“How can control the rate of change of our control system?”
Proportional control systems are great for correcting the error of simple applications. However, one major drawback is that this method does not control the rate of change of the control system. For example, let’s say that we have a self-driving car that needs to accelerate to the speed limit of a roadway. Proportional Control might accelerate so fast that it actually overshoots the speed limit and causes an accident! To solve this, we can introduce a factor called a derivative control which modulates the rate of change of the system. If we were to introduce it to the self-driving car, then its rate of change would be held in a sustainable manner and decrease to zero as it becomes closer to the setpoint.
“How can we have a control method proportional to the error?”
Closed loop control systems respond to external stimuli with the use of an error compared to a setpoint. So how can we use this information to make an easy to use control system? Well, what if we were to base our adjustment to be proportional to the error, such that the higher the error the higher the restoring force? Well, engineers have implemented exactly this in a form known as proportional control and are used in applications such as self-driving vehicles and valve systems.
“What process in Thermodynamics holds the pressure and volume to a constant?”
Thermodynamics is known for its intense reliance on processes. Some of the most important types are classified as Polytropic processes. In polytropic processes, the pressure and volume are held to the constant given by the relation pv^n=c, where p is pressure, v is volume, n is the polytropic index, and c is a constant. A process is polytropic if it obeys the ideal gas law and if the heat to energy transfer as work at each infinitesimal step of the process is kept constant
“Can machines operating at part loads have different efficiencies than full loads?”
Machines can operate at variable loads. For example, an electric grid might be providing electricity to its entire network during the daytime and only a few houses at night. Because these different loads have different parameters, machines operating at partial loads have something called a part-load efficiency, or the efficiency when not at full (100%) loading.