OpenLLM-France/wikimedia huggingface dataset:
# Mechatronics II

Welcome to the Home page for Mechatronics II
In this course we will discuss 3Ø (three-phase) devices ( i.e 3Ø Transformers and 3Ø Induction Motors ). At the end of this course the student is expected to be familiar with the Principles of 3Ø devices and their application in real life.
You are advised to read carefully through given material and attempt all quiz/questionnaires in this course and don't forget to follow necessary safety code that will be outlined in this course. We hope you will enjoy this major course in Electrical Engineering.

## Course Outcomes

At the end of this course the student is expected to be comfortable with the following:
* Basic Principles of Insulators
* First Principles of 3Ø Transformers
* Temperature Rise in 3Ø Transformers
* First Principles of 3Ø Induction Motors
* Special Machines/Motors
* Common Machines Faults & Failures

## Prerequisites

The following courses are considered important for the student to be at ease with material that will be covered in this course:
* Mechatronics
* Alternating Current Circuits

## Resources

Wikiversity has a respectable body of content related to this course, you are advised to use the resources wisely to achieve your success. This course includes a formula sheet that can help you remember important Formulae and principles. Do not rely on the formula sheet entirely without understanding course material.

## Organization

This course consists of:
* 10 Lessons → [ 10 weeks ]
* 1 Quiz Test → [ 1 Day ]
* 1 Laboratory Assignment → [ 1 week ]
All the above Span about 11 weeks. Plan your time wisely, by starting a journal and track your progress. If you work consistently and keep to your planned Study Time, you will Do Very well in this course.
Here are some of the resources available to Help you understand and make better used of this personal Learning Experience:
* History of free learning
* Learning by doing
* How to use wiki technology as a free learner

## Lessons

* Introduction
* Review of 1ɸ Electrical Machines
* 3Ø Transformer: Construction & Tests
* 3Ø Transformer: Tap Changing; Connection & Efficiency
* 3Ø Transformer: Temperature Rise
* Electrical Insulators
* 1Ø Induction Motor (Review)
* 3Ø Induction Motor: Equivalent Circuits & Motor types
* 3Ø Induction Motor: Circle Diagrams; Bracking & Speed Control
* Special Machines
* Electrical Machines: Faults & Failures
* Electrical Machines II - Lab1
# Mechanics of materials/Problem set 4
## Problem 4.1

P3.23, Beer 2012
On our honor, we did this problem on our own, without looking at the solutions in previous semesters or other online solutions.

### Problem Statement

Under normal operating conditions a motor exerts a torque of magnitude $T_{F}$ =1200 lb*in. at F. $r_{D}$ =8in., $r_{G}$ =3in., and the allowable shearing stress is 10.5 ksi in each shaft.

### Objective

Determine the required diameter of (a) shaft CDE, (b) shaft FGH.

### Solution
#### Step 1

FBD

#### Step 2

We can write an equilibrium equation: The moment about the center point D.
$\sum M_{D}=0=T_{E}-F(r_{D})$
$\Rightarrow F={\frac {T_{E}}{r_{D}}}$
FBD

#### Step 3

We can write an equilibrium equation: The moment about the center point G.
$\sum M_{G}=0=T_{F}-F(r_{G})$
$\Rightarrow F={\frac {T_{F}}{r_{G}}}$
(a)
FBD

#### Step 4

Now we set the two Forces (F) equal to each other and solve.
${\frac {T_{E}}{r_{D}}}={\frac {T_{F}}{r_{G}}}\Rightarrow T_{E}={\frac {T_{F}*r_{D}}{r_{G}}}={\frac {1200lb*in*8in}{3in}}=3200lb*in$

#### Step 5

Solve $\tau _{max}$
$\tau _{max}={\frac {T_{E}*C_{D}}{J}}\Rightarrow C_{D}={\sqrt[{3}]{\frac {2T_{E}}{\pi \tau _{max}}}}={\sqrt[{3}]{\frac {2*3200lb*in}{\pi 10.5*10^{3}{\frac {lb}{in^{2}}}}}}=0.58in$

#### Step 6

Solve for the diameter of shaft CDE
$d_{D}=2*C_{D}=2*0.58in=1.158in$
(b)

#### Step 7

FBD

#### Step 8

Solve $\tau _{max}$
$\tau _{max}={\frac {T_{F}*C_{F}}{J}}\Rightarrow C_{F}={\sqrt[{3}]{\frac {2T_{F}}{\pi \tau _{max}}}}={\sqrt[{3}]{\frac {2*1200lb*in}{\pi 10.5*10^{3}{\frac {lb}{in^{2}}}}}}=0.417in$

#### Step 9

Solve for the diameter of shaft FGH
$d_{F}=2*C_{F}=2*0.42in=0.835in$

## Problem 4.2

P3.25, Beer 2012 On our honor, we did this problem on our own, without looking at the solutions in previous semesters or other online solutions.

