This study investigates the flow and heat transfer of dusty Williamson (MHD) Nanofluid flow over a stretching permeable cylinder in a porous medium. Dusty Williamson Nanofluid was considered due to its thermal propert...This study investigates the flow and heat transfer of dusty Williamson (MHD) Nanofluid flow over a stretching permeable cylinder in a porous medium. Dusty Williamson Nanofluid was considered due to its thermal properties and potential benefits of increasing the heat transfer rate. Firstly, partial differential equations are transformed into coupled non-linear ordinary differential equations through a similarity variables transformation. The resulting set of dimensionless equations is solved analytically by using the Homogony Perturbation Method (HPM). The effects of the emerging parameters on the velocity and temperature profiles as well as skin-friction coefficient and Nusselt number are publicized through tables and graphs with appropriate discussions. The present result has been compared with published papers and found to be in agreement. To the best of author’s knowledge, there has been sparse research work in the literature that considers the effect of dust with Williamson Nanofluid and also solving the problem analytically. Therefore to the best of author’s knowledge, this is the first time analytical solution has been established for the problem. The results revealed that the fluid velocity of both the fluid and dust phases decreases as the Williamson parameter increases. Motivated by the above limitations and the gaps in past works, therefore, it is hoped that the present work will assist in providing accurate solutions to many practical problems in science, industry and engineering.展开更多
This study explores the effects of heat transfer on the Williamson fluid over a porous exponentially stretching surface. The boundary layer equations of the Williamson fluid model for two dimensional flow with heat tr...This study explores the effects of heat transfer on the Williamson fluid over a porous exponentially stretching surface. The boundary layer equations of the Williamson fluid model for two dimensional flow with heat transfer are presented. Two cases of heat transfer are considered, i.e., the prescribed exponential order surface temperature （PEST） case and the prescribed exponential order heat flux （PEHF） case. The highly nonlinear partial differential equations are simplified with suitable similar and non-similar variables, and finally are solved analytically with the help of the optimal homotopy analysis method （OHAM）. The optimal convergence control parameters are obtained, and the physical fea- tures of the flow parameters are analyzed through graphs and tables. The skin friction and wall temperature gradient are calculated.展开更多
The simulation of real contact area between materials is foundationally important for the contact mechanics of mechanical structures. The Greenwood and Williamson(GW) model and the Majumdar(MB) model are the basic mod...The simulation of real contact area between materials is foundationally important for the contact mechanics of mechanical structures. The Greenwood and Williamson(GW) model and the Majumdar(MB) model are the basic models in this field, which are widely accepted and proven to be valid in many experiments and engineering. Although the contact models have evolved considerably in recent years, the verifications of the models are most based on the indirect methods such as electrical conductivity and contact stiffness, because of the lack of effective methods to directly measure the variation of contact surface. In this paper, the total reflection(TR) method is introduced into the verification of contact models.An experiment system based on TR method is constructed to measure the real contact area of two PMMA specimens. The comparison analysis between the results of experiment and models suggests that the experiment result has the same trend with simulation, the MB model has better agreement with the experimental result because this method can take into account the variation of radius and the merging of asperities, while the GW model has a huge deviation because of the dependence on resolution and the lack of considering the variation of radius and asperity's merging process. Taking the interaction of asperities into account could give a better result that is closer to the experiment. Our results and analysis prove that the experimental methods in this paper could be used as a more direct and valid method to quantitatively measure the real contact area and to verify the contact models.展开更多
A convenient synthesis of 1-alkyl-2-chloro-1H-indole-3-carbaldehyde oximes（5a―5d） and 1-alkyl-2-phenoxy-1H-indole-3-carbaldehyde oximes（6a―6d） from 2-indolone was completed via the Vilsmeier-Haack reac-tion,with...A convenient synthesis of 1-alkyl-2-chloro-1H-indole-3-carbaldehyde oximes（5a―5d） and 1-alkyl-2-phenoxy-1H-indole-3-carbaldehyde oximes（6a―6d） from 2-indolone was completed via the Vilsmeier-Haack reac-tion,with N-alkylation and oximation as the key steps.An improved one-pot method for the synthesis of 1-alkyl-2-alkoxy-1H-indole-3-carbaldehyde oximes（7a―7h） from 1-alkyl-2-chloro-1H-indole-3-carbaldehydes（3a―3d） was described.The Williamson reactions and esterification reactions were performed and the oxime-ethers and oxime-esters were synthesized,respectively.The new synthesized compounds（3a―11d） were characterized by 1H NMR,IR,MS,and elemental analysis.展开更多
