The location of protection devices on electrical tree networks: a heuristic approach

The problem of determining the number of protection devices and their locations on an electrical tree network with subtrees dependency is investigated. The aim is to reduce the amount of inconvenience caused to customers that are affected by any given fault on the network. A constructive heuristic and an appropriate implementation of tabu search are proposed and compared against a method currently used by the electrical supply companies. Computational tests are performed on randomly generated electrical tree networks varying in size and branch complexity. Both the proposed methods outperformed the one used in practice. In particular our tabu search implementation was found to produce the best results without taking an excessive amount of computational time.     

An analysis of the destabilizing curvature effects on the turbulent flow over a rotating cylinder

An analysis based on the available experimental data and second-order closures is made for a turbulent shear flow over a rotating cylinder in a quiescent fluid. The near-wall behaviour of the non-linear model for the pressure-strain correlation proposed by Speziale, Sarkar and Gatski [J. Fluid Mech. 245, 227 (1991)] is enlarged; and the methodology proposed by Lai and So [J. Fluid Mech. 221, 641 (1990)] is adopted to take into account the wall-effects. The radial profile of the curvature parameter, R_s, is examined in connection with the logarithmic law. It is shown that the log-layer is associated to the region where the mean velocity profile, V, is related to the power of the radial distance as Computations reveal that this region corresponds to the state with the most destabilizing curvature effects; which can be chararacterized by the minimum value of the parameter B _c =2R _s (1+2R _s ), and not that one of the parameter B=2R _s (1+2R _s )/(1+R _s )² firstly introduced by Bradshaw [J. Fluid Mech. 36, 171 (1969)] and extensively used to characterize the turbulence structure in curved flows. Received 9 December 1997     

Investigating Route to Chaos in Nonlinear Plasmonic Dimer

The route to chaos of a plasmonic dimer formed of two identical nanoparticles with Kerr-type nonlinear response and illuminated by an external electric field is reported. It is shown that this system has a complex dynamical behavior with chaotic nature. This complexity is analyzed using Lyapunov exponents, the Kaplan–Yorke dimension, and correlation dimensions. The existence of familiar period-doubling sequences route to chaos is pointed out, and domains corresponding to the onset of period doubling and chaos in the plane of parameters are evidenced.     

Preparation and characterization of submicron hybrid magnetic latex particles

Micrometer magnetic hybrid particles are of great interest in biomedical field, and various morphologies have been prepared via encapsulation processes. Regarding submicron, only few processes have been investigated and the most recent one leading to highly magnetic submicron magnetic hybrid particles is based on oil in water magnetic emulsion (MES) transformation. The encapsulation of magnetic iron oxide nanoparticles forming oil in water MES was investigated using different styrene/cross‐linker divinylbenzene volume ratio in the presence of potassium persulfate initiator. The encapsulation performed in this work is basically conducted by using well‐defined oil in water MES as a seed in radical emulsion polymerization. The chemical composition, morphology, iron oxide content, magnetic properties, electrokinetic properties, particle size, and size distribution of the prepared magnetic hybrid particles were examined using various techniques. The desired perfect magnetic core and polymer shell morphology were successfully obtained, and the final magnetic hybrid particles are superparamagnetic in nature and exhibit high iron oxide content (64 wt %). Copyright © 2015 John Wiley & Sons, Ltd.     

New synthesis of two tridentate bipyrazolic compounds and their cytotoxic activity tumor cell lines

Two new tripodal compounds - 4-{bis[(3,5-dimethyl-1H-pyrazole-1-yl)methyl]amino}butane-1-ol (1); ethyl 1-[((2-hydroxyethyl){[3-(ethoxycarbonyl)-5-methyl-1H-pyrazole-1-yl]methyl} amino)methyl]-5-methyl-1H-pyrazole-3-carboxylate (2) were reported. The evaluation of the cytotoxic properties in vitro of these ligands, was examined on two tumor cell lines - P815 (mastocytome murine) and Hep (carcinoma of human larynx). The concentration required to induce 50% of lysis (IC(50)) was more pronounced against P815 cell line (IC(50): 39.42 microg mL(-1) for the compound 1 and 97.74 microg mL(-1) for the compound 2) than the Hep cell line (IC(50): 83.49 microg mL(-1) for compound 1 and 185.30 microg mL(-1) for compound 2). Statistical analysis shows that the compound 1 is two to three folds more cytotoxic than the compound 2 (p < 0.05). Interestingly, the cytotoxic activity depends strongly on both the substituents linked to the aminic nitrogen and pyrazolic rings.     

Phase-locked mutually coupled 1.3 microm quantum-dot lasers

Fabry-Perot InAs quantum-dot lasers grown on GaAs substrates are mutually coupled with a delay of several nanoseconds. Stable phase-locked output with narrow linewidth is obtained when the frequency detuning between the two lasers is less than 4 GHz. This simple locking scheme could find application in a variety of photonics applications.     

Spin polarized 3He: From basic research to medical applications

Polarization of ³He gas by means of optical pumping is well known since the early 1960s with first applications in fundamental physics. Some thirty years later it was discovered, that one can use hyperpolarized ³He as contrast agent for magnetic resonance imaging of the lung. The wide interest in this new method made it necessary to find ways of polarizing ³He in large quantities with high polarization degrees. A high performance polarizing facility has been developed at the University of Mainz, designed for centralized production of hyperpolarized ³He gas. We present the Mainz concept as well as some examples of numerous applications of spin polarized ³He in fundamental research and medical applications.     

An iterative variable-based fixation heuristic for the 0-1 multidimensional knapsack problem

An iterative scheme which is based on a dynamic fixation of the variables is developed to solve the 0-1 multidimensional knapsack problem. Such a scheme has the advantage of generating memory information, which is used on the one hand to choose the variables to fix either permanently or temporarily and on the other hand to construct feasible solutions of the problem. Adaptations of this mechanism are proposed to explore different parts of the search space and to enhance the behaviour of the algorithm. Encouraging results are presented when tested on the correlated instances of the 0-1 multidimensional knapsack problem.     

The multifacility maximin planar location problem with facility interaction

^** Email: s.salhi{at}kent.ac.uk Two branch-and-bound algorithms are proposed to optimally solvethe maximin formulation for locating p facilities in the plane.Tight upper and lower bounds are constructed and suitable methodsof guiding the search developed. To enhance the method, efficientmeasures for identifying specific squares for subdivision aresuggested. The proposed algorithms are evaluated on a set ofrandomly generated problems of up to five facilities and 120nodes.