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1.
The preirradiation method of grafting has been established by ultraviolet radiation. Methyl methacrylate (MMA) was grafted onto jute fiber in an aqueous medium. The variation of graft weight with UV‐radiation time, monomer concentration, and reaction time was investigated. The conversion of monomer into homopolymer and graft copolymer was evaluated. The graft weight passes through a maximum value (~ 122%) with UV‐radiation time. The optimum value of the monomer concentration was evaluated for maximum degree of grafting. Graft copolymerization of MMA onto lignocellulose fiber significantly increases the elongation at break (~ 65%) compared to that of the “as‐received” sample. However, a linear decrease on breaking load was observed with the increase of graft weight. The estimation of degree of grafting was achieved using an IR technique by correlating band intensities with the degree of grafting. Considering the water‐absorption property, the grafted sample showed a maximum up to 61% decrease in hydrophilicity compared to that of the as‐received sample. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1667–1675, 2004 相似文献
2.
In this work, a systematic study has been conducted to optimize the process conditions and to evaluate kinetic parameters for hydrodenitrogenation (HDN) and hydrodesulphurization (HDS) of heavy gas oil derived from Athabasca bitumen using NiMo/Al2O3 catalysts containing phosphorus (P). In the catalyst, the concentration of phosphorus was maintained at 2.7 wt%. Experiments were performed in a tickle‐bed reactor at the temperature, pressure and liquid hourly space velocity (LHSV) of 340‐420°C, 6.1‐10.2 MPa and 0.5‐2 h?1, respectively. H2 flow rate and catalyst weight were maintained constant at 50 mL/min and 4 g, respectively in all cases. Statistical analysis of all experimental data was carried out using ANOVA to optimize the process conditions for HDN and HDS reactions. Kinetic studies for HDN and HDS reactions were studied within the temperature range of 340‐400°C using the power law model as well as the Langmuir‐Hinshelhood model. The power law model showed that HDN and HDS of heavy gas oil follow first order kinetics. The activation energies for HDN and HDS reactions from the power law and Langmuir‐Hinshelwood models were 94 and 96 kJ/mol and 113 and 137 kJ/mol, respectively. 相似文献
3.
4.
Rakibul Hasan Sagor Kh. Arif Shahriar Md. Ghulam Saber Md. Mahamudun Arif Joy Ikramul Hasan Sohel 《SILICON》2016,8(2):251-275
A nonlinear optimization algorithm based on the Nelder Mead method is used to characterize the frequency dependent permittivity of 15 materials based on Lorentz, modified Lorentz, Drude and Lorentz-Drude models. The optimized model parameters are used to calculate the complex relative permittivity of each material and compare it with experimental data. In each case, a very good match is found between the optimized and experimental data over a long wavelength range. Comparative study of the models used for each material is performed based on accuracy, wavelength range of applicability and computational efficiency. The parameters presented can be used for computer simulation of electromagnetic wave phenomena involving these materials. 相似文献
5.
Abu Zafar M. Shahriar M. Mostofa Akbar M. Sohel Rahman Muhammad Abdul Hakim Newton 《The Journal of supercomputing》2008,43(3):257-280
This paper presents a multiprocessor based heuristic algorithm for the Multi-dimensional Multiple Choice Knapsack Problem
(MMKP). MMKP is a variant of the classical 0–1 knapsack problem, where items having a value and a number of resource requirements
are divided into groups. Exactly one item has to be picked up from each group to achieve a maximum total value without exceeding
the resource constraint of each type. MMKP has many real world applications including admission control in adaptive multimedia
server system. Exact solution to this problem is NP-Hard, and hence is not feasible for real time applications like admission
control. Therefore, heuristic solutions have been developed to solve the MMKP. M-HEU is one such heuristic, which solves the
MMKP achieving a reasonable percentage of optimality. In this paper, we present a multiprocessor algorithm based on M-HEU,
which runs in O(T/p+s(p)) time, where T is the time required by the algorithm using single processor, p is the number of processors and s(p), a function of p, is the synchronization overhead. We also present the worst-case analysis of our algorithm, the computation of the optimal
number of processors as well as the lower bound of the total value that can be achieved by the heuristic. 相似文献
6.
