The purpose of this work is to shed light on the effect of the pivot position on the surface pressure distribution over a 3D wing in different flight conditions.The study is intended to support the design and developm...The purpose of this work is to shed light on the effect of the pivot position on the surface pressure distribution over a 3D wing in different flight conditions.The study is intended to support the design and development of aerospace vehicles where stability analysis,performance optimization,and aircraft design are of primary importance.The following parameters are considered:Mach numbers(M)of 1.3,1.8,2.3,2.8,3.3,and 3.8,angle of incidence(θ)in the range from 5°to 25°,pivot position from h=0.2 to 1.The results of the CFD numerical simulations match available analytical data,thereby providing evidence for the reliability of the used approach.The findings provide valuable insights into the relationship between the surface pressure distribution,the Mach number and the angle of incidence.展开更多
When better fuel-air mixing in the combustion chamber or a reduction in base drag are required in vehicles,rockets,and aeroplanes,the base pressure control is activated.Controlling the base pressure and drag is necess...When better fuel-air mixing in the combustion chamber or a reduction in base drag are required in vehicles,rockets,and aeroplanes,the base pressure control is activated.Controlling the base pressure and drag is necessary in both scenarios.In this work,semi-circular ribs with varying diameters(2,4,and 6 mm)positioned at six distinct positions(0.5D,1D,1.5D,2D,3D,and 4D)inside a square duct with a side of 15 mm are proposed as an efficient way to apply the passive control technique.In-depth research is done on optimising rib size for various rib sites.According to this study,the base pressure rises as rib height increases.Furthermore,the optimal location for the semi-circular ribs with a diameter of 2 mm is at 0.5D.The 1D location appears to be optimal for the 4 mm size as well.For the 6 mm size,however,the 4D position fills this function.展开更多
The work analyzes the basic assumption in Mach’s principle, namely that the inertia of material bodies is determined by their gravitational interaction with distant masses in the universe. However, while Mach’s prin...The work analyzes the basic assumption in Mach’s principle, namely that the inertia of material bodies is determined by their gravitational interaction with distant masses in the universe. However, while Mach’s principle is based on the so-called “long-range gravitational interaction” characterized by an infinitely large propagation velocity, our study is based on a “modified” long-range principle, assuming a very large but finite propagation velocity of the gravitational interaction between local material objects and distant matter. Thus, it is postulated that there are two types of gravitational interaction—short-range gravitational interaction between local objects and long-range gravitational interaction between local objects and distant matter in the universe, which are characterized by different propagation speeds, but with the same gravitational constant. On the basis of the modified long-range principle, a model of distant matter is built in the form of a hollow spherical layer with negligible thickness. The phenomenological assumption is made that the movement with acceleration of the local reference frame (RF) is related to a change in the spherically symmetric distribution of the lines of gravitational interaction of this RF with distant matter, which is expressed in a corresponding asymmetric distribution of the effective mass density on the hollow sphere. A simplified (idealized) model of the effective change of the hollow sphere of distant matter by cutting off separate segments of the sphere is proposed. On the basis of the model, the possibility of representing the inertial effects in three simplest types of reference frames through a corresponding gravitational interaction is considered: 1) inertial RF;2) RF moving in a straight line with constant acceleration;3) RF rotating with constant angular velocity. Expressions were obtained for the gravitational accelerations acting on the test body located inside the hollow sphere with a corresponding change (“cutting”). It is concluded that these accelerations can in a first approximation represent the inertial accelerations of the main types noted above. It is shown that in order to obtain reasonable values of the truncation parameters of the hollow sphere, it is necessary to assume that the gravitational interaction inside this sphere is not of the Newtonian type, i.e. the same depends on the distance not according to the law 1/r2, but according to modified law with a non-integer (fractional) exponent. This law corresponds to a fractal structure of the source of attraction inside the truncated