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161.
Structuring product development processes 总被引:1,自引:0,他引:1
Reza Ahmadi Thomas A. Roemer Robert H. Wang 《European Journal of Operational Research》2001,130(3):539-558
This paper proposes operational frameworks for structuring product development processes. The primary objective of this research is to develop procedures to minimize iterations during the development process which adversely affect development time and costs. Several procedures are introduced to restructure the development process. The computation of the corresponding product development times is facilitated by two Markov models addressing different types of learning. The methodologies are employed to identify a set of managerial concerns in restructuring the product development processes.The developed framework has become an integral part of a re-engineering project for the development of rocket engines at Rocketdyne Division of Rockwell International. Throughout the paper, the methodologies are illustrated with the help of this process. 相似文献
162.
Hajimohammadi Mahdi Ahmadi Khamesi Zahra Nosrati Parisa 《Transition Metal Chemistry》2019,44(2):167-173
Transition Metal Chemistry - The aerobic oxidation of a variety of aromatic aldehydes to the corresponding carboxylic acids by molecular oxygen in the presence of 4-carboxyl tetraphenylporphyrin... 相似文献
163.
Mohammad Hossein Jandaghian Saeid Ahmadjo Seyed Mohammad Mahdi Mortzavi Mostafa Ahmadi 《应用有机金属化学》2020,34(4):e5496
The reactive co-polymer approach is one of the most promising techniques for the synthesis of functional polyolefins. Following this concept, 1-hexene and p-methylstyrene are co-polymerized in the presence of a generic Brookhart-type catalyst. The microstructures of the co-polymers imply the tendency of p-methylstyrene co-monomers to place at the end of the structural branches formed by the chain walking reaction. The molar masses of the co-polymers decrease, not only at higher levels of co-monomer but surprisingly by decreasing reaction temperature. A mechanism consisting of a highly stable η3 metal–benzyl intermediate, which is quantitatively approved by density functional theory calculations, can delicately justify all the aforementioned observations. A series of the produced co-polymers is selectively functionalized by maleic anhydride at the benzylic position of p-methylstyrene, under very mild reaction conditions. Such a reactive intermediate opens the path for the introduction of different types of functionalities in polyolefins. Namely, the grafted co-polymers were further functionalized by a triazole ring, which provides a transient supramolecular network through intermolecular hydrogen bonding. 相似文献
164.
Gan Ting Ming Tingzhen Fang Weijie Liu Yang Miao Lei Ren Kun Ahmadi Mohammad Hossein 《Journal of Thermal Analysis and Calorimetry》2020,141(1):45-56
Journal of Thermal Analysis and Calorimetry - With the rapid increasing heat fluxes released from micro electronic devices, thermal management of electric components faces huge challenge. High... 相似文献
165.
AbstractWe introduce diffeological algebraic hyperstructures such as diffeological hypergroups and diffeological polygroups, which are generalizations of diffeological groups. After providing some examples of these notions, we investigate the relationships between diffeological hypergroups and diffeological groups. It is proved that there is an equivalence of categories between subductions over diffeological groups and diffeological complete hypergroups. We finally show how every diffeological polygroup is a subpolygroup of a diffeological poly-monoid of hyper-diffeomorphisms.Communicated by J. L. Gomez Pardo 相似文献
166.
Baharak Bahramnezhad Dadkhoda Ghazanfari Enayatollah Sheikhhosseini Mohammad Reza Akhgar Sayed Ali Ahmadi 《Journal of heterocyclic chemistry》2020,57(1):173-181
In this work, MnSb2O6-chitosan nanocomposites were synthesized and have been employed in Pechmann condensation for the synthesis of coumarin derivatives. MnSb2O6-chitosan nanocomposites were characterized by Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX) techniques. The particles of MnSb2O6-chitosan have uniform spheres with sizes that are less than 100 nm. Simplicity, easy work-up, and short reaction times are advantages of this reaction. Also, we evaluated the antibacterial activity for some of the products, and the result showed significant pharmaceutical activities as antibacterial reagents against Staphylococcus aureus and Escherichia coli. 相似文献
167.
A minimal distortion localization procedure is devised for defining subsystems in super-molecule calculations on weakly bonded
complexes. When a set of orbitals for the isolated subsystem have been chosen, the localized supersystem orbitals are obtained
by minimizing the sum of the least-square deviations from the isolated subsystem orbitals. Test calculations are presented
for the beryllium complexes Be2, Be3 and Be4, and the neon dimer.
Received: 15 December 1996 / Accepted: 15 March 1997 相似文献
168.
Cyclic voltammetry has been used to investigate the behaviour of sulphate and perchlorate anions adsorbed on Ir{111} and polycrystalline rhodium. In 0.1 M HClO4, perchlorate anions decompose on polycrystalline rhodium to give a surface intermediate which inhibits hydrogen adsorption. This is in agreement with a previous study by Wieckowski and coworkers, who showed that the surface intermediate was, in fact, adsorbed chloride. The voltammetry of the same electrode in sulphate containing electrolytes depends critically on the concentration of sulphate and the potential sweep rate. We conclude that hydrogen adsorption can only occur after significant desorption of sulphate. Hysteresis in the adsorption and desorption of sulphate results in an asymmetric hydrogen adsorption region with respect to the potential axis. Ir{111} is shown also to cause decomposition of perchlorate anions, although, contrary to the case of rhodium, the process is very much a chemical one in which electric currents, arising from perchlorate decomposition, were not detected. In sulphuric acid, a strong interaction between anions and the Ir{111} surface is observed, which precludes oxide formation at potentials less than 1 V (Pd---H), behaviour characteristic of a Pt{111} surface in the same electrolyte. 相似文献
169.
Growth of gold nanorods (AuNRs) by photochemical reduction of HAuCl4 in a micelle solution of hexadecyltrimethylammonium bromide (CTAB) and tetraoctylammonium bromide (TOAB) is studied. The effects of 300 and 254 nm UV light sources and their photon flux on the anisotropic growth of gold nanoparticles are investigated by controlling duration of irradiation and the number of lamps within a photochemical reactor. The resulting AuNRs were characterized by absorption spectroscopy, FTIR, and TEM. Experimental results indicate that a higher density of longer colloidal AuNRs form by increasing the number of incident photons (lamps) at 300 nm while the 254 nm lights produce a lower yield of shorter AuNRs. The yield of AuNRs also depends on the duration of irradiation which was found to be 6.00 h for 300 nm and 5.00 h for 254 nm radiation. Acetone is found to play a major role in the synthesis of AuNRs. Two mechanisms are proposed for the synthesis of Au nanoparticles in the presence and absence of acetone. Irradiation of samples for an excess time produces a lower concentration of AuNRs and a higher yield of spherical particles. This effect is attributed to atom-by-atom dissolution of AuNRs into Au-spherical particles. 相似文献
170.
In this report, we try to show the importance of incorporation of name reactions in the sequential cascade reaction in which significantly decreasing the number of steps towards an ideal and practical multi-step synthesis of natural products as well showing virtually all the advantages already mentioned for “Click Chemistry”. In addition, since the chiral inductions are desired for most of these sequential name reactions, their asymmetric catalyzed reactions were also described. 相似文献