Comparison of impedance behavior of UVRT-Container with medium voltage grid simulator in case of unsymmetrical voltage dip

This paper presents the concept of electrical testing, such as under voltage ride through (UVRT) of wind turbines on test bench using Power Electronics Grid Simulator (PEGS). PEGS can emulate an artificial medium voltage grid up to 36kV. One of the PEGS capabilities is to add artificial series impedance to the voltage source in fa-vor of changing the virtual short circuit power at the point of common coupling (PCC). In order to verify the test bench UVRT tests it is essential to show if PEGS is capable to emulate same grid behavior and characteristics as UVRT-Container. Later, a comparison of the simulation results of the developed PEGS test to the UVRT-Container test is presented. In case of a two-phase fault emulated by UVRT-Container, the impedance seen by the faulted and un-faulted phases are changed during the fault due to additional short circuit impedance connected to the grid. The aim of this paper is to show that the PEGS can emulate the impedance for each phase during unsymmetrical faults

Nonlinear Propagation of Spin Waves in Microscopic Magnetic Stripes

Demidov VE, Jersch J, Rott K, Krzysteczko P, Reiss G, Demokritov SO. Nonlinear Propagation of Spin Waves in Microscopic Magnetic Stripes. PHYSICAL REVIEW LETTERS. 2009;102(17): 177207.We have studied experimentally with high spatial and temporal resolution propagation of intense spin waves in microscopic Permalloy stripes. We show that the nonlinearity of the spin system of metallic magnetic films together with microscopic-scale confinement effects lead to an anomalous nonlinear magnetic dynamics, such as a nonlinear spatial self-modulation of spin waves characterized by the repulsive nonlinearity. This phenomenon appears to be densely connected with the nonlinear damping in the system. We find that both of these effects develop synchronously on the nanosecond temporal scale

Mapping of localized spin-wave excitations by near-field Brillouin light scattering

Jersch J, Demidov VE, Fuchs H, et al. Mapping of localized spin-wave excitations by near-field Brillouin light scattering. APPLIED PHYSICS LETTERS. 2010;97(15): 152502.We report on the experimental study of the spatial characteristics of high-frequency spin-wave modes localized at the edges of micrometer-size in-plane magnetized permalloy ellipses. Using a near-field Brillouin light scattering technique, we have mapped the modes with the spatial resolution of few tens of nanometers. We show that the width of the localization area strongly depends on the applied magnetic field and reduces to about 85 nm for high fields. We also demonstrate that the existing theoretical models do not appropriately describe spatial characteristics of the modes. (c) 2010 American Institute of Physics. [doi:10.1063/1.3502599

Grey mould of strawberry, a devastating disease caused by the ubiquitous necrotrophic fungal pathogen Botrytis cinerea

The fungal pathogen Botrytis cinerea causes grey mould, a commercially damaging disease of strawberry. This pathogen affects fruit in the field, storage, transport and market. The presence of grey mould is the most common reason for fruit rejection by growers, shippers and consumers, leading to significant economic losses. Here, we review the biology and epidemiology of the pathogen, mechanisms of infection and the genetics of host plant resistance. The development of grey mould is affected by environmental and genetic factors; however, little is known about how B. cinerea and strawberry interact at the molecular level. Despite intensive efforts, breeding strawberry for resistance to grey mould has not been successful, and the mechanisms underlying tolerance to B. cinerea are poorly understood and under-investigated. Current control strategies against grey mould include pre- and postharvest fungicides, yet they are generally ineffective and expensive. In this review, we examine available research on horticultural management, chemical and biological control of the pathogen in the field and postharvest storage, and discuss their relevance for integrative disease management. Additionally, we identify and propose approaches for increasing resistance to B. cinerea in strawberry by tapping into natural genetic variation and manipulating host factors via genetic engineering and genome editing