517 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
IR, area studies and IPE: rethinking the study of China's international relations
No full textThis paper attempts to provide a new framework of analysis for understanding China’s international relations. It argues that “traditional” conceptions of international relations, based on “statist” and “realist” methodology, do not capture the dynamics of China’s international relations in an era of globalisation. Rather, we need to consider the analytical tools of international political economy as a means of breaking down the analytical barriers between the domestic and the international, and between politics and economics. At the same time as enriching the study of China, such an approach can also enrich the discipline of international political economy, by breaking away from the OECD-centric nature of much research in the field
Chemical transformation of a long-chain alkyl organosulfate via heterogeneous OH oxidation : a case study of sodium dodecyl sulfate
No full text202308 bcchVersion of RecordRGCOthersLi Ka Shing FoundationPublishedC
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
Models of Magnetic System in the High Magnetic Field
No full textFrom the historical point of view, the invention of the magnetic model is to describe the microscopic phase transition phenomena or the critical
behavior of the variety of physical systems. The simplest magnetic model is called Ising model where each site can have two values (+1 and -1) and
interactions only occur at neighboring sites. The model was rstly proposed by Wihelm Lenz (1920) in order to explain ferromagnetism from microscopic rst principles. Ernst Ising revisited the model in 1925 and solved the one-dimensional case. He found that there was no phase transition (or say Tc=0), and then roughly argued the same result in the higher
dimensional case. However, Dramers and Wannier (1941) gave the finite Tc result qualitatively, and Lars Onsager (1944) derived the analytic free energy and gave the nite Tc result quantitatively. Both of them studied the two-dimensional case, and disproved the Ising's prediction. Ising model,
as a harbinger of the microscopic model, has been becoming one of the pillars of statistical mechanics.
There are lots of models after Ising. Heisenberg model (1928), for instance, is the most essential and representative model. There are three quantum spin components in it, and the non-commutability of the components leads to the quantum nature of the model. Throughout the thesis I divide into two topics about magnetic systems. One is classical and the other is quantum mechanical. Before start-
ing I must explain what are the differences between classical and quantum spins. Generally we should denote the spin as an operator whose components adopt the commutation relations, Si;Sj =ihei jkSk. “Classical” means that one can take h!0 and thus all the components are com-
mutable. This can be done when the temperature is high or the spin value is huge. Another possibility is due to some kinds of anisotropic limit (Jx,Jy << Jz) such that only z-component exists in the model (Ising), and we regard it as “classical” rather than “quantum”.
Firstly I discuss the classical antiferromagnetic Ising chain with single-ion anisotropy term. I will use the transfer matrix method to find the analytic solvability of the one-dimensional Ising case even when the extra
nonlinear term was added. In addition, I also propose a new method to deal with such a problem without solving the eigenvalue problems.
In the second part I will start from a recently discovered magnetic material, called Han purple with the structure of quantum magnetic dimmer. Under the high magnetic eld this material will present BEC phenomena which has been discovered by the experiment and analyzed by numerical works recently. However, in these works they made some artifial transformation to study the model. In this thesis I will use a new mean field method to theoretically understand the physical insight of this material, and compare the analytical result with the experiment and the QMC (Quantum Monte Carlo) simulation.1 Exact ground-state phase diagram of antiferromagnetic Ising spin-S (S 1) chain in external magnetic eld and with single-ion anisotropy 1
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 S=1 Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 S= 3
2 and S=2 Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Rules and the General Case S=s, s= 1
2 ;1; 3
2 ;2; 5
2 ; : : : . . . . . . . . 6
1.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.7 Appendix 1. Details about the transition lines of the general case S=s,
s= 1
2 ;1; 3
2 ;2; 5
2 ; : : : in h-D diagram. . . . . . . . . . . . . . . . . . 8
1.8 Appendix 2. Proof of the spin con guration which is only to be bipartite. 9
2 Magnetic Quantum Phase Transition of Han Purple 19
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2 Mapping from Spin to Bond Operator . . . . . . . . . . . . . . . . . 20
2.3 Mean Field of the Hamiltonian . . . . . . . . . . . . . . . . . . . . . 23
2.4 Excitations of the Mean Field Hamiltonian . . . . . . . . . . . . . . . 27
2.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.6 Appendix 1 De nitions of the notations in (2.52) . . . . . . . . . . . 32
2.7 Appendix 2 De nitions of the notations in (2.74) . . . . . . . . . . . 3
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
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