Added(A)/Deleted(D) following books

 A  Engineering_Mechanics_by_R.K_Bansal/screenshots/sfd2.png
A  j_by_j/README.txt
A  j_by_j/hrituraj.ipynb
A  j_by_j/sai.ipynb
A  j_by_j/screenshots/SAPWEBIDE.png
A  j_by_j/screenshots/monica2.png
A  j_by_j/screenshots/pylab.png

7 files changed, 955 insertions, 0 deletions

diff --git a/Engineering_Mechanics_by_R.K_Bansal/screenshots/sfd2.png b/Engineering_Mechanics_by_R.K_Bansal/screenshots/sfd2.png
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+++ b/Engineering_Mechanics_by_R.K_Bansal/screenshots/sfd2.png
diff --git a/j_by_j/README.txt b/j_by_j/README.txt
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index 00000000..0703bdc5
--- /dev/null
+++ b/j_by_j/README.txt
@@ -0,0 +1,10 @@
+Contributed By: asmita asmita
+Course: mtech
+College/Institute/Organization: sd
+Department/Designation: sd
+Book Title: j
+Author: j
+Publisher: q
+Year of publication: 1
+Isbn: 2
+Edition: 1
\ No newline at end of file
diff --git a/j_by_j/hrituraj.ipynb b/j_by_j/hrituraj.ipynb
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--- /dev/null
+++ b/j_by_j/hrituraj.ipynb
@@ -0,0 +1,596 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter 4 - Design Against Fluctuating Load"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.1 Pg 102"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      " for stepped plate under tension, Kt=1.75 for r/d = 0.125 & D/d = 1.25 \n",
+      "\n",
+      " for finite width plate under tension with a hole, Kt=2.42 for d0/w = 0.25\n",
+      "\n",
+      " Thickness of plate = 6.05 mm or 6 mm\n"
+     ]
+    }
+   ],
+   "source": [
+    "## Given data\n",
+    "P=6## kN\n",
+    "#dimensions of plate\n",
+    "r=5##mm\n",
+    "d=40##mm\n",
+    "D=50##mm\n",
+    "d0=10##mm\n",
+    "w=40##mm\n",
+    "Sut=200##MPa\n",
+    "n=2.5## factor of safety\n",
+    "\n",
+    "#Fillet - \n",
+    "rBYd=r/d#\n",
+    "DBYd=D/d#\n",
+    "Kt=1.75## factor\n",
+    "print ' for stepped plate under tension, Kt=%.2f for r/d = %.3f & D/d = %.2f '%(Kt,rBYd,DBYd)\n",
+    "\n",
+    "# Hole -\n",
+    "d0BYw=d0/w#\n",
+    "Kt=2.42## factor \n",
+    "print '\\n for finite width plate under tension with a hole, Kt=%.2f for d0/w = %.2f'%(Kt,d0BYw)\n",
+    "sigma_max_into_t = Kt*P/(w-d0)##N/mm sq.\n",
+    "\n",
+    "#Design stress\n",
+    "sigma_d = Sut/n## MPa\n",
+    "#putting sigma_max=sigma_d\n",
+    "t=sigma_max_into_t/sigma_d*1000## mm\n",
+    "print '\\n Thickness of plate = %.2f mm or %.f mm'%(t,t)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.2 Pg 104"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " Diameter of axle = 46.5 mm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import pi\n",
+    "# Given Data\n",
+    "rBYd=0.1#\n",
+    "DBYd=1.2#\n",
+    "P=3## kN\n",
+    "Syt=300##MPa\n",
+    "n=3## factor of safety\n",
+    "#dimensions of plate\n",
