Elements Definition and 984 Threads

The Kronecker product of an argument X and a 2x2 matrix, increases the dimensions of each argument X individually. If each argument X is a scalar value, it now becomes a 2x2 matrix. How are these arguments now aligned with each other and the other elements in the resultant matrix? For...

Dear Friends, I have a question and would be pleased if you help me by suggesting a paper or book to study. Let A={1,2,...,n}. We consider all the subsets with k elements. How many of these sets have a sum of r ? e.g. for n=6, k=3, r=10 {1,3,6} {1,4,5} {2,3,5} Hense the...

The general problem I'm trying to solve is the probability of rolling a total t on n s-sided dice. A good chunk of the problem is easy enough, but where I run into difficulty is this: How many combinations of dice will yield a sum total of t? Because the number set is limited, {a \choose n-1}...

i need examplees where the ricci scalar is constant but nonzero . Particulary i search examples of line element. Pd: this is not a homework,

I am working with the Keplerian Elements from the JPL web site. a - Semi-Major Axis e - Eccentricity I - Incilination L - Mean Longitude long.peri. - Longitude of the Periapsis long.node.or N - Longitude of the Ascending Node http://ssd.jpl.nasa.gov/txt/p_elem_t2.txt From this...

Homework Statement a sample of 0.6 moles of a metal M reacts completely with excess of flourine to form 46.8 gms of MF2. a)how many moles of F are present in the sample of MF2 that forms? b)which element is represented by the symbol M? Homework Equations NO. OF MOLES=given mass/molar...

Hi, I have been trying to solve a system consisting of 3 linear spring elements using the Newmark's method to find displacement, velocity and acceleration in Matlab. I followed the instructions shown on page 5 of the paper attached and my code does not seem to be working as the displacement...

I am doing a nonlinear analysis in, Ansys Workbench, of a fuel tank tied down in an aircraft using cargo straps. I need to know how to insert a command function in Ansys workbench 11 that creates compression only elements (in order to model cargo straps). Based upon what have been reading I...

I have a 100x1 vector A, and want to know the ten indices i for which A(i) are the greatest 10 values in A. I can find the values by: B = sort(A) B(1:10); But I don't know how to find the indices, apart from starting a new if loop which searches the entire matrix (which seems very time...

Homework Statement The orbital elements (a,e,i,w,Omega,f) are to be integrated forward in time using two methods: 1) Cowell's method, which is direct interation, and 2) Gauss' Variational diffeential equations. The full assignment description, initial conditions, and my code are given in the...

what is exact reason behind choosing basic primitive shapes for elements in FEA? Why it can't be hexagonal, pentagonal, octagonal, etc. in both cases 2D and 3D... Thanks in advance...

Hi all, I need to figure out the mathematical notation to multiply matricies A and B = C so that... If matrix A is... a1 a2 a3 a4 a5 and matrix B is... b1 b2 b3 b4 b5 so that matric C is... a1*b1 a2*b2 a3*b3 a4*b4 a5*b5 Would this involve using a the transverse of a...

Hello! I'm doing a simulation in ansys workbench mechanical (12.1) of a cantilever beam (axle) fixed to a wall and loaded radialy at the other end. The funny thing here is that when the mesh is rather coarse the results regarding von-mises stress (at the support where the bending moment is...

Homework Statement Let p be a prime and let H be a group of order p^n, some n > 0. Prove that for any x not equal to 1 in H, some power of x has order p. Homework Equations -- The Attempt at a Solution I know that by lagrange, for any x in G, if x is not the identity, then x has an order p^r...

The question: Let n > 1 be a fixed integer and let G be a group. If the set H = {x in G : |x| = n} together with the identity forms a subgroup of G, what can be said about n? I know that n must be prime, but I can't figure out why that would be. The elements of h only have order 1 or n...

RE-EDIT: I'm confused again, continue on reading :redface:Bonjourno, I'm trying to work at the lectures provided on youtube by nptelhrd but I've gotten my foot stuck in a hole in the real line only 15 minutres into it :frown: [SIZE="1"](In my head I say "such that" whenever the symbol : pops...

