Magnesium diboride superconductors for magnet applications

With the discovery of its superconducting properties in 2001, MgB2 is the latest superconductor for use in large scale applications such as superconducting magnets.\ud Compared to other metallic superconductors like Nb-Ti and Nb3Sn, it has the\ud advantage of a higher Tc (40 K), which enables magnets to operate at higher temperatures (» 20 K) and cuts down cooling costs. Compared to high-Tc conductors such as YBa2Cu3Ox and Bi2Sr2Ca2Cu3Ox on the other hand, it is a relatively simple compound and therefore easier to synthesise. Together with the abundance of magnesium and boron, this causes its presently estimated cost-to-performance ratio to be a factor of » 100 lower than that of high-Tc conductors

On the relationship between the open-loop Nash equilibrium in LQ-games and the inertia of a matrix

In this paper we consider the location of the eigenvalues of the composite matrix ( -A S1 S2 ) ( Q1 At 0 ) ( Q2 0 At ) , where the matrices Si and Qi are assumed to be semi-positive definite. Two interesting observations, which are not or only partially mentioned in literature before, challenge this study. The first observation is that this matrix appears naturally in a both necessary and sufficient condition for the existence of a unique open-loop Nash solution in the 2-player linear-quadratic dynamic game and, more in particular, its inertia play an important role in the analysis of the convergence of the associated state in this game. The second observation is that from the eigenvalue and eigenstructure of this matrix all solutions for the algebraic Riccati equations corresponding with the above mentioned dynamic game can be directly calculated and, moreover, also the eigenvalues of the associated closed-loop system. Simulation experiments suggest that the composite matrix will have at least n eigenvalues (here n is the state dimension of the system) with a positive real part. Unfortunately, it turns out that this property of the inertia of this matrix in general does not hold. Some specific cases for which the property does hold are discussed.Game Theory;Nash Equilibrium;game theory

A Result on Output Feedback Linear Quadratic Control

In this note we consider the static output feedback linear quadratic control problem.We present both necessary and sufficient conditions under which this problem has a solution in case the involved cost depend only on the output and control variables.This result is used to present both necessary and sufficient conditions under which the corresponding linear quadratic differential game has a Nash equilibrium in case the players use static output feedback control.LQ theory;Algebraic Riccati equations;Differential games

Spectral and polarization study of the double relics in Abell 3376 using the GMRT and the VLA

Double radio relics in galaxy clusters are rare phenomena that trace shocks in the outskirts of merging galaxy clusters. We have carried out a spectral and polarization study of the spectacular double relics in the galaxy cluster A3376 using the Giant Metrewave Radio Telescope at 150 and 325 MHz and the Very Large Array at 1400 MHz. The polarization study at 1400 MHz reveals a high degree of polarization (~30%) and aligned magnetic field vectors (not corrected for Faraday rotation) in the eastern relic. A highly polarized (>60%) filamentary radio source of size ~300 kpc near the eastern relic and north of the bent-jet radio galaxy is detected for the first time. The western relic is less polarized and does not show aligned magnetic field vectors. The distribution of spectral indices between 325 and 1400 MHz over the radio relics show steepening from the outer to the inner edges of the relics. The spectral indices of the eastern and the western relics imply Mach numbers in the range 2.2 to 3.3. Remarkable features such as the inward filament extending from the eastern relic, the highly polarized filament, the complex polarization properties of the western relic and the separation of the BCG from the ICM by a distance >900 kpc are noticed in the cluster. A comparison with simulated cluster mergers is required to understand the complex properties of the double relics in the context of the merger in A3376. An upper limit (log(P(1.4GHz) W/Hz < 23.0) on the strength of a Mpc size radio halo in A3376 is estimated.Comment: 9 pages, 4 figures, accepted for publication in MNRA

Asymptotic analysis of Nash equilibria in nonzero-sum linear-quadratic differential games: The two player case

Game Theory;Nash Equilibrium

Mapping Diversity of Publication Patterns in the Social Sciences and Humanities: An Approach Making Use of Fuzzy Cluster Analysis