+    "l1=400##mm\n",
+    "l2=300##mm\n",
+    "l3=400##mm\n",
+    "\n",
+    "\n",
+    "sigma_d=Syt/n## MPa\n",
+    "Kt=1.65## factor for circular fillet radius member\n",
+    "Rp=P/2##kN (bearing reaction due to symmetry)\n",
+    "Mf=Rp*l1## kN.mm (bending moment at fillet)\n",
+    "Mc=P*(l1+l2+l3)/4## kN.mm (bending moment at centre)\n",
+    "\n",
+    "#Fillet\n",
+    "#sigma_max=Kt*32*Mf/(pi*d**3)\n",
+    "sigma_max_into_d_cube_1 = Kt*32*Mf*1000/pi\n",
+    "\n",
+    "\n",
+    "#Centre\n",
+    "#sigma_max=32*Mc/(pi*d**3)\n",
+    "sigma_max_into_d_cube_2 = Kt*32*Mf*1000/pi\n",
+    "sigma_max_into_d_cube=max(sigma_max_into_d_cube_1,sigma_max_into_d_cube_2)## (getting max)\n",
+    "\n",
+    "#putting sigma_max=sigma_d\n",
+    "t=(sigma_max_into_d_cube/sigma_d)**(1/3)## mm\n",
+    "print '\\n Diameter of axle = %.1f mm'%t"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.3 Pg 105"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " Endurance limit = 45.50 MPa\n"
+     ]
+    }
+   ],
+   "source": [
+    "# Given Data\n",
+    "Sut=440##MPa\n",
+    "d=25##mm\n",
+    "R=95/100## reliability\n",
+    "Kt=1.8## stress concentration factor\n",
+    "q=0.86## sensitivity factor\n",
+    "\n",
+    "Se_dash = 0.5*Sut## MPa\n",
+    "\n",
+    "# for machined surface\n",
+    "ka=0.82## surface finish factor\n",
+    "kb=0.85## size factor\n",
+    "kc=0.868## reliability factor\n",
+    "kd=1## temperature factor\n",
+    "ke=0.577## load factor\n",
+    "\n",
+    "Kf=1+q*(Kt-1)## fatigue strength factor\n",
+    "kf=1/Kf ## fatigue strength reduction factor\n",
+    "Se=ka*kb*kc*kd*ke*kf*Se_dash## (MPa) Endurance limit\n",
+    "print '\\n Endurance limit = %.2f MPa'%Se"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.4 Pg 105"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " Thickness of plate = 18.23 mm or 20 mm\n"
+     ]
+    }
+   ],
+   "source": [
+    "# Given Data\n",
+    "Sut=440##MPa\n",
+    "w=60##mm\n",
+    "d=12## mm\n",
+    "P=20## kN\n",
+    "q=0.8## sensitivity factor\n",
+    "R=90/100## reliability\n",
+    "n=2## factor of safety\n",
+    "\n",
+    "Kt=2.52## stress concentration factor\n",
+    "Se_dash = 0.5*Sut## MPa\n",
+    "# for hot rollednormalized condition\n",
+    "ka=0.67## surface finish factor\n",
+    "kb=0.85## size factor (assuming t<50 mm)\n",
+    "kc=0.897## reliability factor\n",
+    "kd=1## temperature factor\n",
+    "ke=0.9## load factor\n",
+    "dBYw=d/w# #(for circular hole)\n",
+    "\n",
+    "Kf=1+q*(Kt-1)## fatigue strength factor\n",
+    "kf=1/Kf ## fatigue strength reduction factor\n",
+    "Se=ka*kb*kc*kd*ke*kf*Se_dash## (MPa) Endurance limit\n",
+    "sigma_d=Se/n## MPa (design stress)\n",
+    "# sigma_max=P/(w-d)/t\n",
+    "sigma_max_into_t = P*1000/(w-d)#\n",
+    "# putting sigma_max=sigma_d\n",
+    "t=sigma_max_into_t/sigma_d## mm\n",