I was going over a proof in which the following is given: if abb=bba and b is of odd order, then ab=ba (i.e. if b^2 centralizes a then so does b) I'm not sure why this is so. Any clarification would be appreciated. Cheers, W. =)

If you have a subgroup and it's order how do you find the elements of the group? I'd be happy with any example to help explain this, but just so there's something to go off of my example would be if you have a subgroup A4 = <(1 2 3), (1 2)(3 4)> of S4 that has an order of 12 how do you find...

Well, \langle j,m|S^2_{-}|j,m\rangle=\langle j,m|(S^2_{-}|j,m\rangle) and S^2_{-}|j,m\rangle=S_{-}(S_{-}|j,m\rangle)=___? Normally J_+*J_- is substituted as J^2 - J_z^2+hbarJ_z As described above, J_+(J_-J_+), wouldn't the content in parenthesese just cancel out to 1 ?

I heard someone suggest a correlation between the two, my guess is NO direct correlation exists. Pick an Element on the periodic table, hardness and density do not always correlate. I'm sure atomic lattace structure plays a larger role here. Diamond is the hardest, but by no means high in...

Homework Statement I'm working on problem 3 on page 136 in Landau and Lifgarbagez Quantum mechanics nonrelativistic theory. The problem is to determine the energy levels of an anharmonic linear oscillator with H=H0 + a*x3 + b*x4 (where H0 is the hamiltonian of the harmonic oscillator)...

What if you had a large and very hot sphere (made of a a thick alloy/material with a higher melting point than any of the elements) and you fired in the 94 natural elements to collide in equal parts in the center and make a ball that fits the sphere? The solid elements would be in a powdered...

Hello everyone I was wondering if someone can check out my answers thanks! 1. A cotton ball is dipped in alcohol and wiped across a tabletop. Explain what happens to the alcohol molecule deposited on the tabletop. Is this a physical or chemical change? The alcohol molecule evaporates...

Homework Statement I was just wondering if say A is a 2x2 matrix. Is A^2 equivalent to AxA or all the elements of A are squared? Homework Equations let A and B be 2x2 matrices. is the following true? (A-B)(A+B) = A^2 - B^2 The Attempt at a Solution

Hi everybody. Can I just start off by saying how much I enjoy reading all your posts and trying to increase my scientific knowledge. But now its time for me to ask my own questions. I've just finished watching a programme about elements and was wondering. 1.what use do we have of some of the new...

How many generations of stars were required to make the elements found on Earth. In other words, does a star have to be born with heavier elements for some even heavier elements to form?

I have this question and its a combination of the binomial theorem and nilpotent elements within a ring. Suppose the following, am=bn=0. Is it necessarily true that (a+b)m+n is nilpotent. For this question I did the following: \sumi=0m+n\binom{m+n}{i}am+n-ibi If i=m, then a=0...

Homework Statement Hello, could you please explain to me in simple terms how I can predict the chemical formula of the compounds produced when Group 7 elements are reacted with the elements in Group 1. Thanks. Homework Equations N/A The Attempt at a Solution N/A

Here is my problem: i have group defined by generators, like: < a, b | a^2 = b^3 = (ab)^5 = 1 >. eg. from http://for.mat.bham.ac.uk/atlas/v2.0/alt/A5/ i can't find algorithm to enumerate all element of group ( 60 in this example ) based on generators. thanks for any help :)

Can anyone explain to me why actually are some elements radioactive? I have the explanation in my textbook but i want to know the main reason why these elements are not stable...

I have the following problem: Suppose I have a set called "the white chess pieces on a chess board". I could say the set contains the following: king, queen, rook, bishop, knight, pawn. This means the set contains 6 elements. I could also say the set contains: king, queen, 2 rooks, 2 bishops...

Homework Statement If some conjugacy class of an element in a group G contains precisely two elements, show that G cannot be a simple group. The Attempt at a Solution This question was longer, with two questions before this one which I could answer and which probably lead to the answer on...