High-temperature superconductivity in ceramic oxides is a new technology in which advances are occurring at a rapid pace. Here, the author describes some properties of a new nano crystalline ceramic Type II supercondu...High-temperature superconductivity in ceramic oxides is a new technology in which advances are occurring at a rapid pace. Here, the author describes some properties of a new nano crystalline ceramic Type II superconductor, PbSrCaCuO. Type II superconductors are usually made of metal alloys or complex oxide ceramics. The PSCCO perovskite phase structure was prepared by the conventional solid state reaction technique. In order to show the viability of the proposed method, super-conducting powder was prepared in special furnace. The sample was analyzed by X-ray Diffraction (XRD), Particle size determination, SEM and EDX. The comparison of XRD results with JCPDS files confirmed the orthorhombic structure of the sample with a ≠ b ≠ c and α = β = γ = 90°. Scanning electron microscopy (SEM) studies revealed that its particle size is in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX spectrum shows the elements of the sample. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.展开更多
Homogeneous BaTiO3 fine powder has been synthesized at (80°C) by using three different chemical methods using the roots TiCl4, BaCl2 and NaOH or Oxalic acid. The resultant powders were characterized using x-ray d...Homogeneous BaTiO3 fine powder has been synthesized at (80°C) by using three different chemical methods using the roots TiCl4, BaCl2 and NaOH or Oxalic acid. The resultant powders were characterized using x-ray diffraction (XRD) to estimate the crystal structure, lattice parameters and the crystallite size to investigate the favor method in producing BaTiO3 fine powder. The criteria that was dependent on considering the favor method that was given better results of XRD and demand a least time in preparation which tend to consume a lowest energy.展开更多
X-ray crystallography is concerned with discovering and describing the crystal structure. High-temperature superconductivity in ceramic oxides is a new technology in which advances are occurring at a rapid pace. Here,...X-ray crystallography is concerned with discovering and describing the crystal structure. High-temperature superconductivity in ceramic oxides is a new technology in which advances are occurring at a rapid pace. Here, the author describes some properties of a new nano crystalline ceramic type II superconductor, PbBaTiO. Type II superconductors are usually made of metal alloys or complex oxide ceramics. The PBT perovskite phase structure was prepared by the conventional solid state reaction technique. The sample was analyzed by X-ray Diffraction (XRD), Particle size determination, SEM and EDX. The comparison of XRD results with JCPDS files confirmed the tetragonal structure of the sample with a = b ≠ c and α = β = γ = 90°. Scanning electron microscopy (SEM) studies revealed that its particle size was in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX spectrum shows the elements of the sample. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.展开更多
With the discovery of high-TC superconducting materials like Yttrium Barium Cupric Oxide, Bismuth Strontium Calcium Copper Oxide and Thallium Calcium Barium Copper Oxide, tremendous interest has developed over the pas...With the discovery of high-TC superconducting materials like Yttrium Barium Cupric Oxide, Bismuth Strontium Calcium Copper Oxide and Thallium Calcium Barium Copper Oxide, tremendous interest has developed over the past two years in understanding these materials as well as utilizing them in a variety of applications. The thin films of these materials are expected to play an important role in the area of microelectronics, especially for interconnects in integrated circuits, Josephson junctions, magnetic field sensors and optical detectors. Here, the authors designed a new nanocrystalline ceramic type II high-TC superconductor, Gadolinium Barium Copper Oxide (GdBaCuO/GBCO). The GBCO perovskite phase structure was prepared by the conventional solid state thermochemical reaction technique involving mixing, milling, calcination and sintering. In GBCO system, the method for controlling microstructure and superconducting state is related to oxygen content consideration because small changes in oxygen concentration can often?lead to huge change in Tc. In order to show the viability of the proposed method, super-conducting powder was prepared in special furnace. The sample was analyzed by X-Ray Diffraction (XRD), an indispensible non-destructive tool for structural materials characterization and quality control which makes use of the Debye-Scherrer method. The comparison of XRD results with JCPDS files confirmed the orthorhombic structure of the sample. Micro-structural features are studied using Scanning Electron Microscopy (SEM) which revealed that its particle size is in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX plot shows the presence of all the constituents. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.展开更多
