Engineering Quarterly Winter 2023

Engineering Quarterly VOL.V. . . No.2

University of Mary

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WINTER 2023

W ELCOME !

Welcome to the winter issue of Engineering Quarterly, a newsletter published four times a year by the University of Mary Hamm School of Engineering. In it we try to include articles from each of the six engineering majors that we currently offer: Electrical Engineering, Mechanical Engineering, Civil Engineering, Computer Science, Construction Engineering, and Construction Management.

The intended audience of the Engineering Quarterly are engineers, engineering students, engineering alumni, future engineering students, and people working in fields closely related to engineering such as science, computing, and mathematics.

In this issue we include articles on design projects our students are working on, trips they have gone on, our annual engineering alumni event, service activities, spectacular careers our graduates are embarking on, and interesting assignments from our courses. Enjoy!

Dr. Terry Pilling Dean of Engineering

N EW A DMINISTRATIVE A SSISTANT AND A DJUNCT FACULTY

By TERRY PILLING

What brought you to Mary?

I’ve always been drawn to Mary, even before I became a student in 2010. There is a sense of peace and calm that you feel upon entering the campus. I have wanted to work here since the first time I came to Bismarck on Highway 1804 and saw the bell tower on top of the hill. Not long after my husband passed away in March of 2022 I saw the advertisement for the Administrative Assistant position on the website. I was intrigued but didn’t apply at the time because it was too soon after his death. A couple of months later I went back to the website and the ad was still there. I felt as though God was telling me something so I went ahead and applied. As they say, the rest is history.

What do you like to do in your spare time?

When I’m not playing fetch with one of my dogs, which she would do 24/7 if allowed, I like to read. Eventually I do hope to join a bowling league but I need to purchase my own ball, shoes and bag so I’m not using the house equipment. I also volunteer at my church.

Do you have hobbies, interests, pets, etc?

I have three dogs, a twelve year Border Collie/Blue Healer and technically two mutts, one is 3 and the other is 4. Both of them are Border Collie/Blue Healer, Maltese/Poodle and Australian Shepherd. The three year old might also have Red Healer in her.

I do occasionally make jewelry but mostly I make rosaries, prayer beads and dream catchers. I used to crochet and knit and I hope to start that back up again once I get into a more consistent routine.

What do you think of working here so far?

Patricia Smith joined the Hamm School of I love working here. Everyone is really nice Engineering this semester as our new admin- and they don’t see me as just an “Admin. istrative assistant and Adjunct Professor.

Asst.” but as an equal. Working here is giving me the opportunity to do something that I’ve wanted to do most of my life, teach.

I have always believed that everything, both the good and the bad, happens for a reason, that God has a plan for all of us if we trust in Him and let Him guide us, even if it’s not what we thought it would be. This past year has reinforced this.

O UTSTANDING P EER L EADER

By KATIE MEHRER

Trish has a Bachelors degree in Accounting, an MBA in Accounting, and has served as the Director of Tax Equalization in McIntosh County (2018-2022). Trish has also been a Certified Nursing Assistant for the Ashley Medical Center in Ashley, ND. Trish works mornings with us in Engineering and afternoons in the Science and Math Department in the Harold Miller Center. Trish will also be teaching a variety of courses for the University of Mary beginning in Fall 2023.

One of our senior mechanical engineering students, David Ruiz, was voted the 2022 Outstanding Peer Leader.

The winner of this award is chosen by their fellow Peer Leaders and David will receive his award at the Spring

Awards Banquet. The award recognizes a Welcome Week Peer Leader who excelled in their position. They warmly welcomed all those who they met on campus; worked well with students and fellow Peer Leaders; generated enthusiasm and excitement for Welcome Week events; and went above and beyond to serve their fellow students. The recipient of this award is an example to all other Peer Leaders and was a role model for the University’s Mission and Benedictine Values.

The Welcome Week Peer Leader program is a volunteer group. This was David’s third year volunteering for the Peer Leader program, and over those three years he has volunteer 134 hours. He also stepped forward this past year and applied for a Peer Team Leader position, which assists in the planning, development, and running of the Welcome Week Peer Leader program.

I think this award is well deserved, and that David is an amazing representative of the Hamm School of Engineering.

L OCKHEED -M ARTIN HIRES E LECTRICAL E NGINEERING S ENIOR

By TERRY PILLING

Our senior electrical engineering student Margaret Kuhar accepted a position with Lockheed Martin in New Jersey this semester starting in May 2023. Maggie came to the University of Mary from Philadelphia to study Electrical Engineering at the Hamm School of Engineering with a minor in Computer Science. Since arriving she has been active in peer tutoring, design projects such as building the controls systems for an inverted pendulum, and she has spent six semesters on the Dean’s Honors List. Maggie also took advantage of our Study in Rome program and spent a semester at the University of Mary’s Rome campus. In the summer of 2022, Maggie was an intern at Relay and Power Systems in Pennsylvania where she worked on Python data analysis, Machine Learning, and public outreach. Maggie has always been a friendly and outgoing student here at the Hamm School of Engineering and we are very proud of her many accomplishments.

