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991.
992.
993.
Ahmed A. Bahnasawi Magdi S. Mahmoud Shawki Z. Eid 《Computers & Industrial Engineering》1996,30(4):753-764
A class of manufacturing systems is presented in which the machine interference problem plays an important role in production. We consider a single server (robot) in addition to two types of random machine stoppages with priorities. A detailed analysis has been focused on two measures: robot utilization and machine efficiency. It has been shown that one has to make a compromise between the above two sensitive measures. We have further computed the optimum number of machines that can be served by a robot. A novel optimization technique is used to fulfill this requirement. The simulation results reveal that the number of machines as well as the service rate can be utilized as decision variables in the problem at hand. 相似文献
994.
Ashish Bhattacharjee Mesbahuddin Ahmed Abhijit Mookerjee Amal Halder 《Bulletin of Materials Science》2003,26(1):199-205
We use the self-consistent, augmented space recursion technique to study the electronic structure and magnetic properties
of alloys of the transition metals, Fe, Co and Ni with the noble metals, Ag and Au. We analyse the effect of local environment
and the hybridization between the constituent bands on the electronic and magnetic properties. 相似文献
995.
Hisham Essawy Ahmed Badran Ahmed Youssef Abu El-Fetoh Abd El-Hakim 《Polymer Bulletin》2004,53(1):9-17
Summary Na-montmorillonite (MMT) with cation exchange capacity (CEC) of 90 mEq/100g was converted to MMT-CTAB and MMT-CPC forms by the intercalation of Cetyltrimethylammonium bromide (CTAB) and Cetylpyridinium chloride (CPC), respectively. The intercalation of these surfactants onto the basal space of the montmorillonite was evidenced by fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD). The intercalation of the CPC expanded the basal space from 12.19 Ao to 21.47 Ao while in case of CTAB it was expanded to 19.35 Ao only. The (MMT-CPC) was subsequently used as a host for the preparation of PMMA nanocomposites via intercalative suspension and emulsion polymerization of methylmethacrylate (MMA) using benzoyl peroxide (BPO) and potassium persulphate (PPS) individually and simultaneously. The use of BPO and PPS together invoked better exfoliation but the yield did not change appreciably in comparison with using either of the initiators alone. Different structures were obtained with the variation of the preparation conditions; exfoliated and intercalated nanocomposites which were characterized by XRD, transmission electron microscope (TEM), thermal gravimetric analysis (TGA), and differential scanning calorimeter (DSC). The resultant nanocomposites exhibited improved thermal stability relative to the equivalent macrocomposites. No glass transition temperature (Tg) could be detected for the prepared nanocomposites which was assumed to result from the restricted molecular motion of the polymer chains. 相似文献
996.
Electron beam surface melting of Hastelloy C-276 with the SiC addition is carried out to improve the surface properties. The resulted microstructure and non-equilibrium phases are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive system (EDS). The Hastelloy C-276 is successfully surface-hardened by electron beam melting, the surface hardening effect can be attributed to both microstructure refinement and eutectic phases produced by EB. During EB melting the SiC broke into small pieces and spread in the microstructure increasing the surface hardness by thirteen times. 相似文献
997.
No suitable method for the coloration of unmodified polypropylene using aqueous dye solution has yet been found. Currently, the only viable method is the incorporation of pigments during the extrusion of filaments. In this study, two different commercially available forms of pigment (powder and masterbatch) were incorporated into polypropylene before extruding into filaments to examine their effects on the mechanical behaviour of the filaments. It was found that increasing the pigment content generally reduces tensile strength and Young's modulus in both masterbatch-pigmented filaments and powder-pigmented filaments. However, the extent of reduction is also markedly dependent on the type of pigment incorporated. In addition, elongation to peak is much higher for masterbatch-pigmented filaments than for powder-pigmented filaments. 相似文献
998.
999.
Diagnosis and treatment of malignant pericardial effusion are difficult in clinical practice. This paper reports the feasibility and reliability of percutanous trans-catheter intervention for the diagnosis and treatment of malignant pericardial effusion. Under echocardiagraphic guidence, pericardial puncture was performed and a heamostasis sheath was placed in situ by Seldinger technique. Through the sheath multiple biopsies of the pericardium were taken for pathological examination. A pigtail catheter was inserted to drain off the effusion. According to pathological report suitable anti-cancer drugs were instilled into the pericardial cavity through indwelling catheter for 3-5 days. The catheter was withdrawn when fluid did not re-accumulate. Diagnosis was made in over 96.0% of the cases. Upon follow-up for 3-6 months, complete remission was seen in 96.0% of the treated patients. No significant complication was found in all patients. Percutaneous trans-catheter intervention is a useful approach for the diagnosis and treatment of malignant pericardial effusion. 相似文献
1000.
Thirty-nine Helicobacter pylori (HP) positive chronic duodenal ulcer patients completed the 4 weeks treatment of triple therapy (Denol, Metronidazole and Amoxil). Of these 29 showed healed duodenal ulcer and negative CLO test at 8 weeks (eradication). They were followed at 3,6 and 12 months and at each follow-up, endoscopy and CLO testing were repeated. At 12 weeks, 54% showed a healed ulcer and negative CLO and these figures reached to 69 and 66% at 6 and 12 months respectively. Thirty percent relapsed within 1 year. The present study indicates a prolonged remission of duodenal ulcer following HP eradication. 相似文献