3,865 research outputs found
Status and management of tropical coastal fisheries in Asia
Coastal fisheries, Fishery management, Stock assessment, Conferences, Asia,
Average consensus and gossip algorithms in networks with stochastic asymmetric communications
We consider that a set of distributed agents desire to reach consensus on the average of their initial state values, while communicating with neighboring agents through a shared medium. This communication medium allows only one agent to transmit unidirectionally at a given time, which is true, e.g., in wireless networks. We address scenarios where the choice of agents that transmit and receive messages at each transmission time follows a stochastic characterization, and we model the topology of allowable transmissions with asymmetric graphs. In particular, we consider: (i) randomized gossip algorithms in wireless networks, where each agent becomes active at randomly chosen times, transmitting its data to a single neighbor; (ii) broadcast wireless networks, where each agent transmits to all the other agents, and access to the network occurs with the same probability for every node. We propose a solution in terms of a linear distributed algorithm based on a state augmentation technique, and prove that this solution achieves average consensus in a stochastic sense, for the special cases (i) and (ii). Expressions for absolute time convergence rates at which average consensus is achieved are also given
Fractal Photonic Crystal Waveguides
We propose a new class of one-dimensional (1D) photonic waveguides: the
fractal photonic crystal waveguides (FPCWs). These structures are photonic
crystal waveguides (PCWs) etched with fratal distribution of grooves such as
Cantor bars. The transmission properties of the FPCWs are investigated and
compared with those of the conventional 1D PCWs. It is shown that the FPCW
transmission spectrum has self-similarity properties associated with the
fractal distribution of grooves. Furthermore, FPCWs exhibit sharp localized
transmissions peaks that are approximately equidistant inside the photonic band
gap
Influence of anisotropic ion shape, asymmetric valency, and electrolyte concentration on structural and thermodynamic properties of an electric double layer
Grand canonical Monte Carlo simulation results are reported for an electric
double layer modelled by a planar charged hard wall, anisotropic shape cations,
and spherical anions at different electrolyte concentrations and asymmetric
valencies. The cations consist of two tangentially tethered hard spheres of the
same diameter, . One sphere is charged while the other is neutral. Spherical
anions are charged hard spheres of diameter . The ion valency asymmetry 1:2
and 2:1 is considered, with the ions being immersed in a solvent mimicked by a
continuum dielectric medium at standard temperature. The simulations are
carried out for the following electrolyte concentrations: 0.1, 1.0 and 2.0 M.
Profiles of the electrode-ion, electrode-neutral sphere singlet distributions,
the average orientation of dimers, and the mean electrostatic potential are
calculated for a given electrode surface charge, , while the contact
electrode potential and the differential capacitance are presented for varying
electrode charge. With an increasing electrolyte concentration, the shape of
differential capacitance curve changes from that with a minimum surrounded by
maxima into that of a distorted single maximum. For a 2:1 electrolyte, the
maximum is located at a small negative value while for 1:2, at a small
positive value.Comment: 10 pages, 6 figure
Double layer for hard spheres with an off-center charge
Simulations for the density and potential profiles of the ions in the planar
electrical double layer of a model electrolyte or an ionic liquid are reported.
