用TCP/IP通信协议则能实现C/S模式下的点对点的网络通信。该文主要研究在C/S模式下使用Java Socket实现TCP/IP网络程序框架及网络通信的程序实现。

  5. Analysis of OSI reference and TCP/IP reference model%OSI参考模型与TCP/IP参考模型的比较研究

    Institute of Scientific and Technical Information of China (English)

    刘烨

    2009-01-01

    OSI和TCP/IP是两种重要的网络体系结构.OSI参考模型与TCP/IP参考模型的共同之处是它们都采用了分层的思想,并且在同一层都采用了协议栈的概念,但他们在层次划分和功能设计上存在很大的区别.通过深入的研究,得出TCP/IP体系结构的特点,这些特点是使因特网之所以在今天成为全球最大广域网的原因.

  6. Research and Development of Industrial Real-time TCP/IP Protocol Stack%工业实时TCP/IP协议栈的研究与开发

    Institute of Scientific and Technical Information of China (English)

    韦安; 刘国平

    2005-01-01

    指出了通用TCP/IP协议用于工业控制存在的不足,通过对标准TCP/IP协议栈的简化,并加入自行开发的协议,开发了NETCON-TCP工业以太网控制协议,较好地解决了TCP/IP应用于实际控制中所存在的主要问题,详细描述了协议栈开发的细节.最后对比了NETCON-TCP和LINUX-TCP的实时性,验证了NETCON-TCP协议具有实时性好、体积小、可靠性较高的优点.

  7. TCP performance evaluation over AODV and DSDV in RW and SN mobility models

    Institute of Scientific and Technical Information of China (English)

    REN Wei; YEUNG D.Y.; JIN Hai

    2006-01-01

    This paper presents evaluation and comparison of the TCP performance in different mobile scenarios generated by Random Waypoint (RW) and Social Network (SN) mobility models. To our knowledge, TCP performance in SN mobility is discussed for the first time. The impact of AODV and DSDV routing protocols on the TCP goodput, delay and drop rate performance is also discussed. Extensive simulation results and analysis showed that TCP has better performance over AODV than over DSDV and has more stable performance in SN mobility than in RW mobility. We suggest using more mobility models, in particular, such as SN, in the evaluations of the transport layer or routing layer protocols because the mobility patterns have impacts on the protocol performance.

  8. On TCP-based Session Initiation Protocol (SIP) Server Overload Control

    CERN Document Server

    Shen, Charles

    2010-01-01

    The Session Initiation Protocol (SIP) server overload management has attracted interest since SIP is being widely deployed in the Next Generation Networks (NGN) as a core signaling protocol. Yet all existing SIP overload control work is focused on SIP-over-UDP, despite the fact that TCP is increasingly seen as the more viable choice of SIP transport. This paper answers the following questions: is the existing TCP flow control capable of handling the SIP overload problem? If not, why and how can we make it work? We provide a comprehensive explanation of the default SIP-over-TCP overload behavior through server instrumentation. We also propose and implement novel but simple overload control algorithms without any kernel or protocol level modification. Experimental evaluation shows that with our mechanism the overload performance improves from its original zero throughput to nearly full capacity. Our work leads to the important general insight that the traditional notion of TCP flow control alone is incapable of...

  9. An adaptive mechanism to guarantee the bandwidth fairness of TCP flows

    Institute of Scientific and Technical Information of China (English)

    张顺亮; 叶澄清

    2004-01-01

    End-to-end TCP(transmission control protocol)congestion control can cause unfairness among multiple TCP connections with different RTT(Round Trip Time). The throughput of TCP connection is inversely proportional to its RTT.To resolve this problem,researchers have proposed many methods. The existing proposals for RTT-aware conditioner work well when congestion level is low. However,they over-protect long RTT flows and starve short RTT flows when congestion level is high. Due to this reason,an improved method based on adaptive thought is proposed. According to the congestion level of networks,the mechanism can adaptively adjust the degree of the protection to long RTT flows. Extensive simulation experiments showed that the proposed mechanism can guarantee the bandwidth fairness of TCP flows effectively and outperforms the existing methods.

  10. An adaptive mechanism to guarantee the bandwidth fairness of TCP flows

    Institute of Scientific and Technical Information of China (English)

    张顺亮; 叶澄清

    2004-01-01

    End-to-end TCP (transmission control protocol) congestion control can cause unfairness among multiple TCP connections with different RTT (Round Trip Time). The throughput of TCP connection is inversely proportional to its RTT. To resolve this problem, researchers have proposed many methods. The existing proposals for RTT-aware conditioner work well when congestion level is low. However, they over-protect long RTT flows and starve short RTT flows when congestion level is high. Due to this reason, an improved method based on adaptive thought is proposed. According to the congestion level of networks, the mechanism can adaptively adjust the degree of the protection to long RTT flows. Extensive simulation experiments showed that the proposed mechanism can guarantee the bandwidth fairness of TCP flows effectively and outperforms the existing methods.

  11. New approach in subjective and objective speech transmission quality measurement in TCP/IP networks

    Science.gov (United States)

    Souček, Pavel; Slavata, Oldřich; Holub, Jan

    2015-02-01

    This paper deals with problems of speech transmission quality measurement in modern telecommunication networks. It focuses on problems caused by specific types of distortions and errors caused present in transmissions using TCP/IP networks.

  12. Improving TCP Performance over Wireless Links Using Link-Layer Retransmission and Explicit Loss Notification

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to support the mobility of computers during communication, the transport control protocol (TCP) con-nections between fixed host and mobile host often traverse wired and wireless networks, and the recovery of the losses dueto wireless transmission error is much different from congestion control. This paper analyzes the interaction between TCPand link layer retransmission scheme when the correlated packet are losses handled, indicates that a higher value of themaximum number of successive link layer timeout retransmissions has an adverse effect on TCP ability to perform conges-tion control rapidly. To achieve a better TCP performance, the paper proposes a strategy combining link-layer selective-re-ject automatic repeat request (ARQ) with explicit loss notification mechanism, which can respond to congestion quicklywhile keeping wireless link more reliable, and make TCP react to the different packet losses more suitably.

  13. SM_TCP: a new reliable multicast transport protocol for satellite IP networks

    Science.gov (United States)

    Liu, Gongliang; Gu, Xuemai; Li, Shizhong

    2005-11-01

    A new reliable multicast transport protocol SM_TCP is proposed for satellite IP networks in this paper. In SM_TCP, the XOR scheme with the aid of on-board buffering and processing is used for error recovery and an optimal retransmission algorithm is designed, which can reduce the recovery time by half of the RTT and minimize the number of retransmissions. In order to avoid the unnecessary decrease of congestion window in the high BER satellite channels, the occupied buffer sizes at bottlenecks are measured in adjusting the congestion window, instead of depending on the packet loss information. The average session rate of TCP sessions and of multicast sessions passing through the satellite are also measured and compared in adjusting the congestion window, which contributes to bandwidth fairness. Analysis and simulation results show fairness with TCP flows and scalability.

  14. Experimental study of channel delay impact on throughput performance of TCP and its extensions in space

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Substantially long round trip time (RTT) in space channel hurts TCP interactions between the sending and receiving ends, and limits the usefulness and effectiveness of TCP feedback. Space Communication Protocol Standards-Transport Protocol (SCPS-TP) is a Transmission Control Protocol (TCP) enhancement method aimed at improving its performance in space and interplanetary Intemet and is expected to have capability of being feasible applied to experimental evaluation of the effectiveness of SCPS-TP in coping with long channel delay. This paper presents an experimental evaluation of channel delay impact on throughput performance of SCPS-TP over LEO/GEO-stationary space links using a test-bed, compared with the widely deployed TCP.

  15. Comparative Performance Evaluation of TCP Variants in WiMAX (and WLANs Network Configurations

    Directory of Open Access Journals (Sweden)

    Konstantinos Tsiknas

    2012-01-01

    Full Text Available An important application for the IEEE 802.16 technology (also called WiMAX is to provide high-speed access to the Internet where the transmission control protocol (TCP is the core transport protocol. In this paper we study through extensive simulation scenarios the performance characteristics of five representative TCP schemes, namely, TCP New Reno, Vegas, Veno, Westwood, and BIC, in WiMAX (and WLANs networks, under the conditions of correlated wireless errors, asymmetric end-to-end capabilities, and link congestion. The target is to evaluate how the above conditions would affect the TCP congestion control and suggest the best schemes to be employed in WiMAX networks.

  16. VEGAS: Better Performance than other TCP Congestion Control Algorithms on MANETs

    Directory of Open Access Journals (Sweden)

    T.Kalakumari

    2011-05-01

    Full Text Available The wireless communication TCP/IP protocol is an important role in developing communicationsystems and which provides better and reliable communication capabilities in almost all kinds ofnetworking environment. The wireless networking technology and the new kind of requirements incommunication systems need some extensions to the original design of TCP for on comingtechnology development. In this paper we have analyzed six TCP Congestion Control Algorithmsand their performance on Mobile Ad-hoc Networks (MANET. More specifically, we describe theperformance behavior of BIC, Cubic, TCP Compound, Vegas, Reno and Westwood congestioncontrol algorithms. The evaluation is simulated through Network Simulator (NS2 and theperformance of these congestion control algorithms is analyzed with suitable metrics.

  17. Active queue management controller design for TCP communication networks: Variable structure control approach

    International Nuclear Information System (INIS)

    On the basis of variable structure control (VSC), an active queue management (AQM) controller is presented for a class of TCP communication networks. In the TCP/IP networks, the packet drop probability is limited between 0 and 1. Therefore, we modeled TCP/AQM as a rate-based non-linear system with a saturated input. The objective of the VSC-based AQM controller is to achieve the desired queue size and to guarantee the asymptotic stability of the closed-loop TCP non-linear system with saturated input. The performance and effectiveness of the proposed control law are then validated for different network scenarios through numerical simulations in both MATLAB and Network Simulator-2 (NS-2). Both sets of simulation results have confirmed that the proposed scheme outperforms other AQM schemes.

  18. Comparative study of microstructural remodification to porous β-TCP and HA in rabbits

    Institute of Scientific and Technical Information of China (English)

    SUN Jiao; SHEN QingYi; LU JianXi

    2009-01-01

    emodeling pattern resulted from bone formation and scaffold resorption was significantly different for the two bioceramics.The results demonstrated that the 75% porous β-TCP was more suitable for new bone remodification than HA scaffold.

  19. {beta}-TCP porous pellets as an orthopaedic drug delivery system: ibuprofen/carrier physicochemical interactions

    Energy Technology Data Exchange (ETDEWEB)

    Baradari, Hiba; Damia, Chantal; Dutreih-Colas, Maggy; Champion, Eric; Chulia, Dominique; Viana, Marylene, E-mail: hiva.baradari@etu.unilim.fr [SPCTS-Centre Europeen de la Ceramique, 12 Rue Atlantis, 87068 Limoges CEDEX (France)

    2011-10-15

    Calcium phosphate bone substitute materials can be loaded with active substances for in situ, targeted drug administration. In this study, porous {beta}-TCP pellets were investigated as an anti-inflammatory drug carrier. Porous {beta}-TCP pellets were impregnated with an ethanolic solution of ibuprofen. The effects of contact time and concentration of ibuprofen solution on drug adsorption were studied. The ibuprofen adsorption equilibrium time was found to be one hour. The adsorption isotherms fitted to the Freundlich model, suggesting that the interaction between ibuprofen and {beta}-TCP is weak. The physicochemical characterizations of loaded pellets confirmed that the reversible physisorption of ibuprofen on {beta}-TCP pellets is due to Van der Waals forces, and this property was associated with the 100% ibuprofen release.

  20. Applying a Hypoxia-Incorporating TCP Model to Experimental Data on Rat Sarcoma

    International Nuclear Information System (INIS)

    Purpose: To verify whether a tumor control probability (TCP) model which mechanistically incorporates acute and chronic hypoxia is able to describe animal in vivo dose–response data, exhibiting tumor reoxygenation. Methods and Materials: The investigated TCP model accounts for tumor repopulation, reoxygenation of chronic hypoxia, and fluctuating oxygenation of acute hypoxia. Using the maximum likelihood method, the model is fitted to Fischer-Moulder data on Wag/Rij rats, inoculated with rat rhabdomyosarcoma BA1112, and irradiated in vivo using different fractionation schemes. This data set is chosen because two of the experimental dose–response curves exhibit an inverse dose behavior, which is interpreted as due to reoxygenation. The tested TCP model is complex, and therefore, in vivo cell survival data on the same BA1112 cell line from Reinhold were added to Fischer-Moulder data and fitted simultaneously with a corresponding cell survival function. Results: The obtained fit to the combined Fischer-Moulder-Reinhold data was statistically acceptable. The best-fit values of the model parameters for which information exists were in the range of published values. The cell survival curves of well-oxygenated and hypoxic cells, computed using the best-fit values of the radiosensitivities and the initial number of clonogens, were in good agreement with the corresponding in vitro and in situ experiments of Reinhold. The best-fit values of most of the hypoxia-related parameters were used to recompute the TCP for non–small cell lung cancer patients as a function of the number of fractions, TCP(n). Conclusions: The investigated TCP model adequately describes animal in vivo data exhibiting tumor reoxygenation. The TCP(n) curve computed for non–small cell lung cancer patients with the best-fit values of most of the hypoxia-related parameters confirms previously obtained abrupt reduction in TCP for n < 10, thus warning against the adoption of severely hypofractionated

  1. On TCP-based Session Initiation Protocol (SIP) Server Overload Control

    OpenAIRE

    Shen, Charles; Schulzrinne, Henning

    2010-01-01

    The Session Initiation Protocol (SIP) server overload management has attracted interest since SIP is being widely deployed in the Next Generation Networks (NGN) as a core signaling protocol. Yet all existing SIP overload control work is focused on SIP-over-UDP, despite the fact that TCP is increasingly seen as the more viable choice of SIP transport. This paper answers the following questions: is the existing TCP flow control capable of handling the SIP overload problem? If not, why and how c...

  2. Occupant traffic estimation through structural vibration sensing

    Science.gov (United States)

    Pan, Shijia; Mirshekari, Mostafa; Zhang, Pei; Noh, Hae Young

    2016-04-01

    The number of people passing through different indoor areas is useful in various smart structure applications, including occupancy-based building energy/space management, marketing research, security, etc. Existing approaches to estimate occupant traffic include vision-, sound-, and radio-based (mobile) sensing methods, which have placement limitations (e.g., requirement of line-of-sight, quiet environment, carrying a device all the time). Such limitations make these direct sensing approaches difficult to deploy and maintain. An indirect approach using geophones to measure floor vibration induced by footsteps can be utilized. However, the main challenge lies in distinguishing multiple simultaneous walkers by developing features that can effectively represent the number of mixed signals and characterize the selected features under different traffic conditions. This paper presents a method to monitor multiple persons. Once the vibration signals are obtained, features are extracted to describe the overlapping vibration signals induced by multiple footsteps, which are used for occupancy traffic estimation. In particular, we focus on analysis of the efficiency and limitations of the four selected key features when used for estimating various traffic conditions. We characterize these features with signals collected from controlled impulse load tests as well as from multiple people walking through a real-world sensing area. In our experiments, the system achieves the mean estimation error of +/-0.2 people for different occupant traffic conditions (from one to four) using k-nearest neighbor classifier.

  3. "Christian carrying goomies".

    Science.gov (United States)

    1994-01-01

    Dr. Passingan Usurup tells critics of his pragmatic approach on condom promotion that he is a Christian carrying condoms for Christ. He is head of the University of Papua New Guinea Medical Center and is credited with developing an AIDS/HIV policy for the Papua New Guinea Defence Force. The condoms were named Goomy and promoted at launching in 1992 in a blue packet under the slogan "The bond that guards." Goomy was chosen as the name because it is pidgin for rubber, chewing gum, and anything associated with rubber. Blue packets were chosen over the calls of most soldiers for a camouflage design because of its universal appeal as the color of the sea and sky and because it was the preference of women in the airlines. Once firmly ensconced in his role at the University, Usurup plans to develop a policy for students and staff and help to conduct AIDS prevention and education activities on campus. He will encourage students to test for HIV rather than highlighting the gloom and doom of infection and disease.

  4. Remote Network Communication Based on Modbus and TCP/IP Protocol%基于Modbus和TCP/IP协议的远程网络通信

    Institute of Scientific and Technical Information of China (English)

    蒋近; 毛六平; 戴瑜兴

    2005-01-01

    进行了基于Modbus协议和TCP/IP协议相结合的远程网络通信的研究.采用套接字和多线程技术,使得Modbus协议的信息可以在TCP/IP协议的Internet和Intranet上传输,进一步扩展了Modbus协议的应用,并在用断路器组成的Modbus网络上实现了远程网络通信,这对于由Modbus组网的工业网络具有一定的现实意义.

  5. Air traffic management evaluation tool

    Science.gov (United States)

    Sridhar, Banavar (Inventor); Sheth, Kapil S. (Inventor); Chatterji, Gano Broto (Inventor); Bilimoria, Karl D. (Inventor); Grabbe, Shon (Inventor); Schipper, John F. (Inventor)

    2012-01-01

    Methods for evaluating and implementing air traffic management tools and approaches for managing and avoiding an air traffic incident before the incident occurs. A first system receives parameters for flight plan configurations (e.g., initial fuel carried, flight route, flight route segments followed, flight altitude for a given flight route segment, aircraft velocity for each flight route segment, flight route ascent rate, flight route descent route, flight departure site, flight departure time, flight arrival time, flight destination site and/or alternate flight destination site), flight plan schedule, expected weather along each flight route segment, aircraft specifics, airspace (altitude) bounds for each flight route segment, navigational aids available. The invention provides flight plan routing and direct routing or wind optimal routing, using great circle navigation and spherical Earth geometry. The invention provides for aircraft dynamics effects, such as wind effects at each altitude, altitude changes, airspeed changes and aircraft turns to provide predictions of aircraft trajectory (and, optionally, aircraft fuel use). A second system provides several aviation applications using the first system. Several classes of potential incidents are analyzed and averted, by appropriate change en route of one or more parameters in the flight plan configuration, as provided by a conflict detection and resolution module and/or traffic flow management modules. These applications include conflict detection and resolution, miles-in trail or minutes-in-trail aircraft separation, flight arrival management, flight re-routing, weather prediction and analysis and interpolation of weather variables based upon sparse measurements. The invention combines these features to provide an aircraft monitoring system and an aircraft user system that interact and negotiate changes with each other.

  6. Improve Performance of TCP New Reno Over Mobile Ad-Hoc Network Using ABRA

    Directory of Open Access Journals (Sweden)

    Dhananjay Bisen

    2011-05-01

    Full Text Available In a mobile ad hoc network, temporary link failures and route changes occur frequently. With theassumption that all packet losses are due to congestion, TCP performs poorly in such an environment.There are many versions of TCP which modified time to time as per need. In this paper modificationsintroduced on TCP New Reno over mobile ad-hoc networks using calculation of New RetransmissionTime out (RTO, to improve performance in term of congestion control. To calculate New RTO, adaptivebackoff response approach (ABRA in TCP New Reno was applied which suggest ABRA New Reno. Itutilizes an ABRA by which congestion window and slow start threshold values were decreased wheneveran acknowledgement is received and new backoff value calculate from smoothed round trip time.Evaluation based on comparative study of ABRA New Reno with other TCP Variants like New Reno andReno was done using realistic parameters like TCP Packet Received, Packet Drop, Packets Retransmitted,Throughput, and Packet Delivery Ratio calculated by varying attributes of Node Speed, Number of Nodesand Pause Time. Implementation and simulations were performed in QualNet 4.0 simulator.

  7. Congestion Control in TCP/AQM Networks Using a Disturbance Observer

    Science.gov (United States)

    Kubo, Ryogo; Kani, Junichi; Fujimoto, Yukihiro

    This paper presents a novel congestion controller for transmission control protocol/active queue management (TCP/AQM) networks. In order to maintain the queue length to a value less than the buffer size at the aggregation nodes, the queue management mechanism drops some packets depending on the probability calculated by a congestion controller. However, conventional controllers such as random early detection (RED) algorithms and proportional-integral-derivative (PID)-based controllers are not compatible with parameter variation in TCP/AQM networks. Parameter variation in TCP/AQM networks includes the change of the number of TCP connections, the inflow of user datagram protocol (UDP) flows and so on. In the proposed method, the effect of parameter variation is estimated as drop probability disturbance by using a disturbance observer (DOB). By using the DOB, disturbance suppression characteristics of the controlled system can be drastically improved. In addition, the TCP/AQM network system is analyzed on the basis of an acceleration control scheme. The proposed method is validated by simulation studies performed using a nonlinear model of a TCP/AQM network and verifications made using the network simulator ns-2.

