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排序方式: 共有172条查询结果,搜索用时 31 毫秒
81.
Saravanan Venkatachalam 《国际生产研究杂志》2016,54(14):4087-4103
Integrated inventory and transportation decisions are critical in the supply chain, providing significant gains for all parties. In this paper, we present a mathematical formulation for the dynamic demand multi-item single source replenishment problem with a piecewise linear transportation cost. Through an extensive experimental study, we find that the new formulation provides a tighter LP relaxation of the problem, while requiring fewer computational resources to optimally solve the problem when compared with existing model in the literature. We also present a new metaheuristic for this general class of coordinated capacitated replenishment problems. On average, the solutions from heuristics are within 1.23% of the optimal solution for the comprehensive set of test problems. 相似文献
82.
Venkatachalam K Arzuaga X Chopra N Gavalas VG Xu J Bhattacharyya D Hennig B Bachas LG 《Journal of hazardous materials》2008,159(2-3):483-491
Palladium-based nanoparticles immobilized in polymeric matrices were applied to the reductive dechlorination of 3,3',4,4'-tetrachlorobiphenyl (PCB77) at room temperature. Two different dechlorination platforms were evaluated using (1) Pd nanoparticles within conductive polypyrrole films; or (2) immobilized Fe/Pd nanoparticles within polyvinylidene fluoride microfiltration membranes. For the first approach, the polypyrrole film was electrochemically formed in the presence of perchlorate ions that were incorporated into the film to counter-balance the positive charges of the polypyrrole chain. The film was then incubated in a solution containing tetrachloropalladate ions, which were exchanged with the perchlorate ions within the film. During this exchange, reduction of tetrachloropalladate by polypyrrole occurred, which led to the formation of palladium nanoparticles within the film. For the second approach, the membrane-supported Fe/Pd nanoparticles were prepared in three steps: polymerization of acrylic acid in polyvinylidene fluoride microfiltration membrane pores was followed by ion exchange of Fe(2+), and then chemical reduction of the ferrous ions bound to the carboxylate groups. The membrane-supported iron nanoparticles were then soaked in a solution of tetrachloropalladate resulting in the deposition of Pd on the Fe surface. The nanoparticles prepared by both approaches were employed in the dechlorination of PCB77. The presence of hydrogen was required when the monometallic Pd nanoparticles were employed. The results indicate the removal of chlorine atoms from PCB77, which led to the formation of lower chlorinated intermediates and ultimately biphenyl. Toxicity associated with vascular dysfunction by PCB77 and biphenyl was compared using cultured endothelial cells. The data strongly suggest that the dechlorination system used in this study markedly reduced the proinflammatory activity of PCB77, a persistent organic pollutant. 相似文献
83.
The electrochemical behaviour of 4(2′-thienyl)quinazoline (4-TQ) was studied in acid solutions of varying ionic strengths using polarography, cyclic voltammetry and controlled-potential electrolysis. 4-TQ is reduced in two single electron steps to give the dihydro-4-TQ product. The two polarographic waves were found to be diffusion-controlled, the first wave being reversible and the second wave irreversible. On the basis of the results obtained, a mechanism is suggested for 4-TQ reduction in which a dimerization reaction goes in parallel with the electron-transfer step. 相似文献
84.
Gopalu Karunakaran Rangaraj Suriyaprabha Venkatachalam Rajendran Narayanasamy Kannan 《IET nanobiotechnology / IET》2016,10(4):171
The focus of this investigation is to evaluate the phytotoxicity of selected metal oxide nanoparticles and microparticles as a function of maize seed germination and root elongation under different growth conditions (Petri plate, cotton and soil). The results of seed germination and root elongation experiments reveal that all the growth conditions show almost similar results. Alumina (Al2 O3) and titania (TiO2) nanoparticles significantly reduce the germination percentage, whereas silica (SiO2) nanoparticles and microparticles enhance the same. The results of nanoparticles and microparticles of zirconia (ZrO2) are found to be same as those of controls. Root elongation is enhanced by SiO2 nanoparticles and microparticles treatment, whereas inhibition is observed with Al2 O3 and TiO2 nanoparticles and microparticles. The X‐ray fluorescence spectrometry data of the treated and control seed samples show that seeds uptake SiO2 particles to a greater extent followed by TiO2, Al2 O3 and ZrO2. In addition, the uptake of nanoparticles is found to be greater than that of microparticles. Thus, the tested metal oxides penetrated seeds at the nanoscale as compared with the microscale. This study clarifies phytotoxicity of nanoparticles treated in different growth substrates and highlights the impact of nanoparticles on environment and agricultural systems.Inspec keywords: zirconium compounds, silicon compounds, aluminium compounds, titanium compounds, nanoparticles, nanobiotechnology, botany, toxicologyOther keywords: metal oxide nanoparticles, maize seed germination, phytotoxicity, microparticles, root elongation, growth conditions, Petri plate, cotton, soil, X‐ray fluorescence spectrometry, environment systems, agricultural systems, ZrO2 , SiO2 , Al2 O3 , TiO2 相似文献
85.
