diff --git a/content/Dirak δ-function (lec 21).md b/content/Dirak δ-function (lec 21).md index 948a766..bd115e7 100644 --- a/content/Dirak δ-function (lec 21).md +++ b/content/Dirak δ-function (lec 21).md @@ -17,7 +17,7 @@ $\int _{-\infty} ^{\infty} \delta(t-a)f(t)\, dt=f(a)$ properties: $\int_{{-\infty}}^{\infty} \delta(t-a)\, dt=1$ -![[Drawing 2023-10-25 13.16.20.excalidraw]] +![draw](drawings/Drawing-2023-10-25-13.16.20.excalidraw.png) $\int _{-\infty} ^t \delta(t-a)\, dt=\begin{cases}0, & tfinite number of points of jump discontinuity. What is continuity? the limit exists and equals the value at that point. So what is jump discontinuity? Look at the picture: -![[Drawing 2023-10-11 13.17.32.excalidraw.png]] +![draw](drawings/Drawing-2023-10-11-13.17.32.excalidraw.png) Def: $f(t)$ is of exponential order $\alpha$ if there exists positive constants $\ T,\ M$ such that $f(t)\leq Me^{\alpha t}$ for all $t\geq T$ this is important so that: $f(t)e^{-st}\underset{ \text{as } t\to \infty }{ \nrightarrow } \infty$ @@ -37,7 +37,7 @@ $e^{5 t}$ is this of exponential order? Of course, $M=1,\alpha=5$ what about $\sin(t)$? yes, sin is bounded between -1 and 1 What about $e^{t^2}$? No, $t^2$ always outgrows $\alpha t$ eventually. This function does not have a LT. -![[drawings/Drawing 2023-10-11 13.21.18.excalidraw.png]] +![draw](drawings/Drawing-2023-10-11-13.21.18.excalidraw.png) ## Properties diff --git a/content/Periodic functions (lec 19).md b/content/Periodic functions (lec 19).md index 11c7dcd..68371a0 100644 --- a/content/Periodic functions (lec 19).md +++ b/content/Periodic functions (lec 19).md @@ -6,7 +6,7 @@ This lecture we will learn about periodic functions, specifically, non-sinusoida Definition: $f$ is periodic with period $T \quad (T>0)$ if: $$f(t)=f(t+T), \quad \forall\ t\in \mathbb{R}$$ -![[Drawing 2023-10-20 13.06.35.excalidraw.png]] +![draw](drawings/Drawing-2023-10-20-13.06.35.excalidraw.png) We will now compute laplace transforms of these periodic functions. Computing DE's containing these periodic functions using something like #voparam would not be easy. Let's try taking the laplace of a periodic function $f(t)$: If we take the windowed version of the function (one period, where everywhere else is 0, ie:) @@ -32,7 +32,7 @@ $$\mathcal{L}\{f\}=\mathcal{L}\{f_{T}\} \frac{1}{1-e^{-Ts}}$$ handy formula! ^ will be used again. #ex Imagine another function: (image is of a square wave with a period of 2a, oscillates between 1 and 0, starts at 1 when t=0.) -![[Drawing 2023-10-20 13.27.58.excalidraw.png]] +![draw](drawings/Drawing-2023-10-20-13.27.58.excalidraw.png) Let's compute its LT: $\mathcal{L}\{f\}=\mathcal{L}\{f_{2a}\} \frac{1}{1-e^{-2as}}$ $f_{2a}=u(t)-u(t-a)$ (this is the first period piece) diff --git a/content/Power series (lec 22-25).md b/content/Power series (lec 22-25).md index 2e7f5bc..a00dad8 100644 --- a/content/Power series (lec 22-25).md +++ b/content/Power series (lec 22-25).md @@ -17,7 +17,7 @@ Theorem: With each $\sum_{n=0}^{\infty}a_{n}(x-x_{0})^n$ we can associate a radi The series is absolutely convergent for all $x$ such that $\mid x-x_{0}\mid<\rho$, and divergent for all $x$ where $\mid x-x_{0}\mid>\rho$ "Who keeps stealing the whiteboard erases? (jokingly) It's a useless object, anyways" -![[Drawing 2023-10-30 13.12.57.excalidraw.png]] +![draw](drawings/Drawing-2023-10-30-13.12.57.excalidraw.png) how can we find $\rho$? Definition of ratio test: If $\lim_{ n \to \infty }\mid \frac{a_{n+1}}{a_{n}}\mid=L$ then the radius of convergence $\rho$ is: $\rho=\frac{1}{L}$ @@ -189,7 +189,7 @@ if $p(x)$ and $q(x)$ are analytic functions in a vicinity of $x_{0}$ then we expect that the solution $y$ can be represented by a power series. This is true according to the following