  8. Momentary Recovery Algorithm: A New Look at the Traditional Problem of TCP

    Science.gov (United States)

    Hwang, Jae-Hyun; Yoo, See-Hwan; Yoo, Chuck

    Traditional TCP has a good congestion control strategy that adapts its sending rate in accordance with network congestion. In addition, a fast recovery algorithm can help TCP achieve better throughput by responding to temporary network congestion well. However, if multiple packet losses occur, the time to enter congestion avoidance phase would be delayed due to the long recovery time. Moreover, during the recovery phase, TCP freezes congestion window size until all lost packets are recovered, and this can make recovery time much longer resulting in performance degradation. To mitigate such recovery overhead, we propose Momentary recovery algorithm that recovers packet loss without an extra recovery phase. As other TCP and variants, our algorithm also halves the congestion window size when packet drop is detected, but it performs congestion avoidance phase immediately as if loss recovery is completed. For lost packets, TCP sender transmits them along with normal packets as long as congestion window permits rather than performs fast retransmission. In this manner, we can eliminate recovery overhead efficiently and reach steady state momentarily after network congestion. Finally, we provide a simulation based study on TCP recovery behaviors and confirm that our Momentary recovery algorithm always shows better performance compared with NewReno, SACK, and FACK.

  9. HALR: A TCP Enhancement Scheme Using Local Caching in High-Availability Cluster

    Science.gov (United States)

    Feng, Yi-Hsuan; Huang, Nen-Fu; Wu, Yen-Min

    In this paper, we study the end-to-end TCP performance over a path deploying a High-Availability cluster, whose characteristics are highlighted by the failover procedure to remove single-point failure. This paper proposes an approach, called High-Availability Local Recovery (HALR), to enhance TCP performance in the face of a cluster failover. To minimize the latency of retransmission, HALR saves TCP packets selectively and resends them locally after the failover is finished. For better understanding, we further develop simple analytic models to predict the TCP performance in the aspect of flow latency under a range of failover times and the effects of HALR. Using simulation results, we validate our models and show that HALR improves the TCP performance significantly over a failover event as compared with the original TCP. Typically, HALR reduces the flow latency from 4.1sec to less than 1.9sec when the failover time equals to 500ms. The simulation by real packet trace further demonstrates that the memory requirement of the proposed solution is not a concern for modern network equipments.

  10. Experiences with TCP/IP over an ATM OC12 WAN

    Energy Technology Data Exchange (ETDEWEB)

    Nitzan, Rebecca L.; Tierney, Brian L.

    1999-12-23

    This paper discusses the performance testing experiences of a 622.08 Mbps OC12 link. The link will be used for large bulk data transfer, and as such, of interest are both the ATM level throughput rates and end-to-end TCP/IP throughput rates. Tests were done to evaluate the ATM switches, the IP routers, the end hosts, as well as the underlying ATM service provided by the carrier. A low level of cell loss, (resulting in <.01 % packet loss), decreased the TCP throughput rate considerably when one TCP flow was trying to use the entire OC12 bandwidth. Identifying and correcting cell loss in the network proved to be extremely difficult. TCP Selective Acknowledgement (SACK) improved performance dramatically, and the maximum throughput rate increased from 300 Mbps to 400 Mbps. The effects of TCP slow start on performance at OC12 rates are also examined, and found to be insignificant for very large file transfers (e.g., for a 10 GB file). Finally, a history of TCP performance over high-speed networks is presented.

  11. Improve performance of tcp new reno over mobile ad-hoc network using abra

    CERN Document Server

    Bisen, Dhananjay

    2011-01-01

    In a mobile ad hoc network, temporary link failures and route changes occur frequently. With the assumption that all packet losses are due to congestion, TCP performs poorly in such an environment. There are many versions of TCP which modified time to time as per need. In this paper modifications introduced on TCP New Reno over mobile ad-hoc networks using calculation of New Retransmission Time out (RTO), to improve performance in term of congestion control. To calculate New RTO, adaptive backoff response approach (ABRA) in TCP New Reno was applied which suggest ABRA New Reno. It utilizes an ABRA by which congestion window and slow start threshold values were decreased whenever an acknowledgement is received and new backoff value calculate from smoothed round trip time. Evaluation based on comparative study of ABRA New Reno with other TCP Variants like New Reno and Reno was done using realistic parameters like TCP Packet Received, Packet Drop, Packets Retransmitted, Throughput, and Packet Delivery Ratio calcu...

  12. TCP: a tool for designing chimera proteins based on the tertiary structure information

    Directory of Open Access Journals (Sweden)

    Nishida Reina

    2009-01-01

    Full Text Available Abstract Background Chimera proteins are widely used for the analysis of the protein-protein interaction region. One of the major issues is the epitope analysis of the monoclonal antibody. In the analysis, a continuous portion of an antigen is sequentially substituted into a different sequence. This method works well for an antibody recognizing a linear epitope, but not for that recognizing a discontinuous epitope. Although the designing the chimera proteins based on the tertiary structure information is required in such situations, there is no appropriate tool so far. Results In light of the problem, we developed a tool named TCP (standing for a Tool for designing Chimera Proteins, which extracts some sets of mutually orthogonal cutting surfaces for designing chimera proteins using a genetic algorithm. TCP can also incorporate and consider the solvent accessible surface area information calculated by a DSSP program. The test results of our method indicate that the TCP is robust and applicable to various shapes of proteins. Conclusion We developed TCP, a tool for designing chimera proteins based on the tertiary structure information. TCP is robust and possesses several favourable features, and we believe it is a useful tool for designing chimera proteins. TCP is freely available as an additional file of this manuscript for academic and non-profit organization.

  13. The effect of Tricresyl-Phosphate (TCP) as an additive on wear of Iron (Fe)

    Science.gov (United States)

    Ghose, Hiren M.; Ferrante, John; Honecy, Frank C.

    1987-01-01

    The effect of tricresyl phosphate (TCP) as an antiwear additive in lubricant trimethyol propane triheptanoate (TMPTH) was investigated. The objective was to examine step loading wear by use of surface analysis, wetting, and chemical bonding changes in the lubricant. The investigation consisted of steploading wear studies by a pin or disk tribometer, the effects on wear related to wetting by contact angle and surface tension measurements of various liquid systems, the chemical bonding changes between lubricant and TCP chromatographic analysis, and by determining the reaction between the TCP and metal surfaces through wear scar analysis by Auger emission spectroscopy (AES). The steploading curve for the base fluid alone shows rapid increase of wear rate with load. The steploading curve for the base fluid in presence of 4.25 percent by volume TCP under dry air purge has shown a great reduction of wear rate with all loads studied. It has also been found that the addition of 4.25 percent by volume TCP plus 0.33 percent by volume water to the base lubricant under N2 purge also greatly reduces the wear rate with all loads studied. AES surface analysis reveals a phosphate type wear resistant film, which greatly increases load-bearing capacity, formed on the iron disk. Preliminary chromatographic studies suggest that this film forms either because of ester oxidation or TCP degradation. Wetting studies show direct correlation between the spreading coefficient and the wear rate.

  14. ETFRC: Enhanced TFRC for Media Traffic over Internet

    Directory of Open Access Journals (Sweden)

    Mohammad A. Talaat

    2011-08-01

    Full Text Available The evident increase in media traffic over Internet is expected to worsen its congestion state. TCP-friendly rate control protocol TFRC is one of the most promising congestion control techniques developed so far. TFRC has been thoroughly tested in terms of being TCP-friendly, responsive, and fair. Yet, its impact on the visual quality and the peak signal-to- noise ratio PSNR of the media traffic traversing Internet is still questionable. In this paper we aimed to point out the enhancements required for TFRC that enables producing the maximum PSNR value for Internet media traffic. Firstly, we suspected the default value of n that represents the number of loss intervals used in calculating the loss event rate in the TFRC equation. This value is recommended to be set to 8 according to the latest RFC of TFRC. We investigated the effect of modifying the TFRC mechanism on the resulting PSNR of the transmitted video over Internet using TFRC via switching n across the values from 2 to 16. We investigated the effect of such variation over a simulated network environment to study its effect on the resulting PSNR for a number of arbitrary video sequences. Our simulations results showed that running TFRC with n=11 led to reaching the maximum PSNR values among all the examined values of n including its default value. Secondly, we tested the impact on the PSNR of another modification in the TFRC mechanism via switching both values of n and Nfb which is frequency of feedback messages sent by TFRC receiver to its sender every round-trip time RTT. The default value of Nfb is 1; hence we scanned every possible combination of n and Nfb ranging from 2 to 16, and from 1 to 4, respectively and recorded the produced PSNR. It was obvious that several other combinations of n and Nfb produced higher PSNR values other than their default values in the request for comment RFC of TFRC. We hereby suggest using an enhanced TFRC that we abbreviated as ETFRC which has the values

  15. Emergent traffic jams

    CERN Document Server

    Nagel, K; Nagel, Kai; Paczuski, Maya

    1995-01-01

    We study a single-lane traffic model that is based on human driving behavior. The outflow from a traffic jam self-organizes to a critical state of maximum throughput. Small perturbations of the outflow far downstream create emergent traffic jams with a power law distribution P(t) \\sim t^{-3/2} of lifetimes, t. On varying the vehicle density in a closed system, this critical state separates lamellar and jammed regimes, and exhibits 1/f noise in the power spectrum. Using random walk arguments, in conjunction with a cascade equation, we develop a phenomenological theory that predicts the critical exponents for this transition and explains the self-organizing behavior. These predictions are consistent with all of our numerical results.

  16. Inaccuracy in traffic forecasts

    DEFF Research Database (Denmark)

    Flyvbjerg, Bent; Holm, Mette K. Skamris; Buhl, Søren Ladegaard

    2006-01-01

    This paper presents results from the first statistically significant study of traffic forecasts in transportation infrastructure projects. The sample used is the largest of its kind, covering 210 projects in 14 nations worth US$58 billion. The study shows with very high statistical significance......, the difference between actual and forecasted traffic is more than +-20%; for 25% of road projects, the difference is larger than +-40%. Forecasts for roads are more accurate and more balanced than for rail, with no significant difference between the frequency of inflated versus deflated forecasts. But for both...... forecasting. Highly inaccurate traffic forecasts combined with large standard deviations translate into large financial and economic risks. But such risks are typically ignored or downplayed by planners and decision-makers, to the detriment of social and economic welfare. The paper presents the data...

  17. Traffic Engineering in Metro Ethernet

    Directory of Open Access Journals (Sweden)

    Padmaraj Nair

    2010-05-01

    Full Text Available Traffic engineering is one of the major issues that has to be addressed in Metro Ethernet networks for quality of service and efficient resource utilization. This paper aims at understanding the relevant issues and outlines novel algorithms for multipoint traffic engineering in Metro Ethernet. We present an algorithmic solution for traffic engineering in Metro Ethernet using optimal multiple spanning trees. This iterative approach distributes traffic across the network uniformly without overloading network resources. We also introduce a new traffic specification model for Metro Ethernet, which is a hybrid of two widely used traffic specification models, the pipe and hose models.

  18. Generalized Deterministic Traffic Rules

    CERN Document Server

    Fuks, H; Fuks, Henryk; Boccara, Nino

    1997-01-01

    We study a family of deterministic models for highway traffic flow which generalize cellular automaton rule 184. This family is parametrized by the speed limit $m$ and another parameter $k$ that represents a ``degree of aggressiveness'' in driving, strictly related to the distance between two consecutive cars. We compare two driving strategies with identical maximum throughput: ``conservative'' driving with high speed limit and ``aggressive'' driving with low speed limit. Those two strategies are evaluated in terms of accident probability. We also discuss fundamental diagrams of generalized traffic rules and examine limitations of maximum achievable throughput. Possible modifications of the model are considered.

  19. Traffic Light Detection

    DEFF Research Database (Denmark)

    Philipsen, Mark Philip; Jensen, Morten Bornø; Møgelmose, Andreas;

    2015-01-01

    Traffic light recognition (TLR) is an integral part of any intelligent vehicle, which must function in the existing infrastructure. Pedestrian and sign detection have recently seen great improvements due to the introduction of learning based detectors using integral channel features. A similar push...... database is collected based on footage from US roads. The database consists of both test and training data, totaling 46,418 frames and 112,971 annotated traffic lights, captured in continuous sequences under a varying light and weather conditions. The learning based detector achieves an AUC of 0.4 and 0...

  20. Traffic signals - alternative method for emissions reduction; Liikennevaloillako paeaestoet alas

    Energy Technology Data Exchange (ETDEWEB)

    Niittymaeki, J. [Helsinki Univ. of Technology, Espoo (Finland)

    2001-07-01

    Traffic signalling is a process, which adapts to the prevailing traffic. The objective of traffic signalling is to direct traffic as safely as possible through a road junction. Other objectives are to maximize the road capacity, to clarify the traffic, and to effect the selection of routs. The target of design and timing of traffic signalling is to minimize the delays of the traffic. However, traffic signalling increases the emissions and fuel consumption. Traditionally the traffic adaptive control has been arranged on the basis of the extension principle, which means the extension of the green light as long as there is demand for the signal, however, only to a set maximum time. In practice the systems seeks an adequate distance in the traffic for cutting off the green light. New methods, such as mathematical optimization, fuzzy logic, neural networks and generic algorithms have been included traffic signalling. These new methods have proven to be 10-20% more efficient than the old ones. Results of the researches have shown that it is possible to achieve significant savings in social economy, including savings in fuels consumption and environmental impacts of the traffic, by development/renovation of traffic signalling. This article reviews the studies carried out in Finland on traffic signalling. A typical driving process through a signalized road junction: deceleration, idle running, acceleration and steady driving. The emissions of these phases differ from each other. Gasoline-fueled cars equipped with catalyst produces significantly more CO during idle running than in the other phases, and the HC content is highest during deceleration. On the other hand NO{sub x} formation is highest during acceleration. Formation of CO, HC and aldehydes is lowest during steady driving, and the formation of NO{sub x} during deceleration. CO and NO{sub x} emissions of diesel engines are highest during acceleration, and HC emissions during idle running. Total emissions of diesel

  1. TCP/IP网络协议栈攻击防范措施研究分析%TCP / IP Protocol Stack Attack Prevention Measures Study

    Institute of Scientific and Technical Information of China (English)

    曾振东

    2013-01-01

    由于TCP/IP网络协议栈在设计上的安全缺陷和脆弱性,使得在协议栈各个网络层次上均存在着各种类型的网络攻击技术方法,对互联网及内部网络的安全性造成威胁.该文主要介绍对网络各层的安全协议,也分别列举说明了各层的网络安全防范措施,对如何改善网络安全配置和使用条件,对TCP/IP网络协议栈攻击的防范技术及其发展,进行研究分析.%As the TCP/IP protocol stack in the design of security flaws and vulnerabilities in the protocol stack, so that each net?work level there are various types of network attack technology, on the Internet and the internal network security threat. This pa?per mainly introduces the network layer security protocol, were also examples of each layer of network security precautions, on how to improve the network security configuration and use conditions, the TCP/IP protocol stack attack prevention technology and its development, research and analysis.

  2. 利用VB的TCP/IP编程可拓宽GPS数据源%Diversification of GPS Data Source through TCP/IP Programming with Visual Basic(VB)

    Institute of Scientific and Technical Information of China (English)

    江中略

    2000-01-01

    文中论述了Visual Basic中如何使用Winsock控件实现TCP/IP环境下服务器和客户机之间的连接和通讯.籍此获取相应信息,并可将其转化成GPS的数据源,从而使GPS更高效、快捷.

  3. CNoA: Challenging Number Approach for uncovering TCP SYN flooding using SYN spoofing attack

    Directory of Open Access Journals (Sweden)

    L.Kavisankar

    2011-10-01

    Full Text Available The challenging number is used for the detection of Spoofing attack. The IP Spoofing is considered to beone of the potentially brutal attack which acts as a tool for the DDoS attack which is considered to be amajor threat among security problems in today’s internet. These kinds of attack are extremely severe.They bring down business of company drastically. DDoS attack can easily exhaust the computing andcommunication resources of its victim within a short period of time. There are attacks exploiting somevulnerability or implementation bug in the software implementation of a service to bring that down andsome attacks will use all the available resources at the target machine. This deals on attacks thatconsume all the bandwidth available to the victim machine. While concentrating on the bandwidth attackthe TCP SYN flood is the more prominent attack. TCP/IP protocol suite is the most widely used protocolsuite for data communication. The TCP SYN flood works by exhausting the TCP connection queue of thehost and thus denying legitimate connection request. There are various methods used to detect andprevent this attack, one of which is to block the packet based on SYN flag count from the same IP address.This kind of prevention methods becomes unsuitable when the attackers use the Spoofed IP address. TheSYN spoofing becomes a major tool the TCP SYN flooding. For the prevention of this kind of attacks, theTCP specific probing is used in the proposed scheme where the client is requested challenging numberwhile sending the ACK in the three way hand shake. This is very useful to find the Spoofed IPPackets/TCP SYN flood and preventing them.

  4. Combining phylogenetic and syntenic analyses for understanding the evolution of TCP ECE genes in eudicots.

    Directory of Open Access Journals (Sweden)

    Hélène L Citerne

    Full Text Available TCP ECE genes encode transcription factors which have received much attention for their repeated recruitment in the control of floral symmetry in core eudicots, and more recently in monocots. Major duplications of TCP ECE genes have been described in core eudicots, but the evolutionary history of this gene family is unknown in basal eudicots. Reconstructing the phylogeny of ECE genes in basal eudicots will help set a framework for understanding the functional evolution of these genes. TCP ECE genes were sequenced in all major lineages of basal eudicots and Gunnera which belongs to the sister clade to all other core eudicots. We show that in these lineages they have a complex evolutionary history with repeated duplications. We estimate the timing of the two major duplications already identified in the core eudicots within a timeframe before the divergence of Gunnera and after the divergence of Proteales. We also use a synteny-based approach to examine the extent to which the expansion of TCP ECE genes in diverse eudicot lineages may be due to genome-wide duplications. The three major core-eudicot specific clades share a number of collinear genes, and their common evolutionary history may have originated at the γ event. Genomic comparisons in Arabidopsis thaliana and Solanumlycopersicum highlight their separate polyploid origin, with syntenic fragments with and without TCP ECE genes showing differential gene loss and genomic rearrangements. Comparison between recently available genomes from two basal eudicots Aquilegiacoerulea and Nelumbonucifera suggests that the two TCP ECE paralogs in these species are also derived from large-scale duplications. TCP ECE loci from basal eudicots share many features with the three main core eudicot loci, and allow us to infer the makeup of the ancestral eudicot locus.

  5. β-TCP granules mixed with reticulated hyaluronic acid induce an increase in bone apposition

    International Nuclear Information System (INIS)

    β beta-tricalcium phosphate (β-TCP) granules are suitable for repair of bone defects. They have an osteoconductive effect shortly after implantation. However, dry granules are difficult to handle in the surgical room because of low weight and lack of cohesion. Incorporation of granules in a hydrogel could be a satisfactory solution. We have investigated the use of hyaluronic acid (HyA) as an aqueous binder of the granules. β-TCP granules were prepared by the polyurethane foam technology. Commercially available linear (LHya) and reticulated hyaluronic acid (RHyA) in aqueous solution were used to prepare a pasty mixture that can be handled more easily than granules alone. Thirteen New Zealand White rabbits (3.5–3.75 kg) were used; a 4 mm hole was drilled in each femoral condyle. After flushing, holes were filled with either LHyA, RHyA, dry β-TCP granules alone, β-TCP granules + LHyA and β-TCP granules + RHyA. Rabbits were allowed to heal for one month, sacrificed and femurs were harvested and analysed by microCT and histomorphometry. The net amount of newly formed bone was derived from measurements done after thresholding the microCT images for the material and for the material+bone. LHyA and RHyA did not result in healing of the grafted area. LHyA was rapidly eluted from the grafted zone but allowed deposition of more granules, although the amount of formed bone was not significantly higher than with β-TCP granules alone. RHyA permitted the deposition of more granules which induced significantly more bone trabeculae without inducing an inflammatory reaction. RHyA appears to be a good vehicle to implant granules of β-TCP, since HyA does not interfere with bone remodeling. (paper)

  6. DYNAMIC PCU VALUES AT SIGNALISED INTERSECTIONS IN INDIA FOR MIXED TRAFFIC

    Directory of Open Access Journals (Sweden)

    Sheela Alex

    2015-06-01

    Full Text Available The traffic stream behaves differently in a mixed traffic condition as compared to that of a homogeneous condition. In a mixed traffic condition, as the traffic behaviour is always fluctuating based on the interaction caused by the surrounding elements, it is essential that the factors which affect the dynamic nature of the traffic characteristics should be considered for the proper design of the system. The paper highlights the methodology for developing the dynamic Passenger Car Unit (PCU under various vehicular interactions for mixed traffic conditions prevalent in India. Experiments were carried out using the micro simulation model, TRAFFICSIM, which was developed for signalised intersections by the authors and reported elsewhere. The dynamic PCU values were obtained based on the analysis of the outputs of TRAFFICSIM, for varying approach width, traffic composition, stream speed and traffic volume. Modified area occupancy concept was used to develop Dynamic PCU values in a mixed traffic condition. In the modified area occupancy method, the area occupancy of the vehicle types for various traffic compositions is compared with area occupancy of the passenger cars in a car only traffic condition having the same stream speed. The study showed that the PCU values are highly sensitive to the given traffic conditions such as approach width, traffic composition, stream speed as well as flow ratio.

  7. Surface Traffic Management Research

    Science.gov (United States)

    Jung, Yoo Chul

    2012-01-01

    This presentation discusses an overview of the surface traffic management research conducted by NASA Ames. The concept and human-in-the-loop simulation of the Spot and Runway Departure Advisor (SARDA), an integrated decision support tool for the tower controllers and airline ramp operators, is also discussed.