+    "print '\\n Thickness of plate = %.2f mm or 20 mm'%t"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.5 Pg 107"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " Endurance of specimen = 325.00 MPa\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import pi, log10\n",
+    "# Given Data\n",
+    "Sut=650##MPa\n",
+    "N=10**5## cycles\n",
+    "Se_dash = 0.5*Sut## MPa\n",
+    "of=5## unit\n",
+    "ob=6##unit\n",
+    "bf=ob-of## unit\n",
+    "be=3##unit\n",
+    "\n",
+    "# calculating endurance section wise\n",
+    "OE=log10(Se_dash)#\n",
+    "OA=log10(0.9*Sut)#\n",
+    "AE=OA-OE#\n",
+    "#log10_Sf=OD=OE+ED=OE+FC\n",
+    "log10_Sf=OE+(bf/be)*AE#\n",
+    "Sf=10**log10_Sf# # (MPa) Endurance\n",
+    "print '\\n Endurance of specimen = %.2f MPa'%Sf"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.6 Pg 108"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " diameter of beam 20 mm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import pi, log10\n",
+    "# Given Data\n",
+    "Sut=540##MPa\n",
+    "N=10**4## cycles\n",
+    "q=0.85## sensitivity factor\n",
+    "R=90/100## reliability\n",
+    "P=1500## N\n",
+    "l=160## mm\n",
+    "\n",
+    "Se_dash = 0.5*Sut## MPa\n",
+    "# for cold drawn steel\n",
+    "ka=0.79## surface finish factor\n",
+    "kb=0.85## size factor (assuming t<50 mm)\n",
+    "kc=0.897## reliability factor\n",
+    "kd=1## temperature factor\n",
+    "ke=1## load factor\n",
+    "\n",
+    "Kt=1.33## under bending\n",
+    "\n",
+    "Kf=1+q*(Kt-1)## fatigue strength factor\n",
+    "kf=1/Kf ## fatigue strength reduction factor\n",
+    "Se=ka*kb*kc*kd*ke*kf*Se_dash## MPa( Endurance limit)\n",
+    "\n",
+    "of=4## unit\n",
+    "ob=6##unit\n",
+    "bf=ob-of## unit\n",
+    "be=3##unit\n",
+    "\n",
+    "# calculating endurance section wise\n",
+    "OE=log10(Se)#\n",
+    "OA=log10(0.9*Sut)#\n",
+    "AE=OA-OE#\n",
+    "#log10_Sf=OD=OE+ED=OE+FC\n",
+    "log10_Sf=OE+(bf/be)*AE#\n",
+    "Sf=10**log10_Sf# # (MPa) Endurance\n",
+    "\n",
+    "MB=P*l## N.mm\n",
+    "# 32*MB/pi/d**3 = Sf\n",
+    "d=(32*MB/pi/Sf)**(1/3)\n",
+    "print '\\n diameter of beam %.f mm'%d"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.7 Pg 110"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " diameter d at fillet cross section = 16 mm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import pi, log10, atan\n",
+    "# Given Data\n",
+    "Sut=600##MPa\n",
+    "Syt=380##MPa\n",
+    "q=0.9## sensitivity factor\n",
+    "R=90/100## reliability\n",
+    "n=2## factor of safety\n",
+    "Pmin=-100## N\n",
+    "Pmax=200## N\n",
+    "l=150## mm\n",
+    "\n",
+    "Se_dash = 0.5*Sut## MPa\n",
+    "# for cold drawn steel\n",
+    "ka=0.76## surface finish factor\n",
+    "kb=0.85## size factor (assuming t<50 mm)\n",
+    "kc=0.897## reliability factor\n",