Milos Mravik T. Vetriselvi K. Venkatachalam Marko Sarac Nebojsa Bacanin Sasa Adamovic 《计算机、材料和连续体(英文)》2022,71(1):457-471
At present, the prevalence of diabetes is increasing because the human body cannot metabolize the glucose level. Accurate prediction of diabetes patients is an important research area. Many researchers have proposed techniques to predict this disease through data mining and machine learning methods. In prediction, feature selection is a key concept in preprocessing. Thus, the features that are relevant to the disease are used for prediction. This condition improves the prediction accuracy. Selecting the right features in the whole feature set is a complicated process, and many researchers are concentrating on it to produce a predictive model with high accuracy. In this work, a wrapper-based feature selection method called recursive feature elimination is combined with ridge regression (L2) to form a hybrid L2 regulated feature selection algorithm for overcoming the overfitting problem of data set. Overfitting is a major problem in feature selection, where the new data are unfit to the model because the training data are small. Ridge regression is mainly used to overcome the overfitting problem. The features are selected by using the proposed feature selection method, and random forest classifier is used to classify the data on the basis of the selected features. This work uses the Pima Indians Diabetes data set, and the evaluated results are compared with the existing algorithms to prove the accuracy of the proposed algorithm. The accuracy of the proposed algorithm in predicting diabetes is 100%, and its area under the curve is 97%. The proposed algorithm outperforms existing algorithms. 相似文献
86.
Vimalanand Suthenthiraveerappa Venkatachalam Gopalan Ananda Babu Arumugam Balamurugan Ramasamy 《Advanced Composite Materials》2019,28(2):163-191
Evolution of the laminated woven natural fiber fabric-reinforced polymer composite structures makes a way to the development of the non-uniform laminated composite structures in order to achieve the stiffness variation throughout the structure. An attempt is made in this work to carry out the experimental and numerical investigations on the dynamic characteristics of the thickness-tapered laminated woven jute/epoxy and woven aloe/epoxy composite plates. The governing differential equations of motion for the thickness-tapered laminated composite plate are developed using the h-p version FEM based on higher order shear deformation theory. The validation of the present finite element formulation is carried out by comparing the natural frequencies obtained using the finite element formulation with those natural frequencies determined experimentally. The developed model is further validated with the available literature works on tapered composite plate to confirm the efficiency of h-p version FEM. This work also explores the study of the vibrational characteristics of composite plates under the influence of plant fiber’s transverse isotropic material characteristics and porosity associated with plant fiber composites through the elastic constants evaluated in the author’s previous work. Also the influences of aspect ratios, ply orientations, and taper angles under various end conditions on the natural frequencies of the woven jute/epoxy composite plate are studied using the present finite element formulation. The forced vibration response of the thickness-tapered laminated woven jute/epoxy composite plate under the harmonic force excitation is carried out considering CFCF and CFFF end conditions. 相似文献
87.
M. N. Khan A. Venkatachalam Ashfaq Ahmad V. S. Darshane 《Journal of Materials Science》1990,25(1):595-598
X-ray diffraction studies performed here indicated solid-solution formation between ZnCr2Se4 and CuCr2Se4, and all the compounds could be indexed on the basis of cubic spinel lattice. The compositions between 0 x 0.8 showed semi-conducting behaviour, while CuCr2Se4 (x=1.0) exhibited metallic conductivity. Seebeck measurements showd P-type behaviour for 0 x 1. Magnetic hysteresis indicated a ferromagnetic nature for all the compounds except ZnCr2Se4 (x=0). The shapes of/
i plotted againstT exhibited single domain behaviour, and Curie temperatures showed an increase with increasing copper concentration. 相似文献
88.
Mozhiarasi Velusamy Balakumar Rajan Benish Rose Pious Michealammal Speier Christopher Josef Weichgrebe Dirk Srinivasan Shanmugham Venkatachalam Suthanthararajan Rengasamy 《Clean Technologies and Environmental Policy》2021,23(9):2727-2740
Clean Technologies and Environmental Policy - The organic wastes generated from centralized wholesale markets from urban centres are predominantly disposed in dumpsites/landfills. Although... 相似文献
89.
Dibyaranjan Rout Gunda Santosh Babu Venkatachalam Subramanian Venkatasubramanian Sivasubramanian 《International Journal of Applied Ceramic Technology》2008,5(5):522-528
The complex perovskite Ba(Yb1/2 Ta1/2 )O3 has been prepared by the two-stage solid-state reaction method. Rietveld' refinement analysis indicates cubic perovskite phase with space group . The 1:1 cation ordering at the B-site is revealed by the presence of (111) superlattice reflection in the X-ray diffraction pattern and further evidenced by the presence of A1g and F2g vibrational modes in the Raman spectra. The dielectric constant is measured to be 29.1, the product of quality factor and resonant frequency ( Q × f ) is found to be 32,000 GHz and the temperature coefficient of resonant frequency (τf ) is 135 (ppm/°C) in the temperature range 30–70°C. 相似文献
90.