Optimal design of pipes in series: An explicit approximation

This paper introduces a new methodology for the optimum design of pipes in series, named Optimum Hydraulic Grade Line (OHGL). This methodology is explicit and is based on the knowledge of the series topology and the geometrical distribution of water demands on nodes, i.e. the way in which the pipe in series delivers water mass as function of the distance from the entrance. OHGL consists in the pre-determination of that hydraulic grade line which gives the minimum construction cost, in an explicit way. Once this line has been established, calculation of the pipe’s continuous diameters is direct; after a round up to commercial diameters is developed. To validate the proposed methodology, several pipes in series were designed both using GA and OHGL. Four hundred series were used in total, each with different topological characteristics and demands. Keywords: Pipe in series, optimum design, genetic algorithms, optimum hydraulic grade line

Efficient Cluster Algorithm for Spin Glasses in Any Space Dimension

Spin systems with frustration and disorder are notoriously difficult to study both analytically and numerically. While the simulation of ferromagnetic statistical mechanical models benefits greatly from cluster algorithms, these accelerated dynamics methods remain elusive for generic spin-glass-like systems. Here we present a cluster algorithm for Ising spin glasses that works in any space dimension and speeds up thermalization by at least one order of magnitude at temperatures where thermalization is typically difficult. Our isoenergetic cluster moves are based on the Houdayer cluster algorithm for two-dimensional spin glasses and lead to a speedup over conventional state-of-the-art methods that increases with the system size. We illustrate the benefits of the isoenergetic cluster moves in two and three space dimensions, as well as the nonplanar chimera topology found in the D-Wave Inc.~quantum annealing machine.Comment: 5 pages, 4 figure

Rhodium and copper 6-methylpicolinate complexes. Structural diversity and supramolecular interaction study

Seven new coordination compounds with 6-methylpicolinic acid (6-HMepic) and rhodium(III) or copper(II) of formula [Rh(6-Mepic)3] (1), [Rh(6-Mepic)2(H2O)Cl] (2), [Rh(6-HMepic)(6-Mepic)Cl2]·3.5(H2O) (3), [Cu(6-Mepic)2(H2O)]·H2O (4), [Cu(6-Mepic)2]n, (5), [Cu(6-Mepic)(6-HMepic)I] (6) and [Cu(6-Mepic)(6-HMepic)Cl] (7) have been obtained. Their syntheses have been rationalized, and their structural and supramolecular characteristics have been studied and compared with other similar rhodium and copper picolinate complexes previously reported, in order to stablish structural correlations and analogies. The electrical properties of coordination polymer [Cu(6-Mepic)2]n (5) have been also analyzed and it has been found that it shows a moderated electrical transport along the chain.We thank the financial support from the Spanish Ministerio de Economía y Competitividad (MAT2013-46502-C2-2P and MAT2013-46753-C2-1P). Also the scientific computing center (CCC) of the Autonoma University of Madrid for their tim

Family Dependence in SU(3)_C X SU(3)_L X U(1)_X models

Using experimental results at the Z-pole and atomic parity violation, we perform a chi-squared fit at 95% CL to obtain family-dependent bounds to Z_2 mass and Z-Z' mixing angle in the framework of SU(3)_C X SU(3)_L X U(1)_X models. The allowed regions depend on the assignment of the quark families in mass eigenstates into the three different families in weak eigenstates that cancel anomaliesComment: 14 pages, 2 figures, LaTeX2e; added references, added equations with electroweak corrections for section 4. Version to appear in Phys. Rev.

Best-case performance of quantum annealers on native spin-glass benchmarks: How chaos can affect success probabilities

Recent tests performed on the D-Wave Two quantum annealer have revealed no clear evidence of speedup over conventional silicon-based technologies. Here, we present results from classical parallel-tempering Monte Carlo simulations combined with isoenergetic cluster moves of the archetypal benchmark problem-an Ising spin glass-on the native chip topology. Using realistic uncorrelated noise models for the D-Wave Two quantum annealer, we study the best-case resilience, i.e., the probability that the ground-state configuration is not affected by random fields and random-bond fluctuations found on the chip. We thus compute classical upper-bound success probabilities for different types of disorder used in the benchmarks and predict that an increase in the number of qubits will require either error correction schemes or a drastic reduction of the intrinsic noise found in these devices. We outline strategies to develop robust, as well as hard benchmarks for quantum annealing devices, as well as any other computing paradigm affected by noise.Comment: 8 pages, 5 figure