What is Structure: Definition and 1000 Discussions

A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as biological organisms, minerals and chemicals. Abstract structures include data structures in computer science and musical form. Types of structure include a hierarchy (a cascade of one-to-many relationships), a network featuring many-to-many links, or a lattice featuring connections between components that are neighbors in space.

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  1. Mayhem

    Theoretical Possibility of a N-methyl Polymer Structure

    Out of sheer curiosity, would a polymer of the following structure be theoretically possible? Imagine that the "N-methyl" groups are just the bounds of what is shown, and not actual carbon-containing substituents... It doesn't seem to break any elementary bonding rules. However, the C-C bond...
  2. E

    What is the structure of FOOOF and FOOOOF?

    FOOF looks like this: This paper suggests that FOOOF also exists but does not give a structure, although it does state that it's unlikely it takes the F-O-O-O-F structure. "Ignition: An informal history of liquid rocket propellants" claims that this series of compounds, up to FOOOOOOF, can...
  3. F

    Springs, how they work, their coiled structure

    Hello! Springs are amazing devices: we take a straight piece of metal wire, we change its shape and get something that can compress or extended a finite length. We could not do that with the straight wire (too difficult to move atoms apart or close to each other in a significant way). Why does...
  4. docnet

    Asking questions about protein structure determination

    Hi, I tend to write down questions/thoughts that come to me as I read articles that are interestsing. I'm reading the intro to solution state NMR in a biophysics textbook. Any there any purely theoretical approaches to determine protein structure / dynamics ? The 1 dimensional digital code...
  5. anonymous99

    How does an FCC structure have a coordination number of 12?

    Edit: nevermind, I realized my mistake. Corner atoms don't touch in FCC, so there's just 4 neighbours in each plane which sums to 12.
  6. Y

    Please help solving this problem: Reading & Writing Records in a Structure

    Hi I have a funky problem I have been working on for over a day, it is supposed to be quite simple, but I have funny result. What the program does is to pick out one of the five records(of structure) stored in the file, modify it and store back into the file in the same position. It supposed to...
  7. F

    Python Problem with coding the band structure of graphene nanoribbons

    Hi, I have a Matlab code for calculating the band structure of graphene nanoribbon which is working fine, but I wanted to convert it to python and I've done it. I guess I made a mistake somewhere because the plot is totally wrong. Could someone check it for me, please?
  8. Y

    Verify a pointer to a structure that contains a pointer member

    Hi I am working on Chapter 11 Structure, this is pointer of structure where the structure has a member that is a pointer variable. I just want to run by you guys to make sure my understanding is correct. Below is a program I wrote for verification. It works...BUT I afraid it's like last time...
  9. mfb

    A Spectroscopy of positronium fine structure: 4.5 sigma deviation

    Precision Microwave Spectroscopy of the Positronium n=2 Fine Structure A nice compact abstract, so I'll just quote it here: Positronium with its two light leptons is the dream of every theorist, that keeps the uncertainties small. The 0.61 MHz experimental uncertainty are the sum of 0.57 MHz...
  10. Vigardo

    Buckling and modal FEA of a submarine structure

    Dear FEA experts, I'm trying to model the mechanical behavior (static, modal, and buckling analyses) of an underwater floating structure (e.g. submarine capsule or buoy) under hydrostatic pressure by Finite Element Analysis. To obtain feasible results, the structure should be modeled as freely...
  11. B

    Truss structure square problem

    Here is the full question. I have already tried to answer the questions and have put a red dot next to the answers I think are right? Here is my working out to get the answers I had above Have I done this question right? Sadly I don't have the answers to check for myself here so I'm...
  12. P

    Structure adding rotational stiffness to a plate

    I'm 3d-printing a part that is 110mm x 40mm (XY-plane). I have to keep it light weight, so I made it thin - 0.6mm (Z direction) and filled the surface with holes to remove as much weight as possible. Then I added a grid of 2,5 mm high "walls" in the XY directions to make it stiffer and a couple...
  13. P

    Understanding Bending Moments and Moment Equilibrium in Structural Analysis

    I have a quesrion about forming the eqaution of moment equilibrium. As shown in the picture at cut 1 there are 2 vertical forces and a bending moment. I expect V=A. If I apply moment equilibrium about the point where the bending moment is, we get that Ay*x = M(1). But how about if I take moment...
  14. sergey_le

    The most likely structure from combinations of these atoms

    an element (we will call it X) got a cofiguration of 1##s^2##2##s^2##2##p^6##3##s^2##s##p^3## what molecule is moste likely to happened between this element and Mg? 1.MgX 2.##Mg_2##X 3.Mg##X_2## 4.##Mg_3## ##X_2## how do i do it?with lewis structure?just check what structure makes the most...
  15. rachelmaddiee