+    "kd=1## temperature factor\n",
+    "ke=1## load factor\n",
+    "\n",
+    "Kt=1.4## under bending\n",
+    "\n",
+    "Kf=1+q*(Kt-1)## fatigue strength factor\n",
+    "kf=1/Kf ## fatigue strength reduction factor\n",
+    "Se=ka*kb*kc*kd*ke*kf*Se_dash## MPa( Endurance limit)\n",
+    "Mmax=Pmax*l## N.mm\n",
+    "Mmin=Pmin*l## N.mm\n",
+    "Mm=(Mmax+Mmin)/2## N.mm\n",
+    "Ma=(Mmax-Mmin)/2## N.mm\n",
+    "theta=atan(Ma/Mm)*pi/180## degree\n",
+    "\n",
+    "#equation of Goodman - sigma_m/Sut+sigma_a/Se=1\n",
+    "#here sigma_a/sigma_m=3\n",
+    "sigma_m=1/(1/Sut+3/Se)##MPa\n",
+    "sigma_a=3*sigma_m## MPa\n",
+    "\n",
+    "sigma_da=sigma_a/n## MPa\n",
+    "#sigma_da=32*Ma/pi/d**3\n",
+    "d=(32*Ma/pi/sigma_da)**(1/3)## mm \n",
+    "print '\\n diameter d at fillet cross section = %.f mm'%d"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.8 Pg 112"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " diameter of shaft = 34 mm\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import pi, log10, atan,tan\n",
+    "# Given Data\n",
+    "Sut=500##MPa\n",
+    "Syt=300##MPa\n",
+    "R=90/100## reliability\n",
+    "n=2## factor of safety\n",
+    "Tmin=-200## N.m\n",
+    "Tmax=500## N.m\n",
+    "\n",
+    "Se_dash = 0.5*Sut## MPa\n",
+    "# for cold drawn steel\n",
+    "ka=0.80## surface finish factor\n",
+    "kb=0.85## size factor (assuming t<50 mm)\n",
+    "kc=0.897## reliability factor\n",
+    "kd=1## temperature factor\n",
+    "ke=0.577## load factor\n",
+    "\n",
+    "Ses=ka*kb*kc*kd*ke*Se_dash## MPa( Endurance limit)\n",
+    "Sys=ke*Syt## MPa\n",
+    "Tm=(Tmax+Tmin)/2## N.m\n",
+    "Ta=(Tmax-Tmin)/2## N.m\n",
+    "theta=atan(Ta/Tm)*pi/180## degree\n",
+    "Sms=Ses/tan(theta*180/pi)##MPa\n",
+    "Sas=Ses##MPa\n",
+    "tau_da=Sas/n##MPa\n",
+    "#tua_da=16*Ta/pi/d**3\n",
+    "d=(16*Ta*1000/pi/tau_da)**(1/3)##mm\n",
+    "print '\\n diameter of shaft = %.f mm'%d"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.9 Pg 113"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " life of the spring, N = 215630 cycles\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import pi,log10\n",
+    "# Given Data\n",
+    "Sut=860##MPa\n",
+    "Syt=690##MPa\n",
+    "Pmin=60## N\n",
+    "Pmax=120## N\n",
+    "R=50/100## reliability\n",
+    "l=500##mm\n",
+    "d=10##mm\n",
+    "Se_dash = 0.5*Sut## MPa\n",
+    "# for machines surface\n",
+    "ka=0.70## surface finish factor\n",
+    "kb=0.85## size factor (assuming t<50 mm)\n",
+    "kc=1## reliability factor\n",
+    "kd=1## temperature factor\n",
+    "ke=1## load factor\n",
+    "\n",
+    "Se=ka*kb*kc*kd*ke*Se_dash## MPa( Endurance limit)\n",
+    "Mmax=Pmax*l## N.mm\n",
+    "Mmin=Pmin*l## N.mm\n",
+    "Mm=(Mmax+Mmin)/2## N.mm\n",
+    "Ma=(Mmax-Mmin)/2## N.mm\n",
+    "Sm=32*Mm/pi/d**3##MPa\n",
+    "sigma_m=Sm##MPa\n",
+    "Sa=32*Ma/pi/d**3##MPa\n",
