Experience on the use of MOSTAB-HFW computer code for horizontal-axis wind turbines

Three topics are covered dealing with the frequencies of a rotating beam, the use of the fundamental mode of a uniform cantilever beam, and the analysis of resonance dwell. Immensely high peak loads were generated by the code for resonance dwell indicating further need for including structural damping and for transient analysis capability. The effect of structural damping, newly incorporated in the code, is described

Dynamic instability of ducts conveying fluid

A finite element analysis was used to study dynamic instability in ducts conveying high speed fluids. Ducts examined include cantilevered curved, flexibly supported, arbitrarily shaped, and composite duct systems. Partial differential equations were used to study the duct systems

Value distribution of the hyperbolic Gauss maps for flat fronts in hyperbolic three-space

We give an effective estimate for the totally ramified value number of the hyperbolic Gauss maps of complete flat fronts in the hyperbolic three-space. As a corollary, we give the upper bound of the number of exceptional values of them for some topological cases. Moreover, we obtain some new examples for this class.Comment: 14 pages, to appear in Houston Journal of Mathematic

Port Decoupling for Small Arrays by Means of an Eigenmode Feed Network

An alternative approach to port decoupling and matching of arrays with tightly coupled elements is proposed. The method is based on the inherent decoupling effect obtained by feeding the orthogonal eigenmodes of the array. For this purpose, a modal feed network is connected to the array. The decoupled external ports of the feed network may then be matched independently by using conventional matching circuits. Such a system may be used in digital beam forming applications with good signal-to-noise performance. The theory is applicable to arrays with an arbitrary number of elements, but implementation is only practical for smaller arrays. The principle is illustrated by means of two examples