### Problem Statement

The two solid shafts are connected by gears as shown and are made of steel for which the allowable shearing stress is 8500 psi. A torque of magnitude $T_{C}$ =5 kip*in. is applied at C and the assembly is in equilibrium.

### Objective

Determine the required diameter of (a) shaft BC, (b) shaft EF.

### Solution
#### Step 1

First sum the moments around gears A and E
$\sum M_{A}=F_{A}*R_{C}+T_{C}$
$\sum M_{D}=F_{D}*R_{F}+T_{F}$
Solve for F
$F={\frac {T}{R}}$

#### Step 2

Sum the Forces
$\sum F=0=F_{C}+F_{F}={\frac {T_{C}}{R_{A}}}+{\frac {T_{F}}{R_{E}}}$

#### Step 3

Solve for $T_{F}$
$T_{F}={\frac {-T_{C}*R_{E}}{R_{A}}}={\frac {-5kipin*2.5in}{4in}}=-3.125kip*in$
The magnitude of $T_{F}$ = 3.125 kip*in

#### Step 4

Use the formula for $\tau _{max}$ to solve for the radius
$\tau _{max}={\frac {T*r}{J}}={\frac {2*T}{\pi *r^{3}}}$
$r^{3}={\frac {2*T}{\pi *\tau _{max}}}$
$r=({\frac {2*T}{\pi *\tau _{max}}})^{1/3}$

#### Step 5

Input the Given values into the equation for the radius
$d_{C}=2*r_{C}=2*({\frac {2*T_{C}}{\pi *\tau _{max}}})^{1/3}=2*({\frac {2*5000lb*in}{\pi *8500psi}})^{1/3}=1.44in$
$d_{F}=2*r_{F}=2*({\frac {2*T_{F}}{\pi *\tau _{max}}})^{1/3}=2*({\frac {2*3125lb*in}{\pi *8500psi}})^{1/3}=1.233in$
# Volcanoes/Campi Flegrei

"Campi Flegrei [is] an active four-mile-wide [6.4 kilometer wide] sunken volcano."
"The Campi Flegrei caldera is a supervolcano [as outlined in the image on the right]. Although there’s no picture-postcard volcanic cone, hidden beneath the seemingly placid landscape lies a volcano of immense power. While a new eruption here would be more likely to result in the creation of another Vesuvius-like cone, the worst-case scenario could see it obliterating much of life in Europe."
The image on the right shows the Campi Flegrei caldera circled as a supervolcano relative to Mount Vesuvius, also circled and labeled.

## Eruptions

"The last time the ground gave way like this, 39,000 years ago when the caldera was formed, it created the cliffs that the postcard town of Sorrento stands on now – volcanic deposits over 300 ft [100 m] deep. If the same kind of eruption happened today, this part of Italy could cease to exist, and the ash clouds would blot out the Sun and lower the Earth’s temperature. Life in the UK as we know it would end. We would lose our livestock, crops and three-quarters of our plant species, plunging us into a new dark age of rioting, starvation and perpetual winter."

## Volcanic activity

"Right now we may well be in another period of uplift. If it occurs as before, we might expect another 60 years’ worth of unrest, and possible earthquakes and eruptions, with two or three more episodes and uplift to occur in the next ten years. We have to presume we have a few more decades of unrest, and if this is going to be the case, then we have to get more data about the volcano now."

## Volcanism

Def. any remnants "of the natural phenomena and processes associated with the action of volcanoes, geysers and fumaroles", especially any remnants of past volcanic activity, are called volcanism.
The image on the right from space of Campi Flegrei shows multiple volcanic cones and crater lakes from the past volcanism.
The second image down on the right is a trachytic dome formed from a lava flow from Solfatara.
The third image down on the right is the massive tuff of Monte Gauro.
Monte di Procida in the fourth image down on the right is a volcanic remnant of Campi Flegrei.
Collina dei Camaldoli, the fifth image down on the right, apparently originated about 35,000 b2k as a result of violent eruptions across Campi Flegrei.
The sixth image down on the right shows Monte Nuovo, a relatively recent cinder cone in the caldera of Campi Flegrei.
The image on the left shows relative relief around Campi Flegrei. This emphasizes that most or all of the relief is due to remnants of volcanic activity. Some of these features are shown in the images on the right.

