A Coordination Polymer of Vaska's Complex as a Heterogeneous Catalyst for the Reductive Formation of Enamines from Amides

Low-valent metal–organic frameworks (LVMOFs) and related materials have gained interest due to their potential applications in heterogeneous catalysis. However, of the few LVMOFs that have been reported, none have shown catalytic activity. Herein, a low-valent metal-organic material constructed from phosphine linkers and Ir^I nodes is reported. This material is effectively a crystalline, insoluble analogue of Vaska's complex. As such, the material reversibly binds O₂ and catalyzes the reductive formation of enamines from amides.     

Numerical approximation of the optimal control of a population dynamics model

In this paper, we present a numerical approach to an inverse problem of a population dynamics model. We propose a numerical approximation of the optimal control for obtaining the desired observation state using the augmented Lagrangian method. Moreover, the existence and uniqueness of the numerical solutions are mathematically investigated in this work. Finally, we present some numerical experiments to illustrate our theoretical results.     

Two-soliton solutions of the complex short pulse equation via Riemann–Hilbert approach

Based on the basic conclusions of the Riemann–Hilbert method for solving the initial value problem of the complex short-pulse equations, the general form of the two-soliton solutions of the complex short pulse equation is given in this paper. Under the two different assumptions of the scattering coefficient, the expression of the two-soliton solutions of the equation is given specifically.     

A co-opetitive framework for the hub location problems in transportation networks

In this paper, we present the first model of co-opetition for a Hub Location Problem between two logistics service provider (LSPs) companies where the mother company is the owner of infrastructure. The LSPs would like to cooperate with each other by establishing joint edges with limited capacities connecting their service networks. Such services are in form of pendulum services (a direct service between two points) between nodes of different networks. Additional market can be generated as a result of joining the two networks. At the same time, a competition is taking place between the two operators to increase their share from the additional market generated. In order to solve this problem, we propose a matheuristic approach combining a local search algorithm and a Lagrangian relaxation-based approach. In our matheuristic algorithm, the neighbourhood solutions are evaluated using a Lagrangian relaxation-based approach. Numerical results of applying the proposed algorithm on a real case study of the problem are presented.     

High-order splitting methods for separable non-autonomous parabolic equations

We consider the numerical integration of non-autonomous separable parabolic equations using high order splitting methods with complex coefficients (methods with real coefficients of order greater than two necessarily have negative coefficients). We propose to consider a class of methods that allows us to evaluate all time-dependent operators at real values of the time, leading to schemes which are stable and simple to implement. If the system can be considered as the perturbation of an exactly solvable problem and the flow of the dominant part is advanced using real coefficients, it is possible to build highly efficient methods for these problems. We show the performance of this class of methods on several numerical examples and present some new improved schemes.     

Solution for Eshelby’s elliptic inclusion with polynomials distribution of the eigenstrains in plane elasticity

This paper provides a closed form solution for the Eshelby’s elliptic inclusion in plane elasticity with the polynomials distribution of the eigenstrains. The complex variable method and the conformal mapping technique are used. The continuity conditions for the traction and displacement along the interface in the physical plane are reduced to a similar condition along the unit circle of the mapping plane. From those continuity conditions, we can obtain two sets of the complex potentials for the region outside of the unit circle and for the ring region, respectively. Further, we can obtain the complex potentials in the physical plane, or z-plane (z = x + iy). The mapping function maps the ring region in the mapping plane into a finite elliptic region with a crack on the real axis in the physical plane. An exact form for the complex potentials defined in the ring region is studied and proposed. In addition, the stress distribution on the inclusion is evaluated. Those results are first obtained in the paper.     

On the Number of Fair Triangulations

In this paper a special kind of triangulated maps on the sphere called fair triangulations is enumerated with the size of maps as parameter. Moreover, the number of several other kinds of triangulations are enumerated as well. Received June 18, 1997, Accepted June 12, 1998     

Interest point detection in images using complex network analysis

This paper presents a new application of complex network theory and tools to digital image analysis and computer vision problems in order to detect interest points in digital images. We associate a weighted geometrical and fast computable complex network to each image and then we propose two different methods to locate these feature points based on both local and global (spectral) centrality measures of the corresponding network.     

Augmented Lagrangian-based preconditioners for steady buoyancy driven flow

In this paper, we apply the augmented Lagrangian (AL) approach to steady buoyancy driven flow problems. Two AL preconditioners are developed based on the variable’s order, specifically whether the leading variable is the velocity or the temperature variable. Correspondingly, two non-augmented Lagrangian (NAL) preconditioners are also considered for comparison. An eigenvalue analysis for these two pairs of preconditioners is conducted to predict the rate of convergence for the GMRES solver. The numerical results show that the AL preconditioner pair is insensitive with respect to the mesh size, Rayleigh number, and Prandtl number in terms of GMRES iterations, resulting in a significantly more robust preconditioner pair compared to the NAL pair. Accordingly, the AL pair performs much better than the NAL pair in terms of computational time. For the AL pair, the preconditioner with velocity as the leading variable gives slightly better efficiency than the one with temperature as the leading variable.