Reliability assessment of microgrid with renewable generation and prioritized loads

With the increase in awareness about the climate change, there has been a tremendous shift towards utilizing renewable energy sources (RES). In this regard, smart grid technologies have been presented to facilitate higher penetration of RES. Microgrids are the key components of the smart grids. Microgrids allow integration of various distributed energy resources (DER) such as the distributed generation (DGs) and energy storage systems (ESSs) into the distribution system and hence remove or delay the need for distribution expansion. One of the crucial requirements for utilities is to ensure that the system reliability is maintained with the inclusion of microgrid topology. Therefore, this paper evaluates the reliability of a microgrid containing prioritized loads and distributed RES through a hybrid analytical-simulation method. The stochasticity of RES introduces complexity to the reliability evaluation. The method takes into account the variability of RES through Monte- Carlo state sampling simulation. The results indicate the reliability enhancement of the overall system in the presence of the microgrid topology. In particular, the highest priority load has the largest improvement in the reliability indices. Furthermore, sensitivity analysis is performed to understand the effects of the failure of microgrid islanding in the case of a fault in the upstream network

Excited ionic and neutral fragments produced by dissociation of the N2(+)* H band

N I and N II fluorescent radiation was observed when N2 was irradiated by undispersed synchrotron radiation with an upper energy limit of approximately 200 eV. The excited fragments originate from dissociation of a band of excited ionic states of N2 lying between 34.7 and 44 eV

Investigating the effect of textual enhancement in post-reading tasks on grammatical development by child language learners

This study examined the extent to which textual enhancement incorporated into the post-task stage of task-based reading lessons can promote development in second language (L2) grammatical knowledge. The participants were 49 child language learners who participated in task-based reading lessons in their own classroom contexts. They were randomly assigned to two groups, one being exposed to textual enhancement and the other not. The experiment adopted a multiple-exposure design involving six treatment sessions over three weeks. The target construction was the third person singular -s morpheme. Pretest-posttest development was assessed with a grammaticality judgement test. The results revealed a small but positive effect for textual enhancement. We attributed the relative success of textual enhancement to a combination of factors: use of a multiple-exposure design, the incorporation of textual enhancement into the post-task rather than the during-task stage, age of participants, and prior knowledge

Peeling from a patterned thin elastic film

Inspired by the observation that many naturally occurring adhesives arise as textured thin films, we consider the displacement controlled peeling of a flexible plate from an incision-patterned thin adhesive elastic layer. We find that crack initiation from an incision on the film occurs at a load much higher than that required to propagate it on a smooth adhesive surface; multiple incisions thus cause the crack to propagate intermittently. Microscopically, this mode of crack initiation and propagation in geometrically confined thin adhesive films is related to the nucleation of cavitation bubbles behind the incision which must grow and coalesce before a viable crack propagates. Our theoretical analysis allows us to rationalize these experimental observations qualitatively and quantitatively and suggests a simple design criterion for increasing the interfacial fracture toughness of adhesive films.Comment: 8 pages, To appear in Proceedings of Royal Society London, Ser.

Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control

No abstract available

Quasirandom permutations are characterized by 4-point densities

For permutations π and τ of lengths |π|≤|τ| , let t(π,τ) be the probability that the restriction of τ to a random |π| -point set is (order) isomorphic to π . We show that every sequence {τj} of permutations such that |τj|→∞ and t(π,τj)→1/4! for every 4-point permutation π is quasirandom (that is, t(π,τj)→1/|π|! for every π ). This answers a question posed by Graham

Dynamics of composite Haldane spin chains in IPA-CuCl3

Magnetic excitations in the quasi-one-dimensional antiferromagnet IPA-CuCl3 are studied by cold neutron inelastic scattering. Strongly dispersive gap excitations are observed. Contrary to previously proposed models, the system is best described as an asymmetric quantum spin ladder. The observed spectrum is interpreted in terms of ``composite'' Haldane spin chains. The key difference from actual S=1 chains is a sharp cutoff of the single-magnon spectrum at a certain critical wave vector.Comment: 4 pages 4 figure

Carrier-mediated antiferromagnetic interlayer exchange coupling in diluted magnetic semiconductor multilayers Ga1−x_{1-x}Mnx_xAs/GaAs:Be

We use neutron reflectometry to investigate the interlayer exchange coupling between Ga$_{0.97}$Mn$_{0.03}$As ferromagnetic semiconductor layers separated by non-magnetic Be-doped GaAs spacers. Polarized neutron reflectivity measured below the Curie temperature of Ga$_{0.97}$Mn$_{0.03}$As reveals a characteristic splitting at the wave vector corresponding to twice the multilayer period, indicating that the coupling between the ferromagnetic layers are antiferromagnetic (AFM). When the applied field is increased to above the saturation field, this AFM coupling is suppressed. This behavior is not observed when the spacers are undoped, suggesting that the observed AFM coupling is mediated by charge carriers introduced via Be doping. The behavior of magnetization of the multilayers measured by DC magnetometry is consistent with the neutron reflectometry results.Comment: 4 pages, 4 figure

Higher-order corrections to the short-pulse equation

Using renormalization group techniques, we derive an extended short- pulse equation as approximation to a nonlinear wave equation. We investigate the new equation numerically and show that the new equation captures efficiently higher- order effects on pulse propagation in cubic nonlinear media. We illustrate our findings using one- and two-soliton solutions of the first-order short-pulse equation as initial conditions in the nonlinear wave equation

The Hierarchy Problem and the Top Yukawa: An Alternative to Top Partner Solutions

We discuss the role of the top-quark Yukawa coupling $y_t$ concerning thehierarchy problem and construct an alternative scheme to the conventionalsolutions with top partners. In traditional models, like SUSY or compositeHiggs, top partners cancel the top loop contribution to the Higgs quadraticterm. The lack of evidence for such colored partners however drives thesemodels into more and more fine-tuned regions. Here, an alternative means tomitigate the top loop, allowing for natural electroweak symmetry breaking, ispresented. Emphasizing that we have not measured the top-Higgs interactions athigh scales yet, we envisage scenarios where this interaction is onlyapproaching its sizable strength in the infra-red, but gets strongly suppressedat high scales. We first discuss possible effects via a modification of therunning of the top Yukawa coupling. Then, we turn to models where the topYukawa is generated at one-loop level. Originated from a dimension-sixoperator, it drops when crossing the mass threshold of new degrees of freedom.In either case, the top partners are replaced by some new top-philic particleswith strong interaction. Thus, a very different phenomenology, such as largetop mass running and signals in four top final states, is introduced, whichwill be discussed in detail. With the assistance of this mechanism, thesolution to the hierarchy problem can be pushed to a (well-defined) higherscale, and a final test of naturalness might be deferred to a 100 TeV Collider,like the FCC.<br