19 resultados para TCP(transmissioncontrolprotocol)

em Deakin Research Online - Australia


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Although TCP has emerged as the standard in data communication, the introduction of ATM technology has raised numerous problems regarding the effectiveness of using TCP over A TM networks, especially when video traffic performance is considered. This paper presents a simulation model for transmission performance of video traffic via ATM over TCP/IP. The interactivity between TCP/IP and ATM, generation of MPEG traffic and evaluation of traffic performance are implemented in the model. The design and implementation details of the model are carefully described. The experiments conducted using the model and experimental results are briefly introduced, revealing the capability of our model in simulating network events and in evaluating potential solutions to performance issues.

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A large volume of TCP/IP traffic is currently, and in the future will be, carried over ATM networks. A major part of the traffic, which is produced by multimedia sources, is encoded using the MPEG standard. For the performance analysis of transferring MPEG video sequence via TCP/IP over A TM networks, there is a need for appropriate simulation models. This paper describes one such simulation model that we have constructed. A sct of preliminary simulation experiments have been conducted with the mode to assess the impact of different network configurations on the MPEG traffic transmission performance. Our simulation model is able to simulate many of the potential performance issues regarding video traffic via TCPIIP and A TM and can be used to evaluate any potential solutions.

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2,4,6-trichlorophenol (2,4,6-TCP) aerobic degrading granules were successfully developed in the sequencing batch airlift reactor. The key strategy used in cultivation of the granules was dosing glucose and acetate as co-substrates. After granulation, average concentrations of 2,4,6-TCP and COD in the effluent were less than 8mgL-1 and 59mgL-1, respectively. The removal efficiencies of 2,4,6-TCP and COD were above 93% and 90%, respectively. The specific degradation rate of 2,4,6-TCP peaked at 61mg 2,4,6-TCP gVSS-1h-1 when inoculated at the concentration of 400mgL-1. The extracellular polymeric substance (EPS) contents of the 2,4,6-TCP aerobic degrading granules were decreased compared with the contents in seed sludge. Two peaks attributed to the protein-like fluorophores were identified by three-dimensional excitation emission matrix (EEM) fluorescence spectra. The decrease of fluorescence parameters, e.g., peak locations, intensities, indicated quenching effect of 2,4,6-TCP on the EPS fluorescence. Meanwhile, the shift of peak position indicated chemical changes of the EPS.

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The expected pervasive use of mobile cloud computing and the growing number of Internet data centers have brought forth many concerns, such as, energy costs and energy saving management of both data centers and mobile connections. Therefore, the need for adaptive and distributed resource allocation schedulers for minimizing the communication-plus-computing energy consumption has become increasingly important. In this paper, we propose and test an efficient dynamic resource provisioning scheduler that jointly minimizes computation and communication energy consumption, while guaranteeing user Quality of Service (QoS) constraints. We evaluate the performance of the proposed dynamic resource provisioning algorithm with respect to the execution time, goodput and bandwidth usage and compare the performance of the proposed scheduler against the exiting approaches. The attained experimental results show that the proposed dynamic resource provisioning algorithm achieves much higher energy-saving than the traditional schemes.

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This paper reports an investigation of if, and how, Soft Systems Methodology (SSM) might.be used to facilitate better management of industry supply chains. In two workshops involving supply chain managers from the Textile Clothing and Footwear (TCP) industry and industry facilitators, ways in which SSM techniques might supplement existing Supply Chain Management (SCM) workshop approaches have been explored. Specifically, the placement of SSM techniques within a workshop setting, reactions to the techniques, perceived reasons for using SSM, together with strengths and difficulties encountered, have been examined.

