Optimal Allocation and Operating Point of DG Units in Radial Distribution Network Considering Load Pattern

Distributed generation (DG) is a new approach for solving some problems of older power networks. Due to the increasing power demand in recent power systems, the importance of power loss reduction and maintaining system voltages within an acceptable range has given rise to the wide use of DG units in power systems. On the other hand, unplanned and non-optimal application such as installation and operation of DG units might cause other technical problems. In addition, it is important to consider the load pattern in the network, and the best decision for DG unit's operation must be chosen accordingly. In this paper, a method is introduced in order to make the optimal placement and find an optimal operating point for the DG units, which means the power output of DG units, considering the load pattern of the network. This load pattern has an average load of 24 hr a day, four seasons a year. In the proposed method, optimization has two goals: first, is optimizing the DG unit's placement based on improvement of the voltage profile, and the second is operating DG units with optimum power factor, minimizing power loss, and improving voltage profile, with regard to the load pattern. In order to solve this problem, the gravitational search algorithm and genetic algorithm are used. The proposed method is applied on the IEEE 33-bus test system, and the result shows the effectiveness of the proposed method. In order to solve the optimization problem, MATLAB software is used.     

Influence of Haunches on Performance of Precast-Concrete, Short-Span, Skewed Bridges with Integral Abutment Walls

Precast-concrete, skewed bridges with integral abutment walls are, typically, designed as simplified plane rigid portal frames, neglecting the degrading effects of the skew angle, the influence of haunches between the abutment walls and the deck, and laterally unsymmetrical vertical loading. This practice produces underdesigned bridges for certain aspect ratios. It is well known that the higher shear and torsional moments near the obtuse corners cause cracking and local deterioration. To evaluate the limitations of this practice, an experimental and analytical study was carried out for the live load response at the linear service level. It has been observed that for certain bridge configurations, both the positive and negative moment stresses are higher than the stresses given by plane frame analysis. The presented qualitative results enable comparison of performance characteristics.     

Improving the efficiency of a mixed integer linear programming based approach for multi-class classification problem

Data classification is one of the fundamental issues in data mining and machine learning. A great deal of effort has been done for reducing the time required to learn a classification model. In this research, a new model and algorithm is proposed to improve the work of Xu and Papageorgiou (2009). Computational comparisons on real and simulated patterns with different characteristics (including dimension, high overlap or heterogeneity in the attributes) confirm that, the improved method considerably reduces the training time in comparison to the primary model, whereas it generally maintains the accuracy. Particularly, this speed-increase is significant in the case of high overlap. In addition, the rate of increase in training time of the proposed model is much less than that of the primary model, as the set-size or the number of overlapping samples is increased.     

Software development for design and simulation of terraced wall and top fired primary steam reformers

In recent years, many research activities have been carried out on effective use of natural gas. The first step for this process, however, is converting natural gas to synthesis gas (syngas). Natural gas reforming process by means of a reformer furnace is commonly used for syngas and hydrogen production.

In this paper a windows-based software, RIPI-RefSim, is introduced. By using rigorous heat, mass, kinetic and thermodynamic models as well as taking into account the effect of catalyst shape, the software has been developed in order to provide reformer furnace simulation for syngas and hydrogen production. RIPI-RefSim can be used in three different modes (rating, simulation and design) and provides a detailed understanding of furnace performance, product characteristics, temperature, reaction rates and pressure drop profiles, effect of catalyst shape, and so on.     

Viscoelastic behaviour effect of hyaluronic acid on reciprocating flow inside mini‐channel

One of the most successful surgeries during the 21^st century is total joint replacement (TJR) with material combination of polymer‐on‐metal (PoM). Despite its success, wear particle generation at the interface of the polymer and metal causes eventually implant loosening. Investigating and understanding the wear particles distribution should help in designing implants with better performances. First step towards characterising wear particle distribution is deriving the lubricant behaviour and velocity distribution inside implant gap. Different hyaluronic acid (HA) solutions were subjected to a sinusoidal movement in straight rectangular channels. The velocity profiles along the channel width were measured with Micro Particle Image Velocimetry. HA solution behaviour was found to be dependent on the concentration. Results showed significant differences between the water (Newtonian) and HA behaviour in unsteady flow. The unsteady behaviour of the lubricant depended strongly on its non‐Newtonian viscoelastic behaviour which was due to the time dependent nature of HA solution. Copyright © 2016 John Wiley & Sons, Ltd.