&lt;b&gt;Purpose:&lt;/b&gt; To present a method for systematically mapping diversity of publication patterns at the author level in the social sciences and humanities in terms of publication type, publication language and co-authorship.&lt;br&gt;&lt;b&gt;Design/methodology/approach:&lt;/b&gt; In a follow-up to the hard partitioning clustering by Verleysen and Weeren in 2016, we now propose the complementary use of fuzzy cluster analysis, making use of a membership coefficient to study gradual differences between publication styles among authors within a scholarly discipline. The analysis of the probability density function of the membership coefficient allows to assess the distribution of publication styles within and between disciplines.&lt;br&gt;&lt;b&gt;Findings:&lt;/b&gt; As an illustration we analyze 1,828 productive authors affiliated in Flanders, Belgium. Whereas a hard partitioning previously identified two broad publication styles, an international one vs. a domestic one, fuzzy analysis now shows gradual differences among authors. Internal diversity also varies across disciplines and can be explained by researchers&#39; specialization and dissemination strategies.&lt;br&gt;&lt;b&gt;Research limitations:&lt;/b&gt; The dataset used is limited to one country for the years 2000-2011; a cognitive classification of authors may yield a different result from the affiliation-based classification used here.&lt;br&gt;&lt;b&gt;Practical implications:&lt;/b&gt; Our method is applicable to other bibliometric and research evaluation contexts, especially for the social sciences and humanities in non-Anglophone countries.&lt;br&gt;&lt;b&gt;Originality/value:&lt;/b&gt; The method proposed is a novel application of cluster analysis to the field of bibliometrics. Applied to publication patterns at the author level in the social sciences and humanities, for the first time it systematically documents intra-disciplinary diversity.&lt;b&gt;Purpose:&lt;/b&gt; To present a method for systematically mapping diversity of publication patterns at the author level in the social sciences and humanities in terms of publication type, publication language and co-authorship.&lt;br&gt;&lt;b&gt;Design/methodology/approach:&lt;/b&gt; In a follow-up to the hard partitioning clustering by Verleysen and Weeren in 2016, we now propose the complementary use of fuzzy cluster analysis, making use of a membership coefficient to study gradual differences between publication styles among authors within a scholarly discipline. The analysis of the probability density function of the membership coefficient allows to assess the distribution of publication styles within and between disciplines.&lt;br&gt;&lt;b&gt;Findings:&lt;/b&gt; As an illustration we analyze 1,828 productive authors affiliated in Flanders, Belgium. Whereas a hard partitioning previously identified two broad publication styles, an international one vs. a domestic one, fuzzy analysis now shows gradual differences among authors. Internal diversity also varies across disciplines and can be explained by researchers&#39; specialization and dissemination strategies.&lt;br&gt;&lt;b&gt;Research limitations:&lt;/b&gt; The dataset used is limited to one country for the years 2000-2011; a cognitive classification of authors may yield a different result from the affiliation-based classification used here.&lt;br&gt;&lt;b&gt;Practical implications:&lt;/b&gt; Our method is applicable to other bibliometric and research evaluation contexts, especially for the social sciences and humanities in non-Anglophone countries.&lt;br&gt;&lt;b&gt;Originality/value:&lt;/b&gt; The method proposed is a novel application of cluster analysis to the field of bibliometrics. Applied to publication patterns at the author level in the social sciences and humanities, for the first time it systematically documents intra-disciplinary diversity.</span

XMM-Newton observations of the merging galaxy cluster CIZA J2242.8+5301

We studied the intracluster medium of the galaxy cluster CIZA J2242.8+5301 using deep XMM-Newton observations. The cluster hosts a remarkable 2-Mpc long, ~50-kpc wide radio relic that has been nicknamed the "Sausage". A smaller, more irregular counter-relic is also present, along with a faint giant radio halo. We analysed the distribution of the ICM physical properties, and searched for shocks by trying to identify density and temperature discontinuities. East of the southern relic, we find evidence of shock compression corresponding to a Mach number of 1.3, and speculate that the shock extends beyond the length of the radio structure. The ICM temperature increases at the northern relic. More puzzling, we find a "wall" of hot gas east of the cluster centre. A partial elliptical ring of hot plasma appears to be present around the merger. While radio observations and numerical simulations predict a simple merger geometry, the X-ray results point towards a more complex merger scenario.Comment: Extensively revised and expanded, with 18 pages and 17 figure