Response to 7/17

What I found most interesting about this class was the concept of machine vision. Engineering endeavors often mimic processes that occur naturally. Though I’ve come to this realization before, I’m still amazed when I learn about new research projects that are basically recreating nature. In a completely secular sense, its both frightening and fascinating how scientists can play God, creating artificial mechanisms to emulate that which has been created by unknown hand. Its just strange to think about, I mean, we don’t really know how the human eye was formed or how a hummingbird developed, but we seek to create things that behave in the same way. And when I think about the development of technology… its almost as though we’re forcing evolution upon our artificial creations. Like machine vision, for example. When it was first invented, its range of recognition was extremely narrow. Now we have orange harvesters that use machine vision to identify and pick oranges. The same thing happens in nature. A certain organism must adapt to change over time. Micro-evolution has been scientifically proven. So, in refining our nature-mimicking technologies, we essentially model nature as well.

Life is just like a giant circle… everything relates somehow.

Anyway, I looked up machine vision because I thought it was interesting.

Basically the way machine vision works is a smart camera (a digital camera, framegrabber, and processor) takes a picture of an object that is in position to be inspected. The camera will use lighting that is designed to illuminate parts of interest and downplay that which is not important. The framegrabber then translates the photo into digital format and stores it in the computer’s memory. Machine image software will then reduce noise or perform binarization (conversion of gray shades into black and white). If the machine vision is being used on an assembly line or performing some other inspection, it will count the desired features on the object (defects, markings, dimensions, etc.) and either pass or fail it, according to programmed specifications.

Presently, machine vision is used mostly in single, repetitive tasks such as those involved in product inspection, safety monitoring, and quality control. To a certain extent, machine vision is more reliable than human vision in terms of inspection, because humans are susceptible to distraction and lack of focus. But machine vision is still a long way from even approaching human adaptability, as most machine vision systems cannot adjust to variability in lighting or image degradation.

Response to 7/15

I’m not sure if this is an accepted method of response, but if not I can just redo this post.

I remember learning about the Tacoma Narrows Bridge collapse a while ago in class, but this morning we had a physics demonstration and the collapse was referenced yet again (I guess maybe its a commonly used scare tactic for physics and engineering students? haha). Resonance was physically demonstrated using speakers. From what I understood, the speakers were resonating at an adjustable frequency inside a box with a hole in each end and the middle, above which a strip of glass was placed (suspended an inch or so above the holes). The frequency was increased until the glass shattered. This reminded me of a really high-pitched singer breaking a glass… which I realized, after seeing this demonstration, is actually possible.

The Tacoma failure was caused by resonance in the second torsional mode (the frequeny was 0.2 Hertz), meaning the center remained still while the sides moved in opposite directions. The midpoint stayed still as well, and the two sides of the bridge wavered oppossingly. The cause of this resonance is said to be aeroelastic flutter, which is when the angle of attack between a structure and a force is increased. Once something reaches a critical angle of attack, the air is no longer flowing smoothly over its surface and it is said to be in a stall. This term typically applies to aviation, but it in this case it just means that the bridge began to twist against the force.

Quick side note – I didn’t know who Tesla was before right now, and since I’m talking about resonance, he deserves a mention. Here is a pretty sweet biography on him: http://www.intuitor.com/resonance/tesla.php

But back to bridge failure.

In order to prevent bridge collapse, wind tunnel testing is now mandatory for all designs. This, however, only measures the aerodynamic properties of the bridge – not the material strength or mechanical properties. Those are tested using computer models.

Although I can understand the concept of resonance, how exactly does it occur? How can a specific structure, such as a bridge, which is made out of many different materials, resonate at one given frequency? Does this happen at an atomic level? And how do computers test the mechanical properties of structures? It doesn’t make sense to me. Why couldn’t you just build a model and test it? Why is a computer more reliable? And how was the information for the computer to reference obtained?

Also, when the Tacoma Narrows bridge was resonating in the second torsional mode, does that mean the frequency traveled in sine waves? Do waves (in resonance) travel in specific forms? Can there be cosine and tangent waves, too? And if it was a sine wave, then would the midpoint on the bridge be zero, therefore remaining still? But what about the center line? Would that just be the x-axis on an x-y-z plane?

Since the Tacoma collapse occured at a mere 42 mph wind speed, I’m assuming that nowadays bridges are designed to resonate only at high wind speeds. Is that why they close down bridges during hurricanes? I’d never really considered that before. I always just though that bridges were closed to prevent cars from blowing off. Closing them because of resonance makes much more sense.