  8. Air Traffic Flow Management

    CERN Document Server

    Ganu, Hrishikesh V

    2008-01-01

    Air Traffic Flow Management is the regulation of air traffic in order to avoid exceeding airport or flight sector capacity in handling traffic, and to ensure that available capacity is used efficiently. We have tried to explore the logic behind the claims by Bertsimas et.al about integral solutions to the LP relaxation of the Traffic Flow Management Problem(TFMP). Polyhedral theory only indicates that the stronger TFMP formulation of Bertsimas et.al might lead to integral solutions in some cases. Our computations indicate that the encouraging results reported by Bertsimas et.al are not merely fortuitous or due to their specific data set. Indeed, we found that the TFMP had integral solutions even in case of artificial data sets generated to include severe conflicts in the flight schedules. In our limited tests with 4-5 scenarios, we obtained non-integral solutions only once. This is of significant practical importance because, the LP relaxation can be solved even on small machines with low memory and processor...

  9. Traffic Engineering in Metro Ethernet

    OpenAIRE

    Padmaraj Nair; Suku Nair; Girish Chiruvolu

    2010-01-01

    Traffic engineering is one of the major issues that has to be addressed in Metro Ethernet networks for quality of service and efficient resource utilization. This paper aims at understanding the relevant issues and outlines novel algorithms for multipoint traffic engineering in Metro Ethernet. We present an algorithmic solution for traffic engineering in Metro Ethernet using optimal multiple spanning trees. This iterative approach distributes traffic across the network uniformly without overl...

  10. Chaotic Control of Network Traffic

    Institute of Scientific and Technical Information of China (English)

    YANG Tan; CUI Yi-Dong; JIN Yue-Hui; CHENG Shi-Duan

    2009-01-01

    A method of chaotic control on network traffic is presented.By this method,the chaotic network traffic can be controlled to a pre-assigned equilibrium point according to chaotic prediction and the largest Lyapunov exponent of the traffic on congested link is reduced,thereby the probability of traffic burst and network congestion can be reduced.Numerical examples show that this method is effective.

  11. Road Traffic Accidents in Kazakhstan

    OpenAIRE

    Alma Aubakirova; Alibek Kossumov; Nurbek Igissinov

    2013-01-01

    Background: The article provides the analysis of death rates in road traffic accidents in Kazakhstan from 2004 to 2010 and explores the use of sanitary aviation. Methods: Data of fatalities caused by road traffic accidents were collected and analysed. Descriptive and analytical methods of epidemiology and biomedical statistics were applied. Results: Totaly 27,003 people died as a result of road traffic accidents in this period. The death rate for the total population due to road traffic accid...

  12. Traffic flow modeling: a Genealogy

    OpenAIRE

    Van Wageningen-Kessels, F.L.M.; Hoogendoorn, S.P.; Vuik, C.; Lint, van J. W. C.

    2014-01-01

    80 years ago, Bruce Greenshields presented the first traffic flow model at the Annual Meeting of the Highway Research Board. Since then, many models and simulation tools have been developed. We show a model tree with four families of traffic flow models, all descending from Greenshields' model. The tree shows the historical development of traffic flow modeling and the relations between models. Based on the tree we discuss the main trends and future developments in traffic flow modeling and si...

  13. TCP Performance Analysis in Cognitive Radio Networks%认知网络下TCP协议性能分析

    Institute of Scientific and Technical Information of China (English)

    王精华; 徐昌彪; 鲜永菊; 袁伟; 张坤

    2011-01-01

    首先在无线环境下的基础上搭建认知平台,当主用户想要占次用户信道时,通过基站的频谱监测,频谱分配,分配次用户到其他空闲信道继续通信.其次,在此平台下分析TCP Reno,TCP Newreno,TCP Sackl和TCP vegas协议的性能,包括拥塞窗口、吞吐量.最后定量分析主用户活跃程度、切换后信道带宽和信道误比特率对TCP吞吐量的影响.%In this paper, a Cognitive Radio(CR) platform under wireless circumstances is established, when the Primary User(PU) attempts to occupy the channel, the CR switch secondary user to another idle channel through spectrum sensing and spectrum allocation, so that the communication of sec ondary user can be continued, this is where the innovation lies. Performance of TCP Reno, TCP Newreno, TCP Sackl and TCP vegas are all analyzed, in cuding congestion window and throughput. Finally, the PU activity level, channel bandwidth after switch and the effect on TCP throughput by channel bit error rate are quantitatively analyzed.

  14. Traffic sign detection and analysis

    DEFF Research Database (Denmark)

    Møgelmose, Andreas; Trivedi, Mohan M.; Moeslund, Thomas B.

    2012-01-01

    Traffic sign recognition (TSR) is a research field that has seen much activity in the recent decade. This paper introduces the problem and presents 4 recent papers on traffic sign detection and 4 recent papers on traffic sign classification. It attempts to extract recent trends in the field...

  15. Impact of traffic noise on railway traffic safety

    Directory of Open Access Journals (Sweden)

    Zdravko TOŠ

    2008-01-01

    Full Text Available Traffic noise is one of the dominant factors of ergo-assessment. The harmful impact of traffic noise on the engine driver as target group can be studied in isolation from other ergo-assessment factors only in the initial phase of research. The simultaneous action of several related factors in the system of ergo-assessment factors has cumulative effect on the perception and psychomotoric status of the railway traffic participants in the appropriate traffic situation. The initial partial research of traffic noise by a combination of several scientific methods needs to be eventually upgraded by studying the relations among several concurrent important or dominant ergo-assessment factors.

  16. Traffic Flow Analysis Model based Routing Protocol For Multi-Protocol Label Switching Network

    OpenAIRE

    E.R. Naganathan; Rajagopalan, S.; P. H. Raj

    2011-01-01

    Problem statement: Multi-Protocol Label Switching (MPLS) is a mechanism which is used in high-performance telecommunications networks that directs and carries data from one network node to the next with the help of labels. Traffic management is still an issue in MPLS network as it involves high speed internet. Approach: This study proposed a traffic flow analysis of the real time MPLS traffic and segregates the MPLS traffic as three major class based on the outcome of traffic flow analysis. U...

  17. A Model for Detecting Tor Encrypted Traffic using Supervised Machine Learning

    Directory of Open Access Journals (Sweden)

    Alaeddin Almubayed

    2015-06-01

    Full Text Available Tor is the low-latency anonymity tool and one of the prevalent used open source anonymity tools for anonymizing TCP traffic on the Internet used by around 500,000 people every day. Tor protects user's privacy against surveillance and censorship by making it extremely difficult for an observer to correlate visited websites in the Internet with the real physical-world identity. Tor accomplished that by ensuring adequate protection of Tor traffic against traffic analysis and feature extraction techniques. Further, Tor ensures anti-website fingerprinting by implementing different defences like TLS encryption, padding, and packet relaying. However, in this paper, an analysis has been performed against Tor from a local observer in order to bypass Tor protections; the method consists of a feature extraction from a local network dataset. Analysis shows that it's still possible for a local observer to fingerprint top monitored sites on Alexa and Tor traffic can be classified amongst other HTTPS traffic in the network despite the use of Tor's protections. In the experiment, several supervised machine-learning algorithms have been employed. The attack assumes a local observer sitting on a local network fingerprinting top 100 sites on Alexa; results gave an improvement amongst previous results by achieving an accuracy of 99.64% and 0.01% false positive.

  18. Urban Traffic Eco-Driving: Speed Advisory Tracking

    OpenAIRE

    De Nunzio, Giovanni; Canudas de Wit, Carlos; Moulin, Philippe

    2014-01-01

    International audience The evaluation of the benefits of an Eco-Driving assistance system is carried out in the urban environment in presence of traffic lights. The traffic evolution is modeled macroscopically with the Urban Variable-Length Model in a variable speed limits framework. Under the assumption of equal boundary flows, the vehicles in a road section dispose themselves according to well defined equilibrium conditions which are dependent on the traveling speed in the free-flow part...

  19. INFRASTRUCTURE FACILITIES FOR MONITORING AND INTELLECTUAL ROAD TRAFFIC MANAGEMENT

    Directory of Open Access Journals (Sweden)

    G. Belov

    2014-10-01

    Full Text Available Review of automatic management of road traffic technologies in major cities of Ukraine is carried out in the given article. Priority directions of studies are determined for producing modern and perspective technologies in the given area. The facilities for monitoring and intelligence management of the road traffic on the basis of the programmed logical controller, using the device of fuzzy logic are considered.

  20. Effort and Collective Creation: Experience in Air Traffic Control Work

    OpenAIRE

    Alice Itani

    2015-01-01

    How can work also represent a perspective of creation? We start from the hypothesis that air traffic controllers make an effort to cope with very hard work and to develop improvement processes when carrying out the activity, which can be considered creation. Our objective is to analyze the working conditions of air traffic controllers starting from the experience of the controller. There is effort, which is above all both cognitive and physical, of an activity developed with mental representa...

  1. Modeling Self-Similar Traffic for Network Simulation

    OpenAIRE

    Bai, Xiaofeng; Shami, Abdallah

    2013-01-01

    In order to closely simulate the real network scenario thereby verify the effectiveness of protocol designs, it is necessary to model the traffic flows carried over realistic networks. Extensive studies [1] showed that the actual traffic in access and local area networks (e.g., those generated by ftp and video streams) exhibits the property of self-similarity and long-range dependency (LRD) [2]. In this appendix we briefly introduce the property of self-similarity and suggest a practical appr...

  2. 基于TCP/IP协议的家电远程控制系统设计%Design of Remote Control System in Household Appliances Based on TCP/IP Protocol

    Institute of Scientific and Technical Information of China (English)

    李开国; 康志亮; 丁武伟; 沈茂

    2011-01-01

    A new remote control system based on STC89C58RD+ and ENC28J60 is designed. The system applies the simplified TCP/IP protocol to communicate IPv4 network with microcontroller, and the microcontroller can control multiple home appliances simultaneously by using infrared communication. The website can accept a lot of requests from multiple users. The network programs process the communication between the network and the corresponding microcontroller with aim of providing a remote control scheme, among which the multiuser can control multiple home appliances successfully. Experiments are carried out, and the results show that the rice cooker can be controlled remotely through internet.%利用STC89 C58 RD+单片机与ENC28J60网卡芯片设计了一种家电远程控制系统.该系统采用精简的TCP/IP协议实现单片机与IPv4网络通信,单片机用红外通信的方法来同时控制多个家电.网站接收多个用户请求,网络程序处理与对应单片机之间的通信,从而提供一种多用户远程控制多个家电的方案.对电饭煲进行测试,结果显示该方案能够通过互联网远程控制电饭煲.

  3. Effects of Traffic Lights on CA Traffic Model

    Institute of Scientific and Technical Information of China (English)

    SuweiFENG; GuoqingGU

    1997-01-01

    Cellular automaton traffic models can include various factors in traffic system with simple regulations and the corresponding computations and simulations are rather convenient and effective.In this paper,the Biham-Middleton-Levine model(briefly saying the BML model)is improved by removing its limitation of synchronized change of traffic lights.In new model,the traffic light at each crossing could arbitrarily change its starting time and tempo of variation and hence the model could more realistically describe the influence of traffic lights on the performance of traffic systems.The cases of traffic light with unsynchronized starting time and different tempo of variation are simulated in this paper.

  4. Enhancement of TCP Performance with the Help of Snoop Protocol in Wired CUM Wireless Network

    Directory of Open Access Journals (Sweden)

    Maninder Kaur

    2012-12-01

    Full Text Available The TCP networks have been the only communication for wired media that followed IEEE 802.3networks. This paper attempts to provide a comprehensive overview of this Link Layer approach i.e.Snoop protocol that improving throughput of TCP in wireless networks. It first explains the role of Snoopprotocol that overcomes the limitations of TCP protocols in wireless media. We investigated theapplication of this protocol in wireless networks and observed that a single hop in the wireless networkexperienced large variations in round trip time in a very short period. Without changes to the Snoopprotocol to accommodate these dramatic RTT variations, Snoop was performing badly compared withregular TCP even when there were no packet losses or errors. The main cause for this is prematureretransmissions performed by Snoop. We have modified the Snoop protocol to avoid these unnecessaryretransmissions by having a higher local retransmission timeout. The results showed us that Snoopbenefits from this approach which has made a significant performance improvement over regular TCP inmultihop wired cum wireless networks

  5. Fabrication of PLLA/β-TCP nanocomposite scaffolds with hierarchical porosity for bone tissue engineering.

    Science.gov (United States)

    Lou, Tao; Wang, Xuejun; Song, Guojun; Gu, Zheng; Yang, Zhen

    2014-08-01

    Polymer and ceramic composite scaffolds play a crucial role in bone tissue engineering. In an attempt to mimic the architecture of natural extracellular matrix (ECM), poly(l-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) nanocomposite scaffolds with a hierarchical pore structure were fabricated by combining thermal induced phase separation and salt leaching techniques. The nanocomposite scaffold consisted of a nanofibrous PLLA matrix with a highly interconnected, high porosity (>93%) hierarchical pore structure with pore diameters ranging from 500nm to 300μm and a homogeneously distributed β-TCP nanoparticle phase. The nanofibrous PLLA matrix had a fiber diameter of 70-300nm. The nanocomposite scaffolds possess three levels of hierarchical structure: (1) porosity; (2) nanofibrous PLLA struts comprising the pore walls; and (3) β-TCP nanoparticle phase. The β-TCP nanoparticle phase improved the mechanical properties and bioactivity of the PLLA matrix. The nanocomposite scaffolds supported MG-63 osteoblast proliferation, penetration, and ECM deposition, indicating the potential of PLLA/β-TCP nanocomposite scaffolds with hierarchical porosity for bone tissue engineering applications.

  6. A More Complete Model for TCP Connections Established between One Server and Many Receivers

    Institute of Scientific and Technical Information of China (English)

    LINYu; CHENGShiduan; WUHaitao; WANGChonggang

    2003-01-01

    Different from previous TCP (transmis-sion control program) modeling works, this paper presents a more complete analytical model of multiple TCP con-nections established between a busy server and multiple receivers under two distinct cases: the case there is suffi-cient bandwidth and the case there is a bandwidth bottle-neck link between the server and receivers. In the former case, the server will become the bottleneck of the whole system, and TCP behaviors are different from the model presented before. However, in the latter case, multiple TCP connections will share the bandwidth of the bottle-neck link. Based on the analysis of working flows in the system and a M/G/1 queueing model, the RTT and long-term TCP throughput formulae are derived in terms of number of TCPs, packet loss rate, and end-to-end delay.And the effect of maximum window size is also investi-gated. The simulation results confirm that new model is more accurate than previous model.

  7. LWD–TCP complex activates the morning gene CCA1 in Arabidopsis

    Science.gov (United States)

    Wu, Jing-Fen; Tsai, Huang-Lung; Joanito, Ignasius; Wu, Yi-Chen; Chang, Chin-Wen; Li, Yi-Hang; Wang, Ying; Hong, Jong Chan; Chu, Jhih-Wei; Hsu, Chao-Ping; Wu, Shu-Hsing

    2016-01-01

    A double-negative feedback loop formed by the morning genes CIRCADIAN CLOCK ASSOCIATED1 (CCA1)/LATE ELONGATED HYPOCOTYL (LHY) and the evening gene TIMING OF CAB EXPRESSION1 (TOC1) contributes to regulation of the circadian clock in Arabidopsis. A 24-h circadian cycle starts with the peak expression of CCA1 at dawn. Although CCA1 is targeted by multiple transcriptional repressors, including PSEUDO-RESPONSE REGULATOR9 (PRR9), PRR7, PRR5 and CCA1 HIKING EXPEDITION (CHE), activators of CCA1 remain elusive. Here we use mathematical modelling to infer a co-activator role for LIGHT-REGULATED WD1 (LWD1) in CCA1 expression. We show that the TEOSINTE BRANCHED 1-CYCLOIDEA-PCF20 (TCP20) and TCP22 proteins act as LWD-interacting transcriptional activators. The concomitant binding of LWD1 and TCP20/TCP22 to the TCP-binding site in the CCA1 promoter activates CCA1. Our study reveals activators of the morning gene CCA1 and provides an action mechanism that ensures elevated expression of CCA1 at dawn to sustain a robust clock. PMID:27734958

  8. Edge isolation of transparent conductive polymer (TCP) thin films on flexible substrates using UV laser ablation.

    Science.gov (United States)

    Hsiao, Wen-Tse; Tseng, Shih-Feng; Huang, Kuo-Cheng; Chiang, Donyau; Chen, Ming-Fei

    2012-06-01

    The purpose of this study was to directly use the writing techniques for the complex electrode edge isolation of transparent conductive polymer (TCP) thin films by a nanosecond pulsed UV laser processing system. The processing parameters including the laser pulse energy, the pulse repetition frequency, and the scan speed of galvanometers were examined to ablate the TCP films deposited on polyethylene terephtalate substrates of 188 microm thick. The thickness of TCP films was approximately 20 nm. The laser pulse repetition frequency and the scan speed of galvanometers were applied to calculate the overlapping rate of laser spots and to discuss the patterning region quality. Surface morphology, edge quality, and width and depth of edge isolated patterning structures after laser ablation process were measured by a three-dimensional confocal laser scanning microscope. In addition, the electrical conductivity of ablated TCP films was measured by a four-point probes instrument. After isolated line patterning was formed, the ablated TCP films with a better edge quality were obtained directly when the overlapping rate of laser spots, the scan speed, and the pulse repetition rate were 83.3%, 200 mm/s, and 40 kHz, respectively. The better surface morphology of electrode pattern structures was also obtained when the scan speed and the pulse repetition rate were 500 mm/s and 40 kHz, respectively. PMID:22905550

  9. SATNET development and operation. Pluribus satellite IMP development, remote site maintenance. Internet development: Mobile access terminal network, TCP for the HP3000, TCP-TAC, TCP for VAX-UNIX

    Science.gov (United States)

    Bressler, R. D.

    1980-11-01

    This Quarterly Technical Report is the current edition in a series of reports which describe the work being performed at BBN in fulfillment of several ARPA work statements. This QTR covers work on several ARPA-sponsored projects including (1) development and operation of the SATNET satellite network; (2) development of the Pluribus Satellite IMP; (3) Remote Site Maintenance activities; (4) inter-network monitoring; (5) development of the Mobile Access Terminal Network; (6) TCP for the HP3000; (7) TCP-TAC; and (8) TCP for the VAX-UNIC. This work is described in this single Quarterly Technical Report with the permission of the Defense Advanced Research Projects Agency. The search for a mechanism for loading the UCL gateway, once the ARPANET trunking line via SATNET to the London TIP has been removed from service, has led to renewed interest in a gateway loading access path via SATNET directly. This requires a loader/dumper be written for the gateway which implements XNET4, Internet Protocol, Host-SATNET Protocol, and ARPANET VDH Protocol. Clearly, given the number of functions involved, it is essential that the implementation contain only minimal subsets of all protocols involved.

  10. Research on Object Interaction for DIS Based on RT-TCP/IP%基于RT-TCP/IP的DIS系统对象交互研究

    Institute of Scientific and Technical Information of China (English)

    石磊; 杜承烈; 尤涛; 杨红松

    2009-01-01

    DIS system for small-scale distributed simulation system has well performance and low cost. Based on RT TCP/IP network environment, a DIS system object interaction mechanism is designed. According to the characteristics of RT TCP/IP environment, the object interaction PDU has been redesigned, for network trans- mission delays inherent in, the time stamp mechanism and DR compensation model are used for amending the delay; and learning from HLA_RTI in data management on a number of ideas, a data filtering mechanism is de-signed, combining with DIS in DR algorithm, the system' s real-time performance anti reliability are further guaranteed. Simulation examples show that this design has better practicality, and can be used for aircraft and air defense operations, such as demonstration projects simulation. Using RT-DIS system objects interactive tech-nologies based on RT-TCP/IP technology, is has short development time, and advantages of compromising with cost on performance. It is a good small-scale real-time distributed simulation system technology.%DIS系统对于小型分布式仿真系统具有较好的性能与较低的成本.基于RT-TCP/IP网络环境设计了一种DIS系统对象的交互机制,针对RT-TCP/IP环境的特点对对象交互PDU进行了重新设计;针对网络传输的固有延迟,采用时戳机制与DR补偿模型对延迟进行修正;并借鉴HLA-RTI中的关于数据管理的一些思想,设计了数据过滤机制,结合DIS中DR算法,进一步保证了系统的实时性和可靠性.仿真应用实例表明,这种设计具有较好的实用性,可以用于飞机防空作战仿真等演示验证项目.采用了基于RT-TCP/IP技术的RT-DIS系统对象交互技术,具有开发时间短、成本与性能兼顾等优点,是一项良好的小型实时分布式仿真系统技术.

  11. Virtualized Traffic at Metropolitan Scales

    Directory of Open Access Journals (Sweden)

    David eWilkie

    2015-05-01

    Full Text Available Few phenomena are more ubiquitous than traffic, and few are more significant economically, socially, or environmentally. Any virtual reality system, including virtual globes and immersive multi-player worlds that are set in a modern or futuristic setting feature traffic systems. Virtual reality models can also aid in addressing the challenges of real-world traffic systems, the ever-present gridlock and congestion in cities worldwide: traffic engineers and planners can diagnose system instabilities and explore control strategies in virtual worlds reconstructed from available sensor data. To create these systems, road network models need to be created and represented. Traffic needs to be realistically and efficiently simulated. To analyze real-world scenarios, the traffic conditions need to be estimated and reconstructed. To create virtual scenarios, such as simulated cities, traffic needs to be intelligently and efficiently routed.