+    "sigma_a=Sa##MPa\n",
+    "Sf=Sa*Sut/(Sut-Sm)##MPa\n",
+    "\n",
+    "#calculating section\n",
+    "OB=6##unit ref. o at 3\n",
+    "BE=OB-3##unit\n",
+    "OC=Sf## MPa\n",
+    "AE=log10(0.9*Sut)-log10(Se)##MPa\n",
+    "AC=log10(0.9*Sut)-log10(Sf)##MPa\n",
+    "CD=BE*AC/AE##\n",
+    "#log10(N)=3+CD\n",
+    "N=10**(3+CD)## cycle\n",
+    "print '\\n life of the spring, N = %.f cycles'%N\n",
+    "#Note : answer in the textbook is wrong."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## exa 4.10 Pg 116"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      " factor of safety, n = 5.04\n"
+     ]
+    }
+   ],
+   "source": [
+    "from __future__ import division\n",
+    "from math import pi, log10, sqrt,atan,tan\n",
+    "# Given Data\n",
+    "Sut=600##MPa\n",
+    "Se=280##MPa\n",
+    "sigma_x_min=50## MPa\n",
+    "sigma_x_max=100## MPa\n",
+    "sigma_y_min=20## MPa\n",
+    "sigma_y_max=70## MPa\n",
+    "\n",
+    "sigma_xm=(sigma_x_max+sigma_x_min)/2## MPa\n",
+    "sigma_xa=(sigma_x_max-sigma_x_min)/2## MPa\n",
+    "sigma_ym=(sigma_y_max+sigma_y_min)/2## MPa\n",
+    "sigma_ya=(sigma_y_max-sigma_y_min)/2## MPa\n",
+    "\n",
+    "# distortion energy theory - \n",
+    "sigma_m=sqrt(sigma_xm**2+sigma_ym**2-sigma_xm*sigma_ym)## MPa\n",
+    "sigma_a=sqrt(sigma_xa**2+sigma_ya**2-sigma_xa*sigma_ya)## MPa\n",
+    "theta=atan(sigma_a/sigma_m)## radian\n",
+    "# Sm/Sut+Sa/Se=1 where Sa=Sm*tan(theta)\n",
+    "Sm=1/(1/Sut+tan(theta)/Se)## MPa\n",
+    "Sa=tan(theta)*Sm## MPa\n",
+    "n=Sa/sigma_a## factor of safety\n",
+    "\n",
+    "print '\\n factor of safety, n = %.2f'%n"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.6"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/j_by_j/sai.ipynb b/j_by_j/sai.ipynb
new file mode 100644
index 00000000..89275d31
--- /dev/null
+++ b/j_by_j/sai.ipynb
@@ -0,0 +1,349 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# SAMPLE NOTEBOOK"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "\n",
+    "\n",
+    "\n",
+    "## ch-9 page 227   pb-1"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "('load current =', 21.78649237472767)\n",
+      "('design current=', 28.32244008714597)\n",
+      "('Derating factor=', 0.92)\n",
+      "('fuse rating=', 30.785260964289098)\n"
+     ]
+    }
+   ],
+   "source": [
+    "\n",
+    "from __future__ import division\n",
+    "\n",
+    "import math\n",
+    "\n",
+    "vi=120;\n",
+    "k=1000;\n",
+    "pi=2*k;\n",
+    "eff=0.90;\n",
+    "pf=0.85;\n",
+    "t=65;\n",
+    "\n",
+    "lc=(pi)/(vi*eff*pf);\n",
+    "print('load current =',lc);\n",
+    "\n",
+    "dc=1.3*lc;\n",
+    "print('design current=',dc);\n",
+    "\n",
+    "df=(0.2/100)*(t-25);\n",
+    "df=11.5*df;\n",
+    "print('Derating factor=',df);\n",
+    "\n",
+    "fr=dc/df;\n",
+    "print('fuse rating=',fr);\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "\n",
