The adoption of Internet of Things(IoT)sensing devices is growing rapidly due to their ability to provide realtime services.However,it is constrained by limited data storage and processing power.It offloads its massiv...The adoption of Internet of Things(IoT)sensing devices is growing rapidly due to their ability to provide realtime services.However,it is constrained by limited data storage and processing power.It offloads its massive data stream to edge devices and the cloud for adequate storage and processing.This further leads to the challenges of data outliers,data redundancies,and cloud resource load balancing that would affect the execution and outcome of data streams.This paper presents a review of existing analytics algorithms deployed on IoT-enabled edge cloud infrastructure that resolved the challenges of data outliers,data redundancies,and cloud resource load balancing.The review highlights the problems solved,the results,the weaknesses of the existing algorithms,and the physical and virtual cloud storage servers for resource load balancing.In addition,it discusses the adoption of network protocols that govern the interaction between the three-layer architecture of IoT sensing devices enabled edge cloud and its prevailing challenges.A total of 72 algorithms covering the categories of classification,regression,clustering,deep learning,and optimization have been reviewed.The classification approach has been widely adopted to solve the problem of redundant data,while clustering and optimization approaches are more used for outlier detection and cloud resource allocation.展开更多
Textual data streams have been extensively used in practical applications where consumers of online products have expressed their views regarding online products.Due to changes in data distribution,commonly referred t...Textual data streams have been extensively used in practical applications where consumers of online products have expressed their views regarding online products.Due to changes in data distribution,commonly referred to as concept drift,mining this data stream is a challenging problem for researchers.The majority of the existing drift detection techniques are based on classification errors,which have higher probabilities of false-positive or missed detections.To improve classification accuracy,there is a need to develop more intuitive detection techniques that can identify a great number of drifts in the data streams.This paper presents an adaptive unsupervised learning technique,an ensemble classifier based on drift detection for opinion mining and sentiment classification.To improve classification performance,this approach uses four different dissimilarity measures to determine the degree of concept drifts in the data stream.Whenever a drift is detected,the proposed method builds and adds a new classifier to the ensemble.To add a new classifier,the total number of classifiers in the ensemble is first checked if the limit is exceeded before the classifier with the least weight is removed from the ensemble.To this end,a weighting mechanism is used to calculate the weight of each classifier,which decides the contribution of each classifier in the final classification results.Several experiments were conducted on real-world datasets and the resultswere evaluated on the false positive rate,miss detection rate,and accuracy measures.The proposed method is also compared with the state-of-the-art methods,which include DDM,EDDM,and PageHinkley with support vector machine(SVM)and Naive Bayes classifiers that are frequently used in concept drift detection studies.In all cases,the results show the efficiency of our proposed method.展开更多
The rate determining step and the energy barrier involved in hydrogen adsorption on Pt/WO3- ZrO2 were studied based on the assumption that the hydrogen adsorption occurs only through Pt sites. The rate of hydrogen ads...The rate determining step and the energy barrier involved in hydrogen adsorption on Pt/WO3- ZrO2 were studied based on the assumption that the hydrogen adsorption occurs only through Pt sites. The rate of hydrogen adsorption on Pt/WOa-ZrO2 was measured in the adsorption temperature range of 323-573 K and an initial hydrogen pressure of 50 Torr. The rates of hydrogen uptake were very high for the initial few minutes and the adsorption continued for more than 5 h below 523 K. The hydrogen uptake far exceeded the H/Pt ratio of unity for all adsorption temperatures, indicating that the adsorption of hydrogen involved the dissociative adsorption of hydrogen on Pt sites to form hydrogen atoms, the spillover of hydrogen atoms onto the surface of the WO3-ZrO2 catalyst, the diffusion of spiltover hydrogen atom over the surface of the WO3-ZrO2 catalyst, and the formation of protonic acid site originated from hydrogen atom by releasing an electron in which the electron may react with a second hydrogen atom to form a hydride near the Lewis acid site. The rate determining step was the spillover with the activation energy of 12.3 kJ/mol. The rate of hydrogen adsorption cannot be expressed by the rate equation based on the assumption that the rate determining step is the surface diffusion. The activity of Pt/WO3-ZrO2 was examined on n-heptane isomerization in which the increase of hydrogen partial pressure provided positive-effect on the conversion of n-heptane and negative-effect on the selectivity towards iso-heptane.展开更多