The position at Lockheed Martin seems almost designed for our students at the Hamm School of Engineering in that the skills and educational experience that they are looking for are ones that we emphasize here. Remarkably, these are also skills that are not usually provided at other schools in the country. This gives our graduates an advantage over schools and puts our students at the top of the pile

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when applying at these companies. The following is a summary of the job description Maggie has accepted:

Engineering Quarterly WINTER 2023

• Able to work independently or as a The faculty of the UMary Engineering School are always thrilled to have our graduates remember of a team.

• Strong leadership, administrative, and turn to campus and tell us about all of the cool interpersonal skills. Strong written and things they have been up to and let us show them our new developments and the design verbal communication skills. projects of our current students.

• Experience in working in the Agile environment

Join us at Lockheed Martin, where your mission is ours. Our customers tackle the hardest missions. Those that demand extraordinary amounts of courage, resilience and precision. They’re dangerous. Critical. SomeAt Lockheed Martin Rotary and Mission Systimes they even provide an opportunity to tems, we are driven by innovation and inchange the world and save lives. Those are tegrity. We believe that by applying the highthe missions we care about. est standards of business ethics and visionary thinking, everything is within our reach – and yours as a Lockheed Martin employee. LockWATFORD C ITY B US T RIP heed Martin values your skills, training and

By RODRIGO DA COSTA APARECIDO education. Come and experience your future!

Basic Qualifications BS in Electrical Engineering, Computer Science/Engineering, Physics or equivalent experience.

• Demonstrated potential to work in a team environment on one or more of the following areas: analysis, requirements development, design, modeling, simulation, integration, test.

• Strong communications skills (written and verbal), strong team leadership, administrative and interpersonal skills desired.

We are planning to add a spring semester alumni event every year going forward where we invite our current graduates. Our hope is to help them make new contacts and begin collaborations with our former graduates and give them a leg-up on their careers. It is always fun to hang out with our graduates – both current and former.

DAY OF S ERVICE AT S TANDING ROCK

By JERIKA CLEVELAND

• Familiarity with computer architectures and algorithm development for a range On Friday, November 12th, a number of our of system/subsystem applications.

Mechanical and Electrical Engineering stu• Experience with the C programming dents traveled to Watford City, ND. to atlanguage, algorithm and software de- tend an engineering conference and meeting with the community. Watford city is a rapidly velopment is desired. growing, family oriented, community in west• Performs requirements development, ern North Dakota with brand new facilities verification and validation, cost and and many great career opportunities for engirisk, supportability and effectiveness neers. analyses for total systems.

• Ability to obtain a Secret security clearance is required.

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On Wednesday, October 19th, University of Mary observed “Day of Service,” canceling classes and encouraging students and faculty to give back to the community. In the past, the engineering school has been involved with creating gaga ball pits. This year, however, Dr. Carrico and I got on a bus with over 40 student and faculty from the School of Education to travel to the Standing Rock reservation.

A LUMNI E VENT

Experience With • Real-time determinism of RedHawk Linux • SE Linux for RHEL 6; Administration of OpenStack Cloud Platform • Software integration in Linux • New technology investigation

On November 18, 2022 we held our annual alumni event on campus. This year we gave • Git and Subversion our former students a tour of the completed • Shell Scripting Kelcy Warren Department of Civil Engineer- An hour south of Mandan, the Standing Rock • Linux Administration (multiple distri- ing and all the labs and new equipment. reservation has a mission school in Fort Yates. butions) Together with students in the education program, the engineering professors unloaded • Able to obtain and maintain a security their boxes of material and headed inside to clearance. meet the students. The goal of the day? Well, there were two activities planned. For the 4th Desired Skills through 8th graders, it was dropping an egg from the top of stairs and engineering soluProficient in the use of Linux, Unix Opertions to make sure they didn’t break. For the ating Systems and Bash, C/C++ programming K through 3rd graders, it was all about making languages. paper airplanes.

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Dr. Carrico designed boxes of materials for the older students, giving them a cardboard box with some materials, including a foam cup, a small square of Styrofoam, a balloon, string, and a few other items. The students were tasked with first identifying materials that may protect their egg, then to share their ideas to the other members of their groups. Given only 15 minutes the students devised many ways to protect the egg and all four teams were successful the first time around!

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day ended, all the students lined up threw their planes all at once.

One thing I learned from past events is that children, especially younger ones, will not remember the whole activity or the exact science behind it, but they will remember the people and the fun they had. So, the ultimate goal of the day was to have some fun and leave the students with a story to tell their families and hopefully a new memory associated to the word “engineer.”

