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91.
Chengzhi Chuai Mahmood Iqbal Shixiong Tian 《Journal of Polymer Science.Polymer Physics》2010,48(3):267-275
Graft copolymerization of low‐density polyethylene (LDPE) with a maleic anhydride (MAH) was performed using intermeshing corotating twin‐screw extruder in the presence of benzoyl peroxide (BPO). The LDPE/polyamide 6 (PA6) and LDPE‐g‐MAH/PA6 blends were prepared in a corotating twin‐screw extruder. The melt viscosity of the grafted LDPE was measured by a capillary rheometer. The grafted copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microcopy (SEM). The influence of the variation in temperature, BPO and MAH concentration, and temperature on the grafting degree and on the melt viscosity was studied. The grafting degree increased appreciably up to about 0.45 phr and then decreased continuously with an increasing BPO concentration. According to the FTIR analysis, it was found that the amount of grafted MAH on the LDPE chains was ~5.1%. Thermal analysis showed that melting temperature of the graft copolymers decreases with increasing grafting degree. In addition to this, loss modulus (E″) of the copolymers first increased little with increasing grafting and then obviously decreased with increasing grafting degree. Furthermore, the results revealed that the tensile strength of the blends increased linearly with increasing PA6 content. The results of SEM and mechanical test showed that the blends have good interfacial adhesion and good stability of the phase structure, which is reflected in the mechanical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 267–275, 2010 相似文献
92.
Flow and heat transfer over a permeable sensor surface placed in a squeezing channel is analyzed. A constant transpiration
through the sensor surface is assumed. Locally non-similar momentum and energy equations are solved by three different methods,
against the transpiration parameter τ, for different values of the squeezing parameter b, and Prandtl number Pr. From the investigation, it is found that when the channel being squeezed, the skin-friction reduces but the heat transfer
coefficient increases. Increase in the value of the squeezing parameter onsets reverse flow at the sensor surface when fluid
is being injected and the affect is enhanced with the increase of injection through the surface. It is further observed that
increase of suction of fluid through the sensor thins the thermal and the momentum boundary layer regions, whereas injection
of fluid leads to thickening of both the thermal and the momentum boundary layer regions. Heat transfer from the surface of
the sensor increases with the increase of the value of Pr for the entire range of surface mass-flux parameter τ.
M. A. Hossain is on leave of absence from University of Dhaka. 相似文献
93.
M. F. Mahmood 《Mathematical and Computer Modelling》2002,36(11-13)
Using a variational method, a new model of the nonlinear propagation of optical solitons generated from semiconductor lasers through lossy elliptically low birefringent fiber, is presented within the framework of a system of coupled nonlinear Schroedinger (CNLS) equations with oscillating terms. This analytic model demonstrates polarized soliton oscillations in a lossy elliptically low birefringent optical fiber. 相似文献
94.
Muhammad Bilal Aman-ur- Rehman Shahzad Mahmood Muhammad Ahsan Shahzad Muhammad Sarfraz 《等离子体物理论文集》2023,63(1):e202200102
The dispersion properties and Landau damping rate of ion-acoustic waves (IAWs) with the hybrid Cairns-Tsallis distributed (CTD) electrons and Maxwellian ions are investigated using the plasma kinetic model based on Vlasov-Poisson's equations. For both super-extensive (q < 1) and sub-extensive (q > 1) plasmas, the dielectric response function, real frequency, and Landau damping rate of IAWs are derived. By taking the effect of θi, e (ion-to-electron temperature ratio) into account, it is found that with the increase of ion temperature, the real frequency and wave dispersion effects increase as well (for both super-extensive and sub-extensive cases). Exploring the properties of the Landau damping rate of IAWs with the simultaneous presence of non-thermal parameter α and non-extensive parameter q, a comparison of numerical and analytical results is presented. It is found that in different ranges of θe, i (electron-to-ion temperature ratio), on decreasing the values of the non-extensive parameter and increasing values of the non-thermal parameter, the weak damping rate is observed (vice versa) in super-extensive or super-thermal plasma, although the trend of the damping rate in sub-thermal plasma is similar (as in the case of super-thermal plasma) but is less weak. It is further revealed that the damping rate of IAWs in thermal plasmas (Maxwellian) is stronger than the damping rate of IAWs in the case of non-thermal plasmas (CTD). The current study is applicable to provide deep insight and further allow the exploration of electrostatic plasma modes in different space and laboratory plasma environments where the hybrid CTD plasma exists. 相似文献
95.
Inez Maria Zwetsloot Tahir Mahmood Funmilola Mary Taiwo Zezhong Wang 《商业与工业应用随机模型》2023,39(6):789-817
Early detection of changes in the frequency of events is an important task in many fields, such as disease surveillance, monitoring of high-quality processes, reliability monitoring, and public health. This article focuses on detecting changes in multivariate event data by monitoring the time-between-events (TBE). Existing multivariate TBE charts are limited because they only signal after an event occurred for each of the individual processes. This results in delays (i.e., long time-to-signal), especially when we are interested in detecting a change in one or a few processes with different rates. We propose a bivariate TBE chart, which can signal in real-time. We derive analytical expressions for the control limits and average time-to-signal performance, conduct a performance evaluation and compare our chart to an existing method. Our findings showed that our method is an effective approach for monitoring bivariate TBE data and has better detection ability than the existing method under transient shifts and is more generally applicable. A significant benefit of our method is that it signals in real-time and that the control limits are based on analytical expressions. The proposed method is implemented on two real-life datasets from reliability and health surveillance. 相似文献
96.