In this study, nanocrystalline Co-Ni-Mg ferrite powders with composition Coo.5Nio.5-xMgxFe2O4 are successfully synthesized by the co-precipitation method. A systematic investigation on the structural, morphological an...In this study, nanocrystalline Co-Ni-Mg ferrite powders with composition Coo.5Nio.5-xMgxFe2O4 are successfully synthesized by the co-precipitation method. A systematic investigation on the structural, morphological and magnetic properties of un-doped and Mg-doped Co-Ni ferrite nanoparticles is carried out. The prepared samples are characterized using x-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometry (VSM). The XRD analyses of the synthesized samples confirm the formation of single-phase cubic spinel structures with crystallite sizes in a range of - 32 nm to - 36 nm. The lat- tice constant increases with increasing Mg content. FESEM images show that the synthesized samples are homogeneous with a uniformly distributed grain. The results of IR spectroscopy analysis indicate the formation of functional groups of spinel ferrite in the co-precipitation process. By increasing Mg2- substitution, room temperature magnetic measurement shows that maximum magnetization and coercivity increase from - 57.35 emu/g to - 61.49 emu/g and - 603.26 Oe to 684.11 Oe (l Oe = 79.5775 A.m-l), respectively. The higher values of magnetization Ms and Mr suggest that the opti- mum composition is Co0.5Ni0.4Mg0.1Fe204 that can be applied to high-density recording media and microwave devices.展开更多
The effect of iridium loading on the properties and catalytic isomerization of n-heptane over Ir-HZSM-5 is studied. Ir-HZSM-5 was prepared by impregnation method and subjected to isomerization process in the presence ...The effect of iridium loading on the properties and catalytic isomerization of n-heptane over Ir-HZSM-5 is studied. Ir-HZSM-5 was prepared by impregnation method and subjected to isomerization process in the presence of flowing hydrogen gas. XRD and BET studies show that the presence of iridium stabilizes the crystalline structure of HZSM-5, leading to more ordered framework structure and larger surface area. TGA and FTIR results substantiate that iridium species interacts with OH group on the surface of HZSM-5. Pyridine FT-IR study verifies the interaction between iridium and surface OH group slightly increased the Bro¨nsted and Lewis acid sites without changing the lattice structure of HZSM-5. The presence of iridium and the increase of strong Lewis acid sites on HZSM-5 were found to bring an increase about 4.1%, 33.2% and 11.8% in conversion, selectivity and yield of n-heptane isomerization, respectively.展开更多
Phenol is considered as pollutant due to its toxicity and carcinogenic effect.Thus,variety of innovative methods for separation and recovery of phenolic compounds is developed in order to remove the unwanted phenol fr...Phenol is considered as pollutant due to its toxicity and carcinogenic effect.Thus,variety of innovative methods for separation and recovery of phenolic compounds is developed in order to remove the unwanted phenol from wastewater and obtain valuable phenolic compound.One of potential method is extraction using green based liquid organic solvent.Therefore,the feasibility of using palm oil was investigated.In this research,palm oil based organic phase was used as diluents to treat a simulated wastewater containing 300×10^(-6) of phenol solution using emulsion liquid membrane process(ELM).The stability of water-in-oil(W/O) emulsion on diluent composition and the parameters affecting the phenol removal efficiency and stability of the emulsion;such as emulsification speed,emulsification time,agitation speed,surfactant concentration,pH of external phase,contact time,stripping agent concentration and treat ratio were carried out.The results of ELM study showed that at ratio7 to 3 of palm oil to kerosene,5 min and 1300 r·min^(-1) of emulsification process the stabile primary emulsion were formed.Also,no carrier is needed to facilitate the phenol extraction.In experimental conditions of500 r·min^(-1) of agitation speed,3%Span 80,pH 8 of external phase,5 min of contact time,0.1 mol·L^(-1) NaOH as stripping agent and 1:10 of treat ratio,the ELM process was very promising for removing the phenol from the wastewater.The extraction performance at about 83%of phenol was removed for simulated wastewater and an enrichment of phenol in recovery phase as phenolate compound was around 11 times.展开更多
The laser induced plasma dynamics of graphite material are investigated by optical emission spectroscopy. Abla- tion and excitation of the graphite material is performed by using an 1064nm Nd:YAG laser in different a...The laser induced plasma dynamics of graphite material are investigated by optical emission spectroscopy. Abla- tion and excitation of the graphite material is performed by using an 1064nm Nd:YAG laser in different ambient pressures. Characteristics of graphite spectra as line intensity variations and signal-to-noise ratio are presented with a main focus on the influence of the ambient pressure on the interaction of laser-induced graphite plasma with an ambient environment. Atomic emission lines are utilized to investigate the dynamical behavior of plasma, such as the excitation temperature and electron density, to describe emission differences under different ambient conditions. The excitation temperature and plasma electron density are the primary factors which contribute to the differences among the atomic carbon emission at different ambient pressures. Reactions between the plasma species and ambient gas, and the total molecular number are the main factors influencing molecular carbon emis- sion. The influence of laser energy on the plasma interaction with environment is also investigated to demonstrate the dynamical behavior of carbon species so that it can be utilized to optimize plasma fluctuations.展开更多
A homologous series of Schiff base esters,4-chlorobenzylidene-4'-n-alkanoyloxyanilines,containing even number of carbons at the end groups of the molecules(C_(n-1)H_(2n-1)COO-,n=4,6,8,10,12,14,16) were synthesized...A homologous series of Schiff base esters,4-chlorobenzylidene-4'-n-alkanoyloxyanilines,containing even number of carbons at the end groups of the molecules(C_(n-1)H_(2n-1)COO-,n=4,6,8,10,12,14,16) were synthesized.The mesomorphic properties were investigated by differential scanning calorimetry(DSC) and polarizing optical microscopy(POM).It was found that the end groups of the molecules had an effect on the mesomorphic properties.n-Butanoyloxy was found non-mesogenic,whilst n-hexanoyloxy exhibited monotropic smectic phase.The higher members in this homologous series were enantiotropic smectogens.展开更多
