154 research outputs found

    Hydrodynamic modelling and estimation of exchange rates for Bardawil Lagoon, Egypt. An investigation of governing forces and physical processes using numerical models.

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    Bardawil Lagoon, a natural lagoon located on the northern coast of the Sinai Peninsula, Egypt, there are three inlets of which two are man-made connecting the lagoon with the Mediterranean Sea. The inlets are subjected to changes in morphology, due to sediment transport, over time and this may lead to degrees of closure of either inlet. The sediment transport is governed by longshore currents and the sediments originate from the eroding Nile delta. Inlet closure adversely affects the lagoon water quality which will have a detrimental effect on the ecosystem. In this dissertation the dominant coastal processes governing the water exchange between the lagoon and the Mediterranean are studied. Finite element conceptual computer models are applied to simulate and investigate the hydrodynamics of the inlets and the lagoon itself. Two types of models are applied within the Surface Modelling System (SMS) software; ADCIRC, a regional tidal model and CMS-Flow, a local circulation model. In order to estimate the exchange rate of the lagoon two methods are utilized; based on net intertidal volume and cross sectional flow through the inlets. The methods show a high degree of correlation. The renewal time was estimated to 9.0 days, which is equivalent to a daily replaced volume of 53?106 m3. Tidal forcing governs the water exchange while wind is responsible for the internal circulation

    Guaranteed Employment Plans

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    Att skapa genom att koda Àr ett nytt och spÀnnande sÀtt att gestalta konst, lÀra sig att koda eller bara ha roligt. Denna rapports syfte Àr att utforska hur en sÄdan upplevelse kan göras mer interaktiv och intuitiv för anvÀndaren samt hur sÄdan funktionalitet kan implementeras. Som bas för detta ligger en explorativ fallstudie av det arbete som projektgruppen har utfört för att förbÀttra hemsidan för CodeArt. Det visar sig att ökad anvÀndarupplevelse kan uppnÄs med hjÀlp av implementation av olika verktyg och funktioner, i detta fall livekodning, versionshantering, hjÀlptexter och ett loggningsverktyg

    FyrverkeritĂ„rtors vĂ€ltningsbenĂ€genhet – en studie i fyrverkerisĂ€kerhet och testmetodik

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    This report is a study in fireworks safety with emphasis on the safety issues considering multiple tube devices. The report was produced in order to facilitate the examination of the risks of firework cakes tipping over during firing, as well as providing support for future studies. The availability of detailed Swedish statistics regarding accidents involving fireworks has proven to be deficient, so foreign statistics must be taken into consideration. The report proposes a method for testing the tip-over propensity of multiple tube devices that can be used as a tool for classification of new products. The method in its current form should be considered as the foundation in a developing and validation process that could lead to a standardized test method for testing the tip-over propensity of multiple tube devices

    Distributed Charging Coordination of Electric Trucks with Limited Charging Resources

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    Electric trucks usually need to charge their batteries during long-range delivery missions, and the charging times are often nontrivial. As charging resources are limited, waiting times for some trucks can be prolonged at certain stations. To facilitate the efficient operation of electric trucks, we propose a distributed charging coordination framework. Within the scheme, the charging stations provide waiting estimates to incoming trucks upon request and assign charging ports according to the first-come, first-served rule. Based on the updated information, the individual trucks compute where and how long to charge whenever approaching a charging station in order to complete their delivery missions timely and cost-effectively. We perform empirical studies for trucks traveling over the Swedish road network and compare our scheme with the one where charging plans are computed offline, assuming unlimited charging facilities. It is shown that the proposed scheme outperforms the offline approach at the expense of little communication overhead.Comment: Paper for ECC 202

    Large-Scale Multi-Fleet Platoon Coordination: A Dynamic Programming Approach

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    Truck platooning is a promising technology that enables trucks to travel in formations with small inter-vehicle distances for improved aerodynamics and fuel economy. The real-world transportation system includes a vast number of trucks owned by different fleet owners, for example, carriers. To fully exploit the benefits of platooning, efficient dispatching strategies that facilitate the platoon formations across fleets are required. This paper presents a distributed framework for addressing multi-fleet platoon coordination in large transportation networks, where each truck has a fixed route and aims to maximize its own fleet's platooning profit by scheduling its waiting times at hubs. The waiting time scheduling problem of individual trucks is formulated as a distributed optimal control problem with continuous decision space and a reward function that takes non-zero values only at discrete points. By suitably discretizing the decision and state spaces, we show that the problem can be solved exactly by dynamic programming, without loss of optimality. Finally, a realistic simulation study is conducted over the Swedish road network with 5,0005,000 trucks to evaluate the profit and efficiency of the approach. The simulation study shows that, compared to single-fleet platooning, multi-fleet platooning provided by our method achieves around 1515 times higher monetary profit and increases the CO2_2 emission reductions from 0.4%0.4\% to 5.5%5.5\%. In addition, it shows that the developed approach can be carried out in real-time and thus is suitable for platoon coordination in large transportation systems.Comment: IEEE Transactions on Intelligent Transportation Systems, accepte

    Locally finitely presented categories and functor rings

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    In this paper, 40 Gbaud transmission of single polarization (SP) and Polarization-Multiplexed (PM), RZ-DQPSK and RZ-D8PSK signals is analyzed numerically. The impact of nonlinear crosstalk arising from the presence of neighbouring intensity-modulated channels is analyzed in terms of required OSNR for the BER of 10-3versus launch power.QC 20120607</p

    Hub-Based Platoon Formation: Optimal Release Policies and Approximate Solutions

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    This paper studies the optimal hub-based platoon formation at hubs along a highway under decentralized, distributed, and centralized policies. Hubs are locations along highways where trucks can wait for other trucks to form platoons. A coordinator at each hub decides the departure time of trucks, and the released trucks from the hub will form platoons. The problem is cast as an optimization problem where the objective is to maximize the platooning reward. We first show that the optimal release policy in the decentralized case, where the hubs do not exchange information, is to release all trucks at the hub when the number of trucks exceeds a threshold computed by dynamic programming. We develop efficient approximate release policies for the dependent arrival case using this result. To study the value of information exchange among hubs on platoon formation, we next study the distributed and centralized platoon formation policies which require information exchange among hubs. To this end, we develop receding horizon solutions for the distributed and centralized platoon formation at hubs using the dynamic programming technique. Finally, we perform a simulation study over three hubs in northern Sweden. The profits of the decentralized policies are shown to be approximately 3.5% lower than the distributed policy and 8% lower than the centralized release policy. This observation suggests that decentralized policies are prominent solutions for hub-based platooning as they do not require information exchange among hubs and can achieve a similar performance compared with distributed and centralized policies.Comment: Accepted for T-ITS 202
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