4,559 research outputs found
Distributed Lagrangian Methods for Network Resource Allocation
Motivated by a variety of applications in control engineering and information
sciences, we study network resource allocation problems where the goal is to
optimally allocate a fixed amount of resource over a network of nodes. In these
problems, due to the large scale of the network and complicated
inter-connections between nodes, any solution must be implemented in parallel
and based only on local data resulting in a need for distributed algorithms. In
this paper, we propose a novel distributed Lagrangian method, which requires
only local computation and communication. Our focus is to understand the
performance of this algorithm on the underlying network topology. Specifically,
we obtain an upper bound on the rate of convergence of the algorithm as a
function of the size and the topology of the underlying network. The
effectiveness and applicability of the proposed method is demonstrated by its
use in solving the important economic dispatch problem in power systems,
specifically on the benchmark IEEE-14 and IEEE-118 bus systems
On the convergence rate of distributed gradient methods for finite-sum optimization under communication delays
Motivated by applications in machine learning and statistics, we study
distributed optimization problems over a network of processors, where the goal
is to optimize a global objective composed of a sum of local functions. In
these problems, due to the large scale of the data sets, the data and
computation must be distributed over processors resulting in the need for
distributed algorithms. In this paper, we consider a popular distributed
gradient-based consensus algorithm, which only requires local computation and
communication. An important problem in this area is to analyze the convergence
rate of such algorithms in the presence of communication delays that are
inevitable in distributed systems. We prove the convergence of the
gradient-based consensus algorithm in the presence of uniform, but possibly
arbitrarily large, communication delays between the processors. Moreover, we
obtain an upper bound on the rate of convergence of the algorithm as a function
of the network size, topology, and the inter-processor communication delays
HD101584: Circumstellar characteristics and evolutionary status
We have performed a study of the characteristics of the circumstellar
environment of the binary object HD101584, that provides information on a
likely evolutionary scenario. We have obtained and analysed ALMA observations,
complemented with observations using APEX, of a large number of molecular
lines. An analysis of the spectral energy distribution has also been performed.
Emissions from 12 molecular species (not counting isotopologues) have been
observed, and most of them mapped with angular resolutions in the range 0.1" to
0.6". Four circumstellar components are identified: i) a central compact source
of size 0.15", ii) an expanding equatorial density enhancement (a flattened
density distribution in the plane of the orbit) of size 3", iii) a bipolar
high-velocity outflow (150 km/s), and iv) an hourglass structure. The outflow
is directed almost along the line of sight. There is evidence of a second
bipolar outflow. The mass of the circumstellar gas is 0.5[D/1 kpc]^2 Msun,
about half of it lies in the equatorial density enhancement. The dust mass is
0.01[D/1 kpc]^2 Msun, and a substantial fraction of this is in the form of
large-sized, up to 1 mm, grains. The estimated kinetic age of the outflow is
770[D/1 kpc] yr. The kinetic energy and the scalar momentum of the accelerated
gas are estimated to be 7x10^(45)[D/1 kpc]^2 erg and 10^(39)[D/1 kpc]^2 g cm/s,
respectively. We provide good evidence that the binary system HD101584 is in a
post-common-envelope-evolution phase, that ended before a stellar merger.
Isotope ratios combined with stellar mass estimates suggest that the primary
star's evolution was terminated already on the first red giant branch (RGB).
Most of the energy required to drive the outflowing gas was probably released
when material fell towards the companion.Comment: Accepted for publication in A&
Achieving sub-diffraction imaging through bound surface states in negative-refracting photonic crystals at the near-infrared
We report the observation of imaging beyond the diffraction limit due to
bound surface states in negative refraction photonic crystals. We achieve an
effective negative index figure-of-merit [-Re(n)/Im(n)] of at least 380, ~125x
improvement over recent efforts in the near-infrared, with a 0.4 THz bandwidth.
Supported by numerical and theoretical analyses, the observed near-field
resolution is 0.47 lambda, clearly smaller than the diffraction limit of 0.61
lambda. Importantly, we show this sub-diffraction imaging is due to the
resonant excitation of surface slab modes, allowing refocusing of
non-propagating evanescent waves
Young adults' environmental attitudes and purchase intention in Vietnam
Vietnam is one of the fastest growing economies in South East Asia with a rapidly growing (but relatively young) middle class. With the rise in the middle class has come a commensurate rise in household consumption. This paper presents the findings of a survey into attitudes towards the environment and the pro-environmental behaviours of young people in Ha Noi and Ho Chi Minh City (HCMC) Vietnam. The results suggest that environmental considerations are not taken into account in young Vietnamese adults' purchase intentions. This is more evident in expressive purchases, but also to some degree in utilitarian purchases
Education Abroad and Foreign Training of Students and Specialists as an Effective Incentive of Increasing the Level of Human Capital Development in the Forestry of Vietnam
The article examines a number of current phenomena characteristic of the processes of human capital development in the framework of international education and internships. In particular, an analysis was made of the distribution of the number of people leaving for study in host countries for students from such Asian-Pacific countries as Vietnam and China; motives and incentives are grouped into two large groups that influence the decision of a particular student’s parents to send them to foreign studies; analyzed the modern form of combining higher education with internships in well-known and attractive for students from abroad companies of the “host” country, which is an effective functional and image reception in the arsenal of marketing tools of universities that are highly competitive in the global higher education market for solvent customers. The key elements of improving the quality of “human capital” during the training of Vietnamese students in universities of St. Petersburg are identified.The study concluded that Russian universities, in particular those connected with the training of specialists for the forestry complex, should more actively promote their educational services in Vietnam, pointing to the presence of modern technological and educational base, actual use of knowledge and technologies that are used in leading companies in the forest industry of Canada, Scandinavia, USA, Russia
An introduction to crowdsourcing for language and multimedia technology research
Language and multimedia technology research often relies on
large manually constructed datasets for training or evaluation of algorithms and systems. Constructing these datasets is often expensive with significant challenges in terms of recruitment of personnel to carry out the work. Crowdsourcing methods using scalable pools of workers available on-demand offers a flexible means of rapid low-cost construction of many of these datasets to support existing research requirements and potentially promote new research initiatives that would otherwise not be possible
AGV Trajectory Control Based on Laser Sensor Navigation
Autonomous Guided Vehicle Systems (AGVs) are used to transport goods and products in manufacturing fields where navigation can be done in a structured environment. In order to track the given trajectory, a tracking control based on Lyapunov stability theory is introduced. The use of the nonlinear Lyapunov technique provides robustness for load disturbance and sensor noise. To apply Lyapunov\u27s theorem, the kinematic model of AGV is given. To recognize its position in indoor environment, in this paper, a laser sensor device NAV200 is used to detect the AGV position in real-time. For simulation and experiment, software and hardware are described. The AGV consists of 4 wheels with two passive wheels and two driving wheels. A controller is developed based on industrial computer. The effectiveness of the proposed controller is proved by simulation and experimental results.[AGV Trajectory Control, Laser Sensor Navigation
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