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Relationships between businesses, businesses and end customers, as well as between customers are an important area of practical and scientific interest. In the present era, largely due to digital technologies such as the database, public and private networks, and data collection and information distribution via TCP/IP (Transmission Control Protocol/Internet Protocol) interface tools such as the World Wide Web (Web), the interest in relationships and related aspects such as trust as it relates to Web interactivity continues. An important antecedent empirical study established that arts patrons (customers) of a New York theatre company could be segmented according to their relational orientation, and that this orientation mediated between component attitudes and future purchase intentions. The study reported in this paper employs Web-based data collection and postal data collection methods in an investigation of the mediation effects of these data collection methods used with the same population of a premier football club in Australia. While a future aim is to more closely compare the outcomes established in the arts study with those from a similarly constructed study in the sporting arena, the focus of this initial paper is the differences in response exhibited by online respondents relative to postal survey respondents. The paper reports findings which do not support those of the antecedent arts and entertainment study concerning the weakness of overall satisfaction on the purchase intentions of high relational orientation customers. The paper also reports findings which give confidence to users of online surveys that despite differences in demographic profiles of these respondents and postal survey respondents, there is a degree of similarity in the responses of the two groups on the measures used in this study. The paper also suggests the need for further research into these data collection effects as they relate to relationship marketing.

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This paper presents results from a qualitative study of income support recipients with regard to how they feel about advertising which overtly appeals to their sense of fear, guilt and shame. The motivation of the study was to provide formative research for a social marketing campaign designed to increase compliance with income reporting requirements. This study shows that negative appeals with this group of people are more likely to invoke self-protection and inaction rather than an active response such as volunteering to comply. Social marketers need to consider the use fear, guilt and shame to gain voluntary compliance as the study suggests that there has been an overuse of these negative appeals. While more formative research is required, the future research direction aim would be to develop an instrument to measure the impact of shame on prosocial decision-making; particularly in the context of social networks rather than the wider society.

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An extracellular tannase (E.C. 3.1.1.20) producing fungal strain was isolated from soil and identified as Aspergillus sp MIK23. Out of various plant extracts, Terminalia chebula powder (TCP) in the optimized medium enhanced enzyme production. Maximum yield of tannase (3 IU ml-1) was obtained with glucose (10 g/L), urea (2 g/L), and yeast extract (2.5 g/L) when inoculated with 10% inoculum in 48 h. An initial medium at pH 6.0 and a cultivation temperature of 37 0C was found to be optimum for enzyme production. Metal ions Mg2+, Zn2+, Ca2+, Cu2+ and Cd2+ did not improve enzyme activity, whereas, Ca2+, Fe2+ and Hg2+ repressed enzyme activity. The enzyme was purified using ammonium sulfate precipitation followed by Q-sepharose ion-exchange chromatography. The enzyme was purified to 42-fold with an overall recovery of 20. The pH and temperature optima of the purified tannase were found to be 7.0 and 37°C, respectively.

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Cyber-Physical Systems allow for the interaction of the cyber world and physical worlds using as a central service called Cloud Web Services. Cloud Web Services can sit well within three models of Cyber- Physical Systems, Software-as-a-Service (SaaS), Platform-as-a-Service (PaaS), and Infrastructure-as-a- Service (IaaS). With any Cyber-Physical system use Cloud Web Services it inherits a security problem, the HX-DoS attack. HX-DoS attack is a combination of HTTP and XML messages that are intentionally sent to flood and destroy the communication channel of the cloud service provider. The relevance of this research is that TCP/IP flood attacks are a common problem and a lot of research to mitigate them has previously been discussed. But HTTP denial of service and XML denial of service problem has only been addressed in a few papers. In this paper, we get closer to closing this gap on this problem with our new defence system called Pre- Decision, Advance Decision, Learning System (ENDER). In our previous experiments using our Cloud Protector, we were successful at detecting and mitigate 91% with a 9% false positive of HX-DoS attack traffic. In this paper, ENDER was able to improve upon this result by being trained and tested on the same data, but with a greater result of 99% detection and 1% false positive.

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Streaming applications over Mobile Ad-hoc Networks (MANET) require a smooth transmission rate. The Internet is unable to provide this service during traffic congestion in the network. Designing congestion control for these applications is challenging, because the standard TCP congestion control mechanism is not able to handle the special properties of a shared wireless multi hop channel well. In particular, the frequent changes to the network topology and the shared nature of the wireless channel pose major challenges. In this paper, we propose a novel approach, which allows a quick increase of throughput by using explicit feedback from routers.