  12. Web traffic and firm performance

    DEFF Research Database (Denmark)

    Farooq, Omar; Aguenaou, Samir

    2013-01-01

    Does the traffic generated by websites of firms signal anything to stock market participants? Does higher web-traffic translate into availability of more information and therefore lower agency problems? And if answers to above questions are in affirmative, does higher web-traffic traffic translate...... into better firm performance? This paper aims to answer these questions by documenting a positive relationship between the extent of web-traffic and firm performance in the MENA region during the 2010. We argue that higher web-traffic lowers the agency problems in firms by disseminating more information...... to stock market participants. Consequently, lower agency problems translate into better performance. Furthermore, we also show that agency reducing role of web-traffic is more pronounced in regimes where information environment is already bad. For example, our results show stronger impact of web...

  13. Road Traffic Noise

    Science.gov (United States)

    Beckenbauer, Thomas

    Road traffic is the most interfering noise source in developed countries. According to a publication of the European Union (EU) at the end of the twentieth century [1], about 40% of the population in 15 EU member states is exposed to road traffic noise at mean levels exceeding 55 dB(A). Nearly 80 million people, 20% of the population, are exposed to levels exceeding 65 dB(A) during daytime and more than 30% of the population is exposed to levels exceeding 55 dB(A) during night time. Such high noise levels cause health risks and social disorders (aggressiveness, protest, and helplessness), interference of communication and disturbance of sleep; the long- and short-term consequences cause adverse cardiovascular effects, detrimental hormonal responses (stress hormones), and possible disturbance of the human metabolism (nutrition) and the immune system. Even performance at work and school could be impaired.

  14. Dementia and Traffic Accidents

    DEFF Research Database (Denmark)

    Petersen, Jindong Ding; Siersma, Volkert; Nielsen, Connie Thurøe;

    2016-01-01

    BACKGROUND: As a consequence of a rapid growth of an ageing population, more people with dementia are expected on the roads. Little is known about whether these people are at increased risk of road traffic-related accidents. OBJECTIVE: Our study aims to investigate the risk of road traffic......-related accidents for people aged 65 years or older with a diagnosis of dementia in Denmark. METHODS: We will conduct a nationwide population-based cohort study consisting of Danish people aged 65 or older living in Denmark as of January 1, 2008. The cohort is followed for 7 years (2008-2014). Individual's personal...... data are available in Danish registers and can be linked using a unique personal identification number. A person is identified with dementia if the person meets at least one of the following criteria: (1) a diagnosis of the disease in the Danish National Patient Register or in the Danish Psychiatric...

  15. Study on β-TCP Coated Porous Mg as a Bone Tissue Engineering Scaffold Material

    Institute of Scientific and Technical Information of China (English)

    Fang Geng; Lili Tan; Bingchun Zhang; Chunfu Wu; Yonglian He; Jingyu Yang; Ke Yang

    2009-01-01

    Three-dimensional honeycomb-structured magnesium (Mg) scaffolds with interconnected pores of accurately controlled pore size and porosity were fabricated by laser perforation technique. Biodegradable and bioactive β-tricalcium phosphate (β-TCP) coatings were prepared on the porous Mg to further improve its biocompatibility, and the biodegradation mechanism was simply evaluated in vitro. It was found that the mechanical properties of this type of porous Mg significantly depended on its porosity. Elastic modulus and compressive strength similar to human bones could be obtained for the porous Mg with porosity of 42.6%-51%. It was observed that the human osteosarcoma cells (UMR106) were well adhered and proliferated on the surface of the β-TCP coated porous Mg, which indicates that the β-TCP coated porous Mg is promising to be a bone tissue engineering scaffold material.

  16. A GA-based PID active queue management control design for TCP/IP networks

    Science.gov (United States)

    Kuo, H.-H.; Chen, C.-K.; Yan, J.-J.; Liao, T.-L.

    2008-02-01

    In this paper, a genetic algorithm-based (GA-based) proportional-integral-derivative (PID) controller as an active queue manager for Internet routers is proposed to reduce packet loss and improve network utilization in TCP/IP networks. Based on the window-based nonlinear dynamics, the TCP network was modeled as a time-delayed system with a saturated input due to the limitations of packet-dropping probability and the effects of propagation delays in TCP networks. An improved genetic algorithm is employed to derive optimal or near optimal PID control gains such that a performance index of integrated-absolute error (IAE) in terms of the error between the router queue length and the desired queue length is minimized. The performance of the proposed control scheme was evaluated in various network scenarios via a series of numerical simulations. The simulation results confirm that the proposed scheme outperforms other AQM schemes.

  17. Proactive TCP mechanism to improve Handover performance in Mobile Satellite and Terrestrial Networks

    CERN Document Server

    Vinayakray-Jani, Preetida

    2012-01-01

    Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system is having strong resemblance to terrestrial GSM (Global System for Mobile communications) at the upper protocol layers and TCP (Transmission Control Protocol) is one of them. This space segment technology as well as terrestrial technology, is characterized by periodic variations in communication properties and coverage causing the termination of ongoing call as connections of Mobile Nodes (MN) alter stochastically. Although provisions are made to provide efficient communication infrastructure this hybrid space and terrestrial networks must ensure the end-to-end network performance so that MN can move seamlessly among these networks. However from connectivity point of view current TCP performance has not been engineered for mobility events in multi-radio MN. Traditionally, TCP has applied a set of congestion control algorithms (slow-start, congestion avoidance, fast retransmit, fast recovery) to probe the currently available bandwidth on...

  18. An Advance Approach to Evaluate the Performance of the TCP Networks

    Directory of Open Access Journals (Sweden)

    Ibrahiem M.M. El Emary

    2005-01-01

    Full Text Available In this study, we present a new approach for estimating the performance of the TCP network depending on a mathematical formula which converts the conceptual performance parameter to a valuable one. With respect to TCP network performance, we consider the Random Early Detection (RED and RED-Based algorithms where both RED and RED-Based follow the Active Queue Management (AQM approach in TCP networks. Mainly, we make a comprehensive understanding of various network parameters that continually affect the network performance. The main parameters that are used given by: network throughput, link utilization, network average delay, and packet loss rate. Also in this study, we estimate a new parameter reflecting the network performance called Network Quality Parameter (NQP.

  19. Cascade Probability Control to Mitigate Bufferbloat under Multiple Real-World TCP Stacks

    Directory of Open Access Journals (Sweden)

    Hoang-Linh To

    2015-01-01

    Full Text Available Persistently full buffer problem, commonly known as bufferbloat, causes unnecessary additional latency and throughput degradation whenever congestion happens in Internet. Several proposed queue management schemes, with the debloat mission, are almost based on the modification of one-loop feedback control where the instability and bad transient behavior are still big challenges. In this paper, we present a cascade probability control scheme using margin optimal method to address such challenges under different kinds of real-world TCP stacks. Simulation results guarantee the measured round trip time tracking to a low value of delay (e.g., ≈180 ms under TCP Reno, and ≈130 ms under TCP Cubic and ≈50% delay reduction in comparison to current deployed queue management schemes in network devices.

  20. Improved virtual queuing and dynamic EPD techniques for TCP over ATM

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y.; Siu, K.Y.; Ren, W.

    1998-11-01

    It is known that TCP throughput can degrade significantly over UBR service in a congested ATM network, and the early packet discard (EPD) technique has been proposed to improve the performance. However, recent studies show that EPD cannot ensure fairness among competing VCs in a congested network, but the degree of fairness can be improved using various forms of fair buffer allocation techniques. The authors propose an improved scheme that utilizes only a single shared FIFO queue for all VCs and admits simple implementation for high speed ATM networks. The scheme achieves nearly perfect fairness and throughput among multiple TCP connections, comparable to the expensive per-VC queuing technique. Analytical and simulation results are presented to show the validity of this new scheme and significant improvement in performance as compared with existing fair buffer allocation techniques for TCP over ATM.

  1. Physics of Traffic Flow

    Science.gov (United States)

    Davis, L. C.

    2015-03-01

    The Texas A&M Transportation Institute estimated that traffic congestion cost the United States 121 billion in 2011 (the latest data available). The cost is due to wasted time and fuel. In addition to accidents and road construction, factors contributing to congestion include large demand, instability of high-density free flow and selfish behavior of drivers, which produces self-organized traffic bottlenecks. Extensive data collected on instrumented highways in various countries have led to a better understanding of traffic dynamics. From these measurements, Boris Kerner and colleagues developed a new theory called three-phase theory. They identified three major phases of flow observed in the data: free flow, synchronous flow and wide moving jams. The intermediate phase is called synchronous because vehicles in different lanes tend to have similar velocities. This congested phase, characterized by lower velocities yet modestly high throughput, frequently occurs near on-ramps and lane reductions. At present there are only two widely used methods of congestion mitigation: ramp metering and the display of current travel-time information to drivers. To find more effective methods to reduce congestion, researchers perform large-scale simulations using models based on the new theories. An algorithm has been proposed to realize Wardrop equilibria with real-time route information. Such equilibria have equal travel time on alternative routes between a given origin and destination. An active area of current research is the dynamics of connected vehicles, which communicate wirelessly with other vehicles and the surrounding infrastructure. These systems show great promise for improving traffic flow and safety.

  2. Assessing road traffic expression

    OpenAIRE

    Fábio Silva; Cesar Analide; Paulo Novais

    2014-01-01

    Road traffic is a problem which is increasing in cities with large population. Unrelated to this fact the number of portable and wearable devices has also been increasing throughout the population of most countries. With this advent, the capacity to monitor and register data about people habits and locations as well as more complex data such as intensity and strength of movements has created an opportunity to contribute to the general wealth and comfort within these environments. Ambient Inte...

  3. Organic traffic control

    OpenAIRE

    Prothmann, Holger

    2011-01-01

    Modern cities cannot be imagined without traffic lights controlling the road network. To handle the network's changing demands efficiently, the signal plan specification needs to be shifted from the design time to the run-time of a signal system. The generic observer/controller architecture proposed for Organic Computing facilitates this shift. A two-levelled learning mechanism optimises signal plans on-line while a distributed coordination mechanism establishes green waves in the road network.

  4. Untieing the Traffic Knot

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Beijing is working to resolve its longtime transportation problems before the 2008 Olympics One traffic jam after another, annoying horns, endless lines of cars,impatient sighs from passengers on an overcrowded bus, the youstomped-on-my-toe quarreling in the subway train, all have led to the unsurprising result that Beijing scored at the tail end of a survey of 287 cities in the category of transport satisfaction in China’s 2006 Report on the Quality of Urban Life.

  5. Traffic improvement and transportation pollution control in Xiamen

    Energy Technology Data Exchange (ETDEWEB)

    Dongxing Yuan; Zilin, Wu

    1996-12-31

    in this paper, the urban traffic improvement and transportation control in Xiamen are highlighted. Xiamen is a port city and an economical special zone of China. As the economy grows, the transportation is developing dramatically and becoming the key for further economic development. The air quality is threatened by the rapid growth of the vehicles in the city. The most urgent task in improving urban traffic is to establish a sound traffic system. The municipal government takes great effort to improve the traffic condition, as well as to reduce green house gases and protect air environment. Some management and technical measures are carried out. Those management measures are mainly as follows: (1) systematic planning of the city arrangement and city functional division, and integrated planning of the urban roads system, (2) putting great emphasis on tail gas monitoring and management, and (3) establishing optimized utilization of motor vehicles. Those included in the main technical measures are (1) making the roads clear, (2) enlarging traffic capacity, and (3) developing the public transport. The most urgent task in improving urban traffic is to establish a sound traffic system. The city municipal government and Transportation Management Bureau plan to make a series of reforms to improve the urban traffic condition, such as building high quality road around the city, reducing the number of one way roads and replacing gasoline buses with electric buses. An optimized traffic system of Xiamen, taking public transport as the main means, is the key to meet the needs of both traffic improvement and urban transportation pollution control.

  6. The Physics of Traffic

    Science.gov (United States)

    Davis, L. Craig

    2006-03-01

    Congestion in freeway traffic is an example of self-organization in the language of complexity theory. Nonequilibrium, first-order phase transitions from free flow cause complex spatiotemporal patterns. Two distinct phases of congestion are observed in empirical traffic data--wide moving jams and synchronous flow. Wide moving jams are characterized by stopped or slowly moving vehicles within the jammed region, which widens and moves upstream at 15-20 km/h. Above a critical density of vehicles, a sudden decrease in the velocity of a lead vehicle can initiate a transition from metastable states to this phase. Human behaviors, especially delayed reactions, are implicated in the formation of jams. The synchronous flow phase results from a bottleneck such as an on-ramp. Thus, in contrast to a jam, the downstream front is pinned at a fixed location. The name of the phase comes from the equilibration (or synchronization) of speed and flow rate across all lanes caused by frequent vehicle lane changes. Synchronous flow occurs when the mainline flow and the rate of merging from an on-ramp are sufficiently large. Large-scale simulations using car-following models reproduce the physical phenomena occurring in traffic and suggest methods to improve flow and mediate congestion.

  7. Assessing Road Traffic Expression

    Directory of Open Access Journals (Sweden)

    Fábio Silva

    2014-12-01

    Full Text Available Road traffic is a problem which is increasing in cities with large population. Unrelated to this fact the number of portable and wearable devices has also been increasing throughout the population of most countries. With this advent, the capacity to monitor and register data about people habits and locations as well as more complex data such as intensity and strength of movements has created an opportunity to contribute to the general wealth and comfort within these environments. Ambient Intelligence and Intelligent Decision Making processes can benefit from the knowledge gathered by these devices to improve decisions on everyday tasks such as deciding navigation routes by car, bicycle or other means of transportation and avoiding route perils. The concept of computational sustainability may also be applied to this problem. Current applications in this area demonstrate the usefulness of real time system that inform the user of certain conditions in the surrounding area. On the other hand, the approach presented in this work aims to describe models and approaches to automatically identify current states of traffic inside cities and use methods from computer science to improve overall comfort and the sustainability of road traffic both with the user and the environment in mind. Such objective is delivered by analyzing real time contributions from those mobile ubiquitous devices to identifying problematic situations and areas under a defined criteria that have significant influence towards a sustainable use of the road transport infrastructure.

  8. Geometrical versus Random β-TCP Scaffolds: Exploring the Effects on Schwann Cell Growth and Behavior

    Science.gov (United States)

    Czisch, Christopher; Witek, Lukasz; Shi, Yang; Smay, Jim; Plant, Giles W.; Yang, Yunzhi

    2015-01-01

    Numerous studies have demonstrated that Schwann cells (SCs) play a role in nerve regeneration; however, their role in innervating a bioceramic scaffold for potential application in bone regeneration is still unknown. Here we report the cell growth and functional behavior of SCs on β-tricalcium phosphate (β-TCP) scaffolds arranged in 3D printed-lattice (P-β-TCP) and randomly-porous, template-casted (N-β-TCP) structures. Our results indicate that SCs proliferated well and expressed the phenotypic markers p75LNGFR and the S100-β subunit of SCs as well as displayed growth morphology on both scaffolds, but SCs showed spindle-shaped morphology with a significant degree of SCs alignment on the P-β-TCP scaffolds, seen to a lesser degree in the N-β-TCP scaffold. The gene expressions of nerve growth factor (β-ngf), neutrophin–3 (nt–3), platelet-derived growth factor (pdgf-bb), and vascular endothelial growth factor (vegf-a) were higher at day 7 than at day 14. While no significant differences in protein secretion were measured between these last two time points, the scaffolds promoted the protein secretion at day 3 compared to that on the cell culture plates. These results together imply that the β-TCP scaffolds can support SC cell growth and that the 3D-printed scaffold appeared to significantly promote the alignment of SCs along the struts. Further studies are needed to investigate the early and late stage relationship between gene expression and protein secretion of SCs on the scaffolds with refined characteristics, thus better exploring the potential of SCs to support vascularization and innervation in synthetic bone grafts. PMID:26444999

  9. Incorporation of RANKL promotes osteoclast formation and osteoclast activity on β-TCP ceramics.

    Science.gov (United States)

    Choy, John; Albers, Christoph E; Siebenrock, Klaus A; Dolder, Silvia; Hofstetter, Wilhelm; Klenke, Frank M

    2014-12-01

    β-Tricalcium phosphate (β-TCP) ceramics are approved for the repair of osseous defects. In large defects, however, the substitution of the material by authentic bone is inadequate to provide sufficient long-term mechanical stability. We aimed to develop composites of β-TCP ceramics and receptor activator of nuclear factor κ-B ligand (RANKL) to enhance the formation of osteoclasts and promote cell mediated calcium phosphate resorption. RANKL was adsorbed superficially onto β-TCP ceramics or incorporated into a crystalline layer of calcium phosphate by the use of a co-precipitation technique. Murine osteoclast precursors were seeded onto the ceramics. After 15 days, the formation of osteoclasts was quantified cytologically and colorimetrically with tartrate-resistant acidic phosphatase (TRAP) staining and TRAP activity measurements, respectively. Additionally, the expression of transcripts encoding the osteoclast gene products cathepsin K, calcitonin receptor, and of the sodium/hydrogen exchanger NHA2 were quantified by real-time PCR. The activity of newly formed osteoclasts was evaluated by means of a calcium phosphate resorption assay. Superficially adsorbed RANKL did not induce the formation of osteoclasts on β-TCP ceramics. When co-precipitated onto β-TCP ceramics RANKL supported the formation of mature osteoclasts. The development of osteoclast lineage cells was further confirmed by the increased expression of cathepsin K, calcitonin receptor, and NHA2. Incorporated RANKL stimulated the cells to resorb crystalline calcium phosphate. Our in vitro study shows that RANKL incorporated into β-TCP ceramics induces the formation of active, resorbing osteoclasts on the material surface. Once formed, osteoclasts mediate the release of RANKL thereby perpetuating their differentiation and activation. In vivo, the stimulation of osteoclast-mediated resorption may contribute to a coordinated sequence of material resorption and bone formation. Further in vivo studies

  10. Genome-Wide Identification, Characterization and Expression Analysis of the TCP Gene Family in Prunus mume

    Science.gov (United States)

    Zhou, Yuzhen; Xu, Zongda; Zhao, Kai; Yang, Weiru; Cheng, Tangren; Wang, Jia; Zhang, Qixiang

    2016-01-01

    TCP proteins, belonging to a plant-specific transcription factors family, are known to have great functions in plant development, especially flower and leaf development. However, there is little information about this gene family in Prunus mume, which is widely cultivated in China as an ornamental and fruit tree. Here a genome-wide analysis of TCP genes was performed to explore their evolution in P. mume. Nineteen PmTCPs were identified and three of them contained putative miR319 target sites. Phylogenetic and comprehensive bioinformatics analyses of these genes revealed that different types of TCP genes had undergone different evolutionary processes and the genes in the same clade had similar chromosomal location, gene structure, and conserved domains. Expression analysis of these PmTCPs indicated that there were diverse expression patterns among different clades. Most TCP genes were predominantly expressed in flower, leaf, and stem, and showed high expression levels in the different stages of flower bud differentiation, especially in petal formation stage and gametophyte development. Genes in TCP-P subfamily had main roles in both flower development and gametophyte development. The CIN genes in double petal cultivars might have key roles in the formation of petal, while they were correlated with gametophyte development in the single petal cultivar. The CYC/TB1 type genes were highly detected in the formation of petal and pistil. The less-complex flower types of P. mume might result from the fact that there were only two CYC type genes present in P. mume and a lack of CYC2 genes to control the identity of flower types. These results lay the foundation for further study on the functions of TCP genes during flower development. PMID:27630648

  11. On differences in radiosensitivity estimation: TCP experiments versus survival curves. A theoretical study

    Science.gov (United States)

    Stavrev, Pavel; Stavreva, Nadejda; Ruggieri, Ruggero; Nahum, Alan

    2015-08-01

    We have compared two methods of estimating the cellular radiosensitivity of a heterogeneous tumour, namely, via cell-survival and via tumour control probability (TCP) pseudo-experiments. It is assumed that there exists intra-tumour variability in radiosensitivity and that the tumour consists predominantly of radiosensitive cells and a small number of radio-resistant cells. Using a multi-component, linear-quadratic (LQ) model of cell kill, a pseudo-experimental cell-survival versus dose curve is derived. This curve is then fitted with a mono-component LQ model describing the response of a homogeneous cell population. For the assumed variation in radiosensitivity it is shown that the composite pseudo-experimental survival curve is well approximated by the survival curve of cells with uniform radiosensitivity. For the same initial cell radiosensitivity distribution several pseudo-experimental TCP curves are simulated corresponding to different fractionation regimes. The TCP model used accounts for clonogen proliferation during a fractionated treatment. The set of simulated TCP curves is then fitted with a mono-component TCP model. As in the cell survival experiment the fit with a mono-component model assuming uniform radiosensitivity is shown to be highly acceptable. However, the best-fit values of cellular radiosensitivity produced via the two methods are very different. The cell-survival pseudo-experiment yields a high radiosensitivity value, while the TCP pseudo-experiment shows that the dose-response is dominated by the most resistant sub-population in the tumour, even when this is just a small fraction of the total.

