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1. ### Calculate Power Margin Required to Prevent Satellite Link Drop

Hi, I've been looking at some example solution and still haven't found the physical/mathematical explanation for the given solution. Problem: Due to slow satellite stabilization rotation there are big differences between maximums and minimums of received signals. Calculate the power...
2. ### Find the Right Book on Electromagnetic Radiation and Radio Communications

Hi, I am completing the study of telecommunications. As I've lost some lecture notes and I like to keep references on my bookshelf I am looking for a good book about Electromagnetism, electromagnetic radiation and radio communications. From the comprehensive online offer it is not easy to...
3. ### Modelling electromagnetic wave reflection

Hi, I am trying to calculate the power of a reflected electromagnetic field and can't find a physical explanation for a given solution. I've noticed the following example: The Plane has a radar for altitude measurement which emmits the power Ptx at the frequency ftx. Calculate the power...
4. ### Any idea about how determine body movement upun the accelerations?

How can you determine the type of motion by integrating the graph? The goal is to determine the type of movement by analizing graph - whether it is walk, run, fall... I wrote about the concept here: http://mypetprojects.blogspot.com/
5. ### How to calculate the work from force (acceleration and mass)

Hi, I would like to calculate the used energy with the accelerometer. Does anyone know how to calculate the used energy (work) from acceleration and body mass?
6. ### Any idea about how determine body movement upun the accelerations?

Any idea about how determine body movement upon the accelerations? Hi, I am trying to implement an algorithm which would determine the person's activity upon the received acceleration measurement data. I am measuring the accelerations using accelerometer sensors on mobile phones and send...
7. ### Op-Amp Inverting Configuration: Does Load Resistor Change Gain Equation?

The equation doesn't change. You can get this equation by wrighting a sum of currents on - connection. If you add a load resistor V0 doesn't change thus you can write Uy/R1+V0/R2 = 0 and you get the same equation.
8. ### Aerospace engineering study and work in the United States

Hi, I am approaching the end of my current study of electrical engineering - telecommunications. The world of airplanes and flying machines has also been fascinating me for some time now. But for now this is almost entirely unknown field to me. I would be very happy if I could work somewhere in...
9. ### Searching for the best way to the success

Hi, I am currently 3rd year electrical engineering (telecommunications department). I am really interested in it and I am already thinking about the career. I have pretty high ambitions so I would like to get some advices about the best way to success in engineering work. I am thinking about...
10. ### Aerodynamics and hydrodynamics

Hi, Let's tie a sphere, drop it into a water and trawl it with a boat. How do we calculate the angle between a vertical line and rope? Actually I don't know much about aerodynamics and hydrodynamics so I don't know how drag force is calculated from shape, mass and speed of an object. Recently...
11. ### Solving Ropewalk Equations - Help from Niko

If we think about the relations between quantities: Let's look an angle between vertical line and the man on the rope and we assume equilibrium at x=0. A=angle, v=speed on x direction, k and g are some coefficients dA(t)/dt=k*A(t)-g*v(t) My explanation: If the angle is greater, the angle is...
12. ### Solving Ropewalk Equations - Help from Niko

Hi, I am trying to do a model for a ropewalk. I would like to describe it with two first order differential equations. If we consider a person walking on a rope there are two quantities changing; the speed of a rope in horizontal direction and the angle of a person. I have to write this in a...
13. ### Airship Modeling: Find Data on Air Temperature, Density, and Pressure

Hi! I am doing a simple mathematical model of an airship. I need the data for air temperature, density and pressure for different altitudes. Could anyone give me any web address where I could find these data? I am not native to this field, so I don't know how do these quantities change with...
14. ### Mathematica How to simplify an expression in Mathematica

We were calculating Lame's coeficients for some coordinate system. We had these data: x=a*Cosh[B]*Sin[P]*Cos[F] y=a*Cosh[B]*Sin[P]*Sin[F] z=a*Sinh[B]*Cos[P] The first coeficient (let's call it f1): f1=Sqrt[(dx/dB)^2+(dy/dB)^2+(dz/dB)^2] The second...
15. ### Mathematica How to simplify an expression in Mathematica

a*Sqrt[(Cos[x])^2+(Sinh[y])^2] is what I've got on paper and that is not related to the first problem. The first problem was that mathematica couldn't simplify this: Sqrt[a^2*(Cosh(x))^2*(Sin(y))^2]
16. ### Mathematica How to simplify an expression in Mathematica

