404,161 research outputs found

    Modeling and control of complex dynamic systems: Applied mathematical aspects

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    The concept of complex dynamic systems arises in many varieties, including the areas of energy generation, storage and distribution, ecosystems, gene regulation and health delivery, safety and security systems, telecommunications, transportation networks, and the rapidly emerging research topics seeking to understand and analyse. Such systems are often concurrent and distributed, because they have to react to various kinds of events, signals, and conditions. They may be characterized by a system with uncertainties, time delays, stochastic perturbations, hybrid dynamics, distributed dynamics, chaotic dynamics, and a large number of algebraic loops. This special issue provides a platform for researchers to report their recent results on various mathematical methods and techniques for modelling and control of complex dynamic systems and identifying critical issues and challenges for future investigation in this field. This special issue amazingly attracted one-hundred-and eighteen submissions, and twenty-eight of them are selected through a rigorous review procedure

    Analytical Estimation of the Beam-Beam Interaction Limited Dynamic Apertures and Lifetimes in e^+e^- Circular Colliders

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    Physically speaking, the delta function like beam-beam nonlinear forces at interaction points (IPs) act as a sum of delta function nonlinear multipoles. By applying the general theory established in ref. 1, in this paper we investigate analytically the beam-beam interaction limited dynamic apertures and the corresponding beam lifetimes for both the round and the flat beams. Relations between the beam-beam limited beam lifetimes and the beam-beam tune shifts are established, which show clearly why experimentally one has always a maximum beam-beam tune shift, \xi_{y, max}, around 0.045 for e-^+e$^- circular colliders, and why one can use round beams to double this value approximately. Comparisons with some machine parameters are given. Finally, we discuss the mechanism of the luminosity reduction due to a definite collision crossing angle.Comment: 25 page

    The Role of Ecotourism in the Sustainable Development of Qinkou village, Yunnan, China, 2001 to 2013

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    This study captures evidence of the changes to Qinkou village during the period it was developed as an example of ecotourism in Yunnan province, Southwest China; a process which began in 2001. By examining the aims of the development projects and changes which happened in the village in 2001, 2006 and 2013 respectively, the paper aims to explore how traditions have been understood and deployed with regard to the built environment in Qinkou. It also investigates the shift in focus of academic research into traditional and sustainable development of rural villages over different periods. In 2001, a development project was implemented in Qinkou to demonstrate how tourism could be used as a way to modernise the village. The local government of the Honghe Hani and Yi Autonomous Prefecture, where the village is located, worked with academics in the fields of architecture, planning and anthropology to develop the plan and to obtain funding to transform Qinkou into an ecotourism village. By 2006, the infrastructure of the village had been significantly improved. However, many originally planned activities could not be carried out due to the lack of ongoing funding support and effective management. Tourism alone was unable to bring fundamental changes in Qinkou. Instead, many villagers who worked in the cities returned with savings from the higher incomes enjoyed in the cities and also brought back changed lifestyles that contributed further major transformation. At the same time, the village remained a coherent settlement. The head of the village and management group organised many village co-operative activities. Academic research at the time, on the other hand, focused more on the examination of the cultural symbols of the local families and built environment than providing advice to help the village improve living conditions. In 2013, an application for the spectacular stepped paddy fields in the Prefecture to be listed as a World Heritage Site attracted significant funding from the local government. Qinkou was included in the development master plan; however, the development project for the village focused primarily on the preservation of the traditional forms as cultural symbols. Academic research and local policies discussed needs for sustainable development in order to comply with the requirements of the UNSCO process for World Heritage Site listing. Yet, details of how to achieve social and cultural cohesion remained missing. This paper argues that tourism development in the market-oriented economy now operating in China has worked as the catalyst for the transformation of the village and improvement of living conditions. However, social-cultural sustainable regeneration of rural settlements must create places for the needs of different groups in the local community. The academic research also needs to reinterpret the traditions that were formed and changed by the local communities in a way that is perhaps more diverse and flexible than the previous academic research defined

    Maiter: An Asynchronous Graph Processing Framework for Delta-based Accumulative Iterative Computation

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    Myriad of graph-based algorithms in machine learning and data mining require parsing relational data iteratively. These algorithms are implemented in a large-scale distributed environment in order to scale to massive data sets. To accelerate these large-scale graph-based iterative computations, we propose delta-based accumulative iterative computation (DAIC). Different from traditional iterative computations, which iteratively update the result based on the result from the previous iteration, DAIC updates the result by accumulating the "changes" between iterations. By DAIC, we can process only the "changes" to avoid the negligible updates. Furthermore, we can perform DAIC asynchronously to bypass the high-cost synchronous barriers in heterogeneous distributed environments. Based on the DAIC model, we design and implement an asynchronous graph processing framework, Maiter. We evaluate Maiter on local cluster as well as on Amazon EC2 Cloud. The results show that Maiter achieves as much as 60x speedup over Hadoop and outperforms other state-of-the-art frameworks.Comment: ScienceCloud 2012, TKDE 201

    Interpreting Quantum Mechanics in Terms of Random Discontinuous Motion of Particles

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    This thesis is an attempt to reconstruct the conceptual foundations of quantum mechanics. First, we argue that the wave function in quantum mechanics is a description of random discontinuous motion of particles, and the modulus square of the wave function gives the probability density of the particles being in certain locations in space. Next, we show that the linear non-relativistic evolution of the wave function of an isolated system obeys the free Schrödinger equation due to the requirements of spacetime translation invariance and relativistic invariance. Thirdly, we argue that the random discontinuous motion of particles may lead to a stochastic, nonlinear collapse evolution of the wave function. A discrete model of energy-conserved wavefunction collapse is proposed and shown to be consistent with existing experiments and our macroscopic experience. In addition, we also give a critical analysis of the de Broglie-Bohm theory, the many-worlds interpretation and dynamical collapse theories, and briefly analyze the problem of the incompatibility between quantum mechanics and special relativity
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