C HRISTMAS T OY A DAPT- A - THON

By JERIKA CLEVELAND

This was not our plan. Many students who do this activity will fail the first time and yet the power of a cardboard box was the main theme of the first round. Maybe Amazon should follow their example for how they packed the boxes, but I digress. We still had another 20 minutes with the students. Well, thinking on our feet, Dr. Carrico said the second design could not have the cardboard boxes, and with groans the students obliged but were not too happy. After another 15 minutes a new wave of ideas formed and dropped with only one out of the four groups failing by only a hairline of a fracture. The idea the students decided was all about reducing speed: parachutes. Some used bags, some used balloons, the best team used a bag with a balloon inside: which made sure the parachute was kept open.

The Hamm School of Engineering started their first year of the Toy Adapt-a-thon. A week of modifying toys for children with motor disabilities to use accessibility buttons running from December 1 to 8th. Children learn The group led by Jackson Gallagher, Ben Pihl, through playing, so having many toys for a John Sammons, Cole Kitzenberg, and Nathan child to choose from is important.

Desmaris designed a tracked ATV. However, families of children with motor disabilities often have to consider that the accessibility buttons are between $50-$200. On top of that, the cost for toys that work with these buttons, can make a regular $15 at Target increase to $115, they also must be bought online, and often do not include favorite characters from new movies. The good news is student volunteers can take almost any battery powered toy and adapt it to work with the accessibility button for roughly $3 a toy. The $3 is covered through donations, making this a free service for children and their families and schools.

To help families in Bismarck/Mandan and surrounding communities we are offering to adapt toys for free for families and schools.

We can even repair toys that were already been adapted. We even have brand new, donated toys that we are giving away to children and their families for free!

The students presented their prototype designs at a poster session held at the end of the semester.

ECI 351 B RIDGE D ESIGN P ROJECT

Next was the younger crowd, making paper airplanes! I maybe should have thought that through a little bit better, but I have not heard of students using this new knowledge for mischief. A major hurdle for the paper airplanes was that none of the students knew how to make one on their own! Luckily, we had more volunteers than students and were able to help students make the paper airplanes. Once done, we traveled downstairs to the lunch area and the students took turns throwing the planes and measuring how far they went. Since making the airplanes took more time than planned, the lesson had to be shortened. The students were instructed to place two paperclips on their planes and see how that changed their distance. As the school

M ECHANICAL E NGINEERING D ESIGN This year nine senior mechanical engineering students divided into two groups focusing on the design of two tracked vehicles for use in the snow. The vehicles were conceived of and designed entirely by the students.

The group led by Ben Niemuth, Brett Thompson, David Ruiz, and Elizabeth Hershey designed a snow bike.

Civil Engineering students in ECI 351 and Construction Management students in CMT 321 worked together to design and construct wooden truss bridges that had to meet certain deflection criteria. Students were tasked to design, build, and test a truss bridge that span a 10 foot gap only using 2 × 2’s and 1/2in plywood.

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They had to design the bridge to not deflect more than L/400 (0.3in.) and L/800 (0.15in.) when loaded with three team members and just the professor, respectively. Students performed analysis of material strengths, influence lines, deflections using energy methods, and modeling using RISA to do the design work. Students successfully constructed bridges to satisfy project requirements.

Engineering Quarterly WINTER 2023 time this semester. Each of our degree programs has required technical electives. These are courses which are offered periodically on a rotation and are subjects which are the area of research interest and expertise for one of our faculty members. Here is the course description: Fundamentals of Antennas and Communication Electronics will use a hands-on approach to learn about and create communication circuits while learning about the theory and application. Additionally, the fundamentals of antennas, EMI/EMC, radiation patterns, directivity, and gain will allow students to understand and create simulations to validate basic PCB antenna design.

ROUGHRIDER B ONSPIEL 2022

By ANTHONY WALDENMAIER

E LECTRICAL E NGINEERING D ESIGN

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tips. This can be understood in the context of tensile stress (force per unit area) and ultimate strength. The ultimate strength of a material is the maximum value of tensile stress that a material can withstand.

An idealized model of an icicle presumes its homogeneity (constant density ρ0 ) and ascribes to it a regular conical geometry (circular cross-section in planes perpendicular to its axis of symmetry, and open-half-angle θ). (a) The ice lying below the imaginary surface at distance x from the tip is held in place by the tensile force exerted through the surface, which cancels its weight. (i) Compute the volume of ice lying within distance x from the tip. (ii) Determine the weight of this ice (W = ρ0 × Volume × g). (b) The force counter to the weight determined in (a) is distributed across the cross-sectional face of the icicle (at a distance x from the tip). Compute the tensile stress and verify that it is proportional to x.

Professor Anthony Waldenmaier’s Curling team: Alfredo Anthony and the Meatballs won the 2022 Roughrider Bonspiel on December 11th, 2022 this year at the Capital Curling Club in Bismarck.