    Chemistry CH2O Lewis Structure: Verifying the Correctness

    Is this the correct lewis structure for CH2O?
  16. P

    Engineering Structure Mechanics-Three Pinned/Hinged Arches

    The Example 2 at this site ' http://ocw.ump.edu.my/pluginfile.php/1435/mod_resource/content/2/Chapter%205%20%E2%80%93%20Three%20Pinned%20Arch.pdf ' (page 14): It is parabolic hence the equation is y = (x^2)/10. I used the section method between A-D and applied equilibrium of moment to find a...
  17. Haynes Kwon

    I Determining Degenerate Gas in Stellar Structure

    When modeling stellar structure and formulating equation of states, I've seen various cases where you have to take into account whether the constituent gas of a star is degenerate or not. But how do you determine if the gas is degenerate or not?
  18. S

    Find the sampling matrix and sampling structure for R, G and B components

    Hello, everyone. :) All I could gather is that, if I'm correct, lattices are spans of the column vectors of the matrix within the "LAT()" notation and the X and Y occurrences are unit placeholders (such as the pixel unit (since this is in the context of image processing)). And, as an attempt...
  19. Indula

    A Why does a layer-like structure occur in a cold plasma?

    I have observed a layer like structure (made of plasma) in a cold plasma and wonders what causes it. Following image shows the observation.
  20. L

    Need a Hand Calculating the Maximum Load on a Structure

    Basically looking to find out what the maximum amount of load you could put on the center of a structure like this would be, in theory. Top Beam: The top "Beam" of the assembly in the drawing is 3"x 3"x 3/8" square tubing, 112.5" long Supporting Beams: The beams supporting each end of the Top...
  21. L

    B Structure and Dynamics of Blue Supergiants

    There seems be much understanding of the internal structure the Sun for instance its several layers,thecore, the radiative and convections zones, the corona and so forth. What is known about stars that are not like the Sun? I was particularly thinking blue or red super giants.
  22. Frigus

    Aeroplane wing structure -- airflow question

    Why the air splitted at point a of aeroplane wing's cross section meet at point b simulatneously,
  23. Nik_2213

    Technical term for this material structure?

    A massive rocky material that is connected open-cell, macro-porous at surface, but 'vesicles' shrink to closed-cell then solid as you drill deeper: What's the technical term for such ?? == Writing a SciFi tale, I'm trying to describe a large, alien-ish rock formation. I've a vague recollection...
  24. D

    Structure of code for ODE solution in Octave

    The problem of interest at the moment is the solution of a simple damped oscillator problem, xddot+2*zeta*wn*xdot+wn^2*x = 0 Everything seems to work fine provided I include the values of zeta and wn inside the function that defines the derivative values. But zeta and wn are actually calculated...
  25. Sanborn Chase

    B What Fills the Space Between the Nucleus and Electron Shells in an Atom?

    Summary: The Space Between the Nucleus and Electron Shells? What composes the space between an atom's nucleus and its electron shells?
  26. cynth

    A Electronic band structure of iron superconductor BaFe2As2

    how can I determinate the electronic structure of a multiband system? for example in the case of the superconductor BaFe2As2 , the electronic properties are as known dominated by 5 Fe d states at the fermi energy, so 5 bands cross the Fermi level and form 5 Fermi surface sheets (if we consider...
  27. F

    Finding torque around a structure

    Hello All, I am designing a robot that has these dimensions, I need to work out the torques around T1 to T6, I am unsure of the best way to do it, ie do I do a net torque calculation around the torque to be found or is there a better way. W1 to W4 = 0.53955 kN W5 = 14.44032 kN W6 to...
  28. M

    I What happens in the molecular structure of a liquid (imcompressible)?

    Suppose you have a liquid with high potential energy at a height [H] in a first moment. In a second moment, the liquid loses its potential energy (that is converted into kinetic energy) and fall in a cylinder at height [h] .IF the liquid is incompressible what happens with the molecules in the...
  29. maajdl

    A Getting structure data from a partition function?

    Hello, From wikipedia, this is the partition function for a "classical continuous system": This is the pillar of classical statistical physics, but it can be seen as a mere kind of "mathematical transform" . It can be used even without thinking to statistics or temperature. If we focus only...
  30. amjad-sh

    Band structure of a 2deg including spin orbit coupling

    first of all, I tried to obtain the energy eigenvalues of the Hamiltonian, by using the equation ##det(\hat H -\lambda \hat I)=0## ##\gamma V\delta(z)(\hat z \times \mathbf{p}) \cdot \sigma=\gamma V\delta(z)(p_x\hat j-p_y\hat i)\cdot(\sigma_x\hat i + \sigma _y \hat j)=\gamma...
  31. Math Amateur

    MHB Understanding Stromberg's Theorem 3.18 & its Proof

    I am reading Karl R. Stromberg's book: "An Introduction to Classical Real Analysis". ... ... I am focused on Chapter 3: Limits and Continuity ... ... I need help in order to fully understand the proof of Theorem 3.18 on pages 98-99 ... ... Theorem 3.18 and its proof read as follows: In the...
  32. F

    Proton Structure: De Broglie Wavelength & Resolution

    Hi all. I'd personally consider the De Broglie wavelength λ=h/p, with p being the momentum of the electron beam. I get $$\lambda \simeq 0.6 \times 10^{-18} m $$ and since the radius of a quark is ## \leq 10^{-19} m ##, the proton structure can't be resolved. I'm quite sure there's something...
  33. Benjamin_harsh

    What does "an axis normal to the plane containing the structure" look like?

