The present paper studies the use of genetic algorithm to optimize the tuning of the Proportional, Integral and Derivative (PID) controller. Two control criteria were considered, the integral of the time multiplied by...The present paper studies the use of genetic algorithm to optimize the tuning of the Proportional, Integral and Derivative (PID) controller. Two control criteria were considered, the integral of the time multiplied by the absolute error (ITAE), and the integral of the time multiplied by the absolute output (ITAY). The time variant plant tested is a first-order plant with time delay. We aim at a real time implementation inside a digital board, so, the previous continuous approach was discretized and tested;the corresponding control algorithm is presented in this paper. The genetic algorithms and the PID controller are executed using the soft processor NIOS II in the Field Programmable Gate Array (FPGA). The computational results show the robustness and versatility of this technology.展开更多
One of the issues of Thermodynamics is the question of what exactly thermo-dynamic equilibrium means.It is often interpreted as thermalequilibrium.The question is if this is correct.This is especially relevant for the...One of the issues of Thermodynamics is the question of what exactly thermo-dynamic equilibrium means.It is often interpreted as thermalequilibrium.The question is if this is correct.This is especially relevant for the case of the atmosphere,where gravitational energy also plays a role,which might allow for temperature gradients in equilibrium.In order to answer this question,this work goes back to Boltzmann’s original ideas.As will be shown here,thermo-dynamic equilibrium also means thermal equilibrium in this case.Moreover,it will also be shown why a lapse rate(a linear drop of temperature with alti-tude)is observed in a mechanically stable atmosphere.The implications for climate research are discussed.展开更多
The feedback between carbon dioxide,CO_(2),and the temperature of the atmos-phere is analyzed.Starting with the assumption that the average temperature is a function of the carbon-dioxide concentration in the atmosphe...The feedback between carbon dioxide,CO_(2),and the temperature of the atmos-phere is analyzed.Starting with the assumption that the average temperature is a function of the carbon-dioxide concentration in the atmosphere,[CO_(2)],the so-called greenhouse effect,feedback is introduced into the system:in-creased temperature can further increase the CO_(2) concentration that causes the temperature rise in so-called positive feedback.On the basis of the availa-ble data,it is argued that this cannot be the case;the feedback must be negative at the moment.Moreover,the observed correlation between[CO_(2)]and tem-perature varies across different time scales,suggesting different processes are at work.It is not possible to explain all the data with a single phenomenon like the greenhouse effect,even when feedback is included.展开更多
文摘The present paper studies the use of genetic algorithm to optimize the tuning of the Proportional, Integral and Derivative (PID) controller. Two control criteria were considered, the integral of the time multiplied by the absolute error (ITAE), and the integral of the time multiplied by the absolute output (ITAY). The time variant plant tested is a first-order plant with time delay. We aim at a real time implementation inside a digital board, so, the previous continuous approach was discretized and tested;the corresponding control algorithm is presented in this paper. The genetic algorithms and the PID controller are executed using the soft processor NIOS II in the Field Programmable Gate Array (FPGA). The computational results show the robustness and versatility of this technology.
文摘One of the issues of Thermodynamics is the question of what exactly thermo-dynamic equilibrium means.It is often interpreted as thermalequilibrium.The question is if this is correct.This is especially relevant for the case of the atmosphere,where gravitational energy also plays a role,which might allow for temperature gradients in equilibrium.In order to answer this question,this work goes back to Boltzmann’s original ideas.As will be shown here,thermo-dynamic equilibrium also means thermal equilibrium in this case.Moreover,it will also be shown why a lapse rate(a linear drop of temperature with alti-tude)is observed in a mechanically stable atmosphere.The implications for climate research are discussed.
文摘The feedback between carbon dioxide,CO_(2),and the temperature of the atmos-phere is analyzed.Starting with the assumption that the average temperature is a function of the carbon-dioxide concentration in the atmosphere,[CO_(2)],the so-called greenhouse effect,feedback is introduced into the system:in-creased temperature can further increase the CO_(2) concentration that causes the temperature rise in so-called positive feedback.On the basis of the availa-ble data,it is argued that this cannot be the case;the feedback must be negative at the moment.Moreover,the observed correlation between[CO_(2)]and tem-perature varies across different time scales,suggesting different processes are at work.It is not possible to explain all the data with a single phenomenon like the greenhouse effect,even when feedback is included.
