Structures Definition and 324 Threads

I need advice with my "Discrete Structures" class Hi everyone, I'm a sophomore undergraduate student at the Polytechnic University Of Puerto Rico, currently majoring in "Computer Engineering", for the record this university works by trimesters. I'm currently getting a bit frustrated with my...

M\equiv N means M and N are elementarily equivalent, that is, for any setence S in the language of M and N, M\models S \Leftrightarrow N\models S. An elementary embedding f:M->N is a mapping f:|M|->|N| between the underlying sets such that, for any formula t(x) and matching tuple y of elements...

what is effective mass? and how does it effect both the electrical and optical properties of a crystaline structure?

Hello guys, I was wondering: say you have a structure: struct tag{ int a char b int b int c } how would you make int c equal to int a + int b for all variables of type struct tag? I have tried using pointers but it baffles me how you would make a global change in that all...

Has anyone here taken this class before? I've been in this class for two weeks, and I still can't get a feel for how difficult or time consuming it may be. My instructor keeps mentioning discrete mathematics (which I haven't taken), although it wasn't a prerequisite for the course. Additionally...

Does 'category theory' link different mathematical structures? Can you give a superficial example of how this has been done (eg. Name two mathematical structures and, with waving of hands, explain how they have been linked)? Could you direct me to a link where this has been done elegantly in...

[SOLVED] Resonance Structures 1. Homework Statement [/b] Draw the major resonance contributors that show electron delocaliztion of the formal charge for the following ions, The conjugate base of .O .||... NH2 /..\ /...\\ / ...||...| ... \...//\ ....OH 3. The Attempt at a...

[SOLVED] Organic Chem - Resonance Structures #2 Homework Statement Trying to figure out this resonance structure...Draw the lowest energy alternative.. http://img162.imageshack.us/my.php?image=553562cu7.jpg The Attempt at a Solution ive been trying to move the upper double bond...

Does anyone knows how to solve the following eigenvalue equation using matlab? so as to obtain the energy levels in a quantum well structure.. or does anyone has the codes or knows where to find the codes to do so? Eigenvalue equation: tan(sq_root(2mE/hbar^2)*(d/2)) = sq_root((V-E)/E) for...

Does anyone knows how to solve the following eigenvalue equation using matlab? so as to obtain the energy levels in a quantum well structure.. or does anyone has the codes or knows where to find the codes to do so? Eigenvalue equation: tan(sq_root(2mE/hbar^2)*(d/2)) = sq_root((V-E)/E)...

Hey guys Im having problems figuring out this Statics question I feel like I can solve it, But it has been bugging me for weeks Here it is. and Here is a quick FBD and notes I posted from others Would Anyone let me know If the FBD is correct? Im not asking for the answer. I honestly just...

"]Dear all; I have this assignment in data structures, and it needs for a lot time to solve it by myself really I'm buzy and I stick on it for A long time, I want it as soon as much anyone can:cry: Regards; LoLO:blushing:

Homework Statement A rectangular two-story building with a wood roof and floor system and masonry walls is analyzed to determine seismic forces. Given: I=1, roof dead load D=15psf, floor load=25psf including partition load. Exterior wall dead load D=80 psf along both long and short walls...

Homework Statement A 10 storey building has columns spaced on a 8m by 10m grid. a) Calculate the reaction at the base of an internal column assuming a 300mm thick concrete floor slab and a live load of 3.0kPA (ignore self weight of column and assume concrete density 2.4t/m^3 b) Assuming...

c++ data structures! please help! i want to write a c++ program that implements a binary search tree from an infix expression. the program should perform the following: -the expression should be saved and read from a file. -use a stack to check if the expression is well formed in terms of...

Hi, I'm having trouble figuring out which of the following molecules can be described using three charge-minimized resonance structures. Does anyone have any idea which molecules this would include? a. SF4 b. SO3 c. SO32- d. HSO4- e. SO2+

I have a test after a few days and I face agreat deal with some concepts. Really I don't understand the crystal structure? how we know the Bravias lattice and how we get the primitive vectors and how we know the cells that make the lattice Bravias if it not? I want very clear...

The question/direction is to: "Draw the structure of the following compound!" 2-methyl-4-(1-methylethyl)octane I tired several different ways of constructing this compound but the online homework program ACE Organic says that: I don't know what to do or what I am missing. If anyone can...

Another question: How do we define compatibility of atlases and a maximal atlas? why do we need to define them? How do we conclude for example sphere and circle have 1 differential structure? ( I said "another question but it turn out to be questions")

Hi all, Recently got to thinking about electrostatics and electron densities and band structures. If you have an electrostatically charged piece of material, say for example, a metal, does the density of states of that metal change because of the depletion of electrons? Alternately, if...

Is there any way to predict what crystal structure a pure metal element will be? It seems that the simple 'electron sea' idea does not explain a lot of things. Thanks -scott

What has mainstream decided is the arrangement of the protons and neutrons in the nucleus of the atom? Lattice or cluster structures or ? jal

I am looking for informations about CoIr alloys. Who can tell me about crystal structure, lattice parameters of CoIr alloy? Please share me some references about this material. Thanks! :!)

I'm currently in my final year of high school, doing physics. We have been given an assingment about bridge structures. Basically, we build a bridge out of spaghetti, test it and discuss it. I'm thinking of things in which I can talk about. I've built an Arch Design Bridge. Mainly due to...

hi :biggrin: please help. thankyouuu :] Homework Statement i am studying for my apchem exam in may.and got stuckup on a question. it's just a little exercise.so the answers aren't there.but ok here it is; give the resonance structures of PO4 (3-) and there's supposed to be four Homework...