    How does " an axis normal to the plane containing the structure" look like?
  34. Ranku

    I Cosmological constant and structure formation

    How much impact does the presence of the cosmological constant have on the formation of structures in the universe? On a larger scale, is there less structure formation because of the presence of the cosmological constant?
  35. fresh_42

    Insights How to Write a Math Proof and Their Structure

    Continue reading...
  36. Z

    I Fine Structure Spectra: Understanding Electron Intrinsic Spin Effects

    I understand that the intrinsic spin of an electron causes discrete differences in energy for transitions, due to the interaction of the magnetic dipole moment of the electron. Also, that this in turn creates the fine structure spectra. But what I am currently struggling to picture is why this...
  37. Noah332

    Need help with statics problem -- Structure to hold 1300 pounds

    So given a force F that is at r1/2, distances y, r1,r2,and r3. What is x?
  38. X

    A Question about crystal structure of long chain fatty acids (XRD)

    Hello, we are studying potato periderm before/after digestion and dewaxing and native vs wounded. One of the techniques is XRD, hence my user name. Among other things we are trying to use XRD to determine the arrangement of fatty acids, esters, and other long-chain aliphatics that are present...
  39. K

    Structural mechanics: Distributed forces on a structure

    Problem Statement: What's your result of ##X_A##? I find mine is different from the standard answer. Relevant Equations: My answer for $$X_A =5 kN$$ Problem Statement: What's your result of ##X_A##? I find mine is different from the standard answer. Relevant Equations: My answer for $$X_A...
  40. D

    I The Shadow Of An Atom - False Colour Images Reveal Structure

    I've been adding some renderings I did of the M87 black hole on a different thread and was asked to elaborate on the source of this technique which was investigating images of the shadow of an atom. You can look up the original experiment on Google, as well as observe the final image. The...
  41. P

    I Free electron gas band structure?

    How can I see, by looking at a band structure if the substance in question can be viewed as a free electron gas (FEG) or not? What characterizes a FEG in a bandstructure plot? Thanks in advance!
  42. lpetrich

    A Structure of modulo-integer matrix group GL(r,Z(n))?

    Over in the thread The eight-queens chess puzzle and variations of it | Physics Forums I discovered that with a toroidal board, one with periodic boundary conditions, the amount of symmetries becomes surprisingly large (A group-based search for solutions of the n-queens problem - ScienceDirect)...
  43. P

    I Understanding Band Structure Diagrams

    Hi! I never really understood band structure diagrams. I think they represent the energy of an electron, with the given circumstances, at a k vector. Are the electrons only allowed to be on the lines here? Or can they also be in areas enclosed under/between certain lines? What are some...
  44. R

    Chemical structure vs excitation frequency (photons)

    Is there a text, or set of texts, on how to predict what frequency of photon is released when a particular molecule is brought to an excited state and then relaxes? So for example if you were to put, say, benzene into an electrical tube and excite it what frequency would be released and more...
  45. S

    Programs Meteorologists/atmospheric scientists - structure of the study

    I'm not sure if this is the correct thread, so please accept my apologies if I've posted in the wrong section. My question is for meteorologists and atmospheric scientists who did their undergraduate degree in different, but related fields, such as physics, chemistry, Earth science, etc. and...
  46. Teri

    I Hyperfine structure - Hamiltonian and bases

    Hi, could you please explain me, how to copmute the yellow parts? Thank you very much.
  47. N

    Lowest fine structure energy transitions

    Hi, I would like to know what atoms have the lowest fine-structure energy transitions with their wavelengths. Also I want to know what molecules have the lowest rotational energy transitions with their wavelengths. Is there a database where one can find them? Thank you
  48. L

    A Structure preserved by strong equivalence of metrics?

    Let ##d_1## and ##d_2## be two metrics on the same set ##X##. We say that ##d_1## and ##d_2## are equivalent if the identity map from ##(X,d_1)## to ##(X,d_2)## and its inverse are continuous. We say that they’re uniformly equivalent if the identity map and its inverse are uniformly...
  49. L

    Is cast iron a Body and Face Centered Cube structure?

    Homework Statement is cast irion body and face centenerd cube structure? wasnt quiet sure, i thought it was both because it can solidify different temperatures one of them Homework Equations mululpe different cast irons The Attempt at a Solution
  50. I

    I Center of inversion of cubic diamond structure?

    I'm having hard time finding the center of inversion of cubic diamond structure. At first I thought (2,2,2) would be the center of inversion, but (1,1,3), (3,3,3), (1,3,1), (3,1,1) (i.e. four atoms inside the cube) are not centrosymmetric about (2,2,2).
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