theorem: Theorem: If $x_{0}$ is an ordinary point then the differential equation above has two linearly independent solution of the form $\sum_{n=0} ^\infty a_{n}(x-x_{0})^n, \qquad\sum_{n=0}^\infty b_{n}(x-x_{0})^n$. The radius of convergence for them is at least as large as the distance between $x_{0}$ and the closest singular point (which can be real or complex). -![[Drawing 2023-10-30 13.12.57.excalidraw.png]] +![draw](drawings/Drawing-2023-10-30-13.12.57.excalidraw.png) ## Examples for calculating $\rho$ #ex @@ -218,7 +218,7 @@ $y''+\frac{x}{x^2+1}y'+\frac{y}{x^2+1}=0$ remember singular points can be complex the two singular points are: $x^2=1=0 \qquad x=\pm i$ now we have to compute the two distances of these singular points to x=1 -![[Drawing 2023-11-03 13.40.54.excalidraw.png]] +![draw](drawings/Drawing-2023-11-03-13.40.54.excalidraw.png) To calculate distance: $\alpha_{1}+\beta_{1}i, \qquad \alpha_{2}+\beta_{2}i$ $\sqrt{ (\alpha_{1}-\alpha_{2})^2+(\beta_{1}-\beta_{2})^2 }$ $\rho\geq \sqrt{ 1^2+1^2 }=\sqrt{ 2 }$ diff --git a/content/Resonance & AM (lec 13-14).md b/content/Resonance & AM (lec 13-14).md index 4844fa0..a90a36d 100644 --- a/content/Resonance & AM (lec 13-14).md +++ b/content/Resonance & AM (lec 13-14).md @@ -75,7 +75,7 @@ To recap, taking a frictionless mass spring system which is initially at rest, a >Sometimes I feel this effect when I'm sitting in the back of the bus, where the bus is stopped at a red light. I wonder if this modulated vibration pattern is attributed to this exact phenomenon. # Shortcut for solving DE of a mass-spring system -![[Drawing 2023-10-06 13.24.11.excalidraw]] +![draw](drawings/Drawing-2023-10-06-13.24.11.excalidraw.png) $my''+by'+ky=mg+F$ move $mg$ to LHS and replace $y$ with $y_{new}$ (remember, the $\frac{mg}{k}$ is a constant, its derivative is 0): $m\left( y-\frac{mg}{k} \right)''+b\left( y-\frac{mg}{k} \right)'+k\left( y-\frac{mg}{k} \right)=F$ diff --git a/content/Second order homogenous linear equations (lec 5-7).md b/content/Second order homogenous linear equations (lec 5-7).md index d1a9fc1..aab4630 100644 --- a/content/Second order homogenous linear equations (lec 5-7).md +++ b/content/Second order homogenous linear equations (lec 5-7).md @@ -5,7 +5,7 @@ Second order equations arise from very simple problems many engineers face, for #second_order ### $$a_{2}(t)y''+a_{1}(t)y'+a_{0}(t)y=f(t)$$ To motivate our interest: #fix -![[Drawing 2023-09-15 13.32.48.excalidraw]] +![draw](drawings/Drawing-2023-09-15-13.32.48.excalidraw.png) $ma=my''=-by'-ky$ Look how a second order equation describes the motion of a mass-spring system! > Circuits that contains resistors, capacitors and inductors also behaves with this equation as well if you ignore the external magnetic fields around the circuit. diff --git a/content/Separation of variables & Eigen value problems (lec 26-28).md b/content/Separation of variables & Eigen value problems (lec 26-28).md index 069973b..944d78a 100644 --- a/content/Separation of variables & Eigen value problems (lec 26-28).md +++ b/content/Separation of variables & Eigen value problems (lec 26-28).md @@ -4,9 +4,7 @@ We start with some thermodynamics # Heat equation Heat equation not only describes thermodynamics but it can also model the diffusion of gasses. It is a partial differential equation. Strikingly, it can also model option prices in the stock market. However, using it as a strategy to make money is not so simple, because if it worked then everyone would try to use it to make money, which would cause the overall strategy to be less effective as the option prices start to get priced to accommodate for the prediction (🤯). -![[Drawing 2023-11-08 13.07.19.excalidraw.png]] ->I'm sorry the image doesn't display properly :( I'm trying to get images to work on my notes. For now you can see the relevant .png files in the github repo under content/drawings/ - +![draw](drawings/Drawing-2023-11-08-13.07.19.excalidraw.png) We assume that the tube is perfectly insulating along its surface, this helps reduce the problem into a one dimensional problem. Heat can only travel inside and along the x axis. Fourier figured out that: $\text{Heat flux} = -k(x)a\frac{\partial u}{\partial x}(t,x) \Delta t$ diff --git a/content/Systems of linear equations (lec 21-22).md b/content/Systems of linear equations (lec 21-22).md index 16b3499..9de1bd9 100644 --- a/content/Systems of linear equations (lec 21-22).md +++ b/content/Systems of linear equations (lec 21-22).md @@ -1,7 +1,7 @@ #ex #SoLE Lets start modelling some electric circuits again: -![[Drawing 2023-10-25 13.43.26.excalidraw]] +![draw](drawings/Drawing-2023-10-25-13.43.26.excalidraw) The circuit is switched on (battery in series) at $t=0$ and is then switched off (battery is bypassed) at $t=1$ Applying KVL: $0.2I_{1}'+0.1I_{3}'+2I_{1}=g(t) \qquad \text{where } g(t)=\begin{cases}6, & 0\leq t\leq 1 \\0, & 1 p { - display: inline-block; - margin-left: 16px; } - -hr { - background: var(--divider-color); - margin-top: 2.6em; - margin-bottom: 12px; } - -h4 { - font-family: "AvenirNext-Medium"; - color: var(--title-text-color); - font-size: 1.05em; - margin-bottom: .47143em; } - -* + p, -* + ul, -* + ol, -* + blockquote { - /*margin-top: 1.6em;*/ } - -svg + ul, -svg + ol { - margin-top: 0; } - -* + h2, -* + h3, -* + h4 { - margin-top: 2.8em; } - -h1, h2, h3, h4, h5, h6 { - position: relative; } - -h1:before, -h2:before, -h3:before, -h4:before, -h5:before, -h6:before { - position: absolute; - left: -2.2em; - color: var(--heading-indicator); - font-size: 12px; } - -h1:before { - content: "H1"; } - -h2:before { - content: "H2"; } - -h3:before { - content: "H3"; } - -h4:before { - content: "H4"; } - -h5:before { - content: "H5"; } - -h6:before { - content: "H6"; } - -.note-wrapper { - margin-top: 2em; } - -.highlighted { - background: var(--selected-text-background-color); } - -.hashtag { - cursor: pointer; - margin-bottom: 4px; - position: relative; - margin-right: 2px; } - -.hashtag:before { - content: "#"; } - -* + table { - margin-top: 12px; } - -table { - border-radius: 4px; - border: 1px solid var(--separator-color); - border-collapse: inherit; - overflow: hidden; - width: 100%; } - -table th { - font-family: "Avenir-Medium", "AvenirLTStd-Medium"; } - -table td, -table th { - padding: 0.3em 0.8em; } - -table tr:nth-child(odd) { - background-color: var(--selected-text-inactive-background-color); } - -pre, -p code, -li code { - border: 1px solid var(--separator-color); - padding: 10px; - font-size: 12px; - background: white; - overflow: hidden; } - -li code, -p code { - padding: 2px; } - -li img { - width: 122px; } - -.thumbnail { - width: 122px; - height: 76px; - border: 1px solid var(--separator-color); - object-fit: cover; } - -.turbolinks-progress-bar { - visibility: hidden; } diff --git a/resources/_gen/assets/scss/css/style.scss_f300667da4f5b5f84e1a9e0702b2fdde.json b/resources/_gen/assets/scss/css/style.scss_f300667da4f5b5f84e1a9e0702b2fdde.json deleted file mode 100644 index 28c014b..0000000 --- a/resources/_gen/assets/scss/css/style.scss_f300667da4f5b5f84e1a9e0702b2fdde.json +++ /dev/null @@ -1 +0,0 @@ -{"Target":"css/style.css","MediaType":"text/css","Data":{}} \ No newline at end of file diff --git a/themes/zettels/assets/css/style.scss b/themes/zettels/assets/css/style.scss index 5d1f0e6..0ab9b98 100644 --- a/themes/zettels/assets/css/style.scss +++ b/themes/zettels/assets/css/style.scss @@ -405,7 +405,7 @@ mark { } img { - max-width: 100%; + max-width: 70%; height: auto }