This paper presents the effect of kenaf fibre orientation on the mechanical properties of kenaf–aramid hybrid composites for military vehicle's spall liner application. It was observed that the tensile strength o...This paper presents the effect of kenaf fibre orientation on the mechanical properties of kenaf–aramid hybrid composites for military vehicle's spall liner application. It was observed that the tensile strength of woven kenaf hybrid composite is almost 20.78% and 43.55% higher than that of UD and mat samples respectively. Charpy impact strength of woven kenaf composites is 19.78% and 52.07% higher than that of UD and mat kenaf hybrid composites respectively. Morphological examinations were carried out using scanning electron microscopy. The results of this study indicate that using kenaf in the form of woven structure could produce a hybrid composite material with high tensile strength and impact resistance properties.展开更多
This study aimed to model the kinetic of hydro-distillation of Aquilaria malaccensis leaves oil in order to understand and optimize the extraction process. In addition, this study, for the first time, aimed to identif...This study aimed to model the kinetic of hydro-distillation of Aquilaria malaccensis leaves oil in order to understand and optimize the extraction process. In addition, this study, for the first time, aimed to identify the chemical compositions of the A. rnalaccensis leave-oil. By assessing both first-order kinetic model and the model of simultaneous washing and diffusion, the result indicated that the model of simultaneous washing and diffusion better describes the hydro-distillation mechanism of the essential oil from A. rnalaccensis leaves. The optimum time, solid to liquid ratio, and the heating power for extracting the highest amount of essential oil were found to be around 3 h, 1：10 （g. ml-1）, and 300 W respectively. Yellow essential oil with a strong smell and a yield of 0.05 v/w was extracted by hydro-distillation Clevenger apparatus. Chemical compounds of the essential oil were analyzed using gas chromatography-mass spectroscopy （GC/MS）, which resulted in identification of 42 compounds that constitute 93% of essential oil. Among the identified components, Pentadecanal （32.082%）, 9-Octadecenal, （Z） （15.894%）, and Tetradecanal （6.927%） were the major compounds. Considering the fact that all the identified major components possess pesticidal properties, A. malaccensis leaves can be regarded as a promising natural source for producing pesticides.展开更多
Experimental quasi-static crushing tests were conducted by using a universal testing machine format kenaf-epoxy composite elliptical cones. The work focused on the vertex angle's effects on energy absorption capab...Experimental quasi-static crushing tests were conducted by using a universal testing machine format kenaf-epoxy composite elliptical cones. The work focused on the vertex angle's effects on energy absorption capability; the vertex angles vary from 0° to 24° in 6 increments. The failure modes of the kenaf fibre epoxy composite elliptical cones were observed utilising delegate photos taken during the quasistatic crushing test. Load-deformation curves and deformation histories of typical specimens are presented and discussed. Moreover, the effects of cone vertex angles on the load carrying capacity and the energy absorption capability are also discussed. The results show that the energy absorption abilities significantly influence the ellipticity vertex angle as the load carrying capacity. We concluded that the quasi-static axial crushing behaviour of elliptical mat laminated composite cones is strongly affected by their structural geometry and the specific energy absorbed by the composite elliptical cones with vertex angles of 6°, 12°, 18°, and 24°, which is more than an elliptical cone with the vertex angle of 0°(the elliptical tube) at any given deformation. However, the specific energy absorption for the elliptical composite cone showed a positive correlation, i.e., the more the angle increased, the more energy was absorbed. In this regard, an elliptical composite cone with a 24° angle exhibited the best energy absorption capability.展开更多
