SETRST's blog - Stuff I find useful and helpful ;)

Thursday, November 27, 2014

Live stream from International Space Station (ISS)

eol.jsc.nasa.gov/ForFun/HDEV/

Saturday, November 8, 2014

AC Generator frequency as a function of RPM

w - angular velocity.

f - frequency (number of cycles per second, expressed in Hz).

P - number of poles (= N + S poles. ).

P/2 - number of pole pairs. Above generator example has two poles and one pole pair.

Ns - number of revolutions per second

Nm - number of revolutions per minute

Nm=60*Ns.

w=2Pi*f = (P/2) * N * 2Pi * 1/sec

f=(P/2)*N/sec

f=(P/2)*Ns

f=(P/2)*Nm/60=P*N/120

f=P*Nm/120

Monday, November 3, 2014

Neodymium Magnet Physical Properties

(source: http://www.monroeengineering.com/NeodymiumMagnetPhysicalProperties.html)

Magnetic Characteristics

Material Type Residual Flux Density
(Br) Coercive Force
(Hc) Intrinsic Coercive Force (Hci) Max.Energy Product
(BH)max

N35 11.7-12.1 KGs >11.0 KOe >12 KOe 33-35 MGOe

N38 12.2-12.6 KGs >11.0 KOe >12 KOe 36-38 MGOe

N40 12.6-12.9 KGs >11.0 KOe >12 KOe 38-40 MGOe

N42 13.0-13.2 KGs >11.0 KOe >12 KOe 40-42 MGOe

N45 13.3-13.7 KGs >11.0 KOe >12 KOe 43-45 MGOe

N48 13.8-14.2 KGs >11.0 KOe >12 KOe 45-48 MGOe

N50 14.1-14.5 KGs >11.0 KOe >11 KOe 48-50 MGOe

N52 14.5-14.8 KGs >11.2 KOe >11 KOe 49.5-52 MGOe

N35M 11.7-12.1 KGs >11.4 KOe >14 KOe 33-35 MGOe

N38M 12.2-12.6 KGs >11.4 KOe >14 KOe 36-38 MGOe

N40M 12.6-12.9 KGs >11.4 KOe >14 KOe 38-40 MGOe

N42M 13.0-13.3 KGs >11.4 KOe >14 KOe 40-42 MGOe

N45M 13.3-13.7 KGs >11.4 KOe >14 KOe 42-45 MGOe

N48M 13.6-14.2 KGs >11.4 KOe >14 KOe 45-48 MGOe

N50M 14.1-14.5 KGs >11.4 KOe >14 KOe 48-50 MGOe

N33H 11.4-11.7 KGs >10.3 KOe >17 KOe 31-33 MGOe

N35H 11.7-12.1 KGs >10.8 KOe >17 KOe 33-35 MGOe

N38H 12.2-12.6 KGs >11.4 KOe >17 KOe 36-38 MGOe

N40H 12.6-12.9 KGs >11.4 KOe >17 KOe 38-40 MGOe

N42H 13.0-13.3 KGs >11.4 KOe >17 KOe 40-42 MGOe

N45H 13.3-13.7 KGs >11.4 KOe >17 KOe 42-45 MGOe

N48H 13.6-14.2 KGs >11.4 KOe >16 KOe 45-48 MGOe

N30SH 10.8-11.2 KGs >10.1 KOe >20 KOe 28-30 MGOe

N33SH 11.4-11.7 KGs >10.3 KOe >20 KOe 31-33 MGOe

N35SH 11.7-12.1 KGs >10.8 KOe >20 KOe 33-35 MGOe

N38SH 12.2-12.6 KGs >11.4 KOe >20 KOe 36-38 MGOe

N40SH 12.6-12.9 KGs >11.4 KOe >20 KOe 38-40 MGOe

N42SH 13.0-13.3 KGs >11.4 KOe >20 KOe 40-42 MGOe

N45SH 13.3-13.7 KGs >11.4 KOe >19 KOe 43-45 MGOe

N28UH 10.4-10.8 KGs >9.8 KOe >25 KOe 26-28 MGOe

N30UH 10.8-11.2 KGs >10.1 KOe >25 KOe 28-30 MGOe

