Christina Holman | Design Blog

We finally made it to the end! After the preliminary design report, it was time to finalize our actual design (since we were given enough materials to make one truss to test). After doing a few more draft sketches and analysis, I was able to pick up on patterns on which types of designs produced the maximum strength (all within the parameters we were given). Finally, I came up with the sketch at the bottom-right, and the MATLAB analysis produced the highest load we were able to reach. We theorized that: two members would buckle first instead of just one (Members 3 and 4); the maximum load is 11.62 ± 0.063N; and the total cost of the truss is $290 (under the budget limit). From there, we moved to prototyping: we cut the straws as close as possible to the lengths specified in our final design. To create uniform gusset plates, our "joints," we used the circular cap of an individual Tropicana Orange Juice bottle. It met the area requirements and acted as a stamp...

Motor and Case So, in the most recent lectures, we've talked a lot about what is called " Design for Manufacturing and  Assembly (DFMA) " -- or the combination of designing for the ease of manufacture and designing for the ease of assembly. Even the best assembly process in the world can fail under human errors like fatigue, time pressure, and plain carelessness. (We've all accidentally dived into an Ikea furniture assembly without fulling reading the instructions beforehand.) Hence, wisely, product designers tend to use 'mistake-proofing' features in order to make those kinds of careless mistakes obvious within seconds. Like a puzzle, either a piece fits or it doesn't. Otherwise, you'll end up with a deformed piece and an unclear final product. Honestly, those small DFMA pieces like a raised section of plastic can make or break how well-connected a handle is -- or even how easy it is to replicate the same level of quality that the company is promi...

So ME359 has been great but it has been an exercise in stamina . For a 2-credit class, where weekly homework is 70% of your grade, this is a lot of time and energy -- but, still, exciting. Like I said before, I do really well when it comes to project-based learning and real-world applications. And this course's final project has really been wonderful for that. The final project is to reverse engineer the Black and Decker Li2000 Screwdriver and then use the computer-aided design (CAD) software Creo to re-create the gearbox. This is an interesting task since the B&D Li2000 uses a planetary gearbox, which consists of three types of a gears that all lie on the same horizontal axis. My task is to create the ring gear (the outermost gear), the three pinion gears that rotate around that inner radius of that ring, the sun ring around which the pinion gears rotate, and, then, the planetary gear connected to the central axis of the screwdriver. Ultimately, I need to create all of ...

The second part of the final project for EK301 (Mechanics) consists of a preliminary design -- or, rather, several preliminary designs and one identified draft. Having the data from the straw lab test and the resultant code to determine the approximate load that a straw can hold based on its length, it took quite a bit of creativity to find the perfect combination of straws. However, to simplify this process, the class was instructed to use a MATLAB code that would take a design and then indicate which member of the truss would fail first. It is important to note that all designs were given the same parameters: Figure: One of two designs selected The truss must be a single, planar, simple truss.  Members must be joined concurrently at joints using the provided pins and double pinned to the guest plates.  Gusset plates may be any geometry but must have an area of less than 16 sq. cm. All joint-to-joint distances must be at least 10 cm and no longer than 16 cm. The ...

Wow... it's already the end of December and New Year's Day is right around the corner. I'm thankful for a lot this year: I was able to travel again, help people learn about design and their own potential, develop more skills, discover more about myself.... and, despite numerous challenges and some disappointments, I'm still pushing forward. I know I neglected this blog during the fall semester. (Sorry.) However, I hope to pick things up again in the spring. I'm coming up on my final and last semester in college -- which sounds just as crazy to me as it probably does to you. **Recap**  I did finish my report,  An overview of economic theory and approaches for evaluating the productivity of water on Santiago Island in Cape Verde, from this summer with INIDA. Hopefully, I can publish out-of-house too. Also, I presented at the 2017 Tanner Conference on my activities in Cape Verde this summer, and it seems that a number of people liked my brief talk. Then, this fall...

