Category: Engineering

A visualization of reversible vs nonreversible processes

A visualization of reversible vs nonreversible processes

A visualization of reversible vs nonreversible processes

08/08/17

“What exactly is the difference between reversible and non-reversible systems?”

 

Reversible and non-reversible systems are two of the most fundamental and confusing concepts in thermodynamics. But this visualization should help clarify them. Let’s take a ping pong game. If we are playing without score, then after a round is over, everything goes back to normal with no change in the system, making it reversible. However, if we are keeping score, then after every round the number of points change forever, making this process non-reversible! 

Processes

Processes

Processes

08/07/17

“What do we call it when a system’s state changes?”

 

Thermodynamic systems have a variety of properties, ranging from temperature to pressure to volume, which all make up its state. However, these properties are subject to change if the system is not in equilibrium. So what do we call this change in properties? Well, after much investigation, thermodynamicist have come up with the term process to describe this change. Processes can be of many types, such as changes in volume or pressure.

Linear programming

Linear programming

Linear programming

08/06/17

“How can we maximize or minimize a set of linear equations?”

 

Often times, when working on problems, we have multiple variables related by multiple equations. For example, let’s start out with this situation. Let’s say we have two machine parts x and y that cost 2 dollars and 5 dollars to make respectively, symbolically p(x,y) = 2x + 5y. And let’s also say that we have to make a total of 100 machine parts respectively, or x + y = 100 (blue). And let’s also say that 202 times the number of part x and 5 times the number of part y must be equal to 1400, or 20x + 5y = 1400 (green). So how can we find the minimum price that meets all of our production needs? Well, let’s plot it on a graph (pictured), check all of the points of intersection (In this case (0,100), (60,40) and (100,0) ), and then see which of these points return the minimum desired quantity (In this case (0,100) –> $200). Linear programming can be applied to all forms of applications, ranging from engineering economic systems to control theory and even to general business!

Contour of model predictive control

Contour of model predictive control

Contour of model predictive control

08/04/17

“How can we predict how a system will react based on how it reacts right now?”
When working with control systems, we often have some desired output in our mind. However, frequently the actual performance of our systems diverges greatly from what we want. So how can we use our engineering mindset to correct this problem? Well, let’s think about it. We can tell a computer how we want a certain system to behave. And we can also create a log of its outputs. So what if every time we gave an output, we took its data, compare it to our desired, and try to minimize the difference with the next iteration? Well, this is the fundamental idea behind model predictive control and is used in industries spanning from building controls to renewable energy to intelligent transportation systems!

Passive solar building design

Passive solar building design

Passive solar building design

08/03/17

“How can we make buildings use solar energy without using machines?”

 

One of the most commonly debated topics within the field of renewable energy is how to integrate solar power into everyday buildings. And most of the time this talk is on how we can put more solar power on buildings. However, what if we were to rethink this model? Instead of forcing more machines to be put into a building, let’s just reconfigure the building itself to use the sun more efficiently! For example, to use larger windows such that rooms receives more sunlight, or use green roofing to create more natural insulation.

Demand response

Demand response

Demand response

08/02/17

“How can we prevent a grid overload using a simple technique?”

 

We have a problem. We would like the demand usage for the electric grid to be as equalized as possible, such that the electricity drawn in at one time would look the same as the electricity drawn in at another. But this is almost never the case. Instead, the demand for the grid varies greatly throughout the day. And sometimes these demand peaks are so high that they destabilize the grid! So how can we use our engineering mindset to solve this problem? Well, what if we were to just shift electricity usage from times of peak load to times of less intensive load? This is the fundamental idea behind demand response and can be accomplished with economic incentives and through smart electricity control.

Industrial ecology

Industrial ecology

Industrial ecology

08/01/17

“What is Industrial Ecology?”

 

Things are changing on  Earth. Climate levels are rising, the human population is expanding, and industrialization is increasing, while our natural resources are going down down down. So how can we create a framework that studies how all of these complex systems interact with one another? Well, after many years of research, an entirely new scientific field has formed, industrial ecology. Industrial ecology is the study of how energy and resources flow through our modern industrial system. Industrial ecology looks at this issue through a multitude of perspectives, such as engineering, economics, natural sciences, and sociology.

Shell and tube heat exchanger

Shell and tube heat exchanger

Shell and tube heat exchanger

07/31/17

“What is the most popular type of heat exchanger?”

 

Let’s think of a design for a simple heat exchanger. First, let’s take a bundle of tubes and put it into a shell. Then, let’s run one fluid through the tubes and another around the tubes, both at different temperatures. Over time, the heat from the hotter one to the colder one. This setup is known as a shell and tube heat exchanger. Shell and tube heat exchangers come in two varieties, single phase (which have the fluids in only one phase) and multiphase (which uses both gases and liquids simultaneously). Because of their simple construction, shell and tube heat exchanger have become the most popular in the world.

 

Embedded systems

Embedded systems

Embedded systems

07/30/17

“What houses the controls for cyber-physical systems?”

 

Mechatronic systems require controls software in order to function correctly. However, how is this implemented physically into the system? Well, let’s use our engineering mindset to find out. We know that microcontrollers can perform simple controls tasks. So what if we were to hook a number of them together and program them with software to make a controls unit focused on one task? Well, this piece of technology is known as an embedded system and can be found in electro-mechanical operations worldwide. Examples of embedded systems include braking systems in vehicles, thermostats, and the motors on NASA’s Mars Curiosity Rover!