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141.
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Mohd Amin AT-TASNEEM Sallehuddin Mohamed HARIS Zulkifli Mohd NOPIAH 《浙江大学学报(英文版)(C辑:计算机与电子)》2012,13(10)
The problem of finding stabilizing controllers for switched systems is an area of much research interest as conventional concepts from continuous time and discrete event dynamics do not hold true for t... 相似文献
144.
Fischer-Tropsch (FT) reaction involves conversion of syngas (a mixture of carbon monoxide and hydrogen) into higher hydrocarbons in the presence of an active catalyst. The syngas can be derived from non-petroleum feedstocks such as coal, biomass and natural gas, thus the FT reaction provides an alternative route for production of clean fuels. The FT process has received growing interest in recent years due to uncertainty in the Middle East, fast depletion of fossil fuel and environmental concern. This paper reports the synthesis, physicochemical properties and catalytic performance of cobalt-based catalyst in the FT reaction. The catalysts comprised metal nanoparticles supported on carbon nanotubes (CNTs) which were synthesized via a wet impregnation method. The catalysts were characterized using transmission electron microscopy (TEM), temperature-programmed reduction/desorption (TPR/TPD) and X-ray photoelectron spectroscopy (XPS). The performance of the cobalt-based catalyts in a FT reaction was evaluated in a fixed bed microreactor equipped with an on-line gas chromatograph for analyses of hydrocarbon products. The catalysts investigated in this work were Co/CNTs, 70Co30Mn/CNTs, 0.06%K/70Co30Fe/CNTs and 0.04%Nb/70Co30Fe/CNTs. TEM analyses revealed that the average sizes of the metal nanoparticles were 4-5 nm. Based on TPD analyses, the dispersion of these nanoparticles on CNTs were greater than 90%. The presence of both Co2+ and Co3+ ions were confirmed by XPS analysis. The 0.04% Nb/70Co30Fe/CNTs catalyst performed better than other catalysts in the FT reaction where it resulted in CO conversion of 35% and 16% C5+ selectivity at pressure of 1 bar, 220 ~C and H2:CO of 2:1. Using the same catalyst, the CO conversion and C5+ selectivity increased to 60% and 57%, respectively when the pressure was increased to 20 bar. 相似文献
145.
146.
Mohd Basyaruddin Abdul Rahman Noraini Abdul Ghani Nik Ghazali Nik Salleh Mahiran Basri Raja Noor Zaliha Abdul Rahman Abu Bakar Salleh 《Journal of Coatings Technology and Research》2011,8(2):229-236
Of late, UV-curable products are gaining attention in the wood industry because of the effectiveness and efficiency of this
method. UV-curable surface coatings are widely used because of their excellent properties and because they are environmentally
friendly products. In this study, immobilized Candida antarctica lipase B was used to catalyze formation of liquid wax esters, such as adipate esters, via a solvent-free process. The adipate
esters formed were then used as UV-curable reactants in the wood coating formulations, consisting of epoxy acrylate, additives,
and a photoinitiator. The performance of the products was evaluated by coating them onto glass tiles (using gel content, hardness,
and scratch resistance tests) and wood panels (using adhesion, impact, and heat resistance tests). The coated film from this
formulation performed well during the evaluation tests. The gel content exhibited more than 90% polymerization, while the
pendulum hardness gave a value of 55.25%. Both analyses were significant in determining the effect of irradiation cycles.
A scratch test was also carried out to verify the resistance of the coating. The maximum weight load which can be resisted
by the wax esters formulation is 4.5 N. 相似文献
147.