## Hypotheses

* The most recent supervolcano eruption of Campi Flegrei left a dust layer in the Greenland ice cores.
# Volcanoes, list/Mount Cotopaxi
## Location and Basic Facts

Mount Cotopaxi is known as a stratovolcano. LOCATION:Ecuador, in South America, near the "Galapagos" and " Peru" Basic Info: It has a width at its base of about 23 kilometers and about "14 miles". It has one of the few equatorial glaciers on our world, which starts at the height of 5,170 meters(16,400 ft). The mountain is clearly visible on the skyline from "Quito" a city near Ecuador. It is part of the chain of volcanoes that circles the Pacific ocean called and as known as the Pacific Ring of Fire. It is an explosive and currently active volcano. Mount Cotopaxi is the highest volcano in Ecuador at its height at 19,348 feet which is about 5,879 meters. It is the most visited national park in the entire Ecuador. Cotopaxi is a seduction zone kind of volcano. The rocks melt and become lava inside of Mount Cotopaxi. It is a volcano with a tall shape which is called a "Composition" volcano. Range/Region: Andes Range/Region: Ecuador Andes Latitude: -0.680556 Longitude: -78.437778 Difficulty: Basic Snow/Ice Climb

## After Effects

The last time it erupted was in 2015.The last official eruption of Mt Cotopaxi occurred in 1940. There was some activity in 1975, but not enough to warrant the term "eruption". It caused ashes and mudflows and disaster. Lots of people died not because of the lava impact. It was because of the dirty water, air, and the food that has been polluted more than 100 Hours on total. More people died from pollution than the impact of the volcano. It caused starvation for over four months, and it killed almost 4/5 percentage of the people which is 80% of the people got injured, or killed. Cotopaxi's most violent eruptions occurred in the years 1744, 1768, and 1877. In the 1877 eruption pyroclastic flows descended all five sides of the mountain, with lava traveling more than 100 km into the Pacific Ocean and western Amazon basin draining the valley. There was a major eruption in 1903 through 1904, and some minor activity in 1942 as well as 1975 but it did not produce any major events. In the most recent case, fumarolic activities and sulfuric emissions increased and ice around the inside and on the southeastern side of the cone started to slowly and quietly melt down. The eruptions caused great damage but it also caused global damage. It has a widespread damage.

## Deaths and the Lives being taken

During the violent eruptions in 1904, it killed approximately 500 people. It injured about 350 people, either burned or polluted in the respiration system or crushed. The people died slowly, when they interact with the air, food, and water. It killed 500 people, and hurt or injured 350 people. This is all approximately, but it killed lots of people.
# Volcanoes, list/Oshima

The volcano on Oshima, Japan is a stratovolcano, which is the most common. A stratovolcano, or a composite volcano, is made of alternating layers of lava and pyroclastic material. Lava is molten rock above the surface, and pyroclastic material is molten lava that hardens while soaring through the air. There was a landslide, and the part that slid in the ocean could have caused the tsunami. The volcano is now horseshoe shaped. The summit collapsed, and was caused by a lot of ash on the volcano.

## The Oshima Boom

The volcano on Oshima, Japan erupted on 1741, and due to the eruption, a tsunami occurred. The stratovolcano, which is the most common,is now dormant. During the 1741 eruption, it revealed two types of ash.

## The Kinds of Ash

On January 22 to May 18,1742, the volcano erupted. The volcano was an explosive volcano, and black and grayish white ash fell down on Matsume,with about 10 cm in thickness; the Oshima Peninsula, the Tsugara district, which both also received about 10 cm of ash; and fell on the Oshima Peninsula once again on May 18 with 20-30 cm of ash. The black ash was basaltic, and the light gray ash was andestic ash.