Since the tensile stress increases with distance from the tip, so too does the likelihood of reaching or exceeding the ultimate tensile strength of the ice.

S ECRET S ANTA

By TOM VOLKMAN

Python is an object-oriented, easy-tounderstand interpreted programming language that can be used to write quick programming applications. It’s an ideal coding language for those who want to write do rapid development without having to have a deep understanding of advanced programming concepts. Python is widely popular due to many reasons:

On December 9, electrical engineering seniors held a poster session showcasing their first semester design projects in the Senior Design Center of the Hamm School of Engineering.

Maggie Kuhar and Derek Faul developed a device intended to help increase the independence and safety of blind individuals. The device is capable of navigating a given path while avoiding obstacles and uses an array of ultrasonic sensors in addition to a lidar sensor to detect obstacles and uses stepper motor positions to track pathing.

• It is Easy to Use: It is relatively easy to learn, making it a good first step in learning how to program.

Also on the team are two engineers from Bobcat and one from Terracon.

EE T ECHNICAL E LECTIVE : F UNDAMENTALS OF A NTENNAS AND C OMMUNICATION E LECTRONICS

By JERIKA CLEVELAND

P ROBLEMS TO TRY

• It has Simple Syntax: It is easy to read and understand, since it reads like English.

• It has a Thriving Community: Since it is an open-source language, anyone can use Python to code.

• It has Versatility: It can be used for many different uses; data manipulation, artificial intelligence, web development, game development, and more.

Here are some problems from our courses this semester that you might like to try. The solu- Question: Write a python application to create a Secret Santa list, which can be adapted tions can be found at the end of this issue. to any number of givers/receivers.

B ROKEN I CICLES ENR 304: VOLTAGE D IVIDER S IX S IGMA

By PATRICK KELLY

By TERRY PILLING

Fundamentals of Antennas and Communication Electronics is being offered as a Electrical Engineering technical elective for the first

The icicles that are found on the eaves of houses in the wintertime, as well as the stalactites found in subterranean caverns, tend to fracture nearer to their bases than to their

Write a simulation of a voltage divider circuit where the resistors are given resistor values within of 1%, 5%, and 10% tolerances.

The simulation should run a specified number of times with the resistor values randomized within the tolerance ranges and the voltage divider output placed into a histogram. Write a gnuplot script to show the resulting histogram.

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M ANDELBROT S ET

By TERRY PILLING

The Mandelbrot set has its origin in complex dynamics, a field first investigated by the French mathematicians Pierre Fatou and Gaston Julia at the beginning of the 20th century.

In the 1980’s, Benoit Mandelbrot worked at IBM’s Thomas J. Watson Research Center in Yorktown Heights, New York.

Because of his access to IBM’s computers, Mandelbrot was able to use computer graphics to create and display fractal geometric images, leading to his discovery of the Mandelbrot set in 1980. He showed how visual complexity can be created from simple rules.

The Mandelbrot set appeared on the cover of Scientific American in August 1985 and became prominent in the mid-1980s as a computer graphics demo on personal computers.

A complex number c is a member of the Mandelbrot set if, when starting with z0 = 0 and repeatedly applying the iteration: zn+1 = zn2 + c, the absolute value of zn remains bounded.

For example, for c = 1, the sequence is 0, 1, 2, 5, 26, . . . which tends to infinity → so 1 is not an element of the Mandelbrot set. On the other hand, for c = −1, the sequence is 0, −1, 0, −1, 0, . . . which is bounded → so −1 does belong to the set.

We can visualize this on a computer by taking every pixel of the screen and thinking of the (x, y) coordinates of the pixel as a point in the complex plane. We can use that complex point as our c in the above algorithm and iterate it a few times. If the value passes a given size we consider it as ‘divergent’ and if not we consider it as bounded. We make it more interesting by coloring the pixel according to how fast it becomes divergent. For example, if it is bounded (i.e. if it is a member of the Mandelbrot set) we color the pixel black, if it diverges past our threshold after

Engineering Quarterly WINTER 2023 one iteration it is a certain scale of gray, after two iterations a darker shade of gray, etc.