N33UH 11.4-11.7 KGs >10.3 KOe >25 KOe 31-33 MGOe

N35UH 11.7-12.1 KGs >10.8 KOe >25 KOe 33-35 MGOe

N38UH 12.2-12.6 KGs >11.4 KOe >25 KOe 36-38 MGOe

N40UH 12.6-12.9 KGs >11.4 KOe >25 KOe 38-40 MGOe

N28EH 10.4-10.8 KGs >9.8 KOe >30 KOe 26-28 MGOe

N30EH 10.8-11.2 KGs >10.1 KOe >30 KOe 28-30 MGOe

N33EH 11.4-11.7 KGs >10.3 KOe >30 KOe 31-33 MGOe

N35EH 11.7-12.1 KGs >10.8 KOe >30 KOe 33-35 MGOe

N38EH 12.2-12.6 KGs >10.8 KOe >30 KOe 36-38 MGOe

Thermal Characteristics

Neodymium Material Type Thermal Expansion Coeff. Maximum Operating Temp Curie Temp Thermal Conductivity

%/¡ÆC ¡ÆC (¡ÆF) ¡ÆC (¡ÆF) kcal/m-h-¡ÆC

N -0.12 176¡ÆF (80¡ÆC) 590¡ÆF (310¡ÆC) 7.7

NM -0.12 212¡ÆF (100¡ÆC) 644¡ÆF (340¡ÆC) 7.7

NH -0.11 248¡ÆF (120¡ÆC) 644¡ÆF (340¡ÆC) 7.7

NSH -0.10 302¡ÆF (150¡ÆC) 644¡ÆF (340¡ÆC) 7.7

NUH -0.10 356¡ÆF (180¡ÆC) 662¡ÆF (350¡ÆC) 7.7

NEH -0.10 392¡ÆF (200¡ÆC) 662¡ÆF (350¡ÆC) 7.7

The Thermal Characteristics listed above are values commonly associated with each magnet's grade or material. Actual performance in your application may vary with other factors, including the shape of the magnet, the Permeance Coefficient or load line, and how it is used in a circuit.

Physical and Mechanical Characteristics

Density
7.4-7.5 g/cm³

Compression Strength
110 kg/mm²

Bending Strength
25 kg/mm²

Vickers Hardness (Hv)
560-600

Tensile Strength
7.5kg/mm²

Young's Modulus
1.7 x 104 kg/mm²

Recoil Permeability
1.05 ¥ìrec

Electrical Resistance (R)
160 ¥ì-ohm-cm

Heat Capacity 350-500 J/(kg.¡ÆC)

Thermal Expansion Coefficient (0 to 100¡ÆC)
parallel to magnetization direction 5.2 x 10^-6 /¡ÆC

Thermal Expansion Coefficient (0 to 100¡ÆC)
perpendicular to magnetization direction -0.8 x 10^-6 /¡ÆC

Plating Characteristics

Plating Type Overall Thickness Salt Spray Test Pressure Cooker Test

NiCuNi (Nickel Copper Nickel) 15-21 ¥ìm 24 hours 48 hours

NiCu + Black Nickel 15-21 ¥ìm 24 hours 48 hours

NiCuNi + Epoxy 20-28 ¥ìm 48 hours 72 hours

NiCuNi + Gold 16-23 ¥ìm 36 hours 72 hours

NiCuNi + Silver 16-23 ¥ìm 24 hours 48 hours

Zinc 7-15 ¥ìm 12 hours 24 hours

Each individual layer of Nickel and Copper are 5-7 ¥ìm thick. The Gold and Silver plating layers are 1-2 ¥ìm thick.
Test results shown to allow comparison between plating options. Performance in your application under your specific test conditions may vary. Salt Spray testing conducted with a 5% NaCl solution, at 35¡ÆC. Pressure Cooker Test (PCT) conducted at 2 atm, 120¡ÆC at 100% RH.

