997 resultados para Traffic Gap Acceptance.


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The objective of our research was to analyse the relevant logistic factors influencing energy efficiency in road freight transport, while quantifying the potential for CO2 reduction. We carried out a survey and linked fuel consumption to transport performance parameters in 50 German haulage companies during 2003. Efficiency ranges from 0.8 tkm to 26 tkm for 1 kg CO2 emissions. The results show a high potential for improvements, given a low level of efficiency in vehicle usage and load factor, scarce use of lightweight vehicle design, incorrectly selected vehicle class and a high proportion of empty runs. Efficiency measures are poorly applied.

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The paper addresses road freight transport operations during the London Olympic and Paralympic Games in 2012. It presents work carried out prior to the Games to understand pre-Games patterns of freight deliveries in London (for both light and heavy goods vehicles) and the results of modelling work carried out to assess the likely impacts of the Games road restrictions on freight operations. The modelling results indicated that increases in total hours travelled carrying out collection and delivery work would range from 1.4% to 11.4% in the six sectors considered. The results suggested increases in hours travelled in excess of 3.5% in four of the six sectors modelled. The possible actions that could be taken by organizations to reduce these negative impacts were also modelled and the results indicated that such actions would help to mitigate the impact of the road restrictions imposed on operators during the Games. The actual impacts of the 2012 Games on transport both in general terms and specifically in terms of freight transport are also discussed, together with the success of the actions taken by Transport for London (TfL) to help the road freight industry. The potential freight transport legacy of the London 2012 Games in terms of achieving more sustainable urban freight transport is considered and the steps being taken by TfL to help ensure that such a legacy can be realized are discussed. Such steps include policy-makers continuing to collaborate closely with the freight industry through the ‘London Freight Forum’, and TfL's efforts to encourage and support companies revising their delivery and collection times to the off-peak; improving freight planning in the design and management of TfL-funded road schemes; electronic provision of traffic information by TfL to the freight industry, and the further development of freight journey planning tools.

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Over the last 15 years, the acceleration in media consolidation has presented a series of policy challenges around diversity of editorial output. While policy debates on national ownership limits and other regulatory interventions are important, developments at the local level are often marginalised. And yet, the direction of travel—towards more consolidation and more deregulation—has arguably been more debilitating for democracy at the local level, where the vast majority of citizens interact with hospitals, schools, transport systems and local councils. The decline of local media—including, in some towns, the wholesale disappearance of local newspapers—leaves citizens starved of information and local institutions less accountable. This article uses an existing conceptual framework for assessing whether and how journalism makes a real-life contribution to democratic life at the local level. Against this normative framework, it then assesses the contribution of hyperlocal media sites to local democracy. We present findings from the most extensive survey of the hyperlocal sector to date, a collaboration with research partners at Cardiff and Birmingham City Universities and Talk About Local, which analysed online questionnaires from over 180 local online media initiatives. Our research offers a unique insight into the funding, operational problems and sustainability of community media sites, and suggests they have the potential to fulfil a vital democratic and civic role. These data inform our conclusions and recommendations for policy initiatives that would invigorate hyperlocal sites and therefore provide a real alternative for otherwise democratically impoverished local communities.

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Context: This critical reflection is set in the context of increasing marketisation in UK higher education, where students are seen as consumers, rather than learners with power. The paper explores the dark side of academic work and the compassion gap in universities, in order to make recommendations for practice development in higher education and the human services. Aims: The paper aims to show how reflexive dialogue can be used to enable the development of compassionate academic practice. Conclusions and Implications for Practice: Toxic environments and organisational cultures in higher education have compounded the crisis in compassionate care in the NHS. Implications for practice are: • Narrative approaches and critical appreciative inquiry are useful methods with which to reveal, and rectify, failures of compassion; • Courageous conversations are required to challenge dysfunctional organisational systems and processes; • Leadership development programmes should include the application of skills of compassion in organisational settings.