Here is an implementation of this algorithm, written in C, which creates a Portable Pixel Map (PPM) image and then uses imagemagick to convert it to a Portable Network Graphics (PNG) file that can be viewed with an image viewer. mandelbrot.c # i n c l u d e < s t d i o . h> # i n c l u d e < s t d l i b . h> # d e f i n e DIVERGE 2 . 0 i n t u s a g e ( char * ) ; i n t main ( i n t a r g c , char ** a r g v ) { i f ( a r g c != 8) return usage ( argv [ 0 ] ) ; d o u b l e xmin = a t o f ( a r g v [ 1 ] ) ; d o u b l e xmax = a t o f ( a r g v [ 2 ] ) ; d o u b l e ymin = a t o f ( a r g v [ 3 ] ) ; d o u b l e ymax = a t o f ( a r g v [ 4 ] ) ; int num_iterations = a t o i ( argv [ 5 ] ) ; i n t width = a t o i ( argv [ 6 ] ) ; FILE * f p = f o p e n ( a r g v [ 7 ] , "wb" ) ; d o u b l e dx = ( xmax−xmin ) / w i d t h ; i n t h e i g h t = ( ymax−ymin ) / dx ; int i , j , k ; d o u b l e x , y , u , v , U, V; f p r i n t f ( fp , " P6 \ n# M a n d e l b r o t , " ) ; f p r i n t f ( fp , " xmin=%l f , xmax=%l f , " , xmin , xmax ) ; f p r i n t f ( fp , " ymin=%l f , ymax=% l f " , ymin , ymax ) ; f p r i n t f ( fp , " n u m _ i t e r a t i o n s=%d \ n " , n u m _ i t e r a t i o n s ) ; f p r i n t f ( fp , "%d \ n%d \ n " , w i d t h , h e i g h t ) ; f p r i n t f ( fp , "%d \ n " , ( n u m _ i t e r a t i o n s < 256 ? 255 : num_iterations ) ) ; f o r ( j = 0 ; j < h e i g h t ; j ++) { y = ymax − j * dx ; f o r ( i = 0 ; i < w i d t h ; i ++) { x = xmin + i * dx ; u = 0.0; v = 0.0; f o r ( k = 1 ; k < n u m _ i t e r a t i o n s && ( u * u+v * v < DIVERGE ) ; k ++) { U = u*u − v*v + x ; V = 2* u * v + y ; u = U; v = V; } i f ( k >= n u m _ i t e r a t i o n s ) { char b l a c k [ ] = { 0 , 0 , 0 , 0 , 0 , 0 } ; f w r i t e ( black , 6 , 1 , fp ) ; } else { char c o l o r [ 6 ] ; c o l o r [ 0 ] = k >> 8 ; color [1] = k ; c o l o r [ 2 ] = k >> 8 ; color [3] = k ; c o l o r [ 4 ] = k >> 8 ; color [5] = k ; f w r i t e ( color , 6 , 1 , fp ) ; } } } f c l o s e ( fp ) ; return 0; } i n t u s a g e ( char * name ) { f p r i n t f ( s t d e r r , " Usage : %s <xmin > <xmax> <ymin > < ymax> < n u m _ i t e r a t i o n s > < w i d t h > < o u t . ppm > \ n " , name ) ; f p r i n t f ( s t d e r r , " Example1 : %s 0 . 2 7 0 8 5 0 . 2 7 1 0 0 0 . 0 0 4 6 4 0 0 . 0 0 4 8 1 0 1000 1024 p i c . ppm \ n " , name ) ; f p r i n t f ( s t d e r r , " Example2 : %s 0 . 2 7 0 9 8 6 0 . 2 7 0 9 9 0 0 . 0 0 4 8 0 4 0 . 0 0 4 8 0 7 1000 1024 p i c . ppm \ n " , name ) ; f p r i n t f ( s t d e r r , " C o n v e r t t o png u s i n g : \ n " ) ; f p r i n t f ( s t d e r r , " c o n v e r t − n o r m a l i z e p i c . ppm p i c . png \ nor c o l o r with \ n" ) ; f p r i n t f ( s t d e r r , " See h t t p : / / www. i m a g e m a g i c k . o r g / Usage / c o l o r _ m o d s \ n " ) ; return 1; }

By modifying the input parameters you can zoom in on various regions of the set. You might enjoy playing with the code to explore the beauty of this mathematical curiosity. You can also easily find colorful phone apps and online generators of the Mandelbrot set which allow you to select regions and zoom in smaller and smaller. I encourage you to try them! You might also want to check out the YouTube video youtu.be/ FFftmWSzgmk for an interesting discussion of the Mandelbrot Set and of Julia Sets in general.

C OMPUTATIONAL F LUID DYNAMICS

By ASSAL HADDAD

In Arabic slang, “like water” is used to describe an easy and simple concept or process.

A good example would be if one would want to describe how easy it is to share an image from Facebook to a friend on WhatsApp; one would say it is “like water”. Oddly, one would argue that fluid mechanics is definitely not “like water”. It is a subject where the entire

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basic knowledge of physics and mathematics is working together to describe how a drop of water decides to move. Although there is a feel of randomness when watching a waterfall or when someone spills a glass of water, it is actually the complete opposite. The whole scenario is almost predetermined where every drop of water has precisely one unique path to follow under the given circumstances.

In addition to being crucial, it is also exciting for engineers to mathematically describe a “random” natural phenomenon. It is very challenging to get as close as possible to the real thing, and it requires a deep understanding of every significant and insignificant variable that might affect the natural behavior.