This Friday, I took a step to introduce the WeLab teaching style by forming a brainstorming workshop between the UniCV engineering professors and students - and it was a  HIT!  A few days before we prepped by going over the brainstorming activity (below) Professor Banzaert did in my first class with here: what materials do we need, how will we use the most of an hour, what should the environment/vibe feel like, etc. I even got Paulo to agree to help breakdown the formal professor-student division that Cape Verde (and most schools everywhere) cling too. The day of, I was expecting each professor to bring maybe 1 or 2 students but there were  so  many people (20-30 people). After doing a brief presentation on Wellesley (same ECAA presentation) and the brainstorming rules (below), we had to break down into smaller and smaller groups for the activities. Even better, everyone who came was engaged and even wanted to stay longer to fuel more ideas and connections as ...

Wednesday, we returned to the Hydroponics Center for a second visit. The director Joao quickly whipped up a meeting with a few staff members so we could sit down and talk more about Wellesley and the potential for collaboration. In addition to him, we spoke with one of the engineers there, a social scientist and an intern to ask them about their work and their ideas for the future. It started off a little slow since I think people were shy but then picked up pace as Mackenzie and I started seeding ideas and others built off of them. It's one thing to talk about thoughts at a table but it's another thing to actually see them. Together, we gathered a list of potential topics to explore there and then they led us outside to show us the topics they talked about: Investigation of renewable, sustainable energy sources (Solar and/or Wind).  They have several large machines necessary in seed sorting/planting, soil mixing, irrigation regulation, and daily office functions ...

The second day of interviews was definitely the best! Although many spouted their opinions to us on farmers using traditional irrigation (instead of gota-gota/drip irrigation), it was absolutely amazing to see it in action/finally understand the system and talk to the farmers directly on why they have stuck with traditional systems. We got different opinions and I absolutely want to hear more from that target: We also spoke with two more gota-gota farmers. One is the only member of farmers' association using gota-gota; The other owns a private - and exporting - company. (Note:  Again, all of these farmers are allowing us to use photos and names. ) First things first, traditional irrigation is referred to as " alargamento ," and you really won't understand it unless you see it. This technique is ancient ("since Adam and Eve" as one farmer said) and, generally, farmers learn it from their fathers. We were so lucky to see it in action, because, when you...

So the following two days were filled with interviewing farmers (in different municipalities and of different backgrounds and resources). And to be honest, it was the most useful thing we've done/seen here. A lot of people can talk and read about practices in Cape Verde but it is entirely different to be there to experience it and talk with the people directly. I believe "going to the source" is the most useful way of understanding anything new. So that's what we did for three days this week. We started off close to the office, speaking with two farmers ( both of whom are allowing us to use their names in publications ). The first, clearly, had experience and resources with farmer and proudly proclaimed he was the one to teach and start strawberry farming on the island. Brief profile (or take-aways): 6 hectares  of very hilly land ( boy, did we walk... ); 3 wells and 5 tanks with programming system for irrigation Believes government should have more dams: says...

Tuesday, we were finally able to see the actual (gota-gota; drip) irrigation system. Regla organized a tour for us to see the irrigation system and management for the fields at INIDA's headquarters in Sao Jorges. We walked quite a bit and through lots of unpaved paths to see the well, reservoir/tank, sand-filters and tubing mechanism in the individual plots. BUT we learned so much that can help us for the paper. I was able to make a lovely sketch (below) that shows the flow of water from macro-scale and at the micro-scale in each plot area. Water is pumped from a well up into an uncovered, cement "reservoir" or tank. This is where water is held for irrigation but, because it is uncovered, it should/needs to be cleaned (a lot). The tank is built at the highest point in order to use gravity to direct the flow of water through large and long tubs into the sand-filters (Japanese made, cleaned every 6 months) and two smaller filters after that. The plots are built like tie...

I am really glad I followed my hunch on the hydroponics project. That is an  amazing  facility and one of the most advanced I've seen here. I don't have much experience with hydroponics but from what I've seen, it works really well: the lettuce, tomato, and cucumber plants were absolutely huge! (Thursday, we met with the director Joao Monteiro.) He told us that, with hydroponics setups, you get bigger and more produce: they use a substrate and coconut fibers (to help stabilize the plant) in a pod as the plant grows up a rope. The facility also uses both drip irrigation and mechanical spray system that they sell to farmers. However, all of the water is pumped through an elaborate, advanced valve systems (through which they can regulate fertilizer too): It was a gift from their partner in Spain. They are able to plant so many many seeds so quickly because they also have an advanced seed-sorting and soil-mixing machine from Italy. Both systems have no siblings in Cape Ve...

