509 research outputs found
Why Torture?
No full textI develop a framework to account for torture, which I argue should be understood with reference to international relations. I show that torture is intended as a tool to ensure the security, stability and legitimacy of elites, often transnationally, but there is often a disjuncture between its intended and actual outcomes. Despite dominant claims that torture is used to defeat security threats, most torture is intended to deter political opposition and secure legitimacy for elites. I conclude that torture should be renounced, both on moral grounds, and because it is not necessary for the functions it is intended to serve
Coordination of Multiple Robotic Fish With Applications to Underwater Robot Competition
No full textThis paper is concerned with the coordination control of multiple biomimetic robotic fish in highly dynamic aquatic environments by building a hybrid centralized system. With the aid of the results of biorobotics and control techniques, a radio-controlled multijoint robotic fish and its locomotion control are developed. To enable a closed control loop, a visual subsystem that is responsible for tracking of multiple moving objects is constructed and implemented in real time. Furthermore, a behavior-based hierarchical architecture in conjunction with fuzzy reinforcement learning is proposed to accomplish effective coordination among multiple swimming robots. Finally, experiments on 2vs2 water polo game are carried out to verify the proposed coordination control scheme. Over the past eight years, this multirobot platform has been successfully applied to international underwater robot competitions to promote innovative research and education in underwater robotics
On C1 classifications of hyperbolic vector fields
No full textAbstractIn this paper we study smooth classification of hyperbolic vector fields based on their linear approximations only and obtain the following. On Rn, n⩽5, with only two kinds of exceptions, any two hyperbolic vector fields with generic nonlinear parts ẋ=A1x+⋯ and ẏ=A1y+⋯, where Ai are n×n matrices, are C1 conjugate to each other if and only if A1 and A2 are strictly similar, and they are C1 orbitally equivalent if and only if A1 and A2 are similar
Phylogenetic lineages in the Capnodiales
No full textThe Capnodiales incorporates plant and human pathogens, endophytes, saprobes and epiphytes, with a wide range of nutritional modes. Several species are lichenised, or occur as parasites on fungi, or animals. The aim of the present study was to use DNA sequence data of the nuclear ribosomal small and large subunit RNA genes to test the monophyly of the Capnodiales, and resolve families within the order. We designed primers to allow the amplification and sequencing of almost the complete nuclear ribosomal small and large subunit RNA genes. Other than the Capnodiaceae (sooty moulds), and the Davidiellaceae, which contains saprobes and plant pathogens, the order presently incorporates families of major plant pathological importance such as the Mycosphaerellaceae, Teratosphaeriaceae and Schizothyriaceae. The Piedraiaceae was not supported, but resolves in the Teratosphaeriaceae. The Dissoconiaceae is introduced as a new family to accommodate Dissoconium and Ramichloridium. Lichenisation, as well as the ability to be saprobic or plant pathogenic evolved more than once in several families, though the taxa in the upper clades of the tree lead us to conclude that the strictly plant pathogenic, nectrotrophic families evolved from saprobic ancestors (Capnodiaceae), which is the more primitive stat
The Kowalevskaya exponents and rational integrability of polynomial differential systems
No full textAbstractThis paper primarily grows from the paper of Llibre and Zhang [J. Llibre, X. Zhang, Polynomial first integrals for quasi-homogeneous polynomial differential systems, Nonlinearity 15 (2002) 1269–1280] with the following essential generalizations: (i) we prove that the link established in the mentioned paper between the Kowalevskaya exponents and the degree of the polynomial first integrals holds not only for (1,…,1)-2 type systems but also for any (s1,…,sn)-d type systems. (ii) by using different methods, we obtain necessary and sufficient conditions for planar (s1,s2)-d systems to have rational first integrals, whereas in the mentioned paper, only (s1,s2)-2 type systems and only polynomial integrability are considered.As an application of the methods and the results, we present an illustrative and well studied example to show its non-existence of polynomial first integrals
Stationary solution and parametric estimation for Bilinear model driven by ARCH noises
No full textBilinear model driven by ARCH (1) noises is proposed. Existence, uniqueness and form of stationary solution to this new model are presented. Maximum likelihood estimation of the model is discussed and some simulation results are given to evaluate our algorithm.link_to_subscribed_fulltex
On tail behaviour of nonlinear autoregressive functional conditional heteroscedastic model with heavy-tailed innovations
No full textWe study the tail probability of the stationary distribution of nonparametric nonlinear autoregressive functional conditional heteroscedastic (NARFCH) model with heavy-tailed innovations. Our result shows that the tail of the stationary marginal distribution of an NARFCH series is heavily dependent on its conditional variance. When the innovations are heavy-tailed, the tail of the stationary marginal distribution of the series will become heavier or thinner than that of its innovations. We give some specific formulas to show how the increment or decrement of tail heaviness depends on the assumption on the conditional variance function. Some examples are given
Bond-versus-site doping models for the off-chain-doped Haldane-gap system Y2BaNiO5
No full textUsing the density matrix renormalization-group technique, we calculate the impurity energy levels for two different effective models of off-chain doping for quasi-one-dimensional Heisenberg chain compound Y2BaNiO5: ferromagnetic bond doping and antiferromagnetic site spin-1/2 doping. Thresholds of the impurity strength for the appearance of localized slates are found for both models. However, the ground-state and low-energy excitations for weak impurity strength are different for these two models and the difference can be detected by experiments. [S0163-1829(98)07640-1].http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000077295500038&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, Condensed MatterSCI(E)5ARTICLE1912672-126755
Antiferromagnetic spin-1 XYZ model with the Dzyaloshinskii–Moriya interaction
No full text© 2022, The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature.Antiferromagnetic spin-1 XYZ model is examined by using a mean-field approach with the introduction of spin operators on the simple cubic lattice. The model includes the crystal field interaction (Dz) along the z-axis, the Dzyaloshinskii–Moriya interaction (Δ m) and an external magnetic field with the components of Hx= Hy= Hz= H. The bilinear exchange interaction parameter (Jz) is taken as a scaling parameter chosen to be negative to simulate the antiferromagnetic interactions between the nearest-neighbor spins. Thermal variations of the total magnetization and its components are investigated in detail to obtain the phase diagrams on the (H/ | Jz| , T/ | Jz|) , (Dz/ | Jz| , T/ | Jz|) and (Δ m/ | Jz| , T/ | Jz|) planes. The model exhibits antiferromagnetic, paramagnetic and random phase regions. Very interesting various phase lines and critical points are observed including the tricritical points, bicritical points, critical end points and two more. The reentrant behavior is also observed for appropriate values of the system parameters
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