The high temperature superconductors are ceramic materials with layers of Copper-oxide spaced by layers containing Barium and other atoms. The Yttrium compound is somewhat unique in that it has a regular crystal struc...The high temperature superconductors are ceramic materials with layers of Copper-oxide spaced by layers containing Barium and other atoms. The Yttrium compound is somewhat unique in that it has a regular crystal structure while the Lanthanum version is classified as a solid solution. The Yttrium compound is often called the 1-2-3 superconductor because of the ratios of its constituents. Lanthanum Zirconium Yttrium Barium Calcium Copper Oxide (LaZrYBaCaCuO) was prepared by the usual solid state reaction method. In order to show the viability of the proposed method, super-conducting powder was prepared in special furnace. The sample was analyzed by X-ray Diffraction (XRD), Particle size determination, SEM and EDX. The comparison of XRD results with JCPDS files confirmed the orthorhombic structure of the sample with a ≠ b ≠ c and α = β = γ = 90°. Scanning Electron Microscopy (SEM) studies revealed that its particle size is in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX spectrum shows the elements of the sample. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.展开更多
文摘This study investigates the flow and heat transfer of dusty Williamson (MHD) Nanofluid flow over a stretching permeable cylinder in a porous medium. Dusty Williamson Nanofluid was considered due to its thermal properties and potential benefits of increasing the heat transfer rate. Firstly, partial differential equations are transformed into coupled non-linear ordinary differential equations through a similarity variables transformation. The resulting set of dimensionless equations is solved analytically by using the Homogony Perturbation Method (HPM). The effects of the emerging parameters on the velocity and temperature profiles as well as skin-friction coefficient and Nusselt number are publicized through tables and graphs with appropriate discussions. The present result has been compared with published papers and found to be in agreement. To the best of author’s knowledge, there has been sparse research work in the literature that considers the effect of dust with Williamson Nanofluid and also solving the problem analytically. Therefore to the best of author’s knowledge, this is the first time analytical solution has been established for the problem. The results revealed that the fluid velocity of both the fluid and dust phases decreases as the Williamson parameter increases. Motivated by the above limitations and the gaps in past works, therefore, it is hoped that the present work will assist in providing accurate solutions to many practical problems in science, industry and engineering.
基金supported by the Ph.D.Indigenous Scheme of the Higher Education Commission of Pakistan(No.112-21674-2PS1-576)
文摘This study explores the effects of heat transfer on the Williamson fluid over a porous exponentially stretching surface. The boundary layer equations of the Williamson fluid model for two dimensional flow with heat transfer are presented. Two cases of heat transfer are considered, i.e., the prescribed exponential order surface temperature （PEST） case and the prescribed exponential order heat flux （PEHF） case. The highly nonlinear partial differential equations are simplified with suitable similar and non-similar variables, and finally are solved analytically with the help of the optimal homotopy analysis method （OHAM）. The optimal convergence control parameters are obtained, and the physical fea- tures of the flow parameters are analyzed through graphs and tables. The skin friction and wall temperature gradient are calculated.
基金Project supported by the National Natural Science Foundation of China(Grant No.11872033)the Beijing Natural Science Foundation,China(Grant No.3172017)
文摘The simulation of real contact area between materials is foundationally important for the contact mechanics of mechanical structures. The Greenwood and Williamson(GW) model and the Majumdar(MB) model are the basic models in this field, which are widely accepted and proven to be valid in many experiments and engineering. Although the contact models have evolved considerably in recent years, the verifications of the models are most based on the indirect methods such as electrical conductivity and contact stiffness, because of the lack of effective methods to directly measure the variation of contact surface. In this paper, the total reflection(TR) method is introduced into the verification of contact models.An experiment system based on TR method is constructed to measure the real contact area of two PMMA specimens. The comparison analysis between the results of experiment and models suggests that the experiment result has the same trend with simulation, the MB model has better agreement with the experimental result because this method can take into account the variation of radius and the merging of asperities, while the GW model has a huge deviation because of the dependence on resolution and the lack of considering the variation of radius and asperity's merging process. Taking the interaction of asperities into account could give a better result that is closer to the experiment. Our results and analysis prove that the experimental methods in this paper could be used as a more direct and valid method to quantitatively measure the real contact area and to verify the contact models.
基金Supported by the Natural Science Foundation of Liaoning Province,China(No.202142037)
文摘A convenient synthesis of 1-alkyl-2-chloro-1H-indole-3-carbaldehyde oximes（5a―5d） and 1-alkyl-2-phenoxy-1H-indole-3-carbaldehyde oximes（6a―6d） from 2-indolone was completed via the Vilsmeier-Haack reac-tion,with N-alkylation and oximation as the key steps.An improved one-pot method for the synthesis of 1-alkyl-2-alkoxy-1H-indole-3-carbaldehyde oximes（7a―7h） from 1-alkyl-2-chloro-1H-indole-3-carbaldehydes（3a―3d） was described.The Williamson reactions and esterification reactions were performed and the oxime-ethers and oxime-esters were synthesized,respectively.The new synthesized compounds（3a―11d） were characterized by 1H NMR,IR,MS,and elemental analysis.
