Derivation of near-optimal pump schedules for water distribution by simulated annealing

The scheduling of pumps for clean water distribution is a partially discrete non-linear problem with many variables. The scheduling method described in this paper typically produces costs within 1% of a linear program-based solution, and can incorporate realistic non-linear costs that may be hard to incorporate in linear programming formulations. These costs include pump switching and maximum demand charges. A simplified model is derived from a standard hydraulic simulator. An initial schedule is produced by a descent method. Two-stage simulated annealing then produces solutions in a few minutes. Iterative recalibration ensures that the solution agrees closely with the results from a full hydraulic simulation

Comment on: Diffusion through a slab

Mahan [J. Math. Phys. 36, 6758 (1995)] has calculated the transmission coefficient and angular distribution of particles which enter a thick slab at normal incidence and which diffuse in the slab with linear anisotropic, non-absorbing, scattering. Using orthogonality relations derived by McCormick & Kuscer [J. Math. Phys. 6, 1939 (1965); 7, 2036 (1966)] for the eigenfunctions of the problem, this calculation is generalised to a boundary condition with particle input at arbitrary angles. It is also shown how to use the orthogonality relations to relax in a simple way the restriction to a thick slab.Comment: 3 pages, LaTeX, uses RevTe

Alien Registration- Mccormick, William G. (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/21366/thumbnail.jp

Empirically Testing the Principles of Crime Prevention Through Environmental Design (CPTED) Theory: An Exploratory Investigation of Perceived Safety in Virtual Parks and Green Spaces

Jeffery\u27s Crime Prevention Through Environmental Design has become one of the leading crime prevention strategies used in many countries world wide including the United States. However, to date Jeffery\u27s complete CPTED model has not been subjected to empirical testing (Paulsen & Robinson, 2005). The focus of this research is to empirically test people\u27s perception of Crime Prevention Through Environmental Design (CPTED) principles. This research will record the subject\u27s perception of safety of virtual environments using three levels of CPTED design. A virtual landscape will be utilized because it allows for manipulation of the independent variable while holding the other variables constant and past research suggest that people respond similarly to virtual environments as they do to the real environment (Kaplin and Kaplin, 1989). A convenience sample consisted of one hundred forty three undergraduate students (39 men, and 104 women) at a university in the Mid-Atlantic United States. The stimuli consisted of 33 color slides of computer generated slides of natural and urban landscapes. None of the environments contained people. All slides maintained the exact same sun placement, clouds, weather conditions, time of day and month of the year. Participants in each session rated each of the environments on only one variable, their perception of safety in the photo. A 5-point scale ranged from I (very safe) to 5 (very unsafe). Safety was operationally defined as If all alone in this environment, how safe would you feel? Each environment was presented in three slides, representing three levels of CPTED. The lowest level had no CPTED strategies incorporated into the design of the environment nor does this slide contain any vegetation. The second level incorporated the trees and vegetation, however, there are no CPTED principles applied to the landscape. The last level incorporated at least one or more of the four major components of CPTED (access control, natural observation, territoriality , and maintenance). The data from the results suggests that CPTED does make a difference in the perception of safety. 88 percent of the environments using CPTED principles were viewed as the safest or second safest environments. Only 12 percent or two of the environments using CPTED principles were considered the least safe. Gender differences were tested using the Nonparametric (Mann-Whitney) statistical test. A statistically significance difference existed between gender and perception of fear in the environment at the (P \u3c .001) level. Implications to academic and policy applications are discussed. Future research is recommended

SAGE measurements of the stratospheric aerosol dispersion and loading from the Soufriere Volcano

Explosions of the Soufriere volcano on the Caribbean Island of St. Vincent reduced two major stratospheric plumes which the stratospheric aerosol and gas experiment (SAGE) satellite tracked to West Africa and the North Atlantic Ocean. The total mass of the stratospheric ejecta measured is less than 0.5% of the global stratospheric aerosol burden. No significant temperature or climate perturbation is expected. It is found that the movement and dispersion of the plumes agree with those deduced from high altitude meteorological data and dispersion theory. The stratospheric aerosol dispersion and loading from the Soufrier volcano was measured

Alien Registration- Mccormick, William G. (Portland, Cumberland County)

https://digitalmaine.com/alien_docs/21366/thumbnail.jp

Simulating Drug-Eluting Stents: Progress Made and the Way Forward

Drug-eluting stents have significantly improved the treatment of coronary artery disease. Compared with their bare metal predecessors, they offer reduced rates of restenosis and thus represent the current gold standard in percutaneous coronary interventions. Drug-eluting stents have been around for over a decade, and while progress is continually being made, they are not suitable in all patients and lesion types. Furthermore there are still real concerns over incomplete healing and late stent thrombosis. In this paper, some modelling approaches are reviewed and the future of modelling and simulation in this field is discussed

Fluctuations and Pinch-Offs Observed in Viscous Fingering

Our experiments on viscous (Saffman-Taylor) fingering in Hele-Shaw channels reveal several phenomena that were not observed in previous experiments. At low flow rates, growing fingers undergo width fluctuations that intermittently narrow the finger as they evolve. The magnitude of these fluctuations is proportional to Ca^{-0.64}, where Ca is the capillary number, which is proportional to the finger velocity. This relation holds for all aspect ratios studied up to the onset of tip instabilities. At higher flow rates, finger pinch-off and reconnection events are observed. These events appear to be caused by an interaction between the actively growing finger and suppressed fingers at the back of the channel. Both the fluctuation and pinch-off phenomena are robust but not explained by current theory.Comment: 6 pages, 3 figures; to appear in Proceedings of the Seventh Experimental Chaos Conferenc