This study set out to investigate the effect of operational parameters (i.e. ripping depth and operational speed) during a ripping operation on the draft requirement during ripping in a sandy-clay soil. Field experime...This study set out to investigate the effect of operational parameters (i.e. ripping depth and operational speed) during a ripping operation on the draft requirement during ripping in a sandy-clay soil. Field experiments, laboratory tests and numerical modelling techniques were utilised to observe how the draft force varied with changing values of the operational parameters. The discrete element method in the EDEM Academic<sup>TM</sup> software platform was employed to model the soil en-masse to obtain a virtual experimentation platform on which different treatments combing different settings of the operational parameters were investigated. Statistical methods, including ANOVA, regression analysis and the student t-test were applied to establish the significance of the effect of the operational parameters on the draft requirement;statistical analysis revealed that the draft increased linearly with the ripping depth and operating speed suggesting that they are directly proportional. Lower values of the ripping depth and operating speed were found to give the minimum amount of the draft requirement.展开更多
The Rotary Inverted Pendulum(RIP)is a widely used underactuated mechanical system in various applications such as bipedal robots and skyscraper stabilization where attitude control presents a significant challenge.Des...The Rotary Inverted Pendulum(RIP)is a widely used underactuated mechanical system in various applications such as bipedal robots and skyscraper stabilization where attitude control presents a significant challenge.Despite the implementation of various control strategies to maintain equilibrium,optimally tuning control gains to effectively mitigate uncertain nonlinearities in system dynamics remains elusive.Existing methods frequently rely on extensive experimental data or the designer’s expertise,presenting a notable drawback.This paper proposes a novel tracking control approach for RIP,utilizing a Linear Quadratic Regulator(LQR)in combination with a reduced-order observer.Initially,the RIP system is mathematically modeled using the Newton-Euler-Lagrange method.Subsequently,a composite controller is devised that integrates an LQR for generating nominal control signals and a reduced-order observer for reconstructing unmeasured states.This approach enhances the controller’s robustness by eliminating differential terms from the observer,thereby attenuating unknown disturbances.Thorough numerical simulations and experimental evaluations demonstrate the system’s capability to maintain balance below50Hz and achieve precise tracking below1.4 rad,validating the effectiveness of the proposed control scheme.展开更多
Digestive system diseases refer to organic and functional disorders of the digestive system,which are prone to recurrence and frequently accompanied by multiple complications.Necroptosis is a regulated mode of cell de...Digestive system diseases refer to organic and functional disorders of the digestive system,which are prone to recurrence and frequently accompanied by multiple complications.Necroptosis is a regulated mode of cell death mediated by death receptors,dependent on receptor protein activation,and could be specifically inhibited by necrostatin-1.Necroptosis is involved in pathological and physiological processes of various diseases,and plays an important role in the growth and development of organisms and the homeostasis of organ tissues.This paper reviewed the research advancement of necroptosis in digestive system disorders,and discussed the relationship between necroptosis and digestive system diseases,aiming to provide theoretical basis for the cure of these diseases.展开更多
This paper discusses some characteristics of the phenomenon of ripping up the riverbed, which appears in the Yellow River, reviews the previous researches, and develops a formula for predicting scouring intensity.
RIP(RoutingInformationProtocol,路由信息协议)是一种内部网关协议(IGP)[1],用于在较小的网络中传递路由信息,在这些网络中,距离测量使用跳数(即经过的路由器数)。RIP(Routing Information Protocol)路由协议是一种基于距离向量算法的...RIP(RoutingInformationProtocol,路由信息协议)是一种内部网关协议(IGP)[1],用于在较小的网络中传递路由信息,在这些网络中,距离测量使用跳数(即经过的路由器数)。RIP(Routing Information Protocol)路由协议是一种基于距离向量算法的路由协议,在网络中选择最优路径[2]。RIP协议通过发送和接收路由信息来确定最佳路径,它使用距离向量算法,同时每个路由器都维护一个路由表,表中存储从此路由器到其他路由器的距离。该文阐述了RIP协议的防环机制,主要包括水平分割、毒性逆转和触发更新机制。这些机制可使协议更加准确地找到最佳路径,并降低网络环路的产生风险,从而提高协议的性能、可靠性和稳定性。通过分析和比较这些机制,可以更好地了解和利用RIP协议,使其在网络中发挥更加重要的作用。展开更多
The main idea behind the present research is to design a state-feedback controller for an underactuated nonlinear rotary inverted pendulum module by employing the linear quadratic regulator(LQR)technique using local a...The main idea behind the present research is to design a state-feedback controller for an underactuated nonlinear rotary inverted pendulum module by employing the linear quadratic regulator(LQR)technique using local approximation.The LQR is an excellent method for developing a controller for nonlinear systems.It provides optimal feedback to make the closed-loop system robust and stable,rejecting external disturbances.Model-based optimal controller for a nonlinear system such as a rotatory inverted pendulum has not been designed and implemented using Newton-Euler,Lagrange method,and local approximation.Therefore,implementing LQR to an underactuated nonlinear system was vital to design a stable controller.A mathematical model has been developed for the controller design by utilizing the Newton-Euler,Lagrange