Mackenzie and I were invited by the ECAA professors to attend the final round of student presentations on Friday -- and to also present what we are doing too. We weren't quite sure what to expect but we figured the best route would be a short discussion about Wellesley and who we are as well as our two missions -- INIDA and project collaborations. I made a very elegant powerpoint (if I do say so myself) with several photos of Wellesley in order to give them a clearer picture of this "women's college." (See below.) It seems that our presentation was well-received (and my Crioulo was understandable -- yes, this was almost entirely in another language). We got quite a few questions and five ECAA students volunteered to work with us, especially on the INIDA paper. We have a team now! I can't wait to have our first meeting and get to work. I'm glad we are finally making some progress: I just hope we can keep the momentum.

Last week, when Paulo brought us to his class of third/fourth-year English students, Mackenzie and I learned that students are required to do a quantitative analytical paper and defend it but  have never been taught statistics or research methods. Many of the students seemed lost and stressed out about having no experience in data collection and analysis. So, as the resident economics major who just finished a course in Econometrics, I offered to do a "statistics workshop" and help them formulate their analysis plan for their research topics. The following Monday (this Monday), it went well: students who had no experience with what we, Americans, claim to be "basic" graphs like  y=mx+b  left the session with an understanding of qualitative versus quantitative data; different types of data; descriptive statistics, regression and ANOVA; and even graph and table options for visualization. I'm really glad I could help them out and it felt great when many came up...

On Friday, Paulo set up a meeting with the engineering faculty at Uni-CV main campus, so that we could also make progress on the second goal -- laying the groundwork for joint projects for WeLab courses. Mackenzie and I had already headed into Praia for a meeting with the former "Ministry of Rural Development" (now Ministry of Agriculture and Environment) and ElectraSul - the water and electricity plant as well as desalinization plant. Unfortunately, there was some miscommunication for both meetings; on the bright side, we met with a statistician at the ministry and had more free time since we couldn't go to ElectraSul. Because we had some extra time to stroll around Praia, Mackenzie called a contact at the US embassy who she met on the plane ride over and we all decided to have lunch together. Lo and behold, we just so happened to go to the US ambassador's favorite lunch spot, and he sat with us over a meal. I am really glad all things happened like they did: I c...

INIDA has two other sites: one at the headquarters in São Jorges and the other in city of Tarrafal. We visited both to see the similarities and differences. Fortunately, for us, the sites tend to repeat the same experiments in the different climates and conditions. If we can grab the data from all of the sites to create an analysis, it would be great! Gilbert showed us around the home site and I was surprised to learn that there is a lot going on. There are plenty of mango trees and we passed several people collecting and sorting the mangoes, but there are also different types of sweet potatoes, tomatoes, strawberries, and cassava. Also, they started an experiment in hydroponics but the original head passed away so it was never finished. When I asked him more about it, Gilbert told us there  is  a center of hydroponics in Cape Verde (potential engineering project maybe?). He also showed us the drip-irrigation experiment, called "rega gota-gota" here...

Nora, who works with INIDA's site at São Domingos, was able to give us a tour and talk with us about general agriculture activities. She first took us to the "Estufas" which are tent-like, net structures they use to block insects, wind and dirt from their engineered "pretty" cucumbers. The tent themselves weren't in the best condition, with lots of holes in the material, but the plants seemed to be doing quite well. They produce these engineered plants in order to sell the seeds to farmers and the workers also have several non-tent experiments with tomatoes, potatoes, squash and pepper. There are  all  types of fruit (banana, mango, papaya, pilmebi, picanga, strawberry, etc) and INIDA is testing other plants like macadamia nut and eggplant in hopes of introducing them. (On a somewhat unrelated note, because of all these varieties of food, they have a problem with people stealing their food, ruining their experiments' results - and sometimes have ...