sphere of distant matter. The issue of the possibility of the supposed modified long-range interaction is briefly discussed on the basis of a comparison of the finding a connection with the lines of force of the same with the “cosmic strings” assumed by a number of researchers, along which corresponding excitations (waves, particles) moving at super-light speed. The work advances the idea of the presence of unity and at the same time oppositeness of the inertia of material objects and the known gravitational interaction between them, which are generated by the properties of symmetry of the long-range gravitational interaction. Moreover, while the inertia of the bodies is due to the violation of this symmetry caused by their movement with acceleration, the gravitational interaction between the bodies is due to the aspiration to restore the symmetry of a far-reaching gravitational interaction, which is disturbed by the presence of local material bodies. In the conclusion of the work, the important physico-philosophical significance of Mach’s principle is emphasized, expressed in the understanding that not only the world of microscopic objects (“micro-world”), but also the world of huge cosmic objects (“mega-world”) can have a corresponding impact on our “macroscopic” world.展开更多
Hardware-based sensing frameworks such as cooperative fuel research engines are conventionally used to monitor research octane number (RON) in the petroleum refining industry. Machine learning techniques are employed ...Hardware-based sensing frameworks such as cooperative fuel research engines are conventionally used to monitor research octane number (RON) in the petroleum refining industry. Machine learning techniques are employed to predict the RON of integrated naphtha reforming and isomerisation processes. A dynamic Aspen HYSYS model was used to generate data by introducing artificial uncertainties in the range of ±5% in process conditions, such as temperature, flow rates, etc. The generated data was used to train support vector machines (SVM), Gaussian process regression (GPR), artificial neural networks (ANN), regression trees (RT), and ensemble trees (ET). Hyperparameter tuning was performed to enhance the prediction capabilities of GPR, ANN, SVM, ET and RT models. Performance analysis of the models indicates that GPR, ANN, and SVM with R2 values of 0.99, 0.978, and 0.979 and RMSE values of 0.108, 0.262, and 0.258, respectively performed better than the remaining models and had the prediction capability to capture the RON dependence on predictor variables. ET and RT had an R2 value of 0.94 and 0.89, respectively. The GPR model was used as a surrogate model for fitness function evaluations in two optimisation frameworks based on genetic algorithm and particle swarm method. Optimal parameter values found by the optimisation methodology increased the RON value by 3.52%. The proposed methodology of surrogate-based optimisation will provide a platform for plant-level implementation to realise the concept of industry 4.0 in the refinery.展开更多
文摘The purpose of this work is to shed light on the effect of the pivot position on the surface pressure distribution over a 3D wing in different flight conditions.The study is intended to support the design and development of aerospace vehicles where stability analysis,performance optimization,and aircraft design are of primary importance.The following parameters are considered:Mach numbers(M)of 1.3,1.8,2.3,2.8,3.3,and 3.8,angle of incidence(θ)in the range from 5°to 25°,pivot position from h=0.2 to 1.The results of the CFD numerical simulations match available analytical data,thereby providing evidence for the reliability of the used approach.The findings provide valuable insights into the relationship between the surface pressure distribution,the Mach number and the angle of incidence.
基金supported by the Structures and Materials(S&M)Research Lab of Prince Sultan Universitysupport of Prince Sultan University in paying the article processing charges(APC)for this publication.
文摘When better fuel-air mixing in the combustion chamber or a reduction in base drag are required in vehicles,rockets,and aeroplanes,the base pressure control is activated.Controlling the base pressure and drag is necessary in both scenarios.In this work,semi-circular ribs with varying diameters(2,4,and 6 mm)positioned at six distinct positions(0.5D,1D,1.5D,2D,3D,and 4D)inside a square duct with a side of 15 mm are proposed as an efficient way to apply the passive control technique.In-depth research is done on optimising rib size for various rib sites.According to this study,the base pressure rises as rib height increases.Furthermore,the optimal location for the semi-circular ribs with a diameter of 2 mm is at 0.5D.The 1D location appears to be optimal for the 4 mm size as well.For the 6 mm size,however,the 4D position fills this function.
