162 research outputs found
World city network integration in the Eurasian realm
A team of authors from the Globalization and World Cities (GaWC) research network explores the main empirical features of the global economic integration of Eurasia through an analysis of the (shifting) position of that macroregion's key cities. More specifically, they examine the gateway roles played by key cities in four major subregions-China, the former Eastern Bloc (FEB, i.e., Central and Eastern Europe), former Soviet Union (FSU), and India-in the channeling of transnational flows of capital, goods, knowledge, and people in 2000-2008, focusing on the globalization of firms in the financial and business service sectors. Although cities in the four subregions share a common recent history of transition from closed and state-centered to open and market-based economies, the study reveals the persistence of distinctive geographical idiosyncrasies in their connections across the globe
Partially Distributed Beamforming Design for RIS-Aided Cell-Free Networks
Cell-free networks are regarded as a promising technology to meet higher rate
requirements for beyond fifth-generation (5G) communications. Most works on
cell-free networks focus on either fully centralized beamforming to maximally
enhance system performance, or fully distributed beamforming to avoid extensive
channel state information (CSI) exchange among access points (APs). In order to
achieve both network capacity improvement and CSI exchange reduction, we
propose a partially distributed beamforming design algorithm for reconfigurable
intelligent surface (RIS)-aided cell-free networks. We aim at maximizing the
weighted sum-rate of all users by designing active and passive beamforming
subject to transmit power constraints of APs and unit-modulus constraints of
RIS elements. The weighted sum-rate maximization problem is first transformed
into an equivalent weighted sum-mean-square-error (sum-MSE) minimization
problem, and then alternating optimization (AO) approach is adopted to
iteratively design active and passive beamformer. Specifically, active
beamforming vectors are obtained by local APs and passive beamforming vector is
optimized by central processing unit (CPU). Numerical results not only
illustrate the proposed partially distributed algorithm achieves the remarkable
performance improvement compared with conventional local beamforming methods,
but also further show the considerable potential of deploying RIS in cell-free
networks.Comment: 5 pages, 4 figures, accepted by TV
A Dynamic Bioinspired Neural Network Based Real-Time Path Planning Method for Autonomous Underwater Vehicles
Real-time path planning for autonomous underwater vehicle (AUV) is a very difficult and challenging task. Bioinspired neural network (BINN) has been used to deal with this problem for its many distinct advantages: that is, no learning process is needed and realization is also easy. However, there are some shortcomings when BINN is applied to AUV path planning in a three-dimensional (3D) unknown environment, including complex computing problem when the environment is very large and repeated path problem when the size of obstacles is bigger than the detection range of sensors. To deal with these problems, an improved dynamic BINN is proposed in this paper. In this proposed method, the AUV is regarded as the core of the BINN and the size of the BINN is based on the detection range of sensors. Then the BINN will move with the AUV and the computing could be reduced. A virtual target is proposed in the path planning method to ensure that the AUV can move to the real target effectively and avoid big-size obstacles automatically. Furthermore, a target attractor concept is introduced to improve the computing efficiency of neural activities. Finally, some experiments are conducted under various 3D underwater environments. The experimental results show that the proposed BINN based method can deal with the real-time path planning problem for AUV efficiently
Pathways of change : shifting connectivities in the world city network, 2000-08
This is an empirical paper that measures and interprets changes in intercity relations at the global scale in the period 2000-08. It draws on the network model devised by the Globalization and World Cities (GaWC) research group to measure global connectivities for 132 cities across the world in 2000 and 2008. The measurements for both years are adjusted so that a coherent set of services/cities is used. A range of statistical techniques is used to explore these changes at the city level and the regional scale. The most notable changes are: the general rise of connectivity in the world city network; the loss of global connectivity of US and sub-Saharan African cities (Los Angeles, San Francisco and Miami in particular); and, the gain in global connectivity of south Asian, Chinese and eastern European cities (Shanghai, Beijing and Moscow in particular)
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