The effect of sulfate ion (SO4^2-) loading on the properties of Pt/SO4^2-ZrO2 and on the catalytic isomerization of n-butane to/so-butane was studied. The catalyst was prepared by impregnation of Zr(OH)4 with H2SO...The effect of sulfate ion (SO4^2-) loading on the properties of Pt/SO4^2-ZrO2 and on the catalytic isomerization of n-butane to/so-butane was studied. The catalyst was prepared by impregnation of Zr(OH)4 with H2SO4 and platinum solution followed by calcination at 600 ℃. Ammonia TPD and FT-IR were used to confirm the distribution of acid sites and the structure of the sulfate species. Nitrogen physisorption and X-ray diffraction were used to confirm the physical structures of Pt/SO4^2-ZrO2. XRD pattern showed that the presence of sulfate ion stabilized the metastable tetragonal phase of zirconia and hindered the transition of amorphous phase to monoclinic phase of zirconia. Ammonia TPD profiles indicated the distributions of weak and medium acid sites observed on 0.1 N and 1.0 N sulfate in the loaded catalysts. The addition of 2.0 N and 4.0 N sulfate ion generated strong acid site and decreased the weak and medium acid sites. However, the XRD results and the specific surface area of the catalysts indicated that the excessive amount of sulfate ion collapsed the structure of the catalyst. The catalysts showed high activity and stability for isomerization of n-butane to iso-butane at 200 ℃ under hydrogen atmosphere. The conversion of n-butane to iso-butane per specific surface area of the catalyst increased with the increasing amount of sulfate ion owing to the existence of the bidentate sulfate and/or polynucleic sulfate species ((ZrO)2SO2), which acts as an active site for the isomerization.展开更多
In this work, a new photocatalyts In(0.1),Cu(x)-Zn S(x = 0.01, 0.03, 0.05) is successfully synthesized using simple hydrothermal method. The physical and chemical properties of the In and Cu co-doped Zn S photocatalys...In this work, a new photocatalyts In(0.1),Cu(x)-Zn S(x = 0.01, 0.03, 0.05) is successfully synthesized using simple hydrothermal method. The physical and chemical properties of the In and Cu co-doped Zn S photocatalyst were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), diffuse reflectance UV-visible spectroscopy(DR UV-visible) and photoluminescence spectroscopy(PL). The photocatalytic activity of the as-prepared In and Cu co-doped Zn S for hydrogen production from water with Na_2SO_3 and Na_2S as sacrificial agent under visible light irradiation(λ ≥ 425 nm) was investigated. The presence of co-dopants facilitated the separation of electron-hole as well as increases the visible light absorption. The absorption edge of the co-doped Zn S photocatalyst shifted to longer wavelength as the amount of Cu increases. This indicates that the absorption properties depended on the amount of Cu doped. The photocatalytic activity of single doped In(0.1)-Zn S was significantly enhanced by co-doping with Cu under visible light irradiation. The highest photocatalytic activity was observed on In(0.1),Cu(0.03)-Zn S with the hydrogen production rate of 131.32 μmol/h under visible light irradiation.This is almost 8 times higher than single doped In(0.1)-ZnS.展开更多
Carbon dioxide fixation technique was developed as an alternative dechlorination method of chlorobenzenes. Electrolysis of chlorobenzene was carried out in a one-compartment cell fitted with an aluminium anode and a p...Carbon dioxide fixation technique was developed as an alternative dechlorination method of chlorobenzenes. Electrolysis of chlorobenzene was carried out in a one-compartment cell fitted with an aluminium anode and a platinum cathode. Electrolysis in N, N-dimethylformamide (DMF) solution containing 0.1 M of tetrapropylammonium bromide (TPAB) at 0 ℃, 100 ml/min of CO2 flow rate and 120 mA/cm^2 of current density was found to be the optimum conditions of this electrocarboxylation, which gave 72% yield of benzoic acid from chlorobenzene. These conditions were then applied to 1,2-dichlorobenzene and 1,3-dichlorobenzene in order to convert them to their corrcsponding benzoic acids.展开更多
The vibration of the layered cylindrical shells filled with a quiescent, incompressible, and inviscid fluid is analyzed. The governing equations of the cylindrical shells are derived by Love's approximation. The solu...The vibration of the layered cylindrical shells filled with a quiescent, incompressible, and inviscid fluid is analyzed. The governing equations of the cylindrical shells are derived by Love's approximation. The solutions of the displacement functions are assumed in a separable form to obtain a system of coupled differential equations in terms of the displacement functions. The displacement functions are approximated by Bickley-type splines. A generalized eigenvalue problem is obtained and solved numerically for the frequency parameter and an associated eigenvector of the spline coefficients. Two layered shells with three different types of materials under clamped-clamped (C-C) and simply supported (S-S) boundary conditions are considered. The variations of the frequency parameter with respect to the relative layer thickness, the length-to-radius ratio, the length-to-thickness ratio, and the circumferential node number are analyzed.展开更多
Changes in climate factors such as temperature, rainfall, humidity, and wind speed are natural processes that could significantly impact the incidence of infectious diseases. Dengue is a widespread disease that has of...Changes in climate factors such as temperature, rainfall, humidity, and wind speed are natural processes that could significantly impact the incidence of infectious diseases. Dengue is a widespread disease that has often been documented when it comes to the impact of climate change. It has become a significant concern, especially for the Malaysian health authorities, due to its rapid spread and serious effects, leading to loss of life. Several statistical models were performed to identify climatic factors associated with infectious diseases. However, because of the complex and nonlinear interactions between climate variables and disease components, modelling their relationships have become the main challenge in climate-health studies. Hence, this study proposed a Generalized Linear Model (GLM) via Poisson and Negative Binomial to examine the effects of the climate factors on dengue incidence by considering the collinearity between variables. This study focuses on the dengue hot spots in Malaysia for the year 2014. Since there exists collinearity between climate factors, the analysis was done separately using three different models. The study revealed that rainfall, temperature, humidity, and wind speed were statistically significant with dengue incidence, and most of them shown a negative effect. Of all variables, wind speed has the most significant impact on dengue incidence. Having this kind of relationships, policymakers should formulate better plans such that precautionary steps can be taken to reduce the spread of dengue diseases.展开更多