## Tsunami Causes

There was an eruption in August 29, 1741 simultaneously a earthquake (m>7.5) is estimated to have occurred in the sea bottom near Ōshima, which generated a destructive tsunami and triggered a sector collapse of the volcanic body of Nishiyama.
http://agris.fao.org/agris-search/search.do?recordID=AV20120138291
# Volcanoes, list/Mount Unzen

Mount Unzen lies in Kyushu, a small island in Japan. It is a composite volcano, also known as a stratovolcano. It is a cluster of overlapping volcanoes instead one by itself. There have been many disastrous eruptions from this volcano, it is currently active. Its most recent eruption was in 1991. Its explosions are usually explosive. Unzen’s full name is Unzen-dake. This volcano got its name from all the hot springs around it. “Unzen” means hot springs and “–dake” means peak. Basically, Unzen-dake means hot spring mountain. This volcano is not blamed for erupting. After all, it is on the Ring of Fire. Mount unzen is located in japan and it erupted in 1792 and it killed 15,000 people and that eruption was one of the most deadlest eruptions in japan

## 1792…What Happened?

There was a rumbling sound in the distance. The people of Kyushu trembled in fear. Was it an earthquake? What was it? BOOOOM!! Mount Unzen erupted violently. The worst was not over. Suddenly, an earthquake shook Kyushu. The earthquake has caused an avalanche from Mount Mayuyama! It was collapsing on people! Then there was a tsunami! Kyushu was at its worst day. The whole thing was like a Rube Goldberg to destroy Kyushu. The volcanic eruption triggers an earthquake, which caused a lava dome collapse, which made a tsunami. In total, there were 15,000 deaths! This eruption also lead to mudslides because it was so big and deadly. Mount Unzen also erupted in 1919 and this volcano is still active till this day.

## What Came Out?

This deadly eruption bursted with pyroclastic material. It was strong enough to create an earthquake so the type of pyroclastic material must’ve been large. According to a website, the volcano was shooting out volcanic bombs and volcanic blocks. There was some volcanic ash but not a lot.

## Formation of Mount Unzen

Mount Unzen is super dangerous. How did it even form? This is a hard question sometimes because volcanoes form and process underground, making it difficult to predict and understand. According to Universe Today, “It is believed that this volcano originated as a result of crustal faulting which eventually formed a graben, or a depressed stretch of land typically due to tensional forces and crustal faulting".

## Appearance and Elevation

Mount Unzen is a huge cluster of cone-shaped volcanoes. Its highest peak is Mount Fugen-dake. It measures 1,486 meters. The second highest is Heisei Shinzan which measures at 1,475 meters. Mount Unzen has many lava domes, such as the one that collapsed in 1792.

## Everyday Mount Unzen

Nowadays, Mount Unzen is available for tour. It’s hot springs make it a lovely resort. There are many wilderness sights to see. There are also many spas, making Unzen the perfect place for calming down and relaxing.
# Volcanoes/Campi Flegrei/Quiz

Campi Flegrei is an article and a lecture from the school of geology about the volcano Campi Flegrei.
You are free to take this quiz based on Campi Flegrei at any time.
To improve your score, read and study the lecture, the links contained within, listed under See also, External links, and in the {{geology resources}} template. This should give you adequate background to get 100 %.
As a "learning by doing" resource, this quiz helps you to assess your knowledge and understanding of the information, and it is a quiz you may take over and over as a learning resource to improve your knowledge, understanding, test-taking skills, and your score.
Suggestion: Have the lecture available in a separate window.
To master the information and use only your memory while taking the quiz, try rewriting the information from more familiar points of view, or be creative with association.
Enjoy learning by doing!

## Hypotheses

* There are approximately as many volcanoes per 10° of longitude and 5° of latitude as there are glaciers.
* The volcanoes on Earth have the same or similar origin as those on Io.
# Nonlinear finite elements/Deviatoric and volumetric stress
## Deviatoric and volumetric stress

Often it is convenient to decompose the stress tensor into volumetric and deviatoric (distortional) parts. Applications of such decompositions can be found in metal plasticity, soil mechanics, and biomechanics.

### Decomposition of the Cauchy stress

The Cauchy stress can be additively decomposed as
    ${\boldsymbol {\sigma }}=\mathbf {s} -p~{\boldsymbol {\mathit {1}}}$
where $\mathbf {s}$ is the deviatoric stress and $p$ is the pressure and
    ${\begin{aligned}p&=-{\frac {1}{3}}~{\text{tr}}({\boldsymbol {\sigma }})=-{\frac {1}{3}}~{\boldsymbol {\sigma }}:{\boldsymbol {\mathit {1}}}\\\mathbf {s} &={\boldsymbol {\sigma }}+p~{\boldsymbol {\mathit {1}}}~;~~\mathbf {s} :{\boldsymbol {\mathit {1}}}={\text{tr}}(\mathbf {s} )=0\end{aligned}}$
In index notation,
    ${\begin{aligned}p&=-{\frac {1}{3}}~\sigma _{ii}\\s_{ij}&=\sigma _{ij}-{\frac {1}{3}}~\sigma _{kk}~\delta _{ij}\end{aligned}}$

