123,038 research outputs found
Monitoring wood decay in poles by the vibroacoustic method
No full textDespite recent advances in the development of new materials, wood continues to be used globally for the support of overhead cable networks used by telecommunications and electrical utility companies. As a natural material, wood is subject to decay and will eventually fail, causing disruption to services and danger to public and company personnel. The traditional method of testing poles for decay involves hitting them with a hammer and listening to the sound that results. However, evidence suggests that a large number of poles are replaced unnecessarily and a significant number of poles continue to fail unexpectedly in service. Therefore, a more accurate method for assessing the structural integrity of wooden poles is required. The underlying physical principles behind the 'pole tester's approach' have been identified and used in the development of a decay meter to enable objective monitoring of decay in wooden poles
Weil's converse theorem with poles
No full textWe prove a generalization of the classical converse theorem of Weil, allowing the twists by non-trivial Dirichlet characters to have arbitrary poles.We prove a generalization of the classical converse theorem of Weil, allowing the twists by non-trivial Dirichlet characters to have arbitrary poles
THE GROWTH POLES STRATEGY IN REGIONAL PLANNING: THE RECENT EXPERIENCE OF GREECE
No full textIn recent years, there has been an attempt to stimulate the developmental role of urban centres in Greece in the context of regional and spatial planning. In essence, through the recent basic programming texts for the periods 2000-2006 and 2007-2013, the growth poles strategy has once again been exploited in the development programming. This paper attempts initially to describe the new growth poles strategy through the aforementioned programming texts, and then to present the ensuing problems, as well as to outline the emerging capabilities of planning regarding growth poles in Greece. The main conclusions of the research refer to the lack of a fixed typology, which is based on a specific methodology that could form a hierarchical categorization of urban concentrations through clear, long-term criteria. They also refer to a relative weakness in the planning and implementation of urban development policy, as part of regional programming. The absence of a systematic investigation of the role of particular concentrations in the growth process at regional, national and broader level is also a key-conclusion. The formulation of necessary supplementary policies, as well as the administrative organisation issues of the country’s large cities, are of main importance too.Urban Development, Growth Poles and Axes, Regional and Spatial Planning, Greece.
Poles of L-Functions on Quaternion Groups
No full textThe author shows that the (partial) standard Langlands L-functions on quarternion groups have at most simple poles at certain positive integers
Positive decomposition of transfer functions with multiple poles
No full textWe present new results on decomposing the transfer function t(z) of a linear, asymptotically stable, discrete-time SISO system as a difference t(z) = t(1)(z) - t(2)(z) of two positive linear systems. We extend the results of [4] to a class of transfer functions t(z) with multiple poles. One of the appearing positive systems is always 1-dimensional, while the other has dimension corresponding to the location and order of the poles of t(z). Recently, in [11], a universal approach was found, providing a decomposition for any asymptotically stable t(z). Our approach here gives lower dimensions than [11] in certain cases but, unfortunately, at present it can only be applied to a relatively small class of transfer functions, and it does not yield a general algorithm
Minimal positive realizations of transfer functions with nonnegative multiple poles
No full textThis note concerns a particular case of the minimality problem in positive system theory. A standard result in linear system theory states that any nth-order rational transfer function of a discrete time-invariant linear single-input-single-output (SISO) system admits a realization of order n. In some applications, however, one is restricted to realizations with nonnegative entries (i.e., a positive system), and it is known that this restriction may force the order N of realizations to be strictly larger than n. A general solution to the minimality problem (i.e., determining the smallest possible value of N) is not known. In this note, we consider the case of transfer functions with nonnegative multiple poles, and give sufficient conditions for the existence of positive realizations of order N = n. With the help of our results we also give an improvement of an existing result in positive system theory
Relationship between the system poles, β, and L0 / L.
No full textRelationship between the system poles, β, and L0 / L.</p
Apparatus for Controlling Trolley Poles
No full textPatent for an apparatus for controlling trolley poles. "This invention relates to an apparatus for controlling trolley poles employed for effecting electrical connection between a trolley wire and a motor on a car, and has for its object to provide improved means for automatically throwing the trolley into position to be placed in engagement with the trolley wire" (line 9-15). Illustrations included
Preprint: Ratios of Artin L-functions
No full textWe show that certain quotients of Artin L-functions have infinitely many poles. Our result follows from a converse theorem for Maass forms of Laplace eigenvalue 1/4 in which the twisted L-functions are not assumed to be entire. We do not require the conjectural automorphy of Artin L-functions, only their established meromorphic continuation and functional equation
Computation of transfer function matrices of periodic systems
No full textWe present a numerical approach to evaluate the transfer function matrices of a periodic system corresponding to lifted state-space representations as constant systems. The proposed pole-zero method determines each entry of the transfer function matrix in a minimal zeros-poles- gain representation. A basic computational ingredient for this method is the extended periodic real Schur form of a periodic matrix, which underlies the computation of minimal realizations and system poles. To compute zeros and gains, fast algorithms are proposed, which are specially tailored to particular single-input single-output periodic systems. The new method relies exclusively on reliable numerical computations and is well suited for robust software implementations
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