Lying Your Way to Better Traffic Engineering

To optimize the flow of traffic in IP networks, operators do traffic engineering (TE), i.e., tune routing-protocol parameters in response to traffic demands. TE in IP networks typically involves configuring static link weights and splitting traffic between the resulting shortest-paths via the Equal-Cost-MultiPath (ECMP) mechanism. Unfortunately, ECMP is a notoriously cumbersome and indirect means for optimizing traffic flow, often leading to poor network performance. Also, obtaining accurate knowledge of traffic demands as the input to TE is elusive, and traffic conditions can be highly variable, further complicating TE. We leverage recently proposed schemes for increasing ECMP's expressiveness via carefully disseminated bogus information ("lies") to design COYOTE, a readily deployable TE scheme for robust and efficient network utilization. COYOTE leverages new algorithmic ideas to configure (static) traffic splitting ratios that are optimized with respect to all (even adversarially chosen) traffic scenarios within the operator's "uncertainty bounds". Our experimental analyses show that COYOTE significantly outperforms today's prevalent TE schemes in a manner that is robust to traffic uncertainty and variation. We discuss experiments with a prototype implementation of COYOTE

Adolescent road user behaviour : a survey of 11-16 year olds

This study was carried out to investigate the safety related behaviour of road users aged 11-16. A self-completion questionnaire was designed to measure the frequency with which children from the target population carry out 43 different road using behaviours and a number of other variables including children's beliefs about the safety of their own road using behaviour. Two thousand four hundred and thirty three children from eleven secondary schools within England completed the questionnaire in lesson time at school. Factor analysis showed that scores on the 43 behaviour items were best represented by a three-factor solution. The three factors were named unsafe road crossing behaviour, dangerous playing in the road, and planned protective behaviour. Analysis of variance and stepwise multiple regression analyses showed that demographic variables and exposure variables had statistically significant effects on how often these behaviours were carried out. More interesting was the finding that respondents had realistic perceptions of their own behaviour as road users. The more respondents believed their road using behaviour to be unsafe and irresponsible, the more often they reported carrying out road using behaviour that was undesirable from a road safety point of view. These results and their implications for road safety interventions and further research are discussed

Flying green from a carbon neutral airport : the case of Brussels

The aviation sector is one of the fastest growing emitters of greenhouse gases worldwide. In addition, airports have important local environmental impacts, mainly in the form of noise pollution and deterioration in air quality. Although noise nuisance in the vicinity of airports is recognized as an important problem of the urban environment which is often addressed by regulation, other environmental problems associated with aviation are less widely acknowledged. In the climate debate, the importance of which is rising, aviation has remained under the radar for decades. In the present paper, we use the case of Brussels Airport (Belgium) to demonstrate that the local perception of air travel-related environmental problems may be heavily influenced by the communication strategy of the airport company in question. Basing our analysis on publicly available data, communication initiatives, media reports, and policy documents, we find that (1) the noise impact of aviation is recognized and mainly described in an institutionalized format, (2) the impact of aviation on local air quality is ignored, and (3) the communication on climate impact shows little correspondence or concern with the actual effects. These findings are relevant for other airports and sectors, since the type of environmental communication produced by airport companies can also be observed elsewhere

SDN/NFV-enabled satellite communications networks: opportunities, scenarios and challenges

In the context of next generation 5G networks, the satellite industry is clearly committed to revisit and revamp the role of satellite communications. As major drivers in the evolution of (terrestrial) fixed and mobile networks, Software Defined Networking (SDN) and Network Function Virtualisation (NFV) technologies are also being positioned as central technology enablers towards improved and more flexible integration of satellite and terrestrial segments, providing satellite network further service innovation and business agility by advanced network resources management techniques. Through the analysis of scenarios and use cases, this paper provides a description of the benefits that SDN/NFV technologies can bring into satellite communications towards 5G. Three scenarios are presented and analysed to delineate different potential improvement areas pursued through the introduction of SDN/NFV technologies in the satellite ground segment domain. Within each scenario, a number of use cases are developed to gain further insight into specific capabilities and to identify the technical challenges stemming from them.Peer ReviewedPostprint (author's final draft

Spartan Daily, September 27, 1985

Volume 85, Issue 21https://scholarworks.sjsu.edu/spartandaily/7342/thumbnail.jp

Spartan Daily, December 9, 1991

Volume 97, Issue 67https://scholarworks.sjsu.edu/spartandaily/8204/thumbnail.jp

Spartan Daily, September 22, 1997

Volume 109, Issue 16https://scholarworks.sjsu.edu/spartandaily/9163/thumbnail.jp

Optimising cow traffic in automatic milking systems

This thesis comprises the results from three separate studies performed in the experimental automatic milking system at Kungsängen Research Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden. In the first study, 30 high-yielding cows in early lactation were subjected to two different degrees of controlled cow traffic, and the effects on milk yield, dry matter intake, feeding patterns and voluntary visits to the milking unit and the control gates were measured. A model of mixed distributions for estimations of biologically relevant meal criteria from registrations in roughage stations was also evaluated. In the second study, the behaviour of 24 cows after they had been redirected in control gates was observed, and the cause of long redirection times from gates until they showed up in the milking unit was examined. In the third study, 9 cows were subjected to three different cow traffic systems in a carry-over design and the effects on cortisol concentrations in milk and ruminating patterns were studied. The studies showed that milking frequency and thereby milk production can be altered by different time settings in the control gates without limiting the daily feed intake of the cows. A high degree of guidance provokes social effects in the queue in front of the milking unit and in the feeding areas. It also makes it difficult for the cows to follow their natural feeding patterns. Judging from measurements of milk cortisol concentrations, controlled cow traffic was not stressful for the cows. Cows initiated meals with short intervals, which offered many opportunities to milk them. But the queue in front of the milking unit caused long redirection times, and the control gates failed to guide cows to high milking frequencies. Individual differences in feeding patterns and how cows respond to redirections in the control gates suggest that the control gates should be making decisions on an individual level