Could a building collapse because of resonance? Is that what happens in eathquakes?

Wikipedia says yes. Apparently a building’s resonance is typically 10 hZ divided by the number of floors.

A good example that I just stumbled across (relating to resonance) is a swing. When you are pushing someone on a swing, the swinging will only increase if you push him or her at a certain point, otherwise the swinging will decrease. This works the same way as the building (or bridge). If the eathquake waves are resonating at the same frequency as the building, then the amplitude will increase and the building will break.

Wow, calculus is actually applicable. Why don’t they tell us these things in school?

I apologize for being so scatter-brained and writing such a disjunct post. I always feel more knowledgeable after these assignments, though, so perhaps its a good thing.

Response to 7-10

I feel that this was the best class we’ve had so far, and I definitely learned a lot. I think the class as a whole has opened up more, which allows for better discussion and a greater wealth of shared information. The week before this class, Dr. Jones of the materials engineering department gave us a phenominal lecture, so this was a great follow-up. I especially liked that the production of materials was covered, because I like to know not only how things work, but how they are made.

What I like best about this class is that I am learning the principles of engineering in a much less intimidating fashion than I would in, say, a physics class at my high school. I enjoy being challenged, but this is a nice change of pace. I am actually learning and not just enduring rote memorization for the sake of passing a test.

Anyway, since I have yet to post 5 weblinks, I guess that is how I will respond to this class.

1.) http://www.csa.com/discoveryguides/fuecel/overview.php

This is a great website on solid-oxide fuel cells, and it relates to class because there is an extensive section on materials selection. Materials are a huge deal in fuel cell development right now. SOFCs typically use ceramic substrates as their electrolyte, but ceramic must be heated to temperatures of up to 1,000 degrees Celsius in order to conduct oxygen ions (an integral part of fuel cell function). Current SOFC research is focusing on new materials (such as stainless steel) that can perform at lower operating temperatures.

2.) http://www.rwc.uc.edu/koehler/biophys/2f.html

After class, I was still a little bit fuzzy on the difference between stress and strain. This webpage uses some creative examples (such as a ball of clay and a fractured skull) to make the distinction between the two terms. It helped me quite bit. It also explains related terms such as “extensibility” and “toughness”.

3.) http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch13/structure.php

This page details the different molecular structures that metals can take on. I particularly liked the section about properties in relation to structure, because it explains why metals are ductile, malleable, solid, capable of reflecting light and thermally absorbent. It also explains that a metal’s molecular structure can be changed most easily when it is heated, which reminded me of the katana video we watched in class.

4.) http://www.memsnet.org/mems/processes/lithography.html

I had always thought of lithography in the stone-engraving sense, but I now know that it plays a big role in micromachining and microelectromechanical (say that 5 times fast) systems. It’s still a foggy concept for me (wikipedia helped some), but this website explains the process of microlithography.

5.) http://www.infoplease.com/ce6/sci/A0851203.html

This basically just explains the process of vulcanization (I looked it up primarily because the word sounds cool). I learned that it was invented by Charles Goodyear in 1839 (maybe he had something to do with Goodyear tires?). Vulcanization has been critical for the auto industry, and is basically what fueled the wide use of rubber. So I guess Goodyear was pretty important guy.

Thanks for reading

Response to 7/1

Schulung, D. “Terminology and Symbols in Control Engineering.” Samson (2000). 5 July 2008 <www.samson.de/pdf_en/l101en.pdf>.

This technical article helped clarify what was taught in class (I’m a visual learner, so it helps me quite a bit more to read in order to process information).

The difference between a closed and open loop is simply that an open loop does not monitor feedback, while a closed loop does. This was stated in class, but what I did not consider is that an open loop would, in most cases, require an alert operator to make sure nothing goes awry. Furthermore, this type of loop would need to run a process that is not affected by fluctuation. Off the top of my head, I can’t really think of any processes that are run by open loops. A quick rifle through the infinite resource that is wikipedia suggested that a sprinkler system would be an example of an open loop system, because it does not measure soil moisture – it will turn on at the same time every day regardless of soil condition, which leaves the lawn-person (or whatever he/she would be referred to as) to regulate exactly how often the lawn gets watered.

Anyway, this is suppossed to be about the journal article.

