Feeder Reconfiguration in Distribution Networks Based on Convex Relaxation of OPF

The feeder reconfiguration problem chooses the on/off status of the switches in a distribution network in order to minimize a certain cost such as power loss. It is a mixed-integer nonlinear program and, hence, hard to solve. In this paper, we propose a heuristic algorithm that is based on the recently developed convex relaxation of the ac optimal power flow problem. The algorithm is computationally efficient and scales linearly with the number of redundant lines. It requires neither parameter tuning nor initialization for different networks. It successfully computes an optimal configuration on all four networks we have tested. Moreover, we have proved that the algorithm solves the feeder reconfiguration problem optimally under certain conditions for the case where only a single redundant line needs to be opened. We also propose a more computationally efficient algorithm and show that it incurs a loss in optimality of less than 3% on the four test networks

The Reconstruction of China's Regional Economic Pattern under the Background of "The Belt and Road" Strategy

The excessive development structure between China regions is generated in the process of industrialization and urbanization, and it is concentrated in an unequal spatial structure. The strategic concept of "The Belt and Road" provides an opportunity for the coordinated development of China's regional economy. On the one hand, it helps to promote economic transformation and upgrading in eastern China. On the other hand, it is helpful to realize the rising of central China and the opening of the western border zone, and optimize the regional development pattern. In this study, we propose that the regional coordination should be established by using "The Belt and Road" strategy. First of all, building a multi-center urban network to stimulate the economic development in the central and western regions; secondly, balancing the interests of different regions with a multi-level regional coordination mechanism and finally, forming a new pattern of coordinated regional development with institutionalized regional ecosystems. Keywords: The Belt and Road, regional imbalance, multi-center, regional coordination mechanism, institutio

Security of a new two-way continuous-variable quantum key distribution protocol

The original two-way continuous-variable quantum-key-distribution (CV QKD) protocols [S. Pirandola, S. Mancini, S. Lloyd, and S. L. Braunstein, Nature Physics 4, 726 (2008)] give the security against the collective attack on the condition of the tomography of the quantum channels. We propose a family of new two-way CV QKD protocols and prove their security against collective entangling cloner attacks without the tomography of the quantum channels. The simulation result indicates that the new protocols maintain the same advantage as the original two-way protocols whose tolerable excess noise surpasses that of the one-way CV-QKD protocol. We also show that all sub-protocols within the family have higher secret key rate and much longer transmission distance than the one-way CV-QKD protocol for the noisy channel.Comment: 19 pages, 4 figures, accepted for publication in International Journal of Quantum Informatio

Extraction optimization and characterization of polysaccharide antioxidants from Pinellia ternata (Thunb) Breit rhizome

Purpose: To investigate the optimum extraction conditions of polysaccharides from Pinellia Rhizoma (PRP) and their antioxidant activities.Methods: Response surface methodology (RSM) was applied to optimize the water extraction conditions of PRP by Box-Benhnken design (BBD). A high performance liquid chromatography (HPLC) method was performed for determining the monosaccharide composition, while a high performance gel permeation chromatography (HPGPC) method was established for determining the molecular weight distribution of PRP. In addition, scavenging DPPH and superoxide anion radical scavenging assays were used to evaluate the antioxidant activities of PRP.Results: As a result, the optimum extraction conditions of PRP were as follows: extraction time, 103 min; solid-liquid ratio, 24 g/mL; and extraction no., 3. Under these conditions, the maximum extraction yield of PRP was 2.47 %, which matched the optimum value (2.55 %) predicted by RSM. The results of HPLC analysis suggest that the monosaccharide composition of PRP was mannose (Man), galactose acid (Gal acid), galactose (Gal), glucose (Glc), and arabinose (Ara) in molar ratios of 5.76:2.20:2.64:4.57:1, respectively, and the molecular weight ranged from 13592 to 445065. Furthermore, PRP showed marked antioxidant activities with the highest DPPH free radical scavenging rate of 71.5 % and O2- free radical scavenging rate of 87.5 % at a concentration of 10 mg/mL.Conclusion: RSM is a rapid and effective statistical technique for optimizing conditions for PRP extraction. Furthermore, PRP is a potential natural source of antioxidants.Keywords: Pinellia rhizoma, Polysaccharides Optimization extraction, Monosaccharide composition, Antioxidant activit

New CZM for Interfacial Crack Growth

The cohesive zone model (CZM) has been widely used for numerical simulations of interface crack growth. However, geometrical and material discontinuities decrease the accuracy and efficiency of the CZM when based on the conventional finite element method (CFEM). In order to promote the development of numerical simulation of interfacial crack growth, a new CZM, based on the wavelet finite element method (WFEM), is presented. Some fundamental issues regarding CZM of interface crack growth of double cantilever beam (DCB) testing were studied. The simulation results were compared with the experimental and simulation results of CFEM. It was found that the new CZM had higher accuracy and efficiency in the simulation of interface crack growth. At last, the impact of crack initiation length and elastic constants of material on interface crack growth was studied based on the new CZM. These results provided a basis for reasonable structure design of composite material in engineering