I was reading something the other day on spectral readings from the sun, and I have a few questions regarding its composition. I know that there are heavier elements (gold, uranium, etc.) in the sun. I'm confused by this, as I didn't think there was enough energy to form such elements. My...

I know that I'm told that the heaviest elements can only be created in massive supernovae. Is this just theory, or have we created, in labs, lighter elements in scaled down collisions/explosions?

Hello, I just have a quick question about Quantum Mechanics. It's probably a bit basic but I'm trying to get my head around the off-diagonal Hamiltonian elements of a perturbation. We can assume the unperturbed Hamiltonian to be degenerate. If I have a Hamiltonian H=H_{0}+H' where the...

Hi all, as title, how to take the power of elements of an array to, say, 5? I know how to do it using loops, but would it be very troublesome if I have to do it a thousand times? Any ready made function in fortran90? I hope there is... I have googled it quite a bit, but seems nothing useful.

How many groups size m can you make from n elements (m<n) such that each element is used the same number of times t (t>0)? For instance, if you have 8 teams and group them in triplets, how many triplets do you need so that each team plays the same number of times?

Are group 16 elements more likely to form ionic or covalent compounds, and what is the most common type of ion they will form? Since they are nonmetals and have a negative charge, I am thinking they are more likely to produce ionic bonds and will form bonds most commonly with group 1...

If we call <a> the "span" of a, then I need some clarification on the concept of span. def. if G is a group and a∈G, then <a> denotes the set of all integral powers of a. Thus, <a> = {a^n : n∈ℤ} thm. Let S be any subset of a group G, and let <S> denote the intersection of all of the...

I'm wondering how the group S_n can act on a set with more than n elements? I'm basically only looking for some idea as to how to get started on describing such an action and how to think of that action. Thanks

For any two elements A and B that form AB, neither A nor B have to be invertible for (AB)-1 to exist, right?

I didn't know where to start this so move it as needed, I have seen a bunch of "odd" info about monoatomic metals (mainly gold) and thought ya'll could answer some questions. exactly what is monoatomic? can gold, or any metal be made into a monoatomic element? is it indeed a...

Dear all, I'm trying to figure about an efficient way to to get the redundant element in my array. For instance, let's take the array [0,2,3,0]. I'd like to get out [2,0,3] (or 3,0,2 it doesn't matter). So it find out which element is duplicated, an puts its value in between the 2 other...

if you have an array with size 1000000, would selection sort be feasible on a everyday laptop computer, or just too large? I imagine it would take (1Million)2/2 loops to complete the sort

Hi, There are some points I really want to clear up in this topic...I promise to finish my chain of doubts as quicly as possible! I'll put in my first questions... 1. Rotoinversion is a combination of inversion and rotation-- often it ends up as having the same effect on the crystal as...

How do we go about finding the number of elements of a cyclic subgroup that's generated by an element in the main group. For example: The subgroup Z30 generated by 25. I would think this subgroup would be {0,1,5,25} but there's supposed to be 6 elements and not four. Whats going on?

Suppose G is a group, a,b are two elements of G, does o(ab)=lcm(o(a),o(b))? o(ab) denotes the order of ab, lcm(o(a),o(b)) denotes the Least Common Multiple of o(a) & o(b).

Homework Statement suppose that G is a group in which every non-identity element has order two. show that G is commutative. Homework Equations The Attempt at a Solution IS THIS CORRECT? ab=a[(ab)^2]b=(a^2)(ba)(b^2)=ba

Homework Statement The following elements should have optical spectra similar to either a hydrogen atom or a helium atom. Indicate which of the following elements should have optical spectra similar to a helium atom. (Select all that apply.) The choices are: Cadmium, Lithium, Technetium...

Homework Statement suppose that G is a group in which every non-identity element has order two. Show that G is commutative. Homework Equations The Attempt at a Solution Is my answer correct? Suppose that a,b and ab all have order two. we will show that a and b commute. By...