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81.
In a production system, rework process plays an important role in eliminating waste and effectively controlling the cost of manufacturing. Determining the optimal batch size in a system that allows for rework is, therefore, a worthwhile objective to minimize the inventory cost of work-in-processes and the finished goods. In this paper, models for the optimum batch quantity in a multi-stage system with rework process have been developed for two different operational policies. Policy 1 deals with the rework within the same cycle with no shortage and policy 2 deals with the rework done after N cycles, incurring shortages in each cycle. The major components that play a role in minimizing this cost of the system are manufacturing setups, work-in-processes, storage of finished goods, rework processing, waiting-time, and penalty costs to discourage the generation of defectives. The mathematical structure of this rework processing model falls under a nonlinear convex programming problems for which a closed-form solution has been proposed and results are demonstrated through numerical examples, followed by sensitivity analyses of different important parameters. It is concluded that the total cost in policy 2 tends to be smaller than that in policy 1 at lower proportion of defectives if the in-process carrying cost is low. Policy 2 may be preferred when the work-in-process carrying cost is low and the penalty cost is negligible. 相似文献
82.
83.
The diastereoselective synthesis of the macrolactone core of amphidinolide W was successfully accomplished using Evans’ asymmetric alkylation, Aldol reaction, Julia-Kocienski olefination, and Kita’s macrocyclization protocol. 相似文献
84.
Copper crystals have been grown by Czochralski technique in a 6-bar argon gas environment. X-ray analysis shows that these
are single crystals and are strain-free. A slight pressure environment that is truly hydrostatic seems to improve the quality
of the crystals. Thermal profile estimation results show that the values of temperature which decrease upto the neck region
are same in magnitude as those measured during the experiments and that necking improves the thermal profile and, consequently,
the crystal quality. No facet formation has been observed in these crystals. 相似文献
85.
Ambarish Ray Dipankar Maity Anup Pramanik Kalyan K. Das Mahasweta Nandi Asim Bhaumik M. Nethaji Swastik Mondal Monika Mukherjee Mahammad Ali 《Polyhedron》2009,28(17):3659-3666
Two new copper(II) complexes, [Cu2(L1)2](ClO4)2 (1) and [Cu(L2)(ClO4)] (2), of the highly unsymmetrical tetradentate (N3O) Schiff base ligands HL1 and HL2 (where HL1 = N-(2-hydroxyacetophenone)-bis-3-aminopropylamine and HL2 = N-(salicyldehydine)-bis-3-aminopropylamine) have been synthesised using a template method. Their single crystal X-ray structures show that in complex 1 two independent copper(II) centers are doubly bridged through phenoxo-O atoms (O1A and O1B) of the two ligands and each copper atom is five-coordinated with a distorted square pyramidal geometry. The asymmetric unit of complex 2 consists of two crystallographically independent N-(salicylidene)-bis(aminopropyl)amine-copper(II) molecules, A and B, with similar square pyramidal geometries. Cryomagnetic susceptibility measurements (5–300 K) on complex 1 reveal a distinct antiferromagnetic interaction with J = ?23.6 cm?1, which is substantiated by a DFT calculation (J = ?27.6 cm?1) using the B3LYP functional. Complex 1, immobilized over highly ordered hexagonal mesoporous silica, shows moderate catalytic activity for the epoxidation of cyclohexene and styrene in the presence of TBHP as an oxidant. 相似文献
86.
Synthesis of stereoisomers of 6′‐mono‐ and 4′,6′‐di‐O‐benzyl cryptofolione is described through a key intermediate 6 , which was prepared by coupling of iodobenzene 8 with chiral propargyl alcohol 9 under Cosford protocol conditions. Monobenzyl ether 4 is obtained via epoxide 6 opening with vinyl Grignard, followed by cross‐metathesis reaction with a vinyl lactone 11 . Whereas, dibenzyl ether 5 is prepared by epoxide 6 opening with chiral propargyl alcohol 7 followed by simple transformations and finally cis‐Wittig olefination. 相似文献
87.
Banerjee I Mondal D Martin J Kane RS 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):17369-17374
We report the design of antimicrobial nanocomposite films based on conjugates of multiwalled carbon nanotubes (MWNT) and protoporphyrin IX (PPIX) that are highly effective against Staphylococcus aureus (S. aureus) upon irradiation with visible light. S. aureus infections can lead to life-threatening situations, especially when caused by antibiotic-resistant strains. While the light-activated antimicrobial activity of porphyrins against such pathogens is well-known, a facile way to incorporate porphyrins into coatings may lead to their more effective use. To that end, we decided to synthesize and characterize MWNT-PPIX conjugates which combine the biocidal capacity of porphyrins with the mechanical strength of MWNTs. The conjugates could effectively deactivate S. aureus cells in solution upon irradiation with visible light. We also designed large area nanocomposite films comprised of the MWNT-PPIX conjugates that showed potent antimicrobial activity. These MWNT-PPIX conjugates represent a facile strategy for the design of antimicrobial and antifouling coatings. 相似文献
88.
Gowravaram Sabitha Bhaskar Vangala S. Siva Sankara Reddy Jhillu S. Yadav 《Helvetica chimica acta》2010,93(2):329-338
Ring‐closing metathesis (RCM) and olefin cross‐metathesis (CM) reactions were used as the key steps for the synthesis of (+)‐cryptocaryalactone ( 1 ) and the first synthesis of the diastereoisomer 3 of (+)‐strictifolione, starting from the commercially available L ‐malic acid (=(2S)‐2‐hydroxybutanedioic acid). 相似文献
89.
Subhendu Naskar Priyankar Paira Rupankar Paira Shyamal Mondal Arindam Maity Abhijit Hazra Krishnendu B. Sahu Pritam Saha Sukdeb Banerjee Peter Luger Manuela Webe Nirup B. Mondal 《Tetrahedron》2010,66(27-28):5196-5203
An environmentally benign protocol has been described for the synthesis of novel 2-(1′,3′-dihydro-1H-[2,3′]biindolyl-2′-ylidene)-indan-1,3-diones/bis-indolylindane-1,3-diones from ninhydrin and 3-substituted/unsubstituted indoles. It uses montmorillonite K-10 as catalyst in a solvent-free condition under microwave irradiation. The method was also used for the synthesis of novel bisindolylindeno[1,2-b]quinoxaline derivatives. 相似文献
90.
G. Bhaskar 《Tetrahedron letters》2010,51(23):3141-8145
Indium(III) bromide-catalyzed hydroarylation of alkynes with indoles leading to the synthesis of 3-vinylindoles in good to excellent yields was achieved. The E/Z ratio of the products depends on the substituents on the indole. This protocol is efficient and atom-economic from the synthetic point of view. 相似文献