Computational fluid dynamics (CFD) utilizes the computer capacity to run numerous calculations to solve the Navier-Stokes equations in 3D which provides, for example, engineers with an accurate description of streamlines around an airplane wing along with an estimation of the pressure variations.

However, such a project would be beyond the scope of a fluid mechanics undergraduate course and would also require certain specialized software and programming abilities which may not necessarily be required from civil and mechanical engineering students. Thus, in this Fall semester, fluid mechanics students were able to provide a mathematical description of a simple fluid problem of a jet of water spewing out of a hole in a tank that is being filled itself at a constant rate.

Relating the changes in the water level of the tank and the projectile shape of the water jet required understanding of mass balance concepts, Bernoulli’s concepts, and particle dynamics. The main challenge for students was to give a real-time feel to the dynamic system. The project required students to write a code using V-Python 3.2 that continuously prints the trail of water jet. The intended objectives by the end of the project were: 1. Visualizing the relation between the Bernoulli’s terms (mainly V2 /2g and Z) 2. Visualizing the relation between the continuity equation terms (Accumulation and influent and effluent flowrates) 3. Investigating the nonlinear effect of elapsed time on water height inside the tank, and the shape of the water projectile ejecting outside the tank 4. Understanding the complexity in modeling a water jet under a continuous domain of time (i.e., every drop of water will have different Vx once it leaves the opening); and realizing the value of simplifying continuous time into discrete time fragments (dt), which helps in visualizing the significance of integration 5. Designing an algorithm that continuously calculates a number of variables that progress in time within a loop that has a specified limit.

Students had fun writing their code after Professor Rodrigo da Costa Aparecido, who was assisting with the course, explained the basic building blocks of the V-Python software and walked them through the tricky parts of the coding process. Students were experiencing the gradual buildup of their models and

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visualizing how their models come to life and Secret Santa: Here is the Python code: start to look real. secretSanta.py import random m y L i s t = [ " Reagan " , " Ryan " , " Madison " , " T a y l o r " , " Lucy " , " G r a n t " , "Adam" ] l i s t C o u n t = len ( myList ) # Function d i s p l a y S a n t a L i s t def d i s p l a y S a n t a L i s t ( s a n t a L i s t , g i f t L i s t ) : f o r i n d e x i n range ( l i s t C o u n t ) : print ( f "{ s a n t a L i s t [ index ]} Secret Santa for { g i f t L i s t [ index ]} " ) # main f u n c t i o n d e f main ( ) : # C r e a t e two a r r a y s f o r s t o r i n g u n i q u e l i s t s santaList = [] giftList = [] # C r e a t e two l i s t s f o r name i n m y L i s t : s a n t a L i s t . a p p e n d ( name ) g i f t L i s t . a p p e n d ( name ) # randomly s h u f f l e both l i s t s random . s h u f f l e ( s a n t a L i s t ) random . s h u f f l e ( g i f t L i s t ) d u p l i c a t e = True # l o o p u n t i l t h e r e a r e no m a t c h e s i n t h e l i s t s w h i l e d u p l i c a t e == T r u e : duplicate = False random . s h u f f l e ( g i f t L i s t ) # Compare t h e l i s t s f o r i n d e x i n range ( l e n ( m y L i s t ) ) : i f s a n t a L i s t [ i n d e x ] == g i f t L i s t [ i n d e x ] : d u p l i c a t e = True displaySantaList ( santaList , giftList ) ;

This same technique can be used with any electric circuit, mechanical machine, or physical structure when the materials used have given manufacturing tolerances. You simulate the parameters of the resulting whole by randomizing the input values based on the tolerances. This allows you to optimize the product costs within given quality specifications.