Oxygen evolution reaction(OER)is the key step involved both in water splitting devices and rechargeable metal-air batteries,and hence,there is an urgent need for a stable and low-cost material for efficient OER.In the...Oxygen evolution reaction(OER)is the key step involved both in water splitting devices and rechargeable metal-air batteries,and hence,there is an urgent need for a stable and low-cost material for efficient OER.In the present investigation,Co-Fe-Ga-NiZn(CFGNZ)high entropy alloy(HEA)has been utilized as a low-cost electrocatalyst for OER.Herein,after cyclic voltammetry activation,CFGNZ-nanoparticles(NPs)are covered with oxidized surface and form high entropy(oxy)hydroxides(HEOs),exhibiting a low overpotential of 370 mV to achieve a current density of 10 mA/cm^(2)with a small Tafel slope of 71 mV/dec.CFGNZ alloy has higher electrochemical stability in comparison to state-of-the art RuO2 electrocatalyst as no degradation has been observed up to 10 h of chronoamperometry.Transmission electron microscopy(TEM)studies after 10 h of long-term chronoamperometry test showed no change in the crystal structure,which confirmed the high stability of CFGNZ.The density functional theory(DFT)based calculations show that the closeness of d(p)-band centers to the Fermi level(EF)plays a major role in determining active sites.This work highlights the tremendous potential of CFGNZ HEA for OER,which is the primary reaction involved in water splitting.展开更多
The machining of hard-to-cut materials with a high degree of precision and high surface quality is one of the most critical considerations when fabricating various state-of-the-art engineered components.In this invest...The machining of hard-to-cut materials with a high degree of precision and high surface quality is one of the most critical considerations when fabricating various state-of-the-art engineered components.In this investigation,a comprehensive three-dimensional model was developed and numerically simulated to predict kerf profiles and material removal rates while drilling the aluminum-7075-T6 aerospace alloy.Kerf profile and material removal prediction involved three stages:jet dynamic flow modeling,abrasive particle tracking,and erosion rate pre-diction.Experimental investigations were conducted to validate the developed model.The results indicate that the jet dynamic characteristics and flow of abrasive particles alter the kerf profiles,where the top kerf diameter increases with increasing jet pressure and standoff distance.The kerf depth and hole aspect ratio increase with jet pressure,but decrease with standoff distance and machining time.Crosssectional profiles were characterized by progressive edge rounding and parabolic shapes.Defects can be minimized by utilizing high jet pressure and small standoff distance.The material removal rate increases with increasing jet pressure,abrasive particle size,and exposure time,but decreases with increasing standoff distance.展开更多
据The Art Newspaper报道,伊拉克前总统萨达姆·侯赛因的一处府邸将有可能被改建成为博物馆。早在1926年,大英博物馆就有支援伊拉克建立巴格达博物馆的先例。当时英国将这个支援项目命名为＂格特鲁德·贝尔＂（名称取自英国一...据The Art Newspaper报道,伊拉克前总统萨达姆·侯赛因的一处府邸将有可能被改建成为博物馆。早在1926年,大英博物馆就有支援伊拉克建立巴格达博物馆的先例。当时英国将这个支援项目命名为＂格特鲁德·贝尔＂（名称取自英国一位女考古学家的姓名）,并委派了一些英国考古学家协助项目的进行。展开更多
基金Universiti Putra Malaysia and Science and Technology Research Institute for Defence (STRIDE) for supporting the research activity
文摘This paper presents the effect of kenaf fibre orientation on the mechanical properties of kenaf–aramid hybrid composites for military vehicle's spall liner application. It was observed that the tensile strength of woven kenaf hybrid composite is almost 20.78% and 43.55% higher than that of UD and mat samples respectively. Charpy impact strength of woven kenaf composites is 19.78% and 52.07% higher than that of UD and mat kenaf hybrid composites respectively. Morphological examinations were carried out using scanning electron microscopy. The results of this study indicate that using kenaf in the form of woven structure could produce a hybrid composite material with high tensile strength and impact resistance properties.
文摘This study aimed to model the kinetic of hydro-distillation of Aquilaria malaccensis leaves oil in order to understand and optimize the extraction process. In addition, this study, for the first time, aimed to identify the chemical compositions of the A. rnalaccensis leave-oil. By assessing both first-order kinetic model and the model of simultaneous washing and diffusion, the result indicated that the model of simultaneous washing and diffusion better describes the hydro-distillation mechanism of the essential oil from A. rnalaccensis leaves. The optimum time, solid to liquid ratio, and the heating power for extracting the highest amount of essential oil were found to be around 3 h, 1：10 （g. ml-1）, and 300 W respectively. Yellow essential oil with a strong smell and a yield of 0.05 v/w was extracted by hydro-distillation Clevenger apparatus. Chemical compounds of the essential oil were analyzed using gas chromatography-mass spectroscopy （GC/MS）, which resulted in identification of 42 compounds that constitute 93% of essential oil. Among the identified components, Pentadecanal （32.082%）, 9-Octadecenal, （Z） （15.894%）, and Tetradecanal （6.927%） were the major compounds. Considering the fact that all the identified major components possess pesticidal properties, A. malaccensis leaves can be regarded as a promising natural source for producing pesticides.