Mohammad Shahjahan Mondal Jahir Uddin Chowdhury Md. Ruknul Ferdous 《Water Resources Management》2010,24(5):853-869
A risk-based evaluation is performed for meeting future water demands in the Brahmaputra Floodplain Area within Bangladesh
(BFA). This evaluation is carried out using three risk-based performance indicators: reliability, resiliency and vulnerability.
The vulnerability indicator has been redefined incorporating the aspect of a supply failure. The analysis includes the impacts
of climate change on both water demands and resources, and the generation of synthetic flows of the Brahmaputra River using
time series models. The simulated values of the indicators reveal that the expected demand of the BFA up to the year 2050
can be supplied with the proposed Brahmaputra Barrage inside Bangladesh under the ‘no change’ in climatic condition, provided
that the groundwater remains usable. However, if groundwater becomes unusable due to widespread arsenic contamination and/or
a climate change occurs, it would not be possible to meet the future water demand of the region with high reliability, moderate
resiliency and low vulnerability. 相似文献
7.
As companies rushed into E-commerce in the late 1990s, many predicted that existing catalog retailers would have a natural advantage over physical store retailers. However, confusing market signals and incorrect management assumptions led to some poor decisions. This article explores what went wrong with a successful catalog retailer, Fingerhut Inc., as it initially embraced E-commerce in the late 1990s, and some of the lessons learned. 相似文献
8.
Sakib Ferdous Jared L. Dopp Nigel F. Reuel 《American Institute of Chemical Engineers》2021,67(10):e17389
Optimal tip sonication settings, namely tip position, input power, and pulse durations, are necessary for temperature sensitive procedures like preparation of viable cell extract. In this paper, the optimum tip immersion depth (20–30% height below the liquid surface) is estimated which ensures maximum mixing thereby enhancing thermal dissipation of local cavitation hotspots. A finite element (FE) heat transfer model is presented, validated experimentally with (R2 > 97%) and used to observe the effect of temperature rise on cell extract performance of Escherichia coli BL21 DE3 star strain and estimate the temperature threshold. Relative yields in the top 10% are observed for solution temperatures maintained below 32°C; this reduces below 50% relative yield at temperatures above 47°C. A generalized workflow for direct simulation using the CONSOL code as well as master plots for estimation of sonication parameters (power input and pulse settings) is also presented. 相似文献
9.
In this paper, the development of relay-enhanced multi-loop PI controllers is described for multivariable processes. The control system employs a relay in series with the controller. The relay can ensure a satisfactory level of closed-loop performance and it also yields oscillations for tuning of the PI controller based on an equivalent process model for each loop. A simulation example [on a two-inputs-two-outputs (TITO) process] is provided to illustrate the effectiveness of the proposed method and to compare its performance to an existing method. 相似文献
10.
Ferdous Gheyas Sylvia M Blankenship Eric Young Roger McFeeters 《Journal of the science of food and agriculture》1997,75(3):333-340
Fibre composition of the following 13 apple cultivars was studied: ‘Cortland’, ‘Empire’, ‘Fuji’, ‘Golden Delicious’, ‘Gala’, ‘Granny Smith’, ‘Jonagold’, ‘Mutsu’, ‘McIntosh’, ‘Delicious’, ‘Rome’, ‘Stayman’ and ‘York’. Fruit samples from each of these cultivars were analysed for non-starch cell wall materials (NSCWM) and non-starch polysaccharides (NSP). NSCWM was further fractionated into soluble and insoluble fibre fractions. Both NSCWM and NSP content were found to be significantly influenced by cultivar. NSCWM content ranged from 19·1 g kg−1 apple flesh in ‘Fuji’ to 36·2 g kg−1 in ‘York’. Mean(±SD) NSCWM content of all the cultivars was 23·1±4·5 g kg−1. NSP content of apple flesh ranged from 13·8 g kg−1 in ‘McIntosh’ to 28·7 g kg−1 in ‘York’ with the overall mean for all cultivars being 17·9±4·2 g kg−1. Relative amount of monosaccharides found in the hydrolysates of apple fibre also varied among cultivars. The greatest difference was observed in galactose content. ©1997 SCI 相似文献