Ni/PtHY with different Ni loadings was prepared by impregnating HY with hexachloroplatinic acid solution and Ni2+/N,N-dimethylformamide solution. An increase in the Ni loading decreased the crystallinity, specific su...Ni/PtHY with different Ni loadings was prepared by impregnating HY with hexachloroplatinic acid solution and Ni2+/N,N-dimethylformamide solution. An increase in the Ni loading decreased the crystallinity, specific surface area and meso-micropores of the catalysts. Ni interacted with hydroxyl groups to produce IR absorption bands at 3740-3500 cm-1, Increasing Ni loadings resulted in a decrease in the intensities of the broad bands at 3730-3500 cm-1 and the sharp band at 3740 cm-1 with simultaneous development of new absorbance band at 3700 cm-1 that was attributed to (-OH)Ni. The acidity of the samples did not significantly change with Ni loadings up to 1.0 wt%, which indicated that Ni mostly interacts with non-acidic silanol groups (terminal- and structural-defect OH groups). The presence of Ni decreased the activity of PtHY toward the isomerization of n-pentane because of a decrease in the number of active protonic-acid sites that formed from molecular hydrogen. IR and ESR studies confirmed that Pt facilitated the formation of protonic-acid sites from molecular hydrogen, whereas Ni, even when combined with Pt, didn't exhibit such ability. The absence of protonic-acid sites from molecular hydrogen significantly decreased the yield of iso-pentane and markedly increased the cracking products.展开更多
We study the symmetries,conservation laws and reduction of third-order equations that evolve from a prior reduction of models that arise in fluid phenomena.These could be the ordinary differential equations (ODEs)that...We study the symmetries,conservation laws and reduction of third-order equations that evolve from a prior reduction of models that arise in fluid phenomena.These could be the ordinary differential equations (ODEs)that are reductions of partial differential equations (PDEs) or,alternatively,PDEs related to given ODEs.In this class,the analysis includes the well-known Blasius,Chazy,and other associated third-order ODEs.展开更多
Zn(1-x)Cux O(x=0.00, 0.01, 0.03, and 0.05) nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacte...Zn(1-x)Cux O(x=0.00, 0.01, 0.03, and 0.05) nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5%(x = 0.05). However, the peak corresponding to CuO for x= 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli(Gram negative bacteria)cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping.展开更多
First,we studied the invariance properties of the Kadomstev–Petviashvili equation with power law nonlinearity.Then,we determined the complete class of conservation laws and stated the corresponding conserved densitie...First,we studied the invariance properties of the Kadomstev–Petviashvili equation with power law nonlinearity.Then,we determined the complete class of conservation laws and stated the corresponding conserved densities which are useful in finding the conserved quantities of the equation.The point symmetry generators were also used to reduce the equation to an exact solution and to verify the invariance properties of the conserved flows.展开更多
Conventionally synthesized silver nanoparticles(AgNP)imposed an alarming effect on the environment and caused toxicity to humans.However,the use of zeolite(zeoY)as a support system could increase its biocompatibility ...Conventionally synthesized silver nanoparticles(AgNP)imposed an alarming effect on the environment and caused toxicity to humans.However,the use of zeolite(zeoY)as a support system could increase its biocompatibility and reduce its toxicity.Hence,green synthesis of AgNP using Persicaria odorata leaves extract supported on zeolite Y has been prepared by an in situ synthesis technique.The phytochemical compounds in the optimized leaf extract concentration of 1%and volume of 0.9 mL reduced the silver ions to AgNP within the zeolite Y pores.Morphological observation revealed the incorporation of AgNP in the zeolite Y(average size:18.51 nm).The release of AgNP exhibited antibacterial activity on C.acnes at a concentration lower than 1 g L^(−1) which is also dependent on the electrolyte.AgNP-zeoY promoted cell proliferation in vitro and it has a non-irritating effect when tested in the in vivo skin irritation model.展开更多
Eu3+ doped borophosphate glasses with the chemical composition 20Li2O-30Al2O3-10B2O3-40P2O5-xEu2O3(where x=0.05 mol.%, 0.1 mol.%, 1.0 mol.%, 1.5 mol.% and 2.0 mol.%) were prepared by conventional melt quenching tec...Eu3+ doped borophosphate glasses with the chemical composition 20Li2O-30Al2O3-10B2O3-40P2O5-xEu2O3(where x=0.05 mol.%, 0.1 mol.%, 1.0 mol.%, 1.5 mol.% and 2.0 mol.%) were prepared by conventional melt quenching technique. The structural and luminescence properties of the prepared Eu3+ doped borophosphate glasses were studied and compared with reported results. The XRD pattern showed the amorphous nature of the prepared glasses. Whereas, the FTIR spectra revealed the vibrational modes in the prepared glasses. The bonding parameters( β and ?) were calculated through the excitation spectra. Judd-Ofelt(J-O) intensity parameters were calculated from the emission spectra and were used to determine transition probability(A), stimulated emission cross-section(σE P), radiative lifetime(τR) and branching ratios(βexp) for the transition 5D0→7Fj(j=1, 2, 3 and 4) of Eu3+ ions. Furthermore, the luminescence intensity ratio(R) of 5D0→7F2 to 5D0→7F1 transition was also calculated. Transition 5D0→7F2 had the highest value of stimulated emission cross-section and branching ratios and the results were comparable with the reported values. This indicated that the present glass is promising host material for Eu3+ doped fiber amplifiers.展开更多