文摘High-temperature superconductivity in ceramic oxides is a new technology in which advances are occurring at a rapid pace. Here, the author describes some properties of a new nano crystalline ceramic Type II superconductor, PbSrCaCuO. Type II superconductors are usually made of metal alloys or complex oxide ceramics. The PSCCO perovskite phase structure was prepared by the conventional solid state reaction technique. In order to show the viability of the proposed method, super-conducting powder was prepared in special furnace. The sample was analyzed by X-ray Diffraction (XRD), Particle size determination, SEM and EDX. The comparison of XRD results with JCPDS files confirmed the orthorhombic structure of the sample with a ≠ b ≠ c and α = β = γ = 90°. Scanning electron microscopy (SEM) studies revealed that its particle size is in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX spectrum shows the elements of the sample. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.
文摘Homogeneous BaTiO3 fine powder has been synthesized at (80°C) by using three different chemical methods using the roots TiCl4, BaCl2 and NaOH or Oxalic acid. The resultant powders were characterized using x-ray diffraction (XRD) to estimate the crystal structure, lattice parameters and the crystallite size to investigate the favor method in producing BaTiO3 fine powder. The criteria that was dependent on considering the favor method that was given better results of XRD and demand a least time in preparation which tend to consume a lowest energy.
文摘X-ray crystallography is concerned with discovering and describing the crystal structure. High-temperature superconductivity in ceramic oxides is a new technology in which advances are occurring at a rapid pace. Here, the author describes some properties of a new nano crystalline ceramic type II superconductor, PbBaTiO. Type II superconductors are usually made of metal alloys or complex oxide ceramics. The PBT perovskite phase structure was prepared by the conventional solid state reaction technique. The sample was analyzed by X-ray Diffraction (XRD), Particle size determination, SEM and EDX. The comparison of XRD results with JCPDS files confirmed the tetragonal structure of the sample with a = b ≠ c and α = β = γ = 90°. Scanning electron microscopy (SEM) studies revealed that its particle size was in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX spectrum shows the elements of the sample. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.
文摘With the discovery of high-TC superconducting materials like Yttrium Barium Cupric Oxide, Bismuth Strontium Calcium Copper Oxide and Thallium Calcium Barium Copper Oxide, tremendous interest has developed over the past two years in understanding these materials as well as utilizing them in a variety of applications. The thin films of these materials are expected to play an important role in the area of microelectronics, especially for interconnects in integrated circuits, Josephson junctions, magnetic field sensors and optical detectors. Here, the authors designed a new nanocrystalline ceramic type II high-TC superconductor, Gadolinium Barium Copper Oxide (GdBaCuO/GBCO). The GBCO perovskite phase structure was prepared by the conventional solid state thermochemical reaction technique involving mixing, milling, calcination and sintering. In GBCO system, the method for controlling microstructure and superconducting state is related to oxygen content consideration because small changes in oxygen concentration can often?lead to huge change in Tc. In order to show the viability of the proposed method, super-conducting powder was prepared in special furnace. The sample was analyzed by X-Ray Diffraction (XRD), an indispensible non-destructive tool for structural materials characterization and quality control which makes use of the Debye-Scherrer method. The comparison of XRD results with JCPDS files confirmed the orthorhombic structure of the sample. Micro-structural features are studied using Scanning Electron Microscopy (SEM) which revealed that its particle size is in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX plot shows the presence of all the constituents. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.
文摘The high temperature superconductors are ceramic materials with layers of Copper-oxide spaced by layers containing Barium and other atoms. The Yttrium compound is somewhat unique in that it has a regular crystal structure while the Lanthanum version is classified as a solid solution. The Yttrium compound is often called the 1-2-3 superconductor because of the ratios of its constituents. Lanthanum Zirconium Yttrium Barium Calcium Copper Oxide (LaZrYBaCaCuO) was prepared by the usual solid state reaction method. In order to show the viability of the proposed method, super-conducting powder was prepared in special furnace. The sample was analyzed by X-ray Diffraction (XRD), Particle size determination, SEM and EDX. The comparison of XRD results with JCPDS files confirmed the orthorhombic structure of the sample with a ≠ b ≠ c and α = β = γ = 90°. Scanning Electron Microscopy (SEM) studies revealed that its particle size is in the nanometer range. It also confirmed the calculated value of particle size from Debye Scherrer’s formula. EDX spectrum shows the elements of the sample. X-ray instrumental peak broadening analysis was used to evaluate the size and lattice strain by the Williamson-Hall Plot method.