# C a l l t h e main f u n c t i o n . main ( )

S TRIVE TO BE YOUR B EST

fluid.py

By TERRY PILLING

# Number o f s a m p l e s=n n =10 # h e i g h t 1 =h1 h1 =3 # h e i g h t 2 =h2 h2 =2 # Area o f t h e h o l e Ah = 0 . 2 # Area o f t h e t a n k At =1 # Water i n Qi =1 # Farthest splash f p = s q r t ( 2 * 9 . 8 1 * h1 ) * s q r t ( ( 2 * h2 ) / ( 9 . 8 1 ) ) # Equalibrium Height h f = ( ( Qi / Ah ) * * 2 ) / ( 2 * 9 . 8 1 ) T=0 w h i l e h1 >= 0 : vx= s q r t ( 2 * 9 . 8 1 * h1 ) t o t a l t i m e = s q r t ( ( 2 * h2 ) / ( 9 . 8 1 ) ) t o t a l x =vx * t o t a l t i m e mytank = box ( p o s = v e c t o r ( − 1 , . 5 * ( h2+h1 ) * 1 . 2 , 0 ) , l e n g t h =2 , h e i g h t = ( h1+h2 ) * 1 . 2 , w i d t h = . 0 1 ) m y w a t e r f u l l = box ( p o s = v e c t o r ( − 1 , h2 * . 5 , 0 ) , l e n g t h =2 , h e i g h t =h2 , w i d t h = . 0 1 , c o l o r = c o l o r . b l u e ) h o r i z o n t a l a x i s = curve ( vec ( −2 ,0 ,0) , vec ( ( t o t a l x *1.2) +2 ,0 ,0) ) rat e (100) w a t e r = s p h e r e ( p o s = v e c ( 0 , h2 , 0 ) , r a d i u s = 0 . 1 , c o l o r = c o l o r . b l u e , m a k e _ t r a i l = True , r e t a i n = ( n + 1 ) ) mywater = box ( p o s = v e c t o r ( − 1 , h2 + ( h1 / 2 ) , 0 ) , l e n g t h =2 , h e i g h t =h1 , w i d t h = . 0 1 , c o l o r = c o l o r . b l u e ) t =0 dt= t o t a l t i m e / n T=T+ d t while t < t o t a l t i m e : w a t e r . p o s . x=vx * t w a t e r . p o s . y=h2 − 0 . 5 * 9 . 8 1 * ( t * * 2 ) rat e (100) dt= t o t a l t i m e / n t=t+dt Vh= ( Qi − (Ah * vx ) ) / At dh=Vh * d t print ( " F i n a l Height= "+ hf ) p r i n t ( " h1= " + h1 ) p r i n t ( " Change i n H e i g h t = " + dh ) i f Qi <= 0 : p r i n t ( " Time= " + T ) print ( " F a r t h e s t Splash = "+ fp ) h1=h1+dh mywater . v i s i b l e = F a l s e water . c l e a r _ t r a i l ( )

S OLUTIONS TO P ROBLEMS Here are the solutions to the problems that were presented earlier in this issue.

Broken Icicles: 3

(i) Volume of cone of height x is πx3 tan2 (θ) Think for circular discs dV = πR2 dx, where R = x tan(θ) 3

(ii) W = πρ03gx tan2 (θ) ρ0 gx W W Tensile stress = Area = πR 2 = 3 Since tensile stress increases with x, the longer icicles break and they break far from the tip (near to the base).

ENR 304: Voltage Divider Six Sigma The following code will perform a given numI remember one time in elementary school ber of trials on voltage dividers with given we had “Track and Field Day” where a bunch resistor values and tolerances and output the of schools got together to compete in various resulting voltage divider voltage. running and jumping competitions. The parents were there and it was before the school divider.c age where kids are separated into teams. Everybody competed in every event. It is more # i n c l u d e < s t d i o . h> # i n c l u d e < s t d l i b . h> about the fun and exercise in the sun rather # i n c l u d e < t i m e . h> i n t u s a g e ( char * name ) ; than about one school beating another. Obi n t main ( i n t a r g c , char ** a r g v ) { i f ( a r g c != 6 ) return usage ( argv [ 0 ] ) ; viously it was still competitive and everyone s r a n d ( t i m e (NULL) ) ; f l o a t R1 = a t o f ( a r g v [ 1 ] ) ; wanted to come home with victory ribbons in f l o a t R2 = a t o f ( a r g v [ 3 ] ) ; i n t dR1 = a t o i ( a r g v [ 2 ] ) ; an event or two. i n t dR2 = a t o i ( a r g v [ 4 ] ) ; int T r i a l s = a t o i ( argv [ 5 ] ) ; Anyway, I had a best friend at the time, f l o a t v o l t a g e , s i g n , dr1 , d r 2 ; int stats [101]; Calvin, who I did everything with. To this f o r ( i n t i = 0 ; i < 1 0 1 ; i ++) s t a t s [ i ] = 0 ; f o r ( i n t i = 1 ; i <= T r i a l s ; i ++) { day I am convinced that Calvin had the fun/ / d r 1 i s +/− a p e r c e n t a g e o f R1 s i g n = ( r a n d ( ) %2) ? 1 . 0 : − 1 . 0 ; niest sense of humor of anyone I ever met – d r 1 = s i g n * R1 * ( ( f l o a t ) ( ( r a n d ( )%dR1 ) + 1 ) ) / 1 0 0 . 0 ; / / d r 2 i s +/− a p e r c e n t a g e o f R2 s i g n = ( r a n d ( ) %2) ? 1 . 0 : − 1 . 0 ; and that says something since we were only d r 2 = s i g n * R2 * ( ( f l o a t ) ( ( r a n d ( )%dR2 ) + 1 ) ) / 1 0 0 . 0 ; / / input voltage is 1 something like 8 years old! The problem was / / output voltage fraction / / comes f r o m r e s i s t o r v a l u e s that Calvin was asthmatic and was notoriously v o l t a g e = ( R2+ d r 2 ) / ( R1+ d r 1 +R2+ d r 2 ) ; s t a t s [ ( i n t ) (100* v o l t a g e ) ]++; bad at sporting events as a result. I remember } f o r ( i n t i = 0 ; i < 1 0 1 ; i ++) it was time for the ‘high jump’ competition p r i n t f ( " %0.2 f \ t %0.2 f \ n " , ( f l o a t ) i / 1 0 0 . 0 , ( ( f l o a t ) stats [ i ]) /(( float ) Trials ) ) ; and I could tell that it terrified Calvin. He return 0; } couldn’t jump very high. The way the comi n t u s a g e ( char * name ) { f p r i n t f ( s t d e r r , " Usage : %s R1 dR1 R2 dR2 T r i a l s \ n " , petition worked was that there was a sand pit name ) ; f p r i n t f ( s t d e r r , " R1 , R2 a r e t h e r e s i s t o r n o m i n a l (we weren’t old enough yet to high jump in values \ n" ) ; f p r i n t f ( s t d e r r , " dR1 , dR2 a r e t h e t o l e r a n c e s . I . e . the technical way where you back flip on to 5%% i s 5 \ n " ) ; f p r i n t f ( s t d e r r , " T r i a l s i s t h e number o f random a mat) and the goal was just to hop from one t r i a l s \ n" ) ; return 1; side over the bar into the sand on the other } side. All the students lined up and, one after the other, they would run to the bar and If you run the program with two 100Ω hop over it. If you knocked the bar down you resistors with 1%, 5%, and 10% tolerance would run back around while the referees revalues respectively and plot the histogram placed the bar and you would run at it again. with the following Gnuplot script.