+    "\n",
+    "\n",
+    "## ch-10 page 268   pb-6"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "('power delivered =', 500000.0, 'watts')\n",
+      "('power loss=', 10000.0, 'watts')\n",
+      "(510583.1892725521, 241709.44403085182)\n",
+      "('kvar_cap=', 268.87374524170025)\n",
+      "('c=', 10.111669570616154, 'micro farad/ph')\n",
+      "('differences in kva demand=', 158.7301587301588)\n",
+      "('loss in cable =', 0.6049382716049381)\n",
+      "('cost saving=', 5294.849999999999)\n",
+      "('total three phase capacitor cost=', 48397.274143506045, '$')\n",
+      "('capacitor cost will be recoverred in', 9.140442910281887, 'months')\n"
+     ]
+    }
+   ],
+   "source": [
+    "\n",
+    "from __future__ import division\n",
+    "\n",
+    "import math\n",
+    "\n",
+    "lpf1=0.70;\n",
+    "lpf2=0.90;\n",
+    "vi=460;\n",
+    "f=60;\n",
+    "k=1000;\n",
+    "p=1500*k;\n",
+    "time=300;\n",
+    "cost=60;\n",
+    "l=2/100;\n",
+    "theta1=45.6;\n",
+    "theta2=25.8;\n",
+    "pd=p/3; #since 3 phase;\n",
+    "pl=l*pd;\n",
+    "\n",
+    "print('power delivered =',pd,'watts');\n",
+    "print('power loss=',pl,'watts');\n",
+    "\n",
+    "var1=pd*(math.tan((math.pi/180)*theta1));\n",
+    "var2=pd*(math.tan((math.pi/180)*theta2));\n",
+    "var=var1-var2;\n",
+    "print(var1,var2);\n",
+    "kvar=var/1000;\n",
+    "print('kvar_cap=',kvar);\n",
+    "\n",
+    "vp=vi/(math.sqrt(3));\n",
+    "w=2*math.pi*f;\n",
+    "\n",
+    "c=(1000*kvar)/(w*vp*vp);\n",
+    "c=c*1000;\n",
+    "print('c=',c,'micro farad/ph');\n",
+    "\n",
+    "kva1=(pd/1000)/lpf1;\n",
+    "kva2=(pd/1000)/lpf2;\n",
+    "\n",
+    "dkva=kva1-kva2;\n",
+    "print('differences in kva demand=',dkva);\n",
+    "\n",
+    "loss=(lpf1/lpf2)*(lpf1/lpf2);\n",
+    "print('loss in cable =',loss);\n",
+    "\n",
+    "kvas=3*158.72;\n",
+    "\n",
+    "scl=3*3.95;\n",
+    "\n",
+    "tcost=10*kvas+0.15*scl*time;\n",
+    "print('cost saving=',tcost);\n",
+    "\n",
+    "tccost=cost*3*kvar;\n",
+    "\n",
+    "print('total three phase capacitor cost=',tccost,'$');\n",
+    "\n",
+    "duration=tccost/tcost;\n",
+    "print('capacitor cost will be recoverred in',duration,'months');\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "\n",
+    "\n",
+    "\n",
+    "## ch-13 page 340   pb-3"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "('duty cycle=', 0.5)\n",
+      "('avg o/p voltage=', 60.0)\n",
+      "('avg o/p current=', 4.0)\n",
+      "('avg o/p power=', 240.0)\n",
+      "('L min=', 3.0, 'mhenry')\n"
+     ]
+    }
+   ],
+   "source": [
+    "\n",
+    "from __future__ import division\n",
+    "\n",
+    "import math\n",
+    "\n",
+    "v=120;\n",
+    "i=2;\n",
+    "f=1000;\n",
+    "to=(0.5)/1000;\n",
+    "\n",
+    "T=1/f;\n",
+    "\n",
+    "dr=(to)/T;\n",
