An improved harmony search algorithm to solve economic load dispatch problems with generator constraints

This paper presents a new improved harmony search (IHS) algorithm to solve non-convex economic load dispatch problems in the power system. In the proposed IHS algorithm, multiple harmony memory consideration rates and dynamic pitch adjusting rate are used to generate a new harmony/solution vector with enhanced solution quality. The effectiveness of the proposed IHS algorithm has been successfully tested in the test systems which consists of six units with ramp rate limits, prohibited operating zones and transmission loss, thirteen units with valve point effect, and ten units with multiple fuel options and valve point effect. The results obtained using the proposed IHS algorithm are compared with the results of other techniques reported in the literature. The comparative results reveal that the proposed IHS algorithm has good searching capacity to find the global optimal solution, than the other methods reported in the literature and also has good convergence characteristic.     

Adhesives with patterned sub-surface microstructures

Inspired by the complex hierarchical structures found in natural adhesives, we have embedded monolithic stack of several microchannels inside soft layers of silicon elastomers. These channels are rectangular in cross-section and their internal surfaces are textured with microscopic pillars arranged in regular arrays. Displacement controlled indentation experiment on these adhesives shows that adhesion and debonding occur not only on the surface of the adhesive but also at the interfaces of the embedded layers. These textures on the channel surface enhance adhesion via “crack arrest and initiation” mechanism. Furthermore, the adhesive is treated by hydrochloric acid so that the siloxane bonds present on the exposed surfaces are hydrolyzed generating silanol groups which on two contacting surfaces increase the effect of self adhesion hysteresis. Thus, the combined effect of surface texturing is integrated with the chemical treatment to increase adhesion.     

Cooperative lattice coding and decoding in half-duplex channels

We propose novel lattice coding/decoding schemes for half-duplex outage-limited cooperative channels. These schemes are inspired by the cooperation protocols of Azarian et al. and enjoy an excellent performance-complexity tradeoff. More specifically, for the. relay channel, we first use our lattice coding framework to generalize Yang and Belfiore implementation of the non-orthogonal amplify and forward cooperation protocol. This generalization is shown to offer significant performance gains while keeping the decoding complexity manageable. We then devise a novel variant of the dynamic decode and forward protocol, along with a lattice-coded implementation, which enjoys a near-optimal diversity-multiplexing tradeoff with a low encoding/decoding complexity. Finally, for the cooperative multiple-access channel, we present a lattice-coded implementation of the non-orthogonal amplify and forward protocol and demonstrate its excellent performance-complexity tradeoff. Throughout the paper, we establish the performance gains of our proposed protocols via a comprehensive simulation study     

Reliability analysis of safety grade decay heat removal system of Indian prototype fast breeder reactor

The 500 MW Indian pool type Prototype Fast Breeder Reactor (PFBR), is provided with two independent and diverse Decay Heat Removal (DHR) systems viz., Operating Grade Decay Heat Removal System (OGDHRS) and Safety Grade Decay Heat Removal System (SGDHRS). OGDHRS utilizes the secondary sodium loops and Steam–Water System with special decay heat removal condensers for DHR function. The unreliability of this system is of the order of 0.1–0.01. The safety requirements of the present generation of fast reactors are very high, and specifically for DHR function the failure frequency should be less than ∼1E-7/ry. Therefore, a passive SGDHR system using four completely independent thermo-siphon loops in natural convection mode is provided to ensure adequate core cooling for all Design Basis Events. The very high reliability requirement for DHR function is achieved mainly with the help of SGDHRS. This paper presents the reliability analysis of SGDHR system. Analysis is performed by Fault Tree method using ‘CRAFT’ software developed at Indira Gandhi Centre for Atomic Research. This software has special features for compact representation and CCF analysis of high redundancy safety systems encountered in nuclear reactors. Common Cause Failures (CCF) are evaluated by β factor method.     

Influence of air electrode electrocatalysts on performance of air-MH cells

Ni-MH battery system has been in limelight recently because of its inherent advantages like high-energy density, eco-friendly nature, devoid of memory effect, etc. Replacement of the heavy nickel oxide electrode with lighter air electrode is expected to improve its energy density further by 20% and also to bring down the cost. Hence some studies have appeared in literature on the development of air-MH system. But the main problem is to have an adequate bifunctional electrode with suitable electrocatalyst. Several materials are available for use in air electrodes. A detailed study is required to identify the best catalytic material and optimize the battery activity. Hence, air-MH cells using different oxides like _Ag2O${\mathrm{Ag}}_2\mathrm{O}$, _LaMnO3${\mathrm{LaMnO}}_3$ and _{La0.65Sr0.30MnO3}${\mathrm{La}}_{0.65}{\mathrm{Sr}}_{0.30}{\mathrm{MnO}}_3$ as catalysts for air electrode have been investigated in the present study with _{MmNi3.5Co0.8Mn0.4Al0.3}${\mathrm{MmNi}}_{3.5}{\mathrm{Co}}_{0.8}{\mathrm{Mn}}_{0.4}{\mathrm{Al}}_{0.3}$ metal hydride negative electrode. Life cycling along with charge and discharge characteristics was studied in detail. The air-MH cells assembled with _Ag2O${\mathrm{Ag}}_2\mathrm{O}$ and _LaMnO3${\mathrm{LaMnO}}_3$ as catalysts in the air electrode gave encouraging performance. _LaMnO3${\mathrm{LaMnO}}_3$ when incorporated as electrocatalyst delivered stable cycle life whereas incorporation of Sr resulted in inferior performance in the studied composition range.     

