A growing body of studies and systematic reviews show evidence of the beneficial effects of physical exercise on core symptoms of ADHD. Furthermore, studies indicate that physical exercise as an adjuvant can enhance t...A growing body of studies and systematic reviews show evidence of the beneficial effects of physical exercise on core symptoms of ADHD. Furthermore, studies indicate that physical exercise as an adjuvant can enhance the effects of medication in the treatment of ADHD. Aerobic and coordinative exercises improve executive functioning through their effect on neurocognitive domains that are implicated in ADHD. It is postulated that through their specific modus operandi, aerobic exercise, by raising cortical arousal levels, improves impaired alerting functions whereas coordinative exercises improve the regulation of inhibitory control through the involvement of a higher variety of frontal-dependent cognitive processes. The increasing use of routine neurocognitive testing with continuous performance tests (CPT), such as the QbTest, at clinical assessments for ADHD allows for an innovative approach to identify the assessment impairments in alerting function and inhibition control that are related to ADHD and accordingly choose aerobic or coordinative physical exercise in a more targeted fashion.展开更多
Turbulent flow, the transpor＇t of inclusions and bubbles, and inclusion removal by fluid flow, transport and by bubble flotation in the strand of the continuous slab caster are investigated using computational models...Turbulent flow, the transpor＇t of inclusions and bubbles, and inclusion removal by fluid flow, transport and by bubble flotation in the strand of the continuous slab caster are investigated using computational models, and validated through comparison with plant measurements of inclusions. Steady 3-D flow of steel in the liquid pool in the mold and upper strand is simulated with a finitedifference computational model using the standard k-εturbulence rondel. Trajectories of inclusions and bubhles tire calculated by integrating each local velocity, considering its drag and buoyancy forces, A ＂random walk＂ model is used to incorporate the effect of turbulent fluctuations on the particle motion. The attachment probability of inclusions on a bubble surface is investigated based on fundamental fluid flow simulations, incorporating the turbulent inclusion trajectory and sliding time of each individual inclusion along the bubble surface as a function of particle and bubble size. The chunge in inclusion distribution due to removal by bubble transport in the mold is calculated based on the computed attachment probability of inclusions on each bubble and the computed path length of the bubbles. The results indicate that 6%-10% inclusions are removed by fluid flow transport. 10% by bubble flotation, and 4% by entrapment to the submerged entry nozzle （SEN） walls. Smaller bubbles and larger inclusions have larger attachment probabilities. Smaller bubbles are more efficient for inclusion removal by bubble flotation, so Inng as they are not entrapped in the solidifying shell A larger gas flow rate favors inclusion removal by bubble flotation. The optimum bubble size should be 2-4mm.展开更多
This study explores the quasi-real time inversion principle and precision estimation of three-dimensional coordinates of the epicenter, trigger time and magnitude of earthquakes with the aim to improve traditional met...This study explores the quasi-real time inversion principle and precision estimation of three-dimensional coordinates of the epicenter, trigger time and magnitude of earthquakes with the aim to improve traditional methods, which are flawed due to missing information or distortion in the seismograph records. The epicenter, trigger time and magnitude from the Lushan earthquake are inverted and analyzed based on high-frequency GNSS data. The inversion results achieved a high precision, which are consistent with the data published by the China Earthquake Administration. Moreover, it has been proven that the inversion method has good theoretical value and excellent application prospects.展开更多
An algorithm is presented to analyze the free vibration in a system composed of a cable with discrete elements, e.g., a concentrated mass, a translational spring, and a harmonic oscillator. The vibrations in the cable...An algorithm is presented to analyze the free vibration in a system composed of a cable with discrete elements, e.g., a concentrated mass, a translational spring, and a harmonic oscillator. The vibrations in the cable are modeled and analyzed with the Lagrange multiplier formalism. Some fragments of the investigated structure are modeled with continuously distributed parameters, while the other fragments of the structure are modeled with discrete elements. In this case, the linear model of a cable with a small sag serves as a continuous model, while the elements, e.g., a translational spring, a concentrated mass, and a harmonic oscillator, serve as the discrete elements. The method is based on the analytical solutions in relation to the constituent elements, which, when once derived, can be used to formulate the equations describing various complex systems compatible with an actual structure. The numerical analysis shows that, the method proposed in this paper can be successfully used to select the optimal parameters of a system composed of a cable with discrete elements, e.g., to detune the frequency resonance of some structures.展开更多
随着新能源渗透率不断提高,微电网在分布式能源(distributed energy resources,DERs)运行控制中的作用日益凸显,但分布式能源的接入会给微电网的运行带来扰动。为此,提出了一种基于多智能体系统(multi-agent system,MAS)的两级分散协调...随着新能源渗透率不断提高,微电网在分布式能源(distributed energy resources,DERs)运行控制中的作用日益凸显,但分布式能源的接入会给微电网的运行带来扰动。为此,提出了一种基于多智能体系统(multi-agent system,MAS)的两级分散协调控制方案来保证微电网的高安全性和稳定性。上层智能体基于Petri网(Petri-net,PN),针对各类能源的不同工作模式,构建DERs的PN模型,并以PN模型设计协调逻辑控制指令集,通过网格自适应直接搜索过滤算法(mesh adaptive direct search filter algorithm,MADSFA)选择最佳的协调逻辑控制指令。下层智能体负责局部连续控制,针对不同功率特性DERs的逆变器,分别采用不同的下垂控制策略。为保证暂稳态下微电网的稳定性,在逆变器和下垂控制器之间增设预设性能控制器,以确保逆变器的输出功率误差无论是在暂态还是稳态的情况下均能稳定在预设误差范围以内。同时为提高微电网系统的稳定性,两层之间的交互采用主从和无固定主从相结合的通信模式,这种交互机制提高了MAS在系统的实时监控过程中的时效性和灵活性。最后,仿真结果验证了基于MAS两级分散协调控制策略的有效性。展开更多
文摘A growing body of studies and systematic reviews show evidence of the beneficial effects of physical exercise on core symptoms of ADHD. Furthermore, studies indicate that physical exercise as an adjuvant can enhance the effects of medication in the treatment of ADHD. Aerobic and coordinative exercises improve executive functioning through their effect on neurocognitive domains that are implicated in ADHD. It is postulated that through their specific modus operandi, aerobic exercise, by raising cortical arousal levels, improves impaired alerting functions whereas coordinative exercises improve the regulation of inhibitory control through the involvement of a higher variety of frontal-dependent cognitive processes. The increasing use of routine neurocognitive testing with continuous performance tests (CPT), such as the QbTest, at clinical assessments for ADHD allows for an innovative approach to identify the assessment impairments in alerting function and inhibition control that are related to ADHD and accordingly choose aerobic or coordinative physical exercise in a more targeted fashion.