  12. Determination of physical properties for β-TCP + chitosan biomaterial obtained on metallic 316L substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mina, A. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Tecno-Academia ASTIN SENA Reginal Valle (Colombia); Castaño, A. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Caicedo, J.C., E-mail: julio.cesar.caicedo@correo.univalle.edu.co [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia); Caicedo, H.H. [Biologics Research, Biotechnology Center of Excellence, Janssen R& D, LLC, Pharmaceutical Companies of Johnson & Johnson, Spring House, PA 19477 (United States); National Biotechnology & Pharmaceutical Association, Chicago, IL 60606 (United States); Aguilar, Y. [Tribology, Powder Metallurgy and Processing of Solid Recycled Research Group, Universidad del Valle, Cali (Colombia)

    2015-06-15

    Material surface modification, particularly the deposition of special coatings on the surface of surgical implants, is extensively used in bone tissue engineering applications. β-Tricalcium phosphate/Chitosan (β-TCP/Ch) coatings were deposited on 316L stainless steel (316L SS) substrates by a cathodic electro-deposition technique at different coating compositions. The crystal lattice arrangements were analyzed by X-Ray diffraction (XRD), and the results indicated that the crystallographic structure of β-TCP was affected by the inclusion of the chitosan content. The changes in the surface morphology as a function of increasing chitosan in the coatings via scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that root-mean square values of the β-TCP/Ch coatings decreased by further increasing chitosan percentage. The elastic–plastic characteristics of the coatings were determined by conducting nanoindentation test, indicating that increase of chitosan percentage is directly related to increase of hardness and elastic modulus of the β-TCP/Ch coatings. Tribological characterization was performed by scratch test and pin-on-disk test to analyze the changes in the surface wear of β-TCP/Ch coatings. Finally, the results indicated an improvement in the mechanical and tribological properties of the β-TCP/Ch coatings as a function of increasing of the chitosan percentage. This new class of coatings, comprising the bioactive components, is expected not only to enhance the bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. - Highlights: • Superficial phenomenon that occurs in tribological surface of β-tricalcium phosphate-chitosan coatings. • Improvement on surface mechanical properties of ceramic-polymeric and response to surface tribological damage. • β-tricalcium phosphate-chitosan coatings that offer highest performance in the biomedical devices.

  13. Genome-Wide Identification, Characterization and Expression Analysis of the TCP Gene Family in Prunus mume.

    Science.gov (United States)

    Zhou, Yuzhen; Xu, Zongda; Zhao, Kai; Yang, Weiru; Cheng, Tangren; Wang, Jia; Zhang, Qixiang

    2016-01-01

    TCP proteins, belonging to a plant-specific transcription factors family, are known to have great functions in plant development, especially flower and leaf development. However, there is little information about this gene family in Prunus mume, which is widely cultivated in China as an ornamental and fruit tree. Here a genome-wide analysis of TCP genes was performed to explore their evolution in P. mume. Nineteen PmTCPs were identified and three of them contained putative miR319 target sites. Phylogenetic and comprehensive bioinformatics analyses of these genes revealed that different types of TCP genes had undergone different evolutionary processes and the genes in the same clade had similar chromosomal location, gene structure, and conserved domains. Expression analysis of these PmTCPs indicated that there were diverse expression patterns among different clades. Most TCP genes were predominantly expressed in flower, leaf, and stem, and showed high expression levels in the different stages of flower bud differentiation, especially in petal formation stage and gametophyte development. Genes in TCP-P subfamily had main roles in both flower development and gametophyte development. The CIN genes in double petal cultivars might have key roles in the formation of petal, while they were correlated with gametophyte development in the single petal cultivar. The CYC/TB1 type genes were highly detected in the formation of petal and pistil. The less-complex flower types of P. mume might result from the fact that there were only two CYC type genes present in P. mume and a lack of CYC2 genes to control the identity of flower types. These results lay the foundation for further study on the functions of TCP genes during flower development. PMID:27630648

  14. Geometrical versus Random β-TCP Scaffolds: Exploring the Effects on Schwann Cell Growth and Behavior.

    Directory of Open Access Journals (Sweden)

    Lauren Sweet

    Full Text Available Numerous studies have demonstrated that Schwann cells (SCs play a role in nerve regeneration; however, their role in innervating a bioceramic scaffold for potential application in bone regeneration is still unknown. Here we report the cell growth and functional behavior of SCs on β-tricalcium phosphate (β-TCP scaffolds arranged in 3D printed-lattice (P-β-TCP and randomly-porous, template-casted (N-β-TCP structures. Our results indicate that SCs proliferated well and expressed the phenotypic markers p75LNGFR and the S100-β subunit of SCs as well as displayed growth morphology on both scaffolds, but SCs showed spindle-shaped morphology with a significant degree of SCs alignment on the P-β-TCP scaffolds, seen to a lesser degree in the N-β-TCP scaffold. The gene expressions of nerve growth factor (β-ngf, neutrophin-3 (nt-3, platelet-derived growth factor (pdgf-bb, and vascular endothelial growth factor (vegf-a were higher at day 7 than at day 14. While no significant differences in protein secretion were measured between these last two time points, the scaffolds promoted the protein secretion at day 3 compared to that on the cell culture plates. These results together imply that the β-TCP scaffolds can support SC cell growth and that the 3D-printed scaffold appeared to significantly promote the alignment of SCs along the struts. Further studies are needed to investigate the early and late stage relationship between gene expression and protein secretion of SCs on the scaffolds with refined characteristics, thus better exploring the potential of SCs to support vascularization and innervation in synthetic bone grafts.

  15. Determination of physical properties for β-TCP + chitosan biomaterial obtained on metallic 316L substrates

    International Nuclear Information System (INIS)

    Material surface modification, particularly the deposition of special coatings on the surface of surgical implants, is extensively used in bone tissue engineering applications. β-Tricalcium phosphate/Chitosan (β-TCP/Ch) coatings were deposited on 316L stainless steel (316L SS) substrates by a cathodic electro-deposition technique at different coating compositions. The crystal lattice arrangements were analyzed by X-Ray diffraction (XRD), and the results indicated that the crystallographic structure of β-TCP was affected by the inclusion of the chitosan content. The changes in the surface morphology as a function of increasing chitosan in the coatings via scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that root-mean square values of the β-TCP/Ch coatings decreased by further increasing chitosan percentage. The elastic–plastic characteristics of the coatings were determined by conducting nanoindentation test, indicating that increase of chitosan percentage is directly related to increase of hardness and elastic modulus of the β-TCP/Ch coatings. Tribological characterization was performed by scratch test and pin-on-disk test to analyze the changes in the surface wear of β-TCP/Ch coatings. Finally, the results indicated an improvement in the mechanical and tribological properties of the β-TCP/Ch coatings as a function of increasing of the chitosan percentage. This new class of coatings, comprising the bioactive components, is expected not only to enhance the bioactivity and biocompatibility, but also to protect the surface of metallic implants against wear and corrosion. - Highlights: • Superficial phenomenon that occurs in tribological surface of β-tricalcium phosphate-chitosan coatings. • Improvement on surface mechanical properties of ceramic-polymeric and response to surface tribological damage. • β-tricalcium phosphate-chitosan coatings that offer highest performance in the biomedical devices

  16. Trace Analysis of Driver Behavior on Traffic Violator by Using Big Data (Traffic Program) in Korea

    OpenAIRE

    Lee, Jonghak

    2016-01-01

    This study aims to prove the effectiveness of traffic safety education program for traffic violators. Traffic violators who finished the traffic safety education programs were tracked down. In order to analyze the effectiveness of traffic safety education program, traffic violator’s data during ten-year period were used. This study analyzed how traffic violators changed their attitudes about traffic law abidance. Also predicted social benefits from traffic safety education program...

  17. Application of Azolla for 2, 4, 6-Trichlorophenol (TCP) Removal from Aqueous Solutions

    OpenAIRE

    Mohammad Ali Zazouli; Davoud Balarak; Yusef Mahdavi

    2013-01-01

    Background & Aims of the Study: The 2, 4, 6-Trichlorophenol (TCP) is a phenolic compound which it can produce adverse effects on human and environment. Therefore, the removal of these compounds is necessary. The aim of this study is the investigation of TCP removal by using Azolla filiculoides biomass. Materials & Methods: The Azolla biomass was dried in the sunlight, and then it was crushed and sieved to particle sizes in range of 1-2 mm. Next treated with 0.1M HCl for a period of 5h....

  18. Modbus/TCP-asiakassovellus Windows Phone 7.1 -ympäristöön

    OpenAIRE

    Tuomio, Petri

    2013-01-01

    Opinnäytetyössä kuvataan Windows Phone–alustalle ja sen käyttöjärjestelmän versiolle 7.1 kehitettävän Modbus/TCP asiakassovelluksen toteutusta. Sovellus mahdollistaa Modbus palvelimen input ja holding rekistereiden sisältämien lukuarvojen lukemisen puhelimen näytölle sekä arvojen muokkaamisen ja kirjoittamisen holding rekistereihin käyttäen TCP-yhteyttä asiakassovelluksen ja palvelimen välillä. Sovellus on tarkoitettu käytettäväksi pienimuotoiseen palvelinlaitteen tietojen selaamiseen ja/tai ...

  19. A New Approach for Performance Evaluation of TCP over Interference-Limited Wireless Channels

    Institute of Scientific and Technical Information of China (English)

    LUO Rui; FAN Pingzhi

    2003-01-01

    A new metric for performance evaluation of transport control protocol(TCP) over wireless channels based on the interference-limited characteristics of code division multiple address(CDMA) system is proposed. According to the new metric, the performance of TCP over CDMA correlated channel for different protocol parameters and different versions is investigated. The results show that appropriate selection of protocol parameters and packet error rate(PER) operation point can improve significantly the capacity of packet-switched CDMA-based network.

  20. CER/TER - The New Metric for TCP Connection Robustness Evaluation and Comparison

    Directory of Open Access Journals (Sweden)

    Ondrej Vondrous

    2015-01-01

    Full Text Available This article presents new metric for TCP connection robustness evaluation and comparison. This metric is focused on TCP connection and transmission continuity rather then on maximal throughput or minimal RTT. This metric is developed especially for evaluation of narrow band networks. That is why it is very convenient to use this metric for networks such as Internet of Things networks or industrial sensor networks. Our metric is based on observing if connections or transmissions are successfully finished or not. It is possible to optimize this metric for specific situations. This metric can be used in both the real networks and in discrete simulation environments.

  1. YottaYotta announces new world record set for TCP disk-to-disk bulk transfer

    CERN Multimedia

    2002-01-01

    The Yottabyte NetStorage(TM) Company, today announced a new world record for TCP disk-to-disk data transfer using the company's NetStorager(R) System. The record-breaking demonstration transferred 5 terabytes of data between Chicago, Il. to Vancouver, BC and Ottawa, ON, at a sustained average throughput of 11.1 gigabits per second. Peak throughput exceeded 11.6 gigabits per second, more than 15-times faster than previous records for TCP transfer from disk-to-disk (1 page).

  2. 光突发交换网络中TCP Reno的性能分析%Performance Analysis of TCP Reno in Optical Burst Switching

    Institute of Scientific and Technical Information of China (English)

    刘建平; 文爱军; 刘增基; 靖杰

    2007-01-01

    该文在分析光突发交换(OBS)网络对TCP性能影响的基础上,研究了单个突发所包含的属于同一TCP/IP连接的分组数对TCP Reno吞吐量性能的影响,得到了一个吞吐量与突发丢失率、单个突发所包含分组数以及往返时延(RTT)的闭合表达式;并通过仿真验证了分析的正确性;分析和仿真结果表明,在接入链路带宽较大时,突发所包含的分组数存在一个最佳值,使TCP吞吐量达到最大.

  3. 非饱和状态下TCP/UDP混合流的EDCA模型分析%EDCA Model of TCP/UDP Flows Based on Non-saturation

    Institute of Scientific and Technical Information of China (English)

    张南; 肖扬

    2011-01-01

    IEEE 802. 11e EDCA mechanism permits using CFB (Contention Free Burst) ,which will control the media in a whole TXOP. So it can save some time to occupy the channel and improve the QoS. But few papers think over TXOP in non-saturation. This paper proposed an easy analysis model of TCP/UDP heterogeneous flows appear in non-saturated condition based on IEEE 802. lle EDCA mechanism, the model thinks over CFB, the simulation results indicate that the model is valid on forecasting the EDCA mechanism of mixed flows, and the interaction of the mixed TCP/UDP flows appear when they share the same channel.%IEEE 802.11e EDCA机制允许采用CFB(竞争空闲突发)模式,使站点在整个TXOP中都能对媒体进行控制,进而省去部分竞争信道的时间,提高服务质量,然而很少有文献考虑动态TXOP非饱和状态模型.提出了非饱和状态下TCP/UDP混合流的简单分析模型,该模型考虑了提高服务质量的竞争自由脉冲(CFB)模式.仿真结果表明,该模型能有效地预测混合流的EDCA机制性能,并反映出混合TCP/UDP流共用信道时会产生相互影响.

  4. Implementation Analysis of TCP IP Protocol Stack in Linux and FreeBSD%TCP/IP协议栈在Limux与FreeBSD中的实现分析

    Institute of Scientific and Technical Information of China (English)

    胡影; 蒋年德

    2006-01-01

    本文分析了Linux和freeBSD两个操作系统的部分网络实现代码,并通过研究一个完整的1/0操作流程,遍历操作系统中TCP/IP协议栈的内核实现,最后对相关实现作出了相应的评价.

  5. TCP/IP协议栈在Linux与FreeBSD中的实现分析%the Compare of TCP Protocol Stack in Linux and FreeBSD

    Institute of Scientific and Technical Information of China (English)

    胡影; 蒋年德

    2006-01-01

    本文分析了Linux和FreeBSD两个操作系统的部分网络实现代码,并通过研究一个完整的I/O操作流程.遍历操作系统中TCP/IP协议栈的内核实现,最后对相关实现作出了相应的评价.

  6. TCP/IP Protocol and Video Transfers on IP Multicast%TCP/IP协议和IP组播的视频传输

    Institute of Scientific and Technical Information of China (English)

    沈祖冀

    2001-01-01

    介绍介绍TCP/IP协议的有关内容。介绍IP组播,提出一种用IP组播的传输视频的解决方案和实现实例,此方案兼容现在的网络,有良好的视频信号传输效果。

  7. Robust and reactive traffic engineering for dynamic traffic demands

    OpenAIRE

    Casas Hernandez, Pedro; Fillatre, Lionel; Vaton, Sandrine

    2008-01-01

    Traffic engineering (TE) has become a challenging mechanism for network management and resources optimization due to uncertain and difficult to predict traffic patterns. Recent works have proposed robust optimization techniques to cope with uncertain traffic, computing a stable routing configuration that is immune to demand variations within certain uncertainty set. However, using a single routing configuration for longtime periods can be highly inefficient. Even more, the presence of abnorma...

  8. Dividing the Traffic Matrix to Approach Optimal Traffic Engineering

    OpenAIRE

    Balon, Simon; Leduc, Guy

    2006-01-01

    In this paper we propose a new method to approach optimal Traffic Engineering routing. The method consists of dividing the traffic matrix into $N$ sub-matrices, called strata, and route each of these independently. We propose two different implementations of our method in routers. Our method can also be used to compute a very precise approximation of the optimal value of a given objective function for comparison to heuristic Traffic Engineering algorithms. For this application, our algorithm ...

  9. Traffic Data and Their Implications for Consistent Traffic Flow Modeling

    OpenAIRE

    Helbing, Dirk

    1998-01-01

    The paper analyzes traffic data of the Dutch freeway A9 with respect to certain aspects which are relevant for traffic flow modeling as well as the calibration of model parameters and functions. Apart from the dynamic velocity distribution, the density-dependence and the temporal evolution of various, partly lane-specific quantities is investigated. The results are well compatible with recent macroscopic traffic flow models which have been derived from the dynamics of driver-vehicle units. Th...

  10. Evaluation of Traffic Management Measures on Road Traffic Noise

    OpenAIRE

    Bhaskar, A.; Chung, E; Dumont, A.-G.

    2006-01-01

    Road traffic noise affects the quality of life in the areas adjoining the road. The effect of traffic noise on people is wide ranging and may include sleep disturbance and negative impact on work efficiency. To address the problem of traffic noise, it is necessary to estimate the noise level. For this, a number of noise estimation models have been developed which can estimate noise at the receptor points, based on simple configuration of buildings. Howe...

  11. Performance Evaluation of DSDV and AODV Routing Protocols On The Basis Of TCP Variants in WSN and MANET

    Directory of Open Access Journals (Sweden)

    Shivangi Ranawat

    2014-01-01

    Full Text Available Transmission Control Protocol (TCP provides reliability to data transferring in all end-to-end data stream services on the internet. This protocol is utilized by major internet applications. TCP was originally created to handle the problem of network congestion collapse. This paper is prepared on the performance of different TCP variants to identify the best protocol variant for network expansion. In such context, a full comprehensive simulation environment is created for evaluating the comparative performance of TCP variants like TCP NewReno, SACK, FACK, RTCP and Vegas with the routing protocol AODV and DSDV in WSN and MANET. In this paper the overall performance of WSN and MANET is analyzed by comparing on the basis of Energy, End-to-End Delay, Throughput and Packet Delivery Ratio of the network.

  12. Advanced TCP Port Scan and Its Response%TCP端口的高级扫描及其响应

    Institute of Scientific and Technical Information of China (English)

    孙海峰

    2005-01-01

    TCP端口扫描分为TCP Connect()、TCP SYN、TCP ACK、TCP FIN和TCP NULL等扫描.利用TCP头部6个1位标志字段,向目标主机端口发送带特殊标志字段的数据包,分析目标主机响应数据包TCP头部的6个1位标志字段的内容,得目标主机的端口状态.其编程用VC6.0及Winsock原始套接字实现.

  13. Traffic experiment reveals the nature of car-following.

    Directory of Open Access Journals (Sweden)

    Rui Jiang

    Full Text Available As a typical self-driven many-particle system far from equilibrium, traffic flow exhibits diverse fascinating non-equilibrium phenomena, most of which are closely related to traffic flow stability and specifically the growth/dissipation pattern of disturbances. However, the traffic theories have been controversial due to a lack of precise traffic data. We have studied traffic flow from a new perspective by carrying out large-scale car-following experiment on an open road section, which overcomes the intrinsic deficiency of empirical observations. The experiment has shown clearly the nature of car-following, which runs against the traditional traffic flow theory. Simulations show that by removing the fundamental notion in the traditional car-following models and allowing the traffic state to span a two-dimensional region in velocity-spacing plane, the growth pattern of disturbances has changed qualitatively and becomes qualitatively or even quantitatively in consistent with that observed in the experiment.

  14. 瓶颈网络TCP/主动队列管理模型及仿真%TCP/Active Queue Management Model and Simulation for Bottleneck Networks

    Institute of Scientific and Technical Information of China (English)

    曹振臻; 肖扬; 迟彩霞

    2009-01-01

    提出了一种基于离散时间Markov链的时延闭环反馈TCP/AQM(Active Queue Management)模型,并得到其稳态分布.通过以环路时延为单位,将系统时间分割成长度不同的时隙,分析每个时隙内TCP发送端发送窗口模型和瓶颈路由器队列模型.通过结合相邻时隙的参数,提出了TCP/AQM整体分析模型.该模型可以估计路由器的队列平均长度和丢包率、TCP发送端的平均发送窗口值,因此可以用于分析AQM算法性能以及给新算法的设计提供理论支持.通过在Matlab实施该模型与NS2仿真结果作比较,证实了该模型在模拟时延闭环反馈的TCP/RED系统的有效性.

  15. Camouflaging Timing Channels in Web Traffic

    OpenAIRE

    Sellke, Sarah H; Wang, Chih-Chun; Bagchi, Saurabh; Shroff, Ness B.

    2009-01-01

    Web traffic accounts for more than half of Internet traffic today. Camouflaging covert timing channels in Web traffic would be advantageous for concealment. In this paper, we investigate the possibility of disguising network covert timing channels as HTTP traffic to avoid detection. Extensive research has shown that Internet traffic, including HTTP traffic, exhibits self-similarity and long range persistence. Existing covert timing channels that mimic i.i.d. legitimate traffic cannot imitate ...

  16. Lagrangian Multi-Class Traffic State Estimation

    OpenAIRE

    Y. Yuan

    2013-01-01

    Road traffic is important to everybody in the world. People travel and commute everyday. For those who travel by cars (or other types of road vehicles), traffic congestion is a daily experience. One essential goal of traffic researchers is to reduce traffic congestion and to improve the whole traffic system operation and the environment. To achieve this goal, we have to first understand prevailing traffic situations, then perform pro-active traffic control and management. The estimation of tr...

