Supramolecular networks with 1-substituted benzotriazole ligands and transition metals

1-(2-Pyridyl)benzotriazole (L1) and 1-(4-pyridyl)benzotriazole (L2) with transition metal cations Co(II), Ni(II) and Cu(II) give four coordination complexes, [{Cu(L1)₂(H₂O)₂} · 2NO₃] (1), [{Co(L1)₂(H₂O)₂} · 2NO₃] (2), [Ni(L2)₂(NO₃)₂(H₂O)₂] (3), and [Cu₂(L2)₂(CH₃COO)₄] (4). In 1–4, different supramolecular frameworks are formed through hydrogen bonding and/or π–π interactions.     

Prediction dielectric constant of different ternary liquid mixtures at various temperatures and compositions using artificial neural networks

Artificial neural networks (ANNs) were successfully developed for the modeling and prediction dielectric constant of different ternary liquid mixtures at various temperatures (?10°C?≤?t?≤?80°C) and over the complete composition range (0?≤?x ₁,?x ₂,?x ₃?≤?1). A three-layered feed forward ANN with architecture 7-16-1 was generated using seven parameters as inputs and its output is dielectric constant of media. It was found that properly selected and trained neural network could fairly represent the dependence of dielectric constant of different ternary liquid mixtures on temperature and composition. For the evaluation of the predictive power of the generated ANN, an optimized network was applied for predicting the dielectric constant in the prediction set, which were not used in the modeling procedure. Squared correlation coefficient (R ²) and root mean square error for prediction set are 0.9997 and 0.2060, respectively. The mean percent deviation (MPD) for the property in the prediction set is 0.8892%. The results show nonlinear dependence of dielectric constant of ternary mixed solvent systems on temperature and composition is significant.     

复杂网络病毒传播的局域控制研究

从复杂网络的节点路径长度范围的角度来研究病毒传播的局域控制，分析了在不同拓扑结构的复杂网络中进行局域控制的有效性.研究表明，局域控制对WS小世界网络、BA无标度网络和ER随机网络三类复杂网络均有效，但只有WS小世界网络存在零感染的控制范围最优值d=3；对于长程连边的分布存在距离偏好的Kleinberg小世界网络，随着依赖度的增大，病毒传播率临界值增加，同时局域范围控制的效果得到加强. 关键词： 复杂网络 病毒传播 局域控制 路径长度     

Application of generalized diagonal dominance in wireless sensor network optimization problems

The recent application of the diagonal dominance in the development of the optimization algorithms in the wireless sensor networks design, has been done by Yuan and Yu (2006) [14], extended in Yu et al. (2006) [9], and surveyed in Machado and Tekinay [11]. In this paper, we will use the concept of generalized diagonal dominance, to improve the obtained results regarding the power control game, in three directions. We also discuss the applicability of such improvements.     

Hopfield neural networks in large-scale linear optimization problems

Hopfield neural networks and affine scaling interior point methods are combined in a hybrid approach for solving linear optimization problems. The Hopfield networks perform the early stages of the optimization procedures, providing enhanced feasible starting points for both primal and dual affine scaling interior point methods, thus facilitating the steps towards optimality. The hybrid approach is applied to a set of real world linear programming problems. The results show the potential of the integrated approach, indicating that the combination of neural networks and affine scaling interior point methods can be a good alternative to obtain solutions for large-scale optimization problems.     

Synthesis of novel copper compounds containing isonicotinic acid and/or 2,6-pyridinedicarboxylic acid: third-order nonlinear optical properties

Two novel compounds, [Cu₂(pydc)₂(inta)₂(H₂O)₂]·3H₂O 1 (pydc?=?2,6-pyridinedicarboxylic acid, inta?= isonicotinic acid) and [Cu(pydc)₂][Cu(H₂O)₅]·2H₂O 2, have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses and IR spectra. Compound 1 exhibits reverse saturable absorption and self-defocusing. X-ray structural analysis reveals that Compounds 1 and 2 both possess π–π stacking and hydrogen-bonding interactions forming three-dimensional (3D) networks. Crystal data for 1: a?=?7.2345(14), b?=?12.219(2), c?=?17.069(3)?Å, α?=?90.44(3), β?=?91.82(3), γ?=?93.56(3)°, Z?=?1, R1?=?0.0435, wR2?=?0.1216. Crystal data for 2: a?=?8.3708(17), b?=?27.386(6), c?=?9.6170(19)?Å, α?=?90.00, β?=?98.14(3), γ?=?90.00°, Z?=?3, R1?=?0.0742, wR2?=?0.2160.     

Specific Features of Strain Dependences of Loss Modulus in Highly Stretched Elastomers

The loss modulus E″ in elastomer strips stretched by a factor of λ is studied theoretically. A small oscillating deformation is applied to these strips in the transition frequency zone between the glassy and rubbery states. The range of λ under study ranges up to ultimate extensions close to fracture. A model of E″/λ dependence in the transition frequency zone is suggested that considers the possible distortion in the local chain structure in the ultimate extension range. It is found that E″ in the range of moderate and high λ increases owing to the finite extensibility of the chains. However, upon further extension up to ultimate values, E″ decreases and a maximum appears on the E″/λ curves. These features are also confirmed experimentally.

     

A dynamic system model for solving convex nonlinear optimization problems

This paper proposes a feedback neural network model for solving convex nonlinear programming (CNLP) problems. Under the condition that the objective function is convex and all constraint functions are strictly convex or that the objective function is strictly convex and the constraint function is convex, the proposed neural network is proved to be stable in the sense of Lyapunov and globally convergent to an exact optimal solution of the original problem. The validity and transient behavior of the neural network are demonstrated by using some examples.     

Stochastic exponential synchronization of jumping chaotic neural networks with mixed delays

This paper deals with the exponential synchronization problem for a class of stochastic jumping chaotic neural networks with mixed delays and sector bounded nonlinearities. The mixed time delays under consideration comprise both discrete time-varying delays and distributed time delays. By applying the Finsler’s Lemma and constructing appropriate Lyapunov-Krasovskii functional based on delay partitioning, several improved delay-dependent feedback controllers with sector nonlinearities are developed to achieve the synchronization in mean square in terms of linear matrix inequalities. It is established theoretically that two special cases of the obtained criteria are less conservative than some existing results but including fewer slack variables. As the present conditions involve no free weighting matrices, the computational burden is largely reduced. One numerical example is provided to demonstrate the effectiveness of the theoretical results.