A control system is comprised of several components:

a) a controller and actuator (something causing movement, as per Robert)

b) that which is being controlled

c) measuring equipment (if using a closed loop)

This immediately reminded me of a science experiment. I’m sure you’re all familar with the scientific method; when I was first learning it I had trouble differentiating the independent and dependent variables. A control system essentially models these two components. Think of an air conditioner for example. The temperature, or what is being controlled, would be the dependent variable, because it is being altered and measured. The a/c system would be the independent variable, because temperature depends on its method of operation.

This comparison may be a little out-there, but it makes sense to me.

Back to the article.

In order for a closed loop control system to work properly, it must restore equilibrium quickly and adjust its reference variable in accordance with outside alterations. In some systems, the reference variable will change frequently. For example, a wind turbine must be able to adjust to a wide range of wind speeds (or no wind at all). In order for it to achieve maximum power generation, it is imperative that its reference variable be modified in response to varying wind speeds. In other systems, reference variable adjustment speed may not be quite as important. I would imagine, in considering once again the air conditioner, that the unit would not need to adjust instantaneously to changes in temperature outside the home. Air dispersion is not an overly rapid process, and if the A/C changed with every minor fluctuation in outside temperature, then it would simply be overworking itself.

Anyway, thats the basic gist of the article (with some added insight from yours truly). I like to use this blog as an excuse to spew my newfound realizations in engineering.

Response to 6/26

One of the topics that I found most interesting in class was the manual versus automatic transmission discussion. My dad and I argue all the time about it; I tell him its worthless to drive stick, and he retorts that it ensures better fuel economy.

So, after discussing this subject in class, I decided to do a little research on my own.

The most prominent disadvantages of driving an automatic are that

a) The car costs more.

b) It gets fewer miles to the gallon, due to power loss from slippage in the gearbox. Manuals provide a 5-15% better fuel economy. Furthermore, less energy is lost through heat in a manual car.

c) It accelerates more slowly, because the kickdown facility is delayed.

d) It may require more service.

The advantages of driving an automatic are, from what I gathered:

a) More freedom while driving. Without having to worry about shifting gears and pressing the clutch, one can focus more on his or her surroundings. Although I supposse this could be a bad thing, too, as drivers are probably more likely to multitask when driving an automatic, which could easily lead to accidents.

b) Automatics are easier to start from a standstill.

c) They have higher resale value than manuals.

d) Automatics are generally less stressful to operate in high traffic conditions.

So, after some fact-finding, I maintain my argument that automatics are the way to go. I guess I may fall into a stereotype here (its been said that women prefer automatics because of their ease and comfort), but I think if I had more testosterone, a manual would be the perfect power-trip.  Really, its just a matter of personal preference, budget, and driving habits. I do hope to learn to drive stick one day, if only to appease my dad.

 

Response to 6/24 lecture

a) What did you find interesting about class today? (b) How could class have been taught better today? (c) How might you use what you learned today as an engineer or entrepreneur? (d) How does knowing what you learned today affect your daily life?

a) I found most interesting the stark diversity between seemingly similar people. When we discussed different methods of solving engineering problems, we all provided distinct and unique responses. I was also interested in the methods of memory recall; I was intrigued by the fact that memories are more commonly associated with emotions and feelings rather than sensory details and facts. The human brain is overwhelmingly complex and I find it helpful to consider the ways in which it works when trying to study or learn new concepts.

b) Class so far has been very quiet; I understand this to be a result of exhaustion on the students’ part and perhaps unfamiliarity on the teachers’ part. But this, I anticipate, will easily be overcome and I still maintain high expectations for this class.

c) What learned will easily apply to engineering and/or entrepreneurship. In order to learn the concepts of engineering, or any other subject for that matter, one must attain a thourough understanding of how one’s brain works. In identifying what type of learner I am, I can then develop study habits that cater to my strengths. If I am a visual learner, it doesn’t exactly help to listen to a lecture. If I am an introvert, it won’t help me to study in a large group. These seemingly pithy details can make a difference in how well and how much I comprehend, which is undeniably important to become an engineer. Also, engineers must know where to find reliable information. This lecture provided me with many resources from which to seek desired knowledge.

d) I think my response to (c) covers this question, because learning is not just something that occurs in school. Learning happens everywhere in every moment of every day. In order to be not only a successful engineer, but a successful human being, I must know where to find information and how best to interpret it based on my individual congnizance.

Hello world!

I wish all of my homework assignments were this effortless.