This paper proposes a method for simualting symmetric and simulating symmetric and asymmetric typhoonby using Rankine vortex model. Considering similarity between tropical cyclone andthe Rankine vortex,the paper has qualitatively discussed the feasibility of the methods In order to decide quantitatively Rankine vortex’s parameters to simulate typhoon’s structure, the paper has dealt with TCM data.for Yancy Typhoon (9012) as initial fields.. These results are considered as a foundation for further studying typhoon motion by CD approach. 相似文献
97.
A Functionalized Ag2S Molecular Architecture: Facile Assembly of the Atomically Precise Ferrocene‐Decorated Nanocluster [Ag74S19(dppp)6(fc(C{O}OCH2CH2S)2)18]
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Yiyi Liu Bahareh Khalili Najafabadi Mahmood Azizpoor Fard Prof. Dr. John F. Corrigan 《Angewandte Chemie (International ed. in English)》2015,54(16):4832-4835
A ferrocene‐based dithiol 1,1′‐[fc(C{O}OCH2CH2SH)2] has been prepared and treated with a AgI salt to form the stable dithiolate compound [fc(C{O}OCH2CH2SAg)2]n (fc=[Fe(η5‐C5H4)2]). This is used as a reagent for the preparation of the nanocluster [Ag74S19(dppp)6(fc(C{O}OCH2CH2S)2)18] which was obtained in good yield (dppp=1,3‐bis(diphenylphosphino)propane). 相似文献
98.
A facile, effective, and environmentally friendly method has been adopted for the first time to prepare tiny Co3O4 nanocrystals embedded carbon matrices without using surfactants, harmful organic reagents or extreme conditions. Structural characterizations reveal that the size-controlled Co3O4 nanocrystals are uniformly dispersed on carbon matrices. Electrochemical measurements reveal that Co3O4-ordered mesoporous carbon (OMC) can more efficiently catalyze glucose oxidation and acquire better detection parameters compared with those for the Co3O4-macroporous carbon, Co3O4-reduced graphene oxide, and free Co3O4 nanoparticles (NPs) (such as: the large sensitivity (2597.5 μA cm−2 mM−1 between 0 and 0.8 mM and 955.9 μA cm−2 mM−1 between 0.9 and 7.0 mM), fast response time, wide linear range, good stability, and surpassingly selective capability to electroactive molecules or Cl−). Such excellent performances are attributed to the synergistic effect of the following three factors: (1) the high catalytic sites provided by the uniformly dispersed and size-controlled Co3O4 nanocrystals embedded on OMC; (2) the excellent reactant transport efficiency caused by the abundant mesoporous structures of OMC matrix: (3) the improved electron transport in high electron transfer rate (confinement of the Co3O4 NPs in nanoscale spaces ensured intimate contact between Co3O4 nanocrystals and the conducting OMC matrix). The superior catalytic activity and selectivity make Co3O4-OMC very promising for application in direct detection of glucose. 相似文献
99.
Hua-Hua Wang Yi-Yu Jiang Mian HR Mahmood Hai-Yang Liu Herman H.Y. Sung Ian D. Williams Chi K. Chang 《中国化学快报》2015,26(5):529-533
Tetrakis(alloxycarbonyl)porphyrin and its β-octafluoro-substituted derivatives were synthesized via Lindsey method and transformed to their zinc complexes.Single crystal X-ray structures of corresponding Zn(Ⅱ) porphyrins revealed that β-octafluorination will give more compactness of porphyrin moieties in the crystal structure owing to the hydrogen bonding interactions involving β-fluorine atoms.An unusual six-coordinated Zn(Ⅱ) was found via intramolecular coordination of oxygen atom of meso-substituents with central Zn(Ⅱ). 相似文献
100.
Synthesis,Characterization, and Photoluminescence Properties of Silver(I) Metal‐Organic Polymers with Nanochannels Based on 2‐Sulfoterephthalic Acid and Di(pyridin‐2‐yl)amine Ligands
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Hui Huang Mahmood Payehghadr Jie Wang Hong‐Ping Xiao Ai‐Yin Wang Xin‐Hua Li Ali Morsali 《Helvetica chimica acta》2014,97(3):345-354
Two new silver(I) 3D coordination polymers, namely [Ag3(2‐stp)(dpa)]n ( 1 ) and {[Ag2(2‐stp)(H2O)]?Hdpa}n ( 2 ) (2‐NaH2stp=sodium 2,5‐dicarboxysulfonate, dpa=di(pyridine‐2‐yl)amine) were synthesized. The complexes were characterized by elemental analysis, FT‐IR spectra, thermogravimetric analyses (TGA), and single‐crystal X‐ray diffraction. In complex 1 , three neighboring Ag ions are bridged by N‐ and O‐atom, forming a 3D coordination network. The molecular structure of 2 is cation? anion species, forming 3D host? guest supramolecular network with the [Hdpa]+ cations encapsulated in the nanochannels. The photoluminescence properties of the complexes were also investigated in the solid state at room temperature. 相似文献