Mohammad Hosseini Fouladi Mohd. Jailani Mohd. Nor Ahmad Kamal Ariffin 《Mechanical Systems and Signal Processing》2009,23(2):489-500
Noise has various effects on comfort, performance and health of human. Sound are analysed by human brain based on the frequencies and amplitudes. In a dynamic system, transmission of sound and vibrations depend on frequency and direction of the input motion and characteristics of the output. It is imperative that automotive manufacturers invest a lot of effort and money to improve and enhance the vibro-acoustics performance of their products. The enhancement effort may be very difficult and time-consuming if one relies only on ‘trial and error’ method without prior knowledge about the sources itself. Complex noise inside a vehicle cabin originated from various sources and travel through many pathways. First stage of sound quality refinement is to find the source. It is vital for automotive engineers to identify the dominant noise sources such as engine noise, exhaust noise and noise due to vibration transmission inside of vehicle. The purpose of this paper is to find the vibro-acoustical sources of noise in a passenger vehicle compartment. The implementation of spectral analysis method is much faster than the ‘trial and error’ methods in which, parts should be separated to measure the transfer functions. Also by using spectral analysis method, signals can be recorded in real operational conditions which conduce to more consistent results. A multi-channel analyser is utilised to measure and record the vibro-acoustical signals. Computational algorithms are also employed to identify contribution of various sources towards the measured interior signal. These achievements can be utilised to detect, control and optimise interior noise performance of road transport vehicles. 相似文献
148.
Ziad Mansour Mohd Raihan Taha Zamri Chik 《Bulletin of Engineering Geology and the Environment》2009,68(1):97-106
Problems have occurred with dykes constructed on the Lisan Marl to retain brine pumped from the Dead Sea, which is chemically
processed to produce potash. In this study the engineering behavior, collapse potential and compressibility of the Lisan Marl
were assessed by undertaking laboratory tests with both natural, distilled water and brine as the media. The results showed
that the liquid limit and fine particles increased when the soil was mixed with fresh/distilled water compared with brine
water. The soil can be classified as highly compressible with a low undrained shear strength. In terms of collapsibility,
the soil could be classified as slightly collapsible upon inundation with distilled water and moderately collapsible when
soaked in Dead Sea brine. The results are important when determining the height and nature of the dykes.
相似文献
149.
Comparison of component method with experimental tests for flush end-plate connections using hot-rolled perwaja steel sections 总被引:1,自引:1,他引:0
A component method has been introduced by Steel Construction Institute to predict the moment resistance of partial strength
connection. The design philosophy is taken directly from Eurocode 3 with strength checks on bolts, welds, and steel which
have been modified to comply with BS 5950-1:2000. The accuracy of the method however needs to be validated with the experimental
tests especially for hot-rolled sections other than typical British Section (BS). Six experimental tests on beam-to-column
connections have been carried out for Flush End-Plate (FEP) connections consisting of variable parameters such as thickness
of end-plate, size and number of bolts, size of columns, and beams. The tests were set-up using local hot-rolled steel sections
known as Perwaja Section (PS) for beams and columns instead of typical British Section (BS). The strength of materials for
end-plate, column and beam sections were tested for tensile strength and used in predicting the moment resistance for component
method. The moment versus rotation of the test results were plotted and compared with the moment resistance derived from component
method. The study concluded that the moment resistance of the tested flush end-plate connections was higher than the predicted
moment resistance from component method which showed good agreement between the two moments. The study also concluded that
the tested FEP connections met the requirements and criteria of partial strength connections. 相似文献
150.
Nilofar Asim Shahidan Radiman Mohd Ambar Yarmo M.S. Banaye Golriz 《Microporous and mesoporous materials》2009,120(3):397-401
Using a surfactant-mediated method (surfactant based on cetyltrimethyl ammonium bromide, CTAB) V2O5 nanorod and nanoparticles have been successfully prepared. Morphologies of V2O5 nanostructures can be controlled by applying different precursors and by varying reaction conditions within the CTAB soft template. With ammonium metavanadate and sulfuric acid as precursors, nanoparticles are synthesized in the size range of 45–160 nm. Precursors of vanadyl sulfate hydrate and sodium hydroxide yield vanadium pentoxide nanorods with diameters of 30–90 nm and lengths of 260–600 nm. The resulting products are characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), variable pressure scanning electron microscopy (VPSEM) and X-ray photoelectron spectroscopy (XPS). Temperature programmed reduction (TPR) is included to test catalytic performance. The results show that V2O5 nanoparticles and nanorods achieve better catalytic performance compared to bulk V2O5, i.e. lower onset temperature, workability at lower temperatures, and higher H2 consumption (μmol/g). 相似文献