文摘Turbulent flow, the transpor＇t of inclusions and bubbles, and inclusion removal by fluid flow, transport and by bubble flotation in the strand of the continuous slab caster are investigated using computational models, and validated through comparison with plant measurements of inclusions. Steady 3-D flow of steel in the liquid pool in the mold and upper strand is simulated with a finitedifference computational model using the standard k-εturbulence rondel. Trajectories of inclusions and bubhles tire calculated by integrating each local velocity, considering its drag and buoyancy forces, A ＂random walk＂ model is used to incorporate the effect of turbulent fluctuations on the particle motion. The attachment probability of inclusions on a bubble surface is investigated based on fundamental fluid flow simulations, incorporating the turbulent inclusion trajectory and sliding time of each individual inclusion along the bubble surface as a function of particle and bubble size. The chunge in inclusion distribution due to removal by bubble transport in the mold is calculated based on the computed attachment probability of inclusions on each bubble and the computed path length of the bubbles. The results indicate that 6%-10% inclusions are removed by fluid flow transport. 10% by bubble flotation, and 4% by entrapment to the submerged entry nozzle （SEN） walls. Smaller bubbles and larger inclusions have larger attachment probabilities. Smaller bubbles are more efficient for inclusion removal by bubble flotation, so Inng as they are not entrapped in the solidifying shell A larger gas flow rate favors inclusion removal by bubble flotation. The optimum bubble size should be 2-4mm.
基金National Natural Science Foundation under Grant No.51574201Opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)under Grant No.SKLGP2016K017+2 种基金Open Research Fund by Sichuan Engineering Research Center for Emergency Mapping&Disaster Reduction under Grant No.K2015B008The State Administration of Work Safety under Grant No.2014_3335Soft Science Research Projects in Sichuan Province under Grant No.2015zr0049
文摘This study explores the quasi-real time inversion principle and precision estimation of three-dimensional coordinates of the epicenter, trigger time and magnitude of earthquakes with the aim to improve traditional methods, which are flawed due to missing information or distortion in the seismograph records. The epicenter, trigger time and magnitude from the Lushan earthquake are inverted and analyzed based on high-frequency GNSS data. The inversion results achieved a high precision, which are consistent with the data published by the China Earthquake Administration. Moreover, it has been proven that the inversion method has good theoretical value and excellent application prospects.
文摘An algorithm is presented to analyze the free vibration in a system composed of a cable with discrete elements, e.g., a concentrated mass, a translational spring, and a harmonic oscillator. The vibrations in the cable are modeled and analyzed with the Lagrange multiplier formalism. Some fragments of the investigated structure are modeled with continuously distributed parameters, while the other fragments of the structure are modeled with discrete elements. In this case, the linear model of a cable with a small sag serves as a continuous model, while the elements, e.g., a translational spring, a concentrated mass, and a harmonic oscillator, serve as the discrete elements. The method is based on the analytical solutions in relation to the constituent elements, which, when once derived, can be used to formulate the equations describing various complex systems compatible with an actual structure. The numerical analysis shows that, the method proposed in this paper can be successfully used to select the optimal parameters of a system composed of a cable with discrete elements, e.g., to detune the frequency resonance of some structures.
文摘随着新能源渗透率不断提高,微电网在分布式能源(distributed energy resources,DERs)运行控制中的作用日益凸显,但分布式能源的接入会给微电网的运行带来扰动。为此,提出了一种基于多智能体系统(multi-agent system,MAS)的两级分散协调控制方案来保证微电网的高安全性和稳定性。上层智能体基于Petri网(Petri-net,PN),针对各类能源的不同工作模式,构建DERs的PN模型,并以PN模型设计协调逻辑控制指令集,通过网格自适应直接搜索过滤算法(mesh adaptive direct search filter algorithm,MADSFA)选择最佳的协调逻辑控制指令。下层智能体负责局部连续控制,针对不同功率特性DERs的逆变器,分别采用不同的下垂控制策略。为保证暂稳态下微电网的稳定性,在逆变器和下垂控制器之间增设预设性能控制器,以确保逆变器的输出功率误差无论是在暂态还是稳态的情况下均能稳定在预设误差范围以内。同时为提高微电网系统的稳定性,两层之间的交互采用主从和无固定主从相结合的通信模式,这种交互机制提高了MAS在系统的实时监控过程中的时效性和灵活性。最后,仿真结果验证了基于MAS两级分散协调控制策略的有效性。
