559 research outputs found
A bifurcated circular waveguide problem
No full textThis is a pre-copy-editing, author-produced PDF of an article accepted for publication in IMA Journal of Applied Mathematics following peer review. The definitive publisher-authenticated version A D Rawlins. A bifurcated circular waveguide problem. J.I.M.A. 54 (1995) 59-81. Oxford University press is available online at: http://imamat.oxfordjournals.org/cgi/reprint/54/1/59.pdfA rigorous and exact solution is obtained for the problem of the radiation of sound from a semi-infinite rigid duct inserted axially into a larger acoustically lined tube of infinite length. The solution to this problem is obtained by the Wiener-Hopf technique. The transmission and reflection coefficients, when the fundamental mode propagates in the semi-infinite tube, are obtained. The present results could be of use for exhaust design, and as a possible instrument for impedance measurement
A note on Wiener-Hopf matrix factorisation
No full textThis is a pre-copy-editing, author-produced PDF of an article accepted for publication in Quarterly Journal of Mechanics and Applied Mathematics following peer review. The definitive publisher-authenticated version Rawlins, A D (1985). A note on Wiener-Hopf matrix factorisation. Quarterly Journal of Mechanics and Applied Mathematics. 38 (3) 433-437 is available online at: http://qjmam.oxfordjournals.org/cgi/reprint/38/3/433.pdfIn this paper the most general class of 2 x 2 matrices is determined which permit a
Wiener-Hopf factorization by the procedure of Rawlins and Williams (1). According
to this procedure, the factorization problem is reduced to a matrix Hilbert problem
on a half-line, where the matrix involved in the Hilbert problem is required to have
zero diagonal elements
The method of finite-product extraction and an application to Wiener-Hopf theory
No full textCopyright @ The Author, 2011. The publisher version of the article can be accessed at the link below.In this work we describe a simple method for finding approximate representations for special functions which are entire transcendental functions that can be represented by infinite products. This method replaces the infinite product by a finite polynomial and Gamma functions. This approximate representation is shown in the case of Bessel functions to be very accurate over a large range of parameter values. These approximate expressions can be useful for finding the roots of a transcendental equation and the Wiener-Hopf factorization of functions involving such Bessel functions.The method is shown to be potentially useful for other transcendental andWiener-Hopf problems, which involve other entire functions that have infinite product representations
Commentary : missing targets on drugs-related deaths, and a Scottish paradox
No full textThe 10-year drug strategy for England and Wales was published in February 2008. It dropped drugs-related deaths (DRDs) as a key performance indicator. Scotland retained a necessary strong focus on DRDs. Scotland's DRDs numbered 1006 in 2000–02 and 1009 in 2003–05. The previous Scottish administration's claim that its number of current injectors had decreased substantially between 2000 and 2003 implied, paradoxically, that their DRD rate would have to have increased. Worse was to come: Scotland's DRDs had increased to 876 in 2006 + 2007. We analyse UK's DRDs by sex and age-group to reveal temporal trends (2000–02 versus 2003–05 versus 2006 + 2007) with different public health and epidemiological implications. We also address the above Scottish paradox and assess, by age-group, how consistent Scotland's 876 DRDs in 2006 + 2007 are with Scottish injectors’ DRD rate in 2003–05 of around 1 per 100 injector-years. Public health success in the UK in reducing DRDs at younger ages should not be overshadowed by the late consequence in terms of older-age DRDs of UK's injector epidemics; in the early 1980s in Scotland, and late 1980s in England and Wales. Targets for reducing DRDs should pay heed to UK's injector epidemics
Ummah Futures Halal Investment Cooperative
No full text"Ummah Futures" is an equity-based community investment cooperative that will collect fixed monthly investments from up to 20 members of the Nur-Ul-Islam Center's Ummah (community), located in Cooper City, Florida, towards the goals of wealth creation, asset accumulation and economic brotherhood by stimulating cooperative business activities and investments according to Islamic economic and social principles. Muslims are forbidden to engage in interest or support investing in haram (Islamically unlawful) business activities (i.e. the sale of alcohol). There will be two levels of monthly investment over a 36-months period, they are: 1) 300 per month. Future funding will be derived from the increase of new memberships and the success (or lack thereof) of equity investments made by the co-op. The co-op's initial 20 members, investing at the higher tier, will invest $216,000 over the 36 months period and the return on the investment that the co-op will target is 5% plus the member's principle investment. Moreover, participants in the plan will be encouraged to reinvest their earnings back into the plan.
The success of the project will be evaluated by determining (a) how many participants complete the investment program; (b) the number of new participants enrolling in the program; (c) the increase in earnings; (d) the number of new employment or contracted opportunities created for members, (e) the number of members trained in cooperative structure and Islamic economic principles, and; (f) the effect of that training in the social and economic relations of the investors. (Author abstract)Rawlins, W. E. (2005). Ummah Futures Halal Investment Cooperative. Retrieved from http://academicarchive.snhu.eduMaster of Science (M.S.)School of Community Economic Developmen
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On the hunt for willing sellers : the U.S. Army's land acquisition process
No full texttextTo maintain high levels of proficiency and readiness the U.S. Army trains its soldiers on military bases across the country. However, the Army currently possesses an insufficient amount of land with which to train on, necessitating an expansion of current bases. This paper explores the Army's land acquisition policies, using as case studies the ongoing expansions at Fort Carson in Colorado and Fort Polk in Louisiana. Fort Carson, which announced expansion plans in 2006, faced strong opposition and the project has ground to a halt. In early 2009 Fort Polk announced a 100,000-acre expansion. They have utilized a broad public outreach program and promised on numerous occasions not to use eminent domain to acquire privately-held land. As a result, the Polk expansion has proceeded much more smoothly. Using lessons learned from the pair of case studies, this paper then presents a list of best practices the Army can use for future land acquisition projects.Community and Regional Plannin
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