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As ameaças à segurança da informação, (INFOSEC) atentam contra a perda da respectiva confidencialidade, integridade e disponibilidade, pelo que as organizações são impelidas a implementar políticas de segurança, quer ao nível físico quer ao nível lógico, utilizando mecanismos específicos de defesa. O projecto Network Air Gap Controller (NAGC) foi concebido no sentido de contribuir para as questões da segurança, designadamente daquelas que se relacionam directamente com a transferência de informação entre redes de classificação de segurança diferenciadas ou de sensibilidades distintas, sem requisitos de comunicação em tempo real, e que mereçam um maior empenho nas condições de robustez, de disponibilidade e de controlo. Os organismos que, em razão das atribuições e competências cometidas, necessitam de fazer fluir informação entre este tipo de redes, são por vezes obrigados a realizar a transferência de dados com recurso a um processo manual, efectuado pelo homem e não pela máquina, que envolve dispositivos amovivéis, como sejam o CD, DVD, PEN, discos externos ou switches manuais. Neste processo, vulgarmente designado por Network Air Gap (NAG), o responsável pela transferência de dados deverá assumir de forma infalível, como atribuições intrínsecas e inalienáveis da função exercida, as garantias do cumprimento de um vasto conjunto de normas regulamentares. As regras estabelecidas desdobram-se em ferramentas e procedimentos que se destinam, por exemplo, à guarda em arquivo de todas as transferências efectuadas; à utilização de ferramentas de segurança (ex: antivírus) antes da colocação da informação na rede de classificação mais elevada; ao não consentimento de transferência de determinados tipos de ficheiro (ex: executáveis) e à garantia de que, em consonância com a autonomia que normalmente é delegada no elemento responsável pela operação das comunicações, apenas se efectuam transferências de informação no sentido da rede de classificação inferior para a rede de classificação mais elevada. Face ao valor da informação e do impacto na imagem deste tipo de organizações, o operador de comunicações que não cumpra escrupulosamente o determinado é inexoravelmente afastado dessas funções, sendo que o processo de apuramento de responsabilidades nem sempre poderá determinar de forma inequívoca se as razões apontam para um acto deliberado ou para factores não intencionais, como a inépcia, o descuido ou a fadiga. Na realidade, as actividades periódicas e rotineiras, tornam o homem propenso à falha e poderão ser incontornavelmente asseguradas, sem qualquer tipo de constrangimentos ou diminuição de garantias, por soluções tecnológicas, desde que devidamente parametrizadas, adaptadas, testadas e amadurecidas, libertando os recursos humanos para tarefas de manutenção, gestão, controlo e inspecção. Acresce que, para este tipo de organizações, onde se multiplicam o número de redes de entrada de informação, com diferentes classificações e actores distintos, e com destinatários específicos, a utilização deste tipo de mecanismos assume uma importância capital. Devido a este factor multiplicativo, impõe-se que o NAGC represente uma opção válida em termos de oferta tecnológica, designadamente para uma gama de produtos de baixíssimo custo e que possa desenvolver-se por camadas de contributo complementar, em função das reais necessidades de cada cenário.

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Mathematical Program with Complementarity Constraints (MPCC) finds many applications in fields such as engineering design, economic equilibrium and mathematical programming theory itself. A queueing system model resulting from a single signalized intersection regulated by pre-timed control in traffic network is considered. The model is formulated as an MPCC problem. A MATLAB implementation based on an hyperbolic penalty function is used to solve this practical problem, computing the total average waiting time of the vehicles in all queues and the green split allocation. The problem was codified in AMPL.

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Air pollution represents a serious risk not only to environment and human health, but also to historical heritage. In this study, air pollution of the Oporto Metropolitan Area and its main impacts were characterized. The results showed that levels of CO, PM10 and SO2 have been continuously decreasing in the respective metropolitan area while levels of NOx and NO2 have not changed significantly. Traffic emissions were the main source of the determined polycyclic aromatic hydrocarbons (PAHs; 16 PAHs considered by U.S. EPA as priority pollutants, dibenzo[a,l]pyrene and benzo[j]fluoranthene) in air of the respective metropolitan area. The mean concentration of 18 PAHs in air was 69.9±39.7 ng m−3 with 3–4 rings PAHs accounting for 75% of the total ΣPAHs. The health risk analysis of PAHs in air showed that the estimated values of lifetime lung cancer risks considerably exceeded the health-based guideline level. Analytical results also confirm that historical monuments in urban areas act as passive repositories for air pollutants present in the surrounding atmosphere. FTIR and EDX analyses showed that gypsum was the most important constituent of black crusts of the characterized historical monument Monastery of Serra do Pilar classified as “UNESCO World Cultural Heritage”. In black crusts, 4–6 rings compounds accounted approximately for 85% of ΣPAHs. The diagnostic ratios confirmed that traffic emissions were the major source of PAHs in black crusts; PAH composition profiles were very similar for crusts and PM10 and PM2.5.

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The IEEE 802.15.4 is the most widespread used protocol for Wireless Sensor Networks (WSNs) and it is being used as a baseline for several higher layer protocols such as ZigBee, 6LoWPAN or WirelessHART. Its MAC (Medium Access Control) supports both contention-free (CFP, based on the reservation of guaranteed time-slots GTS) and contention based (CAP, ruled by CSMA/CA) access, when operating in beacon-enabled mode. Thus, it enables the differentiation between real-time and best-effort traffic. However, some WSN applications and higher layer protocols may strongly benefit from the possibility of supporting more traffic classes. This happens, for instance, for dense WSNs used in time-sensitive industrial applications. In this context, we propose to differentiate traffic classes within the CAP, enabling lower transmission delays and higher success probability to timecritical messages, such as for event detection, GTS reservation and network management. Building upon a previously proposed methodology (TRADIF), in this paper we outline its implementation and experimental validation over a real-time operating system. Importantly, TRADIF is fully backward compatible with the IEEE 802.15.4 standard, enabling to create different traffic classes just by tuning some MAC parameters.

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This paper presents the new package entitled Simulator of Intelligent Transportation Systems (SITS) and a computational oriented analysis of traffic dynamics. The SITS adopts a microscopic simulation approach to reproduce real traffic conditions considering different types of vehicles, drivers and roads. A set of experiments with the SITS reveal the dynamic phenomena exhibited by this kind of system. For this purpose a modelling formalism is developed that embeds the statistics and the Laplace transform. The results make possible the adoption of classical system theory tools and point out that it is possible to study traffic systems taking advantage of the knowledge gathered with automatic control algorithms. A complementary perspective for the analysis of the traffic flow is also quantified through the entropy measure.