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131.
M. S. Murugan S. Suresh R. Ganguli V. Mani 《Structural and Multidisciplinary Optimization》2007,33(2):131-146
This paper aims to obtain the optimal composite box-beam design for a helicopter rotor blade. The cross-sectional dimensions
and the ply angles of the box beam are considered as design variables. The objective is to optimize the box beam to attain
a target vector of stiffness values and maximum elastic coupling. The target vector is the optimal stiffness values of helicopter
rotor blade obtained from a previous aeroelastic optimization study. The elastic couplings introduced by the box beam have
beneficial effects on the aeroelastic stability of helicopter. The optimization problem is addressed by decomposing the optimization
into two levels, a global level and a local level. The box-beam cross-sectional dimensions are optimized at the global level.
The local-level optimization is a subproblem which finds optimal ply angles for each cross-sectional dimension considered
in the global level. Real-coded genetic algorithm (RCGA) is used as the optimization tool in both the levels of optimization.
Hybrid operators are developed for the RCGA, thereby enhancing the efficiency of the algorithm. Min–max method is used to
scalarize the multiobjective functions used in this study. Optimal geometry and ply angles are obtained for composite box-beam
designs with ply angle discretization of 1010, 1515, and 45o45^o. 相似文献
132.
Deciding the strategy for production and distribution in a stochastic demand scenario is important for the manufacturing industries. An integrated production–distribution plan considering regular, overtime and outsourced production costs along with inventory holding, backorder, hiring/laying-off and trip-wise distribution costs is developed for a renowned bearing manufacturing industry producing three types of products at three locations. Demand is assumed to vary uniformly and a novel simulation based heuristic discrete particle swarm optimization (DPSO) algorithm is used for obtaining the best production–distribution plan that serves as a trade-off between holding inventory and backordering products. The algorithm also uses an innovative regeneration type constraint handling method which does not require a penalty operator. In addition to the bearing manufacturing industry data set, two other test data sets are also solved. The simulation based optimization approach gives good approximate solutions for the stochastic demand problems. 相似文献
133.
V. Udhayabanu K. R. Ravi K. Murugan D. Sivaprahasam B. S. Murty 《Metallurgical and Materials Transactions A》2011,42(7):2085-2093
In the present study, Ni-30 vol pct Al2O3
in-situ nanocomposite was developed by reactive milling of NiO-Al-Ni powder mixture followed by spark plasma sintering (SPS). During
milling, fcc to hcp transformation was observed in Ni(Al) phase and it transformed back to fcc phase around 773 K (500 °C).
The hardness and yield strength of Ni-30 vol pct Al2O3 nanocomposite are approximately two times higher than that of pure Ni of similar grain size. The improved mechanical properties
of nanocomposite are attributed to the presence of alumina particles of nanometer size. 相似文献
134.
A transaction mapping algorithm for frequent itemsets mining 总被引:1,自引:0,他引:1
Song M. Sanguthevar Rajasekaran 《Knowledge and Data Engineering, IEEE Transactions on》2006,18(4):472-481
In this paper, we present a novel algorithm for mining complete frequent itemsets. This algorithm is referred to as the TM (transaction mapping) algorithm from hereon. In this algorithm, transaction ids of each itemset are mapped and compressed to continuous transaction intervals in a different space and the counting of itemsets is performed by intersecting these interval lists in a depth-first order along the lexicographic tree. When the compression coefficient becomes smaller than the average number of comparisons for intervals intersection at a certain level, the algorithm switches to transaction id intersection. We have evaluated the algorithm against two popular frequent itemset mining algorithms, FP-growth and dEclat, using a variety of data sets with short and long frequent patterns. Experimental data show that the TM algorithm outperforms these two algorithms. 相似文献
135.
Murugan Natarajan Vigneshwaran Basharan Kannayeram Ganapathya Pillai Maheswari Ramasamy Velayutham Willjuice Iruthayarajan Maria Silluvairaj 《电力部件与系统》2015,43(5):566-577
In this article, analysis of electric field stress and electric potential distributions of a 33-kV composite insulator and factors that affect the electric field are discussed. Accordingly, the article is classified into two parts. In the first part, the designs of three different configurations of non-ceramic (composite) insulator based on their geometry modification in end fittings and water shed are discussed. The electrical performances are analyzed using electric field and electrical potential distribution. In the second part, a reduction of the electric field near the end fittings is done to control the electric field stress intended for long-term performance. For that, the grading material is placed between the core and housing materials by fitting the arcing horn near the end fittings. A 33-kV composite insulator is modeled in two dimensions by the finite-element method to investigate the electric field and electric potential distribution under normal and polluted conditions. The results reveal that an optimum installation of an arcing horn at the high-voltage end in the composite insulator with silicone rubber overlapping the edges of metal end fittings made a significant reduction in electric field stress on 33-kV non-ceramic insulators. 相似文献
136.
The large variation in specific heats with concentration between temperatures 50 K and 200 K for Al-Si and Al-Ge alloys are
analysed in detail by lattice dynamical and Monte Carlo approaches. The large deviation from linearity at low temperatures
does not seem to be due to the Debye’s low temperature contribution. It is shown that an anharmonic vibration in the above
solid solutions, particularly at 200 K, is the cause for the small variation in the specific heat. 相似文献
137.
138.
P. Murugan R Pothiraj S. D. D. Roy K. Ramachandran 《Bulletin of Materials Science》2002,25(4):335-340
Theoretical studies are carried out to ascertain the dominant mechanism of Si diffusion in GaAs. Lattice dynamical model calculations
have shown that the most probable diffusion mechanism is through a single vacancy even though several experiments cannot fix
the mechanism as substitutional, substitutional-interstitial pair or neutral defect pair. 相似文献
139.
140.
D. Dini C. Churchman R. Rajasekaran D. A. Hills 《International Journal of Mechanical Sciences》2004,46(3):491-508
A careful analytical comparison is made of the size and shape of the process zones present in a range of fretting fatigue experiments. These include the conventional Hertzian contact, the ‘flat and rounded’ pad problem and the classical square-ended pad geometries. The results clearly display the load and geometry regimes where the ‘flat and rounded’ pad performance may be matched with either of the limiting forms. This should permit a unifying re-interpretation of fatigue data already obtained from each of the three sources. 相似文献