A CFD based numerical simulation of flow velocity of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The resul...A CFD based numerical simulation of flow velocity of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The results show there exist several unsymmetrical envelopes of equal vertical velocities in both upward inner flows and downward outer flows in the hydrocyclone, and the cone angle and apex diameter have remarkable influence on the vertical location of the cone bottom of the envelope of zero vertical velocity. It is also found that the tangential velocity isolines exist in the horizontal planes located in the effective separation region of hydrocyclone. The increase of feed pressure has almost no effect on the distribution characteristics of both vertical velocity and tangential velocity in hydrocyclone, but the magnitude and gradient of tangential velocity are increased obviously to make the motion velocity of high density particles to the wall increased and to make the cyclonic separation effect improved.展开更多
The mixed distribution model is often used to extract information from heteroge-neous data and perform modeling analysis.When the density function of mixed distribution is complicated or the variable dimension is high...The mixed distribution model is often used to extract information from heteroge-neous data and perform modeling analysis.When the density function of mixed distribution is complicated or the variable dimension is high,it usually brings challenges to the parameter es-timation of the mixed distribution model.The application of MM algorithm can avoid complex expectation calculations,and can also solve the problem of high-dimensional optimization by decomposing the objective function.In this paper,MM algorithm is applied to the parameter estimation problem of mixed distribution model.The method of assembly and decomposition is used to construct the substitute function with separable parameters,which avoids the problems of complex expectation calculations and the inversion of high-dimensional matrices.展开更多
Existing discrete element method-based simulation analysis of Panax notoginseng root soil separation still has the challenge to get the accurate and reliable basic parameters,which are necessary for discrete element s...Existing discrete element method-based simulation analysis of Panax notoginseng root soil separation still has the challenge to get the accurate and reliable basic parameters,which are necessary for discrete element simulation.In this paper,the P.notoginseng roots suitable for harvesting period were taken as the experimental object.Then using 3D scanning reverse modeling technology and EDEM software to establish the discrete element model of P.notoginseng,based on which,the physical and virtual tests were carried out to calibrate the simulation parameters.First,the basic physical parameters(density,triaxial geometric size,moisture content,shear modulus,and elastic modulus)and contact coefficients(static friction coefficient,rolling friction coefficient,and crash recovery coefficient between P.notoginseng roots and 65Mn steel)were measured by physical tests.Furthermore,treating the contact coefficients of P.notoginseng roots as the influence factor,the steepest uphill test,and four factors combing five levels of rotational virtual simulation are conducted.The measured relative error accumulation angle and simulation accumulation angle are set as the performance indices.The results show that the static friction coefficient,rolling friction coefficient,crash recovery coefficient,and surface energy coefficient of P.notoginseng roots are 0.55,0.35,0.16,and 19.5 J/m2,respectively.Using calibration results as parameters of the vibration separation simulation test of P.notoginseng soil,the Box-Behnken vibration separation simulation tests were carried out,in which the vibration frequency,inclination angle,and vibration amplitude of separation device as factors,screening rate and damage rate of P.notoginseng soil complex are regarded as indices.The results show that the optimal operating parameters of the separation device are the vibration frequency of 10 Hz,the inclination angle of 5°,and the amplitude of 6 cm.Based on the optimal operation parameters,the discrete element simulation experiment and field experiment of P展开更多
基金Project (50974033) supported by the National Natural Science Foundation of ChinaProject (N100301002) supported by the Fundamental Research Funds for the Universities, China
文摘A CFD based numerical simulation of flow velocity of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The results show there exist several unsymmetrical envelopes of equal vertical velocities in both upward inner flows and downward outer flows in the hydrocyclone, and the cone angle and apex diameter have remarkable influence on the vertical location of the cone bottom of the envelope of zero vertical velocity. It is also found that the tangential velocity isolines exist in the horizontal planes located in the effective separation region of hydrocyclone. The increase of feed pressure has almost no effect on the distribution characteristics of both vertical velocity and tangential velocity in hydrocyclone, but the magnitude and gradient of tangential velocity are increased obviously to make the motion velocity of high density particles to the wall increased and to make the cyclonic separation effect improved.
文摘针对水电站厂房结构模态识别问题,建立了一种密集模态识别的组合方法。该方法通过将逆衰减指数窗和小波包分频结合,实现了降低振动信号的模态密集度,提高了模态分离的精度。振动信号模态分离后采用Random Decrement Technique(RDT)和Spare Time Domain(STD)方法识别水电站厂房结构的模态参数。以一大型地下水电站厂房结构为分析对象,对其原型振动测试数据开展了密集模态识别。结果表明,采用该组合方法识别结果与三维有限元计算结果一致,且识别出的阻尼比也处在合理范围之内。
基金Supported by the National Natural Science Foundation of China(12261108)the General Program of Basic Research Programs of Yunnan Province(202401AT070126)+1 种基金the Yunnan Key Laboratory of Modern Analytical Mathematics and Applications(202302AN360007)the Cross-integration Innovation team of modern Applied Mathematics and Life Sciences in Yunnan Province,China(202405AS350003).
文摘The mixed distribution model is often used to extract information from heteroge-neous data and perform modeling analysis.When the density function of mixed distribution is complicated or the variable dimension is high,it usually brings challenges to the parameter es-timation of the mixed distribution model.The application of MM algorithm can avoid complex expectation calculations,and can also solve the problem of high-dimensional optimization by decomposing the objective function.In this paper,MM algorithm is applied to the parameter estimation problem of mixed distribution model.The method of assembly and decomposition is used to construct the substitute function with separable parameters,which avoids the problems of complex expectation calculations and the inversion of high-dimensional matrices.
基金supported by National Key R&D Program of China(Grant No.2022YFD2002004),Yunnan Fundamental Research Projects(Grant No.202401CF070144)“Xingdian Talent Support Program”Youth Talent Project of Yunnan Province(Grant No.KKXX202423055).
文摘Existing discrete element method-based simulation analysis of Panax notoginseng root soil separation still has the challenge to get the accurate and reliable basic parameters,which are necessary for discrete element simulation.In this paper,the P.notoginseng roots suitable for harvesting period were taken as the experimental object.Then using 3D scanning reverse modeling technology and EDEM software to establish the discrete element model of P.notoginseng,based on which,the physical and virtual tests were carried out to calibrate the simulation parameters.First,the basic physical parameters(density,triaxial geometric size,moisture content,shear modulus,and elastic modulus)and contact coefficients(static friction coefficient,rolling friction coefficient,and crash recovery coefficient between P.notoginseng roots and 65Mn steel)were measured by physical tests.Furthermore,treating the contact coefficients of P.notoginseng roots as the influence factor,the steepest uphill test,and four factors combing five levels of rotational virtual simulation are conducted.The measured relative error accumulation angle and simulation accumulation angle are set as the performance indices.The results show that the static friction coefficient,rolling friction coefficient,crash recovery coefficient,and surface energy coefficient of P.notoginseng roots are 0.55,0.35,0.16,and 19.5 J/m2,respectively.Using calibration results as parameters of the vibration separation simulation test of P.notoginseng soil,the Box-Behnken vibration separation simulation tests were carried out,in which the vibration frequency,inclination angle,and vibration amplitude of separation device as factors,screening rate and damage rate of P.notoginseng soil complex are regarded as indices.The results show that the optimal operating parameters of the separation device are the vibration frequency of 10 Hz,the inclination angle of 5°,and the amplitude of 6 cm.Based on the optimal operation parameters,the discrete element simulation experiment and field experiment of P