### Decomposition of the 2nd P-K stress

The second Piola-Kirchhoff stress can be decomposed into volumetric and distortional parts as
    ${\boldsymbol {S}}={\boldsymbol {S}}'-p~J~{\boldsymbol {C}}^{-1}$
where
    ${\begin{aligned}p&=-{\frac {1}{3}}~J^{-1}~{\boldsymbol {S}}:{\boldsymbol {C}}\\{\boldsymbol {S}}'&=J~{\boldsymbol {F}}^{-1}\cdot \mathbf {s} \cdot {\boldsymbol {F}}^{-T}~;~~{\boldsymbol {S}}':{\boldsymbol {C}}&=0\end{aligned}}$
# Nonlinear finite elements/Homework11/Solutions/Problem 1/Part 10
## Problem 1: Part 10: Discrete evolution equations

Discretize the equations for ${\dot {\mathbf {e} }}^{p}$ (equation 1), ${\dot {\alpha }}$ (from part 1), and ${\dot {T}}$ (from part 2) using Forward Euler.
The relevant equations are
    ${\begin{aligned}f_{\boldsymbol {\sigma }}&={\sqrt {\cfrac {3}{2}}}~\mathbf {n} \\{\dot {\boldsymbol {\varepsilon }}}^{p}&={\dot {\gamma }}~f_{\boldsymbol {\sigma }}={\sqrt {\cfrac {3}{2}}}~{\dot {\gamma }}~\mathbf {n} \\{\dot {\alpha }}&={\sqrt {\cfrac {2}{3}}}~{\dot {\gamma }}~{\cfrac {{\boldsymbol {\varepsilon }}^{p}:f_{\boldsymbol {\sigma }}}{\lVert {\boldsymbol {\varepsilon }}^{p}\rVert _}}={\dot {\gamma }}~{\cfrac {{\boldsymbol {\varepsilon }}^{p}:\mathbf {n} }{\lVert {\boldsymbol {\varepsilon }}^{p}\rVert _}}\\{\dot {T}}&={\cfrac {\chi ~{\dot {\gamma }}}{\rho ~C_{p}}}~{\boldsymbol {\sigma }}:{\frac {\partial f}{\partial {\boldsymbol {\sigma }}}}={\sqrt {\cfrac {3}{2}}}~{\cfrac {\chi ~{\dot {\gamma }}}{\rho ~C_{p}}}~{\boldsymbol {\sigma }}:\mathbf {n} ={\sqrt {\cfrac {3}{2}}}~{\cfrac {\chi ~{\dot {\gamma }}}{\rho ~C_{p}}}~\lVert \mathbf {s} \rVert _\end{aligned}}$
A Forward Euler time discretization gives us
    ${\begin{aligned}{\boldsymbol {\varepsilon }}_{n+1}^{p}&={\boldsymbol {\varepsilon }}_{n}^{p}+{\sqrt {\cfrac {3}{2}}}~\Delta t~{\dot {\gamma }}_{n}~\mathbf {n} _{n}\\\alpha _{n+1}&=\alpha _{n}+\Delta t~{\dot {\gamma }}_{n}~{\cfrac {{\boldsymbol {\varepsilon }}_{n}^{p}:\mathbf {n} _{n}}{\lVert {\boldsymbol {\varepsilon }}_{n}^{p}\rVert _}}\\T_{n+1}&=T_{n}+{\sqrt {\cfrac {3}{2}}}~{\cfrac {\chi ~\Delta t~{\dot {\gamma }}_{n}}{\rho _{n}~C_{p}}}~\lVert \mathbf {s} _{n}\rVert _\end{aligned}}$
or
    ${\begin{aligned}{\boldsymbol {\varepsilon }}_{n+1}^{p}&={\boldsymbol {\varepsilon }}_{n}^{p}+{\sqrt {\cfrac {3}{2}}}~\Delta \gamma ~\mathbf {n} _{n}\\\alpha _{n+1}&=\alpha _{n}+\Delta \gamma ~{\cfrac {{\boldsymbol {\varepsilon }}_{n}^{p}:\mathbf {n} _{n}}{\lVert {\boldsymbol {\varepsilon }}_{n}^{p}\rVert _}}\\T_{n+1}&=T_{n}+{\sqrt {\cfrac {3}{2}}}~{\cfrac {\chi ~\Delta \gamma }{\rho _{n}~C_{p}}}~\lVert \mathbf {s} _{n}\rVert _\end{aligned}}$
# What Matters/Play
## Play