Measurement Systems

Unit cgs System SI System English System

Length (L) centimeter (cm) meter (m) inch (in)

Flux (©ª) Maxwell Weber (Wb) Maxwell

Flux Density (B) Gauss (G) Tesla (T) lines/in²

Magnetizing Force (H) Oersted (Oe) Ampere turns/m (At/m) Ampere turns/in (At/in)

Magnetomotive Force (mmf or F) Gilbert (Gb) Ampere turn (At) Ampere turn (At)

Conversion Between Systems

cgs System to SI system

1 Oe = 79.62 At/m

10,000 G = 1 T

1 Gb = 0.79577 At

1 Maxwell = 1 Line = 10^-8 Wb

1 G = 0.155 lines/in²

Thursday, October 30, 2014

Maxima code based on equation 10 from "Calculation of the Magnetic Field Created by a Thick Coil"

####### Maxima package file (hthickcoil.mac) #######

This code is based on equation 10 from "Calculation of the Magnetic Field Created by a Thick Coil". DOI:10.1163/156939310791958653.

Note: Equ. 10 has two errors. These are fixed in the code.
Errata:
1) In Hz(r,z) plus sign is replaced by minus sign.
2) In EtaZ term z[j] is replaced with z[k].
---------------------------------------------------------

Save this code in hthickcoil.mac file,then copy the file in one of the folders returned by 'file_search_maxima' command. Then execute load("hthickcoil.mac")$

For automatic load of Hring function one can put this line into maxima-init.mac file: setup_autoload("hthickcoil.mac",Hring)$

Usage: Hring(r,z,r1,r2,z1,z2,current).

r and z are cylindrical coordinates of point where you seek the H field.

r1 - inner radius, r2 - outer radius, z1 - lower position, z2 - upper position.

Output is in form of vektor: [HR, Hz, H].

For using built-in elliptic integrals in MAXIMA, see comments FIX1 and FIX2.

Maxima 5.31.2 version has issue with elliptic_ec function of negative argument.

ellipticK(m):=block(

[qtemp1:0.0,qtemp2:0.0],qtemp1:float(qtemp1),

[qtemp1,qtemp2,qtemp2,qtemp2]:quad_qags(1/sqrt(1-m*sin(x)^2),x,0,%pi/2),

return (qtemp1)

ellipticE(m):=block(

[qtemp1:0.0,qtemp2:0.0],qtemp1:float(qtemp1),

[qtemp1,qtemp2,qtemp2,qtemp2]:quad_qags(sqrt(1-m*sin(x)^2),x,0,%pi/2),

return (qtemp1)

Hring(r,z,r_1,r_2,z_1,z_2,I):=

block

(

[Hr,Hz,H,j,theta,v,a,b,fi,kappa,d,c,f,eps:10^(-15),Eta_r,Eta_z,bracket1:0,bracket2:0,qtemp1,qtemp2],

r:float(r),z:float(z),r_1:float(r_1),r_2:float(r_2),z_1:float(z_1),z_2:float(z_2),I:float(I),j:float(j),

H:float(H),Hr:float(Hr),Hz:float(Hz),v:float(v),a:float(a),b:float(b),fi:float(fi),kappa:float(kappa),d:float(d),

c:float(c),f:float(f),bracket1:float(bracket1),bracket2:float(bracket2), qtemp1:float(qtemp1),

/* FIX1: uncomment line below if elliptic_kc/ec(nagative_argument) works. */

/* local (K,E), K(m) := elliptic_kc(m),E(m):=elliptic_ec(m), */

/* FIX2: if elliptic_kc/ec(nagative_argument) does not work use line below.Otherwise if you use FIX1 above then comment line below. */

local (K,E), K(m) := ellipticK(m),E(m):=ellipticE(m),

array(r,flonum,2),array(z,flonum,2),

r[1]:r_1,r[2]:r_2,z[1]:z_1,z[2]:z_2,

j:I/((r_2-r_1)*(z_2-z_1)),

v:r*sin(theta),

for i:1 thru 2 do (

for k:1 thru 2 do (

a: r^2+r[i]^2+(z-z[k])^2,

b:2*r*r[i],

fi:(4/3)*sqrt(a-b)/(b+eps),

kappa: 2*b/(b-a),

d:r[i]-r*cos(theta),

c:sqrt(a-b*cos(theta)),

f:z-z[k]+eps,

Eta_r:r*cos(theta)^2*log(d+c),

Eta_z:r*cos(theta)*log(f+c)+v*atan((d*f*csc(theta)/(r*c+eps)))-z[k]+v*atan(v/f),

[qtemp1,qtemp2,qtemp2,qtemp2]:( quad_qags(Eta_r,theta,0+eps,%pi-eps) + quad_qags(Eta_r,theta,%pi+eps,2*%pi-eps) ),