+    "print('duty cycle=',dr);\n",
+    "\n",
+    "vo=dr*v;\n",
+    "io=i/dr;\n",
+    "po=vo*io;\n",
+    "\n",
+    "print('avg o/p voltage=',vo);\n",
+    "print('avg o/p current=',io);\n",
+    "print('avg o/p power=',po);\n",
+    "\n",
+    "L=(dr*(v/10))/2;\n",
+    "\n",
+    "print('L min=',L,'mhenry');\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "\n",
+    "\n",
+    "\n",
+    "## ch-14 page 363   pb-4"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "('V dc=', 339.4112549695428)\n",
+      "('I dc=', 5.892556509887896)\n",
+      "('fundamental ac side rms current =', 8.333333333333334)\n",
+      "('THD=', 0.8259394650941436)\n",
+      "('I ac(rms)=', 10.77677544021814)\n",
+      "('I dc(rms)=', 9.023118455759443)\n"
+     ]
+    }
+   ],
+   "source": [
+    "\n",
+    "from __future__ import division\n",
+    "import math\n",
+    "\n",
+    "v=240;\n",
+    "f=60;\n",
+    "p=2000;\n",
+    "dpf=1;\n",
+    "k1=73.2;k2=36.6;k3=8.1;k4=5.7;\n",
+    "k5=4.1;k6=2.9;k7=0.8;k8=0.4;\n",
+    "h1=3;h2=5;h3=7;h4=9;h5=11;h6=13;h7=17;\n",
+    "\n",
+    "vdc=math.sqrt(2)*v;\n",
+    "\n",
+    "idc=p/vdc;\n",
+    "print('V dc=',vdc);\n",
+    "print('I dc=',idc);\n",
+    "pac=p/dpf;\n",
+    "\n",
+    "\n",
+    "is1=p/v;\n",
+    "\n",
+    "print('fundamental ac side rms current =',is1);\n",
+    "\n",
+    "k=(k1*k1)+k2*k2+k3*k3+k4*k4+k5*k5+k6*k6+k7*k7;\n",
+    "thd=(math.sqrt(k))/100;\n",
+    "print('THD=',thd);\n",
+    "\n",
+    "iac=is1*(math.sqrt(1+(0.82*0.82)));\n",
+    "\n",
+    "idcr=math.sqrt((iac*iac)-(idc*idc));\n",
+    "\n",
+    "print('I ac(rms)=',iac);\n",
+    "print('I dc(rms)=',idcr);\n",
+    "\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "\n",
+    "\n",
+    "\n",
+    "## ch-16 page 454   pb-6"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "('fundamental load current =', 240.5626121623441)\n"
+     ]
+    }
+   ],
+   "source": [
+    "\n",
+    "from __future__ import division\n",
+    "import math\n",
+    "\n",
+    "v=480;\n",
+    "k=1000;\n",
+    "p=200*k;\n",
+    "thd=600;\n",
+    "\n",
+    "lc=p/(math.sqrt(3)*v);\n",
+    "\n",
+    "print('fundamental load current =',lc);\n"
+   ]
+  }
+ ],
+ "metadata": {
+  "anaconda-cloud": {},
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.6"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 1
+}
diff --git a/j_by_j/screenshots/SAPWEBIDE.png b/j_by_j/screenshots/SAPWEBIDE.png
new file mode 100644
index 00000000..912fc016
--- /dev/null
+++ b/j_by_j/screenshots/SAPWEBIDE.png
diff --git a/j_by_j/screenshots/monica2.png b/j_by_j/screenshots/monica2.png
new file mode 100644
index 00000000..21d90884
--- /dev/null
+++ b/j_by_j/screenshots/monica2.png
diff --git a/j_by_j/screenshots/pylab.png b/j_by_j/screenshots/pylab.png
new file mode 100644
index 00000000..0f57a00d
--- /dev/null
+++ b/j_by_j/screenshots/pylab.png