Skipping, jumping, dancing, singing, fiddling, exploring, imagining, pretending, fantasizing, joking, doodling, visiting, and just goofing off. This is fun, this is play, this is OK. Arnold Toynbee advises: "The supreme accomplishment is to blur the line between work and play." May Sarton suggests: "Each day, and the living of it, has to be a conscious creation in which discipline and order are relieved with some play and pure foolishness." Choose how much adventure and excitement you wish to enjoy.
Increase or decrease the time you spend playing to maintain a temperate balance in your life. Although play often involves risk, if your activities become hurtful to anyone it is no longer play.

### Assignment:

* Complete the Wikiversity course playing.
* Take time to enjoy playing.
* Find somethings that makes you laugh out loud. Enjoy laughing out loud.

### Suggestions for further reading:

* Brown, Stuart; Christopher Vaughan (2010). Play: How it Shapes the Brain, Opens the Imagination, and Invigorates the Soul. Avery Trade. pp. 240. ISBN 978-1583333785.
* Iggulden, Conn; Hal Iggulden (2006). The Dangerous Book for Boys. HarperCollins. pp. 294. ISBN 0-00-723274-8.
* (Evaluate: Exuberant Animal: The Power of Health, Play and Joyful Movement )
* (Evaluate: The Ball )
# What Matters/Pleasure
## Pleasure

Indulge yourself in pure pleasure! Go ahead and pamper yourself. Get a massage, a manicure, or a facial, enjoy a hot bath a bubble bath or a whirlpool bath, eat chocolate, drink wine, or make passionate love with your consenting partner.
Increase or decrease the time you spend pampering yourself to maintain a temperate balance in your life.
# What Matters/Progeny and Legacy
## Progeny and Legacy

Perhaps the purpose of life is to reproduce. This keeps the species alive and allows subsequent generations to adapt, improve, and evolve. At the end of the 20th century, based upon insight gleaned from the gene-centered view of evolution, biologists George C. Williams, Richard Dawkins, David Haig, among others, conclude that if there is a primary function to life, it is the replication of DNA and the survival of one's genes. Life exists to replicate and perpetuate life.
However, raising a child requires significant resources, including: time, social, financial, and environmental resources. Planning can help assure adequate resources are available to provide each child with a good opportunity to flourish.
Marital status and the happiness of your marriage has a significant effect on your overall happiness.
Legacy refers to anything handed down from the past. You may have inherited wealth, land, a family business, family traditions, skills training, or heirlooms from your parents. You may also have inherited debt, abuse, alcoholism, intolerance, bad habits, or any number of other liabilities. Work to pass on a positive legacy and resolve to end the cycle of any negative legacy prevalent in your family.

### Assignment:

* Engage in careful family planning at appropriate stages of your life.
* If you decide to have children, devote adequate attention to their care, protection, and upbringing. Be responsible parents.
* Identify the legacy you have inherited. Evaluate each element of that legacy as beneficial, neutral, or a liability.
* Plan the legacy you wish to pass on. Strive to make it entirely beneficial.

### Suggestions for further reading:

* Albom, Mitch (2002). Tuesdays with Morrie: An Old Man, a Young Man, and Life's Greatest Lesson. Broadway. pp. 192. ISBN 978-0767905923.
* Pausch, Randy (2008). The Last Lecture. NY: Hyperion. pp. 176. ISBN 978-0739495049.
* Smith, Emily Esfahani (January 10, 2017). The Power of Meaning: Crafting a Life That Matters. Crown. pp. 304. ISBN 978-0553419993.

### References:

* ↑ David Seaman (2005). The Real Meaning of Life. New World Library. ISBN 1577315146. Page 126
* ↑ Richard Dawkins (1976). The Selfish Gene. Oxford University Press. ISBN 019857519X.
* ↑ Richard Dawkins (1995). River out of Eden. New York: Basic Books. ISBN 0-465-06990-8.
* ↑ Does Marriage Help Your Health and Happiness?, By John M. Grohol, PsyD World of Psychology, April 17, 2010