The problem of high-performance tracking controlfor the lower-triangular systems with unknown sign-switchingvirtual control coefficients as well as unmatched disturbances isinvestigated in this paper.Instead of the on...The problem of high-performance tracking controlfor the lower-triangular systems with unknown sign-switchingvirtual control coefficients as well as unmatched disturbances isinvestigated in this paper.Instead of the online estimation algorithm,the sliding mode method and the Nussbaum gain technique,a group of orientation functions are employed to handlethe unknown sign-switching virtual control coefficients.The controllaw is combined with the orientation functions and the barrierfunctions lumped in a recursive manner.It achieves outputtracking with the preassigned rate,overshoot,and accuracy.Incontrast with the existing solutions,it is effective for the nearlymodel-free case,with the requirement for information of neitherthe system nonlinearities nor their bounding functions of theplant,nor the bounds of the disturbances.In addition,our controllerexhibits significant simplicity,without parameter identification,disturbance estimation,function approximation,derivativecalculation,dynamic surfaces,or command filtering.Twosimulation examples are conducted to substantiate the efficacyand advantages of our approach.展开更多
Although traditional gamma-gamma density(GGD)logging technology is widely utilized,its potential environmental risks have prompted the development of more environmentally friendly neutron-gamma density(NGD)logging tec...Although traditional gamma-gamma density(GGD)logging technology is widely utilized,its potential environmental risks have prompted the development of more environmentally friendly neutron-gamma density(NGD)logging technology.However,NGD measurements are influenced by both neutron and gamma radiations.In the logging environment,variations in the formation composition indicate different elemental compositions,which affect the neutron-gamma reaction cross-sections and gamma generation.Compared to traditional gamma sources such as Cs-137,these changes significantly affect the generation and transport of neutron-induced inelastic gamma rays and hinder accurate measurements.To address this,a novel method is proposed that incorporates the mass attenuation coefficient function to account for the effects of various lithologies and pore contents on gamma-ray attenuation,thereby achieving more accurate density measurements by clarifying the transport processes of inelastic gamma rays with varying energies and spatial distributions in varied logging environments.The proposed method avoids the complex correction of neutron transport and is verified through Monte Carlo simulations for its applicability across various lithologies and pore contents,demonstrating absolute density errors that are less than 0.02 g/cm^(3)in clean formations and indicating good accuracy.This study clarifies the NGD mechanism and provides theoretical guidance for the application of NGD logging methods.Further studies will be conducted on extreme environmental conditions and tool calibration.展开更多
Discharge coefficients of 3-in-1 hole of three inclination angles and three spacing between holes are presented which described the discharge behavior of a row of holes. The inlet and outlet of the 3-in-1 hole both ha...Discharge coefficients of 3-in-1 hole of three inclination angles and three spacing between holes are presented which described the discharge behavior of a row of holes. The inlet and outlet of the 3-in-1 hole both have a 15° lateral expansion. The flow conditions considered are mainstream turbulence intensities and density ratios of secondary flow to mainstream. The momentum flux ratios varied in the range from 1 to 4. The comparison is made of the discharge coefficients of three shaped holes to find an optimal hole with low flow loss. The results show that the discharge coefficients of 3-in- 1 hole are highest in three shaped holes and therefore this article is focused on the measurements of discharge coefficients of 3-in-1 hole for various geometries and aerodynamic parameters. The measured results of 3-in-1 hole indicate that turbulence intensities, density ratios and momentum flux ratios have weak influence on discharge coefficients for inclination angle of 20°. The high turbulence intensity yields the small discharge coefficients for inclination angle of 45° and 90°. The increased both momentum flux ratios and density ratios lead to the increased discharge coefficients for inclination angle of 45° and 90°. The increased inclination angle causes the rapidly increased discharge coefficients. There is a weak dependence of discharge coefficients on hole pitches.展开更多
Tire slip angle has a great influence on peak values of both logitudinal and lateral adhesion coefficients as well as optimal slip ratios. Regression equations based on the experi- mental data from several countries...Tire slip angle has a great influence on peak values of both logitudinal and lateral adhesion coefficients as well as optimal slip ratios. Regression equations based on the experi- mental data from several countries are given to describe their dependencies. The peak value of longitudiinal adhesion coefficient has a linear relationship with tire slip angle, but peak value of lateral has a complicated relationship; the optimal slip ratio of longitudinal has an exponent function relationship, the optimal slip ratio of lateral almost has nothinng to do with tire slipangle.展开更多
Albira SI小动物单光子发射断层显像-X线计算机体层成像仪(SPECT-CT)是单光子放射性药物临床前研究的先进影像工具,其质量控制及检测性能是图像质量和实验数据可靠性的基本保障。为评价Albira SI SPECT-CT设备应用的真实性、可靠性,采...Albira SI小动物单光子发射断层显像-X线计算机体层成像仪(SPECT-CT)是单光子放射性药物临床前研究的先进影像工具,其质量控制及检测性能是图像质量和实验数据可靠性的基本保障。为评价Albira SI SPECT-CT设备应用的真实性、可靠性,采用临床常用单光子核素^(99m)Tc对Albira SI小动物SPECT-CT进行季度性质量控制,同时进行测量结果的线性、稳定性、偏差的检测,并初步尝试小动物骨代谢扫描。结果表明,该设备与放射性活度之间线性关系良好,稳定性强,与常用活度测量设备测量结果差异较小。Albira SI小动物SPECT-CT能够准确反映单光子核素^(99m)Tc的放射性活度分布,小鼠骨代谢显像效果好,适用于临床前放射性药物研究。本研究中建立的系统研究SPECT-CT性能的方法可为类似设备的操作提供方法学依据。展开更多
基金supported in part by the National Natural Science Foundation of China(61991404,62473089)the Research Program of the Liaoning Liaohe Laboratory(LLL23ZZ-05-01)+6 种基金the Key Research and Development Program of Liaoning Province of China(2023JH26/10200011)the 111 Project 2.0 of China(B08015)the National Key Research and Development Program of China(2022YFB3305905)the Xingliao Talent Program of Liaoning Province of China(XLYC2203130)the Natural Science Foundation of Liaoning Province of China(2024JH3/10200012,2023-MS-087)the Open Research Project of the State Key Laboratory of Industrial Control Technology of China(ICT2024B12)the Fundamental Research Funds for the Central Universities of China(N2108003,N2424004).