基金the Universiti Putra Malaysia for the financial support for this research programme using HiCoE Grant,Ministry of Higher Education,Malaysia
文摘Experimental quasi-static crushing tests were conducted by using a universal testing machine format kenaf-epoxy composite elliptical cones. The work focused on the vertex angle's effects on energy absorption capability; the vertex angles vary from 0° to 24° in 6 increments. The failure modes of the kenaf fibre epoxy composite elliptical cones were observed utilising delegate photos taken during the quasistatic crushing test. Load-deformation curves and deformation histories of typical specimens are presented and discussed. Moreover, the effects of cone vertex angles on the load carrying capacity and the energy absorption capability are also discussed. The results show that the energy absorption abilities significantly influence the ellipticity vertex angle as the load carrying capacity. We concluded that the quasi-static axial crushing behaviour of elliptical mat laminated composite cones is strongly affected by their structural geometry and the specific energy absorbed by the composite elliptical cones with vertex angles of 6°, 12°, 18°, and 24°, which is more than an elliptical cone with the vertex angle of 0°(the elliptical tube) at any given deformation. However, the specific energy absorption for the elliptical composite cone showed a positive correlation, i.e., the more the angle increased, the more energy was absorbed. In this regard, an elliptical composite cone with a 24° angle exhibited the best energy absorption capability.
基金the Institute of Eminence(IoE)MHRD grant of the Indian Institute of Science.N.K.K.acknowledges the Newton Fellowship award from the Royal Society UK(NIF\R1\191571)the core research grant and Ramanujan Fellowship.C.S.T.acknowledges AOARD grant no.FA2386-19-1-4039.
文摘Oxygen evolution reaction(OER)is the key step involved both in water splitting devices and rechargeable metal-air batteries,and hence,there is an urgent need for a stable and low-cost material for efficient OER.In the present investigation,Co-Fe-Ga-NiZn(CFGNZ)high entropy alloy(HEA)has been utilized as a low-cost electrocatalyst for OER.Herein,after cyclic voltammetry activation,CFGNZ-nanoparticles(NPs)are covered with oxidized surface and form high entropy(oxy)hydroxides(HEOs),exhibiting a low overpotential of 370 mV to achieve a current density of 10 mA/cm^(2)with a small Tafel slope of 71 mV/dec.CFGNZ alloy has higher electrochemical stability in comparison to state-of-the art RuO2 electrocatalyst as no degradation has been observed up to 10 h of chronoamperometry.Transmission electron microscopy(TEM)studies after 10 h of long-term chronoamperometry test showed no change in the crystal structure,which confirmed the high stability of CFGNZ.The density functional theory(DFT)based calculations show that the closeness of d(p)-band centers to the Fermi level(EF)plays a major role in determining active sites.This work highlights the tremendous potential of CFGNZ HEA for OER,which is the primary reaction involved in water splitting.
基金supported by the Japan International Cooperation Agency(JICA)in the scope of the Egypt-Japan University of Science and Technology(E-JUST)and special thanks to Alexstone Co.,Ltd.for allowing us to use their machining center for experiments.
文摘The machining of hard-to-cut materials with a high degree of precision and high surface quality is one of the most critical considerations when fabricating various state-of-the-art engineered components.In this investigation,a comprehensive three-dimensional model was developed and numerically simulated to predict kerf profiles and material removal rates while drilling the aluminum-7075-T6 aerospace alloy.Kerf profile and material removal prediction involved three stages:jet dynamic flow modeling,abrasive particle tracking,and erosion rate pre-diction.Experimental investigations were conducted to validate the developed model.The results indicate that the jet dynamic characteristics and flow of abrasive particles alter the kerf profiles,where the top kerf diameter increases with increasing jet pressure and standoff distance.The kerf depth and hole aspect ratio increase with jet pressure,but decrease with standoff distance and machining time.Crosssectional profiles were characterized by progressive edge rounding and parabolic shapes.Defects can be minimized by utilizing high jet pressure and small standoff distance.The material removal rate increases with increasing jet pressure,abrasive particle size,and exposure time,but decreases with increasing standoff distance.
