Fixed gain and adaptive techniques for rotorcraft vibration control

The results of an analysis effort performed to demonstrate the feasibility of employing approximate dynamical models and frequency shaped cost functional control law desgin techniques for helicopter vibration suppression are presented. Both fixed gain and adaptive control designs based on linear second order dynamical models were implemented in a detailed Rotor Systems Research Aircraft (RSRA) simulation to validate these active vibration suppression control laws. Approximate models of fuselage flexibility were included in the RSRA simulation in order to more accurately characterize the structural dynamics. The results for both the fixed gain and adaptive approaches are promising and provide a foundation for pursuing further validation in more extensive simulation studies and in wind tunnel and/or flight tests

Nutrient concentration of forage sorghum (Sorghum bicolor L) varieties under influenced of salinity and irrigation frequency.

The responses of forage sorghum [Sorghum bicolor (L.)Moench] varieties to salinity and irrigation frequency were studied from December 2008 to December 2009 at Universiti Putra Malaysia. Two salt tolerant varieties of forage sorghum, namely Speedfeed and KFS4, were grown under salinity levels of 0, 5, 10, 15 dS m-1 and irrigated when the leaf water potential reached -1(control),-1.5 and -2 MPa. Salinity and irrigation frequency significantly (P≤0.01) affected nutrient concentration of forage sorghum varieties tested. The factorial treatment combinations were arranged in a randomized complete block design with three replications.Sodium content decreased 7 and 17% among the irrigation frequency treatments of -1.5 and -2 MPa, respectively. Abrupt increases in Na contents were noticed at 5 and 10 dS m-1 salinity when Na accumulation increased 4 to 9 fold. Potassium diminished 29, 38 and 54% under 5, 10 and 15 dS m-1 salinity treatment respectively, and decreased 4 and 10% with increase in water stress to -1.5 and -2 MPa respectively. Accumulation of K+, Ca2+ and Mg+ in the shoots was strongly inhibited by salinity.Salinity substantially reduced plant growth as reflected by a decrease in the dry forage yields, and percent of mortality at high salinity levels. The maximum dry forage yields were 45.1, 38.9, and 38.5 g plant–1 for frequent, intermediate, and infrequent irrigation regimes, respectively. Based on salinity, the forage dry weight in control plants had the highest yield (44.09 g plant–1), while plants under the high salinity treatment gave the lowest yield (32.76 g plant–1)

Growth analysis of forage sorghum (Sorghum bicolor L) varieties under varying salinity and irrigation frequency.

Growth of forage sorghum [Sorghum bicolor (L.) Moench] varieties was assessed under saline conditions (EC 0, 5, 10, 15 dS m-1) and irrigated when the leaf water potential reached -1(control),-1.5 and -2 MPa. The forage sorghum varieties namely Speedfeed and KFS4 were differed significantly for emergence, leaf area index, relative growth rate and net assimilation rate. Plants grown under water stress and saline conditions resulted in decreased leaf area which subsequently led to reduced plant growth. Infrequently watered sorghum plants had reduced dry mater, LAI, NAR and eventually dry matter yield. These reductions were higher when lower irrigation frequency was coupled with salinity. The highly significant declined was mostly at -2 MPa irrigation frequency. This indicates that irrigation at 2 weeks interval or till leaf water potential reaches to -1.5 MPa, is possible for forage sorghum

Nilpotence varieties

We consider algebraic varieties canonically associated with any Lie superalgebra, and study them in detail for super-Poincaré algebras of physical interest. They are the locus of nilpotent elements in (the projectivized parity reversal of) the odd part of the algebra. Most of these varieties have appeared in various guises in previous literature, but we study them systematically here, from a new perspective: As the natural moduli spaces parameterizing twists of a super-Poincaré-invariant physical theory. We obtain a classification of all possible twists, as well as a systematic analysis of unbroken symmetry in twisted theories. The natural stratification of the varieties, the identification of strata with twists, and the action of Lorentz and R-symmetry are emphasized. We also include a short and unconventional exposition of the pure spinor superfield formalism, from the perspective of twisting, and demonstrate that it can be applied to construct familiar multiplets in four-dimensional minimally supersymmetric theories. In all dimensions and with any amount of supersymmetry, this technique produces BRST or BV complexes of supersymmetric theories from the Koszul complex of the maximal ideal over the coordinate ring of the nilpotence variety, possibly tensored with any equivariant module over that coordinate ring. In addition, we remark on a natural connection to the Chevalley–Eilenberg complex of the supertranslation algebra, and give two applications related to these ideas: a calculation of Chevalley–Eilenberg cohomology for the (2, 0) algebra in six dimensions, and a degenerate BV complex encoding the type IIB supergravity multiplet

Twisted eleven-dimensional supergravity

We construct a fully interacting holomorphic/topological theory in eleven dimensions that is defined on products of Calabi-Yau fivefolds with real one-manifolds. The theory describes a particular deformation of the cotangent bundle to the moduli space of Calabi-Yau structures on the fivefold. Its field content matches the holomorphic (or minimal) twist of the eleven-dimensional supergravity multiplet recently computed by the second two authors, and we offer numerous consistency checks showing that the interactions correctly describe interacting twisted eleven-dimensional supergravity at the perturbative level. We prove that the global symmetry algebra of our model on flat space is an $L_\infty$ central extension of the infinite-dimensional simple exceptional super Lie algebra $E(5,10)$, following a recent suggestion of Cederwall in the context of the relevant pure spinor model. Twists of superconformal algebras map to the fields of our model on the complement of a stack of M2 or M5 branes, laying the groundwork for a fully holomorphic version of twisted holography in this context.Comment: 58 pages. Comments welcome