What is true if that's not true?
17. ### Learn 8051 Microcontroller: Find Examples & Applications

We learn it at processor systems in telecommunications. It seems interesting so I would like to get some more resources to learn.
18. ### Learn 8051 Microcontroller: Find Examples & Applications

Hi, I have just started with learning about 8051 microcontrollers. Does anyone know some website where I could find examples of written applications? Regards, Niko
19. ### System Modelling: Books & Resources for Real Life Systems

Hi, Recently I have started with learning mathematical system modelling. I seems very interesting so I am looking for books to learn more. Could anyone recommend some good books or some web address about doing mathematical models for real life systems (engineering, economics, human...
20. ### Mathematica How to simplify an expression in Mathematica

On Sqrt[a^2*(Cosh(x))^2*(Sin(y))^2] FullSimplify doesn't work. It returns the same expression.
21. ### Mathematica How to simplify an expression in Mathematica

Hi, I have got this expression from Mathematica: Sqrt[a^2*(Cosh(x))^2*(Sin(y))^2] I have tried to simplify this expression with Simplify[], but it returns the same result. I have tried to solve some other expressions and it returned some strange forms. For example: I have tried to solve...
22. ### Mathematica Reliability of Mathematica

It still doesn't work. I get this result: Sqrt[a^2*Cosh[x]^2*Sin[y]^2]
23. ### Solving the Puzzle: Cow Rope Length in Round Meadow

Meadow is rotund, not rectangular. The radius of the meadow is whatever size. We have to find a relation between rope length and radius length. Assume the radius length is 1.
24. ### Solving the Puzzle: Cow Rope Length in Round Meadow

Hi, I have tried to solve this puzzle: If we had a round meadow and a cow tied with a rope on the edge of that meadow. Hw long should be a rope if we wanted to let the cow eat a half of that meadow? I have tried to solve this puzzle time ago and now it attracted me again. Does anyone know how...
25. ### Mathematica Reliability of Mathematica

Thank you. Maybe the result isn't different but it isn't simplified. I am sure I haven't done any error with my calculations. Something that also seems strange is that Mathematica gave the result in note like this: Sqrt[a^2...] I have put FullSimplify command but it hasn't changed. Anyone...
26. ### Mathematics for electrical engineering

Hi, I study electrical engineering. I have passed the exams of mathematics and I don't have classes of mathematics anymore. Although I have passed mathematical exams with high grades, I have forgotten many things since I don't learn these things separately. Actually a quick look at the notes is...
27. ### Mathematica Reliability of Mathematica

Hi, Recently I was doing some calculations with Mathematica then I did it on paper and the results weren't the same. I am almost sure I didn't make any mistake. I study electrical engineering and we have to do a lot of calculations. I have used Matlab and Mathematica for calculations with...
28. ### Generate Silence: Can We Attain Total Quiet?

Yes, but that sound isn't much complex. Actually I was tinking about realizing a room with two melodies playing each in a part of room without mutual disturbance.
29. ### Generate Silence: Can We Attain Total Quiet?

Hi, I'm wondering If we could generate homogeneous sound field and if we put two sound sources which would have inverse phaze we could attain silence. Is it possible to do that? Is it possible to generate homogeneous sound field in a room full of moving objects (people)? Regards, Niko
30. ### Satellite guided airship

Hi, I study electrical engineering and I was thinking about some projects. I was thinking about constructing a guided zeppelin. I would also add a GPS so I could program its course. I was thinking about the possible problems. I don't know how could it be controlled in the case of wind. I...
31. ### Second norm of matrix

Hi, I have forgotten the formula for calculating the second norm of matrix. Does anyone know the formula? Regards, Niko
32. ### Calculating mass and speed from kinetic energy and linear momentum