Durability against wetting-drying cycles for cement-stabilized reclaimed asphalt pavement blended with crushed rock

Pavement rehabilitation and reconstruction generate large quantities of reclaimed asphalt pavement (RAP). The improvement of the engineering properties of this RAP is required in order to enable it for use as environmentally friendly alternative construction material in road pavements. The durability of RAP when blended with crushed rock (CR) and stabilized with Portland cement was investigated in this paper. The CR replacement was found to improve the compactibility and durability of the stabilized RAP/CR material. For a particular RAP:CR ratio, the compaction curves of cement-stabilized RAP/CR blends were found to be essentially the same for all cement contents, but different for unstabilized blends; i.e., the maximum dry unit weight of cement-stabilized RAP/CR blends is higher than that of unstabilized RAP-CR blends. The wetting-drying (w-d) cycles led to a loss in weight of the cement-stabilized RCA/CR blends and to a subsequent reduction in strength. The w-d cycle strengths (q_u(w-d)) for a state of compaction (dry side, wet side or optimum water content) at any w-d cycle could be approximated from the corresponding initial soaked strength (prior to w-d tests) (q_u0). The q_u0 of cement-stabilized RAP/CR blends increased with an increasing CR replacement and an increasing cement content. Assuming that the CR replacement also results in an increasing cement content, w/[C(1?+?kCR_c)] was proposed as a critical parameter for developing q_u0 and q_u(w-d) predictive equations where w is the water content at the optimum water content, C is the cement content, k is the replacement efficiency, and CR_c is the CR content. Based on the q_u(w-d) predictive equation developed here, a design procedure for the laboratory mixing of cement-stabilized RAP/CR blends was proposed, which would be valuable for an accurate determination of the ingredients (RAP:CR ratio and cement content) required to attain the necessary strength at the design service life.     

Estimation of station blackout frequency for Indian fast breeder test reactor

This paper presents the comparison of station blackout (SBO) frequency computed with approximate time averaged expressions for diesel generator unavailability and time dependent cutset evaluation method. It is found that the frequency of SBO is under predicted by a factor of ∼2 by approximate time averaged expressions for SBO durations of 8 h and 16 h. The time dependent cutset evaluation method is applied for offsite power feeder outage management by treating the change in SBO frequency when one of the feeders is taken out for maintenance for ‘n’ days, as the risk measure.     

Valid Inequalities Based on Demand Propagation for Chemical Production Scheduling MIP Models

Although several mixed‐integer programming (MIP) models have been proposed for the scheduling of chemical manufacturing facilities, the development of solution methods for these formulations has received limited attention. In this article, we develop a constraint propagation algorithm for the calculation of lower bounds on the number and size of tasks necessary to satisfy given demand. These bounds are then used to express four types of valid inequalities which greatly enhance the computational performance of the MIP scheduling model. Specifically, the addition of these inequalities leads to reductions in the computational requirements of more than three orders of magnitude, thereby allowing us to address medium‐sized problems of industrial relevance. Importantly, the proposed methods are applicable to a wide range of problem classes and time‐indexed MIP models for chemical production scheduling. © 2013 American Institute of Chemical Engineers AIChE J, 59:872‐887, 2013     

A study of PFBR auxiliary neutron source strength activation and its variability with respect to the neutron spectrum and 123Sb capture cross section

PrFeB magnets, which possess excellent magnetic properties at low temperatures, have important application value as cryogenic permanent magnet undulators for synchrotron radiation sources and free electron lasers. In this research study, several high-performance PrFeB magnets(P42H, P48SH, and P48UH) were prepared, and their performance was comprehensively examined, including evaluations of their magnetic properties,microstructures, uniformity, and stability. Next,their application prospects were analyzed and discussed. In China, the first cryogenic permanent magnet undulators(CPMUs) with P48SH magnets with 18 mm cycle lengths have been developed. When the temperature is 80 K and the gap is 6.0 mm,the magnetic field measurement results of the CPMU showed that the effective magnetic field peak was approximately 0.92 T, yielding an increase of 11.76% relative to operation at 300 K, with an RMS phase error of about 4.99°.     

Failure Analysis of a Cam Gear in the Torquemeter Assembly of a Turboprop Engine

Journal of Failure Analysis and Prevention - Failure analysis of a cam gear in the torquemeter assembly of a turboprop engine has been carried out to determine the root cause of the failure so that...