文摘The problem of high-performance tracking controlfor the lower-triangular systems with unknown sign-switchingvirtual control coefficients as well as unmatched disturbances isinvestigated in this paper.Instead of the online estimation algorithm,the sliding mode method and the Nussbaum gain technique,a group of orientation functions are employed to handlethe unknown sign-switching virtual control coefficients.The controllaw is combined with the orientation functions and the barrierfunctions lumped in a recursive manner.It achieves outputtracking with the preassigned rate,overshoot,and accuracy.Incontrast with the existing solutions,it is effective for the nearlymodel-free case,with the requirement for information of neitherthe system nonlinearities nor their bounding functions of theplant,nor the bounds of the disturbances.In addition,our controllerexhibits significant simplicity,without parameter identification,disturbance estimation,function approximation,derivativecalculation,dynamic surfaces,or command filtering.Twosimulation examples are conducted to substantiate the efficacyand advantages of our approach.
基金supported by the National Natural Science Foundation of China(U23B20151 and 52171253).
文摘Although traditional gamma-gamma density(GGD)logging technology is widely utilized,its potential environmental risks have prompted the development of more environmentally friendly neutron-gamma density(NGD)logging technology.However,NGD measurements are influenced by both neutron and gamma radiations.In the logging environment,variations in the formation composition indicate different elemental compositions,which affect the neutron-gamma reaction cross-sections and gamma generation.Compared to traditional gamma sources such as Cs-137,these changes significantly affect the generation and transport of neutron-induced inelastic gamma rays and hinder accurate measurements.To address this,a novel method is proposed that incorporates the mass attenuation coefficient function to account for the effects of various lithologies and pore contents on gamma-ray attenuation,thereby achieving more accurate density measurements by clarifying the transport processes of inelastic gamma rays with varying energies and spatial distributions in varied logging environments.The proposed method avoids the complex correction of neutron transport and is verified through Monte Carlo simulations for its applicability across various lithologies and pore contents,demonstrating absolute density errors that are less than 0.02 g/cm^(3)in clean formations and indicating good accuracy.This study clarifies the NGD mechanism and provides theoretical guidance for the application of NGD logging methods.Further studies will be conducted on extreme environmental conditions and tool calibration.
文摘Discharge coefficients of 3-in-1 hole of three inclination angles and three spacing between holes are presented which described the discharge behavior of a row of holes. The inlet and outlet of the 3-in-1 hole both have a 15° lateral expansion. The flow conditions considered are mainstream turbulence intensities and density ratios of secondary flow to mainstream. The momentum flux ratios varied in the range from 1 to 4. The comparison is made of the discharge coefficients of three shaped holes to find an optimal hole with low flow loss. The results show that the discharge coefficients of 3-in- 1 hole are highest in three shaped holes and therefore this article is focused on the measurements of discharge coefficients of 3-in-1 hole for various geometries and aerodynamic parameters. The measured results of 3-in-1 hole indicate that turbulence intensities, density ratios and momentum flux ratios have weak influence on discharge coefficients for inclination angle of 20°. The high turbulence intensity yields the small discharge coefficients for inclination angle of 45° and 90°. The increased both momentum flux ratios and density ratios lead to the increased discharge coefficients for inclination angle of 45° and 90°. The increased inclination angle causes the rapidly increased discharge coefficients. There is a weak dependence of discharge coefficients on hole pitches.
文摘Tire slip angle has a great influence on peak values of both logitudinal and lateral adhesion coefficients as well as optimal slip ratios. Regression equations based on the experi- mental data from several countries are given to describe their dependencies. The peak value of longitudiinal adhesion coefficient has a linear relationship with tire slip angle, but peak value of lateral has a complicated relationship; the optimal slip ratio of longitudinal has an exponent function relationship, the optimal slip ratio of lateral almost has nothinng to do with tire slipangle.