A series of Eu3+ and Dy3+ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3+ and red emission fro...A series of Eu3+ and Dy3+ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3+ and red emission from Eu3+. The f-f transitions in- volving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3+ to Dy3+, which enhanced the emissions of Dy3+. Combinations of the emissions from Eu3+ and Dy3+ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be ad- justable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3+ to Dy3+ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from GaN-based LED chips. This presented the BaB2Si208 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of BaB2Si208 phosphor were also discussed in this study.展开更多
文摘The adoption of Internet of Things(IoT)sensing devices is growing rapidly due to their ability to provide realtime services.However,it is constrained by limited data storage and processing power.It offloads its massive data stream to edge devices and the cloud for adequate storage and processing.This further leads to the challenges of data outliers,data redundancies,and cloud resource load balancing that would affect the execution and outcome of data streams.This paper presents a review of existing analytics algorithms deployed on IoT-enabled edge cloud infrastructure that resolved the challenges of data outliers,data redundancies,and cloud resource load balancing.The review highlights the problems solved,the results,the weaknesses of the existing algorithms,and the physical and virtual cloud storage servers for resource load balancing.In addition,it discusses the adoption of network protocols that govern the interaction between the three-layer architecture of IoT sensing devices enabled edge cloud and its prevailing challenges.A total of 72 algorithms covering the categories of classification,regression,clustering,deep learning,and optimization have been reviewed.The classification approach has been widely adopted to solve the problem of redundant data,while clustering and optimization approaches are more used for outlier detection and cloud resource allocation.
基金The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through Large Groups(Project under Grant Number(RGP.2/49/43)).
文摘Textual data streams have been extensively used in practical applications where consumers of online products have expressed their views regarding online products.Due to changes in data distribution,commonly referred to as concept drift,mining this data stream is a challenging problem for researchers.The majority of the existing drift detection techniques are based on classification errors,which have higher probabilities of false-positive or missed detections.To improve classification accuracy,there is a need to develop more intuitive detection techniques that can identify a great number of drifts in the data streams.This paper presents an adaptive unsupervised learning technique,an ensemble classifier based on drift detection for opinion mining and sentiment classification.To improve classification performance,this approach uses four different dissimilarity measures to determine the degree of concept drifts in the data stream.Whenever a drift is detected,the proposed method builds and adds a new classifier to the ensemble.To add a new classifier,the total number of classifiers in the ensemble is first checked if the limit is exceeded before the classifier with the least weight is removed from the ensemble.To this end,a weighting mechanism is used to calculate the weight of each classifier,which decides the contribution of each classifier in the final classification results.Several experiments were conducted on real-world datasets and the resultswere evaluated on the false positive rate,miss detection rate,and accuracy measures.The proposed method is also compared with the state-of-the-art methods,which include DDM,EDDM,and PageHinkley with support vector machine(SVM)and Naive Bayes classifiers that are frequently used in concept drift detection studies.In all cases,the results show the efficiency of our proposed method.
文摘The rate determining step and the energy barrier involved in hydrogen adsorption on Pt/WO3- ZrO2 were studied based on the assumption that the hydrogen adsorption occurs only through Pt sites. The rate of hydrogen adsorption on Pt/WOa-ZrO2 was measured in the adsorption temperature range of 323-573 K and an initial hydrogen pressure of 50 Torr. The rates of hydrogen uptake were very high for the initial few minutes and the adsorption continued for more than 5 h below 523 K. The hydrogen uptake far exceeded the H/Pt ratio of unity for all adsorption temperatures, indicating that the adsorption of hydrogen involved the dissociative adsorption of hydrogen on Pt sites to form hydrogen atoms, the spillover of hydrogen atoms onto the surface of the WO3-ZrO2 catalyst, the diffusion of spiltover hydrogen atom over the surface of the WO3-ZrO2 catalyst, and the formation of protonic acid site originated from hydrogen atom by releasing an electron in which the electron may react with a second hydrogen atom to form a hydride near the Lewis acid site. The rate determining step was the spillover with the activation energy of 12.3 kJ/mol. The rate of hydrogen adsorption cannot be expressed by the rate equation based on the assumption that the rate determining step is the surface diffusion. The activity of Pt/WO3-ZrO2 was examined on n-heptane isomerization in which the increase of hydrogen partial pressure provided positive-effect on the conversion of n-heptane and negative-effect on the selectivity towards iso-heptane.