method.The nonlinear model has been linearized around an equilibrium point.Linear and nonlinear models have been compared to find the range in which linear and nonlinear models’behaviour is similar.MATLAB LQR function and system dynamics have been used to estimate the controller parameters.For the performance evaluation of the designed controller,Simulink has been used.Linear and nonlinear models have been simulated along with the designed controller.Simulations have been performed for the designed controller over the linear and nonlinear system under different conditions through varying system variables.The results show that the system is stable and robust enough to act against external disturbances.The controller maintains the rotary inverted pendulum in an upright position and rejects disruptions like falling under gravitational force or any external disturbance by adjusting the rotation of the horizontal link in both linear and nonlinear environments in a specific range.The controller has been practically designed and implemented.It is vivid from the results that the controller is robust enough to reject the disturbances in milliseconds and keeps the pendulum arm deflection angle to zero degrees.展开更多
Al-Nakheel beach is located northwest of Alexandria city,Egypt,along the Mediterranean coast.During the period from 1998 to 2003,seven detached breakwaters were constructed along Al-Nakheel beach to create a sheltered...Al-Nakheel beach is located northwest of Alexandria city,Egypt,along the Mediterranean coast.During the period from 1998 to 2003,seven detached breakwaters were constructed along Al-Nakheel beach to create a sheltered area for swimming.Unfortunately,the structures amplify rip currents,shoreline accretions,and erosions.The aim of this research is to track the variations of the rip currents within the study area and show the effects of the breakwaters on the shoreline.The research is based on the hydrodynamic and morphological data of the study area and uses the Delft3D hydrodynamical model combined with other data analysis tools to serve the model input.The data include measured sea-level observations in 2013,the ERA-interim wave datasets from 2015 to 2018 and wind data in 2018,bed morphologies,and Google Earth satellite images from 2010 to 2020.The model is calibrated on the basis of the available current measurements within the nearshore zone.Results show that the shoreline eroded at an average rate of about 0.9 m/yr.Moreover,pairs of vortices are formed behind the breakwaters with an average current velocity of 0.6 m/s.The predominant northwest waves induce rip currents on the leeside of the structures with velocities reaching 1.2 m/s,associated with the rip pulsation that extends offshore.The problem solution decision recommends the removal of the sand deposition on the leeside of the breakwaters by an average amount of 100000 m3/yr and the fencing of the safe area for swimming by a floating fence of 1000 m length and 65 m average width.展开更多
文摘This study set out to investigate the effect of operational parameters (i.e. ripping depth and operational speed) during a ripping operation on the draft requirement during ripping in a sandy-clay soil. Field experiments, laboratory tests and numerical modelling techniques were utilised to observe how the draft force varied with changing values of the operational parameters. The discrete element method in the EDEM Academic<sup>TM</sup> software platform was employed to model the soil en-masse to obtain a virtual experimentation platform on which different treatments combing different settings of the operational parameters were investigated. Statistical methods, including ANOVA, regression analysis and the student t-test were applied to establish the significance of the effect of the operational parameters on the draft requirement;statistical analysis revealed that the draft increased linearly with the ripping depth and operating speed suggesting that they are directly proportional. Lower values of the ripping depth and operating speed were found to give the minimum amount of the draft requirement.
基金supported in part by the Youth Foundation of China University of Petroleum-Beijing at Karamay(under Grant No.XQZX20230038)the Karamay Innovative Talents Program(under Grant No.20212022HJCXRC0005).
文摘The Rotary Inverted Pendulum(RIP)is a widely used underactuated mechanical system in various applications such as bipedal robots and skyscraper stabilization where attitude control presents a significant challenge.Despite the implementation of various control strategies to maintain equilibrium,optimally tuning control gains to effectively mitigate uncertain nonlinearities in system dynamics remains elusive.Existing methods frequently rely on extensive experimental data or the designer’s expertise,presenting a notable drawback.This paper proposes a novel tracking control approach for RIP,utilizing a Linear Quadratic Regulator(LQR)in combination with a reduced-order observer.Initially,the RIP system is mathematically modeled using the Newton-Euler-Lagrange method.Subsequently,a composite controller is devised that integrates an LQR for generating nominal control signals and a reduced-order observer for reconstructing unmeasured states.This approach enhances the controller’s robustness by eliminating differential terms from the observer,thereby attenuating unknown disturbances.Thorough numerical simulations and experimental evaluations demonstrate the system’s capability to maintain balance below50Hz and achieve precise tracking below1.4 rad,validating the effectiveness of the proposed control scheme.