The ions of a real electrolyte or an ionic liquid are usually not spheres; in
ionic liquids, the cations are molecular ions. In the past, this asymmetry has
been modelled by considering spheres that are asymmetric in size and/or valence
(viz., the primitive model) or by dimer cations that are formed by tangentially
touching spheres. In this paper we consider spherical ions that are asymmetric
in size and mimic the asymmetrical shape through an off-center charge that is
located away from the center of the cation spheres, while the anion charge is
at the center of anion spheres. The various singlet density and potential
profiles are compared to (i) the dimer situation, that is, the constituent
spheres of the dimer cation are tangentially tethered, and (ii) the standard
primitive model. The results reveal the double layer structure to be
substantially impacted especially when the cation is the counterion. As well as
being of intrinsic interest, this off-center charge model may be useful for
theories that consider spherical models and introduce the off-center charge as
a perturbation.Comment: 11 pages, 7 figure
Detection and resolution of normative conflicts in multi-agent systems : a literature survey
Peer reviewedPostprin
Ultimate strength and design of lipped channel columns experiencing local/distortional mode interaction - Part I: Experimental investigation
This paper reports the results of an experimental investigation aimed at assessing the post-buckling behaviour and ultimate strength of fixed-ended cold-formed steel lipped channel columns experiencing local/distortional mode interaction. A total of 26 columns were tested and the specimens were carefully selected to ensure various levels of local/distortional interaction effects (more or less close local and distortional critical stresses). The experimental results presented consist of the specimen geometries, material properties, initial imperfections, non-linear equilibrium paths and ultimate strength values. Since the collapse of most columns combines local and distortional deformations, these experimental results may be used to (i) assess the relevance of local/distortional interaction, (ii) calibrate and validate numerical simulations and (iii) provide experimental data aimed at developing a Direct Strength Method (DSM) approach to design cold-formed steel lipped channel columns against local/distortional interaction - such a DSM approach is addressed in Part II of this paper.published_or_final_versionThe 6th International Conference on Advances in Steel Structures in conjunction with IJSSD Symposium on Progress in Structural Stability and Dynamics & IStructE Asia-Pacific Forum (ICASS '09 / IJSSD / IStructE Asia-Pacific Forum), Hong Kong, China, 16-18 December 2009. In Proceedings of the 6th ICASS, 2009, v. 1, p. 460-46
Production and detection of doubly charmed tetraquarks
The feasibility of tetraquark detection is studied. For the cc\bar{u}\bar{d}
tetraquark we show that in present (SELEX, Tevatron, RHIC) and future
facilities (LHCb, ALICE) the production rate is promising and we propose some
detectable decay channels.Comment: 6 pages, 5 figure
Experiências da prática profissional na reabilitação: análise de um grupo de foco
O objetivo desta investigação foi reconhecer as perceções dos múltiplos intervenientes acerca dos problemas encontrados nos processos de reabilitação do património habitacional. Os dados foram recolhidos através de um inquérito orientado para um grupo de foco. O estudo contou com um total de 108 participantes, incluindo arquitetos, engenheiros, construtores e técnicos de construção e restauro e potenciais promotores. Os dados foram analisados com recurso a métodos de investigação qualitativa, nomeadamente análises temáticas e de conteúdo. Os resultados demonstram que os principais problemas identificados estão relacionados com a informação, com o fator económico, com a perceção social e a qualificação dos intervenientes. Foi também possível identificar aspetos positivos no processo, nomeadamente a motivação encontrada em participar na valorização do carácter dos lugares, mas também um maior reconhecimento dos contributos das técnicas tradicionais para a sustentabilidade. Os resultados demonstram que, para que as boas práticas de reabilitação sejam aplicadas de modo efetivo, é necessário melhorar a transmissão dessa informação para a prática profissional, criando ferramentas que permitam apoiar a tomada de decisão ponderada, considerando um leque mais abrangente de critérios para além do económico (como o impacte ambiental, a saúde dos ocupantes, ou o valor patrimonial).info:eu-repo/semantics/publishedVersio
Pentaquarks with One Color Sextet Diquark
The masses of pentaquarks are calculated within the framework of
a semirelativistic effective QCD Hamiltonian, using a diquark picture. This
approximation allows a correct treatment of the confinement, assumed here to be
similar to a Y-junction. With only color antitriplet diquarks, the mass of the
pentaquark candidate with positive parity is found around 2.2 GeV. It
is shown that, if a color sextet diquark is present, the lowest
pentaquark is characterized by a much smaller mass with a negative parity. A
mass below 1.7 GeV is computed, if the masses of the color antitriplet and
color sextet diquarks are taken similar
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