文摘The work analyzes the basic assumption in Mach’s principle, namely that the inertia of material bodies is determined by their gravitational interaction with distant masses in the universe. However, while Mach’s principle is based on the so-called “long-range gravitational interaction” characterized by an infinitely large propagation velocity, our study is based on a “modified” long-range principle, assuming a very large but finite propagation velocity of the gravitational interaction between local material objects and distant matter. Thus, it is postulated that there are two types of gravitational interaction—short-range gravitational interaction between local objects and long-range gravitational interaction between local objects and distant matter in the universe, which are characterized by different propagation speeds, but with the same gravitational constant. On the basis of the modified long-range principle, a model of distant matter is built in the form of a hollow spherical layer with negligible thickness. The phenomenological assumption is made that the movement with acceleration of the local reference frame (RF) is related to a change in the spherically symmetric distribution of the lines of gravitational interaction of this RF with distant matter, which is expressed in a corresponding asymmetric distribution of the effective mass density on the hollow sphere. A simplified (idealized) model of the effective change of the hollow sphere of distant matter by cutting off separate segments of the sphere is proposed. On the basis of the model, the possibility of representing the inertial effects in three simplest types of reference frames through a corresponding gravitational interaction is considered: 1) inertial RF;2) RF moving in a straight line with constant acceleration;3) RF rotating with constant angular velocity. Expressions were obtained for the gravitational accelerations acting on the test body located inside the hollow sphere with a corresponding change (“cutting”). It is concluded that these accelerations can in a first approximation represent the inertial accelerations of the main types noted above. It is shown that in order to obtain reasonable values of the truncation parameters of the hollow sphere, it is necessary to assume that the gravitational interaction inside this sphere is not of the Newtonian type, i.e. the same depends on the distance not according to the law 1/r2, but according to modified law with a non-integer (fractional) exponent. This law corresponds to a fractal structure of the source of attraction inside the truncated sphere of distant matter. The issue of the possibility of the supposed modified long-range interaction is briefly discussed on the basis of a comparison of the finding a connection with the lines of force of the same with the “cosmic strings” assumed by a number of researchers, along which corresponding excitations (waves, particles) moving at super-light speed. The work advances the idea of the presence of unity and at the same time oppositeness of the inertia of material objects and the known gravitational interaction between them, which are generated by the properties of symmetry of the long-range gravitational interaction. Moreover, while the inertia of the bodies is due to the violation of this symmetry caused by their movement with acceleration, the gravitational interaction between the bodies is due to the aspiration to restore the symmetry of a far-reaching gravitational interaction, which is disturbed by the presence of local material bodies. In the conclusion of the work, the important physico-philosophical significance of Mach’s principle is emphasized, expressed in the understanding that not only the world of microscopic objects (“micro-world”), but also the world of huge cosmic objects (“mega-world”) can have a corresponding impact on our “macroscopic” world.
基金Higher Education Commission(HEC),Pakistan,under the National Research Program for Universities(NRPU)Project No.10,215/Federal.
文摘Hardware-based sensing frameworks such as cooperative fuel research engines are conventionally used to monitor research octane number (RON) in the petroleum refining industry. Machine learning techniques are employed to predict the RON of integrated naphtha reforming and isomerisation processes. A dynamic Aspen HYSYS model was used to generate data by introducing artificial uncertainties in the range of ±5% in process conditions, such as temperature, flow rates, etc. The generated data was used to train support vector machines (SVM), Gaussian process regression (GPR), artificial neural networks (ANN), regression trees (RT), and ensemble trees (ET). Hyperparameter tuning was performed to enhance the prediction capabilities of GPR, ANN, SVM, ET and RT models. Performance analysis of the models indicates that GPR, ANN, and SVM with R2 values of 0.99, 0.978, and 0.979 and RMSE values of 0.108, 0.262, and 0.258, respectively performed better than the remaining models and had the prediction capability to capture the RON dependence on predictor variables. ET and RT had an R2 value of 0.94 and 0.89, respectively. The GPR model was used as a surrogate model for fitness function evaluations in two optimisation frameworks based on genetic algorithm and particle swarm method. Optimal parameter values found by the optimisation methodology increased the RON value by 3.52%. The proposed methodology of surrogate-based optimisation will provide a platform for plant-level implementation to realise the concept of industry 4.0 in the refinery.