bracket1: bracket1 + ((-1)^(i+k))*(qtemp1+fi*((a+b)*K(kappa)-a*E(kappa))),

[qtemp1,qtemp2,qtemp2,qtemp2]:( quad_qags(Eta_z-f*log(d+c),theta,0+eps,%pi-eps)+quad_qags(Eta_z-f*log(d+c),theta,%pi+eps,2*%pi-eps) ),

bracket2: bracket2 + ((-1)^(i+k))*qtemp1

) /* end_for_k */

), /* end_for_i */

Hr:ev((j/(4*%pi))*bracket1,numer), Hz:ev((j/(4*%pi))*bracket2,numer),

/* OUTPUT: [HR, Hz, H] */

return ([Hr,Hz,sqrt(Hr^2+Hz^2)])

Monday, October 27, 2014

Double Factorial

n(n-2)(n-4)...3*1 ; n>0 and odd

(n!!)= n(n-2)(n-4)...4*2 ; n>0 and even

1 ; n=-1,0 ( -1!!=0!!=1)

(2n-1)!!=(2n)!/((2^n)*n!)

(2n)!!:=(2^n)n!

Tuesday, September 30, 2014

Running Firebird database server as application

0. Download firebird from: http://sourceforge.net/projects/firebird/files/
1. Unzip Firebird-xxxxxxx-xxxxx.zip

2. Go to bin folder.
3. Execute fbserver with "-a" switch.
--------------------------------------------------
Example for windows:

Start cmd.exe and type:
cd Path_to_firebird\bin [enter]
fbserver.exe -a [enter]

(Use Flamerobin's "Register existing database..." option to connect to a .fdb file,
and then edit and view the contest of the same.
For username | password combo try: sysdba | masterkey)

Friday, September 26, 2014

Maxima Tutorials

Some tutorials about using Maxima , computer algebra system :
http://setrst.byethost10.com/_blog/maxima/

Maxima links and resources: http://mathscitech.org/articles/maxima

Sunday, September 14, 2014

Skype offline installer for Windows

Latest Skype version: http://www.skype.com/go/getskype-full

Thursday, November 28, 2013

Trainer for Windows 3D pinball - Space Cadet

(tags: cheat, trainer, windows, 3d pinball space cadet)

Download Space cadet trainer.

1) Unzip and copy "3d.PINBALL.Space.Cadet.trained.exe" in the same folder as pinball.exe.
Pinball.exe should be somewhere in Program Files (\Windows NT\
Pinball (on Win XP)).

2) Launch "3d.PINBALL.Space.Cadet.trained.exe".

3) Go to Game and check "Always Re-Deploy".

(Cheat works by making Re-Deploy always ON.)

4) Have fun ;)

Wednesday, June 19, 2013

FREE SMS/TXT SITES

1) http://afreesms.com/freesms/ (Let's you spoof the "Sender ID" field.)
2) http://globfone.com/ (Sends flash type of message,which just shows up on your display,no interaction is needed.)
3) http://www.talksms.com/ (1 free sms per day)
4) http://pc2mobile.net
5) http://www.socialland.net/sendsms.php (user: nicksloter, pass:?)
6) http://freesmscell.net/sms.php
7) http://www.dailysms.us

8) http://www.dosms.me/sms.php

9) http://www.freesms.net
----------------------------
10) http://www.armsms.com

Wednesday, March 27, 2013

Santana - Soul Sacrifice (Woodstock 1969) Incredible drum solo by 20 yr old boy! Michael Shrieve

From: http://vimeo.com/63053717