I was curious if anyone has this as a job/major? I'm 100% sure I'm going into it. I haven't done any job shadowing =(. I really want to, but, I personally don't know anyone who does it. For those who do it: How are the working conditions? I heard you work with a lot of people also. I was...

Hello - I am searching for some guidance, and I would greatly (greatly) appreciate any tips, pointers, etc. I am interested in the stability and geometry of nanoscale carbon structures, such as fullerenes and single-walled carbon nanotubes. I am wondering where to begin to develop - for my own...

Hi - I expect this is quite a simple question. What are fortran structures? I'm trying to convert fortran code into MATLAB and I don't know what a structure / endstructure statement is. e.g. structure /pixel/ union map INTEGER*4 cl INTEGER*4 rw endmap map INTEGER*4 x INTEGER*4...

Homework Statement HI, I'm working on this: If n>m, prove that there is a homomorphism of F^(n) onto F^(m) with a kernel W which is isomorphic to F^(n-m). Homework Equations Def: If U and V are vector spaces over F (a field) then the mapping T of U onto V is said to be a homomorphism...

Homework Statement We need to draw the Lewis structure for certain compounds, such as C2H3Cl. Homework Equations None. I know how to draw Lewis structures, but I have a question: How do we know how to distribute the available valence electrons? For example, in drawing C2H3Cl, the right...

I don't think the problems I'm going to post are very difficult, but I'm totally clueless regarding chemistry, so they're pretty difficult for me ^^;; I also have a lot of questions to ask, so I hope you don't mind my sticking them all into one topic. I'm looking forward to your help. You don't...

I'm doing a practice exam that I have answers to, but I'm not sure how to go about getting to the right answer for some. Homework Statement A nitrogen laser produces pulses of light of wavelength 337.1 nm. If each pulse contains 10.0 mJ of energy, how many photons are contained in one...

I'm a math structures class at my college and even though i think the class is pointless its required for my degree and i have to take it. There is a problem in my book that I don't understand how to answer. The problem is: Determine each of the following without actually performing the...

Hi, I'm confused by resonance structures of molecules, what are they really? My teacher said resonance structures are in fact a decomposition of the actual molecular wave-function as a sum of simpler ones. Is this true? Or are they in fact simply pictures we draw when we can not classify the...

Can anybody help me understand how pauli's exclusion principle helps explain the existence of fine line structures in the emmission spectra for atoms, which could not be explained by Bohr's model.

Not too long ago, there was a thread in the General Physics section (I think) where someone was asking about how large buildings are evaluated from a modal analysis perspective. It was my experience that large structures had a completely analytical approach with some scale modeling. This...

What man made structure (large scale) can endure the longest time, i am not thinking pyramid more an/or more oom longer.

Most structures we see in the universe are of a spherical or circular nature. However, our universe is most likely hyperbolic (saddle-shaped) overall. Is it possible that there exist material structures on the large scale that manifest hyberbolic geometry?

I know I am overthinking, as always, but for some reason I am just having so much trouble with picturing the 3-d structures (dash/wedge) when solving the problems. My test is tomorrow and I am stuck, I just can't draw them correctly...I get the hybridization, and the angle that will form. What...

I'm trying to create this program that allows the user to create and manipulate trees. For example, a user might create a new tree with a node containing "words" as its data, then create nodes containing "nouns", "verbs", "adjectives", etc. as their data. The problem is I don't know how to...

I'm looking for structures of ogliosaccarides and homo/heteropolysaccharides but I seem to not be able to come across any. I did searches and checked texts but unfortunately they weren't very helpful. So, can anyone tell me where I find such structures, possibly online? Thanks.

http://img222.imageshack.us/my.php?loc=img222&image=86zg.jpg Now... that monster also known as the first mobile skyscraper.. costs a small fortune... or well, a large fortune... very large... $100,000,000. Now I must ask with things like these... why are they built? Now I could hear things...

Hi, I found out that Kevlar is a crystalline structured polymer, and this is one of the factors about why its so strong. Could someone explain to me why crystallinity affects strenght? Thanks.

I have 2 homework problems.. 1. Draw the Lewis structures for the reactants and products in the neutralization reaction between NH4Cl and NaOH. You may omit spectator ions. According to a Precipitation diagram in my book, it shows that all the elements are spectator ions, or is this...

OK, I am having some issues with some trusses. The first one is a platt truss, h = 8 m, length of horizontal beams = 8 m F = 340 kN occurs at each of the 5 pts between the supports, one is a pin, the other is a roller. I get the force in a diagonal to be ~240 kN, but the answer in the...

1) The CO3 (2-) ion has a maximum of a.two resonance structures involving two single bonds and one double bond. b.two resonance structures involving one single bond and two double bonds. c.three resonance structures involving one single bond and two double bonds. d.three...

Lewis Structures... Is there any place on the web that I can check to make sure I am doing my Lewis structures correctly?

Hi, Did some one calculate the dispersion characteristics of TM volume modes in layered magnetized semiconductor structure?

How many elements are in a sub1 intersect a sub 2 which equals a null set when a sub 1 =12 and a sub2 = 18

In the problems below A[1, ..., n] denotes an array consisting of arbitrary n real numbers, and A[j] denotes the element in the j-th place of the array A[1, ..., n]. 1) Let k be a fixed natural number. Consider the family A_{k} of all arrays A[1, ..., n] satisfying that for every i ≤ n there...