基金Supported by Innovation Project of Guangxi Graduate Education(YCSW2023432).
文摘Digestive system diseases refer to organic and functional disorders of the digestive system,which are prone to recurrence and frequently accompanied by multiple complications.Necroptosis is a regulated mode of cell death mediated by death receptors,dependent on receptor protein activation,and could be specifically inhibited by necrostatin-1.Necroptosis is involved in pathological and physiological processes of various diseases,and plays an important role in the growth and development of organisms and the homeostasis of organ tissues.This paper reviewed the research advancement of necroptosis in digestive system disorders,and discussed the relationship between necroptosis and digestive system diseases,aiming to provide theoretical basis for the cure of these diseases.
文摘This paper discusses some characteristics of the phenomenon of ripping up the riverbed, which appears in the Yellow River, reviews the previous researches, and develops a formula for predicting scouring intensity.
文摘RIP(RoutingInformationProtocol,路由信息协议)是一种内部网关协议(IGP)[1],用于在较小的网络中传递路由信息,在这些网络中,距离测量使用跳数(即经过的路由器数)。RIP(Routing Information Protocol)路由协议是一种基于距离向量算法的路由协议,在网络中选择最优路径[2]。RIP协议通过发送和接收路由信息来确定最佳路径,它使用距离向量算法,同时每个路由器都维护一个路由表,表中存储从此路由器到其他路由器的距离。该文阐述了RIP协议的防环机制,主要包括水平分割、毒性逆转和触发更新机制。这些机制可使协议更加准确地找到最佳路径,并降低网络环路的产生风险,从而提高协议的性能、可靠性和稳定性。通过分析和比较这些机制,可以更好地了解和利用RIP协议,使其在网络中发挥更加重要的作用。
文摘The main idea behind the present research is to design a state-feedback controller for an underactuated nonlinear rotary inverted pendulum module by employing the linear quadratic regulator(LQR)technique using local approximation.The LQR is an excellent method for developing a controller for nonlinear systems.It provides optimal feedback to make the closed-loop system robust and stable,rejecting external disturbances.Model-based optimal controller for a nonlinear system such as a rotatory inverted pendulum has not been designed and implemented using Newton-Euler,Lagrange method,and local approximation.Therefore,implementing LQR to an underactuated nonlinear system was vital to design a stable controller.A mathematical model has been developed for the controller design by utilizing the Newton-Euler,Lagrange method.The nonlinear model has been linearized around an equilibrium point.Linear and nonlinear models have been compared to find the range in which linear and nonlinear models’behaviour is similar.MATLAB LQR function and system dynamics have been used to estimate the controller parameters.For the performance evaluation of the designed controller,Simulink has been used.Linear and nonlinear models have been simulated along with the designed controller.Simulations have been performed for the designed controller over the linear and nonlinear system under different conditions through varying system variables.The results show that the system is stable and robust enough to act against external disturbances.The controller maintains the rotary inverted pendulum in an upright position and rejects disruptions like falling under gravitational force or any external disturbance by adjusting the rotation of the horizontal link in both linear and nonlinear environments in a specific range.The controller has been practically designed and implemented.It is vivid from the results that the controller is robust enough to reject the disturbances in milliseconds and keeps the pendulum arm deflection angle to zero degrees.
文摘Al-Nakheel beach is located northwest of Alexandria city,Egypt,along the Mediterranean coast.During the period from 1998 to 2003,seven detached breakwaters were constructed along Al-Nakheel beach to create a sheltered area for swimming.Unfortunately,the structures amplify rip currents,shoreline accretions,and erosions.The aim of this research is to track the variations of the rip currents within the study area and show the effects of the breakwaters on the shoreline.The research is based on the hydrodynamic and morphological data of the study area and uses the Delft3D hydrodynamical model combined with other data analysis tools to serve the model input.The data include measured sea-level observations in 2013,the ERA-interim wave datasets from 2015 to 2018 and wind data in 2018,bed morphologies,and Google Earth satellite images from 2010 to 2020.The model is calibrated on the basis of the available current measurements within the nearshore zone.Results show that the shoreline eroded at an average rate of about 0.9 m/yr.Moreover,pairs of vortices are formed behind the breakwaters with an average current velocity of 0.6 m/s.The predominant northwest waves induce rip currents on the leeside of the structures with velocities reaching 1.2 m/s,associated with the rip pulsation that extends offshore.The problem solution decision recommends the removal of the sand deposition on the leeside of the breakwaters by an average amount of 100000 m3/yr and the fencing of the safe area for swimming by a floating fence of 1000 m length and 65 m average width.