基金supported by the Ibnu Sina Institute for Scientific and Industrial Research,Physics Department of Universiti Teknologi Malaysia and the Ministry of Education Malaysia(Grant Nos.Q.J130000.2526.04H65)
文摘In this study, nanocrystalline Co-Ni-Mg ferrite powders with composition Coo.5Nio.5-xMgxFe2O4 are successfully synthesized by the co-precipitation method. A systematic investigation on the structural, morphological and magnetic properties of un-doped and Mg-doped Co-Ni ferrite nanoparticles is carried out. The prepared samples are characterized using x-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometry (VSM). The XRD analyses of the synthesized samples confirm the formation of single-phase cubic spinel structures with crystallite sizes in a range of - 32 nm to - 36 nm. The lat- tice constant increases with increasing Mg content. FESEM images show that the synthesized samples are homogeneous with a uniformly distributed grain. The results of IR spectroscopy analysis indicate the formation of functional groups of spinel ferrite in the co-precipitation process. By increasing Mg2- substitution, room temperature magnetic measurement shows that maximum magnetization and coercivity increase from - 57.35 emu/g to - 61.49 emu/g and - 603.26 Oe to 684.11 Oe (l Oe = 79.5775 A.m-l), respectively. The higher values of magnetization Ms and Mr suggest that the opti- mum composition is Co0.5Ni0.4Mg0.1Fe204 that can be applied to high-density recording media and microwave devices.
基金supported by the Ministry of Science,Technology and Innovation,Malaysia through E-Science Fund Research Project(No.03-01-06-SF0564 and 03-01-06-SF0289)the Hitachi Scholarship Foundation for the Gas Chromatograph Instrument Grant
文摘The effect of iridium loading on the properties and catalytic isomerization of n-heptane over Ir-HZSM-5 is studied. Ir-HZSM-5 was prepared by impregnation method and subjected to isomerization process in the presence of flowing hydrogen gas. XRD and BET studies show that the presence of iridium stabilizes the crystalline structure of HZSM-5, leading to more ordered framework structure and larger surface area. TGA and FTIR results substantiate that iridium species interacts with OH group on the surface of HZSM-5. Pyridine FT-IR study verifies the interaction between iridium and surface OH group slightly increased the Bro¨nsted and Lewis acid sites without changing the lattice structure of HZSM-5. The presence of iridium and the increase of strong Lewis acid sites on HZSM-5 were found to bring an increase about 4.1%, 33.2% and 11.8% in conversion, selectivity and yield of n-heptane isomerization, respectively.
基金Supported by the Ministry of Higher Education(MOHE)Universiti Teknologi Malaysia(RU Research GrantGUP:Q.J130000.2546.12H50)
文摘Phenol is considered as pollutant due to its toxicity and carcinogenic effect.Thus,variety of innovative methods for separation and recovery of phenolic compounds is developed in order to remove the unwanted phenol from wastewater and obtain valuable phenolic compound.One of potential method is extraction using green based liquid organic solvent.Therefore,the feasibility of using palm oil was investigated.In this research,palm oil based organic phase was used as diluents to treat a simulated wastewater containing 300×10^(-6) of phenol solution using emulsion liquid membrane process(ELM).The stability of water-in-oil(W/O) emulsion on diluent composition and the parameters affecting the phenol removal efficiency and stability of the emulsion;such as emulsification speed,emulsification time,agitation speed,surfactant concentration,pH of external phase,contact time,stripping agent concentration and treat ratio were carried out.The results of ELM study showed that at ratio7 to 3 of palm oil to kerosene,5 min and 1300 r·min^(-1) of emulsification process the stabile primary emulsion were formed.Also,no carrier is needed to facilitate the phenol extraction.In experimental conditions of500 r·min^(-1) of agitation speed,3%Span 80,pH 8 of external phase,5 min of contact time,0.1 mol·L^(-1) NaOH as stripping agent and 1:10 of treat ratio,the ELM process was very promising for removing the phenol from the wastewater.The extraction performance at about 83%of phenol was removed for simulated wastewater and an enrichment of phenol in recovery phase as phenolate compound was around 11 times.
基金Supported by the FRGS under Grant No R.J130000.7809.4F519
文摘The laser induced plasma dynamics of graphite material are investigated by optical emission spectroscopy. Abla- tion and excitation of the graphite material is performed by using an 1064nm Nd:YAG laser in different ambient pressures. Characteristics of graphite spectra as line intensity variations and signal-to-noise ratio are presented with a main focus on the influence of the ambient pressure on the interaction of laser-induced graphite plasma with an ambient environment. Atomic emission lines are utilized to investigate the dynamical behavior of plasma, such as the excitation temperature and electron density, to describe emission differences under different ambient conditions. The excitation temperature and plasma electron density are the primary factors which contribute to the differences among the atomic carbon emission at different ambient pressures. Reactions between the plasma species and ambient gas, and the total molecular number are the main factors influencing molecular carbon emis- sion. The influence of laser energy on the plasma interaction with environment is also investigated to demonstrate the dynamical behavior of carbon species so that it can be utilized to optimize plasma fluctuations.
基金Universiti Tunku Abdul Rahman(UTAR) for the financial support through UTAR Vote No.6202/O05the Malaysia Toray Science Foundation(UTAR Vote No.4359/000) for funding this project
文摘A homologous series of Schiff base esters,4-chlorobenzylidene-4'-n-alkanoyloxyanilines,containing even number of carbons at the end groups of the molecules(C_(n-1)H_(2n-1)COO-,n=4,6,8,10,12,14,16) were synthesized.The mesomorphic properties were investigated by differential scanning calorimetry(DSC) and polarizing optical microscopy(POM).It was found that the end groups of the molecules had an effect on the mesomorphic properties.n-Butanoyloxy was found non-mesogenic,whilst n-hexanoyloxy exhibited monotropic smectic phase.The higher members in this homologous series were enantiotropic smectogens.