  17. Clinical evaluation of β-TCP in the treatment of lacunar bone defects: A prospective, randomized controlled study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen; Guo, Zheng [Department of Orthopaedics, Xijing hospital, Fourth Military Medical University, Xi' an 710032 (China); Bai, Hua [Department of Toxicology, Faculty of Preventive Medicine, Fourth Military Medical University, Xi' an 710032 (China); Li, Jing; Li, Xiangdong [Department of Orthopaedics, Xijing hospital, Fourth Military Medical University, Xi' an 710032 (China); Chen, Guojing, E-mail: guojing_chen@sohu.com [Department of Orthopaedics, Xijing hospital, Fourth Military Medical University, Xi' an 710032 (China); Lu, Jianxi [Department of Orthopaedics, Shanghai Ninth People' s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 710048 (China)

    2013-05-01

    The aim of this study was to investigate the potential wide application of beta tricalcium phosphate (β-TCP) only for bone defects as compared to allograft. 95 patients with a solitary bone cyst were randomly assigned to the treatment. A new radiographic scoring system was employed to calculate the biodegradation of bone graft and to evaluate the influence of multiple factors. At an average of 28.43 months after surgery, a radiographic semi-quantitative analysis revealed that the degradation rates of β-TCP and the allograft were comparable (p > 0.05). Age, complication, packing methods and granule diameters have a significant influence on β-TCP degradation. The loose packing method and 3–5 mm granule size should be employed in clinical practice. A histological analysis of biopsy showed that β-TCP supported the growth of fibrous tissue, vascular tissue, as well as bone tissue into the implants. The results proved that single β-TCP is an advantageous alternative to allografts for lacunar bone defect repair and would well guide the design and clinical application of the β-TCP. - Highlights: ► Single beta-TCP was used only for bone defect as compared to allograft. ► Beta-TCP shows similar performance as allografts in degradation rates. ► Age, complication, packing methods and granules diameters influence beta-TCP degradation. ► Loose packing method should be employed in clinical practice. ► The degradation of the beta-TCP tends to be better in young patients.

  18. Traffic forecasts ignoring induced demand

    DEFF Research Database (Denmark)

    Næss, Petter; Nicolaisen, Morten Skou; Strand, Arvid

    2012-01-01

    Although the phenomenon of induced traffic has been theorized for more than 60 years and is now widely accepted among transport researchers, the traffic-generating effects of road capacity expansion are still often neglected in transport modelling. Such omission can lead to serious bias...... performance of a proposed road project in Copenhagen with and without short-term induced traffic included in the transport model. The available transport model was not able to include long-term induced traffic resulting from changes in land use and in the level of service of public transport. Even though...... the model calculations included only a part of the induced traffic, the difference in cost-benefit results compared to the model excluding all induced traffic was substantial. The results show lower travel time savings, more adverse environmental impacts and a considerably lower benefitcost ratio when...

  19. KINEMATIC WAVE PROPERTIES OF ANISOTROPIC DYNAMICS MODEL FOR TRAFFIC FLOW

    Institute of Scientific and Technical Information of China (English)

    姜锐; 吴清松; 朱祚金

    2002-01-01

    The analyses of kinematic wave properties of a new dynamics model for traffic flow are carried out. The model does not exhibit the problem that one characteristic speed is always greater than macroscopic traffic speed, and therefore satisfies the requirement that traffic flow is anisotropic. Linear stability analysis shows that the model is stable under certain condition and the condition is obtained. The analyses also indicate that the model has a hierarchy of first-and second-order waves, and allows the existence of both smooth traveling wave and shock wave. However, the model has a distinctive criterion of shock wave compared with other dynamics models, and the distinction makes the model more realistic in dealing with some traffic problems such as wrong-way travel analysis.

  20. Alternate Routing in Tandem Traffic-Groomed Optical Networks

    Directory of Open Access Journals (Sweden)

    Alicia Nicki Washington

    2007-09-01

    Full Text Available Recent advances in telecommunication networks have allowed WDM to emerge as a viable solution to the ever-increasing demands of the Internet. Because these networks carry large amounts of traffic, alternate routing methods are designed in order to allow traffic to be properly re-routed from source to destination in the event of certain events, such as link blocking or failure. In this paper, we consider a tandem traffic-groomed optical network, modeled as a multi-level overflow system, where each level represents a wavelength between adjacent nodes. The queueing network is analyzed using a combination of methods. As will be shown, the decomposition method provides a good approximate analysis of large overflow systems supporting traffic from multiple sources.

  1. Hybrid Traffic Management Model for Multi-Protocol Label Switching Network

    OpenAIRE

    E.R. Naganathan; Rajagopalan, S.

    2011-01-01

    Problem statement: MPLS is a highly scalable, protocol agnostic and data-carrying mechanism. Traffic engineering is the major research area in MPLS due to the emerging requirements of MPLS and the internet usage. A major objective of traffic engineering is to minimize or eliminate high-loss situations. Another goal of traffic engineering is to balance the Quality of Service (QoS) against the cost of operating and maintaining the network. Approach: This study proposes a hybrid model for effect...

  2. Interdomain traffic engineering with BGP

    OpenAIRE

    Quoitin, Bruno; Uhlig, Steve; Pelsser, Cristel; Swinnen, Louis; Bonaventure, Olivier

    2003-01-01

    Traffic engineering is performed by means of a set of techniques that can be used to better control the flow of packets inside an IP network We discuss the utilization of these techniques across interdomain boundaries in the global Internet. We first analyze the characteristics of interdomain traffic on the basis of measurements from three different Internet service providers and show that a small number of sources are responsible for a large fraction of the traffic. Across interdomain bounda...

  3. Framework for Traffic Congestion Management

    OpenAIRE

    Mahmud Hassan TALUKDAR

    2013-01-01

    Traffic Congestion is one of many serious global problems in all great cities resulted from rapid urbanization which always exert negative externalities upon society. The solution of traffic congestion is highly geocentric and due to its heterogeneous nature, curbing congestion is one of the hard tasks for transport planners. It is not possible to suggest unique traffic congestion management framework which could be absolutely applied for every great cities. Conversely, it is quite feasible t...

  4. Traffic noise and cardiovascular disease

    OpenAIRE

    Selander, Jenny

    2010-01-01

    Traffic noise is an increasing problem in urban areas worldwide, but health effects in relation to traffic noise exposure are not well understood. Several studies show that noise may give rise to acute stress reactions, possibly leading to cardiovascular effects, but the evidence is limited on cardiovascular risks associated with traffic noise exposure. Cardiovascular effects have been indicated for other environmental stressors such as occupational noise exposure and job ...

  5. Estimating Emissions from Railway Traffic

    DEFF Research Database (Denmark)

    Jørgensen, Morten W.; Sorenson, Spencer C.

    1998-01-01

    Several parameters of importance for estimating emissions from railway traffic are discussed, and typical results presented. Typical emissions factors from diesel engines and electrical power generation are presented, and the effect of differences in national electrical generation sources...... illustrated as well as the degree of electrification for different countries. Traffic parameters such as passenger occupancy rates, per capita freight and passenger traffic are presented for European conditions. The relationship between average train speed and distance between stops is shown for a variety...

  6. Road traffic injuries

    Institute of Scientific and Technical Information of China (English)

    WANG Zheng-guo 王正国

    2003-01-01

    @@ The appearance of cars has raised materialistic civilization and living standard to an unprecedented level. Today, it is hard to imagine how we human beings can live without cars.Yet, motor vehicles can cause a great number of deaths and injuries as well as considerable economic losses, which have constituted the global burden. Understanding of the occurrence and development of road traffic injuries will contribute to the prevention and control of crash and to the implementation of "everybody has the right to enjoy health" proposed by WHO.

  7. A Modified Efficient Traffic Scheduling Algorithm for Routing in Optical WDM Mesh Networks

    Science.gov (United States)

    Kavitha, T.; Rajamani, V.

    2013-09-01

    This paper is proposing an efficient traffic scheduling for routing in optical networks supported by Wavelength Division Multiplexing (WDM). Normally the traffic is routed through the primary path or back-up path towards the destination. In order to meet the transmission of higher data rates, the path of the WDM should be capable of carrying the traffic without any failure. Whenever the transmission through primary or backup path fails due to excessive overhead or network failure or congestion or excessive load, existing router mechanisms are not scheduling the traffic in an effective manner. This paper deals with an efficient traffic scheduling algorithm which effectively routes the traffic using multipath technique that satisfies the optical constraints. The whole procedure of routing algorithm is separated into two phases: the connection node establishment phase and multipath transmission from the connection node to destination phase. The connection node is selected on the basis of load and current traffic carrying capacity of that node. Then the traffic is routed to the destination using multiple paths. The proposed method tries to minimize the blocking probability of 70% compared to the existing Resource Efficiency Factor (REF) algorithm and also increase the throughput of 30% and better channel utilization of 23% based on data rate and 20% based on traffic time interval. Hence, the proposed algorithm is effectively routes the traffic within the network.

  8. Road traffic noise and stroke

    DEFF Research Database (Denmark)

    Sørensen, Mette; Hvidberg, Martin; Andersen, Zorana J;

    2011-01-01

    Epidemiological studies suggest that long-term exposure to road traffic noise increases the risk of cardiovascular disorders. The aim of this study was to investigate the relation between exposure to road traffic noise and risk for stroke, which has not been studied before.......Epidemiological studies suggest that long-term exposure to road traffic noise increases the risk of cardiovascular disorders. The aim of this study was to investigate the relation between exposure to road traffic noise and risk for stroke, which has not been studied before....

  9. A Simulation Study on the Throughput Performance of TCP over Wireless Fading Channel

    Institute of Scientific and Technical Information of China (English)

    YAO Ling; JI Hong; YUE Guang-xin

    2004-01-01

    Using Markov model and the network simulator-NS, this paper studies the TCP throughput performance in wireless fading channel where the packets losses are always caused by high and burst errors. The results show that the burstiness in packet errors caused by slow multipath fading benefits Reno compared to i.i.d packet errors.

  10. Delay Prediction for Real-Time Video Adaptive Transmisson over TCP

    Directory of Open Access Journals (Sweden)

    Yonghua Xiong

    2010-06-01

    Full Text Available Real-time multimedia streaming applications are increasingly using TCP instead of UCP as underlying transport protocol, however the great end-to-end delays are the major factor to influence the quality of streaming across the Internet using TCP. In this paper, we point the requirement for transmitting real-time video with acceptable playing performance via TCP and present a stochastic prediction model which can predict the sending-delays of video frames.  Based on the prediction model, we propose a real-time video adaptive transmission scheme which can dynamically adjust video frame rate and playout buffer size according to available network bandwidth. The scheme does not require any modifications to the network infrastructure or TCP protocol stack and only wants to measure some parameters including video frame size, loss ratio, congestion windows size, RTT and RTO time before video frames are sent. The performance of proposed prediction model and adaptive scheme are evaluated through extensive simulations using the NS-2 simulator.

  11. Performance of TCP-friendly streaming sessions in the presence of heavy-tailed elastic flows

    NARCIS (Netherlands)

    Bekker, R.; Borst, S.C.; Núñez Queija, R.

    2005-01-01

    We consider a fixed number of streaming sessions which share a bottleneck link with a dynamic population of elastic flows. Motivated by extensive measurement studies, we assume that the sizes of the elastic flows exhibit heavy-tailed characteristics. The elastic flows are TCP-controlled, while the t

  12. Surface biofunctionalization of β-TCP blocks using aptamer 74 for bone tissue engineering.

    Science.gov (United States)

    Ardjomandi, N; Huth, J; Stamov, D R; Henrich, A; Klein, C; Wendel, H-P; Reinert, S; Alexander, D

    2016-10-01

    Successful bone regeneration following oral and maxillofacial surgeries depends on efficient functionalization strategies that allow the recruitment of osteogenic progenitor cells at the tissue/implant interface. We have previously identified aptamer 74, which exhibited a binding affinity for osteogenically induced jaw periosteal cells (JPCs). In the present study, this aptamer was used for the surface biofunctionalization of β-tricalcium phosphate (β-TCP) blocks. Atomic force microscopy (AFM) measurements showed increased binding activity of aptamer 74 towards osteogenically induced JPCs compared to untreated controls. The immobilization efficiency of aptamer 74 was analyzed using the QuantiFluor ssDNA assay for 2D surfaces and by amino acid analysis for 3D β-TCP constructs. Following the successful immobilization of aptamer 74 in 2D culture wells and on 3D constructs, in vitro assays showed no significant differences in cell proliferation compared to unmodified surfaces. Interestingly, JPC mineralization was significantly higher on the 2D surfaces and higher cell adhesion was detected on the 3D constructs with immobilized aptamer. Herein, we report an established, biocompatible β-TCP matrix with surface immobilization of aptamer 74, which enhances properties such as cell adhesion on 3D constructs and mineralization on 2D surfaces. Further studies need to be performed to improve the immobilization efficiency and to develop a suitable approach for JPC mineralization growing within 3D β-TCP constructs. PMID:27287122

  13. Specific surface area effect on adsorption of chlorpyrifos and TCP by soils and modeling

    Science.gov (United States)

    The adsorption of chlorpyrifos and TCP (3,5,6, trichloro-2-pyridinol) was determined in four soils (Mollisol, Inceptisol, Entisol, Alfisol) having different specific surface areas (19–84 m2/g) but rather similar organic matter content (2.4–3.5%). Adsorption isotherms were derived from batch equilibr...

  14. Securing TCP/IP and Dial-up Access to Administrative Data.

    Science.gov (United States)

    Conrad, L. Dean

    1992-01-01

    This article describes Arizona State University's solution to security risk inherent in general access systems such as TCP/IP (Transmission Control Protocol/INTERNET Protocol). Advantages and disadvantages of various options are compared, and the process of selecting a log-on authentication approach involving generation of a different password at…

  15. Improving TCP Performance over Wireless Ad Hoc Networks with Busy Tone Assisted Scheme

    Directory of Open Access Journals (Sweden)

    Cai Lin

    2006-01-01

    Full Text Available It is well known that transmission control protocol (TCP performance degrades severely in IEEE 802.11-based wireless ad hoc networks. We first identify two critical issues leading to the TCP performance degradation: (1 unreliable broadcast, since broadcast frames are transmitted without the request-to-send and clear-to-send (RTS/CTS dialog and Data/ACK handshake, so they are vulnerable to the hidden terminal problem; and (2 false link failure which occurs when a node cannot successfully transmit data temporarily due to medium contention. We then propose a scheme to use a narrow-bandwidth, out-of-band busy tone channel to make reservation for broadcast and link error detection frames only. The proposed scheme is simple and power efficient, because only the sender needs to transmit two short messages in the busy tone channel before sending broadcast or link error detection frames in the data channel. Analytical results show that the proposed scheme can dramatically reduce the collision probability of broadcast and link error detection frames. Extensive simulations with different network topologies further demonstrate that the proposed scheme can improve TCP throughput by 23% to 150%, depending on user mobility, and effectively enhance both short-term and long-term fairness among coexisting TCP flows in multihop wireless ad hoc networks.

  16. ComboCoding: Combined intra-/inter-flow network coding for TCP over disruptive MANETs

    Directory of Open Access Journals (Sweden)

    Chien-Chia Chen

    2011-07-01

    Full Text Available TCP over wireless networks is challenging due to random losses and ACK interference. Although network coding schemes have been proposed to improve TCP robustness against extreme random losses, a critical problem still remains of DATA–ACK interference. To address this issue, we use inter-flow coding between DATA and ACK to reduce the number of transmissions among nodes. In addition, we also utilize a “pipeline” random linear coding scheme with adaptive redundancy to overcome high packet loss over unreliable links. The resulting coding scheme, ComboCoding, combines intra-flow and inter-flow coding to provide robust TCP transmission in disruptive wireless networks. The main contributions of our scheme are twofold; the efficient combination of random linear coding and XOR coding on bi-directional streams (DATA and ACK, and the novel redundancy control scheme that adapts to time-varying and space-varying link loss. The adaptive ComboCoding was tested on a variable hop string topology with unstable links and on a multipath MANET with dynamic topology. Simulation results show that TCP with ComboCoding delivers higher throughput than with other coding options in high loss and mobile scenarios, while introducing minimal overhead in normal operation.

  17. Trace Analysis of Driver Behavior on Traffic Violator by Using Big Data (Traffic Program in Korea

    Directory of Open Access Journals (Sweden)

    Lee, Jonghak

    2016-01-01

    Full Text Available This study aims to prove the effectiveness of traffic safety education program for traffic violators. Traffic violators who finished the traffic safety education programs were tracked down. In order to analyze the effectiveness of traffic safety education program, traffic violator’s data during ten-year period were used. This study analyzed how traffic violators changed their attitudes about traffic law abidance. Also predicted social benefits from traffic safety education program for traffic violators. Effectiveness of traffic accident prevention through traffic safety education program is approximately 93%. In terms of social benefits, it shows more than $12 billion Even though the effectiveness of traffic safety education program represents remarkable results, but this program is made for traffic violators who have already committed traffic offenses in the past. So in order to prevent traffic violations in advance, specific education program for potentially risky drivers is necessary.

  18. The Influences of Composition and Formula on α-TCP/β-TCP Phosphate Cement's Properties%α-TCP/β-TCP骨水泥组成及配比对性能的影响

    Institute of Scientific and Technical Information of China (English)

    史雪婷; 徐立新; 石宗利

    2006-01-01

    通过对α-TCP体系骨水泥固相粉末配方的优化,研究了不同重量比α-TCP/β-TCP粉末对两相骨水泥凝固时间和抗压强度的影响.结果表明粉末含有β-TCP时,骨水泥凝固时间更适合临床塑型,且β-TCP含量为20%时,抗压强度达52.98 MPa.

  19. Real Time Traffic Models, Decision Support for Traffic Management

    NARCIS (Netherlands)

    Wismans, L.; De Romph, E.; Friso, K.; Zantema, K.

    2014-01-01

    Reliable and accurate short-term traffic state prediction can improve the performance of real-time traffic management systems significantly. Using this short-time prediction based on current measurements delivered by advanced surveillance systems will support decision-making processes on various con

  20. Large scale traffic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Nagel, K.; Barrett, C.L. [Los Alamos National Lab., NM (United States)]|[Santa Fe Institute, NM (United States); Rickert, M. [Los Alamos National Lab., NM (United States)]|[Universitaet zu Koeln (Germany)

    1997-04-01

    Large scale microscopic (i.e. vehicle-based) traffic simulations pose high demands on computational speed in at least two application areas: (i) real-time traffic forecasting, and (ii) long-term planning applications (where repeated {open_quotes}looping{close_quotes} between the microsimulation and the simulated planning of individual person`s behavior is necessary). As a rough number, a real-time simulation of an area such as Los Angeles (ca. 1 million travellers) will need a computational speed of much higher than 1 million {open_quotes}particle{close_quotes} (= vehicle) updates per second. This paper reviews how this problem is approached in different projects and how these approaches are dependent both on the specific questions and on the prospective user community. The approaches reach from highly parallel and vectorizable, single-bit implementations on parallel supercomputers for Statistical Physics questions, via more realistic implementations on coupled workstations, to more complicated driving dynamics implemented again on parallel supercomputers. 45 refs., 9 figs., 1 tab.

  1. Regulated intramembrane proteolysis of the virulence activator TcpP in Vibrio cholerae is initiated by the tail-specific protease (Tsp).

    Science.gov (United States)

    Teoh, Wei Ping; Matson, Jyl S; DiRita, Victor J

    2015-09-01

    Vibrio cholerae uses a multiprotein transcriptional regulatory cascade to control expression of virulence factors cholera toxin and toxin-co-regulated pilus. Two proteins in this cascade are ToxR and TcpP - unusual membrane-localized transcription factors with relatively undefined periplasmic domains and transcription activator cytoplasmic domains. TcpP and ToxR function with each other and two other membrane-localized proteins, TcpH and ToxS, to activate transcription of toxT, encoding the direct activator of toxin and pilus genes. Under some conditions, TcpP is degraded in a two-step proteolytic pathway known as regulated intramembrane proteolysis (RIP), thereby inactivating the cascade. The second step in this proteolytic pathway involves the zinc metalloprotease YaeL; V. cholerae cells lacking YaeL accumulate a truncated yet active form of TcpP termed TcpP*. We hypothesized that a protease acting prior to YaeL degrades TcpP to TcpP*, which is the substrate of YaeL. In this study, we demonstrate that a C-terminal protease called Tsp degrades TcpP to form TcpP*, which is then acted upon by YaeL. We present evidence that TcpH and Tsp serve to protect full-length TcpP from spurious proteolysis by YaeL. Cleavage by Tsp occurs in the periplasmic domain of TcpP and requires residues TcpPA172 and TcpPI174 for wild-type activity.

  2. Fastlane: Traffic flow modeling and multi-class dynamic traffic management

    OpenAIRE

    Schreiter, T.; Van Wageningen-Kessels, F.L.M.; Yuan, Y; Lint, van J. W. C.; Hoogendoorn, S.P.

    2012-01-01

    Dynamic Traffic Management (DTM) aims to improve traffic conditions. DTM usually consists of two steps: first the current traffic is estimated, then appropriate control actions are determined based on that estimate. In order to estimate and control the traffic, a suitable traffic flow model that reproduces the properties of traffic well must be used. One of the most important properties is that traffic is composed of multiple vehicle classes. While many traffic flow models have been proposed ...