If you knocked it down three times you would be eliminated. After the entire line of kids divider.gnuplot had finished, the referees would raise the bar a notch and go through the line of kids again s e t t e r m x11 s e t t i t l e " Voltage Divider Output as a F r a c t i o n of and this would continue until only one kid was Input Voltage " s e t xlabel " Output Voltage " left. The last three standing would be awarded set ylabel " F r a c t i o n of T r i a l s " set grid the first, second, and third place ribbons for set x t i c s 0.01 s e t x t i c s r o t a t e by −45 the event. s e t s t y l e f i l l s o l i d border −1 s e t key t o p r i g h t As I said, Calvin was terrified, and with s e t xrange [ 0 . 4 : 0 . 6 ] good reason. Being his best friend I knew that p l o t " d i v i d e r 1 . d a t " u s i n g 1 : 2 w i t h b o x e s t i t l e "1% tolerance " ,\ he was going to do miserably. He could barely " d i v i d e r 5 . d a t " u s i n g 1 : 2 w i t h b o x e s t i t l e "5% tolerance " ,\ run and he certainly couldn’t jump very high. " d i v i d e r 1 0 . d a t " u s i n g 1 : 2 w i t h b o x e s t i t l e "10% tolerance " However, even I was surprised by how poorly he did. The bar was on the first setting when The histogram of the output voltages are as he knocked it down. This was the easiest follows level! Sort of the ‘warm-up’ level where all of the kids were expected to easily clear it. A

VOL.V. . . No.2

confidence booster you might say. And Calvin knocked it down. I could see his face growing red with humiliation as he lumbered back around for his second attempt. He knocked it down again! On his way back around for his final attempt I could see a fear and determination in his eyes. He needed to clear the bar. This day would haunt him forever if it ended in this worst kind of humiliation. To fail at the easiest setting with everyone in the world watching... He knocked it over again.

He was eliminated. He slowly walked to the sidelines as the referees replaced the bar. Up to that point he was the only one who even knocked the bar down once, let alone being eliminated. How horrible he must have felt at that moment.

A few students later and it was my turn. I knocked the bar down. I could see my mom on the sidelines and the confusion that ap-

Engineering Quarterly WINTER 2023 peared on her face. Did my foot snag on something? She must have thought. I ran back around and knocked it down yet again! Now she was really confused. I was a little monkey at that age and she knew that jumping over that measly height was a triviality for me. On my final attempt I knocked it over yet again and was eliminated.

I walked over to my mom and she, although confused, gave me a hug and said, “don’t worry, it’s okay, you’ll do better next time.” I then wandered over to Calvin who was standing with his mom. “I got eliminated,” I said. “I know,” he replied, “me too.

You want to go get a coke from the concession stand?” “Ya”, I smiled, “let’s go!” The rest of the day was a bunch of fun. Calvin’s humor had returned in full force and he forgot all about the traumatic humiliation of the high jump event.

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Calvin now manages a farm implement store in my home town and is happily married with three wonderful kids. I don’t think he even remembers that Track and Field day let alone thinking of it as a failure. As for me? I have thought about that day sometimes. For me, one of the proudest successes in my early life was losing that high jump competition.

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VOL.V. . . No.2

Engineering Quarterly WINTER 2023

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