文摘The effect of sulfate ion (SO4^2-) loading on the properties of Pt/SO4^2-ZrO2 and on the catalytic isomerization of n-butane to/so-butane was studied. The catalyst was prepared by impregnation of Zr(OH)4 with H2SO4 and platinum solution followed by calcination at 600 ℃. Ammonia TPD and FT-IR were used to confirm the distribution of acid sites and the structure of the sulfate species. Nitrogen physisorption and X-ray diffraction were used to confirm the physical structures of Pt/SO4^2-ZrO2. XRD pattern showed that the presence of sulfate ion stabilized the metastable tetragonal phase of zirconia and hindered the transition of amorphous phase to monoclinic phase of zirconia. Ammonia TPD profiles indicated the distributions of weak and medium acid sites observed on 0.1 N and 1.0 N sulfate in the loaded catalysts. The addition of 2.0 N and 4.0 N sulfate ion generated strong acid site and decreased the weak and medium acid sites. However, the XRD results and the specific surface area of the catalysts indicated that the excessive amount of sulfate ion collapsed the structure of the catalyst. The catalysts showed high activity and stability for isomerization of n-butane to iso-butane at 200 ℃ under hydrogen atmosphere. The conversion of n-butane to iso-butane per specific surface area of the catalyst increased with the increasing amount of sulfate ion owing to the existence of the bidentate sulfate and/or polynucleic sulfate species ((ZrO)2SO2), which acts as an active site for the isomerization.
基金Financial support from the Ministry of Science,Technology and Innovation of Malaysia(MOSTI)by the National Science Fellowship(NSF)
文摘In this work, a new photocatalyts In(0.1),Cu(x)-Zn S(x = 0.01, 0.03, 0.05) is successfully synthesized using simple hydrothermal method. The physical and chemical properties of the In and Cu co-doped Zn S photocatalyst were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), diffuse reflectance UV-visible spectroscopy(DR UV-visible) and photoluminescence spectroscopy(PL). The photocatalytic activity of the as-prepared In and Cu co-doped Zn S for hydrogen production from water with Na_2SO_3 and Na_2S as sacrificial agent under visible light irradiation(λ ≥ 425 nm) was investigated. The presence of co-dopants facilitated the separation of electron-hole as well as increases the visible light absorption. The absorption edge of the co-doped Zn S photocatalyst shifted to longer wavelength as the amount of Cu increases. This indicates that the absorption properties depended on the amount of Cu doped. The photocatalytic activity of single doped In(0.1)-Zn S was significantly enhanced by co-doping with Cu under visible light irradiation. The highest photocatalytic activity was observed on In(0.1),Cu(0.03)-Zn S with the hydrogen production rate of 131.32 μmol/h under visible light irradiation.This is almost 8 times higher than single doped In(0.1)-ZnS.
文摘Carbon dioxide fixation technique was developed as an alternative dechlorination method of chlorobenzenes. Electrolysis of chlorobenzene was carried out in a one-compartment cell fitted with an aluminium anode and a platinum cathode. Electrolysis in N, N-dimethylformamide (DMF) solution containing 0.1 M of tetrapropylammonium bromide (TPAB) at 0 ℃, 100 ml/min of CO2 flow rate and 120 mA/cm^2 of current density was found to be the optimum conditions of this electrocarboxylation, which gave 72% yield of benzoic acid from chlorobenzene. These conditions were then applied to 1,2-dichlorobenzene and 1,3-dichlorobenzene in order to convert them to their corrcsponding benzoic acids.
基金supported by the Fundamental Research Grant Scheme of the Ministry of Higher Education,Malaysia(Vote No.4F249)
文摘The vibration of the layered cylindrical shells filled with a quiescent, incompressible, and inviscid fluid is analyzed. The governing equations of the cylindrical shells are derived by Love's approximation. The solutions of the displacement functions are assumed in a separable form to obtain a system of coupled differential equations in terms of the displacement functions. The displacement functions are approximated by Bickley-type splines. A generalized eigenvalue problem is obtained and solved numerically for the frequency parameter and an associated eigenvector of the spline coefficients. Two layered shells with three different types of materials under clamped-clamped (C-C) and simply supported (S-S) boundary conditions are considered. The variations of the frequency parameter with respect to the relative layer thickness, the length-to-radius ratio, the length-to-thickness ratio, and the circumferential node number are analyzed.
文摘Changes in climate factors such as temperature, rainfall, humidity, and wind speed are natural processes that could significantly impact the incidence of infectious diseases. Dengue is a widespread disease that has often been documented when it comes to the impact of climate change. It has become a significant concern, especially for the Malaysian health authorities, due to its rapid spread and serious effects, leading to loss of life. Several statistical models were performed to identify climatic factors associated with infectious diseases. However, because of the complex and nonlinear interactions between climate variables and disease components, modelling their relationships have become the main challenge in climate-health studies. Hence, this study proposed a Generalized Linear Model (GLM) via Poisson and Negative Binomial to examine the effects of the climate factors on dengue incidence by considering the collinearity between variables. This study focuses on the dengue hot spots in Malaysia for the year 2014. Since there exists collinearity between climate factors, the analysis was done separately using three different models. The study revealed that rainfall, temperature, humidity, and wind speed were statistically significant with dengue incidence, and most of them shown a negative effect. Of all variables, wind speed has the most significant impact on dengue incidence. Having this kind of relationships, policymakers should formulate better plans such that precautionary steps can be taken to reduce the spread of dengue diseases.
