305,432 research outputs found
Couplings of self-dual tensor multiplet in six dimensions
No full textThe (1, 0) supersymmetry in six dimensions admits a tensor multiplet which contains a second-rank antisymmetric tensor field with a self-dual field strength and a dilaton. We describe the fully supersymmetric coupling of this multiplet to a Yang–Mills multiplet, in the absence of supergravity. The self-duality equation for the tensor field involves a Chern–Simons modified field strength, the gauge fermions and an arbitrary dimensionful parameter.
Massive IIA supergravity from the topologically massive D-2-brane
No full textThe superfield equations of massive IIA supergravity, in the form of constraints on the superspace geometry, are shown to be implied by κ-symmetry of the topologically massive D-2-brane.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Super D-branes
No full textWe present a manifestly Lorentz invariant, space-time supersymmetric, and 'κ-invariant' world-volume action for all type II Dirichlet p-branes, p ≤ 9, in a general type II supergravity background, including massive backgrounds in the IIA case. The p = 0, 2 cases are rederived from D = 11. The p = 9 case provides a supersymmetrization of the D = 10 Born-Infeld action.
Type II duality symmetries in six dimensions
No full textWe discuss the different discrete duality symmetries in six dimensions that act within and between (i) the 10-dimensional heterotic string compactified on T^4, (ii) the 10-dimensional type IIA string compactified on K3 and (iii) the 10-dimensional type IIB string compactified on K3. In particular we show that the underlying group-theoretical structure of these discrete duality symmetries is determined by the proper cubic group C/Z2. Our group theoretical interpretation leads to simple rules for constructing the explicit form of the different discrete type II duality symmetries in an arbitrary background. The explicit duality rules we obtain are applied to construct dual versions of the 6-dimensional chiral null model.
Analysis of Different Energy Management Strategies for Complex Hybrid Electric Vehicles
No full textThe performance of Hybrid Electric Vehicles (HEVs) is strongly affected by their powertrain control strategies, in particular when complex architectures are concerned. Therefore the purpose of this paper is to analyze, through numerical simulation, different methodologies to develop an energy management strategy aiming to minimize the overall CO2 emissions of the vehicle. In order to perform a comprehensive comparison, different optimization algorithms were selected among the available solutions in the control theory. Foremost a global optimization strategy, the Dynamic Programming (DP), was used to benchmark the performance of the energy management systems. Then a local optimization strategy, the Equivalent Consumption Minimization Strategy (ECMS), was evaluated, to prove its suboptimal performance and to evaluate the possibility to be implemented on a real Engine Control Unit (ECU). Finally, the potential of heuristic control techniques was evaluated due to their low computational requirements and since they represent the most common solution in real applications.
The analysis focused on the case study architecture of the Chevrolet Volt, for which a Simulink model was built and tested on both regulatory driving cycles and real world driving conditions, emphasizing pro and cons of each method
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Gauged supergravity from dimensional reduction
No full textWe perform a generalised Scherk-Schwarz reduction of the effective action of the heterotic string on T6 to obtain a massive N = 4 supergravity theory in four dimensions. The local symmetry-group of the resulting d = 4 theory includes a Heisenberg group, which is a subgroup of the global 0(6,6 + n) obtained in the standard reduction. We show explicitly that the same theory can be obtained by gauging this Heisenberg group in d = 4, N = 4 supergravity.
Heterotic-Type II duality and wrapping rules
No full textWe show how the brane wrapping rules, recently discovered in closed oriented string theories compactified on tori, are extended to the case of the Type IIA string compactified on K3. To this aim, a crucial role is played by the duality between this theory and the Heterotic string compactified on a four-dimensional torus T4. We first show how the wrapping rules are applied to the T4/ZN orbifold limits of K3 by relating the D0 branes, obtained as D2 branes wrapping two-cycles, to the perturbative BPS states of the Heterotic theory on T4. The wrapping rules are then extended to the solitonic branes of the Type IIA string, finding agreement with the analogous Heterotic states. Finally, the geometric Type IIA orbifolds are mapped, via T-duality, to non-geometric Type IIB orbifolds, where the wrapping rules are also at work and consistent with string dualities.
kappa$ Symmetry, Supersymmetry and Intersecting Branes
No full textPublished in: Nucl. Phys. B 502 (1997) 149
citations recorded in [Science Citation Index]
Abstract: We present a new form of kappa-symmetry transformations for D-branes in which the dependence on the Born-Infeld field strength is expressed as a relative rotation on the left- and right-moving fields with opposite parameters. Then, we apply this result to investigate the supersymmetry preserved by certain intersecting brane configurations at arbitrary angles and with non-vanishing constant Born-Infeld fields. We also comment on the covariant quantization of the D-brane actions.
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