I don't know if the first equation is right: E = mr*c^2 = m0*c^2 + K, where mr = relativistic mass and m0 = proper mass, so I thing this can't lead us to the right soluton. When I was doing this exercise I have got the speed greater then speed of light, so it's not right. I have probably made...
33. ### Calculating mass and speed from kinetic energy and linear momentum

Hi, I have tied to solve an exercise where I have kinetic energy and linear momentum and I have to calculate the speed and mass (not relativistic mass) I have these specifications: Wk = 5713.13 MeV P = 6584.92 Mev/c0 I have used these formulas: Wk = mc^2*((gamma)-1) P = (gamma)*m*v I...
34. ### Splitting a Matrix with Choleski Method: A Simple Example

Hi, Could anybody describe a procedure for splitting a matrix using a choleski method? Could anyone show this on a simple example: Let's say we have a matrix A: [2 1 0 0] [1 2 1 0] [0 1 2 1] [0 0 1 2] and matrix b:     How to get x: Ax = b using abovementioned method?
35. ### Splitting a Square Matrix into Lower/Upper Triangular Matrices

I have done the way HallsofIvy has shown me and it works. This question is out of place here, but anyway...I have listened to the discusions on the forum and I must say your answers are really practical and easy to understand. Before giving this question I was looking at my notes to find an...
36. ### Splitting a Square Matrix into Lower/Upper Triangular Matrices

I have already found a mistake: I have changed first column too instead of leave it unchanged.
37. ### Splitting a Square Matrix into Lower/Upper Triangular Matrices

I have tried this procedure on this one: [3 2 5 1] [6 6 15 3] [-3 4 13 1] [-6 6 15 15] and I couldn't come to a right solution After first step I got this: [1 0 0 0] [3 2 5 1] [2 1 0 0] [0 2 5 1] [-1 0 1 0] [0 6 18 2] [-2 0 0 1] 0 10 25 7] After second step I get L and U, but...

Thank you!
39. ### Splitting a Square Matrix into Lower/Upper Triangular Matrices

Hi, Does anybody know the procedure for splitting a square matrix into lower and upper triangular matrix? LU=A Thank you. Regards, Niko
40. ### Older faster if the universe wouldn't be expanding?

The question was incomplete. We wouldn't feel any difference in any case, but time would run faster. That's the thing I don't know...what could we compare with our time?
41. ### Older faster if the universe wouldn't be expanding?

Would we be getting older faster if the universe wouldn't be expanding?
42. ### Speed of two spaceships

The result in a book is equal 0.93c
43. ### Speed of two spaceships

Hi, I am doing exercises regarding relativity. I know how to calculate relative speed in one dimension, but I have some problems with the relative speed in 2D. If we have two spaceships, one is moving in the x direction with speed 0.7c and one is moving in y direction with speed 0.85c. What...
44. ### Divergence of Electric Field

Hi, I have passed the exam of vector analysis time ago, so I hope I remember right: If we have a solenoidal field (field without source) then the divergence of this field is equal 0. If that's true then the flow through the closed surface is equal 0. If we have a charge inside the sphere...
45. ### Wave optics of reflection

Hi, Right now I am solving some exercises in connection with wave optics. If we have three layers of different materials (ex. air, gasoline, water) and we send a light ray through these layers and we calculate the wave length of the reflected rays, then we use these formulas: D = N*l; (D =...
46. ### Description of bipolar and unipolar transistors

I hope you will understand what I write, because English is not my primary language so I don't know translations for technical words. I don't clearly understand how to calculate recombinational current. I think I don't understand clearly what is happening in the transistor when we connect it...
47. ### Description of bipolar and unipolar transistors

Hi, Does anyone know any website with description of bipolar and unipolar transistors (analysis of DC U-I characteristic...) Regards, Niko
48. ### Find Solve Real-Life Engineering Challenges Here!

Hi, I study electrical engineering and I would like to face some real-life problem and try to solve it. Anyone knows any web page where I could find some contests regarding mathematics physics or electrical engineering? Any Information would be helpful. Regards, Niko