基金supported by the Ministry of Higher Education, Malaysia through Fundamental Research (Grant Scheme No. 78670)the UTM Short Term Research (Grant No. 77330)
文摘Ni/PtHY with different Ni loadings was prepared by impregnating HY with hexachloroplatinic acid solution and Ni2+/N,N-dimethylformamide solution. An increase in the Ni loading decreased the crystallinity, specific surface area and meso-micropores of the catalysts. Ni interacted with hydroxyl groups to produce IR absorption bands at 3740-3500 cm-1, Increasing Ni loadings resulted in a decrease in the intensities of the broad bands at 3730-3500 cm-1 and the sharp band at 3740 cm-1 with simultaneous development of new absorbance band at 3700 cm-1 that was attributed to (-OH)Ni. The acidity of the samples did not significantly change with Ni loadings up to 1.0 wt%, which indicated that Ni mostly interacts with non-acidic silanol groups (terminal- and structural-defect OH groups). The presence of Ni decreased the activity of PtHY toward the isomerization of n-pentane because of a decrease in the number of active protonic-acid sites that formed from molecular hydrogen. IR and ESR studies confirmed that Pt facilitated the formation of protonic-acid sites from molecular hydrogen, whereas Ni, even when combined with Pt, didn't exhibit such ability. The absence of protonic-acid sites from molecular hydrogen significantly decreased the yield of iso-pentane and markedly increased the cracking products.
文摘We study the symmetries,conservation laws and reduction of third-order equations that evolve from a prior reduction of models that arise in fluid phenomena.These could be the ordinary differential equations (ODEs)that are reductions of partial differential equations (PDEs) or,alternatively,PDEs related to given ODEs.In this class,the analysis includes the well-known Blasius,Chazy,and other associated third-order ODEs.
基金Project supported by the Universiti Teknologi Malaysia(UTM)(Grant No.R.J1300000.7809.4F626)RMC for postdoctoral grants
文摘Zn(1-x)Cux O(x=0.00, 0.01, 0.03, and 0.05) nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5%(x = 0.05). However, the peak corresponding to CuO for x= 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli(Gram negative bacteria)cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping.
文摘First,we studied the invariance properties of the Kadomstev–Petviashvili equation with power law nonlinearity.Then,we determined the complete class of conservation laws and stated the corresponding conserved densities which are useful in finding the conserved quantities of the equation.The point symmetry generators were also used to reduce the equation to an exact solution and to verify the invariance properties of the conserved flows.
基金The authors would like to thank the Malaysia Ministry of Higher Education and Universiti Teknologi Malaysia for financial support under Industry/International Incentive Grant(IIIG)(Vot No 02M61)and Professional Development Research University(Vot No 06E23).
文摘Conventionally synthesized silver nanoparticles(AgNP)imposed an alarming effect on the environment and caused toxicity to humans.However,the use of zeolite(zeoY)as a support system could increase its biocompatibility and reduce its toxicity.Hence,green synthesis of AgNP using Persicaria odorata leaves extract supported on zeolite Y has been prepared by an in situ synthesis technique.The phytochemical compounds in the optimized leaf extract concentration of 1%and volume of 0.9 mL reduced the silver ions to AgNP within the zeolite Y pores.Morphological observation revealed the incorporation of AgNP in the zeolite Y(average size:18.51 nm).The release of AgNP exhibited antibacterial activity on C.acnes at a concentration lower than 1 g L^(−1) which is also dependent on the electrolyte.AgNP-zeoY promoted cell proliferation in vitro and it has a non-irritating effect when tested in the in vivo skin irritation model.
基金Project supported by the Ministry of Higher Education(MOHE),the Ministry of Science,Technology and Innovation(MOSTI)and Universiti Teknologi Malaysia via Research University Grant Project(R.J130000.7826.4F140)Nanofund Grant(J.130000.7926.4H007)
文摘Eu3+ doped borophosphate glasses with the chemical composition 20Li2O-30Al2O3-10B2O3-40P2O5-xEu2O3(where x=0.05 mol.%, 0.1 mol.%, 1.0 mol.%, 1.5 mol.% and 2.0 mol.%) were prepared by conventional melt quenching technique. The structural and luminescence properties of the prepared Eu3+ doped borophosphate glasses were studied and compared with reported results. The XRD pattern showed the amorphous nature of the prepared glasses. Whereas, the FTIR spectra revealed the vibrational modes in the prepared glasses. The bonding parameters( β and ?) were calculated through the excitation spectra. Judd-Ofelt(J-O) intensity parameters were calculated from the emission spectra and were used to determine transition probability(A), stimulated emission cross-section(σE P), radiative lifetime(τR) and branching ratios(βexp) for the transition 5D0→7Fj(j=1, 2, 3 and 4) of Eu3+ ions. Furthermore, the luminescence intensity ratio(R) of 5D0→7F2 to 5D0→7F1 transition was also calculated. Transition 5D0→7F2 had the highest value of stimulated emission cross-section and branching ratios and the results were comparable with the reported values. This indicated that the present glass is promising host material for Eu3+ doped fiber amplifiers.
基金supported by Fundamental Research Grant Scheme of Malaysia(J130000.2526.03H97)the National Natural Science Foundation of China(51372142)
文摘A series of Eu3+ and Dy3+ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3+ and red emission from Eu3+. The f-f transitions in- volving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3+ to Dy3+, which enhanced the emissions of Dy3+. Combinations of the emissions from Eu3+ and Dy3+ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be ad- justable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3+ to Dy3+ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from GaN-based LED chips. This presented the BaB2Si208 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of BaB2Si208 phosphor were also discussed in this study.