  3. Soft Tissue Augmentation with Autologous Platelet Gel and β-TCP: A Histologic and Histometric Study in Mice

    Science.gov (United States)

    Ceccarelli, Maurizio; Marchetti, Massimiliano; Piattelli, Adriano; Mortellaro, Carmen

    2016-01-01

    Background. Facial aging is a dynamic process involving both soft tissue and bony structures. Skin atrophy, with loss of tone, elasticity, and distribution of facial fat, coupled with gravity and muscle activity, leads to wrinkling and folds. Purpose. The aim of the study was to evaluate microporous tricalcium phosphate (β-TCP) and autologous platelet gel (APG) mix in mice for oral and maxillofacial soft tissue augmentation. The hypothesis was that β-TCP added with APG was able to increase the biostimulating effect on fibroblasts and quicken resorption. Materials and Methods. Ten female, 6–8-week-old black-haired mice were selected. β-TCP/APG gel was injected into one cheek; the other was used as control. The animals were sacrificed at 8 weeks and histologically evaluated. Results. The new fibroblast was intensively stained with acid fuchsin and presented in contact with β-TCP. At higher magnification, actively secreting fibroblasts were observed at the periphery of β-TCP with a well differentiated fibroblast cell line and blood vessels. Acid fuchsin stained cutaneous structures in pink: no epidermal/dermal alterations or pathological inflammatory infiltrates were detected. The margins of β-TCP granules were clear and not diffused near tissues. Conclusion. APG with β-TCP preserves skin morphology, without immune response, with an excellent tolerability and is a promising scaffold for cells and biomaterial for soft tissue augmentation.

  4. Soft Tissue Augmentation with Autologous Platelet Gel and β-TCP: A Histologic and Histometric Study in Mice.

    Science.gov (United States)

    Scarano, Antonio; Ceccarelli, Maurizio; Marchetti, Massimiliano; Piattelli, Adriano; Mortellaro, Carmen

    2016-01-01

    Background. Facial aging is a dynamic process involving both soft tissue and bony structures. Skin atrophy, with loss of tone, elasticity, and distribution of facial fat, coupled with gravity and muscle activity, leads to wrinkling and folds. Purpose. The aim of the study was to evaluate microporous tricalcium phosphate (β-TCP) and autologous platelet gel (APG) mix in mice for oral and maxillofacial soft tissue augmentation. The hypothesis was that β-TCP added with APG was able to increase the biostimulating effect on fibroblasts and quicken resorption. Materials and Methods. Ten female, 6-8-week-old black-haired mice were selected. β-TCP/APG gel was injected into one cheek; the other was used as control. The animals were sacrificed at 8 weeks and histologically evaluated. Results. The new fibroblast was intensively stained with acid fuchsin and presented in contact with β-TCP. At higher magnification, actively secreting fibroblasts were observed at the periphery of β-TCP with a well differentiated fibroblast cell line and blood vessels. Acid fuchsin stained cutaneous structures in pink: no epidermal/dermal alterations or pathological inflammatory infiltrates were detected. The margins of β-TCP granules were clear and not diffused near tissues. Conclusion. APG with β-TCP preserves skin morphology, without immune response, with an excellent tolerability and is a promising scaffold for cells and biomaterial for soft tissue augmentation. PMID:27478828

  5. Soft Tissue Augmentation with Autologous Platelet Gel and β-TCP: A Histologic and Histometric Study in Mice

    Directory of Open Access Journals (Sweden)

    Antonio Scarano

    2016-01-01

    Full Text Available Background. Facial aging is a dynamic process involving both soft tissue and bony structures. Skin atrophy, with loss of tone, elasticity, and distribution of facial fat, coupled with gravity and muscle activity, leads to wrinkling and folds. Purpose. The aim of the study was to evaluate microporous tricalcium phosphate (β-TCP and autologous platelet gel (APG mix in mice for oral and maxillofacial soft tissue augmentation. The hypothesis was that β-TCP added with APG was able to increase the biostimulating effect on fibroblasts and quicken resorption. Materials and Methods. Ten female, 6–8-week-old black-haired mice were selected. β-TCP/APG gel was injected into one cheek; the other was used as control. The animals were sacrificed at 8 weeks and histologically evaluated. Results. The new fibroblast was intensively stained with acid fuchsin and presented in contact with β-TCP. At higher magnification, actively secreting fibroblasts were observed at the periphery of β-TCP with a well differentiated fibroblast cell line and blood vessels. Acid fuchsin stained cutaneous structures in pink: no epidermal/dermal alterations or pathological inflammatory infiltrates were detected. The margins of β-TCP granules were clear and not diffused near tissues. Conclusion. APG with β-TCP preserves skin morphology, without immune response, with an excellent tolerability and is a promising scaffold for cells and biomaterial for soft tissue augmentation.

  6. Traffic flow impacts of adaptive cruise control deactivation and (Re)activation with cooperative driver behavior

    NARCIS (Netherlands)

    Klunder, G.; Li, M.; Minderhoud, M.

    2009-01-01

    In 2006 in the Netherlands, a field operational test was carried out to study the effect of adaptive cruise control (ACC) and lane departure warning on driver behavior and traffic flow in real traffic. To estimate the effect for larger penetration rates, simulations were needed. For a reliable impac

  7. Traffic flow modeling: a Genealogy

    NARCIS (Netherlands)

    Van Wageningen-Kessels, F.L.M.; Hoogendoorn, S.P.; Vuik, C.; Van Lint, J.W.C.

    2014-01-01

    80 years ago, Bruce Greenshields presented the first traffic flow model at the Annual Meeting of the Highway Research Board. Since then, many models and simulation tools have been developed. We show a model tree with four families of traffic flow models, all descending from Greenshields' model. The

  8. Reports on internet traffic statistics

    NARCIS (Netherlands)

    Hoogesteger, Martijn; Oliveira Schmidt, de Ricardo; Sperotto, Anna; Pras, Aiko

    2013-01-01

    Internet traffic statistics can provide valuable information to network analysts and researchers about the way nowadays networks are used. In the past, such information was provided by Internet2 in a public website called Internet2 NetFlow: Weekly Reports. The website reported traffic statistics fro

  9. Transitions towards sustainable traffic management

    NARCIS (Netherlands)

    Wilmink, I.; Immers, B.; Potters, P.; Knaap, R. van der

    2006-01-01

    Traffic management (TM) has come a long way over the past years. However, several problems inhibit further development of traffic management and the large-scale implementation of successful pilot projects with innovative TM solutions. Given the still increasing mobility and its undesirable side-effe

  10. Pandemic serotypes of Vibrio cholerae isolated from ships' ballast tanks and coastal waters: assessment of antibiotic resistance and virulence genes (tcpA and ctxA).

    Science.gov (United States)

    Dobbs, Fred C; Goodrich, Amanda L; Thomson, Frank K; Hynes, Wayne

    2013-05-01

    There is concern that ships' ballasting operations may disseminate Vibrio cholerae to ports throughout the world. Given evidence that the bacterium is indeed transported by ships, we isolated pandemic serotypes O1 and O139 from ballast tanks and characterized them with respect to antibiotic resistance and virulence genes ctxA and tcpA. We carried out concurrent studies with V. cholerae isolated from coastal waters. Of 284 isolates, 30 were serotype O1 and 59 were serotype O139. These serotypes were overrepresented in ballast tanks relative to the coastal waters sampled. All locations, whether coastal waters or ballast tanks, yielded samples from which serotype O1, O139, or both were isolated. There were three groups among the 62 isolates for which antibiotic characterization was conclusive: those exhibiting β-lactamase activity and resistance to at least one of the 12 antibiotics tested; those negative for β-lactamase but having antibiotic resistance; those negative for β-lactamase and registering no antibiotic resistance. When present, antibiotic resistance in nearly all cases was to ampicillin; resistance to multiple antibiotics was uncommon. PCR assays revealed that none of the isolates contained the ctxA gene and only two isolates, one O139 and one O1, contained the tcpA gene; both isolates originated from ballast water. These results support the bacteriological regulations proposed by the International Maritime Association for discharged ballast water.

  11. Dissociative Tendencies and Traffic Incidents

    Directory of Open Access Journals (Sweden)

    Valle, Virginia

    2012-01-01

    Full Text Available This paper analyses the relationship between dissociative experiences and road traffic incidents (crashes and traffic tickets in drivers (n=295 from Mar del Plata (Argentina city. A self-report questionnaire was applied to assess traffic crash involvement and sociodemographic variables. Dissociative tendencies were assessed by a modified version of the DES scale. To examine differences in DES scores tests of the difference of means were applied. Drivers who reported to be previously involved in traffic incidents obtained higher puntuations in the dissociative experiences scale than drivers who did not report such events. This result is observed for the total scale and for the three sub-scales (absorption, amnesia and depersonalization. However, differences appeared mainly for minor damage collisions. Further studies are needed to evaluate the role of dissociative tendencies as a risk factor in road traffic safety.

  12. Basic model for traffic interweave

    Science.gov (United States)

    Huang, Ding-wei

    2015-09-01

    We propose a three-parameter traffic model. The system consists of a loop with two junctions. The three parameters control the inflow, the outflow (from the junctions,) and the interweave (in the loop.) The dynamics is deterministic. The boundary conditions are stochastic. We present preliminary results for a complete phase diagram and all possible phase transitions. We observe four distinct traffic phases: free flow, congestion, bottleneck, and gridlock. The proposed model is able to present economically a clear perspective to these four different phases. Free flow and congestion are caused by the traffic conditions in the junctions. Both bottleneck and gridlock are caused by the traffic interweave in the loop. Instead of directly related to conventional congestion, gridlock can be taken as an extreme limit of bottleneck. This model can be useful to clarify the characteristics of traffic phases. This model can also be extended for practical applications.

  13. Research of Osteo-induced Rat Mesenchymal Stem Cells Seeding on β-TCP/PLLA Porous Composite

    Institute of Scientific and Technical Information of China (English)

    Qiao-Feng WU; Yan-Juan TANG; Huai-Qing CHEN; Jiang WU; Guang-Fu YIN

    2005-01-01

    @@ 1 Introduction Porous biodegradable synthetic materials such as β-tricalcium phosphate (β-TCP) and poly L-lactic acid(PLLA) are usually used in bone tissue engineering.However, proper ratio, optimum pore size and porosity of the composites of β-TCP/PLLA are not very clear yet. In this study, we chose osteo-induced rat bone mesenchymal stem cells (rMSCs) as seeding cells, and cultured them on β-TCP/ PLLA scaffolds with different ratio, different pore size and different porosity. The aim is to investigate the optimum construction for supporting cell growth, proliferation and differentiation.

  14. Traffic Impact Simulation for Road Construction Project

    OpenAIRE

    Yazao Yang; Xiaoni Hao; Junshao Luo

    2012-01-01

    With the increasing traffic contradiction between supply and demand, urban traffic problems have become quite complex. Reasons for traffic congestion have become much more diverse. During the construction of urban road project, the surrounding road network will encounter a huge impact, traffic problems therefore emerged. Simulation is an important means for transport impact assessment, which has an important role for construction traffic impact analysis. Accordingly, traffic simulation i...

  15. Traffic Matrix Reloaded: Impact of Routing Changes

    OpenAIRE

    Teixeira, Renata; Duffield, Nick; Rexford, Jennifer; Roughan, Matthew

    2005-01-01

    International audience A traffic matrix represents the load from each ingress point to each egress point in an IP network. Although networks are engineered to tolerate some variation in the traffic matrix, large changes can lead to congested links and poor performance. The variations in the traffic matrix are caused by statistical fluc-tuations in the traffic entering the network and shifts in where the traffic leaves the network. For an accurate view of how the traffic matrix evolves over...

  16. An Open-Source Microscopic Traffic Simulator

    OpenAIRE

    Treiber, Martin; Kesting, Arne

    2010-01-01

    We present the interactive Java-based open-source traffic simulator available at www.traffic-simulation.de. In contrast to most closed-source commercial simulators, the focus is on investigating fundamental issues of traffic dynamics rather than simulating specific road networks. This includes testing theories for the spatiotemporal evolution of traffic jams, comparing and testing different microscopic traffic models, modeling the effects of driving styles and traffic rules on the efficiency ...

  17. Environmental stress model for evaluation of vessel traffic in ports and waterways

    Institute of Scientific and Technical Information of China (English)

    HU Zhiwu; CHEN Weijiong; INOUE K

    2005-01-01

    Environmental stress model is proposed as an effective tool to the analysis and evaluation of navigational safety in ports and waterways. Marine traffic simulations are carried out in a virtual port area with various arrangements and conditions. Calculations of stress values and traffic volume criteria are illustrated. The simulation results provide a valuable hint for safety management of vessel traffic. The model provides quantitative information and helps administrators in decision making to achieve desired safety level and improve the efficiency of vessel traffic in ports and waterways.

  18. A NOVEL APPROACH FOR REAL TIME INTERNET TRAFFIC CLASSIFICATION

    Directory of Open Access Journals (Sweden)

    Rupesh Jaiswal

    2015-09-01

    Full Text Available Real time internet traffic classification is imperative for service discrimination, network security and network monitoring. Classification of traffic depends on initial first few network packets of full flows of captured IP traffic. Practically, the real world framework situation expects correct conclusion of classification well before a flow has ended even if the start of the Traffic flow is missed. This is achieved by calculating features from few N network packets, taken at any random time instant at any random point in the duration of flow. This research proposes a novel parameter Relative Uncertainty (RU to estimate the level of diversity of internet traffic and can then be used for characterization of internet traffic. Small sub-flows from Full-flows are selected based on minimum RU value (MRUB-SFs: Minimum RU Based Sub Flows, and then features are calculated for training the C4.5 ML classifier. Experimentation is carried out with various standard datasets and results stable accuracy of 99.3167% for different classes of applications.

  19. Traffic information computing platform for big data

    International Nuclear Information System (INIS)

    Big data environment create data conditions for improving the quality of traffic information service. The target of this article is to construct a traffic information computing platform for big data environment. Through in-depth analysis the connotation and technology characteristics of big data and traffic information service, a distributed traffic atomic information computing platform architecture is proposed. Under the big data environment, this type of traffic atomic information computing architecture helps to guarantee the traffic safety and efficient operation, more intelligent and personalized traffic information service can be used for the traffic information users

  20. Web application for traffic flow forecasting

    OpenAIRE

    Dubravac, Dragan

    2015-01-01

    Disturbances in traffic on highways usually lead to an increase in traffic flow density or even traffic jams. The main goal of the diploma thesis is to produce an application that will predict traffic flow and traffic jams on any given date and time based on traffic flow in the past. By using an estimated desired speed the traffic information gained from flow counters we can forecast the evolution of traffic jams. The application presents a graph that represents the number of vehicles on a...

  1. Traffic information computing platform for big data

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Zongtao, E-mail: ztduan@chd.edu.cn; Li, Ying, E-mail: ztduan@chd.edu.cn; Zheng, Xibin, E-mail: ztduan@chd.edu.cn; Liu, Yan, E-mail: ztduan@chd.edu.cn; Dai, Jiting, E-mail: ztduan@chd.edu.cn; Kang, Jun, E-mail: ztduan@chd.edu.cn [Chang' an University School of Information Engineering, Xi' an, China and Shaanxi Engineering and Technical Research Center for Road and Traffic Detection, Xi' an (China)

    2014-10-06

    Big data environment create data conditions for improving the quality of traffic information service. The target of this article is to construct a traffic information computing platform for big data environment. Through in-depth analysis the connotation and technology characteristics of big data and traffic information service, a distributed traffic atomic information computing platform architecture is proposed. Under the big data environment, this type of traffic atomic information computing architecture helps to guarantee the traffic safety and efficient operation, more intelligent and personalized traffic information service can be used for the traffic information users.

  2. Application on the Transportation of TT&C Data Based on TCP/IP%TCP/IP技术在航天测控通信中的应用

    Institute of Scientific and Technical Information of China (English)

    魏晨曦

    2005-01-01

    本文重点介绍了NASA、ESA及俄罗斯航天局在航天测控领域应用Internet及其技术的情况,剖析了该技术在航天测控通信领域已经及将要产生的重要影响.当今网络技术的飞速发展推动着测控通信技术的革新,如何利用TCP/IP协议传输数据也成为我国测控通信研究的一个热点.

  3. 一种新的TCP Reno解析模型%New TCP throughput Analytical Model Considering Burst Errors In Wireless link and Timeout Mechanism

    Institute of Scientific and Technical Information of China (English)

    邓建民; 纪红; 乐光新; 尹长川

    2003-01-01

    本文考虑无线慢衰落信道突发差错的特点,运用一阶Markov过程描述信道,并结合TCP-Reno协议拥塞控制机制中超时的指数增长,提出一种新的有效的TCP解析模型.理论分析和仿真结果表明,该模型不但使计算复杂性降低,也使计算的准确性有很大提高.

  4. Carrying Capacity:An Overview

    Institute of Scientific and Technical Information of China (English)

    Chen Shaofeng

    2004-01-01

    The concept of carrying capacity is derived from ecology, with widespread contentions of its theoretical connotations and applications in the international academic community, especially the impact of human activities on the environment.Disputes on carrying capacity have been occurring not only among biologists and ecologists, but also among mainstream economists. Based on their efforts,the author makes an attempt to describe its origin,connotations, problems, measurement, and at the same time note the latest international progress in this field.

  5. Statistical Multiplexing of Video Traffic and Data Traffic

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This paper studies statistical multiplexing performance byinput of video traffic and data traffic. The inputs have different Qos requirements such as loss and delay jitter. By applying a modified FBM model, we present methods to estimate effective bandwidth of the aggregated traffic. Simulationswere paformed to evaluate effective bandwidth. The comparison between the estimation and the simulation shows that the estimations can give correct data for the effective bandwidths in terms of our interests. The analysis of gain by using priority multiplexing also addresses proper Qos configuration for the inputs in order to achieve positive gains.

  6. Linking spatial and dynamic models for traffic maneuvers

    DEFF Research Database (Denmark)

    Olderog, Ernst-Rüdiger; Ravn, Anders Peter; Wisniewski, Rafal

    2015-01-01

    For traffic maneuvers of multiple vehicles on highways we build an abstract spatial and a concrete dynamic model. In the spatial model we show the safety (collision freedom) of lane-change maneuvers. By linking the spatial and dynamic model via suitable refinements of the spatial atoms to distance...... measures, the safety carries over to the concrete model....

  7. Energy Saving: Scaling Network Energy Efficiency Faster than Traffic Growth

    NARCIS (Netherlands)

    Chen, Y.; Blume, O.; Gati, A.; Capone, A.; Wu, C.-E.; Barth, U.; Marzetta, T.; Zhang, H.; Xu, S.

    2013-01-01

    As the mobile traffic is expected to continue its exponential growth in the near future, energy efficiency has gradually become a must criterion for wireless network design. Three fundamental questions need to be answered before the detailed design could be carried out, namely what energy efficiency

  8. An Approach to Traffic Scenario Analysis, Generation and Evaluation

    NARCIS (Netherlands)

    Chen, Y.; Van Zuylen, H.J.

    2014-01-01

    Start taking a few most applied scenarios from a traffic control centre, analysing each component and structure of the whole, and evaluating the impact of each component and some typical combinations, based on available monitoring systems. Carrying on such initial research on best practices, we buil

  9. 萍乡地区O139群霍乱弧菌TcpA基因序列分析%Gene Sequencing Analysis on Vibrio Cholera O139 Strains TcpA of Pingxiang Area

    Institute of Scientific and Technical Information of China (English)

    王长奇; 姚彬泉; 贺丁山; 陈燕萍; 罗娜; 周文峰

    2003-01-01

    目的探讨O139群霍乱JX株的TcpA基因序列,分析该株基因的特点.方法采用PCR扩增技术,检测含O139群霍乱标本,对TcpA基因阳性者进行核苷酸序列测定,分析基因变异情况.结果发现阳性标本中,对其中1株进行了TcpA基因序列测定,该序列与TcpAET(O139株)同源性为100%,与EVC序列同源性为96%.结论本株与O1群(EVC)遗传关系最近,对萍乡地区霍乱防治具有重要意义.

  10. Evaluation of The Impacts of VMS on Traffic Performance Measures in An Urban Area in Indonesia

    Directory of Open Access Journals (Sweden)

    A. Caroline Sutandi

    2008-01-01

    Full Text Available Variable Message Sign (VMS is especially recommended for congested flow conditions. The aim of this study is to investigate how drivers in a large city in a developing country with many specific geometric and traffic conditions and also specific driver behaviour, use VMS in aid of choosing route for their inter-city trips. Furthermore, to explore the impact of the use of the information on increasing traffic performance measures. A case study was carried out in Bandung, Indonesia. Microscopic traffic simulations were used in this study to evaluate traffic performance measures. The results of the evaluation found that VMS has insignificant impact on drivers’ route choice behaviour. The results indicated that drivers in Bandung rely much on their experience of traffic conditions commonly occur in the city and demonstrated that VMS has no significant impact to increase traffic performance, but has better impact on the roads with higher number of alternative roads.

  11. Framework for Traffic Congestion Management

    Directory of Open Access Journals (Sweden)

    Mahmud Hassan TALUKDAR

    2013-06-01

    Full Text Available Traffic Congestion is one of many serious global problems in all great cities resulted from rapid urbanization which always exert negative externalities upon society. The solution of traffic congestion is highly geocentric and due to its heterogeneous nature, curbing congestion is one of the hard tasks for transport planners. It is not possible to suggest unique traffic congestion management framework which could be absolutely applied for every great cities. Conversely, it is quite feasible to develop a framework which could be used with or without minor adjustment to deal with congestion problem. So, the main aim of this paper is to prepare a traffic congestion mitigation framework which will be useful for urban planners, transport planners, civil engineers, transport policy makers, congestion management researchers who are directly or indirectly involved or willing to involve in the task of traffic congestion management. Literature review is the main source of information of this study. In this paper, firstly, traffic congestion is defined on the theoretical point of view and then the causes of traffic congestion are briefly described. After describing the causes, common management measures, using world- wide, are described and framework for supply side and demand side congestion management measures are prepared.

