Wide area telecommunication network design: application to the Alberta SuperNet

This article proposes a solution methodology for the design of a wide area telecommunication network. This study is motivated by the Alberta SuperNet project, which provides broadband Internet access to 422 communities across Alberta. There are two components to this problem: the network design itself, consisting of selecting which links will be part of the solution and which nodes should house shelters; and the loading problem which consists of determining which signal transport technology should be installed on the selected edges of the network. Mathematical models are described for these two subproblems. A tabu search algorithm heuristic is developed and tested on randomly generated instances and on Alberta SuperNet data.     

Optical behavior of antibiofouling additives in environment‐friendly coverglass materials for bio‐sensors and solar panels

Solar panels and bio‐optical sensors play a significant and growing role in a number of applications that are of importance to many organizations. Many of these instruments require a high transmission of radiation into the device for it to work properly. A major issue faced is that harsh marine environments often aid in the growth or development of fouling on the coverglass used to protect the instruments. Over a period of time in an ocean environment, some plant or animal may attach itself to the coverglass, ultimately obscuring the glass and rendering the instrument useless. As such, an antifouling mechanism is needed for these instruments that is inexpensive, long‐lasting, and environment friendly. The approach discussed herein involves the use of known antifouling chemicals which have been incorporated into the polymer matrix. Polymethylmethacrylate (PMMA), bisphenol A polycarbonate (Bis A PC), and a co‐polyterephthalate (CPTE) were examined. The plaques are optically transparent and previous work has shown that, for most samples, the materials display a minimal decrease in mechanical behavior upon the addition of the algaecides. This paper will discuss the effects on the materials' optical properties when exposed to both harsh marine conditions as well as high intensity UV light. Specifically, the decrease in transmission of visible light was examined over a 6 month period of time. Copyright © 2008 John Wiley & Sons, Ltd.     

The alkylation of hantzsch 1,4-dihydropyridines

The reaction of carbanions derived from Hantzsch 1,4-dihydropyridines with alkyl halides was studied and methods for mono- and di-alkylation were devised.     

Invariant Core Theorems for Double Sequences

The definition for the convergence of a double sequence was presented by A. Pringsheim [9]. Recently, the definitions of limit inferior, limit superior, and the core of a double sequence are presented. By using these definitions and the notion of regularity for four-dimensional matrices, an invariant core theorem for double sequences is presented.AMS Subject Classification (2000) primary 40B05 secondary 40C05     

Avoided level crossing μSR of organic free radicals

Several aspects of the ALC-μSR technique of muonated organic free radicals in liquids, including the effects of chemical dynamics and T₁-processes are discussed.     

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