  12. Rapid Protoyping Software for Developing Next-Generation Air Traffic Management Algorithms Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Research on next-generation air traffic control systems are being conducted at several laboratories. Most of this work is being carried out using custom software....

  13. Bone Regeneration of Rat Tibial Defect by Zinc-Tricalcium Phosphate (Zn-TCP Synthesized from Porous Foraminifera Carbonate Macrospheres

    Directory of Open Access Journals (Sweden)

    Joshua Chou

    2013-12-01

    Full Text Available Foraminifera carbonate exoskeleton was hydrothermally converted to biocompatible and biodegradable zinc-tricalcium phosphate (Zn-TCP as an alternative biomimetic material for bone fracture repair. Zn-TCP samples implanted in a rat tibial defect model for eight weeks were compared with unfilled defect and beta-tricalcium phosphate showing accelerated bone regeneration compared with the control groups, with statistically significant bone mineral density and bone mineral content growth. CT images of the defect showed restoration of cancellous bone in Zn-TCP and only minimal growth in control group. Histological slices reveal bone in-growth within the pores and porous chamber of the material detailing good bone-material integration with the presence of blood vessels. These results exhibit the future potential of biomimetic Zn-TCP as bone grafts for bone fracture repair.

  14. Tcp协议的确认机制比较与分析%Tcp Protocol Acknowledgment Mechanism Comparison and Analysis

    Institute of Scientific and Technical Information of China (English)

    关启学

    2014-01-01

    With the development of Internet, network technology has been widely promoted and applied, Tcp protocol followed emerged. Tcp protocol wide area network generated, based on its development of Arpanet network of research institutions. Because people Tcp protocol validation mechanism lack of understanding, therefore, we compared and analyzed to confirm the mechanism Tcp protocol.%随着互联网的发展,网络技术得到了广泛的推广和运用,Tcp协议随之应运而生。Tcp协议在广域网中产生,它的发展基于Arpanet网的研究机构。由于人们对Tcp协议的确认机制缺乏了解,因此,我们比较、分析了Tcp协议的确认机制。

  15. Traffic Light Detection at Night

    DEFF Research Database (Denmark)

    Jensen, Morten Bornø; Philipsen, Mark Philip; Bahnsen, Chris;

    2015-01-01

    Traffic light recognition (TLR) is an integral part of any in- telligent vehicle, it must function both at day and at night. However, the majority of TLR research is focused on day-time scenarios. In this paper we will focus on detection of traffic lights at night and evalu- ate the performance...... of three detectors based on heuristic models and one learning-based detector. Evaluation is done on night-time data from the public LISA Traffic Light Dataset. The learning-based detector out- performs the model-based detectors in both precision and recall. The learning-based detector achieves an average...

  16. Transition Characteristic Analysis of Traffic Evolution Process for Urban Traffic Network

    OpenAIRE

    Longfei Wang; Hong Chen; Yang Li

    2014-01-01

    The characterization of the dynamics of traffic states remains fundamental to seeking for the solutions of diverse traffic problems. To gain more insights into traffic dynamics in the temporal domain, this paper explored temporal characteristics and distinct regularity in the traffic evolution process of urban traffic network. We defined traffic state pattern through clustering multidimensional traffic time series using self-organizing maps and construct a pattern transition network model tha...

  17. Real-Time Corrected Traffic Correlation Model for Traffic Flow Forecasting

    OpenAIRE

    Lu, Hua-pu; Sun, Zhi-yuan; Qu, Wen-cong; Wang, Ling

    2015-01-01

    This paper focuses on the problems of short-term traffic flow forecasting. The main goal is to put forward traffic correlation model and real-time correction algorithm for traffic flow forecasting. Traffic correlation model is established based on the temporal-spatial-historical correlation characteristic of traffic big data. In order to simplify the traffic correlation model, this paper presents correction coefficients optimization algorithm. Considering multistate characteristic of traffic ...

  18. Spatiotemporal traffic-flow dependency and short-term traffic forecasting

    OpenAIRE

    Yang Yue; Anthony Gar-On Yeh

    2008-01-01

    Short-term traffic forecasting is playing an increasing role in modern transport management. Although many short-term traffic forecasting methods have been explored, the spatiotemporal dependency of traffic flow, an important characteristic of traffic dynamics that can benefit the forecasting of traffic changes, is often neglected in short-term traffic forecasting. This paper first investigates the spatiotemporal dependency of traffic flow using cross-correlation analysis and then discusses i...

  19. A Two-Stage Fuzzy Logic Control Method of Traffic Signal Based on Traffic Urgency Degree

    OpenAIRE

    Yan Ge

    2014-01-01

    City intersection traffic signal control is an important method to improve the efficiency of road network and alleviate traffic congestion. This paper researches traffic signal fuzzy control method on a single intersection. A two-stage traffic signal control method based on traffic urgency degree is proposed according to two-stage fuzzy inference on single intersection. At the first stage, calculate traffic urgency degree for all red phases using traffic urgency evaluation module and select t...

  20. MAC-layer protocol for TCP fairness in Wireless Mesh Networks

    KAUST Repository

    Nawab, Faisal

    2012-08-01

    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 performance 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 to alleviate the unfairness problem in WMNs. Our protocol uses the age of packet as a priority metric for packet scheduling. Simulation is conducted to validate our model and to illustrate the fairness characteristics of our proposed MAC protocol. We conclude that we can achieve fairness with only little impact on network capacity.

  1. Design of the Congestion Control for TCP/AQM Network with Time-Delay

    Directory of Open Access Journals (Sweden)

    Dazhong Wang

    2014-01-01

    Full Text Available The purpose of this paper is to design congestion controller for TCP/AQM (transmission control protocol/active queue management networks using model following control; the equilibrium of a class of TCP/AQM networks with time-delay is investigated, and the effect of communication time-delay on the stability is addressed. The features of this design method are bounded property of the internal states of the control system being given and the utility of this control. Such design exhibits important attributes including fast convergence with high accuracy to a desired queue length. Simulation results show that the time-delay nonlinear behavior of the system can be controlled by this method.

  2. TCP/IP Interface for the Satellite Orbit Analysis Program (SOAP)

    Science.gov (United States)

    Carnright, Robert; Stodden, David; Coggi, John

    2009-01-01

    The Transmission Control Protocol/ Internet protocol (TCP/IP) interface for the Satellite Orbit Analysis Program (SOAP) provides the means for the software to establish real-time interfaces with other software. Such interfaces can operate between two programs, either on the same computer or on different computers joined by a network. The SOAP TCP/IP module employs a client/server interface where SOAP is the server and other applications can be clients. Real-time interfaces between software offer a number of advantages over embedding all of the common functionality within a single program. One advantage is that they allow each program to divide the computation labor between processors or computers running the separate applications. Secondly, each program can be allowed to provide its own expertise domain with other programs able to use this expertise.

  3. ESTRATEGIA PARA EL PRONÓSTICO DEL RTO DE FAST TCP, MEDIANTE LÓGICA DIFUSA

    Directory of Open Access Journals (Sweden)

    Carlos Peña

    2013-07-01

    Full Text Available Este artículo presenta el diseño y la simulación de una estrategia para el pronóstico del temporizador de retransmisión del algoritmo de control de la congestión FAST TCP. La estrategia utiliza la técnica de inteligencia computacional denominada lógica difusa. Los resultados de la simulación demuestran que a través de esta nueva forma de pronóstico del RTO, FAST TCP hace un mejor seguimiento a la situación real de congestión de la red, en el marco de una conexión entre dos extremos de la misma.

  4. On Designing Lyapunov-Krasovskii Based AQM for Routers Supporting TCP Flows

    CERN Document Server

    Labit, Yann; Gouaisbaut, Frédéric; 10.1109/CDC.2007.4434673

    2009-01-01

    For the last few years, we assist to a growing interest of designing AQM (Active Queue Management) using control theory. In this paper, we focus on the synthesis of an AQM based on the Lyapunov theory for time delay systems. With the help of a recently developed Lyapunov-Krasovskii functional and using a state space representation of a linearized fluid model of TCP, two robust AQMs stabilizing the TCP model are constructed. Notice that our results are constructive and the synthesis problem is reduced to a convex optimization scheme expressed in terms of linear matrix inequalities (LMIs). Finally, an example extracted from the literature and simulations via {\\it NS simulator} support our study.

  5. Fuzzy-Logic Adaptive Queuing for a Heuristic TCP Performance in Mobile Wireless Networks

    Directory of Open Access Journals (Sweden)

    Ghaida A. AL-Suhail

    2012-06-01

    Full Text Available In this paper, we propose a new Fuzzy-Logic Adaptive Queuing controller (FLAQ based on a classical Random Early Detection (RED algorithm in wireless cellular network. The controller predicts dynamically the packet dropping rate and the corresponding average queue length. It relies on the average queue length at the base station router and the packet loss rate caused by the channel variations in mobile environment; assuming there is no buffer overflow due to the congestion. Using this model, a heuristic TCP performance can be estimated over a time-varying channel under different conditions of user’s mobility. The results show a significant improvement in TCP throughput performance when the user’s mobility is below 5 m/s; and becomes constant (i.e., close to i.i.d beyond this speed especially at 5% of predefined packet error rate.

  6. Approaches in highly parameterized inversion - GENIE, a general model-independent TCP/IP run manager

    Science.gov (United States)

    Muffels, Christopher T.; Schreuder, Willem A.; Doherty, John E.; Karanovic, Marinko; Tonkin, Matthew J.; Hunt, Randall J.; Welter, David E.

    2012-01-01

    GENIE is a model-independent suite of programs that can be used to generally distribute, manage, and execute multiple model runs via the TCP/IP infrastructure. The suite consists of a file distribution interface, a run manage, a run executer, and a routine that can be compiled as part of a program and used to exchange model runs with the run manager. Because communication is via a standard protocol (TCP/IP), any computer connected to the Internet can serve in any of the capacities offered by this suite. Model independence is consistent with the existing template and instruction file protocols of the widely used PEST parameter estimation program. This report describes (1) the problem addressed; (2) the approach used by GENIE to queue, distribute, and retrieve model runs; and (3) user instructions, classes, and functions developed. It also includes (4) an example to illustrate the linking of GENIE with Parallel PEST using the interface routine.

  7. Biodegradation Study of Microcrystalline Chitosan and Microcrystalline Chitosan/β-TCP Complex Composites

    Directory of Open Access Journals (Sweden)

    Kinga Brzoza-Malczewska

    2012-06-01

    Full Text Available Bone repair or regeneration is a common and complicated clinical problem in orthopedic surgery. The importance of natural polymers, such as microcrystalline chitosan, and minerals such as HAp and β-TCP, has grown significantly over the last two decades due to their renewable and biodegradable source, increasing the knowledge and functionality of composites in technological and biomedical applications. This study compares the biodegradation process, bioactivity, structure, morphology, and mechanical properties of microcrystalline chitosan and microcrystalline chitosan/β-TCP complex; the latter according to the new method of preparation. The complex showed a homogeneous network structure with regular pores, good bioactivity, even after 60 days of conducting the hydrolytic and enzymatic degradation process, showing a bacteriostatic and bactericidal activity. The complex indicates that it could be used successfully as a base for implants and scaffolds production in orthopedic surgery.

  8. How Equalization Techniques Affect the TCP Performance of MC-CDMA Systems in Correlated Fading Channels

    Directory of Open Access Journals (Sweden)

    Giacomo Leonardi

    2007-12-01

    Full Text Available This paper investigates the impact of several equalization techniques for multicarrier code division multiple access systems on the performance at both lower and upper layers (i.e., physical and TCP layers. Classical techniques such as maximal ratio combining, equal gain combining, orthogonality restoring combining, minimum mean square error, as well as a partial equalization (PE are investigated in time- and frequency-correlated fading channels with various numbers of interferers. Their impact on the performance at upper level is then studied. The results are obtained through an integrated simulation platform carefully reproducing all main aspects affecting the quality of service perceived by the final user, allowing an investigation of the real gain produced by signal processing techniques at TCP level.

  9. Satellite communication on pipeline supervision using TCP-IP Protocol; Comunicacao via satelite na supervisao de dutos usando o protocolo TCP-IP

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Agliberto Pessoa da [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Brunette, Sergio Henrique de Moraes

    2003-07-01

    Bit transparent type or X-25 protocols have been used in VSAT satellite communication by PETROBRAS pipeline Supervisory Control and Data Acquisition System (SCADA) as access protocol. Both solutions have inconveniences. By the first one, difficulties exist for analysis and diagnosis of connection flaws, and therefore, for a ready identification by the system management stations of abnormality location. On the other hand, the usage of the X-25 brings an additional over-head in the communication since this is not an available option in most of the equipment that compose the SCADA. The access to VSAT through Ethernet, in the opposite, makes available all networks management tools of the TCP/IP platform and it allows a direct connection to the field devices, since the main models of the several makers of Programmable Controllers and Remote Terminal Units have Ethernet port. An additional earnings is the possibility of standardization that this solution allows. This paper describes a series of communication tests between two Programmable Controllers communicating through the satellite, using a protocol over Ethernet/TCP/IP. (author)

  10. Characteristics of synchronized traffic in mixed traffic flow

    Institute of Scientific and Technical Information of China (English)

    Ning Hong-Xin; Xue Yu

    2012-01-01

    In this paper,the characteristics of synchronized traffic in mixed traffic flow are investigated based on the braking light model.By introducing the energy dissipation and the distribution of slowdown vehicles,the effects of the maximum velocity,the mixing ratio,and the length of vehicles on the synchronized flow are discussed.It is found that the maximum velocity plays a great role in the synchronized flow in mixed traffic.The energy dissipation and the distribution of slowdown vehicles in the synchronized flow region are greatly different from those in free flow and a traffic jamming region.When all of vehicles have the same maximum velocity with Vmax > 15,the mixed traffic significantly displays synchronized flow,which has been demonstrated by the relation between flow rate and occupancy and estimation of the cross-correlation function.Moreover,the energy dissipation in the synchronized flow region does not increase with occupancy.The distribution of slowdown vehicles shows a changeless platform in the synchronized flow region.This is an interesting phenomenon. It helps to deeply understand the synchronized flow and greatly reduce the energy dissipation of traffic flow.

  11. Optimization of VIGS and functional analysis of Gerbera hybrida TCP genes in Calendula officinalis

    OpenAIRE

    Zhang, Yao

    2012-01-01

    The evolution of floral novelties involves activities of several transcription factors. The large Asteraceae plant family has inflorescences consisting of different types of flowers. TCP transcription factors have recently been reported to regulate this complex structure. Gerbera hybrida, a common ornamental crop, has been used as a model plant for flower developmental studies in Asteraceae. It can be genetically transformed; however, transformation is laborious and time-consuming. Calendula ...

  12. Biodegradation Study of Microcrystalline Chitosan and Microcrystalline Chitosan/β-TCP Complex Composites

    OpenAIRE

    Kinga Brzoza-Malczewska; Magdalena Kucharska; Bogdan Gruchała; Maria Wísniewska-Wrona; Luciano Pighinelli

    2012-01-01

    Bone repair or regeneration is a common and complicated clinical problem in orthopedic surgery. The importance of natural polymers, such as microcrystalline chitosan, and minerals such as HAp and β-TCP, has grown significantly over the last two decades due to their renewable and biodegradable source, increasing the knowledge and functionality of composites in technological and biomedical applications. This study compares the biodegradation process, bioactivity, structure, morphology, and mech...

  13. Experimental Evaluation of TCP-Based DTN for Cislunar Communications in Presence of Long Link Disruption

    OpenAIRE

    Ruhai Wang; Xuan Wu; Qinyu Zhang; Tarik Taleb; Zhensheng Zhang; Jia Hou

    2011-01-01

    Delay/disruption tolerant networking (DTN) technology is considered a new solution to highly stressed communications in space environments. To date, little work has been done in evaluating the effectiveness and performance of the available DTN protocols when they are applied to an interplanetary Internet, especially in presence of a long link disruption. In this paper, we present an experimental investigation of the DTN architecture with a Bundle Protocol (BP) running over TCP-based converge...

  14. A study of the consolidation method with albumin to obtain porous beta-TCP ceramics

    OpenAIRE

    Christiane Ribeiro; José Carlos Bressiani; Ana Helena Almeida Bressiani

    2007-01-01

    In many 'in-vivo' and 'in-vitro' studies, the behavior of calcium phosphate ceramics like beta - tricalcium phosphate in biological environments has been reported to be predictive and positive. In terms of bone tissue growth, these ceramics are attractive biomaterials due to their porous microstructures. To obtain biomaterial quality ceramics, in this investigationbeta- TCP porous ceramics were prepared by a special consolidation method with albumin as a foam generating agent. This technique ...

  15. Design of Feedback Controls Supporting TCP based on Modern Control Theory

    OpenAIRE

    Kim, Ki Baek

    2003-01-01

    This paper investigates how to design feedback controls supporting TCP (Transmission Control Protocol) based on modern control theories. The present paper studies a simplified version of this problem: the linearized version of the well-known AIMD (Additive Increase Multiplicative Decrease) dynamic model under the assumption that the network information is known. Since we formulate the feedback control design problem as state-space models without assuming its structure in advance, we get three...

  16. TCP SYN Flood攻击和防御的分析

    Institute of Scientific and Technical Information of China (English)

    聂涛

    2006-01-01

    TCP SYN Flood(TCP同步洪水攻击)是目前最流行的DoS(拒绝服务攻击)与DDoS的方式之一,这是一种利用TCP协议缺陷,破坏TCP三次握手建立正常连接,从而使得被攻击方资源耗尽的攻击方式。

  17. Throughput modeling of TCP with slow-start and fast recovery

    OpenAIRE

    Yeung, KL; Li, VOK; Zhou, K

    2005-01-01

    Despite the rich literature on modeling TCP, we find two common deficiencies with the existing approaches. First, none of the work gives sufficient treatment to slow-start, although almost all of them show that retransmission timeout events are common. Second, the probability that retransmission timeout occurs has been underestimated, because retransmission timeout is coupled with fast recovery but fast recovery has not been properly modeled in the previous work. In this paper, new analytical...

  18. Communication-Gateway Software For NETEX, DECnet, And TCP/IP

    Science.gov (United States)

    Keith, B.; Ferry, D.; Fendler, E.

    1990-01-01

    Communications gateway software, GATEWAY, provides process-to-process communication between remote applications programs in different protocol domains. Communicating peer processes may be resident on any paired combination of NETEX, DECnet, or TCP/IP hosts. Provides necessary mapping from one protocol to another and facilitates practical intermachine communications in cost-effective manner by eliminating need to standardize on single protocol or to implement multiple protocols in host computers. Written in Ada.

  19. TGF-β1-Enhanced TCP-Coated Sensate Scaffolds Can Detect Bone Bonding

    OpenAIRE

    Szivek, J.A.; Margolis, D.S.; Garrison, B.K.; Nelson, E.; Vaidyanathan, R. K.; DeYoung, D. W.

    2005-01-01

    Porous polybutylene terephthalate (PBT) scaffold systems were tested as orthopedic implants to determine whether these scaffolds could be used to detect strain transfer following bone growth into the scaffold. Three types of scaffold systems were tested: porous PBT scaffolds, porous PBT scaffolds with a thin β-tricalcium phosphate coating (LC-PBT), and porous PBT scaffolds with the TCP coating vacuum packed into the scaffold pores (VI-PBT). In addition, the effect of applying TGF-β1 to scaffo...

  20. Enhanced interaction of Vibrio cholerae virulence regulators TcpP and ToxR under oxygen-limiting conditions.

    Science.gov (United States)

    Fan, Fenxia; Liu, Zhi; Jabeen, Nusrat; Birdwell, L Dillon; Zhu, Jun; Kan, Biao

    2014-04-01

    Vibrio cholerae is the causative agent of the diarrheal disease cholera. The ability of V. cholerae to colonize and cause disease requires the intricately regulated expression of a number of virulence factors during infection. One of the signals sensed by V. cholerae is the presence of oxygen-limiting conditions in the gut. It has been shown that the virulence activator AphB plays a key role in sensing low oxygen concentrations and inducing the transcription of another key virulence activator, TcpP. In this study, we used a bacterial two-hybrid system to further examine the effect of oxygen on different virulence regulators. We found that anoxic conditions enhanced the interaction between TcpP and ToxR, identified as the first positive regulator of V. cholerae virulence genes. We further demonstrated that the TcpP-ToxR interaction was dependent on the primary periplasmic protein disulfide formation enzyme DsbA and cysteine residues in the periplasmic domains of both ToxR and TcpP. Furthermore, we showed that in V. cholerae, an interaction between TcpP and ToxR is important for virulence gene induction. Under anaerobic growth conditions, we detected ToxR-TcpP heterodimers, which were abolished in the presence of the reducing agent dithiothreitol. Our results suggest that V. cholerae may sense intestinal anoxic signals by multiple components to activate virulence.